JP6881135B2 - Mold forging member manufacturing method and mold forging member manufacturing equipment - Google Patents

Description

The present invention relates to a method for manufacturing a mold forging member and a manufacturing facility used for a method for manufacturing a mold forging member. More specifically, the present invention relates to a crankshaft manufacturing method and manufacturing equipment used in the crankshaft manufacturing method.

The mold forging member is used in various fields. Mold forging members are, for example, crankshafts, front axles and connecting rods. Crankshafts are used in automobiles and ships. In recent years, as engines have become lighter and more powerful, crankshafts are required to have high strength and high toughness. Forged crankshafts manufactured by die forging have higher strength and toughness than cast crankshafts manufactured by casting. Therefore, the demand for forged crankshafts is increasing.

The forged crankshaft is formed by forging a material such as a billet using a mold having the shape of a crankshaft. In mold forging, excess material that exceeds the volume of the mold protrudes out of the mold as burrs. Burrs are removed after mold forging. The smaller the volume of burrs, the higher the yield.

In order to reduce the volume of burrs, the volume distribution to the material before mold forging has been studied so far. Volume distribution is performed, for example, by performing roll molding, bending, and the like. By roll forming and bending, the volume distribution of the material before die forging in the length direction is brought closer to the volume distribution in the length direction of the crankshaft. By this volume distribution, the volume of burrs after mold forging can be reduced and the yield can be increased.

Japanese Unexamined Patent Publication No. 2001-47177 (Patent Document 1) proposes the following techniques. The two opposing molds reduce the portion of the material corresponding to the front portion of the integrated crankshaft so that the thickness is 80-35% of the material thickness in the direction perpendicular to the axial direction of the material. It is described in Patent Document 1 that this makes it possible to increase the yield of the front portion without causing a dent on the end surface of the portion corresponding to the front portion of the integrated crankshaft.

International Publication No. 2014/016875 (Patent Document 2) proposes the following techniques. In Patent Document 2, the billet before die forging is installed and the cross-sectional area is expanded from the position corresponding to the crank arm portion at the beginning of the crankshaft to the position corresponding to the crank arm portion at the end. To mold. It is described in Patent Document 2 that this makes it possible to improve the yield over the entire area of the crankshaft, and it is also possible to integrate the cross-sectional size of the billet to be used into a smaller one.

Japanese Unexamined Patent Publication No. 2001-47177 International Publication No. 2014/016875 JP-A-59-4902

As in Patent Documents 1 and 2, many techniques for reducing the volume of burrs by volume distribution have been proposed. On the other hand, by making the outer diameter of the material the minimum size necessary for manufacturing the mold forging member, the volume of burrs can be reduced and the yield can be increased.

However, there are restrictions on the type of outer diameter of the billet that is the material of the mold forging member. Billets are usually manufactured using slab rolling. In slab rolling, a pair of horizontal roll sets (upper roll and lower roll) is used to roll the slabs to produce billets. Each upper and lower roll has a hole shape called a caliber. The outer diameter of the billet is determined according to this hole type. The number of hole types that a pair of horizontal rolls can have is limited. Therefore, there are restrictions on the type of outer diameter of the billet.

By using horizontal rolls having different hole shapes, it is possible to increase the types of outer diameters of billets. However, when manufacturing billets having a plurality of types of outer diameters, a plurality of horizontal roll sets having different hole shapes must be prepared. In addition, the horizontal roll set of the slabbing mill must be replaced to produce billets of the desired outer diameter. (Hereinafter, the replacement of the roll set is referred to as the roll rearrangement.) This roll rearrangement reduces the productivity. Therefore, with the conventional manufacturing method, it is difficult to manufacture a billet having an optimum outer diameter for the mold forging member while suppressing a decrease in productivity.

An object of the present invention is to provide a method for manufacturing a mold forged member and a manufacturing facility used for the method for manufacturing a mold forged member, which can improve the yield while suppressing a decrease in productivity.

In the method for manufacturing a mold forging member according to the present embodiment, a heating furnace, a tilt rolling mill including three tilt rolls, and a manufacturing facility including a mold forging machine are used in order from upstream to downstream. The manufacturing method includes a heating step, a diameter reduction rolling step, and a mold forging step. In the heating step, the billet is heated in a heating furnace. In the reduced diameter rolling step, the heated billet is reduced in diameter with an inclined rolling mill to adjust the outer diameter to a desired value. In the mold forging process, billets with adjusted outer diameters are forged with a mold forging machine.

The manufacturing equipment according to the present embodiment includes a heating furnace, a tilt rolling mill, and a mold forging machine. The heating furnace heats the billet. The billet includes a first end face, a second end face opposite the first end face, and a side surface between the first end face and the second end face. The tilt rolling mill is located downstream of the heating furnace. The tilt rolling mill is provided with three tilt rolls, and the billet is reduced in diameter to be adjusted to a desired outer diameter. The mold forging machine is located downstream of the inclined rolling mill. The mold forging machine is provided with a mold having a shape of a desired mold forging member, and a billet having an adjusted outer diameter is mold forged to obtain a desired shape of the mold forging member.

The method for manufacturing the mold forging member according to the present embodiment is a manufacturing method using the above-mentioned manufacturing equipment. By manufacturing the mold forging member using the above manufacturing equipment, it is possible to improve the yield while suppressing the decrease in productivity.

FIG. 1 is a diagram showing a crankshaft manufactured by die forging. FIG. 2 is a diagram showing after finishing punching in the case where a crankshaft is manufactured by die forging. FIG. 3 is a layout diagram of the manufacturing equipment for the die forging member according to the first embodiment. FIG. 4 is a perspective view of the inclined rolling mill as viewed from the outside. FIG. 5 is a front view of the inclined rolling mill as viewed from the entrance side. FIG. 6 is a side view of the inclined rolling mill. FIG. 7 is a partial cross-sectional view showing a cross section and a billet of the inclined roll at the line segment VII-VII in FIG. FIG. 8 is a layout diagram of the manufacturing equipment for the mold forging member according to the second embodiment, which is different from FIG. FIG. 9 is a side view of the stationary forging machine. FIG. 10 is a cross-sectional view of a stationary forging die including the central axis of the tapered hole. FIG. 11 is a front view of the stationary forging die seen from the axial direction of the billet at the time of stationary forging. FIG. 12 is a cross-sectional view of a stationary forging die including a central axis of a tapered hole according to another embodiment different from FIG. FIG. 13 is a cross-sectional view of a stationary forging die including a central axis of a tapered hole according to another embodiment different from FIGS. 10 and 12. FIG. 14 is a cross-sectional view of a stationary forging die including a central axis of a tapered hole according to another embodiment different from FIGS. 10, 12, and 13. FIG. 15 is a diagram showing an example of a billet that has been reduced in diameter and rolled by an inclined rolling mill having three inclined rolls without pre-installed forging. FIG. 16 is an enlarged view of the end portion of the forging die when the end face of the billet is greatly recessed and the mold is forged using the billet shown in FIG. FIG. 17 is an enlarged view of the end portion of the forging die when the end face of the billet is greatly recessed and the mold is forged using the billet shown in FIG. FIG. 18 is an enlarged view of the end portion of the forging die when the end face of the billet is greatly recessed and the mold is forged using the billet shown in FIG. FIG. 19 is a diagram showing billets that have been forged by using a stationary forging machine. FIG. 20 is a diagram showing billets after the billet shown in FIG. 19 which has been forged in advance is rolled in a reduced diameter by an inclined rolling mill having three inclined rolls. FIG. 21 is an enlarged view of the end portion of the die forging die when the die is forged using the billet shown in FIG. 20 in which the dent on the end face is suppressed. FIG. 22 is an enlarged view of the end portion of the die forging die when the die is forged using the billet shown in FIG. 20 in which the dent on the end face is suppressed. FIG. 23 is an enlarged view of the end portion of the die forging die when the die is forged using the billet shown in FIG. 20 in which the dent on the end face is suppressed. FIG. 24 is a side view of the stationary forging machine according to another embodiment, which is different from FIG. 9. FIG. 25 is a cross-sectional view of the central portion of the billet in the axial direction and the restraint tool as viewed from the axial direction of the billet during stationary forging. FIG. 26 is a cross-sectional view of the central portion of the billet in the axial direction and the restraint tool as viewed from the axial direction of the billet at the time of stationary forging according to another embodiment different from FIGS. 24 and 25. FIG. 27 is a cross-sectional view of the central portion of the billet in the axial direction and the restraint tool as viewed from the axial direction of the billet at the time of stationary forging according to another embodiment different from FIGS. 25 and 26. FIG. 28 is a cross-sectional view of the central portion of the billet in the axial direction and the restraint tool as seen from the axial direction of the billet during the stationary forging after the stationary forging. FIG. 29 is a layout diagram of a mold forging member manufacturing facility according to a third embodiment, which is different from FIGS. 3 and 8.

FIG. 1 is a diagram showing an example of a mold forging member manufactured by mold forging. FIG. 1 shows a forged crankshaft as an example. In FIG. 1, the crankshaft 1 includes a journal portion 10, a pin portion 11, a front portion 12, and a crank arm portion 13 that connects the journal portion 10 and the pin portion 11. For example, when the crankshaft 1 is manufactured by mold forging, the heated billet is forged using a mold having the shape of the crankshaft 1. The mold forging process may include roughing and finishing. FIG. 2 is a diagram showing after finishing punching in the case where the crankshaft 1 is manufactured by die forging. After finishing the finishing, the surplus material of the billet exceeding the volume of the mold protrudes out of the mold as burrs 2. The burr 2 is punched out and removed by a knife or the like. As a result, the crankshaft 1 is manufactured.

Conventionally, a method of reducing the volume of the burr 2 by volume distribution has been studied. On the other hand, by making the outer diameter of the material the minimum size necessary for manufacturing the mold forging member, the volume of burrs can be reduced and the yield can be increased.

As described above, the mold forging member includes various members such as a front axle and a connecting rod in addition to the crankshaft 1. Therefore, in order to make the outer diameter of the material the minimum necessary for manufacturing the mold forging member, it is necessary to manufacture a plurality of types of materials having an outer diameter suitable for each mold forging member.

However, as described above, there are restrictions on the types of outer diameters of billets produced by using bulk rolling. Further, in order to produce a billet having a desired outer diameter, the roll must be rearranged. This roll rearrangement reduces productivity. Therefore, with the conventional manufacturing method, it is difficult to manufacture a billet having an optimum outer diameter for the mold forging member while suppressing a decrease in productivity.

Therefore, the present inventors have studied a method for producing a billet having an optimum outer diameter for a mold forging member while suppressing a decrease in productivity. As a result, the following findings were obtained.

In an inclined rolling mill including three inclined rolls, the outer diameter of the billet after reduced diameter rolling can be widely adjusted by adjusting the crossing angle of the rolls described later. That is, if the billet is reduced in diameter by a tilt rolling mill including three tilt rolls, the billet can be adjusted to the minimum outer diameter necessary for manufacturing a desired die forging member.

Further, the inclined rolling mill including the three inclined rolls can increase the rolling reduction amount at one time as compared with the slabbing rolling mill. Therefore, even when a billet having a small outer diameter is required to manufacture the mold forging member, it is possible to manufacture a billet having the required outer diameter under one reduction.

That is, if a billet is manufactured using an inclined rolling mill including three inclined rolls, a billet having a small outer diameter is required even when it is necessary to finely adjust the outer diameter of the billet after reduced diameter rolling. Even in this case, a billet having a required outer diameter can be produced under one rolling.

In a slabbing mill, for example, when a billet having a small outer diameter is required, it may be necessary to reciprocate and roll the billet many times, and it may take time to manufacture the billet. On the other hand, in an inclined rolling mill including three inclined rolls, the amount of rolling down at one time is large. Therefore, for example, even when a billet having a small outer diameter is required, the time required for manufacturing the billet is short. As a result, the billet temperature is unlikely to drop.

Further, when an inclined rolling mill containing three inclined rolls is used, it is not necessary to rearrange the rolls in order to manufacture billets having a plurality of types of outer diameters as in the case of a bulk rolling mill. Therefore, the decrease in the productivity of the mold forging member is suppressed.

From the above, the present inventors can suppress a decrease in the productivity of the die forging member even if the diameter reduction rolling is performed by an inclined rolling mill including three inclined rolls even before the die forging. , It was found that the temperature of the billet does not easily decrease. Therefore, in the die forging member production line, by arranging an inclined rolling mill including three inclined rolls between the heating furnace and the die forging machine, it is possible to suppress a decrease in productivity in the die forging process while suppressing a decrease in productivity. We have reached this embodiment to improve the yield.

The method for manufacturing the die forging member according to the present embodiment completed based on the above findings is a manufacturing facility equipped with a heating furnace, an inclined rolling mill including three inclined rolls, and a die forging machine in order from upstream to downstream. Is used. The manufacturing method includes a heating step, a diameter reduction rolling step, and a mold forging step. In the heating step, the billet is heated in a heating furnace. In the reduced-diameter rolling step, the heated billet is reduced-diameter-rolled over the entire surface with an inclined rolling mill to adjust the outer diameter to a desired value. More specifically, a billet having an outer diameter larger than the desired outer diameter is rolled using a tilt rolling mill so that the outer diameter becomes smaller, and the outer diameter is adjusted to the desired outer diameter. In the mold forging process, billets with adjusted outer diameters are forged with a mold forging machine.

In the above-mentioned manufacturing method, the diameter reduction rolling step is carried out before the die forging step. In the reduced diameter rolling step, a tilting rolling mill containing three tilting rolls allows the billet to be adjusted to the minimum outer diameter required to produce the desired die forging member. Therefore, in the mold forging process, the volume of burrs is reduced and the yield is improved. Further, when an inclined rolling mill containing three inclined rolls is used, it is not necessary to rearrange the rolls in order to manufacture billets having a plurality of types of outer diameters as in the case of a bulk rolling mill. Therefore, the decrease in the productivity of the mold forging member is suppressed.

Preferably, the manufacturing equipment further comprises a stationary forging machine between the heating furnace and the tilt rolling mill. Preferably, the manufacturing method further comprises a stationary forging step after the heating step and before the diameter reduction rolling step. In the stationary forging process, a stationary forging machine is used to perform stationary forging on the billet, and the end portion of the billet is tapered.

Here, the tapered shape is a shape in which the width of the billet in the cross section including the central axis of the billet decreases continuously or intermittently toward the end face of the billet, or from the first and second billet facing surfaces described later. The widths of the first and second inner peripheral surfaces in the cross section of the first and second stationary forging dies, including the central axes of the first and second tapered holes, are continuous or toward the first and second back surfaces. A shape that decreases intermittently. The rate at which the width decreases may or may not be constant. For example, the width of the billet or the width of the first and second inner peripheral surfaces is discontinuous toward the end face of the billet or from the facing surfaces of the first and second billets described later toward the first and second back surfaces. Decreasing shapes (eg stepped) are also included in the tapered shape. The tapered shape may be, for example, a cone in which the end of the billet is convex.

In the reduced diameter rolling step, the larger the rolling reduction amount of the billet, the more the billet surface layer portion is stretched at the billet end portion than the billet central portion. Therefore, the billet end is dented. If the end face of the billet is greatly recessed, the concave end face is bent as the forging progresses, and finally overlaps. As a result, forging defects are formed in the overlapping portions of the materials. The forging defect in this case is called a flaw. In other words, a curled up defect is a forging defect created by bending and overlapping a part of the material in the die in the die forging. By pre-installing and forging the billet end portion, the dent of the billet end portion in the subsequent diameter reduction rolling process is suppressed. If the dent at the end of the billet is suppressed, the forging defect (rolling defect) caused by the dent is suppressed in the mold forging process. Therefore, even if the amount of reduction of the billet in the reduced diameter rolling process is large, forging defects of the die forging member can be suppressed.

Preferably, the manufacturing method further comprises a sorting step after the heating step and before the stationary forging step. In the sorting process, billets to be forged are supplied to the forging machine, and billets not to be forged are supplied to the inclined rolling mill. In the stationary forging process, the billet to be stationary forged is stationary forged. In the reduced-diameter rolling process, the billets after the set-in forging process and the billets not subject to the set-in forging are reduced-diameter rolled.

Whether or not stationary forging is necessary depends on the steel type of the billet charged into the heating furnace, the outer diameter, the amount of rolling in the inclined rolling mill, and the like. By providing the sorting process, only billets that require forging can be forged. This increases the productivity of the die forging member.

In the distribution step, the billets to be forged may be supplied to the forging machine and the billets not to be forged may be supplied to the inclined rolling mill according to the rolling reduction amount of the billets in the reduced diameter rolling step. ..

The larger the reduction amount in the reduced diameter rolling process, the larger the dent on the end face of the billet. On the other hand, when the rolling reduction amount in the reduced diameter rolling process is small, the dent on the end face of the billet is small. In this case, the influence at the time of mold forging is small. Therefore, the billet supply destination (installed forging machine or inclined rolling machine) may be determined based on the rolling reduction amount in the reduced diameter rolling process.

The die forging member in the above method for manufacturing a die forging member may be a crankshaft.

The manufacturing equipment according to the present embodiment includes a heating furnace, a tilt rolling mill, and a mold forging machine. The heating furnace heats the billet. The billet includes a first end face, a second end face opposite the first end face, and a side surface between the first end face and the second end face. The tilt rolling mill is located downstream of the heating furnace. The tilt rolling mill is provided with three tilt rolls, and the billet is reduced in diameter to be adjusted to a desired outer diameter. The mold forging machine is located downstream of the inclined rolling mill. The mold forging machine is provided with a mold having a shape of a desired mold forging member, and a billet having an adjusted outer diameter is mold forged to obtain a desired shape of the mold forging member.

The above-mentioned manufacturing equipment is equipped with a tilt rolling mill upstream of the die forging machine. The tilt rolling mill adjusts the billet to the minimum outer diameter required to produce the desired die forging member. As a result, in the mold forging process, the volume of burrs is reduced and the yield is improved. Further, the inclined rolling mill of the present embodiment does not require roll rearrangement to manufacture billets having a plurality of types of outer diameters. Therefore, the decrease in the productivity of the mold forging member is suppressed.

Preferably, the manufacturing equipment is further equipped with a stationary forging machine. The stationary forging machine is arranged between the heating furnace and the inclined rolling mill. The stationary forging machine includes a first stationary forging die, a second stationary forging die, and a stationary drive mechanism. The first stationary forging die includes a first billet facing surface and a first back surface. The first billet facing surface includes a first tapered hole facing the first end surface of the billet during stationary forging. The first back surface is arranged on the side opposite to the first billet facing surface. The second stationary forging die includes a second billet facing surface and a second back surface. The second billet facing surface includes a second tapered hole facing the second end surface of the billet during stationary forging. The second back surface is arranged on the side opposite to the second billet facing surface. The stationary drive mechanism can drive the first stationary forging die in the axial direction of the billet at the time of stationary forging. The first stationary forging die and the second stationary forging die are arranged in the horizontal direction. The first tapered hole includes a first inner peripheral surface. The width of the first inner peripheral surface in the cross section including the central axis of the first tapered hole of the first stationary forging die decreases from the first billet facing surface toward the first back surface. The second tapered hole includes a second inner peripheral surface. The width of the second inner peripheral surface in the cross section including the central axis of the second tapered hole of the second stationary forging die decreases from the second billet facing surface toward the second back surface.

Here, the fact that the first stationary forging die and the second stationary forging die are arranged in the horizontal direction means that the first stationary forging die and the second stationary forging die are perpendicular to the gravity. Not limited to the case where they are arranged in the intersecting direction, when the first set-in forging die and the second set-in forging die are arranged so as to be offset within a range of 30 ° or less from the direction at which they intersect at right angles to gravity. including.

Here, the central axes of the first and second tapered holes refer to the centers of gravity of the first and second inner peripheral surfaces in a cross section orthogonal to the axial direction of the billets during installation forging, and face the first and second billets. It is a line segment connecting from the surface toward the first and second back surfaces.

In this case, the billet end is preliminarily formed into a tapered shape by a stationary forging machine arranged upstream of the inclined rolling mill. As a result, the dent at the billet end in the subsequent reduced diameter rolling step is suppressed. If the dent at the end of the billet is suppressed, forging defects are suppressed in the mold forging process.

Preferably, the stationary forging machine in the manufacturing equipment further includes first and second restraint tools and first and second restraint tool support mechanisms. The first restraint tool includes a first restraint surface that is arranged around the axis of the axially central portion of the billet during stationary forging and is in contact with the side surface of the billet. The second restraint tool is arranged on the opposite side of the first restraint tool across the billet at the time of stationary forging and around the axial center portion of the billet at the time of stationary forging, and is a side surface of the billet. Includes a second restraint surface that comes into contact with. The first restraint tool support mechanism is arranged on the side opposite to the first restraint surface of the first restraint tool and supports the first restraint tool. The second restraint tool support mechanism is arranged on the side opposite to the second restraint surface of the second restraint tool and supports the second restraint tool.

Here, the axially central portion of the billet means a portion other than the portion in the axial direction of the billet from the end of the billet to the same distance as the diameter of the billet.

In this case, the first and second restraint tools are arranged around the axial center of the billet during forging, and restrain the side surface of the billet. As a result, it is possible to prevent the billet from buckling during stationary forging.

Preferably, the stationary forging machine further comprises first and second elastic members. The first elastic member is arranged between the first restraint tool and the first restraint tool support mechanism. The second elastic member is arranged between the second restraint tool and the second restraint tool support mechanism.

The elastic member here means a member that is distorted and deformed when an external force is applied, but returns to its original shape when the external force is removed. The elastic member is, for example, a spring, rubber, or the like.

In the stationary forging process, the billet is installed and forged in the axial direction of the billet. Therefore, if the stationary forging is carried out, the radius of the billet increases. The elastic member arranged between the restraint tool and the restraint tool support mechanism contracts under the radial outward pressure of the billet of the restraint tool as the radius of the billet increases. Therefore, the billet of the restraint tool is allowed to move in the radial direction. As a result, the diameter of the billet after the installation forging is not limited, and billets of a plurality of sizes can be manufactured. Further, the contracted elastic member allows the restraint tool to maintain a state of restraining the side surface of the billet even when the diameter of the billet is increased. As a result, even when the billet of the restraint tool is allowed to move in the radial direction, it is possible to suppress the occurrence of buckling of the billet during stationary forging.

Preferably, the manufacturing facility further comprises a sorting mechanism. The sorting mechanism supplies the billets to be forged to the stationary forging machine and the billets not to be forged to the inclined rolling mill. The stationary forging machine installs and forges the billet to be forged. The tilt rolling mill reduces the diameter of the billet after the set-in forging and the billet that is not subject to the set-in forging.

The manufacturing equipment is provided with a sorting mechanism. Therefore, only billets that require stationary forging can be forged. Therefore, by using the above manufacturing equipment, the productivity of the mold forging member is increased.

The sorting mechanism may supply the billet to be forged to the stationary forging machine and the billet not to be forged to the inclined rolling mill according to the rolling reduction amount of the billet in the inclined rolling mill. ..

The mold forging member to be manufactured by the manufacturing equipment may be a crankshaft.

Hereinafter, the manufacturing method and manufacturing equipment of the mold forging member of the present embodiment will be described in detail. The same or corresponding parts in the drawings are designated by the same reference numerals and the description thereof will not be repeated.

[First Embodiment]
[production equipment]
FIG. 3 is a layout diagram of the manufacturing equipment for the die forging member according to the first embodiment. With reference to FIG. 3, the manufacturing equipment includes a heating furnace 3, a tilt rolling mill 4, and a mold forging machine 5. A transfer mechanism 6 is arranged between the heating furnace 3 and the inclined rolling mill 4, and between the inclined rolling mill 4 and the mold forging machine 5. The transport mechanism 6 transports the billets extracted from the heating furnace 3 to the tilt rolling mill 4, and the billets that have been reduced in diameter and rolled by the tilt rolling mill 4 to the mold forging machine 5.

In the manufacturing equipment for the die forging member shown in FIG. 3, the heating furnace 3, the inclined rolling mill 4, and the die forging machine 5 are linearly arranged. However, the arrangement of each device of the die forging member manufacturing equipment does not have to be linear. The arrangement of each device of the die forging member manufacturing equipment may be arranged in the order of the heating furnace 3, the inclined rolling mill 4, and the die forging machine 5 from upstream to downstream.

[heating furnace]
The heating furnace 3 heats the billet to a predetermined temperature. The billet is, for example, a round billet manufactured by a normal slabbing rolling process. The cross section of the billet (cross section perpendicular to the axial direction) is preferably circular. However, the cross section of the billet may be a polygon such as a hexagon or an octagon, or may be an ellipse.

The type of the heating furnace 3 is not particularly limited as long as the billet can be heated to a predetermined temperature. The heating furnace 3 may be, for example, a walking beam type continuous heating furnace or a rotary Haworth type continuous heating furnace.

[Inclination rolling mill]
The tilt rolling mill 4 is arranged downstream of the heating furnace 3. FIG. 4 is a perspective view of the inclined rolling mill 4 as viewed from the outside. With reference to FIG. 4, the tilt rolling mill 4 includes three tilt rolls 40. The three inclined rolls 40 are arranged at equal intervals around the pass line L. FIG. 5 is a front view of the inclined rolling mill 4 as viewed from the entrance side. In FIGS. 4 and 5, three inclined rolls 40 are arranged at equal intervals (every 120 °) around the pass line L.

The three tilt rolls 40 are attached to a motor (not shown). The three inclined rolls 40 are rotated in the same direction by a motor to reduce the diameter of the billet and adjust it to a desired outer diameter.

FIG. 6 is a side view of the inclined rolling mill 4. FIG. 7 is a partial cross-sectional view showing a cross section of the inclined roll 40 and a billet 7 at the line segment VII-VII in FIG. With reference to FIG. 6, each inclined roll 40 is arranged at an angle α1 ° with respect to the pass line L. Further, referring to FIG. 7, each inclined roll 40 is arranged so as to intersect the pass line L at an angle β1 °. The billet 7 is reduced in diameter and rolled while spirally rotating according to the inclination angle α1 and the crossover angle β1, and is adjusted to a desired outer diameter.

By adjusting the shortest distance D between each inclined roll 40 and the pass line L shown in FIG. 7, the inclined rolling mill 4 can freely adjust the outer diameter of the billet 7. Therefore, in the inclined rolling mill 4, it is not necessary to carry out roll rearrangement according to the outer diameter of the billet 7 as in the bulk rolling mill. That is, the inclined rolling mill 4 can adjust the billet 7 to various outer diameters without rearranging the rolls.

In FIGS. 4 to 7, the outer diameter of each inclined roll 40 increases from the entrance side to the exit side of the inclined rolling mill 4. However, the shape of each inclined roll 40 is not limited to this. For example, a so-called barrel-shaped roll having the largest outer diameter near the center of the inclined roll 40 in the longitudinal direction may be used.

[Mold forging machine]
The mold forging machine 5 is arranged downstream of the inclined rolling mill 4. The mold forging machine 5 is provided with a mold having a desired mold forging member (for example, crankshaft 1) shape, and a billet 7 having an adjusted outer diameter is forged to form a desired mold forging member (for example, crankshaft 1). Make it into a shape. As the mold forging machine 5, a so-called mechanical press or a hydraulic press can be used. The mold used for the mold forging machine 5 is, for example, a pair of upper and lower dies. The mold used for the mold forging machine 5 is prepared according to the type and size of the mold forging member (for example, crankshaft 1, front axle, connecting rod, etc.) to be manufactured.

[Manufacturing method of mold forging members]
The method for manufacturing a mold forging member using the above-mentioned manufacturing equipment includes a heating step, a diameter reduction rolling step, and a mold forging step. In the following embodiment, the crankshaft 1 will be described as an example of the forged mold product. However, the forged product is not limited to the crankshaft 1. The mold forged product is not particularly limited in shape and use as long as it is a member manufactured by hot forging using a mold.

[Heating process]
In the heating step, the billet 7 cut to a predetermined length in advance is charged into the heating furnace 3 and heated. The heating time and heating temperature can be appropriately set according to the steel type, size, shape of the die forging member, and the like of the billet 7.

[Diameter rolling process]
In the reduced diameter rolling step, first, the heated billet 7 is extracted from the heating furnace 3. Then, the billet 7 is rolled in a reduced diameter over the entire surface by an inclined rolling mill 4 including three inclined rolls 40 to adjust the outer diameter to a desired value.

As described above, the inclined rolling mill 4 can adjust the billet 7 to various outer diameters by adjusting the shortest distance D between each inclined roll 40 and the pass line L without rearranging the rolls. In the case of the conventional slabbing mill, there is a limit to the type of outer diameter of the billet 7 that can be manufactured. Therefore, for example, a billet 7 having an outer diameter larger than the minimum outer diameter necessary for manufacturing the crankshaft 1 is used. In this case, the volume of the burr 2 increases and the yield decreases. In the present embodiment, the outer diameter of the billet 7 can be freely adjusted by the inclined rolling mill 4. Therefore, the billet 7 can be adjusted to the minimum outer diameter necessary for manufacturing, for example, the crankshaft 1, the volume of the burr 2 is reduced, and the yield is improved.

Billets 7 having various outer diameters can also be manufactured by a conventional slabbing mill. However, in the case of conventional slabbing mills, roll rearrangement must be carried out frequently in order to produce billets 7 having various outer diameters. In this case, the productivity of the mold forging member decreases. In the inclined rolling mill 4, the outer diameter of the billet 7 can be freely adjusted without rearranging the rolls, so that the productivity of the die forging member is increased.

In the conventional slabbing rolling mill, for example, when a billet 7 having a small outer diameter is required, it may be necessary to reciprocate and roll the billet 7 many times, and it may take time to manufacture the billet 7. On the other hand, in the tilt rolling mill 4 including the three tilt rolls 40, the amount of rolling down at one time is large. Therefore, for example, even when a billet 7 having a small outer diameter is required, the time required for manufacturing the billet 7 is short. That is, a billet 7 having an outer diameter of a desired size can be produced in a short time under one compression. If the billet 7 can be manufactured in a short time, even if the tilt rolling mill 4 including the three tilt rolls 40 is arranged between the heating furnace 3 and the mold forging machine 5 and the outer diameter of the billet 7 is adjusted, the billet 7 can be manufactured. The temperature does not drop easily.

[Mold forging process]
In the mold forging step, the billet 7 having an adjusted outer diameter is forged by the mold forging machine 5. In the die forging step, the billet 7 is arranged and pressed in a die (for example, a pair of dies) having a desired die forging member shape. As a result, the billet 7 is deformed into a desired shape forged member. The shape of the mold is, for example, the shape of the crankshaft 1. The mold forging process may include roughing and finishing. The shape of the mold may be the shape of another mold forging member such as a front axle and a connecting rod.

As described above, the billet 7 used for die forging is adjusted to the minimum outer diameter necessary for manufacturing the die forging member (for example, the crankshaft 1) in the diameter reduction rolling process. Therefore, the volume of the burr 2 in the mold forging process is small. Therefore, the yield is improved.

By punching and removing the burr 2 after the mold forging step, the mold forging member of the present embodiment can be manufactured.

[Second Embodiment]
In the first embodiment described above, the die forging member manufacturing equipment includes a heating furnace 3, an inclined rolling mill 4, and a die forging machine 5. The manufacturing equipment is further preferably equipped with a stationary forging machine.

FIG. 8 is a layout diagram of the manufacturing equipment for the mold forging member according to the second embodiment, which is different from FIG. With reference to FIG. 8, the manufacturing facility includes a stationary forging machine 8 in addition to a heating furnace 3, a tilt rolling mill 4, and a mold forging machine 5. The stationary forging machine 8 is arranged between the heating furnace 3 and the inclined rolling mill 4. A transport mechanism 6 is arranged between the devices 3 to 5 and 8.

[Installation forging machine]
FIG. 9 is a side view of the stationary forging machine 8. In FIG. 9, a part of the stationary forging machine 8 is shown in a cross-sectional view (hatched portion). With reference to FIG. 9, the stationary forging machine 8 includes a first stationary forging die 81, a second stationary forging die 82, and a stationary drive mechanism 83. With reference to FIG. 9, the first set-in forging die 81 and the second set-in forging die 82 are arranged in the horizontal direction. The first set-in forging die 81 and the second set-in forging die 82 are arranged so that the tapered holes 810 and 820, which will be described later, face each other. The first stationary forging die 81 and the second stationary forging die 82 are arranged on an extension line of the central axis of the billet 7 at the time of stationary forging. At the time of stationary forging, the billet 7 is arranged between the first stationary forging die 81 and the second stationary forging die 82.

Here, the fact that the first stationary forging die 81 and the second stationary forging die 82 are arranged in the horizontal direction means that the first stationary forging die 81 and the second stationary forging die 82 are arranged in the horizontal direction. The first stationary forging die 81 and the second stationary forging die 82 are displaced within a range of 30 ° or less from the direction perpendicular to the gravity, not limited to the case where they are arranged in the direction perpendicular to the gravity. Including the case where they are arranged.

The stationary forging machine 8 performs stationary forging at both ends of the billet 7. The billet 7 includes a first end face 70, a second end face 71 opposite to the first end face 70, and a side surface 72 between the first end face 70 and the second end face 71.

[1st and 2nd stationary forging dies]
FIG. 10 is a cross-sectional view of the first and second stationary forging dies 81 and 82 including the central axes of the first and second tapered holes 810 and 820. With reference to FIG. 10, the first stationary forging die 81 includes a first billet facing surface 811 and a first back surface 812. The first billet facing surface 811 includes a first tapered hole 810 facing the first end surface 70 of the billet 7 during installation forging. The first back surface 812 is arranged on the side opposite to the first billet facing surface 811. The second stationary forging die 82 includes a second billet facing surface 821 and a second back surface 822. The second billet facing surface 821 includes a second tapered hole 820 facing the second end surface 71 of the billet 7 during installation forging. The second back surface 822 is arranged on the side opposite to the second billet facing surface 821.

[About the taper holes of the 1st and 2nd stationary forging dies]
With reference to FIG. 10, the first tapered hole 810 includes a first inner peripheral surface 813. The width of the first inner peripheral surface 813 in the cross section (for example, FIG. 10) of the first stationary forging die 81 including the central axis of the first tapered hole 810 is from the first billet facing surface 811 to the first back surface 812. Decrease towards. The second tapered hole 820 includes a second inner peripheral surface 823. The width of the second inner peripheral surface 823 in the cross section (for example, FIG. 10) of the second stationary forging die 82 including the central axis of the second tapered hole 820 is from the second billet facing surface 821 to the second back surface 822. Decrease towards.

Here, the central axes of the first and second tapered holes 810 and 820 are the centers of gravity of the first and second inner peripheral surfaces 813 and 823 in the cross section orthogonal to the axial direction of the billet 7 at the time of forging. It is a line segment connecting the first and second billet facing surfaces 811 and 821 toward the first and second back surfaces 812 and 822.

FIG. 11 is a front view of the first and second stationary forging dies 81 and 82 viewed from the axial direction of the billet 7 at the time of stationary forging. With reference to FIG. 11, the first tapered hole 810 has a first inner peripheral surface 813 whose cross-sectional shape orthogonal to the axial direction of the billet 7 at the time of stationary forging is, for example, circular. The second tapered hole 820 has a second inner peripheral surface 823 whose cross-sectional shape orthogonal to the axial direction of the billet 7 at the time of stationary forging is, for example, circular. In FIG. 11, the cross-sectional shapes of the first and second inner peripheral surfaces 813 and 823 are circular. However, the shape of the cross section orthogonal to the axial direction of the billet 7 at the time of stationary forging of the first and second inner peripheral surfaces 813 and 823 is not limited to a circular shape. The shape of the cross section of the first and second inner peripheral surfaces 813, 823 is an arbitrary two points on the first and second inner peripheral surfaces 813, 823 in the cross section orthogonal to the axial direction of the billet 7 at the time of stationary forging. The ratio of the length of the line segment having the maximum length (for example, the major axis or the diameter) to the length of the line segment having the minimum length (for example, the minor axis or the diameter) is 20%. Including cases where they differ within the following range. The shape of the cross section of the first and second inner peripheral surfaces 813 and 823 at the time of stationary forging and orthogonal to the axial direction of the billet 7 may be, for example, an ellipse or a polygon.

As described above, the tapered shape is a shape in which the width of the billet 7 in the cross section including the central axis of the billet 7 decreases continuously or intermittently toward the first and second end faces 70 and 71 of the billet 7. First and second stationary forgings, including the central axes of the first and second tapered holes 810, 820, from the first and second billet facing surfaces 811, 821 to the first and second back surfaces 812, 822. A shape in which the widths of the first and second inner peripheral surfaces 813 and 823 in the cross sections of the molds 81 and 82 decrease continuously or intermittently. The rate at which the width decreases may or may not be constant. For example, the width of the billet 7 or toward the first and second end faces 70, 71 of the billet 7, or from the first and second billet facing surfaces 811, 821 to the first and second back surfaces 812, 822. A shape in which the widths of the first and second inner peripheral surfaces 813 and 823 are discontinuously reduced (for example, a stepped shape) is also included in the tapered shape. The tapered shape may be, for example, a cone in which the end of the billet 7 is convex.

The first billet facing surface 811 corresponds to the second billet facing surface 821, the first back surface 812 corresponds to the second back surface 822, and the first inner peripheral surface 813 corresponds to the second inner peripheral surface 823. Therefore, in the following description, each configuration of the first tapered hole 810 will be described as a substitute for the description of each configuration of the second tapered hole 820.

With reference to FIG. 10, the width of the first inner peripheral surface 813 decreases from the first billet facing surface 811 toward the first back surface 812. In the cross section including the central axis of the first tapered hole 810 (FIG. 10), the first inner peripheral surface 813 is a straight line, and the area of the first inner peripheral surface 813 is from the first billet facing surface 811 to the first back surface 812. And decrease continuously.

In FIG. 10, the first tapered hole 810 penetrates from the first billet facing surface 811 to the first back surface 812. However, the first tapered hole 810 does not have to penetrate from the first billet facing surface 811 to the first back surface 812.

FIG. 12 is a cross-sectional view of the first and second stationary forging dies 81, 82, including the central axes of the first and second tapered holes 810, 820, according to another embodiment different from FIG. With reference to FIG. 12, the first stationary forging die 81 includes a hole bottom 814 of the first tapered hole 810. With reference to FIG. 12, the second stationary forging die 82 includes a hole bottom 824 of the second tapered hole 820. As shown in FIG. 12, the first and second tapered holes 810, 820 do not penetrate from the first or second billet facing surface 811 or 821 to the first or second back surface 812 or 822, and the hole bottom 814 or 824 does not penetrate. May be provided.

In the cross section (FIGS. 10 and 12) including the central axis of the first tapered hole 810, the first inner peripheral surface 813 was a straight line. However, the first inner peripheral surface 813 in the cross section (FIGS. 10 and 12) including the central axis of the first tapered hole 810 does not have to be a straight line.

FIG. 13 is a cross-sectional view of the first and second stationary forging dies 81, 82, including the central axes of the first and second tapered holes 810, 820, according to another embodiment different from FIGS. 10 and 12. Is. In FIG. 13, the first inner peripheral surface 813 is not a straight line but is bent. The width of the first inner peripheral surface 813 continuously decreases from the first billet facing surface 811 toward the first back surface 812, but does not decrease thereafter and becomes constant.

FIG. 14 shows first and second stationary forging dies 81, 82 including the central axes of the first and second tapered holes 810, 820 according to other embodiments different from FIGS. 10, 12, and 13. It is a cross-sectional view of. In FIG. 14, the first inner peripheral surface 813 is not a straight line, but is curved toward the outside of the first tapered hole 810.

The shape of the first tapered hole 810 is not limited to FIGS. 10 to 14. The shape of the first tapered hole 810 may be, for example, the first inner peripheral surface 813 may be curved inward of the first tapered hole 810, or the first inner peripheral surface 813 may be stepped. Further, the dents of the first and second end faces 70 and 71 of the billet 7 after diameter reduction rolling include the central axis of the first tapered hole 810 as seen from the direction orthogonal to the axial direction of the billet 7, depending on the degree of denting. , The inclination of the first inner peripheral surface 813 in the cross section of the first and second stationary forging dies 81 and 82 may be increased. The shape of the first tapered hole 810 can be appropriately adjusted within the range in which the central portion of the billet 7 becomes convex at the end portion of the billet 7 after the installation forging.

The shape of the second taper hole 820 included in the second stationary forging die 82 may be the same as or different from that of the first taper hole 810. When the first tapered hole 810 and the second tapered hole 820 have the same shape, the load applied to the first end surface 70 and the second end surface 71 of the billet 7 is the same. Therefore, the stress due to forging can be uniformly applied to the entire billet 7. On the other hand, for example, when the degree of dent is different between the first end surface 70 and the second end surface 71 of the billet 7 after diameter reduction rolling, the shape of the first taper hole 810 and the shape of the second taper hole 820 are changed. You may.

At the time of stationary forging, the first end surface 70 of the billet 7 is deformed along the shape of the first tapered hole 810 and formed into the shape of the first tapered hole 810. The second end surface 71 of the billet 7 is deformed along the shape of the second tapered hole 820, and is formed into the shape of the second tapered hole 820. Therefore, when the billet 7 is stationary forged using the first and second stationary forging dies 81 and 82, the area of the first and second end faces 70 and 71 of the billet 7 after the stationary forging is the billet. It is smaller than the cross-sectional area of the other part of 7. Then, the cross-sectional area of the end portion of the billet 7 becomes smaller toward the first or second end surface 70 or 71. Further, the shape of the end portion of the billet 7 after the installation forging is a shape (tapered shape) having the same inclination as the first or second inner peripheral surface 813 or 823.

If the end of the billet 7 is tapered by stationary forging using the stationary forging machine 8, even if the billet 7 is subsequently reduced in diameter by the inclined rolling mill 4, the billet 7 after the reduced diameter is rolled. The dents of the 1st and 2nd end faces 70 and 71 are suppressed.

FIG. 15 is a diagram showing an example of a billet 7 that has been reduced in diameter and rolled by an inclined rolling mill 4 having three inclined rolls 40 without pre-installed forging. With reference to FIG. 15, the first and second end faces 70, 71 of the billet 7 are greatly recessed. 16 to 18 show an enlargement of the ends of the forging dies 81 and 82 when the first and second end faces 70 and 71 of the billet 7 are greatly recessed and the forging is performed using the billet 7 shown in FIG. It is a figure. With reference to FIGS. 16 to 18, when mold forging is performed using billets 7 in which the first and second end faces 70 and 71 are greatly recessed, the first and first mold forging progresses to FIGS. 16 to 18. The two end faces 70 and 71 may bend and eventually overlap. This may cause forging defects called curled up flaws.

FIG. 19 is a diagram showing a billet 7 that has been forged by using a stationary forging machine 8. FIG. 20 is a diagram showing a billet 7 after the billet 7 shown in FIG. 19 which has been forged in advance is rolled in a reduced diameter by an inclined rolling mill 4 having three inclined rolls 40. 21 to 23 show a die forging die when the die forging is performed using the billet 7 shown in FIG. 20 which is diameter-reduced and rolled by the inclined rolling mill 4 after being forged by the stationary forging machine 8. It is an enlarged view of an end part. With reference to FIGS. 21 to 23, at the end portion of the billet 7, the central portion of the billet 7 has a convex tapered shape at the end portion of the billet 7 before the diameter reduction rolling. Therefore, even if the surface layer portion of the billet 7 is stretched from the central portion of the billet 7 by the reduced diameter rolling, as shown in FIG. 20, the first and second end faces 70 and 71 of the billet 7 after the reduced diameter rolling are recessed. Is suppressed. If the billet 7 in which the dents of the first and second end faces 70 and 71 are suppressed is forged with reference to FIGS. 21 to 23, even if the die forging proceeds to FIGS. 21 to 23, the first and second ends are formed. Bending of the two end faces 70 and 71 is suppressed. As a result, the occurrence of forging defects (blurring defects) can be suppressed.

[Installation drive mechanism]
The stationary drive mechanism 83 can drive the first stationary forging die 81 in the axial direction of the billet 7 at the time of stationary forging. With reference to FIG. 9, at the time of stationary forging, the stationary drive mechanism 83 drives the first stationary forging die 81 in the direction indicated by the arrow in the drawing. Then, the first set-in forging die 81 is relatively close to the second set-in forging die 82. As a result, the end portion of the billet 7 is forged by installation.

In FIG. 9, the stationary drive mechanism 83 drives the first stationary forging die 81. However, the stationary drive mechanism 83 may drive the second stationary forging die 82 instead of the first stationary forging die 81. The stationary drive mechanism 83 may further drive the first and second stationary forging dies 81 and 82 so as to be close to each other.

In FIG. 9, the stationary forging machine 8 also includes a die holder 84 for fixing the first and second stationary forging dies 81 and 82, and a guide post 85 for moving the die holder 84 on a constant axis. .. However, other configurations of the stationary forging machine 8 are not limited to this. The first and second stationary forging dies 81 and 82 need only be arranged on the extension line of the central axis of the billet 7 at the time of stationary forging, and the other configuration of the stationary forging machine 8 is a so-called C frame or , It may be an integrated straight side frame.

In FIG. 9, the stationary forging machine 8 further includes a support mechanism 86 that supports the billet 7. In FIG. 9, the support mechanism 86 is a support pedestal that supports the billet 7 from below. However, the support mechanism 86 is not limited to the configuration shown in FIG. The support mechanism 86 is, for example, a robot arm, and may be a mechanism for gripping a part of the billet 7. The support mechanism 86 may also be suspended by a chain or the like. The configuration of the support mechanism 86 is not particularly limited as long as it can support the billet 7 until the installation forging is started. Further, the support mechanism 86 may move as the billet 7 contracts in the axial length due to the stationary forging.

FIG. 24 is a side view of the stationary forging machine 8 according to another embodiment, which is different from FIG. 9. In FIG. 24, a part of the stationary forging machine 8 is shown in a cross-sectional view (hatched portion). With reference to FIG. 24, the stationary forging machine 8 includes the first stationary forging die 81, the second stationary forging die 82, and the stationary drive mechanism 83, as well as the first and second restraint tools 91 and 92. , The first and second restraint tool support mechanisms 93 and 94, and the first and second elastic members 95 and 96 are newly provided.

The first restraint tool 91 is arranged around the axis of the central portion in the axial direction of the billet 7 at the time of stationary forging. The second restraint tool 92 is arranged on the opposite side of the first restraint tool 91 with the billet 7 sandwiched between them at the time of stationary forging, and around the axis of the central portion of the billet 7 at the time of stationary forging. To.

[First and second restraint tools]
FIG. 25 shows a case where the stationary forging machine 8 is provided with the first and second restraint tools 91 and 92, and the central portion in the axial direction of the billet 7 and the first and first and first billet 7 viewed from the axial direction of the billet 7 during the stationary forging. 2 is a cross-sectional view of the restraint tools 91 and 92 of 2. With reference to FIG. 25, the first and second restraint tools 91, 92 include first and second restraint surfaces 910 and 920 that come into contact with the side surface 72 of the billet 7.

When the billet 7 is installed and forged, the billet 7 may buckle. The first and second restraint tools 91 and 92 are arranged around the axial central portion of the billet 7 and restrain the side surface 72 of the billet 7. As a result, buckling of the billet 7 at the time of stationary forging can be suppressed.

In FIGS. 24 and 25, the first restraint tool 91 is arranged above the billet 7, and the second restraint tool 92 is arranged below the billet 7. However, the arrangement of the first and second restraint tools 91 and 92 may be reversed, and the first and second restraint tools 91 and 92 may not be arranged in the vertical direction. The first and second restraint tools 91 and 92 may be arranged so as to face each other with the billet 7 interposed therebetween.

FIG. 26 shows the axial central portion of the billet 7 and the first and second restraint tools 91 and 92 as viewed from the axial direction of the billet 7 during installation forging according to another embodiment different from those of FIGS. 24 and 25. It is a cross-sectional view of. With reference to FIG. 26, the first and second restraint tools 91, 92 are arranged in the horizontal direction. The arrangement directions of the first and second restraint tools 91 and 92 are not limited to FIGS. 24 to 26. The first and second restraint tools 91 and 92 may be arranged in a straight line with the billet 7 in between, and may be tilted by 0 to 45 ° with respect to the vertical direction, for example.

[Cross-sectional shape of first and second restraint tools]
Preferably, as shown in FIGS. 25 and 26, the shape of the cross section of the first and second restraint surfaces 910 and 920 as viewed from the axial direction at the time of stationary forging is arched. If the cross-sectional shape of the first and second restraint surfaces 910 and 920 is arcuate, the contact area between the billet 7 and the first and second restraint surfaces 910 and 920 at the time of forging can be increased. Therefore, at the time of stationary forging, the first and second restraint surfaces 910 and 920 tend to restrain the billet 7 while maintaining the shape of the billet 7. Therefore, the buckling of the billet 7 can be suppressed more efficiently. Here, the bow shape means a state in which a part or the whole is bent in an arc. The bow shape is, for example, an elliptical arc or an arc. The bow shape may have a shape having a plurality of curvatures, or may have a shape in which the central portion has a curvature and the end portion is a straight line.

However, the cross-sectional shapes of the first and second restraint surfaces 910 and 920 are not limited to the bow shape. FIG. 27 shows the axially central portion of the billet 7 and the first and second restraint tools 91 and 92 as viewed from the axial direction of the billet 7 during stationary forging according to another embodiment different from those of FIGS. 25 and 26. It is a cross-sectional view. With reference to FIG. 27, the cross-sectional shape of the billets 7 of the first and second restraint surfaces 910 and 920 as viewed from the axial direction may be a V-shape that is convex outward in the radial direction of the billets 7. Alternatively, the cross-sectional shapes of the first and second restraint surfaces 910 and 920 may be arcuate and trapezoidal. The cross-sectional shapes of the first and second restraint surfaces 910 and 920 can be appropriately adjusted within a range in which buckling of the billet 7 can be suppressed.

In FIGS. 25 to 27, two first and second restraint tools 91 and 92 are arranged around the axis of the billet 7. However, additional restraint tools may be placed. For example, in addition to the first and second restraint tools 91 and 92, the third and fourth restraint tools are further arranged around the axis of the billet 7. In this case, four first to fourth restraint tools are arranged around the axis of the billet 7. The number of restraint tools arranged around the axis of the billet 7 can be set as appropriate. Further, the stationary forging machine 8 may further include a restraint tool at a different position in the axial center portion of the billet 7. For example, in the axial direction of the billet 7, the third and fourth restraint tools are further arranged between the first and second restraint tools 91 and 92 and the first and second end faces 70 and 71 of the billet 7. In this case, buckling can be further suppressed. The number of restraint tools in the axial direction of the billet 7 can be set as appropriate.

[Elastic member]
With reference to FIG. 25, the first elastic member 95 is arranged between the first restraint tool 91 and the first restraint tool support mechanism 93. The second elastic member 96 is arranged between the second restraint tool 92 and the second restraint tool support mechanism 94. The elastic member here means a member that is distorted and deformed when an external force is applied, but returns to its original shape when the external force is removed. The elastic member is, for example, a spring, rubber, or the like.

In the above-mentioned stationary forging step, the billet 7 is installed and forged in the axial direction. Therefore, if the stationary forging is carried out, the radius of the billet 7 is expanded. FIG. 28 shows the axial center of the billet 7 as viewed from the axial direction of the billet 7 at the time of the stationary forging after the stationary forging when the stationary forging machine 8 is provided with the first and second restraint tools 91 and 92. It is sectional drawing of the part and the 1st and 2nd restraint tools 91, 92. With reference to FIGS. 25 and 28, the radius of the billet 7 before the installation forging is R0, and after the installation forging, the radius of the billet 7 is expanded to become the radius R1.

When the radius of the billet 7 is increased, the first and second restraint tools 91 and 92 are subjected to outward pressure in the radial direction of the billet 7. The first and second elastic members 95 and 96 contract under this pressure. Therefore, the first and second restraint tools 91 and 92 are allowed to move in the radial direction of the billet 7. As a result, the diameter of the billet 7 after the installation forging is not limited, and billets of a plurality of sizes can be manufactured.

Even when the radius of the billet 7 is expanded by the contracted first and second elastic members 95 and 96, the first and second restraining tools 91 and 92 restrain the side surface 72 of the billet 7. maintain. As a result, buckling of the billet 7 can be suppressed even when the billet 7 of the first and second restraint tools 91 and 92 is allowed to move in the radial direction.

In order to suppress the buckling of the billet 7, for example, the side surface 72 of the billet 7 can be completely restrained by an immovable formwork or the like. As a result, buckling of the billet 7 can be suppressed. However, in this case, the type of radius of the billet 7 after installation forging is limited by the inner diameter of the formwork. On the other hand, in the present embodiment, the side surface 72 of the billet 7 is restrained by the first and second restraint tools 91 and 92 that can move in the radial direction of the billet 7. Therefore, it is permissible to increase the radius of the billet 7 at the time of stationary forging. In the present embodiment, the presence of the first and second elastic members 95 and 96 further causes the first and second restraint tools 91 and 92 to be on the side surface 72 of the billet 7 even when the radius of the billet 7 is expanded. Maintain the restrained state. Therefore, in the stationary forging machine 8 of the present embodiment, buckling of the billet 7 at the time of stationary forging can be suppressed, and billets 7 of a plurality of sizes can be manufactured.

In FIGS. 25, 26 and 28, the numbers of the first and second elastic members 95 and 96 are four, respectively. However, the number of the first and second elastic members 95 and 96 is not particularly limited. The number of the first and second elastic members 95 and 96 may be one, respectively. The number, size, material, etc. of the elastic members can be appropriately selected. Further, in FIGS. 25, 26 and 28, the stationary forging machine 8 includes first and second elastic members 95 and 96. However, the elastic members 95 and 96 may be omitted, and even when the first and second restraint tools 91 and 92 are directly attached to the first and second restraint tool support mechanisms 93 and 94, the billet Buckling of 7 can be suppressed.

[Restriction tool support mechanism]
The first restraint tool support mechanism 93 is arranged on the side opposite to the first restraint surface 910 of the first restraint tool 91, and supports the first restraint tool 91. The second restraint tool support mechanism 94 is arranged on the side opposite to the second restraint surface 920 of the second restraint tool 92, and supports the second restraint tool 92.

In FIG. 24, the first restraint tool support mechanism 93 includes a restraint tool support member 930 and a cylinder 931 attached to the restraint tool support member 930. The second restraint tool support mechanism 94 includes a restraint tool support member 940 and a restraint tool support stand 941 immediately below the restraint tool support member 940. The first restraint tool 91 can be moved in the vertical direction by the cylinder 931. As a result, the distance between the first restraint tool 91 and the second restraint tool 92 is widened, and the billet 7 can be easily taken in and out of the stationary forging machine 8 before and after the stationary forging.

In FIGS. 24, 25 and 28, the first restraint tool support mechanism 93 includes a restraint tool support member 930 and a cylinder 931 attached to the restraint tool support member 930. The second restraint tool support mechanism 94 includes a restraint tool support member 940 and a restraint tool support stand 941 immediately below the restraint tool support member 940. However, the method of supporting the first and second restraint tools 91 and 92 is not limited to this method. The first and second restraint tool support mechanisms 93 and 94 can be appropriately selected within a range in which the first and second restraint tools 91 and 92 can be supported.

[Third Embodiment]
Whether or not stationary forging is necessary depends on the steel type of the billet 7 charged into the heating furnace 3, the outer diameter, the amount of rolling down in the inclined rolling mill 4, and the like. Therefore, the above-mentioned manufacturing method may further include a sorting step after the heating step and before the installation forging step. In the sorting step, the billet 7 to be forged is supplied to the forging machine 8, and the billet 7 not to be forged is supplied to the inclined rolling mill 4.

FIG. 29 is a layout diagram of a mold forging member manufacturing facility according to a third embodiment, which is different from FIGS. 3 and 8. With reference to FIG. 29, the manufacturing equipment includes a heating furnace 3, a tilt rolling mill 4, a mold forging machine 5, a stationary forging machine 8, and a sorting mechanism 600.

In FIG. 29, the sorting mechanism 600 includes a first transport mechanism 610, a second transport mechanism 620, and a sorter 630. The first transfer mechanism 610 is arranged between the heating furnace 3 and the inclined rolling mill 4. The first transfer mechanism 610 transfers the billet 7 extracted from the heating furnace 3 to the inclined rolling mill 4. The second transfer mechanism 620 branches from the branch point 640 on the first transfer mechanism 610 and joins the confluence point 650 on the first transfer mechanism 610. The first and second transfer mechanisms 610 and 620 are, for example, a transfer table including a plurality of transfer rollers arranged in a row, or a robot that grabs and moves the billet 7.

The sorter 630 is, for example, a kicker or a robot arm. The sorter 630 moves only the billet 7 to be forged to be installed and forged onto the second transport mechanism 620 among the billets 7 extracted from the heating furnace 3 and move on the first transport mechanism 610. As a result, only the billet 7 to be forged is supplied to the forging machine 8. The billet 7 supplied to the stationary forging machine 8 is stationary forged. The stationary forged billet 7 moves from the confluence point 650 to the first transfer mechanism 610 again and is supplied to the inclined rolling mill 4.

The method of manufacturing the mold forging member using the manufacturing equipment of FIG. 29 is as follows. The billet 7 heated by the heating step is extracted from the heating furnace 3 and transferred onto the first transfer mechanism 610. Subsequently, a sorting step is performed on the extracted billets 7.

In the sorting step, the billet 7 is sorted into a stationary forging target or a non-installed forging target. When the billet 7 is the target for stationary forging, the billet 7 for the stationary forging is supplied to the stationary forging machine 8. Specifically, the billet 7 on the first transport mechanism 610 is moved onto the second transport mechanism 620 using the sorting machine 630 and transported to the stationary forging machine 8.

On the other hand, when the billet 7 is not subject to stationary forging, the billet 7 not subject to stationary forging is supplied to the inclined rolling mill 4. Specifically, the billet 7 on the first transfer mechanism 610 is conveyed as it is to the inclined rolling mill 4 by the first transfer mechanism 610.

In the stationary forging process, the billet 7 to be stationary forged is forged by the stationary forging machine 8. On the other hand, in the reduced diameter rolling step, the billet 7 which is not subject to stationary forging and the billet 7 after the stationary forging are reduced in diameter and adjusted to a desired outer diameter. That is, in the diameter reduction rolling step, the billet 7 to be forged and not to be forged is reduced in diameter.

As described above, in the present embodiment, only the billet 7 that requires set-in forging is set-forged by the sorting step, and the billet 7 that does not require set-in forging is reduced in diameter and rolled as it is by the inclined rolling mill 4. Therefore, the productivity of the mold forging member is increased.

The sorting may be carried out according to the steel type, or may be carried out according to the rolling reduction amount in the inclined rolling mill 4. As described above, the larger the rolling reduction step, the larger the dents of the first and second end faces 70 and 71 of the billet 7. On the other hand, when the rolling reduction amount in the reduced diameter rolling step is small, the dents of the first and second end faces 70 and 71 of the billet 7 are small. In this case, the effect on mold forging (occurrence of curling flaws) is small. Therefore, it is preferable to determine the supply destination of the billet 7 (installed forging machine 8 or inclined rolling mill 4) based on the rolling reduction amount. The amount of reduction of the billet 7 charged into the heating furnace 3 is predetermined for each billet 7. Therefore, the distribution mechanism 600 can distribute the billet 7 according to the planned reduction amount.

In FIG. 29, the sorting mechanism 600 includes a first transport path 610, a second transport path 620, and a sorter 630. However, the distribution mechanism 600 may have another configuration. In short, the configuration is not particularly limited as long as the distribution mechanism 600 can supply the billet 7 to be forged to the stationary forging machine 8 and the billet 7 not to be forged to be installed to the inclined rolling mill 4.

The first to third embodiments described above may further include a roll forming step and a bending step, if necessary. The roll forming step is carried out after the diameter reduction rolling step and before the die forging step. In the roll forming step, the billet 7 is rolled by a hole-shaped roll to distribute the volume of the billet 7 in the axial direction. As a result, the volume of the burr 2 can be further reduced. The bending step is carried out, for example, after the roll forming step. In the bending step, the volume-distributed billet 7 is partially reduced in the direction perpendicular to the axial direction. Thereby, the volume of the burr 2 can be further reduced. In the first to third embodiments described above, a heating step may be further provided if necessary. The heat supplementing step is carried out, for example, after the diameter reduction rolling step and before the mold forging step. In the heat replenishment step, the billet 7 is heated in a well-known heating furnace to a temperature suitable for mold forging.

In the above-mentioned first to third embodiments, the manufacturing method of the crankshaft 1 and the manufacturing equipment thereof have been mainly described. However, the method for manufacturing the mold forging member and the manufacturing equipment thereof of the present embodiment can be applied to the mold forging member other than the crankshaft 1.

The embodiments of the present invention have been described above. However, the embodiments described above are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and the above-described embodiment can be appropriately modified and implemented within a range that does not deviate from the gist thereof.

1 Crankshaft 3 Heating furnace 4 Tilt rolling mill 40 Tilt roll 5 type forging machine 7 Billet 70, 71 Billet end face 72 Billet side surface 8 Stationary forging machine 81, 82 Stationary forging die 810, 820 Tapered hole 811, 821 Installation Billet facing surface of forging die 812, 822 Back surface of stationary forging die 813, 823 Inner peripheral surface of tapered hole 83 Installation drive mechanism 91, 92 Restraint tool 93, 94 Restraint tool support mechanism 910, 920 Restraint of restraint tool Surfaces 95, 96 Elastic member 600 Sorting mechanism

Claims (12)

A method for manufacturing a mold forging member, which is manufactured by using a heating furnace, a tilt rolling mill equipped with three tilt rolls, and a manufacturing facility equipped with a mold forging machine in order from upstream to downstream.
The heating step of heating the billet in the heating furnace and
A reduced-diameter rolling process in which the heated billet is reduced in diameter with the inclined rolling mill to adjust the outer diameter to a desired value.
A method for manufacturing a mold forging member, comprising a mold forging step of mold forging the billet having an adjusted outer diameter with the mold forging machine. The method for manufacturing a mold forging member according to claim 1, further
The manufacturing facility is further equipped with a stationary forging machine between the heating furnace and the inclined rolling mill.
The manufacturing method is
After the heating step and before the diameter reduction rolling step, a stationary forging step is performed on the billet using the stationary forging machine to form a tapered end portion of the billet. A method for manufacturing a mold forging member. The method for manufacturing a mold forging member according to claim 2, further
A sorting step of supplying the billet to be forged to the stationary forging machine to the billet to be forged and supplying the billet not to be forged to the inclined rolling mill after the heating step and before the stationary forging step. With
In the stationary forging step, the billet to be stationary forged is stationary forged.
In the diameter reduction rolling step, a method for manufacturing a mold forging member, in which the billet after the installation forging step and the billet not subject to installation forging are reduced in diameter and rolled. The method for manufacturing a mold forging member according to claim 3.
In the sorting step, the billet to be forged is supplied to the forging machine according to the amount of rolling of the billet in the reduced diameter rolling step, and the billet not to be forged is supplied to the inclined rolling mill. A method of manufacturing a mold forging member to be supplied to. The method for manufacturing a mold forging member according to any one of claims 1 to 4.
A method for manufacturing a mold forging member, wherein the mold forging member is a crankshaft. A heating furnace that heats a billet including a first end face, a second end face opposite to the first end face, and a side surface between the first end face and the second end face.
An inclined rolling mill which is arranged downstream of the heating furnace, has three inclined rolls, and rolls the billet to a desired outer diameter by reducing the diameter.
It is provided downstream of the inclined rolling mill, has a mold having a shape of a desired mold forging member, and has a mold forging machine for forging the billet having an adjusted outer diameter into a desired mold forging member shape. , Manufacturing equipment for mold forging members. The equipment for manufacturing the mold forging member according to claim 6, further
Arranged between the heating furnace and the inclined rolling mill,
A first including a first billet facing surface including a first tapered hole facing the first end surface of the billet at the time of stationary forging, and a first back surface arranged on the side opposite to the first billet facing surface. Stationary forging dies and
A second surface including a second billet facing surface including a second tapered hole facing the second end surface of the billet at the time of stationary forging, and a second back surface arranged on the side opposite to the second billet facing surface. Stationary forging dies and
The first stationary forging die is provided with an stationary drive mechanism capable of driving the billet in the axial direction during stationary forging.
The first stationary forging die and the second stationary forging die are arranged in the horizontal direction.
The first taper hole is
Including the first inner peripheral surface
The width of the first inner peripheral surface in the cross section including the central axis of the first tapered hole of the first stationary forging die decreases from the first billet facing surface toward the first back surface.
The second taper hole is
Including the second inner peripheral surface
The width of the second inner peripheral surface in the cross section of the second stationary forging die including the central axis of the second tapered hole decreases from the second billet facing surface toward the second back surface. A manufacturing facility for mold forging members equipped with a forging machine. The equipment for manufacturing the mold forging member according to claim 7.
The stationary forging machine further
During the stationary forging, a first restraint tool arranged around the axis of the axially central portion of the billet and including a first restraint surface in contact with the side surface of the billet.
At the time of the stationary forging, it is arranged on the opposite side of the first restraint tool across the billet and around the axial central portion of the billet at the time of the stationary forging, and the side surface of the billet. A second restraint tool that includes a second restraint surface that comes into contact with
A first restraint tool support mechanism arranged on the side opposite to the first restraint surface of the first restraint tool and supporting the first restraint tool, and a first restraint tool support mechanism.
A mold forging member manufacturing facility provided with a second restraint tool support mechanism that is arranged on the side opposite to the second restraint surface of the second restraint tool and supports the second restraint tool. The equipment for manufacturing the mold forging member according to claim 8.
The stationary forging machine further
A first elastic member arranged between the first restraint tool and the first restraint tool support mechanism,
A mold forging member manufacturing facility including a second elastic member arranged between the second restraint tool and the second restraint tool support mechanism. The equipment for manufacturing the mold forging member according to any one of claims 7 to 9, further
A distribution mechanism is provided for supplying the billet to be forged to the stationary forging machine and supplying the billet not to be forged to the inclined rolling mill.
The stationary forging machine performs stationary forging of the billet to be stationary forged.
The inclined rolling mill is a mold forging member manufacturing facility for reducing the diameter of the billet after the set-in forging and the billet that is not subject to the set-in forging. The equipment for manufacturing the mold forging member according to claim 10.
The sorting mechanism supplies the billet to be forged to the stationary forging machine according to the amount of rolling down of the billet in the inclined rolling mill, and the billet not subject to the stationary forging is supplied to the inclined rolling mill. Equipment for manufacturing mold forging parts to be supplied to. The equipment for manufacturing the mold forging member according to any one of claims 6 to 11.
The mold forging member is a crankshaft, which is a manufacturing facility for the mold forging member.

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