JP6665643B2 - Manufacturing method and manufacturing apparatus for expanded pipe parts - Google Patents

Description

  The present invention relates to a method and an apparatus for manufacturing an expanded-diameter pipe part.

  Generally, pipe-expanded (mouth-expanded) parts are used as exhaust system parts for automobiles and motorcycles. These are desired to be integrally formed from the viewpoint of less welding and cost reduction.

  On the other hand, a special shape is required, for example, having an eccentric and enlarged diameter end portion at the end of the metal tube.

  As a part with a special shape that has been expanded, a general part having a predetermined diameter, and formed at the tip of the cylinder and expanded to a predetermined size with respect to this general part, in the axial direction of the general part An enlarged portion having an axial direction decentered at a predetermined intersection angle, and a changing portion formed between the general portion and the enlarged portion and expanding from the general portion to a tip portion at a predetermined inclination angle. There is an expanded tube part having (1) and (2) arranged in the axial direction.

  As a method of processing a special shape on a metal tube, a forming method of performing bulge forming (hydroforming) has been proposed as disclosed in Patent Documents 1 to 3.

  Further, as disclosed in Patent Documents 4 to 6, spinning processing, which is a technique of plastic working in which a tubular material is pressed against a rotating mold by a working roller or a spatula to form the material, has been proposed.

JP 2000-225422 A JP 2004-268096 A JP 2000-045767 A JP 2000-190038 A JP-A-2003-010935 JP 2009-018342 A

  However, in bulge forming and spinning, the processing equipment is large and expensive, and the cycle time is long and the productivity is low. There is a problem that variation occurs and cracks and wrinkles are likely to occur. In particular, in the processing of a high-strength material or a welded pipe, it is difficult to manufacture a molded product having a large degree of end processing by bulging or spinning.

  Under such circumstances, there is a demand for a manufacturing method and a manufacturing apparatus capable of manufacturing a large-diameter pipe part having a large degree of end machining with low cost, low tact time and high productivity.

  An object of the present invention is to provide a method and an apparatus for manufacturing the above-described enlarged-diameter tube component.

  The present invention is as listed below.

(1) A cylindrical body made of a metal material is processed to form a general portion having a predetermined diameter, and a diameter formed at the tip of the cylindrical body and expanded to a predetermined size with respect to the general portion. An enlarged portion having an axial direction that is eccentric at a predetermined intersection angle with respect to the axial direction of the general portion, and the enlarged portion formed between the general portion and the enlarged portion and from the general portion. A method for manufacturing an enlarged-diameter pipe component having a change portion that expands in diameter at a predetermined inclination angle toward in the axial direction,
At least one concentric expanding step of manufacturing a first intermediate molded product by pressing a concentric expanding punch in the axial direction of the cylindrical body and performing concentric expanding processing on the cylindrical body,
An eccentric pipe-expanding punch having an outer surface shape that matches the inner surface shape of the changing portion, and the concentric expanding process in the first intermediate molded product installed in a mold having an inner surface shape that matches the outer surface shape of the changing portion. By eccentrically expanding the first intermediate molded product by pushing in the axial direction of the performed portion, the end portion is expanded compared to the expanded product, which is the final product, having the shape of the changing portion and having the shape of the changing portion. An eccentric expansion process for producing a second intermediate molded product,
A diameter-reducing punch having an inner surface shape that matches the outer surface shape of the enlarged diameter portion is pushed outside the end of the second intermediate product to reduce the diameter of the end of the second intermediate product. (Diameter drawing).

  (2) The diameter-reducing punch is characterized in that the diameter-reducing punch is pressed in the axial direction of the second intermediate molded product from outside the end of the second intermediate molded product, thereby reducing the diameter. )).

  (3) The concentric expanding step includes forming a concentric expanding punch having a punch half angle larger than the inclination angle of the changing portion, an outer diameter larger than the inner diameter of the cylindrical body, and smaller than the inner diameter of the changing portion. The method for manufacturing a part of a large-diameter pipe according to the above mode (1) or (2), wherein the pipe is concentrically expanded at an expansion ratio of 25% or less by pushing the cylindrical body in the axial direction.

  In the present invention, the “expansion ratio” refers to an expansion ratio based on the outer diameter of the expanded portion before the expansion process in each step. That is, the expansion ratio is: ((outer diameter of expanded portion after expansion in each process-outer diameter of expanded portion before expansion in each process) / outer diameter of expanded portion before expansion in each process) x 100 (%).

Or, if the outer diameter of the expanded portion of the front pipe expanding at each step was d _0, which is the outer diameter d ₁ of the expanded portion after pipe expanding in each step, the expansion ratio _{= {(d 1 -d 0)} / d ₀ } × 100 (%).

  In addition, it is sufficient that at least one concentric pipe expansion step is provided, but a plurality of steps may be used depending on the shape of the final product. For example, in the case of processing the concentric expansion process in three stages, it can be formed as follows.

  (1) In the method for manufacturing the expanded-diameter pipe part according to any one of (1) to (3), the concentric expansion step includes a first concentric expansion step, a second concentric expansion step, and a third concentric expansion step. .

  The first concentric expansion step includes a step of forming a first concentric expansion punch having a punch half-angle larger than the inclination angle of the changing portion, an outer diameter larger than the inner diameter of the cylindrical body, and smaller than the inner diameter of the changing portion. By pushing in the axial direction of the cylindrical body, the cylindrical body is expanded at a pipe expansion ratio of 25% or less to produce an intermediate molded product 1a.

  In the second concentric pipe expansion step, the second half having a punch half-angle larger than the inclination angle and having an outer diameter larger than the inner diameter at the axial end of the intermediate molded product of the first a and smaller than the inner diameter of the changing portion. Is pushed in the axial direction of the 1a intermediate molded product to a position just before the first concentric expanded punch, thereby expanding the 1a intermediate molded product at an expansion ratio of 25% or less. 1b is produced.

  Further, the third concentric expansion step has a punch half-angle larger than the inclination angle, and has an outer diameter larger than the inner diameter at the axial end of the 1b intermediate molded product and smaller than the inner diameter of the changing portion. The third expanded punch is pushed in the axial direction of the 1b intermediate molded product to a position just before the second concentric expanded punch to expand the 1b intermediate molded product at an expansion ratio of 25% or less. To manufacture the 1c intermediate molded product.

  Then, the eccentric expanding pipe having an eccentric pipe expanding punch having an outer surface shape matching the inner surface shape of the changing portion is mounted on the mold having the inner surface shape matching the outer surface shape of the changing portion, by the concentric expanding pipe of the 1c intermediate molded product. The eccentric expansion process is performed on the 1c intermediate molded product by pushing the processed portion in the axial direction, so that the end portion of the intermediate molded product having the shape of the changing portion is expanded more than the expanded product, which is the final product. To produce a second intermediate molded product.

  Further, it is one of the modes preferably used in the present invention that the first concentric pipe expanding punch, the second concentric pipe expanding punch, and the third concentric pipe expanding punch have the same punch half angle.

  (4) The expanded diameter pipe according to any one of (1) to (3), further including a step of cutting a thinned portion formed at a tip of the enlarged diameter portion. The method of manufacturing the part.

In the present invention, the “thinned portion” refers to a thickness of a raw tube (also referred to as a cylindrical body in the present invention) before diameter expansion processing is compared with a thickness of an expanded diameter pipe part as a final product. , Means a reduced thickness portion. Specifically, the wall thickness reduction rate = {(thickness before diameter expansion processing−thickness after diameter expansion processing) / thickness before diameter expansion processing} × 100 (%). Or, the thickness of the material before the steel pipe mouth spread molding and t _0, when the thickness after mouth spread molding in the axial direction end portion of the end mouth spread steel pipe was t _1, the thinning rate = {(t ₀₋ t ₁ ) / t ₀ } × 100 (%). The more the wall thickness reduction ratio becomes positive, the more the wall thickness is reduced.

  (5) The method according to any one of (1) to (4), wherein the tubular body is a welded pipe.

  (6) The method according to any one of (1) to (5), wherein the material has a tensile strength of 590 MPa or more.

  (7) The expanded pipe according to any one of (1) to (6), wherein the expanded pipe part is an exhaust system muffler or a catalyst case of an automobile or a motorcycle. The method of manufacturing the part.

(8) The cylindrical body which is a metal material is processed to have a general portion having a predetermined diameter and a general portion formed at the tip of the cylindrical body and expanded to a predetermined size with respect to the general portion. An enlarged portion having an axial direction that is eccentric at a predetermined intersection angle with respect to the axial direction of the general portion, and the enlarged portion formed between the general portion and the enlarged portion and from the general portion. An apparatus for manufacturing an expanded-diameter pipe part having a change portion that expands in diameter at a predetermined inclination angle toward in the axial direction,
At least one concentric expanding punch for producing a first intermediate product by being pushed in the axial direction of the cylindrical body and performing concentric expanding processing on the cylindrical body;
A mold having an inner surface shape that matches the outer surface shape of the changing portion,
It has an outer surface shape that matches the inner surface shape of the changing portion, and is pushed in the axial direction of the portion where the concentric expansion process has been performed in the first intermediate molded product installed in the mold, and the first An eccentric pipe-expansion punch for producing a second intermediate molded product having the shape of the above-mentioned change portion and having an end expanded from the expanded-diameter pipe part as a final product by performing eccentric expansion processing on the intermediate molded product; ,
It has an inner surface shape that matches the outer surface shape of the enlarged diameter portion, and is pressed into the outside of the end of the second intermediate molded product to reduce the diameter of the end of the second intermediate molded product. An apparatus for manufacturing an expanded-diameter pipe part, comprising:

  (9) The expanded-diameter pipe part described in (8), wherein the reduced-diameter punch is pushed in the axial direction of the second intermediate molded product from the outside of the second intermediate molded product. Manufacturing equipment.

  (10) The concentric expanding punch has a punch half angle larger than the inclination angle of the changing portion, an outer diameter larger than the inner diameter of the cylinder, and an outer diameter smaller than the inner diameter of the changing portion. The expanded pipe part manufacturing apparatus according to the above mode (8) or (9), wherein the tubular body is expanded at an expansion rate of 25% or less by being pushed in the axial direction.

  (11) The diameter increasing device according to any one of the items (8) to (10), further including a cutting unit configured to cut a thinned portion formed at a tip of the enlarged diameter portion. Equipment for manufacturing pipe parts.

  (12) The apparatus according to any one of the above items (8) to (11), wherein the material is a welded tube.

  (13) The apparatus for manufacturing an expanded-diameter pipe part according to any one of (8) to (12), wherein the material has a tensile strength of 590 MPa or more.

  (14) The expanded pipe according to any one of (8) to (13), wherein the expanded pipe part is an exhaust system muffler or a catalyst case of an automobile or a motorcycle. Parts manufacturing equipment.

  According to the present invention, a general portion having a predetermined diameter and a predetermined cross angle with respect to the axial direction of the general portion are formed at the tip of the cylindrical body and expanded to a predetermined size with respect to the general portion. A radially enlarged portion having an axial direction eccentric with a variable portion formed between the general portion and the radially expanded portion and extending from the general portion to a tip portion at a predetermined inclination angle is arranged in the axial direction. It is possible to provide a manufacturing method and a manufacturing apparatus for the expanded-diameter pipe component having the above.

  Further, according to the manufacturing method and the manufacturing apparatus of the present invention, since the tubular material can be set in a predetermined mold, and the opening can be processed by a predetermined diameter-enlargement punch after the opening, a plurality of dies can be formed. Since it is not necessary to use the material and it is not necessary to change the material, the process and the cost can be reduced. Further, since the center of the material and the axis of the diameter-enlargement punch can be prevented from shifting, the product dimensions and shape can be stabilized, and the product yield can be improved.

FIG. 1 is a cross-sectional view showing an example of an enlarged-diameter pipe component manufactured according to the present invention. 2 (a) to 2 (e) are explanatory views showing the preferred manufacturing steps of the present invention over time. FIG. 3 is a contour diagram showing the wall thinning rate of the expanded pipe part manufactured according to the present invention. FIG. 3 (a) is a front view of the expanded pipe part, and FIG. FIG. 3C is a bottom view of the expanded-diameter pipe part.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

1. FIG. 1 is a cross-sectional view showing an example of an enlarged-diameter pipe component manufactured according to the present invention.

  As shown in FIG. 1, the expanded-diameter pipe part P3 manufactured according to the present invention has a general portion P31, a changing portion P32, and an expanded-diameter portion P33 having a predetermined diameter arranged in the axial direction.

  The enlarged diameter portion P33 is formed at the distal end of the cylindrical body and is enlarged to a predetermined size with respect to the general portion P31. Have.

  The intersection angle θ is preferably in the range of 5 to 30 °. Within this range, the formation of the thinned portion of the expanded-diameter pipe part P3 is suppressed, product breakage can be suppressed, and reduction in yield can be significantly suppressed.

  If the crossing angle θ is less than 5 °, it is not possible to obtain a large-diameter pipe part having a large degree of end processing, which is the object of the present invention, and it is possible to manufacture not only the present invention but also the prior art. There is no. On the other hand, if the crossing angle θ exceeds 30 °, cracks may occur during machining in some cases, and it is difficult to manufacture the expanded pipe part P3 having sufficient dimensional accuracy even without cracks.

  The changing portion P32 is formed between the general portion P31 and the enlarged diameter portion P33, and is expanded at a predetermined inclination angle (α1, α2) from the general portion P31 toward the enlarged diameter portion P33. Since the inclination angle of the changing portion is not constant in the circumferential direction of the enlarged-diameter pipe part P3, FIG. 1 shows the inclination angles α1 and α2 by a cross-sectional view of the enlarged-diameter pipe part P3.

  Further, it is preferable to set the inclination angles α1 and α2 such that the final expansion ratio from the material is 100% or less. Within this range, the formation of the thinned portion of the expanded-diameter pipe part P3 is suppressed, product breakage can be suppressed, and reduction in yield can be significantly suppressed.

2. 2. Manufacturing Apparatus According to the Present Invention FIGS. 2A to 2E are explanatory views showing preferred manufacturing steps of the present invention over time.

  As shown in FIGS. 2A to 2E, a manufacturing apparatus 0 according to the present invention includes a concentric expanding punch 1, an eccentric expanding punch 2, a reduced diameter punch 3, and a mold 4.

(2-1) Concentric expansion punch 1
As shown in FIG. 2A, the concentric expansion punch 1 is pushed in the axial direction of the cylinder P from the end Pa side of the expansion hole side of the cylinder P to perform concentric expansion on the cylinder P. Thereby, the first intermediate molded product P1 is manufactured.

  The concentric expanding pipe punch 1 has an inclined portion 11 having an inclination angle β (hereinafter, referred to as a “punch half angle β”) larger than a predetermined inclination angle α at a changing portion P32 of a desired expanded pipe part P3 manufactured in the present invention. Is preferably provided at the tip of the cylinder body press-in side. Here, the inclination angle α indicates an average value at each position in the circumferential direction of the cross section of the changing portion P32.

  Further, the concentric expanding punch 1 preferably has an outer diameter d larger than the inner diameter of the cylindrical body P and smaller than the inner diameter of the changing portion P32. The expansion ratio by one concentric expansion punch 1 is preferably 25% or less, more preferably 20 to 25%.

  The punch half angle β can be appropriately adjusted according to the size of the inclination angle α and the length of the changing portion P32. For example, the punch half angle β is an angle larger than the inclination angle α, and is preferably in the range of 30 ° to 60 °. If the punch half-angle β is less than 30 °, the metal material is insufficiently pushed and cracks are likely to occur in the changed part. As the inclination angle β increases, the load due to the punch pressing becomes too large and buckling easily occurs. If β exceeds 60 °, curling deformation such that the end on the pipe expansion hole side is rolled outward occurs, which is not preferable.

  In the above description, the case where one concentric expanding punch 1 is provided is taken as an example. However, it is sufficient that at least one concentric expanding punch is provided, and depending on the shape of the final product, a plurality of concentric expanding punches may be provided. For example, a case where three concentric expanding punches are provided will be described with reference to FIGS. 2A to 2C as an example.

  A first concentric expanding punch 1 shown in FIG. 2A, a second concentric expanding punch 1-1 shown in FIG. 2B, and a third concentric expanding punch 1-2 shown in FIG. 2C. Is used.

  As shown in FIG. 2A, the first concentric expanding punch 1 has a punch half angle β1 larger than a predetermined inclination angle α at a changing portion P32 of a desired expanded pipe part P3 manufactured in the present invention. An inclined portion 11a is provided at the tip of the cylinder body press-in side. The first concentric expanding punch 1 preferably has an outer diameter d1 larger than the inner diameter of the cylindrical body P and smaller than the inner diameter of the changing portion P32.

  The first concentric pipe-expanding punch 1a expands the pipe P by being pushed in the axial direction of the pipe P from the end of the pipe P on the side of the pipe-expanding hole, thereby forming the 1a intermediate molded product P1a. To manufacture.

  The expansion ratio from the cylindrical body P by the first concentric expansion punch 1a is preferably 25% or less, more preferably in the range of 20 to 25%.

  As shown in FIG. 2 (b), the second concentric expanding punch 1-1 has a punch half angle β2 larger than a predetermined inclination angle α at a changing portion P32 of a desired expanded pipe part manufactured in the present invention. Of the first intermediate molded product P1a on the press-fit side end. The second concentric expanding punch 1-1 preferably has an outer diameter d2 larger than the inner diameter at the axial end of the 1a intermediate molded product P1a and smaller than the inner diameter of the changing portion P32.

  The second concentric pipe-expanding punch 1-1 is located in front of the pushed position of the first concentric pipe-expanding punch 1 in the axial direction of the 1a intermediate molded product P1a from the end of the 1a intermediate molded product P1a on the side of the expansion hole. By being pushed to the position, the 1a-th intermediate molded product P1a is expanded to produce a 1b-th intermediate molded product P1b.

  The expansion ratio of the second concentric expansion punch 1b from the 1a intermediate molded product P1a is preferably 25% or less, and more preferably 20 to 25%.

  As shown in FIG. 2C, the third concentric expanding punch 1-2 has a punch half angle β3 larger than a predetermined inclination angle α at a changing portion P32 of a desired expanded pipe part manufactured in the present invention. The first inclined part 11c is provided at the tip of the 1b intermediate molded product P1b on the press-fit side. Further, the third concentric expanding punch 1-2 preferably has an outer diameter d3 larger than the inner diameter at the axial end of the 1b intermediate molded product P1b and smaller than the inner diameter of the changing portion 32.

  The third concentric tube-expanding punch 1-2 is located just before the pushing position of the second concentric tube-expanding punch in the axial direction of the 1b-b intermediate molded product P1b from the end on the tube-expansion hole side of the 1b-b intermediate molded product P1b. By pressing the intermediate molded product P1b to the position, the 1b intermediate molded product P1b is expanded to produce a 1c intermediate molded product P1c.

  The expansion ratio of the third concentric expansion punch 1c from the 1b intermediate molded product P1b is preferably 25% or less, more preferably 20 to 25%.

  The punch half angles β1, β2, and β3 can be appropriately adjusted according to the size of the inclination angle α and the length of the changing portion P32. For example, the punch half angle β3 is an angle larger than the inclination angle α, and is preferably in the range of 30 ° to 60 °. When the punch half angle β2 is less than 30 °, the metal material is insufficiently pressed and cracks are likely to occur in the changed part. As the punch half angle β2 increases, the load due to the pressing of the punch becomes too large to easily cause buckling. If β2 exceeds 60 °, curling deformation such that the end on the pipe expansion hole side is rolled outward occurs, which is not preferable.

  The relationship among the punch half angles β1, β2, β3 of the concentric expanding punches 1a to 1b is not particularly limited. It can be set as appropriate in accordance with the desired shape of the enlarged-diameter tube component changing portion. For example, β1 = β2 = β3, β1 <β2 <β3, or β1 <β2> β3.

  Regarding the eccentric expansion pipe punch 2 and the mold 4, the same eccentric expansion punch 1 and the same one as described later in the case of having one concentric expansion punch 1 can be used.

  As described above, it is preferable to use a plurality of concentric pipe expanding punches, because it is possible to reduce the wall thinning rate in the changing section P32 and the pipe expanding section P33 of the expanded pipe part formed into a desired shape.

(2-2) Eccentric expansion punch 2
As shown in FIG. 2D, the eccentric expansion punch 2 has an outer shape that matches the inner shape of the change portion P32 of the desired expanded pipe part P3. The eccentric pipe-expanding punch 2 is pushed in the axial direction of the concentric pipe-expanded portion of the first intermediate molded product P1 or 1c intermediate molded product P1c installed in the mold 4, and the first intermediate molded product By performing eccentric pipe expansion processing on the intermediate molded product P1c of P1 or 1c, the second intermediate molded product having the shape of the changing portion P32 and having an end expanded from the expanded pipe part P3 which is the final product P2 is manufactured.

  Further, as shown in FIG. 2D, not only the inner surface shape of the changing portion P32 but also an outer surface shape that matches a part of the inner surface shape of the enlarged diameter portion P33 may be provided. In this case, the shape of the diameter-reducing punch 3 described below may have an inner surface shape that matches the outer surface shape of the diameter-enlarging portion P33 in a portion other than a part of the diameter-enlarging portion P33 formed by the eccentric expanding tube punch 2. .

  In addition, the eccentric expanding punch 2 may be divided into a plurality of parts depending on the shape of the changing portion P32.

(2-3) Reduced diameter punch 3
As shown in FIG. 2E, the reduced diameter punch 3 has an inner surface shape that matches the outer surface shape of the enlarged diameter portion P33 of the desired enlarged diameter pipe part. The reduced diameter punch 3 is pushed outside the end of the portion of the second intermediate molded product P2 where the eccentric expansion has been performed, and performs the diameter reducing process on the end of the second intermediate molded product P2. Is manufactured.

  It is preferable that the reduced diameter punch 3 is axially pushed into the end of the second intermediate molded product P2 from the outside. It is preferable that the diameter-reducing punch 3 is pushed into the end of the second intermediate molded product P2 in the axial direction, because the diameter-reducing processing can be performed without moving the mold 4. Further, even when the mold 4 is moved, the mold 4 may be designed to be moved outward from the second intermediate molded product P2 only at a part of the portion where the reduced diameter punch 3 is pushed. , And can be manufactured by simple steps.

(2-4) Mold 4
The mold 4 can have the second intermediate molded product P2 disposed therein, and has an inner surface shape that matches the outer surface shape of the changing portion P32 of the expanded pipe part P3 (the shape of the final product).

  FIG. 2 shows an embodiment in which the mold 4 is divided into an upper mold 4a and a lower mold 4b. However, the present invention is not limited to this embodiment. May be.

  It is preferable that a plate or the like be provided at the end opposite to the end on the side of the pipe expansion hole to close the end of the mold 4.

  Further, the manufacturing apparatus of the present invention may further include a cutting means for cutting a thinned portion formed at the tip of the enlarged diameter portion P33 of the enlarged diameter pipe part P3.

  FIG. 3 is a contour diagram showing the wall thickness reduction rate of the expanded-diameter pipe part P3 manufactured according to the present invention. FIG. 3 (a) is a front view of the expanded-diameter pipe part P3, and FIG. FIG. 3C is a bottom view of the enlarged-diameter pipe part P3. FIGS. 3A to 3C show that the greater the positive value of the wall thickness reduction ratio, the greater the wall thickness reduction.

  For example, at the tip of the expanded-diameter pipe part P3 shown in FIG. 3, there is a part where the degree of wall thinning is large (reduction rate of 10 to 20%). Can be eliminated.

  Furthermore, when the cylindrical body P as a material is a welded pipe, when the cylindrical body P is set in the mold 4, the welded pipe is connected to the center point of the cross section of the deformed portion P32 of the expanded-diameter pipe part P3. It is preferable to install the welding portion so as to be located at the circumferential portion closest to the position because the breaking at the time of expanding the diameter can be suppressed.

  Existing mechanisms can be used for the pressing mechanism of the mold and the punch, and examples thereof include a hydraulic cylinder, a gas cylinder, and a pressing mechanism such as a spring or rubber.

  ADVANTAGE OF THE INVENTION According to the manufacturing apparatus of this invention, since a tubular material is set to a predetermined metal mold | die, and it carries out a mouth drawing process after a widening process with a predetermined diameter expansion punch, it is not necessary to use a several metal mold | die, and a material is grasped. Since no replacement is required, steps and costs can be reduced. Further, since it is possible to prevent the axial center of the material and the diameter expanding punch from shifting, the dimensional accuracy of the diameter expanding pipe part P3 is stabilized and the product yield is improved.

  The above description has been made with reference to an example in which the concentric tube-expanding punch 1 (1-1, 1-2), the eccentric tube-expanding punch 2, the reduced-diameter punch 3, and the mold 4 are provided. Depending on the shape of P3), a concentric expanding punch having another outer diameter may be appropriately added in addition to the concentric expanding punch 1 (1-1, 1-2).

3. The manufacturing method according to the present invention The manufacturing method according to the present invention includes a concentric pipe expansion step, an eccentric pipe expansion step, and a diameter reduction processing step.

(3-1) Concentric Expanding Step As shown in FIG. 2A, in the concentric expanding step, the concentric expanding punch 1 is pushed in the axial direction of the cylindrical body P from the end on the expanding hole side of the cylindrical body P. The first intermediate molded product P1 is manufactured by performing concentric pipe expansion processing on the cylindrical body P in the above.

  By providing a concentric expansion step of uniformly expanding the cylindrical body P in the cross-sectional circumferential direction at the previous stage of the eccentric expanding step of forming the desired changed portion P32, the shape of the changed portion P32 is different in the cross-sectional circumferential direction. Even if there is, it is preferable because thickness reduction in the circumferential direction of the cross section of the changing portion P32 can be suppressed.

  That is, when the eccentric expansion is performed from the initial step, only the expanded side is prevented from being extremely thinned.In addition, in the conventional method, the material easily flows in the pipe axis direction at the location, so that the end face of the product is straightened. In the present invention, the phenomenon of skew rather than obliqueness can be suppressed smaller, and the product yield can be improved.

  In the concentric expanding step, it is preferable to perform concentric expanding processing on the cylindrical body P by using the concentric expanding punch 1 having an outer diameter larger than the inner diameter of the cylindrical body P which is a raw tube and smaller than the inner diameter of the changing portion P32. .

  Further, the inclined portion 11 having a larger inclination angle β (hereinafter, referred to as “punch half angle β”) than the predetermined inclination angle α at the changing portion P32 of the desired enlarged-diameter tube part manufactured in the present invention is press-fitted into the cylindrical body. It is preferable to use a concentric expanding punch at the side end. Here, the inclination angle α indicates an average value of the inclination angles in the circumferential direction of the cross section of the changing portion P32.

  The pushing amount of the metal material in the concentric pipe expansion step can be appropriately adjusted by adjusting the punch half angle β with respect to the size of the inclination angle α and the length of the changing portion P32. If the metal material is insufficiently pushed, cracks are likely to occur in the changing part. If the amount of pushing increases, the load due to the pressing of the punch is too large and buckling tends to occur. Since the curling deformation such that the side end is rolled outward occurs, the punch half angle β is larger than the inclination angle α, and is preferably in the range of 30 ° to 60 °.

  The expansion ratio in one concentric expansion step is preferably 25% or less, and more preferably 20 to 25%.

  Although not particularly limited, preferably, the cylindrical body P is disposed inside the mold 4 during the concentric expansion step.

(3-2) Eccentric Expansion Step As shown in FIG. 2 (d), in the eccentric expansion step, the eccentric expansion punch 2 having an outer surface shape that matches the inner surface shape of the changing portion P32 and the outer surface shape of the changing portion P32 match. A mold 4 having an inner surface shape is used.

  The eccentric expansion punch 2 is pushed in the axial direction of the portion where the concentric expansion process is performed in the first intermediate molded product P1 installed inside the mold 4 to perform the eccentric expansion process on the first intermediate molded product P1. Thus, the second intermediate molded product P2 having the shape of the changing portion P32 and having the end expanded from the expanded pipe part P3 as the final product is manufactured.

  Further, as shown in FIG. 2B, not only the inner surface shape of the changing portion P32 but also a mold 4 and an eccentric expanding tube punch 2 having an outer shape matching the inner shape of a part of the enlarged diameter portion P33 are used. Eccentric expansion processing may be performed. In this case, in the eccentric expansion processing, a part of the expanded diameter part P33 of the desired expanded diameter pipe part P3 is formed at the same time, so that in the subsequent diameter reduction processing, the expanded diameter part P33 not formed in the eccentric expansion step is used. The diameter reduction processing may be performed on the shape portion.

  Furthermore, when the mold 4 and the eccentric expanding punch 2 to be used are divided into a plurality, the pushing of each eccentric expanding punch may be divided into several stages.

(3-3) Diameter Reduction Step As shown in FIG. 2 (e), in the diameter reduction step, the reduced diameter punch 3 having the inner surface shape that matches the outer surface shape of the enlarged diameter portion P33 is formed by the second intermediate molding. The outer diameter of the second intermediate molded product P2 is reduced by being pushed outside the end of the product P2.

  It is preferable that the diameter-reducing punch 2 is subjected to the diameter-reducing process by being pushed in the axial direction of the second intermediate molded product P2 from outside the end of the second intermediate molded product P2. Pressing the diameter reducing punch in the axial direction in this manner is preferable because the diameter reduction processing can be performed without significantly moving the mold 4. Further, even when the mold 4 is moved, the mold 4 may be designed to be moved outward from the second intermediate molded product P2 only at a part of the portion where the reduced diameter punch 3 is pushed. , And can be manufactured by simple steps.

  Further, the manufacturing method of the present invention may further include a cutting step of cutting a thinned portion formed at the tip of the enlarged diameter portion P33 of the enlarged diameter pipe part P3. For example, a reduced thickness portion is shown at the tip of the enlarged diameter pipe part shown in FIG. 4, but it can be cut along a dotted line to cut off the reduced thickness part of the enlarged diameter pipe part.

  Furthermore, when the cylindrical body P as a material is a welded pipe, when the cylindrical body P is set in the mold 4, the welded pipe is connected to the deformed portion P32 of the expanded-diameter pipe part P3 having a desired shape. It is preferable to install the welding portion so as to be located at the circumferential portion closest to the position serving as the center point of the cross section, because breakage during diameter expansion processing can be suppressed.

  Existing means can be used for pressing the mold and the punch, and examples thereof include a hydraulic cylinder, a gas cylinder, and a pressing mechanism such as a spring or rubber.

  According to the manufacturing method of the present invention, the tubular material is set in a predetermined mold, and the opening drawing can be performed after the opening process with a predetermined diameter expanding punch, so that it is not necessary to use a plurality of dies. Since it is not necessary to change the material, the process and cost can be reduced. Furthermore, since the material and the center of the diameter-enlargement punch can be prevented from shifting, the product dimensions and shape are stabilized, and the product yield is improved.

  In the above, the manufacturing method including one concentric expansion step, eccentric expansion step, and diameter reduction processing has been described. However, depending on the shape of the expanded pipe part, a further concentric expansion step using a concentric expansion punch having a different outer diameter may be performed. May be added.

  Hereinafter, a description will be given of a manufacturing method of an embodiment including three concentric pipe expansion steps, namely, a first concentric pipe expansion step, a second concentric pipe expansion step, and a third concentric pipe expansion step.

(4-1) First Concentric Expansion Step As shown in FIG. 2A, in the first expansion step, the inclination angle α of the changing portion P32 of the desired expanded pipe part P3 manufactured in the present invention is determined. Also, a first concentric expanding punch 1a having a larger punch half angle β1 and an outer diameter d1 larger than the inner diameter of the cylinder P and smaller than the inner diameter of the changing portion P32 is used. By pushing the first concentric expanding punch 1a in the axial direction of the cylindrical body P from the end side of the cylindrical body P, the cylindrical body P is expanded to manufacture the 1a-th intermediate molded product P1a.

  The expansion ratio of the expansion process in the first expansion process is preferably 25% or less, and more preferably 20 to 25%.

(4-2) Second Concentric Expansion Step As shown in FIG. 2 (b), in the second expansion step, a predetermined inclination angle α at the change portion P32 of a desired expanded pipe part manufactured in the present invention. A second concentric expanding punch 1b having a punch half angle β2 larger than the inner diameter of the cylindrical body P and an outer diameter d2 smaller than the inner diameter of the changing portion P32 is used. From the end of the 1a intermediate molded product P1a on the side of the pipe expanding hole side to the axial direction of the 1a intermediate molded product P1a, up to a position just before the first concentric expansion punch is pushed in by the first concentric expansion process. The 1a intermediate molded product P1a is expanded by pushing in the tube expansion punch 1b to produce the 1b intermediate molded product P1b.

  The expansion ratio of the expansion process in the second concentric expansion process is preferably 25% or less, and more preferably 20 to 25%.

(4-3) Third Concentric Expansion Step As shown in FIG. 2C, in the third expansion step, a predetermined inclination angle α at the changing portion P32 of a desired expanded pipe part manufactured in the present invention. A third concentric expanding punch 1c having an outer diameter d3 larger than the inner diameter of the cylinder P and smaller than the inner diameter of the changing portion P32 is used. From the end of the 1b intermediate molded product P1b on the side of the pipe expanding hole to the axial direction of the 1b intermediate molded product P1b, up to a position just before the second concentric expansion punch is pushed in by the second concentric expansion process. The 1b intermediate molded product P1b is expanded by pushing in the tube expansion punch 1c to produce the 1c intermediate molded product P1c.

  The expansion ratio of the expansion process in the third concentric expansion process is preferably 25% or less, and more preferably 20 to 25%.

  The eccentric tube expanding step and the diameter reducing step are as described above.

  Performing a plurality of concentric pipe expansion steps as described above is preferable because it is possible to reduce the wall thinning rate in the change portion P32 and the pipe expansion portion P33 of the expanded-diameter pipe part formed into a desired shape.

4. Metal material used in the present invention The present invention, for example,
(A) the average thickness of the mouth spread molding before the material steel pipe and _{t 0,} the outer diameter when as D, the ratio _(t 0 / D) in the range of 0.005 to 0.3 and _t 0 = 0, 0.5-30 mm, D = 15-700 mm,
(B) mouth spread the thickness of the material steel pipe before molding and t _0, thinning ratio when the thickness after mouth spread molding in the axial direction end portion of the end mouth spread steel pipe was t ₁ "{(t ₀₋ t ₁ ) / t ₀ } × 100 (%) ”is 0 to 40,
(C) When the length L (mm) of the enlarged diameter portion formed by flaring to the axial end of the end flaring steel pipe is in the range of 0D to 10D,
(D) The work hardening coefficient (strain effect index) n value of the end-opened steel pipe is in the range of 0.005 to 0.4,
(E) The r value, which is a characteristic value representing the deep drawability of the end-opened steel pipe, can be applied in the range of 0.3 to 4.0. In particular, in the mouth-opening molding, if the n value is too small, the molding load becomes large and the buckling becomes easy. On the other hand, if the r value is too small, the material is difficult to flow, and the moldability is poor (the expansion ratio that can be molded is small) descend).

  The steel type of the raw steel pipe is not particularly limited in the present invention.

  The metal material used in the present invention is not particularly limited, but a metal material having high strength such as stainless steel or high-tensile steel can be preferably used.

  Further, even if the material has a tensile strength of 590 MPa or more, it can be preferably used.

  According to the present invention, it is possible to manufacture an expanded-diameter pipe component without buckling or cracking even with such a high-strength material.

  Furthermore, the present invention can be preferably used even when the material is a welded pipe.

  ADVANTAGE OF THE INVENTION According to this invention, even if a raw material is a welded pipe, extremely thinning and breakage can be suppressed in the vicinity of the welded portion or on the side opposite to the welded portion in the circumferential direction of the material. Diameter tube parts can be manufactured.

  The expanded pipe part manufactured by the present invention can be preferably used as a catalyst case of an automobile or a motorcycle, a fuel supply pipe for fuel injection of an automobile, and the like.

1, 1-1, 1-2: Concentric expansion punch 2: Eccentric expansion punch 3: Reduced diameter punch 4: Die

Claims (14)

A cylindrical body extending in the first axial direction and made of a metal material is processed to form a general portion extending in the first axial direction and having a predetermined diameter, and a general portion formed at a tip of the cylindrical body. A diameter-expanded portion having a second axis direction expanded to a predetermined size with respect to the first axis direction and eccentric at a predetermined intersection angle with respect to the first axis direction, and between the general portion and the diameter-expanded portion. toward the enlarged diameter portion from said general portion is formed into a method of manufacturing a radially enlarged tube part which chromatic and changing portion whose diameter increases to a predetermined inclination angle,
At least one concentric expanding step of manufacturing a first intermediate molded product by performing a concentric expanding process on the cylindrical body by pushing a concentric expanding punch from the distal end of the cylindrical body in the first axial direction,
An eccentric pipe-expanding punch having an outer surface shape that matches the inner surface shape of the changing portion, and the concentric expanding process in the first intermediate molded product installed in a mold having an inner surface shape that matches the outer surface shape of the changing portion. By performing eccentric expansion processing on the first intermediate molded product by pressing the performed portion in the first axial direction, the first intermediate molded product has the shape of the changing portion and is larger in end than the expanded product as the final product. An eccentric expansion step for producing a second intermediate molded product whose part is expanded,
A diameter reducing punch having an inner surface shape that matches the outer surface shape of the enlarged diameter portion is pushed outside the end of the second intermediate molded product to reduce the diameter of the end of the second intermediate molded product. And a diameter reducing step of forming the enlarged diameter portion by performing the following steps. 2. The expanded pipe according to claim 1, wherein the reduced diameter punch is reduced in diameter by being pushed into the first axial direction from outside the end of the second intermediate molded product. 3. The method of manufacturing the part. The concentric tube expansion step, with a large punch half angle than the inclination angle of the change unit, larger than the inner diameter of the cylindrical body, the first axis concentric tube expanding punch having an outer diameter smaller than the inner diameter of said change unit 3. The method for manufacturing a pipe part according to claim 1, wherein the pipe is concentrically expanded at a pipe expansion ratio of 25% or less by pushing in a direction. 4.   4. The method of manufacturing the expanded diameter pipe part according to claim 1, further comprising a step of cutting a thinned portion formed at a front end of the enlarged diameter portion. 5.   The method according to any one of claims 1 to 4, wherein the tubular body is a welded pipe.   The method according to any one of claims 1 to 5, wherein the material has a tensile strength of 590 MPa or more.   The method according to any one of claims 1 to 6, wherein the enlarged pipe part is an exhaust system muffler or a catalyst case of an automobile or a motorcycle. A cylindrical body extending in the first axial direction and made of a metal material is processed to form a general portion extending in the first axial direction and having a predetermined diameter, and a general portion formed at a tip of the cylindrical body. A diameter-expanded portion having a second axis direction expanded to a predetermined size with respect to the first axis direction and eccentric at a predetermined intersection angle with respect to the first axis direction, and between the general portion and the diameter-expanded portion. toward the enlarged diameter portion from said general portion is formed into an apparatus for manufacturing a radially enlarged tube part which chromatic and changing portion whose diameter increases to a predetermined inclination angle,
At least one concentric tube-expanding punch which is pushed into the first axial direction from the distal end of the tube, and performs concentric tube-expansion processing on the tube to produce a first intermediate molded product;
A mold having an inner surface shape that matches the outer surface shape of the changing portion,
It has an outer surface shape that matches the inner surface shape of the change portion, and is pushed in the first axial direction with respect to a portion of the first intermediate molded product installed in the die, on which the concentric expansion process has been performed. By performing eccentric expansion processing on the first intermediate molded product, a second intermediate molded product having the shape of the changing portion and having an end expanded from the expanded pipe part as a final product is manufactured. Eccentric expansion punch
It has an inner surface shape that matches the outer contour of the enlarged diameter portion, the second Push the outside of said end portion of the intermediate molded article rare, the diameter-reduction processing to the end portion of the second intermediate product An apparatus for manufacturing a part of an enlarged diameter pipe, comprising: a reduced diameter punch for forming the enlarged diameter part by performing the operation. The apparatus according to claim 8, wherein the reduced-diameter punch is pushed in the first axial direction from outside the second intermediate molded product. The concentric expanding punch has a punch half angle larger than the inclination angle of the changing portion, an outer diameter larger than the inner diameter of the cylindrical body, and smaller than the inner diameter of the changing portion, and is pushed in the first axial direction. The expanded pipe part manufacturing apparatus according to claim 8, wherein the pipe is expanded at a pipe expansion rate of 25% or less by performing the expansion.   The apparatus according to any one of claims 8 to 10, further comprising a cutting unit configured to cut a thinned portion formed at a tip of the enlarged diameter portion. .   The apparatus according to claim 8, wherein the material is a welded pipe.   13. The apparatus according to claim 8, wherein the material has a tensile strength of 590 MPa or more. The apparatus for manufacturing an expanded pipe part according to any one of claims 8 to 13, wherein the expanded pipe part is an exhaust system muffler or a catalyst case of an automobile or a motorcycle.