JP4873401B2 - Sheet hydroform product, sheet hydroform molding method, and sheet hydroform molding apparatus using the same - Google Patents

Description

  The present invention relates to a board hydroform product, a molding method and a board hydroform molding apparatus using the molding method, and more specifically, a board hydroform product having excellent dimensional accuracy while being excellent in impact absorption performance at the time of collision, In addition, the present invention relates to a plate hydroform molding method and a plate hydroform molding apparatus using the same.

  2. Description of the Related Art In recent years, structural members of automobiles have been strongly demanded to improve collision characteristics capable of suppressing damage and impact due to collisions in order to satisfy the standards in accordance with stricter safety standards at the time of collision. In order to meet such demands, the use of high-tensile steel plates as structural members for automobiles and the application of multilayer members composed of a plurality of metal plates have been studied.

  FIG. 1 is a diagram showing a cross-sectional configuration of a bumper beam composed of three plates proposed by Patent Document 1 as a multilayer member. The proposed bumper beam has two beam 1 members (hereinafter referred to as “hat members”) having a hat-shaped cross section in order to provide the reinforcing plate 2 in the vertical direction perpendicular to the longitudinal direction of the vehicle body in the cross section of the beam 1. The combination is such that a reinforcing flat plate 2 is arranged in the middle.

  According to the bumper beam shown in FIG. 1, in the event of a collision, the reinforcing plate 2 made of a flat plate suppresses upward deformation in the vertical direction perpendicular to the collision direction, and efficiently deforms the hat member on the collision surface side. Therefore, it is possible to exert a high reaction force against an impact. However, since the hat member is usually formed by press working, when using a high-tensile steel plate, there is a problem that the spring back after the press working is large. Furthermore, the bumper beam shown in FIG. 1 is a system in which each member is molded and then product is molded by welding. Therefore, there are problems that work steps increase and workability during welding deteriorates.

  With regard to dimensional accuracy and workability after processing, by applying hydroform, it is possible to reduce the springback even when using high-tensile steel sheets, and to reduce the welding process, which can reduce the work process Can be demonstrated.

  If hydroform is divided in more detail, it can be divided into pipe hydroform made of metal pipe and plate hydroform made of metal plate, but at present, pipe hydroform is widely industrialized. It can be said that. However, when applied to structural members of automobiles in recent years, plate hydroform has become an effective technique as proposed in Patent Documents 2 to 4 in consideration of dimensional accuracy and workability after processing.

  FIG. 2 is a diagram showing a cross-sectional configuration of a structural member (front side member) of an automobile using a plate hydroform proposed by Patent Documents 2 to 4. In the structural member shown in FIG. 2, a pair of reinforcing plates 2 are disposed so as to partition the inside of the closed cross-section member 1, and the cross section has a shape with many ridge lines, so that it has excellent strength and rigidity, It is said that a high reaction force can be obtained against impact.

  However, in the bulging process of the structural member shown in FIG. 2 by hydroforming, the reinforcing plate 2 disposed inside the member is formed in such a manner that it is pulled and stretched through the joint 2 a with the closed cross-section member 1. Therefore, the reinforcing plate 2 is limited to a flat plate shape that partitions the inside of the closed cross-section member 1 with a straight line.

  FIG. 3 is a diagram showing a cross-sectional configuration of a vehicle member part proposed by Patent Document 5. As shown in FIG. In the structural member shown in FIG. 2, the reinforcing plate 2 is limited to a flat plate that partitions the inside of the closed cross-section member, whereas in the vehicle member part shown in FIG. 3, the reinforcing plate 2 arranged as an intermediate plate. Is not a flat plate, but is bent in a vertical direction on a right-angle plane in the longitudinal direction. As a result, the collision energy absorption performance of the structural member of the automobile is improved by providing the reinforcing plate 2 as a reinforcing vertical rib.

  However, in the vehicle member part shown in FIG. 3, after hydroforming with two hat members having different widths, a flat closing member 3 covering the reinforcing plate 2 is welded and joined to form a product. It is a method to do.

JP-A-6-171441 JP 2003-320960 A JP 2004-82142 A JP 2004-160485 A JP 2004-182052 A

  As described above, in order to exhibit excellent collision characteristics as structural members for automobiles, the use of high-tensile steel plates and the application of multilayer members composed of multiple metal plates have been studied, but high-strength steel plates are used. In this case, since the dimensional accuracy can be sufficiently secured, a plate hydroform made of a metal plate is also adopted when applying the multilayer member.

  When forming a multilayer member provided with a reinforcing plate with a plate hydroform, as shown in FIG. 2, when the reinforcing plate is formed of a flat plate that partitions the inside of the closed cross-section member with a straight line, the cross-sectional shape is Since there are relatively many ridge lines, the strength and rigidity of the member can be ensured, but certain limitations are imposed on the absorbability of collision energy.

  In contrast, as shown in FIG. 3, the reinforcing plate is not a straight cross-sectional shape formed by a flat plate on a right-angle plane in the longitudinal direction, but plastic deformation deviates from the cross-sectional shape of the flat plate that partitions the inside of the closed cross-section member with a straight line. When forming a portion (hereinafter referred to as “out-of-plane deformed portion”), particularly excellent collision energy absorption can be exhibited as a collision characteristic in axial crushing and bending deformation.

  However, when the out-of-plane deformed portion is formed as in the vehicle member part shown in FIG. 3, in the conventional plate hydroforming method, the hat member is formed by overlapping the plate hydroform from the welded work material. Later, it is necessary to weld the closing member to the bottom surface of the hat member. For this reason, the vehicle member parts shown in FIG. 3 require a plurality of welding processes. In particular, since the welding after the plate hydroforming is a joining of the molded product, twisting due to thermal deformation during welding occurs. In order to solve the problem, there is a case where a correction process is required.

  The present invention has been made in view of the problems of the above-described plate hydroform, and when forming a multilayer member composed of three or more metal plates, an out-of-plane deformation portion is provided on the reinforcing plate, By adopting a molding process that keeps welding work to a minimum, sheet hydrofoam products that have good dimensional accuracy and can also exhibit excellent impact energy absorption in axial crushing and bending deformation, as well as sheet hydro It is an object of the present invention to provide a foam forming method and a plate hydroform forming apparatus using the same.

  In order to solve the above-mentioned problem by improving the collision energy absorption particularly at the time of collision, the present inventors have made various studies on a method of providing an out-of-plane deformed portion on the reinforcing plate by reducing the welding process, In plate hydroforming, it is effective to separate the step of forming the out-of-plane deformed portion on the reinforcing plate and the step of bulging while maintaining the shape of the formed out-of-plane deformed portion. Pay attention.

  At this time, as the step of forming the out-of-plane deformed portion, a method of forming a metal plate material (hereinafter referred to as “blank”) stacked in a single layer or multiple layers by pressing, and a blank stacked in a single layer or multiple layers There are methods of forming by hydroforming bulging, and each can be applied to plate hydroforming.

  And the sheet hydroform molding method including the molding process of the out-of-plane deformed portion is a “composite molding method” in which after forming the out-of-plane deformed portion by pressing, a final shaped product is obtained by bulging the hydroform. After forming the out-of-plane deformed part by hydroforming bulging, it can be further classified into “multi-stage forming method” in which a final shaped product is obtained by bulging.

The present invention has been completed based on the above findings, and uses the following plate hydroform products (1) and (2), and plate hydroform molding methods (3) to (6) (7). ) Plate hydroform molding equipment.
(1) It is composed of three or more metal plates with a reinforcing plate arranged in the middle part and all the peripheral edges are overlapped and joined, and when the cross-sectional shape is observed on a perpendicular surface in the longitudinal direction, The plastic deformation part (hereinafter referred to as “out-of-plane deformation part”) that deviates from the cross-sectional shape of the flat plate that partitions the inside of the cross-section member with a straight line is formed by pressing, and the space divided by the internal reinforcing plate is connected It is a board hydroform product characterized by The space divided by the internal reinforcing plate is connected through a hole provided in the reinforcing plate.
(2) It is composed of three or more metal plates in which a reinforcing plate is arranged in the middle portion and the entire peripheral edge portion is overlapped and joined. A plate hydroform product, characterized in that it is provided with a hydroformed metal plate positioned on one side of the reinforcing plate and a hole penetrating the reinforcing plate.
(3) A first step of processing an injection port for hydrofoaming in at least one metal plate to be used for hydroforming, drilling holes in the reinforcing plate, or providing the reinforcing plate for hydroforming A second step of processing to a smaller area than the metal plate, sandwiching the reinforcing plate between the metal plates provided to the hydroform , joining the metal plate provided to the hydroform and the reinforcing plate , A third step of welding the entire circumference, a fourth step of pressing the metal plate and the reinforcing plate provided to the hydroform, and exchanging the die used for the press with a hydroform die fifth step, and the stamped reinforcing plate without hydroforming, the sixth step, a plate for hydroforming a metal plate that is subjected to the hydroforming Idro foam molding process.
(4) The first step of processing the injection port used for the hydroforming swell process on at least one of the metal plates used for hydroforming, and at least one of the metal plates used for hydroforming and reinforcement A second step of processing the injection port used to swell the hydrofoam that penetrates the plate and welds the periphery of the penetrating part, sandwiching the reinforcing plate between the metal plates provided for the hydroform, The third step of welding the entire circumference of the metal plate to be provided and the reinforcing plate, the fourth step of plastic working the metal plate to be used for hydroforming and the reinforcing plate, and the plastic working. a fifth step of replacing the mold hydroforming die, and the plastic processed reinforcing plate without hydroforming, at least one of a metal plate that is subjected to the hydroforming 1 Sixth step, the plate hydroformed method comprising you hydroforming a.
(5) First step of processing an injection port for swelling of hydrofoam in at least one metal plate to be used for hydrofoam, drilling a hole in the reinforcing plate, or making the reinforcing plate into a hydroform A second step of processing to a smaller area than the metal plate provided, sandwiching the reinforcing plate between the metal plates provided to the hydroform, and joining the metal plate provided to the hydroform and the reinforcing plate , the metal plate a third step, the plastic deformation by pressing a metal plate and the reinforcing plate is subjected to hydroforming to advance the movable mold provided so as to be forward and backward in hydroforming for molds for welding the entire circumference of the fourth step of the fifth step of the retracting a movable mold provided hydroforming for mold accommodated in the hydroforming for mold-defining member, and the plastic processed complement Plate not hydroforming, the sixth step, the plate hydroformed method consisting of hydroforming a metal plate that is subjected to the hydroforming.
(6) a first step of processing an injection port for swelling of hydroform on at least one of the metal plates provided for hydroforming, at least one of the metal plates provided for hydroforming; A second step of processing an inlet for swelling of the hydrofoam, which penetrates the reinforcing plate and welds the periphery of the penetrating portion, sandwiching the reinforcing plate between the metal plates provided for the hydroform, The third step of welding the entire circumference of the metal plate provided to the foam and the reinforcing plate, the double-acting movable mold provided in the hydrofoam mold so as to be able to move forward and backward, fourth step of plastic working by pressing a metal plate and reinforcing plate which is subjected to the hydroforming in the state in which the foam for mold body issuing the movable mold tip, wherein the plastic working has been reinforced plate, the movable Mold A fifth step of hydroforming along the metal plate to be subjected to the hydroformed sandwiched reinforcing plate and the movable die of the double-acting and hydroforming die, the hydroforming for die the retracting the outer movable portion of the movable die of a double acting provided the towards the hydroforming for mold-defining member is retracted, the inner movable movable mold double-acting from the hydroforming die body The sixth step of bringing the tip of the part out , and the plastic-worked reinforcing plate are not subjected to hydroforming, and at least one of the metal plates provided for the hydroforming is subjected to a hydroforming mold and hydroforming. A seventh step of hydroforming along the double-acting movable mold exposed from the mold for foam;
A plate hydroforming method comprising:
(7) The plate hydroforming apparatus used in the plate hydroforming method described in (6) above, wherein the movable die is used when the tip of the movable die is protruded from the die body. Is a plate hydroforming apparatus provided on the mold body on the side where the metal plate provided for the hydroform and the reinforcing plate are overlaid and projecting.

  4A and 4B are diagrams for explaining an “out-of-plane deformed portion” defined in the present invention. FIG. 4A shows a cross-sectional configuration that does not form an “out-of-plane deformed portion”, and FIG. 4B shows an “out-of-plane deformed portion”. The cross-sectional structure which forms is shown. The out-of-plane deformed portion is recognized as a cross-sectional shape of the reinforcing plate 2 on a right-angle plane in the longitudinal direction when the reinforcing plate 2 is joined to the closed cross-section member 1 at both side edges along the longitudinal direction.

  Therefore, when the out-of-plane deformed portion is not formed, as shown in FIG. 4A, the cross-sectional shape of the reinforcing plate 2 is a shape connecting both joints with a straight line, but the out-of-plane deformed portion is formed. As shown in FIG. 4B, a plastic deformation portion 4 is provided that deviates from the cross-sectional shape of the flat plate that partitions the inside of the closed cross-section member with a straight line.

  The out-of-plane deformed portion 4 defined in the present invention is not limited to the cross-sectional shape shown in FIG. 4, and does not need to be provided in the central portion of the reinforcing plate 2 and does not need to be deformed equally on the left and right sides. As shown in FIG. 3, the cross-sectional shape of the plastic deformation portion may be a circle, an ellipse, a rectangle, a polygon, or the like, even if the shape is bent in the vertical direction.

  According to the plate hydroform product and the plate hydroform molding method of the present invention, when forming a multilayer member composed of three or more metal plates, an out-of-plane deformation portion is provided in the reinforcing plate provided in the intermediate portion, By keeping the joining process to a minimum, even when using high-strength steel sheets, the amount of spring back after processing is small and there is no variation, so it is excellent in repeatability, ensuring good dimensional accuracy, Collision energy absorption in axial crushing and bending deformation can be improved. Thereby, the optimal structural member of a motor vehicle can be provided.

  The board hydroform product of the present invention is most suitable for a multilayer member as a vehicle body structural component of an automobile, and can be applied to, for example, a side member, a side sill, a front pillar, a side roof rail, a center pillar, a bumper and the like. In this case, as the blank (metal plate material), it is desirable to employ a high-tensile steel plate (for example, a tensile strength of 400 MPa or more) in order to improve the collision characteristics.

  The three-lap joining adopted by the present invention is not limited to welding means, but can serve as a seal at the time of hydroforming and brazing, adhesive, etc. as long as it can exhibit sufficient bond strength in the final product. Means other than welding can be applied. Therefore, in the following, the description will be made based on the case where the welding means is employed, but the same operational effects can be exhibited even by means other than welding. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIGS. 5A and 5B are diagrams for explaining a molding process by a composite molding method, in which FIGS. 5A and 5B show a cross-sectional configuration in a perpendicular plane in the longitudinal direction, and FIG. 5C shows a cross-sectional configuration in the longitudinal direction. . In the composite molding method, an out-of-plane deformed portion is formed on a reinforcing plate by press working, and then a final shape plate hydroform product is obtained by bulging processing by applying internal pressure. FIG. 5 shows a molding process of a plate hydroform product composed of three plates. In the following description, a three-plate configuration is assumed unless otherwise specified.

  As shown in FIG. 5 (a), the blanks 1 and 2 that are overlap welded are simultaneously processed in the press die 5 by using the punch 6 to form an out-of-plane deformed portion. Next, as shown in FIGS. 5 (b) and 5 (c), in order to apply the internal pressure and perform the bulging process, the upper and lower molds are closed by being inserted into the hydroform mold 7 (hereinafter referred to as “mold”). A required load is applied so that the mold is not released by the press-fitting of liquid.

  When an internal pressure is applied between the blanks 1 and 2 through the liquid inflow path 8 provided in the hydroform mold 7 with a load applied, the upper blank 1a and the lower blank 1b of the three blanks are bulged and deformed. To do. The reinforcing blank 2 positioned at the intermediate portion is not deformed because it receives equal pressure from both the upper and lower sides, and the shape of the out-of-plane deformed portion can be maintained.

  FIG. 6 is a diagram showing a configuration of a blank that is overlap welded for use in the composite molding method shown in FIG. The three blanks 1a, 1b, and 2 are welded at all peripheral edges along the welding line L in order to secure a seal in the bulging process. As the type of welding, laser welding, seam welding, arc welding, flare welding, plasma welding, and the like can be appropriately selected. Furthermore, penetration welding and fillet welding can be appropriately selected as the welded portion form.

  In the blank, the water injection port 9 or the flow hole 10 for securing the flow path is penetrated, and in the configuration of the blank shown in FIG. 6, the water injection port 9 is provided in the lower blank 1b and the reinforcement blank 2, and further the reinforcement blank 3 is provided with three flow holes 10. The number, size, and arrangement pattern of the water injection ports 9 and the circulation holes 10 provided in the blank are not limited, and can be appropriately selected as long as the functions of water injection and channel securing are achieved.

  In addition, the form of the water injection port is not limited to the shape shown in FIG. 6, and other types such as an overlap injection port (see JP 2004-105998 A and JP 3171544 A) are adopted. Can do.

  FIG. 7 is a diagram for explaining a molding process by a multi-stage molding method, in which (a) to (c) show a cross-sectional configuration in a perpendicular plane in the longitudinal direction, and (d) and (e) are cross-sections along the longitudinal direction. The configuration is shown. In the multi-stage forming method, after the out-of-plane deformed portion is formed by the initial bulging process in the hydrofoam die 7, a final-shaped plate hydroform product is subsequently obtained by the bulging process by applying internal pressure.

  FIG. 8 is a diagram showing a configuration example of a blank to be overlap welded for use in the multistage forming method shown in FIG. Of the three blanks 1a, 1b, and 2 that are overlap-welded, a water injection port 9 is provided in the upper blank 1a and the lower blank 1b. For this reason, the liquid flowing in from the water inlet 9 of the upper blank 1a is filled between the upper blank 1a and the reinforcing blank 2, and the liquid flowing in from the water inlet 9 of the lower blank 1b is filled in the lower blank 1b and the reinforcing blank 2. Will be charged in between.

  As shown in FIG. 7 (a), the lap welded blank is inserted into a hydroform mold 7 having a projection 7a for molding in order to form an out-of-plane deformed portion, and is initially expanded. As shown in FIGS. 7B and 7D, when the high-pressure liquid is injected from the water inlet 9 of the upper blank 1a through the liquid inflow path 8 provided in the hydroform mold 7, the upper blank 1a is processed. Receives bulging deformation and sticks to the upper mold. On the other hand, the reinforcing blank 2 and the lower blank 1b are also subjected to bulging deformation, and an out-of-plane deformation portion is formed in the mold.

  Next, as shown to FIG.7 (c), (e), it inserts into the metal mold | die 7 for hydroforming for obtaining a final product, and the water injection port 9 of the upper side blank 1a and the water injection port 9 of the lower side blank 1b By simultaneously injecting the liquid of the same pressure, the lower blank bulges and deforms and sticks to the lower mold. At this time, the reinforcing blank 2 positioned at the intermediate portion is not deformed because it receives equal pressure from both sides thereof, and the shape of the out-of-plane deformed portion can be maintained. In this way, a plate hydroform molded product having an out-of-plane deformed portion on the reinforcing blank 2 can be obtained.

  FIG. 9 is a diagram for explaining another molding example of a molding process by a multi-stage molding method, in which (a) to (c) show a cross-sectional configuration in a perpendicular plane in the longitudinal direction, and (d) and (e) A cross-sectional configuration along the longitudinal direction is shown. FIG. 10 is a diagram showing a configuration of a blank to be overlap welded for use in the multistage forming method shown in FIG. Compared to the configuration of FIG. 8, the blank configuration shown in FIG. 10 is provided with two water inlets 9a, 9b in the lower blank 1b among the blanks 1a, 1b, 2 that are overlap-welded in three pieces, The water injection port of the blank to be welded is provided on the same surface side.

  Although the water injection port 9a formed in the lower blank 1b extends to the reinforcing blank 2, since the periphery of the water injection port of the lower blank is welded along the welding line L, the high pressure that circulates through the water injection port 9a. The liquid is sealed. For this reason, the high-pressure liquid flowing in from the water injection port 9a is filled between the upper blank 1a and the reinforcement blank 2, and the high-pressure liquid flowing in from the water injection port 9b is filled between the lower blank 1b and the reinforcement blank 2. Since the reinforcement blank 2 receives equal pressure from both sides thereof, it does not deform and can maintain the shape of the out-of-plane deformed portion.

  In the board hydroform product of the present invention, by providing a region composed of three blanks in a part of the total length of the product along the longitudinal direction, sufficient strength and rigidity can be ensured at a predetermined location. As a whole, the weight can be reduced. In this case, as the molding method, either a composite molding method or a multistage molding method can be applied.

  FIG. 11 is a diagram showing an embodiment in which a region composed of three blanks is provided in a part, where (a) shows a cross-sectional configuration on a perpendicular plane in the longitudinal direction, and (b) shows a cross-sectional configuration along the longitudinal direction. (C) is a figure which shows the structure of the blank carried out by overlap welding. In the embodiment shown in FIG. 11, the three blanks 1a, 1b, and 2 all have the same outer dimensions, but by providing a large opening in the reinforcing blank 2, only the necessary region of the total product length is three. Can be composed of blanks.

  FIG. 12 is a diagram showing another example of an embodiment in which a region composed of three blanks is provided in a part, where (a) shows a cross-sectional configuration in a perpendicular plane in the longitudinal direction, and (b) shows in the longitudinal direction. (C) is a figure which shows the structure of the blank which overlaps and welds the cross-sectional structure which follows. In the embodiment shown in FIG. 12, the reinforcing blank 2 is configured to be shorter than the upper blank 1a and the lower blank 1b, and the reinforcing blank 2 is arranged at an optimal position in the longitudinal direction, so that only necessary areas are formed by three blanks. Can be configured.

  FIG. 13 is a diagram showing still another example of an embodiment in which a region composed of three blanks is provided in part, (a) is a cross-sectional configuration on a perpendicular plane in the longitudinal direction, and (b) is a longitudinal direction. (C) is a figure which shows the structure of the blank on which overlap welding is carried out. In the embodiment shown in FIG. 13, the lower blank 1 b is configured to be short in the longitudinal direction, and the arrangement position of the lower blank 1 b is selected, so that only a necessary region can be configured with three blanks.

  In the board hydroform product of the present invention, it is possible to give the same shape as the out-of-plane deformed portion formed in the reinforcing blank to a blank other than the reinforcing blank, for example, the lower blank, and further, if necessary. The width of the blank can be changed.

  FIG. 14 is a diagram for explaining a molding process in which a shape similar to an out-of-plane deformed portion is imparted to the lower blank by a multi-stage molding method, and (a) to (c) are cross-sectional configurations on a perpendicular plane in the longitudinal direction. (D) is a figure which shows the structure of the blank overlap-welded. As shown in FIGS. 14 (a) and 14 (b), after forming the out-of-plane deformed portion on the reinforcing blank by the initial bulging process, as shown in FIG. The side blank can be given a shape similar to the out-of-plane deformed portion.

  FIG. 15 is a diagram for explaining a forming process for changing the width of a blank by a multi-stage forming method, (a) to (c) showing a cross-sectional configuration in a perpendicular plane in the longitudinal direction, and (d) being an overlap welding. It is a figure which shows the structure of the blank performed. When the line length of the upper mold is short in the cross-sectional shape, the upper blank 1a can be made narrower than the reinforcing blank 2 and the lower blank 1b, and the weight of the member can be reduced.

  The plate hydroform product of the present invention can have a four-plate structure or a multi-layer structure exceeding the three-plate structure. FIG. 16 is a diagram for explaining a process of forming a five-plate structure by combining a composite molding method and a multi-stage molding method. d) is a diagram showing the structure of a blank to be overlap welded. In the molding example of the five-plate structure shown in FIGS. 16 (a) to 16 (c), the multi-stage molding method is applied after the composite molding method is applied, whereby the reinforcing blank 2 is replaced with the intermediate reinforcing blank 2c, the upper reinforcing blank 2a, and The lower reinforcing blank 2c is composed of three sheets, each having an out-of-plane deformed portion. At this time, in the structure of the welding blank shown in FIG.16 (d), while providing three water injection holes, the circulation hole is provided in the intermediate | middle reinforcement blank 2c.

  As shown in FIG. 16A, all five blanks 1 and 2 are deformed by press working in the press die 5. Next, as shown in FIG.16 (b), it inserts in the metal mold | die 7 for hydroforms of the 1st step, and is 4 sheets of the upper blank 1a and the lower blank 1b, and the upper reinforcement blank 2a and the lower reinforcement blank 2b. The blank is bulged and deformed. At this time, since the same pressure is applied to both sides of the intermediate reinforcing blank 2c, the shape of the out-of-plane deformed portion is maintained. At this time, the high-pressure liquid is injected through the water inlet 9a.

  As shown in FIG. 16 (c), after the bulging process in the first-stage hydroforming mold 7, the upper-stage blank 1 a and the lower-side blank are further charged into the second-stage hydroforming mold 7. The two blanks 1b are bulged and deformed. The injection of the high-pressure liquid at this time is performed simultaneously from all of the water injection ports 9a, 9b, 9c, and the shapes of the intermediate reinforcing blank 2c, the upper reinforcing blank 2a, and the lower reinforcing blank 2b in which the out-of-plane deformed portions are formed are maintained. Get the final product.

  In the plate hydroforming method of the present invention, the number of dies can be halved because no punch is required compared to the normal press molding method. However, the hydroforming die is equipped with a movable die, In addition, the number of molds to be used and the molding process can be further reduced by using the movable mold even in the multi-stage molding method.

  FIGS. 17A and 17B are diagrams for explaining a molding process by a composite molding method using a movable die, and FIGS. The number of molds to be used is determined by operating the movable mold 11 in the hydroforming mold 7 to form an out-of-plane deformed portion in the reinforcing blank 2 and then performing the bulging process by retracting the movable mold 11. Further, the molding process can be reduced.

  FIG. 18 is a diagram for explaining a molding process by a multi-stage molding method using a movable mold, and (a) to (e) show a cross-sectional configuration in a perpendicular plane in the longitudinal direction. By mounting the movable mold 11 on the hydrofoam mold 7 used in a normal multistage molding method, the number of molds to be used and the molding process can be reduced. In the molding process shown in FIG. 18, the out-of-plane deformed portion formed in the reinforcing blank 2 also on the lower blank 1 b without increasing the number of molds by applying the double-acting movable molds 11 a and 11 b. The same shape as can be provided.

  In the molding process described above, an example was shown in which three plate blanks were welded all around before molding. When all-around welding is performed before molding, the machining fluid can be reliably sealed even when hydroforming a component having a complicated shape. Furthermore, if the blank dimensions are determined so that the processed product after hydroforming has the product dimensions, it is possible to omit flange trim and the like, and it is possible to omit welding of three-dimensional parts. There are many advantages to welding.

  Depending on the product, after forming the out-of-plane deformed portion on the blank by press working, lap welding may be performed to cause deformation by hydroforming. Further, in the case of a shallow drawing part, as shown in FIG. 6 and FIG. 8, only a part of the blank welding line L before the molding process does not have to be the entire circumference, or the welding may not be performed. There is. If the entire circumference is not welded, a hydroforming can be performed without reducing the pressure of the working fluid by installing a bead portion for sealing the working fluid at the peripheral portion of the hydroforming mold.

Example 1
In Example 1, in order to confirm the shock absorbing performance of the present invention, the test products of the present invention 1 as a present invention example and the conventional examples 1 to 3 as a comparative example were produced, and a comparative investigation was performed. The production conditions for each test product and the results of the comparative survey are as follows.
(1) Preparation conditions of test product In the present invention 1, a test product having a cross-sectional shape shown in FIG. 19 (a) is obtained by a composite molding method using a welding blank having the configuration shown in FIG. 19 (b). It was. The used steel sheet had a tensile strength (hereinafter referred to as TS) of 270 MPa and a wall thickness of 1.09 mm, and the blank was welded by laser welding. The welding blank formed a projection-like out-of-plane deformed portion in the press die, and then applied a clamping force of 1800 tonf in the hydroform die to perform bulge processing with high-pressure water. The maximum internal pressure was 100 MPa. The cross-sectional shape of the final product was observed, and it was confirmed that the out-of-plane deformed portion was maintained on the reinforcing blank.

  Conventional Example 1 has a two-plate structure and uses a steel plate having a TS of 270 MPa and a wall thickness of 1.2 mm, and a test product having a cross-sectional shape shown in FIG.

  In Conventional Example 2, a steel plate having a TS of 270 MPa and a thickness of 1.2 mm was used as a two-plate structure, and a test product having a cross-sectional shape shown in FIG.

Conventional Example 3 has a three-plate structure, and the same steel plate as that of Invention 1 was used, and a test product having a cross-sectional shape shown in FIG. However, the three-plate structure was a part of the total product length. The reason why the plate thickness is changed between the two-plate structure and the three-plate structure is to compare the same weights in the comparison of impact characteristics.
(2) Results of Comparative Investigation FIG. 21 is a diagram showing the configuration of a three-point bending tester used for investigating impact characteristics in Example 1. Using the three-point bending tester shown in the figure, the amount of bending deformation energy absorbed by each test product was investigated. The results of the investigation are shown in Table 1 with the result of Conventional Example 1 being 100.

  As shown in Table 1, the present invention 1 shows higher energy absorption than other comparative examples, and if the out-of-plane deformed portion is formed on the reinforcing blank, it is partially made into a three-plate structure. Even if it does, the energy absorption performance in a predetermined location is excellent.

  Further, in order to compare the hydroform molding method and the press molding method, when comparing the present invention 1 with the conventional example 3 or the conventional example 1 with the conventional example 2, the test product by the hydroform molding method is provided by the press molding method. More energy is absorbed than the trial product. This is considered to be the influence of work hardening in the plate hydroform.

Further, when the steps of the present invention 1 and the conventional example 3 are compared, in the conventional example 3, each blank is press-molded and overlapped and joined by spot welding, so the number of steps is increased. From this, it was confirmed that the present invention 1 also has an effect of reducing the molding process.
(Example 2)
In Example 2, in order to confirm the dimensional accuracy of the present invention, the test products of the present inventions 2 and 3 as the present invention example and the conventional examples 4 and 5 as the comparative example were produced, and a comparative investigation was performed. The production conditions for each test product and the results of the comparative survey are as follows.
(1) Preparation conditions of test product In the present invention 2, a test product having a cross-sectional shape shown in FIG. 22 was obtained by a composite molding method using a welding blank shown in FIG. The steel plate used was a high-tensile steel plate having a TS of 780 MPa and a wall thickness of 1.2 mm, and lap welding was performed by laser welding. An out-of-plane deformed portion was formed in the press mold, and then a clamping force of 1800 tonf was applied in the hydroform mold to perform bulging with high-pressure water. The maximum internal pressure was 100 MPa.

  In Invention 3, a test product having a cross-sectional shape shown in FIG. 22 was obtained by a multistage forming method using the welding blank shown in FIG. The steel plate used was the same as in the case of the present invention 2 and was molded using a movable mold, but the hydroforming molding conditions were also the same as in the case of the present invention 2.

  In the conventional method 4, the same steel plate as that of the present invention 1 was used, and three individually pressed plates were welded.

In the conventional method 5, the same steel plate as in the present invention 1 was used, and a two-ply welded blank was bulged with hydroform, and then the press-formed blank was overlap welded.
(2) Results of comparative survey The dimensions of each test product were measured, and the survey results are shown in Table 2.

  Conventional Example 4 by the press molding method has a large spring back and poor dimensional accuracy. Therefore, a mold was prepared with a springback in mind, and molding was performed, but the final error was as large as ± 0.25 mm.

  Conventional Example 5 in which the two-sheet hydroform member and the press-formed member were welded showed higher dimensional accuracy than Conventional Example 4 by the press-forming method, but was a large value of ± 0.17 mm. .

On the other hand, all of the examples of the present invention showed good dimensional accuracy, but the present invention 3 by the multi-stage molding method was extremely excellent in dimensional accuracy. Thus, according to the forming method of the present invention, it was found that good dimensional accuracy can be obtained even when a high-tensile steel plate (TS = 780 MPa) is used. In the multi-stage molding method, it was confirmed that the number of molds can be reduced by using a movable mold.
(Example 3)
In Example 3, in order to confirm the axial crushability of the present invention, the present invention 4 (product by a multi-stage molding method) and the conventional example 6 (two-sheet press product) were used as test products to be crushed in the axial direction. The impact characteristics were compared. The test was conducted under the conditions that the length of the test body was 300 mm and the collision speed was 64 km / h.

  FIG. 24 is a diagram showing a cross-sectional shape of the test product used in Example 3. The present invention 4 shown in FIG. 24 (a) is a three-plate hydroform product formed by a multistage forming method using a steel plate having a TS of 270 MPa and a plate thickness of 1.2 mm. Conventional Example 6 shown in FIG. 24B is a two-sheet press product formed using a steel plate having a TS of 270 MPa and a plate thickness of 1.8 mm. In order to compare with the same weight, the plate thickness of Conventional Example 6 was set to be thicker than that of Invention 4. The results are shown in Table 3.

  From the results shown in Table 3, it can be seen that the invention 4 significantly improves the absorbed energy (6%) compared to the conventional example 6. From this, it was confirmed that the plate hydroform product according to the present invention exhibits excellent impact energy absorption performance in both bending deformation and axial crushing.

  According to the plate hydroform product and the plate hydroform molding method of the present invention, the reinforcing plate provided in the intermediate portion is provided with an out-of-plane deformed portion, and is composed of three or more metal plates by minimizing the welding process. Even when using a high-strength steel sheet when forming a multilayer member to be formed, the amount of spring back after processing is small and there is no variation, so it is excellent in repeatability, ensuring good dimensional accuracy, Collision energy absorption in axial crushing and bending deformation can be improved. Thereby, it can apply widely as an optimal structural member of a car.

It is a figure which shows the cross-sectional structure of the bumper beam comprised by the 3 sheet board which patent document 1 proposes as a multilayer member. It is a figure which shows the cross-sectional structure of the structural member (front side member) of the motor vehicle using the board hydroform which the patent documents 2-4 propose. It is a figure which shows the cross-sectional structure of the member member for vehicles which patent document 5 proposes. It is a figure explaining the "out-of-plane deformation part" prescribed | regulated by this invention, (a) shows the cross-sectional structure which does not form an "out-of-plane deformation part", (b) is the cross section which forms an "out-of-plane deformation part" The configuration is shown. It is a figure explaining the molding process by the composite molding method. It is a figure which shows the structure of the blank overlap-welded in order to use for the composite-molding method shown in the said FIG. It is a figure explaining the formation process by a multistage forming method. It is a figure which shows the structure of the blank overlap-welded in order to use for the multistage shaping | molding method shown in the said FIG. It is a figure explaining the other shaping | molding example of the shaping | molding process by a multistage shaping | molding method. FIG. 10 is a diagram showing a configuration of a blank that is overlap welded for use in the multistage forming method shown in FIG. 9. It is a figure which shows embodiment which provides the area | region comprised with three blanks in part. It is a figure which shows the other example of embodiment which provides the area | region comprised by three blanks in part. It is a figure which shows the further another example of embodiment which provides the area | region comprised with three blanks in part. It is a figure explaining the shaping | molding process which provides the shape similar to an out-of-plane deformation part to a lower blank by a multistage shaping | molding method. It is a figure explaining the shaping | molding process which changes the width | variety of a blank with a multistage shaping | molding method. It is a figure explaining the process of shape | molding a 5 sheet | seat structure combining the composite shaping | molding method and a multistage shaping | molding method. It is a figure explaining the shaping | molding process by the complex shaping | molding method using a movable metal mold | die. It is a figure explaining the shaping | molding process by the multistage shaping | molding method using a movable metal mold | die. It is a figure which shows the cross-sectional shape of the sample product used in Example 1, and the structure of a welding blank. It is a figure which shows the cross-sectional shape of the sample product used in Example 1. FIG. It is a figure which shows the structure of the 3 point | piece bending test machine used in order to investigate an impact characteristic in Example 1. FIG. It is a figure which shows the cross-sectional shape of the sample product used in Example 2. FIG. It is a figure which shows the structure of the welding blank used in Example 2. FIG. It is a figure which shows the cross-sectional shape of the sample product used in Example 3. FIG.

Explanation of symbols

1: beam, closed cross-section member, upper blank, lower blank 2: reinforcement plate, reinforcement blank, 3: closing member 4: out-of-plane deformation portion, plastic deformation portion, 5: press die 6: punch, 7: hydroform Mold 8: Liquid inflow path, 9: Water inlet 10: Flow hole, 11: Movable mold L: Welding line

Claims (13)

  When the cross-sectional shape is observed on a right-angled surface in the longitudinal direction, the reinforcing plate is formed of a closed cross-section member. A plastic deformation part (hereinafter referred to as “out-of-plane deformation part”) that deviates from the cross-sectional shape of the flat plate that divides the inside with a straight line is formed by pressing, and the spaces divided by the internal reinforcing plates are connected. Sheet hydroform products.   The board hydroform product according to claim 1, wherein the space divided by the internal reinforcing plate is connected through a hole provided in the reinforcing plate. It is composed of three or more metal plates with a reinforcing plate arranged in the middle part and the entire peripheral edge part overlapped and joined, and the out- of- plane deformed part is formed on the reinforcing plate by hydroforming bulging or pressing, A plate hydroform product comprising a hydroformed metal plate positioned on one side of the reinforcing plate and a hole penetrating the reinforcing plate. A first step of processing an injection port for swelling of hydrofoam on at least one metal plate provided for hydrofoam;
A second step of drilling a hole in the reinforcing plate or processing the reinforcing plate into a smaller area than the metal plate provided for hydroforming;
A third step of sandwiching the reinforcing plate between metal plates provided for hydroforming , joining the metal plate provided for hydroforming and the reinforcing plate , and welding the entire periphery of the metal plate ;
A fourth step of pressing the metal plate and the reinforcing plate to be provided to the hydroform;
A fifth step of exchanging the die used for the press processing with a hydroform die , and the pressed reinforcing plate is not hydroformed, and the metal plate provided for the hydroform is hydroformed. A sixth step of
A plate hydroforming method comprising: A first step of processing an inlet used for hydroforming of hydroform on at least one of the metal plates provided for hydroform;
A second step of processing an inlet used for swelling of hydrofoam, which penetrates at least one of the metal plates provided to the hydroform and the reinforcing plate and welds the periphery of the penetrating portion;
A third step in which the reinforcing plate is sandwiched between metal plates provided for hydroforming, and the entire circumference of the metal plate provided for hydroforming and the reinforcing plate is welded;
A fourth step of plastically processing the metal plate to be used for hydroforming and the reinforcing plate;
A fifth step of exchanging the mold used for the plastic working with a hydroform mold ; and
The plastic processed reinforcing plate without hydroforming, the sixth step you hydroforming at least one of the metal plate is subjected to the hydroforming,
A plate hydroforming method comprising:   The plate hydroforming method according to claim 5, wherein the fourth step is a step of pressing a metal plate provided to the hydroform and the reinforcing plate.   The fourth step is a step of hydroforming a metal plate provided for hydroforming and the reinforcing plate, and at least one of the metal plates provided for hydroforming overlaps with the reinforcing plate. The plate hydroforming method according to claim 5, which is a hydroforming process. In the sixth step, the liquid having the same pressure is formed between the space formed in the fourth step and the plate in which the metal plate and the reinforcing plate used in the hydroforming overlap in the fourth step. The plate hydroforming method according to claim 7 , wherein the hydroforming is press-fitted. A first step of processing an inlet for swelling of hydrofoam on at least one of the metal plates provided for hydrofoam;
A second step of drilling a hole in the reinforcing plate or processing the reinforcing plate into a smaller area than the metal plate provided for hydroforming;
A third step of sandwiching the reinforcing plate between metal plates provided for hydroforming , joining the metal plate provided for hydroforming and the reinforcing plate , and welding the entire periphery of the metal plate ;
Fourth step of plastically deformed by pressing to advance the metal plate and a movable mold provided so as to be forward and backward said reinforcing plate hydroforming for molds to be subjected to hydroforming,
A fifth step of storing the hydroforming for mold body by retracting the movable mold provided in the hydroforming for molds, and
The plastic processed reinforcing plate without hydroforming, sixth step of hydroforming a metal plate that is subjected to the hydroforming,
A plate hydroforming method comprising: A first step of processing an inlet for swelling of hydrofoam on at least one of the metal plates provided for hydrofoam;
A second step of processing an inlet for swelling of hydrofoam, in which at least one of the metal plates provided to the hydrofoam and the reinforcing plate penetrate, and the periphery of the penetrating portion is welded;
A third step in which the reinforcing plate is sandwiched between metal plates to be used for hydroforming, and the entire circumference of the reinforcing plate and the metal plate to be used for hydroforming is welded;
To advance the double-acting movable mold provided so as to be forward and backward in the hydroforming mold, the metal plate to be subjected to the hydroforming while issuing the movable mold from the tip hydroforming for mold-defining member And a fourth step of plastically processing the reinforcing plate by pressing ,
Hydroforming the plastically processed reinforcing plate and the movable mold and a metal plate provided for the hydroform sandwiched between the reinforcing plates along the hydroforming mold and the double-acting movable mold A fifth step of processing,
Wherein retracting the outer movable portion of the movable die of a double acting provided in hydroforming for dies are retracted toward the hydroforming for mold body, double-acting from the hydroforming die body A sixth step in which the tip of the inner movable portion of the movable mold is brought out ; and
The plastic-worked reinforcing plate is not hydroformed, and at least one of the metal plates used for the hydroforming is exposed from the hydroforming die and the hydroforming die. A seventh step of hydroforming along the mold ,
A plate hydroforming method comprising: The fourth step is a step of advancing the double-acting movable mold and bending and plastically deforming a metal plate and a reinforcing plate to be used for hydroforming by pressing the movable mold. 10. The plate hydroforming method according to 10. The plate hydroforming method according to claim 10 , wherein the fourth step is hydroforming performed in a state in which a tip of the movable die is protruded from a die body. The plate hydroforming apparatus used in the plate hydroforming method according to claim 12 , wherein the movable mold is a metal on a side where the metal plate provided for the hydroform and the reinforcing plate are overlapped and projectingly molded. A plate hydroforming device provided in the mold body.

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