WO2021215392A1

WO2021215392A1 - Press forming method for elongated component, and vehicular pillar member formed by same forming method

Info

Publication number: WO2021215392A1
Application number: PCT/JP2021/015855
Authority: WO
Inventors: 啓正宮田; 井上　直明; 洋康小坂; 宗一郎馬場
Original assignee: 豊田鉄工株式会社
Priority date: 2020-04-20
Filing date: 2021-04-19
Publication date: 2021-10-28
Also published as: JP7335198B2; JP2021171767A

Abstract

Disclosed is a method for forming, by cold pressing, an elongated component whereby the cross-sectional shape orthogonal to the longitudinal direction is a hat shape, having a top plate part in the middle and a flange section at both ends. The hat depth, corresponding to the distance from the flange sections to the top plate part, of the elongated component varies at positions in the longitudinal direction. This method comprises a plurality of press forming steps, including at least a first press forming step for forming an intermediate formed article and a second press forming step for forming a final formed article, the hat depth being formed by this plurality of press forming steps. A press die of the second press forming step comprises an upper die and a lower die. The upper die has a plurality of pads disposed subdivided in the longitudinal direction of the elongated component at locations corresponding to the top plate part. The lower die has a blank holder disposed at a location corresponding to the flange sections. The amount by which each pad juts out in a press forming direction from the upper die at the start of the second press forming step is set according to the hat depth at which the relevant pad is disposed.

Description

Press molding method for long-shaped parts and pillar members for vehicles molded by the same molding method

The present invention relates to a press molding method for long-shaped parts and a pillar member for a vehicle molded by the same molding method. In particular, the present invention relates to a press molding method performed in two stages, a first press molding step of molding an intermediate molded product and a second press molding step of molding a final molded product by using a pad on a part of a press mold.

Various long-shaped parts manufactured by press molding are used for the body of vehicles such as automobiles. As the long-shaped component, for example, there is a pillar member constituting a pillar arranged on a side portion of a vehicle body of an automobile. Pillars include front pillars, center pillars, and rear pillars. The member responsible for the strength of the center pillar is also called the center pillar reinforcement.

The center pillar reinforcement is usually a structural member with a closed cross section in which the outer member and inner member are integrated by welding. The center pillar member such as the outer member and the inner member is, for example, a press-molded product of a high-strength steel plate, and is molded into a predetermined shape by cold press molding. For example, some center pillar members have a hat-shaped cross section orthogonal to the longitudinal direction after molding. In this case, the center pillar member has a central top plate portion, flange portions at both ends, and side plate portions connecting the top plate portion and the flange portion.

The hat depth, which is the distance between the top plate and the flange, may differ depending on the position of the center pillar member in the longitudinal direction. For example, the hat depth is changed according to the change in the width of the top plate portion depending on the position in the longitudinal direction. The center pillar member is arranged with its longitudinal direction generally oriented in the vertical direction, and usually has a gently curved shape protruding outward in the vehicle width direction in order to cope with an impact such as a side collision.

The molding of the center pillar member described above is usually performed by cold press molding. In the conventional general press forming, a high-strength steel plate (for example, 1180 MPa material) is deep-drawn to obtain a desired hat depth H in one press forming. In the case of this one deep drawing process, the press-formed product may be cracked or wrinkled because of the high-strength steel plate.

In addition, when the above-mentioned one-time press molding is performed, the movement of the molding material during the press molding is large. Therefore, a measure is taken in which the press reference pin is provided in the press mold, the press reference pin hole is provided in the molding material, and the two are fitted to each other to suppress the movement of the molding material. However, when this measure is adopted, the press reference pin holes of the material may be rounded by the press reference pins during press molding. The term "hole rolling" as used herein means that a relative displacement in the plane direction occurs between the press reference pin and the press reference pin hole, and the press reference pin hole is expanded by the press reference pin. Then, when the hole is rounded, it affects the molding accuracy of the press-molded product.

On the other hand, if the press reference pin is not used to avoid the problem of hole curling, another problem arises in which the variation in outer shape accuracy becomes large when press molding without the outer shape.

Therefore, various proposals have been made as measures for accurately molding long-shaped members. For example, there is a policy of performing press molding in two steps (for example, see International Publication No. 2014/050973) and a policy of dividing and arranging pads to be set in a press mold (for example, in addition to the above publication, Japanese Patent Application Laid-Open No. 2015). -11237 (see).

As in the above-mentioned patent documents, various measures have been conventionally proposed for cold press molding of long-shaped members such as center pillar members of vehicles such as automobiles with high accuracy. However, there is a demand for further proposals for press-molding the final molded product with high accuracy to prevent or reduce molding defects in the final molded product. In particular, when a long member having a hat-shaped cross-sectional shape and the depth of the hat-shaped shape (hat depth) differs in the longitudinal direction, press molding with high accuracy is performed when press molding is performed using a pad. Proposals to do are desired.

One aspect is a method in which a long-shaped part having a hat-shaped cross-sectional shape orthogonal to the longitudinal direction and having a top plate portion in the center and flange portions at both ends is formed by cold pressing. The hat depth corresponding to the distance from the flange portion to the top plate portion of the long-shaped component differs depending on the position in the longitudinal direction. This method includes a plurality of press molding steps including at least a first press molding step of molding an intermediate molded product and a second press molding step of molding a final molded product, and the hat depth is the plurality of presses. It is formed by a molding process. The press mold in the second press molding step includes an upper mold and a lower mold, and a plurality of pads are arranged in the upper mold at positions corresponding to the top plate portion by dividing them in the longitudinal direction of the long-shaped part. The lower mold is provided with a blank holder at a position corresponding to the flange portion. The amount of protrusion of each pad from the upper mold in the press molding direction at the start of the second press molding step is set according to the hat depth at the position where the pad is arranged.

Depending on the embodiment, the amount of protrusion of the pad at the start of the second press molding step is the hat depth H1 of the final molded product and the hat depth of the intermediate molded product at the position where the pad is arranged. The difference from H2 is H1-H2.

Depending on the embodiment, a plurality of press reference pins are set in the press mold in the second press molding step, and the press reference pins are set in each of the plurality of pads.

Depending on the embodiment, the hat depth in the final molded product and the hat depth in the intermediate molded product are the hat depths at the position where the press reference pin is set.

Another aspect is a long-shaped part molded by the above method.

Depending on the embodiment, the long-shaped part is a pillar member for a vehicle.

It is a perspective view which looked at the vehicle pillar outer member of one Embodiment from the vehicle outside direction. It is a front view which looked at the pillar outer member of FIG. 1 from the outside of a vehicle. It is a side view of the pillar outer member of FIG. It is sectional drawing which shows typically the IV-IV line cross section of the pillar outer member of FIG. 1 and FIG. It is a figure which shows each stage of the 1st press molding process as one Embodiment step by step. It is a figure which shows each stage of the 2nd press molding process as one Embodiment step by step. It is a perspective view which shows the molding material of the pillar outer member as one embodiment. It is a perspective view which shows the intermediate molded article of a pillar outer member. It is a perspective view which shows the final molded product of a pillar outer member. It is a figure which shows the modification which arranged a plurality of press reference pins on one pad as another embodiment. It is sectional drawing which shows typically by cutting the pillar outer member in the process of molding by a press die along the line XI-XI of FIG. It is sectional drawing which shows typically by cutting the pillar outer member in the process of molding by a press die by line XII-XII of FIG. It is sectional drawing which shows typically by cutting the pillar outer member in the process of molding by a press die along the line XIII-XIII of FIG. It is a figure explaining the hat depth schematically.

Hereinafter, various embodiments of the present invention will be described with reference to the drawings.

The press molding method of the embodiment described in the present application can be used for molding long-shaped parts such as pillar members of vehicles. As described at the beginning, front pillars (A pillars), center pillars (B pillars), and rear pillars (C pillars) are provided on the side portions of the vehicle in order from the front as structural members of the vehicle body. In one embodiment, the long-shaped part to be molded can be a center pillar member that bears the strength of the center pillar. The center pillar is usually an assembly member (called a center pillar reinforcement) in which a pillar inner member arranged inside and a pillar outer member arranged outside are integrated by welding when viewed in the vehicle width direction. There is also). As one embodiment, the center pillar member to be molded can be this pillar outer member. However, the various features of the structure and method described below are the inner members of the center pillar, the strength members of the front and rear pillars, and the bumper reinforcement that is responsible for the strength of the bumpers provided at the front and rear of the vehicle. In particular, it can be widely applied to long members having a hat-shaped cross section.

<Pillar outer member>
1 to 3 are perspective views of the pillar outer member 10 of the center pillar on the left side of the vehicle as viewed from the outside as one embodiment. FIG. 2 is a front view of the pillar outer member 10 of FIG. 1, and FIG. 3 is a side view. In the description of the pillar outer member 10, the direction indications appropriately shown in each figure indicate the directions in the normal posture state of the vehicle. The arrow FR indicates the vehicle forward direction, the arrow UP indicates the upward direction, and the arrow IN indicates the vehicle width inner direction. In the following description, the description regarding the direction uses the direction with respect to this vehicle. In addition, when the left and right components are present on the left and right on the drawing, when the left and right parts are individually designated, L is added to the left component on the drawing at the end of the code indicating the component. , The components on the right side are indicated by R.

As shown in FIG. 1, the pillar outer member 10 is arranged so that its length extends in the vertical direction of the vehicle. Since the pillar outer member 10 is a structural member that is required to have high strength at the time of a side collision of the vehicle, it is usually convex with respect to the direction in which the lateral impact load acts in a part of the longitudinal direction in which the lateral impact load acts. It is formed into a curved shape.

As one embodiment, the range A of the upper half of the pillar outer member 10 shown in FIG. 1 is configured to have a curved shape that is convex in the outward direction of the vehicle. This curved shape can be clearly seen from the side view of FIG.

The range B of the lower half of the pillar outer member 10 can be made substantially linear, as can be clearly seen from the side view of FIG.

As can be clearly seen in FIG. 2 seen from the side surface of the vehicle, the pillar outer member 10 is arranged in an inclined state in which the upper end is behind the vehicle from the lower end. Then, the pillar outer member 10 is joined to the roof side rail 18 via a substantially T-shaped mounting portion 16 formed at the upper end. Further, it is joined to the side sill 22 via a substantially T-shaped mounting portion 20 formed at the lower end.

<Hat type shape>
Next, the cross-sectional shape of the pillar outer member 10 will be described with reference to FIG. FIG. 4 schematically shows the shape of the IV-IV line cross section in FIGS. 1 and 2. As shown in FIG. 4, the cross section of the pillar outer member 10 is basically formed in a hat shape.

The hat-shaped shape is formed of a central top plate portion 24, flange portions 28 at both ends, and a side plate portion 26 connecting the top plate portion 24 and the flange portion 28. The side plate portion 26 extends from both ends of the top plate portion 24, and is composed of a left side plate portion 26L and a right side plate portion 26R as seen in FIG. The left and right

side plate portions

26L and 26R extend downward. That is, it is inclined in a trapezoidal shape.

The flange portion 28 extends in the left-right direction from the lower end portion of the side plate portion 26, and is composed of a left flange portion 28L and a right flange portion 28R. The left flange portion 28L is formed by connecting to the lower end of the left side plate portion 26L, and the right flange portion 28R is formed by connecting to the right side plate portion 26R. Although the pillar inner member is omitted in FIG. 1, the portion W where the pillar outer member 10 is welded to the pillar inner member is indicated by black dots on the

flange portions

28L and 28R.

As one embodiment, the pillar outer member 10 can be manufactured from a high-strength steel plate in order to increase its strength. As one embodiment, a steel sheet having a tensile strength of 1180 MPa can be used. A concave bead may be formed on the top plate portion 24 in order to increase the strength in shape. In FIG. 4, the concave bead is not shown.

<Hat depth>
As shown in FIG. 4, since the pillar outer member 10 has a hat-shaped cross-sectional shape after molding, a depth is formed by the side plate portion 26 between the top plate portion 24 and the flange portion 28. In the present application, this depth is referred to as "hat depth" and is represented by H. The hat depth H differs depending on the position of the pillar outer member 10 in the longitudinal direction. In the case of the pillar outer member 10 shown in FIG. 3, the hat depth H at the center in the vehicle height direction is the deepest, and the hat depth H gradually becomes shallower from the center toward the upper end or the lower end.

As one embodiment, the hat depth H can be changed according to the difference in the width of the top plate portion 24. For example, as shown in FIG. 2, the width of the top plate portion 24 is formed to be the widest in the center in the vehicle height direction, and correspondingly, the hat depth at this position is the widest as shown in FIG. It's getting deeper. The width of the top plate gradually narrows from the center toward the upper end and the lower end, and the hat depth also becomes shallower accordingly.

<Press molding process>
Next, a method of press-molding the pillar outer member 10 will be described with reference to FIGS. 5 and 6. Press molding can be performed by cold pressing and is divided into at least two press molding steps.

As one embodiment, the intermediate molded product S2 is molded in the first press molding step 12 shown in FIG. 5, and the final molded product S3 is molded in the second press molding step 14 shown in FIG. In each of FIGS. 5 and 6, in order to facilitate understanding, the press molds used in the press molding steps 12 and 14 are schematically shown, and in the order of progress of the molding process, the upper stage is before molding and the middle stage is. During molding, each stage after molding is shown in the lower row. In the upper figure before molding, the alternate long and short dash line indicates the position where the upper dies 30 and 40 are completely open, and the solid line indicates the position at the moment when the upper dies 30 and 40 descend and come into contact with the molding material S1. ..

<1st press molding process>
In the first press molding step 12 shown in FIG. 5, a "shallow drawing" process is performed in which the pillar outer member 10 is squeezed shallowly to about half the hat depth required, and an intermediate molded product S2 having a shallow hat depth is formed.

In the press apparatus used in the first press forming step 12, a die 32 is arranged as an upper die 30, a punch 36 and a blank holder 38 are arranged as a lower die 34. A flat plate-shaped molding material S1 is arranged between the molding surfaces of the die 32 and the punch 36 between the upper die 30 and the lower die 34, and the punch 36 and the die 32 move relative to each other (usually, the upper die 30 descends). Then, the molding material S1 is pressed to perform molding.

The upper part of FIG. 5 shows the state before molding of the first press molding step 12. In this state, the flat plate-shaped molding material S1 is held between the die 32 of the upper mold 30 and the blank holder 38, and is located on the upper surface of the punch 36 of the lower mold 34. In this state, the blank holder 38 is given an upward urging force by a pressurizing means (not shown), and the molding material S1 is held by the urging force on the blank holder 38. Therefore, the blank holder 38 is sometimes called a cushion. Examples of the pressurizing means for the blank holder 38 include spring means, rubber, a gas cylinder, a hydraulic cylinder, and the like.

As shown in the middle part of FIG. 5, the die 32 of the upper die 30 descends halfway while holding the molding material S1 in the blank holder 38. As a result, the molding material S1 hits the upper surface (molding surface) of the punch 36 of the lower mold 34, and is sequentially pressed by the punch 36. At this stage, the lower surface (molding surface) of the die 32 of the upper die 30 has not yet hit the molding material S1. Therefore, shallow drawing is performed on the side plate portion 26 of the pillar outer member 10.

As shown in the lower part of FIG. 5, the die 32 of the upper die 30 further lowers and moves to the lower limit position in the first press forming step 12. As a result, the molding material S1 is pressed between the die 32 of the upper mold 30 and the punch 36 of the lower mold 34 to complete the intermediate molding, and the intermediate molded product S2 is obtained.

In the middle and lower stages of FIG. 5, the virtual line drawn on the die 32 of the upper mold 30 indicates the position of the molding material S1 before molding shown in the upper stage. Therefore, by comparing the positions of the molding material S1 and the intermediate molded product S2 in the middle stage and the lower stage, it can be seen that the shape changes with the lowering of the upper mold 30 (die 32).

<Second press molding process>
Next, the second press molding step 14 shown in FIG. 6 will be described. The second press molding step 14 is a step of further molding the intermediate molded product S2 molded in the first press molding step 12 described above to form a pillar outer member which is the final molded product S3. That is, by the second press molding step 14, the hat depth of the hat-shaped shape in the pillar outer member becomes a predetermined depth of the final product shape.

In the press apparatus used in the second press molding step 14, a punch 46 and a blank holder 48 are arranged as the lower mold 44 in the same manner as in the first press molding step 12 described above. However, in the second press molding step 14, the pad 50 is arranged in addition to the die 42 as the upper die 40. The pad 50 is arranged corresponding to the position when the top plate portion 24 of the pillar outer member 10 is formed. A plurality of pads 50 can be divided and arranged.

The shape of the molding surface of the press mold in the second press molding step 14, particularly the shape forming the hat depth H, is the shape of the molding surface of the press mold in the first press molding step 12 for molding the intermediate molded product S2. Is different. As described above, the type of the mold to be arranged and the shape of the molding surface are different between the first press molding step 12 and the second press molding step 14.

In the second press molding step 14, the intermediate molded product S2 molded in the first press molding step 12 described above is arranged between the die 42 and the pad 50 of the upper die 40 and the punch 46 of the lower die 44. Molding is performed by relatively moving the upper mold 40 and the lower mold 44 (usually lowering the upper mold 40) and pressing the intermediate molded product S2. In the second press molding step 14, the positioning of the intermediate molded product S2 can be performed by using the press reference pin 52 set in the press mold described in detail below, which will be described later.

The upper part of FIG. 6 shows the state of the second press molding step 14 before molding. In this pre-molding state, the die 42 and pad 50 of the upper die 40 and the punch 46 of the lower die 44 are separated from each other with a space. Then, the intermediate molded product S2 molded in the first press molding step 12 described above is placed between the upper mold 40 and the lower mold 44. Specifically, the portion of the intermediate molded product S2 corresponding to the top plate portion 24 is positioned at a predetermined position on the upper surface (molded surface) of the punch 46.

Note that the pad 50 of the upper mold 40 and the blank holder 48 of the lower mold 44 in the state before molding are both subjected to urging force by a pressurizing means (not shown). A downward urging force is applied to the pad 50, and the relative position of the pad 50 with respect to the die 42 is at the lowermost end. An upward urging force is applied to the blank holder 48, and the position is at the uppermost end. Then, the intermediate molded product S2 is placed on the blank holder 48 at the uppermost position. As the pressurizing means, as described above, there are springs, rubbers, gas cylinders, hydraulic cylinders, and the like.

As shown in the middle part of FIG. 6, when the die 42 and the pad 50 of the upper mold 40 are lowered, the pad 50 first hits a position corresponding to the top plate portion 24 of the intermediate molded product S2 and is intermediate with the punch 46 of the lower mold 44. The top plate portion 24 of the molded product S2 is sandwiched. At the same time, the die 42 hits the position corresponding to the flange portion 28 of the intermediate molded product S2, and the position of the flange portion 28 of the intermediate molded product S2 is sandwiched by the blank holder 48 of the lower mold 44. That is, the intermediate molded product S2 is in a state of being gripped by the die 42 of the upper mold 40 and the blank holder 48 of the lower mold 44. At this stage, there is still space between the die 42 of the upper die 40 and the punch 46 of the lower die 44.

In the process from the upper stage to the middle stage of FIG. 6, the pad 50 is slightly retracted from the die 42. In other words, it can be said that the intermediate molded product S2 is processed by the die 42 by that amount. Specifically, bending in the longitudinal direction and drawing of the side plate portion 26 are performed.

As shown in the lower part of FIG. 6, when the upper mold 40 is further lowered and the intermediate molded product S2 is pressed until there is no space between the die 42 of the upper mold 40 and the punch 46 of the lower mold 44, the final molding is performed. Product S3 is obtained. As a result, the press molding of the pillar outer member 10 is completed.

In the process of reaching the state after molding, the die 42 of the upper die 40 is lowered to the lower limit position. Then, along with this lowering, the blank holder 48 of the lower mold 44 also lowers against the pressurizing means, but the state of gripping the flange portion 28 with the die 42 in the final molded product S3 is maintained.

Then, in the state of the above lower limit position, the molding of the final shape of the side plate portion 26 of the pillar outer member 10 is completed by the die 42 of the upper die 40 and the punch 46 of the lower die 44.

Further, the pad 50 of the upper die 40 also rises relative to the die 42 as the die 42 descends. This relative rise continues until there is no space between the die 42 of the upper die 40 and the punch 46 of the lower die 44. As a result, the top plate portion 24 of the pillar outer member 10 is formed into the final shape.

<Split pad and press reference pin>
Next, the divided arrangement of the pads 50 provided in the upper die 40 of the second press forming step 14, and the press reference pin 52 provided in the press die will be described.

7 to 9 show changes in shape from the molding material S1 to the final molded product S3 when molded by the above-mentioned press molding steps 12 and 14. FIG. 7 shows the molding material S1 before molding in the first press molding step 12 shown in FIG. 5 described above. FIG. 8 shows an intermediate molded product S2 in which molding in the first press molding step 12 is completed. FIG. 9 shows the final molded product S3 that has been molded in the second press molding step 14. In each of these figures, the arrangement relationship of the press reference pin 52, the press reference pin hole 54, and the plurality of pads 50 is shown.

FIG. 7 shows the molding material S1 provided in the first press molding step 12 shown in FIG. 5 described above. For example, it is a molding material S1 for manufacturing the pillar outer member 10 shown in FIGS. 1 to 2. The molding material S1 is a flat plate of a high-strength steel plate, and is formed in advance in a predetermined long blank shape. A press reference pin hole 54 is formed in the molding material S1 at a position corresponding to the press reference pin 52 (see FIGS. 8 and 9) described later. In the present embodiment, three press reference pin holes 54 are bored at intervals in the longitudinal direction. For convenience of explanation, the press reference pin hole 54 is referred to as a first reference pin hole 54a, a second reference pin hole 54b, and a third reference pin hole 54c in order from the right side when viewed in FIG. 7.

FIG. 8 shows a state in which the press reference pin 52 set in the press mold is fitted into the press reference pin hole 54 formed in the intermediate molded product S2 by the first press molding step 12. Three press reference pins 52 are also set in the press mold, and for convenience of explanation, they are referred to as a first reference pin 52a, a second reference pin 52b, and a third reference pin 52c in order from the right side when viewed in FIG. The first reference pin 52a fits into the first reference pin hole 54a, the second reference pin 52b fits into the second reference pin hole 54b, and the third reference pin 52c fits into the third reference pin hole 54c. ..

The press reference pin 52 provided in the press mold is used as a position reference during press molding. The press reference pin 52 is usually provided on the

lower molds

34 and 44. As one embodiment, the press reference pin 52 may be set on the punch 36 in the first press forming step 12 (see FIG. 5) and the punch 46 in the second press forming step 14 (see FIG. 6), respectively. can. As another embodiment, the setting of the press reference pin 52 in the first press forming step 12 in which the shallow drawing process is performed may be omitted. As yet another embodiment, the press reference pin 52 can be provided on the

upper molds

30 and 40.

In FIG. 9, a plurality of pads 50 for the intermediate molded product S2 and the final molded product S3 in the second press molding step 14 can be divided in the longitudinal direction and arranged (three in FIG. 9). In FIG. 9, the arrangement position of each pad 50 is shown in the shaded area. For convenience of explanation, these three pads 50 are referred to as a first pad 50a, a second pad 50b, and a third pad 50c in order from the right side when viewed in FIG.

As one embodiment, the pads 50 at a plurality of locations can be arranged so that the pads 50 arranged adjacent to each other are separated from each other in the longitudinal direction. That is, the first pad 50a and the second pad 50b are arranged at intervals in the longitudinal direction, and the second pad 50b and the third pad 50c are also arranged at intervals in the longitudinal direction. By arranging the pads at intervals, it is possible to prevent the divided pads 50 from interfering with each other during press molding.

The three pads 50 and the three press reference pins 52 are arranged as a pair. That is, a press reference pin 52 corresponding to each pad 50 that is divided and arranged is provided. In the present embodiment, the first pad 50a and the first reference pin 52a, the second pad 50b and the second reference pin 52b, and the third pad 50c and the third reference pin 52c are arranged as a pair. The

pads

50a, 50b, and 50c are provided with fitting holes 56 into which the reference pins 52a, 52b, and 52c are fitted. The first pad 50a is formed with a first fitting hole 56a, the second pad 50b is formed with a second fitting hole 56b, and the third pad 50c is formed with a third fitting hole 56c.

As shown in FIG. 10, as another embodiment, a plurality of press reference pins 52 may be arranged for one pad 50. For example, a fourth separate pin 52d may be arranged in addition to the third reference pin 52c with respect to the third pad 50c, and two press reference pins 52 may be arranged. With such an arrangement, the intermediate molded product S2 can be reliably positioned and placed at two points.

<Press molding by press mold with press reference pin and split pad set>
11 to 13 show an intermediate stage (see FIG. 6) of the second press molding step 14 when the above-mentioned

press reference pins

52a, 52b, 52c and the divided

pads

50a, 50b, 50c are used. It is a cross-sectional view. FIG. 11 shows a cross section taken along the line XI-XI of FIG. 9, FIG. 12 shows a cross section taken along the line XII-XII, and FIG. 13 shows a cross section taken along the line XIII-XIII. Note that FIG. 13 is cut at a position slightly deviated from the press reference pin 52c.

As shown in FIG. 11, the first reference pin 52a is integrally provided on the upper surface of the punch 46 in an upright state. Then, by fitting the first reference pin hole 54a formed in the intermediate molded product S2 into the first reference pin 52a, the intermediate molded product S2 is positioned with respect to the punch 46.

A first fitting hole 56a into which the first reference pin 52a is fitted is formed on the lower surface of the first pad 50a. By fitting the first reference pin 52a into the first fitting hole 56a, the punch 46, the intermediate molded product S2, and the pad 50 are positioned in the surface direction. That is, the relative positions in the direction orthogonal to the press forming direction (left-right direction as seen in FIG. 11) are aligned. The tighter the fitting between the first reference pin 52a and the first reference pin hole 54a formed in the intermediate molded product S2 and the first fitting hole 56a of the first pad 50a, the more accurately press molding can be performed. ..

Further, a downward urging force is applied to the first pad 50a by a pressurizing means (not shown) described above, and this urging force ensures that the intermediate molded product S2 is between the first pad 50a and the punch 46. It is pinched and descends.

The second reference pin 52b and the second pad 50b and the third reference pin 52c and the third pad 50c can be understood in the same manner.

11 to 13 show the stroke amount of the pad 50 required for molding from the intermediate molded product S2 to the final molded product S3 at each position of the XI-XI line, the XII-XII line, and the XIII-XIII line shown in FIG. Indicates t1 to t3. The stroke amounts t1 to t3 of the pad 50 are the amount of protrusion of the pad 50 from the upper mold 40 in the press direction before molding in the second press molding step (before contacting the intermediate molded product S2). The stroke amounts t1 to t3 of the

pads

50a, 50b, and 50c differ depending on the difference in the set positions of the

pads

50a, 50b, and 50c. It is determined corresponding to the hat depth H (see FIG. 4).

As one embodiment, as shown in FIG. 14, the stroke amount t is the hat depth (H1) in the final molded product S3 and the hat depth (H2) in the intermediate molded product S2 at the position where each pad is arranged. It is determined by. Specifically, the stroke amount t of the pad 50 is the difference (H1-H2) between the hat depth (H1) in the final molded product S3 and the hat depth (H2) in the intermediate molded product S2. As one embodiment, the positions that determine the hat depth (H1) in the final molded product S3 and the hat depth (H2) in the intermediate molded product S2 are the positions where the

press reference pins

52a, 52b, and 52c are set. Can be done.

As a result of determining the stroke amount t of the pad 50 as described above, even if the stroke amounts t1 to t3, that is, the hat depth H is different, the portion corresponding to the top plate portion 24 in the intermediate molded product S2 is gripped by the pad 50. , The portion corresponding to the flange portion 28 can be gripped by the blank holder 48 at the same time. This is because the pads 50 are divided into a plurality of pieces and arranged, and the amount of protrusion of the divided pads 50 from the die 42 can be set to different lengths. When the pads 50 are integrated, the top plate portion 24 and the flange portion 28 cannot be gripped at the same time during molding.

The urging force applied to each of the divided pads 50 can be set differently depending on the difference in the hat depth H and the difference in the stroke amounts t1 to t3. As a result, it is possible to effectively prevent the hole from being rolled up.

<Effect of embodiment>
As described above, the pillar outer member is formed by cold pressing of a high-strength steel plate. When a member having a relatively deep hat depth H such as the pillar outer member 10 is formed by deep drawing in one step, there is a problem that cracks and wrinkles occur. In the above-described embodiment, since the first press molding step 12 and the second press molding step 14 are divided into two steps, the occurrence of cracks and wrinkles can be minimized.

In particular, in the above-described embodiment, since the molding material S1 is first squeezed shallowly in the first press molding step 12, the movement of the material during press molding is small, and molding can be performed with high accuracy. Further, when the press reference pin is used in the shallow drawing molding, it is possible to suppress the formation of pores in the molding material.

Then, in the second press molding step 14, press molding is performed using the divided pads 50. As a result, even if the drawing depth (hat depth H) is not constant, the top plate portion 24 and the flange portion 28 of the intermediate molded product S2 are simultaneously grasped and bent from the start of the second press forming step 14. And the drawing can be processed. As a result, even when press molding is performed using the press reference pin 52, it is possible to prevent or suppress the formation of holes in the final molded product S3 due to the press reference pin 52.

<Other Embodiments>
Although there were two types of press molding steps in the above embodiment, as another embodiment, two or more types of press molding steps may be used.

Further, in the above embodiment, a plurality of pads arranged adjacent to each other in the longitudinal direction are arranged apart from each other, but as another embodiment, if the pads are not integrally connected, the adjacent pads are adjacent to each other. May be arranged so that the end faces of the above are in contact with each other.

Further, in the above embodiment, the number of pads 50 arranged is 3, but as another embodiment, 2 or 4 or more may be arranged.

Further, in the above embodiment, the pillar outer member 10 is manufactured by using a high-strength steel plate, but as another embodiment, a normal general steel plate may be used.

<Effect of embodiment>
Finally, the effects that the above-described embodiment can exert are added.

According to the above-described embodiment, the press molding of a long-shaped part formed by cold press molding includes a first press molding step of molding an intermediate molded product and a second press molding step of molding a final molded product. It is performed by two-step molding with. As a result, it is possible to prevent or suppress the occurrence of cracks and wrinkles in the press-molded product as much as possible, as compared with the case where a long-shaped part having a product depth (hat depth) is molded by one press molding. can.

In addition, the cross-sectional shape of the long-shaped part is a hat-shaped part, and the hat depth from the flange portion to the top plate portion of the hat-shaped shape differs depending on the position in the longitudinal direction. Then, in the second press molding step, a plurality of pads are divided and arranged in the longitudinal direction. Then, the amount of protrusion of each pad from the upper mold in the press molding direction at the beginning of molding in the second press molding step is set according to the hat depth at the position where the pad is arranged. As a result, from the beginning of molding in the second press molding step, the top plate portion of the press-molded product can be simultaneously gripped by the pad and the flange portion by the blank holder for molding. Further, the magnitude of the pressing force applied to the plurality of pads can be set to a predetermined magnitude. As a result, cracks and wrinkle molding defects in the final molded product can be more reliably prevented or suppressed.

Depending on the embodiment, the amount of pad protrusion is the difference (H1-H2) between the hat depth (H1) of the final molded product and the hat depth (H2) of the intermediate molded product at the position where each pad is arranged. be. Thereby, the above-mentioned effect can be achieved more appropriately.

Depending on the embodiment, a press reference pin is set in the press mold in the second press molding step, and this press reference pin is set in a pad which is divided and arranged. As a result, a press reference pin is set for each pad and press molding is performed. As a result, a press-molded product of a long-shaped part can be molded with high accuracy. Further, in this case, the pad is formed with a press reference pin hole into which the press reference pin is fitted. However, according to the pad arrangement described above, the press reference pin may appropriately prevent the press reference pin hole from being rolled up. It can be suppressed.

Depending on the embodiment, the hat depth (H1) in the final molded product and the hat depth (H2) in the intermediate molded product are set to the hat depth at the position where the press reference pin is set. As a result, the press reference pin can more appropriately and reliably prevent or prevent the press reference pin hole from being curled up.

Depending on the embodiment, the long-shaped part is manufactured by the above press molding method. As a result, a long-shaped part with high accuracy is provided.

Depending on the embodiment, the pillar member is manufactured by the above-mentioned press molding method. This provides a highly accurate vehicle pillar member.

Although specific embodiments have been described above, the present invention is not limited to these embodiments, and those skilled in the art will be able to make various modifications, substitutions, and improvements without deviating from the gist of the technique. ..

Claims

A method in which a long-shaped part having a hat-shaped cross-sectional shape orthogonal to the longitudinal direction and having a top plate portion in the center and flange portions at both ends is formed by cold pressing.
The hat depth corresponding to the distance from the flange portion to the top plate portion of the long-shaped part differs depending on the position in the longitudinal direction.
It has a plurality of press molding steps including at least a first press molding step of molding an intermediate molded product and a second press molding step of molding a final molded product, and the hat depth is formed by the plurality of press molding steps. Being done
The press mold in the second press molding step includes an upper mold and a lower mold, and a plurality of pads are arranged in the upper mold at positions corresponding to the top plate portion by dividing them in the longitudinal direction of the long-shaped part. A blank holder is arranged on the lower mold at a position corresponding to the flange portion.
A method in which the amount of protrusion of each pad from the upper die in the press molding direction at the start of the second press molding step is set according to the hat depth at the position where the pad is arranged.
The method according to claim 1.
The amount of protrusion of the pad at the start of the second press molding step is the difference H1 between the hat depth H1 of the final molded product and the hat depth H2 of the intermediate molded product at the position where the pad is arranged. -H2, the method.
The method according to claim 1 or 2.
A method in which a plurality of press reference pins are set in the press mold in the second press molding step, and the press reference pins are set in each of the plurality of pads.
The method according to claim 3.
A method, wherein the hat depth in the final molded product and the hat depth in the intermediate molded product are the hat depths at the positions where the press reference pins are set.
A long-shaped part molded by the method according to any one of claims 1 to 4.
The long-shaped part according to claim 5, wherein the long-shaped part is a pillar member for a vehicle.