JP7335198B2 - Press molding method for long shape parts, and vehicle pillar member molded by the same molding method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a press molding method for elongated parts, and a vehicle pillar member molded by the same molding method. In particular, the present invention relates to a two-stage press molding process comprising a first press molding process for molding an intermediate molded product and a second press molding process for molding a final molded product in which pads are provided as press dies.

2. Description of the Related Art Vehicle bodies such as automobiles are assembled using elongated parts manufactured by press molding. As such an elongated component, there is a vehicle pillar member arranged on the side of the vehicle body of the vehicle. A typical vehicle pillar member is a vehicle center pillar member. The vehicle center pillar member is also called a vehicle B-pillar member because it is the second pillar member from the front of the vehicle. Note that the vehicle center pillar member is also called a center pillar reinforcement.

A center pillar member for a vehicle is arranged in a vertically elongated form when viewed in the vehicle height direction, and is a press-formed product of high-strength steel plate, which is formed into a predetermined shape by cold press-forming. be done. The shape of the press-molded product of the center pillar member for a vehicle is a long shape with a hat-shaped cross section perpendicular to the long direction, with a top plate in the center and flanges and top plate at both ends. and a side plate portion connecting the flange portion.

The hat depth H between the top plate portion forming the side plate portion and the flange portion in the above-described hat-shaped shape varies depending on the longitudinal position of the vehicle center pillar member. A center pillar member for a vehicle is usually formed in a curved shape that protrudes slightly outward in the vehicle width direction in order to cope with a side collision or the like. The above-mentioned hat depth H differs at positions in the longitudinal direction of the curved shape. The hat depth also varies depending on the width of the top plate portion in the hat shape.

The forming of the vehicle center pillar member described above is usually performed by cold press forming. In press molding, so-called drawing and bending are performed because the cross-sectional shape of the molded product is a relatively deep hat-shaped shape.

In the conventional general press forming process, a high-strength steel plate (1180 MPa material) flat plate material is deep-drawn, and the product depth (hat depth H) of the press-formed product is obtained in one press forming. It is a molding process. In this press forming process, since the steel sheet is of high tensile strength, if the depth of the product (hat depth H) is obtained by one press forming, cracks and wrinkles may occur in the press formed product.

In addition, when the press molding is performed once as described above, the movement of the molding material during press molding is large. For this reason, a measure is adopted in which a press reference pin is used in the press die, a press reference pin hole is provided in the molding material, and the two are fitted together to suppress the movement of the molding material during press molding. However, when this measure is taken, the press reference pin hole of the material may be burred by the press reference pin during press molding.

In view of the above points, there is another problem that the variation in the accuracy of the outer shape becomes large when the press forming without the outer shape development is performed without using the press reference pin.

Therefore, various proposals have been made as measures for accurately forming elongated members. For example, there is a method of performing press molding in two stages (see Patent Document 1 below) and a method of dividing and arranging pads set in the press mold (see Patent Documents 1 and 2 below).

WO2014/050973 JP 2015-110237 A

As in the above-mentioned patent documents, various proposals have been made for cold press forming of elongated members such as center pillar members of vehicles such as automobiles with high accuracy. However, there is still a demand for a proposal for press-molding the final molded product with even higher accuracy and preventing or reducing molding defects in the final molded product. In particular, in the case of a long member having a hat-shaped cross-sectional shape and the product depth of the hat-shaped product (hat depth) is different in the longitudinal direction, it is possible to perform press molding using a pad with high accuracy. Proposals for press molding are desired.

Accordingly, the present invention was invented based on the above-mentioned requirements, and the problem to be solved by the present invention is to press a plurality of pads from a press die in a press molding process using a plurality of pads. To prevent or reduce defective molding by accurately molding a final molded product by setting the amount of protrusion in the molding direction in relation to the difference in molding depth due to the difference in the position where a pad is arranged. .

In order to solve the above problems, the press molding method for long shaped parts and the vehicle pillar member molded by the molding method according to the present invention employ the following means.

According to a first aspect of the present invention, the press-formed product is an elongated part having a hat-shaped cross section perpendicular to the longitudinal direction, a top plate in the center, and flanges at both ends. A press forming method for a long part, in which the press-formed product of the long part is formed by cold press forming, wherein the long part is formed from the hat-shaped flange portion to the top plate portion. The hat depth differs depending on the position in the longitudinal direction, and the molding of the hat depth is performed in a first press molding step for molding an intermediate molded product and a second press molding step for molding a final molded product. In the press mold in the second press molding step, the upper mold is provided with a pad at a position corresponding to the hat-shaped top plate portion, and the lower mold is provided with the pad. A blank holder is provided at a position corresponding to the hat-shaped flange portion to sandwich the press-formed product, and the pad is divided in the longitudinal direction of the long-shaped component and arranged in a plurality, The amount of protrusion in the press-molding direction from the upper mold of the pad at the beginning of molding in the second press-molding step is the position of the pad in the plurality of pads divided and arranged in the longitudinal direction. It is a press molding method for long shaped parts, which is set in relation to the difference in the hat depth due to the difference in .

A second aspect of the present invention is a method for press-molding a long-shaped component according to the first aspect, wherein the pad is pressed from the upper mold in the press-molding direction at the beginning of molding in the second press-molding step. The protrusion amount is the difference (H1-H2) between the hat depth (H1) in the final molded product and the hat depth (H2) in the intermediate molded product at the positions where the plurality of pads are arranged. This is a press molding method for long shaped parts.

A third invention of the present invention is a method for press-molding a long-shaped part according to the first invention or the second invention, wherein the press die in the second press-molding step includes the long-shaped part A press reference pin is set to the pad, and the press reference pin is set to the pad arranged in a divided manner.

A fourth aspect of the present invention is a method for press-molding a long-shaped component according to the third aspect, wherein the pad depth (H1 ) and the pad depth (H2) in the intermediate molded product is the position where the press reference pin is set, which is the press molding method of the elongated shaped part.

A fifth invention of the present invention is a long part manufactured by the press molding method for a long part according to any one of the first to fourth inventions.

A sixth aspect of the present invention is the elongated component of the fifth aspect described above, wherein the elongated component is a vehicle pillar member.

According to the means of the present invention described above, in a press-forming process using a plurality of pads, the protrusion amount of the plurality of pads from the press die in the press-forming direction is determined by the forming depth depending on the position where the pads are arranged. It is possible to accurately mold the final molded product and prevent or reduce molding defects by setting the values in relation to the differences in the values.

FIG. 2 is a perspective view of the vehicle center pillar member of the present embodiment as seen from the outside of the vehicle; It is the front view which looked at the center pillar member for the same vehicle from the vehicle exterior direction. It is a side view of the center pillar member for the same vehicle. FIG. 3 is a cross-sectional view schematically showing a cross section taken along line IV-IV in FIGS. 1 and 2; It is a figure which shows the shaping|molding state of a 1st press molding process later on. It is a figure which shows the shaping|molding state of a 2nd press molding process later on. FIG. 3 is a perspective view showing a molding material for the vehicle center pillar member; FIG. 3 is a perspective view showing an intermediate molded product of the vehicle center pillar member; FIG. 3 is a perspective view showing a final molded product of the vehicle center pillar member. FIG. 10 is a diagram showing a modification in which a plurality of press reference pins are arranged on one pad; FIG. 10 is a diagram schematically showing a molding state by a press mold in the XI-XI line cross section of FIG. 9; FIG. 10 is a diagram schematically showing a molding state by a press mold in the XII-XII line cross section of FIG. 9; FIG. 10 is a diagram schematically showing a molding state by a press mold in the XIII-XIII cross section of FIG. 9; It is a figure which shows hat depth typically.

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

First, an elongated component of a press-formed product to be formed in the press-forming process of the present embodiment will be described. The elongated component molded in the press molding process of the present embodiment is the center pillar member 10 for a vehicle. In the description of the vehicle center pillar member 10, the directions shown in each drawing indicate the directions in the normal posture of a vehicle such as an automobile. Arrow FR indicates the forward direction of the vehicle, arrow UP indicates the upward direction of the vehicle, and arrow IN indicates the inner direction in the vehicle width direction. In the following description, descriptions regarding directions are given with reference to this direction. In addition, when components are present on the left and right sides in the drawing, when referring to the left and right components individually, L is added to the end of the symbol indicating the component, and the component on the left side in the drawing is added, Components on the right are marked with an R.

<Vehicle center pillar member 10>
FIG. 1 shows a perspective view of a vehicle center pillar member 10 viewed from the outside of the vehicle, FIG. 2 shows a front view, and FIG. 3 shows a side view. The vehicle center pillar member 10 in FIG. 1 is installed on the left side of the traveling direction of a vehicle such as an automobile. As described in the background art above, pillar members are arranged on the sides of a vehicle such as an automobile as a mounting structure of the vehicle body. The pillar members include, from the front of the automobile, a front pillar member commonly called an A pillar, a center pillar member commonly called a B pillar, and a rear pillar member commonly called a C pillar. The pillar member of this embodiment is a vehicle center pillar member 10 called a B pillar.

As shown in FIG. 1, the vehicle center pillar member 10 is arranged in an elongated shape extending in the vertical direction of the vehicle. That is, it is arranged as an elongated member. Since the vehicle center pillar member 10 is a structural member that functions as a strength member in the event of a side collision (side collision) of the vehicle, it is configured to have a high strength. For this reason, normally, in a partial range in the longitudinal direction where the side impact load acts, it is formed with a convex curvature shape with respect to the direction in which the side impact load acts, thereby improving the strength.

In this embodiment, about the upper half range of the elongated form shown in FIG. That is, the range A shown in FIG. 1 is the range formed in such a shape, and is formed in a curved shape protruding outward from the vehicle. This curved shape is best shown in the side view of FIG.

Approximately the lower half of the elongated shape of the vehicle center pillar member 10 has a linear configuration as shown in the side view of FIG. This range is indicated by B in FIGS.

In addition, the vehicle center pillar member 10 is generally composed of a pillar inner member disposed on the inner side when viewed in the vehicle width direction, and a pillar outer member disposed on the outer side. Then, the pillar inner member and the pillar outer member are superimposed to form an integrated assembly member. 1 to 3, only the pillar outer member is shown for illustration purposes. Therefore, in this embodiment, the pillar outer member will be described as the vehicle center pillar member 10 . The vehicle center pillar member 10 is sometimes called a center pillar reinforcement. In addition, the locations indicated by black dots in FIG. 1 indicate locations where the pillar inner member and the pillar outer member are integrated by welding W. As shown in FIG.

2, the vehicle center pillar member 10 is arranged in an inclined shape such that the upper end position is located rearward of the vehicle from the lower end position, as well shown in FIG. The vehicle center pillar member 10 is joined to the roof side rail 18 via a substantially T-shaped mounting portion 16 formed at the upper end. It is also joined to a side sill 22 via a substantially T-shaped mounting portion 20 formed at the lower end.

<Hat shape>
Next, the cross-sectional shape of the vehicle center pillar 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. In FIG. As shown in FIG. 4, the cross-sectional shape of the vehicle center pillar member 10 is formed as a hat-shaped basic shape.

As seen in FIG. 4, the hat-shaped shape is formed with a top plate portion 24 at the central portion, flange portions 28 at both end portions, and side plate portions 26 connecting the top plate portion 24 and the flange portions 28 . The side plate portions 26 are formed so as to hang down from both ends of the top plate portion 24, and are composed of a left side plate portion 26L and a right side plate portion 26R as viewed in FIG. The left and right side plate portions 26L and 26R are formed to expand downward. That is, as seen in FIG. 4, it is formed in a mountain-like inclined 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 in connection with the lower end of the left side plate portion 26L, and the right flange portion 28R is formed in connection with the right side plate portion 26R.

A high-strength steel plate is used for the center pillar member 10 of the present embodiment in order to increase its strength. In this embodiment, a material having a tensile strength of 1180 MPa is used. In addition, concave beads may be formed in the top plate portion 24 in order to increase the strength in terms of shape. Illustration of the concave bead is omitted in FIG.

<Hat depth H>
As shown in FIG. 4, the center pillar member 10 has a hat-shaped cross section. It has a shape with This depth is referred to herein as the "hat depth" and is denoted by H. The depth of the hat depth H varies depending on the position of the center pillar member 10 in the longitudinal direction. In the case of the center pillar member 10 illustrated in FIG. 3, the hat depth H is the deepest at the center position in the height direction, and the hat depth H gradually increases from the center position toward the upper end position or the lower end position. is shallower.

Also, the hat depth H differs depending on the width of the top plate portion 24 . As shown in FIG. 2, the width of the top plate 24 is widest at the central position in the height direction, and the hat depth H at this position is the deepest as shown in FIG. . The width of the top plate portion gradually narrows from the central position toward the upper end position or the lower end position, and the hat depth H becomes shallow accordingly.

<Press molding process>
Next, a press molding process for press molding the center pillar member 10 will be described. The press-molding process in the present invention is cold press-molding, and two types of press-molding processes are performed. This embodiment is performed in a first press-molding process 12 and a second press-molding process 14 . FIG. 5 shows the first press-molding step 12, and FIG. 6 shows the second press-molding step 14. As shown in FIG.

An intermediate molded product S2 is molded in a first press molding process 12 shown in FIG. 5, and a final molded product S3 is molded in a second press molding process 14 shown in FIG. In order to facilitate understanding, both FIGS. 5 and 6 schematically show the press dies used in each of the press forming steps 12 and 14, and the figures before forming (top dead center) are shown in the order of progress of the forming process. The middle row shows the state during molding, and the lower row shows the state after molding (bottom dead center). In addition, in the illustration of the state before molding (top dead center) in the upper stage, the state where the upper molds 30 and 40 are indicated by a two-dot chain line is the top dead center state, and the solid line position of the upper molds 30 and 40 is the upper mold 30. , 40 descends and contacts the forming material S1.

<First press molding step 12>
First, the first press molding step 12 shown in FIG. 5 will be described. In this embodiment, in the first press-molding step 12, the center pillar member 10 is press-molded so that the hat depth H of the hat-shaped shape is about half. That is, an intermediate molded product S2 having a shallow hat depth H is molded. Since the first press forming step 12 is draw forming, the present inventors call the forming in the first press forming step 12 "shallow drawing".

As press dies for the first press molding step 12 , a die 32 is arranged as an upper die 30 and a punch 36 and a blank holder 38 are arranged as a lower die 34 . A flat forming material S1 is placed between the forming 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 (the upper die 30 moves downward). Press molding is thus performed. The first press molding step 12 will be described in order below.

<State before molding in first press molding step 12>
The illustrated state in the upper part of FIG. 5 shows the state before forming (top dead center) in the first press forming step 12 . In this pre-forming state, the flat forming material S1 is held between the die 32 of the upper die 30 and the blank holder 38 and positioned on the upper surface of the punch 36 of the lower die 34 . In this state, the blank holder 38 is given an upward biasing force by a pressure means (not shown), and the molding material S1 is held by the biasing force to the blank holder 38 . The pressurizing means for the blank holder 38 includes spring means, rubber, gas cylinders, hydraulic cylinders, and the like. For this reason, the blank holder 38 is sometimes called a cushion.

<Molding state in the first press molding step 12>
The illustrated state in the middle of FIG. 5 shows a state in the middle of forming in the first press forming step 12 . This intermediate molding state is a state in which the die 32 of the upper mold 30 moves downward while holding the molding material S1 in the blank holder 38 . In this state, the molding material S1 hits the upper surface (molding surface) of the punch 36 of the lower mold 34 and is pressed by the punch 36 in sequence. In this state, the lower surface (molding surface) of the die 32 of the upper mold 30 is not in contact with the molding material S1. Therefore, in this state, the intermediate draw forming of the side plate portion 26 of the vehicle center pillar member 10 is performed.

<State after molding in first press molding step 12>
The illustrated state in the lower part of FIG. 5 shows the state after forming in the first press forming step 12 (bottom dead center). This post-forming state indicates a state in which the above-described intermediate forming state has progressed and the die 32 of the upper die 30 has moved to the bottom dead center in the first press-forming step 12 . In this state, the molding material S1 in the middle of molding shown in the middle stage is sandwiched between the die 32 of the upper mold 30 and the punch 36 of the lower mold 34, and the intermediate molding is completed, and the molding of the intermediate molded product S2 is completed. .

In the illustrated states shown in the middle and lower stages of FIG. 5, the position of the straight line indicated by the imaginary line at the position of the die 32 of the upper die 30 indicates the position of the molding material S1 in the pre-molding state shown in the upper stage. Therefore, the illustrated states of the molding material S1 and the intermediate molded product S2 shown in the middle and lower stages show the molding change state from the imaginary line state accompanying the downward movement of the upper die 30 (die 32).

<Second press molding step 14>
Next, the second press molding step 14 shown in FIG. 6 will be described. This second press molding process 14 is a process of molding the intermediate molded product S2 formed in the first press molding process 12 into the final molded product S3 of the vehicle center pillar member 10 . That is, in the second press molding step 14, the hat depth H of the hat-shaped shape of the center pillar member 10 is formed to a predetermined depth of the final product shape.

As the press die for the second press-molding step 14, a lower die 44 is provided with a punch 46 and a blank holder 48 in the same manner as in the first press-molding step 12 described above. As the upper die 40 , a pad 50 is also provided in addition to the die 42 in the second press molding step 14 . The pad 50 is arranged corresponding to the position when the top plate portion 24 of the center pillar member 10 is molded. A plurality of pads 50 are divided and arranged. The layout of the pads 50 is a feature of this embodiment, and will be described in detail later.

The shape of the molding surface of the press mold in the second press molding step 14, particularly the shape that forms 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 product S2. is different from Thus, the first press-molding step 12 and the second press-molding step 14 are different in the type of molds provided and the shape of the molding surface.

In the second press molding step 14, the intermediate product S2 molded in the first press molding step 12 is placed between the molding surfaces between the die 42 and pad 50 of the upper mold 40 and the punch 46 of the lower mold 44. Press molding is performed by relative movement of the upper mold 40 and the lower mold 44 (downward movement of the upper mold 40). In the second press molding step 14, the molding of the intermediate molded product S2 by the pad 50 of the upper mold 40 is performed using a press reference pin 52 set in the press mold, which will be described in detail later. ing. However, in the description of the second press forming step 14 shown in FIG. 6, the press reference pin 52 is omitted. The second press molding step 14 will be described in order below.

<State before molding in second press molding step 14>
The illustrated state in the upper part of FIG. 6 shows the state before forming (top dead center) in the second press forming step 14 . In this pre-molding state, the die 42 and pad 50 of the upper mold 40 and the punch 46 of the lower mold 44 are spaced apart from each other. Between the two 40 and 44, the intermediate product S2 formed in the first press forming step 12 is placed. Specifically, the top plate portion 24 of the intermediate molded product S2 is positioned and placed on the upper surface (molding surface) of the punch 46 .

In this state before molding (top dead center), both the pad 50 of the upper die 40 and the blank holder 48 of the lower die 44 are biased by a pressing means (not shown). A downward biasing force is applied to the pad 50 to bring the pad 50 to the lowest position when viewed relative to the die 42 . An upward biasing force is applied to the blank holder 48, and this position is the uppermost position. This uppermost position is the position of the blank holder 48 when the intermediate molded product S2 is placed. As mentioned above, the pressurizing means includes spring means, rubber, gas cylinders, hydraulic cylinders, and the like.

<Molding state in the second press molding step 14>
The illustrated state in the middle of FIG. 6 shows a state in the middle of forming in the second press forming step 14 . In this intermediate molding state, the die 42 of the upper mold 40 and the pad 50 move downward, the pad 50 contacts the top plate portion 24 of the intermediate molded product S2, and the punch 46 of the lower mold 44 moves the intermediate molded product. The position of the top plate portion 24 of S2 is sandwiched. At the same time, the die 42 contacts the position of the flange portion 28 of the intermediate molded product S2, and the flange portion 28 of the intermediate molded product S2 is sandwiched between the blank holder 48 of the lower mold 44 and the die 42. That is, the intermediate molded product S2 is held by the die 42 of the upper mold 40 and the blank holder 48 of the lower mold 44. As shown in FIG. In this state, there is still a molding space between the die 42 of the upper mold 40 and the punch 46 of the lower mold 44 .

In the above state, the positional relationship between the pad 50 of the upper die 40 and the die 42 is different from the position of the pad 50 in the press operation direction (vertical direction in the figure) with respect to the state before molding in the upper illustrated state. is positioned slightly backward relative to the position of the die 42 . In other words, the intermediate molded product S2 is press-molded by the die 42 to that extent. Specifically, the bending of the side plate portion 26 is performed accordingly.

<State after molding in second press molding step 14>
The illustrated state in the lower part of FIG. 6 shows the state after forming in the second press forming step 14 (bottom dead center). This post-molding state indicates a state in which the above-described intermediate molding state progresses, and molding is performed until there is no molding space between the die 42 of the upper mold 40 and the punch 46 of the lower mold 44, and the final molded product S3 is formed. . This completes the press molding of the vehicle center pillar member 10 .

In the post-molding state described above, the die 42 of the upper die 40 moves to the lowest dead center position in the press molding direction (downward in FIG. 6) with respect to the punches 46 of the lower die 44 . Along with this, the blank holder 48 of the lower mold 44 is also moved downward relative to the punch 46 against the pressure means, and the gripping state of the flange portion 28 with the die 42 in the final molded product S3 is changed. To position.

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

The pad 50 of the upper die 40 also moves upward relative to the die 42 as the die 42 moves downward. This upward movement is performed until the molding space between the die 42 of the upper mold 40 and the punch 46 of the lower mold 44 is exhausted. Thereby, the final shape of the top plate portion 24 of the vehicle center pillar member 10 is formed.

<Pad 50 and press reference pin 52>
Next, a press molding method in which a plurality of pads 50 are arranged in the upper die 40 of the second press molding step 14 and press molding is performed using a press reference pin 52 in the press die, which is a feature of the present embodiment, will be described. do.

7 to 9 show changes in the molded shape from the molding material S1 to the final molded product S3 when molded by the press molding steps 12 and 14 described above. That is, the change process of the molding shape of the vehicle center pillar member 10 is shown. FIG. 7 shows the forming material S1 placed before forming (top dead center) in the first press forming step 12 shown in FIG. FIG. 8 shows an intermediate product S2 molded in the first press molding step 12. As shown in FIG. FIG. 9 shows the final molded product S3 molded in the second press molding step 14. As shown in FIG. It should be noted that each of these figures shows the arrangement relationship of the press reference pin 52, the press reference pin hole 54, and the plurality of pads 50. As shown in FIG. A description will be given below in order.

FIG. 7 shows the molding material S1 provided for the first press molding step 12 shown in FIG. 5 described above. That is, it is the molding material S1 for the vehicle center pillar member 10 shown in FIGS. The forming material S1 is a flat plate of high-strength steel plate, and is formed in advance into a predetermined long blank shape. A press reference pin hole 54 for a press reference pin 52 (see FIGS. 8 and 9), which will be described later, is formed in the molding material S1. In this embodiment, three press reference pin holes 54 are provided at intervals in the longitudinal direction. For convenience of explanation, the press reference pin holes 54 are 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 in FIG.

FIG. 8 shows a state in which the press reference pin 52 set in the press die is fitted with the press reference pin hole 54 formed in the intermediate product S2 formed in the first press molding step 12. FIG. Three press reference pins 52 are also set in the press die, and for convenience of explanation, they are designated as a first reference pin 52a, a second reference pin 52b, and a third reference pin 52c from the right side 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 setting of the press reference pin 52 to the press die is set so that press molding is performed using the press reference pin 52 as a positional reference. In this embodiment, it is set to the punch 36 in the first press-molding step 12 (see FIG. 5) and the punch 46 in the second press-molding step 14 (see FIG. 6). The setting of the press reference pin 52 in the first press forming process 12 for shallow drawing may be omitted.

FIG. 9 shows how the pads 50 are arranged with respect to the intermediate molded product S2 and the final molded product S3 in the second press molding step 14. As shown in FIG. In FIG. 9 , the positions of the pads 50 are schematically shown by hatched areas, and the structural form of the pads 50 is not shown. On the other hand, as shown in FIG. 9, the pads 50 are divided in the longitudinal direction and arranged at a plurality of locations, and in this embodiment, divided into three locations. 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 as viewed in FIG.

In this embodiment, the pads 50 at a plurality of locations are arranged so that adjacent pads 50 are separated from each other in the longitudinal direction. That is, the first pad 50a and the second pad 50b are arranged with a gap in the longitudinal direction, and the second pad 50b and the third pad 50c are also arranged with a gap in the longitudinal direction. By arranging the pads 50 at intervals, the divided pads 50 can be arranged without interfering with each other.

In this embodiment, the three pads 50 and the three press reference pins 52 are arranged as pairs. That is, there is a relationship in which the press reference pin 52 is set for each pad 50 that is divided and arranged. In this 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 pairs. Each pad 50a, 50b, 50c is provided with a fitting hole 56 into which each reference pin 52a, 52b, 52c is fitted. A first fitting hole 56a is formed in the first pad 50a, a second fitting hole 56b is formed in the second pad 50b, and a third fitting hole 56c is formed in the third pad 50c.

As described above, the basic form of this embodiment is such that one press reference pin 52 is arranged for one pad 50 . However, as a modification, a plurality of press reference pins 52 may be arranged for one pad 50 . The modification shown in FIG. 10 is an example in which a fourth separate pin 52d is arranged in addition to the third reference pin 52c for the third pad 50c, and two press reference pins 52 are arranged. By adopting such an arrangement form, the pad 50 can be reliably positioned and arranged at two points, and the press die structure can be simplified.

<Press molding with a press die in which the press reference pin 52 and the pad 50 are set>
Next, the state of press molding by a press die will be described with reference to FIGS. 11 to 13. FIG. The press reference pin 52 is normally set on the lower dies 34, 44 of the press die. 11 to 13 are provided with the pads 50. Therefore, when the pad 50 is provided on the upper die 40 shown in FIG. 9 and the intermediate molded product S2 is molded into the final molded product S3 is. Therefore, description will be made with reference to FIG. 9 as necessary.

FIG. 11 shows the state of molding by the press mold in the XI-XI line cross section of FIG. FIG. 12 also shows the state of molding by the press mold in the XII-XII cross section of FIG. FIG. 13 also shows the state of molding by the press mold in the XIII-XIII cross section of FIG. The press-molding states shown in these figures illustrate stages in the middle of molding in the second press-molding step 14 shown in FIG.

FIG. 11 is a cross section taken along line XI-XI of FIG. 9, and shows a state of press molding using the first reference pin 52a and the first pad 50a. As shown in FIG. 11, the first reference pin 52a is integrally provided on the upper surface of the punch 46 in a standing state. A first reference pin hole 54a formed in the intermediate molded product S2 is fitted into the first reference pin 52a and positioned, whereby the intermediate molded product S2 is positioned with respect to the punch .

A first fitting hole 56a into which the first reference pin 52a is fitted is formed in 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 plane direction. That is, the relative position in the direction orthogonal to the press forming direction (horizontal direction as viewed in FIG. 11) is determined. Therefore, by tightly fitting the first reference pin 52a, 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 precision can be improved. It can be press molded well.

A downward biasing force is applied to the first pad 50a by the aforementioned pressure means (not shown), and this biasing force ensures that the intermediate molded product S2 is positioned between the first pad 50a and the punch 46. It is in a state of being sandwiched and moving downward.

FIG. 12 is a cross section taken along the line XII-XII of FIG. 9 and shows a state of press molding using the second reference pin 52b and the second pad 50b. Since the contents are basically the same as those in FIG. 11, the detailed description is omitted by attaching the corresponding reference numerals.

Although FIG. 13 is a cross section taken along the line XIII-XIII of FIG. 9 and shows a position where the press reference pin 52 is not set, the method of press molding using the third pad 50c is the same. Therefore, the contents thereof are the same as those of FIGS. 11 and 12 described above, and therefore detailed description thereof will be omitted by assigning corresponding reference numerals.

Note that t1 to t3 of the pad 50 shown in FIGS. 11 to 13 indicate the press stroke t of the pad 50. FIG. That is, the press strokes t1 to t3 are the press strokes t (see FIG. 14) of the pad 50 for forming the final molded product S3 from the intermediate molded product S2 at the cross-sectional positions shown in FIG. 9 corresponding to FIGS. be. The press strokes t1 to t3 of the pad 50 are the amount of projection of the pad 50 from the upper die 40 in the press molding direction at the beginning of molding in the second press molding process. The press strokes t1 to t3 of the respective pads 50a, 50b, 50c differ due to differences in the set positions of the respective pads 50a, 50b, 50c. That is, the press stroke t of each pad 50a, 50b, 50c is determined corresponding to the hat depth H (see FIG. 4) of the hat shape at the position where each pad 50a, 50b, 50c is set.

The press stroke t in this embodiment is determined by the hat depth (H1) in the final molded product S3 and the hat depth (H2) in the intermediate molded product S2 at the positions where each pad is arranged. Specifically, the press stroke 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. FIG. 14 schematically illustrates this. In this embodiment, the settings determine the hat depth (H1) of the final molded product S3 and the hat depth (H2) of the intermediate molded product S2 at the positions where the plurality of pads 50a, 50b, and 50c are arranged. The positions are the positions where the press reference pins 52a, 52b, and 52c are set.

In this embodiment, as a result of the press stroke t of the pad 50 being determined as described above, as shown in FIGS. , the position corresponding to the top plate portion 24 in the intermediate molded product S2 can be gripped by the pad 50, and the position 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 the protruding amounts of the divided pads 50 from the die 42 can be set to different lengths. If the pad 50 is integral, the top plate portion 24 and the flange portion 28 cannot be gripped at the same time during molding.

In this embodiment, the urging force applied to the divided pad 50 can be set differently depending on the difference in the hat depth H and the difference in the press strokes t1 to t3. And thereby, prevention of burr hole can be performed appropriately.

<Action and effect of the present embodiment>
Next, the effect of this embodiment mentioned above is demonstrated.

First, in the present embodiment, a center pillar member for a vehicle is press-formed by cold press-forming using a high-strength steel plate. When this is performed in one molding process and deep drawing is performed with a relatively deep product depth (hat depth H) such as the vehicle center pillar member 10, there is a problem that cracks and wrinkles are generated. In this embodiment, since the first press-molding step 12 and the second press-molding step 14 are performed separately, cracks and wrinkles are prevented as much as possible.

In particular, in the present embodiment, shallow drawing is performed in the first press forming step 12 to shallowly draw the forming material S1, so that the movement of the material during press forming is small, and the forming can be performed with high accuracy. In addition, even when shallow drawing is performed using a press reference pin, so-called burrs do not occur in the molding material.

Then, in the second press molding step 14, the divided pad 50 is used for press molding. As a result, even if the grip bending depth (hat depth H) is not constant, the top plate portion 24 and the flange portion 28 of the intermediate molded product S2 can be gripped at the same time from the start of the second press forming step 14. Bending press molding is possible. As a result, even when the press reference pin 52 is used for press molding, it is possible to prevent or suppress the occurrence of burrs caused by the press reference pin 52 in the final molded product S3.

<Other embodiments>
While specific embodiments of the invention have been described above, the invention may be embodied in many other forms.

For example, the above embodiment was the case of the vehicle center pillar member 10 . However, it is also applicable to other vehicle pillar members, for example, the first A-pillar member and the third C-pillar member from the front of a vehicle such as an automobile. Furthermore, it is widely applicable to elongated members having a hat-shaped cross section. For example, it can also be applied to a bumper reinforcement of a bumper device mounted on the front or rear portion of the vehicle body of a vehicle such as an automobile.

Further, although there are two kinds of press-molding steps in the above embodiment, two or more kinds of press-molding steps may be used.

In the above-described embodiment, the plurality of pads arranged adjacent to each other in the longitudinal direction are arranged with a space therebetween. Arrangement form may be sufficient.

Also, in the above embodiment, the number of pads 50 arranged is three in the longitudinal direction, but may be two or four or more.

Further, in the above-described embodiment, the vehicle center pillar member 10 uses a high-strength steel plate, but it may be a normal steel plate.

<Effects of each invention described in "Means for Solving the Problems">
Finally, the effects of the above-described embodiments corresponding to the inventions in the above-described "Means for Solving the Problems" will be added.

First, according to the first invention, press forming of a long shaped part formed by cold press forming includes a first press forming step for forming an intermediate formed product and a second press forming step for forming a final formed product. It is performed by two-stage molding with a molding process. This makes it possible to prevent or suppress the occurrence of cracks and wrinkles in the press-formed product as much as possible, compared to the case where a long-shaped part having a product depth (hat depth) is formed by a single press-molding. can.

Further, the cross-sectional shape of the elongated component in the first invention is a hat shape, and the depth of the hat from the flange portion to the top plate portion of the hat 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. The amount of pad protrusion in the press molding direction from the upper mold at the beginning of molding in the second press molding step is set in relation to the depth of the hat at the position where the pads divided in the longitudinal direction are arranged. be done. Thereby, from the beginning of molding in the second press molding step, the top plate portion of the press-molded product can be gripped by the pad and the flange portion can be gripped by the blank holder at the same time. Further, the magnitude of the pressure applied to each of the pads can be set to a predetermined magnitude. As a result, it is possible to more reliably prevent or suppress molding defects such as cracks and wrinkles in the final molded product.

Next, according to the second invention, the protrusion amount of the pads in the first invention is determined by the hat depth (H1) in the final molded product at the position where each pad is arranged and the hat depth (H1) in the intermediate molded product. H2) is the difference (H1-H2). This makes it possible to more appropriately achieve the effects of the first invention described above.

Next, according to the third invention, a press reference pin is set in the press die in the second press molding step, and this press reference pin is set in a pad that is divided and arranged. As a result, a press reference pin is set for each pad and press molding is performed. As a result, it is possible to accurately form a press-formed long-shaped component. In this case, the press reference pin hole into which the press reference pin is fitted is formed in the pad. , can be adequately prevented or suppressed.

Next, according to the fourth invention, the positions where the hat depth (H1) of the final molded product and the hat depth (H2) of the intermediate molded product are measured are the positions where the press reference pins are set. As a result, it is possible to more appropriately and reliably prevent or suppress the bending of the press reference pin hole by the press reference pin.

Next, according to the fifth invention, the elongated component is produced by any one of the press molding methods of the first invention to the fourth invention. This provides an elongated component with good accuracy.

Next, according to the sixth invention, a vehicle pillar member is produced by any one of the press molding methods of the first to fourth inventions. Accordingly, a highly accurate vehicle pillar member is provided.

10 Vehicle center pillar member (long shaped part)
12 first press forming process 14 second press forming process 16 mounting portion 18 roof side rail 20 mounting portion 22 side sill 24 top plate portion 26 side plate portion 26L left side plate portion 26R right side plate portion 28 flange portion 28L left flange portion 28R Right flange portion 30 Upper mold (for the first press molding process)
32 die (for the first press molding process)
34 lower mold (for first press molding process)
36 punch (for the first press molding process)
38 blank holder (for first press molding process)
40 upper mold (for the second press molding process)
42 die (for the second press molding process)
44 Lower mold (for second press molding process)
46 punch (for second press molding process)
48 blank holder (for second press molding process)
50 pad 50a first pad 50b second pad 50c third pad 52 press reference pin 52a first reference pin 52b second reference pin 52c third reference pin 54 press reference pin hole 54a first reference pin hole 54b second reference pin hole 54c Third reference pin hole 56 Fitting hole 56a First fitting hole 56b Second fitting hole 56c Third fitting hole H Hat depth S1 Molding material S2 Intermediate molded product S3 Final molded product t Pad press stroke

Claims (5)

The press-formed product is an elongated part having a hat-shaped cross section orthogonal to the longitudinal direction and having a top panel in the center and flanges at both ends. A press molding method for long-shaped parts, in which a molded product is molded by cold press molding,
The hat depth from the hat-shaped flange portion to the top plate portion of the elongated component differs depending on the position in the longitudinal direction,
Forming the hat depth is formed by a plurality of press forming steps of a first press forming step for forming an intermediate formed product and a second press forming step for forming a final formed product,
In the press mold in the second press molding step, the upper mold is provided with a pad at a position corresponding to the hat-shaped top plate portion, and the lower mold is provided with a pad corresponding to the hat-shaped flange portion. A blank holder that sandwiches the press-formed product is arranged at the position,
The pad is divided in the longitudinal direction of the elongated part and arranged in plurality,
The amount of protrusion in the press-molding direction from the upper mold of the pad at the beginning of molding in the second press-molding step is the position of the pad in the plurality of pads divided and arranged in the longitudinal direction. A press molding method for long shaped parts, which is set in relation to the difference in the hat depth due to the difference in the hat depth. A press molding method for a long-shaped part according to claim 1,
The protrusion amount of the pad from the upper mold in the press-molding direction at the beginning of the molding in the second press-molding step is the hat depth (H1) of the final molded product at the position where each of the plurality of pads is arranged. A press molding method for long-shaped parts, which is the difference (H1-H2) from the hat depth (H2) in the intermediate molded product. A press molding method for a long-shaped part according to claim 1 or claim 2,
The press die in the second press molding step is provided with a press reference pin for the elongated component, and the press reference pin is set in the divided pad. Part press molding method. A press molding method for a long-shaped part according to claim 3,
The setting positions that determine the hat depth (H1) in the final molded product and the hat depth (H2) in the intermediate molded product at the positions where the plurality of pads are arranged are the positions at which the press reference pins are set. A press molding method for long shaped parts. A press molding method for a long-shaped part according to claim 1 ,
The elongated part is a press molding method for an elongated part that is a pillar member for a vehicle.

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