Press forming method for T-shaped press parts and T-shaped press-formed parts

Abstract

To increase a length of a press molding surface at a plate-like portion in a second component forming part to prevent or inhibit occurrence of wrinkles in the second component forming part in a first press molding step.SOLUTION: A press molding method of a T-shaped press molding component, such as a center pillar 10, includes a first press molding step and a second press molding step to perform molding. In the first press molding step, a specific area range Y of a second component forming part B in an area where a first component forming part A extends from an end of the first component forming part A in the T shaped press molding component X in a second component forming part B direction is press-molded as a protruding shape having a height that protrudes to the upper side relative to a height position of a top plate part 24 of the first component forming part A.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a press forming method for a T-shaped pressed part and a T-shaped press-formed part. In particular, the present invention is directed to a T-shaped press-formed part that is an upper position forming member of a center pillar constituting a side frame of an automobile.

Background Art

[0002] As a member constituting a frame of a vehicle such as an automobile, there is a T-shaped press-formed part. For example, the upper position forming member of a center pillar constituting a side frame of an automobile is a T-shaped press-formed part.

[0003] The T-shaped press-formed part serving as the upper position forming member of a center pillar is normally arranged in the following form in a side frame of an automobile. That is, in the T-shaped press-formed part, a first part forming portion arranged in a vertical direction (the height direction of a vehicle) and a second part forming portion arranged in a horizontal direction (the front-rear direction of the vehicle) are integrally connected and formed in a T-shape, and arranged as such.

[0004] The first part forming portion is a member in which a hat-shaped cross-section consisting of a top plate portion, side plate portions and flange portions is arranged in the height direction (vertical direction) of the vehicle, and is arranged as an elongated shape. In this case, the top plate portion of the hat-shaped cross-section is arranged so as to be located at an outer position in the width direction of the vehicle.

[0005] The second part forming portion is a member arranged in a flat plate form at an end of the aforementioned elongated first part forming portion in a direction intersecting the first part forming portion. The second part forming portion is integrally and continuously formed with the first part forming portion, and the forming position of the flat plate form of the second part forming portion is a position protruding from the position of the top plate portion of the hat-shaped cross-section in the first part forming portion.

[0006] In other words, the arrangement of the two forming parts at the connection point between the first and second forming parts is such that the flat plate-shaped portion of the second forming part protrudes outward in the width direction when viewed in the vehicle width direction from the hat-shaped top plate portion of the first forming part.

[0007] The T-shaped press-formed parts described above are typically press-formed using a first press-forming process that involves a drawing process and a second press-forming process that involves a bending process or a pad drawing (gripping and bending) process. In this press-forming process, T-shaped press-formed parts may develop wrinkles on the press-formed surface due to the press-forming process. For this reason, a forming method has been proposed in which a convex shape (a small mound of excess material) is formed in the region near the connection between the first part forming section and the second part forming section during the drawing process of the first press-forming process (see Patent Document 1 below). This increases the line length of the press-formed surface during the drawing process of the first press-forming process, thereby preventing or suppressing the occurrence of wrinkles. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2019-13952 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, in the deep drawing process of the first part forming section described above, there is a problem in that wrinkles occur in the flat plate-shaped portion of the second part forming section during the deep drawing process of the first press forming step. The inventors focused on the fact that this is due to the difference in line length of the press-formed surfaces in the cross-section of the first part forming section and the second part forming section in the vehicle's longitudinal direction. The inventors then noted that if wrinkles occur, the product quality cannot be met.

[0010] The present invention was devised in view of the above-mentioned points, and the problem that the present invention aims to solve is to prevent or suppress the occurrence of wrinkles in the second part forming portion by increasing the length of the press-formed surface of the flat plate-shaped portion in the second part forming portion during the first press forming process. [Means for solving the problem]

[0011] To solve the above problems, the press forming method for a T-shaped press part and the T-shaped press-formed part according to the present invention employ the following means.

[0012] The first aspect of the present invention is a press forming method for a T-shaped press part, comprising: a first part forming portion formed by arranging a hat-shaped cross-sectional shape, which has a top plate portion, a side plate portion, and a flange portion, in an elongated manner; and a second part forming portion, which is arranged in a flat plate shape at the end of the first part forming portion in a direction intersecting the first part forming portion, and is formed integrally and continuously with the first part forming portion, with the position of the flat plate shape being at a position protruding from the position of the top plate portion of the hat-shaped cross-sectional shape in the first part forming portion. The press forming method for the T-shaped press part comprises at least a first press forming step and a second press forming step, wherein in the first press forming step, a specific area range of the second part forming portion in the region extending from the end of the first part forming portion in the direction of the second part forming portion is press-formed as a convex shape with a height protruding above the height position of the top plate portion of the first part forming portion.

[0013] The second invention of the present invention is a press forming method for a T-shaped press part according to the first invention described above, wherein in the first press forming step, the height at which the convex shape is formed in a specific area of ​​the second part forming part is lower than the height at which the flat plate shape of the second part forming part is formed in the second press forming step.

[0014] The third invention of the present invention is a press forming method for a T-shaped press part according to the second invention described above, wherein in the press forming of the second press forming step, an additional convex shape is set at the upward inclined surface position of the connection part from the end of the first part forming part to the second part forming part, and the part is press formed.

[0015] The fourth invention of the present invention is a press forming method for a T-shaped press part according to the third invention described above, wherein the additional convex shape set at the upward inclined surface position of the connection part from the end of the first part forming part to the second part forming part is the positions on both sides of the top plate in the first part forming part at the connection part position.

[0016] The fifth invention of the present invention is a press forming method for a T-shaped press part according to any of the first to fourth inventions described above, wherein the T-shaped press part is an upper position forming member for a center pillar that forms the side frame of an automobile.

[0017] The sixth aspect of the present invention is a T-shaped press-formed part having a first part forming section formed by arranging a hat-shaped cross-sectional shape with a top plate section, a side plate section, and a flange section in an elongated shape, and a second part forming section arranged in a flat plate shape at the end of the first part forming section in a direction intersecting the first part forming section, and formed integrally and continuously with the first part forming section, wherein the position of the flat plate shape is set to protrude from the position of the top plate section of the hat-shaped cross-sectional shape in the first part forming section, and an additional convex shape is formed at the upward inclined surface position of the connection from the end of the first part forming section to the second part forming section.

[0018] The seventh invention of the present invention is a T-shaped press-formed part of the sixth invention described above, wherein the additional convex shape formed at the upward inclined surface position of the connection portion from the end of the first part forming portion to the second part forming portion is located on both sides of the top plate in the first part forming portion at the connection portion position. [Effects of the Invention]

[0019] According to the means of the present invention described above, in the first press forming step, by increasing the length of the press forming surface at the flat plate-shaped portion in the second component forming portion, generation of wrinkles in the second component forming portion can be prevented or suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] [Figure 1] It is a perspective view of the center pillar of the present embodiment viewed from the outside of the vehicle. [Figure 2] It is a front view of the same center pillar viewed from the outside of the vehicle. [Figure 3] It is a side view of the same center pillar. [Figure 4] It is a cross-sectional view schematically showing the cross-section taken along line IV-IV in FIG. 1 and FIG. 2. [Figure 5] It is a diagram sequentially showing forming states in the drawing step of the first press forming step. [Figure 6] It is a diagram sequentially showing forming states in the pad drawing (grip bending) step of the second press forming step. [Figure 7] It is a diagram sequentially showing forming states in the bending step of the second press forming step. [Figure 8] It is a plan view (side view of a vehicle) viewed from the press forming direction, showing an extracted T-shaped press formed component portion in the center pillar. [Figure 9] It is a cross-sectional view taken along line VIII-VIII in FIG. 8. [Figure 10] It is a cross-sectional view taken along line IX-IX in FIG. 8. [Figure 11] It is a diagram showing a state where wrinkles are generated in a conventional T-shaped press formed component. [Figure 12] It is a diagram showing a state where generation of wrinkles is prevented or suppressed in the T-shaped press formed component of the present embodiment. [Figure 13]This is a plan view (side view of the vehicle) taken from the press molding direction, showing the shape of the T-shaped press-formed part of this embodiment in which additional convex shapes are formed on both sides of the boundary between the first part forming part and the second part forming part. [Modes for carrying out the invention]

[0021] The press forming method for a T-shaped press part and embodiments of the T-shaped press-formed part according to the present invention will be described below with reference to the drawings. In the illustrations, arrow FR indicates the forward direction of the vehicle, arrow RR indicates the rearward direction of the vehicle, arrow UP indicates the upward direction of the vehicle, and arrow IN indicates the inward direction in the vehicle width direction. Unless otherwise specified, the direction indications refer to the direction in the illustration itself.

[0022] [T-shaped pressed parts] First, based on Figures 1 to 4, we will describe the T-shaped press part targeted by this embodiment, which is an upper position forming member of the center pillar 10 that forms the side frame of an automobile.

[0023] [Center pillar 10] The center pillar 10 is shown in Figures 1 to 4. Figure 1 is a perspective view of the center pillar 10 as seen from outside the vehicle, Figure 2 is a front view, and Figure 3 is a side view. Note that the center pillar 10 in Figure 1 is shown installed on the left side in the direction of travel of a vehicle such as an automobile. As explained in the background technology above, the center pillar 10 is arranged as a member that forms the side frame of a vehicle such as an automobile. The center pillar 10 is also commonly called the B pillar, due to its position in the sequence of pillars located on the side of the automobile.

[0024] As shown in Figure 1, the center pillar 10 has a long, elongated shape that extends in the vertical direction of the vehicle. In other words, it is a long, elongated member. Furthermore, since the center pillar 10 is a structural member that functions as a strength member during a side collision (side impact) of the vehicle, it is formed as a strong strength component. For this reason, high-tensile steel plates are usually used. In addition, as shown in Figure 3, it is formed with a convex curvature in the direction in which the side impact load acts, thereby improving its strength.

[0025] As clearly shown in Figure 2, the center pillar 10 is positioned with an inclined shape, with its upper end positioned further rearward than its lower end, when viewed from the side of the vehicle. The center pillar 10 is joined to the roof side rail 18 via a roughly T-shaped mounting portion 16 formed at its upper end. The configuration of this T-shaped mounting portion 16 at the upper end of the center pillar 10 is the T-shaped pressed part that this embodiment is based on, which will be described in detail later. The center pillar 10 is also joined to the side sill 22 via a roughly T-shaped mounting portion 20 formed at its lower end.

[0026] [Hat-shaped cross-section] The shape between the T-shaped mounting portion 16 at the upper end of the center pillar 10 and the T-shaped mounting portion 20 at the lower end is formed in a hat-shaped cross-section. The hat-shaped cross-section is shown in Figure 4. As shown in Figure 4, the hat-shaped cross-section is formed from a top plate portion 24 at the central position, flange portions 28 at both ends, and side plate portions 26 connecting the top plate portion 24 and the flange portions 28. In Figure 4, the side plate portions 26 are formed hanging down from both ends of the top plate portion 24 and consist of a left side plate portion 26L and a right side plate portion 26R. The left and right side plate portions 26L and 26R are formed in a shape that widens downwards. That is, in Figure 4, they are formed in a mountain-shaped inclined shape.

[0027] The flange portion 28 is formed extending from the lower end of the side plate portion 26 in the left-right direction and consists 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 lower end of the right side plate portion 26R.

[0028] [Press forming process] Next, the press forming process for press forming the center pillar 10 will be described. The press forming process in this embodiment is cold press forming and is carried out in at least two types of press forming steps. In this embodiment, the process is carried out in a drawing step of the first press forming step 12 and a bending step or pad drawing (gripping and bending) step of the second press forming step 14. Figure 5 shows the drawing step of the first press forming step 12, and Figure 6 shows the pad drawing (gripping and bending) step of the second press forming step 14.

[0029] In the first press forming process 12 shown in Figure 5, an intermediate molded product S2 is formed in the drawing process, and in the second press forming process 14 shown in Figure 6, a final molded product S3 is formed in the pad drawing (gripping and bending) process. In both Figures 5 and 6, for ease of understanding, the press dies used in each press forming process 12 and 14 are schematically shown, and in the order of the progress of the forming process, the top row shows the state before forming (top dead center), the middle row shows the state during forming, and the bottom row shows the state after forming (bottom dead center). In the illustration of the state before forming (top dead center) in the top row, the state where the upper dies 30 and 40 are shown by a dashed line is the top dead center state, and the solid line position of the upper dies 30 and 40 shows the moment when the upper dies 30 and 40 have descended and come into contact with the molding material S1.

[0030] [First press forming process 12 (drawing process)] First, the drawing process of the first press forming process 12 shown in Figure 5 will be explained. In this embodiment, the first press forming process 12 press forming is performed to about half the hat-shaped cross-section of the center pillar 10. That is, an intermediate molded product S2 with a shallow hat-shaped cross-section is formed. Since the forming in this first press forming process 12 is a drawing process, the inventors refer to the forming in the first press forming process 12 as "shallow drawing." The forming depth in this first press forming process 12 may be about half the depth of the product shape, or it may be drawn to almost the depth of the product shape. The drawing depth varies depending on the shape of the product, such as its depth.

[0031] In the first press forming process 12, a die 32 is positioned as the upper die 30, and a punch 36 and a blank holder 38 are positioned as the lower die 34. A flat molding 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 deep drawing press forming is performed by the relative movement of the punch 36 and the die 32 (the upper die 30 moves downward). The deep drawing process of the first press forming process 12 will be described in order below.

[0032] [Pre-molding state of the first press molding process 12] The upper part of Figure 5 shows the state before forming (top dead center) of the drawing process in the first press forming process 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 is positioned on the upper surface of the punch 36 of the lower die 34. In this state, the blank holder 38 is subjected to an upward biasing force by a pressurizing means (not shown), and the forming material S1 is held in place by the biasing force on the blank holder 38. The pressurizing means for the blank holder 38 can be a spring, rubber, gas cylinder, hydraulic cylinder, etc. For this reason, the blank holder 38 is sometimes referred to as a cushion.

[0033] [Intermediate state of molding during the first press molding process 12] The diagram in the middle of Figure 5 shows the intermediate state of the drawing process in the first press forming process 12. In this intermediate state, the die 32 of the upper die 30 moves downward while holding the molding material S1 in the blank holder 38. In this state, the molding material S1 strikes the upper surface (forming surface) of the punch 36 of the lower die 34, and is sequentially pressed by the punch 36. In this state, the lower surface (forming surface) of the die 32 of the upper die 30 does not strike the molding material S1. Therefore, in this state, intermediate drawing of the side plate portion 26 of the center pillar 10 is performed.

[0034] [Post-molding state after the first press molding process 12] The lower part of Figure 5 shows the post-forming (bottom dead center) state of the drawing process in the first press forming process 12. This post-forming state indicates that the intermediate forming state described above has progressed, and the die 32 of the upper mold 30 has moved to the bottom dead center of the drawing process in the first press forming process 12. In this state, the intermediate forming material S1 shown in the middle part is sandwiched between the die 32 of the upper mold 30 and the punch 36 of the lower mold 34, completing the intermediate forming process and the formation of the intermediate molded product S2 is complete.

[0035] In Figure 5, in the illustrated states shown in the middle and lower sections, the linear position indicated by the dashed line at the 32nd position of the upper mold 30 represents the position of the molding material S1 in the pre-molding state shown in the upper section. Therefore, the illustrated states of the molding material S1 and intermediate molded product S2 shown in the middle and lower sections represent the change in state from the dashed line state due to the downward movement of the upper mold 30 (die 32) during deep drawing.

[0036] Therefore, the wrinkle formation in the press-formed product during the drawing process of the first press-forming process 12, which is the problem addressed by this embodiment, occurs during the press-forming process from the middle to the lower stage shown in Figure 5. The countermeasures taken by this embodiment to address this issue will be described in detail later.

[0037] [Second press forming process 14 (pad drawing (gripping and bending) process)] Next, the pad drawing (gripping and bending) process of the second press forming process 14 shown in Figure 6 will be explained. This pad drawing (gripping and bending) process of the second press forming process 14 is a process in which the intermediate molded product S2 formed in the drawing process of the first press forming process 12 described above is formed into the final molded product S3 of the center pillar 10. That is, in this pad drawing (gripping and bending) process of the second press forming process 14, the hat depth of the hat-shaped cross-section of the center pillar 10 is formed to a predetermined depth of the final product shape.

[0038] For the pad drawing (gripping and bending) process of the second press forming process 14, the press die 44 is equipped with a punch 46 and a blank holder 48, similar to the drawing process of the first press forming process 12 described above. For the bending process of this second press forming process 14, the upper die 40 is equipped with a pad 49 in addition to the die 42.

[0039] The shape of the molded surface of the press die in the pad drawing (gripping and bending) process of the second press forming process 14, in particular the shape that forms the hat depth of the hat-shaped cross-section, is different from the shape of the molded surface of the press die in the drawing process of the first press forming process 12 that forms the intermediate molded product S2 described above.

[0040] In the pad drawing (gripping and bending) process of the second press forming process 14, the intermediate molded product S2 formed in the drawing process of the first press forming process 12 is placed between the forming surfaces of the die 42 and pad 49 of the upper mold 40 and the punch 46 of the lower mold 44, and press forming is performed by the relative movement of the upper mold 40 and the lower mold 44 (downward movement of the upper mold 40). The pad drawing (gripping and bending) process of the second press forming process 14 will be described in order below.

[0041] [Pre-molding state of the first press molding process 12] The upper part of Figure 6 shows the state before forming (top dead center) of the pad bending (gripping bend) process of the second press forming process 14. In this pre-forming state, the die 42 and pad 49 of the upper die 40 and the punch 36 of the lower die 44 are spaced apart with a gap between them. The intermediate molded product S2 formed in the drawing process of the first press forming process 12 is placed between these two 40 and 44. In detail, the top plate portion 24 of the intermediate molded product S2 is positioned and placed on the upper surface (forming surface) of the punch 46.

[0042] In this molding surface (top dead center) state, the pad 49 of the upper die 40 and the blank holder 48 of the lower die 44 are both subjected to biasing forces by pressurizing means (not shown). The pad 49 is subjected to a downward biasing force, placing it at its lowest position relative to the die 42. The blank holder 48 is subjected to an upward biasing force, placing it at its highest position. This highest position is the position of the blank holder 48 when the intermediate molded product S2 is placed on it. As mentioned above, pressurizing means include springs, rubber, gas cylinders, hydraulic cylinders, etc.

[0043] [Intermediate state of molding during the second press molding process 14] The diagram in the middle of Figure 6 shows the intermediate state of the pad drawing (gripping and bending) process of the second press forming process 14. In this intermediate state, the die 42 and pad 49 of the upper die 40 have moved downward, and the pad 49 has come into contact with the position corresponding to the top plate portion 24 of the intermediate molded product S2, and the top plate portion 24 of the intermediate molded product S2 is being gripped by the punch 46 of the lower die 44. At the same time, the die 42 has come into contact with 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 being gripped by the blank holder 48 of the lower die 44. In other words, the intermediate molded product S2 is being gripped by the die 42 of the upper die 40 and the blank holder 48 of the lower die 44. Note that in this state, there is still a forming space between the die 42 of the upper die 40 and the punch 46 of the lower die 44.

[0044] In the above state, the arrangement of the pad 49 of the upper mold 40 and the die 42 is such that, compared to the pre-molding state shown in the upper diagram, the position of the pad 49 in the press operating direction (vertical direction in the diagram) is slightly retracted relative to the position of the die 42. In other words, the die 42 has performed press molding on the intermediate molded product S2 by that amount. More specifically, the side plate portion 26 has been bent by that amount.

[0045] [Post-molding state after the second press molding process 14] The lower part of Figure 6 shows the post-forming (bottom dead center) state of the pad drawing (gripping and bending) process in the second press forming process 14. This post-forming state shows the state after the intermediate forming process described above has progressed, and forming has been completed until the forming space between the die 42 of the upper die 40 and the punch 46 of the lower die 44 is eliminated, resulting in the final formed product S3. This completes the press forming of the center pillar 10.

[0046] In the post-molding state described above, the die 42 of the upper mold 40 moves to the lowest bottom dead center position relative to the punch 46 of the lower mold 44 in the press molding direction (downward as seen in Figure 6). Consequently, the blank holder 48 of the lower mold 44 also moves downward relative to the punch 46 against the pressurizing means, positioning the flange portion 28 of the final molded product S3 to be gripped by the die 42.

[0047] Then, in the bottom dead center position described above, the final shape of the side plate portion 26 of the center pillar 10 is formed by the die 42 of the upper mold 40 and the punch 46 of the lower mold 44.

[0048] Furthermore, the pad 49 of the upper die 40 also moves upward relative to the die 42 as the die 42 moves downward. This upward movement continues until the molding space between the die 42 of the upper die 40 and the punch 46 of the lower die 44 is eliminated. This forms the final shape of the top plate portion 24 of the center pillar 10.

[0049] [Second press forming process 14 (bending process)] Figure 7 shows an embodiment where the second press forming process 14 is a bending process. The upper, middle, and lower diagrams in Figure 7 are shown in comparison to the upper, middle, and lower diagrams in Figure 6. As can be seen from this diagram, in the case of the bending process, the blank holder 48 in the pad drawing (gripping and bending) process in Figure 6 is not arranged. The reference numerals assigned to the bending process in Figure 7 are shown in comparison to the reference numerals assigned to the pad drawing (gripping and bending) process in Figure 6. The forming state is basically the same, so it is omitted.

[0050] [Description of the features of this embodiment] Next, the press forming method for the T-shaped press part and the T-shaped press-formed part, which are characteristic of this embodiment in the press forming of the center pillar 10 described above, will be explained. In the center pillar 10 described above, the location of the T-shaped press-formed part 10 targeted by this embodiment is the formation configuration of the area enclosed by frame S in Figures 1 and 2. Figure 8 shows an enlarged view of the said area. Note that the state shown in Figure 1 is a center pillar 10 installed on the left side in the direction of travel of a vehicle such as an automobile, while the state shown in Figure 8 is a case where the center pillar 10 is installed on the right side in the direction of travel.

[0051] Accordingly, as explained with reference to Figure 8, the T-shaped press-formed part X targeted by this embodiment consists of a first part forming section A and a second part forming section B. In this embodiment, the first part forming section A refers to a forming area in the center pillar 10 shown in Figures 1 to 4 where a hat-shaped cross-sectional shape, having a top plate portion 24, a side plate portion 26, and a flange portion 28, is arranged in an elongated shape. The second part forming section B is a forming area at the end of the first part forming section A (the upper end of the first part forming section A in Figure 8), arranged in a flat plate shape in a direction intersecting the first part forming section A. This second part forming section B is formed integrally and continuously with the first part forming section A, and in the product state, the position of the flat plate shape is slightly protruding from the position of the top plate portion 24 of the hat-shaped cross-sectional shape in the first part forming section A.

[0052] In the T-shaped press-formed part X, which consists of a first part forming section A and a second part forming section B as shown in Figure 8, the area where wrinkles occur during press forming in the first press forming process 12 is the area shown by hatching in Figure 8. In this embodiment, this area is referred to as the specific area range Y. The specific area range Y of the second part forming section B is the area of ​​the T-shaped press-formed part X that is extended from the end of the first part forming section A toward the second part forming section B.

[0053] In the specific region Y of the second component forming section B, wrinkles W as shown in Figure 11 occurred during the conventional press forming process 12. The inventors have devised the following means to prevent or suppress the occurrence of these wrinkles W and have taken countermeasures. Note that the wrinkles W generated during the press forming process 12 remain even after the press forming process 14, making it difficult to meet the product quality requirements for the center pillar 10.

[0054] Figures 9 and 10 show the configuration of countermeasures to prevent or suppress the occurrence of wrinkles W. These countermeasures involve press-forming a specific area Y of the second part forming section B, as described above, in the first press forming process 12, into a convex shape 50 (small mountain shape) that protrudes above the height of the top plate section 24 of the first part forming section A.

[0055] The detailed shape of the convex shape 50 will be explained based on Figures 9 and 10. Figure 9 shows a cross-section taken along the line VIII-VIII in Figure 8, and Figure 10 shows a cross-section taken along the line IX-IX in Figure 8. In the illustrations of Figures 9 and 10, the shape state indicated by the dashed line P indicates the position state in conventional general press forming, and the shape state indicated by the solid line R indicates the position state in which the convex shape 50 (small mountain shape) is formed and press-formed in this embodiment. Note that the height position K of the second part forming section B in Figure 9 indicates the height of the center pillar 10 as a finished product after the completion of the second press forming process 14.

[0056] In this embodiment, the height h of the convex shape 50 shown in Figure 10 is set to 8 mm. As can be seen from the illustrated state in Figure 9, this height h is lower than the formation height K of the flat plate shape of the second part forming section B that is press-formed in the second press forming process 14. In other words, the height of the convex shape 50 (small mountain shape) is set to be less than or equal to the height to which it is bent in the second press forming process 14.

[0057] [Effects of the first press molding process in the above-described embodiment] According to the embodiment described above, in the first press forming step 12, a convex shape 50 (a small mountain shape) is formed in a specific area Y of the T-shaped press-formed part X by press molding and then press-formed. As a result, the line length of the press-formed surface in the specific area Y of the second part forming part B can be made longer than in the conventional method, and the occurrence of wrinkles in the second part forming part B can be prevented or suppressed. Figure 12 shows the state of the second part forming part B after forming in the first press forming step 12. As can be seen from Figure 12, the occurrence of wrinkles W is almost completely prevented or suppressed.

[0058] [Additional embodiments added to the above embodiments] Next, an additional embodiment added to the basic embodiment described above will be explained. In this additional embodiment, during the press forming of the second press forming process 14, an additional convex shape 52 is set at the upward inclined surface position 54 of the connection from the end of the first part forming section A to the second part forming section B, and then press forming is performed. Figure 13 shows the position where the additional convex shape 52 is set. Note that the additional convex shape 52 may also be a concave shape. Even if it is a concave shape, the same effects and advantages as in the case of the additional convex shape 52 described later can be obtained.

[0059] The formation locations of the additional protruding shape 52 shown in Figure 13 are on both sides of the top plate portion 24 at the upward inclined surface position 54 of the connecting portion. The inclined surface position 54 where the additional protruding shape 52 is formed is explained with reference to Figure 9 as the part that reaches position K, which is shown as the finished product height in the second part forming portion B. This part is indicated by reference numeral 54 in Figure 9, and the position where the additional protruding shape is formed is indicated by reference numeral 52.

[0060] In Figure 13, the additional protruding shape 52 is formed at two locations on both sides of the top plate portion 24, but it is also possible to form a continuous additional protruding shape 52 by connecting these two locations.

[0061] [Effects of the above additional embodiment] According to the additional embodiment described above, in the press forming process of the second press forming step 14, an additional convex shape 52 is set at the upward inclined surface position 54 of the connection from the end of the first part forming section A to the second part forming section B. This makes it possible to increase the line length of the press forming surface at the inclined surface position 54, and reliably prevent or suppress the occurrence of wrinkles W at the inclined surface position 54.

[0062] Furthermore, the additional convex shape 52 is formed as a press molding in the second press molding process 14, and also becomes the product shape after molding in the second press molding process 14. This additional convex shape 52 as a product shape also has the effect of improving the strength of the formation location, that is, the upward inclined surface position 54 of the connection from the end of the first part forming section A to the second part forming section B.

[0063] [Other Embodiments] Although specific embodiments of the present invention have been described above, the present invention can also be implemented in various other forms.

[0064] For example, the embodiment described above described a T-shaped pressed part formed on the center pillar 10 of an automobile. This can also be applied to T-shaped pressed parts formed in other parts that form the frame of an automobile.

[0065] Furthermore, in the embodiments described above, the press forming process consisted of the drawing process of the first press forming process 12 and the pad drawing (gripping and bending) process and bending process of the second press forming process 14, but other press forming processes may also be included. For example, a trimming process may be included.

[0066] [Effects and effects of each invention described in "Means for solving the problem"] Finally, the effects and benefits of each invention in the "means for solving the problems" described above are noted below.

[0067] First, according to the first invention, in the first press forming process, a specific area of ​​the second part forming section is press-formed in a convex shape. As a result, in the first press forming process, the line length of the press-formed surface of the specific area of ​​the second part forming section becomes longer than in the conventional method. Therefore, the occurrence of wrinkles in the second part forming section can be prevented or suppressed.

[0068] Next, according to the second invention, the height at which the convex shape is formed in the specific region of the second part forming section in the first invention is set to a lower height than the height at which the flat plate shape of the second part forming section is formed in the second press forming process. This allows for accurate press forming without affecting the second press forming process of the second part forming section.

[0069] Next, according to the third invention, in the press forming of the second press forming process, an additional convex shape is set at the upward inclined surface position of the connection from the end of the first part forming section to the second part forming section, and then press forming is performed. This makes it possible to increase the line length of the press-formed surface at the inclined surface position, and thus reliably prevent or suppress the occurrence of wrinkles at the inclined surface position.

[0070] Next, according to the fourth invention, the position of the convex shape set on the upward inclined surface of the connection part from the end of the first part forming part to the second part forming part is set on both sides of the top plate in the first part forming part at the connection part position. As a result, since this position is a place where wrinkles are likely to occur, the occurrence of wrinkles can be prevented or suppressed more efficiently.

[0071] Next, according to the fifth invention, the T-shaped press part is an upper position forming member for the center pillar that forms the side frame of the automobile. This makes it possible to prevent or suppress the occurrence of wrinkles during press forming of the center pillar.

[0072] Next, the T-shaped press-formed part of the sixth invention provides the same effects and advantages as the press-forming method for the T-shaped press-formed part in the third invention described above.

[0073] Next, the T-shaped press-formed part of the seventh invention provides the same effects and advantages as the press-forming method for the T-shaped press-formed part in the fourth invention described above. [Explanation of Symbols]

[0074] 10 Center pillar 12. First press forming process 14. Second Press Forming Process 16 Mounting part 18 Roof side rails 20 Mounting part 22 Side sill 24 Top panel 26 Side plate part 26L Left side panel 26R Right side panel 28 Flange section 28L Left side flange 28R Right side flange section 30 Upper mold (for the first press molding process) 32 dies (for the first press forming process) 34. Lower mold (for the first press molding process) 36. Punch (for the first press forming process) 38. Blank holder (for the first press forming process) 40 Upper mold (for the second press molding process) 42 Dies (for the second press molding process) 44 Lower mold (for the second press molding process) 46. ​​Punch (for the second press forming process) 49 pads 48. Blank holder (for the second press forming process) 50 Convex form 52 Additional convex form 54. Position of the uphill slope A 1st part forming section B 2nd part forming section XT-shaped press-formed part Y Specific area range Height position of the R-shaped convex form K Formation height of the second part forming section of the finished product Height of h-shaped convex form W wrinkle

Claims

1. T-shaped pressed parts are A first component forming section is formed by arranging a hat-shaped cross-sectional shape, which has a top plate section, a side plate section, and a flange section, in an elongated manner, The first part forming portion is formed having a second part forming portion which is arranged in a flat plate shape at the end of the first part forming portion in a direction intersecting the first part forming portion, and is formed integrally and continuously with the first part forming portion, and the position of the flat plate shape is such that it protrudes from the position of the hat-shaped top plate portion in the first part forming portion. The T-shaped press part is formed by a press forming method comprising at least a first press forming step for forming an intermediate molded product and a second press forming step for forming a final molded product, In the first press forming process, In the T-shaped press part, a specific area of ​​the second part forming part in the region extending from the end of the first part forming part toward the second part forming part is press-formed as a convex shape with a height that protrudes above the height of the second part forming part outside of the specific area. In the press forming of the aforementioned second press forming process, The process involves press molding by setting an additional convex or concave shape at the upward inclined surface position of the connection from the end of the first part forming section to the second part forming section. The additional convex shape or the additional concave shape is formed at two locations on both sides of the top plate portion at the position of the ascending inclined surface. Press forming method for T-shaped press parts.

2. A press forming method for a T-shaped press part according to claim 1, A press forming method for a T-shaped press part, wherein in the first press forming step, the height at which a convex shape is formed in a specific area of ​​the second part forming part is lower than the height at which a flat plate shape is formed in the second part forming part that is press formed in the second press forming step.

3. A press forming method for a T-shaped press part according to either Claim 1 or Claim 2, The T-shaped press part is a member that forms the upper position of the center pillar, which forms the side frame of an automobile, and the method for press forming a T-shaped press part.

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