JP6176046B2 - Welded structure made of high-tensile steel plate - Google Patents

Description

The present invention relates to high-tensile steel plate welded structure in an automobile body.

  The automobile body includes a front and rear member arranged in the front-rear direction of the vehicle body and a vehicle width member arranged in the width direction of the vehicle body as main structural members. The front and rear members and the vehicle width member are usually joined to each other via a flange formed at the end of the vehicle width member in the longitudinal direction, and bear the rigidity of the vehicle body and load transmission at the time of collision.

  For example, the vehicle width member is required to have a small deformation due to a load acting in the vehicle width direction and a high bending rigidity, torsional rigidity, and shear rigidity. In recent years, the use of high-tensile steel sheets having a tensile strength of 390 MPa or more has been directed as materials for these structural members from the viewpoint of weight reduction of the vehicle body and collision safety.

  For example, the floor cross member has a substantially hat-shaped cross-sectional shape and is joined to front and rear members such as side sills via outward flanges formed at both ends in the longitudinal direction. It is important to increase the rigidity to improve the rigidity of the vehicle body and the load transmission performance when an impact load is applied.

  However, a steel plate with high strength has problems such as a low degree of freedom in design because press formability is inferior to a steel plate with low strength.

  That is, a flange (outward flange) directed outward in cross section is continuously formed on the entire circumference of the end of a structural member such as a vehicle width member or a front / rear member to obtain an outward flange width of a certain length. Then, at the time of press molding, molding failure such as stretch flange cracking near the outer periphery of the portion along the ridge line portion of the outward flange (also referred to as ridge line flange) or wrinkle near the root of the ridge line flange occurs, and the desired shape is In many cases, it cannot be obtained. This molding defect generally tends to occur as the material strength increases.

  Therefore, when a high-tensile steel plate is used as a forming material, due to restrictions on press forming, it is difficult to manufacture a structural member having a continuous outward flange including a ridge line flange by the conventional press forming method. The present situation is that the vicinity of the ridge line portion must be compensated for the lack of formability by notching the flange. The presence of this notch and the use of a steel plate with a thin plate thickness are factors that reduce the performance such as load transmission, bending rigidity, and torsional rigidity.

  Patent Documents 1 to 3 disclose a method for manufacturing this type of member.

Japanese Patent No. 4438468 JP 2009-255116 A JP2012-0511005A

  Also based on the conventional invention disclosed in Patent Documents 1 to 3, a tensile member having a substantially groove-shaped cross-sectional shape and having an outward flange formed at least in the range along the ridgeline portion at the end in the longitudinal direction It is difficult to form a structural member for a vehicle body made of a high-strength steel plate having a strength of 390 MPa or more.

An object of the present invention is to obtain a welded structure that is a press-formed body made of a high-tensile steel plate of 390 MPa or more and includes a vehicle body structural member that can be welded to another member via a ridge line flange. .

The present invention is , for example, a press-formed body made of a high-strength steel plate of 390 MPa or more, and has a groove bottom flange or vertical length capable of staggered arrangement, two-row spot welding, or non-linear (for example, wave shape) laser welding. and to obtain a welded structure comprising a vehicle body structural member having a wall flange.

Solution

As a result of intensive studies to solve the above problems, the present inventors have
(A) A press molding apparatus that includes a punch and a die, and further includes a pad that presses against the molding material and restrains the molding material. A substantially groove having a groove bottom part, a ridge line part continuing to the groove bottom part, and a vertical wall part continuing to the ridge line part by constraining at least a part of the part formed on the adjacent ridge line part. This is a press-formed body made of a high-tensile steel plate of 390 MPa or more having a mold cross-sectional shape and an outward flange continuous in a range extending from a ridge line portion at an end portion in the longitudinal direction and a groove bottom portion and a vertical wall portion on both sides thereof. Obtaining a structural member for a vehicle body;
(B) With this press molding, it is possible to ensure the width of the ridge line flange capable of welding such as spot welding via the outward flange (ridge line flange) in the ridge line part,
(C) The present invention was completed by finding that it is possible to secure a flange width that enables welding such as staggered arrangement or two-row spot welding via outward flanges at the groove bottom or vertical wall. did. The present invention is listed below.
(1) A groove bottom portion made of a high-tensile steel sheet having a tensile strength of 390 MPa or more, which is arranged in the vehicle width direction or the front-rear direction of the automobile body, a ridge line portion continuous to the groove bottom portion, and a vertical line continuous to the ridge line portion A substantially groove-shaped transverse cross-sectional shape including at least a wall portion, and the entire ridge line portion and at least a part of each of the groove bottom portion and the vertical wall portion on both sides of the edge portion around the end portion in the longitudinal direction. and car-body structural member having an outward flange that is continuous with the range,
Other members to which the outward flanges in the groove bottom part, the vertical wall part and the ridge line part are joined to the vehicle body structural member;
A welded structure characterized by comprising:
(2) The welded structure described in (1) , wherein the vehicle body structural member is a press-formed body .
(3) with a width of the outward flange at the ridgeline portion is 2mm or more, at least one of the flange width of the outward flange in said outward flange and the vertical wall portion of the groove bottom 15mm or more A welded structure described in a certain item (1) or (2).
(4) together with the width of the outward flange at the ridgeline portion is 10mm or more, at least one of the flange width of the outward flange in said outward flange and the vertical wall portion of the groove bottom 15mm or more A welded structure described in a certain item (1) or (2).
(5) together with the width of the outward flange at the ridgeline portion is 10mm or more, at least one of the flange width of the outward flange in said outward flange and the vertical wall portion of the groove bottom 30mm or more A welded structure described in a certain item (1) or (2).
( 6 ) The welded structure according to any one of items (1) to (5) , wherein the joining is spot welding.
(7) and said outwardly flange in the vertical wall portion, said at least one of the outward flange at the groove bottom, is spot welded in a staggered arrangement or 2 row arrangement (6) welded structure according to claim body.
( 8 ) The welded structure according to any one of items (1) to (5) , wherein the joining is non-linear laser welding or a combination of laser welding and spot welding.
( 9 ) The welding structure according to any one of items (1) to (5) , wherein the joining is a combination of laser welding, spot welding, and an adhesive.

  According to the present invention, a vehicle width member or a front / rear member made of a high-tensile steel plate of 390 MPa or more having a ridge line portion at an end portion in the longitudinal direction and an outward flange continuous with a range extending from a groove bottom portion and a vertical wall portion on both sides thereof. Such as spot welding with other members via the outward flange in the ridge line portion is possible, the joint strength of the welded structure having the structural member and other members is improved, Improves impact performance, torsional rigidity, bending rigidity, and shear rigidity. Thereby, the rigidity and strength of the automobile body are increased, and the weight reduction of the vehicle is promoted.

  According to the present invention, since the occurrence of cracks and wrinkles in the outward flange can be reduced, it is possible to increase the width of the outward flange in the groove bottom portion and the vertical wall portion. As a result, welding such as staggered arrangement or two-row spot welding is possible via outward flanges at the groove bottom or vertical wall, and the joint strength of the welded structure is further improved, and impact performance, torsional rigidity and shearing are improved. The rigidity can be further improved.

FIG. 1A to FIG. 1D are explanatory views conceptually showing the features of a press-molded body, its manufacturing method and manufacturing apparatus, FIG. 1A is a diagram seen from the front in the longitudinal direction of the press-molded body, and FIG. FIG. 1C is a diagram schematically showing a schematic configuration of a press-molded body manufacturing apparatus and a first step, and FIG. 1D is a view around a ridge line pad in the first step. It is a perspective view which shows the structure. 2A to 2D are explanatory views schematically showing a welded structure, in which FIGS. 2A and 2B show the case of spot welding, and FIGS. 2C and 2D show the case of laser welding. 3A to 3C are explanatory views showing the shape of the press-formed body of Analysis Example 1, FIG. 3A is a perspective view of the press-formed body, FIG. 3B is a view taken along the arrow II in FIG. 3A, and FIG. It is a cross-sectional view. 4A is a perspective view showing a punch (lower die), a die (upper die), a ridge line pad, and a molding material at the time of press molding using the ridge line pad, and FIG. 4B is a punch at the time of press molding using the ridge line pad ( 4C is an enlarged perspective view showing a rectangular box in FIG. 4B, and FIG. 4D is a cross-sectional view taken along line III-III in FIG. 4C. . 5A to 5C are explanatory views showing the shape of the press-formed body of Analysis Example 2. FIG. 5A is a perspective view of the press-formed body, FIG. 5B is a view taken along the arrow VI in FIG. 5A, and FIG. FIG. 6A is a perspective view showing a punch (lower mold), a die (upper mold), a ridge line pad, and a molding material at the time of press molding using the ridge line pad, and FIG. 6B is a punch at the time of press molding using the ridge line pad. FIG. 6C is an enlarged perspective view showing a square box part of FIG. 6B, and FIG. 6D is a sectional view taken along the line VII-VII in FIG. 6C. is there.

The present invention will be described with reference to the accompanying drawings.
1A to 1D are explanatory views conceptually showing the features of the press-formed body 15 and the manufacturing method and manufacturing apparatus of the present embodiment. FIG. 1A is a view of the press-formed body 15 as viewed from the front in the longitudinal direction. FIG. 1B is a view of the press-formed body 15 as viewed from the side in the longitudinal direction. FIG. 1C is a diagram schematically showing a schematic configuration of the manufacturing apparatus 10 for the press-formed body 15 and a first step. Furthermore, FIG. 1D is a perspective view showing a configuration around the ridge line pad 14 in the first step.
(1) Structural member As shown in FIG. 1A, the structural member for a vehicle body of the present embodiment is a press-formed body 15 made of a long, high-tensile steel plate of 390 MPa or more. The press-formed body 15 is continuous with the groove bottom 15a, ridge lines 15b and 15b continuous with the groove bottom 15a, vertical wall sections 15c and 15c continuous with the ridge line sections 15b and 15b, and vertical wall sections 15c and 15c, respectively. And has a substantially groove-shaped cross section having curved portions 15d and 15d and flanges 15e and 15e continuous to the curved portions 15d and 15d, respectively.

  The outward flange 16 is formed along the entire circumference of the end in the longitudinal direction, that is, along the groove bottom 15a, the ridges 15b and 15b, the vertical walls 15c and 15c, the curved portions 15d and 15d, and the flanges 15e and 15e. Yes.

  The structural member for a vehicle according to the present embodiment is a press-molded body 15 having no notches in the ridge line flange portions 16 a and 16 a of the outward flange 16.

Moreover, the cross-sectional height of the structural member for vehicle body of this embodiment is 20 mm or more.
The width of the outward flange 16 is 10 mm or more from the viewpoint of securing a region of welding joint such as laser welding or spot welding in the groove bottom portion 15a, the ridge line portions 15b and 15b, and the vertical wall portions 15c and 15c. In addition, even if it does not weld-connect in the ridgeline parts 15b and 15b, it is 2 mm or more from a viewpoint of ensuring performance, such as a collision characteristic, torsional rigidity, and bending rigidity.

  In the present embodiment, a structural member that is a press-formed body 15 having a hat-shaped substantially groove-shaped cross section will be described. However, the structural member has at least a groove bottom portion 15a, ridge line portions 15b and 15b, and vertical wall portions 15c and 15c. The present invention can be applied to any press-formed body having a substantially groove-shaped cross section.

  Moreover, although the example in which the outward flange 16 is formed on the entire circumference of the end portion in the longitudinal direction will be described, the press-formed body 15 in which the outward flange 16 including the ridge line flanges 16a and 16a is formed, in other words, The present invention can be applied to any press-molded body in which the outward flange 16 is formed over the ridge portions 15b and 15b and the groove bottom portions 15a and the vertical wall portions 15c and 15c on both sides thereof.

  It is desirable that the flange width of at least one of the groove bottom flange 16b and the vertical wall flanges 16c and 16c is 15 mm or more. By setting the width to 15 mm or more, it becomes possible to perform spot welding or laser welding of other members, the groove bottom flange 16b, and the vertical wall flanges 16c and 16c in a staggered arrangement or a two-row arrangement, thereby increasing the strength of the joint. Can be increased.

  In addition, it is desirable that the width of the ridge line flange 16a is 10 mm or more. This makes it possible to perform spot welding or laser welding of the ridge line flange 16a with other members, and further increase the torsional rigidity of the joint structure. Can do.

  In the present embodiment, the structural member that is the press-formed body 15 made of a high-tensile steel plate having a tensile strength of 390 MPa or more has been described. However, in order to further reduce the weight and torsional rigidity, the tensile strength is preferably a high strength of 590 MPa or more. It is made of a tension steel plate, and more preferably made of a high strength steel plate having a tensile strength of 980 MPa or more.

The high-tensile steel plate may be a cold-rolled steel plate or a hot-rolled steel plate. The upper limit of the tensile strength is not particularly specified, but is usually 1470 MPa and can be further 1770 MPa.
(2) Welded structure 10
2A to 2D are explanatory views schematically showing the welded structure 10. FIGS. 2A and 2B show the case of spot welding, and FIGS. 2C and 2D show the case of laser welding.

  As shown in FIG. 2A, the welded structure 10 has a groove bottom portion 20a, ridge line portions 20b and 20b continuous to the groove bottom portion 20a, and vertical wall portions 20c and 20c respectively continuous to the ridge line portions 20b and 20b. Spot-welded via a press-formed body 20 made of a high-tensile steel plate having a groove-type cross section of 390 MPa or more, a groove bottom flange 20f, ridge line flanges 20g, 20g, and vertical wall flanges 20h, 20h of the press-formed body 20 Further, each of the widths of the groove bottom flange 20f, the ridge line flange 20g, and the vertical wall flange 20h is 10 mm or more.

  As shown in FIG. 2B, the welded structure 10 includes a groove bottom portion 20a, ridge line portions 20b and 20b continuous with the groove bottom portion 20a, and vertical wall portions 20c and 20c respectively continuous with the ridge line portions 20b and 20b. Spot-welded via a press-formed body 20 made of a high-tensile steel plate having a groove-type cross section of 390 MPa or more, a groove bottom flange 20f, ridge line flanges 20g, 20g, and vertical wall flanges 20h, 20h of the press-formed body 20 This is a welded structure having another steel plate member 40.

  The width of the groove bottom flange 20f and the ridge line flange 20g is 10 mm or more, and the width of the vertical wall flange 20h is 15 mm or more. The groove bottom flange 20f and the ridge line flange 20g are formed by single-line spot welding and the vertical wall part. The flange 20h is joined and integrated with another steel plate member 40 by spot welding in a staggered arrangement.

  The present invention is not limited to this form, and the vertical wall flange 20h may be spot-welded in two rows. Further, the width of the vertical wall flange 20h and the ridge line flange 20g is 10 mm or more, the width of the groove bottom flange 20f is 15 mm or more, the vertical wall flange 20h and the ridge line flange 20g are single-line spot welding, The groove bottom flange 20f may be staggered or two-row spot welding. In addition, spot welding conditions are not specifically limited, It can be set as normal spot welding conditions.

  The spot welding may be spot welding using a conductive adhesive (for example, Betamate 1496V. Of Dow Chemical Company) in addition to general spot welding.

  In the embodiment shown in FIGS. 2A and 2B, the width of the ridge line flange 20g is 10 mm or more and spot welding is performed via the ridge line flange 20g. However, the present invention is not limited to this embodiment. When spot welding is not performed, the width of the ridge line flange 20g may be 2 mm or more.

  The welded structure 10 shown in FIGS. 2C and 2D is a substantially groove having a groove bottom portion 20a, ridge line portions 20b and 20b continuous with the groove bottom portion 20a, and vertical wall portions 20c and 20c respectively continuous with the ridge line portions 20b and 20b. Laser-welded through a press-formed body 20 made of a high-tensile steel plate having a mold cross section of 390 MPa or more, a groove bottom flange 20f, ridge line flanges 20g, 20g, and vertical wall flanges 20h, 20h of the press-formed body 20 It is a welded structure having another steel plate member 40, the width of the groove bottom flange 20f and the ridge line flange 20g is 10 mm or more, and the width of the vertical wall flange 20h is 15 mm or more.

  The laser welding pattern is not particularly limited. For example, a C-shaped pattern as shown in FIG. 2C or a wave shape pattern as shown in FIG. 2D can be used.

In addition, although the tensile strength of the other steel plate members 40 is not particularly defined, a high strength steel plate of 390 MPa or more can be used.
(3) Press molded body manufacturing apparatus 10 (press molding apparatus)
As shown in FIG. 1C, the press molding apparatus 10 includes a punch 11, a die 12, and a pad 14 that presses and restrains a molding material 13 against the punch 11. In the manufacturing apparatus 10, as described below, the pad 14 is not only a portion of the molding material 13 that is molded into the groove bottom portion 15 a, but at least a portion near the longitudinal direction of the portions that are molded into the ridge line portions 15 b and 15 b. Is also restrained and will be referred to as a ridge line pad.

  The ridge line pad 14 has a shape that restrains a portion of the molding material 13 that is molded into the groove bottom portion 15 a and a portion that is molded into the ridge line portions 15 b and 15 b in the vicinity of the outward flange 16.

  In the known pad, the portion formed in the groove bottom portion 15a is constrained, but the portion formed in the ridge line portions 15b and 15b is not constrained. On the other hand, the ridge line pad 14 restrains not only the part formed in the groove bottom part 15 a but also the part formed in the ridge line parts 15 b and 15 b in the vicinity of the outward flange 16. According to the ridge line pad 14, the shape of the ridge line portions 15b and 15b is formed by being overhanged only by the material in the vicinity of the portion. Thereby, the movement of the material of the periphery of the part which the ridgeline pad 14 contact | abuts is reduced. For this reason, since the expansion and shrinkage deformation of the surrounding material causing cracks and wrinkles are suppressed, the stretch flange cracks in the ridge line flange portion 16a of the flange 16 and the wrinkles in the vicinity of the flange 16 in the ridge line 15b. Can be reduced.

  The ridge line pad 14 aims at the effect of suppressing the movement of the peripheral material by projecting and forming the shape of the ridge line portion 15b in the vicinity of the outward flange 16. Therefore, among the parts formed on the ridge line part 15b, the connection part 15a-b is used as a starting point, and the part of the ridge line part 15b, 15b has a length of 1/3 or more of the cross-sectional circumferential length, more preferably the ridge line part 15b. It is desirable to constrain the entire cross-sectional circumferential length of the portion. In this case, if the shape is such as to hold a part of the vertical wall portion 15c, for example, the ridge line portion 15b and the vertical wall portion 15c with a length of 20 mm or less, the pad load is insufficient and cannot be pressed down. Therefore, it is allowed as a ridge line pad in the present invention.

  Further, the range (length 1 shown in FIG. 1B) restrained by the ridge line pad 14 in the longitudinal direction of the portion formed on the ridge line portion 15b is the vicinity of the outward flange 16, that is, the root of the outward flange 16 from the root of the ridge line portion 15b. It is preferable to set it as at least a part of a predetermined range in the direction in which. The predetermined range may be the same as the flange width of the ridge line flange portion 16a of the outward flange 16. For example, if the flange width of the ridge line flange portion 16a of the outward flange 16 is 20 mm, the predetermined range is about 20 mm, and if the flange width of the ridge line flange portion 16a is 30 mm, the predetermined range is also about 30 mm. In this case, it is not necessary to constrain the portion formed in the ridge line portion 15b throughout the predetermined range, and it may be a part of the predetermined range.

Other elements such as the dimensions (excluding portions corresponding to the ridge lines) and materials of the ridge line pad 14 other than those described above may be the same as those of known pads.
(4) Manufacturing Method of Press Molded Body In the press molding apparatus 10, the ridge line pad 14 is used to form a portion of the molding material 13 formed on the groove bottom 15 a and the ridge line portions 15 b and 15 b in the vicinity of the outward flange 16. Press molding while restraining the part to be molded.

  In order to form a portion that cannot be formed by this press forming (first press forming), a second press forming that is a subsequent process is performed. Specifically, the portion that cannot be formed by the first press molding is a portion that is located under the nose of the ridge line portion 15b restrained by the ridge line pad 14, as indicated by the oblique lines in FIG. 1B. 1B, that is, a part formed on a part of the vertical wall parts 15c and 15c, a part formed on a part of the curved parts 15d and 15d, and a part of the flanges 15e and 15e. In order to mold the part, the second press molding, which is a subsequent process, is performed.

  In the second press molding, press molding using only a die and a punch that does not use a pad (stamping press molding) or press bending molding using a normal pad may be used.

  Depending on the region constrained by the ridge line pad 14, there may be a remaining portion of the portion formed in the ridge line portion 15 b that could not be formed by the first press molding. In this case, the remaining portion of the portion formed on the ridge line portion 15b is press-molded by the second press molding. For example, when 1/3 of the portion formed on the ridge line portion 15b is formed by the first press forming, the remaining 2/3 of the portion formed on the ridge line portion 15b is formed by the second press forming. .

  As described above, the molding material 13 is press-molded by the press molding apparatus 10 including the punch 11, the die 12, and the ridge line pad 14 that presses and restrains the molding material 13 against the punch 11 (first press molding). 2A, the groove bottom portion 15a, the ridge line portions 15b and 15b continuous to the groove bottom portion 15a, the vertical wall portions 15c and 15c continuous to the ridge line portions 15b and 15b, It has a substantially groove-shaped cross section having curved portions 15d, 15d continuous with the wall portions 15c, 15c and flanges 15e, 15e continuous with the curved portions 15d, 15d, and the outward flange 16 is formed around the entire circumference of the end portion in the longitudinal direction. A press-formed body 15 made of a high-strength steel plate having a length of 390 MPa or more can be manufactured.

  In addition, since the press molding is performed twice, a concavo-convex shape portion of 0.1 mm or more is formed at the boundary portion between the ridge line portion 15b and the vertical wall portion 15c, which corresponds to the end portion of the ridge line pad 14 at the time of press molding. The

  In the above description, the case where the press-formed body 15 is manufactured by the press-forming apparatus 10 having the ridge line pad 14 is taken as an example, but the manufacturing method of the press-formed body 15 is not limited to this method. Needless to say, the press-formed body 15 having the above-described shape may be manufactured by any manufacturing method.

The numerical analysis results by the finite element method will be described.
[Analysis Example 1]
3A to 3C are explanatory views showing the shape of the press-formed body 20 of Analysis Example 1. FIG. 3A is a perspective view of the press-molded body 20, FIG. 3B is a view taken along arrow II in FIG. 3A, and FIG. 3C is a cross-sectional view of the press-molded body 20 (the outward flange 20f is not shown).

  The press-formed body 20 of Analysis Example 1 is made of a high-strength steel plate (590 MPa class dual phase (DP) steel), and the plate thickness is 1.4 mm.

  The press-molded body 20 includes a groove bottom portion 20a, ridge line portions 20b and 20b continuous to the groove bottom portion 20a, vertical wall portions 20c and 20c continuous to the ridge line portions 20b and 20b, and a curve continuous to the vertical wall portions 20c and 20c. It has the parts 20d and 20d and the flanges 20e and 20e which follow the curve parts 20d and 20d. The curvature radius inside the plate | board of ridgeline part 20b, 20b is 12 mm.

  An outward flange 20f is formed on the entire circumference of both ends in the longitudinal direction of the press-formed body 20, and the flange outer periphery of the ridge line flange portion 20g is a curved portion. The flange width of the outward flange 20f is 25 mm at a portion formed along the groove bottom portion 20a, and 30 mm at a portion formed along the vertical wall portions 20c and 20c.

  The cross-section wall angle of the press-formed body 20 is 70 degrees, and the cross-section height is 100 mm. In Analysis Example 1, the press-molded body 20 is manufactured by press molding by bending using a development blank.

  4A is a perspective view showing a punch (lower mold) 21, a die (upper mold) 22, a ridge line pad 25, and a molding material 24 during press molding using the ridge line pad 25, and FIG. 4B uses the ridge line pad 25. FIG. 4C is a perspective view showing a punch (lower mold) 21, a ridge line pad 25, and a molding material 24 during press molding, FIG. 4C is an enlarged perspective view showing a rectangular box part in FIG. 4B, and FIG. It is III-III sectional drawing in 4C.

  In bending using a normal pad, the pad constrains only the groove bottom portion of the molding material 24 or only the whole or part of the portion formed in the portion including the flange portion corresponding to the groove bottom portion. That is, it is a shape which does not restrain the part shape | molded by a ridgeline part. In the comparative example obtained by bending using a normal pad, the plate thickness reduction rate at the end of the ridge line flange portion is large, and there is a high possibility that stretch flange cracks will occur.

On the other hand, in bending using the ridge line pad 25, as shown in FIGS. 4A to 4D, the ridge line pad 25 is formed in the ridge line portion in addition to the portion formed in the groove bottom near the outward flange. Among the portions to be formed, the range of 1/3 or more of the cross-sectional circumferential length of the ridge line portion is constrained starting from the connection portion. In the example of the present invention obtained by bending using the ridge line pad 25, the plate thickness reduction rate at the end of the ridge line flange portion is small, and elongation flange cracking can be avoided.
[Analysis Example 2]
5A to 5C are explanatory views showing the shape of the press-formed body 30 of Analysis Example 2. FIG. 5A is a perspective view of the press-formed body 30, FIG. 5B is a view taken along the arrow VI in FIG. 5A, and FIG. 5C is a cross-sectional view of the press-formed body 30 (the outward flange 30f is not shown).

  The press-formed body 30 of Analysis Example 2 is made of a high-strength steel plate (590 MPa class DP steel), and the plate thickness is 1.4 mm.

  The press-formed body 30 includes a groove bottom portion 30a, ridge line portions 30b and 30b continuous with the groove bottom portion 30a, vertical wall portions 30c and 30c continuous with the ridge line portions 30b and 30b, and a curve continuous with the vertical wall portions 30c and 30c. It has the parts 30d and 30d and the flanges 30e and 30e which follow the curve parts 30d and 30d. The curvature radius inside the plate of the ridge portions 30b, 30b is 12 mm.

  An outward flange 30f is formed on the entire circumference of both end portions in the longitudinal direction of the press-formed body 30, and the flange outer periphery of the ridge line flange portion 30g is a curved portion. The flange width of the outward flange 30f is 20 mm at a portion formed along the groove bottom portion 30a, and 25 mm at a portion formed along the vertical wall portions 30c, 30c.

  The cross-section wall angle of the press-formed body 30 is 82 degrees, and the cross-section height is 60 mm. In Analysis Example 2, the press-molded body 30 is manufactured by press molding by bending using a development blank.

  FIG. 6A is a perspective view showing a punch (lower mold) 31, a die (upper mold) 32, a ridge line pad 35, and a molding material 34 during press molding using the ridge line pad 35. FIG. 6B is a perspective view showing the punch (lower mold) 31, the ridge line pad 35, and the molding material 34 during press molding using the ridge line pad 35. FIG. 6C is an enlarged perspective view showing the square box in FIG. 6B. 6D is a cross-sectional view taken along the line VII-VII in FIG. 6C.

  In bending molding using a normal pad, the pad restrains all or only a part of the molding material 34 that is molded into the groove bottom portion or the portion including the flange portion corresponding to the groove bottom portion. In other words, the portion formed in the ridge line portion has a shape that is not constrained. In the comparative example obtained by bending using a normal pad, the plate thickness increase rate is high in the vicinity of the ridge portion flange base, and there is a high possibility that wrinkles will occur.

  In contrast, in bending using the ridge line pad 35, as shown in FIGS. 6A to 6D, the ridge line pad 35 is formed in the ridge line portion in addition to the portion formed in the groove bottom portion in the vicinity of the outward flange. Among the portions to be formed, the range of 1/3 or more of the cross-sectional circumference of the ridge line portion is constrained starting from the connection portion. In the example of the present invention obtained by bending using the ridge line pad 35, the plate thickness increase rate at the base of the ridge line flange portion is small, and generation of wrinkles can be avoided.

  The press molding method and the press molding apparatus 10 described above are not limited to the above-described embodiments and examples. For example, although the cold rolled steel sheet was demonstrated in the Example, it can apply also to the various plated steel plate which uses a cold rolled steel plate or a hot rolled steel plate as a base material. In the embodiment, the case where the press molding is bending molding is taken as an example, but it may be drawn molding. Further, the press molding apparatus 10 has a mode in which the lower mold is configured by the punch 11 and the upper mold is configured by the die 12 and the ridge line pad 14, but is not limited to this mode. It is good also as a structure which reversed.

Not only the full lower cross member, and the groove bottom portion has a ridge portion continuous to the groove bottom portion, a substantially thin cross-section and a vertical wall portion continuous to the ridge portion, of the longitudinal ends, ridge all There is provided a press-formed body made of a high-tensile steel plate of 390 MPa or more in which outward flanges are formed in a range extending over at least a part of each of the groove bottom part and the vertical wall part on both sides thereof.

15 Press-formed body 15a Groove bottom 15b Ridge line 15c Vertical wall 16 Outward flange

Claims (9)

A groove bottom portion made of a high-tensile steel plate having a tensile strength of 390 MPa or more, which is arranged in the vehicle width direction or the front-rear direction of the automobile body, a ridge line portion continuous to the groove bottom portion, and a vertical wall portion continuous to the ridge line portion; along with having a substantially channel-shaped cross-sectional shape at least comprising, around the longitudinal end portion, and the whole of the ridge portion, respectively range over at least a portion of the groove bottom portion and the vertical wall on both sides and car-body structural member having an outward flange successive,
Other members to which the outward flanges in the groove bottom part, the vertical wall part and the ridge line part are joined to the vehicle body structural member;
A welded structure characterized by comprising: The welded structure according to claim 1, wherein the vehicle body structural member is a press-formed body . Together with the width of the outward flange at the ridgeline portion is 2mm or more, claim at least one of the flange width of the outward flange in said outward flange and the vertical wall portion of the groove bottom portion is 15mm or more A welded structure according to claim 1 or claim 2. Together with the width of the outward flange at the ridgeline portion is 10mm or more, claim at least one of the flange width of the outward flange in said outward flange and the vertical wall portion of the groove bottom portion is 15mm or more A welded structure according to claim 1 or claim 2. Together with the width of the outward flange at the ridgeline portion is 10mm or more, claim at least one of the flange width of the outward flange in said outward flange and the vertical wall portion of the groove bottom portion is 30mm or more A welded structure according to claim 1 or claim 2. The welded structure according to any one of claims 1 to 5 , wherein the joining is spot welding. The outward flange and, at least one of the outward flange in the groove bottom, weld structure according to claim 6 which is spot welded in a staggered arrangement or two rows arranged in the vertical wall portion. The welded structure according to any one of claims 1 to 5 , wherein the joining is non-linear laser welding or a combination of laser welding and spot welding. The welded structure according to any one of claims 1 to 5 , wherein the joining is any combination of laser welding, spot welding, and an adhesive.

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