JPH06246355A - Method for bending high tensile steel sheet - Google Patents

Abstract

PURPOSE:To perform bending accurately in a hat-shaped cross-section with a single press stroke with a simple structure by giving the end part of a high tensile steel sheet a bend in the direction reverse to the spring back by the use of a horizontal slide die and thereby preventing the spring back. CONSTITUTION:When a lowering stroke is given to an upper die 1, a high tensile steel sheet W is lowered while being held between a punch 5 and a counter holder 4; the end part (w) of the high tensile steel sheet is raised by a bending shoulder 60 in accordance with the increase of the stroke of the punch 5; and a bending inclination is produced in the direction reverse to the spring back with the bending shoulder as a fulcrum. The bending inclination is squeezed on the bent end part from the boundary part between a web (a) and a horizontal flange (b) by the bending shoulder 30 of a fixed die 3. Further, when the punch 5 is lowered, the tip part of the end is hit by the bending shoulder of the fixed die at the recessed bending shoulder 52, a horizontal flange C is bent, and the working in the hat-shaped cross-section is complete.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for bending a high-strength steel sheet, and more particularly to a method for bending a high-strength steel sheet into a hat cross section using a press die.

[0002]

2. Description of the Related Art Automotive parts such as front side members and side rear members tend to use high-tensile steel sheets of 100 kg or more of high tensile strength steel as a material from the viewpoint of improving safety. However, since the high-strength steel sheet has a large residual strain during bending as a characteristic, it is attempted to obtain a so-called hat cross section having the web a, the vertical flanges b and b, and the horizontal flanges c and c as shown in FIG. In this case, the occurrence of springback and warpage is unavoidable, and it is difficult to perform bending into an appropriate shape. Conventionally, various methods for correcting springback have been proposed for bending metal plates, but generally, a method of bending a predetermined bending angle or more in a wrist-like process in consideration of the amount of springback, and a large bending shoulder of the die A method is adopted in which the curvature is set and the list is re-stretched into a regular shape in the subsequent process. Also, as a method for preventing warping due to ironing of the material surface on the die shoulder, a method of making two types of molds and bending in two steps, setting a large curvature of the bending shoulder of the die, The method of restructuring into a regular shape is adopted in.

[0003]

However, as in the former method, the method of restriking in consideration of the amount of springback is as follows.
The accuracy is uncertain because the degree of correction tends to vary, and the latter method involves two steps, resulting in poor efficiency and high cost. The present invention was devised to solve the above problems, and an object thereof is to accurately bend a high-strength steel sheet into a hat cross-sectional shape in one press stroke with a simple structure. It is to provide a method that can.

[0004]

In order to achieve the above object, the present invention provides a fixed die having a bending shoulder at the top as a bending die for bending a high-strength steel plate into a hat-shaped cross-sectional shape. With a counter holder that can appear and disappear
A punch having a bending shoulder at the tip and a concave bending shoulder for forming a lateral flange above the side wall, and a lateral slide having a bending shoulder at the top of the tip, which is arranged on the lower mold side so as to be able to approach and retract from the punch. Using a die and a driver provided with an upper die and having a cam surface corresponding to the back cam surface of the lateral slide die, a high-tensile steel plate is sandwiched between a punch and a counter holder, and a high-tensile steel plate protruding from them is used. With the end placed on the horizontal slide die at a position away from the punch shoulder, lower the upper die to move the horizontal slide die with a driver, and bend the high-tensile steel plate in the direction opposite to the springback with the punch shoulder as the fulcrum. Pre-bending is performed, and then the horizontal slide die is moved closer to the punch as the upper die descends, and the bend-raising portion is moved from the recessed bending shoulder of the punch to the side wall below and the front surface of the horizontal slide die. Bent to the specified bending angle while squeezing the opposite direction with the bending shoulder of the fixed die by lowering the punch and bending the lateral flange with the concave bending shoulder and the bending shoulder of the fixed die. It is the one.

Further, in the present invention, in the above-mentioned pre-bending process, the lateral slide die is brought closer to the punch by the biasing means at the start of processing, the end portion of the high-tensile steel plate is placed thereon, and the upper die is lowered to make the punch shoulder a fulcrum. As the initial stage, while pre-bending the bending line part, the horizontal slide die is retracted by the bending reaction force of the high-tensile steel plate, and then the driver is moved until it comes into contact with the cam surface as the upper die descends. Including bending and bending in the direction.

Further, according to the present invention, as a method of processing a lateral flange, instead of processing with a concave bending shoulder of a punch and a bending shoulder of a fixed die, a concave bending shoulder of a punch and a bending shoulder of a lateral slide die are used. Including a method of tapping. In this case, the bending shoulder of the fixed die is a concave bending shoulder.

Further, in addition to the above-mentioned lateral flange processing method, the present invention further makes the side wall of the punch downwardly sloped and the front wall of the lateral slide die downwardly sloped in order to surely prevent springback of the vertical flange. And a method of overbending in the direction opposite to the springback by sandwiching a high-tensile steel plate between them.

Further, according to the present invention, in addition to the method of making the side wall of the punch downwardly inclined and the front wall of the lateral slide die downwardly inclined to perform the above-mentioned excessive bending, the springback of the lateral flange is also prevented. In order to do so, the concave bent shoulder of the punch is configured to be a downward slope instead of a horizontal shape, and the bending shoulder of the lateral slide die is also configured to be a downward slope, and the lateral flange is set in the direction opposite to the springback between the downward slope regions. Over bending method. That is, the high-tensile steel plate is sandwiched between the punch and the counter holder, the end of the high-tensile steel plate protruding from the punch is placed on the horizontal slide die, and the upper die is lowered to move the horizontal slide die with a driver, thereby Perform a preliminary bending to bend in the direction opposite to the spring back with the punch shoulder as the fulcrum,
Then, as the upper die descends, the lateral slide die is moved closer to the punch, and the bent and raised portion is clamped between the downward slope surface of the horizontal slide die and the downward sloped side wall of the punch to perform excessive bending, and the subsequent downward movement of the punch results in lateral bending. The method includes a method of over-bending by pinching the end portion of the high-tensile steel plate with a downward slope behind the bending shoulder of the slide die and a downward slope-like bending shoulder of the punch. In this method, the pre-bending process includes
Any aspect of species can be employed. The present invention includes a method of performing three-dimensional bending as well as two-dimensional bending of the hat cross section.

[0009]

2 to 7 show the structure of FIG. 1 to which the present invention is applied.
The 1st example which processes the three-dimensional bending hat section shown in (a) is shown. Reference numeral 1 is an upper die, 2 is a lower die, and the upper die 1 is vertically movable by a press slide.
Is fixed to the bed side. The lower die 2 is provided with a fixed die 3, a counter holder 4 supported by a cushion is arranged in a groove-shaped hole 31 of the fixed die 3 so as to be retractable, and a bending shoulder 30 is provided at an inlet of the groove-shaped hole 31. Has been. On the other hand, a punch 5 is attached to the upper die 1 so as to face the counter holder 4, and the punch 5 is attached to the fixed die 3
The bending shoulder 50 has a size and a cross-sectional shape corresponding to that of the groove-shaped hole 31, and a bending shoulder 50 for forming a boundary bending portion between the web a and the vertical flange b in cooperation with the bending shoulder 30 is provided at the tip. A recessed bent shoulder 52 for forming a lateral flange is provided in an upper region of the side wall 51 continuing from 50.

In the upper surface area of the lower mold 2, horizontal slide dies 6, 6 that are paired on the left and right are arranged. As shown in FIGS. 3 and 4, the horizontal slit dies 6 and 6 have protrusions 63 and 63 that are in sliding contact with the slide guides 33 and 33 provided on the fixed die 3, and are advanced from the retracted position shown in FIG. It is possible to move to the position. The lateral slide cams 6 and 6 are pulled rearward in a normal state by biasing means 9 and 9, respectively. As the urging means 9, 9, an elastic body represented by a spring or cylinders is used. A bending shoulder 60 for pre-bending is provided on the upper end of the tip, and a cam surface 61 is formed behind the bending shoulder 60. The upper mold 1 is provided with drivers 7 and 7 in a relationship corresponding to the lateral slide dies 6 and 6 in the backward movement limit.
Cam surfaces 71, 71 for pressing the cam surfaces 61 of the horizontal slide dies 6, 6 are formed in the lower part of the. The fixed die 3 is provided with holes 32, 32 for allowing the drivers 7, 7 to enter, and the outer wall is provided with back heels 8, 8 for vertically sliding the drivers 7, 7. .

In this embodiment, since the three-dimensional hat-shaped cross section is bent, the counter holder 4 is provided with the horizontal portion 400 and the inclined portions 401 and 401 on both sides thereof as shown in FIG. 3, and the punch 5 corresponds thereto. Horizontal part 50
0 and inclined portions 501 and 501 are provided, and the horizontal portion 300 is provided at least on the upper surface of the groove-shaped hole side of the fixed die 3.
And inclined portions 301, 301 are provided. The horizontal slide dies 6 and 6 and the drivers 7 and 7 are divided and arranged in a plurality of sets. In this embodiment, one set is arranged in the horizontal part and one set is arranged in the boundary part between the horizontal part and the left and right inclined parts. In the case of a two-dimensional hat-shaped cross-section bending, the lateral slide dies 6, 6 and the drivers 7, 7 may be one set, or, of course, a plurality of sets may be arranged.

In this first embodiment, in forming, the horizontal slide dies 6, 6 are positioned at the backward limit, and the high-tensile steel plate W is set from the counter holder 4 in the elevated position to the horizontal slide dies 6, 6 and The mold 1 is lowered and the high-strength steel plate W is sandwiched and fixed by the counter holder 4 and the punch 5. This state is shown in FIG. 2, and then the upper die 1 is moved downward. In this way, the high-tensile steel plate W is lowered while being sandwiched between the punch 5 and the counter holder 4, but the end w of the high-tensile steel plate W is on the horizontal slide die 6, and the horizontal slide die 6 is the cam on the back. Since the surface 61 is pressed by the cam surface 71 of the driver 7 that descends synchronously with the upper mold 1, the surface 61 moves horizontally so as to approach the punch 5. Therefore, the end w of the high-tensile steel plate W is caused by the bending shoulder 60 corresponding to the increase in the stroke of the punch 5, and as shown in FIG. 5, the bending shoulder 50 of the punch 5 is used as a fulcrum to bend in the direction opposite to the spring back. A habit is attached. This pre-bending angle is usually 8
It is around 0 °. Then, when the punch 5 further descends,
In response to this, the lateral slide die 6 also advances, so that the bending angle with the bending shoulder 50 of the punch 5 as a fulcrum increases, and the end portion w of the high-strength steel plate W is moved toward the punch sidewall by the bending shoulder 60 of the lateral slide die 6. When pressed, the end w approaches the punch sidewall while curving in an S shape.

As the punch 5 descends, the lateral slide die 6 is advanced by the driver 7 to a position where the front wall 64 can contact the punch upper side wall 53. Therefore, in FIG.
As described above, the end portion w curved in the S shape is confined in the closed space formed by the front wall 64 of the lateral slide die 6 and the punch side wall 51. In this state, the punch 5 further descends and enters the groove-shaped hole 31 of the fixed die 3. As a result, as shown in FIG. 7, the end portion w curved in an S-shape is squeezed by the bending shoulder 30 of the fixed die 3 from its root, that is, the boundary portion between the web and the vertical flange, and the punch side wall 51.
The vertical flange b having a regular bending angle is formed by being drawn into the fixed die 3 while being sandwiched between the groove wall and the groove hole. When the punch 5 is further lowered, the concave bending shoulder 52 is moved to the fixed die 3
8 and the bottom dead center is reached as shown in FIG. Since the above-mentioned closed space is lost at this time, the tip of the end w is hit by the concave bending shoulder 52 and the bending shoulder 30 of the fixed die 3, whereby the lateral flange c is bent. As described above, the hat cross-section processing is completed, and the upper die 1 is lifted to move the horizontal slide die 6 backward. The punch 5 is lifted, and the product is removed from the punch 5 by an ejector (not shown).

9 to 12 show a second embodiment of the present invention. The mold structure in this embodiment is almost the same as that in the first embodiment, but in this embodiment, the lateral slide dies 6, 6 are punched from the back heels 8, 8 by the biasing means 9, 9 in the normal state to the punch sidewall 51 ,. It is urged to approach 51. Since the other mold structures are the same as those of the first embodiment, the same parts are designated by the same reference numerals and the description thereof will be omitted. The biasing means 9 and 9 are the holes 3 of the drivers 7 and 7.
It is arranged on both sides as shown virtually in FIG. In the second embodiment, the horizontal slide dies 6, 6 are moved to the forward limit of the position approaching the punches 5, 5, and the high tensile steel plate W is bent by the counter holder 4 and the horizontal slide dies 6, 6 during bending. It is stably placed on the upper surface of.

Next, when the upper die 1 descends, the high-tensile steel plate W is clamped by the lower surface of the punch 5 and the counter holder 4, as shown in FIG. Then, when the punch 5 starts to descend, the counter holder 4 and the end w protruding laterally from the punch 5 are supported on the upper surfaces of the horizontal slide dies 6 and 6, so that the bending shoulder 50 of the punch 5 is used as a fulcrum. As a result, the high-tensile steel plate W is started to be bent, and the reaction force of the bending exceeds the urging force of the urging means 9, so that the lateral slide die 6 starts to retreat and the supporting point for the end w moves. The lateral slide die 6 moves to the retracted limit where the cam surface 61 of the back portion comes into contact with the cam surface 71 of the driver 7, whereby the end portion w is bent and raised to a required angle as shown in FIG. Even at this time, the punch 5 and the driver 7 are descending, so that the lateral slide die 6
Starts to move forward from the backward limit in synchronization with the lowering of the punch 5, and presses the pre-bent end w toward the punch side wall 51. The bending operation and the bending mechanism of this transition are the first
Similar to the embodiment, the molding is completed at the lower limit of the punch 5 as shown in FIG.

13 to 15 show a third embodiment of the present invention. In this embodiment, the lateral flange c is not bent by the bending shoulder 30 of the fixed die 3 and the recessed bending shoulder 52 of the punch 5 as in the first and second embodiments.
The bending shoulder 60 and the upper surface of the lateral slide die 6 and the concave bending shoulder 52 of the punch 5 are used. Therefore, the bending shoulder 30 of the fixed die 3 is formed as a concave bending shoulder as a mold, and the width of the side wall 51 of the punch 5 is made larger than that of the groove hole 31.

In forming, as shown in FIG. 13, the high-tensile steel plate W is placed on the counter holder 4, the end w is placed on the horizontal slide dies 6 and 6, and the upper die 1 is lowered to form the counter holder 4. The high-tensile steel plate W is held between the punches 5, and the pre-bending is performed by bending the end w toward the side opposite to the spring back as shown in FIG. 14 by moving the horizontal slide dies 6 and 6 by lowering the drivers 7 and 7. . Then, as the punch 5 continues to descend and the horizontal slide die 6 advances due to the descending of the drivers 7 and 7, the bent and raised portion is moved to the side wall 51 of the punch 5.
Approach. As a result, the bent and raised portion is punch 5
While being bent and bent along the bending shoulder 50, the vertical flange b is squeezed by the punch side wall 51 and the front surface 64 of the horizontal slide die 6. Further, since the width of the side wall 51 of the punch 5 is larger than that of the groove hole 31, when the lower limit is reached, the boundary between the web a and the vertical flange b is fixed to the punch bending shoulder 50 as shown in FIG. A bottom recess is formed with the die recessed bending shoulder 30. Further, since the bending shoulder 60 of the horizontal slide die 6 and the recessed bending shoulder 52 of the punch 5 hit the tip of the vertical flange b, the horizontal flange c is bent.

16 to 18 show a fourth embodiment of the present invention. This embodiment is an example in which, in addition to the above-described pre-bending process, the vertical flange b is excessively bent to prevent spring back more completely. As a mold structure therefor, the side wall 51 of the punch 5 is formed as described above. As in the embodiment, the side wall is not inclined but has a slope that becomes wider toward the bottom, and the front walls 64, 64 of the lateral slide dies 6, 6 are correspondingly formed. Further, similarly to the third embodiment, the bending shoulder 30 of the fixed die 3 is formed as a concave bending shoulder, and the width of the side wall 51 of the punch 5 is larger than that of the groove hole 31. In the fourth embodiment, when the upper mold 1 is lowered from the state of FIG. 16, the end w of the high-tensile steel plate W is bent and raised in the direction opposite to the spring back as shown in FIG. 17 by the mechanism as described above. Subsequently, the bent and raised portion is pushed by the forward movement of the lateral slide die 6 against the sloped side wall 51 of the punch 5. Then, the bent and raised portions are continuously bent and lowered by the downward movement of the punch 5 and the forward movement of the lateral slide die 6, and the inclined side wall 51 and the inclined front wall 64.
The web is pinched by the excess of the bending angle of the product.
Bendable to vertical flange angle. When the punch 5 reaches the lower limit as in the third embodiment, the boundary portion of the web-vertical flange is bottom-projected, and at the same time, the bending shoulder 60 of the horizontal slide die 6 and the concave bending shoulder 52 of the punch 5 are lengthened. Since the tip end of the flange b is hit, the lateral flange c is bent.

19 to 25 show a fifth embodiment of the present invention. In this embodiment, both the springback of the vertical flange b and the sprinkback of the horizontal flange c are reliably prevented, and a hat-shaped cross section with high bending accuracy can be obtained. Therefore, as a die structure, the side wall of the punch 5 is not vertical as in each of the above-described embodiments, but has a sloped side wall 51 whose width becomes wider as it goes downward, and the lateral slide dies 6, 6 are correspondingly formed. The front wall is the inclined front wall 64, 64, and the lateral wall is not horizontal from the concave bending shoulder of the punch 5, but the inclined walls 55, 55.
Then, from the bending shoulder 60 of the lateral slide dies 6, 6 to the cam surface 6
The portion between 1 is a downgraded surface 65 corresponding to the downgraded wall 55. Also, the third
Similar to the embodiment, the bending shoulder 30 of the fixed die 3 is formed as a concave bending shoulder, and the width of the side wall 51 of the punch 5 is set to the groove hole 3.
It is larger than 1.

In this embodiment, the high-tensile steel plate W is set as shown in FIG. 19 and then the upper die 1 is lowered. First, the high-tensile steel plate W is punched and the counter holder 4 as shown in FIG. Then, as shown in FIG. 21, the driver 7 moves the lateral slide cam 6 while the punch 5 descends.
The horizontal slide cam 6 is moved forward by the action of, and the end portion w of the high-tensile steel plate on the bending shoulder 60 is bent and raised as shown in FIG. When the pre-bending is completed, and then the punch 5 further descends and the lateral slide die 6 continues to move forward, the bend-raised portion begins to be pressed against the sloped side wall 51 of the punch 5 as shown in FIG. Is sandwiched between the sloped side wall 51 and the sloped front wall 64 and is pressurized, so that the vertical flange b is excessively bent as shown in FIG.
Is molded. Then, when the punch 5 descends, the end of the bent and raised portion begins to be pushed into the recessed bending shoulder 52 of the punch 5, and when the punch 5 reaches the lower limit, the boundary portion of the web-vertical flange is bottom-projected, and at the same time, the lateral slide is performed. Since the downward sloped surface 65 of the die 6 and the downward sloped wall 55 of the punch 5 hit the tip of the vertical flange b, the lateral flange c having an excessive bending angle is bent as shown in FIG. Therefore, with one stroke of the press, there is no springback, and there is no warp in the vertical flange, and a hat-shaped cross-section product with good accuracy can be obtained. Incidentally, in the third to fifth embodiments, the lateral slide die 6 is arranged at a position separated from the punch 5 at the start of bending, but of course, as in the second embodiment, when the biasing means is used, It is possible to adopt a type in which the counter holder 4 is moved closer to the counter holder 4, and when the pre-bending is started, the counter holder 4 is retracted by a reaction force and is then moved forward again. In any of the examples, since the lateral slide dies 6 and 6 are used, there is a difference in the pre-bending angle of the end portion of the high-strength thin plate W in the process until the punch 5 and the die 3 are adjacent to each other. Since the contact resistance given to the outside of the material when intersecting is different, it is possible to surely suppress warpage and springback.

Applying the first embodiment of the present invention, 120 kg
Grade, thickness 1.6 mm, length 1400 mm, high strength steel plate, web outer width 91 mm, vertical flange height 71 mm, web-vertical flange angle 90 °, horizontal flange width 17 mm,
The vertical flange-horizontal flange was bent into a hat-shaped cross section of 90 °. As a result, a product with zero springback amount could be processed in one stroke.

[0022]

According to claim 1 of the present invention described above, when a high-tensile steel plate having a large residual strain is bent into a hat-shaped cross section, a spring is attached to the end of the high-tensile steel plate by using a lateral slide die. By giving a bending in the opposite direction to the back, the spring back generated in the step of bending at a predetermined bending angle can be offset with the above-mentioned bending hump, and the spring back can be prevented. Since it is squeezed by the bending shoulder of the fixed die while being confined in the enclosed space between the front wall and the side wall of the punch, warping can also be prevented,
The excellent effect that a hat cross-section processed product made of a high-strength steel plate with a vertical flange having an appropriate bending angle can be obtained in one stroke is obtained. Further, according to claim 2, the lateral slide die is initially approached in the punch direction and then retracted by the bending reaction force to form the bending line in the initial stage.
Higher institutional web width can be obtained. According to claim 3, since the boundary between the vertical flange and the web is bottom-bottomed in addition to the pre-bending process, springback is further suppressed,
Moreover, the lateral flange can be surely bent by hitting the lateral slide die and the punch. According to the fourth aspect, in addition to the effect of the third aspect, the vertical flange can be excessively bent by the punch whose side wall is spread downward and the inclined front wall of the horizontal slide die.
It is possible to more reliably obtain a hat cross-section processed product made of a high-tensile steel plate without springback. According to claim 5,
In addition to the effect of claim 4, since the lateral flange can also be excessively bent, it is possible to obtain a hat cross-section processed product made of a high-precision high-tensile steel plate in which the bending angle of each corner is accurate and there is no springback. Excellent effect can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view illustrating a product obtained by a method for bending a high-strength steel sheet according to the present invention.

FIG. 2 is a cross-sectional view showing a die structure for processing the product of FIG. 1 (a) and a steel plate set state (first embodiment).

3 is a plan view showing the lower mold structure in FIG. 2. FIG.

FIG. 4 is a side view showing the state of the bottom die of the upper die in FIG.

FIG. 5 is a half cross-sectional view showing a preliminary bending process in the first embodiment diagram.

FIG. 6 is a half cross-sectional view showing a state immediately before the start of vertical flange bending in the first embodiment.

FIG. 7 is a half sectional view showing a state during bending of the vertical flange in the first embodiment.

FIG. 8 is a half cross-sectional view showing a completed bending process.

FIG. 9 is a sectional view showing a second embodiment of the present invention in a steel plate set state.

FIG. 10 is a half sectional view showing a pre-bending process in the second embodiment.

FIG. 11 is a half cross-sectional view showing a state immediately before the start of vertical flange bending in the second embodiment.

FIG. 12 is a half cross-sectional view showing a completed bending process in the second embodiment.

FIG. 13 is a sectional view showing a third embodiment of the present invention in a steel plate set state.

FIG. 14 is a half sectional view showing a pre-bending process in the third embodiment.

FIG. 15 is a half cross-sectional view showing a completed bending process in the third embodiment.

FIG. 16 is a sectional view showing a fourth embodiment of the present invention in a steel plate set state.

FIG. 17 is a half sectional view showing a pre-bending process in the fourth embodiment.

FIG. 18 is a half cross-sectional view showing a completed bending process in the fourth example.

FIG. 19 is a sectional view showing a fifth embodiment of the present invention in a steel plate set state.

FIG. 20 is a half sectional view showing a steel plate clamped state in a fifth embodiment.

FIG. 21 is a half cross-sectional view showing a state immediately before the start of preliminary bending in the fifth embodiment.

FIG. 22 is a half cross-sectional view showing a preliminary bending step in the fifth example.

FIG. 23 is a half cross-sectional view showing a state during bending of a vertical flange in the fifth embodiment.

FIG. 24 is a half cross-sectional view showing a state during bending of a vertical flange in the fifth embodiment.

FIG. 25 is a half cross-sectional view showing a completed bending process in the fifth example.

[Explanation of symbols]

 1 Upper Die 2 Lower Die 3 Fixed Die 4 Counter Holder 5 Punch 6 Side Slide Die 7 Driver 9 Energizing Means 30 Bending Shoulder 50 Bending Shoulder 51 Side Wall 52 Recessed Bending Shoulder 54 Side Wall 60 Bending Shoulder 61 Cam Face 64 Front Wall 65 Downward sloped surface 71 Cam surface W High-tensile steel plate w End part a Web b Vertical flange c Horizontal flange

Claims (5)

[Claims] 1. When bending a high-strength steel plate into a hat-shaped cross-sectional shape, a bending die is provided with a fixed die having a bending shoulder at the top, a counter holder capable of appearing and retracting in the fixed die, and a bending shoulder at the tip. A punch having a concave bending shoulder for forming a lateral flange above the side wall, a lateral slide die having a bending shoulder on the lower tip side so as to be able to approach and retract with respect to the punch, and an upper die. Using the one provided with a driver having a cam surface corresponding to the back cam surface of the lateral slide die, the high-tensile steel plate is sandwiched between the punch and the counter holder, and the end of the high-tensile steel plate protruding from them is punched from the punch shoulder. With the upper die lowered while being placed on the horizontal slide die at a separated position, the horizontal slide die is moved by the driver, and the high-tensile steel plate is bent in the direction opposite to the spring back with the punch shoulder as the fulcrum. While performing the pre-bending, the lateral slide die is moved closer to the punch as the upper die descends, and the bent and raised portion is trapped between the recessed bending shoulder of the punch and the side wall below and the front surface of the lateral slide die. Further, by further lowering the punch, the bending shoulder of the fixed die is squeezed in the opposite direction while bending it to a predetermined bending angle, and the lateral flange is bent by the concave bending shoulder and the bending shoulder of the fixed die. Characteristic high-strength steel plate bending method. 2. In the pre-bending process, the lateral slide die is brought closer to the punch by the biasing means at the start of processing, the end of the high-tensile steel plate is placed on the punch, and the upper die is lowered to initially bend the punch shoulder as a fulcrum. While pre-bending the wire part, the lateral slide die is retracted by the bending reaction force of the high-tensile steel plate, and then the driver is moved until it comes into contact with the cam surface as the upper die descends, causing bending in the direction opposite to the spring back. The method of bending a high-strength steel sheet according to claim 1, including a method. 3. When bending a high-strength steel plate into a hat-shaped cross-section, as a bending die, a fixed die having a concave bending shoulder on the upper side, a counter holder capable of appearing and retracting in the fixed die, and a tip end A punch having a bending shoulder and a concave bending shoulder for forming a horizontal flange above the side wall, and a lateral slide die having a bending shoulder on the lower tip side so as to be able to approach and retract with respect to the punch, The end of the high-strength steel plate that is sandwiched between the punch and the counter holder and protrudes from them by using the one provided with the upper die and having the cam surface corresponding to the back cam surface of the lateral slide die. Move the horizontal slide die with the driver by lowering the upper die while placing it on the horizontal slide die at a position separated from the punch shoulder, and reverse the springback with the high-tensile steel plate using the punch shoulder as a fulcrum. Bending is performed in the same direction, and then the horizontal slide die is moved closer to the punch as the upper die descends to bend the bend-raising part along the bending shoulder of the punch. It is pinched at the front side, and the boundary between the web and the vertical flange is formed by bottom punching with the punch bending shoulder and the concave bending shoulder of the fixed die,
A method for bending a high-strength steel sheet, characterized in that a lateral flange is tapped to form a concave shoulder of a punch and a lateral shoulder of a lateral slide die. 4. When bending a high-strength steel plate into a hat-shaped cross-sectional shape, a bending die is provided with a fixed die having a concave bending shoulder at the top, a counter holder capable of appearing and retracting in the fixed die, and a tip end. A punch having a bending shoulder and a side wall having a downward sloping slope and having a concave bending shoulder for forming a lateral flange above the side wall, and a punch which is arranged on the lower die side so as to be able to approach and retract with respect to the punch, Using a high-tensile steel plate with a horizontal slide die having a bent shoulder and a front wall descending to a sloping surface, and a driver provided with an upper die and having a cam surface corresponding to the back cam surface of the horizontal slide die. Move the horizontal slide die with a screwdriver by lowering the upper die while sandwiching it with the punch and the counter holder and placing the end of the high-tensile steel plate protruding from them on the horizontal slide die at a position separated from the punch shoulder. While performing pre-bending to bend the high-strength steel plate in the direction opposite to the spring back with the punch shoulder as a fulcrum, the lateral slide die is moved closer to the punch as the upper die descends, and the bend-raised portion becomes the bending shoulder of the punch. Bending along the vertical flange, and pressing the vertical flange between the side wall of the punch and the lower slope of the horizontal sled die, excessive bending is performed in the direction opposite to the springback, and the boundary between the web and the vertical flange is bent to the punch shoulder and fixed die. A method for bending a high-strength steel sheet, which comprises bottom-forming with a recessed bending shoulder, and tapping a lateral flange with a recessed bending shoulder of a punch and a bending shoulder of a lateral slide die. 5. When bending a high-strength steel plate into a hat-shaped cross-sectional shape, as a bending die, a fixed die having a concave bending shoulder at the top, a counter holder capable of appearing and retracting in the fixed die, and a tip end A punch having a bending shoulder and a side wall having a downwardly sloping slope and having a recessed bending shoulder with a downward slope for forming a lateral flange above the side wall, and a punch which is arranged on the lower die side so as to be able to approach and retract with respect to the punch. A driver having a lateral slide die having a curved shoulder at the upper end of the tip and a descending slope surface following the bending shoulder and a front wall forming a descending slope surface, and a cam surface provided on the upper die and corresponding to the back cam surface of the lateral slide die. Using the one equipped with, insert the high-tensile steel plate between the punch and the counter holder, and lower the upper die while placing the end of the high-tensile steel plate protruding from them on the horizontal slide die at a position separated from the punch shoulder. By moving the horizontal slide die with a driver more and performing pre-bending to bend the high-tensile steel plate in the direction opposite to the spring back with the punch shoulder as a fulcrum, then move the horizontal slide die closer to the punch as the upper die descends. Excessive bending is performed by pinching the bend-raising part with the downward slope surface of the horizontal slide die and the downward slope of the punch side wall, and then the punch is lowered to bend the lateral slide die. A method for bending a high-strength steel sheet, which comprises over-bending a lateral flange portion by pinching the end portion of the high-tensile steel sheet.