JPH11179440A - Pressing method for sheet made product having bead and pressing device used in it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sheet made product having beads with no warpage nor twist, without necessitating straightening in another process after pressing. SOLUTION: A blank S is held between a lower die blank holder 23 and an upper die blank holder 25 and lowered down to a lower limit position regulated by fixing pins 19, 20, whereby initial beads B1 are formed by a die 17 and a punch 15. A spring 16 is successively compressed by the punch 15, the die 17 which is fixed to the upper die holder 14 is lowered until abutting on a fixing pin 18, and a ridge part M of the initial beads B1 is crushed and returned. A residual tensile stress which is generated at the time of forming the initial beads is cancelled by compressing, thus the warpage and twist owing to the tensile stress are not generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of pressing a plate product provided with beads, such as a cover member of a casing of an electronic device or a mechanical device, and a press apparatus used for the same.

[0002]

2. Description of the Related Art A large number of flat press products are used as a cover member for a casing of an electronic device or a mechanical device, an internal partition, or the like. Such a flat product is generally formed with a bead bulging into a stripe shape as shown in FIG. 7 in order to increase the surface rigidity. In this example, two strips 42 and 43 heading toward the opposing corners are provided substantially at the center of the flat plate 40.
Are formed to cross each other. Thereby, the deformation of the flat plate in the direction perpendicular to the plane is suppressed, and the generation of abnormal noise due to the vibration of the flat plate is also prevented.

[0003]

However, conventionally,
A flat plate or the like on which such a bead is formed is almost inevitably provided with a warp F shown in FIG.
The twist G shown in FIG. When the flat plate is attached to the casing by, for example, fitting, such a warp or twist lowers the quality and degrades the merchantability. Further, even when fixing to a mating member with a bolt or the like, there is a problem that it is difficult to position a bolt hole at the time of assembly.

[0004] Therefore, it has been necessary to carry out surface correction processing in a separate step for warpage and twist. However, this requires repetition of trial and error, and when it is warped up, a new mold such as a mold in the direction of lowering it will be prepared and restricked, and it will have a predetermined accuracy after the press mold is made It took a considerable lead time to get the product.

[0005] Further, it is also attempted to form a tensile bead in an outer region of a part to be a final product to also reduce warpage and twist, also serving as a wrinkle holder accompanying bead forming. There is a problem that an extra material is required as a material. Therefore, in view of the above-mentioned conventional problems, the present invention does not require correction in a separate step after pressing, does not need to form a tensile bead, and can obtain a plate product having a bead without warpage or twist. And a press device used for the same.

[0006]

Accordingly, the present inventor has studied the cause of the warpage and torsion as a result of the study, and found that the cause is that the tensile stress generated around the bead due to the formation of the bead remains. I got For this reason, the press method of the present invention, based on the above findings, after press-forming a bead higher than a preset height, crushing the peak portion of the bead by a predetermined amount to the preset height. And

More specifically, first, a lower die blank holder and an upper die blank holder sandwiching a blank material are lowered with respect to a bead forming punch to form a bead having a peak higher than a predetermined height. Then, with respect to the lower mold blank holder and the upper mold blank holder, the punch is lowered together with the die sandwiching the peak between the punch and the punch,
The ridge of the bead is crushed to the preset height. By compressing the peak of the bead once formed by a predetermined amount, the residual tensile stress generated during bead forming is canceled by compression, and as a result,
No warping or twisting due to tensile stress occurs.

[0008] Further, a pressing device used for this includes a lower die holder, an upper die holder, a bead forming punch supported by the lower die holder via a first spring, and a punch fixed to the upper die holder. A die for sandwiching a bead forming portion of a blank material between the lower die blank holder, a lower die blank holder supported by a cushion pin extending from the lower die holder, and a lower die blank holder supported by the upper die holder via a second spring An upper mold blank holder sandwiching a peripheral portion surrounding a bead forming portion of a blank material, a blank holder position regulating means for regulating a lower limit position of the lower mold blank holder, and a punch position regulating means for regulating a lower limit position of the punch After lowering the lower mold blank holder and the upper mold blank holder to the lower limit position of the lower mold blank holder to form a bead, the punch and the die are punched. By lowering to the lower limit position, only the lowered amount was those adapted to crush the bead.

The above-mentioned punch position regulating means projects upward from the lower die holder, and is a fixed pin which can be brought into contact with the lower surface of the punch. The first spring is provided between the lower die holder and the lower surface of the punch. Rubber spring. With this press apparatus, it is possible to obtain a plate product having a bead without warpage or twist in one stroke without requiring correction in a separate step.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to examples. FIG. 1 shows a bead forming press apparatus used in the embodiment. The pressing device includes a lower die holder 13 with bolts (not shown) on the bolster 11 and ram 12, respectively.
The upper die holder 14 is fixed, and the punch 1 is placed on the lower die holder 13 via a rubber spring 16.
5 is held, and the die 17 is fixed to the upper die holder 14. The lower die holder 13 is provided with fixing pins 18, 19, 20 projecting upward. Fixing pins 18, 1
9 and 20 serve as stoppers for the punch 15, a lower die blank holder 23 and an upper die blank holder 25, which will be described later. Further, the cushion pin 21 protrudes upward from the bolster 11 side through the lower mold holder 13.

A spring 16 for supporting the punch 15 is made of rubber, and has a space for accommodating a fixing pin 18 in the center. In the free state, the upper end of the fixing pin 18 and the punch 1
A predetermined amount of gap is provided between the lower end surfaces of 5.

Between the lower die holder 13 and the upper die holder 14, a lower die blank holder 23 and an upper die blank holder 25 are further provided. The lower mold blank holder 23 surrounds the punch 15 with a hole 24 and is supported by the cushion pin 21. The upper mold blank holder 25 also has a hole 26 through which the punch 15 can pass, and a bolt 3 is attached to the upper mold holder 14 via a rubber spring 27.
2 supported. A slight gap is formed between each of the holes 24 and 26 of the lower die blank holder 23 and the upper die blank holder 25 and the punch 15 so as to allow mutual sliding.

In the free state, the lower blank holder 2
3 has an upper surface that is the same as or slightly higher than the upper surface of the punch 15, between the upper end of the fixing pin 19 and the lower surface of the lower die blank holder 23, and between the upper end of the fixing pin 20 and the upper die blank holder 25. A gap is provided between the lower surfaces. The upper end of the punch 15 is narrower than the lower part corresponding to the peak width of the bead to be formed. Further, a bolt 31 that penetrates the spring 16 and the lower mold holder 13 and is slidable along the guide hole 30 of the lower mold holder is fixed to the lower end of the punch 15.

FIG. 2 shows the initial stage of the bead forming press working. After the blank S is set between the punch 15 and the die 17, the ram 12 is lowered, and first, the upper blank holder 25 sandwiches the blank S between the lower blank holder 23. When the ram 12 is further lowered against the cushion pin 21 with the blank S sandwiched therebetween, the blank S contacts the punch 15. In this state, the fixing pins 18, 19, and 20 are not in contact with the punch 15, the lower mold blank holder 23, and the upper mold blank holder 25.

FIG. 3 shows a state where the ram 12 is further lowered to complete the bead drawing. The lower mold blank holder 23 and the upper mold blank holder 25 sandwich the blank S, and further push the cushion pin 21 to the lower position, so that the die 17 presses the blank S by the punch 15 and the lower mold blank holder 23 is pressed. The height difference between the blank material holding position of the upper die blank holder 25 and the upper surface of the punch 15 becomes a predetermined amount, for example, 6 mm, and the initial bead B1 is formed. At this position, the fixing pins 19 and 20 abut against the lower mold blank holder 23 and the upper mold blank holder 24, respectively, and prevent further lowering of the lower mold blank holder and the upper mold blank holder. On the other hand, a predetermined gap D still remains between the fixing pin 18 and the lower end surface of the punch 15.

FIG. 4 shows the final stage of processing. Ram 12
When the is further lowered from the state of FIG. 3, the die 17 fixed to the upper die holder 14 is lowered to crush the bead ridge M in a direction in which the height of the initial bead B1 is reduced.
During this time, the spring 27 is compressed while the height positions of the lower mold blank holder 23 and the upper mold blank holder 25 do not change.

The punch 1 pushed down by the die 17
5 compresses the spring 16, and the amount of displacement of the punch from the state of FIG. 3 to the contact with the fixing pin 18, for example, D = 1 m
m is the return amount (crush amount) of the bead peak M. Thereafter, the ram 12 is raised, and the blank S on which the bead B2 has been formed is taken out to be a final product or an intermediate product.

The present embodiment is configured as described above. After forming the bead B1 once, the lower die blank holder 23 and the upper die blank holder 25 are successively punched,
By further pressing down the die 17 to form a bead B2 in which the height of the ridge M is crushed by a predetermined amount, warpage and twist are significantly suppressed.

That is, FIG. 5 shows a first comparative measurement example with the related art. This is, as shown in FIG.
About the AA cross section when a 6 mm high bead is formed on a 1 mm thick electrogalvanized steel sheet of 00 mm, (b) the conventional method and (c) 6 mm by crushing 1 mm from the height of 7 mm based on the present embodiment. This is a comparison with the above. In the conventional method of (b), warpage of 6-7 mm occurs at the edge, whereas in the present embodiment of (c), the amount of warpage was 0.5 mm. Note that, in (b), the torsion was almost equal to the amount of warpage, but in (c), no twist occurred.

FIG. 6 shows a second comparative example. This is (a)
As shown in the figure, 450 mm × 1 having a plurality of notches
This is a comparison of a case where a bead having a height of 3 mm is formed in a longitudinal direction on a bent member of a 20 mm 0.5 mm thick electrogalvanized steel sheet. In the conventional method, as shown in (b), undulation was observed with a warp of 3 mm at the edge and 2 mm at the middle, based on the point (a) at the middle in the longitudinal direction. On the other hand, in this embodiment, the warpage was 0.5 mm as shown in FIG. Here, 3.5
0.5 mm was crushed from the height of 3 mm to 3 mm.

The springs 16, 2 in the embodiment are
Although 7 is made of rubber, any material such as a coil spring, urethane, or gas spring can be used as long as it is an elastic body.

[0022]

As described above, the pressing method of the present invention
After press-forming a bead higher than a preset height, the ridge of the bead was crushed by a predetermined amount to have the above-mentioned preset height, so that the residual tensile stress generated at the time of bead molding was reduced by compression. Cancellation is performed, and as a result, there is an effect that warpage or twisting due to tensile stress does not occur.

In the press apparatus of the present invention, a bead forming punch is supported by a lower mold holder via a first spring, a lower mold blank holder is supported by a cushion pin, and an upper mold blank holder is supported by a second spring. The upper die holder is supported via a spring of the lower die blank holder, the lower limit position of the blank holder position regulating means, and a punch position regulating means for regulating the lower limit position of the punch shall have a blank holder. After the bead is formed by lowering to the lower limit position and the punch and the die are lowered to the lower limit position of the punch, the bead is configured to be crushed. Therefore, a plate having a bead without warping or twisting in one stroke. The product can be obtained, and no correction is required in another process.

[Brief description of the drawings]

FIG. 1 is a view showing a press device in an embodiment.

FIG. 2 is a diagram showing an initial stage of bead forming press working.

FIG. 3 is a diagram showing a state where bead drawing is completed.

FIG. 4 is a view showing a final stage of press working.

FIG. 5 is a diagram showing a first comparative measurement example with the related art.

FIG. 6 is a diagram showing a second comparative measurement example with the related art.

FIG. 7 is a diagram illustrating an example of a flat product including a bead.

FIG. 8 is a view showing warpage and twist in a flat plate.

[Explanation of symbols]

 11 Bolster 12 Ram 13 Lower Holder 14 Upper Holder 15 Punch 16, 27 Spring 17 Die 18, 19, 20 Fixing Pin 21 Cushion Pin 23 Lower Blank Holder 24, 26 Hole 25 Upper Blank Holder 30 Guide Hole 31, 32 Bolt B1 Initial bead B2 Bead D Gap M Peak S Blank

Claims (4)

[Claims] 1. A method of pressing a plate product provided with a bead, wherein a bead having a height higher than a predetermined height is press-formed, and a ridge portion of the bead is crushed by a predetermined amount to obtain the predetermined height. A method for pressing a plate product provided with a bead, characterized in that: 2. A bead having a peak higher than a predetermined height by lowering a lower mold blank holder and an upper mold blank holder sandwiching a blank material with respect to a bead forming punch to form a bead. For the lower die blank holder and the upper die blank holder, lowering the punch together with the die sandwiching the peak between the punch and crushing the bead peak to the preset height. A method of pressing a plate product having a characteristic bead. 3. A blank material between a lower mold holder, an upper mold holder, a bead forming punch supported by the lower mold holder via a first spring, and a punch fixed to the upper mold holder. A die for sandwiching a bead forming portion, a lower die blank holder supported by a cushion pin extending from the lower die holder side, and a lower die blank holder supported by the upper die holder via a second spring. An upper mold blank holder sandwiching a peripheral portion surrounding the bead forming portion, a blank holder position regulating means for regulating a lower limit position of the lower mold blank holder, and a punch position regulating means for regulating a lower limit position of the punch, After lowering the lower mold blank holder and the upper mold blank holder to the lower limit position of the lower mold blank holder to form a bead, lowering the punch and the die to the lower limit position of the punch. A press apparatus characterized in that the bead is crushed by the descending amount by being lowered. 4. The punch position restricting means is a fixing pin projecting upward from the lower mold holder and being capable of abutting on a lower surface of the punch, wherein the first spring is provided between the lower mold holder and the lower surface of the punch. 4. The press device according to claim 3, wherein the press device is a rubber spring provided therebetween.