JP2827632B2 - Hole punching type for inclined panel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a punching die for a metal panel, and more particularly to a punching die for an inclined panel used for punching an inclined panel.

[0002]

2. Description of the Related Art Conventionally, an apparatus for punching an inclined panel of a press-formed product such as a door panel or a hood panel, which is an automobile part, includes an upper die which is vertically movable and a lower surface facing the upper die. A lower die installed at a predetermined angle with respect to a plane perpendicular to the drawing direction, a punch provided at a lower portion of the upper die, and a die provided on the lower die corresponding to the punch. And a punching die composed of: Then, when punching the pressed product, after placing the pressed product on the lower die, the upper die is lowered, the punch presses the punched portion of the pressed product, and the punch and the die are pressed. A crack is generated from at least one of the punch side and the die side due to shear stress generated from the edge portion (blade portion), and a punched product is punched. However, in view of the quality of the punched product, it is necessary to reduce the height of the burr, so that it is necessary to set and manage the clearance between the punch and the die in a narrow range as shown in FIG. Also, since the surface of the punch that presses the panel is inclined during processing, the resultant force of the punch pressing force and the vertical reaction force from the slope (hereinafter referred to as the sliding force) acts on the tip of the punch, and this slippage occurs. If the force exceeds the static frictional force between the tip of the punch and the panel, the punch slides in the inclined direction, interferes with the die, and the punch and the die may be damaged. Therefore, as a technique capable of setting a clearance within a range where the punch does not interfere with the die even if slipping occurs, and suppressing generation of burrs, for example, Japanese Patent Application Laid-Open No.
An apparatus as shown in Japanese Patent No. 293922 is used. This prior art will be described below with reference to FIGS. 3 and 4, reference numeral 1 denotes a punch;
Is a dice. The punch 1 or the die 2 is evenly chamfered at the tip end on the scrap side, and the other end is formed with an edge (blade) 2a. Since the chamfer 1a is applied to one of the punch 1 and the die 2, stress is always concentrated on the edge 2a on the side that is not chamfered during processing. Due to the concentration of the stress, a crack is always generated from the side of the edge portion 2a, and the side that is not chamfered is broken. As a result, the burrs can be collected on the chamfered side (scrap side), the occurrence of burrs on the side without chamfering is suppressed, and the occurrence of burrs on the product side is reduced. This is punch 1 and die 2
Since the occurrence of burrs is reduced regardless of the clearance, there is no need to set the clearance narrow,
Interference between the punch 1 and the die 2 can be prevented, and their breakage can be prevented.

[0003]

However, in the punching of an inclined panel in which the forming surface forms a predetermined angle with respect to a plane perpendicular to the punching direction, the punch 1 has an obtuse angle with the acute side 8 at which the punching angle is acute. There is an obtuse angle side 9, and the acute angle side 8 is a portion for pressing the lower side cutout portion of the inclined panel, and the obtuse side 9 presses the upper side cutout portion of the inclined panel. This is the part to be processed. At the portion where the draft angle is on the acute angle side 8, the thickness of the panel 4 is reduced by the pressing of the punch 1, and when the thickness becomes equal to or less than a certain thickness, a crack is generated near the die edge due to shear stress from the die edge 7 and breaks. On the other hand, in the portion where the draft angle is on the obtuse angle side 9, the shear stress from the die edge 7 and the panel 4
Is smaller than that at the acute angle side 8, the crack generation timing is later than at the acute angle side 8. As a result, there is a shift in the timing of withdrawal between the acute angle side 8 and the obtuse angle side 9, and the acute angle side 8 breaks first, and the punching process is performed, but the obtuse angle 9 still breaks. No punching has been performed. For this reason, the scrap scrap is left on the obtuse angle side, the scrap is bent in the pulling direction, and the scrap cannot be completely removed, resulting in processing defects. Therefore, the present invention reduces the tensile stress of the panel at the acute angle side in the square hole punching processing of the inclined panel, thereby aligning the timings of the acute angle side and the obtuse angle side, so that the punching timing is always the same. The purpose is to eliminate the processing defects at the same timing.

[0004]

According to the present invention, there is provided a punching die for an inclined panel according to the present invention, comprising: a movable die movably disposed; a fixed die disposed opposite to the movable die at a predetermined angle; An inclined panel comprising a punch for square hole punching which is provided on a surface of a movable die opposed to the fixed die and whose peripheral edge portion is chamfered, and a die provided on the fixed die corresponding to the punch. In the punching die for punching, the amount of chamfering at a portion where the punching angle of the punch is acute is larger than the amount of chamfering at a portion where the punching angle is obtuse.

[0005]

The punch of the above structure presses the panel by lowering the movable die in the square hole punching process of the inclined panel, and the shearing stress from the die and the tensile stress applied to the panel when the punching angle is on the obtuse angle side. As a result, a crack occurs near the edge of the die and breaks. On the other hand, on the acute angle side, cracks occurred earlier and fractured earlier than on the obtuse angle side, but the chamfer amount on the acute angle side was larger than that on the obtuse angle side. As a result, the amount of the panel contacting the chamfered portion on the acute angle side (the amount of sticking) increases, and the deformation of the panel in the direction perpendicular to the plate thickness during the downward movement of the punch by a certain distance is reduced. Delay in thickness reduction. This means that the rate of change of the tensile stress applied to the vicinity of the punch of the panel is reduced. Thereby, the timing of crack generation on the acute angle side and the timing of fracture can be delayed on the acute angle side, and can be matched with the crack generation timing on the obtuse angle side. Therefore, in the square hole punching processing of the inclined panel, it is possible to uniformly punch the inclined panel at the same timing.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIGS. 1 to 3 show the configuration of the present invention. Reference numeral 5 denotes a movable upper die, which is fixed to a vertically movable ram (not shown). On the other hand, a molding surface faces the upper mold 5 below the upper mold 5 at a predetermined angle, and a fixed lower mold 6 is fixed on a bolster (not shown). Further, a punch 1 for punching a square hole having a quadrangular tip is attached to the lower part of the upper die 5 and a stripper for pressing and fixing the panel 4 so as to surround the punch 1. 3 are provided. The stripper 3 is made of a cushion material such as urethane or rubber. The lower end of the stripper 3 is located slightly below the tip of the punch 1 and is compressed as the upper die 5 descends to press and fix the panel 4. At the end, the panel 4 is paid by the elastic force. Reference numeral 2 denotes a die provided on the lower die 6 corresponding to the punch 1, and a die edge 7 is formed at the tip thereof. And the punch 1
Is formed in a rectangular cross section, and the bottom of the punch 1 forms a predetermined angle with respect to the drawing direction, and the acute side 8 where the drawing angle is acute and the obtuse side 9 where the drawing angle is obtuse.
And exists. The punch 1 is chamfered at the peripheral edge. As shown in FIGS. 1 to 3, this chamfer means that the angle between the chamfered portion and the bottom surface of the punch 1 is constant on both the acute angle side 8 and the obtuse angle side 9.
The angle of the chamfer on the acute angle side 8 of the punch 1 is set to 5 degrees, and the chamfer amount on the obtuse angle side 9 of the punch 1
It is large in the vertical direction, 1.5 times to 3 times,
If it is smaller than 1.5 times, the tensile stress on the acute angle side 8 cannot be reduced, and if it exceeds 3 times, there is a restriction on the shape of the punch 1 and cannot contribute to the present invention.

The operation of the punching die for an inclined panel having the above-described structure will be described. When punching the inclined panel, the upper die 5 descends while the panel 4 is placed on the upper surface of the lower die 6, and the stripper 3 provided on the upper die 5 presses and fixes the panel 4. Further, as the punch 1 is lowered, the pressing of the panel 4 is started. At this time, as shown in FIGS. 1 to 3, the chamfer amount on the acute angle side 8 of the punch 1 where the draft angle is acute is larger than that on the obtuse angle side 9 of the punch where the draft angle is obtuse. The thickness of the panel 4 contacting the vicinity of the chamfered portion on the acute side 8 of the punch 1 can be reduced, and the acute side 8 of the punch 1 can be delayed.
, The tensile stress of the panel 4 in contact with the panel is reduced. Thereby, it is possible to delay the generation of a crack in a portion of the panel 4 that abuts on the acute angle side 8 of the punch 1, and it is possible to generate a crack on the acute angle side 8 and the obtuse angle side 9 at the same timing,
Punching can be performed at the same timing. Therefore, square hole punching can be performed uniformly on the inclined panel.

In addition, since the clearance between the punch 1 and the die 2 is insensitive, the degree of freedom of the diameter of the punch 1 with respect to the diameter of the die 2 is high, and the punches 1 having different diameters can be used. The labor is reduced, and the cost can be reduced.

[0009]

As described above, in the square hole punching process of the inclined panel, since the tensile stress applied to the vicinity of the punch of the panel at the acute angle side is reduced, the punching at the acute angle side and the obtuse angle side is performed. The timing can be made uniform, and the squared hole processing of the inclined panel can be performed uniformly.

[Brief description of the drawings]

FIG. 1 is a front view showing a configuration of the present invention.

FIG. 2 is a perspective view of a punch according to the present invention.

FIG. 3 is a sectional view taken along the line III-III in FIG. 2;

FIG. 4 is a front view showing a configuration of a conventional technique.

FIG. 5 is a diagram schematically illustrating the operation of the conventional technique.

FIG. 6 is a graph showing the relationship between the clearance and the burr height according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Punch 2 ... Die 3 ... Stripper 4 ... Panel 5 ... Upper die 6 ... Lower die 7 ... Die edge 8 ... Acute angle side 9 ... Obtuse angle side 1a: chamfered portion 2a: edge portion

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B21D 28/34 B21D 28/32 B21D 28/16

Claims (1)

(57) [Claims] 1. A movable die movably disposed, a fixed die having a molding surface facing the movable die at a predetermined angle, and a movable die installed on a surface of the movable die facing the fixed die, In a punching die for an inclined panel, which is formed by a punch for punching a square hole having a chamfered tip peripheral portion and a die provided on the fixed die corresponding to the punch, the punching angle of the punch is an acute angle. A hole punching die for an inclined panel, wherein a chamfer amount of a portion to be formed is larger than a chamfer amount of a portion to become an obtuse angle.