JPH05138261A - Punching die for inclined panel - Google Patents

Abstract

PURPOSE:To reduce the tensile stress of the acute angle side of panel and to punch a square hole at the same timing by largely forming the chamfering amount of the place having an acute punched angle than the chamfering amount of the place having an obtuse punched angle in the punching die for an inclined panel. CONSTITUTION:A panel 4 is mounted on a lower die 6 and an upper die 5 is lowered, and the panel 4 is began to be pressed by lowering the punch 1. At this time, the tensile stress of the panel 4 can be reduced, because the reduction of the thickness of panel 4 abutting with the neighborhood of the chamfering part of the acute angle side 8 of the punch 1 can be delayed by making the chamfering amount of the acute angle side 8 of the punch 1 having the acute punched angle larger in comparing with the obtuse angle side 9 of the punch 1 having the obtuse punched angle. Therefore, the acute angle side 8 and the obtuse angle side 9 can be generated to crack at the same timing and worked with punching at the same timing.

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 a tilted panel used for punching a tilted panel.

[0002]

2. Description of the Related Art Conventionally, an apparatus for punching an inclined panel of a pressed product such as a door panel, a hood panel, etc., which is an automobile part, has an upper die which is vertically movable and a lower die facing the upper die. Then, a lower die installed at a predetermined angle with respect to a plane perpendicular to the drawing direction, a punch provided in the lower part of the upper die, and a die provided in the lower die corresponding to the punch. A punching die composed of and is used. Then, when punching the stamped product, after placing the stamped product on the lower die, the upper die descends, the punch presses the punched portion of the stamped product, and the punch and die Due to the shearing stress generated from the edge portion (blade portion), a crack is generated from at least one of the punch side and the die side, and a punched product is punched. However, in terms 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 within a narrow range as shown in FIG. In addition, 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 drag force from the slope (hereinafter referred to as the sliding force) acts on the tip of the punch, and this slippage occurs. When the force exceeds the static frictional force between the tip of the punch and the panel, the punch slides in the tilt direction and interferes with the die, which may cause damage to the punch and the die. Therefore, as a technique for setting the clearance within a range where the punch does not interfere with the die even if the punch slides and suppressing the occurrence of burrs, for example, Japanese Patent Laid-Open No. 1-
An apparatus as disclosed in Japanese Patent No. 293922 is used. This conventional technique will be described below with reference to FIGS. 3 and 4. 3 and 4, 1 is a punch, and 2
Is a die. A uniform chamfer is applied to the scrap-side tip peripheral edge of the punch 1 or the die 2, and an edge (blade) 2a is formed on the other tip peripheral edge. By chamfering 1a on either the punch 1 or the die 2, stress is always concentrated on the edge portion 2a on the non-chamfered side during processing. Due to this concentration of stress, a crack is always generated from the edge portion 2a side, and the non-chamfered side is broken. Thereby, the burr can be collected on the chamfered side (scrap side), the burr generation on the non-chamfered side is suppressed, and the burr generation on the product side is reduced. This is punch 1 and dice 2
Since the occurrence of burrs is reduced regardless of the clearance with, there is no need to set the clearance narrow,
It is possible to prevent the punch 1 and the die 2 from interfering with each other and prevent them from being damaged.

[0003]

However, in punching an inclined panel in which the molding surface has a predetermined angle with respect to a plane perpendicular to the punching direction, the punch 1 is obtuse with the acute side 8 where the punching angle is acute. There is an obtuse angle side 9 and the acute angle side 8 is a portion for pressing the punched line portion on the lower side of the inclined panel, and the obtuse angle side 9 presses the punched line portion on the upper side of the inclined panel. The part to be processed. At the portion where the punching angle is on the acute side 8, the thickness of the panel 4 is reduced by pressing the punch 1, and when the thickness becomes less than a certain thickness, shear stress from the die edge 7 causes a crack near the die edge to break. On the other hand, in the part where the draft angle is on the obtuse side 9, the shear stress from the die edge 7 part and the panel 4
Since the tensile stress applied to is smaller than that on the acute-angle side 8, the timing of crack generation is later than that on the acute-angle side 8. As a result, there is a deviation in the extraction timing 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 side 9 still breaks. Without punching. As a result, the scrap scrap remains on the obtuse angle side, the scrap is bent in the scraping direction, and the scrap cannot be completely removed, resulting in processing defects. Therefore, in the present invention, in the square hole punching process of the inclined panel, by reducing the tensile stress of the panel when the punching angle is an acute angle side, the punching timings of the acute angle side and the obtuse angle side are aligned, and the pulling angle is always equal. The purpose is to eliminate processing defects by punching at the same timing.

[0004]

In a punching die for an inclined panel according to the present invention, a movable die that is movably disposed, a fixed die that is installed to face the movable die at a predetermined angle, and A tilted panel that is installed on the surface of the movable die facing the fixed die and has a punch for punching a square hole with a chamfered peripheral edge and a die provided on the fixed die corresponding to the punch. In the punching die for use, the chamfering amount of the portion where the punching angle is an acute angle is made larger than the chamfering amount of the portion where the punching angle is an obtuse angle.

[0005]

[Function] In the square hole punching process of the inclined panel, the punch having the above-mentioned structure presses the panel by lowering the movable die, and when the punching angle is an obtuse angle, shear stress from the die and tensile stress applied to the panel As a result, a crack occurs near the edge of the die and breaks. On the other hand, when the draft angle is on the acute angle side, conventionally, cracks occurred at earlier timing than on the obtuse angle side, and fracture occurred, but the chamfering amount on the acute angle side was made larger than the chamfering amount on the obtuse angle side. As a result, the amount of contact (touching amount) of the panel on the acute angle side with the chamfer increases, and the deformation of the panel in the direction perpendicular to the plate thickness decreases while the punch descends a certain distance. The reduction of thickness is delayed. This means that the change rate of the tensile stress applied to the vicinity of the punch of the panel becomes small. This makes it possible to delay the timing of crack generation on the acute angle side and the timing of fracture on the acute angle side, and to match the timing of crack generation on the obtuse angle side. Therefore, in the square hole punching process of the inclined panel, it is possible to uniformly punch at the same timing.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 3 show the structure of the present invention, and 5 is a movable upper die, which is fixedly mounted on a vertically movable ram (not shown). On the other hand, below the upper mold 5, a molding surface faces the upper mold 5 at a predetermined angle, and a lower mold 6 as a fixed mold is fixedly mounted on a bolster (not shown). In addition, a punch 1 for punching a square hole having a quadrangular tip is attached to the lower portion of the upper die 5, and a stripper for pressing and fixing and wiping the panel 4 so as to surround the punch 1. 3 is provided. The stripper 3 is made of a cushioning material such as urethane or rubber, and its lower end is positioned slightly below the tip of the punch 1 and is compressed as the upper die 5 is lowered to press and fix the panel 4 for processing. At the end, the panel 4 is paid off by its 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
Of the punch 1 has a quadrangular cross section, and the bottom of the punch 1 forms a predetermined angle with respect to the drawing direction, and the acute angle side 8 has an acute angle and the obtuse angle side 9 has an obtuse angle.
And exist. The punch 1 is chamfered at the peripheral edge. As shown in FIG. 1 to FIG. 3, the chamfering means that the angle formed by 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 chamfering amount on the acute side 8 of the punch 1 is set to 5 degrees, and the chamfering amount on the obtuse side 9 of the punch 1 is larger than that on the punch 1 side.
It is large in the vertical direction, and is formed 1.5 times to 3 times.
If it is less 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 it cannot contribute to the present invention.

The operation of the punched die for the inclined panel constructed as above will be described. During punching of the inclined panel, the upper die 5 descends with the panel 4 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 accordingly. Further, as the punch 1 descends, the panel 4 starts to be pressed. At this time, as shown in FIGS. 1 to 3, as compared with the obtuse angle side 9 of the punch having an obtuse angle, the chamfering amount at the acute angle side 8 of the punch 1 having an obtuse angle is set to be large. It is possible to delay the decrease in the plate thickness of the panel 4 that comes into contact with the chamfered portion of the punch 1 on the acute side 8 of the punch 1.
The tensile stress of the panel 4 that abuts against is reduced. As a result, it is possible to delay the generation of cracks in the portion of the panel 4 that is in contact with the acute angle side 8 of the punch 1, and to generate the cracks at the acute angle side 8 and the obtuse angle side 9 at the same timing,
Punching can be done at the same timing. Therefore, in the inclined panel, square hole punching can be performed uniformly.

Further, since the clearance between the punch 1 and the die 2 is insensitive, the punch 1 has a high degree of freedom in the diameter of the die 2, and it is possible to use punches 1 having different diameters, which is used for clearance management. The labor can be reduced and the cost can be reduced.

[0009]

As described above, in the square hole punching of the inclined panel, the tensile stress applied to the vicinity of the punch of the panel on the acute angle side is reduced, so that the punching on the acute angle side and the obtuse angle side is performed. The timing can be made uniform, and it becomes possible to perform square hole punching of the inclined panel uniformly.

[Brief description of drawings]

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

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

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

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

FIG. 5 is a diagram schematically showing an operation of a conventional technique.

FIG. 6 is a graph showing the relationship between clearance and burr height in the prior art.

[Explanation of symbols]

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

Claims (1)

[Claims] 1. A movable die which is movably disposed, a fixed die whose molding surface faces the movable die at a predetermined angle, and a movable die which is placed on a surface of the movable die opposed to the fixed die. In an inclined panel punching die composed of a square punching punch having a chamfered peripheral edge and a die provided in the fixed die corresponding to the punch, the punching angle of the punch is an acute angle. A punching die for a tilted panel, characterized in that the chamfering amount of the portion to be formed is larger than the chamfering amount of the portion to have an obtuse angle.