JPH07148700A - Shearing working method without burr - Google Patents

Abstract

PURPOSE:To perform shearing working without the generation of a burr by protruding a pin, inserted in a punch, after punching in the incomplete punched state so as to apply tension to a scrap area to rupture it. CONSTITUTION:When a punch 5 bites into sheet metal material W, the part pushed out by the punch 5 is put in the incompletely punched state, and cracks are generated from the edge part of a die hole 7a and the part corresponding to the edge.part of the punch. In this case, a negative clearance is previously provided between the punch 5 and the die hole 7a. The crack generating direction is thereby different from the case of having a positive clearance so as to generate no burr. In this state, when a scrap area S is pushed out by a pin 8, the tension toward the center of the scrap area S acts upon the scrap area S while being plastically deformed, so that the scrap area S is ruptured from the crack generating position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shearing method which does not cause burrs.

[0002]

2. Description of the Related Art As a shearing method that does not produce burrs, there are known methods such as a vertical punching method, a flat pressing method and an ultrahigh pressure gas method.

The flat pressing method is described in Japanese Examined Patent Publication No. 30-5896 and "Research on Machines, 10-1 (1958), 140".
As shown in FIG. 7, a pair of dies 51A and 51B and punches 52A and 52B are arranged above and below,
As a first step, as shown in FIG.
A and the punch 52A cause the punch 52A to bite into the plate thickness of the sheet metal material W to make the scrap region S extruded by the punch 52A into an incomplete punching state, while in the second step (B) of FIG. As shown in FIG. 2, the scrap area S is formed by the other die 51B and the punch 52B.
Is a method of punching and breaking in the opposite direction.

Further, the flat pressing method is disclosed in JP-A-55-84232.
Gazette and "Press Technology, 13-5 (1975), 9"
3 ”as shown in FIG.
The diameter of the punch 54 is made larger than the diameter of the die hole 53a, and a so-called negative clearance is provided in advance. In the first step, as shown in FIG. Push the punch 54 up to
The scrap region S pushed out by the punch 54 is brought into an incomplete punching state, and in the second step, the sheet metal material W is pressed and restrained by the flat die 55 and the punch 56 as shown in FIG. It is a method of breaking the scrap area S by pushing it back. There is also a roll blanking method in which a roll is used instead of the die 55 and punch 56 of the flat pressing method.

On the other hand, the ultra-high pressure gas method is introduced in "Lecture Proceedings of 1993 Plastic Working Spring Lecture Meeting (1993), 737". As shown in FIG. In this method, the material W (aluminum foil or copper foil) is pressure-restrained, and then the scrap region S is broken by applying an ultrahigh-pressure gas pressure from the hole 59 on the pad 58 side.

[0006]

According to the flat pressing method shown in FIG. 7, two sets of dies 51A and 51B and punches 52A and 52B are used.
Since it is necessary to drive the punches 52A and 52B from both the upper and lower directions by coexisting with each other, the structure of the press machine becomes extremely complicated. In addition, the flat pressing method shown in FIG. 8 requires the processing to be performed in two steps, so that the number of processing steps (the number of steps) cannot be reduced, and the press equipment cost rises accordingly. As a result, it is not preferable.

Further, what is common to the above-mentioned top-bottoming method and the flat pressing method is that the punched scrap area S remains on the punch 52B (FIG. 7), or on the die 55 together with the processed sheet metal material W. It will be left in the scrap area (Fig. 8).
It is not preferable because a mechanism for processing is required.

Further, the ultrahigh pressure gas method shown in FIG. 9 depends on the gas pressure from the beginning of the plastic deformation of the sheet metal material W to the breakage thereof. In addition to the large sag R generated at the peripheral portion, the use of ultrahigh pressure gas leads to an increase in the size of the equipment, and the equipment cost becomes extremely high.

The present invention has been made in view of the above problems, and it is possible to perform the desired burr-free shearing processing with a relatively simple facility and a minimum number of processing man-hours. It is to provide the method.

[0010]

The invention according to claim 1 is a method of shearing a sheet metal material by a shearing action of a die and a punch in a state where the sheet metal material is pressure-constrained by a die having a die hole and a pad. Then, a punch having a diameter larger than the die hole diameter is bitten into the sheet metal material to the middle of its thickness, and the scrap region extruded by the punch is incompletely punched, and then the die and the punch are formed. Is stopped, and then the pin previously inserted in the punch is projected from the front end surface of the punch to apply a tensile force to the scrap region to break the pin.

The above-mentioned pins are driven using, for example, hydraulic pressure or a mechanical drive mechanism. The negative clearance given by making the punch larger than the die hole diameter is in the range of 5 to 10% of the plate thickness, while the bite amount of the punch into the sheet metal material is 60 to 70% of the plate thickness. The degree.

The invention of claim 2 is the same as that of claim 1 until the scrap area is incompletely punched, but thereafter, the scrap area is passed through a gas supply hole formed in advance in the punch to reach the scrap area. It is characterized in that it is broken by applying a high gas pressure and applying a tensile force to the scrap region.

[0013]

According to the first aspect of the present invention, when the punch is cut into the sheet metal material, the portion extruded by the punch is incompletely punched out, and the portion corresponding to the edge of the die hole and the edge of the punch. A crack is generated from each. In this case, since the negative clearance is previously provided between the punch and the die hole, the crack generation direction is different from that in the case where the positive clearance is provided, and the flash does not occur.

In this state, when the scrap region is extruded by the pin, the scrap region is plastically deformed and a tensile force toward the center thereof acts, so that the scrap region breaks from the crack generation position.

According to the invention of claim 2, claim 1
Since the pushing force by the gas pressure acts on the scrap region instead of the pushing force by the pin, the scrap region breaks under the same behavior as in claim 1.

[0016]

1 to 3 are views showing an embodiment of the present invention, and FIG. 1 shows a state in which an essential part of FIG. 2 is enlarged.

As shown in FIG. 2, a pad 3 is elastically supported by an upper holder 1 fixed to a press ram (slide) 10 via an elastic body 2 such as urethane rubber so as to be movable up and down, and a punch retainer. Piercing punch 5 through 4
Is fixedly supported. On the other hand, a button die 7 corresponding to the piercing punch 5 is fixedly supported on the lower holder 6. Then, as shown in FIG. 3, the piercing punch 5 is used.
The diameter D of the tip portion of is larger than the diameter d of the die hole 7a, and a so-called negative clearance is provided between the two. The clearance C is set to about 5 to 10% of the plate thickness t of the sheet metal material W to be processed as shown in FIG.

Further, the piercing punch 5 is formed in a hollow shape, and a pin 8 is provided therein so as to be vertically movable. The tip of the pin 8 is formed in a hemispherical shape and is relatively chamfered, and a large-diameter flange portion 8a is integrally formed at the upper end of the pin 8 so that the tip portion of the pin 8 can be pierced by the piercing punch 5. The stroke of the pin 8 is set so that the pin 8 can project from the tip surface of the pin by a predetermined amount.

As shown in FIG. 2, hydraulic pressure is supplied to the inside of the pierce punch 5 from the hydraulic pump 9, and the pin 8 receives this hydraulic pressure with the flange portion 8a as the pressure receiving surface. , Pin 8 is piercing punch 5
Will be forced out from.

At the time of press working, when the sheet metal material W is positioned on the lower holder 6 and then the upper holder 1 is lowered together with the press ram 10 as shown in FIGS. The elastic body 2 is gradually compressed by coming into contact with the material W, whereby the lower holder 6 and the pad 3 press and restrain the sheet metal material W. At this time, no hydraulic pressure acts on the pin 8.

When the upper holder 1 descends, the piercing punch 5 comes into contact with the sheet metal material W, and further, FIG.
As shown in FIG. 3, the piercing punch 5 bites into the sheet metal material W by the shearing action of the die hole 7a and the piercing punch 5, and the scrap region S of the sheet metal material W extruded downward by the piercing punch 5 is in an incomplete punching state. .

Then, as shown in FIG. 3, the lower limit position of the plus ram 10 is set in advance so that the bite amount e of the piercing punch 5 into the sheet metal material W is about 60 to 70% of the sheet thickness t of the sheet metal material W. Therefore, the amount of bite of the piercing punch into the sheet metal material W is 60 to 70% of the sheet thickness.
When it becomes, the piercing punch 5 is temporarily stopped, and the so-called dwell state is maintained for a predetermined time.

Here, as shown in FIG. 3 in addition to FIG. 1B, when the piercing punch 5 bites into the sheet metal material W, a sag R is generated on the upper surface side of the sheet metal material W and the tip of the piercing punch 5 is formed. A crack Q is generated in the vertical direction at the portion where the edge portion hits and the portion where the edge portion of the die hole 7a hits. However, as described above, the so-called negative clearance C is provided in advance so that the diameter D of the piercing punch 5 is larger than the die hole diameter d by about 5 to 10% of the plate thickness t of the sheet metal material W. Therefore, as compared with the case where a positive clearance is provided, the generation direction of the crack Q is opposite, and no burr is generated on the lower surface side of the sheet metal material W.

That is, the crack Q due to shearing is generated along the line connecting the edge portion of the pierce punch 5 and the edge portion of the die hole 7a, and when a positive clearance C is provided, as shown in FIG. The flash F is unavoidable, but in the present embodiment, the flash F does not occur because the line connecting the edge portion of the piercing punch 5 and the edge portion of the die hole 7a has an opposite slope.

Subsequently, when the piercing punch 5 is in the dwell state as described above, hydraulic pressure is supplied from the hydraulic pump 9 into the piercing punch 5 as shown in FIG. 2 in addition to FIG. The pin 8 is forced out from the tip of the pin 5. As a result, the central portion of the scrap region S is pushed and gradually bent, and at the same time, a tensile force is applied to the scrap region S from its peripheral portion toward the center, so that the scrap region S will eventually reach the limit of plastic deformation. If it exceeds, it will break from the crack Q. Since this final breaking is performed by the pulling force as described above, no burr is generated at the peripheral portion of the processed hole H.

Since the scrap area S punched out by fracture has a diameter smaller than the die hole diameter due to deformation during shearing, the scrap area S will drop downward due to its own weight. Scrap area S generated by the subsequent press working even if
Since they are sequentially pushed by, they will eventually fall by their own weight.

4 to 6 are views showing another embodiment of the present invention, in which the same parts as those of the first embodiment described above are designated by the same reference numerals.

As shown in FIGS. 4 and 5, the piercing punch 15 is used.
The first embodiment differs from the first embodiment in that a gas supply hole 15a is formed in the central portion of the chamber and is opened at its tip end surface, and this gas supply hole 15a is connected to the high pressure gas generator 19. Then, as shown in FIG. 6, the clearance C between the die hole 7a and the piercing punch 15 is 5 to 1 of the plate thickness t of the sheet metal material W to be processed as in the first embodiment.
A value of 0% is given as a negative clearance, and the bite amount e of the piercing punch 15 into the sheet metal material W is similarly set to about 60 to 70% of the sheet thickness t.

In the case of the present embodiment, as shown in FIG. 5A, the piercing punch 1 penetrates into the sheet metal material W up to about 60 to 70% of the sheet thickness t thereof.
It is the same as the first embodiment until 5 becomes stationary and becomes a dwell state.

After this, the high-pressure gas is supplied from the high-pressure gas generator 19 of FIG. 4 to the gas supply hole 15a of the pierce punch 15, and the gas pressure acts on the scrap region S in the incomplete punching state as it is. Become. As a result, the scrap region S that has received the gas pressure is pushed and gradually deformed downward, and at the same time, the tensile force shown by the arrow f acts on the scrap region S, so that the scrap region S eventually undergoes plastic deformation. If the limit is exceeded, the fracture will start from the crack portion Q that has occurred earlier.

That is, also in the second embodiment, since the tensile force is applied to the scrap area S by the pressure of the high-pressure gas, the scrap area S causes burrs under the same behavior as in the first embodiment. Breaks without

[0032]

As described above, according to the invention of claim 1,
The punch, which has a larger diameter than the die hole diameter and has a negative clearance, penetrates halfway through the plate thickness of the sheet metal material to make an incomplete punching state, after which the pin inserted in the punch is ejected and the scrap area By applying tensile force to rupture, it is possible not only to perform shearing without burrs, but also to reduce processing man-hours because the processing can be completed in one process, and the existing Since it can be carried out by making a slight modification to the equipment, the press equipment can be simplified and the equipment cost can be reduced. In addition, since a scrap area associated with shearing is generated on the die hole side, no special scrap processing means is required, which also simplifies the equipment and reduces the equipment cost.

According to the second aspect of the present invention, in addition to the above-mentioned effects, since shearing is carried out halfway and then ruptured by gas pressure, a large droop like the conventional ultrahigh pressure gas method is used. If it does not occur, the gas pressure itself can be greatly reduced, and the molding quality can be improved and the equipment cost can be further reduced.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of the present invention, and an operation explanatory view of a main part of the press die shown in FIG.

FIG. 2 is an explanatory sectional view of a press-type structure to which the method of the present invention is applied.

FIG. 3 is an enlarged view of a main part of FIG.

FIG. 4 is an explanatory cross-sectional view of a press-type structure to which another method of the present invention is applied.

5 is an operation explanatory view of a main part of the press die shown in FIG.

FIG. 6 is an enlarged view of a main part of FIG.

FIG. 7 is an explanatory diagram of a conventional top and bottom extraction method.

FIG. 8 is an explanatory diagram of a conventional flat pressing method.

FIG. 9 is an explanatory view of a conventional ultrahigh pressure gas method.

FIG. 10 is an explanatory diagram at the time of shearing when a general positive clearance is given.

[Explanation of symbols]

 3 ... Pad 5 ... Piercing punch 7 ... Button die 7a ... Die hole 8 ... Pin 15 ... Piercing punch 15a ... Gas supply hole S ... Scrap area W ... Sheet metal material

Claims (2)

[Claims] 1. A method of shearing a sheet metal material by a shearing action between a die and a punch in a state in which the sheet metal material is pressure-constrained by a die having a die hole and a pad, and having a diameter larger than the diameter of the die hole. The punch is made to bite into the sheet metal material in the middle of its plate thickness, the scrap area extruded by the punch is incompletely punched, and then the relative movement of the die and the punch is stopped, and thereafter, A flashless shearing method, characterized in that a pin inserted in advance in the punch is projected from the front end surface of the punch and broken by applying a tensile force to the scrap region. 2. A punch having a diameter larger than the diameter of the die hole is made to penetrate into a sheet metal material up to the middle of its thickness, and the scrap region extruded by the punch is incompletely punched, and then the die is pressed. The relative movement between the punch and the punch is stopped, and thereafter, high pressure gas pressure is applied to the scrap area through a gas supply hole formed in advance in the punch to apply a tensile force to the scrap area to break the punch. The flashless shearing method according to claim 1.