JP2009241091A - Punching machine and method for metal sheet with inversely tapered punch and chamfered die - Google Patents

Abstract

A punching apparatus and method for reducing burrs on an end face of a punching process are provided.
The punch 8 includes a first parallel part 29 having the same cross-sectional shape including a cutting edge, and a punching direction rearward from the first parallel part 29. It has a reverse taper portion 9 whose outer diameter decreases toward the end, and the cutting edge of the die 11 is chamfered by being inclined in the punching direction, and the plate retainer 10 is a hollow portion 31 similar to the punching portion 30 of the die 11. The inner circumference c of the cavity 31 is not less than the outer circumference a of the first parallel portion 29 of the punch 8 and not more than the inner circumference b of the punched portion 30 of the die 11.
[Selection] Figure 4

Description

  The present invention relates to a punching apparatus and a punching method for a metal plate such as iron, aluminum, titanium, magnesium, and alloys thereof used in automobiles, home appliances, building structures, ships, bridges, construction machines, various plants, penstocks, and the like. In particular, it relates to the reduction of burrs caused by punching.

  Metal plates such as automobiles, home appliances, and building structures are punched with a punch 2 and a die 3 as shown in FIG. 1A, or processed with a punch 2 and a die 3 as shown in FIG. 1B. A cutting and punching process for cutting the material 1 back and forth is often performed. As shown in FIG. 2, the punched end face is defined as a sag 4 formed by the workpiece 1 being entirely pushed by the punch 2, and within the clearance between the punch 2 and the die 3 (hereinafter referred to as “clearance” unless otherwise specified). In this case, the workpiece 1 is drawn into the clearance between the punch 2 and the die 3, and the workpiece 1 drawn into the clearance between the punch 2 and the die 3. 1 is constituted by a fracture surface 6 formed by breaking and a burr 7 formed on the back surface of the workpiece 1.

  In order to increase the smoothness of the punched end surface, it is effective to use a taper punch as described in Patent Document 1 and perform punching and cutting while burnishing the punched surface. The material extruded at this time May be a big burr, which is a problem.

  Many conventional techniques for reducing burrs at the time of punching have been proposed. For example, a punching method using a punch with a reverse taper is generally used. In this punching method, since the contact area between the punch side surface and the punching end surface is reduced, the punch is not easily worn, the sliding resistance of the punch is reduced, and the amount of meat to be pushed to the die shoulder is reduced, so that occurrence of burrs can be suppressed. On the other hand, burrs are also crushed by coining after punching (Patent Document 2).

  Further, Patent Document 3 discloses a method of punching out a plate in a bent state using a chamfering die and a plate presser and shifting the burr generation direction from the plate thickness direction.

  Patent Document 4 describes a method of drilling at the first stage and removing burrs at the second stage using a two-stage punch.

  Patent Document 5 describes a method of suppressing the generation of burrs by chamfering a die.

  Non-Patent Document 1 describes a method in which burrs are not generated by making a difference in sharpness between the die and the cutting edge of the punch and generating a crack from one of the die and punch.

JP-A-11-333530 JP-A-6-57325 JP 2006-43757 A JP 2006-281323 A JP 2002-172435 A Proceedings of the 39th Plastic Working Joint Lecture pp. 483-486

  However, there are several problems with the disclosed technology.

  The reverse tapered punch and the methods described in Patent Documents 2, 3, 5, and Non-Patent Document 1 have an effect of suppressing the generation of burrs at the time of punching, but have no effect of crushing the generated burrs. It is impossible to prevent burrs caused by extrusion using a taper punch.

  The method disclosed in Patent Document 4 is effective for fine burrs extending on the inner surface of the punching hole, but not effective for burrs extending in the plate thickness direction (punching direction) of the workpiece.

  The present invention provides an apparatus and method that can prevent the generation of relatively large burrs (about 10% of the plate thickness) caused by the extrusion of a material to the die side, such as using a taper punch. Objective.

In order to solve the above problems, the gist of the present invention is as follows.
(1) A punching device for a metal plate having a punch, a die, and a plate press, wherein the punch includes a first parallel portion having the same cross-sectional shape including a cutting edge, and a punching direction from the first parallel portion. The die has a reverse taper portion whose outer diameter decreases toward the rear, and the cutting edge of the die is chamfered by being inclined in the punching direction, and the plate retainer is a cavity similar to the punched portion of the die A reverse taper punch and a chamfer, wherein the inner circumferential length of the hollow portion is not less than the outer circumference of the first parallel portion of the punch and not more than the inner circumference of the punched portion of the die. Metal plate punching machine with a die.
(2) The inverted taper punch and the chamfering die according to (1), wherein the punch has a tapered portion whose outer diameter increases toward the rear in the punching direction in front of the first parallel portion in the punching direction. Punching machine for metal plates.
(3) The punch has a second parallel part smaller than the outer diameter of the first parallel part in front of the taper part in the punching direction, and has a curved surface with a radius of curvature of 0.5 to 10 mm. The apparatus for punching a metal plate using a reverse taper punch and a chamfering die according to (2), wherein the metal plate is chamfered.
(4) The punch has a stepped portion whose outer diameter is smaller in the punching direction rearward than the outer diameter of the first parallel portion instead of the reverse tapered portion (1) to (3) A punching device for a metal plate by using a reverse taper punch and a chamfering die according to any one of the above.
(5) The die shape of the die chamfered is a convex curved surface, and the metal plate is punched by the reverse taper punch and the chamfer die according to any one of (1) to (4). Processing equipment.
(6) The die chamfered inclined shape satisfies an elastic deformation range of the metal plate when the metal plate is bent along the chamfered inclination (1) to ( 5) A metal plate punching apparatus using the reverse taper punch and the chamfering die according to any one of 5).
(7) Using the apparatus according to any one of (1) to (6), the first parallel portion of the punch is made of the metal plate while restraining the metal plate with a die and a plate presser. The punch is advanced to the punched portion of the die until it is positioned below, and the metal plate is punched out. Then, the punch is pulled out in the direction opposite to the punching direction, and burrs generated on the metal plate are removed from the reverse of the punch. A metal plate punching method using a reverse taper punch and a chamfering die, wherein the metal plate is crushed by a taper portion or the stepped portion.

  According to the present invention, it is possible to prevent the generation of relatively large burrs (about 10% of the plate thickness) due to the extrusion of the material to the die side, such as using a taper punch.

  Details of the present invention will be described below.

  The present invention is characterized in that a part for crushing burrs is provided on the punch side, and a part for easily crushing burrs generated on the die side is provided.

  Nowadays, devices such as servo press machines that can generate a stable load regardless of the position of the ram are spreading, and free movement that has not been considered in the past has been applied to the mold. It is possible to grant. The present inventors pay attention to the positive use of punch drawing motion, and if the punch shape, die shape, and stripper are as shown in FIG. 3, it is possible to crush large burrs generated during punching. It was discovered (the invention according to (1) above).

  As shown in FIG. 3, the punching processing apparatus according to the present invention includes a punching punch 8 (reverse taper punch, also simply referred to as a punch), a die 11 having an inclined portion 12 formed on a blade edge, and a plate presser 10. The punch 8 of the present embodiment has a first parallel portion 29 having the same cross-sectional shape including the cutting edge on the distal end side, and on the proximal end side toward the rear in the punching direction, that is, as the punching proceeds. It has the reverse taper part 9 in which a diameter becomes small.

  The plate retainer 10 has a hollow portion 31 similar to the punched portion 30 of the die 11. The length c of the inner periphery of the hollow portion 31 of the plate retainer 10 is set to be equal to or greater than the outer periphery a of the first parallel portion 29 of the punch 8 so that the clearance is equal to or greater than 0. 11 or less of the inner periphery b of the punched portion 30.

  If the punching apparatus shown in FIG. 3 is used, after the workpiece 1 is punched into a predetermined shape such as a round hole by the first parallel portion 29 as shown in FIG. 4, the workpiece caused by the die inclined portion 12 is processed. Due to the elastic deformation of the material 1, the direction in which the burrs 7 are generated changes from the plate thickness direction (FIG. 4 (a) downward direction on the paper) to the punch 8 side (same left direction), and as shown in FIG. When pulling out 8, the burr 7 comes into contact with the reverse tapered portion 9 of the punch 8. At this time, if the workpiece 1 is suppressed by the plate presser 10 with a force larger than the pulling force of the punch 8, the burr 7 is crushed as shown in FIG. invention).

  The force with which the punch is pulled out is about several tens [kg / mm] per unit punching line length even if estimated to be large, and if it is a generally circulating plate pressing mechanism using a urethane spring or a gas pressure cushion, the burr 7 is used. Enough to crush.

  However, since the amount of the burr 7 that can be crushed decreases if the clearance amount is large, it is most effective to set the clearance amount to about 0 to 10% of the workpiece thickness in order to use the present invention.

  As for the position and angle of the reverse tapered portion 9, as shown in FIG. 5, any slope of the reverse tapered portion 9 of the punch 8 coincides with the position of the burr 7 of the workpiece 1 at the punch bottom dead center position. It must be set to be positional. Since the setting of the bottom dead center varies depending on the press device, the mold, and the material to be used, individual settings are required for the reverse tapered portion 9.

  The present invention is particularly effective when a taper portion whose outer diameter increases with the progress of punching is provided in front of the parallel portion of the punch (the invention according to (2) above).

  When using a taper punch with an outer diameter that simply increases with the progress of punching and then a parallel portion is formed, the material is pushed out to the die side to obtain a smooth end surface. Large burrs are likely to occur even with a small clearance.

  Therefore, if the punch 13 is provided with a tapered portion 14 whose outer diameter increases as the punching progresses as shown in FIG. 6 in front of the first parallel portion 29 of the punch shown in FIG. Thus, the material is pushed to the die side to smooth the end face, so that the portion that has conventionally become the burr 7 can be crushed by the reverse tapered portion 9. At this time, in order to push the material to the die side, it is desirable that the taper angle of the taper portion 14 is about 10 to 30 degrees with respect to the vertical line in order to prevent punch seizure.

  Further, as shown in FIG. 7, a second parallel portion 17 smaller than the outer diameter of the first parallel portion 29 is provided in front of the tapered portion 14 shown in FIG. If the punch 15 is chamfered into a curved surface with a radius of curvature of 10 mm, the cost of creating the punch increases, but the material is less likely to break, so the amount of material flow required to obtain a smooth end surface is reduced, As a result, since the frictional resistance between the punch and the material is reduced, it is possible to increase the punch life as compared with the shape of the punch 13 as shown in FIG. 6 (the invention according to (3) above).

  If the radius of curvature of the cutting edge 16 is less than 0.5 mm, the effect of making the material difficult to break is thin if the cutting edge is not rounded, so there is no significant difference in the smoothness of the end face. Since a large amount of the material is dragged into the die part, the amount of sag around the punching hole is large and the smoothness of the end face may be deteriorated. Therefore, the curvature radius of the cutting edge may be 0.5 to 10 mm. preferable. At this time, in order to prevent punch burn-in, the punch stroke amount from the punch tip to the target punching diameter (the diameter of the first parallel portion 29), that is, the second parallel portion 29 and the tapered portion from the tip of the blade edge 16 is determined. The vertical length to the boundary of 14 is preferably less than 100% of the workpiece thickness, and the taper angle of the tapered portion 14 for sweeping the material is preferably about 10 to 30 degrees with respect to the vertical line. .

  In the present invention of (1) to (3), as shown in FIG. 8, a stepped portion 19 may be provided instead of the reverse tapered portion 9 (the invention according to (4) above). In this case, the burr 7 is scraped rather than crushed, and the smoothness of the punched end face cannot be improved. However, unlike the reverse tapered portion 9, the punch stroke amount when removing the burr is slightly reduced. Therefore, it is superior to the case of using the reverse tapered portion 9 in terms of mold wear. If the height of the step ((diameter of the first parallel portion 29−diameter of the rear portion 32 of the step portion 19) / 2) is 5% or more of the punch diameter (diameter of the first parallel portion 29), the burrs will be sufficient. It is possible to scrape off. On the other hand, if it is too large, the pulling force may be insufficient and the punch may be caught, or burrs may be generated on the upper surface side of the workpiece 1, and the step is preferably 20% or less of the punch diameter.

  As shown in FIG. 3, when the inclined portion 12 of the die 11 is linear, the amount of strain caused by bending applied to the workpiece 1 during punching is concentrated at the boundary between the inclined portion 12 and the flat portion, and is punched out. The amount of tilt must be reduced to prevent product deflection. However, if the inclined portion 21 of the die 20 has a convex curved surface as shown in FIG. 9, the bending applied to the workpiece 1 at the time of punching is diffused over the entire portion in contact with the inclined portion 21 of the workpiece 1. The upper limit of the limit die tilt amount at which the punched product can be bent can be increased (the invention according to (5) above). If the die inclination amount is increased, the direction of the burr 7 can be shifted to the punch side, so that the amount of the burr 7 that can be removed by the reverse taper portion 9 or the step portion 19 of the punch can be increased.

  In order to obtain the die inclined portions 12 and 21 that can prevent the product from being bent, the die inclined portions 12 and 21 may be designed so that the amount of bending of the workpiece 1 by the die inclined portions 12 and 21 falls within the elastic range of the material ((6) above). Invention). If the punching shape is a simple shape such as a straight line or a circle, it is possible to derive the die inclined part shape analytically, but in many cases it is a complicated punching shape. It is effective to derive the shapes of the die inclined portions 12 and 21 using a simple numerical simulation. Specifically, several finite element simulations with different die tilt amounts may be performed to determine the tilt amount limit at which plastic strain does not occur.

  As Example 1 of the present invention, a 10 mm diameter circular hole was punched into 10 test pieces using the punch 22, die 23, and plate retainer 24 shown in FIG. 10, and a test for measuring the burr height of the punched hole was performed.

  The punching clearance was 12% of the thickness of the workpiece, and a 3 mm thick hot rolled steel plate having a tensile strength of 440 MPa was used as the workpiece. Further, a gas pressure type cushion is used for the load generating mechanism of the plate presser 24, and a punch pull-out load of 200 kg can be generated near the bottom dead center of the punch. The amount of inclination of the inclined portion 12 of the die 23 was set to 3 degrees, the horizontal direction from the die cutting edge was 4 mm, and the cross-sectional shape of the hollow portion of the plate presser was a circle having a diameter of 10.5 mm.

  As a comparative example, the punch 22 and the plate presser 24 are common to the example of the present invention, and a die that does not have the inclined portion 12 described above was used. Other conditions were the same as those of the example of the present invention.

  The burr height was a distance in the plate thickness direction between the burr tip and the lower surface of the workpiece, and was measured by image analysis of an optical microscope image of a test piece in which a hole cross section of the workpiece 1 was cut out and embedded with resin.

  The measurement result of the burr height after punching measured by the above method is 17 μm on average in the case of the present invention example 1. In the comparative example, the average burr height of the punched specimen is 18 μm. About 5% burr height could be reduced.

  Subsequently, as Example 2 of the present invention, only the punch was used as the punch 25 having the shape shown in FIG.

  The average burr height measurement result after punching is 15 μm in the case of the present invention example 2, and the conventional punching method performed as a comparative example (only the punch 25 is common to this embodiment, and no chamfering die is used. The burr height was reduced by about 60% in the punching method according to the present invention.

  Subsequently, as Example 3 of the present invention, only the punch was made the punch 26 having the shape shown in FIG.

  The measurement result of the burr height after punching is 13 μm on average in the case of the present invention example 3, and the conventional punching method performed as a comparative example (only the punch 26 is common to the present embodiment, and the chamfering die is not used. The burr height was reduced by about 50% in the punching method according to the present invention, whereas the average burr height of the punched test piece by 25) was 25 μm.

  Subsequently, as Example 4 of the present invention, only the punch was used as the punch 27 having the shape shown in FIG.

  The average burr height measurement result after punching is 18 μm in the case of the present invention example 4, and the conventional punching method performed as a comparative example (only the punch 27 is common to the present embodiment, and no chamfering die is used. The burr height was reduced by about 50% in the punching method according to the present invention.

  Subsequently, as Example 5 of the present invention, only the die was the die 28 having the shape shown in FIG. 14, and the other tests were performed in the same manner as in Example 1.

  The burr height measurement result after punching is 12 μm on average in the case of the present invention example 5, and the conventional punching method performed as a comparative example (only the punch 22 is common to this embodiment, and no chamfering die is used. The burr height was reduced by about 30% with the punching method according to the present invention.

  The present invention can be applied to a punching apparatus and punching method for a metal plate such as iron, aluminum, titanium, magnesium, and alloys thereof.

It is the figure which showed the general hole punching process typically, (a) shows a hole punching process, (b) shows a cutting punching process. It is a figure which shows typically the punching end surface of the to-be-punched material. It is a figure which shows typically the structure of the punching apparatus of this invention. It is explanatory drawing which shows typically the mechanism which crushes the burr | flash of a punching end surface by this invention, (a) is during a punching, (b) shows the extraction start stage from the bottom dead center of a punch after punching, (c) is punching Indicates that the rear punch is being pulled out. It is a figure which shows the burr | flash position of a desirable reverse taper part and a punching edge part in the bottom dead center position of a punch. It is a figure which shows typically the different punch shape of this invention. It is a figure which shows typically further different punch shape of this invention. It is a figure which shows typically further different punch shape of this invention. It is a figure which shows typically the die | dye shape from which this invention differs. It is a figure which shows typically the punching die used for Example 1. FIG. It is a figure which shows typically the punching punch shape used for Example 2. FIG. It is a figure which shows typically the punching punch shape used for Example 3. FIG. It is a figure which shows typically the punching punch shape used for Example 4. FIG. It is a figure which shows typically the punching die shape used for Example 5. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Work material 2 Punch 3 Die 4 Sag 5 Shear surface 6 Fracture surface 7 Burr 8, 13, 15, 18, 22, 25, 26, 27 Punch 9 Reverse taper part 10, 24 Plate presser 11, 20, 23, 28 Die 12, 21 Inclined part 14 Taper part 16 Cutting edge 17 Second parallel part 19 Step part 29 First parallel part

Claims (7)

A punching device for a metal plate having a punch, a die and a plate presser,
The punch has a first parallel part having the same cross-sectional shape including the cutting edge, and a reverse taper part whose outer diameter decreases from the first parallel part toward the rear in the punching direction,
The cutting edge of the die is chamfered to be inclined in the punching direction,
The plate retainer has a hollow portion similar to the punched portion of the die, and the length of the inner periphery of the hollow portion is equal to or greater than the outer periphery of the first parallel portion of the punch and the punched portion of the die. An apparatus for punching a metal plate with a reverse taper punch and a chamfering die, characterized by being equal to or less than the inner circumference.   2. The metal plate using a reverse taper punch and a chamfering die according to claim 1, wherein the punch has a taper portion whose outer diameter increases toward the rear in the punching direction in front of the first parallel portion in the punching direction. Punching machine.   The punch has a second parallel part smaller than the outer diameter of the first parallel part in front of the taper part in the punching direction, and the cutting edge is chamfered into a curved surface having a radius of curvature of 0.5 to 10 mm. The punching apparatus for a metal plate by using an inverted taper punch and a chamfering die according to claim 2.   4. The punch according to claim 1, wherein the punch has a stepped portion whose outer diameter is smaller in the punching direction rearward than the outer diameter of the first parallel portion, instead of the reverse tapered portion. A metal plate punching apparatus using a reverse taper punch and a chamfering die.   The metal plate punching apparatus according to any one of claims 1 to 4, wherein the inclined shape of the die chamfered is a convex curved surface.   The chamfered inclined shape of the die satisfies an elastic deformation range of the metal plate when the metal plate is bent along the chamfered inclination. A punching device for a metal plate using the reverse taper punch and the chamfering die according to item 1.   The apparatus according to any one of claims 1 to 6, wherein the first parallel portion of the punch is positioned below the metal plate while constraining the metal plate with a die and a plate presser. After the punch is advanced to the punched portion of the die and the metal plate is punched out, the punch is pulled out in the direction opposite to the punching direction, and the burr generated on the metal plate is caused by the reverse tapered portion or the step portion of the punch. A metal plate punching method using a reverse taper punch and a chamfering die characterized by crushing with a chamfer.

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