JPH0857557A - Metal plate punching die and processing method - Google Patents

Abstract

(57) [Summary] [Purpose] For punching metal plates, punching is performed by adjusting the punching clearance to an appropriate value using a mold that does not require any special equipment and can be manufactured in almost the same way as the conventional method. Prevent cracking. [Structure] The tip of the punch is chamfered to 5 to 20% of the punch diameter and the clearance is set to 6 to 10% of the plate thickness. In addition, a crack-free punching method that promotes crack initiation and controls crack growth.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a machining tool and a machining method for punching or punching a metal plate.

[0002]

2. Description of the Related Art In metal plate processing for automobile parts and the like, a punching process using a press machine is always included. In particular, when punching a bolt hole or a decorative hole for air cooling with a steel plate of 3 mm or more for a wheel, cracks or minute cracks occur at the punched end face, which is a problem. Due to the generation of these cracks and minute cracks, the fatigue durability of the wheel is significantly impaired and it cannot be used as a product. Further, also in the strength parts of other automobiles, the cracks and minute cracks have an adverse effect such that the paint does not ride well during coating and the corrosion resistance is impaired. The cracking is expected to be improved by increasing the ductility of the material, but the reduction of the material strength leads to the reduction of the product strength and the deterioration of the fatigue characteristics, which is a problem. further,
Due to the recent needs for weight reduction of automobile companies, the strength of materials has been increased, the ductility of materials has deteriorated, and punching cracks are more likely to occur.

For this reason, conventionally, in punching a metal plate, the clearance of the mold has been narrowed, but this cannot always be completely prevented. Further, if the clearance is reduced, the wear of the cutting edge becomes a problem, so there is a limit to the clearance adjustment. Further, the invention in the punching process of the metal plate up to now is disclosed in, for example, Japanese Patent Application No.
No. 181238 aims at suppressing the generation of burrs, and does not give any knowledge about punching cracks.

[0004]

SUMMARY OF THE INVENTION The present invention uses a mold that can be manufactured in substantially the same manner as conventional mold manufacturing without requiring a special device for the occurrence of punching cracks, which is a problem of the above-mentioned prior art. And provide a method for preventing it by adjusting the punching clearance to an appropriate value.

[0005]

SUMMARY OF THE INVENTION The inventors of the present invention punched a metal plate having a plate thickness of 3 to 15 mm using a punch and a die and punched the cutting edge of the punch with a punch diameter of 5 to 20 mm. It was found that punching cracks can be prevented by using a punching die with chamfering of about%. That is, according to the present invention, a clearance is 6 to 15% of the plate thickness and the punch tip is chamfered in the above range, and a punching die having no punching crack for a metal plate, and punching using this die. This is a method for punching a metal plate.

[0006]

The present invention will be described in detail below. Much research has been conducted on shearing of metallic materials.
As shown in Fig. 1, cracks during punching occur from both punch and die cutting edges, and when the two meet due to the growth of cracks, and when cracks from one side tool grow to the opposite side tool cutting edge. It is known to be divided into cases. If the clearance is small enough, the crack propagates along the shear force and punches through. However, if the clearance is large, the propagation is not successful and the crack propagates to the product side, and the crack is likely to occur.

As can be seen from the crack generation mechanism, it is important to properly control the propagation of cracks in order to prevent punching cracks. However, a method of adjusting crack propagation by sufficiently reducing the clearance is However, it is not preferable because the punching force increases and the blade edge wears due to secondary shearing. Therefore, the present inventors, by the chamfered punch tip before the start of shearing, give work hardening to the crack occurrence site, facilitate the occurrence of cracks and the propagation of cracks from the punch shoulder, and the clearance The crack growth was controlled by adjusting to an appropriate range, and a punching method without cracks was found.

A punching method using the punching punch of the present invention will be described with reference to the drawings. FIG. 2 is a schematic explanatory diagram of punching of a metal plate by the punching punch and die used in the embodiment of the present invention. The die of the present invention comprises a punch 1 having a diameter of 20φ and a chamfered portion of 15% at the tip,
This is a general punching die including a stopper 2 and a die 3. The metal plate 4 to be processed includes a steel plate, an aluminum plate,
A general metal plate such as a copper plate, a titanium plate and the like and alloys thereof can be applied, and the metal plate 4 is placed on a die and subjected to punching.

First, in FIG. 2 (a), the metal plate to be processed is held by the stopper 2, and then the punch is lowered to reach FIG. 2 (b). When the punch further descends, Fig. 2 (c)
As described above, the chamfered punch tip, which is slightly larger than the set clearance, pushes the metal plate to be processed, and the portion subjected to the shearing process is subjected to a tensile process in the direction of the arrow in FIG. As shown in FIG. 2D, the chamfered portion at the tip of the punch comes into contact with the metal plate, and immediately thereafter, shearing and cracking occur from the set clearance portion, propagate along the shearing force, and cracks occur from the die shoulder portion. Meeting with Figure 2
As shown in (e), it is possible to punch without cracking.

Next, the limiting conditions of the present invention will be described. First, the thickness of the metal plate to be processed is 3 mm or more is 3 mm
This is because, in the case of punching a metal plate of less than, since the crack propagation distance is short, it is possible to perform punching without cracking by a conventional method without adjusting crack propagation. Further, the thickness of the metal plate to be processed is set to 15 mm or less because when a material thicker than 15 mm is punched, the wear of the cutting edge of the punch increases and the durability of the punch is impaired.

Chamfer the tip of the punch by 5 to 2 of the punch diameter.
The reason for setting 0% is that the chamfering of less than 5% of the punch diameter does not provide an effect of promoting crack initiation because the amount of work hardening applied to the cracked portion of the material is insufficient. The chamfering of the punch tip is set to 20% or less of the punch diameter because the chamfering is larger than 20% of the punch diameter, the deformation due to tension until cracking is large, and the punched product cross-sectional shape shown in FIG. This is because the sagging portion becomes large and the product shape is impaired. The chamfered shape of the punch tip is preferably formed at an angle of 45 °, but it may be slightly deviated due to problems in manufacturing accuracy.

The clearance at the time of punching is set to 6 to 15% of the metal plate to be processed, because the wear of the punch increases if it is less than 6%, and if it exceeds 15%, the propagation of cracks is in the direction of shear force. This is because it does not proceed and cracks easily occur. The punching speed is not specified, but it is 10 depending on the productivity and the capacity of the mechanical press currently used.
It is preferably 0 mm / sec or more. By using the present invention based on the above limiting conditions, it is possible to prevent cracks that occur when punching a metal plate having a relatively large thickness.

[0013]

EXAMPLES Examples of the present invention will be described below. As the metal plate, a general metal plate such as a steel plate, an aluminum plate, a copper plate, a titanium plate and the like and alloys thereof can be applied. Among them, a mild steel plate, a high tensile steel plate and a semi-hard aluminum plate were used. The punching tool shown in FIG. 2 (a) was used, and the punches were 20 mmφ in diameter, and two types of cutting blades were prepared: a normal cutting edge and a 3 mm (15%) chamfered cutting edge. For the die, 21.6mmφ, 22.8m
Three types of mφ and 23.6 mmφ were used. Further, as a comparative example, the results obtained by using those having chamfering of 4% and 25% with a punch diameter of 20 mmφ are also shown. Blank plate is 100
mm, the other punching conditions were the same, and the punching speed was 150 mm / sec. The lubrication condition was that the anti-rust oil was applied. The cracks were evaluated by visual inspection, and those with small cracks and cracks were marked with X, and those without punches were marked with ◯. Further, the shape of sagging after punching was also visually evaluated.

[0014]

[Table 1]

[0015]

INDUSTRIAL APPLICABILITY As described above, the present invention is extremely effective as a punching tool and a method for punching a metal plate that does not cause cracking during punching, and has a high industrial value because it can be performed without requiring a special die. It is a thing.

[Brief description of drawings]

FIG. 1 is an explanatory view of a crack generation mechanism in punching a metal plate,

FIG. 2 is a schematic explanatory view of a punching tool and a punching method according to the present invention,

FIG. 3 is a cross-sectional view of the product after punching.

[Explanation of symbols]

 1 punch 2 stopper 3 die 4 metal plate 5 chamfer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Tezuka 1 Kimitsu, Kimitsu-shi, Chiba Shin Nippon Steel Co., Ltd. Inside the Kimitsu Works (72) Inventor Kazuki Tachiki 2-6-Otemachi, Chiyoda-ku, Tokyo 3 Within Nippon Steel Corporation

Claims (2)

[Claims] 1. A punching tool for a metal plate using a punch and a die, wherein the cutting edge of the punch has a punch diameter of 5 to 2
Punching die of metal plate with 0% chamfer and without punching cracks. 2. In punching a metal plate having a plate thickness of 3 to 15 mm using a punch and a die, the clearance is 6 to 15% of the plate thickness, and punching is performed using the punching die according to claim 1. A method for punching metal without cracking a metal plate, which is characterized in that