JPH0899131A - Method for blanking metallic plate and blanking die - Google Patents

Abstract

PURPOSE: To prevent occurrence of blanking cracking by using a die which can be manufactured by almost the same way as the conventional method without requiring a specific device and adjusting a blanking clearance to the suitable value, in the blanking of a metallic plate. CONSTITUTION: Work hardening is applied by the tension to a shearing crack part in the tip part at the initial stage of blanking, to promote the occurrence of the cracking and the adjustment of the cracking by providing a projecting part having such smaller shape than a punch diameter that the height from a cutting edge is 5-20% of the punch diameter at the tip part of the punch 1, and setting the clearance to 6-10% of the plate thickness.

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. Also, in strength parts of other automobiles, cracks and minute cracks have an adverse effect such that the paint does not ride well during coating and the touch 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 inventions in the punching of metal plates up to now are aimed at suppressing the occurrence of burrs as disclosed in Japanese Patent Application No. 3-181238, for example. Did not give.

[0005]

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.

[0006]

Means for Solving the Problems In the punching of a metal plate having a plate thickness of 3 to 15 mm using a punch and a die, the inventors have found that the height from the cutting edge is the punch diameter at the punch tip. It was found that by using a punching die having a convex portion having a shape smaller than the punch diameter, it is possible to prevent punching cracking. 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.

The present invention will be described in detail below.

[0008]

[Operation] Many studies have been made so far on shearing of metallic materials. As shown in Fig. 1, cracks during punching occur from both cutting edges of the punch 1 and the die 3, and when the two meet due to the growth of cracks, and when the cracks generated from one side of the tool reach the opposite side of the tool cutting edge. It is known to split when growing. If the clearance is small enough, the crack propagates along the shear force and punches through. However, when the clearance is large, the propagation is not successful, and the crack propagates to the product side, and the crack easily occurs. In the figure, 4 indicates a metal plate.

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 give work hardening to the crack generation site by the convex portion of the punch tip before the start of shearing, facilitate the generation of cracks and the propagation of cracks from the punch shoulder, and have an appropriate clearance. The crack growth was controlled by adjusting the range to a certain 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 mold of the present invention has a diameter of 14φ, a diameter of 14φ, and a height of 3 m from the cutting blade.
This is a general punching die provided with a punch 1 having m convex portions, a stopper 2 and a die 3. Worked metal plate 4
A general metal plate such as a steel plate, an aluminum plate, a copper plate, a titanium plate, or an alloy thereof can be applied to the metal plate 4. The metal plate 4 is placed on a die and subjected to punching. First, in FIG. 2A, the metal plate 4 to be processed is held by the stopper 2, and then the punch is lowered to reach FIG. 2B. When the punch further descends, as shown in FIG. 2 (c), the tip of the chamfered punch 1 slightly larger than the set clearance pushes the metal plate 4 to be processed, and the portion to be sheared is in FIG. 2 (c). Undergoes tensile work in the direction of the arrow to work harden. As shown in FIG. 2D, the chamfered portion at the tip of the punch 1 comes into contact with the metal plate 4, and immediately after that, shearing and cracking occur from the set clearance portion, propagate along the shearing force, and propagate from the die shoulder portion. Figure 2
As in (e), punching is possible without tearing.

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.

The height of the convex portion of the punch tip is 5 to 5 mm from the cutting edge.
The range of 20% is set because at a height of less than 5% of the punch diameter, the amount of processing hardness given to the cracked portion of the material is insufficient and the effect of promoting cracking cannot be obtained. The height of the convex portion of the punch tip portion is set to 20% or less of the punch diameter, because when the height of the convex portion is larger than 20% of the punch diameter, the deformation due to tension until cracking is large, and after punching shown in FIG. This is because the sagging portion becomes large and the product shape is impaired in the product sectional shape of.

The clearance at the time of punching is set to 6 to 15% of the metal plate to be worked, because if it is less than 6%, the wear of the punch increases, 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 particularly specified, but is preferably 100 mm / sec or more in view of productivity and the capacity of the mechanical press currently used.

By using the present invention based on the above-mentioned limiting conditions, it is possible to prevent cracks occurring when punching a metal plate having a relatively large thickness.

[0016]

EXAMPLES Examples of the present invention will be described below.

As the metal plate, general metal plates such as steel plate, aluminum plate, copper plate, titanium plate and alloys thereof can be applied. Among them, mild steel plate, high tensile steel plate and semi-hard aluminum plate were used. The punching tool shown in FIG. 2 (a) is used, and the punch is 20
Two types of cutting blades, a normal cutting blade having a diameter of mmφ and a cutting blade having a height of 3 mm (15%) at the tip convex portion (FIG. 2- (a)) were prepared. For the die, 21.6mmφ, 22.8
Three types of mmφ and 23.6 mmφ were used. Further, as a comparative example, the results using the ones having the protrusion heights of 4% and 25% at the punch diameter of 20 mmφ are also shown. 1 blank plate
The punching speed was 150 mm / sec, 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 rated as x, and those without punches that were punched were rated as o. Further, the shape of sagging after punching was also visually evaluated.

[0018]

[Table 1]

[0019]

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

[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 diagram of a punching tool and a punching method according to the present invention.

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

[Explanation of symbols]

 1 ... Punch 2 ... Stopper 2 ... Die 4 ... Metal plate 5 ... Height of convex part

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[Procedure amendment]

[Submission date] October 24, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

[0018]

[Table 1]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] Explanation of code

[Correction method] Change

[Correction content]

[Explanation of Codes] 1 ... Punch 2 ... Stopper 3 ... Die 4 ... Metal plate 5 ... Height of convex portion

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Makoto Tei, 1 Kimitsu, Kimitsu City Nippon Steel Corporation Kimitsu Steel Works

Claims (2)

[Claims] 1. A punching tool for a metal plate using a punch and a die, wherein a punching crack having a convex portion having a height from a cutting blade of 5 to 20% of the punch diameter and smaller than the punch diameter is provided at a punch tip. Punching die of metal plate without. 2. The punching process for a metal plate having a plate thickness of 3 to 15 mm using a punch and a die, wherein the clearance is 6 to 15% of the plate thickness, and the punching die for a metal plate according to claim 1 is used. , A metal plate punching method characterized by punching.