JPH0966318A - Burring of covered metal plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a substance covered on metal surface from peeling in burring by making a length of tapered tip part of a burring punch lower than burring height and executing burring without protruding the tip of burring punch beyond a prepared hole for burring. SOLUTION: After a prepared hole for burring is pierced to a metal plate 1 covered with a protective film 2 by a punch 3, by pushing a burring punch 7 toward the side of burring die 8 with a burring punch 7 having a tapered part shorter than burring height at the tip so as to obtain a prescribed burring height, burred part is obtained. At this time, because the height of tip tapered part of burring punch 7 is shorter than burring height, the tip of burring punch is not protruded beyond the prepared hole for burring. Accordingly, when the protective film is stretched from punch tapered part, the burring punch 7 and metal plate end part 6 are not brought into contact with each other, as a result, peeling of protective film is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective film, a plating film, and the like when burring a metal plate having a surface coated with another substance such as a metal plate having a protective film, a plated steel plate, a coated steel plate, etc. The present invention relates to a burring processing method capable of obtaining a product without peeling of a surface coating such as a coating.

[0002]

2. Description of the Related Art A conventional burring method is shown in FIG.
a, FIG. 2b, and FIG. 2c. That is, as shown in FIG. 2a, a burring pilot hole is made in a metal plate 1 coated with another substance 2 by a punch 3, and then a burring hole is formed.
Burring is performed by the burring punch 4 shown in Fig. 2 to obtain the burring portion shown in Fig. 2c.

[0003]

However, according to the conventional processing method, since the burring punch tip is projected from the burring pilot hole in the burring process, the burring punch 4 causes the metal plate end 6 of the burring pilot hole to be processed.
The coating substance 5 existing on the surface of the metal is rubbed against the tapered surface of the burring punch and stretched, cut by the metal plate end portion 6 and the burring punch 4, peeled into a thread or ring and adhered to the product, and the peeled residue is removed. It takes a lot of work to do. In addition, when continuous production is carried out, if the separation slag accumulates on the mold and continues processing, it may cause dents that scratch the surface of the product, resulting in a decrease in commercial value. Therefore,
The debris had to be removed frequently so that it did not deposit on the mold.

[0004]

Therefore, the present invention has been made in view of the above problems, and prevents peeling of a substance coated on the surface of a metal plate during burring, which requires a great deal of labor until now. The productivity can be improved without the need to remove the coating material debris. That is, in the burring process of a metal plate whose surface is coated with another substance,
When performing burring after the pilot hole is opened in advance, the taper length at the tip of the burring punch is made shorter than the burring height, and the burring processing is performed by making the burring punch tip not protrude from the burring pilot hole. It is an object of the present invention to provide a burring method that does not generate slag.

[0005]

According to the present invention, the coating material existing on the surface of the metal plate end portion of the burring pilot hole is formed by burring without the tip of the burring punch protruding from the burring pilot hole. Since the burring process can be performed without being peeled by being cut by the burring punch and the metal plate end portion, it is possible to improve the productivity without requiring the conventional removal work of the debris.

The present invention will be described below with reference to FIG. FIG.
Punch 3 on metal plate 1 with protective film 2 shown in a.
After the pilot hole for burring is opened with, the burring punch 7 is pushed to the burring die 8 side so that the burring punch 7 has a predetermined burring height having a tapered portion shorter than the burring height shown in FIG. obtain. At this time, since the height of the tapered portion at the tip of the burring punch 7 is shorter than the burring height,
The tip of the burring punch does not protrude from the burring pilot hole. Therefore, even if the protective film existing between the burring punch 7 and the metal plate end portion 6 of the burring pilot hole is stretched by the punch taper portion, the burring punch 7
The metal plate end portion 6 of the burring pilot hole does not contact with each other, and as a result, peeling of the protective film can be prevented. Further, even if the height of the tapered portion at the tip of the burring punch 7 is longer than the burring height, the burring punch 7 protrudes from the burring pilot hole during processing and even contacts the film end 5 by adjusting the stroke. Needless to say, if there is no film residue, it will not occur. The burring punch 7 of FIG. 1 is tapered and chamfered so that the tip is flat. However, if the shoulder radius of the chamfered portion at the tip is small, the film may be scratched during burring or the protective film may When the protective film is cut after being cut into a ring shape and processed, there arises a problem that a thread-shaped or ring-shaped film remains in the product. It takes a great deal of effort to remove this thread-like or ring-shaped film residue, so it is necessary to make the shoulder radius large enough when chamfering in a taper shape so as not to scratch or cut the protective film. is necessary. Needless to say, the size of the shoulder radius at this time varies depending on the type and thickness of the protective film.

[0007]

[Example] As the metal plate 1, a SUS43 plate having a plate thickness of 0.8 mm
0 is a protective film 2 made of vinyl chloride having a thickness of 0.12 mm, and the mold has a structure shown in FIG. The diameter of the burring punch 3 for punching was 5.8 mm. Burring die 8 has a diameter of 9.0
mm. Burring punch 7 has a diameter of 8.25 m
m, tip angle 80 degrees, tip taper length 4.0 mm
The tape of which the tip and the shoulder radius were changed was used.

The burring height is set to 1.3 mm,
Burring punch 7 has a tip taper length of 1.3 mm
When the length was made longer, the die was adjusted so that the burring punch tip protruded from the burring pilot hole during burring and the burring punch 7 and the metal plate end 6 of the burring pilot hole contacted each other. The length of the tapered portion of the burring punch 7 is 1.0 mm, 1.1 mm, 1.2 mm, 1.3.
mm, 1.4 mm, 1.5 mm chamfered length and 4.0 mm length of as-purchased 7 kinds of burring punches 7 are set in the mold and continuous burring test is performed at the same time. did. However, the shoulder radius of the chamfered portion of the tip of the burring punch 7 was gradually expanded so as not to scratch the protective film, and the experiment was conducted. as a result,
At the burring portion processed by the burring punch 7 having a taper length of the tip of the burring punch longer than 1.3 mm and a shoulder radius of 2 mm or less, thread-like debris of the protective film is generated and the length of 1.3 mm or less is generated. It was found that a peeling residue of the protective film did not occur in the burring portion processed by the burring punch 7 having the tapered portion.

[0009]

As described above, according to the burring method of the present invention, a burring process is performed on a metal plate having a surface coated with another substance such as a metal plate having a protective film, a plated steel plate, and a coated steel plate. Surface protection film,
This is a highly productive processing method that can perform burring processing without peeling off the plating film, coating film, etc., and does not require the removal work of the debris that has been frequently done conventionally. Has great value.

[Brief description of drawings]

FIG. 1 is a diagram showing a burring method of the present invention.

FIG. 2 is a diagram showing a conventional burring method.

[Explanation of symbols]

 1: Metal plate 2: Protective film 3: Punch for burring pilot hole processing 4: Conventional burring punch 5: Film end part of burring pilot hole 6: Metal plate end part of burring pilot hole 7: Burring punch 8: Burring Dice 9: Stripper plate

Claims (1)

[Claims] 1. In the burring process of a metal plate having a surface coated with another substance, when the burring process is performed after pre-drilling a hole, the length of the taper portion at the tip of the burring punch is made shorter than the burring height. A burring method for a coated metal plate that eliminates the generation of coating material slag by performing burring without protruding the tip from the burring pilot hole.