JPH09300295A - Punching work method for coated metal plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent enamel hair from generating at punching of a coated metal plate using a punch and a die by previously cutting in the coating of punching part by the tickness of coating, and then punching it while setting the clearance of the punch and the die to be a specific rate of the plate thickness. SOLUTION: A coated metal plate to be worked of which the original plate is a metal plate 1 having plating layers 4, is formed with a surface film 2 and a back film 2' by some organic or inorganic film layers through chemical conversion treatment layers 3, the metal plate to be worked is held with a plate presser B, and then a punch A is brought down and the metal plate is punched by the punch A and the die C. Hereat, the surface film 2 and the back film 2' are previously cut off, and the clearance between the punch A and the die C is set to be 5-10%. of the plate thickness so as to punch it. When the clearance is smaller than 5%, abrasion of the punch is increased, and when the clearance is larger than 10%, sagging of the metal plate is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing method such as punching or punching a coated metal plate.

[0002]

2. Description of the Related Art Conventionally, home electric appliance manufacturers and automobile parts manufacturers use cold-rolled steel sheets or surface-treated steel sheets to form parts,
It was painted in a later process. However, with the aim of reducing the cost by reducing the process by omitting the process, the solvent used for painting has a negative impact on the human body and the natural environment, and the omission of painting by users has been advanced. As a result, the coated metal plate pre-painted by the material manufacturer will be pressed by the user. It can be said that the punching process by a press machine is always included in the processing of coated metal sheets for home electric appliances and automobile parts. At that time, the enamel hair (peeling of the coating film on the end face) generated on the punched end face becomes a problem. This enamel hair not only impairs the aesthetic appearance of the product, but also causes the peeling of the coating film and cannot be used as a product.

As a measure for preventing this enamel hair, for example, as disclosed in Japanese Patent Publication No. 60-5351, the thickness of the coating film on the expected shear line is reduced in advance to suppress the generation of enamel hair during cutting. . However, with this method, it is necessary to paint while considering the shear position of the product, which is a significant cost increase for the material manufacturer to handle. Also, as a measure to prevent enamel hair in the punching method, it is performed to reduce the clearance between the punch and the die in order to prevent sagging at the time of punching the processed plate, which is one of the factors causing enamel hair. . However, preventing the sagging cannot prevent the enamel hair, and if the clearance is reduced, the blade edge is likely to wear, which is an insufficient preventive measure.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a method for preventing the enamel hair that occurs when punching a coated metal sheet, which is a problem of the above-mentioned prior art.

[0005]

[Means for Solving the Problems] In punching a coated metal plate using a punch and a die, after making a cut for the film thickness in advance in the coating of the punched portion, the clearance between the punch and the die is 5% of the plate thickness. As described above, the punching method of the coated metal plate is characterized by punching at 10% or less.

Hereinafter, the present invention will be described in detail. The generation process of enamel hair will be described with reference to the drawings. FIG. 1 is a schematic explanatory view of a punching process of a coated metal plate by a general punch A, a die C, and a plate holder B. The metal plate to be processed is a metal plate 1 having a plating layer 4 used as an original plate, and a surface coating film 2 and a back surface coating film 2 ′ formed by an organic or inorganic coating layer via a chemical conversion treatment layer 3. . First, in FIG. 1A, the metal plate to be processed is held by the plate retainer B, and then the punch A is lowered to reach FIG. 1B. In the state of FIG. 1 (b),
The metal plate 1, the front and back coating films 2 and 2 ', the chemical conversion treatment layer 3, and the plating layer 4 all receive a tensile force in the direction of the arrow in the drawing on the planned shear line. Especially at that time, the front and back coating films 2 and 2'are punch A
Further, the sheet is stretched by the tensile force received from the die C, and when the clearance is large, the sheet is sandwiched between the metal plate 1, the punch A and the die C and crushed.

On the other hand, since the plating layer 4 has a remarkably small deformability, it cannot withstand the tensile force and the deformation (sagging) of the metal plate 1 and breaks near the shear line. Further, the deformation of the front and back coating films 2 and 2'is close to the elastic deformation that returns to the original state when it is sheared, and is different from the metal plate 1 and the plating layer 4. Due to the difference in the deformation state of the metal plate 1, the front and back coating films 2 and 2 ', and the plating layer 4, enamel hair peeling off the coating film at the sheared surface as shown in FIG. 2 is generated. Therefore, in order to eliminate the enamel hair, (1) cut the coating film on the planned shear line in advance to suppress the deformation of the coating film due to the tensile force at the time of shearing, and (2) suppress the sagging of the steel sheet. Punch A
It was concluded that it is necessary to minimize the clearance of the die C as much as possible.

Next, the limiting conditions of the present invention will be described. First, a method of cutting the coating film in advance is not particularly limited, and for example, a method of pressing the cutting blade having the same diameter as the punching punch diameter to cut the coating film may be used. Also,
Clearance between punch and die is 5% or more of plate thickness, 10%
The reason for setting below is that the wear of the punch is increased if it is less than 5%, and the sagging of the metal plate is increased if it is more than 10%. The punching speed is not particularly specified, but is preferably 50 mm / sec or more in view of productivity and the capacity of the mechanical press currently used. The type of coating of the metal plate to which the present invention can be applied is either organic or inorganic.

The resin used for the organic coating layer is thermoplastic,
It may be thermosetting, and specifically, polyester resin, fluorine resin, epoxy resin, acrylic resin, urethane resin, silicon resin, olefin resin, butyral resin, vinyl chloride resin, etc. , Engineering plastics such as polyether sulfone resin, polyphenylene sulfide resin, etc.,
These may be used alone or in combination. Further, an inorganic polymer such as siloxane or borosiloxane may be used, and an organic / inorganic mixture or a composite may be used.

Pigments may be added to the coating layer, specifically, commonly used pigments such as color pigments, rust preventive Pigs, constitution Pigs, and metal powders may be used. Further, additives may be added, and specifically, leveling agents, defoaming agents, color separation preventing agents and the like. The method for forming the coating may be painting, or a previously formed coating such as a film may be attached.

An organic wax is used as the wax. Synthetic wax such as olefin and acrylic
It is desirable that a natural wax such as carnauba-based wax or a mixture thereof is contained in the coating film in an amount of 0.01% or more and 10% or less. The wax content is set to 0.01% or more in order to ensure lubricity and scratch resistance. In addition, the reason why the wax content is 10% or less is that
This is because if it is more than 10%, appearance defects such as uneven gloss are caused.

Here, the metal plate to be coated is not only a cold rolled steel plate or a steel plate such as a tin plate plated but also an aluminum alloy plate, a Ti alloy plate, a copper alloy plate, or the like. Also includes. The plating type is not particularly limited, and Zn, Fe, Sn, Pb, Ni, A
Single phase plating such as 1 and composite plating of these may be used.
The method for forming these platings is not particularly limited, and any of electroplating, hot dipping, chemical plating, vapor phase plating, and the like may be used.
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]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. As a coated metal plate, the plate thickness is 0.6 mm and the tensile strength is 29.
An electrogalvanized steel sheet having 5 MPa and a total elongation of 46% was used. The plating component contained 12% Ni in addition to zinc, and the plating used was 30 g / m ^{2 on} both sides.
Regarding the method of coating the electrogalvanized steel sheet, it was manufactured by painting. As for the coating method, after coating chromate treatment was performed on a galvanized steel sheet, the coating material was coated with a roll coater to a film thickness of 10 μm and baked in an oven. The baking conditions were in accordance with the standard specifications of the paint. The punching tool used was 20 mmφ for the punch. For the die, 20.05 mmφ, 20.
Two types of 08 mmφ were used. Blank plate is 100 mm
The punching speed was 100 mm / sec.
As a method of cutting the film in advance, a circular cutting blade with a diameter equal to the punch punch diameter is used at the punching position of the blank plate for 1 k.
It was pressed with gf. In addition, whether the coating film was cut was confirmed by a cross-sectional microscope. Further, as a comparison, a punching test was also performed when the coating was not cut. To evaluate the occurrence of enamel hair, visually check the end face after punching,
◯: No enamel hair was generated, ×: Enamel hair was generated.

[0014]

[Table 1]

[0015]

INDUSTRIAL APPLICABILITY As described above, the present invention is extremely effective as a punching method for a coated metal plate that does not generate enamel hair, and is of high industrial value because it can be performed without requiring a special mold.

[Brief description of drawings]

FIG. 1 is an explanatory view of an enamel hair generation mechanism in punching a coated metal plate.

FIG. 2 is a schematic explanatory diagram of enamel hair.

[Explanation of symbols]

 1 Metal plate 2 Surface coating 2'Back coating 3 Chemical conversion treatment layer 4 Plating layer A Punch B Plate holder C Die

Claims (1)

[Claims] 1. In punching a coated metal sheet using a punch and a die, after making a notch for the film thickness in the coating of the punching portion, the clearance between the punch and the die is 5% or more and 10% of the sheet thickness. A method of punching a coated metal plate, which comprises punching as follows.