JP5719149B2 - Painted steel plate shearing punch and coated steel plate shearing method - Google Patents

Description

  The present invention relates to a shearing punch A for a coated steel sheet, and more particularly to a new improvement for suppressing enamel hair and sag of defective shape by using a stepped blade.

2. Description of the Related Art In recent years, products made of pre-coated steel plates (pre-coated steel plates) have been frequently used as home appliances, automobile parts, and the like from the viewpoint of omitting processes and reducing costs. In particular, a coated stainless steel plate having a stainless steel plate as a base plate and a clear coating on the surface thereof is used for home appliances aimed at high design. Here, the coated steel sheet includes a so-called laminated steel sheet in which a resin film is laminated on the steel sheet.
In the process of processing coated steel sheets into household electrical appliances and automobile parts, shear processing such as punching and cutting with a press machine is often performed. At that time, the end surface called enamel hair is applied to the shear end surface. Membrane peeling is likely to occur.
When so-called enamel hair occurs on the shear end face, the appearance is impaired and the quality of the product is deteriorated, and if it occurs in the process of molding home appliances and automobile parts, it causes dents and the yield decreases. It leads to.
Therefore, when the coated steel plate is sheared, the coating on the shear surface is cut in advance, or the shear clearance is extremely reduced to reduce sagging, thereby preventing the occurrence of enamel wrinkles. When the original plate of the coated steel plate is a surface-treated steel plate, if the sag is large, the elongation of the plating layer between the original plate and the coating film is small, so that the part is broken and enamel hair is likely to occur. Yes.
Specifically, Patent Document 1 proposes that after a thickness is cut in advance in the coating film at the shearing portion, the clearance between the punch and the die is punched at 5% or more and 10% or less of the plate thickness.

Patent Document 2 discloses an enamel hair in which the glass transition temperature Tg of a coated steel sheet coated with a plated steel sheet is set to a temperature lower than the shearing temperature, and the shear clearance is 5% to 15%. Prevention techniques are disclosed.
Further, in the coated steel sheet and the shearing method of Patent Document 3, a corner R is given to the tip of the punching (punch) blade edge, the corner R is 0.05 mm or more, and the thickness of the coated steel sheet (particularly a clear stainless steel sheet). Enamel hair generation is suppressed by setting it as 30% or less.

In patent document 3, the generation | occurrence | production mechanism of enamel hair is demonstrated below.
As shown in FIG. 5, when the coated steel plate 3 placed on the die 1 is subjected to a shearing process using the punch 2 (a), first, the edge of the punch 2 bites into the coating 5 and the coating film is sheared. (B). Thereafter, the cutting edge of the punch 2 bites into the original plate 4 which is the material, the original plate is sheared (c), and separated into a punching residue and a punching die (d). When the cutting residue is separated and shearing ends, the punch is pulled upward and the cutting edge is detached from the material (e), the coating film end face and the cutting edge side face slide with high surface pressure, and the coating film 5 Force acts in the direction of peeling from the original plate 4. And the coating-film edge peeled when the blade edge | tip separated from the material will detach | leave from a main-body part, and will become enamel hair. That is, enamel hair is considered to occur in the process of pulling out the punch.

  When the present inventors further analyzed the generation mechanism of enamel hair at the shear end, the following contents were newly found. FIG. 6 is an explanatory view showing a generation mechanism of enamel hair generated at the shear end. As shown to (a) of FIG. 6, the coated steel plate 4 has the coating film 47 formed in the upper surface of the steel plate 45 which is a base material through the pre-processing film 46. As shown in FIG. Here, the pretreatment film is provided in order to ensure adhesion between the steel sheet as the base material and the coating film. As the type of treatment, various inorganic and organic treatments that do not contain chromate treatment or chromate are used. There is. In the drawing, the pretreatment film 46 is shown thick for easy understanding, whereas the coating film 47 is a film of about several μm, whereas the pretreatment film 46 is a very thin film of about several tens of nm. It is.

  As shown in FIG. 6A, when the punch 3 starts to be pushed into the coated steel plate 4, a compressive stress 50 indicated by an arrow in the drawing is applied to each of the steel plate 45, the pretreatment film 46, and the coating film 47. Works. At this time, since the pretreatment film 46 is made of a harder material than the steel plate 45 and the coating film 47, it cannot follow the slip deformation of the steel plate 45. For this reason, cracks and cohesive failure occur in the pretreatment film 46, and the coating film 47 rises. Hereinafter, the part where the coating film 47 is peeled from the steel plate 45 is referred to as a coating film peeling part 47a. That is, it was found that the peeling of the coating film due to the destruction of the pretreatment layer had already occurred when the punch was pushed.

  As shown in FIG. 6B, the coating film 47 does not follow the deformation of the steel plate 45 from the middle stage to the latter half of the indentation, and the compressive stress 50 acting on the coating film 47 increases. On the other hand, the tensile stress 51 resulting from the pressing of the punch 3 acts on the steel plate 45. For this reason, the cohesive failure surface 46a of the pretreatment film 46 propagates to the inside, and the coating film peeling portion 47a is enlarged. When the punch 3 is further pushed in, the coating film peeling portion 47a is pulled by the punch 3, and the coating film 47 is broken depending on the conditions, so that an enamel hair 48 shown in FIG. 6C is generated. The properties of the pretreatment film vary depending on the type of base steel sheet and the processing method. In general, a stainless steel plate having a chemically inert passive film on the surface as a base material tends to have poor adhesion in a pretreatment that does not contain chromate in the treatment method.

That is, by using the punch provided with the tip R, the enamel hair can be suppressed by applying the tensile stress 51 from the beginning without applying the compressive stress 50 in the sag portion in the shearing process.
The properties of the pretreatment film vary depending on the type of base steel sheet and the processing method. In general, a stainless steel plate with a chemically inert passive film on the surface as a base material is a pretreatment that does not contain chromate in the treatment method, and each tends to have poor adhesion, and enamel hair tends to occur. Become.

Japanese Patent Laid-Open No. 9-3000295 Japanese Patent Laid-Open No. 10-43679 JP 2010-172944 A

Conventionally, the shearing method of this type of coated steel sheet that has been used has been configured as described above, and the following problems existed.
First, in the methods of Patent Documents 1 and 2 described above, a plated steel plate is used as a base plate, and enamel hair cannot be suppressed when a stainless steel plate is used as a base plate.
In addition, in the method of Patent Document 3, when the plate thickness is 0.16 mm or less and the plate thickness is 30% or less, it is less than 0.05 mmR, so that it is not applicable to a coated stainless steel foil steel plate of 0.16 mm or less. It was possible. Moreover, it has been difficult to prevent a large sag due to a shape defect formed at the shear end.

The shearing punch for a coated steel sheet according to the present invention is a shearing punch for a coated steel sheet having a cutting edge part at the lower part of the punch body, wherein the cutting edge part is higher than the first cutting edge having a tip R and the first cutting edge. The first cutting edge has an offset distance along the width direction of the punch body with respect to the second cutting edge, and the second cutting edge is the first cutting edge. A configuration in which a sheared portion of the coated steel plate is cut after the coated steel plate is sheared by a blade edge, and a shape that enters the inside along the width direction of the punch body between the first blade edge and the second blade edge. And a length a from the bottom surface of the punch body to the second cutting edge is greater than the offset distance b, and the first, Painted steel plate with 2nd cutting edge When shearing, the first cutting edge suppresses enamel hair, and the cutting by the second cutting edge suppresses sagging, and the bent recess is configured to have a C-shaped cross section. The lower part of the bent recess is formed by a downward slope, and the method for shearing the coated steel sheet according to the present invention is a method using the shearing punch according to any one of claims 1 to 4. is there.

Since the shearing punch for the coated steel sheet and the shearing method for the coated steel sheet according to the present invention have the effects as described above, they have the following effects.
That is, in a shearing punch of a coated steel sheet having a cutting edge portion at the lower portion of the punch body, the cutting edge portion is formed with a first cutting edge having a tip R and a second cutting edge that is spaced apart upward from the first cutting edge. The first cutting edge has an offset distance along the width direction of the punch body relative to the second cutting edge, thereby suppressing the generation of enamel hair at the first cutting edge, and the second cutting edge. Sagging can be suppressed by cutting, and it is possible to shear a coated steel plate without sagging that causes enamel hair and shape defects.
Moreover, since the said bending recessed part is formed in the cross-sectional C shape, the sagging cut by the 2nd blade edge is accommodated in this bending recessed part, and is discharged | emitted below by a downward slope.
In addition, even when mild enamel hair (discontinuous film peeling) occurs with the first blade, the peeled coating film is discharged downward by the cutting with the second blade, thereby preventing the generation of enamel hair. Suppress.

It is sectional drawing which shows the punch for shearing of the coated steel plate by this invention. It is an expanded sectional view which shows the principal part A of FIG. It is sectional drawing of the conventional shearing part. It is a conventional shear plane. It is a conventional shear plane. It is sectional drawing of the shearing part of this invention. It is process drawing which shows the conventional shearing method. It is process drawing which shows the generation | occurrence | production mechanism of enamel hair.

  An object of this invention is to provide the punch A for the shearing of the coated steel plate which suppressed enamel hair and sagging of a shape defect by using a cutting blade.

A preferred embodiment of a punch A for shearing a coated steel sheet according to the present invention will be described below with reference to the drawings.
Note that the same or equivalent parts as in the conventional example will be described using the same reference numerals.
In the cross-sectional view of FIG. 1, a reference numeral 2 denotes a punch provided in a press machine (not shown), and the cutting edge portion 10 having a lower surface 10 c that is a tip of the punch body 2 a of the punch 2 is enlarged in FIG. 2. As shown in the cross-sectional view, the first cutting edge 10a and the second cutting edge 10b are formed.

  As shown in the enlarged cross-sectional view of FIG. 2, the first cutting edge 10 a has an R at the corner C of the tip, and by having this R, the well-known coated steel sheet in the aforementioned Patent Document 3 As disclosed in the shearing method, the enamel hair can be suppressed.

  A second cutting edge 10b is formed spaced apart by a length a upward B from the first cutting edge 10a, and the first cutting edge 10a is more predetermined along the width direction W of the punch body 2a than the second cutting edge 10b. A bent recess 12 is formed so as to enter the inner side along the width direction W of the punch main body 2a by an offset distance b, and to enter the inner side between the blade edges 10a, 10b.

  The bent concave portion 12 has a C-shaped cross section, and the lower portion of the bent concave portion 12 is formed by a downward slope 13 and is cut by the second cutting edge 10b (shown in FIG. 4). Is accommodated in the bent recess 12 and can be discharged downward through a downward slope 13 at the lower portion of the bent recess 12.

  The length a from the lower surface 10c of the punch main body 2a to the upper edge B to the second cutting edge is larger than the offset distance b, the enamel hair is suppressed by the first cutting edge 10a, and the cutting by the second cutting edge 10b is performed. It is configured to suppress sagging.

Next, an experimental example in which the coated steel plate 3 is sheared using the punch 2 of the present invention having the above-described configuration will be described.
The present inventors prepared SUS430 (BA finish) having a plate thickness of 0.16 mm as the stainless steel plate 4, and the stainless steel plate 4 was washed with water by alkali degreasing in advance. On the surface (one side) of the stainless steel plate 4, a chromate type coating pretreatment liquid (NRC300: Nippon Parkerizing Co., Ltd.) is applied with a bar coater, and the pretreatment film is deposited at 100 ° C. so that the adhesion amount becomes 10 mg / m ^2. And dried. Further, a solvent-based acrylic paint was applied on the upper surface and baked at 230 ° C. to form a coating film 5 having a thickness of 5 μm. The tip R of the first cutting edge 10a of the punch was set to 0.1 mm, and the tip R of the second cutting edge 10b was set to 0 mm.

  The present inventors made the following enamel hair generation evaluation experiment after producing such a coated steel plate 3. That is, a test piece was cut out from the coated steel plate 4 as described above and subjected to shearing. Cellophane tape was affixed to the sheared edge and immediately forcedly peeled off, and then the state of enamel hair (coating peeling) was observed with a scanning electron microscope (SEM) (500 times). The shearing is performed using a shearing die in a 15-ton press, and the processing conditions are a processing speed of 100 spm, a punch diameter φ of 20 mm, and a die diameter of 5% clearance with respect to the plate thickness. Adjusted.

FIG. 3 shows a shearing method of the coated steel plate 3 shown in FIG. 5 using a normal punch as a comparative example, where a sag 4c is formed and enamel hair is generated. Moreover, since FIG. 3A is only the punch 2 which has R, generation | occurrence | production of enamel hair is suppressed, However, since the sagging became large and the shear shape of the sagging part was unsatisfactory, it did not become a product. In the case of FIG. 3B, enamel hair was generated. Since the tip R of the first cutting edge 10a is 0R, the coating float is generated like a normal punch, and even if it is cut by the second cutting edge 10b, the coating floating part propagates to the inner side. Will occur.
Moreover, according to the shearing method of the coated steel plate 3 using the stepped punch 2 having the first and second cutting edges 10a and 10b according to the present invention of FIG. 4, the shearing of the coated steel sheet 3 by the first cutting edge 10a having R is performed. The sagging 4c was removed cleanly by cutting with the second cutting edge 10b after shearing with the first cutting edge 10a as well as suppressing the enamel hair at the time, and a vivid shear surface 4b could be obtained.

  The punch A for shearing a coated steel sheet according to the present invention can be applied not only to a coated steel sheet but also to a laminated thin steel sheet. Moreover, the coating original plate can be applied to a plated steel plate in addition to the stainless steel plate.

2 Punch 2a Punch body a Length b Offset distance W Width direction B Upper 3 Painted steel plate 4 Stainless steel plate (original plate)
4a Fracture surface 4b Shear surface 4c Sag 5 Coating film 10a First blade edge 10b Second blade edge 10c Lower surface 12 Curved recess 13 Down slope

Claims (5)

In a shearing punch for a coated steel sheet having a cutting edge portion (10) at the lower portion of the punch body (2a), the cutting edge portion (10) includes a first cutting edge (10a) having a tip R and the first cutting edge (10a). The first cutting edge (10a) is formed in a width direction (W) of the punch body (2a) more than the second cutting edge (10b). And the second cutting edge (10b) cuts the sheared portion of the coated steel sheet after the coated steel sheet is sheared by the first cutting edge (10a). Punches for shearing painted steel sheets.   Between the first blade edge (10a) and the second blade edge (10b), there is formed a bent recess (12) having a shape that goes inward along the width direction (W) of the punch body (2a). The shearing punch for a coated steel sheet according to claim 1.   The length (a) from the lower surface (10c) of the punch body (2a) to the second cutting edge (10b) is greater than the offset distance (b). Punch for shearing painted steel sheets.   When the coated steel plate (3) is sheared by the first and second cutting edges (10a, 10b), enamel hair is suppressed by the first cutting edge (10a), and sagging (4c) is achieved by cutting by the second cutting edge (10b). The shearing punch for a coated steel sheet according to any one of claims 1 to 3, wherein the punch is for preventing the coating. A method for shearing a coated steel sheet using the shearing punch according to any one of claims 1 to 4.

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