JP6654877B2 - Manufacturing method of fastening parts - Google Patents

Description

The present invention relates to a method for producing a fastening component having a coating layer on the outer periphery.

  The conventional fastening part is formed by molding a blank made of metal cut to a predetermined length into a predetermined shape as shown in Patent Document 3, and a head having a diameter larger than the diameter of the blank, A shaft portion smaller in diameter than the head is integrally provided. Further, the conventional fastening component includes a coating layer containing a tin component disclosed in Patent Documents 1 and 2 on the outer periphery of the head and the shaft. As a result, the conventional fastening parts are widely used as bolts or screws or rivets excellent in heat dissipation and corrosion resistance.

  Also, so-called electroplating is widely used as a method of forming the coating layer. That is, as shown in FIG. 3, the conventional method for manufacturing a fastening part includes a molding step 120 for molding the head and the shaft, and a molded article formed by the molding step 120 is degreased, pickled, and washed. Cleaning step 130, an electroplating step 140 for forming the coating layer on the outer periphery of the molded article after the cleaning step 130, and a baking step 150 described later.

  As described in Patent Document 4, the baking step 150 is performed because hydrogen generated during the cleaning step 130 (particularly at the time of pickling) or the electroplating step 140 enters the inside of the molded article. This is a step of removing this hydrogen from the molded article. Specifically, the baking step 150 is a step of heating the coated molded article on which the coating layer has been formed by the electroplating step 140 or the like to about 200 ° C. and maintaining the heating temperature for several hours. Therefore, the conventional method for manufacturing a fastening component has a feature that occurrence of delayed fracture due to so-called hydrogen embrittlement of the fastening component can be reduced.

JP 11-257323 A Japanese Patent No. 4454640 Patent No. 2909892 JP 2009-062616 A

However, in the conventional method for manufacturing a fastener, the fastener is heated to a temperature close to the melting point of tin in the baking step 150, so that the tin component of the coating layer is dissolved. As a result, the surface of the coating layer changes from a smooth state to an uneven state, and there is a problem that the product value of the fastening part is lost. In addition, since the surface of the fastening component changes to an uneven state, there is also a problem that it is difficult to finish the thickness of the coating layer uniformly. Furthermore, since the coating layer has such a non-uniform thickness, there is also a problem that rust or the like is easily generated from a portion of the thin coating layer and the corrosion resistance is reduced.

The method for manufacturing a fastening component according to the present invention includes a forming step of forming a blank material made of metal into a predetermined shape, and electroplating the formed article formed by the forming step to include zinc or components of zinc and nickel. A first plating step of forming a first coating layer on the outer periphery of the molded article; heating the coated molded article having the first coating layer formed in the first plating step in a range of 190 ° C. to 210 ° C .; A baking step of maintaining the time for at least 2 hours or more, and a step of plating the coated molded article heated by the baking step to form a second coating layer containing tin or a component of tin and zinc on the outer periphery of the coated molded article. And two plating steps . Incidentally, after the second plating step, Rukoto to add chromate treatment step of treating by immersing the fastening part into a solution composed mainly of chromium is preferable.

The method for manufacturing a fastening part according to the present invention has an advantage that it is possible to reduce the delayed fracture of the fastening part due to hydrogen embrittlement because hydrogen that has entered the inside of the coated molded article can be removed. Further, the manufacturing method according to the fastening component has an advantage that the second coating layer is formed on the outermost surface of the fastening component, so that the heat dissipation and the corrosion resistance are excellent and the delayed fracture due to hydrogen embrittlement can be reduced. . Furthermore, in the method for manufacturing a fastening part according to the present invention, in the step after forming the second coating layer containing the tin component, there is no step of heating in the range of 190 ° C. to 210 ° C., which is close to the melting point of tin. There is also an advantage that the outermost surface of the part can be formed smoothly. In addition, the method of manufacturing a fastening component according to the present invention has an advantage that the second coating layer and the first coating layer can be more firmly protected because the outermost surface of the fastening component is covered with the coating by the chromate treatment.

It is a perspective view of the fastening component concerning this invention. Further, (a) is a rivet, (b) is a screw, (c) is a hexagonal bolt, and (d) is an enlarged sectional view of a part of (a) to (c) with a partial cutout. It is a manufacturing process figure showing the manufacturing method of the fastening component concerning the present invention. It is a manufacturing process figure showing the manufacturing method of the conventional fastening component.

A fastening component and a method for manufacturing the same according to the present invention will be described with reference to FIGS. First, the fastening component 1 according to the present invention is formed by molding a blank (not shown) in which a metal wire is cut into a predetermined length into a predetermined shape, and has a diameter larger than the diameter of the blank. A head portion 2 having a diameter and a shaft portion 3 having a diameter smaller than that of the head portion 2 are integrally provided, and a coating layer 10 laminated on the surfaces of the head portion 2 and the shaft portion 3 is provided. Further, the fastening component 1 according to the present invention is a so-called rivet, screw, or bolt, and the shape of the head 2 and the shaft 3 as shown in FIGS. Is molded.

Specifically, when the fastening component 1 according to the present invention is used as a rivet shown in FIG. 1A, a hollow hole 5 extending in the axial direction is formed in the shaft portion 3. 1B, a male screw is formed in the shaft portion 3 and a cross-shaped drive hole 6 is formed in the head portion 2. Furthermore, if it is used as a bolt shown in FIG. 1 (c), a male screw is formed on the shaft portion 3, and the head portion 2 is formed on the outer periphery of a polygonal shape.

  The coating layer 10 is composed of at least two layers having different components. The first coating layer 11 is formed on the surface of a base 4 of a molded product in which the head 2 and the shaft 3 are formed. And a second coating layer 12 formed outside the first coating layer 11. As shown in FIG. 1 (d), the coating layer 10 has a third coating layer 13 thinner than the first coating layer 11 or the second coating layer 12 outside the second coating layer 12. May be formed.

  The first coating layer 11 includes zinc or a component of zinc and nickel, and is formed by performing electroplating on the molded product. The first coating layer 11 has a thickness of 1 μm to 10 μm, and preferably has a thickness of 2 μm to 3 μm.

  The second coating layer 12 includes tin or a component of tin and zinc, and is formed by performing the electroplating or the hot-dip plating. The second coating layer 12 has a thickness of 5 μm to 20 μm, and preferably has a thickness of 10 μm to 15 μm. Further, since the tin contained in the component of the second coating layer 12 has a high heat dissipation property, a fastening component (not shown) whose outermost surface is the second coating layer 12 has a heat dissipation function. Therefore, there is an advantage that it can be used for a work that easily becomes high in temperature.

  The third coating layer 13 is formed of a thin chromate film by a chromate treatment, and has a thickness of about 0.1 μm.

Accordingly , the fastening component 1 according to the present invention has an advantage that the outer periphery of the molded product is protected by the first coating layer 11 and the second coating layer 12, and thus has excellent corrosion resistance. Further, when the outermost surface of the fastening component 1 of the present invention is the second coating layer 12 containing a tin component having excellent heat dissipation properties, the fastening component 1 functions as a heat dissipation component if fastened to a workpiece that easily becomes hot. There are advantages too. Furthermore, when the outermost surface of the fastening component 1 according to the present invention is the third coating layer 13, the fastening protected by the above-described two coating layers (the first coating layer 11 and the second coating layer 12). Has higher corrosion resistance than parts.

Next, as shown in FIG. 2, the method for manufacturing the fastening component 1 according to the present invention includes forming the blank material into a die by means of a die (not shown) or forming the blank material into a cutting tool (see FIG. 2). (Not shown) or the like to form the molded article, a cleaning step 30 for degreasing and washing the molded article, and electroplating the molded article washed in the washing step 30 to form the first molded article. A first plating step 40 for forming the coating layer 11, a baking step 50 for heating the coated molded article coated in the first plating step 40 for a predetermined time, and an electric heating of the coated molded article heated in the baking step 50. A second plating step 60 in which the second coating layer 12 is formed by plating or hot-dip plating; and the third coating layer 1 is formed on the two-layer coated molded article coated in two layers by the second plating step 60. And a chromate treatment step 70 to form a.

  The molding step 20 is a step of forging or cutting a blank material as described above. In this step, the head 2 and the shaft 3 are integrally molded to produce the molded article.

  The washing step 30 is a step of removing lubricating oil, dust and the like adhering to the surface of the substrate 4, and the molded article is put into a tank (not shown) filled with an acidic solution. This is the step of degreasing and washing.

  The first plating step 40 is a step of electroplating the molded article cleaned in the cleaning step 30. The molded article is immersed in a plating bath (not shown) mainly composed of zinc or zinc and nickel. And forming the first coating layer 11 on the surface of the substrate 4 with the plating bath in an energized state.

  In the baking step 50, since the hydrogen generated in the cleaning step 30 and the first plating step 40 enters the inside of the base 4, the molded article is heated to a predetermined temperature to transfer the hydrogen in the base 4 to the outside. This is a step for fixing the fluid hydrogen released or remaining inside the substrate 4. Specifically, this is a step of heating the molded article in the range of 190 ° C. to 210 ° C. and keeping the heating time for at least 2 hours. The heating time is preferably set in the range of 4 hours to 6 hours.

  The second plating step 60 is a step of plating the coated molded product from which danger such as hydrogen embrittlement has been removed by the baking step 50. Alternatively, any one of so-called hot-dip plating without energization may be used. In the second plating step 60, the coated molded product is immersed in a tin or tin and zinc plating bath (not shown) in which the tin component is set in the range of 60% to 100%. This is a step of forming the second coating layer 12 on the surface. Preferably, the tin component of the plating bath is set in a range of 70% to 80%.

  The chromate treatment step 70 is a step of forming the third coating layer 13 on the surface of the two-layer coating molded article on which the second coating layer 12 has been formed by the second plating step 60, This is a step of forming a chromate coating on the outside of the second coating layer 12 by immersing the product in a chromate solution containing chromium in a range of 5% to 30% for several tens of seconds.

As described above, in the method for manufacturing the fastening part 1 according to the present invention , the baking step 50 of heating from 190 ° C. to 210 ° C. is set before the second plating step 60, so that the tin having a relatively low melting point is close to the melting point. Never reach. Thereby, since the outermost surface of the fastening component 1 does not become uneven, there is an advantage that the fastening component 1 having high commercial value can be stably manufactured.

DESCRIPTION OF SYMBOLS 1 Fastening component 2 Head 3 Shaft 4 Base 10 Coating layer 11 1st coating layer 12 2nd coating layer 13 3rd coating layer 20 Forming process 40 1st plating process 50 Baking process 60 2nd plating process 70 Chromate processing process

Claims (2)

A forming step of forming a blank material made of metal into a predetermined shape,
A first plating step of electroplating the molded article molded by the molding step to form a first coating layer containing zinc or a component of zinc and nickel on the outer periphery of the molded article;
A baking step of heating the coated molded article having the first coating layer formed in the first plating step in a range of 190 ° C. to 210 ° C. and maintaining the heating time for at least 2 hours;
A second plating step of plating the coated molded article heated by the baking step to form a second coating layer containing tin or a component of tin and zinc on the outer periphery of the coated molded article. Manufacturing method of fastening parts. The method according to claim 1 , further comprising, after the second plating step, a chromate treatment step of immersing the fastening component in a solution containing chromium as a main component.

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