JP6986826B2 - Manufacturing method of fasteners - Google Patents

Description

The present invention relates to a method for manufacturing a fastener having a coating layer on the outer periphery.

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

Further, as a method for forming the coating layer, so-called electroplating is widely used. That is, as shown in FIG. 3, the conventional method for manufacturing fastening parts is a molding step 120 for molding the head portion and the shaft portion, and the molded product molded by the molding step 120 is degreased and pickled for cleaning. The cleaning step 130, an electroplating step 140 for forming the coating layer on the outer periphery of the molded product that has passed the cleaning step 130, and a baking step 150 described later are included.

In the baking step 150, as described in Patent Document 4, hydrogen generated during the cleaning step 130 (particularly during pickling) and the electroplating step 140 invades the inside of the molded product. , This is the process of removing this hydrogen from the molded product. Specifically, the baking step 150 is a step of heating a coated molded product having a coated layer formed by an electroplating step 140 or the like to about 200 ° C. and maintaining this heating temperature for several hours. Therefore, the conventional method for manufacturing fasteners is characterized in that the occurrence of delayed fracture due to so-called hydrogen embrittlement of fasteners can be reduced.

Japanese Unexamined Patent Publication No. 11-257323 Japanese Patent No. 4454640 Japanese Patent No. 2909892 Japanese Patent Application Laid-Open No. 2009-062616

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 melted. As a result, the surface of the coating layer changes from a smooth state to an uneven state, so that there is a problem that the product value of the fastener is lost. Further, since the surface of the fastener is changed to the uneven state in this way, there is also a problem that it is difficult to finish the thickness of the coating layer uniformly. Further, since the coating layer has such an uneven thickness, there is a problem that rust or the like is likely to occur from the portion of the thin coating layer and the corrosion resistance is reduced.

The method for manufacturing a fastening part of the present invention includes a molding step of molding a blank material made of metal into a predetermined shape, and electroplating of the molded product formed by this molding step to contain zinc or zinc and nickel components. The first plating step of forming one coating layer on the outer periphery of the molded product and the coating molded product on which the first coating layer is formed by this first plating step are heated in the range of 190 ° C. to 210 ° C. and this heating time. The first baking step of maintaining the temperature for at least 2 hours and the coating molded product heated by the first baking step are plated, and a second coating layer containing tin or tin and zinc components is applied to the outer periphery of the coating molded product. The second plating step to be formed and the coated molded product after the second plating step are set to a heating temperature lower than that of the first baking step and lower than 190 ° C. , and are heat-treated for at least 2 hours or more. It is characterized by including 2 baking steps. It is desirable to add a chromate treatment step for immersing the coated molded product in a solution containing chromium as a main component between the second plating step and the second baking step. Further, in the second baking step, it is desirable to set the heating temperature of the coated molded product in the range of 100 ° C. to 150 ° C.

In the method for manufacturing a fastening part of the present invention, there is no step of heating in the range of 190 ° C. to 210 ° C., which is close to the melting point of tin, after the second plating step after forming the second coating layer containing a tin component. , The tin component does not elute on the outermost surface of the fastener. Therefore, there is an advantage that the outermost surface of the fastener can be finished into a smooth surface without being formed in an uneven state. Further, the method for manufacturing a fastener of the present invention has an advantage that the outermost surface of the fastener is covered with a coating by chromate treatment, so that the second coating layer and the first coating layer can be protected more firmly. Further, in the method for manufacturing a fastening component of the present invention, the second baking in which the heating temperature of the zinc atom forming the first coating layer and the tin atom forming the second coating layer is set in the range of 100 ° C. to 150 ° C. Each can be diffused by the heat treatment of the step. Therefore, there is an advantage that the degree of adhesion near the boundary surface between the first coating layer and the second coating layer is increased and the internal stress of each coating layer can be removed. Further, since the degree of adhesion between the first coating layer and the second coating layer is increased in this way, there is an advantage that plating peeling and the like are less likely to occur and corrosion resistance is improved.

It is a perspective view of the fastening part which concerns on this invention. Further, (a) is a rivet, (b) is a screw, (c) is a hexagon bolt, and (d) is an enlarged cross-sectional view of a part of a main part of (a) to (c). It is a manufacturing process diagram which shows the manufacturing method of the fastening part which concerns on this invention. It is a manufacturing process diagram which shows the manufacturing method of the conventional fastener | fastener.

The manufacturing method of the fastener of the present invention will be described with reference to FIGS. 1 and 2. First, the fastening component 1 of the present invention is a blank material (not shown) in which a metal wire is cut to a predetermined length and is formed into a predetermined shape, and has a diameter larger than the diameter of the blank material. The head portion 2 and the shaft portion 3 having a diameter smaller than that of the head portion 2 are integrally provided, and the covering layer 10 laminated on the surfaces of the head portion 2 and the shaft portion 3 is provided. Further, the fastening component 1 of the present invention is a so-called rivet, a screw, and a bolt, and the shapes of the head portion 2 and the shaft portion 3 as shown in FIGS. 1 (a) to 1 (c) are different according to the intended use. It is molded.

Specifically, when the fastening component 1 of 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. Further, when it is used as the screw shown in FIG. 1 (b), a male screw is formed in the shaft portion 3 and a cross-shaped drive hole 6 is formed in the head portion 2. Further, when 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, and is a first coating layer 11 formed on the surface of a base material 4 of a molded product obtained by molding the head portion 2 and the shaft portion 3, and the first coating layer 11. 1 It is composed of a second coating layer 12 formed on the outside of the coating layer 11. As shown in FIG. 1D, the coating layer 10 is a third coating layer 13 thinner than the thickness of the first coating layer 11 or the second coating layer 12 on the outside of the second coating layer 12. May be formed.

The first coating layer 11 is composed of zinc or zinc and nickel components, and is formed by electroplating the molded product. Further, the first coating layer 11 is set to have a thickness of 1 μm to 10 μm, and is preferably configured to have a thickness of 2 μm to 3 μm.

The second coating layer 12 is composed of tin or a component of tin and zinc, and is formed by subjecting the electroplating or hot-dip plating. The second coating layer 12 is set to a thickness of 5 μm to 20 μm, preferably 10 μm to 15 μm. Further, since tin contained in the component of the second coating layer 12 has high heat dissipation, the 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 workpieces that tend to get hot.

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

Therefore, the fastener 1 of the present invention has an advantage of being excellent in corrosion resistance because the outer periphery of the molded product is protected by the first coating layer 11 and the second coating layer 12. 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, the fastening component 1 functions as a heat dissipation component if it is fastened to a work that tends to become hot. There are also advantages. Further, when the outermost surface of the fastener 1 of the present invention is the third coating layer 13, the fastening component 1 is protected by the above-mentioned two coating layers (first coating layer 11 and second coating layer 12). It has even higher corrosion resistance than the above.

Next, in the method for manufacturing the fastening parts of the present invention, as shown in FIG. 2, the blank material is press-molded by a mold (not shown) or the like, or the blank material is formed by a cutting tool (not shown). ) And the like to form the molded product, a cleaning step 30 for degreasing and cleaning the molded product, and the first coating layer by electroplating the molded product cleaned by the cleaning step 30. The first plating step 40 for forming 11, the first baking step 50 for heating the coated molded product coated by the first plating step 40 for a predetermined time, and the coated molded product heated by the first baking step 50. The third coating layer is added to the second plating step 60 for forming the second coating layer 12 by electroplating or hot-dip plating, and the two-layer coating molded product coated with the two layers by the second plating step 60. A chromate treatment step 70 for forming 13 and a second baking step 80 for heating the three-layer coated molded product or the two-layer coated molded product coated with the three layers by the chromate treatment step 70 for a predetermined time are included.

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

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

The first plating step 40 is a step of electroplating the molded product cleaned by the cleaning step 30, and the molded product is immersed in zinc or a plating bath (not shown) containing zinc and nickel as main components. This is a step of forming the first coating layer 11 on the surface of the substrate 4 by energizing the inside of the plating bath.

In the first baking step 50, hydrogen generated in the cleaning step 30 and the first plating step 40 penetrates into the base material 4, so that the molded product is heated to a predetermined temperature to remove the hydrogen in the base material 4. This is a step for immobilizing the fluid hydrogen released to the outside or remaining inside the substrate 4. Specifically, it is a step of heating the molded product in the range of 190 ° C. to 210 ° C. and maintaining this heating time for at least 2 hours or more. 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 the risk of hydrogen brittleness and the like has been removed by the first baking step 50, and the same electroplating as in the first plating step 40 is performed. Or, it may be either so-called hot-dip plating that does not energize. Further, 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%, and the coated molded product is subjected to the coating molded product. This is a step of forming the second coating layer 12 on the surface. The tin component of the plating bath is preferably set in the 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 product on which the second coating layer 12 is formed by the second plating step 60, and the two-layer coating molding. This is a step in which the product is immersed in a chromate solution in which chromium is set in the range of 5% to 30% for several tens of seconds to form a chromate film on the outside of the second coating layer 12.

In the second baking step 80, either the three-layer coated molded product or the two-layer coated molded product that has passed through the chromate treatment step 70 or the second plating step 60 is heated from the heating temperature of the first baking step 50. Is a process of heating at a low temperature for 2 hours or more. The heating temperature of the second baking step 80 is set in the range of 100 ° C to 150 ° C, and is preferably 140 ° C.

Method for producing a fastening part 1 of the present invention as described above, first because not bake step 50 is set to be heated from 190 ° C. prior to the second plating step 60 to 210 ° C., a relatively low melting point the tin Never reaches near the melting point. As a result, since the outermost surface of the fastener 1 is not uneven, there is an advantage that the fastener 1 having a high commercial value can be stably manufactured. Further, in the method for manufacturing the fastening component 1 of the present invention, after molding up to at least the second coating layer 12, the zinc atom which is the main component of the first coating layer 11 is formed by the heat treatment in the second baking step 80. , It is possible to diffuse the atom of tin which is the main component of the second coating layer 12. As a result, the vicinity of the boundary surface between the first coating layer 11 and the second coating layer 12 becomes a layer containing zinc and tin components in a well-balanced manner, so that strong adhesion can be obtained.

1 Fastening parts 2 Head 3 Shaft 4 Base 10 Coating layer 11 1st coating layer 12 2nd coating layer 13 3rd coating layer 20 Molding process 40 1st plating process 50 1st baking process 60 2nd plating process 70 Chromate treatment Process 80 2nd baking process

Claims (3)

The molding process of molding a blank material made of metal into a predetermined shape,
The first plating step of electroplating the molded product molded by this molding step to form a first coating layer containing zinc or zinc and nickel components on the outer periphery of the molded product.
The first baking step of heating the coated molded product on which the first coating layer is formed by this first plating step in the range of 190 ° C. to 210 ° C. and maintaining this heating time for at least 2 hours or more.
A second plating step of plating the coated molded product heated by the first baking step to form a second coating layer containing tin or tin and zinc components on the outer periphery of the coated molded product.
The inclusion includes a second baking step in which the coated molded product after the second plating step is set to a heating temperature lower than that of the first baking step and is set to a temperature lower than 190 ° C. and is heat-treated for at least 2 hours or more. A characteristic method for manufacturing fasteners. The first aspect of the present invention is characterized in that a chromate treatment step of immersing the coated molded product in a solution containing chromium as a main component is added between the second plating step and the second baking step. Manufacturing method of fastening parts. The method for manufacturing a fastener according to claim 1 or 2, wherein the second baking step sets the heating temperature of the coated molded product in the range of 100 ° C. to 150 ° C.

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