JP2022030191A - Tack screw - Google Patents

Abstract

To provide a tack screw capable of realizing loose torque characteristics comparable to conventional hexavalent chromate coatings while achieving excellent corrosion resistance with a simple structure.SOLUTION: A tack screw is provided with a zinc-plated layer 2 on the surface thereof, and a glass coating film 4 having a hardness higher than that of the zinc-plated layer 2 is laminated on the surface.SELECTED DRAWING: Figure 2

Description

The present invention relates to a rivet screw having a zinc-plated layer on the surface.
However, in the present specification, "tack screw" shall mean a bolt, a screw, a screw, a nut, and a washer.

For rivets such as bolts, screws, and nuts, which are iron rivets, after providing a zinc-plated layer on the surface, chemical conversion treatment can be performed to further improve corrosion resistance. In the chemical conversion treatment, a hexavalent chromate film can be provided to improve the corrosion resistance of the rivet screw, but since hexavalent chromium causes pollution, a trivalent chromium compound has been developed in place of the hexavalent chromate treatment (patented). See Document 1).

The trivalent chromium compound used in place of the hexavalent chromate treatment has a loosening torque of 10 to 20% lower than that of the hexavalent chromate coating in the tightened state. It becomes easy to loosen, which is a big drawback. In order to improve the loosening torque, which is a drawback of the trivalent chromate film, a technique has been developed in which the film thickness of the trivalent chromium chemical conversion coating provided on the surface of the screw is extremely thinned to 50 nm to 100 nm (Patent Document 2). reference).

For the extremely thin trivalent chromate film, when the screw is tightened, the trivalent chromate film provided on the surface of the male thread is peeled off to expose the galvanized layer, and the threads and female screw holes of the male thread are exposed. The structure is such that the female screws are brought into contact with each other to suppress a decrease in loosening torque. However, an extremely thin trivalent chromate film having a diameter of 100 nm or less does not have sufficient corrosion resistance due to the chromate treatment, and if it is made thicker in order to eliminate this defect, a harmful effect of lowering the loosening torque occurs.

Special Table 2000-509434 Gazette Japanese Unexamined Patent Publication No. 2006-348314

The present invention has been developed for the purpose of eliminating the above-mentioned drawbacks, and an important purpose of the present invention is to realize excellent corrosion resistance with a simple structure and to be inferior to the conventional hexavalent chromate coating. It is to provide galvanized studs that provide no loosening torque characteristics.

Means for Solving Problems and Effects of Invention

The rivet screw according to an embodiment of the present invention is a rivet screw having a galvanized layer provided on the surface thereof, and a glass coating film having a hardness higher than that of the galvanized layer is provided on the surface of the galvanized layer.

The above-mentioned rivet screw of the present invention realizes extremely important characteristics in the rivet screw, such as excellent corrosion resistance and improvement of loosening torque characteristics, while having an extremely simple structure.

The stud screw of another embodiment of the present invention is a film in which the glass coating film is broken in the tightened state. The above-mentioned stud screw has a feature that the loosening torque can be further strengthened in the tightened state by the glass powder in which the glass coating film is broken.

The stud screw of another embodiment of the present invention is a waterproof film in which the glass coating film is substantially impermeable to water permeability. In the above rivet screw, the glass coating film covering the galvanized layer prevents water from permeating, and excellent corrosion resistance can be realized.

In the stud screw of another embodiment of the present invention, an inorganic powder or granular material having a hardness higher than that of the glass coating film is embedded in the glass coating film. The above-mentioned tack screw has a feature that the loosening torque can be further increased by the inorganic powder or granular material embedded in the glass coating film.

The rivet screw of another embodiment of the present invention comprises a glass coating film laminated directly on the surface of a non-chromate treated galvanized layer. The above-mentioned tack screw has a feature that corrosion resistance can be improved while preventing the damage of hexavalent chromium caused by chromate treatment.

In the rivet screw of another embodiment of the present invention, the film thickness of the glass coating film is 1 μm or more and 10 μm or less.

In the screw stud screw of another embodiment of the present invention, the thickness of the galvanized layer is 5 μm or more and 15 μm or less.

FIG. 1 is a schematic side view showing a stud screw (bolt) according to an embodiment of the present invention. FIG. 2 is a schematic side view showing a stud screw (bolt and nut) according to an embodiment of the present invention. FIG. 3 is an enlarged cross-sectional view of a main part of the stud screw shown in FIGS. 1 and 2. FIG. 4 is an enlarged cross-sectional view of a main part showing a stud screw according to another embodiment of the present invention. FIG. 5 is an enlarged cross-sectional view of a main part showing a stud screw according to another embodiment of the present invention. FIG. 6 is an enlarged cross-sectional view of a main part showing a washer according to another embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings. In the following description, terms indicating a specific direction or position (for example, "upper", "lower", and other terms including those terms) are used as necessary, but the use of these terms is used. The purpose is to facilitate understanding of the invention with reference to the drawings, and the meaning of these terms does not limit the technical scope of the present invention. Further, the parts having the same reference numerals appearing in a plurality of drawings indicate the same or equivalent parts or members. Further, the embodiments shown below show specific examples of the technical idea of the present invention, and do not limit the present invention to the following. In addition, the dimensions, materials, shapes, relative arrangements, etc. of the components described below are not intended to limit the scope of the present invention to the specific description, but are exemplified. It was intended. Further, the contents described in one embodiment and the embodiment can be applied to other embodiments and the embodiments. In addition, the size and positional relationship of the members shown in the drawings may be exaggerated in order to clarify the explanation.

1 to 6 show a bolt 100 (including a screw and a screw in addition to a bolt), a nut 200, and a washer 300, which are stud screws according to an embodiment of the present invention. 3 to 5 show an enlarged cross-sectional view of a screw thread provided on the bolt 100 and the nut 200, and FIG. 6 shows an enlarged cross-sectional view of the surface of the washer 300. The bolt, screw, and screw shown in the figure have a head portion 9 and a shaft portion 10 having a spiral thread (male screw portion 11) on the surface thereof. The nut 200 shown in FIG. 2 has a female screw portion 13 having a spiral thread on the surface of the female screw hole 12 in the center, and the male screw portion 11 of the screw 100 is screwed into the female screw portion 13 of the nut 200. And fixed. The washer is a ring-shaped metal plate, and has a flat washer and a spring washer. FIG. 6 shows a flat washer.

The rivet screw shown in the above figure is made of iron made of iron or an iron alloy, is electroplated to provide a zinc-plated layer 2 on the entire surface, and further, a glass coating film 4 is laminated on the surface of the galvanized layer 2. There is. The glass coating film 4 is transparent and is preferably laminated directly on the surface of the zinc-plated layer 2 which is not chromate-treated. The rivet screw provided with the glass coating film 4 on the surface of the galvanized layer 2 that is not chromate-treated can realize a beautiful silver screw while eliminating the influence of hexavalent chromium due to the chromate treatment. However, the rivet screw of the present invention can realize a strong loosening torque by laminating a glass coating film 4 on the surface of a galvanized layer 2 that has undergone chemical conversion treatment such as trivalent chromate treatment. It can also be laminated on the surface of the chemical conversion-treated galvanized layer 2.

In consideration of corrosion resistance, the galvanized layer 2 has a thickness of, for example, 5 μm or more and 15 μm or less, preferably 5 μm or more and 10 μm or less. In consideration of corrosion resistance and loosening torque, the glass coating film 4 has, for example, a film thickness of 1 μm or more and 10 μm or less, preferably 3 μm or more and 5 μm or less.
(Galvanized layer 2)

The studs shown in FIGS. 1 to 6 are provided by laminating the galvanized layer 2 and the glass coating film 4 on the entire surface, but the bolt 100 (including screws and screws in addition to the bolt), the nut 200, and the like are The glass coating film 4 may be provided only on the male screw portion 11 provided with the spiral thread, and the nut may be provided only on the female screw portion 13.

The zinc-plated layer 2 is preferably provided on the entire surface of the rivet screw through the following degreasing step, pickling step, electrolytic degreasing step, and plating step.
[Degreasing process]
This step is a step for removing oils and fats adhering to the surface of the rivet screw and providing a uniform zinc-plated layer 2 on the surface. You can use an alkaline cleaning method that degreases with.
[Pickling process]
This step removes oxide films, metal chips, inorganic stains and the like. In this step, an inorganic acid and a corrosion inhibitor are combined and chemically removed.
[Electrolytic degreasing process]
In this step, the material and the electrode plate are made to face each other in an alkaline degreasing solution, and an electric current is passed to remove oils and fats. Hydrogen gas is generated from the cathode and oxygen gas is generated from the anode by electrolysis, and the degreasing effect is enhanced by the stirring effect and mechanical effect of the material surface, and the cathode reduction and anodic oxidation action.
[Plating process]
In this step, preferably, using a zincate bath or an acidic bath, the rivet screw is placed in a conductive barrel and immersed, and the rivet screw is energized and galvanized while rotating the barrel. It can be soaked in a barrel, depping with a sloping barrel, or sprayed with a new liquid. For the zinc oxide bath, use a bath containing zinc oxide and sodium hydroxide as the main components. As the acidic bath, a bath containing zinc chloride, ammonium chloride or potassium chloride as a main component is used. Brighteners and additives can be used in this step. The plating bath for immersing the rivet screw has a temperature of preferably 20 ° C to 35 ° C, a DC voltage of 3V to 10V, a current density of 0.5A / m ² to 5A / m ² , and a film thickness of 5μm to 15μm. The zinc-plated layer 2 to be used is formed on the entire surface of the screw.

The rivet screw can be formed by directly laminating the glass coating film 4 on the surface of the galvanized layer 2 produced in the above steps, or by forming the galvanized layer 2 and then forming the glass coating film 4. It is also possible to form the glass coating film 4 after performing the zinc phosphate treatment. As the chemical conversion treatment, zinc phosphate treatment, chromate treatment, or the like can be used. Zinc phosphate treatment is a solution in which phosphoric acid, primary zinc phosphate and an oxidizing agent are mixed, and a film of Zn ₃ (PO ₄ ) 2.4H ₂ O is formed _on the surface of the screw. In the chromate treatment, a chromate-treated film is formed by immersing in a solution containing chromic acid, sulfuric acid, nitric acid, phosphoric acid and the like with chromium hydroxide and chromic acid.
(Glass coating film 4)

The rivet screw forms a zinc-plated layer 2 on the entire surface thereof, and then further forms a glass coating film 4 on the surface thereof. The glass coating film 4 can be provided not only on the entire surface of the rivet screw but also only on the male screw portion 11 provided with the spiral screw thread. The film thickness of the glass coating film 4 is set to, for example, 1 μm to 10 μm as described above in consideration of corrosion resistance and loosening torque. If the glass coating film 4 is too thin, the loosening torque and corrosion resistance are lowered, and if it is too thick, the processing cost is high and the tightening of the female screw holes may be impaired.

The glass coating film 4 is an inorganic film cured in the form of glass, and is formed by immersing a screw or nut in a liquid glass coating agent or spraying it to uniformly apply it to the surface of the screw and then curing it. The glass coating film 4 preferably contains SiO ₂ as a main component, and particularly preferably 80% or more of SiO ₂ . Further, as the glass coating agent, a compound that cures at room temperature and promotes SiO ₂ conversion is preferable, but the glass coating agent is not limited thereto. For example, a glass coating agent whose curing is promoted by heating may be used.
(Primer layer 8)

As shown in FIG. 4, the glass coating film 4 can also be coated with a glass coating agent after forming the primer layer 8 on the surface of the galvanized layer 2. As the primer layer 8, a layer that improves the adhesive force of the glass coating agent can be used, and for example, various resin layers such as acrylic, phenol, urethane, epoxy, and polyester can be used. Furthermore, as the glass coating agent, for example, polysilazane, tetraethoxysilane, water glass, an organic silane compound and the like can be used, and for example, already commercially available silane compound containing a catalyst can also be used.

The glass coating film 4 is preferably a waterproof film having substantially no water permeability. However, in the present specification, the "waterproof film having substantially no water permeability" is a film having a smaller water permeability than the zinc-plated layer 2, and can suppress or prevent the permeation of water to improve corrosion resistance. Show things.

The galvanized layer 2 cannot eliminate the generation of fine gaps due to the gas generated in the plating process, which causes the corrosion resistance of the galvanized layer 2 to deteriorate. Providing a glass coating film 4 that is more impermeable than the galvanized layer 2 on the surface of the galvanized layer 2 is effective in improving the corrosion resistance of the galvanized layer 2 having fine gaps.

Further, as the glass coating film 4 provided on bolts, screws, screws, nuts, washers and the like, a hard glass material that is destroyed by the impact of being tightened is suitable. The glass coating film 4 is destroyed with the bolts, screws, screws, and nuts tightened, and the washer is pressed and destroyed while being rubbed with the screws and bolts tightened. The glass coating film 4 has a pencil hardness of 3H or more, more preferably a pencil hardness of 5H or more in a cured state, and can be broken by the impact of tightening. The glass coating film 4 is broken in a tightened state to strengthen the loosening torque. The broken glass powder is sandwiched between the male screw portion 11 and the female screw portion 13 to increase the frictional resistance, and the glass powder on both sides of the washer 300 increases the frictional resistance with bolts, screws, screws, etc. Because it does. These rivet screws can increase the loosening torque by about 4% to 15% as compared with the rivet screws in which the glass coating film 4 is not laminated on the galvanized layer 2.
(Inorganic powder or granular material 5)

Further, as shown in FIG. 5, the glass coating film 4 can be mixed with the inorganic powder or granular material 5 to further strengthen the loosening torque. The inorganic powder or granular material 5 has a higher hardness than the glass coating film 4, and for example, powder or granular material such as alumina or silica having an average particle size of 1 μm to 10 μm can be used. By embedding the inorganic powder or granular material 5 having a hardness higher than that of the glass coating film 4 in the glass coating film 4, the loosening torque can be increased. The glass coating film 4 can increase the mixing ratio of the inorganic powder or granular material 5 to increase the loosening torque. However, since the inorganic powder or granular material 5 is added while being embedded in the glass coating film 4, the inorganic powder or granular material 5 is added. The addition amount is 10% by weight or more and 80% by weight or less, and is embedded in the glass coating film 4 to strengthen the loosening torque.
(Example 1)

A galvanized layer 2 having a film thickness of 5 μm is electroplated and adhered to the surface of a bolt of M5, and a glass having a film thickness of 3 μm is attached to the surface of the galvanized layer 2 without chemical conversion treatment. 100 bolts were prototyped by laminating the coating film 4. The prototype bolt was installed outdoors for 3,000 hours at a location 30 m from the seaside, and as a result of follow-up observation of corrosion resistance deterioration, no corrosion was observed even after 3,000 hours. Further, when the surface was screwed into a nut having neither plating nor a glass coating film and the loosening torque was measured, it was about 7% stronger than that of only the zinc plating layer 2 without the glass coating film 4.
However, perhydropolysilazane manufactured by Clariant Japan Co., Ltd. is used as the glass coating agent, zinc-butyl ether is added as a solvent for this perhydropolysilazane, and a 20 wt% solution is sprayed on the surface of the screw. After that, it was heated and dried at 45 ° C. and cured, and the glass coating film 4 was laminated on the galvanized layer 2.
(Example 2)

When 100 bolts were prototyped in the same manner as in Example 1 except that the thickness of the glass coating film 4 provided on the surface of the bolt was 1 μm, these bolts were placed at a location 30 m from the seaside for 1,500 hours. As a result of observing the deterioration of corrosion resistance by the exposure test installed outdoors, no corrosion was observed on any of the bolts even after 1,500 hours had passed, and the loosening torque was compared with the bolts without the glass coating film 4. Was strengthened by about 4%.
(Example 3)

When 100 bolts were prototyped in the same manner as in Example 1 except that the thickness of the galvanized layer 2 provided on the surface of the bolt was 10 μm and the thickness of the glass coating film 4 was 5 μm, these bolts were found. As a result of observing the deterioration of corrosion resistance by an exposure test in which it was installed outdoors for 3,000 hours at a location 30 m from the seaside, no corrosion was observed on any of the bolts even after 3,000 hours had passed, and the glass coating film. Loosening torque was increased by 10% compared to bolts without 4.
(Example 4)

When 100 bolts were prototyped in the same manner as in Example 1 except that the thickness of the galvanized layer 2 provided on the surface of the bolts was 15 μm, these bolts were placed 30 m from the seaside for 3,000 hours. As a result of observing the deterioration of corrosion resistance by the exposure test installed outdoors, no corrosion was observed on any of the bolts even after 3,000 hours had passed, and the loosening torque was compared with the bolts without the glass coating film 4. Was strengthened to almost the same level as the bolt of Example 1.
(Example 5)

When 100 bolts were prototyped in the same manner as in Example 1 except that the thickness of the glass coating film 4 provided on the surface of the bolt was 10 μm, these bolts were placed 30 m from the seaside for 3,000 hours. As a result of observing the deterioration of corrosion resistance by the exposure test installed outdoors, no corrosion was observed on any of the bolts even after 3,000 hours had passed, and the loosening torque was compared with the bolts without the glass coating film 4. Was strengthened by about 13%.
(Example 6)

100 bolts were prototyped in the same manner as in Example 1 except that 50% by weight of alumina powder having an average particle size of about 5 μm was added to the glass coating film 4 provided on the surface of the bolt to make the film thickness 10 μm. Then, as a result of observing the deterioration of corrosion resistance by an exposure test in which these bolts were installed outdoors for 3,000 hours at a location 30 m from the seaside, all the bolts were corroded even after 3,000 hours had passed. Was not observed, and the loosening torque was increased by about 15% compared to the bolt without the glass coating film 4.

In the above embodiment, the bolt 100 is used as a specific example of the rivet screw, but when the corrosion resistance and the loosening torque are measured by using 100 screws, screws, nuts, and washers instead of the bolt 100, the bolt is used. It showed excellent characteristics equivalent to 100. Furthermore, when a bolt larger or smaller than M5 was prototyped and the corrosion resistance and loosening torque were measured, the characteristics equivalent to those in the above examples were shown. Further, in the above embodiment, the bolt 100 provided with the galvanized layer 2 and the glass coating film 4 was screwed into the nut without the plated layer 2 and the glass coating film 4, and the loosening torque was measured. When the galvanized layer 2 and the glass coating film 4 were provided on both of the 200 and screwed in to measure the loosening torque, the loosening torque was increased by about 10% to 50%.

INDUSTRIAL APPLICABILITY The present invention can be effectively used as a stud screw for galvanized bolts, screws, screws, nuts, washers, etc., which require excellent corrosion resistance and strong loosening torque.

100 ... Bolt 200 ... Nut 300 ... Washer 2 ... Galvanized layer 4 ... Glass coating film 5 ... Inorganic powder 8 ... Primer layer 9 ... Head 10 ... Shaft 11 ... Male bolt 12 ... Female bolt hole 13 ... Female Bolt part

Claims (7)

It is a stud screw with a zinc-plated layer on the surface.
On the surface of the galvanized layer,
A stud screw characterized in that a glass coating film having a hardness higher than that of the galvanized layer is provided. The stud screw according to claim 1.
The glass coating film
A stud screw characterized by being a film that breaks in the tightened state. The stud screw according to claim 1 or 2.
The glass coating film
A stud screw characterized by being a waterproof film that is virtually impermeable to water. The stud screw according to any one of claims 1 to 3.
On the glass coating film,
A stud screw characterized in that an inorganic powder or granular material having a hardness higher than that of the glass coating film is embedded. The stud screw according to any one of claims 1 to 4.
The glass coating film
A stud screw that is directly laminated on the surface of a galvanized layer that is not chromate-treated. The stud screw according to any one of claims 1 to 5.
A stud screw having a thickness of 1 μm or more and 10 μm or less of the glass coating film. The stud screw according to any one of claims 1 to 6.
A stud screw having a zinc-plated layer having a film thickness of 5 μm or more and 15 μm or less.

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