JPH0420098B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a link chain, and more particularly, to a link chain mainly used for chain blocks. (Prior art) In general, link chains used in chain blocks are required to have a tensile strength of at least 5 times the rated load for safety reasons, and to have low rust and excellent wear resistance. has been done. By the way, regarding the tensile strength, the rated load can be improved by selecting the steel material that makes up the link chain, such as esmanganese steel such as SMn21, or Ni-Cr-Mo steel, which has good toughness and excellent tensile strength. Furthermore, by electroplating the surface of the steel with nickel or zinc or applying chemical plating, it can pass the salt spray test and cause less rust. However, there were problems with wear resistance. That is, even if a film is formed on the steel surface by the plating described above, it has almost no effect on wear resistance, and even if carburized and quenched to impart wear resistance, there is a limit, and even more The wear resistance of tempered link chains was even worse than that of carburized link chains, and there were problems with durability. Conventionally, when using the link chain, lubricating oil is used and constantly lubricated to compensate for the weak points in wear resistance. (Problems to be Solved by the Invention) However, there is a problem in that the link chain is often forgotten to be lubricated with lubricating oil, resulting in insufficient lubrication, which shortens the target durability period. Reslink chains have been strongly requested for a long time. The purpose of the present invention is to provide not only carburized link chains but also heat-treated link chains without changing the composition of the steel material, in other words, while using commercially available steel, it has excellent wear resistance and does not require lubrication. The aim is to provide an oil-free link chain. (Means for Solving the Problems) The present invention provides a film with a thickness of 3μ on the surface of steel having a surface hardness of 570 (HV) or more and an internal hardness of 36 to 50 (HRC). A base film consisting of a copper film having cushioning properties that is softer than the surface hardness of the steel is formed on the surface of the base film, and a fluorine-based polymer, fluorinated graphite, and silicone caramel which have lubricity and wear resistance are coated on the surface of the base film. It is characterized in that by electroplating with a nickel plating solution in which fine particles such as bits, molybdenum dioxide, etc. are dispersed, an outer layer film having a thickness of 8 to 35 micrometers in which the fine particles are deposited together with nickel is formed. (Function) With the above configuration, while using a steel material that can sufficiently obtain the tensile strength required for the link chain, the outer layer film can be applied to the surface of the steel material in a film thickness.
The underlying film, which has a thickness of over 3 μm, blends in well and forms a strong adhesion, and provides cushioning and thermal insulation properties between the steel material and the outer film, thereby making it possible to withstand the harsh conditions of use of the link chain. Also, peeling of the outer layer film and heat conduction of frictional heat generated in the outer layer film to the steel surface can be prevented,
As a result, the outer layer film can significantly improve lubricity and wear resistance over a long period of time without reducing corrosion resistance, and can also suppress sliding resistance to a minimum. The steel material used for the link chain of the present invention is
Manganese steel such as SMn21 and SMn21C or
Manganese steel standardized to SEC1524, 1527, or boron steel added with 0.005% by weight, or Ni-Cr-Mo steel, etc., with surface hardness.
570 (HV) or higher hardness, chain grade grade T(8) (ISO standard 3077-1980,
JISB8812-1981) or above are suitable. still,
The carburized link chain has a martensitic structure that has been carburized, quenched, and tempered, and the tempered link chain has a martensitic structure that has been quenched and tempered. In addition, when a fluorine-based polymer and fluorinated graphite are used as the fine particles, they are dispersed in the Nickelmetsuki liquid together with a cationic activator, a nonionic activator, or a cationic amphoteric surfactant that strongly adsorbs to the fine particles. Let it happen. The reason for using the above-mentioned activator is to positively charge the surface of the fine particles so that the fine particles can be easily deposited together with nickel ions by electroplating. In addition, when using the polytetrafluoroethylene mentioned above, an activator having a C-F bond is preferable.
Further, the particle size of the fine particles of the fluorine-based polymer is suitably 0.3 μm to 3 μm in diameter. (Example) Next, an example of the link chain of the present invention will be described. Example 1 SMn21 is used as the steel material, and this material is 9.5φ
After drawing the wire, it is bent and welded to form a link-shaped chain element. After degreasing, pickling, and degreasing again, this chain element is coated with a copper plating solution using copper cyanide for about 50 minutes.
Electroplating is performed for 5 minutes to form a copper film with a thickness of more than 3 μm, which is softer and has more cushioning properties than the surface hardness of the steel, which is less than 5 μm. After that, a flash unit is sprayed with nickel for about 5 minutes.
A nickel film is formed on the outer surface of the copper film. The copper coating and the nickel coating are base coatings that allow the coating described later to blend into the surface of the steel material, improve its adhesion, and prevent the coating from peeling off due to its cushioning action. Next, nickel sulfate 280g/, nickel chloride
45g/and boric acid 40g/, saccharin 2g/
The plating solution is prepared by gradually adding 50 g of a mixture of polytetrafluoroethylene fine particles and a cationic activator into the nickel plating solution with stirring, and using this plating solution, Solution 40-60℃, usually 50℃, current density
The chain element is plated under conditions of 4 A/dm ² to form an outer layer film having a thickness of 8 to 35 microns in which the fine particles are precipitated together with nickel. The plating is carried out by supporting the chain element on a jig and moving the chain element. Although the jig may be raised above the level of the plating liquid, it is preferable to immerse it below the liquid level. However, the outer layer film having a thickness of 8 μ to 35 μ can be formed in a short time. In the embodiments described above, fine powder of polytetrafluoroethylene was used as the fine particles, but other materials such as graphite fluoride, silicon carbide, molybdenum disulfide, etc. can also be used. As in the case of using fluorine-based polymers such as polytetrafluoroethylene, these fine particles are used in an amount of 50 g/1, and the film thickness is also 15
It is set to ~35μ. Incidentally, nickel sulfamate can also be used as the nickel plating liquid. When we investigated the abrasion resistance of the link chains formed as described above with the outer film thicknesses of 15μ, 20μ, 25μ, 30μ, and 35μ, we obtained the results shown in Table 1. .

[Table] In Table 1, an electric chain block with a 1.5 ton capacity is used, and the sample is
A link chain is set, a load with a rated load of 1.5 tons is suspended from the chain, and the hoisting speed is 8 m/
After lifting the load to a height of 1 m and unloading it to the original position, the degree of wear was measured using a chain gauge.
This is a measurement of the number of times until % wear, and each sample ~
The numbers in are the average values of test specimens manufactured under the same conditions. In addition, although the results shown in Table 1 are based on examples using fine powder of polytetrafluoroethylene as the fine particles, the same effect can be obtained even when graphite fluoride, silicon carbide, and molybdenum disulfide are used. is obtained. Figure 1 shows a graph of the average values of the test results shown in Table 1.As is clear from Figure 1, when the thickness of the outer layer film is less than 8μ, a sufficient effect can be obtained. However, by making it 15μ or more, the number of times can be increased dramatically. still,
When the thickness of the outer layer film is made thicker than 35 μm, not only the improvement in wear resistance is small but also a peeling phenomenon occurs. Therefore, the thickness of the outer layer film is 15 to 35μ.
That is to say. By the way, conventional link chains usually experience 5% wear after 2,500 to 5,000 cycles. In addition, when we investigated the relationship between the stress acting on the chain and the number of times using a film with a thickness of 25 μm, we found that
The results shown in Figure 2 were obtained. The one shown in Figure 2 corresponds to a 750Kg to 1 ton specification chain block that is normally used in a stress range of 10 to 12Kg/mm.
In the case of Kg/mm, the durability is 70,000 times, and even with 12Kg/mm, the durability is 50,000 times. Therefore, it is clear that if the stress applied to the chain is less than 10 kg/mm, its durability can be further improved. In addition, what is indicated by a dashed line in Fig. 2 is
Nickel is electroplated or electroless plated, and the film thickness is
A nickel plating film of 30 μm is formed, and if the stress is in the range of 10 to 12 kg/mm, 5% wear will occur after 5000 cycles or less. Also, stainless steel (svs304) is used as the chain material.
When using plating, it has excellent durability, but as with the case without plating, 5% wear occurs after 2000 to 30000 times or less. Further, when forming a 50μ manganese phosphate film, the number of times of 5% wear in the range of 10 to 12 kg/mm can be 10,000 to 20,000 times, but the corrosion resistance is poor. Next, Table 2 shows a comparison of the wear resistance and corrosion resistance of the present invention with those of conventional products. In Table 2, ◎ means very good, △ means very good, ○ means average, △ means bad, and × means very bad.

【table】

[Table] The examples described above are link chains that are carburized and quenched to be used as road chains for electric chain blocks, but they can also be applied to tempered chains used for road chains for manual chain blocks. can. (Effects of the Invention) As described above, the present invention has a surface hardness of 570 (HV) or more and an internal hardness of 36 to 50 (HRC) with a film thickness of more than 3μ. A base film made of a copper film having cushioning properties that is softer than the surface hardness of the steel is formed, and on the surface of the base film,
By electroplating with a nickel plating liquid in which fine particles of fluorine-based polymer, fluorinated graphite, silicon carbide, molybdenum dioxide, etc., which have lubricity and wear resistance are dispersed, a film thickness of 8 μm or more in which the fine particles are precipitated together with nickel is formed. Since it is characterized by the formation of a 35μ outer layer film, it has significantly improved wear resistance without reducing corrosion resistance, compared to conventional link chains that have a film formed simply by nickel plating or zinc plating. You can improve your sexuality,
In addition, sliding resistance can be minimized, making it particularly suitable as a road chain for electric chain blocks that have had problems with wear resistance. In addition, when forming the outer layer film on the surface of the steel that is the material of the link chain, a base layer is formed on the surface of the steel in advance, which is made of a copper film with a thickness exceeding 3 μm and having cushioning properties softer than the hardness of the steel. Since a film is formed and the outer layer film is formed on the surface of the base film, the outer layer film can be well adapted to the surface of the steel through the base film to form a strong adhesion. At the same time, cushioning properties can be imparted to the outer layer coating, and as a result, even if the outer layer coating is made as thick as 8μ to 35μ, the problem of peeling can be reduced. The heat conduction to the steel can be reduced by the thickness of the outer layer film and the base film, so even if frictional heat is generated at the joints of each link when using a link chain, this heat is not conducted to the steel surface. This prevents any adverse effects on the composition of the steel surface. As a result, the lubricity and wear resistance can be significantly improved over a long period of time, and the sliding resistance can be suppressed to a minimum due to the outer layer film with a thickness of 8μ to 35μ in which the fine particles are precipitated together with nickel. be.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between the film thickness of the film and the number of times of 5% wear in the link chain of the present invention, and FIG. 2 is a graph showing the relationship between the stress acting on the chain and the number of times of 5% wear.

Claims (1)

[Claims] 1. On the surface of steel with a surface hardness of 570 (HV) or more and an internal hardness of 36 to 50 (HRC), the film thickness exceeds 3 μ and has cushioning properties that are softer than the surface hardness of the steel. A base film consisting of a copper film is formed, and a nickel plating liquid is used in which fine particles of fluorine-based polymer, fluorinated graphite, silicon carbide, molybdenum dioxide, etc., which have lubricity and wear resistance are dispersed on the surface of the base film. By electroplating,
Film thickness where the fine particles are deposited together with nickel
A link chain characterized by forming an outer layer film of 8μ to 35μ.