JPS6059987B2 - Manufacturing method of strong wear-resistant and corrosion-resistant link chain - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a motor block and a chain block as loading equipment, and relates to a method for manufacturing a link chain having high strength, high toughness, and corrosion resistance.

[Background of the Invention] A motor block or chain block has a mission as a lifting machine.

The link chains used in these systems are directly subjected to loads during the lifting and hanging of loads, and may also be subject to significant stress due to abnormal load lifting.
For this reason, link chains must have high strength, excellent wear resistance because they can withstand contact wear, and safety. In addition to this, it is also required to have toughness. On the other hand, in recent years, link chains that are not only strong but also have excellent corrosion resistance are desired in the food, medical, and fisheries fields. On the other hand, as corrosion-resistant link chains, link chains made of stainless steel or those subjected to various plating treatments have conventionally been used. However, stainless steel has the disadvantage that it not only does not provide the required functionality, but is also expensive, and when a load is applied to a link chain made of stainless steel, bending stress is generated in the chain. There was a drawback that a difference in elastic strain occurred between the plated layer and the base layer, and the plated portion peeled off, resulting in a significant decrease in corrosion resistance. [
OBJECT OF THE INVENTION The object of the present invention is to provide a method for producing a strong, wear-resistant and corrosion-resistant link chain that eliminates the above-mentioned drawbacks.

[Summary of the Invention] As a result of various research conducted by the present inventors in order to develop a link chain that is strong, wear-resistant, and corrosion-resistant, the inventors have achieved the above object using a melt having the composition and manufacturing process as shown below. I found out what I can do.

In other words, a link chain made of steel is carburized or carbonitrided, and in that atmosphere it becomes SnlO~ by weight.
We have found a method of directly inserting and cooling a molten liquid having a composition of 70% Cd, 5-40% Cd, and 60% Bi2O, preferably at a temperature of 250 DEG C. or lower. By doing so, a link chain that is strong, wear-resistant, and corrosion-resistant can be obtained. Here, the composition of the melt is expressed in weight%
with SnlO~70%, Cd5~40% and BI2O~6
The reason why it is set at 0% is that firstly, the melting point can be lowered to about 180°C due to the synergistic effect of the three elements Sn, Bi, and Cd, and it is possible to lower the melting point to about 180°C from carburizing, carbonitriding, and normal quenching temperatures to this melt. By cooling the link chain during insertion, a sufficient hardening result can be obtained. If the composition is other than this, the melting point will be high and the quenching result will not be sufficient. Second, by inserting the link chain into the melt, the melt adheres to the surface of the link chain, which has a significant effect on the melt. The melting temperature of the Sn-Cd-Bi alloy melt is preferably 250°C or lower.

If the temperature is set higher than 250° C., it is difficult to obtain quenching cooling results and desired strength and wear resistance as a link chain with a melt having these compositions.

The lowest freezing point of the Sn-Cd-B1 alloy is about 180°C. [Embodiment of the invention] Chemical composition is C: 0.21% in weight%
, Si: 0.21%, Mn: 1.39%, P: 0.01
Various experiments were conducted on a link chain with a wire diameter of 7.1 Tnmφ made of an alloy consisting of 3% S, 0.011% S, and residual Pe.

In Fig. 1, after carburizing the link chain for 870x20 minutes, the link chain was carburized with Sn65% by weight while maintaining the atmosphere.
2 made of an alloy with a composition of 25% BI and 25% CdlO
Three powders are inserted into a 10'C melt, quenched, and cooled.
This is an example of the present invention. 2 is traditionally done8
The powder was carburized twice at 70°C, cooled in oil, and then tempered at 200°C.

No. 3 was soaked in a Sn bath after the treatment of No. 2.

4 is made of SUS3O4.

FIG. 1 shows the tensile test results for the four types mentioned above.

As is clear from this, Sample No. 1 made according to the present invention and Sample No. 2 of the conventional example are excellent in both tensile strength and elongation, and are the strongest. Figure 2 shows the results of the oscillation fatigue test of the link chain.

In terms of fatigue strength, it can be seen that product 1 of the present invention exhibits higher strength than product 3 with other plating treatments and 4 with SUS3O dust. FIG. 3 shows a link chain wear test conducted using an actual motor block with a rated load of 1 t0n, and the conditions were a dry atmosphere.

The results of the abrasion test show that Nos. 1 and 2 have almost the same values within the variation range, but are significantly superior to Nos. 3 and 4, which have corrosion resistance. Next, as a corrosion resistance evaluation, we conducted a salt spray test and found that product 1 of the present invention and stainless steel link chain 4 showed no red rust even after 2 hours, but product 2 developed red rust within 1 hour. 3 again
Red rust developed within 5 to 2 hours.

Does the table show various performances? This is a comprehensive evaluation of the test results.

As a result, it can be seen that the product of the present invention has the best performance in each item, and has excellent toughness and corrosion resistance. Fourth
The figure shows the manufacturing process of the product of the present invention and the conventional manufacturing process in which plating was applied to impart corrosion resistance, and it can be seen that the manufacturing process is about half that of the conventional method. Conventionally, plating is performed as a simple method to impart corrosion resistance to mechanical structural members, but when strength is required, post-treatment and pre-treatment are required for plating after heat treatment.

According to the present invention, heat treatment and plating treatment are integrated, and the processing steps can be significantly shortened. [Effects of the Invention] As detailed above, the link chain according to the present invention is superior in its characteristics to the conventional one.

[Brief explanation of the drawing]

Figure 1 is a graph showing the results of a tensile test on a link chain that has been plated. Figure 2 is a graph showing the results of a oscillation fatigue test on a link chain. Figure 3 is a graph showing the results of a wear test on an actual link chain. The figure shows the manufacturing process of the link chain.

Claims (1)

[Claims] 1 A link chain made of steel material is carburized or carbonitrided, and Sn: 10 to 10 by weight in that atmosphere.
70%, Cd: 5 to 40%, and Bi: 20 to 60%.