JPH0234747A - Sheave material - Google Patents

Abstract

PURPOSE:To obtain the title sheave material having less relative wear with a wire to be brought into contact with it and having long service life by using spheroidal graphite cast iron having a specific graphite shape as a sheave material for an elevator. CONSTITUTION:The sheave for an elevator is manufactured with the material of spheroidal graphite cast iron having 80 to 100% spheroidizing rate of graphite, 20 to 100mum grain size of spheroidal graphite and 70 to 100 pieces distribution rate of spheroidal graphite per 1mm<2>, contg. specific amounts of Cu and Mo as a promotor for the bainitic structure and Ni, etc., as a homogenizing promotor for the structure in the use of Mg metal as a graphite spheroidizing agent. The material is subjected to austempering treatment to convert the matrix structure into bainite and to form it into construction material having 260 to 320 HB hardness. The wear loss of the sheave and wire caused by sliding contact therebetween is reduced, by which the wear resistance of the sheave to a wire rope is improved and the service life of an elevator device can be prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a new sheave material, particularly a sheave material suitable for use in elevator sheaves.

[Conventional technology]

Elevators conventionally used to raise and lower people and cargo in high-rise buildings use wire lobes wrapped around sheaves to raise and lower cages containing people and cargo using the frictional force between the two. It has become. The sheave material used here has traditionally been flake graphite cast iron (JI
S FC20~FC30) and spheroidal graphite cast iron (JIS
FCD45 to FCD70) are often used.

The base of these materials is a mixed structure of ferrite and pearlite or a pearlite structure, and the hardness is Vickers hardness H (
3-143 to 240 or so, graphite particle size 100 to 150
It has physical properties of μm.

[Problem to be solved by the invention]

If the base of the sheave material is a relatively soft ferrite plus pearlite structure, the wire lobe will have a high hardness (
(Vickers hardness of about 430 to 470 Hv), the sheave is likely to wear out due to relative slippage between the sheave and the wire lobe that occurs during operation of the elevator. On the other hand, if the base of the sheave material is a relatively hard pearlite structure, the wire lobes will wear out and become slippery, reducing traction performance.

In either case, the sheave or wire lobe must be replaced as soon as possible to maintain safety.

In particular, sheaves are more prone to wear than wire lobes, and in some cases some have to be replaced after only a few years.

[Purpose of the invention]

Thus, in view of the above-mentioned problems, the present invention prevents the amount of wear of the sheave and wire lobe that occurs during elevator operation from increasing unilaterally, and reduces the amount of wear of both as much as possible, so that the wear amount of the sheave and wire lobe can be maintained for a long period of at least 10 years. The object of the present invention is to provide a long-life sheave material with excellent wear resistance that can be used for years without needing to be replaced.

[Means to solve the problem]

According to research and experiments conducted by the present inventors, a sieve material that can achieve these objectives has a spheroidization rate of 80% to 100%, a graphite particle size of 20 μm to 100 μm, and a graphite particle number of 70/- to 100/mtA. The brinell hardness is HB260~32.
It was discovered that the material was made of 0 spheroidal graphite cast iron.

The present invention will be explained in detail below.

As described above, the present invention aims to minimize the amount of wear caused by sliding contact between the sheave and the wire lobe, and particularly to improve the wear resistance of the sheave with respect to the wire lobe.

Since the wear properties of spheroidal graphite cast iron are generally better than those of flake graphite cast iron, spheroidal graphite cast iron is also used in the sheave material according to the present invention. In order to make the lubricating effect of graphite even out and to equalize the wear on the sheave groove surface, and to avoid local wear, it is necessary that the graphite grains be as small and uniform as possible and have a -C distribution. . Generally, the strands of the wire lobe are less than 1 strand, so the graphite particle size of the sheave material according to the present invention is 100 μm or less, 20 μm or less.
m or more, preferably in the range of 30 to 50 μm, and the distribution of graphite particles is 70/- to 100/-1 and the spheroidization rate is 80
% to 100%.

Furthermore, in the present invention, in order to improve the wear resistance, the base structure of the sheave material is made into a bainite structure by heat treatment, and its hardness is set to a Brinell hardness of HB260 to HB320. This range is the appropriate hardness for the sheave and wire lobe to have an appropriate amount of wear. In addition, it is desirable that the sheave material according to the present invention has high mechanical properties, particularly tensile strength, and good castability.

The sheave material according to the present invention, which minimizes the amount of wear due to sliding contact with the wire lobes, has excellent wear resistance against the wire lobes, and has good mechanical properties, is made by heat treating a material having the following composition. That is,
The material has a weight ratio of C: 2.7 to 3.5%, Si: 2.
0-2.7%, Mn: 0.5-1.0%, P: 0.
03% or less, Si: 0.03% or less, Mg: 0.03~
0.07%, the remainder consisting of Fe and incidental impurities. This material may contain Cu: 0, 3~
0.7%, Ni: 0.2-0.6%, Mo: 0.
2-0. 6% of any I Pli or several species can be added. In that case, it is preferable to add only Cu or to use a combination of Ni and Mo.

The purpose of adding each component and the reason for limiting the composition range will be explained below.

If C exceeds 3.5%, the mechanical properties, especially the bow tension strength, will not exceed the target of 70 kgf/-;
Below this is not preferable because the distribution of graphite particles will not be 70/- or more.

Si is added to improve the spheroidization rate and castability, but S
When the i is 2.7% or more, ferrite is present even after heat treatment, and the hardness decreases, making it difficult to achieve Hv of 200 or more.

If the Si content is less than 2.0%, the spheroidization rate may be less than 80%, the castability deteriorates, and shrinkage cavities, which are undesirable as a sheave, are likely to occur.

If Mn is less than 0.5%, ferrite is more likely to be generated in the center of thick castings during air cooling, resulting in poor wear resistance. On the other hand, if it exceeds 1%, hardened phases tend to segregate at grain boundaries, making it brittle, which is not desirable.

Since P and S reduce the formation of inclusions, it is desirable to reduce them as much as possible. Since the inclusions are hard and irregularly present, they easily scratch the wire lobe. For this reason, the content is preferably 0.03% or less in both cases. If it exceeds 0.03%, inclusions larger than the abrasive grains (Fe 3PSMnS,
MgS, etc.) is generated, which is undesirable.

Mg is an alloying element necessary to make graphite spheroidal, and has a content of 0.
If it is less than 0.03%, the spheroidization rate will not exceed 80%;
If it exceeds 079δ, irregularly shaped graphite will be produced, which is not preferable.

Ni and Cu are elements that make the structure uniform, for example, from the surface to the depth direction, thereby eliminating variations in hardness. Further, Ni has the effect of preventing oxide formation during heat treatment.

NiO, below 2%, these effects are small, and 0,
Adding more than 6% is not very effective in achieving these effects, nor is it economical. On the other hand, like Ni, Cu has little effect on uniformity when it is less than 0.3%;
If more than 100% is added, Cu will segregate in the matrix at the center of the wall thickness, making the structure non-uniform and impairing wear resistance.

Cu is a desirable alloying component for bainiticizing the structure.

Mo is also an element that promotes bainite formation and improves wear resistance. When MO exceeds 0.6%, coarse carbides are formed, which accelerates the wear of the lobe agent.

When heat-treating the above-mentioned composition material, the temperature of the heat treatment must be such that the base structure can be converted to bainite, and the temperature should be between about 850°C and 980°C, preferably around 930°C ± 20°C, and about 60-120°C. It is heated for a minute to form an austenitic structure, and then immersed in a hot bath of nitrate or the like at 300 to 400°C for 30 to 60 minutes, and then left to cool for austempering treatment to form a bainite structure.

The material thus obtained has the above-mentioned hardness and other properties, has excellent wear resistance, and is particularly suitable as a sheave material for elevators.

[Examples and comparative examples]

Example 1 Spheroidal graphite cast iron having the components shown in Example 1 in Table 1 was cast.

The graphite spheroidization rate was 85%, the graphite particle size was 30 to 50 μm, and the graphite particles were distributed at 70 pieces/mtA. This is 9
Heated at 30℃ for about 60 minutes to form an austenitic structure,
After that, it was immersed in nitrate at 340° C. for 1 hour, then allowed to cool and was subjected to austempering treatment to form a bainite structure. Brinell hardness was around H8320. A wear test piece was made from this, and a rolling and sliding wear test was performed by combining it with a material equivalent to wire lobe type A. As a result, the wear characteristics were located on curve l in Figure 1, and the amount of wear was reduced to 1/40 (Comparative Example 1) (1), and showed desirable characteristics as a sheave material with excellent wear resistance (see Table 2).

Example 2 Spheroidal graphite cast iron having the components shown in Example 2 in Table 1 was austenitized at 930°C and then austempered at 370°C to form a bainitic structure.

The graphite spheroidization rate was 90%, the graphite particle size was 30 to 45 μm, the number of graphite particles was 80 pieces/mtA or more, and the hardness was HB300. A wear test piece was made from this, and a wear test was conducted in combination with a material equivalent to wire lobe type A. As a result, the wear characteristics were the first.
It was located on curve 1 in the figure, and the wear amount decreased to 115 (comparative example 1 is set as 1), showing desirable characteristics as a sheave material with excellent wear resistance (see Table 2).

Example 3 Spheroidal graphite cast iron having the components shown in Example 3 in Table 1 was made into an austenitic structure at 930°C, and then subjected to austempering treatment at 400°C to form a bainite structure. Graphite nodularity rate is 8
5%, graphite particle size is 30~508m1 graphite particles are 75 pieces/-
As mentioned above, the hardness was HB260. A wear test piece was made from this, and a rolling and sliding wear test was conducted by combining it with a material equivalent to wire rope type A. As a result, the wear characteristics were located on curve 1 in Figure 1, and the amount of wear was reduced to 1/1.5. (Comparative Example 1 is designated as 1) and exhibited desirable characteristics as a sheave material with excellent wear resistance (see Table 2).

Comparative Example 1 Spheroidal graphite cast iron having the composition shown in the comparative example in Table 1 was cast. The graphite spheroidization rate was 75%, the graphite particle size IQO ~150 μm, and the number of graphite particles was 60 pieces/mtA. This is heated to about 1 at 930℃.
The base was heated for 20 minutes and air cooled to form a ferrite + pearlite structure. The hardness was HB220. After heat treatment, abrasion test pieces were prepared, and as a result of a rolling and sliding abrasion test in combination with a material equivalent to wire lobe A, the results showed that the wear characteristics of each of the above examples were on the wear characteristic curve 1 shown in FIG. The amount of wear was large compared to the wear characteristics of

Comparative Example 2 Spheroidal graphite cast iron having the composition shown in the comparative example in Table 1 was cast. The graphite spheroidization rate was 75%, the graphite particle size was 100 to 150 μm, and the number of graphite particles was 60 pieces/mi. This is heated to 930℃ for about 1
It was heated for 20 minutes, quenched in oil, heated to 500°C for about 200 minutes, cooled in oil, and tempered. Hardness was HB390. From this, a wear test piece was made and the wire lobe A
As a result of performing a rolling and sliding wear test in combination with similar materials, the wear characteristics were as shown in curve 1 in Figure 1, and the amount of wear was 1.
However, as shown in curve 2 in Figure 1, the wear amount of the material equivalent to Lobe A increased by 50 times (Comparative Example 1 was set as 1). (assuming the wear amount of the corresponding material to be 1), which is undesirable because it causes a large amount of wear on the mating material (see Table 2).

/ The wear characteristics of Examples and Comparative Examples are shown in Figure 1, and based on these characteristics, by setting the hardness of the sheave material to HB260-320, the wear of the sheave and wire rope can be relatively balanced. Can be done.

〔Effect of the invention〕

As is clear from the results of the above Examples and Comparative Examples, the sheave material of the present invention has characteristics particularly desirable as a sheave material for elevators in terms of wear amount compared to conventional materials.

Although the present invention has been specifically explained in detail with respect to elevator sheave materials, it goes without saying that the present invention is not limited to such applications and can be effectively applied to cast iron sheaves of other equipment, and in that case, the present invention also applies. It is within the scope of the invention.

Wear characteristics of similar materials.

Claims (1)

[Claims] Spheroidization rate 80%~100%, graphite particle size 20μm~100
μm, number of graphite particles 70 pieces/mm^2 to 100 pieces/mm^2
A sieve material comprising spheroidal graphite cast iron having a Brinell hardness of H_B260 to 320.