JPS6367044B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention provides a system in which a bush is fitted into the inner surface of a housing, and a solid lubricant is embedded in the sliding surface of the bush against the shaft, thereby maintaining a lubricated state without maintenance. The present invention relates to a method of manufacturing such a bearing.

[Background of the invention]

Figure 1 shows this type of conventional bearing, where 1 is a copper alloy bush fitted into the inner surface of the housing;
2 indicates a shaft inserted and supported within the bush 1. On the sliding surface of the bush 1 with the shaft 2,
A plurality of holes 3 penetrating from the inner peripheral surface 1a of the bush 1 to the outer peripheral surface are formed, and each hole 3 has PTEE,
Solid lubricants such as C, M ₀ S ₂ (including those mixed with wax and additives as binders) 4
is embedded.

Conventionally, the above-mentioned bearing is coated with a solid lubricant or a solid lubricant on the inner circumferential surface 1a of the bushing 1 in order to improve conformability at the initial stage (until the inner circumferential surface 1a is lubricated by the solid lubricant 4). It is coated with grease. However, the coating of the solid lubricant or the grease containing the solid lubricant has a weak adhesion strength to the bush, so it easily peels off and cannot serve the intended purpose. As a result, metal contact occurs between the inner circumferential surface 1a of the bush 1 and the shaft 2 at the initial stage, and adhesion tends to occur on the inner circumferential surface 1a.
When adhesion occurs, since the bushing 1 is made of a copper alloy, its ability to repair the adhesion is small, resulting in seizure. Furthermore, even if seizure does not occur, the sticking phenomenon occurs repeatedly, causing premature wear of the bush 1.

[Purpose of the invention]

The purpose of the present invention is to improve the problems of the prior art as described above, to prevent seizure and wear of the bushing at the initial stage, and to improve seizure resistance and wear resistance during operation after the initial stage. The purpose is to provide bearings that can be obtained.

[Summary of the invention]

In order to achieve the above objects, the present invention has the following features:
Before embedding the solid lubricant, a tin film is formed on the inner peripheral surface of the bushing, and then, while the tin maintains its physical properties on the inner peripheral surface, a portion of the tin that comes into contact with the bushing is diffused into the base metal of the bushing. The feature is that a solid lubricant is embedded in the sliding surface of the bush after the bush is subjected to heat treatment.

[Embodiments of the invention]

In the present invention, as shown in FIG. 2, the inner circumferential surface of the bush 11 is
A Sn coating 13 is formed on 1a. This Sn coating 1
Although the method for forming the layer 3 is arbitrary, for example, an electroplating method, a vacuum evaporation method, an ion plating method, a melt plating method, etc. are used. Further, the thickness of the Sn coating 13 is approximately 5 to 10 μm, but is not limited to this range.

When forming this Sn film, if there is a hole in the bush 11 for embedding the solid lubricant, see Figure 2 a.
As shown in FIG. 2, the Sn coating 13a may be formed only on the inner peripheral surface 11a of the bushing by masking 14 in the hole 31, or alternatively, as shown in FIG. Hole 3 from 11a
The Sn coating 13a' may be formed up to the inside of the substrate 1.
Furthermore, the hole 31 for embedding the solid lubricant may be a through hole as shown in FIG. 2a or a hole with a bottom as shown in FIG. 2b. Moreover, since the solid lubricant is not embedded at this point, the Sn coating 13a'' may be applied to a hole that does not have a hole as shown in FIG. 2c.

Next, the bush 11 on which the Sn coating 13 has been formed as described above is placed in a heat treatment furnace 15 as shown in FIG. and hold for each predetermined time. As described below, this temperature and holding time must be controlled within a range where Sn maintains its physical properties on the inner peripheral surface, while a portion of the Sn on the side that contacts the bushing is diffused into the base metal of the bushing. For example, at 350° and 600°C for about 2 hours each.

When the bush on which the Sn film is formed is heat-treated, as shown in Fig. 4, part of the Sn in contact with the bush is thermally diffused into the base metal, which is a Cn alloy, and forms Cu ₃ Sn (δ phase). ) and Cu ₄ Sn (ε phase) is formed on the inner peripheral side of the bushing, and the Sn coating 13 is present on the diffusion layer 11b, so that the bushing 11 has no Sn The coating is bonded extremely firmly, and the inner circumferential surface 11a of the bush 11 is connected to the diffusion layer 11.
hardened by b.

In FIG. 4, solid lines are drawn between the bush 11 and the diffusion layer 11b, and between the diffusion layer 11b and the Sn coating 13, but in reality they are not so clear-cut.

Next, as shown in FIG. 4, a solid lubricant 41 is filled into holes 31 formed at intervals in the bush 11 to complete the product. Incidentally, as shown in FIG. 2c, if holes were not drilled during the formation of the Sn film, the holes should be drilled up to this point.

In the bearing obtained by the present invention, as described above, the inner circumferential surface of the bush 11 is hardened by the diffusion of Sn, and the Sn coating 13 is firmly bonded to the bush through the diffusion layer 11b. Therefore, as described below, there is no risk of seizure or wear during the initial stage, and furthermore, seizure resistance and wear resistance during subsequent operation can be improved.

That is, the contact between the bush and the shaft obtained by the present invention is first the contact between the Sn coating 13 and the shaft 12. As is well known, Sn is a soft metal with high lubricity, so it has good compatibility with the shaft.
In addition, although the contact between the Sn coating 13 and the shaft 12 is a kind of metal contact, the Sn coating has a large repair ability and can repair the adhesion phenomenon, so it is possible to prevent seizure and wear at the initial stage. Moreover, this effect can be easily and reliably achieved because the Sn coating is firmly bonded to the bush.

Furthermore, when the Sn coating 13 wears away after a certain period of time, the temperature of the sliding part has already increased at this point, and a large amount of the solid lubricant 41 is present on the sliding surface with the shaft 12. and hardened diffusion layer 1
1b slides on the shaft 12, and as described above, this diffusion layer 11b has high hardness and therefore has excellent wear resistance, and the presence of Sn in the alloy also improves wear resistance.

Example: Sn is applied to the inner circumference of bushing 11 by electroplating method.
was plated for 1 hour to form a 10 μm thick Sn film. Next, the bush on which the Sn film was formed was placed in a heating furnace and heat-treated at 350°C to 500°C for 5 hours, resulting in Cu ₃ Sn and
A diffusion layer made of Cu ₄ Sn was formed to a depth of 15 μm, and a 5 μm Sn film was present on top of the diffusion layer.

When a bearing using this bushing was used in a hydraulic excavator, there was no seizure or wear at all at the initial stage, and although the Sn coating was worn away after 100 hours, there was a gap between the diffusion layer on the inner peripheral surface of the bush and the shaft. It was confirmed that there was a sufficient amount of solid lubricant in the product and that it achieved good lubrication performance.

〔Effect of the invention〕

As described above, according to the present invention, in a bearing in which a solid lubricant is embedded in the bushing, it is possible to improve the compatibility between the bushing and the shaft at the initial stage, which has traditionally been the most problematic problem, and to prevent seizure at the initial stage. This has the effect of not only preventing wear but also improving seizure resistance and wear resistance after that.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional bearing. Figures 2 to 4 show examples of the present invention; Figure 2 is a sectional view showing the state of Sn coating formation, Figure 3 is an explanatory diagram of heat treatment, and Figure 4 is a sectional view of the completed state. be. 11... Bush, 11a... Bush inner peripheral surface, 11b... Diffusion layer, 12... Shaft, 13...
Sn coating, 15...Heat treatment furnace.

Claims (1)

[Claims] 1. A method for manufacturing a bearing in which a copper alloy bushing is inserted into the inner surface of a housing and a solid lubricant is embedded in the sliding surface of the bushing with the shaft, wherein the inside of the bushing is embedded before the solid lubricant is embedded. A tin film is formed on the circumferential surface, and then heat treatment is applied to the inner circumferential surface so that some of the tin on the side that comes into contact with the bushing is diffused into the base metal of the bushing, while the tin maintains its physical properties. A method for producing a solid lubricant-embedded bearing characterized by embedding a solid lubricant in the sliding surface of the bearing.