JPS5970759A - Sliding contact member in bearing shaft sealing part of revolving shaft for excavation - Google Patents

Abstract

PURPOSE:To improve wear resistance and sealability, by melt spraying an Ni self-fluxing alloy contg. powder of a sintered hard alloy on the surface of a sliding contact member that contacts a sealing member in the shaft seal part adapted to the bearing part of the revolving shaft for excavation of an excavator. CONSTITUTION:The bearing part A of a revolving shaft 2 for excavation used for an excavator which excavates the wear ground in the seabed is constituted of a bearing 3, a housing 4, a sleeve 5, a sealing member 6 and a sliding contact member 7, and a shaft sealing part B is constituted of the member 6 and the member 7 among these members. The abrasion owing to the intrusion of sand, soil, etc. into the part B leads to a loss of the intrinsic shaft sealing function and therefore the melt-sprayed film mixed with 20-80% powder of a sintered hard alloy with an Ni self-fluxing alloy contg. 5-20% Cr, 1-5% B, 1-5% Si or further <1% C, <5% Cu, <5% Mo is formed on the surface of the member 7 in sliding contact with the member 6 to prevent the wear of the member 7 by the material intruded from the sealing part B in the bearing part A, whereby the service life is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shaft seal applied to a bearing of an excavation rotating shaft of an excavator, and particularly to a sliding member with which a seal member abuts in the shaft seal.

For example, an excavation rotation shaft having such a bearing portion is used in a ground improvement device installed in a work boat used for improving soft seabed ground, and the excavation rotation shaft becomes long and multi-axis. For this reason, the shaft is extended in the longitudinal direction through an appropriate number of bearings, and the positions of the respective excavation rotation shafts are maintained through vertical supports and brackets. Then, the excavation rotation shaft is rotated by a rotary drive machine on a work boat to excavate soft seabed ground, and then cloud material is injected through the excavation rotation shaft to solidify the seabed ground.

Therefore, foreign matter such as earth and sand, sludge, cement slurry, or seawater is mixed on the outside of the bearing part of the excavation rotating shaft, and in order to prevent the intrusion of these foreign matters, the bearing part is generally installed as shown in Fig. 1. It has a structure. Here, 1 is an excavation rotation shaft connected to each other via a flange, 2 is an excavation rotation shaft to which a bearing is attached, 3 is a bearing, 4 is a housing, 5 is a sleeve, and 6 is fixed to the sleeve 5 by a fixing band 8. The synthetic comb-based seal member 7 is a sliding contact member, and the main members of the bearing 3, the housing 4, the sleeve 5, the seal member 6, and the sliding member 7 constitute a bearing portion A. Further, 9 is a bracket, and the housing 4
and a column (not shown) are interposed between the shaft and the column to maintain the excavation rotating shaft at a constant distance from the column. 10 has a Q IJ song.

The seal member 6 and the sliding member 7 in the bearing part A constitute a shaft seal part B, and the shaft seal part B mainly prevents foreign matter from entering.

In addition, a cover 11 is appropriately disposed on the shaft sealing part B, and the cover 11 has one end extending around the outer periphery of the housing 4 so as to cover the shaft sealing part, and the other end slidably sealing on the outer periphery of the sleeve 5. The cover 11 may be used to prevent preliminary foreign matter from entering.

However, in conventional shaft seals, high-strength and wear-resistant steel materials (e.g. carbon tool steel) are used for the sliding contact members, but they wear out under the harsh conditions mentioned above. This progressed at an unexpected speed, and as a result, the shaft seal lost its sealing function, causing damage to the excavation rotating shaft, bearing, and other bearing components.

In other words, considering the cause of this problem, when the foreign matter that enters the shaft seal is a particulate hard material, the particulate material is captured by the synthetic rubber seal member, the particulate material becomes abrasive grains, and the sliding contact occurs. It is thought that the sliding surface of the member is ground.

It is also believed that foreign matter such as seawater corrodes the sliding surface of the sliding member, and the combination of these phenomena causes the wear of the sliding member to progress.

Based on the above circumstances, and as a result of extensive experiments and research, the present invention has been developed by applying a thermal spray coating of a nickel-based self-fluxing alloy containing a predetermined amount of cemented carbide powder to the sliding contact surface of the sliding contact member. This was achieved by confirming that a strong coating that is integrated with the material, significantly improved wear resistance, and exceptional coating performance can be obtained.

That is, the present invention provides a shaft sealing section that is composed of a sealing member in a bearing section of an excavation rotating shaft and a sliding contacting member that is in sliding contact with the sealing member. The structure (technical means) is that a thermally sprayed coating of a nickel-based self-fluxing alloy containing

By adopting the above configuration, the present invention has the following excellent effects.

■ Thermal spray coating is strong and integrated with the base material.
The toughness of the sliding contact member itself is improved.

■ The wear resistance of the seal member is significantly improved compared to conventional products. For this reason, although the sealing member is relatively worn, the sealing member is easy to replace and inexpensive, so the overall economic efficiency is improved.

■ The sealing effect at this shaft sealing part is further improved.

That is, the deterioration of the sealing surface is reduced, and if foreign matter enters the sealing member, it is absorbed by the sealing member, so that the sealing surface is always kept in close contact with the sealing surface.

For this reason, there is no need for permanent installation to prevent the grease supplied into the bearing from leaking out to the outside and contaminating the environment.

■ Since it has corrosion resistance, the sliding surface will not be corroded by seawater, etc.

Hereinafter, embodiments of the thermal spray coating will be described in detail.

The nickel-based self-fluxing alloy is applied as a thermally sprayed coating, and a subsequent heat treatment forms a diffusion bonding layer at the interface of the underlying base material, resulting in a strong coating that is integrated with the base material.

The nickel-based self-fluxing alloy used in the present invention has the following component composition (total: 100%) by weight.

Chromium: 5 to 20% Boron: 1 to 5 Ti Silicon = 1 to 5% Nickel: Remaining In addition, the cemented carbide powder is a composite alloy powder in which tungsten carbide fine particles are coated with cobalt.
The composition of the powder is preferably 80 to 95 tuxten carbide and 5 to 20 cobalt. This thing is
It is added in an amount of 20 to 80% to a nickel-based self-fluxing alloy to increase the strength of the coating and contribute to improved wear resistance. Incidentally, when added to a self-fusing alloy in the form of tungsten carbide powder without cobalt coating, tungsten carbide does not melt during thermal spraying, so it is difficult to adhere to the surface of the treated base material, and it is difficult to form. The blending ratio of the powder in the thermally sprayed coating decreases and varies, making it impossible to achieve the desired performance improvement.

In the present invention, in addition to the nickel-based self-fusing alloy having the above-mentioned composition, a self-fusing alloy having a composition consisting of carbon 1 or less, molybdenum 5% or less, and 5% or less is used in addition to the above-mentioned composition. be able to. Carbon forms carbides with other metals, especially chromium, and contributes to improving the hardness of the alloy, but if added in too large an amount, it impairs toughness. Molybdenum and copper are elements that contribute to improving the toughness of the alloy and are effective in forming a relatively thick thermal spray coating.

Generally, in order to impart wear resistance, corrosion resistance, etc., the thickness of the sprayed coating applied to the surface of the base material is usually on the order of 10 microns or 1 to 5 x 102 microns, but in some cases it may be on the order of 1,000 microns. There is a method that is applied as thick as a micron. As the thickness of the coating increases, the effect of the difference in thermal expansion between the base material and the coating becomes more pronounced, which may cause stress cracks in the coating.

Both molybdenum and copper have the function of adjusting the thermal expansion of the nickel-based self-fluxing alloy coating and greatly alleviating the occurrence of such inconveniences. However, if the amounts of molybdenum and copper are increased, the heat treatment workability will be reduced, so the amount should be at most 5%, but usually less.

The nickel-based self-fluxing alloy coating containing the cemented carbide powder of the present invention can be formed by flame spraying or plasma spraying.

In the former case of flame spraying, good results have been obtained by spraying under the following conditions.

(B) Thermal spray gun: Oxygen-acetylene spray gun (B) Oxygen flow rate: 2.7 m/hour (C) Oxygen pressure crab 2.1 kg/i (C) Acetylene flow rate: 1.7 m;/hour (E) Acetylene pressure crab 1.1kg/al Spraying distance: 15-25 cm (g) Alloy powder supply amount = 20-80g/min In the case of the latter plasma spraying, good results were obtained by adopting the following conditions. .

(B) Thermal spray gun: Plasma spray gun (B) Arc gas: Argon (C) Flow rate and pressure crab 5017 minutes, 3.5 to 9/ff
l) Thermal spraying distance near ~ 15 cm (e) Alloy powder supply rate: 20~80g/min The base material used for the sliding contact member of the present invention is a ferrous metal such as carbon steel for machine structures, and the thermal spraying The surface of the base material to which the coating will be applied is made by undercutting the sliding contact area, degreasing the area in a conventional manner, and then roughening it by crit blasting, etc.
The alloy powder described above is immediately thermally sprayed.

The heat treatment of the coating after thermal spraying may be performed by direct heating using an oxyacetylene reducing flame, or may be performed using a reducing furnace such as an ammonia decomposition gas atmosphere. Good results have been obtained by setting the heat treatment temperature to 800°C or higher, usually around 11000C, and the treatment time to 5 to 30 minutes.

(The following is a blank space.) The table shows the performance of the sliding contact member of the present invention in comparison with the conventional Shinayoshi.

(Weight ratio) As can be seen from the table, the amount of wear of the sliding contact portion of the present invention is less than one-tenth that of the conventional product, and it is found that it is resistant to abrasive (rough) wear.

FIG. 3 shows an annular disk-shaped sliding contact member 7' coated with the above-mentioned thermal spray coating. This sliding member 7' is divided into an appropriate number of parts in the radial direction so that it can be easily attached/detached or replaced. Here, 12 is a thermally sprayed coating of a nickel-based self-fluxing alloy containing cemented carbide powder, 13 is an undercut part, and the coating 1
2 is adhered to this undercut portion, and its surface is smoothed by grinding or the like. Hole 4 is a bolt hole for attaching the sliding member 71 to a supporting member such as a housing.

FIGS. 4A and 4B show an embodiment in which a thermal spray coating is applied to the outer periphery of a cylindrical sliding member γ. Here, 12 is a thermal sprayed I, 13 is an undercut portion, and 14 is a bolt hole, which has the same structure and function as the embodiment shown in FIG. This sliding contact member 1 is divided into an appropriate number of parts in the radial direction, and is freely fixed to a support member such as a sleeve with bolts (not shown) through bolt holes 14, and is attached to a seal member 6 fixed to the housing. It makes sliding contact on the vertical surface and has a sealing effect.

According to the structure of this embodiment, there is an effect that expansion and contraction in the longitudinal direction due to heat of the constituent members of the bearing section, for example, the housing 4 or the sleeve 5, can be absorbed by this sliding surface.

In addition, instead of this embodiment, the thermal spray coating 12 can be applied to the sleeve 5.
It is also possible to adopt an embodiment in which it is applied directly to the surface.

[Brief explanation of drawings]

Fig. 1 is a partially sectional side view showing the structure of the bearing part of a general excavation rotating shaft, Fig. 2 is an enlarged sectional view of the shaft seal part, and Fig. 3 is an enlarged sectional view of the shaft sealing part.
Figures (A) and (B) are a plan view and a sectional view showing the structure of an embodiment of the sliding contact member of the present invention, and Figures (A) and (B) are
FIG. 2 is a perspective view showing the structure of another embodiment and an enlarged sectional view of a shaft seal portion. A...Bearing part B...Shaft seal part 1, 2
...Drilling rotation shaft 3...Bearing 6...
... Seal members 7, 7'. γ...Sliding contact member 12...Thermal spray coating Fig. 2 9 Fig. 3 Fig. 4 Continued from page 1 ■Applicant Oiles Industries Co., Ltd. 1-3 Shiba Daimon, Minato-ku, Tokyo No.2 ■Applicant MEX Co., Ltd. 5-6-4 Tsukiji, Chuo-ku, Tokyo

Claims (1)

[Scope of Claims] (1) In a shaft sealing portion comprising a sealing member in a bearing portion of an excavation rotating shaft and a sliding member with which the sealing member slides, a surface of the sliding member with which the sealing member slides; A sliding contact member characterized by being coated with a sprayed coating of a nickel-based self-fluxing alloy containing cemented carbide powder. 2. The sliding contact member according to claim 1, wherein the cemented carbide powder is dispersed in a weight ratio of 20 to 80% based on the nickel-based self-fusing alloy. 3. The nickel-based self-fluxing alloy consists of 5 to 20 parts of chromium, 1 to 5 parts of boron, 1 to 5 parts of silicon, and the remainder nickel in weight ratio. Sliding contact member. 4. The nickel-based self-fusing alloy has a weight ratio of 5 to 20 chromium, 1 to 5% boron, 1 to 5% silicon,
3. The sliding contact member according to claim 1 or 2, which comprises carbon of 1 or less, @5Llb or less, molybdenum of 5% or less, and the remainder of nickel.