JP2016020709A - Slide bearing and its process of manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new slide bearing which is manufactured at low cost and is capable of realizing a superior wear resistance for a long period of time and its process of manufacture.SOLUTION: Projection particles 300 having particulate hard carbide 230 adhered to the surfaces of carriers 310 are generated, the projection particles 300 are projected at high speed against a sliding surface 200 to form minute irregularity 220 and at the same time the particulate hard carbide 230 is buried there, and then the sliding surface 200 is heat treated to cause the hard carbide 230 to be diffused and connected to the sliding surface 200. With this processing, its surface is plastic hardened to realize superior wear resistance and shows no possibility of peeling. Further, since they can be formed through shot-peening, their manufacturing cost becomes less-expensive.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a slide bearing generally used for various machines, and particularly suitable for a place where a high surface pressure, low speed sliding and severe lubrication conditions are required such as a slide bearing of a construction machine represented by a hydraulic excavator. The present invention relates to a slide bearing and a manufacturing method thereof.

  Generally, a construction machine such as a hydraulic excavator is provided with a large number of slide bearings used under high surface pressure and low speed sliding conditions. For example, as shown in FIG. 8, a conventional excavator 500 has a structure in which an arm 520 is connected to the tip of a boom 510 extending from the vehicle body, and a bucket 530 is rotatably connected to the tip of the arm 520. Each of the hydraulic cylinders 540, 550, and 560 is rotatably driven by expansion and contraction. The boom 510, the arm 520, the connecting portion of the bucket 530, the end portions of the hydraulic cylinders 540, 550, and 560 are pivotally supported via slide bearings 570, respectively.

  In the conventional slide bearing 570 used in such a portion, during excavation work, an extremely large surface pressure is applied to the sliding surface between the bush and the shaft portion constituting the slide bearing 570 and both slide at a low speed. Therefore, the contact surface (sliding surface) between the bush and the shaft portion has severe lubrication conditions and is liable to cause seizure, galling, uneven wear, etc. due to running out of lubricating oil such as grease.

  Therefore, for example, as in Patent Document 1 below, it is conceivable to prevent seizure due to running out of lubricating oil, galling, uneven wear, and the like by employing a bearing made of a high viscosity oil impregnated sintered alloy containing hard particles.

Japanese Patent No. 3342972

  However, in the technique as shown in Patent Document 1, hard particles may fall off or peel off, and the durability is not sufficient. Moreover, there is a possibility that the hard particles may fall off or wear suddenly as soon as they are peeled off. For this reason, it is conceivable to apply hard plating or thermal spraying to the sliding surface. However, since these techniques are over-spec and require a long processing time, the cost is high and the burden on the environment is large.

  Accordingly, the present invention has been devised to solve these problems, and its purpose is to provide a novel plain bearing that can exhibit excellent wear resistance over a long period of time and that is inexpensive to manufacture. A manufacturing method is provided.

  In order to solve the above-mentioned problems, a first invention is a plain bearing characterized in that a sliding surface has minute irregularities by shot peening and has a film in which particulate hard carbides are diffusion bonded. According to such a configuration, since the sliding surface has a thin hard carbide film together with minute irregularities (micro dimples), the surface is plastic-cured and at the same time exhibits excellent wear resistance. . Moreover, since this hard carbide film is a thin film, there is no fear of peeling. Further, since the minute irregularities and the hard carbide film are formed by shot peening, the manufacturing cost is also low.

  A second invention is the plain bearing according to the first invention, wherein the particulate hard carbide is a metal carbide. According to such a configuration, a thin and strong hard metal film can be formed.

A third invention is the plain bearing according to the second invention, wherein the metal carbide is one or more of WC, Mo ₂ C, TiC, NbC, VC and ZrC. According to such a configuration,

  According to a fourth aspect of the present invention, there is provided a projection particle generation step for generating a projection particle in which a particulate hard carbide is attached to the surface of a particulate carrier, and the projection particle generated in the projection particle generation step is rapidly applied to a sliding surface. A shot peening process for projecting with a shot peening process for forming minute irregularities on the sliding surface and embedding the particulate hard carbide, and heat-treating the sliding surface after the shot peening process to form the particulate hard And a heat treatment step of diffusion bonding the carbide to the sliding surface.

  According to such a manufacturing method, as in the first aspect of the invention, a sliding bearing having excellent wear resistance having a thin hard carbon carbide film with fine irregularities (micro dimples) on the sliding surface can be easily and inexpensively. Can be manufactured.

  According to a fifth aspect of the present invention, in the fourth aspect of the invention, any one of carburizing, gas soft nitriding, and induction hardening is used as the heat treatment. By using such a heat treatment, the particulate hard carbide embedded in the surface can be surely diffusion bonded within the sliding surface.

  According to the present invention, since the sliding surface has a thin strong hard carbide film together with minute irregularities (micro dimples), the surface thereof is plastic-cured and at the same time exhibits excellent wear resistance. Moreover, since this hard carbide film is a thin film, there is no fear of peeling. Further, since the minute irregularities and the hard carbide film are formed by shot peening, the manufacturing cost is also low.

1 is a longitudinal sectional view showing an embodiment of a plain bearing 100 according to the present invention. It is an expanded sectional view showing sliding surface 200 of slide bearing 100 concerning the present invention. It is process drawing which shows the flow of the manufacturing method of the sliding bearing 100 which concerns on this invention. FIG. 6 is a schematic diagram showing a projected particle 300. It is a block diagram which shows an example of the projection apparatus. It is a conceptual diagram which shows the state which is projecting the projection particle | grains 300 on the sliding surface 200 using the projection apparatus 400. FIG. It is a schematic diagram which shows the diffusion bonding by the heat processing in a projection word. 1 is an overall view showing a construction machine (hydraulic excavator) 500 to which a sliding bearing 100 according to the present invention can be applied.

  Next, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a longitudinal sectional view showing an embodiment of a plain bearing 100 according to the present invention. Reference numeral 10 in the figure denotes a cylindrical bush having both ends opened. A cylindrical shaft portion 20 is rotatably inserted into the shaft hole of the bush 10 so as to penetrate the bush. The inner peripheral surface of the bush 10 and the outer peripheral surface of the shaft portion 20 are in contact with each other and slide at a low speed (for example, 3.0 m / min or less) under high surface pressure (for example, several MPa to several tens of MPa). It is a sliding surface.

  The bush 10 is further fitted inside the boss 30, and dust seals 40, 40 are pressed into both ends of the bush 10 inside the boss 30. Blocking intrusion. Further, brackets 50 and 51 are provided on both end faces of the boss 30, and shims 52 and 52 are interposed in the respective gaps. Then, O-rings 53 and 53 are respectively mounted outside the upper ends of the gaps. The boss 30 and the bush 10 can be fitted and fixed to each other by any method known to those skilled in the art, for example, shrink fitting such as shrink fitting or cooling fitting.

  The shaft portion 20 is positioned so as to penetrate the brackets 50 and 51 at both ends, and one end thereof is non-rotatably locked by a rotation locking bolt 60 that penetrates the one bracket 51 in the radial direction. Further, a grease supply passage 70 penetrating from one end surface side to the side portion is formed in the shaft portion 20, and the grease G is filled in the grease supply passage 70. Further, a grease nipple 80 is screwed to one end of the grease supply passage 70, and the inside of the grease supply passage 70 is sealed by the grease nipple 80. The grease G can be easily supplied. The grease G filled in the grease supply passage 70 reaches the sliding surface side between the shaft portion 20 and the bush 10 from the outlet and acts to lubricate the sliding surface.

  FIG. 2 is an enlarged cross-sectional view showing the structure of the sliding surface 200 of the bush 10 or the shaft portion 20. As shown in the figure, the sliding surface 200 has a plurality of minute irregularities (micro dimples) 220 formed by shot peening on the surface of a base material (steel) 210 containing iron as a main component, and particulate hard carbide on the surface thereof. 230 exists in an embedded state. The hard carbide 230 is diffusely bonded from the surface into the base material 210 to form a thin hard carbide film 240.

  Here, the size and depth of the unevenness 220 are not particularly limited, but are, for example, about 10 μm to 100 μm. Further, the thickness of the hard carbide coating 240 is not particularly limited, and is, for example, about several μm to several tens of μm.

As the particulate hard carbide 230, a metal carbide having a very high hardness, specifically, WC (tungsten carbide) HV1000 or more, Mo ₂ C (molybdenum carbide), TiC (titanium carbide), NbC (niobium carbide). VC (vanadium carbide), ZrC (zirconium carbide), or the like can be used. And any 1 type or 2 types or more of these metal carbides can be mixed and used. The size is about several μm to 20 μm.

  FIG. 3 shows a flow of a method for manufacturing such a sliding surface 200. As shown in the drawing, first, the projected particles 300 as shown in FIG. 4 are generated in the first step S100. The projection particle 300 is a particle having a high-mass particle 310 as a carrier and adhered around the particle-like hard carbide 230 as described above. For example, the projection particle 300 is attached to a pressure vessel 410 as shown in FIG. These particles 310 and 230 are obtained by mixing and stirring. Here, the high-mass particles 310 are sufficiently larger than the particulate hard carbide 230, for example, 10 to 100 μm in particle size, that is, glass beads or high speed (steel balls) having almost the same size as the minute irregularities 220. A material that is inexpensive, easy to process, and has a relatively large kinetic energy is used.

  Next, as shown in step S102 of FIG. 3, the projected particles 300 are sprayed onto the surface of the sliding surface 200 at high speed (shot peening). This shot peening can be performed using a projection apparatus 400 as shown in FIG. The projection device 400 throws high-mass particles 310 and particulate hard carbides 230 constituting the projection particles 300 into a pressure vessel 410 and blows a flow control gas into the inside thereof. At this time, by placing the rubber ball G in the pressure vessel 410, the inside is agitated and the high-mass particles 310 and the particulate hard carbide 230 are mixed well, and the surface of the high-mass particles 310 is particulate hard. Good quality projection particles 300 with carbides 230 uniformly attached can be obtained.

  The projected particles 300 in the pressure vessel 410 are sent to the nozzle 430 through the hose 420 together with the flow rate control gas by a constant amount by the flow rate control gas. As shown in FIG. At the same time, it is jetted at a high speed and sprayed onto the sliding surface 200 of the bush 10 or the shaft portion 20. Then, the projected particles 300 sprayed on the sliding surface 200 vigorously collide with the surface of the sliding surface 200 of the bush 10 or the shaft portion 20 due to the high kinetic energy of the high mass particles 310 as shown in FIG. Then, the fine irregularities 210 are plastically formed on the surface, and at the same time, the particulate hard carbide 230 adhering to the periphery remains embedded so as to bite into the surface.

  Next, if such a shot peening process is performed, the process proceeds to step S104, which is the last step, and the bush 10 or the entire shaft portion 20 including the sliding surface 200 is carburized, gas soft-nitrided, or induction-fired. A known heat treatment such as pouring is performed. As a result, as shown in FIG. 7, the particulate hard carbide 230 remaining so as to be embedded in the surface of the sliding surface 200 diffuses into the base material 210 and is firmly bonded to the surface to form a thin film. A strong hard carbide film 240 can be formed.

  In the sliding surface 200 having such a configuration, the surface is plastic-cured by forming minute irregularities 220 on the surface, and at the same time, has a thin strong hard carbide film 240. Therefore, it exhibits excellent wear resistance. Further, since the hard carbide film 240 is a thin film, it can be maintained for a long time without fear of peeling. Furthermore, since the minute unevenness 220 and the hard carbide film 240 can be easily formed by shot peening as described later, the manufacturing cost is lower than that of hard plating or thermal spraying.

  Since the sliding surface 200 of the bush 10 or the shaft portion 20 shown in FIG. 1 is a curved surface, a dedicated jig for holding this is prepared at the time of shot peening, and the nozzle 430 is provided. On the other hand, operations such as rotating the bush 10 or the shaft portion 20 are performed simultaneously so that the sliding surface 200 is always positioned at a right angle. In addition, when shot peening is performed on the inner surface of the bush 10, the shape of the nozzle 430 is of course changed as appropriate so as to enter the bush 10.

10 ... Bush (metal sintered body)
DESCRIPTION OF SYMBOLS 20 ... Shaft part 100 ... Slide bearing 200 ... Sliding surface 210 ... Base material 220 ... Minute unevenness (micro dimple)
230 ... Particulate hard carbide 240 ... Hard carbide coating 300 ... Projection particle 310 ... High mass particle (carrier)
400 ... Projection device 430 ... Nozzle 500 ... Construction machine (hydraulic excavator)
G ... Rubber ball

Claims (5)

  A sliding bearing characterized in that a sliding surface has a fine unevenness caused by shot peening and a coating in which particulate hard carbide is diffusion-bonded. The plain bearing according to claim 1,
The sliding bearing, wherein the particulate hard carbide is a metal carbide. The plain bearing according to claim 2,
A sliding bearing characterized in that the metal carbide is any one or more of WC, Mo ₂ C, TiC, NbC, VC, ZrC. A projected particle generating step for generating projected particles in which particulate hard carbide is adhered to the surface of a particulate carrier;
A shot peening process for projecting the projected particles generated in the projected particle generating process on the sliding surface at a high speed to form minute irregularities on the sliding surface and embedding the particulate hard carbide,
And a heat treatment step of heat-treating the sliding surface that has undergone the shot peening step and diffusion-bonding the particulate hard carbide to the sliding surface. In the manufacturing method of the plain bearing of Claim 4,
As the heat treatment, any one of carburizing, gas soft nitriding, and induction hardening is used.

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