JP4902430B2 - Sliding members and bushes for plain bearings - Google Patents

Description

  The present invention relates to a sliding member used for sliding parts of various machines, and a bush for a slide bearing using the sliding member.

  Sliding members are used in parts where members relatively slide such as bearings and gears in various machines (construction machines, civil engineering machines, conveyance machines, heavy machinery, machine tools, automobiles, etc.). Conventionally, as the sliding member, a metal member has been mainly used, but recently, due to technological progress, a resin-based material (resin sliding member) is increasingly used. ing.

  Some sliding members made of resin are made of fiber reinforced resin (FRP) in which a thermosetting resin such as an epoxy resin is used as a base material and is reinforced with glass fiber or the like ( (See Patent Document 1). This type of sliding member is often used at a location that supports a member that moves at a relatively high speed, such as a drive shaft of a rotary machine, and can reduce the load and noise and reduce the weight of the product.

JP 2006-205436 A

  By the way, the environment in which the sliding member is used varies depending on the application location, the use of the machine, and the like, and is required to have performance suitable for the environment. For example, a bearing used for a connecting portion of a boom, an arm, and a bucket constituting a working device of a hydraulic excavator is slid at a lower speed than a shaft that rotates at a relatively high speed such as a drive shaft of a rotary machine In addition, it supports the shaft where high surface pressure is applied.

  Here, when considering application of a resin sliding member as a sliding member to be used at such a low speed and high surface pressure, the above FRP is used in consideration of the fact that strength that can withstand high surface pressure is required. It is possible to do. However, although a sliding member formed of FRP has good strength, it is difficult to say that it has a sliding property that can withstand use under high surface pressure like a bearing of a hydraulic excavator. Therefore, when such a sliding member is used under high surface pressure, there is a high possibility that it will be damaged by frictional heat due to sliding with the counterpart material. On the other hand, if priority is given to slidability, avoiding the use of FRP and using a resin with excellent self-lubricity may cause sudden abnormal wear or deformation (creep phenomenon) due to insufficient strength and hardness. There is.

  An object of the present invention is to provide a resin sliding member that can be used even under high surface pressure, and a bush for a slide bearing using the same.

  (1) In order to achieve the above object, the present invention is a sliding member comprising a fiber reinforced resin layer formed using a resin as a base material on a sliding surface with a counterpart material, and the fiber reinforced resin layer At least a plurality of holes arranged on the sliding surface, a resin held as a sealing material in the plurality of holes, and contained in the resin of the sealing material, which is higher than the resin of the base material And hard particles having hardness.

  (2) The resin of the sealing material of (1) is preferably a resin having higher self-lubricity than the resin of the base material.

  (3) The plurality of pores of the above (1) or (2) are preferably formed by embedding a sublimable substance that sublimates by heating or a foaming agent that foams by heating in the fiber reinforced resin layer. Shall.

  (4) The resin of the base material in any one of (1) to (3) is preferably engineering plastic including PTFE, polyethylene, phenol resin, or a hybrid resin combining these. .

  (5) In order to achieve the above object, according to the present invention, a sliding bearing bush is formed by using any one of the sliding members (1) to (4).

  (6) The bush for a plain bearing according to the above (5) is provided on the radially outer side of the fiber reinforced resin layer, and is made of a resin whose strength is higher than that of the base material resin of the fiber reinforced resin layer. A fiber reinforced resin layer is provided.

  According to the present invention, since it can have slidability and strength, a resin sliding member that can be used even under high surface pressure can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a side view of a hydraulic excavator as an example of a machine in which a sliding member according to an embodiment of the present invention is used.
The hydraulic excavator shown in this figure is provided on a lower traveling body 1, an upper revolving body 2 that is turnably mounted on the lower traveling body 1, and one side (left side in FIG. 1) on the upper revolving body 2. The engine room 4 provided on the other side (right side in FIG. 1) on the upper swing body 2 and the working device 5 provided on the driver room 3 side on the upper swing body 2 are provided. Yes.

  The front work machine 5 is provided on the upper swing body 2 so as to be able to move up and down, a boom hydraulic cylinder 7 for moving the boom 6 up and down, and rotatably provided at the tip of the boom 6. An arm 8, an arm hydraulic cylinder 9 for rotating the arm 8, a bucket 10 rotatably provided at the tip of the arm 8, and a bucket hydraulic cylinder 11 for rotating the bucket 10 It has.

  The boom 6, the arm 8, the bucket 10, and the hydraulic cylinders 7, 9, and 11 are connected to each other by a slide bearing 12 so as to be rotatable. Each bearing used for the front work machine 5 differs in size, shape, etc. depending on the installation location, but the basic configuration is substantially the same.

FIG. 2 is a sectional view of a bearing provided with a sliding member according to an embodiment of the present invention.
In FIG. 2, the plain bearing 12 is provided on a boss 15, a cylindrical sliding member (hereinafter referred to as “bush” as appropriate) 16 fitted in the boss 15, and both sides of the bush 16. An oil shielding member 17, a dust seal 18 press-fitted on both sides of the bush 16 in the boss 15 so as to abut the oil shielding member 17 toward the bush 16, and a bracket disposed on both sides of the boss 15 via a gap. 19, a shim 20 provided in the gap between the bracket 19 and the boss 15, an O-ring 21 mounted on the outer peripheral side of the gap between the bracket 19 and the boss 15, and the bracket 19 and the bush 16 are inserted. The shaft 22 is provided so as to be slidable with the bush 16 and the rotation locking bolt 23 is provided.

  The shaft 22 is made of a steel material. First, after carburizing, nitriding, induction hardening, etc., the outer surface is subjected to chemical conversion treatment using zinc phosphate, manganese phosphate, etc., and various types including diffusion plating. It is preferable to modify the surface by a plating process or a sulfuration process. The rotation locking bolt 23 is provided so as to penetrate the shaft 22 and the bracket 19, and makes the shaft 22 and the bracket 19 non-rotatable. Further, the boss 15 and the bush 16 are fitted and fixed to each other by, for example, shrink fitting such as shrink fitting or cooling fitting. Therefore, the bearing 12 is configured such that the shaft 22 and the bracket 19 rotate relative to the boss 15 and the bush 16 so that the shaft 22 and the bush 16 slide relative to each other.

FIG. 3 is a schematic cross-sectional view of a sliding member according to an embodiment of the present invention.
In FIG. 3, the bush 16 includes a fiber reinforced resin layer (hereinafter referred to as an FRP layer) 30 provided on the sliding surface 25 side (the inner peripheral side of the bush 16) with the shaft 22 that is a sliding counterpart. Yes.

  The FRP layer 30 includes a fiber 31 as a reinforcing material, a base material resin 32 as a base material, a plurality of holes 33, a sealing material resin 34 as a sealing material of the holes 33, and a sealing material resin. 34 is provided with hard particles 35 contained in. Of the FRP layer 30, a layer formed with a predetermined thickness from the sliding surface 25 is a hole layer 40 in which a plurality of holes 33 are provided.

  The fiber 31 is a fiber (for example, glass fiber or carbon fiber) impregnated with the base material resin 32, and is laminated toward the radially outer side while being wound along the axial direction of the bush 16. In order to form a bush with the fibers 31, a filament winding method, a sheet winding method, or the like may be used (detailed later).

  The base material resin 32 is obtained by curing the resin impregnated in the fibers 31 and is disposed so as to surround the fibers 31 from the outside. The base material resin 32 is used to improve the strength of the bushing 16 in combination with the fibers 31, and is made of fluororesin (for example, polytetrafluoroethylene (PTFE)), engineer plastic (for example, ultrahigh molecular weight polyethylene, Polyacetal (POM) or the like), thermosetting resin (for example, epoxy resin, phenol resin, polyimide, or the like), or a hybrid resin that combines these may be used. From the viewpoint of improving the strength of the sliding member, a thermosetting resin that is hard to be softened even when heated after being solidified is particularly preferable.

  The air holes 33 are formed when the fibers 31 are wound to form the bush 16, and are provided so that the concave portions are exposed on at least the sliding surface 25. In order to provide the holes 33 in the bush 16, a sublimable substance that easily sublimes by heating (for example, wax used in the lost wax method), a foaming agent that foams by heating (for example, a synthetic foam material, etc.) ) Is recommended (detailed later).

  The thickness of the layer forming the holes 33 (hole layer 40) from the sliding surface 25 is preferably thick from the viewpoint of extending the life of the slidability, but is as severe as in the present embodiment. When used in the environment, it is better to make it thinner by giving priority to the enhancement of mechanical strength. This is because, if the pore layer 40 is made thin, a layer made of FRP alone can be formed on the radially outer side of the layer 40 (the direction opposite to the sliding surface 25), so that the mechanical strength of the bush is improved. For example, when priority is given to enhancing the mechanical strength with a bush having an outer diameter of 80 to 90 mm and an inner diameter of 65 to 75 mm, the pore layer 40 may be set to about 0.3 to 1.0 mm.

  The diameter of the air holes 33 is preferably in the range of at least 2 μm to 100 μm. When the diameter is less than 2 μm, it becomes practically difficult to obtain the self-lubricating property (described later) of the sealing resin 34, and when it exceeds 100 μm, there is a problem in strength when used at a low speed and high surface pressure. Because. Needless to say, when adjusting the diameter of the air holes 33, the diameters of the sublimable substance and the foaming agent may be adjusted.

  The sealing material resin 34 is a sealing material that is held in the plurality of holes 33, and also serves as a binder (binder) that fixes the hard particles 35 to the base material resin 32. Thus, if resin is used as the sealing material for the air holes 33, the slidability of the bush 16 can be improved by the lubricity of the resin. However, from the viewpoint of further improving the slidability of the bush 16, it is preferable to use a resin having higher self-lubricating property than the base material resin 32 as the sealing material resin 34. In particular, from the viewpoint of improving strength and slidability, a thermosetting resin (for example, epoxy resin) containing a resin having good lubricity such as PTFE is preferable. As described above, if the sealing material resin 34 having high lubricity is used, these adhere to the mating material (shaft 22) during sliding and act as a lubricant. Can be improved.

  The hard particles 35 contribute to the wear resistance of the sliding member, and are contained in the sealing material resin 34 in a predetermined amount (for example, 2 to 50 mass%). As means for improving the wear resistance of the bush 16, there is a method of improving the hardness of the base material itself of the bush 16, but if the hardness of the base material is improved more than necessary, the wear amount of the shaft 22 which is the counterpart material is increased. May be increased. Therefore, in the present embodiment, in order not to increase the hardness of the base material itself of the bush 16 more than necessary, the hard particles 35 are added to the sealing material resin 34 to improve the wear resistance of the bush 16. ing. The hard particles 35 are required to have at least a hardness higher than that of the base material resin 32 from the viewpoint of suppressing the wear of the bush 16, for example, HSS, tungsten carbide, chromium carbide, ceramic, etc. having a hardness of Hv 800 or higher. It is good to use. Moreover, as a ratio which adds the hard particle | grains 35 to the sealing material resin 34, the range of 5-20 mass% is preferable. This is because when the ratio of the hard particles 35 is 5 mass% or less, the effect of reducing the amount of wear due to the addition of the hard particles 35 is small, and when it exceeds 20 mass%, the contact area between the hard particles 35 and the shaft 22 increases. This is because it is difficult to obtain a reduction effect. Moreover, it has been confirmed that the addition of the hard particles 35 in the range of 5 to 20 mass% not only reduces the amount of wear but also has an effect of extending the life of the bush 16. The range is considered to be optimal.

  The hard particles 35 have different performances depending on the amount added to the sealing material resin 34. In general, increasing the addition amount of the hard particles 35 tends to improve the abrasive wear resistance, and reducing the addition amount tends to improve the sliding property under high surface pressure. Therefore, by adjusting the addition amount according to the use environment of the bearing, a bush having performance suitable for the use environment can be obtained. When the use in a dust environment is premised, as in the case of the hydraulic excavator used in the description of the present embodiment, the amount of addition of the hard particles 35 is set to be relatively large in order to improve the abrasive wear resistance. It is preferable to do. As a result, wear due to dust can be reduced, and dust resistance is improved.

  Next, the manufacturing method of the bush 16 comprised as mentioned above is demonstrated.

  In order to manufacture the cylindrical bush 16 in the present embodiment, a fiber 31 impregnated with a base material resin 32 is wound around a mandrel (not shown) having a diameter substantially equal to the inner diameter of the bush 16. The filament winding method (FW method) for forming the bush is used. In addition, a sheet winding method (SW method) in which a fiber sheet such as a knitted fabric is impregnated with a resin (prepreg) is wound around a core metal.

  When the bush is manufactured by the above method, the portion that comes into contact with the cored bar becomes the sliding surface 25. Therefore, when the fiber 31 is wound around the cored bar, preparation for providing the hole layer 40 is required. For this purpose, first, when the fiber 31 is wound around a cored bar, a sublimable substance that easily sublimes by heating (for example, wax used in the lost wax method) or a foaming agent that foams by heating (for example, Synthetic foam material or the like is sprayed, and these are embedded between the fibers 31. By continuing this, when the winding thickness of the fiber 31 reaches the desired thickness of the pore layer 40, the spraying of the sublimable substance or the foaming agent is stopped. Thereafter, only the fiber 31 impregnated with the base material resin 32 is continuously wound, and when the outer shape of the bush 16 is formed, the winding of the fiber 31 is finished. In addition, when not only the inner peripheral side of the bush 16 but also the outer peripheral side is used for sliding with the counterpart material, and it is necessary to provide the hole layer 40 also on the outer peripheral side, the same procedure as described above. Thus, a hole layer 40 having a desired thickness may be provided immediately before the end of winding of the fiber 31.

  When the outer shape of the bush 16 is completed in this way, it is heated to the FRP molding temperature and cured. At this time, since the sublimable substance and the foaming agent embedded between the fibers 31 are sublimated and foamed, holes 33 are formed in the bush 16. As described above, since the holes 33 need to be formed when FRP is molded, it is necessary to select a sublimation substance and a foaming agent having a sublimation temperature / foaming temperature equal to or lower than the FRP molding temperature.

  When the air holes 33 are formed in the bush 16 in this way, the bush 16 is cooled and removed from the cored bar, and the process proceeds to the impregnation step with the sealing material resin 34. The sealing material resin 34 to be impregnated is mixed with a desired amount of hard particles 35 in advance, and the bushing 16 is immersed in the sealing material resin 34 and left in a vacuum atmosphere. As a result, air is easily removed from the air holes 33 of the bush 16 and the impregnation action of the air sealing material 34 is promoted, so that the air sealing material 34 mixed with the hard particles 35 is replaced with the air holes inside the bush 16. Up to 33 can be impregnated. When the impregnation treatment is finished, the bush 16 is taken out and heated to the curing temperature of the sealing material resin 34. Thereby, the sealing material resin 34 and the hard particles 35 can be fixed in the air holes 33.

  After fixing the sealing material (sealing material resin 34, hard particles 35) to the air holes 33 in this way, the bush 16 is cooled and subjected to processing of the inner diameter and outer diameter of the bush 16 as necessary. The bush 16 is completed. In addition, although the manufacturing method of the 1 piece bush which laminates | stacks a FRP layer continuously with the void | hole layer 40 was demonstrated above, at least the components formed to the void | hole layer 40 made from FRP, the product made from a steel plate, etc. Of course, the cylindrical part may be press-fitted into a two-piece bush to further increase the strength.

  In addition, although the manufacturing method of the 1 piece bush which laminates | stacks a FRP layer continuously with the void | hole layer 40 was demonstrated above, the fiber reinforced resin layer 30 is at least to the void | hole layer 40 from a viewpoint of ensuring slidability. If it forms, it is enough. Therefore, a bush may be configured by laminating a high-strength layer made of a material higher in strength than the base material resin 32 on the radially outer side of the pore layer 40 (fiber reinforced resin layer 30). For this high-strength layer, for example, an FRP material having a higher strength resin than the base material resin 32 as a base material, a metal material, or the like can be used. As a method of laminating the high-strength layer, a method in which the fiber-reinforced resin layer 30 is press-fitted after the high-strength layer is formed, or the fiber of the base material is replaced with a high-strength material after the fiber-reinforced resin layer 30 is formed, and further fiber It is preferable to use a method in which a high strength layer is laminated by winding the wire.

  Next, the operation and effect of the present embodiment will be described.

  The sliding member made of resin is a good sliding member that can reduce noise and reduce the weight, but at low speeds and high surface pressures that expose the bearings of hydraulic excavators as described above. It is difficult to use. For example, a sliding member made of FRP has good strength but lacks slidability, so when used under high surface pressure, there is a high possibility that it will be damaged by frictional heat due to sliding with the counterpart material. . On the contrary, avoiding the use of FRP to give priority to slidability and using a resin with excellent self-lubricating properties causes sudden abnormal wear and deformation (creep phenomenon) due to insufficient strength and hardness. End up. Thus, in order to use the sliding member formed of resin in a severe environment of low speed and high surface pressure, it is required to have both mechanical strength and sliding property.

  In contrast, the sliding member according to the present embodiment includes a plurality of holes 33 arranged on the sliding surface 25 of the FRP layer 30 and a sealing material resin 34 held in the plurality of holes 33. And hard particles 35 contained in the sealing material resin 34. According to the sliding member of the present embodiment configured as described above, the sealing material in the air holes 33 is maintained while maintaining the mechanical strength of the sliding member by the FRP formed by the fibers 31 and the base material resin 32. The resin 34 can exhibit slidability. Thereby, since slidability and intensity | strength can be comprised, a resin-made sliding member can be utilized also in the severe use environment under what is called low speed and high surface pressure. Therefore, it is possible to provide a sliding member that can be used without lubrication for a long period (for example, several years) and can reduce noise generated during sliding.

  In addition, self-lubricating materials such as the sealing resin 34 and the like are generally said to have low dust resistance, which is sand or dust that has entered between the shaft and the bush (dust). This is because the sliding surface is worn while moving on the sliding surface. In order to suppress such wear of the sliding surface due to dust, the sliding member of the present embodiment has hard particles 35 held by the sealing material resin 34 and fixed on the sliding surface 25. ing. When the hard particles 35 are fixed on the sliding surface 25 in this way, the hardness of the sliding surface 25 is increased by the hard particles 35 and the wear resistance against dust entering the sliding surface 25 is improved. Can be suppressed. Therefore, according to the sliding member of the present embodiment configured as described above, the dust resistance performance of the sliding member can be improved.

  By the way, in order to improve the slidability of the sliding surface, a hard film may be separately provided or a solid lubricant may be added. However, if it is continuously used, the effect decreases with wear. On the other hand, the sliding member of the present embodiment is a layer in which the sealing material resin 34 contributing to lubricity and the holes 33 holding the hard particles 35 contributing to wear resistance are gathered, and the sliding member A hole layer 40 having a predetermined thickness from the surface 25 is provided. Since the hard particles 35 are held in the holes 33 of the hole layer 40 by the above-described method such as vacuum impregnation, the progress of wear of the sliding surface 25 can be suppressed. Even if the wear of the sliding surface 25 proceeds, the wear rate of the sliding surface 25 can be reduced by the self-lubricating property of the sealing material resin 34. Therefore, according to the sliding member of the present embodiment, the sealing material resin 34 and the hard particles 35 can be present on the sliding surface 25 until the void layer 40 disappears even if wear progresses. Therefore, slidability can be maintained for a long time.

  In the present embodiment, since the pores 33 are formed by spraying a sublimation substance or the like on the fibers 31, the arrangement and ratio of the pores 33 can be controlled. By controlling the arrangement and ratio of the holes 33 in this manner, a portion where the sealing material resin 34 and the hard particles 35 are exposed can be provided on the sliding surface 25, and these appear on the sliding surface. Since the ratio can be adjusted, a sliding member with a small quality difference can be manufactured stably.

  In the above description, the bushing for a hydraulic excavator used at low speed and high surface pressure has been described, but a sliding member used in other environments (for example, a rotating machine used at high speed and low surface pressure) Of course, it can also be used for bearing bushes.

The side view of the hydraulic shovel which is an example of the machine in which the sliding member which is embodiment of this invention is used. Sectional drawing of the bearing provided with the sliding member which is embodiment of this invention. The schematic diagram of the cross section of the sliding member which is embodiment of this invention.

Explanation of symbols

12 Slide bearing 16 Bush 22 Shaft (partner material)
25 Sliding surface 30 Fiber reinforced resin layer 31 Fiber 32 Base material resin 33 Hole 34 Sealing material resin 35 Hard particle 40 Hole layer

Claims (6)

A sliding member comprising a fiber reinforced resin layer formed of a resin as a base material on a sliding surface with a counterpart material,
A plurality of holes arranged on at least the sliding surface of the fiber reinforced resin layer; and
A resin held as a sealing material in the plurality of holes;
A sliding member comprising: hard particles contained in the resin of the sealing material and having a hardness higher than that of the resin of the base material. The sliding member according to claim 1,
The sliding member characterized in that the resin of the sealing material is a resin having higher self-lubricating property than the resin of the base material. The sliding member according to claim 1 or 2,
The sliding member, wherein the plurality of holes are formed by heating a sublimable substance that sublimates by heating or a foaming agent that foams by heating in the fiber reinforced resin layer. In the sliding member in any one of Claim 1 to 3,
The sliding member, wherein the hard particles are high speed, tungsten carbide, chromium carbide, or ceramic. In the sliding member in any one of Claim 1 to 4,
The sliding member characterized in that the resin of the base material is PTFE, engineering plastics such as polyethylene, phenolic resin, or a hybrid resin combining these.   A bush for a sliding bearing using the sliding member according to any one of claims 1 to 5.

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