JPS62215123A - Sliding bearing and its process - Google Patents

Abstract

PURPOSE:To enable a sliding bearing to be manufactured into a light-weight and high-precision structure at a low cost, and improved in its frictional property by making up a bearing member, which is provided with projections on its outer surface, from a flurocarbon resin, and then providing, on the outside of the bearing member, a bearing base material, which uses a synthetic resin having a melting point lower than that of the bearing member. CONSTITUTION:On the outside of a bearing member 12, which is provided, on its outer surface, with annular or non-annular projections 12a made from a fluorocarbon resin, or PTFE or the like, having a low coefficient of friction, is provided a bearing base material 11, which is made from a synthetic resin, such as PPS or the like, having a melting point lower than that of said raw material and a sufficient mechanical strength. For the manufacture of this device, first of all, a bearing member 12 is injection molded, and then, it is placed in core 13 having a reference circumferential surface, and further, on a female mold 14 for the bearing base material 11, which has a resin injection space 14b corresponding to the shape of the bearing base material 11, is put a male mold 15 for the bearing base material 11, and finally, resin is injected through a resin injection passage 15b into the resin injection space 14b so that the device is injection molded. Thereby, a sliding bearing can be manufactured into a light-weight structure at a low cost, and the accuracy can easily be improved so as to improve its frictional property.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a sliding bearing that supports a shaft that rotates and reciprocates, and a method for manufacturing the same.

"Prior art and its problems" This type of sliding +lt+I+ bearing is widely used in various parts of vehicles including engines and various hydraulic equipment. On the inside of the material,
Efforts are being made to integrate low-friction bearing systems. Conventionally, this bearing member was usually made of a bimetallic material, which was made by sintering metal such as copper on the surface of the bearing base material, which was made of a backing metal, and then impregnating and firing a low-friction resin on top of the sintered metal. . However, this conventional sliding bearing has problems not only in that the manufacturing process is complicated, but also in that it is difficult to increase its dimensional granularity.

On the other hand, the sliding bearing proposed in European Publication EP 735968 has a plurality of annular protrusions and grooves formed on the inner surface of the bearing base material, and a sheet of fluororesin material on the inner surface of the bearing base material. By inserting a forming jig having a heated reference cylindrical surface into the inner side of the sheet, the sheet is plastically deformed to bite into the groove of the bearing base material. It has the advantage of excellent integration with the bearing base material. However, this plain bearing must be formed from a metal material because the bearing base material must also be heated during manufacture, and therefore machining including annular protrusions and grooves is essential. High cost. In addition, it cannot sufficiently meet recent demands for weight reduction. In addition, looking at the manufacturing process, it is difficult to accurately position the sheet made of fluororesin material on the inner surface of the bearing base material, and the conditions for passing the heated molding jig inside the sheet are also difficult. contains problems.

"Purpose of the Invention" The purpose of the present invention is to obtain a sliding bearing that can solve the problems of conventional sliding bearings at once, has a simple manufacturing process, has low processing costs, and is lightweight. shall be.

"Summary of the Invention" As a result of reconsidering the common knowledge that the bearing base material of a sliding bearing must be made of a metal material, the present invention found that there is no problem in constructing it from a synthetic resin material. This was done with the idea that processing costs would be low, weight could be reduced, and the shape of the bearing could be freely selected. That is, the sliding bearing of the present invention is characterized in that the bearing member that constitutes the sliding portion with the shaft is made of a fluororesin material, and the bearing base material is made of a synthetic resin material whose melting point is lower than that of the fluororesin material. It is something.

In addition, the method of the present invention proposes a method for manufacturing the above-mentioned sliding bearings efficiently and with high particle size.As for the fluororesin material, it is first formed as a bearing member by any method, and the bearing member is The member is fitted onto the outer periphery of the core so that its inner sliding surface is in close contact with the reference cylindrical surface of the core, and a resin material having a melting point lower than that of the bearing member is molded on the outside of the core to form a bearing base material. It is characterized by the fact that By heating the core at the same time as forming the bearing member, the shape of the reference cylindrical surface of the core can be transferred to the bearing member, and an accurate sliding diameter can be obtained.

"Embodiments of the Invention" The present invention will be described below with reference to illustrated embodiments. Figure 1 shows
This figure shows the completed state of the sliding bearing of the present invention, in which a bearing member 12 is integrated with the inner surface of a bearing 11. The bearing member 12 whose inner surface is a sliding surface is made of a low-friction fluororesin material.
It is made of a resin material that has a lower melting point and has the mechanical strength as a bearing base material.

As such a resin material, the bearing member 12 is first made of P.
TFE, PI'Δ, l1TF8 or FEP alone,
Alternatively, the bearing base material 11 may be composed of polyphenylene cellulite (pps), polybutylene terephthalate (
PBT), polyamide resin materials, polyimide resin materials, aromatic polyester resin materials (for example, product name Coconol), polyether resin materials, polyether resin materials, polyetherimide resin materials, polysulfone resin materials (IIEs, PSF), a polyolefin resin material, or a phenol resin material alone or a mixture of these and a filler, which satisfies the condition of "double melting point" can be used.

- Fillers mentioned in 2 are organic fibers such as glass fibers, carbon fibers, alumina fibers, and aromatic polyamide fibers, fibrous materials such as metal fibers, and granular particles such as glass beads, carphone, silica, and talc. , or Fluffite,
It is possible to use flaky particles such as mica.

An annular or non-annular protrusion 12a may be formed on the outer surface of the bearing member 12 for the purpose of increasing the integrity with the bearing base material 11. In order to prevent the bearing base material 11 from rotating, the protrusion 12a is formed into a shape other than an annular shape. As shown in FIG. 2, the inner surface of the bearing member 12 may be made flat, and the upper and lower ends thereof may be pressed by the bearing base material 11.

FIGS. 3 and 4 show a manufacturing method according to the present invention for manufacturing the above-mentioned flat bearing.

First, the bearing member 12 is prepared by first forming it into a cylindrical shape as shown in FIG. Although the method of molding the bearing member 12 is not limited, it is generally difficult to injection mold a fluororesin material. Therefore, it can be made by, for example, sintering powder, machining, or the like. When forming the protrusion 12a, it can be formed by cutting or rolling.

The above bearing member 12 is fitted onto the outer periphery of the core 13 having the reference cylindrical surface 13a. The core 13 is a bearing base material lower mold 1
It can be slid within the sliding hole 14a of No. 4, and is heated by a heating device (not shown). The lower bearing base mold 14 has a resin injection space 14b corresponding to the shape of the bearing base 11, and a second bearing base mold 15 is placed on the lower bearing base mold 14. The bearing base material lower mold 15 is
There is a shape defining surface 15a that closes the upper opening of the lower bearing base mold 14 and defines the two-sided shape of the bearing base 11. The lower bearing base mold 15 has a resin inlet passage 15b that opens on the shape defining surface 15a and communicates with the resin injection space 14b, from which a resin material having a lower melting point than the bearing member 12 is injected. Ru.

That is, after fitting the bearing member 12 around the outer periphery of the core 13, the core 13, the bearing base material lower mold 14, and the bearing base material upper mold 15 are set as shown in FIG. 4, and the molten resin material is poured from the resin injection path 15b. When the resin is injected into the resin injection space 14b, the bearing base material 11 is molded on the outside of the bearing member 12 and integrated therewith. This injection molded resin material is used for bearing member 1
It melts at a temperature that does not melt 2,
The resin materials mentioned above are used.

In terms of specific temperatures, for example, the melting point of the bearing member 12 is 3
00°C, the melting point of the resin material forming the bearing base material 11 needs to be less than 300°C.

Further, when forming the protrusion 12a, the resin material constituting the bearing base material 11 is subject to restrictions depending on whether the protrusion 12a is formed by cutting or rolling. That is, when forming by cutting, the shape of the protrusion 12a is maintained even if the bearing member 12 is heated to a relatively high temperature below the melting point, but when forming by rolling, the shape of the protrusion 12a is maintained when the heating temperature is high. may return to its original flat surface. Therefore, it is necessary to use a material with a relatively low melting point as the bearing base material 11. In the above example, when the projections 12a are formed by rolling at about 300°C, the melting point of the resin material of the bearing base material 11 is limited to about 270°C.

During the above injection molding, the core 13 is heated (150 to 240
℃) is desirable. When heated in this way, the shape of the reference cylindrical surface 13a of the core 13 remains unchanged in the bearing member 12.
Since the bearing is transferred to the inner surface of the bearing, it is possible to obtain a sliding bearing with extremely high dimensional accuracy. Of course, the diameter of the reference cylindrical surface 13a is
This is determined in anticipation of shrinkage of the bearing base material 11 and bearing member 12 after injection molding.

Note that the magnitude of this thermal contraction varies depending on the radial thickness of the bearing base material 11, and the larger the thickness, the greater the radial contraction. Therefore, by utilizing this difference in thermal contraction, the bearing member 1
It is possible to set two inner surface shapes. That is, the thickness of the bearing base material 11 in the radial direction is varied in the axial direction so that the desired shape of the inner peripheral surface of the bearing member 12 can be obtained in consideration of shrinkage after injection molding. FIG. 5 shows an example of this, in which the diameter of the bearing base material 11 is set such that the diameter r3 at the center is larger than the diameters r1 and r2 at both ends in the axial direction. If the radii are made different in this way, the heat shrinkage in the central part will be large, so the shape of the inner surface of the bearing member 12 should be a drum-shaped shape with a small diameter at the center and large at both ends, as shown exaggeratedly in the figure, or this It can be shaped similar to. According to this shape, even if the shaft inserted into the bearing member 12 is tilted to some extent, "galling" or the like will not occur. lll
After the above molding is completed, the 1lI receiving base material 11 can be cut, for example, along the cutting line -A'.

FIG. 6 shows an embodiment in which the sliding bearing of the present invention is applied to a shock absorber. Briefly explaining the structure of the illustrated shock absorber, the lower end of the outer shell 2 housing the cylinder 1 therein is connected to the wheel side (not shown), and the piston 3 is slidably fitted into the cylinder 1. The rod 4 connects its upper end to the vehicle body side. The space between the cylinder 1 and the outer shell 2 constitutes a viscous fluid reservoir 5. A guide bush G according to the present invention is fixed to the upper ends of the cylinder 1 and outer shell 2, and the piston rod 4 passes through the guide bush G and oil seal 6 and extends upward. 7 is an outer cylinder of the guide bush G and the oil seal 6. The piston 3 is provided with a valve 8, and a damping force is exerted by the resistance of the viscous fluid passing through the valve 8.

In the above shock absorber, since the piston rod 4 slides on the guide bush G, the guide bush G is
The guide bush (sliding bearing) of the present invention is required to have low frictional resistance, high sealing performance, and stable properties over a long period of time. performance can be obtained.

FIG. 7 shows an embodiment in which the sliding bearing of the present invention is applied to a bearing for a copy machine or the like. In this embodiment, the bearing base material 11 molded on the outside of the bearing member 12 is formed integrally with the support member 21 of the guide rod 20 from the above resin material. A suitable sliding member is supported on the guide rod 20. In this way, the shape of the bearing base material 11 can be arbitrary.

In addition to injection molding, the bearing base material 11 can also be molded by compression molding of powder.

"Effects of the Invention" As described above, the sliding bearing of the present invention is lightweight because the bearing member is made of a fluororesin material and the bearing base material is made of a synthetic resin material with a lower melting point than the fluororesin material. Moreover, a sliding bearing with high integrity can be obtained by joining the resins together.

Further, according to the method of the present invention, this sliding bearing can be easily manufactured at low cost, and its precision can be easily increased. In particular, when protrusions are provided on the outer surface of the bearing member, the resin material that makes up the bearing base material wraps around the protrusions, increasing the integrity of the bearing member and the bearing base material, increasing pressure resistance and rigidity. It is possible to improve the IC and II rubbing characteristics.

[Brief explanation of drawings]

Figures 1 and 2 are longitudinal sectional views showing examples of the shape of a sliding bearing according to the present invention, Figures 3 and 4 illustrate the method of the present invention, and Figure 3 is a cross-sectional view of half of the bearing member. 4 is a longitudinal sectional view showing the state of injection molding, FIG. 5 is a longitudinal sectional view exaggerating the state of change in the inner surface shape of the bearing member due to the difference in thermal contraction, and FIG. 6 is a longitudinal sectional view showing the state of injection molding. FIG. 7 is a cross-sectional view showing an example in which the sliding bearing of the invention is applied to a shock absorber, and FIG. 7 is a cross-sectional view showing an example in which the sliding bearing of the invention is applied to a guide portion of a guide rod. 11... Bearing base material, 12... Bearing member, 12a...
・Protrusion, 13... Core, 13a... Reference cylindrical surface, 1
4...Bearing base material lower mold, 14b...Resin corporation space, 1
5...Bearing base material upper mold, 15b...Resin injection path, G.
...Guide bush (sliding bearing). Figure 1 Figure 2 Figure 7

Claims (10)

[Claims] (1) In a sliding bearing in which a bearing member is integrated into the inner surface of a bearing base material, the bearing member is made of a fluororesin material, and the bearing base material is made of a synthetic resin material with a melting point lower than that of the fluororesin material. A sliding bearing characterized by the following structure. (2) The sliding bearing according to claim 1, wherein an annular or non-annular projection is formed on the outer surface of the bearing member. (3) The sliding bearing according to claim 1 or 2, wherein the fluororesin material is made of PTFE, PFA, ETFA, or FEP alone, or a mixture of these and a filler. (4) In any one of claims 1 to 3, the bearing base material is polyphenylene cellulite,
Polybutylene terephthalate, polyamide resin materials,
A single substance of polyimide resin material, aromatic polyester resin material, polyisolate resin material, polyether resin material, polyetherimide resin material, polysulfone resin material, polyolefin resin material, or phenolic resin material, or Plain bearings made of a mixture of these and fillers. (5) Form a bearing member from a fluororesin material, fit this bearing member around the outer periphery of the core so that its inner sliding surface is in close contact with the reference cylindrical surface of the core, and place the bearing member on the outside of the core. A method for manufacturing a plain bearing, comprising forming a bearing base material by molding a resin material with a lower melting point. (6) The method for manufacturing a sliding bearing according to claim 5, wherein an annular or non-annular protrusion is formed on the outer surface of the bearing member. (7) The method of manufacturing a sliding bearing according to claim 5 or 6, wherein the core is heated to an extent that softens the bearing member. (8) In any one of claims 5 to 7, the radial thickness of the bearing base material molded on the outside of the bearing member is adjusted to a cylindrical shape in consideration of shrinkage after injection molding. A method of manufacturing a sliding bearing in which the shape of the sliding member is varied in the axial direction so as to obtain the desired shape of the inner peripheral surface. (9) In either claim 5 or 8, the fluororesin material is PTFE, PFA, E
A method for manufacturing a sliding bearing made of TFA or FEP alone, or a mixture of these and a filler. (10) In any one of claims 5 to 8, the bearing base material includes polyphenylene cellphide, polybutylene terephthalate, a polyamide resin material, a polyimide resin material, an aromatic polyester resin material, Sliding bearings made of a single polyasolate resin material, polyether resin material, polyetherimide resin material, polysulfone resin material, polyolefin resin material, or phenol resin material, or a mixture of these and a filler. manufacturing method.