JPH0369813A - Bearing with dynamic pressure slot and manufacturing method thereof - Google Patents

Abstract

PURPOSE:To improve friction characteristic and dimensional accuracy by bonding resin sheets made of PTFE(polytetrafluoroethylene resin) as a main component to the bore face of an outer pipe and forming dynamic pressure generating recesses in the inner surfaces of the sheets. CONSTITUTION:A bearing 20 with dynamic pressure slots consists of resin sheets 22, made of PTFE as the main component and wear resisting material mixed therein, bonded to the bore surface of an outer metal pipe 21 in axial direction with an interval, and dynamic pressure generating recesses 60, 70 of arrowhead shapes formed in the inner surfaces of the sheets 22. In manufacturing thereof, first, dynamic pressure generating recesses 60, 70 are formed in one surface of the sheet 22 by plastic working. Next, the sheet 22 is inserted into the outer pipe 21 so as to face the other surface of the sheet 22 to the inner surface of the outer pipe 21 via adhesive agent, a rod is inserted inside the inner surface of the sheet 22, and the rod is taken out from the inside of inner surface of the sheet 22 after hardening of the adhesive agent. A rubber adhesive agent dissolved with a solvent or a thermohardening adhesive agent and the like is used as the adhesive agent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydrodynamic grooved bearing made of synthetic resin used for office equipment, audio equipment, measuring equipment, etc., and a method for manufacturing the same.

[Prior art] Conventional cylindrical sliding bearings made of synthetic resin, especially dynamic pressure grooved bearings with grooves for generating dynamic pressure on the inner diameter surface, are made of elastic thermoplastic synthetic resin with graphite, carbon fiber, etc. It is manufactured by injection molding using a mold using a composite material mixed with lubricating substances such as molybdenum disulfide and fluororesin, and then pulling it out of the mold using the elasticity of the resin.

The groove for generating dynamic pressure is formed at the same time as the above molding.

In that case, the base resin of the thermoplastic synthetic resin used does not include PTFE (polytetrafluoroethylene resin). This is because PTFE does not melt even when heated and is in powder form, and becomes gelatinous at temperatures above 330''C, making injection molding impossible.

Generally, forming PTFH is done in a manner similar to powder metallurgy. That is, after putting a PTFE powder material into a mold and gradually pressurizing it, it is taken out from the mold and 360 to 380°
Bake at C. When the entire product becomes gel-like, it is taken out and immediately placed in another mold for secondary molding. Products with complex shapes or requiring dimensional accuracy are finished by machining after molding. The process is complicated and time-consuming, and the production of hydrodynamic grooved bearings using this molding method has not been carried out as a practical matter.

In the case of pipes, tubes, etc., an organic solvent is added to PTFE powder to form a paste, which is then extruded into a pipe, etc. using an extruder, and then the solvent is evaporated and then fired in a heating furnace to form the product. A molding method is also used. However, since baking takes about two days, productivity is poor, and the shape is largely deformed by baking, so this method has not been applied to the production of hydrodynamic grooved bearings.

It is possible to manufacture dynamic pressure grooved bearings using thermoplastic resin materials other than PTFE, but the molding shrinkage is large and the dimensional accuracy is insufficient, and the friction characteristics are not sufficient. Its performance is not fully demonstrated. In response to this, the present applicant has previously proposed a dynamic pressure grooved bearing using a thermosetting resin with good molding precision and a method for manufacturing the same (Japanese Patent Application Laid-open No. 203916/1983).

This is made of thermosetting resin such as epoxy resin, phenol resin, unsaturated polyester resin, diallyl phthalate resin, etc., and has a thin inner cylinder with grooves for generating dynamic pressure on the inner diameter surface, and a metal outer cylinder. This is a dynamic pressure grooved bearing that is fixed to the inner diameter surface of the bearing.

When manufacturing this bearing with hydrodynamic pressure grooves, an outer cylindrical body with many grooves or fixing means such as adhesive applied to the inner diameter surface is fitted into the outer mold in advance, and the grooves for generating dynamic pressure are shaped. A molding material made by heating and melting a thermosetting resin is supplied into a narrow annular space between an inner mold in which protrusions corresponding to the above are arranged on the outer peripheral surface and an outer cylinder fitted in the outer mold. This molding material is cured to form an inner cylindrical body, and this is fixed to the outer cylindrical body via a fixing means to form a laminated structure in which the inner cylindrical body and the outer cylindrical body are integrated. , the laminated structure of the inner cylinder and the outer cylinder is extracted from the outer mold and the inner mold in the axial direction and released from the mold.

[Problem to be solved by the invention]

However, although thermosetting resins have good molding accuracy, the resin itself has low friction and wear characteristics, and even graphite,
Even when lubricating substances such as carbon fiber and molybdenum disulfide are mixed, there is a problem in that good friction and wear characteristics cannot be obtained.

Further, when a plurality of single bearings are assembled into a unit, there is a problem in that it is difficult to achieve coaxiality of the inner diameters of the plurality of bearings.

Therefore, the present invention has been made by focusing on the above-mentioned conventional problems, and its purpose is to improve the frictional properties by using a resin whose main component is PTFE, which is a thermoplastic resin with excellent frictional properties. The object of the present invention is to provide a hydrodynamic grooved bearing having excellent wear characteristics and excellent dimensional accuracy, and a method for manufacturing the same, thereby solving the above-mentioned conventional problems.

[Means to solve the problem]

In the dynamic pressure grooved bearing of the present invention, a resin sheet containing PTFE as a main component is adhered to the inner diameter surface of an outer cylinder, and grooves for generating dynamic pressure are formed on the inner surface of the sheet.

In addition, in another dynamic pressure grooved bearing of the present invention, sheets of resin mainly composed of PTFE are adhered to the inner diameter surface of the outer cylinder at intervals in the axial direction, and the inner surface of the sheets is used for generating dynamic pressure. A groove is formed.

The method for manufacturing a dynamic pressure grooved bearing of the present invention involves forming grooves for generating dynamic pressure on one surface of a resin sheet mainly composed of PTFE by plastic working, and forming a groove between the other surface of the sheet and an outer cylinder. A sheet is inserted into the outer cylinder so that the inner diameter faces are opposed to each other via an adhesive, a rod is inserted into the inner surface of the sheet, and after the adhesive has hardened, the rod is taken out from the inner surface of the sheet.

The present invention will be explained in detail below.

The resin containing PTFE as a main component of the present invention is a mixture of PTFE and a wear property improving substance.

The content of PTFE is preferably 50 to 90 wt%. If it is less than 50 wt%, the frictional properties, which are the characteristics of PTFE, will deteriorate. On the other hand, if it is more than 90wL%, the amount of the abrasion-improving substance added will be too small, and the abrasion resistance will not improve. However, it is not necessarily limited to the above range, and may be less than 50 wt%, or 90 wt%
may exceed.

As the wear property improving substance to be mixed, for example, graphite, carbon fiber, molybdenum disulfide, polyimide, econol, glass fiber, etc. can be used.

The resin sheet containing PTFE as a main component of the present invention may be formed by a well-known resin sheet manufacturing method using a mixed material of the above-mentioned PTFE resin and a wear property improving substance,
For example, an organic solvent such as naphtha is added to make a paste, the sheet is made into a sheet in a calender, the solvent is evaporated and then burned in a heating furnace, or a dispersion of mixed materials is poured onto a metal surface. After that, it can be burned and the formed film peeled off, or one cut from a molded cylindrical block can be used. The thickness of the sheet is 0.1 to 2. O
tmrr is preferred.

When adhering this sheet of resin whose main component is PTFE to the inner diameter surface of the outer cylinder, the surface of the sheet to be adhered is subjected to a roughening chemical treatment (defluorination treatment) according to a conventional method. This is a treatment for improving the adhesiveness of the sheet, and surface treatment using a primer specifically for fluororesin, a so-called sodium treatment method, etc. can be applied.

As the adhesive, a rubber adhesive dissolved in a solvent to an appropriate viscosity, a thermosetting adhesive, or the like can be used. These adhesives are uniformly applied to the chemically treated surface of the resin sheet containing PTFE as a main component, and then semi-dried. Alternatively, instead of applying the adhesive to the sheet, the adhesive may be applied to the inner diameter surface of the outer cylinder.

Note that the depth of the grooves for generating dynamic pressure in the dynamic pressure grooved bearing is preferably 5 to 60 μm in order to obtain an appropriate dynamic pressure effect.

However, the depth of the groove for generating dynamic pressure formed on the inner surface of the resin sheet mainly composed of PTFE is preferably slightly deeper than 5 to 60 μm. This groove for generating dynamic pressure is P
It is preformed by plastic working on one side of a resin sheet whose main component is TFE. For example, after chemically treating the other surface to be adhered for adhesion, grooves for generating dynamic pressure are rolled by a rolling machine on the surface that is not chemically treated, and the sheet thickness is made uniform. The heating temperature during this rolling is preferably 100 to 200''C. However, the chemical treatment for adhesion may be performed after the above-mentioned plastic working of the grooves for generating dynamic pressure.

Note that pressing may be used instead of rolling.

At the same time that the adhesive is applied to the surface to be bonded (if the adhesive is applied to the outer cylinder side, the surface to be bonded is simply subjected to chemical treatment for adhesion), and the above-mentioned dynamic pressure is generated on the other surface. A resin sheet mainly composed of PTFE with plastic grooves is cut to the required length, rolled up and inserted into the outer cylinder with the surface to be adhered facing outward. Next, a metal or plastic rod is lightly press-fitted and inserted into the inner surface of this rolled sheet.

For example, when a rubber adhesive is used as the adhesive, it is heated to a temperature of 60 to 150°C for 10 to 6 hours to harden the adhesive.
Heat for 0 minutes.

In addition, by making the linear expansion coefficient of the rod larger than that of the outer cylinder, making the linear expansion coefficient of the seat larger than that of the outer cylinder, and further making the linear expansion coefficient of both the rod and the seat larger than the outer cylinder, During heating, it is preferable that the inner surface of the sheet is compressed by the rod and undergoes some plastic deformation.

If the linear expansion coefficients of the outer cylinder, rod, and seat are selected in this way, even if the rod is inserted into the inner surface of the seat with a gap, the inner surface of the seat will be compressed by the rod during heating, resulting in some plastic deformation. It can be made to accompany.

Furthermore, aluminum has a higher coefficient of linear expansion than steel, but a lower coefficient of linear expansion than synthetic resin. A resin containing PTFE as a main component has a larger coefficient of linear expansion than steel or aluminum. It is preferable that the inner surface of the seat is pressed by the rod by appropriately selecting materials for the rod and the outer cylinder.

Note that when a room temperature curing type adhesive is used, heating is not necessary, and it is sufficient to leave it at room temperature for the time required for curing after the rod is press-fitted into the inner surface of the sheet.

After the adhesive has hardened, remove the rod from the inner surface of the sheet.

A plurality of the above-mentioned rolled sheets may be inserted into the outer cylinder at intervals in the axial direction and adhered to each other.

In this way, the sheet is adhered to the inner diameter surface of the outer cylinder with some plastic deformation under the pressure of the rod, and excellent inner diameter dimensional accuracy and coaxiality are obtained.

Note that the outer cylinder may be made of metal or plastic, and can be appropriately selected based on the bearing specifications. Further, the shape of the outer cylinder is not limited to a cylindrical shape, but can be square or any other shape as required.

〔Example] Embodiments of the present invention will be described below with reference to the drawings.

Dynamic pressure grooved bearings allow the shaft body and bearing to rotate in one direction or in the opposite direction through their mutual sliding surfaces.

Performs relative linear or spiral movement in the axial direction. Therefore, the pattern of the grooves for generating dynamic pressure is also determined according to the mode of their relative movement.

1(a) to d) show a first embodiment of the present invention, and in FIG. 1(a), the shaft lO and the cylindrical dynamic pressure grooved bearing 20 are relatively Performs linear motion in the forward and reverse directions of the axis. In the dynamic pressure grooved bearing 20, resin sheets 22 mainly composed of PTFE are adhered to the inner diameter surface of a metal outer cylinder 21 at intervals in the axial direction. Palm-shaped grooves 60, 70 for generating dynamic pressure are formed as shown in (b), (C), and (d).

The grooves shown in FIG. 6(b) include grooves 60 whose arrowheads point to the right in the axial direction and grooves 70 which point to the left in the axial direction alternately at approximately the same intervals in the axial direction, and at appropriate intervals in the direction perpendicular to the axis. They are arranged at intervals of .

The groove shown in Figure (C) connects a groove 60 whose arrowheads point to the right in the axial direction and a groove 70 which points to the left in the axial direction facing each other in a diamond shape, and connects the groove with the shaft at almost the same interval in the axial direction. They are arranged at appropriate intervals in the right angle direction.

The grooves shown in FIG. 2(d) are grooves 60 whose arrowheads point to the right in the axial direction and grooves 70 which point to the left in the axial direction, connected in a wave shape in a direction perpendicular to the axis, and arranged at approximately the same intervals in the axial direction. It is.

The depth of the grooves 60, 70 is appropriately selected in the range of several μm to several tens of μm.

The lubricants for the above bearings include oil and grease.

Either water or air is used.

When the shaft body 10 moves linearly in the direction of arrow mark A, the pressure of the fluid at the point of the arrow increases due to the pumping action of the groove 60 pointing to the right in the axial direction whose arrow tip coincides with the direction of movement A.
The shaft body 1O is supported by a fluid film of lubricant flowing into the bearing clearance 23. When the shaft body 10 moves linearly in the opposite arrow B direction, the lubricant flows out from the arrow tip of the groove 70 into the bearing clearance 23 due to the pumping action of the groove 70 facing leftward in the axial direction, the arrow tip of which coincides with the movement direction B. A fluid film is formed by the agent.

The hydrodynamic grooved bearing 20 described above was manufactured as follows.

First, one surface of a resin sheet 22 made of PTFE as a main component and mixed with, for example, glass fiber as an abrasion property improving substance, is subjected to a fluorine-free treatment as a pretreatment for adhesion. This example was carried out in a conventional manner using a primer specifically designed for fluororesin. Thereafter, while pressing and heating the sheet 22 using a rolling machine, grooves 60 and 70 for generating dynamic pressure were bottom-shaped on the other surface that was not subjected to the fluorination treatment. Next sheet 2
A rubber adhesive adjusted to an appropriate viscosity with a solvent was uniformly applied to the defluorinated surface of No. 2, and after volatilizing the solvent and semi-drying, the sheet 22 was cut into desired dimensions. Two identical sheets 22 are rolled up so that the adhesive-applied surface is on the outside, and inserted into the metal (or plastic) outer cylinder 21 with a gap in the axial direction. It was installed in the state shown in a). Let the inner diameter of the seat in that state be d. Thereafter, a rod R having an outer diameter is press-fitted into the inner surface of the inserted sheet 22. This rod outer diameter is slightly larger than the seat inner diameter d, but since the seat 22 is elastically deformable and the coefficient of friction between the seat 22 and the outer cylinder 21 is large at the time of insertion, the rod R can be inserted. is possible.

After that, when heated to a predetermined temperature, the sheet 22 has a larger coefficient of linear expansion than the outer cylinder 21, so the compressive force received from the rod R becomes greater than when the rod R is inserted into the inner surface of the sheet 22.

Note that aluminum is used as the outer cylinder 21, and the rod R
If steel is used as the material, the difference in linear expansion coefficient between the outer cylinder 21 and the rod R is small, and the linear expansion coefficient of the SINIT 22 is several times larger than that of the outer cylinder 21, so the compressive force that the sheet 22 receives from the rod R during heating is is greater than when the rod R is press-fitted into the inner surface of the seat 22.

The sheet 22 is made to conform to the inner surface of the outer cylinder 21 and the outer diameter surface of the rod R by utilizing the plastic deformation caused by the compression of the rod R. After the adhesive has hardened after a predetermined period of time, the rod R
is extracted from the inner diameter surface of the sheet 22.

In this way, the two sheets 22 glued at intervals in the axial direction are commonly pressed with one rod R and plastically deformed, thereby achieving excellent inner diameter dimensional accuracy and A hydrodynamic grooved bearing 20 with guaranteed coaxiality is obtained.

FIGS. 3 and 4 show modified examples of grooves for generating dynamic pressure. The groove pattern shown in FIG. 3 is a groove pattern in which the shaft body 10 and the dynamic pressure grooved bearing 20 perform relative spiral motion in forward and reverse directions. The figure (a) shows a downward groove 60 and an upward groove 7 whose arrowheads are located in the lead angle θ direction of the shaft body 10.
0 are alternately arranged in parallel to the lead angle θ direction.

In the same figure (b), downward grooves 60 and upward grooves 70 whose arrowheads are located in the lead angle θ direction are connected in a diamond shape and arranged in four rows in the axial direction in the lead angle θ direction. are doing.

In the one in FIG. 4, the shaft body 1o and the dynamic pressure grooved bearing 20 are
This is the groove pattern for a radial dynamic pressure grooved bearing that rotates relatively forward and backward. In the same figure (a), grooves 60 whose arrow tips point downward and grooves 7° which point upward are arranged alternately at substantially the same intervals in the circumferential direction, and are arranged at appropriate intervals in the axial direction. . In the same figure (b), the arrow direction is downward facing groove 6.
0 and upwardly facing grooves 70 are connected facing each other in a diamond shape and are arranged at substantially the same intervals in the circumferential direction and at appropriate intervals in the axial direction. A groove 80 for holding lubricant is provided inside the diamond-shaped groove 60, 70 for generating dynamic pressure.

FIG. 5 shows a second embodiment.

In this embodiment, on the inner diameter surface of the outer cylinder 30 whose outer surface is non-cylindrical,
It has grooves for generating dynamic pressure and incorporates a resin sheet 22 made of PTFE as a main component mixed with a wear property improving substance. Function as a hydrodynamic grooved bearing
There is no difference in effect from the first embodiment. In this way, the outer cylinder is not limited to a cylindrical shape, and any shape can be used.

〔Effect of the invention〕

As explained above, the dynamic pressure grooved bearing of the present invention has a structure in which a sheet of resin mainly composed of PTFE, which has grooves for generating dynamic pressure formed on the inner surface, is adhered to the inner diameter surface of the outer cylinder. , the dimensional accuracy of the inner diameter of the bearing becomes sufficiently high, and extremely good friction characteristics are obtained. In addition, excellent wear characteristics can be obtained due to the pumping action of the grooves for generating dynamic pressure.

Further, according to the method for manufacturing a dynamic pressure grooved bearing of the present invention, P
Because grooves for generating dynamic pressure are shaped in advance by plastic processing on one side of the resin sheet whose main component is TFE, the groove depth, groove shape, and sheet thickness can be uniformly formed to the desired dimensions. Furthermore, the bearing clearance can be controlled arbitrarily using the rod inserted into the inner surface of the seat, suppressing the runout of the shaft and bearings and achieving high-precision performance.

Furthermore, the sheet is inserted into the outer cylinder so that the other surface of the sheet and the inner diameter surface of the outer cylinder face each other with the adhesive interposed therebetween, a rod is inserted into the inner surface of the sheet, and after the adhesive hardens, the sheet is Since the rod is taken out from the inner surface, it is easy to make the inner diameters of the multiple bearings coaxial even when multiple bearings are installed at intervals in the axial direction to form a unit, which improves friction characteristics. , it is possible to manufacture high-quality hydrodynamic grooved bearings with excellent wear characteristics and dimensional accuracy.

[Brief explanation of drawings]

FIG. 1(a) is a vertical cross-sectional view of a hydrodynamic grooved bearing according to the first embodiment of the present invention, FIG. 1(b), (C), (d), and FIG. 3(a), (b). , Figures 4(a) and (b) are plan views showing groove patterns for generating dynamic pressure, respectively, and Figure 2(
a) and (b) are longitudinal sectional views illustrating the manufacturing process of the hydrodynamic grooved bearing of the present invention, and FIG. 5 is a longitudinal sectional view of the hydrodynamic grooved bearing of the second embodiment. In the figure, 21 is an outer cylinder, 22 is a seat, 60.70 is a groove for generating dynamic pressure, and R is a rod. Patent issued by NSK Co., Ltd.

Claims (3)

[Claims] (1) A hydrodynamic grooved bearing in which a resin sheet containing PTFE as a main component is adhered to the inner diameter surface of an outer cylinder, and grooves for generating dynamic pressure are formed on the inner surface of the sheet. (2) Dynamic pressure grooves in which sheets of resin whose main component is PTFE are adhered to the inner diameter surface of the outer cylinder at intervals in the axial direction, and grooves for generating dynamic pressure are formed on the inner surface of the sheets. With bearing. (3) Grooves for generating dynamic pressure are formed by plastic processing on one side of a resin sheet whose main component is PTFE, and the other side of the sheet and the inner diameter surface of the outer cylinder are opposed to each other via an adhesive. A method for manufacturing a hydrodynamic grooved bearing, in which a sheet is inserted into an outer cylinder as shown in FIG.