JPS6358288B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises a sliding surface layer made of a thin plate of tetrafluoroethylene resin (PTFE), an intermediate layer made of wire mesh, and a reinforcing layer formed of multiple wound layers of resin cloth. The present invention relates to a bearing and a manufacturing method thereof.

Conventionally, methods for manufacturing rolled bush bearings in which the inner sliding surface layer is made of PTFE and the outer reinforcing layer is made of other synthetic resins include Japanese Patent Publication No. 47-50893 and Japanese Patent Publication No. 50893.
No. 56-8045 and JP-A No. 54-3892, etc., but in both of these, the PTFE layer forming the sliding surface is composed of PTFE fibers, other fibers, and interwoven fabrics, so dimensional accuracy is low. When the above problem occurs or the diameter needs to be expanded, there is a problem in that the inner sliding surface layer cannot be corrected by cutting.

That is, the mixed woven fabric forming the sliding surface is cut and removed by a knife, resulting in a significant reduction in bearing performance.

Furthermore, in products lined with PTFE mixed woven fabric, the adhesive used to bond the reinforcing layer tends to seep into the woven fabric surface (sliding surface) during molding and cover the surface. There is a problem in that the low friction properties of the material are lost.

When a product in such a state is used, particularly under heavy load conditions, the frictional torque is large, which often causes the problem of peeling of the lining layer.

Therefore, in this type of bearing, not only the dimensional accuracy of the core metal but also the type of resin and base material used, the degree of drying (hardening) of the resin cloth and primer treated surface, molding conditions, curing conditions, etc. If you do not strictly control the process, you will not be able to obtain a satisfactory product.

If the inner sliding surface layer could be machined and there was no need to worry about adhesive seepage, there would be some disadvantages such as an additional step and generation of cutting waste. However, compared to the difficulty of solving problems due to strict management as mentioned above, it can be said that the advantages in terms of production practices are rather large.

From this viewpoint, the present inventors have conducted extensive research to solve the above-mentioned problems, and have completed the present invention.

That is, by using a thin plate of filled or unfilled PTFE with one side treated to remove fluorine as the sliding surface layer, the above-mentioned cutting problems and adhesive oozing problems were solved.

In order to increase the bonding strength between this PTFE thin plate and the multi-wound reinforcing layer made of resin cloth, a wire mesh is placed between the two as an intermediate layer. A desired bearing product was obtained by combining the above-mentioned engagement with the fluorine-free treated surface of PTFE and the resin cloth through the wire mesh.

The present invention is characterized in that this mechanical engagement and adhesion are effectively achieved by employing a roll forming technique.

The present invention will be explained in detail below.

First, prepare a thin PTFE plate with one side treated to remove fluorine. The thickness of this PTFE thin plate is usually about 0.3 to 5 mm, particularly 0.5 to 3 mm, although it varies depending on the diameter of the bearing to be obtained.

PTFE can be used as an unfilled commercially available thin plate, but as a sliding material, materials such as graphite and molybdenum disulfide are used to improve wear resistance and load carrying capacity without impairing the low friction properties. It is more preferable to use a filled PTFE thin plate mixed with solid lubricant powder or metal powder or inorganic powder.

If the PTFE sheet has already been defluorinated when the sheet is delivered from the manufacturer, it can be used as is, otherwise it can be treated with a treatment agent (for example, Junkosha's "Tetra-Etschi") according to the usual method. Process using. The fluorine-free treatment is performed to increase the adhesive strength with the reinforcing layer, but
It is more preferable to apply a primer to the treated surface prior to winding and lamination molding.

As the primer, a varnish made of the same type of thermosetting synthetic resin used for resin cloth is generally used. After applying the varnish, remove the solvent before moving on to the next step.

The PTFE thin plate pretreated in this way is wrapped in a single layer around the core metal with the treated side facing outward.

The winding around the core metal can be exemplified in the following two ways.

In other words, if you decide the width of the thin plate in advance according to the circumference of the core metal and wrap it around the core metal,
It is possible to wrap it in a single layer so that at least the starting edge and the ending edge of the wrapping do not overlap.

Another method is to prepare a thin PTFE plate cut into strips with a certain width, and wrap this in a spiral in the longitudinal direction of the core so that the side edges of the strips do not overlap. be.

In either case, a sliding surface layer is obtained by wrapping the core metal in a single layer. Here, "at least they do not overlap" means that the ends or side edges may come into contact with each other in each winding method.

During this winding, if the sliding surface layer thin plate is used in a heated state (approximately 120° C.), it will have increased flexibility and will be easier to wind.

In particular, for products that have been subjected to primer treatment, if the applied primer is heated and dried at a temperature of around 120°C (solvent removed) and then immediately used for wrapping, there is no need to reheat the thin plate during wrapping.

Next, a wire mesh is fitted onto this PTFE wound layer.

The wire mesh used is, for example, a bag-knitted wire mesh with a thickness of about 3 to 5 mm. stainless steel wire,
Braided wire meshes made of nickel silver wire, phosphor bronze wire, etc. are preferred; those made of too soft metal wires are not preferred because they do not bite into the resin sufficiently.

Bag-knitted wire mesh can expand to some extent in the radial direction and has elasticity, so if you use bag-knitted wire mesh that is slightly smaller than the outer diameter of the PTFE wound layer, it will fit snugly and be fitted. can be done.

This wire mesh can be coated by spirally winding a sheet-like mesh onto the PTFE wound layer, but if a bag-knitted mesh is used with an expanded diameter, there are no seams between the meshes. , it can be fitted uniformly and has excellent homogeneity.

A resin cloth obtained by applying a thermosetting synthetic resin varnish such as phenolic resin, epoxy resin, or polyester resin is placed on top of this wire mesh intermediate layer and wrapped while heating and pressurizing it to form a laminated reinforcing layer. .

A roll molding method described later is applied to this lamination molding.

The finished product is removed from the roll forming machine along with the core metal, and heated to the curing temperature of the resin (approximately 130°C).
Curing proceeds in an atmosphere heated to ~180°C) without external pressure. It is preferable to keep the curing temperature relatively low and to take a slightly long curing time.

135±5℃ when using phenolic resin
The standard time is about 6 hours at a temperature of
10-odd millimeters), it is necessary to take a longer curing time.

During this treatment (curing) process in a heated atmosphere, radial compressive force is generated in the molded product due to thermal expansion of the core metal and contraction as the molded material hardens, resulting in dense molding. Become a thing.

The radial compressive force generated in this curing process is greater than the pressure applied by rolls during laminated molding of resin cloth, and the holding time in the heated atmosphere is also significantly longer than the heating time during molding. .

Therefore, although the wire mesh is bitten into the PTFE thin plate that forms the sliding surface layer and the resin cloth that forms the reinforcing layer during molding, it is completed in this curing process.

Also, the adhesion between the PTFE treated surface and the resin cloth is completed at this point.

After curing for a specified period of time, when the core is removed,
Since some shrinkage will still occur in the molded product, leave the molded product until the dimensional change has subsided.

After this curing process and the core metal removal, the molded product is left undisturbed even if there is a slight gap between the winding start and winding end edges of the PTFE thin plate or the side edges in the case of spiral winding.
This gap is almost completely closed.

The thus obtained cylindrical and tubular laminated molded product (up to a length of about 4 meters is possible) is cut to an appropriate length depending on the purpose, and by lightly cutting the inner and outer diameters, the inner The bearing is made of a synthetic resin laminate with a PTFE sliding surface layer, a reinforcing layer made of thermosetting synthetic resin on the outside, and a wire mesh intermediate layer between the two to firmly connect the two. can get. Of course, for applications where dimensional accuracy is not so required, the PTFE inner diameter surface as molded may be used as the sliding surface.

The cloth base material used in the resin cloth of the present invention is preferably a cloth made of polyester fiber (trade name: Tetron), or a blended or interwoven cloth made of polyester fiber and cotton fiber.

In addition, cotton cloth can also be used, but inorganic cotton cloth made of glass fiber, asbestos fiber, carbon fiber, etc. is preferable for heat-resistant applications.

The above-mentioned polyester or blended or woven fabrics containing polyester have the following characteristics: ○A) It has low hygroscopicity, so there is almost no swelling due to moisture absorption, and it has excellent dimensional stability as a bearing. ,
Combined with the thermal expansion of the core metal, the compressive force generated in the molded product is large, and therefore the wire mesh middle layer is well penetrated into the resin, and the bonding force between the PTFE sliding surface layer and the reinforcing layer is large. Not only that, but also the molded product as a whole becomes a dense molded product.

○C Excellent in manufacturing and moldability of resin cloth.

It has the following advantages, and is particularly preferable as a general-purpose base material used in the present invention.

FIG. 1 shows a principle diagram of the roll forming method used for manufacturing a bearing made of a laminate molded product of the present invention, in which 1 is a core metal, 2 is a pressure roller, 3 and 4 are heating rollers, and 5 is a guide roller.

The core metal 1 is located in a position surrounded by these three rollers, rotational driving force is applied to the core metal, and the three rollers are in contact with and follow the core metal.

FIG. 2 is a plan view showing a PTFE thin plate wound around a core metal and a wire mesh coated on the thin plate, and FIG. 3 is a cross-sectional view showing a state in which lamination molding has progressed.

6 is a winding layer (sliding surface layer) made of PTFE thin plate;
7 is a wire mesh, 8 is a laminated reinforcing layer, and 9 is a resin cloth used for forming the reinforcing layer.

Once the reinforcing layer has reached a predetermined diameter (wall thickness) after being rolled in this way, the resin cloth is cut and rolled up, the molded product along with the core metal is removed from the molding machine, and it is placed in the heating furnace together with the core metal. Move and cure.

FIG. 4 is a perspective view of a bearing bush obtained by cutting a cylindrical and tubular laminated molded product.

Compared to molded products made by compression molding using a mold, products made by roll molding are more uniform and beautiful because there are no disturbances in the base material layer or resin flow marks on the laminated reinforcing layer, It is obtained as a cylindrical and tubular laminated molded product, and by cutting it, it can be made into a bearing of the desired length, so it is easy to manufacture, does not require the use of expensive molds, and has a particularly small outer diameter dimension. It has the advantage of having a large degree of dimensional freedom by adjusting the number of layers of winding.

The thus obtained bearing of the present invention has no oozing of adhesive on the sliding surface, has an intermediate layer, and has a strong bond between the sliding surface layer and the reinforcing layer. It has many advantages, such as being able to withstand use under heavy load conditions, and having a laminated structure, it has excellent mechanical strength.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of the roll forming method used for manufacturing a bearing made of a laminated molded product of the present invention. Fig. 2 is a plan view showing the PTFE thin plate wound around the core metal and the wire mesh covered on the thin plate, Fig. 3 is a cross-sectional view showing the state in which lamination molding has progressed, and Fig. 4 is a FIG. 2 is a perspective view of a bearing bush of the present invention. 1... Core bar, 2... Pressure roller, 3, 4...
Heating roller, 5... Guide roller, 6...
Winding layer (sliding surface layer) made of PTFE thin plate, 7...
Wire mesh, 8... Laminated reinforcing layer, 9... Resin cloth.

Claims (1)

[Claims] 1. Sequentially from the inside: a sliding surface layer made of a filled or unfilled tetrafluoroethylene resin thin plate, an intermediate layer made of a wire mesh, and a resin cloth made of a thermosetting synthetic resin and a cloth base material. and a reinforcing layer formed by multiple winding layers of the polytetrafluoroethylene resin and the resin cloth, both of which fill the holes in the wire mesh of the intermediate layer and adhere to each other, thereby reinforcing the intermediate layer. A bearing made of a synthetic resin laminate molded product in which three parts are firmly integrated through a media. 2 (a) Prepare a thin plate made of tetrafluoroethylene resin that has been subjected to a fluorine-free treatment on one side, and wrap it in a single layer around a core metal with the treated side facing outward to form a sliding surface layer. ) on the wrapped tetrafluoroethylene resin thin plate,
Covering the wire mesh as an intermediate layer (c) A resin cloth made of a thermosetting synthetic resin and a cloth base material is wound multiple times on the covered wire mesh while heating and pressurizing it to form a laminated reinforcing layer. (d) The thermosetting synthetic resin is cured together with the core metal in a heated atmosphere without applying pressure from the outside. (E) The core metal is then removed and the resulting cylindrical tubular shape is A method for manufacturing a bearing made of a synthetic resin laminate molded product, characterized by the steps described above, including cutting the laminate molded product into a predetermined length.