JPH0225053B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing an oil-impregnated bearing used in the bearing manufacturing industry.

(Prior art) Conventional sintering involves pressure-forming metal powder in a mold, sintering it to form a porous sintered body, and impregnating the pores with a lubricating medium such as oil. Oil-impregnated bearings are already known.

As shown in Figure 6 of the drawing, this conventionally known sintered oil-impregnated bearing includes a mixing process for uniformly mixing fine particles of copper or iron bearing material alone or several types of materials, and a process for uniformly mixing this mixed material. A pressure forming process in which the pressure-formed product is compression-molded in a mold, a sintering process in which the pressure-formed product is sintered at high temperature in a sintering furnace, and correction in which the sintered product is sized and partially machined. It is manufactured through a manufacturing process consisting of a machining process and an oil impregnation process of impregnating the porous portions of the bearing to be formed with oil.

Also, a method of coating or fitting a microscopic porous plastic material such as nylon, Teflon, Delrin, etc. on the sliding surface of a bearing using a sintered alloy against the shaft in order to allow the oil in the sintered alloy to flow out little by little. There is one described in Japanese Patent Publication No. 40-5362.

(Problems to be Solved by the Invention) However, in the conventional oil-impregnated bearing, when the shaft rotates while the bearing and the shaft are in contact with each other during use, the oil impregnated in the hole of the bearing flows out and causes a problem between the bearing and the shaft. An oil film is formed in between, and this oil film lubricates and enables smooth rotation of the shaft.For this reason, it is important to impregnate as much lubricating medium into the porous part, and at the same time, this In order to ensure that the appropriate amount of lubricating medium always flows out, it is important to consider how large the holes in the porous section should be.For example, if the hole size is too large, a large amount of oil, which is the lubricating medium, will flow out, and the shaft The rotation causes the oil to scatter and disappear quickly.

Furthermore, if the holes are too small, the lubricating medium oil will not flow out as expected, making it difficult to form the oil film and causing problems such as seizure of the bearing.

In order to solve these problems, a method of increasing the oil content has recently been considered and implemented by installing an oil sump device externally in contact with the bearing. However, when using this oil sump device, the structure is complicated and the device is This had the problem of being expensive.

Furthermore, the method described in Japanese Patent Publication No. 40-5362 had the problem of poor manufacturability because a member other than the sintered alloy was coated or fitted as a minute porous member.

The present invention was made in order to solve the above-mentioned conventional problems, and the holes in the surface and shallow parts of the bearing through which the lubricating medium flows out are made small, and the holes in the deep part are made large. Result oil retention amount (oil content)
The object of the present invention is to provide an inexpensive method for manufacturing an oil-impregnated bearing that can increase oil retention time and maintain oil retention time.

B. Structure of the Invention (Means for Solving the Problems) In order to achieve the above object, the method for manufacturing an oil-impregnated bearing of the present invention includes the following steps shown in Examples.

That is, in a porous oil-impregnated bearing, after the baking step c, there is a step d of masking the small pore walls of the bearing surface portion 3 and the shallow layer portion 4, and after the masking step d, the deep layer portion 7 of the bearing is etched. This process consists of step e and step i of impregnating the etched pores with the lubricating medium 2.

(Example) Next, an example of an oil-impregnated bearing manufactured by the method of manufacturing an oil-impregnated bearing according to the present invention will be described based on FIGS. 1 to 3. This is a sectional view showing an oil-impregnated bearing 1, in which holes 5 in a bearing surface portion 3 and a shallow layer portion 4 through which a lubricating medium 2 made of oil flows out are made into small holes during pressure molding, and A large hole 8 is formed by an etching process in which the deep layer 7 of the bearing 6 to be formed is vacuum impregnated with an etching solution such as ferric chloride, which will be described later, and the hole 5 of the bearing surface portion 3 and the shallow layer 4 are formed. Hole 8 in deep layer 7
A lubricating medium 2 made of oil such as Anderol oil is impregnated into the porous portion.

The oil-impregnated bearing having the above structure is manufactured by the manufacturing methods of the following first and second embodiments, and the first embodiment will be explained based on FIG. 4.

(a) Mixing process; Either fine particles of copper powder, lead powder, tin powder, and graphite powder are mixed in a mixer, or bearing forming materials made of iron powder, copper powder, lead powder, and graphite powder are mixed in a mixer.

(b) Molding process; The mixed bearing forming material is compression molded using a mold to form the bearing 6. A powder compact is obtained in which holes 5 consisting of a large number of small holes are formed in the surface portion 3 and shallow layer portion 4 of the bearing 6 formed at this time.

(c) Firing step: The compacted compact shaped into a bearing is placed in a firing furnace whose interior is heated to a high temperature and sintered.

(d) Masking step; vacuum impregnates water-soluble acrylic resin liquid on the surface of the metal powder in the holes 5 of the surface portion 3 and the shallow layer 4 near the surface of the fired bearing 6, and dries the water. is evaporated to form a resin film 9 of about 1 um in thickness so that the surface of the metal powder is not affected by the etching described later.

As a means for this masking, for example, an oxide film may be formed by surface treatment such as black dyeing, or a film may be formed on the surface of the metal powder by electrolytic plating of nickel or the like. All of these materials must be made of materials that are not corroded by the etching solution.

(e) Etching process; impregnating the inside of the bearing 6 with an etching solution from the hole 5 of the bearing surface part 3 covered with the resin film 9 in the masking process to corrode the unmasked iron or copper metal part, A large hole 8 is formed in the deep part 7 of the bearing 5.

This etching solution uses ferric chloride and is vacuum impregnated. The amount of etching is controlled by the time and concentration of the solution.

In some cases, a gas that corrodes metal is used as the etching means.

(f) Cleaning step: The etched bearing 6 is washed with a cleaning solvent to wash away the etching solution and remove it.

(g) Masking film removal step: After removing the etching solution, a film removal solution was impregnated from the surface portion 3 of the bearing 6 and was swirled into the holes 5 in the surface portion 3 and the shallow layer portion 4 of the bearing 6. The resin film 9 is peeled off. If the resin film 9 is formed using an acrylic resin at this time, the film 9 can be removed using an alkaline solution.

(h) Washing step: After removing the resin film 9, the adhering film removal liquid is washed away again with a cleaning solution to remove it.

(i) Oil impregnation step: A lubricating medium is applied to the holes 5 in the porous bearing 6, in which the holes 5 in the surface portion 3 and the shallow layer 4 of the bearing 6 are small holes, and the holes 8 in the deep layer 7 are large holes. This impregnation is carried out by placing the bearing 6 in an impregnation tank, vacuum degassing the tank, pouring Anderol oil into the tank and holding it for a certain period of time. It is impregnated with oil.

Next, the second embodiment of the manufacturing method according to the present invention will be described in the fifth embodiment.
To explain based on the diagram, the manufacturing method of this second embodiment consists of a mixing process, a molding process, a firing process, a masking process, an etching process, a cleaning process, and an oil impregnation process, especially the mixing process, molding process, and firing process. The steps up to this point are the same as in the first embodiment, except that in the next masking step, a fluororesin with a low coefficient of friction is used, and a fluororesin solution is applied to the bearing surface and the holes in the shallow layer near the surface. The material is impregnated with water, dried, and the water is evaporated to form a resin film for masking.

This masked bearing is vacuum impregnated with an etching solution made of ferric chloride to etch the unmasked metal parts to form holes for oil reservoirs in the deep part of the bearing (etching process). After washing away the liquid with a cleaning solution (cleaning process), the formed porous portions are impregnated with Anderol oil (oil impregnation process) to form a predetermined oil-impregnated bearing.

If a fluororesin is used for this masking, it may be left as is without washing for the purpose of imparting a friction coefficient even after the etching process.

Note that the oil-impregnated bearing manufactured according to this example is as follows:
For example, it is used in micro motors in audio equipment, etc., and receives these rotating shafts. When the shaft rotates, the oil from the lubricating medium 2 impregnated in the porous part of the bearing flows out, causing the bearing and shaft to An oil film is created between the two to provide lubrication.

At this time, the oil film was initially formed on the bearing surface area 3 and shallow layer area 4.
To obtain a long-life oil-impregnated bearing with a constant and stable supply of oil by forming an oil film by the oil accumulated in the hole 5 of the bearing, and later increasing the oil content by forming an oil film by the oil 2 accumulated in the hole 8 of the bearing deep layer 7. Can be done.

C. Effects of the Invention The method for producing an oil-impregnated bearing according to the present invention includes, in a porous oil-impregnated bearing, a step of masking the bearing surface portion and the small hole wall portion of the shallow layer after the baking step, and after the masking step. Since this process involves etching the deep part of the bearing and impregnating the etched pores with a lubricating medium, it is possible to sump oil into the deep part without affecting the surface part of the bearing and the pores in the shallow part. Alternatively, holes for press fit strain absorption can be easily formed, and by adjusting the etching solution concentration and etching time in the etching process,
It is possible to optimize the hole size in the deep layer, which makes it possible to always supply an appropriate lubricating medium during use, and it is unique in that it is possible to provide high-performance bearings with good manufacturability at low cost. effective.

[Brief explanation of drawings]

Figure 1 is a sectional view showing an example of an oil-impregnated bearing manufactured by the method of manufacturing an oil-impregnated bearing according to the present invention, and Figure 2 is an enlarged sectional view of the main part in a masked state in the manufacturing process. , FIG. 3 is an enlarged sectional view of the main parts after oil impregnation, FIG. 4 is a block diagram showing the first embodiment of the manufacturing method, and FIG. 5 is a block diagram showing the second embodiment. , FIG. 6 is a block diagram showing a conventional manufacturing process. In the figure, 1 is the oil-impregnated bearing, 2 is the lubricating medium, 3 is the bearing surface, 4 is the shallow layer, 5 is the hole, 6 is the bearing, 7 is the deep layer, 8 is the hole, 9 is the resin film, and c is the fired one. process, d
is a masking process, e is an etching process, and i is an oil impregnation process.

Claims (1)

[Claims] 1. In a porous oil-impregnated bearing, after the baking process, there is a process of masking the surface of the bearing and the walls of the small holes in the shallow part, a process of etching the deep part of the bearing after the masking process, and a process of etching the deep part of the bearing. A method for manufacturing an oil-impregnated bearing comprising the step of impregnating a porous portion with a lubricating medium.