JPH068820U - Sliding block - Google Patents

Abstract

(57) [Summary] [Purpose] A graphite rod 13 that performs a solid lubricating action is easily cast around a block body 11 made of metal. [Structure] The carbon content in the binder that bonds the graphite particles of the graphite rod 13 is heated to a high temperature in an oxygen-free atmosphere to be graphitized before casting. As a result, even if the graphite rod 13 comes into contact with the molten metal and is heated to a high temperature during pouring, the carbon content in the binder of the graphite rod 13 does not oxidize to generate gas, and the cast graphite rod 13 Is possible.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a sliding block in which a graphite body as a solid lubricant is embedded in a block body.

[0002]

[Prior art]

 Generally, in mechanical devices, etc., there are places where members slide, for example, slide bearings and guide bushing installation places.However, in order to reduce friction and wear between members at such places, it is Buried solid lubricants.

Conventionally, as a sliding block in which such a solid lubricant is embedded, for example, one described in Japanese Patent Publication No. 64-87056 is known. This is one in which a plurality of solid lubricants made of a sintered body of calcium fluoride are embedded in a block body made of cast iron. In order to manufacture this product, first, a plurality of solid lubricants are embedded in a model made of foamed polyethylene or the like that burns when it comes into contact with molten cast iron in the same shape as the sliding block, and then the solid lubricant is used. The molding sand is filled around the model in which is embedded to mold the mold. Next, molten cast iron is poured into the mold to vaporize the model to form a cavity in the mold, and the cavity is filled with the molten cast iron. As a result, the solid lubricant is surrounded by the molten cast iron. Then, this molten cast iron is cooled and solidified to form a sliding block. Then, the sliding block is machined as required to expose a part of the solid lubricant on the sliding surface.

[0004]

[Problems to be solved by the device]

 Here, it is possible to use a graphite body as the above-mentioned solid lubricant, but when trying to cast such a graphite body, a large amount of gas is generated from the graphite body in contact with the molten metal, so pouring It had to be completed halfway, and as a result, the graphite body could not actually be cast.

[0005]

[Means for Solving the Problems]

 As a result of earnest research on the mechanism by which the gas is generated from the graphite body during pouring, the present inventor found that the graphite body formed a large number of fine graphite particles, for example, a flammable binder such as a thermoplastic resin. It was found that the carbon content in the binder burns and a large amount of gas is generated when the high-temperature molten metal comes into contact with the graphite body during casting, because it is composed by bonding.

The present invention was made based on the above-mentioned findings, and casts a plurality of graphite bodies as solid lubricants, some of which are exposed on the sliding surface, in a block body made of metal. In a sliding block constructed by embedding by encircling, the carbon content in the binder that bonds the graphite particles of the graphite body to graphite by heating to 2500 ° C or more in an oxygen-free atmosphere before casting. It has been transformed.

[0007]

[Action]

 When a sliding block is manufactured, a graphite body is cast by a molten metal, but at this time, the molten metal and the graphite body come into contact with each other, so that the graphite body is heated to almost the same temperature as the molten metal. Here, the carbon content in the binder that binds the graphite particles of the above-mentioned graphite body was graphitized by heating it to 2500 ° C or higher in an oxygen-free atmosphere before casting, so Even if heated, the carbon content (black lead) in the binder does not burn, and as a result, the graphite body can be cast. Then, when the molten metal having the graphite body cast therein is cooled and solidified to form a block body, a sliding block in which the graphite body is enclosed is formed in the block body. Then, if necessary, mechanical processing is performed to expose a part of the graphite body on the sliding surface.

[0008]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 10 denotes a guide bush as a sliding block used in a press die or the like. The guide bush 10 includes a block body 11 made of a metal such as cast iron or a copper alloy, and a block body 11 inside the block body 11. It is composed of a cylindrical graphite rod 13 as a plurality of embedded graphite bodies. The block body 11 has a cylindrical portion 12, and an inner peripheral surface 15 of the cylindrical portion 12 serves as a sliding surface that is in sliding contact with a guide pin, for example. The graphite rods 13 extending in the radial direction are embedded in the cylindrical portion 12 of the block body 11 by casting, and a part of these graphite rods 13, here the radial inner end, is inside the cylindrical portion 12. It is exposed on the peripheral surface 15 (sliding surface), and its radial outer end terminates in the middle of the cylindrical portion 12. Here, each graphite rod 13 is composed of a large number of graphite particles of 150 mesh or less bonded by a binder composed of phenol resin, coal tar pitch or the like with a weight ratio of 15% or less. The component is graphitized before the graphite rod 13 is cast into the block body 11. Here, such graphitization of carbon content is performed, for example, by first loading the molded graphite rod 13 into a firing furnace and then heating it to about 700 ° C to 1100 ° C in an oxygen-free atmosphere, Carbonize the carbon content in the furnace, then cool the furnace to about 370 ° C to 400 ° C to prevent oxidation, and then cool it to the atmosphere, and then carry the graphite rod 13 into a graphite furnace in an oxygen-free atmosphere. By heating to 2500 ° C or higher, for example 2500 ° C to 3000 ° C, the carbonized carbon is graphitized, and then, in order to prevent oxidation, the inside of the furnace is cooled to about 370 ° C to 400 ° C and then cooled to the atmosphere. To do.

In manufacturing the guide bush 10 as described above, a mold 21 as shown in FIG. 2 is molded, but in molding such a mold 21, first, the upper frame 22 is not shown. After mounting on the board, a wooden mold (not shown) of a predetermined shape is stored in the upper frame 22, and then the upper frame 22 is filled with casting sand such as self-hardening sand and carbon dioxide sand. Then, the wooden mold is removed from the foundry sand. As a result, the upper mold 23 as a mold segment is molded. When forming the upper mold 23, the sprue 24 and the riser 25 are simultaneously formed. Further, the molding sand as described above is also filled in the lower frame 27 and crushed to mold the lower mold 28 as a mold segment. A ring groove 29 and a plurality of radial grooves 30 extending radially inward from the ring groove 29 are formed on the upper surface of the lower mold 28. Reference numeral 35 denotes a core as a mold segment in the shape of a hollow cylinder, and a part of a plurality of graphite rods 13 extending in the radial direction, that is, a radially inner end is embedded in the outer periphery of the core 35. As a result, the rest of these graphite rods 13 project from the outer circumference of the core 35. Here, the burial depth D of the graphite rod 13 in the core 35 is preferably 3 mm or more. The reason for this is that if the burial depth D is less than 3 mm, the graphite rod 13 may come out of the core 35 due to the flow of molten metal when pouring into the cavity, which will be described later. Then, the core 35 in which such a graphite rod 13 is embedded has the remaining part of the graphite rod 13 inserted into the inner surface of a mold (not shown) of the split mold, and in this state, as described above. It was filled with foundry sand and tamped, and then the mold was removed from the core 35, or the above-mentioned foundry sand was filled and tamped into the mold having a plurality of protrusions formed on the inner surface. After that, the mold frame is removed from the core 35, and then a part of the graphite rod 13 is inserted into each hole formed on the outer periphery of the core 35 by the projection to mold.

Next, the mold 21 is molded by combining the three mold segments described above, that is, the upper mold 23, the lower mold 28, and the core 35. In the mold 21 molded in this way, A cavity 40 having the same shape as the guide bush 10 is formed. Here, the remaining part of the graphite rod 13 partially embedded in the core 35 projects into the cavity 40. Further, the ring groove 29 and the radial groove 30 described above are closed by the upper mold 23 at their upper ends to form a runner 41 communicating with the lower end of the cavity 40. Next, a molten metal of metal, here cast iron, is poured from the sprue 24, and is filled into the cavity 40 through the runner 41. Then, when the cavity 40 is filled with the molten metal, the remainder of the graphite rod 13 protruding from the core 35 is cast by the molten metal. During this pouring, the molten metal is injected into the cavity 40 from its lower end, so that the molten metal does not directly flow into the rest of the graphite rod 13, and as a result, melting loss of the graphite rod 13 is suppressed. At this time, the molten metal comes into contact with the graphite rods 13 and gives an external force, but since each graphite rod 13 is partially embedded in the core 35, it will not slip or come off, To maintain. Further, since the graphite rods 13 are encased in the molten metal, they are heated to almost the same temperature as the molten metal, but the carbon content in the binder of these graphite rods 13 is graphitized as described above. Even when the graphite rod 13 is heated to a high temperature, the carbon content (graphite) in the binder does not burn, and as a result, the graphite rod 13 is cast into the molten metal without burning.

When the cavity 40 is thus filled with the molten metal, the pouring is stopped and the molten metal in the cavity 40 is cooled and solidified to form the block body 11. As a result, the guide bush 10 in which the graphite rod 13 is cast in the block body 11 is formed. Next, after removing the guide bush 10 from the mold 21, the molding sand is removed from the guide bush 10 by shot blasting. At this time, since the hardness of the graphite rod 13 is much smaller than the hardness of the block body 11, the graphite rod 13 is Make sure that 13 is not too shaved by shot blasting and will not be recessed from the inner peripheral surface 15 of the guide bush 10. Next, if necessary, the guide bush 10 is machined, for example, the inner peripheral surface 15 and the outer peripheral surface are ground, and a part of the graphite rod 13, here the radial inner end, is formed on the inner peripheral surface 15 of the guide bush 10. Exposed to (sliding surface).

When the graphite rod 13 is burnt out by the molten metal during pouring, the surface of the graphite rod 13 may be coated with zircon or graphite particles in advance to prevent the burnout. In addition, if it does in this way, the sand removal property of casting sand will also improve. Further, in the above-described embodiment, since the sliding block is the guide bush 10, it has a cylindrical shape with a flange, but in this invention, the sliding block may be a plate-shaped wear plate. Further, in the above-mentioned embodiment, the graphite rod 13 is cylindrical, but in this invention, various shapes such as prismatic can be used, and the sliding block can be penetrated. You can also use it.

[0013]

[Effect of device]

 As described above, according to the present invention, the graphite body that performs the solid lubricating action can be easily cast into the block body made of metal.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing an embodiment of the present invention.

FIG. 2 is a sectional view of a mold for manufacturing a sliding block.

[Explanation of symbols]

 10… Sliding block 11… Block body 13… Graphite body 15… Sliding surface

Claims (1)

[Scope of utility model registration request] 1. A sliding block constructed by embedding a plurality of graphite bodies as a solid lubricant, which are partially exposed at a sliding surface, by burying them in a block body made of a metal. The carbon content in the binder that binds the graphite particles of the graphite body to each other in an oxygen-free atmosphere before casting.
A sliding block characterized by being graphitized by heating above 2500 ° C.