JP2001259822A - Method for lost foam casting of complex sliding member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lost foam casting method by which a complex sliding member, such as a slide base, oil bush, can be manufactured in a high yield without possibilities that a solid lubricator such as graphite pins comes out, even in the case the sliding member is used at high temperature. SOLUTION: An assembling pattern 3 is formed by inserting graphite pins 2 as the solid lubricator into a lost foam pattern 1 having the same shape as a metal-made base body 9, and runner pattern 5 is added to this assembling pattern 3 and both patterns are covered with refractory molding sand 6 containing a facing agent to make a mold 7 with the patterns. The lost pattern mold 8 is prepared by burning and vaporizing the lost foam pattern in the mold with these patterns, and molten metal of base metal is poured while the graphite pins 2 in the inner part of this lost pattern mold 8 are at high temperatures to cast the complex sliding member 10. The graphite pins 2 form groove 4 at the center of the peripheral surface, and the molten metal inserting the graphite pins 2 is made to penetrate into the annular groove 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for casting a composite sliding member such as a slide base, an oilless bush, etc., comprising a metal base and a solid lubricant.

[0002]

2. Description of the Related Art A method of manufacturing a composite sliding member in which a solid lubricating material such as a graphite pin is embedded in a metal base by vanishing casting is known from Japanese Patent Publication No. 7-71735. In this known method, a solid lubricant is fitted into a fitting hole formed in a disappearing model to form a solid lubricant incorporated model, which is buried in molding sand in a casting box, and the molten metal for the base is poured. Hot water, the gas in the casting box was vented, and the vanishing model was vanished with hot water for casting.

[0003]

However, in the known method, defects are likely to occur due to entrainment of combustion gas and cinders in the vanishing model, and when graphite pins are used as a solid lubricant, the temperature of the hot water to be cast becomes sharp. , The shrinkage nest,
Defective products having defects such as pinholes and organization chilling occur frequently, and the yield is low.

In addition, when the conventional composite sliding member is used at a high temperature, there is a possibility that the solid lubricant may not be removed.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and has as its object that there is no casting defect due to the solid lubricant and that the solid lubricant may come off even when used at a high temperature. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of vanishing casting of a composite sliding member.

[0006]

Means for Solving the Problems In order to achieve the above object, a first means adopted by the present invention is to apply a molding sand containing a coating material to a model incorporating a solid lubricant and dry it to form a model-containing mold. Next, there is a casting method in which the disappearing model in the mold is incinerated and the molten metal is poured while the solid lubricant is hot.

[0007] In order to ensure that the solid lubricant is supported by the foundry sand after incineration of the disappearing model, the length of the solid lubricant is 2-3 mm longer than the thickness of the model. Relatively large composite sliding members such as slide bases should not be fixed with the mold in the frame, but relatively small composite sliding members such as OILES bush should be fixed with the back sand with the mold in the frame. Is preferred.

[0008] In the above casting method, the combustion gas and the flammable of the vanishing model do not come into contact with the molten metal of the base material.
There is no risk of defects occurring due to entrainment of combustion gas or cinders in the casting. Since the solid lubricant is hot at the time of pouring, the temperature of the molten metal does not rapidly cool due to contact with the solid lubricant, so defects such as hot boundaries, shrinkage cavities, pinholes, and organization chilling occur in the casting. There is no fear. Therefore, the yield of castings is high and the quality is improved.

The second means is that an annular groove is formed in the center of the peripheral surface of the solid lubricant. The base metal that encloses the solid lubricant by casting enters the annular groove and prevents the solid lubricant from coming out of the composite sliding member after casting. There is no risk of escape from the base metal. It is desirable that the annular groove has a width of 1 mm or more and a depth of 1 mm or more.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described based on a first embodiment shown in FIG. The composite sliding member of the first embodiment is a relatively large flat slide base.

FIG. 1 (a) is a view showing a cross section of a graphite pin built-in model formed in a first step, FIG. 1 (b) is a view showing a cross section of a model-containing mold formed in a second step, and (c).
Is a view showing a cross section of the model disappearing mold in the third step, (d) is a view showing a cross section of the slide base immediately after casting in the fourth step,
(E) is a diagram showing a cross section of the slide base after finishing in the fifth step.

As shown in FIG. 1, in a first step, a built-in model 3 in which graphite pins 2 are inserted into a foamed polystyrene vanishing model 1 having the same shape as the slide base substrate is insert-molded by a molding machine. Both ends of the numerous graphite pins 2 protrude from the front and back surfaces of the vanishing model 1 by about 2 mm. The graphite pin 2 has an annular groove 4 having a width of 2 mm and a depth of 2 mm at the center of the peripheral surface.

In a second step, a runner model 5 is added to the built-in model 3, and a refractory molding sand 6 containing a coating material is applied to the entire surface of both models so as to have a thickness of 2 to 15 mm and dried. The mold containing the model 7 shown in FIG. 1B is formed.

As shown in FIG. 1 (c), in the third step, the disappeared model in the mold containing the model is burnt and vaporized by a gas burner or the like, and is eliminated to obtain a model disappearing mold 8. At this time, since the graphite pin 2 has both ends inserted into the refractory molding sand 6 by about 2 mm, there is no possibility that the graphite pin 2 will shift or fall.

As shown in FIG. 1C, while the graphite pin 2 is at a high temperature, a fourth step of pouring a molten metal serving as a base of the slide base into the model disappearing mold 8 and casting is performed. At this time, since the vanishing model has disappeared, there is no possibility that the combustion gas and the flammable of the vanishing model will be involved and cause a defect. Also, since the hot graphite pin 2 does not rapidly cool the hot water,
There is almost no possibility that defects such as shrinkage cavities, pinholes, hot water boundaries, and tissue chilling may occur. Therefore, a cast product of high yield and good quality is manufactured.

The slide base 10 after casting and before finishing
As shown in FIG. 1 (d), the graphite pins 2 project from the front and back surfaces of the base 9, but as shown in FIG. 1 (e), the slide base after finishing in the fifth step is finished. Both end portions of the graphite pin 2 are flush with the front and back surfaces of the substrate 9.

Since the base metal enters the annular groove 4 of the graphite pin 2 of the slide base 10 by casting,
Even if the slide base 10 is used at a high temperature, there is no possibility that the graphite pins 2 will fall out of the base 9.

[0018]

Next, a second embodiment will be described with reference to FIG. The composite sliding member of the second embodiment is a relatively small cylindrical oilless bush.

FIG. 2A is a cross-sectional view of a vanishing model in which a fitting hole is formed after molding in the first step, and FIG.
FIG. 3C is a cross-sectional view of a model incorporating the graphite pin formed in the process, FIG. 4C is a cross-sectional view of the mold containing the model formed in the third process, and FIG. Is a cross-sectional view, (e) is a cross-sectional view of the model vanishing mold in the fifth step, (f) is a cross-sectional view of an oilless bush after the casting in the sixth step, and (g) is a diagram of the seventh step. It is a figure which shows the oiles bush after finishing in cross section.

In a first step, a foamed polystyrene cylinder is injection-molded, and then a fitting hole 1 into which a graphite pin is fitted.
2, a vanishing model 11 having the same shape as the metal base of the oilless bush shown in FIG. 2A is formed.

In the second step, the fitting hole 12
Then, the graphite pin 2 is inserted to form a built-in model 13.
The graphite pin 2 is longer than the thickness of the vanishing model 11 by 3 mm or more, and both ends protrude from the vanishing model 11 by 1 mm or more as shown in FIG.

In the third step, a runner model 15 of expanded polystyrene is added to the built-in model 13 and, as shown in FIG. 17 is molded. The thickness of the refractory casting sand 6 containing the coating material is 2 to 15 mm or more.

In the fourth step, as shown in FIG. 2D, a mold 17 containing a model is put into a frame 14 and fixed with a back sand 16 such as dry sand, green mold sand, self-hardening sand, or brick.

Next, in a fifth step, as shown in FIG. 2 (e), the expanded polystyrene model in the mold containing the model is burned and vaporized to form a model disappearing mold 18, and the graphite pins 2 inside are heated by combustion. In the meantime, the sixth step of pouring the molten metal and casting the oilless bush is performed.

As shown in FIG. 2 (f), both ends of the graphite pin 2 of the oilless bush 20 after casting and before finishing project from the inner and outer peripheral surfaces of the base 19, as shown in FIG. 2 (g). Both ends of the finished graphite pin 2 are flush with the inner and outer peripheral surfaces of the base 19 of the oilless bush 20.

Since the graphite pin 2 has an annular groove 4 in the center of the peripheral surface as in the above-described embodiment, the base metal surrounding the graphite pin 2 at the time of casting enters the annular groove 4 and holds the graphite pin 2 firmly with the base 19. I do. Therefore, even if the oilless bush 20 is used at a high temperature, there is no possibility that the graphite pin 2 will fall out of the base 19.

[0027]

As described above, the method of the present invention is different from the conventional method in which a lost model is burned and vaporized with molten metal, and the lost model is burned and vaporized by a gas burner or the like, and is fitted into a fitting hole of the lost model. This is a casting method in which the combined lubricant is heated and the molten lubricant is poured into the solid lubricant while the temperature is high.Therefore, the combustion gas of the vanishing model is entrained in the casting to cause defects, or the molten metal becomes solid. Since there is little risk of causing defects such as shrinkage cavities, pinholes, hot water boundaries, and chilled structures due to rapid cooling by the lubricant, it is possible to produce a high-yield, high-quality composite sliding member with an excellent effect. Play.

In the method of the present invention, an annular groove is formed at the center of a peripheral surface of a solid lubricant inserted into a fitting hole of a metal substrate of a composite sliding member, and the base metal for enclosing graphite by casting is formed in the annular shape. Since the solid lubricant is prevented from coming out of the base by being inserted into the groove, even when the composite sliding member is used at a high temperature, there is an extraordinary effect that there is no possibility that the solid lubricant comes off the base.

[Brief description of the drawings]

FIGS. 1A and 1B are views showing a first embodiment of the present invention, in which FIG. 1A is a cross-sectional view of a built-in model formed in a first step, and FIG. Cross section of the
(C) is a sectional view of the model disappearing mold in the third step of the first embodiment,
(D) is a sectional view of the slide base immediately after casting in the fourth step of the first embodiment, (e) is a sectional view of the slide base after finishing in the fifth step of the first embodiment,

FIGS. 2A and 2B are views showing a second embodiment, in which FIG. 2A is a cross-sectional view of a vanishing model in the first step, FIG. 2B is a cross-sectional view of a built-in model in the second step of the second embodiment, and FIG. Sectional view of the mold containing the model in the third step of the embodiment, (d) Sectional view of the mold containing the frame of the fourth step in the second embodiment, (e) Section showing the model disappearing mold in the fifth step of the second embodiment. (F) Sectional view of the oilless bush after casting in the sixth step of the second embodiment, (g) Sectional view of the oilless bush after finishing in the seventh step of the second embodiment,

[Explanation of symbols]

 1: vanishing model 2: graphite pin 3: built-in model 4: annular groove 5: runner model 6: refractory molding sand 7: model containing mold 8: model disappearing mold 9: base 10: slide base 11: vanishing model 12: fitting Mating hole 13: Built-in model 14: Frame 15: Runner model 16: Back sand 17: Model containing mold 18: Model disappearing mold 19: Base 20: OILES bush

Claims (3)

[Claims] 1. A vanishing casting method for a composite sliding member (10, 20) comprising a metal base (9, 19) and a solid lubricant (2) inserted into a fitting hole of the base. The solid lubricant is inserted into the fitting hole of the vanishable vanishing model (1, 11) having the same shape as the above to form the built-in model (3, 13), and the runner model (5, 15) is inserted into the built-in model. In addition, both models are covered with a refractory molding sand (6) containing a coating material to form molds (7, 17) with a model. 18)
Wherein the solid lubricant inside the model vanishing mold is cast by injecting molten metal of the base metal while the temperature is high. 2. The method according to claim 1, wherein the mold containing the model (17) is placed in a frame (14) and fixed with a back sand (16). 3. The method according to claim 1, wherein the solid lubricant has an annular groove in the center of the peripheral surface.