JPH09314308A - Vanishing model casting method - Google Patents

Abstract

(57) Abstract: A through hole of a casting is formed with high accuracy. SOLUTION: A pipe 12 is embedded in a required position of a vanishing model 10 formed by using expanded polystyrene so as to penetrate a required number of pipes. A model of a sprue 14, a runner 16, a weir 18, and a riser 20 formed of expanded polystyrene is adhered to the disappeared model 10. The mold 22 having the vanishing model 10 in which the pipe 12 is integrally embedded is positioned inside is filled with molding sand 24 to obtain a mold 26 in which the vanishing model 10 is buried. When the molten metal is cast from the sprue 14 of the mold 26, the molten metal is melted by the sprue 14, the runner 16 and the weir 1.
While burning the model No. 8 to reach the bottom of the disappearing model 10, the model 10 burns and is sequentially replaced from the lower side. At this time, since the pipe 12 embedded in the disappearance model 10 does not disappear, a casting in which the pipe 12 is integrally cast is cast.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vanishing model casting method, and more particularly, by burying a pipe in the vanishing model in advance, a casting having through holes formed at accurate positions can be cast. The present invention relates to an extinction model casting method.

[0002]

2. Description of the Related Art A vanishing model casting method (full molding method) is known as one of casting methods for producing a casting having a required shape. In this method, a model of a product to be cast is molded from expanded polystyrene that disappears at a high temperature, and the disappeared model is embedded in molding sand to form a mold. Then, when the molten metal is cast into this mold, the vanishing model is burned by the molten metal to be gasified and vanished, and the molten metal is replaced and filled at that location to obtain a casting.

In casting products used in various industrial fields, there is a demand for forming through holes in the required portions thereof. In this case, forming the through hole by drilling after casting the casting has a drawback that the number of post processes is increased and the manufacturing efficiency is lowered. Moreover, it is difficult to accurately form the through hole with a small diameter or a long through hole by drilling. Therefore, castings having through holes are cast by the above-described disappearing model casting method. That is, a through hole is formed at a required position of the disappearance model, and when the disappearance model is buried in the foundry sand, the inside of the through hole is also filled with sand, so that the molten metal cast in the mold is It replaces the vanishing model excluding the inside of the through hole, whereby a casting having the through hole is cast.

[0004]

In the method of forming through holes in a casting by forming through holes in the vanishing model in advance,
Since the model disappears when the molten metal is cast, the thin sand column filled in the through hole is deformed or loses its shape due to the gas pressure generated from the molten metal or the model or the molten metal pressure, and the through hole is deformed. There was a problem that it was blocked on the way. In addition, since sand is used, the inner surface of the through hole becomes rough, and a product requiring smoothness on the inner surface of the through hole requires a post-process, which increases the number of steps. Furthermore, high dimensional accuracy of the through holes could not be obtained.

Therefore, it has been proposed to mix the binder with the sand filled in the holes of the vanishing model to solidify the sand, but since the diameter of the column of sand filled in the holes is small,
It has not been possible to prevent deformation and deformation. Furthermore, there is a possibility that a new problem may occur that the sand is sintered in the through holes.

[0006]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above-mentioned problems inherent in the above-mentioned conventional techniques, and has been proposed to suitably solve the problems. It is possible to form a through hole of a casting with high accuracy. It is an object of the present invention to provide a disappearance model casting method.

[0007]

[Means for solving the problems] To overcome the above-mentioned problems,
Disappearance model casting method according to the present invention in order to preferably achieve the intended purpose, by casting the molten metal in a mold molded by burying the disappearance model in the molding sand, the disappearance model is burned to disappear and melted. In a vanishing model casting method of casting a casting by replacing, in a state where a pipe is previously embedded in a required position of the vanishing model, the vanishing model is buried in casting sand to mold, and the molten metal is cast into the obtained mold. According to the present invention, the pipe is integrally cast to cast a casting.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Next, with reference to the accompanying drawings, a description will be given of an embodiment in which a moving block, which is a component of a linear guide device, is produced by using the disappearance model casting method according to the present invention. To do.

FIG. 1 is a linear guide device to which the present invention is applied.
1 is a schematic view of a (linear motion guide device), in which reference numeral 1 denotes a track rail, and a ball rolling surface on which a ball 2 rolls is formed on the track rail 1 and each rolling surface is formed. Respectively form an angle of 45 ° with the radial direction and the thrust direction. The track rail 1 is fixed to a fixed part (not shown) such as a bed by a fixing bolt. Reference numeral 3 indicates a slider that moves along the track rail 1, and the slider 3 includes a moving block 28 that sandwiches a large number of balls 2 together with the track rail 1 and front and rear end surfaces of the moving block 28. A pair of lids 5 attached to the
It is composed of

The moving block 28 is formed in a saddle shape straddling the track rail 1, and a ball rolling surface of the track rail 1 is formed on the inner surface side of the pair of sleeve portions 28b, 28b hanging from both sides of the horizontal portion 28a. The ball 2 is sandwiched together 4
The strip load rolling surface is formed. Also, each of the sleeve portions 28
In b, the ball return hole 6 is provided at a position corresponding to each load rolling surface.
Have penetrated each.

Next, a method of making the moving block shown in the figure by using the vanishing model casting method will be described. A desired model of the moving block 28 is molded using expanded polystyrene, and is embedded in the vanishing model 10 at a position corresponding to the ball return hole 6 of the moving block 28 so as to penetrate the pipe 12 (see FIG. 2). The pipe 12 is made of an appropriate metal material that can withstand the high temperature during casting of the molten metal, and both ends in the longitudinal direction of the pipe 12 are the disappearing model 10.
From the end of each of them, respectively, by the required length (for example, 50 mm). Further, the vanishing model 10 includes a sprue 14, a runner 16, a weir 18, and a riser 20 formed of expanded polystyrene.
The model of is glued. The weir 18 is the disappearance model 10
At the bottom of the pipe 12, the pipe 12 is separated from the position where the pipe 12 is arranged, and the direction in which the molten metal flows from the weir 18 is
Is connected in a position substantially parallel to.

As shown in FIG. 3, the vanishing model 10 in which the pipe 12 is integrally embedded is positioned inside the form 22, and zircon or chromite containing no binder is contained inside the form 22. Foundry sand such as sand or coal grain 2
By filling with 4 and molding, a mold 26 in which the disappearing model 10 is buried is obtained. At this time, the extending portions 12 a, 12 a of the pipe 12 extending from the end portion of the vanishing model 10 are firmly held by the molding sand 24. At the time of molding with the molding sand 24, a reduced pressure molding method (also referred to as a V process) in which the molding sand 24 is tightly bonded by utilizing atmospheric pressure to hold a fixed shape as the mold 26 and to secure strength is suitable. Adopted. It is also possible to mold the casting mold 26 by hardening the foundry sand 24 with a binder.

When the molten metal is cast from the sprue 14 of the mold 26 obtained as described above, the molten metal reaches the bottom of the vanishing model 10 while burning the models of the sprue 14, the runway 16 and the weir 18. The model 10 burns and is sequentially replaced from the lower side to be filled. At this time, since the pipe 12 embedded in the disappearance model 10 does not disappear, the moving block 28 as a casting in which the pipe 12 is integrally cast is cast. Then, from the moving block 28, the sprue 14, the runner 16, the weir 18, the riser 20 and the extension 12 of the pipe 12 are provided.
By cutting a and 12a, as shown in FIG.
A product is manufactured in which the pipe 12 functions as a through hole. The pipe 12 does not easily deform or lose its shape like a conventional sand column due to the molten metal pressure during casting of molten metal and the gas pressure generated when the model 10 burns.
Moreover, since the extending portions 12a, 12a of the pipe 12 protruding from the end of the disappearing model 10 are firmly held by the casting sand 24, the pipe 12 may be displaced even if the disappearing model 10 disappears. It does not deform. Therefore, the pipe 12 of the obtained moving block 28, that is, the through hole
The (corresponding to the ball return hole 6) is formed at an accurate position. The molten metal is cast into the mold 26 by a reduced pressure casting method in which the pressure inside the mold 26 is reduced and the molten metal is injected using the atmospheric pressure. By the way, if the extending portions 12a, 12a of the pipe 12 are short, when the disappearing model 10 disappears, the pipe 12 is displaced from a predetermined position or the pipe 1
It is recommended that the length of the extending portions 12a, 12a be 30 mm or more, preferably 50 mm or more, because the molten metal flows into the inside of the pipe 2.

As described above, by burying the pipe 12 in advance in the position of the vanishing model 10 corresponding to the formation position of the through hole in the moving block 28, the through hole is accurately formed in the obtained moving block 28. can do.
Further, since the inner surface of the pipe 12 is smooth, even if the inner surface of the through hole is required to be smooth, it is possible to improve the manufacturing efficiency because no processing is required in the post process. Since the weir 18 is provided at the bottom of the vanishing model 10 away from the position where the pipe 12 is arranged, the molten metal is cast by a push-up method, so that the molten metal flowing from the weir 18 locally melts the pipe 12. Can be prevented.

When casting the moving block 28, there is a risk that the pipe 12 will be melted and damaged by the molten metal. To prevent this, the inside of the pipe 12 is filled with sand 30 as shown in FIG. deep. This increases the heat capacity of the entire pipe, making it less likely to cause melting loss,
Even if melting damage occurs in the pipe 12, it is possible to prevent the molten metal from entering the inside of the pipe. Therefore, the through hole is secured by removing the sand 30 from the inside of the pipe 12 after casting the pipe 12.

Further, since the material of the pipe 12 can be appropriately selected, when the moving block base material is a material that rusts, for example, by using a stainless steel pipe 12, rust is generated in the through hole. Can be prevented. That is, it is not necessary to perform rust prevention treatment in the through holes in the subsequent process, and the number of manufacturing processes can be reduced.

In the embodiment, the case where the pipe is extended from the end of the vanishing model has been described, but the length of the pipe may be set to be the same as the length of the vanishing model. Also in this example, the pipe is not deformed or moved by the molten metal or the gas pressure generated from the model or the molten metal pressure, and the through hole can be formed with high accuracy. The method of casting the molten metal in the mold is not limited to the vacuum casting method, and other casting methods can be appropriately adopted.

[0018]

As described above, according to the vanishing model casting method of the present invention, by burying the pipe in the vanishing model in advance, it is possible to form through holes at accurate positions of the obtained casting. . Further, since the pipe can be formed with high accuracy, the dimensional accuracy of the through hole of the obtained mold becomes good. Moreover, since the inner surface of the pipe can be made smooth, the inner surface of the through hole is also made smooth, which has the advantage of not requiring processing in a later step. Further, by extending both ends in the longitudinal direction of the pipe from the end of the vanishing model, and holding the extending part by the foundry sand, it is possible to reliably prevent movement of the pipe during casting of the molten metal, A highly accurate through hole can be formed. That is, since it is not necessary to make corrections in the subsequent steps, the number of steps can be reduced and complicated labor can be saved, and the manufacturing efficiency can be improved.

Further, by casting the molten metal while the pipe is filled with sand, it is possible to prevent melting damage to the pipe and prevent rough skin. Further, as the material of the pipe, a material different from the material of the casting base material can be appropriately selected, so that it is possible to form a through hole in which rust does not occur, for example.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a linear guide device using a moving block cast by a vanishing model casting method according to an embodiment of the present invention.

FIG. 2 is a schematic perspective view showing a vanishing model used in the vanishing model casting method according to the embodiment of the present invention.

FIG. 3 is an explanatory view showing a mold in which the disappearance model according to the example is buried in foundry sand.

FIG. 4 is a schematic perspective view showing a moving block cast by a mold according to an embodiment.

FIG. 5 is an explanatory view of a main part showing a state in which the inside of the pipe of the vanishing model according to the embodiment is filled with sand.

[Explanation of symbols]

 10 Disappearance model 12 Pipe 12a Extension part 24 Foundry sand 26 Mold 28 Moving block (casting) 30 Sand

Claims (7)

[Claims] 1. A casting in which the disappearance model (10) is buried in a casting sand (24) and the molten metal is cast into a casting mold (26), whereby the disappearance model (10) is burned to disappear and replaced with the molten metal. In the disappearance model casting method of casting (28), the disappearance model (10) is buried in the casting sand (24) in a state where the pipe (12) is embedded in advance at a required position of the disappearance model (10) to perform molding. Then, a molten metal is cast into the obtained mold (26) to cast a cast product (28) in which the pipe (12) is integrally surrounded, so that the disappearance model casting method is characterized. 2. Both ends of the pipe (12) in the longitudinal direction are extended from the ends of the vanishing model (10) by a required length, and the extension portions (12a, 1a)
2. The method according to claim 1, wherein 2a) is held by foundry sand (24).
The disappearing model casting method described. 3. The extension portion (12a, 12a) of the pipe (12) is provided with three
The vanishing model casting method according to claim 2, wherein the method is 0 mm or more. 4. The vanishing model casting method according to claim 1, wherein the molten metal is cast while the pipe (12) is filled with sand (30). 5. The vanishing model casting method according to claim 1, wherein the molten metal is cast by a reduced pressure casting method. 6. The vanishing model casting method according to claim 1, wherein the material of the pipe (12) is different from the material of the casting (28). 7. The casting is a moving block (28) of a linear motion guide device, and the pipe (12) is the moving block (2).
8. The method for casting a disappearing model according to claim 1, wherein the ball returning hole (6) is arranged at a position corresponding to the ball returning hole (6).