JPH10235451A - Mold for partial precision casting, and casting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the man-hour of the machining, and to reduce the cost by loading a precision mold on a base, placing a lost foam pattern for full mold on the precision mold and surrounding it by a peripheral molding flask, and filling and ramming the molding sand so that a sprue is formed in the peripheral molding flask. SOLUTION: A pattern 10 for a precision part is placed on a molding board 30 and surrounded by a molding flask 40, the material for precision casting is poured in the molding flask 40, and the obtained precision mold 20 is released and hardened. The precision mold 20 is placed on a base 35, and a lower side of a lost foam pattern 50 is lapped on the upper surface side of the mold 20, and surrounded by a peripheral molding flask 45 so that the pattern 50 is located at the center. A sprue 51 is provided on an upper surface of the pattern 50. The casting sand 60 is filled in the peripheral molding flask 45, and the lost foam pattern 50 is embedded and rammed in the casting sand 60. The molten metal 80 is poured into the foam wax pattern 50 of the full mold from the sprue formed by removing a gate stick 51, and when the lost foam pattern 50 is replaced by the molten metal 80, the intended casting 90 is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to improve the dimensional accuracy by manufacturing only the high-precision mold with a precision mold material such as a show process, and manufacturing the low-precision mold with a full mold. The present invention relates to a partially precision casting mold and a casting method that reduce the processing load.

[0002]

2. Description of the Related Art Heretofore, there have been known several casting methods using a mold using a vanishing model. Among them, there is a full mode method proposed by Schroier of the United States and put into practical use by Wit Moser and the like in Germany. Yes, it is widely used for casting of press dies and the like. In this casting method, as shown in FIG. 1, a model 1a made of plastic such as expanded polystyrene is embedded in a casting sand 60 to form a mold 1, and a molten metal 80 is injected as it is without removing the model 1a. In this method, the model 1a is decomposed and vaporized and eliminated by the heat of the molten metal 80, and a portion of the model 1a is replaced with the molten metal 80 and cooled to produce a casting 90. In addition, 35 is a base and 45 is a surrounding frame.

[0003] In this full molding method, operations such as division of a mold, alignment of a mold, molding of a core, insertion of a core, and the like can be omitted. You. Furthermore, the use of plastics such as expanded polystyrene makes the model material inexpensive and improves workability, so that the number of steps is reduced and the time required for casting is greatly reduced.

[0004] However, expanded polystyrene has the property of shrinking over time after foam molding. Therefore, it is necessary to allow for this amount of shrinkage in determining the dimensions of the mold for the model. In addition, there is a disadvantage that part of carbon generated during decomposition and vaporization in expanded polystyrene adheres to the surface of the casting. From the above, castings manufactured by the full mold casting method have low dimensional accuracy, and for example, it is necessary to provide an allowance of 10 to 15 mm for a main part that requires high dimensional accuracy. It is necessary to perform machining three times, that is, intermediate finishing and finishing, which requires a large number of man-hours for machining, resulting in a high cost.

[0005]

A problem to be solved is that a casting manufactured by a conventional full mold casting method has a low dimensional accuracy and requires a margin of 10 to 15 mm for a main part requiring high dimensional accuracy. It is necessary to provide, therefore, it is necessary to perform a total of three times of machining of roughing, semi-finishing, and finishing, which requires a great deal of man-hours for machining, which increases the cost, The present invention
By solving the above problems, the casting part requiring high dimensional accuracy is constituted by a precision casting method such as a show process, and the casting part of the low precision part is constituted by a full molding method, thereby achieving high precision. It is an object of the present invention to provide a partially precision casting mold and a casting method in which the dimensional accuracy of a required portion of a casting is increased and the burden of machining is significantly reduced.

[0006]

Means for Solving the Problems As shown in FIGS. 2 to 4, the partial precision casting mold according to the first invention mounts the precision mold 20 on a base 35, and further places the precision mold 20 on a precision mold 20 for full molding. Place the model 50 and surround it with the surrounding frame 45,
The casting sand 60 having the gate 61 formed in the surrounding frame 45 is filled and solidified.

In the partial precision casting method according to the second invention, a precision casting material such as a show process is injected into a mold frame 40 having the precision part model 10 placed on the bottom, released from the mold, and fired. And a corresponding lower surface of a disappearing model 50 made of plastic such as expanded polystyrene is superimposed on the upper surface of the precision mold 20 disposed at the bottom of the peripheral frame 45, and a casting sand 60 is formed in the peripheral frame 45. To fill the solidification mold by filling the disappearance model 50 to form a full mold mold 70 and inject the molten metal 80 into the disappearance model 50 from the gate of the full mold mold 70, and decompose and vaporize the disappearance model 50 by the heat of the molten metal 80. It consists of a step of replacing the disappearance model 50 with the molten metal 80 and a step of solidifying the molten metal into a casting 90.

According to the present invention, although the burden of manufacturing the precision mold 20 is slightly increased, the dimensional accuracy of the high precision portion of the casting formed by the precision mold 20 having high dimensional accuracy is 1 to 2 mm. Only one machining is enough to finish that part, and the man-hour for machining is greatly reduced.
The cost is reduced accordingly.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 2 to 4. For example, in manufacturing a casting 90 such as a press die, a mold of a portion requiring high dimensional accuracy is used. 20 is manufactured using a precision mold material such as a show process, and the remaining low-precision mold 70 is manufactured by a full mold process.

First, a method of manufacturing the precision mold 20 will be described. As shown in FIG. 4, the precision part model 10 is placed on a surface plate 30, surrounded by a mold frame 40, and the precision part model 10 is closed. Then, a material for precision casting such as a show process is poured into the mold 40, and then the precision mold 20 thus obtained is released and solidified.

Next, a method of manufacturing the full mold 70 will be described. As shown in FIG.
Is placed on the base 35, the lower surface of the disappearing model 50 made of plastic such as expanded polystyrene is overlapped on the upper surface side of the precision mold 20, and the surrounding frame 45 is further surrounded so that the disappearing model 50 is located at the center. The gate 51 is attached to the upper surface of the vanishing model 50. Foundry sand 6 in the surrounding frame 45
0 and the disappearance model 50 is buried in the foundry sand 60 and solidified.

The molten metal 80 is poured into the vanishing model 50 of the full mold 70 formed as described above from the gate formed by removing the gate 51. When the disappearing model 50 is decomposed and vaporized and disappears by the heat of the molten metal 80, and the disappearing model 50 is replaced with the molten metal 80 and cooled, the desired casting 9
0 is obtained.

At this time, since the surface of the mold forming the surface of the high precision portion 91 of the casting 90 is the upper surface of the precision mold 20, the dimensional accuracy of the surface is high. Therefore, the high precision part 91 of the casting 90
Dimensional accuracy is 1-2 mm, and that part finish is 1 mm
Only one machining is sufficient, the man-hour for machining is greatly reduced, and the cost is correspondingly reduced.

[0014]

Since the present invention is configured as described above, the surface of the main part 91 of the casting 90 requiring high dimensional accuracy is
It is formed by the upper surface of the precision mold 20 having high purity and high dimensional accuracy. Therefore, the dimensional accuracy of the high-precision part 91 of the casting 90 to be manufactured is 1 to 2 mm, and the finishing of that part is sufficient by only one machining, so that the number of man-hours for machining is greatly reduced, and the cost is accordingly reduced. Reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a conventional example.

FIG. 2 is a sectional view showing a part of the embodiment of the present invention.

FIG. 3 is a sectional view showing the obtained casting.

FIG. 4 is a sectional view showing a processing procedure according to the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 mold 1a model 10 model for precision part 20 precision mold 30 surface plate 35 base 40 formwork 45 peripheral frame 50 vanishing model 51 sprue bar 60 molding sand 61 spout 70 full mold mold 80 molten metal 90 casting 91 high precision part

Claims (2)

[Claims] 1. A precision mold (20) is placed on a base (35), and a vanishing model (50) for full molding is further placed on the precision mold (20), and is surrounded by a peripheral frame (45). Casting sand (60) having a gate (61) formed in it
Partial precision casting mold that is filled and solidified. 2. A precision mold manufactured by injecting a material for precision casting such as a show process into a mold (40) having a model for a precision part (10) at the bottom, releasing, and firing. Process and the precision mold (2) placed at the bottom of the surrounding frame (45)
The corresponding lower surface of the vanishing model (50) made of plastic such as expanded polystyrene is overlapped on the upper surface of (0), and the casting frame (60) is filled and solidified in the surrounding frame (45) to embed the vanishing model (50). Step of making a full mold mold (70) and pouring a molten metal (80) into a vanishing model (50) from a gate of the full mold mold (70), and heating the vanishing model (50) by heat of the molten metal (80). A partial precision casting method comprising the steps of: decomposing and evaporating and disappearing; replacing the disappearance model (50) with a molten metal (80); and solidifying the molten metal into a casting (90).