JPH09300045A - Mold making method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molding method capable of firmly hardening the molding sand at the peripheral part of a mold near the inner surface of a molding flask liable to insufficiently harden the molding sand and the lower end part of the mold near the inner and the outer surfaces of a pattern. SOLUTION: This molding method consists of a process for charging molding sand, a process for pre-compressing the molding sand for each part by inserting and pushing down thin plate bodies 10 and a bar-like body 11 simultaneously toward a pattern plate 3 from the upper part of the molding sand to the inner surface of the molding flask and the inner and outer side surfaces of the pattern, and process for pressing the whole molding sand by acting the pressure of compressed gas on the upper surface of the molding sand.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention applies a pressure of a compressed gas to the upper surface of a molding sand put in a space defined by a pattern plate having a pattern mounted on the upper surface and a casting frame. The present invention relates to a method for molding a mold.

[0002]

2. Description of the Related Art Conventionally, in the molding of a mold by the action of the pressure of compressed gas as described above, the lower end of the peripheral edge of the mold close to the inner surface of the mold, especially the lower corners of the mold close to the corners of the mold and the inner and outer surfaces of the pattern. There is a tendency that the mold clamping of the parts, especially between the patterns or the pocket part is insufficient. This is because when the molding sand is put into the molding flask, the sand density in the portion close to the molding wall inner wall tends to be small, and the pressing of the molding sand, especially the pattern inner and outer surfaces and the molding wall inner wall surface. This is because the pressing force is difficult to be transmitted to the molding sand in this portion due to the friction of the molding sand.
A mold having such a part with poor mold clamping is apt to lose its shape and is easily deformed at the time of pouring, so that a sound casting with good dimensional accuracy cannot be obtained. For this reason, the pressure of the compressed gas used to obtain sufficient mold clamping in the mold is made higher or the pressure of the compressed gas is made to act more rapidly on the upper surface of the casting sand.

[0003]

However, when increasing the pressure of the compressed gas applied to the upper surface of the foundry sand as described above, it is necessary to make the apparatus more robust in consideration of the pressure resistance of the apparatus. In addition, if the pressure of compressed gas acts more rapidly on the top surface of the molding sand, the valve structure must be large and complicated, and the molding sand moves more rapidly, which can cause cracks in the molding mold. There were problems such as increasing the number. The present invention has been made in view of the above-mentioned problems, and the mold peripheral edge lower end portion and / or pattern near the inner surface of the casting frame where the mold clamping of the foundry sand tends to be insufficient.
It is an object of the present invention to provide a method for molding a mold by improving the mold clamping of the lower end of the mold close to the inner and outer surfaces of the mold.

[0004]

In order to achieve the above object, the first mold making method in the present invention is to install a casting frame on the upper part of a pattern plate having a pattern attached to the upper surface, The step of introducing the molding sand into the space defined by the pattern plate and the molding frame, and at the upper position with a slight distance from the inner surface of the molding frame and / or the inner and outer surface of the pattern. A step of precompressing the molding sand near the inner surface of the molding frame and / or near the inner and outer surfaces of the pattern by inserting and pushing the installed thin plate member from above the molding sand toward the pattern plate. And a step of extracting the thin plate body from the molding sand and then applying a pressure of compressed air to the upper surface of the molding sand to compress the entire molding sand. In the second mold making method of the present invention, a casting frame is placed on the upper part of a pattern plate having a pattern attached to the upper surface thereof, and the space is defined by the pattern plate and the casting frame. In the step of introducing the molding sand, a thin plate body and a rod-shaped body, which are arranged at an upper position with a slight gap to the inner surface of the flask and / or the inner and outer surfaces of the pattern, are simultaneously provided from above the molding sand. A step of precompressing the molding sand near the inner surface of the molding frame and / or near the inner and outer surfaces of the pattern by relatively pressing down the molding plate toward the pattern plate; and the thin plate body and the rod-shaped body from the molding sand. It is characterized by comprising the step of compressing the entire foundry sand by applying a pressure of compressed gas to the upper surface of the foundry sand after withdrawing.

[0005]

Embodiments of the present invention will be described below in detail with reference to the drawings. A pattern plate 3 having a pattern 2 attached to the upper surface thereof is placed on the base 1, and a casting frame 4 and a filling frame 5 are stacked and placed on the pattern plate 3.
A space is defined by the pattern plate 3, the casting frame 4 and the fill frame 5. A concave pocket 2A is formed in the center of the pattern 2. On the other hand, above the base 1, a mounting plate 7 which is connected to a piston rod 6 of a cylinder (not shown) and can be moved up and down is communicated with a compressed air source P via an opening / closing valve 8 and can be pressed against the upper part of the filling frame 5. The cover member 9 and the cover member 9 are installed so that they can be put in and taken out. On the lower surface of the mounting plate 7, an annular thin plate member 10 and the pattern which are formed to be slightly smaller than the inner surfaces of the casting frame 4 and the filling frame 5.
A rod-shaped body 11 that can be inserted into the pocket portion 2A of the connector 2 is attached. The height of the thin plate member 10 and the height of the rod-shaped member 11 are substantially the same as the heights of the casting frame 4 and the filling frame 5 that are stacked, and the rod-shaped member 11 is slightly shorter. Further, the lower end portion of the thin plate member 10 has a slightly different height and may be corrugated.

In this state, the foundry sand S is put into the space defined by the pattern plate 3, the casting frame 4 and the filling frame 5. Next, the mounting plate 7 to which the annular thin plate member 10 and the rod-shaped member 11 are attached is lowered by the operation of the piston rod 7, and the thin plate member 10 and the rod-shaped member 11 are inserted into the molding sand S and pushed down to move the thin plate member 10. When the lower end reaches a position slightly above the pattern plate 3 and the rod-shaped body 11 reaches a position slightly above the pocket portion 2A, the lowering is stopped. (See FIG. 1) As a result, the lower end peripheral portion and the pocket portion 2 near the casting frame 4 are formed.
The foundry sand S of A is precompressed. Next is the piston rod 6
Is reversely operated to pull out the thin plate member 10 and the rod-shaped member 11 from the foundry sand S, and then the cover member 9 is covered with the filling frame 5 as shown in FIG.
After the pressure is applied to the upper portion of the molding sand S, the on-off valve 8 is opened and the pressure of the compressed gas is applied to the upper surface of the molding sand S to compress the entire molding sand to mold a mold having a good mold closure as a whole.

Next, another embodiment of the thin plate member 10 and the rod-shaped member 11 will be described with reference to FIGS. 4 and 5.
As can be seen from the above, the thin plate member 10 is provided corresponding to the outer side of the pattern 2, and the rod-shaped member 11 corresponds to the pocket portion 2A and the four corners of the inside of the casting frame 4 and the fill frame 5 and corresponds to the pocket portion 2. The body 11 is formed in the shape of a round bar, and the bar-shaped body 11 corresponding to the four inner corners of the frame is formed in a chevron shape. Therefore, in this case, the pocket portion 2
The outer peripheral edges of A and the pattern plate 2 and the four corners of the casting frame 4 are pre-compressed. Further, in addition to the above-described embodiment, the thin plate member 10 may not be a continuous annular member but a large number of strip members may be arranged at a slight interval, and the rod-shaped member 11 may be round bar-shaped or mountain-shaped. In addition to steel, square rod-shaped or I-shaped steel can be used. Therefore, the thin plate member 10 and the rod-shaped member 11 may be selectively used depending on the portion for pre-compressing the molding sand S and the shape thereof. For pre-compression near the inner surface of the flask, the four corners should be bar-shaped.
The remaining part may be performed by the thin plate member 10.

[0008]

As is clear from the above description, the present invention simultaneously pre-compresses the molding sand near the inner surface of the casting frame and the inner and outer surfaces of the pattern with the thin plate body and the rod-shaped body, and then compresses the compressed sand on the upper surface of the molding sand. Since the entire molding sand is compressed under the pressure of, the molding sand in the molding frame can be molded well even in a portion where the mold clamping tends to be insufficient.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a pre-compressed body according to the present invention.

FIG. 2 is a view on arrow AA in FIG.

FIG. 3 is a vertical cross-sectional view showing a mold sand mold clamping state.

FIG. 4 is a vertical sectional view showing another pre-compressed body according to the present invention.

FIG. 5 is a view taken in the direction of arrows BB in FIG. 4;

[Explanation of symbols]

 2 Pattern 2A Pocket part 3 Pattern plate 4 Casting frame 5 Filling frame 7 Mounting plate 9 Cover member 10 Thin plate body 11 Rod-shaped body S Cast sand

Claims (2)

[Claims] 1. A step of placing a casting frame on an upper portion of a pattern plate having a pattern attached to its upper surface, and introducing casting sand into a space defined by the pattern rate and the casting frame. And a thin plate member disposed at an upper position with a slight distance from the inner surface of the casting frame and / or the inner and outer surface of the pattern is relatively inserted from above the casting sand toward the pattern plate. A step of pre-compressing the molding sand near the inner surface of the flask and / or the inner and outer surfaces of the pattern by pressing down, and the pressure of the compressed gas on the upper surface of the molding sand after extracting the thin plate from the molding sand And a step of compressing the whole of the foundry sand, and a mold making method characterized by the following steps: 2. A step of placing a casting frame on an upper portion of a pattern plate having a pattern attached to its upper surface, and introducing casting sand into a space defined by the pattern plate and the casting frame. And a thin plate body and a rod-shaped body which are arranged at an upper position with a slight distance to the inner surface of the flask and / or the inner and outer surface of the pattern from the upper portion of the molding sand toward the pattern plate at the same time. A step of pre-compressing the molding sand near the inner surface of the casting frame and / or the inner and outer surface of the pattern by relatively inserting and pushing down, and the upper surface of the molding sand after extracting the thin plate body and the rod-shaped body from the molding sand And a step of applying a pressure of compressed gas to compress the entire foundry sand,