JP3144618B2 - Filling method of mold sand - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a model box having a sand mold cavity in which an upper half is formed in a cavity having a large cross-sectional area and a lower half is formed in a cavity having a small cross-sectional area. And a method for filling the mold sand of the invention.

[0002]

2. Description of the Related Art Conventionally, as a method suitable for automatically filling a mold cavity into every corner of a sand mold cavity, a negative pressure is applied to the inside of a model box and a pressure is applied between the inside of the model box and a sand hopper. A method of making a difference and filling the mold box with the differential pressure by using the pressure difference is known in Japanese Patent Publication No. Sho 63-21582. Even in such a method of filling the molding sand, in a model box having a long cavity part having an extremely small cross-sectional area in the lower half of the cavity, the molding sand is blocked at the entrance part of the cavity having a small cross-sectional area. There was a problem that the mold sand filling failure occurred due to the occurrence. The present invention has been made in view of the above-mentioned problems, and provides a method for filling mold sand without causing poor filling even in a model box having a cavity portion having an extremely small cross-sectional area in the lower half portion. The purpose is to provide.

[0003]

In order to achieve the above object, a method for filling mold sand according to the present invention comprises forming an upper half into a cavity having a large cross-sectional area and cutting a lower half into a small cross-sectional area. A model hopper having a sand mold cavity formed in a cavity having a large area is press-bonded to an upper portion of a model box having an amount of mold sand that is slightly larger than an amount of filling the lower half of the sand mold cavity therein. The lower end portion of the sand mold cavity is communicated with a reduced pressure source to make the inside of the sand mold cavity negative, while the interior of the sand mold cavity is communicated with the inside of the sand mold cavity. Suction filling and then sand mold cavity in the hopper
The upper part of the sand mold cavity is filled and the upper end of the sand mold cavity is communicated with a reduced pressure source to reduce the pressure in the sand mold cavity. The sand is suction-filled into the upper half of the sand mold cavity.

[0004]

According to the present invention, by adopting the above-described solution, as a first step, the mold sand is suction-filled into the cavity portion having a small cross-sectional area formed in the lower half part, As a second step, the molding sand is suction-filled to the corners of the upper half formed in the large cross-sectional area remaining in the cross section, and the molding sand is sufficiently filled in the small cross-sectional area. After being filled, the mold sand is filled as a whole.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus for carrying out the present invention will be described below with reference to FIG. In FIG. 1, the upper half part is a large cross-sectional area R
The model box 1 provided with a sand mold cavity C formed in the cavity of the above and formed with a lower half portion in a cavity having a small cross-sectional area S has an upper vent hole communicating with the upper end portion of the sand mold cavity C. A lower vent hole 3.3 communicating with the lower end portion 2.2 and the lower end portion 3.3 is perforated, respectively. A vent plug 4 is driven into the tip of each of the vent holes 2.2 and 3.3, and each of the vent holes 2.2 and 3.3.
The base end of 3.3 is connected to an upper open / close valve 5.5 and a lower open / close valve 6.6 attached to the side surface of the model box 1. A suction hose 7.7 communicating with a vacuum pump (not shown) is detachably connected to the lower opening / closing valve 6.6. Further, in the center of the upper end of the model box 1, the sand mold cavity is provided.
A sand suction port 8 communicating with C is provided.

A hopper 9 is pressed on the upper part of the model box 1 with a sand discharge port 10 provided at the upper end thereof communicating with the sand supply port 8. A slide gate 13 operated by a cylinder 12 provided via a mounting frame 9 is provided. Further, in the hopper 9, a mold sand 14 of self-hardening sand or gas-hardening sand is stored in an amount slightly larger than an amount for filling the lower half of the sand mold cavity-C. In FIG. 1, the on-off valves 5.5 and 6.6 are closed.

A method of filling mold sand into the sand mold cavity C of the model box 1 using the apparatus having the above structure will be described with reference to FIGS. In the state shown in FIG. 1, the lower opening / closing valve 6.6 is opened, and the sand mold cavity C is communicated with a vacuum pump (not shown) through the vent hole 3.3 so that the pressure inside the sand mold cavity C is reduced to a predetermined pressure. Become In this state (the communication between the sand mold cavity C and the vacuum pump is maintained), the cylinder 12 is operated to move the slide gate 13 to the right, and the sand suction port 8 and the inside of the hopper 9 are communicated via the sand discharge port 10. Thereby, the mold sand 14 in the hopper 9
Due to the pressure difference between the inside and outside of the model box 1 and the flow of air generated toward the vent hole 3.3, the vent hole 3 passes through the small cross-sectional area S in the lower half of the sand mold cavity C.
Suction filling toward 3. (First stage mold filling)

Next, the cylinder 12 is operated in reverse to move the slide gate 13 to the left to close the sand discharge port 10 and then fill the hopper 9 with the amount of mold sand 14 to fill the upper half of the sand mold cavity C. Is stored. On the other hand, the lower opening / closing valve 6.6 is closed and the suction hose 7 is detached from the lower opening / closing valve 6.6, and is connected to the upper opening / closing valve 5.5 to obtain the state shown in FIG. Next, the upper open / close valve 5.5 is opened, and the sand mold cavity C is connected to a vacuum pump (not shown) through the vent hole 2.2 to make the inside of the sand mold cavity C negative pressure to a predetermined pressure reduction degree. . In this state (sand mold cavity-C and vacuum pump are kept in communication)
Then, the cylinder 12 is operated to move the slide gate 13 to the right so that the sand suction port 8 and the inside of the hopper 9 communicate with each other through the sand discharge port 10. As a result, the mold sand 14 in the hopper 9 moves toward the vent hole 2.2 at the upper end of the sand mold cavity C by the pressure difference between the inside and outside of the model box 1 and the flow of air generated toward the vent hole 2.2. Since suction filling is performed, the filling is performed without interference with the mold sand 14 already filled.

Next, the cylinder 12 is operated in reverse to move the slide gate 13 to the left to close the sand discharge port 10 and to close the upper opening / closing valve 5.5 to set the suction hose 7.7 to the upper opening / closing valve 5.5.
After removal from the box 5, the model box 1 and the hopper 9 are separated from each other, and the model box 1 is brought into the state shown in FIG. Next, when the filled mold sand 14 is self-hardening sand, it is held until the sand is hardened, and when it is gas-curable sand, the hardened gas is supplied to the sand suction port in the same manner as in the filling of the mold sand 14. The hardening gas supplied from 8 is spread over the entire molding sand 14 (lower half and upper half) to harden the entire molding sand. Thereafter, the model box 1 is divided and separated, and the hardened sand mold is taken out to complete the molding of the mold. In the above embodiment, the suction hose 7.7 is used.
Are connected to the up / down on / off valves 5.5 and 6.6. However, even if the suction hose 7.7 is connected to all the on / off valves 5.5 and 6.6 and they are connected only by operating the valves. Good. The filling of the mold sand may be performed twice in a state where all of the on-off valves 5.5, 6.6 and the vacuum pump are connected to each other. The filling effect is slightly reduced. Further, two hoppers 9 may be prepared and alternately pressed against the model box 1 so that the molding sand is filled in two stages.

[0010]

According to the present invention, as is apparent from the above description, the mold filling is carried out in the first stage by suction filling a slightly larger amount of the molding sand than the filling of the lower half of the sand mold cavity.
Since the molding sand is suction-filled into the remaining upper half as a step, the molding sand is formed without blocking the model box having a small cross-sectional area in the lower half of the sand mold cavity. It can be filled.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an apparatus for carrying out the present invention.

FIG. 2 is a vertical cross-sectional view of the apparatus showing a state during the implementation of the present invention.

FIG. 3 is a longitudinal sectional view of the model box after sand filling is completed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Model box 2 Upper vent hole 3 Lower vent hole 5 Upper open / close valve 6 Lower open / close valve 7 Suction hose 9 Hopper 13 Slide gate C Sand mold cavity R Cross section large cross section S Cross section small cross section

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B22C 11/00-25/00

Claims (1)

(57) [Claims] 1. A model box having a sand mold cavity in which an upper half is formed in a cavity having a large cross-sectional area and a lower half is formed in a cavity having a small cross-sectional area. Then, a hopper storing mold sand in an amount slightly larger than the amount of filling the lower half portion of the sand mold cavity is press-bonded, and the lower end portion of the sand mold cavity is communicated with a reduced pressure source so that the inside of the sand mold cavity is negatively charged. While pressurizing, the inside of the hopper communicates with the inside of the sand mold cavity to cause the mold sand to be suction-filled into the lower half of the sand mold cavity, and then the amount to be filled into the hopper with the upper half of the sand mold cavity. And the upper end of the sand mold cavity is communicated with a reduced pressure source to reduce the pressure in the sand mold cavity while the inside of the hopper and the sand mold cavity are communicated. A method for filling mold sand, wherein the upper half of the cavity is filled by suction.