JPH0558822B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for making a green sand mold, and more specifically, the present invention relates to a method for making a green sand mold. This invention relates to a method for forming a green sand mold.

(Prior art) In general, when a green sand mold that consists of a thick wall part and a thin wall part and has a flat shape as a whole is molded by a method such as a blow squeeze or a Jjort squeeze, the squeeze dimensions of the thick wall part and the thin wall part are the same. Because of this relationship, thicker parts have a lower compression ratio than thinner parts, resulting in inferior hardness and strength. For this reason, there was a problem in that parts of the mold with poor hardness and strength were deformed by the pressure of the molten metal, resulting in defective cast products.

(Object of the Invention) The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to form a green sand mold having a flat shape as a whole and comprising a thick part and a thin part to have uniform hardness and strength. The goal is to provide a way to obtain

(Example) The present invention will be described in detail based on an example below. In FIG. A lower mold 5 having a recess 4 corresponding to the shape of the lower part of the thick part of the final mold (desired mold) is mounted on the upper part of the table 3.

Reference numeral 6 denotes a casting flask that is carried in and out of a position above the lower mold 5 by a transport device (not shown), and its height is dimensioned to correspond to the thin wall portion a of the desired mold. Reference numeral 7 denotes a filling frame which can be pushed down by a push-down device (not shown) and is disposed above the lower die 5, and has a height dimension corresponding to the enlarged dimension a' of the thin wall portion of the preform, which will be described later. There is.

Reference numeral 8 indicates the filling frame 7 by a traveling device (not shown).
It is a blow tank that can be entered and removed above the
A sand blowing mold 10 is fixed to the bottom of the blow tank 8, and the sand blowing mold 10 has a recess 9 deeper than the shape of the upper part of the thick part of the desired mold. A preformed cavity 11 is defined by fitting the frame 7 and the sand suction mold 10.

In addition, the sand blowing mold 10 is inserted from the bottom of the blow tank 8.
A sand blowing hole 12 is drilled through the recess 9 of the sand blowing mold 10, and an exhaust hole 13 is drilled through the sand blowing mold 10 from the periphery of the lower surface to the side surface.
A vent plug 14 is fitted into the lower end opening of 3.

In FIG. 2, reference numeral 15 denotes a truck that moves in conjunction with the movement of the blow tank 8.
A compression mold 17 having a recess 16 corresponding to the shape of the upper thick part of the desired mold is fixed to the lower part of the mold. The compression mold 17 has an external shape that can be slidably fitted inside the filling frame 7.

Also, a stopper 1 is provided on the outer periphery of the lower surface of the truck 15.
8 is fixed to surround the compression mold 17,
The stopper 8 comes into contact with the upper surface of the filling frame 7, so that the lower surface of the compression mold 17 is at a height that corresponds to the lower surface level of the filling frame 7.

In the apparatus constructed as described above, the lifting cylinder 1 is first retracted to position the lower mold 5 at the lower end, and the blow tank 8 is placed above the lower mold 5. In this case, the filling frame 7 is located between the lower mold 5 and the sand blowing mold 10, and the casting flask 6 is placed between the lower mold 5 and the sand blowing mold 10.
They are suspended with an interval wider than the height of the two, and with a push-down device (not shown) in a free state.

In this state, the flask 6 is moved by a conveyor (not shown).
is carried between the lower die 5 and the filling frame 7, the table 3 and the lower die 5 are raised by the extension operation of the lifting cylinder 1, and the lower die 5 pushes up the casting flask 6 and the filling frame 7 to form the sand-blow mold. The upper surface of the filling frame 7 is brought into pressure contact with the lower surface of the filling frame 10. As a result, lower mold 5, mold 6, filling frame 7
A preformed cavity 11 is defined by the sand blowing mold 10 and the sand blowing mold 10 . Now, preformed cavity 11
To explain in detail the shape of the cavity 11, as shown in FIG.
has a shape corresponding to the desired mold, while the recess 9 in the upper portion has a vertical dimension larger than the shape of the desired mold, and furthermore, the cavity 11 has a shape corresponding to the desired mold.
The vertical dimensions of the entire mold are enlarged by seven filling frames compared to the desired shape of the mold, and these enlarged dimensions are designed to be different between the thick and thin parts. That is, as shown in FIG. 3, the enlarged dimension b' in the thick section is larger than the enlarged dimension a' in the thin section, and the dimensional ratio between the two is equal to the dimensional ratio between the thick section b and the thin section a in the desired mold. has been done.

Next, compressed air is introduced into the blow tank 8, and the green sand contained therein is blown and filled into the preform cavity 11 through the sand blowing hole 12 to form a preform. At this time, cavity 1
The air in the cavity 1 and the air blown in together with the green sand are discharged to the atmosphere from the exhaust hole 13 with the vent plug 14, so the green sand rides on the air flow and flows into the cavity 1.
It is evenly filled to every corner of the interior.

After blowing and filling green sand and molding the preform,
While operating the push-down device (not shown) of the filling frame 7 to push the filling frame 7 downward, the lifting cylinder 1 is retracted and the lower mold 5, flask 6, and filling frame 7 on the table 3 are lowered as one unit. As a result, the sand blowing mold 10 and the filling frame 7 are separated, and as a result, a preform having the shape of the recess 9 of the sand blowing mold 10 formed on the upper surface is formed on the upper surface of the lower mold 5, the casting flask 6, and the filling frame 7. It is kept inside.

Note that the retracting operation of the lifting cylinder 1 is stopped in the middle before the flask 6 comes into contact with a conveying device (not shown).

Next, the blow tank 8 is moved laterally by the traveling device, and the cart 15 to which the compression mold 17 is attached is positioned above the filling frame 7. During this time, the pressing device for the filling frame 7 is in a free state.

Next, when the lifting cylinder 1 is extended and the lower mold 5, casting flask 6, filling frame 7, and the held preform are raised together with the table 3, the compression mold 17 is slidably fitted inside the filling frame 7. , compressing the preform. When the lower surface of the compression mold 17 reaches the level of the lower surface of the filling frame 7, the upper surface of the filling frame 7 comes into contact with the stopper 18 to stop the rise, and the preform is compression molded into the desired mold shape.

Next, when the pressing device of the filling frame 7 is activated to push down the filling frame 7 and the lifting cylinder 1 is retracted, the compression mold 17 is first pulled out and separated from the filling frame 7, and then the table 3 is When descending, the filling frame 7 is stopped at the lowering end of the push-down device. Further, the table 3 continues to descend, and the flask 6 comes into contact with the conveying device, stopping the descent. As the table 3 further descends, the lower die 5 is separated from the flask 6 and removed. As a result, the desired mold is found in flask 6.
Obtained in a state where it is kept in

Next, the flask 6 containing the desired mold is sent out by a conveying device (not shown), a new empty flask 6 is introduced above the lower mold 5, and the compression mold 17 and blow tank 8 are transferred via a traveling device (not shown). and replace it, completing one cycle.

In the embodiment, the ratio between the enlarged dimension b' of the thick wall part and the enlarged dimension a' of the thin wall part in the preform cavity 11 is made equal to the dimensional ratio of the thick wall part b and the thin wall part a in the desired mold. However, the former b' is simply made larger than the latter a', and similar effects can be obtained.

(Effects of the Invention) As is clear from the above description, the present invention is effective in producing a green sand mold that has a thick wall portion and a thin wall portion and has a flat shape as a whole. A preformed cavity with enlarged dimensions is defined, green sand is blown and filled into this cavity to form a preformed body, and this preformed body is compression molded into a desired mold shape.
The produced green sand mold has substantially uniform hardness and strength between the thick and thin parts, and a good mold that does not undergo deformation due to molten metal pressure can be obtained.

Furthermore, since the green sand in the thick portion of the preform is well compacted, the transferability of this portion is improved, and a mold with good dimensional accuracy can be obtained.

[Brief explanation of the drawing]

The figures show one embodiment of the present invention, and FIGS.
The figures are partial cross-sectional views showing the operating mode, and the third figure shows the operating mode.
The figure is a dimensional comparison diagram of a preformed cavity and a desired mold cavity.

Claims (1)

[Claims] 1. A lower mold 5 with a recess 4 formed on the upper surface corresponding to the shape of the lower part of the thick-walled part of the desired mold, a casting flask 6 and a filling frame 7 having a height corresponding to the height dimension of the thin-walled part of the desired mold, and a desired mold on the lower surface. Preforming is performed by sequentially matching the molds from the bottom with a sand blowing mold 10 in which a concave portion 9 is formed by adding an enlarged dimension b' larger than the height dimension of the filling frame 7 to the shape corresponding to the lower part of the thick part of the filling frame 7. a step of defining a cavity 11; a step of blowing and filling green sand together with compressed air into the preform cavity 11 to form a preform of a mold; and a step of molding the preform into the lower mold 5 and the mold. A process of separating from the sand blowing mold 10 while being held inside the frame 6 and filling frame 7, and forming a recess 1 on the lower surface corresponding to the shape of the upper part of the thick part of the desired mold.
6 is formed inside the filling frame 7 to compression mold the preform into a desired mold shape, and the compression molded desired mold is held in the lower mold 5 and the flask 6. In this state, the compression mold 17 is placed in the filling frame 7.
At the same time, the medium mold is removed from the mold and placed in the flask 6.
A method for making a green sand mold, comprising the steps of: removing and separating the lower mold 5 from the flask 6 while holding the lower mold 5 in the mold.