JPS5849345B2 - How to make shell molds - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a shell mold, and more particularly, to a method for manufacturing a shell mold.
The present invention relates to a shell mold manufacturing method that prevents deformation of the mold when bonding two shell molds.

The shell mold method, which is one of the mold making methods, provides highly accurate castings and does not require much skill, so it is very advantageous in mechanizing casting work, and is widely used today. ing.

Hereinafter, using FIGS. 1A to 1F, a brief explanation will be given of the case in which a mold (outer mold) is manufactured by this mode method.

1. The pump box 1 is in an upside-down position, mixed sand 2 is placed inside it, and a pattern plate (mold) 3 is set in an upside-down position.

During this time, the pattern plate 3 is preheated (Figure 1A)
.

Next, the dump box 1 is rotated about the rotating shaft 4, and the mixed sand 2 falls onto the pattern plate 3.

Then, the thermosetting resin in the mixed sand 2 around the pattern plate 3 is heated by the pattern plate 3, softens and melts, and loosely fixes the sand (FIG. 1B).

Next, flip Gump Box 1 and pattern plate 3.
Instead of sanding, the remaining sand other than the mixed sand is removed (first
Figure C).

When the pattern plate 3 around which the mixed sand 2 is oxidized is removed from the dump box 1, and the mixed sand 2 and the pattern plate 3 are further heated, the thermosetting resin in the mixed sand hardens, and this mixed sand becomes It solidifies and becomes the shell mold 5 (
Figure 1D).

The fired shell mold 5 is released from the pattern plate 3 by pushing out the pins 6 previously provided on the pattern plate 3 (Fig. 1E).
.

Two shell molds 5 formed as described above are bonded together to form one mold (outer mold).

In order to bond two molds formed on each side as described above, a flange portion is formed on the outer periphery of each mold.

The two molds are bonded together using a bonding table as shown in FIG. 1F.

As shown in FIG. 1, the bonding table has a lower bonding plate 7 and an upper bonding plate 8, and each bonding plate has a spring 9a,
A large number of bonding pins 10a and 10b are provided, which are urged toward the mating bonding plate by 9b.

For example, in a bonding stand used for bonding a mold for a camshaft of a passenger car engine, about 50 bonding pins 10a, 10b are provided on each plate.

One of the paired shell molds 5a has a flange portion 11a provided on its outer periphery supported by the bonding pin 10a of the lower mold bonding plate 7, and is mounted on the lower mold bonding plate 7. be placed.

After an adhesive is applied to the mating surface of the flange portion 11a or the flange portion 1lb of the shell mold 5b which is to be mated with the shell mold 5a, the shell mold 5b is placed on top of the shell mold 5a.

A bonding pin 1 of the upper mold bonding plate 8 is provided on the back side of the flange portion 11b of the upper shell mold 5b.
0b are aligned, and the upper bonding mold V 8 is placed on this upper mold 5b.

Thereafter, the upper mold bonding plate 8 is pressed downward by, for example, compression.

Such Calo pressure is applied for about one minute, and the upper shell mold 5b and the lower shell mold 5a are integrated with the above-mentioned adhesive.

As mentioned above, the bonding pins 10a, 10b springs 9
a, 9b respectively to the lower bonding plate 7.
, since it is supported by the upper mold bonding plate 8,
The bonding pins 10a and 10b are attached to each flange portion 11.
a, 1lb elastically abuts.

It is difficult to form the flange portions 11a, 1lb of the shell molds 5a, 5b to have a uniform thickness over the entire circumference,
When bonding two shell molds using the bonding stand as described above, these flange parts 11a, 1lb
(There is considerable variation in the thickness of the flange, and if the flange part is unevenly sized, the pressure distribution will be uneven, causing partial ups and downs, causing distortion in the shell mold.) become.

Such distortion is particularly likely to occur when the shell mold is long and narrow, and has been a cause of defective castings, for example, in shell molds for engine camshafts.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method for manufacturing a shell mold that does not cause distortion in two molds when they are bonded together. .

The shell mold manufacturing method of the present invention is a mold manufacturing method in which two molds are molded using a dump box as explained above, and then these are glued together. Before the mold hardens, a flat part is press-formed on the back side of the flange part which will be the mating surface of this shell mold, and after the shell mold hardens, this shell mold is released from the pattern plate, and this shell mold is Place the mold on a bonding table with a non-stretchable reference pin protruding from the top surface using the flat part as a seat, and then place the mating shell mold on top of the shell mold and raise both shell molds. It is characterized by pressure bonding using a spring pin.

As mentioned above, without directly supporting the surface of the flange part whose thickness is not constant, the flat catch provided on the flange part is placed on a reference pin for positioning that does not expand or contract like in the past. If the bonding surface of the shell mold is subjected to the bonding process, the bonding surface of the shell mold will not be displaced on the bonding table, and the above-mentioned distortion can be prevented from occurring.

Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings.

2A to 2C show the main steps of a method for manufacturing a shell mold according to an embodiment of the present invention.

1. First, the pattern plate 2 in which the shell mold 20 has been formed by the steps shown in FIGS. 1A to 1C described above.
1 or be removed from the Gump Box.

The pattern plate 21 is placed, for example, on a flat table, with the shell mold 20 facing upward, as shown in FIG. 2A.

Next, this shell mold 20 has a number of pins 2 with flat tips and arranged in the same manner as the bonding pins that will be used later.
It is pressed from above with a pressurizing force 23 having a pressure of 2.

At this time, the Karo pressure mold 23 is arranged so that its relative pin 22 comes into contact with the flange portion 24 of the shell mold 20.

Since the shell mold 20 is not trench-burned, it is not completely solidified, and when the above-mentioned force or pressure 23 is pressed, a flat part 25 is formed in the flange part 24 by the shaped pin 22. be shaped into a certain form.

After shaping such a flat part 25, it is pressed by force or pressure 2.
3 is separated from the shell mold 20, and the shell mold 20 is fired.

The fired and completely hardened shell mold 20 is released from the pattern plate 21 and the mating surface 2 of the flange portion 24 is removed.
6 One side of the mold with a flat part 25 formed on the back side is completed (see Figure 2B).

This shell mold 20 is then bonded to another shell mold on a bonding table as shown in FIG. 2C.

The lower bonding plate 27 of the bonding table is fixed with reference pins 28 which are not stretchable like conventional ones and are made of a number of rod-shaped bodies having flat upper end surfaces.

These reference pins 28 are connected to the aforementioned force mouth pressure or shape 2
Since it is arranged in the same way as the shaped pin 22 in 3,
When the shell mold 20 is placed on the lower mold bonding plate 27 with its mating surface 26 facing upward, the reference pins 28 are attached to each of the flat portions 25 provided on the flange portion 24. Fall asleep, touch these reference pins 2
8 can be reliably supported.

If the tip level of each of the pins 22 of the Karo press holder 23 is aligned, and the tip level of each of the reference pins 28 is also the same, the mold 20 will not wobble on the reference pin 28. There is no.

Next, the other shell mold 30 is placed with its mating surface 29 aligned with the mating surface 26 of this shell mold 20.

As described above, these mating surfaces 26 and 29 are coated with adhesive in advance.

After the shell molds 20 and 30 are combined, an upper mold bonding plate 31 is placed on the upper shell mold 30.

The upper shell mold 30 is molded by the molding method shown in FIGS. 1A to 1F described above, and has a flange portion 32 with an uneven thickness.

Therefore, the upper bonding plate 31 placed directly on the surface of the flange portion 32 of this shell mold 30 has a spring 33 similar to the upper bonding plate 8 in FIG. 1F.
A device having a resilient pin 34 that moves in and out elastically is used, so that differences in thickness of the flange portion 32 can be absorbed.

After this, the upper mold bonding plate 31 is pressurized downward, and the shell mold 20 and the shell mold 30 are bonded together.
Two molds (outer molds) are completed.

As described above, in the shell mold manufacturing method of this embodiment, the shell mold 20 disposed on the lower side of the bonding table is supported on the reference pin 28 without wobbling, so that the shell mold 20 is The shell mold 20
Even if the weight of the shell mold 30 according to the above rule or the pressure applied during adhesion changes, no force is applied in the direction of shearing the flange portion 24, and the shell mold 20 is prevented from being destroyed.

Since the shell mold 20 according to the rule below is directly supported by the reference pin 28 in this way, the parts of the molds 20 and 30 do not rise and fall unevenly during Calo pressure bonding, and therefore the shell No distortion occurs in the mold 20.30.

In the embodiment described above, the flat part of the flange part 24 of the shell mold 20 placed on the lower side during Calo pressure bonding is deformed using a large number of pins. In addition to the above-mentioned pin, the flat portion may be shaped into an annular shape around the entire periphery of the flange portion, for example, by the end face of a frame-shaped plate member.

In such a case, the lower bonding plate may be shaped to receive the annular flat portion with a large number of pins, or the entire surface of the flat portion may be covered with a frame-like plate member. It may be shaped to receive.

It is not necessarily necessary to form the flat portion at a position recessed from the surface of the flange portion, but the flat portion may be formed at the same level as the surface of the flange portion.

However, as in the above embodiment, if the flat part is used as the bottom surface of the recess, the supporting part of the lower bonding plate will fit into the recess during Caro pressure bonding, and the shell mold will fit into the lower bonding plate. This is advantageous since there is no possibility of lateral displacement on the holding plate.

Furthermore, it goes without saying that the seats of both of the two shell molds forming the lamp may be shaped.

As explained in detail above, the shell mold manufacturing method of the present invention completely prevents distortion of the two shell molds by an extremely simple method when the two shell molds are bonded together using Calo pressure. The practical value of the present invention is extremely high.

[Brief explanation of drawings]

1A to 1F are illustrations showing a conventional method for making a shell mold, and FIGS. 2A to 2C are illustrations showing the main steps of a method for making a shell mold according to an embodiment of the present invention. 1...Dump box, 2...Mixed sand, 3,21...Pattern plate, 5.5a,
5b, 20.30... Shell mold, 7, 27.
...Lower bonding plate, 8, 31...
...Upper bonding plate, 1 1 a, 1 l
b, 24.32-Flange part, 22... Certain shaped pin, 23... Pressurized shape provisional, 25...
・Flat part, 26.29...Matching surface, 28...
...Reference pin, 34...Bullet pin.

Claims (1)

[Claims] 1. Cast a shell mold on the pattern plate using a tab box, and before this shell mold hardens, press a flat part on the back side of the flange part that will be the mating surface of this shell mold, and then press the shell mold. After the shell mold is cured, the shell mold is released from the pattern plate, and the shell mold is placed on a bonding table having a non-stretchable reference pin protruding from the upper surface, using the flat part as a seat, Thereafter, a mating shell mold is placed on top of the shell mold, and both shell molds are pressure-bonded from above via a spring pin.