JPH0126784B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is a method for casting a large number of products at once.
This relates to a mold.

Conventionally, in the vacuum molding method, when pouring molten metal, the inside of the mold cavity surrounded by the shielding member and the part of the mold on the filling material side that is solidified under negative pressure are exposed to the heat of the molten metal, which causes the shielding member to be burned out. As a result, the pressure is equalized due to communication, and the holding force of the mold is lost, resulting in deformation of the mold and resulting in poor product shape after pouring.

For this purpose, a ventilation hole is provided at the upper end of the mold cavity to prevent the mold from deforming during pouring, but as shown in Figures 3A and 3B,
When there are a plurality of mold cavities 20, it is necessary to provide a plurality of ventilation holes 21, which makes film molding work difficult, and conditions such as the pitch and depth of the plurality of ventilation holes 21 may cause problems. As a result, film molding work becomes impossible. In addition, molding or mold coating work was difficult, resulting in problems such as product defects or deterioration of quality. Furthermore, it is difficult to fix the position of the ventilation hole, and it cannot be mechanized.

The present invention has been made in view of these problems, and even when there are multiple mold cavities, only one ventilation hole is required, making various operations such as film molding, molding, and mold coating easy and reliable. In addition, during film molding work, good casting products can be expected without being affected by gates, ventilation holes, etc. Furthermore, the position of the ventilation hole can be easily fixed, and there is only one piece. The object of the present invention is to provide a vacuum molding mold that has great versatility and is extremely easy to mechanize.

The illustrated embodiment will be described in detail below. Reference numeral 1 denotes a vacuum molding flask equipped with a vacuum chamber 2 on its outer periphery, which is connected to a vacuum source (not shown) through a connecting pipe 2a. A perforated pipe 3 is provided, and a negative pressure is applied to the inside of the vacuum flask 1 through the connecting pipe 2a, the vacuum chamber 2, and the perforated pipe 3 by the operation of the vacuum source. At the same time, the filler 4 in the form of dried sand particles is solidified under negative pressure via flexible shielding members 5 and 6 tightly attached to the upper and lower surfaces of the filler 4, thereby forming and holding a vacuum molding mold 7. As shown in FIG. 2, on the mold surface of this vacuum molding mold 7,
The vacuum molding mold 7 held in the vacuum casting flask 1 is passed through the sprue 8
When erected so that the sprue 8 is on the top surface, two mold cavities 9 are arranged in parallel in three stages above and below, with the side far from the sprue 8 positioned slightly above, and the sprue 8 extends vertically downward and is provided substantially parallel to the mold cavity 9, and the lower end of the sprue 8 is located below the mold cavity 9 in the lowest area.

Moreover, the sprue 8 has a plurality of runners 8a on the way.
Each runner 8a is branched into
The mold cavities 9 are provided below and above the mold cavities 9 at positions slightly apart from the ends of the mold cavities 9, respectively, in parallel and upwardly inclined.
The lower runner 8a and the lower end of the mold cavity 9 are
Further, the runner 8a above the mold cavity 9 and the upper end of the mold cavity 9 are connected to each other via a weir 10. And the top runner 8a
is connected to a ventilation hole 11 that is open to the atmosphere near its upper position. Therefore, each mold cavity 9 is configured to communicate with a ventilation hole 11 via a runner 8a and a weir 10.

The vacuum molding mold 7 is molded with the other vacuum molding mold that was vacuum molded by the same operation to form a vertically split vertical mold, and as shown in FIG. 2, pour the metal from the sprue 8. The molten metal is at sprue 8.
The molten metal flows through the runner 8a at the lowest position and from the weir 10 into the mold cavity 9 at the lowest area, and when the mold cavity 9 at the lowest area is filled with molten metal, the molten metal flows into the next runner located at the upper side. 8a, the molten metal similarly flows from the weir 10 into the area one step above the lowermost area, and thereafter, the molten metal flows sequentially into the mold cavity 9 located above.

That is, as shown in FIG. 2, when the molten metal is flowing into the mold cavity 9 in the lowest area, the upper space above the molten metal level in the mold cavity 9 is connected to the weir 10 above the molten metal level. Vent hole 11 via passage 8a and mold cavity 9, etc.
Since the outside air is flowing into the vacuum mold 7, even if the shielding member 5 is burnt out by the heat of the molten metal, the vacuum mold 7 will not lose its shape, and the mold cavity 9 in the lowermost area will be filled with the molten metal. After that, when the molten metal flows into the mold cavity 9 on the upper side, the upper space of the mold cavity 9 where the molten metal has not yet flowed is filled with the weir 10 above the molten metal level, the runner 8a and the runner 8a. Since outside air is flowing in from the ventilation hole 11 through the mold cavity 9 etc., the mold cavity 9 located one step above the lowest area will not lose its shape even if the shielding member 5 is burned out by the heat of the molten metal. . Furthermore, the molten metal can also flow into the mold cavity 9 in the uppermost area without causing deformation, as described above. In this way, the mold cavity 9 in the upper region is smaller than the mold cavity 9 in the lowermost region.
The molten metal flows into each mold cavity 9 in an orderly manner, and each mold cavity 9 has a ventilation hole 11 through the weir 10 above the molten metal level, the runner 8a, the mold cavity 9, etc.
Since the ventilation hole 11 is designed to be in communication with the outside air to be introduced, only one ventilation hole 11 can fulfill its function, and each mold cavity 9 will not lose its shape even if the shielding member 5 is burned out by the heat of the molten metal. . After solidification of the molten metal, the decompression effect acting on the filler 4 is released and the mold is released.

Incidentally, the uppermost runner 8a among the runners 8a is
If the product is thin and cannot be used as a riser,
It is also possible to cut off the communication with the sprue 8 and use it only as a ventilation passage that communicates the weir 10 and the ventilation hole 11.

As is clear from the above description, the present invention has the following effects.

That is, 1) Even if there are a plurality of mold cavities, only one ventilation hole is required, and film molding can be easily and reliably performed, and mold coating work can be performed easily.

2) Film molding is not affected by gates or vents and can be applied to any product.

3) Product quality improves.

4) Because the position of the ventilation hole can be easily fixed,
Mechanization becomes much easier.

5) Conventionally, the sprue is located higher than the mold cavity, as shown in Figure 3, but in the present invention, the sprue and the mold cavity are on the same plane and have a lower height, as shown in Figure 1. Therefore, film molding can be easily and reliably performed, and mold coating work can be performed evenly and uniformly, and seizures caused by variations in coating mold thickness, blowholes, and explosion phenomena during pouring can be prevented.

6) Since the molten metal is poured into the mold cavity in the upper area sequentially from the lower area,
The temperature of the molten metal within the multiple mold cavities becomes uniform, stabilizing the quality of the casting, and it also makes it possible to lower the pouring temperature by 50 to 70 degrees Celsius compared to conventional methods, which helps save energy.

[Brief explanation of drawings]

Figure 1 is a sectional view showing an embodiment of the present invention during vacuum molding, Figure 2 is a sectional view showing the vacuum molding mold in Figure 1 being erected and pouring metal, and Figure 3 is a sectional view showing an embodiment of the present invention during vacuum molding.
Figure A is a plan view showing a conventional vacuum molding, and Figure 3B is a longitudinal sectional view of Figure 3A. 1: vacuum flask, 5, 6: shielding member, 7: vacuum mold, 8: sprue, 8a: runner, 9: mold cavity, 10: weir.

Claims (1)

[Claims] 1. A plurality of mold cavities and a sprue are provided approximately parallel to the mold surface of the vacuum molding mold covered with a shielding member, and when the vacuum molding mold is erected with the sprue facing upward, from the sprue Below each of the mold cavities, runners are provided that are slightly upwardly inclined and approximately parallel to each other, and the lower end of each mold cavity is connected to the runner below the mold cavity, and the upper end of the mold cavity is connected to the runner that is below the mold cavity. The runners above the mold cavity are connected to each other through weirs, and the upper end of the mold cavity in the uppermost area is connected to a vent opening from the upper end of the mold to the atmosphere. Molding mold.