JPH0520186B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a vacuum casting method and apparatus.

BACKGROUND ART Conventionally, as a method for casting with a sand mold section under reduced pressure, a fugitive model made of foamed plastic or the like is placed inside a casting flask, and casting sand is filled around this fugitive model to form a sand mold. After forming the sand mold part, the sand mold part is placed in a reduced pressure state to tightly solidify it to prevent collapse, and molten metal is injected into the fugitive model to melt and vaporize the fugitive model, thereby forming the fugitive model. There are castings that have the same shape.

Problems to be Solved by the Invention However, in the past, when placing a fugitive model in a casting flask, an operator installed the model inside the casting flask, but the inside of the casting flask was a limited space. This not only makes the work difficult, but also requires space for the worker within the flask, making the capacity of the flask larger than that required for the placement of the fugitive model. This created the problem of rising equipment costs as the equipment became larger. Furthermore, there is a problem in that it takes time to remove the casting sand when the cast product is taken out of the flask, especially when a long fugitive model is cast with a longitudinally disposed arrangement.

The present invention solves the above-mentioned problems, and makes it possible to easily install a fugitive model without providing extra space in the casting flask.
It is an object of the present invention to provide a reduced pressure casting method and an apparatus thereof, in which casting sand can be easily removed after casting and castings can be easily taken out.

Means for Solving the Problems In order to solve the above problems, the method of the present invention includes:
A fugitive model is placed on a pedestal part through floor sand, a frame part that can be attached to and detached from the pedestal part is placed surrounding the fugitive model, and the pedestal part and the frame part form a The molded flask is filled with sand to form a sand mold, molten metal is injected into the fugitive model in the sand mold, and the molten metal is vaporized and dissipated to become the same as the fugitive model. The structure is such that the mold is cast into a shape, and after casting, the frame is separated from the pedestal and the casting sand around the cast is removed.

Furthermore, the apparatus of the present invention has an upper frame part and a lower pedestal, which are disposed surrounding the fugitive model and are capable of joining and detaching a casting flask for filling the inside with casting sand to form a sand mold part. The structure is divided into two parts.

Effects According to the configuration of the method described above, after placing the vanishing model on the pedestal, the vanishing model is surrounded by the frame, so that the installation work of the vanishing model is not obstructed by the frame. This can be easily carried out without any problems, and the capacity of the frame body can be the minimum required to enclose the evanescent model.

In addition, when taking out the casting, the casting sand around the casting collapses naturally by separating the frame from the pedestal, making it possible to easily remove the casting sand with a simple operation.

Furthermore, according to the above-described configuration of the device, since the casting flask is divided into an upper frame portion and a lower pedestal portion, the fugitive model can be placed on the pedestal portion with the frame portion removed. The installation work can be done easily without being obstructed by the frame, and there is no need to provide space in the frame for the installation work of the fugitive model, so the capacity of the frame can be reduced. It is possible to minimize the amount required to surround the evanescent model. Further, by removing the frame portion from the pedestal portion after casting, the sand mold portion naturally collapses, making it easier to remove the cast product.

Embodiment Hereinafter, an embodiment of the present invention will be described based on the drawings. 1 and 2, a flask 1 is divided into an upper frame portion 2 forming a cylindrical body portion and a lower pedestal portion 3 forming a bottom portion. In addition, the lower end peripheral portion 2a forming the brim shape of the frame body portion 2 and the pedestal portion 3
It is formed so that it can be airtightly joined to the upper end peripheral edge part 3a forming a brim shape through a packing 4. and,
The frame body part 2 is fixed by a removable joint hook 5 that clamps and fixes the lower end peripheral part 2a and the upper end peripheral part 3a.
and the pedestal part 3 are connected and fixed. A plurality of deaeration pipes 6 are arranged at appropriate intervals in the circumferential direction inside the frame body part 2, and the deaeration pipes 6 are provided with a plurality of deaeration holes 7 of about 8 mm in diameter in a staggered manner on the pipe wall. There is. Further, a stainless steel wire mesh 9 is wrapped around the degassing pipe 6 to prevent the casting sand filled into the flask 1 from flowing in, and the wire mesh 9 is secured with a wire 10. . The lower end of the degassing pipe 6 is closed by a blind plug 11, and the upper end passes through the frame body 2 and communicates with a ventilation duct 12 formed on the outer circumference of the frame body 2. . Further, a pressure reducing pipe 13 communicating with a suction device (not shown) is connected to the ventilation duct 12. A plurality of gas vent pipes 14 are provided at appropriate locations on the outer periphery of the frame body 2 so as to communicate with the inside of the frame body 2. A valve (not shown) is provided that allows only one-way flow to the outside. Further, a horizontal rib 15 in the circumferential direction and a vertical rib 16 in the axial direction are provided on the outer side of the frame body part 2 to reinforce the strength of the frame body part 2. In addition, a hanging handle 17 is provided at the intersection of the horizontal rib 15 and the vertical rib 16.
is provided. An upper base part 18 forming a cavity is provided at the bottom of the pedestal part 3, and a plurality of deaeration holes 19 are provided in the upper base part 18. Further, the upper base 18 is covered with a stainless steel wire mesh 20 that prevents the casting sand 8 from flowing in, and a ring 18a for holding down the wire mesh 20 is externally fitted onto the outer periphery of the upper base 18 via the wire mesh 20. are doing. And a pressure reducing pipe 21 communicating with a suction device (not shown)
is provided in communication with the cavity of the upper base portion 18.
As shown in FIG. 3, the joint hook 5 includes a fixing part 22 fixed to the back side of the upper peripheral edge 3a of the pedestal part 3, and an intermediate joint 23 rotatably connected to the fixing part 22. And this middle clause 23
An arm 24 whose one end is rotatably connected in the middle of the
and a male screw 26 that is screwed into a female screw portion 25 provided at the other end of the arm 24.
Moreover, on the back side of the lower end peripheral edge 2a of the frame body part 2,
A retaining ring portion 27 is formed to prevent the male screw 26 from coming off. In the flask 1, a plurality of fugitive models 28 made of styrene foam are arranged on a floor sand 29, and each fugitive model 28 is connected by a runner 30 also made of styrene foam. There is. Further, a sand mold portion 31 is formed by casting sand 8 filled around the fugitive model 8. The upper end opening of the frame body 2 is closed with a membrane 32 made of plastic film sheet or metal foil in order to maintain airtightness. Sand is placed on it.
A sprue 33 penetrates the membrane body 32 and is provided continuously to the runner 30.

Hereinafter, the effects of the above configuration will be explained. First, the floor sand 29 is placed inside the pedestal section 3 with the frame section 2 removed. And this floor sand 2
The fugitive model 28 is placed continuously on the runner 9 with a runner 30. Therefore, the installation work of the evanescent model 28 is not carried out within the limited space of the frame body part 2, and is therefore easy to install without being obstructed by the frame body part 2.
Next, the frame body part 2 is lifted onto the pedestal part 3 by using a crane or the like with the lifting hand 17, and each vanishing model 28 is lifted up.
Place it on the pedestal part 3 so as to surround it. The joint hook 5 clamps and fixes the lower edge 2a of the frame 2 and the upper edge 3a of the pedestal 3, thereby connecting and fixing the frame 2 and the pedestal 3. At this time, the gastightness of the joint is maintained by the gasket 4 disposed between the lower end peripheral edge 2a of the frame body part 2 and the upper end peripheral edge 3a of the pedestal part 3. The joint hook 5 is attached by swinging the free end side of the intermediate section 23 upward and rotating the arm 24 to make the male thread 26 correspond to the retaining ring part 27.
This is done by swinging the free end side of the intermediate section 23 downward and pressing the male screw 26 against the lower end peripheral edge 2a of the frame body part 2 via the arm 24. next,
After filling the frame body part 2 with casting sand 8 to form a sand mold part 31, the upper end opening of the frame body part 2 is closed with a membrane body 32, and sand is placed on the membrane body 32 and pressed.
Then, the air in the sand mold part 31 is removed by the suction device from the degassing pipe 6 and the degassing holes 7 of the upper bottom part 18.
19, the sand mold part 31 is brought into a reduced pressure state, and the casting sand 8 is tightly solidified. Note that the air sucked into the degassing pipe 6 passes through the ventilation duct 12 and enters the decompression pipe 13.
The air sucked into the upper bottom portion 18 is guided to the pressure reducing pipes 21 and sucked and discharged. Next, the membrane body 3
Molten metal is injected through a sprue 33 provided through the hole 2. At this time, the runner 3 is located at the lower end opening of the sprue 33.
0 is located, and the runner 30 formed of styrene foam guides the molten metal to the fugitive model 28 while vaporizing and disappearing due to the heat of the molten metal.
Then, the molten metal that has reached the fugitive model 28 vaporizes and disappears the fugitive model 28 due to heat.
It flows into the cavity created by vaporization and disappearance of the fugitive model 28. As a result, the molten metal is cast into the same shape as the fugitive model 28. When taking out the casting, the fixation by the joint hook 5 is released, and the frame body part 2 is separated from the pedestal part 3 and the sand mold part 31 by being lifted by a crane or the like.
At this time, the sand mold part 31 is released from the restraint by the frame part 2 and collapses naturally. Therefore, the work of taking out the casting can be easily performed.

Effects of the Invention As described above, according to the present invention, the work of installing a fugitive model can be easily carried out without being obstructed by the frame. Also, when taking out the casting,
By separating the frame portion from the pedestal portion, the sand mold portion naturally collapses, making it possible to easily remove the cast material.

[Brief explanation of drawings]

FIG. 1 is an overall sectional view showing an embodiment of the present invention;
Figure 2 is a view from the X-X arrow in Figure 1, Figure 3 A is the 1st
Enlarged view of Y part in the figure, Figure 3B is Z-Z of Figure 3A
It is an arrow view. 1... Casting flask, 2... Frame body part, 3... Pedestal part, 5
...Jyointofutsuk, 28... Vanishing model, 3
0... Yudo club.

Claims (1)

[Scope of Claims] 1. A fugitive model is placed on a pedestal part with floor sand interposed therebetween, a frame part that can be connected to and detached from the pedestal part is placed surrounding the fugitive model, and the pedestal part A sand mold is formed by filling a casting flask formed by a mold and a frame body, and molten metal is injected into the fugitive model in the sand mold, and the metal melts by vaporizing and disappearing from the fugitive model. A vacuum casting method characterized by casting molten metal in the same shape as a fugitive model, and after casting, separating the frame from the pedestal and removing casting sand around the cast. 2. The casting flask, which is placed around the fugitive model and is used to fill the inside with casting sand to form a sand mold, is divided into an upper frame portion and a lower pedestal portion that can be joined and removed. A vacuum casting device featuring: