JPH06114530A - Vacuum filling casting apparatus - Google Patents

Abstract

PURPOSE:To reduce the equipment cost for monitoring the pressure in a molding flask. CONSTITUTION:A vacuum filling casting apparatus is provided with pressure introducing piping 20, which is positioned to a specified position in molding sand 2 through a filter at the one end and to the outside of the molding flask at the other end 14t, a vacuum gage 30 supported to the frame base 32 separately arranged from the molding flask 4 and an air cylinder 38 connecting the pressure introducing piping 20 with the vacuum gage 30 by abutting a pressure detecting hole 36 in the vacuum gage 30 on the other end 14t of the pressure introducing piping 20 in the condition of positioning the molding flask 4 to the casting position. By this method, to the molding flask 4 in the casting position, the vacuum gage 30 can automatically be set. Therefore, the vacuum gage 30 in each molding flask 4 is unnecssary to always ready and the cost of the molding flask is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method in which molding sand is stored in a molding frame having an open upper part, a disappearing model is buried in the molding sand, and the inside of the molding frame is depressurized from below to make the molding sand. After fixing, the molten metal is injected from the sprue part of the disappearing model to cast a product having substantially the same shape as the disappearing model.

[0002]

2. Description of the Related Art The above-described vacuum filling and casting apparatus is capable of returning the solidified molding sand to a fluidized state again when the depressurized state in the flask is released after casting, and thus it can be easily reused. This is a casting method that is excellent for mass production. The decompression in the flask here not only hardens the molding sand, but also improves the bathing area,
This is done for the purpose of efficiently discharging the gas generated by burning the vanishing model generated during casting. Therefore, the influence of the pressure in the flask on the casting quality is very large. Therefore, in the conventional vacuum filling casting apparatus, the pressure in the vacuum chamber provided at the bottom of the casting frame is indirectly detected to detect the pressure in the casting frame, or a pressure gauge is provided at a required position in the casting frame. The pressure inside the flask is monitored during casting by, for example, mounting and detecting the pressure at that position.

[0003]

However, the method of measuring the pressure in the decompression chamber at the bottom of the flask cannot detect the accurate pressure in the flask, resulting in low measurement accuracy. In addition, the method of installing a pressure gauge at a required position in the flask and detecting the pressure at that position can ensure measurement accuracy, but in mass production equipment, a pressure gauge is attached to all flasks used for casting. Must be,
The cost of the flask will increase significantly. Further, there is a problem in that the accuracy of the pressure gauge is lowered and the daily maintenance cost is increased due to damage of the pressure gauge due to an impact during transportation of the casting frame. The technical problem of the present invention is that the pressure detection sensor is automatically attached to and detached from the casting frame, and the pressure detection sensor is set only in the casting frame positioned at the casting position, whereby the pressure for each casting frame is reduced. The purpose of the present invention is to reduce the cost of the flask by eliminating the need to install a gauge, and also to reduce the damage of the pressure detection sensor to improve the accuracy of pressure measurement and reduce the cost.

[0004]

The above-mentioned problems can be solved by a vacuum filling and casting apparatus having the following respective structures. That is, the vacuum filling and casting apparatus according to the present invention stores the molding sand in the molding frame whose upper part is open, burying the disappearing model in the molding sand, decompressing the inside of the molding frame from below and casting the molding. After fixing the sand, injecting molten metal from the spout of the vanishing model, in a vacuum filling casting device for casting a product having almost the same shape as the vanishing model, one end is located at a predetermined position in the foundry sand through a filter. The pressure guiding pipe having the other end positioned outside the casting frame, the pressure detection sensor installed at a position different from the casting frame, and the casting frame is positioned at the casting position. In this state, the pressure detecting port of the pressure detecting sensor is brought into contact with the other end of the pressure guiding pipe to connect the pressure guiding pipe to the pressure detecting port.

[0005]

According to the present invention, in order to measure the pressure at a predetermined position in the flask, first, the flask is positioned at the casting position,
Next, the pipe connection mechanism is operated to bring the pressure detection port of the pressure detection sensor into contact with the other end of the pressure guiding pipe. As a result, the pressure detecting port of the pressure detecting sensor and the pressure guiding pipe are connected to each other, and the pressure at the tip of the pressure guiding pipe, that is, the pressure at a predetermined position in the foundry sand is introduced to this pressure detecting sensor. . Therefore, if the tip of the pressure guiding pipe is positioned at a position required for pressure monitoring, the pressure at this position can be constantly monitored by the pressure detection sensor during casting. Further, after the casting is completed, the pipe connecting mechanism is operated to separate the pressure detecting port of the pressure detecting sensor from the other end of the pressure guiding pipe, whereby the connection between the pressure detecting port and the pressure guiding pipe is easily released. As described above, since the pressure detection sensor can be automatically set for the flask at the casting position, it is not necessary to always have the pressure detection sensor in each flask, and the cost of the flask can be reduced. Further, when the flask is not in the casting position, the pressure sensor is not attached to the flask, so that the pressure sensor is not damaged due to movement of the flask. As a result, the pressure in the casting mold can be measured by the pressure detection sensor without damage, so that the measurement accuracy is also improved.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vacuum filling and casting apparatus according to an embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a longitudinal sectional view of a main part of a vacuum filling and casting apparatus according to this embodiment, FIG. 2 is a detailed view of II of FIG. 1, and FIG. 3 is a detailed view of III of FIG. Further, FIG. 4 is a graph showing the pressure distribution in the flask. As shown in FIG. 1, the vacuum filling and casting apparatus according to the present embodiment includes a casting frame 4 for containing heat-resistant granular material (hereinafter referred to as casting sand 2). The flask 4 is a box-shaped container having an open top and a double bottom. The upper plate (middle plate 4n) of the double bottom is made of a breathable porous sintered plate. A pressure reducing chamber 4c is provided below the intermediate plate 4n, and the pressure reducing chamber 4c is connected to a pressure reducing device (not shown) via a suction valve 6. Furthermore, the decompression chamber 4
c is also connected to an air source (not shown) via a pressurizing valve (not shown).

A plurality of small chambers 14 are provided at predetermined intervals at the upper end of the outer surface of the casting frame 4. As shown in FIG. 2, a lateral through hole 14y is formed between the small chamber 14 and the casting frame 4, and the small chamber 14 and the interior of the casting frame 4 communicate with each other through the lateral through hole 14y. is doing. Further, a vertical through hole 14t is formed in the upper plate 14u of the small chamber 14, and the small chamber 14 is opened to the outside by the vertical through hole 14t. Further, in both through holes 14y and 14t, a gas permeable porous sintered vent 24y, 2 functioning as a filter.
4t is attached. This allows the small chamber 1
The casting sand 2 in the casting frame 4 and external dusts and the like do not enter the inside of the casting frame 4. Due to the structure described above, the flask 4
With a predetermined amount of foundry sand 2 stored inside, and with the fusible film 10 covered on the flask 4, the flask 4
When the decompression chamber 4c at the bottom is decompressed, the inside of the casting frame 4 is indirectly decompressed through the air-permeable middle plate 4n, and the molding sand 2 is sucked downward and solidified. Further, the fugitive film 10 has its central portion adsorbed on the surface of the foundry sand 2, and its edge portion further includes the upper plate 14 of the small chamber 14.
By being adsorbed by the vertical through hole 14t of u, it is surely covered with the casting frame 4 and the sealing property inside the casting frame 4 is secured.

FIG. 4 shows the pressure distribution (●) in the casting frame 4 and the disappearance film 1 when the disappearance film 10 is covered.
6 is a graph showing a pressure distribution (◯) in the casting frame 4 in a state where 0 is not covered. The horizontal axis represents the pressure measurement site, and the vertical axis represents the degree of pressure reduction. Consider, for example, the case where the inside of the decompression chamber 4c is decompressed by 540 mmHg from the atmospheric pressure. When the extinguishing film 10 is covered, the upper surface, the center and the bottom of the casting frame 4 are maintained at −540 mmHg (atmospheric pressure is 0 mmHg) with almost no pressure fluctuation. On the other hand, in the case where the fusible film 10 is not covered, the bottom of the casting frame 4 is only held at approximately -540 mmHg, and the degree of reduced pressure becomes smaller as it approaches the upper surface. In the actual operation, the pressure inside the flask 4 is -200 mmHg (atmospheric pressure 0 mm
Hg).

A pressure detecting pipe 20 for guiding the pressure in the casting frame 4 to the outside of the casting frame 4 is attached to the inside of the casting frame 4. As shown in FIG. 3, the pressure detecting pipe 20 is a pipe formed in a substantially L shape, and the casting frame 4
Is vertically attached to the inner wall surface of the through a support 22. Further, the upper portion of the pressure detecting pipe 20 is passed through the lateral through hole 14y and accommodated in the small chamber 14, and the vertical opening 14t of the small chamber 14 has the upper opening 20j of the pressure detecting pipe 20. It is connected. Further, the pressure detection port 20s provided at the tip of the pressure detection pipe 20 is positioned at a predetermined level in the casting frame 4. Further, a sintering vent 24 functioning as a filter is attached to the pressure detecting port 20s and the upper opening 20j of the pressure detecting pipe 20. As a result, in the pressure detection pipe 20, the molding sand 2 in the molding frame 4
It is also designed to prevent the entry of external dust and the like. Note that the pressure detection position can be freely selected by changing the length of the pressure detection pipe 20. That is, the pressure detecting pipe 20 and the vertical through hole 14t of the small chamber 14 function as a pressure guiding pipe. On the upper plate 14u of the small chamber 14 with which the upper opening 20j of the pressure detecting pipe 20 abuts, a groove 14m having a ring-shaped planar shape is formed on the upper surface thereof. And this groove 14m
The O-ring 36s attached to the tip of the pressure reduction detection attachment 36 described later is stored therein.

As shown in FIG. 1, a frame 32 for supporting the vacuum gauge 30 is installed near the casting position of the casting frame 4. The frame 32 has the vacuum gauge 3
0, the vacuum gauge 30 and the pressure detection pipe 2
Decompression detection attachment 36 for communicating with 0
Also, an air cylinder 38 for raising and lowering the decompression detecting attachment 36 is supported. Further, the vacuum gauge 30 and the reduced pressure detection attachment 36 are connected by a flexible pressure detection pipe 34.
Here, the decompression detection attachment 36 is a cylindrical container, and the suction chamber 3 formed inside the container.
As shown in FIG. 3, the pressure detecting pipe 34 is connected to 6k. Further, the decompression detection attachment 36
A concave portion 36h is formed in the center of the front end surface 36f, and the concave portion 36h and the suction chamber 36k communicate with each other through a suction passage 36t. Further, the recess 36h
A tapered pin 36p is fixed to the center of the. The outer diameter of the pin 36p is set smaller than the diameter of the vertical through hole 14t of the small chamber 14, and the tip portion of the pin 36p has the tip surface 3 of the attachment 36 for detecting reduced pressure.
It projects by a predetermined dimension from 6f. Further, a through hole 36c is formed inside the pin 36p in the axial direction, and an air nozzle 36a is housed in the through hole 36c. Then, air can be blown out from the tip of the pin 36p at a predetermined timing. further,
An O-ring 36s for sealing is mounted around the recess 36h on the tip surface 36f of the attachment 36 for detecting the reduced pressure.

The decompression detecting attachment 36 is coaxially connected to a piston rod (not shown) of the air cylinder 38 with the tip surface 36f facing downward. The air cylinder 38 is attached vertically downward at a predetermined position of the gantry 32. With this structure, when the air cylinder 38 is driven in the direction of extending the piston rod, the decompression detection attachment 36 descends, and when the air cylinder 38 is driven in the direction of accommodating the piston rod, decompression detection is performed. Attachment 36 is raised.

Here, the casting frame 4 has a vertical through hole 14 of a small chamber 14 to which the pressure detecting pipe 20 is connected.
The center line of t is positioned at the casting position such that the center line of t coincides with the axes of the attachment 36 for detecting reduced pressure and the air cylinder 38. Therefore, when the air cylinder 38 is driven in the direction in which the piston rod extends while the casting frame 4 is positioned at the casting position, the depressurization detection attachment 36 descends and the pin 36p of the depressurization detection attachment 36 is moved. Is inserted into the vertical through hole 14t of the small chamber 14. As a result, a hole is made in the fusible film 10 covering the vertical through hole 14t of the small chamber 14, and the vertical through hole 14t and the recess 36h of the reduced pressure detection attachment 36 communicate with each other. Further, the tip surface 36f of the decompression detection attachment 36 abuts the upper plate 14u of the small chamber 14 through the fusible film 10, and the O-ring 36s and the fusible film 10 mounted on the tip surface 36f are moved to the upper side. Board 14u
It engages with the groove 14m formed in. As a result, the vertical through hole 14t and the recess 36h of the reduced pressure detection attachment 36 are provided.
And are sealed from the outside. As a result, the pressure detection pipe 20 and the pressure detection pipe 34 of the vacuum gauge 30 are connected to each other through the vertical through hole 14t and the pressure reduction detection attachment 36, and the vacuum gauge 30 has a predetermined position in the casting frame 4. The pressure of is led. Further, when the air cylinder 38 is driven in the direction for accommodating the piston rod, the pressure reduction detection attachment 36 rises, and the pin 36p of the pressure reduction detection attachment 36 is pulled out from the vertical through hole 14t.
Further, the tip surface 36f of the decompression detection attachment 36 is separated from the upper plate 14u of the small chamber 14,
The connection between the pressure detection pipe 20 and the vacuum gauge 30 is released. That is, the vacuum gauge 30, the pressure detection pipe 34, and the depressurization detection attachment 36 function as a pressure detection sensor, and the depression 36h of the depressurization detection attachment 36.
Functions as the pressure detection port of the pressure detection sensor. Further, the air cylinder 38 functions as a pipe connection mechanism that connects the pressure detection port and the pressure guiding pipe.

Next, the operation of the vacuum filling and casting apparatus according to this embodiment will be described. First, a casting frame 4 accommodating a predetermined amount of foundry sand 2 is positioned at a casting position, and a pipe from a pressure reducing device and a pipe from an air source are connected to the casting frame 4.
When the casting flask 4 is set as specified, the pressurizing valve provided in the casting flask 4 is opened and compressed air is supplied from the air source to the decompression chamber 4c. As a result, air flows from the decompression chamber 4c into the casting frame 4 through the intermediate plate 4n. When the casting sand 2 is brought into a fluidized state by the air flowing into the casting frame 4, the vanishing model 1 is buried in the casting sand 2. And the disappearing model 1 is a casting frame 4
When positioned at a predetermined position inside, the pressurizing valve is closed, and as shown in FIG. 1, the fusible film 10 is put on the casting frame 4. Next, the air cylinder 38 attached to the gantry 32 is driven in the direction in which the piston rod extends, and the decompression detection attachment 36 descends. Further, air is blown out from the air nozzle 36a housed in the pin 36p of the pressure reduction detection attachment 36, and the foundry sand 2 and dust at the portion where the tip surface 36f of the pressure reduction detection attachment 36 abuts is blown off. Then, as shown in FIG. 3, the reduced pressure detection attachment 36
When the tip surface 36f of the pin comes into contact with the upper plate 14u of the small chamber 14 through the disappearing film 10, the pin 36p
Of the disappearing film 1 by inserting the tip of the
No. 0 is drilled, and the pressure detection pipe 20 mounted on the casting frame 4 and the pressure detection pipe 34 of the vacuum gauge 30 are connected via this pressure reduction detection attachment 36 and the vertical through hole 14t. The air nozzle 36a is connected to the pressure detecting pipe 20 and the pressure detecting pipe 34.
The release of air from is stopped.

Next, the suction valve 6 provided in the casting frame 4 is opened to reduce the pressure in the decompression chamber 4c. As a result, the inside of the casting frame 4 is indirectly depressurized via the intermediate plate 4n, and the foundry sand 2 is sucked downward and solidified. Further, the disappearing film 10 has a molding sand 2 at the center thereof.
Is adsorbed on the surface of the casting chamber 4, and the edge portion thereof is further adsorbed on the vertical through hole 14t of the upper plate 14u of the small chamber 14, so that the casting frame 4 is securely covered and the sealing property inside the casting frame 4 is secured. . Then, the pressure at a predetermined position in the casting flask 4 is constantly measured by the vacuum gauge 30. In this state, molten metal is injected from the sprue part of the vanishing model 1 for casting. Here, since the decompression inside the casting frame 4 is continuously performed during casting, the molten metal flow is improved and the gas generated by the combustion of the vanishing model 1 is also efficiently discharged. As described above, according to the vacuum filling and casting apparatus according to the present embodiment, for example, the pressure change due to the clogging of the intermediate plate 4n made of the porous sintered plate and the pressure change due to the damage of the casting frame 4 can be managed very easily. Further, since the vacuum gauges 30 can be automatically set for the flasks 4 at the casting position, it is not necessary to keep the vacuum gauges 30 in each of the flasks 4, so that the cost of the flasks can be reduced. Further, when the flask 4 is not in the casting position, the vacuum gauge 30 is not attached to the flask 4, so
The vacuum gauge 30 will not be damaged due to movement of the vacuum gauge.

[0015]

As described above, according to the present invention, it is not necessary to always have a pressure detecting sensor in the flask, so that the cost of the flask is reduced. Further, damage to the pressure detection sensor is reduced.
This reduces the equipment cost for monitoring the pressure in the flask.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a main part of a vacuum filling and casting apparatus according to an embodiment of the present invention.

FIG. 2 is a detailed view of II in FIG.

FIG. 3 is a detailed view of III in FIG.

FIG. 4 is a graph showing a pressure distribution in a flask.

[Explanation of symbols]

1 Disappearance model 2 Foundry sand 4 Casting frame 14t Vertical through hole (pressure guiding pipe) 20 Pressure detection pipe (pressure guiding pipe) 30 Vacuum gauge (pressure detection sensor) 34 Pressure detection pipe (part of pressure detection sensor) 36 Decompression detection attachment (part of pressure detection sensor) 36h Recess (pressure detection port) 38 Air cylinder (pipe connection mechanism)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keiichi Morita 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Automobile Co., Ltd.

Claims (1)

[Claims] 1. The molding sand is stored in a molding frame having an open upper part, the disappeared model is buried in the molding sand, the interior of the molding frame is decompressed from below to fix the molding sand, and then the molding sand is fixed. In a vacuum filling and casting apparatus for injecting molten metal from the spout of the vanishing model to cast a product having almost the same shape as the vanishing model, one end is positioned at a predetermined position in the foundry sand through a filter, A pressure guiding pipe whose end is positioned outside the casting frame, a pressure detection sensor installed at a position different from the casting frame, and the pressure detection in a state where the casting frame is positioned at the casting position. A reduced pressure filling casting apparatus comprising: a pipe connecting mechanism that connects the pressure guiding port and the pressure detecting port by bringing the pressure detecting port of the sensor into contact with the other end of the pressure guiding pipe.