JPH0438938Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a suction casting device, and more particularly, to a suction casting device that can obtain desired pressure reduction characteristics when reducing the pressure inside a cavity. It is something.

(Prior Art) Molten metal is injected into the cavity of a mold via a stalk by various means, one of which is a suction casting method. This is intended to reduce the pressure inside the cavity using a vacuum source such as a vacuum pump, and to supply molten metal from the stalk into the cavity due to the pressure difference with the atmosphere. Incidentally, there is the so-called vacuum casting method, which has a similar name to the suction casting method, but this method reduces the pressure inside the cavity in order to improve the fill-up properties of the molten metal inside the cavity. This is the only problem. Therefore, it is referred to as having a different technical meaning from the suction casting method of the present application.

In the conventional suction casting method, the pressure inside the cavity is reduced by simply communicating a vacuum pump with the cavity, and the degree of pressure reduction during the process of pressure reduction is not particularly adjusted.

By the way, the filling speed of molten metal in the cavity depends on the speed of depressurization in the cavity, but in the case of simple depressurization in the conventional suction casting method, the filling speed is directly influenced by the capacity of the vacuum pump. .

On the other hand, experiments and research by the inventors of the present application have revealed that the filling speed of molten metal is not necessarily constant, but should be changed as appropriate depending on the conditions, from various viewpoints such as improving product quality and making work easier. It has been found that it is preferable to vary the rate of pressure reduction in the cavity, that is, the pressure reduction characteristics, even after filling is completed.

Therefore, as a means to obtain such desired pressure reduction characteristics, for example, as shown in FIG.
The first idea is to provide a manual valve 20 whose opening degree can be adjusted in the communication pipe 3 that connects the cavity in the mold 1 and the vacuum pump 2, and to adjust the reduced pressure by adjusting the opening degree of this manual valve 20. be.

However, according to this method, as shown in Fig. 4, the characteristic curve A when no opening adjustment is performed.
In order to change the characteristic curve B to a polygonal characteristic curve B, the opening degree of the manual valve 20 must be manually adjusted at each corner point a, b, and c. Manual opening adjustment like this is a bottleneck in streamlining work.
Furthermore, errors in the opening degree are likely to occur. If an attempt is made to automate this opening adjustment, the valve mechanism and control mechanism will become complicated, resulting in a significant disadvantage in terms of cost and maintenance.

In order to solve the above-mentioned inconvenience, the present inventors first
A method and device for easily obtaining a desired decompression characteristic curve were proposed (Japanese Patent Application Laid-open No. 143113-1983).
issue). That is, a plurality of branch passages are provided in the middle of a communication passage (suction passage) that connects the cavity 1 and the vacuum source, and the air suction speed of the branch passages is adjusted by various combinations of opening and closing of the plurality of branch passages. This is a method and apparatus for adjusting the pressure reduction by changing the .

(Problems to be Solved by the Invention) However, although good pressure reduction characteristics can be obtained with this method and apparatus, it has been found that there are the following problems.

During suction casting, gases and impurities generated in the cavity inevitably pass through the branch flow path, and in particular, when using cores and producing the necessary casting products, for example, binders of shell cores, etc. When the resin is fired, a large amount of gas and sticky substances are generated, which adhere to the walls of the relatively narrow branch channels in a tar-like manner, as well as to the valves that open and close the branch channels. However, there is a problem in that the operation becomes defective. This malfunction occurs frequently, and maintenance thereof is extremely troublesome.

In addition, since the branch flow path is a pressure reduction system, the diameter of the piping must be increased, which requires a large amount of space for the multiple branch flow paths installed in the middle of the communication path, and the valves used for opening and closing must also be large. There is a problem in that the manufacturing cost is also high.

The present invention has been developed in view of the above facts, and its purpose is to provide a suction casting device that has excellent pressure reduction characteristics and requires as little maintenance as possible.

(Means for Solving the Problems) In order to achieve the above object, the suction casting device of the present invention is provided with an air supply flow path for supplying pressurized air in the middle of the suction flow path connecting the cavity and the vacuum source. A plurality of branch channels each having a solenoid valve and a manual valve are provided in the middle of the air supply channel, and the solenoid valves of each branch channel whose opening degree is adjusted by the manual valve are selectively opened and closed to control the air supply flow. It is characterized by being equipped with an automatic opening/closing means for a solenoid valve that changes the amount of air passing through the passageway.

In other words, the amount of air passing through the air supply flow path is adjusted by changing the opening degree of the manual valve stepwise to change the amount of air passing through each branch flow path per unit time. This is done by selecting whether to open or close a solenoid valve.

Examples of the above-mentioned automatic solenoid valve opening/closing means include an electronic control device, a timer operating device, etc., which switches the on-off state of each solenoid valve in response to a signal from a pressure sensor provided at an appropriate position. .

A means for supplying pressurized air, such as a compressor, is provided on the upstream side of the air supply flow path, thereby making it possible to accurately adjust the pressure and to reduce the diameter of the air supply flow path.

(Function) In this configuration, the amount of air drawn from inside the cavity by the vacuum source changes depending on the amount of air supplied from the air supply channel to the suction channel. That is, by adjusting the amount of air supplied from the air supply flow path to the suction flow path, the pressure reduction speed within the cavity can be adjusted.

Since the air supply channel has a plurality of branch channels, the amount of air passing through the air supply channel can be adjusted by selecting the number of channels to be blocked from among the branch channels whose openings have been adjusted. I can do it.

Therefore, desired pressure reduction characteristics can be obtained by various adjustments in the plurality of branch channels. The branch channels are installed in a pressurized system where gases and sticky substances generated by firing the binder in the shell core do not flow, so sticky substances adhere in the form of resin in the branch channels of conventional depressurized systems. Valve malfunction, which was caused by this, no longer occurs.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings, but the present invention is not limited thereby.

As shown in the schematic diagram of FIG. 1, the suction casting apparatus of this embodiment has an air supply pipe 4 which is connected to a suction pipe 3 that connects a cavity in a mold 1 and a vacuum pump 2. is provided. A plurality of branch pipes 5 to 9 are provided in the middle of this air pipe 4,
Each of the branch pipes 5 to 9 has a solenoid valve 10 to 14 for blocking the flow path thereof, and a means valve 15 to 19 arranged in series with the solenoid valve and capable of adjusting the opening degree of the valve. and is provided.

The air supply pipe 4 between the branch pipes 5 to 9 and the suction pipe 3 is provided with a manual valve 21 that can adjust the flow rate of air flowing through the entire pipe 4. is connected to a compressor 23 that sends out machining air. Further, the suction pipe 3 is provided with a manual valve 20 for adjusting the amount of air suction.

Next, a method of using the suction casting apparatus configured as described above will be explained.

First, prior to casting, the vacuum pump 2 is activated, the electromagnetic valves 10 to 14 of the branch pipes 5 to 9 are opened, and compressed air is sent by the compressor 23. Next, the manual valves 20 and 21 are adjusted so that the inside of the cavity of the mold 1 is neither depressurized nor pressurized, and the timer mechanism of the controller 22 is set. Then, when the controller 22 is activated, the electromagnetic valve 10 is closed and pressure reduction in the cavity of the mold 1 is started (at this time, the electromagnetic valves 11 to 14 are open). As the pressure inside the cavity is reduced, the molten metal rises in the stalk and is injected into the cavity, but at this time, the timer mechanism opens the solenoid valve 10 and at the same time closes the solenoid valve 11. Then, the second
As shown in the characteristic curve diagram in the figure, the electromagnetic valve 10
However, after the open point d, the straight line has a different slope than before. Then, the injection of molten metal continues in this state, and when the injection reaches point e where the injection ends, the electromagnetic valve 11 is also opened.In this way, the electromagnetic valves 10 to 14 are automatically shut off or opened by the controller 22. This makes it possible to obtain a polygonal decompression characteristic curve that changes stepwise.
The slope of the straight line at each stage can be changed by selecting and combining various opening adjustments of the manual valves 15 to 19.

The above is a basic embodiment of the present invention, but in this embodiment, when returning the inside of the cavity from a reduced pressure state to an atmospheric pressure state, the same procedure as described above is performed.
It is possible to return in stages.

(Effects of the invention) The suction casting device of the invention provides the following effects.

First, when adjusting the pressure reduction in the cavity, various desired pressure reduction characteristics can be obtained by simple means, so that high-quality cast products can be provided without difficulty.

In addition, even if a lot of resin is generated during casting due to the use of cores, etc., there will be no malfunction in the operation of the electromagnetic valve, greatly simplifying the maintenance of the suction casting equipment, and at the same time, reducing the maintenance of the equipment. Reliability also increases.

Furthermore, by flowing compressed air through a plurality of branch channels, the diameter of the pipes, as well as the electromagnetic valves, manual valves, etc., can be reduced, and their manufacturing costs can be reduced.

Moreover, the load on the vacuum pump can be kept constant;
This has the advantage of not putting strain on the pump and extending its service life.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the suction casting apparatus of the present invention, FIG. FIG. 4 is an explanatory diagram of the problems of the prior art. In the figure, 1... Mold, 2... Vacuum pump (vacuum source), 3... Suction pipe (suction channel), 4... Air supply pipe (air supply channel), 5 to 9... Branch pipe (branch flow path), 1
0-14...Solenoid valve, 15-21...Manual valve, 23...Compressor.

Claims (1)

[Scope of utility model registration request] An air supply passage for supplying pressurized air is provided in the middle of the suction passage connecting the cavity and the vacuum source, and a plurality of branch passages each having an electromagnetic valve and a manual valve are provided in the middle of the air supply passage, and further A suction casting device characterized by being provided with an automatic electromagnetic valve opening/closing means for selectively opening and closing electromagnetic valves of each branch flow path whose opening degree is adjusted by a manual valve to change the amount of air passing through the air supply flow path.