JPH03138061A - Reducing pressure type die casting method - Google Patents

Abstract

PURPOSE:To improve a die casting product without reconstructing the die casting machine in large scale by pressing molten metal into a forming space under condition of beforehand sufficiently evacuating air in the die in the reducing pressure die casting method. CONSTITUTION:After clamping a fixed die 1 and a movable die 2, the molten metal (a) is poured into a pressurized chamber 11 from a sprue 12 thereof. Successively, the pouring is stopped under condition of closing the sprue 12 by pressing a plunger 10 into there. Then, an evacuating pump 18 communicated with the forming space 14 in the die through an evacuating way 15 and a valve 17 with filter is actuated and the air in the forming space 14 and runner 13 is gradually evacuated in so degree that the molten metal (a) is not spattered. At the time, when the forming space 14 and the runner 13 come to the prescribed reducing pressure condition, the evacuating way 15 is closed with a core 15, and after that, the molten metal (a) is pressed into the forming space 14 with the plunger 10 to execute the die casting formation. Therefore, the die casting product having high quality without any blow hole, is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a casting method, and particularly to a vacuum die casting method capable of producing high quality die casting products.

(Conventional technology and its issues) In the normal die casting method, blowholes often remain inside the casting, so the air inside the mold is forcibly removed to prevent air from being drawn in when pouring molten metal. A vacuum die casting method was devised.

However, in the conventional vacuum die casting method, the molding space in the mold and the air in the runner are instantly evacuated during high-speed operation during plunging, so timing of both is extremely difficult, and the exhaust time is insufficient. Blowholes have not been completely prevented since sufficient exhaustion is not possible. In addition, since the exhaust and the pushing of the molten metal are performed in parallel, the exhaust valve is often clogged with the molten metal, which poses a problem in productivity.

Therefore, an object of the present invention is to improve the quality of die-cast products by improving the conventional vacuum die-casting method without making extensive modifications to the die-casting machine.

(Means for Solving the Problems) In order to solve the above problems, the reduced pressure die-casting method of the present invention injects molten metal into a pressurized chamber from a pouring port, then closes the pouring port with a plunger, and then The air in the molding space and runners in the mold is forcibly exhausted through an exhaust path to bring the molding space and runners into a predetermined depressurized state, and then the exhaust path is closed and the molten metal in the pressurized chamber is discharged by a plunger. It was then pushed into the molding space.

[Effect]

In the above-mentioned reduced pressure die casting method, the air inside the mold is evacuated in advance, so there is no need to consider the timing of pushing in molten metal as in the conventional method, and the mold can be cast without being subject to time constraints. The air inside can be reliably exhausted.

Also, when pushing the molten metal in the pressurized chamber into the molding space,
Since the exhaust duct is closed, molten metal will not enter the exhaust system.

〔Example] Examples will be described below with reference to the drawings.

As shown in FIGS. 1(a) and 1), after clamping the fixed mold 1 and the movable mold 2, molten metal a is poured into the pressurizing chamber 11 from the pouring port 12 of the pressurizing chamber 11. do. At this time, as shown in FIG. 1(a), the core 16 for blocking the exhaust path 15 is open.

Next, as shown in FIGS. 2(a) and 2(b), the plunger 10 is pushed in and stopped with the pouring port 12 closed. Then, the exhaust pump 18, which communicates with the molding space 14 in the mold via the exhaust pipe 15 and the filter-equipped valve 17, is started, and as shown by the arrow in the figure, the molding is carried out to the extent that the molten metal a does not scatter. Space 14 and runner 13
gradually exhaust the air.

When the molding space 14 and the runner 13 reach a predetermined reduced pressure state, as shown in FIGS. 3(a) and 3(b),
The exhaust passage 15 is closed by the core 16, and then the molten metal a is forced into the molding space by the plunger 10 to perform die casting.

Note that it is more effective to seal the mold mating surface or the like in order to increase the degree of vacuum inside the mold.

According to the above method, the air in the molding space 14 and the runner 13 can be reliably exhausted, and when the molten metal a is pushed into the molding space 14, the molten metal will not enter the exhaust system. Therefore, clogging of the external fill valve 17 does not occur.

〔effect〕

As described above, the vacuum die-casting method of the present invention can produce high-quality die-cast products.

Furthermore, since the exhaust system is closed when molten metal is pushed in, the molten metal does not enter the exhaust system, allowing efficient use of the device.

[Brief explanation of the drawing]

1 to 3 show the manufacturing process of die-cast products by the reduced pressure die-casting method of the present invention, each figure (a) is a cross-sectional view of the mold part, and each figure (b) is a cross-sectional view of the mold part. FIG. 1...Fixed mold, 2...Movable mold, 10...Plunger, 11...
・Pressure chamber, 12...Pouring port, 13...
... Runway, 14 ... Molding space, 15
...Exhaust path, 16... Core, 17... Valve with filter, 18...
・Exhaust pump.

Claims (1)

[Claims] (1) After injecting molten metal into the pressurized chamber from the pouring spout, the pouring spout is closed with a plunger, and then the air in the molding space in the mold and the runner is forcibly exhausted from the exhaust passage to form the molding space. and a reduced-pressure die-casting method, in which the runner is brought into a predetermined reduced pressure state, the exhaust path is then closed, and the molten metal in the pressurized chamber is pushed into the molding space with a plunger.