JPS5916866B2 - High pressure solidification casting equipment - Google Patents

Description

[Detailed description of the invention] The present invention particularly relates to a high pressure solidification casting apparatus.

Generally, when injecting molten metal into a mold, injection into the mold is performed at high speed, and as necessary, the injection speed is sequentially switched to low speed, although there are differences depending on the cooling rate of the molten metal, the material of the product, and the application. It is normal to apply the necessary pressure.

Therefore, when injecting at high speed, the flow rate of pressurized oil for cylinder operation is extremely large, so it is recommended to perform high-speed injection using an accumulator or the like, and then switch to low speed by sequentially switching valves. It is being

In this case, speed control is performed by adjusting a throttle valve or the like, but since an accumulator is used, there is a risk of fluctuations in speed or pressure.

The purpose of the present invention is to eliminate the above-mentioned drawbacks and provide a high-pressure solidification casting apparatus that can arbitrarily change the injection speed as necessary. The large-diameter head end of the increasing cylinder that increases the amount of fluid at a constant rate is connected to the injection cylinder, and the small-diameter rond end of the increasing cylinder is connected to the variable displacement pump via a switching valve to increase the amount of fluid at a constant rate. By connecting a low-pressure high-speed circuit that sends fluid increased by the ratio to the injection cylinder and fluid discharged from a variable displacement pump directly to the injection cylinder via a switching valve, and changing the discharge volume of the variable pump. The present invention is characterized in that a high-pressure, low-speed circuit is formed to directly supply the required amount to the injection cylinder, and the low-pressure, high-speed circuit and the high-pressure, low-speed circuit are switched for use during the injection process.

A variable discharge pump that can change the discharge amount arbitrarily according to a command is used, and this variable discharge pump is combined with an increase cylinder that increases the pump discharge amount at a fixed ratio.

This makes it possible to provide the necessary flow rate for high-speed injection, and also to change the discharge amount arbitrarily based on commands, thereby making it possible to control the injection speed of the injection cylinder in any way.

Furthermore, during the high-pressure compression process of the molten metal, pressurized oil is supplied from a high-pressure circuit separate from the increase cylinder, making it possible to supply both the flow rate and the necessary pressure.

Embodiments of the present invention will be described below with reference to the drawings.

In Fig. 1, 1 is an injection cylinder equipped with an injection plunger 2 that can be freely moved in and out, and 3 is an increase cylinder that houses a piston 3c in a cylinder consisting of a large diameter part 3a and a small diameter part 3b. The portion 3a is communicated with the flow port 1a of the injection cylinder 1 via a pilot check valve 10 and a check valve 11.

Reference numeral 4 designates a variable displacement pump connected to the increasing cylinder 3 and the injection cylinder 11/c through switching valves 5 and 6, respectively.

A check valve 7, a relief valve 8, and a pressure switch 9 are provided in a circuit that communicates the switching valve 5 with the large diameter portion 3a and the small diameter portion 3b of the increase cylinder 3, respectively.

Further, a pilot check valve 12, a pressure reducing valve 13, and a relief valve 15 are provided in a circuit that communicates the switching valve 6 and the flow port 1a of the injection cylinder 1, and a check valve 14 is connected in parallel with the pressure reducing valve 13. There is.

Next, the non-embodiment ρ effect having the above-described configuration will be explained.

When the variable displacement pump 4 is operated and pressure oil is sent to the small diameter part 3b of the increase cylinder 3 through the switching valve 5, the pressure oil is discharged from the large diameter part 3a of the increase cylinder 3 at a constant increase ratio. and pilot check valve 10 and check valve 1
1 and is supplied to the head side of the injection cylinder 1 from the flow port 1a, so the injection plunger 2 is pushed out at high speed.

By operating the injection plunger 2, the molten metal is injected at high speed through a device not shown until the mold is filled.

The resistance in this case is the flow resistance of the molten metal and the pressure resistance of the gas in the mold, and it is sufficient to apply enough pressure to overcome these resistances.

On the other hand, the pressure oil existing in the injection cylinder 1 is discharged from the flow port 1b and returned to the oil tank via the switching valve 6.

When the mold is filled with molten metal, the pressure in the flow port 1a of the injection cylinder 1 increases.

That is, the pressure at the outlet (large diameter portion 3a) and inlet (small diameter portion 3b) of the increase cylinder 3 increases.

The specified pressure at this time of increase is detected by the pressure switch 9, and this detection signal operates the high-pressure side switching valve 6, and the pressure oil is sent to the injection cylinder 1 from the flow port 1a via the check valve 12 and the pressure reducing valve 13. Push out the injection plunger 2 further.

For this reason, we completely compress the trace gases present in the mold from the state where the mold is filled with molten metal to form a complete product, and also prevent solidification shrinkage holes and pinballs from occurring in the product. It is possible to apply high pressure to the molten metal and maintain it at high pressure until the product cools to a certain temperature.

The specified pressure when the pressure inside the increase cylinder 3 increases is adjusted by a pressure reducing valve 13 and a relief valve 15.

Furthermore, if it is desired to regulate the upper limit of the pressure when the increase cylinder 3 is used, the relief valve 8 may be adjusted.

Note that the injection cylinder 1 feeds the molten metal into the mold through the injection plunger 2 by supplying pressure oil through the pressure oil port 1a, but the feeding speed is high until the mold is filled with the molten metal. If it does not sink in, the molten metal will cool down and the water will not circulate properly.

Therefore, high-speed injection is performed until the molten metal is almost filled.

Next, when the mold is almost filled with molten metal, the gas remaining in the mold and the molten metal is completely compressed, and the molten metal is compressed to prevent pinholes from forming in the product and to give the product a perfect shape. Maintain high pressure until cooled.

In another embodiment shown in FIG. 2, a relief valve 16 is connected to the discharge side of the variable displacement pump 4, and this relief valve 16 is connected to pilot relief valves 18 and 19 arranged in parallel via a switching valve 1T. , is different from the embodiment (FIG. 4) in that the relief valve 8 on the switching valve 5 side and the pressure reducing valve 13, check valve 14, and relief valve 15 on the switching valve 6 side in the embodiment in FIG. Since the other configurations are the same, the explanation will be omitted.

Note that the same reference numerals shown in FIGS. 1 and 2 indicate the same parts.

In the embodiment configured in this manner, high-speed low-pressure injection and low-speed high-pressure injection can be performed by switching the switching valve 17 and adjusting the respective set pressures of the pilot relief valves 18 and 19.

FIG. 3 shows the relationship between the molten metal resistance (molten metal pressure) and time in the above-described embodiment.

Region A in the figure is the resistance of the molten metal in the range of the circuit using high-speed injection, that is, the increasing cylinder 3, and when the mold is filled with molten metal, the pressure begins to rise rapidly.

Point B is that this increased pressure is detected by the pressure switch 9 and the high pressure injection, that is, the high pressure circuit is activated.

After that, the high voltage circuit is operated and the high voltage is maintained until the product is completed.

Further, region C is the molten metal resistance in the range used for low-speed high-pressure injection, that is, a high-pressure circuit.

FIG. 4 shows the relationship between the speed of the injection cylinder and time corresponding to FIG. 3, and A in FIG.

C shows the velocity of the injection cylinder in a range similar to that in FIG. 3, and B shows a point similar to that in FIG.

According to this embodiment, the surge pressure that occurs at the end of high-speed injection, that is, when the mold is filled with molten metal, is suppressed by the increase cylinder, so a large pressure increase does not occur, so the mold clamping force is reduced. There is no fear that there will be a shortage.

As explained above, according to the present invention, by changing the injection speed as necessary, it is possible to improve the mechanical properties of the product and to obtain a product free from defects such as solidification shrinkage holes and pinholes. I can do it.

Furthermore, according to the present invention, by setting the pressure booster cylinder to give the optimum increase ratio depending on the application of the product, the capacity of the variable displacement pump can be reduced, the motor horsepower can be used efficiently, and the injection speed can be freely controlled. It becomes possible.

[Brief explanation of the drawing]

1 and 2 are hydraulic circuit diagrams showing an embodiment of the high-pressure solidification and casting apparatus of the present invention, and FIGS. 3 and 4 are diagrams for explaining the same embodiment. 1...Injection cylinder, 2...Injection plunger, 3...Increasing cylinder, 4...
...Variable displacement pump, 5.6...Switching valve.

Claims (1)

[Claims] 1. Connect the large diameter side of an increasing cylinder that increases the amount of fluid discharged from a variable displacement pump at a fixed ratio to an injection cylinder having an injection plunger to the injection cylinder → U, and connect the small diameter side of the increasing cylinder through a switching valve. A low-pressure high-speed circuit is connected to the variable displacement pump side to send fluid increased at a fixed ratio to the injection cylinder, and the fluid discharged from the variable displacement pump is connected directly to the injection cylinder via a switching valve. A high-pressure low-speed circuit is formed to directly supply the required amount to the injection cylinder by changing the discharge amount of the variable pump, and the low-pressure high-speed circuit and the high-pressure low-speed circuit are switched for use during the injection process. High pressure solidification casting equipment.