JPH0749145B2 - Injection controller for vertical die cast machine - Google Patents

Description

TECHNICAL FIELD The present invention relates to an injection control device for controlling the injection speed of molten metal in a vertical die casting machine.

(Prior Art) In a vertical die casting machine, molten metal (molten metal) in a vertically arranged injection sleeve is pushed upward from below by an injection plunger, and the upper end opening of the injection sleeve is fitted. The molten metal is injected into the mold cavity through the gate of the mold. Therefore,
The injection speed of the molten metal into the mold cavity can generally be changed by changing the push-up speed of the injection plunger. For example, in the injection device described in JP-A-59-215259, the speed of the injection plunger is changed within one injection stroke, and the injection speed of the molten metal is controlled in two steps.

(Problems to be Solved by the Invention) Here, in controlling the injection speed of the molten metal as described above, basically, it is necessary to reduce the temperature of the molten metal until the molten metal is cast into the mold cavity. A higher injection speed is desirable because it needs to be minimized. However, when injection is performed at high speed, the molten metal is filled in the mold cavity, and the air in the cavity is discharged to the outside through the air vent holes formed in the mold or between the split surfaces of the mold. As a result, the molten metal entrains air, resulting in voids in the molded product. Also,
When the injection speed is high, in the process of injecting the molten metal into the mold cavity, the molten metal is filled in the cavity before the solidified layer is formed on the surface of the injected molten metal. As a result, the molten metal may enter between the split surfaces of the mold, and a large amount of flash may occur in the molded product.

The present invention has been made in view of the above-mentioned points, and is a vertical die cast that controls injection of molten metal so that injection can be performed in as short a time as possible without causing air inclusion and flashing. It is intended to provide an injection control device for a machine.

(Means for Solving Problems) In order to achieve the above object, an injection device of a vertical die casting machine according to the present invention is a split die formed by upper and lower molds from an injection port of the vertical die casting machine. In an injection control device for controlling the injection speed of a molten metal injected into a cavity having a surface, an injection machine for injecting the molten metal into the cavity and a signal for controlling an injection speed from the injection machine are generated. The control unit and the injector at the first injection speed from the start of the injection operation upon receiving a signal from the control unit to the time when the melt is filled up to the split surfaces of the upper and lower molds in the cavity. High-speed injection means for operating so as to perform injection of the molten metal, and the injector after the molten metal is filled up to the dividing surface until the state immediately before the completion of the molten metal filling in the cavity is reached. A medium-speed injection unit that operates to inject the molten metal at a second injection speed that is slower than the first injection speed; and And a low-speed injection unit that operates so as to inject the molten metal at a third injection speed lower than the second injection speed.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention. In the figure, 1 is a fixed mold, 2 is a movable mold, the fixed mold 1 is arranged horizontally with its split surface 1a facing upward, and the movable mold 2 is arranged above the fixed mold 1. The split surface 2a is arranged horizontally with the split surface 2a facing downward, and a cavity 3 is formed between these two molds. Further, in the fixed mold 1, a gate 1b communicating with the cavity 3 extends vertically downward, and a lower end thereof has a sleeve fitting hole having an inner diameter larger than that of the gate 1b.
1c is formed coaxially. Furthermore, in the movable mold 2,
Air vent hole 2b for letting air in the cavity 3 escape to the outside
Are formed.

Below the mold 1, a molten metal injection machine 11 having the same axis as the gate 1b is arranged. The injector 11 can swing within a certain angle range from the vertical state shown in the drawing in a vertical plane including the axis of the injector. The injection machine 11 has, at its upper end, a fitting hole 1c for the mold 1 described above.
It has a cylindrical injection sleeve 12 which can be fitted inside, the sleeve 12 being mounted on the upper end of a housing 13 whose upper half extends downwards in a frustoconical shape. The housing 13 includes piston rods 15a, 1 of hydraulic cylinders 15, 17.
It is supported above the upper end surface 19c of the injection cylinder 19 via 7a. An injection plunger 21 is slidably inserted into the injection cylinder 19, and a space inside the cylinder 19 is divided into hydraulic chambers 19a and 19b by a base end 21a of the plunger. Meanwhile, this injection plunger 2
An upper end side of 1 penetrates the inside of the housing 13 and a tip portion 21b thereof is slidably fitted into the injection sleeve 12.

In the injection machine 11 having this configuration, first, the injection machine 11 is tilted to the position indicated by the broken line in the figure, and a required amount of molten metal is injected into the sleeve 12. Next, the hydraulic chambers 15b, 1 of the hydraulic cylinders 15, 17
When hydraulic pressure is applied to the inside of 7b, the injection sleeve 12 is moved upward from its retracted position and fitted into the fitting hole 1c of the fixed mold 1. After that, by applying hydraulic pressure to the hydraulic chamber 19b of the injection cylinder 19 or removing the hydraulic pressure from the hydraulic chamber 19a, the injection plunger 21 is pushed upward, and the molten metal injected into the sleeve 12 by its tip 21b. 23 is injected into the cavity 3 through the gate 1b of the mold 1.

Next, the structure of the hydraulic circuit for controlling the injection speed of the molten metal will be described. In FIG. 1, 31 is a hydraulic pressure supply source including a hydraulic pump and the like, and 33 is a directional control valve having three positions. The direction control valve 33 is connected to four switching valves 37, 39, 41, 43 arranged in parallel via the oil passage 5. Among these valves, the three valves 37, 39, 41 have their other end sides through the flow rate adjusting valves 45, 47, 49, respectively, and the hydraulic chamber 19 of the injection cylinder in the injector 11 having the above-described configuration.
connected to a. On the other hand, the remaining one valve 43 is directly connected to the hydraulic chamber 19a at the other end side. The other hydraulic chamber 19b of the injection cylinder, via the oil passage 51,
It is connected to the directional control valve 33 described above. Reference numeral 53 is a position sensor for detecting the moving position of the injection plunger 21, and is composed of, for example, a plurality of limit switches. Each of the valves 33, 37, 39, 41, 43 described above is of an electromagnetic drive type, and their control is performed by a drive signal from the control unit 55. Here, the flow rates regulated by the flow rate control valves 45, 47, 49 are set to decrease in this order.

Next, the injection control of the molten metal of this example configured as described above will be described. First, at the start of injection of molten metal, as shown in FIG. 1, the injection plunger 21 is pushed down to the bottom, and the hydraulic chamber 19a is filled with hydraulic oil. The valves 37, 39, 41, 43 are also in the closed position and the valve 33 is set in its block 33b. In this state, the drive signal from the control unit 55 urges the solenoid of the valve 37 to set it to the open position. At the same time, the valve 33 is also energized to switch to the block 33a. As a result, the hydraulic pressure acts on the hydraulic chamber 19b of the cylinder via the valve 33, while the hydraulic oil in the hydraulic chamber 19a is discharged through the valves 45 and 37 sequentially. The flow rate of hydraulic oil discharged here is determined by the valve 45
Plunger 21
Is pushed upwards at high speed, so that the molten metal in the sleeve 12 is injected at high speed into the mold cavity 3 through the gate 1b. By this injection, when the molten metal is filled up to the positions of the split surfaces 1a and 2a in the cavity 3, the state is detected by the sensor 53 which detects the position of the plunger 21, whereby the valve 37 is replaced. Valve 39 is opened. Valve 39
The flow rate set by the flow control valve 47 connected to
Since the value is smaller than that of the valve 45 described above, the plunger 21 is pushed up at a medium speed thereafter, so that the molten metal is injected at a medium speed. Next, just before the molten metal was filled into the mold cavity 3, the plunger 21
The valve 41 is now opened instead of the valve 39 when detected from the position. As a result, the plunger 21 is pushed up at a slower and lower speed, and even after the filling of the molten metal is completed, the low speed allows the molten metal filled in the cavity 3 to be pressurized.

Then, after filling and pressurization is completed, the valve 33 is switched to the position of the block 33c, and the valve 43 is opened instead of the valve 41. As a result, the hydraulic pressure is applied to the hydraulic chamber 19a and the hydraulic chamber 19b communicates with the drain side, so that the plunger 21 is quickly pushed down to the position shown in the figure.

The graph shown in Fig. 2 shows the push-up speed of the plunger 21 during high-speed, medium-speed and low-speed injection control at 100 mm / s and 70 m, respectively.
The figure shows an example in the case of setting to m / s and 5 mm / s.

As described above, in this embodiment, the molten metal is injected at high speed up to the split surface, and then at medium speed. That is, high-speed injection is performed while the air escape path in the cavity 3 is between the split surfaces 1a and 2a and the hole 2b, and medium-speed injection is performed after the air escape path is only the hole 2b. It is possible to fill the molten metal in the cavity 3 while allowing the air in the cavity 3 to smoothly escape to the outside. Therefore, the inclusion of air can be avoided, and no cavity is formed in the molded product. Further, immediately before the completion of the filling of the molten metal, since the low-speed injection is performed, the pressure is applied after the suitable solidified layer is generated on the surface of the filled molten metal. It is possible to avoid the problem that the molten metal invades between the split surfaces 1a and 2a of the mold to generate flash.

Next, FIG. 3 shows another example of the hydraulic circuit for controlling the movement of the plunger 21. In this example, the supply rate of the hydraulic oil applied to the hydraulic chamber 19b side of the hydraulic cylinder is changed to switch the injection speed of the molten metal in three stages. That is, the flow control valves 61, 62, and 63 in the figure are
They are used for high-speed injection, medium-speed injection, and low-speed injection, respectively.

(Effects of the Invention) As is clear from the above description, in the present invention, high-speed injection is performed from the start of injection of the molten metal until the molten metal is filled up to the split surface of the mold, and thereafter the molten metal Injection is performed at a medium speed until just before the mold cavity is filled, and then at a low speed, injection is performed at a low speed. It has an advantage that the injection operation can be performed in a short time.

[Brief description of drawings]

1 is an overall configuration diagram showing an embodiment of the present invention, FIG. 2 is a characteristic diagram showing the relationship between the position of the injection plunger and time,
FIG. 3 is a circuit diagram showing another example of the hydraulic circuit. 1, 2 ... Mold, 1a, 2a ... Split surface 12 ... Injection sleeve, 19 ... Injection cylinder 21 ... Injection plunger, 23 ... Molten metal 31 ... Hydraulic pressure source 33, 37, 39, 41 , 43, 45, 47, 49 …… Valve 53 …… Position sensor, 55 …… Control unit

Front page continuation (72) Inventor Shigemi Kurogumi 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (56) References JP 59-215259 (JP, A) JP 59-1059 (JP) , A) JP 61-74764 (JP, A) JP 61-144257 (JP, A)

Claims (1)

[Claims] 1. An injection control device for controlling an injection speed of a molten metal injected from an injection port of a vertical die casting machine into a cavity having a split surface formed by upper and lower molds. An injection machine (11) for injecting into the machine, a control unit (55) for generating a signal for controlling the injection speed from the injection machine (11), and an injection operation upon receiving a signal from the control unit (55) From the start of the process until the molten metal is filled up to the split surfaces of the upper and lower molds in the cavity, the injection machine (11) operates so as to inject the molten metal at the first injection speed ( 37), and after the molten metal is filled up to the split surface, the injection machine (11) is slower than the first injection speed until the state immediately before the completion of the molten metal filling in the cavity is reached. Of the molten metal at the second injection speed of The medium-speed injection means (39) for operating so as to perform the discharging, and the injection machine (11) which has a third speed lower than the second injection speed after the state immediately before the completion of the molten metal filling is reached. An injection device for a vertical die-casting machine, comprising: a low-speed injection means (41) that operates so as to inject molten metal at an injection speed.