JP2009131868A - Booster for boosting accumulator in die-casting machine and controlling method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact injecting apparatus required in a die-casting industry at the recent years, for obtaining the high quality casting, a high speed injection and raised pressure can be realized. <P>SOLUTION: In the injecting apparatus in the die-casting machine, provided with; an accumulator for filling up, with which hydraulic oil is supplied into a head side of an injecting piston during filling-up process for injection-filling up the molten metal into a die cavity with the movement of the injecting piston; an accumulator for raising pressure, supplying the high pressure hydraulic oil storing up in the head side of the injecting piston during raising the pressure after completing the filling-up pressure; the booster for storing pressure of the high pressure hydraulic oil in the accumulator for raising pressure; and an accumulator raising pressure valve for operating the booster. The booster is composed of a booster body provided with one of head chamber and two rod chambers, and both-rod type booster piston, and has the structure, in which the high pressure hydraulic oil can alternately and continuously be injected from two rod chambers accompanied with the reciprocating motion. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an injection device of a die casting machine that injects and fills a molten metal such as aluminum into a mold cavity and casts a metal part, and provides a booster device and a method for controlling the booster accumulator. Is.

First, a general die casting apparatus and method using a horizontal die casting machine will be described with reference to FIG.
A die casting machine (casting apparatus) 200 includes a mold apparatus 201 and an injection cylinder 202. In the mold apparatus 201, a fixed mold is interposed between a pair of opposed fixed platens 220 and a movable platen 221. A mold 218 and a movable mold 219 are provided. The fixed mold 218 and the movable mold 219 are closed by a mold clamping device including the fixed platen 220 and the movable platen 221, thereby forming a cavity 222 therebetween, and aluminum (AL ) And the like are injected and filled to produce a cast product. In order to inject and fill molten aluminum, an injection cylinder 202 is provided, and a fixed platen 220 is provided with a plunger sleeve 217 for storing molten aluminum, and the plunger sleeve 217 includes a fixed platen 220 and a fixed metal. Through the mold 218 and in fluid communication with the cavity 222.

The injection cylinder 202 is a hydraulically driven reciprocating piston / cylinder for injecting molten aluminum. The injection cylinder 202 includes an injection cylinder body 216 and a piston 203. The piston 203 engages with the plunger sleeve 217. The piston 203 includes a cylinder piston head 215 at the left end in FIG. 4, and a plunger rod 212 is connected to a piston rod 214 integrated with the cylinder piston head 215 by an injection coupling 213, and a plunger tip is provided at the tip. 211 is attached. The plunger tip 211 is fitted in the plunger sleeve 217, reciprocates in the plunger sleeve 217, and pumps the molten aluminum in the plunger sleeve 217 to inject and fill the molten aluminum into the cavity 222. To do.
In the present embodiment, since the injection cylinder 202 is hydraulic, hydraulic oil is supplied to the head side of the cylinder body 216 to drive the cylinder piston head 215 and the piston rod 214, and is stored in the plunger sleeve 217. The molten aluminum (AL) is pushed by the plunger tip 211 and injected into the cavity (cavity) 222 formed from the fixed mold 218 and the movable mold 219 to be cast.

Here, in order to cast a non-defective product, it is important to appropriately set and control the injection speed and the injection pressure when the molten metal is injected into the cavity.
A general casting injection speed and injection pressure pattern will be described with reference to FIG. The injection pressure in FIG. 5 is the pressure in the head chamber of the injection cylinder.
In the hot water supply process before the injection filling is started, the molten metal is poured into the injection sleeve 217 by a hot water supply device (not shown), and the injection is started. (See Figure 4)

From this state, as shown in FIG. 5, first, the plunger tip 211 is advanced at a low injection speed so that the molten metal does not engulf air inside the injection sleeve 217. When the plunger tip 211 moves forward, the molten metal reaches the upper wall of the injection sleeve 217 and the molten metal surface rises to the vicinity of the entrance of the cavity 222, the high-speed injection is switched. (By detecting the position of the injection stroke sensor)
In the high-speed injection process, the plunger tip 211 and the like are accelerated at a stroke, and the molten metal is injected and filled into the cavity 222 at a high speed. This is because the molten metal instantly solidifies when it comes into contact with the surface of the cavity 222 at a low temperature, and filling before solidifying as fast as possible is desirable for good casting.
Then, immediately before the molten metal is completely filled in the cavity 222, the injection speed is reduced in order to prevent generation of burrs due to surge pressure.
When the molten metal is completely filled in the cavity 222, the injection pressure (head pressure of the injection cylinder) rises. Therefore, when the measured value of the pressure sensor becomes equal to or higher than the set switching pressure, the next pressure increasing process is performed.
In the pressurization process, if the pressure is raised too early, burrs are generated, and if it is late, shrinkage cavities are generated. Therefore, the pressure is increased at an appropriate pressure increase rate. Further, it is necessary to increase the pressure to a high pressure in order to crush cavities and shrinkage cavities caused by air entrainment. Then, the plunger tip 211 is moved forward by the amount that the molten metal is solidified, cooled, and contracted for a certain period of time at a high pressure increase.

  In order to realize such a high-speed injection and a high pressure increase pressure, an injection device including two accumulators for injection and pressure increase has been devised. Furthermore, in order to increase the pressurization pressure for the purpose of improving the quality of the cast product, an apparatus and a method have been devised for boosting the accumulator for pressurization to a high pressure.

For example, in Patent Document 1, hydraulic oil discharged from a hydraulic pump is introduced into a large-diameter side oil chamber of a one-rod booster (pressure increase) booster, and the hydraulic oil is boosted to a high pressure from a small-diameter side oil chamber. Is disclosed, and a pressure accumulating (pressure increasing) piston accumulator is discharged.
Further, Patent Document 2 discloses a method in which high pressure hydraulic oil is stored in a pressure increasing (pressure increasing) accumulator using an area difference between a head side and a rod side of an injection cylinder.

Japanese Patent Laid-Open No. 08-71725 Japanese Patent No. 3662001

However, in the injection device described in Patent Document 1, since the booster for boosting the pressure (pressure increase) piston accumulator is a single rod type, the piston needs to return while sucking the hydraulic oil. The operation of discharging the hydraulic oil was temporarily interrupted, and it took time for animal pressure. For this reason, a large booster is required and the apparatus is large.
In addition, in the injection device described in the prior art document 2, in order to generate high-pressure oil that has been pressurized in the rod side chamber of the injection cylinder, it is necessary to design the rod side chamber and the packing to have a structure that can withstand high pressure.

  In the present invention, it is intended to provide a booster device that solves the disadvantages of the conventional injection device and hydraulic circuit and is compact and capable of animal pressure in a short time.

  In order to solve the above-described problems, in the first aspect of the present invention, a filling accumulator that supplies hydraulic oil to the head side of the injection piston during the filling step of injecting and filling the molten metal into the mold cavity by the operation of the injection piston is provided. The boosting accumulator that supplies the high-pressure hydraulic fluid accumulated in the head side of the injection piston during the boosting step after the filling step is completed, the booster for stocking the high-pressure hydraulic fluid to the boosting accumulator, and the booster are operated. In a die casting machine injection apparatus equipped with a boosting accumulator animal pressure valve for booster, the booster is composed of a booster body composed of one head chamber and two rod chambers, and a double rod type booster piston, and the booster piston reciprocates. A structure that allows high pressure hydraulic oil to be discharged alternately and continuously from the two rod chambers as a result of movement.

  According to a second aspect of the present invention, there is provided a method of controlling a boosting accumulator using the injection device according to the first aspect of the invention, wherein the booster piston is reciprocated by repeating excitation and demagnetization of the boosting accumulator storage pressure valve. The pressure accumulator is pressurized by exercising and continuously discharging high pressure hydraulic oil, and the pressure of the pressure accumulator is measured by a pressure sensor. When the measured pressure reaches the set pressure value, the stock pressure process is terminated. The control method was used.

In the present invention, the following excellent effects are exhibited.
(1) Since the high pressure hydraulic oil can be continuously discharged during the reciprocating motion of the booster piston, it is possible to reduce the pressure of the pressure increasing accumulator in a short time.
(2) The booster can be downsized and the injection hydraulic device can be made compact.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments relating to an injection device, a hydraulic device, and a control method for a die casting machine according to the present invention will be described below in detail with reference to the drawings. 1 to 3 all relate to an embodiment of the present invention, FIG. 1 is a hydraulic circuit diagram of an injection device, FIGS. 2 and 3 show a hydraulic circuit for accumulating a pressure accumulator, and an operation during the accumulating pressure is shown. It is a figure showing states, such as a flow of oil.

  Also in the present embodiment, the mold device, injection plunger, injection cylinder, etc. are the same as those in the general die casting machine shown in FIG. 4, but are characterized by the hydraulic circuit, hydraulic device, and control method of the injection device. .

FIG. 1 shows a hydraulic circuit of an injection device, and an injection and boosting circuit and a circuit for moving the injection piston 2 back and forth are connected to the head side of the injection cylinder 1.
First, in the injection circuit, the injection forward on-off valve 8, the injection accumulator 5, and the gas bottle 7 are connected in series from the head chamber of the injection cylinder 1 through a check valve. An injection animal pressure valve 15 for checking the injection accumulator 5, a check valve, and a pump A are branched and connected in the circuit.
A boosting time control valve 14, a boosting on-off valve 9, and a boosting accumulator 6 are connected to the boosting circuit, branching on the way, to the check valve, the booster 3, the boosting animal pressure valve 16 and the pump B. The circuit is connected.
Further, the injection piston forward / reverse circuit is connected to the pump B via the injection forward / reverse switching valve 11 and the check valve.

  On the other hand, the rod side of the injection cylinder 1 is connected to the tank via the injection speed on-off valve 10 and the injection speed control valve 13, and is branched halfway through the injection forward / reverse switching valve 11 to check the check valve. And connected to pump B.

The injection speed control valve 13 and the pressure increase time control valve 14 have a structure in which the opening degree of the valve can be adjusted by controlling the rotation angle of the motor.
Also, an injection accumulator pressure sensor 17 for measuring the pressure of the injection accumulator 5, a boost accumulator pressure sensor 18 for measuring the pressure of the boost accumulator, and an injection for measuring the pressure in the head chamber of the injection cylinder. A pressure sensor 19 is connected to each circuit.

Next, a circuit and a method for storing pressure of the boosting accumulator 6 will be described in detail with reference to FIGS. In FIG. 2, the boosting animal pressure valve 16 is being excited, and in FIG. 3 is being demagnetized. Moreover, an arrow shows the direction etc. in which hydraulic fluid flows.
As shown in FIG. 2, a booster piston 4 is incorporated in a booster body 3a in the booster 3, and the booster piston 4 is composed of a piston head 4a and a left piston rod 4b and a right piston rod 4c fixed to both end faces thereof. Is done. The booster body 3a has a head chamber composed of a left head chamber 3b and a right head chamber 3c partitioned by a booster piston 4a, a left rod chamber 3d in which the left piston rod 4b is inserted, and a right piston rod 4c. It is composed of a right rod chamber 3e.
The circuit connections of the pump B, the tank, the boosting animal pressure valve 16, the booster 3, four check valves, the boosting accumulator 6, and the boosting accumulator pressure sensor 18 are as shown in FIG.

  In the state of FIG. 2, the booster pressure control valve 16 is energized, and the P port and the B port and the T port and the A port are connected, and the hydraulic oil discharged from the pump B passes through the P port and the B port. One branch flows into the right head chamber 3c, and the other flows into the right rod chamber 3e via the check valve. The booster piston 4 is pushed to the left and moves by the pressure of the hydraulic oil flowing into each chamber. At this time, the hydraulic fluid in the left head chamber 3b falls into the tank via the boosting pressure control valve 16, and the hydraulic fluid in the left rod chamber 3d is pressurized and flows into the boosting accumulator 6 under the action of each check valve. .

  Next, in the state of FIG. 3, the boosting pressure control valve 16 is demagnetized, the P port and the A port, the T port and the B port are connected, and the hydraulic oil discharged from the pump B passes through the P port and the A port. Branching on the way, one flows into the left head chamber 3b and the other flows into the left rod chamber 3d via the check valve. The booster piston 4 is pushed to the right and moved by the pressure of the hydraulic oil flowing into each chamber. At this time, the hydraulic oil in the right head chamber 3c falls into the tank via the boosting pressure control valve 16, and the hydraulic oil in the right rod chamber 3e is pressurized and flows into the boosting accumulator 6 under the action of each check valve. .

  In this way, in the boosting pressure of the boosting accumulator 6, the boosting booster pressure valve 16 is repeatedly excited and demagnetized to reciprocate the booster piston 4 and continuously discharge high pressure hydraulic oil. Increase pressure. The switching time between excitation and demagnetization is determined by the relationship between the amount of hydraulic oil discharged from the pump B and the internal volume of the booster body 3a, and is performed at the timing when the booster piston 4 reaches the stroke end.

Here, the diameter of the piston head 4a is D (mm), the diameter of each piston rod 4b, 4c is d (mm), the pressure of the hydraulic oil discharged from the pump B is P _P (MPa), and the booster 3 discharges If the pressure to be applied is P _A (MPa), the balance of the forces acting on the booster piston 4
^{_{P P · (Π · D 2}} /4) = P A · (Π · d 2/4)
And
P _A = (D ² / d ² ) · P _P
It becomes.
Therefore, the pressure of the hydraulic oil discharged from the pump B by the booster 3 becomes (D ² / d ² ) times, and the pressure is accumulated in the accumulator 6 for pressure increase.

  Next, a description will be given of a method for controlling the operation of the filling process, the pressure increasing process, and the animal pressure process according to the present invention using the hydraulic circuit and hydraulic device for injection configured as described above.

First, before entering the filling step, the accumulator for injection 5 and the accumulator for boosting 6 are each in a state where the animal pressure has been completed.
Also, the injection forward on-off valve 8, the boosting on-off valve 9, the injection speed on-off valve 10, and the injection forward / backward switching valve 11 are closed (demagnetized). The injection speed control valve 13 is also closed, but the pressurization time control valve 14 is maintained at an opening at which a desired pressure increase speed is obtained.

In the filling process, the injection advance on / off valve 8 and the injection speed on / off valve 10 are opened, and the injection piston 2 of the injection cylinder 1 starts to advance. At this time, by controlling the opening degree of the injection speed control valve 13, the amount of oil returning from the rod side oil chamber to the tank is adjusted, and control is performed so that the set low speed injection speed is obtained.
When an unillustrated injection stroke sensor detects that the high-speed injection region has been reached, the opening degree of the injection speed control valve 13 is increased, and the opening amount is controlled so as to obtain a desired high-speed injection speed.

In order to prevent surge pressure from being generated and flashing out at the moment when the molten metal fills the cavity, the speed is lowered at the end of the high-speed injection region, and the process proceeds smoothly to the pressure increasing process.
The timing for proceeding to the boosting process is performed at the moment when the set switching pressure is reached while monitoring the measured value of the injection pressure by the injection pressure sensor 19, and the injection forward on-off valve 8 is closed and the boost on-off valve 9 is opened. It is.

At this time, the opening amount of the boost time control valve 14 is adjusted so as to obtain a desired boost speed. Then, the pressure is held at a pressure slightly lower than the stock pressure value of the boosting accumulator 6.
When the pressure holding time for coagulation contraction elapses, the boosting on-off valve 9 and the injection speed on-off valve 10 are closed, and the boosting process ends.

  Thereafter, the solenoid a of the injection forward / reverse switching valve 11 is excited together with the mold opening, the injection piston 2 is advanced, and the product is ejected. Further, the b solenoid of the injection forward / reverse switching valve 11 is excited to return the injection piston 2 to the injection start position.

In order to stock pressure the injection accumulator 5, the injection stock pressure valve 15 is opened with the injection forward on-off valve 8 closed, the hydraulic oil is discharged from the pump A, and the pressure is detected by the injection accumulator pressure sensor 17. Feed hydraulic oil until the desired injection pressure setting is reached.
In order to pressurize the pressure accumulator 6, hydraulic oil is discharged from the pump B with the pressure on-off valve 9 closed (demagnetized). Then, excitation and demagnetization of the pressurizing stock pressure valve 16 are repeated, and high pressure hydraulic oil is sent to the preset boost stock pressure setting value while measuring the pressure with the boost accumulator pressure sensor 18. Then, the boosting pressure control valve 16 is demagnetized to finish the pressure control process.
This completes preparations for the next hot water supply step and filling step.

In the hydraulic circuit of the embodiment described above or shown in the attached drawings, for the sake of easy understanding, only the minimum components are basically described, but the function, control, and arrangement of the device are described. Components such as a valve, a filter, and a sensor that are necessary depending on the above may be added.
Further, the above embodiment is an example of the present invention, and the present invention is not limited by the embodiment, and is defined only by matters described in the claims. Forms are also possible.

1 is a hydraulic circuit diagram of an injection apparatus according to an embodiment of the present invention. FIG. 6 is a diagram for explaining the flow of hydraulic oil when the boosting accumulator is excited with the booster and the boosting pressure valve is excited by the booster according to the embodiment of the present invention. It is a figure explaining the flow of the hydraulic fluid when it concerns on the Example of this invention and the accumulator for pressure | voltage rise is stocking pressure with the booster, and the stock pressure valve for pressure | voltage rise is demagnetizing. It is a figure which shows the injection device of a die-casting machine, and the structure around a metal mold | die. It is a graph showing the injection speed and injection pressure at the time of injection filling of a die casting machine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injection cylinder 2 Injection piston 3 Booster 3a Booster main body 3b Left head chamber 3c Right head chamber 3d Left rod chamber 3e Right rod chamber 4 Booster piston 4a Piston head 4b Left piston rod 4c Right piston rod 5 Injection cumulator 6 Booster cumulator 7 Gas bottle 8 Injection forward opening / closing valve 9 Boosting opening / closing valve 10 Injection speed opening / closing valve 11 Injection forward / reverse switching valve 13 Injection speed control valve 14 Boosting time control valve 15 Injection boosting pressure valve 16 Boosting boosting pressure valve 17 Injection accumulator Pressure sensor 18 Boosting accumulator pressure sensor 19 Injection pressure sensor 200 Main part of horizontal die casting machine 201 Mold device 202 Injection cylinder 203 Piston 211 Plunger tip 212 Plunger rod 213 Coupling 214 Piston rod 215 Cylinder piston head 216 Injection cylinder body 217 Injection sleeve 218 Fixed mold 219 Movable mold 220 Fixed platen 221 Movable platen 222 Cavity

Claims (2)

An accumulator for filling that supplies hydraulic oil to the head side of the injection piston during the filling process of injecting and filling molten metal into the mold cavity by the operation of the injection piston, and a head of the injection piston during the pressurizing process after the filling process is completed A boosting accumulator for supplying high-pressure hydraulic oil accumulated on the side, a booster for boosting the high-pressure hydraulic fluid to the boosting accumulator, and a boosting accumulator pressure-control valve for operating the booster In an injection device of a die casting machine,
The booster includes a booster body composed of one head chamber and two rod chambers, and a double rod type booster piston, and alternately and continuously from the two rod chambers as the booster piston reciprocates. It is possible to discharge high-pressure hydraulic oil,
Die casting machine injection device.
A method for controlling the pressure of an accumulator for boosting using the die casting machine injection device according to claim 1,
By repeating excitation and demagnetization of the boosting accumulator animal pressure valve, the booster piston is reciprocated to continuously discharge high-pressure hydraulic fluid, and the booster accumulator is accumulated and the pressure of the booster accumulator is reduced. Measured with a pressure sensor, the animal pressure process is terminated when the measured pressure reaches the set animal pressure value,
Die casting machine control method.

Images