JP3589399B2 - High speed injection hydraulic circuit of light metal injection molding machine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light metal injection molding machine that melts and injects a light alloy chip, and in particular, rotates a screw disposed in a cylinder to which a heater is attached to rotate a light alloy chip stored in a hopper into a cylinder tip. After the metering operation of feeding a fixed amount in the direction of the nozzle of the section, the pressurized hydraulic oil is fed into the piston chamber, and the injection piston arranged in the piston chamber and connected to the screw is driven to perform the injection operation. Accordingly, the present invention relates to a light metal injection molding machine capable of injecting a molten light alloy in which the light alloy tip is melted by a heater from the nozzle.
[0002]
[Prior art]
In a light metal injection molding machine 101 shown in FIG. 2, a hopper 12 is attached to a cylinder 11, and a light alloy chip 13 is housed in the hopper 12. When the metering motor 14 rotates, the screw 15 disposed in the cylinder 11 rotates, and sends the light alloy chip 13 supplied from the hopper 12 toward the nozzle 16 at the tip of the cylinder 11. The light alloy chip 13 weighed in accordance with the rotation speed of the screw 15 (metering operation) and sent out toward the nozzle 16 is moved by the heater 17 provided on the outer wall of the cylinder 11 when moving inside the cylinder 11. Heats to a molten light alloy. On the other hand, the accumulator 21 stores pressurized oil (pressurized hydraulic oil) which is pressurized by the hydraulic pressure source 22 and sent through the check valve 23. The flow rate of the oil passing through the directional control flow control valve 24 is adjusted, the flow direction to the pipes 27 and 28 is set as indicated by the arrow on the left side of the directional control flow control valve 24, and the ACC switch valve 25 is set to the ACC switch valve 25. The oil stored in the accumulator 21 is sent into the piston chamber 18a via the pipes 26 and 27 when the oil is set and opened as indicated by the arrow on the left side of FIG.
[0003]
When the pressurized oil is sent into the piston chamber 18a, the injection piston 18 is pressed in the direction of the nozzle 16, and the oil contained in the piston chamber 18b is discharged to the oil receiver 24a via the pipe 28 and used. It is stored again in the accumulator 21 by the hydraulic pressure source 22 to supplement the oil of the minute. When the injection piston 18 is pressed by the pressure oil entering the piston chamber 18a, the molten light alloy at the tip of the cylinder 11 is injected from the nozzle 16 into a mold (not shown) (injection operation). Next, the measuring motor 14 rotates, and the screw 15 is rotated to measure the light alloy chip 13. At this time, the flow direction of the directional control flow control valve 24 is set as indicated by an arrow on the right side of the directional control flow control valve 24, and the ACC switch valve 25 is set and closed like the right side of the ACC switch valve 25. When the hydraulic pressure source switching valve 29 is set and opened as shown by the arrow on the lower side, the pressure oil from the hydraulic pressure source 22 is sent to the piston chamber 18b through the pipes 34 and 28, and the injection piston 18 is moved to the metering motor 14 Retract in the direction of. The oil contained in the piston chamber 18a is discharged to the oil receiver 24a via the pipe 27.
[0004]
[Problems to be solved by the invention]
In the above-described conventional injection molding machine for light metal, the molten light alloy is injected from the nozzle 16 into the mold. In this case, a cold plug 19 is generated at the tip of the nozzle 16. If it is not removed, the molten light alloy cannot be injected into the mold. However, a high pressure is required in the early stage of the injection operation for ejecting the cold plug 19. The speed of the screw 15 in the injection operation becomes appropriate only when pressure oil having a sufficient flow rate and pressure is supplied to the piston chamber 18a. Even if oil is supplied, the cold plug 19 is not ejected until the pressure in the piston chamber 18a rises above a predetermined value, and it takes time for the injection speed to reach a desired speed. The rising performance of the injection speed at the initial stage of the injection operation is very important for molding. The reason is that the molten light alloy filled in the mold immediately starts to solidify.
[0005]
Therefore, it is desirable to execute the injection operation at the highest possible speed. Normally, in the case of light alloy injection molding, the injection time is about 0.1 second or less, and during this time, for example, the injection speed is affected by punching out the cold plug 19, and it takes 0 to reach the maximum injection speed. The ratio of the filling amount of the molten light alloy is 1: 5 between the case where 0.05 seconds is required and the case where 0.01 seconds is required, and both are molded products having different appearances. Therefore, in order to solve this problem, the force for ejecting the cold plug 19, that is, the pressure of the pressure oil sent from the accumulator 21 to the piston chamber 18a, is increased in order to improve the rising response of the injection speed at the beginning of the injection operation. It may be better. Indeed, if the pressure of the pressurized oil of the accumulator 21 is increased, the rising response of the injection speed at the beginning of the injection operation is improved. However, in the case of filling the molten light alloy in the mold, at the moment when the molten light alloy becomes full in the mold, it is necessary to fill the molten light alloy with the pressure as low as possible. Otherwise, an excessive compressive residual stress is generated in the molded product, and molding defects such as "burrs" are generated. Therefore, the pressure of the accumulator 21 cannot be increased unnecessarily.
[0006]
The present invention has been made in order to solve the above-described problem, and it is possible to quickly punch out a cold plug with high pressure only for a certain period at the start of an injection operation, and to form a light metal that can be processed at normal pressure thereafter. An object of the present invention is to provide an injection molding machine.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problem, the present invention provides a light alloy chip housed in a hopper (12) by rotating a screw (15) arranged in a cylinder (11) to which a heater (17) is attached. After the metering operation of feeding a fixed amount of (13) in the direction of the nozzle (16) at the tip of the cylinder, pressurized hydraulic oil is fed into the piston chamber (18a), and the screw is disposed in the piston chamber (18a). By driving the injection piston (18) connected to (15) to perform the injection operation, the light alloy chip (13) melts the molten light alloy melted by the heater (17) from the nozzle (16). In an injection molding machine for light metals that can be injected, first and second accumulators (21, 31) for storing hydraulic oil and hydraulic oil at a first pressure (A). A first pressurizing means for directing the pressure in the first accumulator (21) (22, 23), the pressurized hydraulic fluid to a first pressure (A) higher than the second pressure (B) And second pressurizing means (32, 33) leading to the second accumulator (31), and at the start of the injection operation, only the pressure oil of the second accumulator (31) is fed into the piston chamber (18a). When the pressure of the pressure oil of the second accumulator (31) decreases and becomes substantially equal to the pressure of the pressure oil of the first accumulator (21), the hydraulic oil of the first and second accumulators (21, 31) And a hydraulic circuit (30, 25, 26, 24, 27) for sending the hydraulic fluid into the piston chamber (18a) in parallel.
[0008]
According to such a configuration, at the start of the injection operation, if the ACC switching valve (25) is set as indicated by the arrow on the left, the pressure oil from the second accumulator (31) causes the ACC switching valve (25) to move. The cold plug generated in the nozzle can be quickly ejected by driving the injection piston with high pressure hydraulic fluid after being sent to the piston chamber (18a). As described above, the rising response of the injection speed of the molten light alloy does not decrease. Also, in the hydraulic circuit, while the pressure of the second accumulator is higher than the pressure of the first accumulator, the check valve 30 does not open, so that the pressure oil of the first accumulator does not flow. After that, when the pressure of the pressure oil of the second accumulator decreases and becomes substantially equal to the pressure of the pressure oil of the first accumulator, the check valve 30 opens and the hydraulic oil of the first and second accumulators opens. Can be stably fed into the piston chamber in parallel. That is, the injection can be performed at a high pressure only when the plug is ejected at the start of injection, and the injection operation can be advanced at a low pressure after the plug is ejected.
[0009]
In the embodiment of the present invention, the light alloy chip (13) housed in the hopper (12) by rotating the screw (15) arranged in the cylinder (11) to which the heater (17) is attached. After the metering operation of feeding a predetermined amount of fluid in the direction of the nozzle (16) at the tip of the cylinder, pressurized hydraulic oil is fed into the piston chamber (18a), and the screw (15) is disposed in the piston chamber (18a). The light alloy chip (13) is caused to inject molten light alloy melted by the heater (17) from the nozzle (16) by driving the injection piston (18) connected to the nozzle to perform an injection operation. The first and second accumulators (21, 31) for storing hydraulic oil and the hydraulic oil are pressurized to a first pressure (A). The hydraulic source (22) and the check valve (23) stored in the accumulator (21), and the hydraulic oil is pressurized to a second pressure (B) higher than the first pressure (A) to produce a second pressure (B). At the start of the injection operation, only the hydraulic oil of the second accumulator (31) is fed into the piston chamber (18a) and the hydraulic pressure source (32) and the check valve (33) stored in the accumulator (31). When the pressure of the pressure oil of the second accumulator (31) decreases and becomes substantially equal to the pressure of the pressure oil of the first accumulator (21), the hydraulic oil of the first and second accumulators (21, 31) And a hydraulic circuit (25, 26, 24, 27) for sending a check valve (30) to the piston chamber (18a) in parallel.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram showing an embodiment of a light metal injection molding machine according to the present invention. The injection molding machine for light metal of FIG. 1 is substantially the same as the injection molding machine for light metal of FIG. 2 except that an accumulator 31, check valves 30, 33, and a hydraulic source 32 are added. In the light metal injection molding machine 1 of FIG. 1, a hopper 12 is attached to a cylinder 11, and a light alloy chip 13 is stored in the hopper 12. When the metering motor 14 rotates, the screw 15 disposed in the cylinder 11 rotates, and sends the light alloy chip 13 supplied from the hopper 12 toward the nozzle 16 at the tip of the cylinder 11. As described above, when the light alloy chip 13 is sent out from the hopper 12 and moves in the cylinder 11 toward the nozzle 16, the light alloy chip 13 is weighed in accordance with the rotation speed (or rotation angle) of the screw 15 (weighing operation). Further, when moving inside the cylinder 11, it is heated by a heater 17 provided on the outer wall of the cylinder 11 to become a molten light alloy.
[0011]
On the other hand, the accumulator 21 is pressurized to a pressure similar to that in the conventional example shown in FIG. 2 by the hydraulic pressure source 22 and sent through the check valve 23 (pressurized hydraulic oil). Is stored. The accumulator 31 stores therein pressurized oil that is pressurized by the hydraulic pressure source 32 to a higher pressure than the accumulator 21 and sent through the check valve 33. The accumulators 21 and 31 are connected via a check valve 30, and the pressure oil of the accumulator 31 does not always flow toward the accumulator 21, and the pressure of the pressure oil of the accumulator 31 is reduced by the pressure oil of the accumulator 21. Is higher than the pressure, the pressure oil of the accumulator 21 does not flow into the accumulator 31 side. Therefore, the flow rate of the directional control flow control valve 24 is adjusted, the flow direction to the pipes 27 and 28 is set as indicated by the arrow on the left side of the directional control flow control valve 24, and the ACC switch valve 25 is set to the left side of the ACC switch valve 25. When it is set and opened as indicated by the arrow in the section, the high-pressure oil stored in the accumulator 31 is sent into the piston chamber 18a via the pipes 26 and 27.
[0012]
When high-pressure oil is sent into the piston chamber 18a, the injection piston 18 is pressed at high speed in the direction of the nozzle 16. The oil that has entered the piston chamber 18b is discharged to the oil receiver 24a via the pipe 28, and is stored again in the accumulators 21 and 31 by the hydraulic pressure sources 22 and 32. When the injection piston 18 is pressed by the high-pressure oil from the accumulator 31 entering the piston chamber 18a, the cold plug 19 at the tip of the cylinder 11 is rapidly ejected. It is injected into a mold (not shown) (injection operation). When the injection starts, the pressure oil amount of the accumulator 31 decreases, and the pressure gradually decreases, and becomes almost equal to the pressure of the pressure oil in the accumulator 21. Then, the pressure oil of the accumulator 21 also passes through the check valve 30, and is sent to the piston chamber 18a through the ACC switching valve 25, the pipe 26, the direction switching flow rate adjustment valve 24, and the pipe 27 together with the pressure oil of the accumulator 31. The injection piston 18 is stably pressed with the normal pressure similar to the conventional one. When the molten light alloy is completely filled into the cavity of the mold, the pressure is sufficiently reduced so that "burrs" and the like are not generated.
[0013]
As described above, since the cold plug 19 is ejected at a high speed by the high-pressure oil, the injection speed reaches the maximum speed very quickly. After the cold plug 19 is ejected, the injection piston 18 becomes the accumulator. The injection operation can be stably continued because the oil is pressed by the normal pressure oil supplied in parallel from 21 and 31, and the pressure is sufficiently reduced at the time of completion of the filling of the molten light alloy. Next, when the filling of the molten light alloy is completed, the operation shifts to the measuring operation. The flow direction of the directional control flow control valve 24 is set as indicated by the arrow on the right side of the directional control flow control valve 24, and the ACC switch valve 25 is set and closed as indicated by the right side of the ACC switch valve 25, and the hydraulic pressure source is switched. When the valve 29 is set and opened as shown by the arrow on the lower side of the hydraulic pressure source switching valve 29, the pressure oil from the hydraulic pressure source 32 is sent to the piston chamber 18b through the pipe 28, and the injection piston 18 is moved to the metering motor. Retract in the direction of 14. The oil contained in the piston chamber 18a is discharged to the oil receiver 24a via the pipe 27.
[0014]
【The invention's effect】
As described in detail above, the injection molding machine for light metal of the present invention comprises a metering operation of rotating a screw to feed a fixed amount of light alloy chips from a hopper in the direction of a nozzle. To drive the injection piston to drive the injection piston to cause the light alloy chip to be injected from the nozzle into the mold by the molten light alloy melted by the heater 17. 1, a second accumulator, a first pressure oil storing means for pressurizing the hydraulic oil to a first pressure (A) and storing it in the first accumulator, and a first pressure (A) for the hydraulic oil. A second pressure oil storing unit that pressurizes to a higher second pressure (B) and stores it in the second accumulator; and at the start of the injection operation, only the pressure oil of the second accumulator is supplied to the piston chamber. Send in, second When the pressure of the pressurized oil of the accumulator decreases and becomes substantially equal to the pressure of the pressurized oil of the first accumulator, a hydraulic circuit that sends the hydraulic oil of the first and second accumulators to the piston chamber in parallel. By having this, at the start of the injection operation, the hydraulic circuit sends the hydraulic oil set at a high pressure from the second accumulator to the piston chamber and drives the injection piston with the high-pressure hydraulic oil, thereby generating the oil at the nozzle. Thus, the cold plug can be shot in a short period of time, and there is no delay in shooting the cold plug, thereby reducing the rising response of the injection speed of the molten light alloy as in the related art. After that, since the hydraulic oil is fed into the piston chamber from the first and second accumulators in parallel, the molten light alloy can be injected stably, and the molded shape can be stabilized. In addition, when the filling of the molten light alloy into the cavity of the mold is completed, the injection pressure can be sufficiently reduced, so that "burrs" and the like do not occur.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of a light metal injection molding machine according to the present invention.
FIG. 2 is a view showing a conventional example of a light metal injection molding machine.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Injection molding machine for light metals 11 Cylinder 12 Hopper 13 Light alloy chip 14 Metering motor 15 Screw 16 Nozzle 17 Heater 18 Injection piston 18a, 18b Piston chamber 19 Cold plug 21, 31 Accumulator 22, 32 Hydraulic source 23, 30, 33 Non-return Valve 24 Direction switching flow control valve 24a Oil receiver 25 ACC switching valve 26, 27, 28, 34 Pipe 29 Hydraulic source switching valve A First pressure B Second pressure

Claims (1)

By rotating a screw (15) arranged in a cylinder (11) to which a heater (17) is attached, a light alloy chip (13) housed in a hopper (12) is moved to a nozzle (16) at the tip of the cylinder. After the metering operation of feeding a predetermined amount in the direction, the pressurized hydraulic oil is fed into the piston chamber (18a), and the injection piston (18) arranged in the piston chamber (18a) and connected to the screw (15) is moved. A light metal injection molding machine capable of injecting a molten light alloy melted by a heater (17) from the nozzle (16) by driving and performing an injection operation,
First and second accumulators (21, 31) for storing hydraulic oil,
First pressurizing means (22, 23) which pressurizes the hydraulic oil to a first pressure (A) and guides the hydraulic oil to a first accumulator (21);
Second pressurizing means (32, 33) which pressurizes the hydraulic oil to a second pressure (B) higher than the first pressure (A ) and guides it to a second accumulator (31);
At the start of the injection operation, only the pressure oil of the second accumulator (31) is sent into the piston chamber (18a), the pressure of the pressure oil of the second accumulator (31) decreases, and the pressure of the first accumulator (21) decreases. ) Is substantially equal to the pressure oil pressure, the hydraulic circuits (30, 25, 26,) for sending the hydraulic oil of the first and second accumulators (21, 31) to the piston chamber (18a) in parallel. 24, 27). An injection molding machine for light metals.

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