JPH08155622A - Local pressure device - Google Patents

Abstract

PURPOSE: To perform a squeeze suitable for a molded good by measuring a pressure to be applied to a pressure pin for a local pressure with a pressure sensor, measuring the position of the pressure pin by a position detecting sensor, and controlling the operation of the hydraulic cylinder of the pressure pin. CONSTITUTION: After the completion of the injection of molten metal and the lapse of a specified time, squeezing is started by a pressure pin 13. A pressure piston 13 is pushed into molded goods through rod 14b and piezoelectric element 20 by operating a hydraulic cylinder 14. A squeeze pressure is measured by the piezoelectric element 20. The moving distance (squeeze stroke) of the rod 14b is measured by a sensor 25. The hydraulic cylinder 14 is controlled so that the squeeze pressure becomes a set pressure. The hydraulic cylinder is stopped in a position where a stroke value is smaller than the full stroke value. After holding for a specific time, the hydraulic cylinder 14 is returned. Consequently, porosity can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a local pressure device for controlling the stroke value during pressure casting to reduce or eliminate porosity.

[0002]

2. Description of the Related Art Conventionally, when a casting is manufactured by a local pressure method, when the molten metal injected into the cavity of the mold is cooled and solidified, the volume of the molten metal shrinks, which causes internal shrinkage. Further, since the molten metal is injected at a high speed, air is entrained in the molten metal to generate porosity inside the casting. In order to eliminate defects such as internal shrinkage and the formation of porosity, a method has been adopted in which the pressure pin is projected into the cavity immediately before the molten metal in the cavity is solidified. The operation of the pressurizing pin of this type used the hydraulic circuit for operating the core port of the die casting machine without adding a circuit for improving or improving the function.

According to the official gazette of Japanese Patent Publication No. 59-156560, the pressurizing timing of the pressurizing pin is constantly controlled by a timer. According to the official gazette of Japanese Patent Laid-Open No. 58-9758, the mold temperature is It was detected by a sensor, and the operation of the pressure pin was controlled by the detected temperature. Japanese Patent Laid-Open No. Hei 4
-118167 can directly measure the position of the pressure pin, and these sensors had to be attached to each mold.

[0004]

According to the prior art, there were the following technical problems.

In the technique disclosed in Japanese Examined Patent Publication No. 59-156560, the quality of the product may vary because the mold temperature at the start of casting differs from the solidification temperature when the mold temperature is stable. In the technique of Japanese Patent Laid-Open No. 58-9758, there is a problem that it is difficult to grasp unless the relationship between the mold temperature or the melt temperature and the pressurizing timing is clear. It was difficult to keep the relationship constant.

In Japanese Patent Laid-Open No. 4-118167, the position of the pressure pin can be directly measured, but there is the trouble that these sensors must be attached to each mold.

The present invention has been made in view of the above technical problems, and an object of the present invention is to immediately press a pressure pin by a hydraulic cylinder on a molded product under pressure casting using a die immediately before solidification. In order to reduce or eliminate the porosity by pushing, the hydraulic circuit that activates the pressure pin is independently controlled, and the pressure of the pressure pin is directly measured to control the position of the pressure pin. An object of the present invention is to provide a local pressurizing device capable of producing die cast products.

[0008]

In order to solve the above problems, the local pressurizing device of the present invention is provided with the following means.

The local pressurizing device of the present invention is configured such that a pressurizing pin is pressed by a hydraulic cylinder just before solidification to reduce or eliminate a porosity in a molded product under pressure casting using a mold. In the pressure casting apparatus, a hydraulic pressure supply source, a pressure adjusting unit that adjusts the pressure of the hydraulic oil from the hydraulic pressure supply source, a pressure compensating unit that compensates the pressure of the hydraulic oil whose pressure is adjusted by the pressure adjusting unit, A flow rate adjusting part that adjusts the flow rate of the hydraulic oil whose pressure is adjusted by the pressure compensating part, a direction switching valve that switches the direction of the hydraulic oil whose flow rate is adjusted by the same flow rate adjusting part, and between the pressurizing pin and the end of the cylinder rod. A hydraulic cylinder that holds a pressure sensor between them to move the pressure pin forward and backward, a position detection sensor that is provided on the cylinder rod and that directly measures the position of the pressure pin, and the starting and operating time of the hydraulic cylinder. And a control device for controlling Therefore, it was constructed.

In the pressure pin device of the present invention, a linear scale is provided on one side of the piston of the hydraulic cylinder to measure the tip position of the rod, and a screw is formed on the other side of the rod tip. , The nut is screwed, and the flange part additional pressure pin is movably loosely fitted to the holding nut, and the flange part locks the pressure pin from coming off from the holding nut.
A piezoelectric element is sandwiched between the flange and the rod so that the thrust force of the pressure pin can be detected.

The pressure pin is provided with a ring-shaped stopper on the flange portion of the pressure pin, and the piezoelectric element is put in this stopper, and the end face of the stopper is brought into contact with the rod to prevent the piezoelectric element from being destroyed. .

Positioning control of the pressurizing pin may be performed by fixing a rod and a linear scale to the left and right of the piston of the hydraulic cylinder, measuring the position with a position sensor, and controlling with a controller.

[0013]

The operation of the apparatus of the present invention constructed as above will be described below.

A pressure pin is connected to the rod of the hydraulic cylinder, and a piezoelectric element is sandwiched between the rod and the pressure pin.
The pressure is directly measured through the pressure sensor, the position of the pressure pin is directly measured through the position sensor, and the position and operating time of the hydraulic cylinder are controlled by the controller based on the pressure obtained by the pressure sensor. Control.

In the pressure pin, the piezoelectric element is inserted into the stopper, the end face of the stopper is brought into contact with the rod, and the rod is compressed beyond the operating range of the piezoelectric element to prevent the piezoelectric element from breaking. Further, the local pressurization controls the stroke value of the pressing pin so that the stroke value at the time of pressure casting is stopped and retracted at a position where the stroke value is less than the full stroke value.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In the pressure casting apparatus of the present invention, the pressure pin is used to press or press the pressure pin with a hydraulic cylinder immediately before solidification to a molded product which is being pressure-molded using a mold to reduce or eliminate the porosity. It is for.

FIG. 1 shows a hydraulic circuit for operating a pressure pin of a die casting machine used in the present invention.

In the following description of the hydraulic circuit, only the main components will be described, and the details are omitted because they are general techniques.

In FIG. 1, reference numeral 1 is a hydraulic pressure supply device, and the hydraulic pressure supply device 1 is a hydraulic pump 2, a motor 3, a relief valve 4,
It consists of tank 5 and so on. The pressure oil supplied from the hydraulic pressure supply source 1 is further pressurized by the accumulator ACC, and the relief valve 6 as a pressure adjusting section pressure unit for adjusting the pressure of the hydraulic oil from the hydraulic pressure supply source 1 and the proportional electromagnetic release The flow valve 7 and the proportional electromagnetic directional flow valve 8 as a flow rate adjusting unit for adjusting the flow rate of the hydraulic oil, the series type pressure compensating valve 9 as a pressure compensating unit, the pressure reducing valve 10, and the flow rate adjusting unit A direction switching valve 12 for switching the direction of the adjusted hydraulic oil, and a hydraulic cylinder 14 connected to the direction switching valve 12 for moving the pressurizing pin 13 back and forth.
And a control device 15 for controlling the position of the pressurizing pin 13 and controlling the starting and operating time of the hydraulic cylinder 14.

The position control of the pressurizing pin 13 is performed by indirectly measuring the position by the flow rate counter 11 that counts the flow rate of the hydraulic oil that has passed through the direction switching valve 14 in a predetermined unit, and by the control device 15. You can also

Next, the detailed structure of the pressure pin 13 will be described with reference to the sectional view of FIG.

In the figure, for the positioning control of the pressure pin 13, a linear scale 19 is provided on the right side of the piston 14a of the hydraulic cylinder to measure the tip position of the rod 14b, and a screw is provided at the tip of the rod 14b. 14c is formed, and the holding nut 16 and the nut 16a are screwed together to form a double nut. A flange portion 13a additional pressure pin 13 is movably engaged with the holding nut 16, and the flange portion 13a locks the pressure pin 13 from being separated from the holding nut 16. Flange 13a and rod 14b
A piezoelectric element 20 as a pressure sensor is sandwiched between
The thrust force of the pressure pin 13 can be detected.

In order to protect the piezoelectric element 20, the flange portion 13a of the pressure pin 13 is provided with a ring-shaped stopper 2.
1, the piezoelectric element 20 is inserted into the stopper 21, the end face of the stopper 21 and the rod 14b are brought into contact with each other, and the piezoelectric element 20 is compressed to a range in which the piezoelectric element 20 operates.
Prevent them from being destroyed.

The controller 15 controls the starting and operating time of the hydraulic cylinder 14.

The operation of the pressure casting apparatus of the present invention will be described.

First, when the molten metal is put into an injection sleeve and injected, the molten metal is filled in the cavity. At that time, the pressure of the injection cylinder rises, which is detected by the series type pressure compensating valve 9 and sent to the controller 15. The controller 15 controls the timers T1 and T2, the proportional electromagnetic directional flow valve 8, and the proportional electromagnetic release valve 7 based on the preset time T, flow rate Q, and pressure P. The objects can be achieved by controlling the flow rate Q and the pressure P independently or mutually.

When the injection sleeve steps on the high-speed injection limit switch, the pressurizing pin operates after the timer time T1 when the set pressure of the series type pressure compensating valve 9 and the pressure reducing valve 10 is reached. After the timer-T1 has timed out, the proportional electromagnetic directional flow valve 8 operates via the proportional electromagnetic relief valve 7 to finely control the flow rate Q, and pressurize the pin 1 against the molded product.
Squeeze according to 3.

The squeeze is controlled by the control device 15 which controls the starting and squeeze operation time of the hydraulic cylinder 14 and the squeeze pressure.

Since the squeeze stroke is measured by the scale 15 and the sensor 25 during the squeeze, the moving distance of the squeeze stroke pushed immediately before solidification can be directly measured from this count value.

Next, the measured squeeze pressure is compared with the set squeeze pressure, and the hydraulic cylinder 14 is operated to pressurize the molded product until the set squeeze pressure reaches a predetermined range, and the stroke at the time of pressure casting. Stops when the value is less than the full stroke value. When the direction switching valve 12 is de-energized after the time T2 for holding the pressurizing pin 13 expires, the hydraulic cylinder 14 returns to the forward state and waits for the next injection start. The piezoelectric element 2 as a pressure sensor is provided at the tip of the hydraulic cylinder 14.
The pressure pin 13 is operated via 0 to directly measure the position of the pressure pin 13 via the piezoelectric element 20, and based on the pressure obtained by the piezoelectric element 20, the position of the hydraulic cylinder and The operating time is controlled by the control device.

Further, the local pressurization is a stroke at the time of pressure casting.
The stroke value of the pressure pin 13 is controlled so that the stroke value is stopped and retracted at a position where the stroke value is less than the full stroke value. Further, the stroke value of the pressure pin 13 is controlled so that the stroke value at the time of pressure casting is stopped and retracted at a position where the stroke value is less than the full stroke value.

For the pressure pin 13, the piezoelectric element 20 is put in the stopper 21, and the end face of the stopper 21 is brought into contact with the pressure pin 13, and compressed to a range in which the piezoelectric element 20 operates,
Prevents the piezoelectric element from breaking.

At this time, since the proportional electromagnetic directional flow valve 8 is in the neutral state, the pressure oil cannot pass through and flows to the accumulator ACC side to accumulate the pressure in the accumulator ACC.

The surplus pressure oil is collected in the tank 5 via the relief valve 7.

A signal from the piezoelectric element 20 is received by an external receiver (not shown) using the oscillator 22, controlled by the controller 15, and the hydraulic cylinder 14 is controlled.

As described above, according to this embodiment, the pressure pin is pushed in immediately before solidification by the hydraulic cylinder, the pressure of the pressure pin is detected, and the pressure in the molding state during casting Since the pressurizing pin is pushed in immediately before solidification while controlling the flow rate and time, local pressurization suitable for the molded product can be performed, and the porosity can be reduced or eliminated.

[0038]

According to the present invention, the pressure pin is pushed in immediately before solidification by the hydraulic cylinder, the pressure of the pressure pin is detected, and the flow rate and the time are respectively adjusted with the pressure in the molding state during casting. Since the pressure pin is pushed in immediately before solidification while controlling, a squeeze suitable for the molded product can be performed, and porosity can be reduced or eliminated.

[Brief description of drawings]

FIG. 1 shows a hydraulic circuit for operating a pressure pin in a die casting machine.

FIG. 2 is a cross-sectional view showing a detailed configuration of a pressure pin.

[Explanation of symbols]

 1 Hydraulic Supply Source 7 Proportional Electromagnetic Release Valve 8 Proportional Electromagnetic Directional Flow Valve 9 Series Type Pressure Compensation Valve 13 Pressurizing Pin 13a Flange 14 Hydraulic Cylinder 15 Controller 16 Holding Nut 20 Piezoelectric Element

Claims (3)

[Claims] 1. A pressure casting apparatus, wherein a pressurizing pin is pressed by a hydraulic cylinder immediately before solidification to reduce or eliminate a porosity in a molded product under pressure casting using a metal mold. A supply source, a pressure adjusting unit for adjusting the pressure of the hydraulic oil from the hydraulic pressure source, a pressure compensating unit for compensating the pressure of the hydraulic oil adjusted by the pressure adjusting unit, and a pressure adjusting unit for the pressure compensating unit. A flow rate adjusting unit that adjusts the flow rate of the hydraulic oil that is adjusted, a direction switching valve that switches the direction of the hydraulic oil whose flow rate is adjusted by the flow rate adjusting unit, and a pressure sensor between the pressurizing pin and the end of the cylinder rod. A hydraulic cylinder for moving the pressure pin forward and backward, a position detection sensor provided on the cylinder rod for directly measuring the position of the pressure pin, and a control device for controlling the starting and operating time of the hydraulic cylinder. That configured by Characteristic local pressure device. 2. A linear scale is provided on one side of the piston of the hydraulic cylinder to measure the position of the tip of the rod, and a screw is formed on the tip of the rod on the other side, and a nut is screwed into the piston. A flange part additional pressure pin is movably fitted to the holding nut, and the flange part locks the pressure pin from coming off the holding nut, and a piezoelectric element is sandwiched between the flange part and the rod. A pressure pin device characterized in that it is configured to detect the thrust force of the pressure pin. 3. A ring-shaped stopper is provided on the flange portion of the pressure pin, the piezoelectric element is inserted into this stopper, and the end face of the stopper is brought into contact with the rod to compress the piezoelectric element beyond the range in which the piezoelectric element operates. The pin device according to claim 3, wherein the piezoelectric device is prevented from being broken.