JP2000005857A - Press casting machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate dispersion of a press pin protruding velocity due to temperature variation of a hydraulic operation fluid. SOLUTION: An opening degree of a flow volume adjusting valve 8 is corrected by a computer 12 corresponding to a detection signal of an instantaneous temperature sensor 11 mounted to an oil path B when the valve 8 is controlled by PID control of the movement of a press pin 4. Thereby, since the opening degree of the flow volume valve is adjusted corresponding to temperature variation of the hydraulic operation fluid, dispersion of the press pin movement can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure casting machine in which when a molten metal is condensed, a pressure pin is projected into a cavity to compensate for the shrinkage of the molten metal by the projected portion.

[0002]

2. Description of the Related Art For example, in aluminum casting, when the molten aluminum solidifies, it shrinks, so a space is created due to the reduced bulk, and defective products such as incomplete shapes and nests inside are generated. Invite. Therefore, the pressing pin is projected into the cavity to compensate for the amount of contraction, thereby eliminating the influence of the contraction. In the pressure pin, the projecting timing occupies an important factor, and in the unsolidified state, the shrinkage has not yet started yet, and it is too early. They must be projected together. Therefore, conventionally, as described in, for example, JP-A-6-226416, the ideal operation of the pressing pin is created as master data, and the apparatus shown in FIG. An attempt has been made to detect the protruding stroke of the pressure pin 4 with the attached potentiometer 14 and compare it with the master data to control the operating pressure of the hydraulic cylinder 5 and the flow rate of the operating oil in a direction to reduce the difference between the two to zero. ing. In FIG. 6, reference numeral 8 denotes a flow control valve, 9 denotes a pressure control valve, and these valves are controlled by a computer 12.

[0003]

Just as the temperature of the mold differs between the start of the work and after the shot is repeated several times, the temperature of the hydraulic oil also changes over time, and the temperature of the hydraulic oil also changes depending on the outside air temperature. It depends. When the temperature of the hydraulic oil changes, the characteristics also change, but in particular, the change in kinematic viscosity directly affects the flow rate. For this reason, there is a possibility that the pressurization timing varies, and the occurrence of underfill or nest cannot be completely prevented.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a pressure casting machine in which variations in pressure timing due to the influence of temperature are eliminated, and the structure thereof is provided in a hydraulic oil supply line for driving a pressure pin. The movement of the pressurizing pin is feedback-controlled by the flow control valve and the pressure control valve, and the control of the flow control valve can be corrected in accordance with the temperature change of the hydraulic oil. The position of the pressure pin can be detected based on a signal of an instantaneous flow meter provided in the hydraulic oil supply line, and the instantaneous flow meter can be disposed near the head side of the pressure pin driving cylinder. desirable. Further, the operation of the pressure pin can be detected using a potentiometer attached to a cylinder for driving the pressure pin. Furthermore, the temperature of the hydraulic oil is detected by using a temperature sensor disposed near the flow control valve, and correction according to the temperature change of the hydraulic oil is performed by changing the flow rate due to the kinematic viscosity that changes with temperature. It is desirable to execute based on.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A pressure casting machine according to the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a die set for pressure casting comprising a movable die 1a and a fixed die 1b, and the die set can be closed to form a cavity 2 therein. The mold 1b incorporates a plunger tip 3 for feeding molten aluminum into the cavity 2 and a hydraulic cylinder 5 serving as a pressure pin driving cylinder for projecting the pressure pin 4 into the cavity 2.

The hydraulic cylinder 5 is of a return type, and a hydraulic source 6
Pressure oil sent out of the solenoid valve 7 of 4 port 3 position type
And the pressure pin 4 attached to the tip of the piston rod is forced into the cavity 2 by being fed into one of the port 5a on the piston rod side and the port 5b on the head side on the opposite side. An advance or retreat operation is performed. A flow control valve 8 is provided in an oil passage A connecting the hydraulic pressure source 6 and the solenoid valve 7,
A pressure adjusting valve 9 is provided in an oil passage B connecting the solenoid valve 7 and the port 5b. Further, a temperature sensor 10 is provided in the oil passage A near the flow control valve 8, and an instantaneous flow meter 11 is provided in the oil passage B near the port 5 b of the hydraulic cylinder 5.
Is attached.

Reference numeral 12 denotes a CPU 12a and a controller 12
b, wherein the temperature sensor 10
And the signal from the instantaneous flow meter 11 are input to the CPU 12a,
The flow control valve 8 and the pressure control valve 9 are connected to the controller 1.
2b. Reference numeral 13 in the figure denotes a control panel for controlling the entire pressure casting apparatus.

In addition, the CPU 12a preliminarily stores the ideal operation state of the pressure pin, the pressurizing time and the pressurizing piston stroke in master data M shown by a solid line in FIG. Data N of kinematic viscosity characteristics of the hydraulic oil indicating the relationship with the viscosity are stored.

Next, an example of control by the computer 12 will be described.
This will be described with reference to FIG. First, when a pressurizing pin operation start command is issued from the control panel 13 to the computer 12 at the time a, the flow control valve 8 is opened by a predetermined amount by a signal output from the controller 12b, and then the electromagnetic valve 7 is opened. Operates, and a constant pressure oil is supplied through the oil passage B to the port 5b.
Is supplied into the hydraulic cylinder 5 and the pressure pin 4 starts to protrude. The CPU 12a sequentially calculates the stroke of the pressurizing pin 4 based on a signal sent from the instantaneous flow meter 11, and controls the PID control of the flow control valve 8 so that the actual stroke becomes the target value of the master data M. Control the pressure pin. When the CPU 12a controls the flow rate control valve 8, the computer 12 incorporates kinematic viscosity characteristics data shown in FIG. 3 based on temperature information from the temperature sensor 10 and controls the flow rate control valve 8 with respect to a reference temperature. The opening is controlled by correcting the constant, and the temperature sensor 10 is provided in the vicinity of the flow control valve 8, so that more accurate hydraulic oil temperature information can be obtained. As a result, the stroke control of the pressure pin which is not affected by the temperature change is realized.

In the above embodiment, the effect of the kinematic viscosity is eliminated by executing the control in which the opening of the flow control valve 8 is corrected.

Further, the movement of the pressurizing pin is not limited to the instantaneous flow meter, but a potentiometer 14 attached to the hydraulic cylinder 5 or an encoder as shown in FIG. 5 can be used. Furthermore, it is also possible to simultaneously execute the correction of the projecting timing of the pressurizing pin in accordance with the temperature change, or to use the capability of the hydraulic pressure source and the control of the pressure regulating valve together. The master data can be rewritten according to the characteristics of the molten metal, and the viscosity characteristics of the hydraulic oil are changed each time according to the type of the hydraulic oil.

According to the present invention, the control constant is corrected based on the information of the hydraulic oil temperature to control the opening of the flow regulating valve, so that the pressurizing pin always projects in an ideal state, so that there is no variation in products. .

[0013]

According to the present invention, since the opening of the flow control valve is corrected in accordance with the temperature change of the hydraulic oil, the operation of the pressure pin does not vary. If the operation of the pressure pin is detected using an instantaneous flow meter, control of the flow regulating valve can be easily performed in real time. In addition, since the device can be arranged without being affected by heat unlike a potentiometer, the device can be made compact. Further, by providing a temperature sensor for detecting the temperature of the hydraulic oil near the flow regulating valve, more accurate hydraulic oil temperature information can be obtained. And if you modify the conventional model especially based on the kinematic viscosity characteristics,
Errors can be minimized.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a pressure casting machine according to the present invention.

FIG. 2 is an explanatory diagram showing a relationship between time and a pressure stroke in each of master data and an actual pressure pin.

FIG. 3 is an explanatory diagram showing an example of control of a flow control valve and a pressure control valve.

FIG. 4 is an explanatory diagram of a modified example.

FIG. 5 is an explanatory diagram of a conventional example.

[Explanation of symbols]

1 die set, 1a movable mold, 1b fixed mold, 2 cavity, 3 plunger tip, 4
・ Pressure pin, 5 ・ ・ Hydraulic cylinder, 6 ・ ・ Hydraulic source, 7 ・
· Solenoid valve, 8 ··· Flow control valve, 9 ··· Pressure control valve, 10
..Temperature sensor, 11 ... Instantaneous flow meter, 12 ... Computer, 12a ... CPU, 12b ... Controller,
13 ··· Control panel, A, B ··· oil passage, M · · · master data, N · · · kinematic viscosity characteristics data for hydraulic oil.

Continued on the front page (72) Inventor Yoshio Fujita 2-1-1 Toyota-cho, Kariya-shi, Aichi Prefecture Inside Toyota Industries Corporation (72) Inventor Toshikazu Okada 2-1-1, Toyota-cho, Kariya-shi, Aichi Co., Ltd. F term in Toyota Industries Corporation (reference) 4F206 AA49 AM32 AP05 AP06 AR02 AR14 JA07 JM04 JN25 JP11 JQ81 JT07 JT21

Claims (6)

[Claims] 1. A hydraulic oil supply system for driving a pressurizing pin, wherein the pressurizing pin is protruded into a cavity when the melt condenses, and the protruding portion compensates for shrinkage of the melt. A pressure casting machine wherein the movement of the pressurizing pin is feedback-controlled by a flow control valve and a pressure control valve provided in a path, and the control of the flow control valve can be corrected according to a change in the temperature of hydraulic oil. 2. The method according to claim 1, wherein the position of the pressure pin is detected based on a signal from an instantaneous flow meter provided in the hydraulic oil supply line.
Pressurized casting machine described in 1. 3. The pressure flow meter according to claim 1, wherein the instantaneous flow meter is disposed near the head-side port of the pressure pin driving cylinder.
2. The pressure casting machine according to 1. 4. The pressure casting machine according to claim 1, wherein the operation of the pressure pin is detected by using a potentiometer attached to a cylinder for driving the pressure pin. 5. The pressure casting machine according to claim 1, wherein the temperature of the hydraulic oil is detected by using a temperature sensor disposed near the flow control valve. 6. The pressure casting machine according to claim 1, wherein the correction according to the temperature change of the hydraulic oil is executed based on a flow rate change due to an influence of a kinematic viscosity that changes with the temperature. .