JPH03174968A - Method and apparatus for controlling increased pressure rise time in injection cylinder - Google Patents

Abstract

PURPOSE:To stabilize quality of a casting product by storing relation of opening degree of a control valve for increased pressure rise time and the increased pressure rise time and automatically controlling the actual value of increased pressure rise time in the permissible range of the set value. CONSTITUTION:The opening degree of control valve 24 for increased pressure rise time is detected with an encorder 29 arranged to a driving shaft for motor 28a in a stroke setting mechanism 28, and at the time of inputting this signal into an input unit, this is compared with the inputted set value from a data input instrument 33, and the motor 28a is driven till coming to no difference and positional control is executed. By this method, the quality of casting product can be stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to control of pressure increase rise time in an injection circuit of a die casting machine.

[Prior Art] An example of a conventional injection pressure control method for a die-casting machine will be described with reference to Japanese Patent Publication No. 59-47626. After the elapse of time, measure the injection cylinder's extrusion oil pressure (boosting force), compare the average value of this measured value with the set value, and if the difference exceeds the allowable range, the injection cylinder's press oil pressure in the next casting cycle is determined to be acceptable. It is characterized in that the pressing oil pressure is corrected by correcting the opening degree of the pressure increase setting valve so that it falls within the range.

The pressure increase start timing is a set point on the stroke of the shot plunger at the injection cylinder brake start point, and the pressure increase start valve is opened at this point.

[Problem to be solved by the invention] From the stroke of the shot plunger to the brake starting point,
In other words, there is a large error in setting the point at which the pressurizing pressure of the injection cylinder starts rising when the cavity is filled with molten metal, and if the pressure increase starts too early, the solidification of the molten metal in the cavity has not progressed and the liquid is ejected. If this point is too late, solidification of the molten metal will be completed and the increased pressure will have no effect, making it impossible to obtain a sound cast product.

In Japanese Patent Publication No. 59-47626, the opening degree of the pressure increase setting valve is corrected to correct the pressure of the hydraulic source, and the pressure at the completion of pressure increase is controlled, which controls the rise time of pressure increase, which affects the quality of cast products. has not been carried out.

The present invention has been made with attention to the above points, and the state of the molten metal filled in the cavity is detected by the pressure hydraulic pressure of the injection cylinder, pressure increase is started, and the pressure increase rise time is measured and set. The purpose is to compare and control the pressure rise time and maintain it within an acceptable range to stabilize the quality of the cast product.

[Means for Solving the Problems] fi+injection pressure is detected by the pressing oil pressure of the injection cylinder, and the increase in the pressing oil pressure of the injection cylinder upon completion of filling the cavity with molten metal causes a predetermined pressure to be lower than the highest pressure of the first hydraulic circuit. The point in time when the reduced set pressure exceeds the first pressure is used as a reference point for pressure increase rise time measurement, and the first hydraulic circuit is shut off when the maximum pressure is reached, and the pressure increase rise time adjustment valve is turned on. It opens and starts pressure increase, and the relationship between the pressure increase rise time of the pressure increase rise time adjustment valve and the opening degree of the pressure increase rise time adjustment valve is stored in advance in a storage device, and the set pressure increase rise time is set. The opening degree of the pressure increase rise time adjustment valve is automatically set in accordance with the above, and the pressure increase rise time is measured, with the time when the pressure is increased to the preset second pressure as the time when the pressure increase rise time measurement is completed, and the pressure increase rise time is measured. The pressure increase rise time is compared with the preset pressure increase rise time, and if the allowable range is exceeded, an alarm signal is issued, and the opening degree of the pressure increase rise time adjustment valve is controlled to increase the pressure increase to the preset pressure increase time. A method of controlling the pressure increase rise time of an injection cylinder, characterized in that the rise time of the chamber is maintained within an allowable range.In the apparatus of the present invention, a hydraulic accumulator is provided as a hydraulic power source, an injection speed control valve, A first hydraulic circuit communicates with the pressure hydraulic port of the injection cylinder via a pressure increase check valve, and is branched from the hydraulic accumulator and connected to a pressure increase cylinder provided on the pressure hydraulic side of the injection cylinder via a pressure increase rise time adjustment valve. In the pressure increase rise time control device for the injection cylinder of the die-casting machine having a communicating second hydraulic circuit, one of the two relief valves set at a pressure slightly lower than the maximum pressure of the first hydraulic circuit is set to a pressure slightly lower than the maximum pressure of the first hydraulic circuit. A pilot hydraulic line communicates with the pilot hydraulic port of the pressure check valve to close the pressure increase check valve, and another one of the relief valves communicates with the pilot hydraulic port of the pressure increase rise time adjustment valve to close the pressure increase check valve. a pilot hydraulic line that opens the pressure rise time adjustment valve; a pressure sensor that detects the pressure pressure of the injection cylinder; and a relationship between the pressure rise time of the pressure rise time adjustment valve and the opening degree of the pressure rise time adjustment valve. is stored in a storage device, the opening degree of the pressure increase rise time adjustment valve is automatically set in accordance with the set pressure increase rise time, and the output of the pressure sensor is input, and the preset first Measure the pressure increase rise time from the time the pressure exceeds the preset pressure to the time the preset second pressure is reached, compare this time with the set pressure increase rise time, and if it exceeds the allowable range, an alarm will be activated. A calculation device is provided that controls a stroke setting mechanism that, upon emitting the signal, controls the opening degree of the pressure increase rise time adjusting valve to maintain it within a preset allowable range of the set pressure increase rise time. It is characterized by being

[Function] The press hydraulic pressure of the injection cylinder upon completion of filling the cavity with molten metal is detected by the pressure increase in the first hydraulic circuit, and the relief valve is set slightly lower than the maximum pressure of the first hydraulic circuit and activated to increase the pressure. At the same time as the check valve is closed, the other relief valves are activated and the pressure increase rise time adjustment valve is opened to begin pressure increase, and the opening degree of the counter valve is controlled to control the pressure increase rise time. By creating a relationship curve between the pressure increase rise time TA and the opening degree EN of the pressure increase rise time adjustment valve, and storing it in the microcomputer, the pressure increase rise time T can be automatically controlled to a set value.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a hydraulic circuit of an injection cylinder of a die-casting machine for implementing the injection cylinder pressure increase rise time control method of the present invention.

Reference numeral 1 denotes a mold device which injects and fills a cavity 2 with molten metal 3 by pressing it with an injection plunger 4, thereby performing pressure casting.

The injection plunger 4 is attached to a piston rod 5A of a hydraulically operated injection cylinder 5, and molten metal is injected under pressure by operating the injection cylinder 5.

The pressure increase cylinder 6 is located behind the injection cylinder 5 and supplies pressure increase oil to the injection cylinder 5. A position sensor 16 for detecting the position of the injection plunger 4 is provided on the side of the injection cylinder 5, thereby detecting when the injection plunger 4 passes through each preset point. .

The injection cylinder 5 is also provided with a pressure sensor 3o for measuring the working oil pressure within the injection cylinder 5.

Reference numeral 9 denotes an accumulator connected to a hydraulic pressure source lo and filled with a constant pressure.

Reference numeral 11 denotes an injection speed control valve, which uses an electric motor M to adjust the position of stoppers (15A, 19A) that come into contact with a piston IIA that determines the opening degree of the injection speed control valve 11.
The amount of oil in the tank is controlled, and the speed of the injection plunger 4 is controlled.

Stroke setting mechanisms 15 and 19 are provided on both sides of the injection speed control valve 11, respectively, to adjust the positions of the stoppers (15A, 19A), and to set the stroke using the pilot piston 12 and the chamber 17 and port 18. The speed of the injection plunger 4 is controlled to be low or high, respectively, by setting the stroke and adjusting the opening of the piston IIA.

Reference numeral 13 denotes a pressure increase check valve, which is used to increase the injection pressure immediately before the injection plunger 4 completes injection. 14
is a pilot piston that controls opening and closing of the piston 13A in the pressure increase check valve 13.

Reference numeral 24 denotes a pressure increase rise time adjustment valve that adjusts the rise time of the injection pressure immediately before the injection plunger 4 completes injection. Electric motor 2
8a and the stroke setting mechanism 28 to set the opening degree of the pressure increase rise time adjustment valve 24, and this opening degree is detected by the encoder 29.

The pressure sensor 30 is connected to an arithmetic device 31 via an A/D converter 39, and a detection signal is input to the arithmetic device 31.

FIG. 3 is a schematic diagram illustrating microcomputer control related to injection pressure control, in which a calculation device 31 includes an input device 32 into which a detection signal is input, and a predetermined calculation process on the data input to this input device 32. It is configured to include a central processing unit 34, a storage device 35 that stores calculation results etc. obtained by the central processing unit 34, and an output device 36 that outputs a predetermined signal according to the calculation result.

A data input device 33 is connected to the input device 32 of the calculation device 31, and the data input device 33 inputs the pressure increase time T of the pressure increase rise time adjustment valve 24 and the pressure at the reference point for measuring the pressure increase rise time. P1. Increased pressure P2 is input as a set value.

At this time, the set values T, Pl, and P2 are set according to conditions specific to the mold. Also, the computing device 31 has a display bag such as a CRT! 40 are connected.

This display device 40 can output data obtained by processing a detection signal from the pressure sensor 30 via the A/D converter 39 to the arithmetic device 31. Further, an alarm device 41 is connected to the arithmetic device 31 via an amplifier 37.

The alarm device 41 can issue an alarm with a buzzer or a light, and is activated when the measured value TA of the pressure increase rise time exceeds the above-mentioned set value plus the allowable range. Furthermore, the arithmetic unit 31 is connected via an amplifier 37 and a drive power supply 38 to an encoder 29 provided on the drive shaft of the electric motor 28a of the stroke setting mechanism 28. The encoder 29 detects the opening degree of the pressure increase rise time adjustment valve 24 and sends the signal to the input bag r11 in the arithmetic unit 31.
32 is entered.

7.8 are injection speed control valve 11 and pressure increase check valve 1, respectively.
3. A first hydraulic circuit and a second hydraulic circuit that connect the pressure increase cylinder 6 and the pressure increase rise time adjustment valve 24. 22.23 is the first
This is a relief valve that operates at a pressure slightly lower than the maximum pressure of the hydraulic circuit 7. 21 and 27 are solenoid valves for switching oil paths. 20, 25, and 26 are pilot hydraulic lines, respectively.

Next, in FIG. 2, various variables related to the operation of this hydraulic circuit will be described.

FIG. 2 is a graph of the injection pressure curve, in which the pressure pressure of the injection cylinder 5 is detected by the pressure sensor 30, and the A/D converter 39 detects the pressure pressure of the injection cylinder 5.
The image is inputted to the input device 32 via the , and is processed and displayed. In this graph, the vertical axis is the injection pressure, the horizontal axis is time, S is the injection start point, H is the switching point from low injection speed to high injection speed, point A is the injection pressure at point H, and point B is the injection speed. The point at which the plunger 4 completes injection and filling of the molten metal 3 into the cavity 2 and the pressure begins to rise rapidly, the 0 point is the point at which the pressure continues to rise and the first hydraulic circuit 7 shown in FIG. 1 rises to the maximum pressure PIM, Point D is relief valve 2
2.23 This is the pressure drop point when the valve is opened.

The pressure increase rise time refers to TA in FIG. 2, and is the time obtained by adding γ to the actual pressure increase rise time T during which the pressure increase rise time adjustment valve 24 operates.

Note that TA represents the measured value of the pressure increase rise time, and T represents the set value of the pressure increase rise time inputted from the data input device 33. Furthermore, the pressure Pi at point G on the injection pressure curve is the pressure (
P1=PACC-α), and Pl<PIM (maximum pressure of the first hydraulic circuit 7).

Point G is the reference point for the pressure increase rise time TA, and point F is the completion point of measurement of the pressure increase rise time.

Point F is the point at which the pressure reaches 90% of the pressure increase completion pressure P2M.

Incidentally, the pressure increase rise curve DF'Ef point Ml corresponds to the case where the pressure increase rise time is TA', which is the case where the pressure increase rise time is slow.

Next, the operation of the hydraulic circuit accompanying the injection process of the injection plunger 4 will be described below with reference to FIGS. 1 to 5.

As shown in FIG. 1, the injection speed control valve 11
The injection speed control valve 1 is activated by operating the pilot piston 12 of the injection speed control valve 1.
1, operate the pilot piston 14 of the pressure increase check valve 13 to open the pressure increase check valve 13,
Hydraulic pressure from the accumulator 9 is supplied to the injection cylinder 5.

The pilot pistons 12 and 14 are operated by a pilot hydraulic circuit using solenoid valves (not shown), but a detailed explanation thereof will be omitted. In addition,
The opening degree of the injection speed control valve 11 is adjusted by the stroke setting mechanism 1.
It is done by 5.

Next, the stroke of the injection plunger 4 is detected by the position sensor 16, and a signal is generated at the time of switching from the low injection speed to the high injection speed. In response to this signal, the injection speed control valve 11
The hydraulic pressure in the chamber 17 on the right side of the chamber 17 is discharged into the oil tank by switching a solenoid valve of a pilot hydraulic circuit (not shown) connected to a port 18. tti5 The opening degree of the injection speed control well 11 is set in advance by the stopper 1 of the stroke setting mechanism 19.
9A to switch to a high injection speed.

Next, the injection plunger 4 moves forward and pours the molten metal 3 into the cavity 2.
The injection plunger 4 is injected and filled, and when the filling is completed, the injection plunger 4 is rapidly decelerated. Therefore, the oil pressure in the first hydraulic circuit 7 rises rapidly and rises from point B to point 0 on the injection pressure curve shown in FIG.

However, since the set pressures of the relief valves 22 and 23 are kept slightly lower than the maximum pressure PIM of the first hydraulic circuit 7, which corresponds to the pressure at the zero point, the hydraulic pressure of the first hydraulic circuit 7 is controlled by the pilot hydraulic line 20, the solenoid Relief valves 22.23 are actuated via valve 21, discharging the hydraulic pressure in the pilot hydraulic line 25.26 to the oil tank. When the hydraulic pressure in the pilot hydraulic line 26 is discharged, the pressure increase check valve 13 moves to the right and shuts off the first hydraulic circuit 7. In addition, the pilot hydraulic line 25 is the pilot hydraulic pressure of the pressure increase rise adjustment valve 24, and is supplied with hydraulic pressure from the solenoid valve 27 connected to the hydraulic line of the accumulator 9.
Since the solenoid valve 27 is normally open, when the relief valve 22 opens, its pilot oil pressure is discharged to the oil tank and becomes zero.

Then, the pressure increase rise time adjustment valve 24 opens, the pressure of the accumulator 9 is supplied to the second hydraulic circuit 8, and the pressure increase cylinder 6 starts operating.

Next, the encoder 29 provided on the drive shaft of the electric motor 28a of the stroke setting mechanism 28 detects the opening degree of the pressure increase rise time adjustment valve 24, and inputs the signal to the input device 32. The electric motor 28a is driven and positioning is controlled until there is no difference compared with the value.

FIG. 4 shows the relationship between the opening degree of the pressure increase rise time adjustment valve 24 and the pressure increase rise time TA, which was created through tests using an actual machine.The data of this curve is inputted from the data input device 33 via the central processing unit 34. and is stored in the storage device 35.

On the other hand, the injection pressure is detected by inputting the signal of the pressure sensor 30 to the input device 32 through the A/D converter 39, processed by the central processing unit 34, and then sent to the output device.
It is also possible to output a curve as shown in FIG. 2 to a display device 40 such as a CRT. The V alarm device 41 is configured to output when the measured value TA of the pressure increase rise time exceeds a set tolerance range T±β (tolerance value) of the pressure increase rise time. The pressure increase rise time TA is measured by using the pressure PI (P1=PACC-〇) at the reference point for pressure increase rise time measurement (point G in Figure 2) and the pressure increase pressure P2 (P2=P2Mx0.9). Set by inputting from the data input device, detect the point in time when the injection pressure from the pressure sensor 30 exceeds the pressure Pl, start measuring the pressure increase rise time TA, then detect the pressure P2, and measure it. is to be completed.

Next, the present invention will be explained with reference to the injection pressure curve graph shown in FIG. 2 and the flowchart shown in FIG.

Start the control program of the present invention to determine the allowable range T±β of the pressure increase rise time, that is, the upper limit T10β, the lower limit lower −
Measurement reference point for β and pressure increase rise time TA (point G in Figure 2)
The measurement completion point of pressure P1 and pressure increase rise time TA (second
The increased pressure P2 at point F in the figure is input and set from the data input device 33.

When this setting is completed, proceed to the next step, and store the pressure increase rise time setting value from the memory device @35 that stores the relationship between the opening degree EN of the pressure increase rise regulating valve 24 and the pressure increase rise time TA shown in FIG. Opening degree EN of the pressure increase rise time adjustment valve 24 corresponding to the bottom
Read out.

Next, the stroke setting mechanism 28 is set to the pressure increasing rise time adjusting valve 2.
Positioning control is performed to the opening degree EN of 4.

Then, a casting cycle is executed and measurement of the injection pressure inside the pressure increase cylinder 6 is started. Here, it is detected whether the injection pressure exceeds PI, and the measurement of the pressure increase rise time TA is started from the time when the injection pressure exceeds PL.

Next, it is detected whether the increased pressure has reached P2, and the measurement of the increased pressure rise time TA is completed.

Next, this pressure increase rise time TA is compared with the pressure increase rise time set values ``lower β'' and ``T-β'' including the allowable range, and (T+β
)≦TA, (T-β)≧TA! A message is output to a display device 40 such as an f-reply signal CRT.

When (T+β)≦TA, the stroke setting mechanism 28 of the pressure increase rise time adjustment valve 24 reduces the opening degree of the pressure increase rise time adjustment valve 24, and when (T−β)≧TA, the pressure increase rise time 2
After increasing the opening degree of 4, repeat the next casting cycle.

Furthermore, if (T-β) <TA< fT+I3), it is within the allowable range, and the next generation cycle is continued.

The corrective control for (T+β)≦TA, (T-β)≧TA is not limited to the above, but the corrective control should be performed when the average value of TA exceeds the allowable range over multiple casting cycles. good.

[Effect of the invention 1] The relationship between the opening degree of the pressure increase rise time adjustment valve and the pressure increase rise time is stored in the memory of the computing device, and the actual value of the pressure increase rise time is automatically brought within the allowable range of the set value. By controlling this, the quality of the cast product can be stabilized.

[Brief explanation of drawings]

Fig. 1 is an injection cylinder hydraulic circuit diagram of the die casting machine of this embodiment, Fig. 2 is a graph of an injection pressure curve, Fig. 3 is a schematic diagram explaining microcomputer control regarding injection pressure control, and Fig. 4 is a pressure increase FIG. 5 is a flowchart showing the relationship between the rise time adjustment valve and the pressure increase rise time. l... Mold device, 2... Cavity, 3... Molten metal, 4... Injection plunger, 5... Injection cylinder, 6
...-pressure increase cylinder, 7... first hydraulic circuit, 8...
2nd hydraulic circuit, 9...-accumulator, 10...hydraulic source, 11...injection speed control valve, 12...pilot piston, 13...pressure increase check valve, 14...
Pilot piston, 15.19.28... Stroke setting mechanism, 16... Position sensor, 17... Chamber, 18... Port, 20.25.26... Pilot hydraulic line, 21.27.・・Solenoid valve,
22.23 - Relief valve, 24 - Pressure increase rise time adjustment valve, 28a - Electric motor, 29 - Encoder, 30 - Pressure sensor, 31 - Arithmetic unit, 3
2... Input device, 33... Data input device, 34...
-Central processing unit, 35...Storage device, 36...Output device, 37...-Amplifier, 38...Drive power supply device, 3
9... A/D exchanger, 40... Display device, 41...
・Alarm device.

Claims (2)

[Claims] (1) The injection pressure is detected by the pressing oil pressure of the injection cylinder, and the increase in the pressing oil pressure of the injection cylinder upon completion of filling the cavity with molten metal is the set pressure that is a predetermined pressure less than the maximum pressure of the first hydraulic circuit. The time when the pressure exceeds the pressure is used as a reference point for measuring the pressure increase rise time, and the first hydraulic circuit is shut off when the maximum pressure is reached, and the pressure increase is started by opening the pressure increase rise time adjustment valve. The relationship between the pressure increase rise time of the pressure increase rise time adjustment valve and the opening degree of the pressure increase rise time adjustment valve is stored in advance in a storage device, and the pressure increase is performed in accordance with the set pressure increase rise time. The opening degree of the rise time adjustment valve is automatically set, and the pressure increase rise time is measured, with the time when the pressure is increased to a preset second pressure as the completion of the pressure increase rise time measurement, and this time and the preset increase Compare the pressure rise time with the pressure rise time, and if the pressure rise time exceeds the allowable range, issue an alarm signal and control the opening degree of the pressure rise time adjustment valve to bring the pressure rise time within the preset allowable range. A method for controlling the pressure increase rise time of an injection cylinder, characterized in that the pressure increase rise time is maintained. (2) A hydraulic accumulator is provided as a hydraulic power source, and a first hydraulic circuit is connected to the press hydraulic port of the injection cylinder via an injection speed control valve and a pressure increase check valve, and is branched from the hydraulic accumulator to adjust the pressure increase rise time. In a control device for increasing pressure rise time of the injection cylinder of a die-casting machine, the control device has a second hydraulic circuit communicating with a pressure increasing cylinder provided on the pressing hydraulic side of the injection cylinder via a valve, A pilot hydraulic line that connects one of the two relief valves set at a slightly lower pressure to the pilot hydraulic port of the pressure increase check valve to close the pressure increase check valve, and the other one of the relief valves. a pilot hydraulic line that communicates with a pilot hydraulic port of the pressure increase rise time adjustment valve to open the pressure increase rise time adjustment valve; a pressure sensor that detects the pressure pressure of the injection cylinder; and a pressure sensor for detecting the pressure pressure of the injection cylinder; The relationship between the pressure increase rise time and the opening of the pressure increase rise time adjustment valve is stored in a storage device, and the opening of the pressure increase rise time adjustment valve is automatically set in accordance with the set pressure increase rise time. Then, input the output of the pressure sensor, measure the pressure increase rise time from the time when the preset first pressure is exceeded to the time when the preset second pressure is reached, and calculate this time and the above setting. When the pressure increase rise time is compared and exceeds the allowable range, an alarm signal is issued and the opening degree of the pressure increase rise time adjustment valve is controlled to ensure that the pressure rise time is within the preset allowable range. 1. A pressure increase rise time control device for an injection cylinder, comprising an arithmetic device that controls a stroke setting mechanism that maintains a stroke setting mechanism.