JP2012240069A - Method for detecting abnormality of flow rate control valve in die casting machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for detecting abnormality of a flow rate control valve, each cycle, which controls injection speed and molten metal pressure, when aluminum molten metal in a molten state is ejected and filled in a die cavity, in an injection device of a die casting machine which casts aluminum products.SOLUTION: In the flow rate control valve which directly operates a spool with a servo motor and a conversion mechanism of rotary and linear motion, the spool is moved up to a mechanical moving boundary every one cycle, and a position detected at that time by an encoder of the servo motor is compared with a predetermined original position. When a deviation quantity exceeds tolerance, the flow rate control valve is determined to be abnormal, and then a warning is given to an operator.

Description

  The present invention relates to an abnormality detection method for a flow rate control valve for controlling an injection speed and a molten metal pressure when a molten aluminum melt is injected into a mold cavity in an injection device of a die casting machine for casting an aluminum product.

First, a general die casting apparatus and method in a horizontal die casting machine will be described with reference to FIG.
A die casting machine (casting apparatus) 100 includes a mold apparatus 101 and an injection apparatus 102. A fixed mold 3 and a movable mold 4 are attached to the mold apparatus 101 between a pair of opposed fixed platen 1 and movable platen 2. The fixed mold 3 and the movable mold 4 are closed by a mold clamping device including a fixed platen 1, a movable platen 2, an opening / closing device (not shown), and a product-shaped cavity 5 is formed therebetween. To do. In a state where a mold clamping force is applied, a molten product such as aluminum (AL) (in a molten state at a high temperature) is injected and filled into the cavity 5, and after cooling and solidifying, the mold is opened and taken out, whereby a cast product can be manufactured. An injection device 102 is provided in order to inject and fill the molten aluminum into the cavity 5. Further, the fixed platen 1 is provided with a sleeve 6 for storing molten aluminum, and is in fluid communication with the cavity 5 through the fixed platen 1 and the fixed mold 3.

The injection device 102 is provided with an injection cylinder 10 having a hydraulically driven reciprocating piston for injecting molten aluminum. The injection cylinder 10 includes an injection cylinder body 13 and a piston 12 that reciprocates. The piston 12 is provided with a piston head at the left end in FIG. 5, and the plunger rod 8 is connected to the tip of the piston rod integrated with the piston head by an injection coupling 9. Installed. The plunger tip 7 can be injected into the cavity 5 by fitting into the sleeve 6, reciprocating in the sleeve 6, and pumping the molten aluminum poured into the sleeve 6.
In the embodiment of FIG. 5, since the injection device 102 is hydraulic, hydraulic oil (not shown) supplies hydraulic oil to the head chamber 10H of the cylinder body 10 to drive the piston 12 forward. The molten aluminum (AL) stored in the sleeve 6 is pushed by the plunger tip 7 and injected into the cavity (cavity) 5 formed from the fixed mold 3 and the movable mold 4 to be cast.

Here, it is extremely important to properly set and control the injection speed and injection (molten metal) pressure when the molten metal is injected into the cavity.
A general casting injection speed pattern and the like will be described with reference to FIG.
In the pouring process before the injection filling process is started, the molten metal is poured into the sleeve 6 from the opening on the upper surface of the sleeve 6 by an unillustrated pouring device, and the injection is started. The tip position of the plunger tip 7 at this time is A. (See figure above figure 6)

From this state, a low-speed injection process is first performed. In this step, the plunger tip 7 is advanced at a low speed, but it is important that the molten metal does not entrain the air inside the sleeve 6. Therefore, stable low speed (VL) control is required. When the plunger tip 7 moves forward, the molten metal reaches the upper wall of the sleeve 6 and the molten metal surface rises to the vicinity of the gate and reaches the B position (when the injection stroke sensor detects that the SL has advanced), it switches to the high-speed injection process. It is done. (See the second figure from the top in Fig. 6)
In the high-speed injection process, the plunger tip 7 and the like are accelerated at a stroke, and the molten metal is injected and filled into the cavity 5 at a high speed (Vh). This is because the molten metal instantly solidifies when it comes into contact with the surface of the cavity 5 at a low temperature, and it is desirable for the casting of a good product to be filled before solidifying in as short a time as possible. In particular, when the cavity 5 (cast product) is enlarged and complicated, higher speed is required.

Then, immediately before the molten metal is completely filled in the cavity 5, the molten metal pressure in the cavity 5 increases, and the injection speed decreases. When the plunger tip 7 reaches the C position and the cavity 5 is filled with molten metal, the injection pressure (head pressure of the injection cylinder) further increases, so when the measured value of the pressure sensor becomes the set switching pressure, Is switched to the step of maintaining the pressure (increase). (See the third figure from the top in Figure 6)
In the pressurizing and holding step, burrs are generated when the pressure is increased too early, and shrinkage cavities are generated when the pressure is increased, and the pressure is increased at an appropriate pressure increasing rate. When the set holding pressure (P) is reached, the molten metal pressure is held and controlled for a certain period of time, and the plunger tip 7 is advanced by the amount that the molten metal solidifies and cools and contracts. (See the bottom figure in Figure 6)

Thus, in the injection filling process, stable high-speed injection speed control and boost pressure holding force control are required according to the set values, so the flow rate of hydraulic oil flowing into the injection cylinder is controlled with high response and high accuracy (meter-in control). ) Or a flow control valve that can control the hydraulic oil flowing out from the injection cylinder with high response and high accuracy (meter-out control) is required. Therefore, various flow control valves have been developed so far.
For example, Patent Document 1 discloses a flow rate control valve capable of controlling the spool in the valve directly in the axial direction by a servo motor and adjusting the valve opening with high accuracy. In this flow control valve, a ball screw is used to convert the rotary motion of the servo motor into a linear motion, and the rotary shaft of the servo motor and the ball screw shaft are connected by a coupling. In addition, since the ball screw nut and the spool which are screwed onto the ball screw shaft are connected, the axial position of the spool can be directly adjusted by the rotation control of the servo motor. Further, since the position of the spool can be directly detected from the rotation angle of the servo motor by the encoder directly connected to the rotation shaft of the servo motor, highly accurate feedback control is possible. Then, the flow rate of hydraulic oil flowing into or out of the injection cylinder is finely controlled to realize high-precision plunger advance speed control and injection pressure control.

JP-A-10-58114

However, the spool in the flow control valve receives a strong fluid force in the axial direction due to the hydraulic oil flowing at high speed in the valve. This force is converted into a strong torsional force of the ball screw shaft by the action of the ball screw, and also acts on the coupling connecting the ball screw shaft and the motor rotation shaft. At this time, when the coupling force of the coupling is not sufficient, the coupling is loosened, and a deviation occurs in the rotational direction between the ball screw shaft and the motor rotation shaft. When the deviation occurs, the detection of the spool position by the encoder becomes incorrect, and if the feedback control is performed based on the detection, the valve opening degree is deviated. Then, the injection speed and the pressure holding force control become unstable, deviating from the setting conditions for casting a good product, and the quality of the cast product is deteriorated. In addition, error control of the spool position detection may become unstable due to an encoder pulse detection error.
Therefore, in order to solve these problems, the present invention monitors the loose state of the coupling of the flow control valve and the pulse detection error of the encoder, and immediately issues a warning when an abnormality is detected, whereby the operator performs casting. By stopping, it is intended not to continue making defective products.

In order to solve the above problems, the first invention of the present invention is:
Mold for casting products, plunger for filling molten metal into the mold cavity, injection cylinder with piston connected to the plunger, and flow rate of hydraulic oil flowing into the injection cylinder by the operation of the spool Alternatively, the flow rate of the hydraulic oil flowing out from the injection cylinder can be adjusted to control the operating speed or pressure of the piston, and the spool control unit is equipped with a mechanism that converts the rotary motion into linear motion. In a die casting machine comprising: a servo motor capable of adjusting the position; and an encoder provided in the servo motor and capable of detecting the position of the spool based on the rotation amount of the rotation shaft of the servo motor.
When the spool of the flow control valve is moved to the mechanical movement limit for each casting cycle, the position detected by the encoder at that time is compared with the preset home position, and the deviation exceeds the allowable range. This is a method for detecting an abnormality of the flow control valve, which determines that the flow control valve is abnormal and issues a warning.

In the second invention, the flow control valve is connected to the rod chamber of the injection cylinder in the flow path according to the first invention, and when the plunger and the piston are retracted, the spool is moved to the mechanical movement limit. This is a method for detecting an abnormality of a flow control valve in which an abnormality is determined and a warning is issued from the detection position of the encoder.

  Since the state of the flow rate control valve is checked for each casting cycle and an abnormality is determined, a warning is issued, so that the operator can immediately stop casting of a defective product resulting from fluctuations in the injection filling process.

It is one Example of this invention, and is a hydraulic circuit diagram of an injection device. It is a figure which shows the structure of a flow control valve, a servomotor, a controller, etc. based on this invention. It is a figure which shows structures, such as a spool, a rotation linear motion conversion apparatus, a coupling apparatus, of the flow control valve concerning this invention. It is a graph which shows the state of the piston position, each valve | bulb, etc. at that time in the invention of this application, time change, such as an injection speed and a spray output. It is a figure which shows the injection device of a hydraulic drive system, and a metal mold | die periphery in a general die-casting machine. It is the figure and graph which show the relationship of the position of the plunger tip in the general die-casting, the state of a molten metal, the injection speed, and a molten metal pressure.

  Embodiments of a die casting machine injection device, hydraulic circuit, flow control valve, and abnormality detection method thereof according to the present invention will be described below in detail with reference to the drawings.

  Also in the present embodiment, the mold device, the plunger, the injection cylinder, and the like are the same as the general die casting machine shown in FIG. 5, but have a feature in the abnormality detection method of the flow control valve.

FIG. 1 shows a hydraulic circuit of an injection apparatus according to the present invention.
The head chamber 10 </ b> H of the injection cylinder 10 is connected to the injection accumulator 14 through the injection switching valve 18. The inside of the injection accumulator 14 is partitioned into an oil chamber and a gas chamber by a piston, and the gas chamber is connected to a gas bottle 17 by piping. The gas bottle 17 is filled with compressed nitrogen gas, and the working oil in the oil chamber of the injection accumulator 14 is supplied into the injection cylinder at once by using the energy when the high-pressure nitrogen gas expands. It is possible to achieve high-speed injection.
The head chamber 10 </ b> H has a pipe branched in the middle, and is connected to the pressure increasing accumulator 15 via the throttle valve 21 and the pressure increasing switching valve 19. The pressure increasing accumulator 15 is also partitioned into an oil chamber and a gas chamber by a piston, and a high pressure increasing holding force can be supplied to the head chamber 10H of the injection cylinder 10 by the pressure of nitrogen gas in the gas chamber.
Further, the head chamber 10H is also connected to the low speed forward / reverse switching valve 20 by a pipe. The low speed forward / reverse switching valve 20 is also connected to the hydraulic pressure supply device 22 via a tank 24 and a check valve 23. Therefore, when the a solenoid is excited, the hydraulic oil in the head chamber 10H can be returned to the tank 24, and when the b solenoid is excited, the hydraulic oil can be supplied from the hydraulic pressure supply device 22 to the head chamber.

The rod chamber 10R of the injection cylinder 10 is connected to a flow control valve (servo valve) 16 driven by a servo motor. The flow control valve 16 is connected to the hydraulic pressure supply device 22 through a tank 24 and a check valve 23. While the piston 12 of the injection cylinder 10 moves forward, the flow rate control valve 16 is operated so that the rod chamber 10R and the tank 24 communicate with each other, and by controlling the valve opening degree with high accuracy, meter-out control is performed. The high injection speed and the increased pressure holding force can be controlled. Further, when the flow control valve 16 is operated so that the rod chamber 10R and the hydraulic pressure supply device 22 are communicated with each other, the piston 12 can be retracted.
The hydraulic pressure supply device 22 includes a pump, a variable pressure control valve, a variable flow rate control valve, an electric motor, and the like. The hydraulic pressure supply device 22 can supply hydraulic oil at a desired pressure and flow rate, and can perform low-speed injection and backward movement of the piston 12. It has become so.
Further, the movable portion of the injection position speed sensor 26 is attached to the piston rod of the piston 12 so that the position and speed of the piston 12 can be measured, and a measurement signal is sent to the controller for use in feedback control.
The measurement of spray output (molten metal pressure) can be performed by a load cell mounted in the injection coupling, or pressure sensors are attached to the head chamber 10H and the rod chamber 10R, and converted from the respective cross-sectional areas. It can also be done.

  Next, the structure and the like of the flow control valve 16 will be described with reference to FIG. In the flow control valve main body 30, a stepped cylindrical spool 35 is mounted so as to be slidable in the axial direction (left-right direction in the figure). On the right side of the flow control valve body 30, a rotary linear motion conversion mechanism 31 and a coupling device 32 are attached, and a servo motor 33 is further attached. The rotational motion of the rotation shaft of the servo motor 33 is transmitted to the rotational linear motion conversion mechanism 31 by the coupling device 32, where it is converted into linear motion, and then transmitted to the spool 35 via the connecting rod 51, thereby opening and closing the valve. (Axial movement) is performed. An encoder 34 is attached to the servomotor 33 in a state where the rotation shaft is connected, and the rotation angle of the rotation shaft of the servomotor 33 can be detected. The servo motor 33 and the encoder 34 are electrically connected to the controller by wiring, and the servo motor 33 is operated by the command of the controller to move the spool 35. Also, the position of the spool 35 is converted from the detection signal of the encoder 34. And used for feedback control. Further, the controller is also electrically connected to the display device, and when an abnormality is detected in the flow control valve 16, the controller displays the abnormality and warns the operator. As another warning method, a buzzer can be sounded.

  Inside the flow control valve main body 30, there is provided a space portion in which the spool 35 is inserted as shown in FIG. The space includes a cylinder-side large-diameter portion 46 that communicates with the rod chamber of the injection cylinder 10 via the cylinder connection port 42, and a hydraulic-supply-side large-diameter portion that communicates with the hydraulic supply device 22 via the hydraulic supply device connection port 43. 45 and a tank-side large-diameter portion 47 communicating with the tank 24 through the tank connection port 41 is formed. The oil pressure supply side spool large diameter portion 35b is fitted in a slidable state with a slight gap in the oil pressure supply side small diameter portion 30c formed between the cylinder side large diameter portion 46 and the oil pressure supply side large diameter portion 45. The hydraulic oil is prevented from communicating between the cylinder-side large diameter portion 46 and the hydraulic pressure supply-side large diameter portion 45. Similarly, in the tank side small diameter portion 30b formed between the cylinder side large diameter portion 46 and the tank side large diameter portion 47, the tank side spool large diameter portion 35a is slidable with a slight gap. The hydraulic oil is prevented from communicating between the cylinder-side large-diameter portion 46 and the tank-side large-diameter portion 47. Large diameter portions are formed at both ends of the spool 35, and the outside flow of the hydraulic oil is prevented by fitting with the inner diameter portion of the flow control valve body 30 with a slight gap. The slightly leaked hydraulic oil is returned to the tank 24 via a small diameter pipe. In the spool 35, the space between the large-diameter portions at both ends, the tank-side spool large-diameter portion 35a, and the hydraulic pressure-supply-side spool large-diameter portion 35c is a space through which hydraulic oil flows.

2, the tank connection port 41, the cylinder connection port 42, and the hydraulic pressure supply device connection port 43 are all blocked by the tank side spool large diameter portion 35a and the hydraulic pressure supply side spool large diameter portion 35b, respectively. The closed position, which is the zero point position of the spool 35. When the spool 35 is moved to the right side by the operation of the servo motor 33 from this state, the tank-side spool large diameter portion 35a is positioned inside the cylinder-side large diameter portion 46, and the tank connection port 41 and the cylinder connection port 42 communicate with each other. Thus, the hydraulic oil in the rod chamber of the injection cylinder 10 can be returned to the tank 24. Further, when the spool 35 is moved to the left side, the hydraulic supply side spool large diameter portion 35b is positioned inside the cylinder side large diameter portion 46, and the hydraulic supply device connection port 43 and the cylinder connection port 42 communicate with each other. Hydraulic oil can be supplied to the rod chamber.
When the spool 35 is moved to the left by X mm from the state shown in FIG. 2, the spool left end surface 35c and the retreat side end surface 30a come into contact with each other, and the mechanical movement limit is reached. The controller stores the detected value of the encoder 34 with this position as the origin of the spool 35, so that the controller can accurately grasp the position of the spool 35 and control the opening degree of the flow control valve 16 as set.

FIG. 3 shows the internal structure of the rotary linear motion conversion device 31 and the coupling device 32 of the flow control valve 16.
The conversion device case 54 is fixed to the right side of the flow control valve main body 30, and a ball screw shaft 57 is rotatable inside by a bearing 58 and a holding nut 59 but is restricted in the axial direction. It is supported. A ball screw nut 56 that is screwed to the ball screw shaft 57 is connected to the spool 35 via a connecting rod 51. The connecting rod 51 is slidably fitted to a guide bush 53 incorporated in a guide rod bush fixing plate 52 fixed to the right side of the flow control valve main body 30. For this reason, the ball screw nut 56 is movable in the axial direction but is in a state in which rotation is constrained.
A coupling case 60 is fixed to the right side of the converter case 54, and a servo motor 33 is fixed to the right side thereof. The rotating shaft of the servo motor 33 is connected to the ball screw shaft 57 by the coupling 62, and can transmit the rotating motion.

Therefore, when a rotation command signal is sent from the controller to the servo motor 33, the rotation shaft, the coupling 62, and the ball screw shaft 57 rotate, and the ball screw nut 56 and the connecting rod are smoothly converted into a linear motion by the action of the ball screw. 51 and the spool 35 operate right and left.
By appropriately providing a rotation signal to the servo motor 33, the flow control valve 16 can be freely opened and closed and the opening degree can be adjusted.

From here, the abnormality detection method of the flow control valve of the injection device according to the present invention, which is performed using the hydraulic circuit and the hydraulic apparatus configured as described above, will be described with reference to FIG.
FIG. 4 is a graph showing piston (plunger) position, time change such as injection speed and injection power, movement of the piston 12 at that time, and the state of each valve in the injection filling process of the present embodiment. Pm represents a set holding force, and Pm ′ represents a switching force. The low-speed injection region is between times t0 and t1, the high-speed injection region is between times t1 and t2, the boosting region is between times t2 and t3, and the holding region is between times t3 and t4.

First, before entering the injection filling process, the stock pressure and mold clamping operations of the injection accumulator 14 and the pressure increase accumulator 15 are completed. Then, the molten aluminum melted in the high-temperature melting furnace is drawn up with a ladle or the like and poured into the sleeve. Thereafter, the injection filling process is started promptly so as not to lower the temperature of the molten metal.
At the start of the injection filling process, from the state where all the valves are turned off (demagnetized state), the b solenoid of the low speed forward / reverse switching valve 20 is turned on (excited), and the flow control valve 16 is connected to the rod chamber 10R and the tank 24. Open a certain amount in the direction of communication. In the first low-speed injection region, the discharge amount from the hydraulic pressure supply device 22 is adjusted so that a desired injection speed (about 0.2 to 0.5 m / sec) is obtained.
The low-speed injection region can be controlled by the discharge amount from the hydraulic pressure supply device 22, but the supply of hydraulic oil from the hydraulic pressure supply device 22 is stopped, the injection switching valve 18 is opened, and the flow rate control valve 16 is slightly opened. It is also possible to control at low speed.

  When it is detected that the injection position speed sensor 26 has reached the high-speed injection switching position (t1), the injection switching valve 18 is instantaneously opened, and the high-pressure hydraulic fluid accumulated in the injection accumulator 14 is supplied to the injection cylinder 10. Supply to the head chamber 10H at a stretch. At this time, it is necessary to instantaneously accelerate and stabilize from a low speed to a high speed of 4 to 5 m / sec. This is performed by adjusting the opening degree of the flow control valve 16 and performing feedback control by meter-out. However, the constant opening degree of the servo valve 16 in the low-speed injection region is set to an opening degree that is approximately the set speed in the high-speed region. In this case, the opening degree control of the flow control valve 16 after switching becomes easy. In the high-speed injection region, the plunger tip 7 is advanced at a high speed, and is filled in a short time before the molten metal begins to solidify in the cavity.

When it is detected that the mold cavity is filled with the molten metal and the molten metal pressure rises and the measured value of the radiant power reaches the switching force (Pm ′), the process is switched to the pressure increase holding process (region) (t2). The switching timing may be position switching performed when the set switching position is reached. FIG. 4 shows a state of switching by pressure, and switching to the boosting holding process is performed at the moment when the set switching pressure (Pm ′) is reached while monitoring the measured value of the radiation output by the pressure sensor or the load cell.
At the time of switching, the injection switching valve 18 is closed and the pressure increase switching valve 19 is opened. Then, the high pressure hydraulic oil accumulated in the pressure increasing accumulator 15 flows into the head chamber of the injection cylinder. At this time, a sudden pressure increase causes the generation of burrs, and if it is slow, a cast hole is generated. Therefore, the throttle amount of the throttle valve 21 is adjusted in advance so as to increase the pressure in an appropriate pressure increase time. Then, when the set holding force (Pm) is approached, the opening degree of the flow control valve 16 is adjusted, and control is performed so that the shot output becomes the holding force (Pm) (t3). When the holding region is reached, the flow control valve 16 is almost closed, and the hydraulic fluid is fed into the head chamber as much as the molten metal solidifies and contracts and the piston 12 of the injection cylinder advances to maintain the holding force (Pm). .

When the pressure increase holding time is completed (t4), the flow control valve 16 is completely closed, and the pressure increase switching valve 19 and the low speed forward / reverse switching valve 20 are also closed.
Thereafter, when the cooling time ends, the flow rate control valve 16 is opened to the tank side by a certain amount in conjunction with the mold opening operation, and the b solenoid of the low speed forward / reverse switching valve 20 is excited to advance the piston rod 12 and the plunger. Protruding the product from the fixed mold.

Subsequently, in order to retract (return) the piston 12 to the injection start position, the flow control valve 16 is opened to the hydraulic pressure supply device 22 side (retreat side), and the a solenoid of the low speed forward / reverse switching valve 20 is excited. When the piston 12 reaches the injection start position, all the valves are closed.
Thereafter, the injection accumulator 14 and the pressure-increasing accumulator 15 are subjected to livestock pressure to prepare for the next pouring step and injection filling step.

When the piston 12 is retracted, the spool 35 of the flow control valve 16 is moved (opened) to the mechanical movement limit (reverse movement limit) on the left side in FIG. At this time, in the controller, the detected position of the encoder 34 is compared with the stored origin position at the time of setting. If the amount of deviation between the detected position and the stored origin position is greater than or equal to the allowable value, it is determined that there is an abnormality, a warning message is displayed on the display device, and the operator is notified of the abnormality of the flow control valve 16. An operator who knows the abnormality can stop the occurrence of defective products by stopping the casting operation. Since the check of the spool origin position is performed when the piston moves backward, it can be performed every cycle, and the casting of defective products can be minimized. Further, the warning to the operator may be given by sound with a buzzer or the like.
Then, after the operator retightens the coupling or replaces the encoder to remove the abnormality, the casting operation is started again.

  As described above, in the present invention, it is possible to check the abnormality of the flow control valve every cycle and notify the operator, so even if an abnormality occurs, the casting process can be stopped immediately, and defective products can be cast. Never continue.

  The above-described embodiment is an example of the present invention, and the present invention is not limited by the embodiment, but is defined only by matters described in the claims, and other embodiments than the above are also possible. It can be implemented.

  It can be used in production plants that cast aluminum products using a die casting machine, and can contribute to improving the yield rate and productivity of cast products.

1 fixed platen 2 movable platen 3 fixed mold 4 movable mold 5 cavity
6 Sleeve 7 Plunger tip 8 Plunger rod 9 Injection coupling 10 Injection cylinder 10H Head chamber 10R Rod chamber 12 Piston 13 Cylinder body 14 Injection accumulator 15 Pressure increase accumulator 16 Flow control valve (servo valve)
DESCRIPTION OF SYMBOLS 17 Gas bottle 18 Injection switching valve 19 Pressure increase switching valve 20 Low speed forward / reverse switching valve 21 Throttle valve 22 Hydraulic supply device 23 Check valve 24 Oil tank 26 Injection position speed sensor 30 Flow control valve main body 30a Reverse side end face 30b Tank side small diameter part 30c Hydraulic supply side small diameter portion 31 Rotating linear motion conversion device 32 Coupling device 33 Servo motor 34 Encoder 35 Spool 35a Tank side spool large diameter portion 35b Hydraulic supply side spool large diameter portion 35c Spool left end face 41 Tank connection port 42 Cylinder connection port 43 Hydraulic supply device connection port 45 Hydraulic supply side large diameter portion 46 Cylinder side large diameter portion 47 Tank side large diameter portion 51 Connecting rod 52 Guide bush fixing plate 53 Guide bush 54 Conversion device case 56 Ball screw nut 57 Ball screw shaft 58 Bearing 59 Holding nut 60 Coupling case 62 Coupling 100 Die casting machine (casting equipment)
101 Mold device 102 Injection device

Claims (2)

A mold for casting the product;
A plunger for filling the mold cavity with molten metal;
An injection cylinder having a piston connected to the plunger;
A flow control valve capable of adjusting the flow rate of hydraulic oil flowing into the injection cylinder or the flow rate of hydraulic oil flowing out of the injection cylinder by the operation of the spool and controlling the operating speed or pressure of the piston;
A servomotor that is provided in the flow rate control valve and that can adjust the position of the spool via a mechanism that converts rotational motion into linear motion;
An encoder that is provided in the servo motor and that can detect the position of the spool based on the amount of rotation of the rotation shaft of the servo motor;
In the die casting machine equipped with
In each casting cycle, the spool of the flow rate control valve is moved to the mechanical movement limit, and the position detected by the encoder at that time is compared with a preset origin position, and the deviation amount exceeds the allowable range. In this case, it is determined that the flow control valve is abnormal and a warning is issued. The flow control valve is connected to the rod chamber of the injection cylinder and the flow path,
The flow rate control valve according to claim 1, wherein when the plunger and the piston are moved backward, the spool is moved to a mechanical movement limit, and an abnormality is determined and a warning is issued from a detection position of the encoder at that time. Anomaly detection method.

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