TWI579129B - Clamping device - Google Patents

Description

Molding device

The present invention relates to a mold clamping device for a press forming device, an injection molding device, a die casting device, and the like, and more particularly to a mold clamping device having a plurality of servo motors.

The inventors conducted research on keeping the bottom surface of the upper mold horizontal by a mold clamping device that drives a link shaft by a plurality of servo motors. If there are multiple servo motors, a plurality of sensors must be used, and what signals are measured by the sensors, so that the signals are combined is the problem.

Hereinafter, the related prior art is shown. Patent Document 1 (JP2006-75864A) describes a four-axis mold clamping device that controls four servo motors by respective encoders and corrects the delay with respect to the other axes. However, since a link shaft or the like is interposed between the servo motor and the mold, there is an error between the signal of the encoder and the height of the bottom surface of the mold. Further, if the control is performed such that the delay is eliminated, the other servo motors are controlled so as to match the most advanced servo motor, and the load of the other servo motors that are delayed is increased.

In Patent Document 2 (JP2007-283332A), the height of the upper mold is monitored by a line sensor and fed back to the servo motor. However, the position to be monitored is the base of the upper mold, or the link shaft or the like. This position is spaced from the bottom surface of the upper mold and is not fixed due to thermal deformation of the mold or the like.

An object of the present invention is to use a plurality of servo motors to move a moving mold while maintaining a posture.

The present invention is constructed as follows. That is, in the mold clamping device, a plurality of link shafts are mounted on the moving mold, a servo motor is disposed on each of the link shafts, and movement is performed in contact with the fixed mold by a plurality of servo motors. The mold produces a movement. Further, the mold clamping device is provided with a plurality of interval sensors and control means. A plurality of spaced sensors are provided in the same number as the number of the connecting rod shafts, and the distance between the moving mold and the fixed mold is measured. The control means generates a first control amount common to the plurality of servo motors in such a manner as to eliminate the error of the target position of the moving mold along the link shaft and the actual position of the moving mold from the signals of the plurality of spaced sensors. The control means generates a second control amount of each servo motor from a plurality of signals of the interval sensors to eliminate the tilt of the moving mold with respect to the link shaft. Further, the control means generates the control amount of each servo motor by adding the first control amount to the second control amount of each sensor.

The actual position of the moving mold is, for example, the center position of the moving mold, and the interval sensor is a gap between the moving mold and the fixed mold, and does not include an encoder, or a sensor that measures the position of the moving mold without using a fixed mold. Wait. The first control amount is, for example, an equation for moving the abutting surface of the mold to the fixed mold, and is more simply determined by the average value of the signals of the plurality of spaced sensors to generate a moving mold along the connecting rod axis. Actual location. The second control amount is obtained by, for example, determining the inclination of the moving mold with respect to the link shaft based on the equation with respect to the abutting surface of the moving mold, and more simply to eliminate the unevenness of the signals of the plurality of spaced sensors. By the first control amount and The second control amount is added, and the control amount of each servo motor can be obtained. Thereby, the movable mold can be moved in accordance with the movement of the target position while maintaining the posture of the moving mold, that is, while maintaining the abutting surface of the moving mold perpendicular to the link axis.

The present invention is preferably further configured in the following manner. That is, the control means generates the first control amount in such a manner as to eliminate the error of the target position of the moving mold along the link shaft and the average value of the interval determined by the plurality of interval sensors. The control means generates the second control amount in such a manner as to eliminate the deviation between the average value and the interval obtained by the individual interval sensors.

The average of the intervals determined by the interval sensor indicates the center position of the abutting surface in the moving mold. Therefore, by comparing the value with the target position, the first control amount for matching the position of the moving mold with the target position can be obtained. Further, by generating the second control amount so as to eliminate the deviation from the average value, that is, the deviation between the measured values of the intervals between the sensors, the posture of the moving mold can be maintained.

The average value for generating the first control amount is not limited to the arithmetic mean, and may be a weighted average, and the center position of the moving mold or the like is obtained based on the signal of the interval sensor. The deviation for generating the second control amount is not limited to the deviation from the average value, and may be a deviation between the signals of the interval sensor or the like.

The present invention is preferably further configured in the following manner. That is, the interval sensor is configured to include a wired sensor and an abutting member. The line sensor has a magnetic rod, a sensing head, a stopper, and an elastic body. The magnetic rod is magnetically marked and moves forward and backward. The sensing head measures the advance and retreat position of the magnetic rod. The stop member defines the movement limit of the magnetic rod. The elastic system adds a potential energy to the magnetic rod toward the side of the stopper. The abutment member abuts against the magnetic rod to cause the magnetic rod to move. Moreover, the wire sensor is placed on one side of the moving mold and the fixed mold, and the abutting member is moved to the mold and solid. The other side of the mold is fixed and mounted in such a manner as to face each other.

In this way, the distance between the moving mold and the fixed mold can be accurately measured, and the line sensor can use a shorter measuring range but higher resolution.

The present invention is preferably further configured in the following manner. That is, in the mold clamping device, a remote type line sensor which measures the position of the moving mold without depending on the fixed mold, or an encoder of each servo motor is further provided. The interval sensor is freely measurable when the distance between the moving mold and the fixed mold is below a predetermined value. In the case where the distance between the moving mold and the fixed mold exceeds a predetermined value, a plurality of servo motors are controlled by a remote line sensor or encoder. On the other hand, in the case where the distance between the moving mold and the fixed mold is less than or equal to a predetermined value, on the one hand, the control by the remote line sensor or the encoder is directed toward the plurality of spaced sensors. The control is performed to change the weight of the control performed by the interval sensor in a continuous manner, and on the one hand, the control of the plurality of servo motors is switched. Further, for example, only one remote type line sensor may be provided.

In this way, until the moving mold approaches the fixed mold, it is controlled by the remote line sensor or the encoder, and if the moving mold is close to the fixed mold, it can be switched to the control of the interval sensor. Moreover, the switching of the control can be performed continuously and smoothly.

In particular, even if the signal between the encoder or the remote line sensor and the interval sensor is inconsistent, there is no excessive control.

The present invention is further preferably configured in the following manner. That is, before the moving mold comes into contact with the fixed mold, the target position of the moving mold is temporarily fixed, and the control by the second control amount is continued. Therefore, before the moving mold comes into contact with the fixed mold, the abutting surface of the moving mold is relatively connected. The shaft is indeed a right angle. Next, the target position of the moving mold is changed in such a manner that the moving mold comes into contact with the fixed mold. For example, the mold clamping device is an injection molding device that starts filling the resin when the target position of the moving mold is temporarily fixed. In this way, the molding by the compression molding method can be accurately performed.

The present invention is preferably further configured in the following manner. That is, in the mold clamping device, the gain with respect to the second control amount is larger than the gain with respect to the first control amount. Further, it is preferable that the plurality of interval sensors of the present invention are configured to be disposed at positions corresponding to the respective link shafts.

The present invention is constructed in the following manner on the other side. That is, in the control method of the mold clamping device, a plurality of link shafts are mounted on the moving mold, a servo motor is disposed on each of the link shafts, and contact is made with the fixed mold by a plurality of servo motors. The way the moving mold moves. Further, the control method of the mold clamping device includes a measurement step, a first step, a second step, and an addition step. In the measuring step, the distance between the moving mold and the fixed mold is measured by a plurality of spaced sensors. In the first step, the signals from the plurality of interval sensors are caused to generate a common servo motor in a manner that eliminates an error between the target position of the moving mold along the link shaft and the actual position of the moving mold. The first control amount. In the second step, the control means causes the second control amount of each servo motor to cancel the inclination of the moving mold with respect to the link shaft from the signals of the plurality of interval sensors. In the adding step, by adding the first control amount and the second control amount of each sensor, the control means generates the control amount of each servo motor.

The moving mold can be moved in accordance with the movement of the target position while maintaining the posture of the moving mold.

2‧‧‧Injection molding device

4‧‧‧Upper mold (moving mold)

6‧‧‧Lower mold (fixed mold)

8, 10‧‧‧ internal mold

11‧‧‧Marketing

12‧‧‧Connector shaft

14‧‧‧ crank mechanism

18‧‧‧Injection device

20‧‧‧Control Department

24‧‧‧ reference plate (abutment member)

30, 32, 38‧‧ ‧ adders

34, 36‧‧‧Differentiator

40‧‧‧Serval

42‧‧‧Metal housing

44‧‧‧Magnetic rod

45‧‧‧ reference board

48‧‧‧ Sense head

49‧‧‧ Elastomers

52‧‧‧ magnetic body

53‧‧‧Non-magnetic body

54‧‧‧Sliding members

55‧‧‧Connecting components

56‧‧‧stops

57‧‧‧ trench

E1, E2, E3, E4‧‧ ‧ encoder

M1, M2, M3, M4‧‧‧ servo motor

S1, S2, S3, S4‧‧‧ line sexy sensor

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram showing an injection molding apparatus of an embodiment.

Fig. 2 is a bottom plan view showing the bottom surface of the upper mold in the embodiment.

Fig. 3 is a view showing the mounting line sensor in the embodiment.

Figure 4 is a cross-sectional view of the line sensor in the embodiment.

Fig. 5 is a block diagram showing a control system of a servo motor in the embodiment.

Figure 6 is a waveform diagram of an embodiment, 1) showing the weight of the encoder signal and the line sensor signal, and 2) indicating the angular velocity of the motor.

Fig. 7 is a flow chart showing the control algorithm of the servo motor in the embodiment.

Hereinafter, preferred embodiments for carrying out the invention are shown. The scope of the present invention should be determined based on the description of the scope of the claims, the description of the specification and the well-known technology in the field, and the understanding of the ordinary skill in the art to which the invention belongs.

[Examples]

The embodiment and its actions are shown in Figs. 1 to 7 . Further, although the embodiment has been described mainly with the configuration of the mold clamping device (the injection molding device 2), it may be replaced with the description of the control method of the mold clamping device. Fig. 1 is a view showing an injection molding apparatus 2 of an embodiment in which an upper mold (moving mold) 4 is a mold which is moved up and down by, for example, four link shafts (mold rods) 12, and is provided to inject synthetic resin by injection molding. Internal mold 8. An inner mold 10 for injecting a synthetic resin is provided in the lower mold (fixed mold) 6. The upper mold 4 is guided by, for example, four guide pins 11, and is moved up and down via the four crankshafts 14 and the four servomotors M1 to M4 via the four link shafts 12. Further, an injection device 18 including a screw pump, a plunger, and the like is connected to the lower mold 6, and synthetic resin is injected into the chamber between the molds 8 and 10. Furthermore, in addition to the injection device 18, it can also be used as a press forming device or even as a die casting device. Instead of the crank mechanism 14 or the crank mechanism 14 or the like, the servo motor M1 to M4 may be driven by the ball screw. Further, the movable mold 4 can be horizontally moved toward the fixed mold 6 by the link shaft 12.

The control unit 20 feedback-controls the servo motors M1 to M4 by signals from the encoder and the line sensor (interval sensor) S1 to S4. The wired sensors S1 to S4 are fixed to the upper portion of the lower mold 6, and the distance from the reference plate (contact member) 24 fixed to the lower portion of the upper mold 4 is measured. The combination of the line sensors S1 to S4 and the reference plate 24 is provided in each of the servo motors M1 to M4, and in the embodiment, one set is provided around each of the molds 4 and 6. The line sensors S1 to S4 and the reference plate 24 are fixed to the vicinity of the opposing portions of the molds 4 and 6, and the actual intervals between the molds 4 and 6 are measured by the line sensors S1 to S4. Further, the line sensors S1 to S4 are disposed in the vicinity of the respective link shafts 12 so as to correspond to the respective link shafts 12, respectively.

2 shows the bottom surface of the upper mold 4, O is the center of the upper mold 4, has a guide pin 11 on four sides, and a reference plate 24 is attached to the side surface of the upper mold 4. Furthermore, the signals from the line sensor corresponding to the respective reference plates 24 are set to a to d.

Fig. 3 shows the arrangement of the line sensors S1 to S4 and the like. The reference plate 24 and the line sensors S1 to S4 are disposed in the vicinity of the opposing portions of the molds 4 and 6. Further, the line sensores S1 to S4 may be disposed on the upper mold 4 side, and the reference plate 24 may be disposed on the lower mold 6 side.

4 is a cross section of the line sensor 50, the component symbol 42 is a metal case, and the movable magnetic bar 44 is provided with a magnetic body 52 and a non-magnetic body 53. The magnetic mark is formed and penetrates into the sensing head 48 having a plurality of coils. A sliding member 54 that slides along the groove 57 of the casing 51 and the magnetic rod 44 are fixed to the reference plate 45, and the reference plate 45, the magnetic rod 44, and the sliding member 54 are integrally slid to the left and right in FIG.

The magnetic rod 44 and the sliding member 54 are coupled by the connecting member 55, and the potential energy is added to the side of the reference plate 45 on the left side of the drawing by the elastic body 49. Further, until the reference plate 45 is pressed from the upper mold 4 side, the connection member 55 is positioned by the stopper 56 by the additional potential of the elastic body 49. The stroke (measurement range) of the magnetic rod 44 is, for example, about 10 mm. The line sensor S1 to S4 are corrected such that the height is set to 0 or the like when the upper and lower molds 4 and 6 are in contact.

Although the line sensors S1 to S4 have a measurement range on the negative side of the mold clamping position, since the upper mold 4 is stopped at the mold clamping position, the range of the negative side is not measured. Moreover, the position of the position of the upper mold 4 cannot be detected by the line sensor S1 to S4, and the signal of the encoders E1 to E4 or the remote line type of the position of the link shaft 12 is not shown. The signal of the detector controls the servo motors M1~M4.

The control system of the servo motors M1 to M4 is shown in FIG. The component symbol 30 is an adder that multiplies the signals from the encoders E1 to E4 by weights, and multiplies the signals a to d from the line sensors S1 to S4 by weights (1-w) and adds them. The signals from the four adders 30 are input to the adder 32, and an average value thereof is output, which is the height of the center O of the bottom surface of the upper mold 4. The differencer 34 determines the difference between the target height and the height of the center O obtained by the adder 32, and sets the difference as the first control amount. Furthermore, the average value obtained by the adder 32 is not limited to the arithmetic mean, as long as it is determined by the four sensors and is suitable as the height of the center O, for example, four senses. The weighted average of the signals of the detector can be.

The deviation of the height of the center O from the signals a to d of the respective line sensors S1 to S4 indicates the inclination from the bottom surface of the mold 4 above the horizontal plane. Therefore, in order to eliminate the change, the second control amount is generated by the differentiator 36. When the first control amount and the second control amount are added by the adder 38, the control amounts of the servo motors M1 to M4 can be obtained. Preferably, the gain with respect to the second control amount is larger than the gain with respect to the first control amount, and the bottom surface of the upper mold 4 is kept horizontal, and the height of the upper mold is made to coincide with the target height.

The servo mechanism 40 controls the servo motors M1 to M4 by setting the control amount input from the adder 38 to the position control amount and setting the rate of change of the signals of the encoders E1 to E4 to the control amount of the speed circuit.

It is also possible to determine the equation of the bottom surface of the upper mold 4 instead of using the deviation between the height of the center O of the upper mold 4 and the height from the center O to eliminate the slope of the bottom surface and to control the center O to fall in a predetermined mode. . Since there are four sensors (the same number as the link shaft 12) in the embodiment, the plane calculation can be obtained more accurately than the case where the sensor is three. However, the control of the bottom surface is used, or the deviation between the height of the center O and the height from the center O is substantially the same.

Fig. 6 shows the weight w and the average angular velocity of the four servo motors. The range of the interval between the upper mold 4 and the lower mold 6 cannot be measured by the line sensor S1 to S4, and the weight w of the signal to the encoder E1 to E4 or the remote line sensor is 1, and the line is When the sensor S1~S4 obtains the signal, the w is slowly approached to 0, and the control from the encoder E1~E4 or the remote line sensor is switched to the line sensor S1~S4. Control.

When the interval between the upper and lower dies 4 and 6 reaches a predetermined value such as 100 μm, the target height is temporarily fixed. At this time, by setting the deviation of the signal between the line sensors S1 to S4 to 0, the control for using the second control amount for leveling the bottom surface of the upper mold 4 is continued. Then, during the fixing of the target height, the filling (ejection) of the resin is started, and the air is ejected from the chamber between the dies 8, 10. Thereby, even if it is a thin chamber, the air can be surely driven out. While continuing the filling of the resin, the upper mold is further lowered until the target height becomes 0 (the upper and lower molds 4 and 6 are in contact). Further, during this period, if a predetermined amount of resin is filled, the filling is stopped. In this way, the upper mold 4 can be lowered while keeping the bottom surface horizontal.

Fig. 7 shows the control performed by the line sensors S1 to S4. In step 71, the average value f of the signals of the four line sensors is obtained. Control signals g1 to g4 are generated in step 72 in such a manner as to eliminate the deviation from the average value f. Further, in step 73, the control signal h is generated in such a manner as to eliminate the error between the target height z and the signal f. In step 74, the servo motor M1 is controlled by (h+g1), the servo motor M2 is controlled by (h+g2), the servo motor M3 is controlled by (h+g3), and controlled by (h+g4). Servo motor M4. Then, the speed loop of each servo motor is controlled by the signals of the encoders E1 to E4 (step 75).

2‧‧‧Injection molding device

4‧‧‧Upper mold (moving mold)

6‧‧‧Lower mold (fixed mold)

8, 10‧‧‧ internal mold

11‧‧‧Marketing

12‧‧‧Connector shaft

14‧‧‧ crank mechanism

18‧‧‧Injection device

20‧‧‧Control Department

24‧‧‧ reference plate (abutment member)

M1, M3‧‧‧ servo motor

S1, S2, S3‧‧‧ line sexy detector

Claims (9)

A mold clamping device is provided with a plurality of link shafts mounted on a moving mold, a servo motor is disposed on each of the link shafts, and the movable mold is moved in contact with the fixed mold by a plurality of servo motors The method is characterized in that: a plurality of interval sensors are provided, and the distance between the moving mold and the fixed mold is measured, and the number is the same as the number of the connecting rod shafts; and the control means is different from the plurality of intervals The signal of the detector is used to eliminate the error of the moving position of the mold along the connecting rod axis and the actual position of the moving mold, and generates a first control amount common to the plurality of servo motors, and eliminates the relative to the connecting rod shaft The second control amount of each servo motor is generated by moving the tilt of the mold, and the control amount of each servo motor is generated by adding the first control amount to the second control amount of each sensor. The mold clamping device of claim 1, wherein the control means is for eliminating an error of a target position of the moving mold along the connecting rod axis and an average value of the interval determined by the plurality of spaced sensors. The method generates the first control amount, and generates the second control amount so as to eliminate the deviation between the average value and the interval obtained by the individual interval sensors. The mold clamping device of claim 1, wherein the interval sensor is configured to include: a line sensor having: a magnetic rod having a magnetic mark and being retractable, and measuring a forward and backward position of the magnetic rod a sensing head, a stopper for defining a movement limit of the magnetic rod, and an elastic body that adds a potential energy to the magnetic rod toward the stopper; and an abutting member that abuts against the magnetic rod to move the magnetic rod And The wire sensor is mounted on one side of the movable mold and the fixed mold, and the abutting member is opposed to each other on the other side of the movable mold and the fixed mold. The mold clamping device of claim 1, wherein a remote type line sensor that measures the position of the moving mold without depending on the fixed mold, or an encoder of each servo motor, is provided. The measuring device is freely measurable at a distance between the moving mold and the fixed mold, and the control means is configured to: when the distance between the moving mold and the fixed mold exceeds a predetermined value, the remote type line is sexy. The detector or the encoder controls a plurality of servo motors, and the control is performed by a remote line sensor or encoder when the distance between the moving mold and the fixed mold is below a predetermined value. The control of the plurality of servo motors is switched on the one hand by changing the weight of the control by the interval sensor in a continuous manner by the control performed by the plurality of interval sensors. The mold clamping device according to any one of claims 1 to 4, wherein the control means is configured to temporarily fix a target position of the movable mold before the moving mold comes into contact with the fixed mold, and continue to borrow Controlled by the second control amount, the target position of the moving mold is changed in such a manner that the moving mold comes into contact with the fixed mold. The mold clamping device of claim 5, wherein the mold clamping device is an injection molding device, and is configured to start filling the resin when the target position of the moving mold is temporarily fixed. For example, the clamping device of claim 1 of the patent scope, wherein The gain with respect to the second control amount is greater than the gain with respect to the first control amount. The mold clamping device of claim 1, wherein the plurality of interval sensors are respectively disposed at positions corresponding to the respective link shafts. A method for controlling a mold clamping device, wherein the mold clamping device is provided with a plurality of link shafts mounted on a moving mold, a servo motor is disposed on each of the link shafts, and a plurality of servo motors are used to make contact with the fixed mold The method for controlling the moving mold is characterized in that: the control method of the mold clamping device is characterized by: a measuring step of measuring a distance between the moving mold and the fixed mold by a plurality of interval sensors; the first step, the plural step The signal of the interval sensor causes the control means to generate a first control amount common to the plurality of servo motors in such a manner as to eliminate an error of the target position of the moving mold along the link shaft and the actual position of the moving mold; a signal from a plurality of spaced sensors, the control means causing a second control amount of each servo motor to eliminate tilt of the moving mold relative to the link shaft; and an adding step by the first The control amount is added to the second control amount of each sensor, and the control means generates the control amount of each servo motor.