TWI690402B - Mold clamping device and method - Google Patents

Abstract

The object of the present invention is to minimize the influence of the deformation of the mold due to stress, measure the relative position between the molds with high accuracy and smoothly, and smoothly switch the sensor used during the mold clamping stroke .

The servo motor is feedback controlled by the encoder signal to move the mold. The distance between the molds is measured by a sensor for mold installation that is fixed near the opposite part of the mold, and the servo motor is controlled by the signal of the encoder in the area beyond the measurement range of the sensor, and In the closest interval, the servo motor is controlled by the signal from the sensor for mold installation. Then when the mold enters the measurement range of the sensor for mold installation, the control of the servo motor is switched from the control according to the signal of the encoder in a continuous manner to the control according to the signal of the sensor for mold installation.

Description

Mold clamping device and method

The invention relates to the mold clamping technology of molds used for press molding, injection molding, die casting molding, etc., and particularly relates to the monitoring or position control of the mold position when the opposite mold is closest.

As a sensor that measures the position of a moving body, a wired sensor is known. In the linear sensor, a magnetic mark arranged with a magnetic body and a non-magnetic body, or a magnetic mark arranged with magnets with different polarities, and a sensing head provided with a plurality of coils are provided. If the position of the sensor head on the magnetic mark changes, the magnetic interaction of the magnetic mark and the coil will change, and the position of the sensor head relative to the magnetic mark can be obtained.

In mold clamping devices (Mold Clamping Apparatus) that use molds such as compression molding devices, injection molding devices, and die casting molding devices, there is also a requirement to accurately monitor or control the relative position between the molds up and down or left and right. Furthermore, in Patent Document 1 (JP2007-283332A), a linear sensor is used to monitor the position of the base of the upper mold and feed back to the servo motor that drives the upper mold. However, the monitored position is the base of the upper mold or the position of the link shaft as a sliding mechanism. Due to the stress caused by the contact of the upper and lower molds, the thermal deformation of the mold, etc., the distance between this position and the lower end of the upper mold is not fixed. Therefore, even if the position of the upper mold is monitored at the installation position of the crank or the connecting rod shaft, etc., the position of the upper mold relative to the lower mold cannot be correctly controlled, in other words, the interval between the upper and lower molds cannot be correctly controlled.

The inventor further noticed that the resolution of a linear sensor with a generally longer measurement range is lower. Moreover, it is noted that the movement of the mold itself must be monitored and controlled, so even if the position of the sliding mechanism is monitored, the movement of the mold is only indirectly monitored. Therefore, the inventors discussed using a linear sensor with a short measuring range, and switching control between another sensor such as an encoder of a servo motor and a linear sensor directly mounted on the mold. Among them, when the control is discontinuously switched between the other sensors and the linear sensor, the slight difference in the detection value between the sensors will be fed back to the control unit as a large control error, Servo motor control becomes unstable.

[Prior Technical Literature] [Patent Literature]

[Patent Literature 1] JP2007-283332A

The object of the present invention is to: 1) by minimizing the influence of the stress caused by the contact of the mold, the temperature change of the mold, etc., the relative position between the opposing molds can be measured accurately and with high resolution; and 2) On the way of the mold stroke, smoothly switch the sensor used.

The mold clamping device of the present invention includes: at least a pair of opposed molds; a servo motor that causes at least one of the molds to move through the connecting rod shaft; and a servo motor encoder signal or monitoring of the connecting rod shaft position The signal of the long-range linear sensor is used as the control input value, and the control part of the feedback control of the servo motor; the special feature of the mold clamping device The feature is that it is configured to be provided with a die mounting sensor which is directly fixed to one of the dies near the opposing part of the die and used to measure the distance between the opposing dies The interval, and the interval between the molds is monitored by the signal of the sensor for mold installation. The term “fixed directly to the mold” means to be fixed to the outer periphery of the mold and to the interior of the mold. Mold clamping devices are, for example, injection molding devices, compression molding devices, and die casting molding devices. Instead of using an encoder to monitor the rotation of the servo motor shaft, a long-range linear sensor is used to monitor the position of the link shaft and the like.

The present invention measures the distance between the opposite mold, that is, the position of the other mold based on one mold by using a sensor directly fixed to the mold at the position of the mold. Therefore, unlike the encoder of the servo motor and the linear sensor that monitors the position of the connecting rod shaft, the interval between the molds can be accurately measured. Since the measurement is performed at the position of the mold, even if the mold is deformed due to the stress between the molds, or the mold is thermally deformed due to the temperature change, or the heat generated by the mold clamping process, the interval between the molds can be accurately measured. In addition, as long as the sensor can measure the interval near the closest section of the mold, a high-resolution sensor with a short measurement range can be used. Furthermore, if the interval between the molds is measured, it can be fed back to the servo motor, or it can be judged whether maintenance of the mold clamping device is required.

Preferably, the mold clamping device is provided with switching means for continuously switching the control input value between the signal of the encoder or the signal of the long-range linear sensor and the signal of the sensor for mold installation. And the structure is: in the mold clamping area near the mold clamping position, the servo motor is controlled by the signal of the mold installation sensor; in the remote area away from the mold clamping position, by the encoder signal or long range The signal of the linear sensor controls the servo motor; and the intermediate area between the remote area and the mold clamping area is edited The control input value is switched in a continuous manner between the signal of the encoder or the signal of the long-range linear sensor and the signal of the sensor for mold installation.

In addition, the mold clamping method of the present invention is based on the signal of the encoder of the servo motor or the signal of the long-range linear sensor that monitors the position of the connecting rod shaft. The mold clamping method in which at least one side moves is characterized in that, by means of a sensor for mold installation that is directly fixed to the mold of one side near the opposing portion of the mold, the interval between the molds opposed to each other is monitored and used for mold installation In the area outside the measurement range of the sensor, the servo motor is controlled by the signal of the encoder or the signal of the long-range linear sensor that monitors the position of the link shaft; in the closest section of the mold, by the mold installation The signal of the sensor controls the servo motor; and when the mold enters the measurement range of the sensor for mold installation, the servo motor is controlled according to the signal of the encoder or the long-range linearity of the position of the monitoring link shaft. The control of the signal of the detector is switched to the control of the signal of the sensor for mold installation in a continuous manner.

In the case where the signal of the sensor for mold installation is used to feed back to the servo motor, the short measurement range becomes a problem. Therefore, in the area outside the measurement range of the mold mounting sensor, the signal from the encoder of the servo motor is used as the control input value, and between the signal from the mold mounting sensor and the signal from the encoder, etc. Continuously switch the control input value. In this way, even if the control input value is switched, there will be no control confusion. In addition, the control of returning the molds away from each other has no effect on the accuracy of mold clamping. Therefore, the weight w may be fixed to 1 at the time of regression, for example. In this specification, the description about the mold clamping device can also be directly applied to the mold clamping method.

Preferably, the switching means converts the signal P1 of the encoder or the signal of the long-range linear sensor that monitors the position of the connecting rod shaft and the sensor of the mold installation by a variable weight w of 0 or more and 1 or less The signal P2 is converted to the control input value P3 by using P3=P1‧w+P2‧(1-w), and when it exceeds the measurement range of the mold mounting sensor, it is w=1, when the mold is closest to In the interval, w=0, and when the mold enters the measurement range of the mold mounting sensor, the weight w is continuously changed from 1 to 0. In this way, the control input value can be easily and smoothly switched between the encoder and the like and the mold mounting sensor.

Preferably, the control unit is provided with a position control means for converting the error between the command position and the control input value into a speed command, and an error between the speed command and the rate of change of the encoder signal per unit time, Speed control means converted to current command. In this way, since the speed control loop can be controlled by the signal of the encoder that can obtain the signal in a short period, even if it is assumed that the period from which the signal can be obtained from the sensor is long, the speed control can still be performed correctly.

In addition, it is preferable that the sensor for mold mounting is a linear sensor, which has: a magnetic rod provided with a magnetic mark, and advancing and retreating by the opposing mold; a sense of measuring the advancing and retreating position of the magnetic rod Probe; stopper that determines the movement limit of the magnetic rod toward the connecting rod shaft side; and an elastic body that urges the magnetic rod toward the connecting rod shaft side. It is constituted as follows: the opposing mold is provided with an abutment member that abuts on the magnetic rod to move the magnetic rod along the connecting rod axis; and the elastic body is used to preliminarily set the position fixed by the stopper The magnetic rod applies a force toward the connecting rod shaft side, thereby eliminating the vibration of the magnetic rod caused by contact with the contact member. In this way, the amplitude of the sensor signal can be reduced, and the spacing between the molds can be accurately measured.

2‧‧‧Injection molding device

4‧‧‧ Upper mold

6‧‧‧ Lower mold

8‧‧‧Mobile mold

10‧‧‧Fixed mold

11‧‧‧Guide pin

12‧‧‧Link shaft

14‧‧‧Crank mechanism

16‧‧‧Servo motor

18‧‧‧ Injection device

20‧‧‧Control Department

22.50‧‧‧Linear sensor for mold installation

24‧‧‧Reference board of linear sensor for mold installation

26‧‧‧Strain gauge

30‧‧‧Command generator

31, 32‧‧‧ Differentiator

33, 34‧‧‧Amplifier

35‧‧‧Current amplifier

36‧‧‧Encoder

38, 40‧‧‧ adder

42、51‧‧‧case

44‧‧‧Magnetic rod

45‧‧‧Reference plate of magnetic rod

46, 47‧‧‧ Datum

48‧‧‧Sensor head

49‧‧‧Elastomer

49a, 49b‧‧‧stop

52‧‧‧Magnetic

53‧‧‧Non-magnetic body

54‧‧‧Sliding member

55‧‧‧Connecting member

56‧‧‧stop

57‧‧‧Groove

60, 62‧‧‧ track

70‧‧‧cavity

K _p ‧‧‧Control constant

K _V ‧‧‧Control constant

P‧‧‧ Lowest point

P0‧‧‧Position command

P1‧‧‧signal

P2‧‧‧Signal

P3‧‧‧Position signal

a, b‧‧‧ deceleration

v‧‧‧Speed signal

vo‧‧‧speed command

w‧‧‧ weight

FIG. 1 is a block diagram showing an injection molding apparatus of an embodiment.

FIG. 2 is a diagram showing a control unit of the servo motor of the embodiment.

Fig. 3 is a diagram showing a linear sensor of the embodiment.

4 is a waveform diagram of an embodiment, 1) shows the weight of the encoder signal and the linear sensor signal, 2) shows the angular velocity of the motor.

Fig. 5 is a vertical sectional view showing a linear sensor of the preferred embodiment.

Fig. 6 is an explanatory diagram showing vibration suppression of the linear sensor of the preferred embodiment.

Fig. 7 is a plan view showing the mounting of the linear sensor of the preferred embodiment to the lower mold.

8 is a characteristic diagram showing the position of the mold and the end position of the motor in the preferred embodiment.

9 is a characteristic diagram showing the position of the mold and the end position of the motor in the prior art example.

In the following, preferred embodiments for implementing the present invention are shown. The scope of the present invention should be determined based on the description of the scope of the patent application, with reference to the description of the specification and well-known technology in the field, and based on the understanding of those with ordinary knowledge in the technical field to which the present invention belongs.

[Example] [Basic embodiment]

Figures 1 to 4 show the basic embodiment and its characteristics. FIG. 1 shows an injection molding apparatus 2 of an embodiment. The upper mold 4 is a movable mold that moves up and down by a ram axis (die bar: die bar) 12 and is equipped with injection molding for injection Synthetic resin moving mold 8. A fixed mold 10 for injecting synthetic resin is installed on the fixed lower mold 6. The upper mold 4 is guided by, for example, four guide pins 11 and is moved up and down via a link shaft 12 by a crank mechanism 14 and a servo motor 16. In addition, the lower mold 6 An injection device 18 equipped with a screw pump, a plunger, etc. is connected to inject synthetic resin into the cavity between the molds 8 and 10. Moreover, the molds 4 and 6 may not be arranged up and down, but may be arranged to face each other. In addition to the injection device 18, a press molding device or a die casting molding device may be used. Instead of the crank mechanism 14, a toggle mechanism or the like may be used, or the crank mechanism 14 or the like may not be provided.

The control unit 20 feedback-controls the servo motor 16 based on signals from the encoder and the linear sensor 22 for mold mounting. A linear sensor 22 for mold mounting is fixed to the upper part of the lower mold 6 to measure the distance from the reference plate 24 as a contact member of the linear sensor for mold mounting fixed to the lower part of the upper mold 4. The combination of the linear sensor 22 for mold installation and the reference plate 24 may be, for example, one pair, two pairs, or four pairs. In the embodiment, one set is provided around each of the molds 4 and 6. The linear sensor 22 for mold installation and the reference plate 24 are fixed in the vicinity of the opposing parts of the molds 4 and 6, and the actual distance between the molds 4 and 6 is measured by the linear sensor 22 for mold installation. The strain gauge 26 corrects the signal of the linear sensor 22 for mold installation by detecting the strain caused by the contact between the molds 4 and 6, but the strain gauge 26 may not be provided.

FIG. 2 shows the control unit 20 of the servo motor 16. The command generator 30 outputs the position command P0 according to the operation pattern of the upper mold 4. Element symbols 31 and 32 are differentiators, 33 and 34 are amplifiers, 35 is a current amplifier, and the current amplifier 35 is controlled in such a manner that the drive current of the servo motor 16 matches the target value. The servo motor 16 includes an encoder 36, and feeds back to the differentiator 32 the amount of change of the encoder signal per unit time as a speed signal v. In addition, for example, the adder 38 averages the position signals of the four mold mounting linear sensors 22 and outputs the same to the adder 40. When there is only one linear sensor 22 for mold installation, the adder 38 is unnecessary. In addition, the signal of the linear sensor 22 for mold mounting is subtracted by the distance from the axis of the servo motor 16 to the reference plate 24 The amount of displacement is adjusted to match the signal of the encoder 36. The adder 40 performs weighted averaging of the signal from the encoder 36 and the signal from the adder 38 on the mold mounting linear sensor 22 side based on the variable weight w input from the command generator 30. The weight w is 0 or more and 1 or less. Set the weight of the signal P1 from the encoder 36 to w, and the weight of the signal P2 from the adder 38 to (1-w), from the formula (1) P3=P1‧w+P2‧(1-w) (1) The position signal P3 is obtained. In addition, in order to generate the weight w, any one of the signals P1, P2, P3 is input to the command generator 30, and the command generator 30 memorizes w with respect to the values of these signals.

The differentiator 31 outputs the difference between the position command P0 and the position signal P3 as a position error, and the amplifier 33 multiplies the position error by a control constant Kp and inputs it to the differentiator 32 as a speed command v0. The differentiator 32 outputs the difference between the speed command v0 and the speed signal v composed of the rate of change of the signal of the encoder 36 as a speed error, and the amplifier 34 multiplies the speed error by the control constant Kv and outputs it as a current command to the current amplifier 35. As mentioned above, the speed signal v from the encoder 36 is used in the speed control loop composed of the differentiator 32, the amplifier 34, etc., and the position control loop composed of the differentiator 31, amplifier 33, etc. is used The position signal P3 is generated in such a manner that the signal P1 of the encoder 36 and the signal P2 of the linear sensor 22 for mold mounting are smoothly switched by the adder 40. In addition, the signal of the strain gauge 26 indicates the stress generated by the contact of the upper and lower molds, and is input to the command generator 30 in order to correct the influence of the installation position of the linear sensor 22 for mold installation.

FIG. 3 shows the arrangement of the linear sensor 22 for mold mounting and the like. The reference plate 24 and the linear sensor 22 for mold mounting are arranged near the opposing parts of the molds 4 and 6. Moreover, the linear sensor 22 for mold mounting may be arranged on the upper mold 4 side, and the reference plate 24 may be arranged on the lower mold 6 side. The linear sensor 22 for mold installation is provided with a casing 42 and can be taken out up and down The magnetic rod 44 is freely provided, and the magnetic rod 44 is provided with a magnetic mark (not shown) from one cycle to a plurality of cycles. At the front end of the magnetic rod 44, the reference plate 45 of the magnetic rod is fixed, and the opposing surfaces of the reference plates 24, 45 are used as the reference planes 46, 47. The magnetic rod 44 can freely move into and out of the housing 42 upward and downward in FIG. 3, and is biased in the protruding direction in advance by the elastic body 49 and the stoppers 49a and 49b. The sensor head 48 detects the magnetic mark. An alternating current is applied to the coil of the sensor head 48 to detect the change in impedance caused by the interaction with the magnetic mark as a phase based on the magnetic mark. The magnetic rod 44 is provided with, for example, a magnetic mark within a range of about several mm in length. The magnetic mark is used to determine the measurement range of the linear sensor 22 for mold mounting. Although the linear sensor 22 for mold installation has a measuring range on the negative side of the mold clamping position, the upper mold stops at the mold clamping position and becomes a mechanical stop state. In addition, when the measurement range of the linear sensor 22 for mold installation is exceeded and the position of the upper mold cannot be detected, the signal of the encoder or the long-range linear sensor (not shown) for monitoring the position of the link shaft 12 is used. Signal to control the servo motor.

Figure 4 shows that the weight of the encoder signal is w, and the weight of the linear sensor signal is (1-w). When the linear sensor cannot detect the position of the upper mold, w is set to 1, and the weight w is set to 0 in the vicinity of the lowermost end of the stroke of the upper mold. When the linear sensor becomes capable of detecting the position of the upper mold, As shown in 1) of FIG. 4, the weight w is continuously changed from 1 toward 0. Therefore, in the interval where the signal of the encoder is used, the servo motor can be controlled by the rotation angle of the shaft of the servo motor, and in the interval where the signal of the linear sensor is used, the interval between the upper mold and the lower mold can be controlled. Even if the upper mold reaches the lowermost end, the rotation angle of the motor shaft is not fixed due to deformation of the mold due to compression stress, etc., but it vibrates slightly as shown in Fig. 4 (2).

[Best Embodiment]

Figures 5 to 8 show the preferred embodiment and its characteristics, except for the parts specifically indicated, which are the same as the basic embodiments of Figures 1 to 4. FIG. 5 shows a cross section of the linear sensor 50. The element symbol 51 is a metal casing. The movable magnetic rod 44 is provided with a magnetic mark composed of a magnetic body 52 and a non-magnetic body 53 and penetrates a plurality of The sensor head 48 of the coil. A slide member 54 and a magnetic rod 44 that slide along the groove 57 of the housing 51 are fixed to the reference plate 45, and the reference plate 45, the magnetic rod 44, and the slide member 54 slide integrally to the left and right in the figure. The magnetic rod 44 and the slide member 54 are connected by the connecting member 55, and are urged toward the reference plate 45 side on the left side of the figure by the elastic body 49. In addition, before the reference plate 45 is pressed from the upper mold side, the coupling member 55 is positioned by the stopper 56 due to the urging force of the elastic body 49, and the stroke of the magnetic rod 44 is, for example, about 10 mm. In addition, within the range of this stroke, the interval between the upper and lower molds is measured, and at the beginning of the stroke, the weighted average of the encoder signal and the linear sensor 50 signal is fed back to the servo motor. In the middle of the stroke, The upper mold is lowered to the lowest point, and injection molding, die casting molding, and compression molding are performed.

When the magnetic rod 44 is urged sharply toward the right side in the figure by the upper mold, the magnetic rod 44 may move independently from the reference plate on the upper mold side. Such vibration will make the servo motor control unstable. On the other hand, by using the elastic body 49 and the stopper 56, the magnetic rod 44 is strongly urged toward the reference plate 45 from the beginning, so that the deceleration (absolute value of acceleration) of the magnetic rod 44 is greater than The deceleration of the upper mold. In this way, there will be no vibration. In addition, it is assumed that even if vibration occurs, it will only occur at the beginning of the stroke. Moreover, if the signal of the encoder and the signal of the linear sensor 50 are used by weighted average, the influence of vibration can be reduced. Figure 6 shows such a mechanism.

Fig. 6 shows the position of the upper mold 4 near the lowest point P of the upper mold Position and speed, the locus 60 indicates the position and speed of the upper mold 4. In addition, the chain line 62 in the upper right circle is a track where the magnetic rod 44 as a linear sensor is separated from the upper mold to move, indicating its trajectory. If it is assumed that the magnetic rod 44 moves independently from the upper mold 4, its deceleration a is proportional to the elastic constant of the elastic body 49, and if the elastic body 49 is compressed by the stopper 56 in advance, the deceleration a Get bigger. If the deceleration of the upper mold 4 is set to b, when the deceleration a of the magnetic rod 44 is greater than the deceleration b of the upper mold, the magnetic rod will be pressed against the upper mold by the elastic body without vibration. Therefore, by selecting the elastic constant of the elastic body 49 and the position of the stopper 56, the vibration of the magnetic rod 44 can be prevented. Since the deceleration a of the magnetic rod increases as it approaches the lowest point, the possibility that the trajectory 62 of the magnetic rod deviates from the trajectory 60 of the upper mold is limited to the beginning of the stroke. At the beginning of the stroke, since the encoder and the linear sensor are used for speed control, it is assumed that even if vibration of the magnetic rod 44 occurs, the vibration degree is small and the influence on the speed control is also small.

FIG. 7 shows that the linear sensor 50 is attached to the lower mold 6. The wire sensor 50 is fixed at, for example, four locations around the cavity 70 where injection molding, die casting, press molding, etc. are performed. Therefore, the relative position between the upper and lower molds can be accurately measured without being affected by the stress caused by the contact of the upper and lower molds 4 and 6 and the temperature change of the lower mold 6. In addition, since the linear sensor 50 is arranged at a plurality of positions around the cavity 70, the average value and deviation of the relative positions between the molds can be accurately measured. In addition, the reference plate 24 may be provided in the upper mold, or the reference plate 24 may not be provided, and the upper mold itself may be used as the reference plate.

Fig. 8 shows the control result of the preferred embodiment, and Fig. 9 shows the control result of the prior art example in which the servo motor is controlled only by the encoder signal. The end position of the motor in the figure represents the signal of the encoder, and here represents the area near the lowermost end of the stroke of the upper mold result. In an embodiment, at the mold clamping position, an error of less than 3 μm including the external error of the system may be used to control the interval between the upper and lower molds. In addition, the measurement error of the linear sensor can be about ±1 μm, for example. In addition, the position of the motor end is not fixed due to stress caused by the contact of the mold. In the embodiment, the feedback control is performed by the signal of the linear sensor in a manner to correct the deformation and thermal deformation due to stress. Therefore, if the end position under the upper mold is fixed, the position of the motor end will not be fixed. In contrast, in the prior art example, the position of the motor end is fixed, and the end position under the upper mold is unstable.

The embodiment has the following features.

1) Measure the actual distance between the molds 4 and 6 by using the linear sensors 22 and 50 for mold installation and the reference plate 24 near the opposing parts of the molds 4 and 6 above and below.

2) Use the linear sensors 22, 50 for mold installation with a short measuring range to measure the gap between the molds 4 and 6 with high position resolution.

3) Outside the measurement range of the linear sensors 22 and 50 for mold installation, the signal of the encoder 36 is used, and the weight w of the signal of the encoder 36 and the signal of the signal of the linear sensor are added by the adder 40 The weight (1-w) changes continuously, so there will be no control confusion caused by the switching of the sensors.

4) Multiple feedback control loops are formed by controlling the speed as a secondary loop for position control and controlling the torque (current) as a secondary loop for speed control.

5) In the switching between the encoder and the linear sensor of the feedback signal, the control loop is switched by changing only the feedback signal. Therefore, it is preferable to use an encoder and a linear sensor to correct the responsiveness and minimum resolution of the signal by pre-processing. In addition, even if the feedback signal is switched, the servo parameters such as the parameters of the specified position and the loop gain still use the same value.

6) With the elastic body 49 and the stopper 56 etc., the magnetic rod 44 is moved upward in advance The deceleration rate when the force is applied to the mold side and the magnetic rod 44 is moved independently from the upper mold side is greater than that of the upper mold. In this way, since the magnetic rod 44 cannot move away from the upper mold side, the movement of the mold to be accurately measured, that is, the movement of the magnetic rod 44 and the movement of the linear sensor can be made uniform in time.

7) The area where the magnetic rod 44 moves independently from the upper mold side is limited to the state where the reference plate 45 of the magnetic rod is not in contact with the reference plate 24 of the linear sensor for mold mounting, and the reference plates of both sides are in contact At the beginning of the stroke of the magnetic rod 44 after that. In this area, since the signal of the encoder and the signal of the linear sensor are used for speed control, even if it is assumed that the vibration of the magnetic rod 44 is generated, the influence can be reduced on the control side.

8) As shown in FIG. 7, if a plurality of linear sensors 50 and the like are arranged in the fixed lower mold 6 around the cavity 70, the relative position of the upper and lower molds can be accurately measured. In particular, since the measurement is performed inside the mold and near the cavity, the deformation caused by the contact of the mold, the deformation caused by the temperature deformation of the mold, etc., will not become an error. In addition, the deviation of the position of the upper and lower molds can be measured.

9) When the mold clamping is completed, the torque output from the control circuit will be cut off, or it will be limited to low torque in order to prevent abnormal heating of the motor.

16‧‧‧Servo motor

20‧‧‧Control Department

22‧‧‧Linear sensor for mold installation

26‧‧‧Strain gauge

30‧‧‧Command generator

31‧‧‧Differentiator

32‧‧‧differentiator

33‧‧‧Amplifier

34‧‧‧Amplifier

35‧‧‧Current amplifier

36‧‧‧Encoder

38‧‧‧Adder

40‧‧‧ adder

P0‧‧‧Position command

P1‧‧‧signal

P2‧‧‧Signal

P3‧‧‧Position signal

v‧‧‧Speed signal

Claims (4)

A mold clamping device comprising: at least a pair of opposed dies; a servo motor that causes at least one of the dies to move via a link shaft; and a signal from an encoder of the servo motor or monitoring the link shaft The signal of the long-range linear sensor of the position is used as the control input value, and the control part of the feedback control of the servo motor; the feature of the mold clamping device is that it is composed of: a mold installation composed of a linear sensor A sensor is used to monitor the interval between the molds by the signal of the mold mounting sensor, wherein the mold mounting sensor is directly fixed to one of the molds near the opposite part of the mold , And measure the position based on the opposite mold or the reference plate by contacting the opposite mold or the reference plate installed on the opposite mold; and, setting the switching means, the switching means is in the above code The signal of the sensor or the signal of the long-range linear sensor and the signal of the sensor for mold installation are switched in a continuous manner; the mold clamping area near the mold clamping position is determined by the mold The sensor signal is used to control the servo motor; in the remote area away from the self-clamping position, the servo motor is controlled by the signal of the encoder or the signal of the long-range linear sensor; in the remote area The intermediate area between the mold clamping area and the signal of the encoder or the sensor of the long-range linear sensor and the signal of the mold mounting sensor are used to switch the control input value in a continuous manner; and The above-mentioned switching means converts the signal P1 of the encoder or the signal of the long-range linear sensor that monitors the position of the connecting rod shaft and the signal of the sensor for mold installation by a variable weight w of 0 or more and 1 or less P2, use P3=P1‧w+P2‧(1-w) to convert to control Enter the value P3, and w=1 when it exceeds the measurement range of the mold mounting sensor, w=0 when the mold is in the closest range, and when the mold enters the measurement range of the mold mounting sensor , The weight w is determined in such a way that the weight w continuously changes from 1 to 0. For example, the mold clamping device according to item 1 of the patent application, wherein the control section includes: position control means for converting the error between the command position and the control input value into a speed command; and for controlling the speed command and The error between the rate of change of the signal of the encoder per unit time is converted into the speed control means of the current command. For example, the mold clamping device according to item 1 or 2 of the patent application scope, wherein the sensor for mounting the mold has: a magnetic rod with a magnetic mark, which is advanced and retracted by the opposing mold; measuring the advance and retreat of the magnetic rod A position sensing head; a stopper that determines the movement limit of the magnetic rod toward the connecting rod shaft side; and an elastic body that urges the magnetic rod toward the connecting rod shaft side; the magnetic rod is configured as: Contact with the opposite mold or the above-mentioned reference plate and move along the link axis; and using the above-mentioned elastic body, the magnetic rod is previously biased toward the link axis side at the position fixed by the stopper, thereby eliminating Vibration of the magnetic rod caused by contact with the contact member. A mold clamping method is based on the signal of the encoder of the servo motor or the signal of the long-range linear sensor that monitors the position of the connecting rod shaft, and at least one side of the opposing mold is feedback controlled while facing the servo motor. A mold clamping method that generates movement; characterized by: a sensor for mold installation composed of a linear sensor, and The signal of the sensor monitors the interval between the molds, wherein the sensor for mounting the mold is directly fixed to the mold of one mold in the vicinity of the opposing part of the mold, and by Or it is contacted with the reference plate of the opposite mold to measure the position based on the opposite mold or the reference plate; and by switching means, the signal of the encoder or the signal of the long-range linear sensor , And the signal of the sensor for mold installation to switch the above control input value in a continuous manner; in the mold clamping area near the mold clamping position, the servo motor is controlled by the signal of the sensor for mold installation ; In the remote area away from the mold clamping position, the servo motor is controlled by the signal of the encoder or the signal of the long-range linear sensor; the intermediate area between the remote area and the mold clamping area is above The signal of the encoder or the signal of the long-range linear sensor and the signal of the sensor for mold installation are used to switch the above control input value in a continuous manner; The weight of change w is to use the signal P1 of the encoder or the signal of the long-range linear sensor that monitors the position of the connecting rod shaft and the signal P2 of the sensor for mold installation, using P3=P1‧w+P2‧( 1-w) Converted to the control input value P3, and w=1 when it exceeds the measurement range of the mold installation sensor, w=0 when the mold is in the closest interval, and when the mold enters the mold installation sense When the measurement range of the detector is within the range, the weight w is determined in such a way that the weight w continuously changes from 1 to 0.

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