JP2010110960A - Controller for toggle type injection molding machine having means of detecting mold closing position - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for toggle type injection molding machines having a means of detecting the mold closing position. <P>SOLUTION: The controller 20 controlling an injection molding machine calculates the magnification of a toggle type clamping mechanism geometrically from the position of the crosshead detected by a position-speed detector 11 serving as a means of detecting the position of the crosshead and the thrust of the movable platen 3 on the basis of a current of the motor detected by a current detector 12, determines the variation amount of the calculated thrust of the movable platen 3 per constant time, determines whether the variation amount reaches a predetermined value or not and detects the position of the crosshead when the variation amount reaches the predetermined value as the mold closing position. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for a toggle injection molding machine, and more particularly to a control device for a toggle injection molding machine provided with a mold closing position detecting means.

  Move the movable platen forward and contact the movable mold attached to the movable platen with the fixed mold attached to the fixed platen. Conventionally, the position is detected.

  Patent Document 1 discloses a technique in which the load torque during mold closing is monitored and the mold closing position when the fluctuation rate of the load torque reaches a preset fluctuation rate is set as the mold closing position. The technique of this document detects that the load torque during mold closing changes at a constant level as shown in FIG. 1 and the value suddenly increases when the mold closes, and the position of the crosshead at that time is determined as the mold. The closed position Pch is determined. In the graph of FIG. 1, the load torque on the vertical axis is displayed as a ratio to the maximum torque of the motor. The horizontal axis represents time.

  In Patent Document 2, the spring is completely compressed by generating the driving torque of the movable platen forward / backward servomotor so that the platen thrust slightly exceeds the reaction force of the spring. A technique is disclosed in which the detection is performed by the movable platen closing the mold and the rotation of the movable platen forward / backward servomotor being stopped (the presence or absence of a position feedback signal).

  Patent Document 3 discloses a technique for calculating a mold clamping force by multiplying an enlargement ratio of a toggle mechanism from a thrust of a cross head during mold closing as a monitor amount during mold closing.

JP 2005-288893 A JP-A-9-57804 JP-A-5-293863

  In the technique disclosed in Patent Document 1 described in the background art, in the case of a mold with a spring, the load torque increases when the spring is compressed. Therefore, the load torque is increased by closing the mold or the load torque by compressing the spring. It is not possible to determine whether it is rising. FIG. 2 shows the transition of the load torque when the mold with a spring is closed. As shown in FIG. 2, the load torque rises at the moment Pfa at which the compression of the spring is started. In the technique disclosed in Patent Document 1, there is a possibility that the moment Pfa at which compression of the spring is started may be determined as the mold closing position, and the accurate mold closing position Pch cannot be determined. In the graph of FIG. 2 as well, the load torque is displayed as a ratio to the maximum torque of the motor, similarly to the graph of FIG. The horizontal axis represents time.

  Further, the technique disclosed in Patent Document 2 completely compresses a spring by generating a driving torque of a movable platen forward / backward servomotor in order to detect a mold closing position. The closed position is detected based on the rotation stop state (presence or absence of a position feedback signal) of the movable platen forward / backward servomotor after the movable platen closes the mold.

  In the technique disclosed in Patent Document 2, in order to detect the mold closed position, it is necessary to detect that the stationary plate mold and the movable mold are in contact with each other and the movable platen forward / backward servomotor is stopped. . For this reason, it is absolutely necessary to compress the mold with a certain pressure (= pressure slightly exceeding the spring reaction force). For this reason, there has been a problem that the movable platen forward / backward servomotor stops at a position compressed from the original mold closing position, and that position is determined as the mold closing position.

  Accordingly, an object of the present invention is to provide a control device for a toggle type injection molding machine provided with a mold closing position detecting means capable of detecting a mold closing position regardless of the presence or absence of a spring incorporated in the mold. .

  The invention according to claim 1 of the present application has a toggle type clamping mechanism, a movable platen forward / backward servomotor that moves the movable platen forward / backward via the toggle type clamping mechanism, and the movable platen forward / backward servo. In a control apparatus for controlling a toggle injection molding machine comprising: current detection means for detecting a motor current value of a motor; and crosshead position detection means for detecting the position of a crosshead of the toggle type clamping mechanism. The control device is configured to move the movable unit based on the enlargement ratio of the toggle type mold clamping mechanism geometrically obtained from the crosshead position detected by the crosshead position detecting unit and the motor current value detected by the current detecting unit. The thrust calculation means for calculating the thrust of the platen and the thrust calculation when the movable platen forward / backward servomotor moves the movable platen. A change amount of the thrust of the movable platen calculated by the means is obtained, it is determined whether the change amount has reached a preset change amount, and a position of the crosshead when the preset change amount is reached is determined by a mold. A control device for controlling a toggle type injection molding machine, comprising: a mold closing position detecting means for detecting a closing position.

The invention according to claim 2 is the control apparatus for controlling the toggle type injection molding machine according to claim 1, wherein the change amount of the thrust is a change amount with respect to a predetermined time.
According to a third aspect of the present invention, the amount of change in the thrust is the amount of change with respect to a constant amount of movement of the crosshead position detected by the crosshead position detecting means for detecting the position of the crosshead of the toggle type mold clamping mechanism. The control device for controlling the toggle type injection molding machine according to claim 1.
The invention according to claim 4 is the control apparatus for controlling the toggle type injection molding machine according to claim 1, wherein the change amount of the thrust is a change amount with respect to a constant movement amount of the movable platen position. .
According to a fifth aspect of the present invention, there is provided a movable platen forward / backward servomotor having a toggle type mold clamping mechanism and moving the movable platen back and forth via the toggle type mold clamping mechanism, and the movable platen forward / backward servomotor. In the control apparatus for controlling a toggle type injection molding machine comprising: current detection means for detecting a motor current value; and crosshead position detection means for detecting the position of the crosshead of the toggle type mold clamping mechanism. Is based on an enlargement ratio of the toggle type mold clamping mechanism geometrically obtained from the crosshead position detected by the crosshead position detecting means and a motor current value detected by the current detecting means. A thrust calculating means for calculating a thrust, and the thrust calculating means when the movable platen forward / backward servomotor moves the movable platen; Mold closing position detection for determining whether the thrust of the movable platen calculated from the above reaches a preset threshold thrust, and detecting the position of the crosshead when the preset threshold thrust is reached as a mold closing position And a control device for controlling a toggle type injection molding machine.

  According to the present invention, it is possible to provide a control device for a toggle type injection molding machine provided with a mold closing position detecting means capable of detecting a mold closing position regardless of the presence or absence of a spring incorporated in the mold.

  FIG. 3 is a schematic diagram of a mold clamping device 100 used in an injection molding machine as an example of the mold clamping device. The stationary platen 1 and the rear platen 2 are connected by four tie bars 4 constituting a mold clamping mechanism. Between the fixed platen 1 and the rear platen 2, a movable platen 3 is guided by a tie bar 4 and is movably disposed. A fixed mold 5a is attached to the fixed platen 1, and a movable mold 5b is attached to the movable platen 3 so as to face the fixed mold 5a.

  A toggle mechanism 6 constituting a mold clamping mechanism is disposed between the rear platen 2 and the movable platen 3, and a nut provided on a cross head 6 a of the toggle mechanism 6 is attached to the rear platen 2 so as to be rotatable and immovable in the axial direction. The ball screw 7 is screwed. When the movable platen forward / backward servomotor 8 drives the ball screw 7 via the transmission mechanism 10, the movable platen 3 is moved forward and backward in the direction of the fixed platen 1, thereby opening and closing the molds 5a and 5b and clamping. Thus, a toggle type mold clamping device is formed. The mold closing operation is an operation of moving the movable platen 3 forward to the fixed platen 1 side. The mold opening operation is an operation of moving the movable platen 3 away from the fixed platen 1 side, that is, an operation of retreating. A position / speed detector 11 for detecting the rotation position (rotation angle) and speed of the servo motor such as a pulse coder is attached to the movable platen forward / backward servo motor 8. Based on the output signal from the position / velocity detector 11, the position of the cross head 6a, that is, the state of the toggle mechanism 6 and the position of the movable platen 3 (movable side mold 5b) can be detected.

  Further, a mold clamping force adjusting means is constituted by a transmission mechanism (not shown) including a tie bar nut 9 and a gear, a mold thickness adjusting motor 14 and the like. The end of the tie bar 4 on the rear platen 2 side is threaded. The tie bar nut 9 screwed with the screw is rotationally driven by the mold thickness adjusting motor 14 via the transmission mechanism (not shown), so that the rear platen 2 can move forward and backward along the tie bar 4.

  Reference numeral 20 denotes a control device that controls the injection molding machine. FIG. 3 shows only the main part of the control device 20. An axis control circuit 22, an input / output circuit 24, a memory 26, and an interface circuit 28 of a display device 29 that control the position, speed, and current (torque) of the servo motor via a bus 30 to a processor (CPU) 21 that controls the whole. Is connected.

  The axis control circuit 22 includes a processor, a memory, an interface, and the like. The position / speed feedback signal from the position / speed detector 11 attached to the movable platen forward / backward servomotor 8 is fed back. A current feedback signal from the current detector 12 that detects the drive current of the servo motor 8 is fed back. The axis control circuit 22 is connected to a movable platen forward / backward servomotor 8 via a servo amplifier 23. Further, the mold thickness adjusting motor 14 is connected to the input / output circuit 24 via the inverter 25, and the display device 29 is connected to the interface circuit 28.

  The memory 26 stores a program for controlling the injection molding machine. A program created based on a flowchart shown in an algorithm for adjusting the clamping force described later is also stored in the memory 26. The processor 21 controls the injection molding machine based on these programs. Regarding the mold clamping operation, the processor 21 outputs a movement command to the axis control circuit 22 based on the program. A processor (not shown) built in the axis control circuit 22 determines the position and speed based on the movement command and the position / speed feedback signal from the position / speed detector 11 and the current feedback signal from the current detector 12. , And current feedback control, and drive control of the movable platen forward / reverse servomotor 8 is performed via the servo amplifier 23.

  By driving the movable platen forward / backward servomotor 8, the ball screw 7 rotates, and the crosshead 6 a of the toggle mechanism 6 having a nut screwed to the ball screw 7 moves along the ball screw 7, thereby driving the toggle mechanism 6. The movable platen 3 moves. When the movable platen 3 is moved forward, the movable mold 5b moves forward. When the movable platen 3 continues to move forward, the movable mold 5b comes into contact with the fixed mold 5a, and when the movable platen 3 is further moved forward, a toggle mechanism. When the link 6 extends and the movable platen 3 reaches a predetermined mold clamping completion position, the movable platen forward / reverse servomotor 8 is positioned at this position, and a mold clamping force is generated.

  That is, since the fixed platen 1 and the rear platen 2 are connected by the tie bar 4, when the fixed side mold 5a and the movable side mold 5b come into contact with each other, and the movable platen 3 and the movable side mold 5b move forward, the tie bar 4 is stretched, and a clamping force is obtained by the reaction force of the tie bar 4 stretching.

  Due to such a structure, when the molds 5a and 5b are exchanged for different mold thicknesses or when the mold clamping force is changed, the target mold clamping force is obtained when the movable platen 3 advances to the mold clamping completion position. Therefore, it is necessary to adjust the clamping force by changing the position of the rear platen 2 so that the tie bar is stretched so as to obtain the above. When changing the position of the rear platen 2, the processor 21 drives the mold thickness adjusting motor 14 via the input / output circuit 24, and rotates the tie bar nut 9 via a transmission mechanism (not shown) to adjust the position of the rear platen 2. Change.

  A rear platen position detector 13, which is a sensor for specifying the rotational position of the mold thickness adjusting motor, is attached to the mold thickness adjusting motor 14. The rotational position data of the mold thickness adjusting motor 14 detected by the rear platen position detector 13 is input to the control device 20 via the input / output circuit 24.

  In the injection molding machine in which the toggle type clamping mechanism is driven by the movable platen forward / backward servomotor 8 in this way, the position of the crosshead 6a in a state where the fixed side mold 5a and the movable side mold 5b are in contact with each other thereafter The extension amount of the tie bar 4 when the movable platen 3 is advanced to the mold clamping completion position, that is, the mold clamping force can be calculated. In order to obtain an accurate mold clamping force, it is necessary to accurately obtain the position of the crosshead 6a in a state where the fixed mold 5a and the movable mold 5b are in contact with each other as the mold closing position.

  Next, the principle of the mold closing position detection method of the present invention will be described. FIG. 4 is a diagram for explaining the time transition of the load torque and thrust Th of the movable platen forward / backward servomotor when the spring-loaded mold is closed. When the mold is closed with the mold closed, the tie bar 4 is extended, and a mold clamping force is generated by the elastic force of the tie bar 4.

  When only the load torque fluctuation during mold closing is monitored as in the prior art, as shown in the load torque graph of FIG. 4, the distinction between when the spring in the mold is contracted and when the mold is closed is performed. I can't. In the mold closing position detection method of the present invention, the thrust of the movable platen 3 during mold closing is obtained by sequential calculation from the current value for driving the movable platen forward / backward servomotor 8 and the enlargement ratio of the toggle link mechanism, and the fluctuation of the thrust By detecting this, it is possible to accurately determine the timing of mold closing.

When the mold is closed while the mold is closed and the tie bar 4 is extended and the spring in the mold is extended, the elastic constant value of the elastic body being extended is greatly different, so the same distance is moved. There is a large difference in the amount of change in thrust, which is the forward force of the movable platen 3. For this reason,
As shown in FIG. 4, the load torque varies greatly when the spring in the mold starts to contract, whereas the thrust Th of the movable platen 3 does not vary significantly. The thrust Th of the movable platen 3 greatly fluctuates when the mold closes and the tie bar 4 begins to expand (mold closing position Pch). Therefore, the accurate mold closing position can be determined by detecting this change. Can do. Further, the threshold thrust in the figure is a thrust that serves as a determination criterion when determining the mold closing position based on the magnitude of the thrust.

  On the other hand, FIG. 5 shows the relationship between the load torque of the movable platen forward / backward servomotor 8 and the calculated thrust Th of the movable platen 3 when a mold without a spring is closed. Also in this case, the accurate mold closing position can be determined by detecting the variation of the thrust Th. Further, the threshold thrust in the figure is a thrust that serves as a determination criterion when determining the mold closing position based on the magnitude of the thrust.

  Next, a calculation formula for calculating the thrust Th of the movable platen 3 will be described. In the mold closing process, the thrust Th of the movable platen 3 can be obtained from Equation 1 based on the drive current of the movable platen forward / backward servomotor 8 for moving the crosshead 6a forward and backward and the enlargement ratio of the toggle link mechanism. .

Th: Thrust of movable platen [N]
Gd: Number of teeth of drive pulley of movable platen forward / backward servomotor Gf: Number of teeth of driven pulley of movable platen forward / backward servomotor R: Lead of ball screw [m]
A: Ratio of the current value of the servo motor for moving the platen back and forth to the maximum current (%)
Here, the maximum current is a current value when the movable platen forward / backward servomotor generates a maximum torque.
Tmax: Maximum torque [Nm]
λ: Toggle link magnification at the current position of the crosshead (current position of the movable platen forward / backward servomotor)

  FIG. 6 is a diagram for explaining the derivation of equation (1). FIG. 6A is a schematic view of the driving pulley 15 and the driven pulley 16 as viewed from the front. As shown in FIG. 6B, the drive pulley 15 is attached to the rotating shaft of the movable platen forward / backward servomotor 8, and the driven pulley 16 is attached to the ball screw 7. The rotation of the driving pulley 15 is transmitted to the driven pulley 16 by the timing belt 10. The ball screw 7 is rotated by the rotation of the driven pulley 16. The cross head 6 a moves in the axial direction of the ball screw 7 by the rotation of the ball screw 7. As described above, the number of teeth of the drive pulley 15 is Gd, and the number of teeth of the driven pulley 16 is Gf. The lead of the ball screw 7 is R. The rotational energy (see FIG. 6C) when the ball screw 7 is rotated once by the rotational torque Tb can be expressed by Equation 2.

  Further, the energy of the linear motion when the ball screw 7 makes one rotation (see FIG. 6D) can be expressed by Equation 3 when the forward force is F ([N]: Newton).

  Since rotational energy is converted into linear motion energy, Equation 4 is obtained from the energy conservation law.

  Since Tb is the rotational torque of the ball screw 7, when calculating from the motor torque Tm, it can be expressed as Equation 5. Substituting into Equation 3 yields Equation 5.

  By substituting equation (5) into equation (4) and obtaining F, equation (6) is obtained.

  Since Tm is the current torque value of the movable platen forward / reverse servomotor 8, it can be expressed by Equation (7).

  Here, A is the ratio (%) of the current current value of the movable platen forward / backward servomotor 8 to the maximum current value, and Tmax is the maximum torque value (torque value at the maximum current) of the movable platen forward / backward servomotor 8. ). Then, Formula 6 can be transformed into Formula 8.

  Since F is the forward force of the ball screw 7, when converted to the thrust Th of the movable platen 3, Formula 1 can be obtained by multiplying the enlargement factor λ of the toggle mechanism.

Next, the flowchart which shows the algorithm which performs the metal mold | die closed position detection process of this invention shown by FIG. 7 is demonstrated. Hereinafter, it demonstrates according to each step.
[Step SA1] With the fixed side mold 5a and the movable side mold 5b opened, mold closing is started at low speed and low torque. Here, the low torque is set to a value that allows the mold to be completely closed against the elastic force of the spring in the mold incorporating the spring.
[Step SA2] The crosshead position of the crosshead 6a is detected. The position of the cross head 6a can be detected based on a detection signal from a position / speed detector 11 attached to the servo motor 8 for moving the platen forward and backward.
[Step SA3] The enlargement ratio is calculated based on the position of the crosshead 6a. A function equation is set in advance for the relationship between the position of the crosshead 6a and the enlargement ratio. More specifically, a function formula is stored in the memory 26.

[Step SA4] The drive current of the movable platen forward / backward servomotor 8 of the movable platen 3 is detected using the current detector 12.
[Step SA5] Thrust Th is calculated based on Formula 1.
[Step SA6] Set Th_s to Th.
[Step SA7] The crosshead position of the crosshead 6a is detected. The position of the cross head 6a can be detected based on a detection signal from a position / speed detector 11 attached to the servo motor 8 for moving the platen forward and backward.

[Step SA8] The enlargement ratio is calculated based on the crosshead position of the crosshead 6a.
[Step SA9] The drive current of the movable platen forward / backward servomotor 8 of the movable platen 3 is detected by using the current detector 12.
[Step SA10] Thrust Th is calculated based on Formula 1.
[Step SA11] It is determined whether or not the difference between the thrust Th calculated in Step SA10 and the previously calculated thrust Th_s is equal to or smaller than a thrust fluctuation amount ΔTh for determining mold closing detection. If not, the process proceeds to step SA14. Here, the thrust fluctuation amount ΔTh is a preset value. This comparison and determination is performed every control cycle.
[Step SA12] Replace the previously calculated thrust Th_s with the currently calculated thrust Th.

[Step SA13] It is determined whether or not the crosshead position of the crosshead 6a detected in Step SA7 is 0 (zero). If it is not 0 (zero), the process returns to Step SA7 to continue the process. ), The process proceeds to step SA15.
The position where the toggle link is extended to the maximum in the toggle type mold clamping mechanism is defined as an origin O of the toggle mechanism. That the crosshead position is 0 (zero) means that the origin O of the toggle mechanism, that is, the mold closed position is not reached even when the toggle link is extended to the maximum.
[Step SA14] The crosshead position of the crosshead 6a detected in step SA7 is set to the crosshead mold closing position Ytch.
[Step SA15] The crosshead mold closing position Ytch is displayed when the process proceeds from step SA14, or the crosshead mold closing position Ytch is not detected when the process proceeds from step SA13. .
[Step SA16] The mold is closed and finished.

The algorithm flowchart shown in FIG. 8 determines whether or not the crosshead 6a has reached the mold closing position based on whether or not the thrust Th of the movable platen 3 has reached a preset threshold thrust. Yes. In step SB6, it is determined whether or not the thrust Th calculated in step SB5 is equal to or greater than a preset threshold thrust.
Hereinafter, it demonstrates according to each step.
[Step SB1] With the fixed mold 5a and the movable mold 5b opened, the mold closing is started at a low speed and a low torque. Here, the low torque is set to a value that allows the mold to be completely closed against the elastic force of the spring in the mold incorporating the spring.
[Step SB2] The crosshead position of the crosshead 6a is detected. The position of the cross head 6a can be detected based on a detection signal from a position / speed detector 11 attached to the servo motor 8 for moving the platen forward and backward.
[Step SB3] The enlargement ratio is calculated based on the position of the crosshead 6a. A function equation is set in advance for the relationship between the position of the crosshead 6a and the enlargement ratio. More specifically, a function formula is stored in the memory 26.

[Step SB4] The drive current of the movable platen forward / backward servomotor 8 of the movable platen 3 is detected by using the current detector 12.
[Step SB5] Thrust Th is calculated based on Formula 1.
[Step SB6] It is determined whether or not the thrust Th is greater than or equal to a preset threshold thrust. If the thrust Th is greater than or equal to the threshold thrust, the process proceeds to Step SB8, and if not, the process proceeds to Step SB7.
[Step SB7] It is determined whether or not the crosshead position of the crosshead 6a detected in Step SB2 is 0 (zero). If it is not 0 (zero), the process returns to Step SB2 to continue the process. ), The process proceeds to step SB9.
The position where the toggle link is extended to the maximum in the toggle type mold clamping mechanism is defined as an origin O of the toggle mechanism. That the crosshead position is 0 (zero) means that the origin O of the toggle mechanism, that is, the mold closed position is not reached even when the toggle link is extended to the maximum.
[Step SB8] The crosshead position of the crosshead 6a detected in Step SB2 is set to the crosshead mold closing position Ytch.
[Step SB9] In the case of transition from step SB8, the crosshead mold closing position Ytch is displayed, or in the case of transition from step SB7, it is displayed that the crosshead mold closing position Ytch has not been detected. .
[Step SB10] The mold is closed and finished.
The processor 21 of the control device 20 of the injection molding machine can detect the mold closing position by executing the processing shown in FIG. 7 or FIG.

  The determination of the amount of change in thrust in FIG. 7 and FIG. 8 or the determination of the arrival of the threshold value is executed every control cycle, but in order to obtain the amount of change in thrust with respect to the amount of change in crosshead position, You may judge every. In this case, for example, the difference between the crosshead position when Th_s is set in FIG. 7 and the current crosshead position is determined after step SA7, and step SA8 is executed after detecting that the vehicle has advanced by a predetermined interval.

  Further, in order to obtain the amount of change in thrust with respect to the amount of change in the movable platen position, it may be determined whether the amount of change in thrust or the arrival of the threshold value is reached for each fixed movable platen position. In this case, for example, after the crosshead position is detected in step SA2 and step SA7 in FIG. 7, the movable platen position is calculated by a geometrical calculation formula, and the amount of change in thrust is calculated in the same manner as every fixed crosshead movement amount. to decide. Alternatively, a linear scale or the like may be added to the movable platen to directly measure the position.

Further, in FIGS. 7 and 8, the thrust is calculated sequentially while the movable platen 3 is moved forward by the movable platen forward / backward servomotor 8 to determine whether the thrust change amount or the threshold value is reached. The forward / backward servomotor 8 is driven with a constant load torque, the movable die 5b and the fixed die 5a are brought into contact with each other, and there is no change in the detection position of the movable platen forward / backward servomotor 8, that is, movable. The side mold 5b and the fixed mold 5a are compressed with a constant load torque by the movable platen forward / backward servomotor 8, and the movable platen 3 is moved backward by the movable platen forward / backward servomotor 8 from this state. You may obtain | require thrust sequentially, making it.
FIG. 9 is a diagram for explaining the transition of the load torque of the movable platen forward / backward servomotor when the mold is opened from the state in which the springless mold is compressed. FIG. 10 is a diagram for explaining the transition of the load torque of the movable platen forward / backward servomotor when the mold is opened from the state where the spring-loaded mold is compressed.

  In this case, the movable platen forward / backward servomotor 8 is pushed back in the backward direction by the compression force of the mold or the spring in the mold. In order to move the movable platen 3 backward against the pushed-back force. The movable platen forward / reverse servomotor 8 moves backward while generating thrust in the forward direction. After that, when the closed state of the movable mold 5b and the fixed mold 5a is released, the thrust is switched in the backward direction. Thus, when the movable platen 3 is moved backward, the detected crosshead position is not the mold closed position but the mold closed open position, but the same position as the closed position is detected.

  Further, a linear motor may be used as a mechanism for moving the cross head 6a back and forth in the mold clamping device 100. In this case, since it is not necessary to consider the pulley ratio and the lead of the ball screw, Formula 1 for obtaining the thrust Th of the movable platen 3 is simplified as Formula 9.

  An algorithm for performing the mold closing position detection process of the present invention in the case of determination based on the amount of change in thrust when the mold is opened from the state where the mold shown in FIGS. The flowchart which shows is demonstrated.

[Step SC1] The crosshead position of the crosshead 6a is detected.
[Step SC2] The crosshead position where Yst is detected in step SC1 is set as the crosshead current position.
[Step SC3] With the fixed mold 5a and the movable mold 5b opened, the low-speed low-torque mold starts to close.
[Step SC4] The crosshead position of the crosshead 6a is detected. The process of step SC4 is executed in a control cycle after the process of step SC2.
[Step SC5] It is determined whether or not the current position of the crosshead detected in Step SC4 is equal to Yst. If not, the process proceeds to Step SC6. If equal, the process proceeds to Step SC9. That is, the determination in step SC5 is a step of determining whether or not the crosshead 6a is moving.
[Step SC6] Reset Yst to the crosshead position detected in Step SC4. That is, Yst is updated to the current crosshead position after movement.
[Step SC7] It is determined whether or not the crosshead position is 0 (zero). If it is not 0, the process returns to Step SC4, and if it is 0, the process proceeds to Step SC8.
[Step SC8] Mold closed position not detected is displayed on the display screen of the display device, and the process ends. That is, it is displayed that the mold closed position cannot be detected even when the cross head 6a moves to the origin position.
[Step SC9] Stop mold closing.
[Step SC10] The low speed low torque mold opening is started.
[Step SC11] The crosshead position of the crosshead 6a is detected.
[Step SC12] The enlargement ratio is calculated based on the crosshead position.
[Step SC13] The drive current of the movable platen forward / backward servomotor is detected.
[Step SC14] The thrust Th is calculated based on Equation 1.
[Step SC15] Set Th_s to Th.
[Step SC16] The crosshead position is detected.
[Step SC17] The enlargement ratio is calculated based on the crosshead position.
[Step SC18] The drive current of the movable platen forward / backward servomotor is detected.
[Step SC19] The thrust Th is calculated based on the first equation.
[Step SC20] It is determined whether or not the difference between the previously calculated thrust Th_s and the thrust Th calculated in Step SC19 is less than or equal to the thrust fluctuation amount ΔTh for determining the mold closing detection. If not, the process proceeds to step SC23. Here, the thrust fluctuation amount ΔTh is a preset value. This comparison and determination is performed every control cycle.
[Step SC21] Replace the previously calculated thrust Th_s with the currently calculated thrust Th.
[Step SC22] It is determined whether or not the crosshead position of the crosshead 6a detected in Step SC16 is the mold opening completion position. If it is not the mold opening completion position, the process returns to Step SC16. Control goes to step SC24.
[Step SC23] The crosshead position of the crosshead 6a detected in step SC16 is set to the crosshead mold closing position Ytch.
[Step SC24] The crosshead mold closing position Ytch from step SC23 or the crosshead mold closing position Ytch from step SC22 is displayed as undetected.
[Step SC25] The mold opening is stopped and the process ends.

  Also, the flowchart of the algorithm shown in FIGS. 12-1 and 12-2 shows whether the crosshead 6a has reached the mold closing position depending on whether or not the thrust Th of the movable platen 3 has fallen below a preset threshold thrust. Judging whether or not. Hereinafter, it demonstrates according to each step.

[Step SD1] The crosshead position of the crosshead 6a is detected.
[Step SD2] The crosshead position where Yst is detected in step SD1 is set as the crosshead current position.
[Step SD3] With the fixed side mold 5a and the movable side mold 5b opened, the low-speed low-torque mold starts to close.
[Step SD4] The crosshead position of the crosshead 6a is detected. The process of step SD4 is executed in a control cycle after the process of step SD2.
[Step SD5] It is determined whether or not the current position of the crosshead detected in step SD4 is equal to Yst. If not, the process proceeds to step SD6. If equal, the process proceeds to step SD9. That is, the determination at step SD5 is a step of determining whether or not the crosshead 6a is moving.

[Step SD6] Reset Yst to the crosshead position detected in step SD4. That is, Yst is updated to the current crosshead position after movement.
[Step SD7] It is determined whether or not the crosshead position is 0 (zero). If it is not 0, the process returns to step SD4, and if it is 0, the process proceeds to step SD8.
[Step SD8] The mold closed position not detected is displayed on the display screen of the display device, and the process ends. That is, it is displayed that the mold closed position cannot be detected even when the cross head 6a moves to the origin position.
[Step SD9] Stop mold closing.

[Step SD10] Low-speed low-torque mold opening is started.
[Step SD11] The crosshead position of the crosshead 6a is detected.
[Step SD12] The enlargement ratio is calculated based on the crosshead position.
[Step SD13] The drive current of the movable platen forward / backward servomotor is detected.
[Step SD14] The thrust Th is calculated based on Formula 1.
[Step SD15] If the thrust Th is greater than or equal to a preset threshold thrust, the process proceeds to Step SD16, and if not, the process proceeds to Step SD17.

[Step SD16] It is determined whether or not the crosshead position of the crosshead 6a detected in Step SD11 is the mold opening completion position. If it is not the mold opening completion position, the process returns to Step SD11. Control goes to step SD18.
[Step SD17] The crosshead position of the crosshead 6a detected in step SD11 is set to the crosshead mold closing position Ytch.
[Step SD18] The crosshead mold closing position Ytch is displayed when the process proceeds from step SD17, or the crosshead mold closing position Ytch is not detected when the process proceeds from step SD16.
[Step SD19] The mold opening is stopped and the process ends.

  The processor 21 of the control device 20 of the injection molding machine executes the processing shown in FIGS. 7, 8, 11-1, 11-2, 12-1, and 12-2, thereby closing the mold closed position. Can be detected.

A supplementary description will be given of performing automatic mold clamping adjustment using a control device for controlling the toggle type injection molding machine of the present invention.
A fixed mold 5 a is attached to the fixed platen 1, and a movable mold 5 b is attached to the movable platen 3. Then, the movable platen forward / backward servomotor 8 is driven to move the movable platen 3 forward. At this time, the speed of the movable platen forward / backward servomotor 8 is a constant low speed and the pressure is low. However, when a spring is built in the mold, the pressure is set so that the spring can be completely contracted so that the mold is closed. The rear platen 2 is advanced to a position where the mold is completely closed.

While the movable platen 3 is moving forward, the current position of the movable platen forward / backward servomotor 8 is detected at a constant period, and at the same time, the thrust of the movable platen 3 is calculated.
When the fluctuation rate of the thrust Th of the movable platen 3 with respect to a certain period reaches a preset fluctuation rate, the current position of the servo motor 8 for moving the platen forward and backward at that time is set as the mold closing position (t1), and the movable platen 3 Stop moving forward.

  The mold closing position (t2) that can generate the set mold clamping force is obtained in advance from the set mold clamping force, and the movable platen retraction amount y is obtained from the difference between t2 and t1. The rear platen 2 is moved backward by y obtained by the calculation, and the mold clamping force adjustment is completed. The rear platen 2 is retracted by driving the mold thickness adjusting motor 14.

It is a figure explaining transition of the load torque of the servomotor for a movable platen forward / reverse movement when the mold of the springless mold is closed. It is a figure explaining transition of the load torque of the servomotor for a movable platen back-and-forth when the mold with a spring is closed. It is a schematic diagram of the mold clamping apparatus used for an injection molding machine. It is a figure explaining the time transition of the load torque and thrust of a movable platen forward / backward servomotor when a die with a spring is closed. It is a figure explaining the time transition of the load torque and thrust of a movable platen forward / backward servomotor when the mold of a springless mold is closed. It is a figure explaining derivation | leading-out of Formula 1. It is a flowchart which shows the algorithm which performs the metal mold | die closed position detection process of this invention (in the case of judgment based on the variation | change_quantity of thrust). It is a flowchart which shows the algorithm which performs the metal mold | die closed position detection process of this invention (in the case of judgment based on threshold value thrust). It is a figure explaining transition of the load torque of the servomotor for a movable platen back-and-forth when the mold opening is performed from the state where the springless mold is compressed. It is a figure explaining transition of the load torque of the servomotor for a movable platen back-and-forth when the mold is opened from the state where the spring-loaded mold is compressed. It is a flowchart which shows the algorithm which performs the metal mold | die closed position detection process of this invention (in the case of the judgment based on the variation | change_quantity of the thrust when performing mold opening from the state which has compressed the metal mold | die) (the 1). It is a flowchart which shows the algorithm which performs the metal mold | die closing position detection process of this invention (in the case of the judgment based on the variation | change_quantity of the thrust when performing mold opening from the state which has compressed the metal mold | die) (the 2). It is a flowchart which shows the algorithm which performs the metal mold | die closed position detection process of this invention (in the case of judgment based on the threshold thrust when performing mold opening from the state which has compressed the metal mold | die) (the 1). It is a flowchart which shows the algorithm which performs the metal mold | die closed position detection process of this invention (in the case of the judgment based on the threshold thrust when performing mold opening from the state which has compressed the metal mold | die) (the 2).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixed platen 2 Rear platen 3 Movable platen 6a Crosshead 8 Movable platen forward / backward servomotor 11 Position / speed detector 12 Current detector 20 Control device 100 Clamping device

Claims (5)

A movable platen forward / backward servomotor having a toggle type clamping mechanism and moving the movable platen back and forth via the toggle type clamping mechanism, and current detection for detecting a motor current value of the movable platen forward / backward servomotor A control device for controlling a toggle injection molding machine comprising: means; and a crosshead position detecting means for detecting the position of the crosshead of the toggle mold clamping mechanism;
The control device includes:
The thrust of the movable platen is calculated based on the enlargement ratio of the toggle type clamping mechanism geometrically determined from the crosshead position detected by the crosshead position detecting means and the motor current value detected by the current detecting means. Thrust calculating means for calculating;
When the movable platen forward / backward servomotor moves the movable platen,
The amount of change in thrust of the movable platen calculated by the thrust calculation means is obtained, it is determined whether the amount of change has reached a preset amount of change, and the position of the crosshead when the amount of change has reached the preset amount A mold closing position detecting means for detecting as a mold closing position;
A control device for controlling a toggle type injection molding machine.   The control device for controlling a toggle type injection molding machine according to claim 1, wherein the change amount of the thrust is a change amount with respect to a predetermined time.   2. The change amount of the thrust is a change amount with respect to a constant movement amount of the crosshead position detected by a crosshead position detecting unit that detects a position of the crosshead of the toggle type mold clamping mechanism. The control apparatus which controls the toggle type injection molding machine described in 1.   The control device for controlling a toggle type injection molding machine according to claim 1, wherein the change amount of the thrust is a change amount with respect to a constant movement amount of the movable platen position. A movable platen forward / backward servomotor having a toggle type clamping mechanism and moving the movable platen back and forth via the toggle type clamping mechanism, and current detection for detecting a motor current value of the movable platen forward / backward servomotor A control device for controlling a toggle injection molding machine comprising: means; and a crosshead position detecting means for detecting the position of the crosshead of the toggle mold clamping mechanism;
The control device includes:
The thrust of the movable platen is calculated based on the enlargement ratio of the toggle type clamping mechanism geometrically determined from the crosshead position detected by the crosshead position detecting means and the motor current value detected by the current detecting means. Thrust calculating means for calculating;
When the movable platen forward / backward servomotor moves the movable platen,
A mold that determines whether the thrust of the movable platen calculated by the thrust calculation means has reached a preset threshold thrust, and detects the position of the crosshead when the preset threshold thrust is reached as a mold closing position Mold closing position detecting means;
A control device for controlling a toggle type injection molding machine.

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