JP3822157B2 - Method of adjusting clamping force of clamping device and clamping device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
According to the present invention, when a mold is clamped by closing a stationary mold and a movable mold in a mold clamping device of a molding machine such as an injection molding machine or a die cast machine, a predetermined mold clamping force can be obtained when the mold clamping is completed. The present invention relates to a mold clamping force adjusting method and a mold clamping device for making the above.
[0002]
[Prior art]
The injection molding machine includes an injection device and a mold clamping device. The mold clamping device is fixed to a machine base 1 and a fixed die plate 3 to which a fixed mold 2 is attached, as shown in FIGS. 6 and 7, for example. A tie bar 5 fixed to the die plate 3 and spanned over the tail plate 4, a movable die plate 7 movable along the tie bar 5 and having a movable mold 6 attached thereto, and the movable die plate 7 and the tail plate 4. A toggle mechanism 8 which is disposed between and moves the movable die plate 7 forward and backward along the tie bar 5 to open / close and clamp the mold, a mold opening / closing servo motor 9 which operates the toggle mechanism 8, and the tail plate 4 is connected to the tie bar 5. The mold thickness adjusting mechanism 10 that moves the toggle mechanism 8 and the moving die plate 7 together with the tail plate 4 by moving the tail plate 4 and the mold thickness adjusting mechanism 10 is operated. Comprising a cell-type thickness motor 11.
[0003]
The toggle mechanism 8 includes a toggle link 12 that connects the tail plate 4 and the movable die plate 7, a cross head 14 that is connected to the toggle link 12 via a link 13, and a ball screw shaft 15 that is fixed to the rear side of the cross head 14. And a ball screw nut (not shown) that forms part of the ball screw mechanism together with the ball screw shaft 15. The mold opening / closing servo motor 9 drives the pulley 17 and the ball fixed to the pulley 17 via the timing belt 16. The screw nut is rotated to move the ball screw shaft 15 in the axial direction, whereby the cross head 14 is advanced and retracted, and the toggle link 12 is expanded and contracted.
The mold thickness adjusting mechanism 10 includes a tie nut 18 that is screwed into a male screw formed at an end of each tie bar 5 and a common main gear 19 that meshes with the outer periphery of each tie nut 18. The mold thickness motor 11 is driven to drive a motor gear 20. The main gear 19 and the nuts 18 are rotated via this, whereby the tail plate 4, the toggle mechanism 8, and the moving die plate 7 move (advance / retreat) along the tie bar 5 as a unit.
[0004]
When performing mold closing and mold clamping in the mold clamping device, the mold opening / closing servo motor 9 is driven to advance the crosshead 14 and extend the toggle link 12. At the moment of mold closing when the parting surface of the movable mold 6 abuts against the parting surface of the fixed mold 2 (see the solid line in FIG. 6), the toggle link 12 is not yet extended, and at this point the mold clamping force Does not work. When the cross head 14 further advances from here, the toggle link 12 is extended, the tie bar 5 is extended, and the clamping force based on the reaction force acts between the movable mold 6 and the fixed mold 2.
The state of the toggle mechanism 8 when the toggle link 12 is fully extended is called a dead point (see the broken line in FIG. 6). At this time, the maximum mold clamping force is generated. The cross head 14 is set to stop at the time of forward movement, with the position of the dead point as a mold clamping completion position.
[0005]
The stroke (movement) of the crosshead 14 from the position of the crosshead 14 when the movable mold 6 and the fixed mold 2 are in contact (zero clamping force) to the position of the crosshead 14 at the dead point (maximum clamping force). The distance) is said to be the tightening amount of the crosshead 14. For example, as shown in FIG. 8, there is a certain relationship unique to the apparatus between the additional clamping amount and the mold clamping force.
In such a mold clamping device, when the mold to be used is changed, the thickness of the mold usually changes. Therefore, in order to generate a desired mold clamping force at the dead point, according to the thickness of the mold. The tail plate 4 (toggle mechanism 8 and moving die plate 7 is also integrated) needs to be advanced or retracted along the tie bar 5 and set to an additional tightening amount corresponding to the desired clamping force.
[0006]
[Problems to be solved by the invention]
As a conventional method of setting the tightening amount, for example, (1) the mold thickness motor is driven to retract the tail plate, and after the mold replacement, the mold thickness motor is driven to advance the tail plate to move the moving mold. A method of driving the mold opening / closing servo motor to move the crosshead backward from the position of the dead point and then driving the mold thickness motor to advance the tail plate by an amount corresponding to the tightening amount after contacting the fixed mold. (2) Drive the mold thickness motor to retract the tail plate, and after changing the mold, drive the mold opening / closing servo motor to retract the crosshead from the dead point position by the amount of tightening, then mold A method is known in which the thickness plate is driven to advance the tail plate and the movable mold is brought into contact with the fixed mold (see FIGS. 7 and 5 of Japanese Patent Publication No. 8-25213).
[0007]
However, in the above method, when the tail plate is moved forward by an amount corresponding to the additional tightening amount, or when the cross head is moved backward by the additional tightening amount, the mold clamping mechanism including the tail plate, the toggle mechanism and the moving die plate is in a free state (in which direction Therefore, a desired clamping force may not be obtained with the set additional clamping amount due to the influence of backlash and backlash of the clamping mechanism. In particular, there has been a concern that the effect will be noticeable when the injection molding machine is used for a long time and the play becomes large.
Accordingly, an object of the present invention is to provide a mold clamping force adjusting method and a mold clamping device capable of obtaining a mold clamping force as set without being affected by backlash or backlash of the mold clamping mechanism.
[0008]
[Means for Solving the Problems]
The present invention includes a fixed die plate fixed to a machine base and having a fixed mold attached thereto, a tie bar fixed to the fixed die plate and spanned on a tail plate, and a movable mold movable along the tie bar. A movable die plate attached to the movable die plate, a toggle mechanism disposed between the movable die plate and the tail plate, for moving the movable die plate back and forth along the tie bar to open and close the mold, and to clamp the mold. A mold opening / closing servo motor to be operated, a mold thickness adjusting mechanism for moving the toggle mechanism and the moving die plate together with the tail plate by moving the tail plate along the tie bar, and the mold thickness adjusting mechanism. A mold thickness motor to be operated is provided, and the mold opening / closing servo motor is driven to advance and retract the toggle mechanism crosshead. Thus, in the mold clamping apparatus of the molding machine in which the toggle link of the same mechanism expands and contracts to advance and retract the movable die plate along the tie bar, the fixed mold and the movable mold are clamped. A mold clamping force adjustment method that sometimes obtains a desired mold clamping force , driving the mold opening / closing servo motor to bring the toggle mechanism into a state before the dead point where the toggle link extends, and the mold thickness The motor is driven, the tail plate is advanced by the mold thickness adjusting mechanism to bring the moving mold into contact with the fixed mold, and after the moving mold comes into contact with the fixed mold, the mold opening / closing servo motor the off, followed by pressing force by the tail plate retracting the crosshead shortens the toggle link, the position of the crosshead corresponding to the desired clamping force When retracted location, wherein the stopping the driving of the mold thickness motor.
[0009]
According to the mold clamping force adjusting method, the movable mold is pressed against the fixed mold by the driving force of the mold thickness motor, that is, the movable mold is pressed in the same direction as the actual mold clamping. The head tightening amount is set. Therefore, the crosshead moves backward in accordance with the amount of advancement of the tail plate without being affected by backlash or backlash of the mold clamping mechanism. Therefore, when the mold clamping is performed after this adjustment, it is possible to obtain a mold clamping force having a magnitude that accurately corresponds to the additional clamping amount of the cross head.
[0010]
Te above clamping force adjustment method smell, the position of the cross head can be detected by an encoder that is attached to the servomotor for mold opening and closing. Since it is not necessary to detect the position of the tail plate, the mold thickness motor does not require an encoder for position detection.
In the above clamping force adjusting method, when the tail plate is advanced to bring the moving mold into contact with the fixed mold, the toggle mechanism is in a state before the dead point where the toggle link extends. This is because when the toggle mechanism is in a dead point state, the toggle link is not contracted only by the operation of the mold thickness motor (advance of the tail plate). Further, after the moving mold comes into contact with the fixed mold, the switch of the mold opening / closing servo motor is turned off, so that the torque of the mold opening / closing servo motor becomes free and the tail plate This is because the toggle link can be shrunk by the pressing force.
[0011]
In addition, the mold clamping device according to the present invention is configured to detect the position of the crosshead in the toggle mechanism, and to detect the position of the mold opening / closing servo based on a signal from the detection means, in order to perform the mold clamping force adjustment method The motor is driven to position the crosshead before the dead point, and then the die thickness motor is driven to advance the tail plate so that the position of the crosshead is retracted to a position corresponding to the desired clamping force. When this is detected by the signal of the detection means, the driving of the mold thickness motor is stopped, while the moving mold comes into contact with the fixed mold as the tail plate advances, or at a timing before that, A control means for turning off the mold opening / closing servo motor and allowing the crosshead to move backward is provided, whereby a desired mold and a movable mold are clamped. Characterized in that as clamping force is obtained. In this mold clamping device, the detection means is, for example, an encoder attached to the mold opening / closing servo motor.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the mold clamping force adjusting method and the mold clamping apparatus according to the present invention will be described more specifically with reference to FIGS. 1 to 4 have the same meaning as described in FIGS. 6 and 7.
The mold clamping device is provided with a control device 21 for automatically performing mold clamping force adjustment. The function of the control device 21 will be clarified in the description of the mold clamping force adjusting method described later. In this mold clamping apparatus, the encoder attached to the mold opening / closing servo motor 9 functions as a detection unit that detects the position and the movement amount of the cross head 14 in the toggle mechanism 8. However, the encoder attached to the mold opening / closing servo motor 9 and its function itself are not new.
[0013]
An example of the mold clamping force adjusting method according to the present invention will be described in the order of steps in the flowchart of FIG.
(S1) mold clamping force setting;
After replacing the mold, a clamping force necessary for the replaced mold is input to the control device 21.
(S2) Calculation of crosshead retightening amount;
The control device 21 calculates the crosshead retightening amount (Xmm) corresponding to the set mold clamping force based on the relationship between the crosshead retightening amount and the mold clamping force. As a temporary tightening amount, Z (mm) = X (mm) * Y (%) is calculated. However, Y <100.
(S3) Automatic clamping force adjustment activation;
Start automatic clamping force adjustment. Thereafter, the following steps are automatically advanced by the control device 21.
[0014]
(S4) Crosshead advance (up to Zmm);
The mold opening / closing servo motor 9 is driven in the adjustment mode (= low speed operation), and the cross head 14 is moved forward. A pulse signal of the encoder of the mold opening / closing servo motor 9 is sent to the control device 21 to detect the position and movement amount (tightening amount) of the cross head 14. The amount of tightening of the crosshead 14 in this step is up to Zmm calculated previously. Therefore, even if the cross head 14 moves forward to the limit of the tightening amount (Zmm), the toggle link 12 does not reach the dead point and is slightly bent.
(S5) Mold contact? (Torque measurement);
When the parting surface of the moving mold 6 comes into contact with the parting surface of the fixed mold 2 before the crosshead 14 reaches the limit of the tightening amount (Zmm), the moving mold 6 and the moving die plate 7 → toggle The force is transmitted to the link 12 → the cross head 14 → the ball screw mechanism → the mold opening / closing servo motor 9, and the torque of the mold opening / closing servo motor 9 changes (appears as a change in current value). The torque of the mold opening / closing servo motor 9 is detected by a torque sensor provided in the mold opening / closing servo motor 9, and the detection signal is sent to the control device 21. When the torque changes and reaches a preset value, it is determined that the movable mold 6 is in contact with the fixed mold 2, and the process proceeds to S6.
On the other hand, if no change in torque is detected by the torque sensor until the crosshead 14 reaches the limit of the tightening amount (Zmm), it is determined that the movable mold 6 has not contacted the fixed mold 2, and the process proceeds to S8. The state of the mold clamping device at that time is shown in FIG. As shown in FIG. 1, the crosshead 14 and the toggle link 12 do not reach the dead point, and the toggle link 12 is slightly bent.
[0015]
(S6) Retreating the crosshead;
The mold opening / closing servo motor 9 is driven reversely in the adjustment mode, and the cross head 14 is moved backward by a predetermined distance. Thereby, the state where the movable mold 6 and the fixed mold 2 are in contact with each other is once resolved. If the movable mold 6 and the fixed mold 2 are kept in contact with each other, a slight clamping force is generated, and the tail plate 4 receives the reaction force and is pushed in the direction of extending the tie bar 5. Therefore, a large resistance acts on the mold thickness adjusting mechanism 10 incorporated in the tail plate 4 and the tie bar 5, and the tail plate 4 and the like may not move even when the mold thickness motor 11 is driven. Therefore, in order to proceed to the next S7, it is necessary to once cancel the state where the moving mold 6 and the fixed mold 2 are in contact with each other.
(S7) tail plate retraction;
The mold thickness motor 11 is driven in the adjustment mode, and the tail plate 4, the toggle mechanism 8, the movable die plate 7 and the movable mold 6 are moved backward.
In steps S4 to S7, when the tightening amount is Zmm (a little before the dead point, that is, the toggle link 12 is slightly bent), no torque is applied to the mold opening / closing servo motor 9 (fixed to the movable mold 6). This is a step for creating a state in which the parting surface of the mold 2 is open. If the moving mold 6 and the fixed mold 2 are sufficiently separated from the beginning, the steps S5 to S7 can be omitted.
[0016]
(S8) Tail plate advance;
The mold thickness motor 11 is driven in the adjustment mode, and the tail plate 4, the toggle mechanism 8, the moving die plate 7 and the moving mold 6 are advanced.
(S9) Mold contact? (Torque measurement);
When the moving mold 6 moves forward and its parting surface comes into contact with the parting surface of the fixed mold 2, the torque of the mold opening / closing servo motor 9 changes. The mold thickness motor 11 is continuously driven until a torque change is detected by the torque sensor (same as the torque sensor in S5). When the torque changes and reaches a preset value, the movable mold 6 is fixed. It is determined that it is in contact with the mold 2, and the process proceeds to S10. The state of the mold clamping device at this time is shown in FIG.
[0017]
(S10) Mold opening / closing servo motor OFF;
The torque of the mold opening / closing servo motor 9 is eliminated by turning off the switch of the mold opening / closing servo motor 9. However, the pulse signal of the encoder is sent to the control device 21, and the position detection of the crosshead 14 is continued.
Note that the timing of the mold opening / closing servo motor OFF may be the time before the movable mold 6 contacts the fixed mold 2.
(S11) Tail plate advance;
The mold thickness motor 11 is driven in the adjustment mode, and the tail plate 4 is advanced. Since the movable mold 6 is in contact with the fixed mold, the movable die plate 7 and the movable mold 6 do not move. Due to the pressing force of the tail plate by the mold thickness motor 11, the toggle link 12 is contracted, and the cross head 14 is retracted simultaneously. Since the toggle link 12 is in a slightly bent state, it can be shrunk only by the pressing force. The reason why Zmm is calculated as the provisional additional tightening amount in S2 and the additional tightening amount of the cross head 14 is set to Zmm in S4 is to enable this.
The advancement of the tail plate 4 (drive of the mold thickness motor 11) in this step may be a series of movements following the advancement of the tail plate 4 in S8 (it is not necessary to stop once).
[0018]
(S12) Crosshead Xmm reached? (Position measurement);
The position and amount of movement of the crosshead 14 are detected by the pulse signal of the encoder of the mold opening / closing servomotor 11. When it is detected that the crosshead 14 has retreated from the dead point by an additional tightening amount (X mm), the process proceeds to S13. The state of the mold clamping device at this time is shown in FIG.
(S13) Tail plate stop, mold open / close servo motor ON;
The mold thickness motor 11 is stopped and the tightening amount (Xmm) of the cross head 14 is determined. At the same time, the switch of the mold opening / closing servo motor 9 is turned ON, and the unnecessary movement of the toggle mechanism 8 is sealed by the generated torque.
(S14) Automatic clamping force adjustment completion;
The automatic mold clamping force adjustment controlled by the control device 21 is completed, and the mold thickness motor 11 and the mold opening / closing servo motor 9 are returned from the adjustment mode to the normal mode.
[0019]
【The invention's effect】
According to the mold clamping adjustment method according to the present invention, the movable mold is pressed against the fixed mold by the driving force of the mold thickness motor, that is, the movable mold is pressed in the same direction as the actual mold clamping. Because the crosshead retightening amount is set in the above, it is not affected by backlash or backlash of the mold clamping mechanism. A clamping force can be obtained. Therefore, even after a mold clamping device such as an injection molding machine is used for a long period of time, it is possible to obtain a mold clamping force as set at every adjustment. Moreover, since an encoder is not necessary for the mold thickness motor, the cost is also reduced.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional side view of a mold clamping device according to the present invention.
FIG. 2 is a partial cross-sectional side view of a mold clamping device according to the present invention.
FIG. 3 is a partial cross-sectional side view of a mold clamping device according to the present invention.
FIG. 4 is a diagram showing a control system of the mold clamping device according to the present invention.
FIG. 5 is a flowchart showing an example of a mold clamping force adjusting method according to the present invention.
FIG. 6 is a partial sectional side view (partially omitted) of the mold clamping device.
FIG. 7 is a side view of the mold clamping device.
FIG. 8 is a conceptual diagram showing the relationship between the amount of additional tightening of the cross head and the clamping force.
[Explanation of symbols]
2 fixed mold 3 fixed die plate 4 tail plate 5 tie bar 6 moving mold 7 moving die plate 8 toggle mechanism 9 mold opening / closing servo motor 10 mold thickness adjusting mechanism 11 mold thickness motor 12 toggle link 14 cross head 15 ball screw shaft 17 pulley 18 Tie nut 19 Main gear 21 Control device

Claims (4)

A fixed die plate fixed to the machine base and having a fixed die attached thereto, a tie bar fixed to the fixed die plate and spanned on the tail plate, and a movable die attached to be movable along the tie bar. A movable die plate, a toggle mechanism that is disposed between the movable die plate and the tail plate, moves the movable die plate back and forth along the tie bar, opens and closes the mold, and clamps the mold, and opens and closes the mold that operates the toggle mechanism Servo motor, mold thickness adjusting mechanism for moving the toggle mechanism and moving die plate together with the tail plate by moving the tail plate along the tie bar, and mold thickness for operating the mold thickness adjusting mechanism A motor for opening and closing the mold to open and close the crosshead of the toggle mechanism, In a mold clamping device of a molding machine in which the toggle link of the same mechanism expands and contracts to move the movable die plate back and forth along the tie bar, and is desired when the fixed mold and the movable mold are clamped The mold clamping force adjustment method is such that the mold clamping force can be obtained, and the mold opening / closing servo motor is driven to bring the toggle mechanism into a state before the dead point where the toggle link extends and the mold thickness motor is driven. Then, the tail plate is advanced by the mold thickness adjusting mechanism to bring the moving mold into contact with the fixed mold, and after the moving mold comes into contact with the fixed mold, the mold opening / closing servo motor is turned off. , followed by retracting the crosshead shortens the toggle link by pressing force by the tail plate, retracted position in which the position of the crosshead corresponding to the desired clamping force Clamping force adjustment method in the clamping device, characterized in that stops driving of the type thickness motor when the. The method of adjusting a clamping force of a clamping device according to claim 1 , wherein the position of the crosshead is detected by an encoder attached to the servo motor for opening and closing the die.   A fixed die plate fixed to the machine base and having a fixed die attached thereto, a tie bar fixed to the fixed die plate and spanned on the tail plate, and a movable die attached to be movable along the tie bar. A movable die plate, a toggle mechanism that is disposed between the movable die plate and the tail plate, moves the movable die plate back and forth along the tie bar, opens and closes the mold, and clamps the mold, and opens and closes the mold that operates the toggle mechanism Servo motor, mold thickness adjusting mechanism for moving the toggle mechanism and moving die plate together with the tail plate by moving the tail plate along the tie bar, and mold thickness for operating the mold thickness adjusting mechanism A motor for opening and closing the mold to open and close the crosshead of the toggle mechanism, In a mold clamping device of a molding machine in which the toggle link of the mechanism further expands and contracts to move the movable die plate back and forth along the tie bar, and further detects the position of the crosshead in the toggle mechanism. And a mold opening / closing servo motor to drive the crosshead based on a signal of the detection means to position the crosshead in front of a dead point, and then drive the mold thickness motor to advance the tail plate. When the movement of the mold thickness motor is detected by a signal from the detection means, the driving of the mold thickness motor is stopped. The mold opening / closing servo motor is turned off after the contact with the fixed mold or before it, allowing the crosshead to move backward. Comprising a control means, the mold clamping device, characterized in that as the desired mold clamping force is obtained when the clamping of the movable mold and the fixed mold thereby. 4. The mold clamping apparatus according to claim 3 , wherein the detecting means is an encoder attached to the mold opening / closing servo motor.

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