JP4252789B2 - Control method of toggle link type mold clamping device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control method for a toggle link type mold clamping device suitable for use when a crosshead of a toggle link mechanism is moved forward and backward by a drive unit.
[0002]
[Prior art]
Conventionally, a mold clamping machine that supports a movable mold is opposed to a stationary plate that supports a fixed mold, and a toggle link mechanism is provided between the mold clamping machine and the pressure receiving plate, and a drive unit provided on the pressure receiving plate is used. Toggle link type clamping devices which perform opening / closing and clamping of a fixed mold and a movable mold by moving a crosshead of a toggle link mechanism forward and backward are disclosed in JP-A-5-309707 and JP-A-11-291312. And Japanese Patent Laid-Open No. 2001-301000.
[Patent Document 1]
JP-A-5-309707 [Patent Document 2]
Japanese Patent Laid-Open No. 11-293112 [Patent Document 3]
Japanese Patent Laid-Open No. 2001-301000
[Problems to be solved by the invention]
By the way, when the cross link is moved at a constant speed, the toggle link mechanism normally has a characteristic in which the moving speed of the mold clamping machine is different from the position of the mold clamping machine, as shown by the characteristic curve Pr shown in FIG. Control of moving the mold clamping machine fastest in the middle of the mold clamping stroke and relatively slow before and after that, and moving and stopping the mold clamping machine, which is quite heavy, by the feedback control system Therefore, there is a side where it is difficult to perform smooth and stable control.
[0004]
In particular, when the mold clamping machine is moved and then decelerated or stopped, unstable phenomena such as vibration (shock) and noise are likely to occur, and it is difficult to ensure smooth and stable control. It also causes a decrease. On the other hand, it is possible to deal with the speed control so that such an unstable phenomenon does not occur, but on the other hand, the cycle loss (temporal loss) increases and the production efficiency decreases.
[0005]
The present invention solves such a problem existing in the prior art, can eliminate unstable phenomena such as vibration and noise during deceleration or stop control, further improve durability, and at the same time, An object of the present invention is to provide a control method for a toggle link type mold clamping device capable of increasing production efficiency by reducing cycle loss.
[0006]
[Means for Solving the Problems and Embodiments]
In the control method of the toggle link type mold clamping device 1c according to the present invention, the toggle link mechanism L is disposed between the pressure receiving platen 2 and the mold clamping plate 3, and the drive unit 4 provided in the pressure receiving platen 2 When the mold clamping plate 3 is moved at a predetermined moving speed by moving the cross head Lh forward and backward to perform mold opening / closing and mold clamping, a standard negative acceleration Af and a deceleration time Ts corresponding to the negative acceleration Af are previously stored. In addition, when setting the stable limit speed Vo that does not cause an unstable phenomenon with respect to the moving speed and setting the negative acceleration for the predetermined mold C, the speed command value Dv for the moving speed in the mold C is the stable limit speed. It is determined whether the speed is lower or higher than Vo. If the speed command value is equal to or faster than the stability limit speed Vo, control is performed using the standard negative acceleration Af, and When the speed command value Dv is slower than the stability limit speed Vo, a negative acceleration As (Ass) that is smaller than the standard negative acceleration Af is obtained by calculation from the speed command value Dv and the deceleration time Ts, and the obtained negative acceleration is obtained. Control is performed by As (Ass). In this case, according to a preferred embodiment, the deceleration time Tss due to the negative acceleration As (Ass) that is smaller than the standard negative acceleration Af can be made substantially equal to the preset deceleration time Ts.
[0007]
In addition, the control method of the toggle link type mold clamping device 1c according to another aspect of the present invention is such that a toggle link mechanism L is disposed between the pressure receiving plate 2 and the mold clamping plate 3, and the drive unit 4 provided in the pressure receiving plate 2 is provided. When the mold clamping plate 3 is moved at a predetermined moving speed by moving the cross head Lh of the toggle link mechanism L forward and backward, the mold clamping is performed with respect to the moving speed Vh of the cross head Lh when performing mold opening / closing and clamping. The negative acceleration Afa to be decelerated or stopped at the first position Xa at which the moving speed Vfa of the panel 3 becomes relatively fast is set to an appropriate value, and the moving speed Vfb of the mold clamping machine 3 is set to the moving speed Vh of the crosshead Lh. The negative acceleration Afb of the mold clamping machine 3 to be decelerated or stopped at the relatively slow second position Xb is controlled so as to substantially coincide with the negative acceleration Afa of the mold clamping machine 3 to be decelerated or stopped at the first position Xa. It is characterized by. In this case, according to a preferred embodiment, the appropriate value of the negative acceleration Afa to be decelerated or stopped at the first position Xa can be set to a value that does not cause an unstable phenomenon.
[0008]
【Example】
Next, preferred embodiments according to the present invention will be given and described in detail with reference to the drawings.
[0009]
First, the configuration of a toggle link type mold clamping device 1c capable of performing the control method according to the present embodiment will be described with reference to FIGS.
[0010]
FIG. 3 shows an injection molding machine 1 including a toggle link type mold clamping device 1c and an injection device 1i. The mold clamping device 1c includes a stationary platen 11 and a pressure receiving plate 2 that are spaced apart from each other. The stationary platen 11 is fixed on a machine base (not shown), and the pressure receiving plate 2 can be moved forward and backward on the machine base. Supported. Further, four tie bars 13 are installed between the fixed platen 11 and the pressure receiving platen 2. In this case, the front ends of the tie bars 13 are fixed to the stationary platen 11, and the rear ends of the tie bars 13 are inserted into the pressure receiving plate 2 and screw portions 13s formed on the rear end side. The adjusting nuts 14 that also serve as stoppers for the pressure receiving plate 2 are screwed together.
[0011]
The adjustment nuts 14 constitute a mold thickness adjustment mechanism 15 that adjusts the position of the pressure receiving platen 2, and the mold thickness adjustment mechanism 15 includes an adjustment drive mechanism unit 16 that rotates the adjustment nuts 14. The adjustment drive mechanism unit 16 includes a drive motor 17 and a transmission mechanism unit 18 that simultaneously transmits the rotation of the drive motor 17 to the adjustment nuts 14. Therefore, a timing belt 18b that simultaneously transmits rotation to the four adjustment nuts 14 is bridged over the transmission mechanism 18, and a gear portion integrally formed with each adjustment nut 14 is engaged with the timing belt 18b. The drive gear attached to the shaft of the drive motor 17 is engaged. Further, an incremental encoder 19 for detecting the position of the pressure receiving plate 2 is engaged with the timing belt 18b. Further, a position detection mechanism 20 having position detection switches SWf and SWr using proximity switches or the like for detecting the forward limit position and the backward limit position of the pressure receiving board 2 is disposed between the tie bar 13 and the pressure receiving board 2.
[0012]
On the other hand, the mold clamping machine 3 is slidably loaded on the tie bars 13. The mold clamp 3 supports the movable mold Cm, and the fixed disk 11 supports the fixed mold Cc. A mold C is constituted by the movable mold Cm and the fixed mold Cc.
[0013]
A toggle link mechanism L is disposed between the pressure receiving plate 2 and the mold clamping plate 3. The toggle link mechanism L includes a pair of first links La and La coupled to the pressure receiving plate 2, a pair of output links Lc and Lc coupled to the mold clamping plate 3, and the first links La and La and the output links Lc and Lc. A pair of second links Lb and Lb coupled to the coupling shaft is coupled, and the cross head Lh is coupled to the second links Lb and Lb. Furthermore, a drive unit 4 is disposed between the pressure receiving plate 2 and the cross head Lh. The drive unit 4 includes a ball screw part 21s rotatably supported by the pressure receiving plate 2, and a ball screw mechanism having a ball nut part 21n screwed to the ball screw part 21s and provided integrally with the cross head Lh. 21 and a rotational drive mechanism 22 that rotationally drives the ball screw portion 21s. The rotation drive mechanism unit 22 includes a servo motor 23 and a rotation transmission unit 24 that transmits the rotation of the servo motor 23 to the ball screw unit 21s. In this case, the servomotor 23 is provided with a rotary encoder 25, and the rotation transmitting portion 24 is a driven gear attached to the ball screw portion 21s, a drive gear attached to the shaft of the servomotor 23, and between the drive gear and the driven gear. And a timing belt 24b extending over the belt.
[0014]
On the other hand, reference numeral 31 denotes a controller having a computer function for executing various control processes, arithmetic processes, storage processes, and the like. The drive motor 17 and the servo motor 23 are connected to the output side of the controller 31, and the controller 31 On the input side, an incremental encoder 19, a rotary encoder 25, and position detection switches SWf and SWr are connected. FIG. 4 shows a block system of the controller 31, in particular, a control system block system that can implement the control method according to the present embodiment. The controller 31 broadly includes a command value output unit 32, a motion control unit 33, and a servo amplifier 34, and the motion control unit 33 further includes a control command unit 35, a negative acceleration adjustment unit 36, and a servo control unit 37. .
[0015]
Next, a control method according to the present embodiment using the toggle link type mold clamping device 1c will be described with reference to FIGS.
[0016]
First, in order to facilitate understanding of the control method according to the present embodiment, the operation of the mold clamping process using the mold clamping device 1c will be described together with the operation of the controller 31. Now, it is assumed that the mold C is in the mold open position. In the mold closing operation, the command value output unit 32 gives a position command value Dx, a speed command value Dv, and a negative acceleration command value Da to the control command unit 35. Thereby, the mold clamping machine 3 moves forward based on the speed command value Dv. When the mold clamping machine 3 reaches the deceleration position based on the position command value Dx, deceleration control (slow down control) is performed based on the negative acceleration command value Da. Thereafter, when the mold clamping machine 3 reaches the low pressure start position, the low pressure mold clamping is performed. When the mold clamping machine 3 reaches the low pressure end position where the low pressure mold clamping ends, the high pressure mold clamping by the high pressure control is performed. At this time, a control signal is output from the control command unit 35 and is given to the servo control unit 37, and the output signal of the servo control unit 37 is given to the servo amplifier 33. Further, the output signal of the servo amplifier 33 is It is given to the servo motor 23. On the other hand, the detection signal of the rotary encoder 25 is given to the servo amplifier 33 and the servo control unit 37, respectively, and feedback control is performed on the moving speed and the target position of the mold clamping machine 3.
[0017]
The control method according to the present embodiment is executed in this mold clamping process (mold closing operation). Incidentally, since various molds C having different thicknesses are attached to the mold clamping device 1c, the moving speed for moving the mold clamping machine 3 in the mold closing direction is also set corresponding to the type of the mold C. . FIG. 1 shows the relationship between time and negative acceleration during stop control when the moving speed of the mold clamping machine 3 is varied. Vf is high speed, Vs is low speed, Vss is low speed that is further slower than low speed Vs. ing. When stopping the mold clamping machine 3 moving at each of these speeds, since a constant negative acceleration is normally set, the deceleration characteristics (negative acceleration) at the high speed Vf and the low speed Vs, Vss are represented by the signs Af, The slopes are the same as Asr and Assr. Therefore, a certain amount of deceleration time can be secured when stopping after moving at the high speed Vf, but the deceleration time is shortened when stopping after moving at the low speed Vs, Vss. The amplification action causes unstable phenomena such as vibration (shock) and noise.
[0018]
Therefore, by the control method according to the present embodiment, after the mold clamping machine 3 is moved at the low speed Vs (Vss), the negative acceleration As (Ass) until the stop is moved at the high speed Vf and then stopped. It was made to become smaller than the negative acceleration Af until. Note that, in the relationship between the low speed Vs and Vss, it can be assumed that Vs is high speed and Vss is low speed, and in this case, the relationship of Ass <As is also established.
[0019]
Hereinafter, a specific control method will be described with reference to the flowcharts shown in FIGS. First, in the command value output unit 32, a standard negative acceleration command value Da is set. As the standard negative acceleration command value Da, for example, a negative acceleration with respect to the most frequently used moving speed among the moving speeds of the mold clamping machine 3 can be set, and the negative acceleration Af when moving at a high speed Vf can be set. In particular, it is possible to set a negative acceleration Afa set as an appropriate value described later. On the other hand, in the negative acceleration adjusting unit 36, when the stop is performed at the stability limit speed Vo corresponding to the set negative acceleration Af, i.e., the negative acceleration Af, the slowest instability such as vibration (shock) and noise does not occur. The mold clamping speed is set as the stability limit speed Vo. In addition, the negative acceleration adjusting unit 36 is set with a deceleration time by the stable limit speed Vo and the negative acceleration Af. In the embodiment, the deceleration time Ts is set as the deceleration time. The stability limit speed Vo can be obtained by experiments or the like.
[0020]
Now, a case is assumed where an arbitrary speed command value Dv is given to the negative acceleration adjustment unit 36 (step S1). The negative acceleration adjustment unit 36 determines whether the given speed command value Dv is on the lower speed side or the higher speed side than the stability limit speed Vo (step S2). At this time, when the speed command value Dv is a high speed Vf and is equal to or faster than the stability limit speed Vo, there is no possibility of causing an unstable phenomenon such as vibration (shock) or noise. The negative acceleration Af thus used is used as it is (step S3). On the other hand, when the speed command value Dv is a low speed Vs and is a value slower than the stability limit speed Vo, there is a risk of causing an unstable phenomenon such as vibration (shock) or noise. Therefore, the speed command value Dv (low speed The negative acceleration As is calculated from Vs) and the set deceleration time Ts (step S4). Even when the speed command value Dv is a low speed Vss slower than the low speed Vs, similarly, the negative acceleration As is calculated from the low speed Vss (speed command value Dv) and the set deceleration time Ts (step S4). . Then, the obtained negative acceleration (negative acceleration value) Af, As, Ass is given to the control command unit 35 (step S5).
[0021]
The characteristics shown by the solid line in FIG. 1 indicate these negative accelerations Af, As, and Ass. The negative acceleration to be stopped after the mold clamping machine 3 is moved at a high speed Vf is the set negative acceleration. The negative acceleration to be stopped after moving the mold clamping machine 3 at the low speed Vs becomes the negative acceleration As adjusted (changed) by the negative acceleration adjusting unit 36, and this negative acceleration As is the high speed Vf. It becomes smaller than the negative acceleration Af until it is stopped after being moved by. Further, the negative acceleration to be stopped after moving the mold clamping machine 3 at the low speed Vss is also adjusted (changed) to the negative acceleration Ass by the negative acceleration adjusting unit 36, and the deceleration time Tss at this time is the deceleration time Ts. It almost agrees.
[0022]
Therefore, by such a control method, even if the moving speed of the mold clamping machine 3 is a low speed Vs, the necessary deceleration time Ts is ensured. Therefore, unstable phenomena such as vibration (shock) and noise during stop control are ensured. As a result, it is possible to eliminate the cause of the decrease in durability. In addition, since the necessary deceleration time Tss is ensured even at a low speed Vss that is particularly slow, an unstable phenomenon can be reliably avoided with respect to the moving speed of all the mold clamping machines 3.
[0023]
On the other hand, in the control method according to the present embodiment, when the mold clamping machine 3 is moved at a predetermined high speed or higher and then stopped, the movement speed Vfa of the mold clamping machine 3 with respect to the movement speed Vh of the crosshead Lh. The negative acceleration Afa that stops at the first position Xa where the relative speed becomes relatively high is set to an appropriate value, and the second position where the moving speed Vfb of the mold clamping plate 3 becomes relatively slower than the moving speed Vh of the crosshead Lh. Control is performed so that the negative acceleration Afb of the mold clamping machine 3 stopped at Xb substantially coincides with the negative acceleration Afa of the mold clamping machine 3 stopped at the first position Xa.
[0024]
That is, in the mold clamping device 1c, as indicated by the characteristic curve Pr shown in FIG. 6, the moving speed of the mold clamping machine 3 varies depending on the position of the mold clamping machine 3, and the stop position of the mold clamping machine 3 is around 150 mm. In this case, the speed becomes faster, and when the stop position of the mold clamping machine 3 is around 400 [mm], the speed becomes slower. Therefore, as shown in FIG. 2, it is stopped at the first position Xa (FIG. 6: around 150 mm) where the moving speed Vfa of the mold clamping plate 3 is relatively faster than the moving speed Vh of the crosshead Lh. Even if the negative acceleration Afa is set to an appropriate value, the second position Xb at which the moving speed Vfb of the mold clamping plate 3 becomes relatively slower than the moving speed Vh of the crosshead Lh (FIG. 6: around 400 mm). The negative acceleration Afbr to be stopped at is delayed.
[0025]
Therefore, in the control method according to the present embodiment, the negative acceleration Afb of the mold clamping machine 3 stopped at the second position Xb where the movement speed Vfb of the mold clamping machine 3 becomes relatively slower than the movement speed Vh of the crosshead Lh. Is controlled to substantially coincide with the negative acceleration Afa of the mold clamping machine 3 which is stopped at the first position Xa. That is, Afa = Afb, and the negative accelerations Afa and Afb shown in FIG. In this case, the negative acceleration Afb is obtained by being adjusted (changed) by the negative acceleration adjusting unit 36. The appropriate value of the negative acceleration Afa to be stopped at the first position Xa is set to a value that does not cause instability such as vibration (shock) or noise. This suitability value can be obtained by experiments or the like.
[0026]
Therefore, by such a control method, the negative acceleration Afb of the mold clamping plate 3 is the same as the negative acceleration Afa which is an appropriate value even in the vicinity of 400 mm (position Xb) where the moving speed of the mold clamping plate 3 is the slowest. Therefore, instability phenomena such as vibration (shock) and noise do not occur, and accordingly, the deceleration time is shortened by time Tu (FIG. 2) compared to the case where the control method according to the present embodiment is not performed. And high cycle can be realized by cycle up.
[0027]
Although the embodiments have been described in detail above, the present invention is not limited to such embodiments, and the detailed configuration, method, etc., can be arbitrarily changed, added, or deleted without departing from the spirit of the present invention. can do.
[0028]
For example, the concept of “high speed” and “low speed” does not mean absolute speed, but refers to a relative speed when two speeds are compared. Further, the concept of “substantially coincidence” not only completely coincides but also includes a range in which the effect of the present invention can be obtained even if there is some difference. On the other hand, in the embodiment, the negative acceleration until complete stop has been described. However, when the negative acceleration until deceleration, that is, when slowing down the moving mold clamping machine 3 to a speed (low speed) slower than this, The same applies to the negative acceleration. Moreover, although the Example illustrated the case where the timing belt 18b was used as a means to transmit the rotation of the drive motor 17 to each adjustment nut 14 ... simultaneously, the drive gear attached to the shaft of the drive motor 17 and each adjustment nut 14 ... This can be similarly implemented by engaging one or more intermediate gears using spur gears between the gear portions. Therefore, in this case, the incremental encoder 19 may be engaged with the intermediate gear.
[0029]
【The invention's effect】
Thus, in the present invention, in the control method of the toggle link type mold clamping device, the standard negative acceleration, the deceleration time corresponding to the negative acceleration, and the stable limit speed that does not cause the unstable phenomenon to the moving speed are set in advance. In addition, when setting the negative acceleration for a predetermined mold, it is determined whether the speed command value for the moving speed in the mold is lower or higher than the stability limit speed, and the speed command value When the value is equal to or faster than the stability limit speed, control is performed using standard negative acceleration, and when the speed command value is slower than the stability limit speed, the standard negative acceleration is calculated from the speed command value and deceleration time. Since the negative acceleration smaller than the acceleration is obtained by calculation and the control is performed by the obtained negative acceleration, the following remarkable effects are obtained.
[0030]
(1) Even if the moving speed of the mold clamping machine is low, the necessary deceleration time is secured, and the occurrence of unstable phenomena such as vibration (shock) and noise during deceleration or stop control can be eliminated. At the same time, durability can be improved.
[0031]
(2) The negative acceleration to be decelerated or stopped at the first position where the moving speed of the mold clamping machine is relatively faster than the moving speed of the crosshead is set to an appropriate value, and the mold clamping is set to the moving speed of the crosshead. In order to control the negative acceleration of the mold clamping machine to be decelerated or stopped at the second position where the moving speed of the machine is relatively slow, so as to substantially match the negative acceleration of the mold clamping machine to be decelerated or stopped at the first position. A high cycle can be realized by cycle-up while avoiding the occurrence of unstable phenomena such as vibration (shock) and noise during deceleration or stop control.
[0032]
(3) According to a preferred embodiment, if the deceleration time due to the negative acceleration that is smaller than the standard negative acceleration is made to substantially match the preset deceleration time, the required deceleration even if the speed is particularly slow. Time can be secured, so that an unstable phenomenon can be surely avoided with respect to the moving speed of all the mold clamping machines.
[Brief description of the drawings]
FIG. 1 is a diagram showing the moving speed characteristics of a clamping machine versus time when controlled by a control method according to a preferred embodiment of the present invention;
FIG. 2 is another time vs. moving speed characteristic diagram of the clamping machine when controlled by the same control method;
FIG. 3 is a block diagram of a toggle link type mold clamping device that can implement the control method;
FIG. 4 is a block system diagram of a controller provided in the toggle link type mold clamping device;
FIG. 5 is a flowchart showing processing in the control method;
FIG. 6 is a diagram of the position of the mold clamping plate of the toggle link type mold clamping device used in the control method versus the moving speed characteristic of the mold clamping plate;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1c Toggle link type clamping device 2 Pressure receiving board 3 Mold clamping machine 4 Drive part L Toggle link mechanism Lh Crosshead C Die Dv Speed command value Af Standard negative acceleration Afa Negative acceleration As Negative acceleration As Negative acceleration Ts Deceleration time Tss Deceleration Time Vh Crosshead moving speed Vfa Die moving speed Vfb Die moving speed Xa 1st position Xb 2nd position

Claims (4)

  A toggle link mechanism is disposed between the pressure receiving plate and the mold clamping plate, and the mold clamping plate is moved at a predetermined moving speed by moving the crosshead of the toggle link mechanism forward and backward by a drive unit provided in the pressure receiving plate. In a control method of a toggle link type mold clamping device that performs mold opening / closing and mold clamping, a standard negative acceleration, a deceleration time corresponding to the negative acceleration, and a stable limit speed that does not cause an unstable phenomenon with respect to the moving speed are previously obtained. When setting the negative acceleration for a predetermined mold, it is determined whether the speed command value for the moving speed in the mold is a lower speed side or a higher speed side than the stability limit speed. When the speed command value is equal to or faster than the stable limit speed, control is performed with the standard negative acceleration, and the speed command value is lower than the stable limit speed. A toggle link type clamping device characterized in that a negative acceleration that is smaller than the standard negative acceleration is calculated from the speed command value and the deceleration time, and control is performed using the obtained negative acceleration. Control method.   2. The method for controlling a toggle link type mold clamping apparatus according to claim 1, wherein a deceleration time due to a negative acceleration smaller than the standard negative acceleration substantially matches a preset deceleration time.   A toggle link mechanism is disposed between the pressure receiving plate and the mold clamping plate, and the mold clamping plate is moved at a predetermined moving speed by moving the crosshead of the toggle link mechanism forward and backward by a drive unit provided in the pressure receiving plate. Then, in a control method of a toggle link type mold clamping device that performs mold opening / closing and mold clamping, the mold clamping plate is decelerated or stopped at a first position where the movement speed of the mold clamping plate is relatively higher than the movement speed of the cross head. The negative acceleration is set to an appropriate value, and the negative acceleration of the mold clamping machine that is decelerated or stopped at a second position where the movement speed of the mold clamping machine is relatively slow with respect to the movement speed of the crosshead is A control method for a toggle link type mold clamping device, wherein control is performed so as to substantially coincide with the negative acceleration of the mold clamping machine decelerated or stopped at one position.   The method for controlling a toggle link type mold clamping apparatus according to claim 3, wherein an appropriate value of the negative acceleration to be decelerated or stopped at the first position is set to a value at which an unstable phenomenon does not occur.

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