JP4313259B2 - Mold thickness adjustment method for toggle type mold clamping device - Google Patents

Description

  The present invention relates to a mold thickness adjusting method for a toggle type mold clamping apparatus that performs mold thickness adjustment by moving a pressure receiving plate to a predetermined position.

  In general, a toggle type mold clamping device for clamping a mold provided in an injection molding machine uses a toggle link mechanism to connect between a movable plate that supports a movable die and a crosshead that moves forward and backward by a drive unit supported by a pressure receiving plate. The crosshead has a function of increasing the pressure applied to the crosshead and transmitting it to the movable platen, and a predetermined mold clamping force is generated based on the extension of the tie bar when the toggle link mechanism is almost extended. For this reason, when the mold is replaced, it is necessary to set the position of the pressure receiving plate so that a predetermined clamping force is generated. Usually, the position of the pressure receiving plate is automatically set by the mold thickness adjusting device. The

Conventionally, as a mold thickness adjusting method using this type of mold thickness adjusting apparatus, an automatic mold thickness adjusting method for an injection molding machine disclosed in Japanese Patent No. 2668599 is known. This automatic mold thickness adjustment method is an automatic mold thickness adjustment method for an injection molding machine having a toggle type mold clamping device that moves the rear platen backward while pressing the mold with the output torque of the servo motor for mold clamping, The pressure applied to the mold is detected by the mold pressure detection means provided in the mold clamping device, and the difference between the command value and the output of the mold pressure detection means is feedback controlled as the torque limit value of the mold clamping servo motor. The mold plate thickness adjustment is performed by moving the rear platen while limiting the pressure applied to the mold to a predetermined pressure or less.
Japanese Patent No. 2668599

  However, the mold thickness adjusting method of the conventional toggle type mold clamping device described above has the following problems.

  First, because the rear platen (pressure platen) is moved backward while pressing the mold with the output torque of the servo motor for clamping, the overall control becomes complicated and the time required for mold thickness adjustment increases. As a result, work man-hours increase and production efficiency decreases.

  Second, because the mold thickness adjustment is performed by an operation that is significantly different from the operation in the original mold clamping process, there is room for errors due to the difference in operation, and sufficient accuracy and stability cannot be ensured.

  An object of the present invention is to provide a mold thickness adjusting method for a toggle type mold clamping device that solves the problems existing in the background art.

  In the mold thickness adjusting method of the toggle type mold clamping device Mc according to the present invention, when the mold thickness adjustment is performed by moving the pressure receiving plate 2 to a predetermined position, the pressure receiving plate 2 is moved backward while the toggle link mechanism 3 is extended. The first step T1 is advanced from the position Xr at the first speed Vh, and when the pressure receiving plate 2 reaches the mold closing position Xc, the first step T1 is moved backward, and after this first step, the pressure receiving plate 2 is moved to the first speed. Advance at a second speed Vs set to 10 to 30% of Vh. When the mold closing position Xc is reached, the toggle link mechanism 3 is bent to open the mold by a predetermined distance Lr. A second step T2 is provided in which the pressure receiving platen 2 is advanced by a distance Lc corresponding to a clamping allowance for obtaining a target mold clamping force.

  In this case, according to a preferred aspect of the invention, the first step T1 performs the mold opening by a predetermined distance Lp by bending the toggle link mechanism 3 when the pressure receiving plate 2 reaches the mold closing position Xc. The toggle link mechanism 3 can be extended after the pressure platen 2 is retracted by a predetermined distance Ls. The second speed Vs can be used as the speed at which the pressure receiving platen 2 is moved forward by a distance Lc corresponding to the tightening allowance in the second step T2. Further, a geared motor 4 incorporating a reduction gear mechanism is used as a drive source for moving the pressure receiving platen 2, and the second speed Vs can be set by lowering the power supply frequency for driving the geared motor 4.

  According to the mold thickness adjusting method of the toggle type mold clamping device Mc according to the present invention by such a method, the following remarkable effects are obtained.

  (1) A first step T1 for moving the pressure receiving plate 2 forward from the reverse position Xr at a first speed Vh that is high speed, and a second speed Vs that is low speed by a set small distance Ls after the first step. Unlike the conventional method in which the rear platen is moved in a state where the mold is in contact with the rear platen because the second step T2 is advanced in the step, the man-hours are reduced and the production efficiency is improved by reducing the time required for adjusting the die thickness. Can be achieved.

  (2) Since the mold thickness can be adjusted by almost the same operation as in the original mold clamping process, there is no room for errors due to the difference in operation, and sufficient accuracy and stability can be secured. it can.

  (3) Since the second speed Vs is set to 10 to 30% of the first speed Vh, both the shortening of the mold thickness adjusting operation time and the accuracy and stability of the set clamping force are optimally achieved. Can be made.

  (4) According to a preferred embodiment, the first step T1 is carried out by bending the toggle link mechanism 3 when the pressure receiving plate 2 reaches the mold closing position Xc, and opening the mold by a predetermined distance Lp. If the toggle link mechanism 3 is extended after the board 2 is retracted by a predetermined distance Ls, a geared motor 4 having a small output torque is used as a drive source for moving the pressure receiving board 2. Thus, the problem of being unable to move backward by so-called tightening when reaching the mold closing position Xc can be avoided, and the next operation can be surely shifted.

  (5) According to a preferred embodiment, if the second speed Vs is used as the speed at which the pressure receiving platen 2 is moved forward by the distance Lc, the tightening allowance required for accuracy can be set with high accuracy.

  (6) According to a preferred embodiment, a geared motor 4 incorporating a reduction gear mechanism is used as a drive source for moving the pressure receiving platen 2, and the second speed Vs is set by lowering the power supply frequency for driving the geared motor 4. Then, even if the geared motor 4 is used, speed switching (speed change) can be easily performed.

   Next, the best embodiment according to the present invention will be given and described in detail with reference to the drawings.

  First, the configuration of a toggle type mold clamping device Mc capable of performing the mold thickness adjusting method according to the present embodiment will be described with reference to FIGS.

  In FIG. 2, the injection molding machine indicated by M includes a toggle type mold clamping device Mc and an injection device Mi. The toggle type mold clamping device Mc includes a fixed platen 21 and a pressure platen 2 that are spaced apart from each other. The fixed platen 21 is fixed on a machine base (not shown), and the pressure platen 2 moves forward and backward on the machine table. Supported as possible. Further, four tie bars 22 are installed between the fixed platen 21 and the pressure receiving platen 2. In this case, the front ends of the tie bars 22 are fixed to the fixed platen 21 and the rear ends of the tie bars 22 are inserted through the pressure receiving plate 2.

  On the other hand, the movable platen 23 is slidably loaded on the tie bars 22. The movable platen 23 supports the movable mold Cm, the fixed platen 21 supports the fixed mold Cc, and the movable mold Cm and the fixed mold Cc constitute a mold C. Further, a toggle link mechanism 3 is disposed between the pressure receiving plate 2 and the movable platen 23. The toggle link mechanism 3 includes a pair of first links 3a and 3a that are pivotally supported on the pressure receiving plate 2, a pair of output links 3c and 3c that are pivotally supported on the movable plate 23, the first links 3a and 3a, and the output link 3c, A pair of second links 3 b and 3 b coupled to the support shaft of 3 c is provided, and the second links 3 b and 3 b are pivotally supported on the cross head 24.

  A mold clamping drive unit 25 is disposed between the pressure receiving platen 2 and the cross head 24. The mold clamping drive unit 25 includes a ball screw portion 26 that is rotatably supported by the pressure receiving plate 2, and a ball nut portion 27 that is screwed into the ball screw portion 26 and is provided integrally with the cross head 24. A ball screw mechanism 28 is provided, and a rotation drive mechanism 29 that rotates the ball screw 26 is provided. The rotation drive mechanism 29 includes a mold clamping servo motor 30, a rotary encoder 31 attached to the servo motor 30 for detecting the rotation speed of the servo motor 30, and a drive gear 32 attached to the shaft of the servo motor 30. A driven gear 33 attached to the ball screw portion 26 and a timing belt 34 spanned between the drive gear 32 and the driven gear 33 are provided.

  Accordingly, when the servo motor 30 is operated, the drive gear 32 is rotated, and the rotation of the drive gear 32 is transmitted to the driven gear 33 via the timing belt 34, and the ball screw portion 26 is rotated to thereby rotate the ball nut. Part 27 moves forward and backward. As a result, the cross head 24 integrated with the ball nut portion 27 moves forward and backward, the toggle link mechanism 3 bends or extends, and the movable platen 23 moves forward and backward in the mold opening direction (retracting direction) or the mold closing direction (forward movement direction). To do.

  On the other hand, the mold thickness adjusting device 1 is attached to the pressure receiving plate 2. The mold thickness adjusting apparatus 1 includes screw mechanisms 38 formed by forming screw portions 36 on the rear end sides of the four tie bars 22 and screwing adjustment nuts 37 to the screw portions 36. In this case, the adjusting nuts 37 also serve as stoppers for the pressure receiving plate 2. Accordingly, when the adjustment nuts 37 are rotated, they are displaced relative to the screw portions 36, so that the pressure receiving platen 2 can be moved back and forth.

  A geared motor 4 serving as a drive source for moving the pressure receiving plate 2 is attached to the side surface of the pressure receiving plate 2. The geared motor 4 serves as a mold thickness adjusting drive motor. The geared motor 4 includes a motor main body 41. The motor main body 41 includes a motor unit using an induction motor provided in the second half, and a reduction gear mechanism for inputting rotation of the motor unit provided in the first half. The output shaft 42 that outputs the rotation of the reduction gear mechanism projects from the front end surface of the motor main body 41. Further, a motor shaft in the motor unit protrudes from the rear end surface of the motor main body 41, a motor brake unit 43 that locks or unlocks the position of the motor shaft, and a rotary encoder unit 44 that detects the rotational speed of the motor shaft. Is attached. The rotary encoder 44 can detect an absolute position based on the number of encoder pulses generated with respect to a reference position using an incremental encoder. In addition, since the rotary encoder part 44 and the motor brake part 43 are assembled | attached integrally with the motor main-body part 41, it can contribute to the whole size reduction compactness similarly to the servomotor with an encoder.

  On the other hand, as shown in FIGS. 3 and 4, a drive gear 51 is attached to the front end side of the output shaft 42, and small gears 52 are integrally attached to the adjustment nuts 37, respectively. In this case, the adjustment nuts 37 and the small gears 52 are coaxially positioned. Further, a large gear 53 that meshes with each small gear 52... And the drive gear 51 is disposed. The large gear 53 is formed in a ring shape, and a rail portion provided along the inner peripheral surface is supported by four support rollers 54 attached to the pressure receiving platen 2. That is, the small gears 52 are arranged at the four corners of the square, and the large gears 53 are arranged at positions surrounded by the small gears 52, so that the small gears 52 mesh with the large gears 53 at the same time. To do.

  Therefore, when the geared motor 4 is operated, the large gear 53 is rotated by the rotation of the drive gear 51, and the small gears 52 are simultaneously rotated by the rotation of the large gear 53. Since the adjustment nuts 37 that rotate integrally with the small gears 52 advance and retract along the screw portions 36 of the tie bars 22, the pressure receiving platen 2 also moves forward and backward, and its front-rear direction position is adjusted. . Reference numeral 61 denotes a molding machine controller, which connects the mold clamping servo motor 30, the rotary encoder 31, the geared motor 4, the motor brake unit 43, and the rotary encoder unit 44.

  Next, a mold thickness adjusting method according to this embodiment using such a mold thickness adjusting apparatus 1 will be described with reference to FIGS.

  FIG. 1 is a flowchart showing a processing procedure of the mold thickness adjusting method. The mold thickness adjustment is normally performed when the mold C is replaced, and a series of operations and processes based on the mold thickness adjustment method are automatically performed. For this reason, a sequence program for executing the same mold thickness adjusting method is set in the molding machine controller 61, and the operations of the mold clamping servo motor 30 and the geared motor 4 are sequence-controlled in accordance with this sequence program, and various processes are performed. Executed.

  First, the operation of the geared motor 4 is controlled to retract the pressure receiving platen 2 to the retracted position Xr (step S1). The reverse speed at this time is a normal speed based on the power supply frequency of 60 Hz. Further, at the retracted position Xr, the mold clamping servomotor 30 is controlled to be in a state where the toggle link mechanism 3 is extended (a state where it is fully extended) (step S2). This state is shown in FIG. In this case, the retracted position Xr is set to the last retracted position. However, since a predetermined gap may be generated between the movable mold Cm and the fixed mold Cc in a state where the toggle link mechanism 3 is extended, the retracted position Xr is not necessarily the last retracted position. It doesn't have to be a position.

  Next, the operation of the geared motor 4 is controlled, and the pressure receiving platen 2 is advanced in the direction of the arrow Ffp shown in FIG. 6 (step S3). The forward speed in this case is the first speed Vh that is high. The first speed Vh is a normal speed based on the power supply frequency 60 Hz for driving the geared motor 4. When the mold closing position Xc is reached, the pressure receiving platen 2 is stopped (steps S4 and S5). This state is shown in FIG. Therefore, the pressure receiving plate 2 moves at a normal speed (first speed Vh) at a high speed over a distance Lf from the retracted position Xr, which is a relatively long distance section, to the mold closing position Xc. The mold closing position Xc is a position where the movable mold Cm and the fixed mold Cc touch, and can be detected by the following method, for example. That is, the load torque fluctuation amount associated with the closing of the mold C is sequentially detected, and the fluctuation rate of the load torque with respect to the constant movement amount is sequentially obtained, so that the position when the fluctuation rate reaches a preset setting rate. Is detected as the mold closing position Xc.

  Next, the mold clamping servo motor 30 is controlled to bend the toggle link mechanism 3, whereby the movable platen 23 is retracted by a predetermined distance Lp in the direction of the arrow Fr shown in FIG. Step S6). This mold opening is for the following reason. As described above, when the pressure receiving plate 2 is moved forward at the first speed Vh that is a high speed and the movable mold Cm and the fixed mold Cc are touched at the mold closing position Xc, so-called tightening occurs due to inertia during forward movement. Thereafter, even if the geared motor 4 is controlled to retract the pressure receiving plate 2, it cannot move. In particular, since the momentum and acceleration are proportional, the amount of tightening (the amount of movement until stopping) is proportional to the square of the speed, and when moving at the first speed Vh that is high, the amount of tightening is ignored. When the geared motor 4 having a small output torque is used as a drive source for moving the pressure receiving platen 2, the tightening cannot be released. Therefore, the mold clamping servo motor 30 is controlled and the toggle link mechanism 3 is bent to release the tightening. Therefore, in this case, the distance Lp for retracting the movable platen 23 is sufficient, and can be set to about several [mm], preferably around 4 [mm]. Thereby, when reaching the mold closing position Xc and stopping the pressure receiving platen 2, it is possible to avoid the problem of being unable to move backward due to tightening, and it is possible to reliably shift to the next operation.

  Next, the geared motor 4 is controlled, and the pressure receiving platen 2 is moved backward by a predetermined distance Ls in the direction of the arrow Frp shown in FIG. 7 (step S7). In this case, the first speed Vh described above can be used as the reverse speed. As described above, when advanced at the first speed Vh, which is a high speed, tightening occurs at the mold closing position Xc. This tightening amount is, for example, an error when setting (adjusting) the mold clamping force. As a result, the reproducibility of the mold clamping force becomes worse, and in particular, a low mold clamping force cannot be set. Therefore, in the present embodiment, the pressure receiving platen 2 that has reached the mold closing position Xc at the first speed Vh is once retracted, and then re-advanced at a slow speed. Therefore, the predetermined distance Ls may be a small distance that can realize this processing, and can be set to about several [mm], preferably around 2 [mm].

  If the pressure receiving platen 2 is moved backward by the predetermined distance Ls, the mold clamping servomotor 30 is controlled to extend the toggle link mechanism 3 (step S8). As a result, the movable platen 23 moves forward in the arrow Ff direction by the same distance as the distance Lp described above. This state is shown in FIG. Therefore, a gap having the same distance as the above-described distance Ls is generated between the movable mold Cm and the fixed mold Cc. The above is the first step T1. After the first step T1, the following second step T2 is performed.

  In the second step T2, first, the geared motor 4 is controlled to advance the pressure receiving plate 2 in the direction of the arrow Ffp shown in FIG. 9 (step S9). The forward speed in this case is the second speed Vs that is low. The second speed Vs is set to a fine speed of about 10 to 30% of the first speed Vh. That is, since the first speed Vh is set based on the power supply frequency 60 Hz for driving the geared motor 4, this power supply frequency is set to a low value, specifically about 6 to 18 Hz, preferably about 10 Hz. In this way, by setting the second speed Vs to 10 to 30% of the first speed Vh, the time for the mold thickness adjustment work is shortened and the accuracy and stability with respect to the set clamping force are optimized. It is possible to make it compatible with the state. Note that by setting the second speed Vs by lowering the power supply frequency for driving the geared motor 4, speed switching (speed change) can be easily performed even when the geared motor 4 is used.

  When the mold closing position Xc is reached, the pressure receiving platen 2 is stopped (steps S10 and S11). This state is shown in FIG. Therefore, the pressure platen 2 moves forward at a slow speed over a distance Ls that is a relatively short distance section. In this case, since the distance Ls is small, the moving time is short even at a very low speed. Further, since the vehicle moves forward at a slow speed, the impact when reaching the mold closing position Xc is reduced and a stable operation is ensured, and in particular, the tightening amount described above can be greatly reduced. That is, the second speed Vs is set to 10 to 30% of the first speed Vh, and the tightening amount is proportional to the square of the speed, and can be reduced to about 1/100 to 1/10. . As a result, the variation in the mold clamping force set by the mold thickness adjustment is about 2 to 5% when performed only at the first speed Vh, whereas the second variation as in the present embodiment. By carrying out by adding the speed Vs, it was able to be improved to about 0.1-0.2 [%].

  Next, the mold clamping servo motor 30 is controlled to bend the toggle link mechanism 3 so that the movable platen 23 is retracted by a predetermined distance Lr in the direction of the arrow Fr shown in FIG. Step S12). In this case, the distance Lr is a movement for setting a fastening allowance described later, and a distance that can secure at least the fastening allowance is selected. Specifically, it can be set to about 4 mm, which is about the same as the distance Lp described above. Then, the geared motor 4 is controlled, and the pressure receiving platen 2 is advanced by a distance Lc corresponding to a clamping allowance for obtaining a target mold clamping force in the direction of arrow Ffp shown in FIG. 10 (step S13). The advance speed in this case uses the second speed Vs described above. By using the second speed Vs, it is possible to set the tightening allowance for which accuracy is required with high accuracy. Since the relationship between the distance when the movable platen 23 is moved forward from the mold closing position Xc and the clamping force is set in advance, the distance Lc corresponding to the clamping allowance for obtaining the target clamping force is selected. be able to. Thereafter, by controlling the mold clamping servomotor 30 and extending the toggle link mechanism 3, high-pressure mold clamping can be performed. Thereby, mold thickness adjustment is completed (step S14).

  As described above, the mold thickness adjusting method according to the present embodiment includes the first step T1 for moving the pressure receiving plate 2 forward from the retreat position Xr at the first speed Vh, and is set after the first step. Unlike the conventional method in which the rear platen is moved in a state where the mold is in contact with the rear platen because the second step T2 is advanced at the second speed Vs, which is a low speed by a small distance Ls, the overall control is simple. It is possible to reduce the number of work steps and improve the production efficiency by shortening the time required for mold thickness adjustment. In addition, since the mold thickness can be adjusted by substantially the same operation as that in the original mold clamping process, it is possible to eliminate room for errors due to the difference in operation, and to ensure sufficient accuracy and stability. .

  As described above, the best embodiment has been described in detail, but the present invention is not limited to such an embodiment, and the details, methods, configurations, numerical values, and the like are within the scope not departing from the gist of the present invention. It can be changed, added, or deleted arbitrarily. For example, in the first step T1, when the pressure receiving plate 2 reaches the mold closing position Xc, the toggle link mechanism 3 is bent to open the mold by a predetermined distance Lp, and thereafter, the pressure receiving plate 2 is moved to the predetermined distance. A step of extending the toggle link mechanism 3 after retreating by Ls is provided, but tightening that occurs, such as using a large high-torque motor for the drive source (geared motor 4) for moving the pressure receiving plate 2, is provided. If it can be solved, this step can be omitted. Moreover, when using a servomotor for the drive source which moves the pressure receiving board 2, the 1st speed Vh and the 2nd speed Vs by servo control can be set.

The flowchart which shows the process sequence of the mold thickness adjustment method which concerns on the best embodiment of this invention, A plan view of a toggle type clamping device capable of performing the same mold thickness adjustment method, Side configuration diagram showing the main part of a mold thickness adjusting device provided in the toggle type mold clamping device, Rear view showing the main part of the same thickness adjustment device, Explanatory drawing of processing steps when performing mold thickness adjustment by the same mold thickness adjustment method, Other process steps explanatory diagram when performing mold thickness adjustment by the same mold thickness adjustment method, Other process steps explanatory diagram when performing mold thickness adjustment by the same mold thickness adjustment method, Other process steps explanatory diagram when performing mold thickness adjustment by the same mold thickness adjustment method, Other process steps explanatory diagram when performing mold thickness adjustment by the same mold thickness adjustment method, Other process steps explanatory diagram when performing mold thickness adjustment by the same mold thickness adjustment method,

Explanation of symbols

2 Pressure receiving plate 3 Toggle link mechanism 4 Geared motor Mc Toggle type clamping device Xr Retraction position Xc Mold closing position Vh 1st speed Vs 2nd speed T1 1st process T2 2nd process Ls distance Lr distance Lc distance Lp distance

Claims (4)

  In the mold thickness adjusting method of the toggle type mold clamping device for adjusting the mold thickness by moving the pressure receiving plate to a predetermined position, the pressure receiving plate is moved forward from the retracted position at the first speed while the toggle link mechanism is extended, When the pressure receiving plate reaches the mold closing position, the first step of moving back by a predetermined distance, and after this first step, the pressure receiving plate is set at a second speed set to 10 to 30% of the first speed. When the die closing position is reached, the toggle link mechanism is bent to open the die for a predetermined distance, and thereafter, the pressure receiving plate for a distance corresponding to a clamping allowance for obtaining a target clamping force. A mold thickness adjusting method for a toggle type mold clamping apparatus, comprising a second step of moving the mold forward.   In the first step, when the pressure receiving plate reaches the mold closing position, the toggle link mechanism is bent to open the mold by a predetermined distance, and thereafter, the pressure receiving plate is moved backward by a predetermined distance. 2. The mold thickness adjusting method for a toggle type mold clamping apparatus according to claim 1, wherein the toggle link mechanism is extended afterwards.   2. The mold thickness adjusting method for a toggle type mold clamping apparatus according to claim 1, wherein the second speed is used as a speed at which the pressure receiving plate is advanced by a distance corresponding to the clamping allowance in the second step.   2. A geared motor having a built-in reduction gear mechanism is used as a drive source for moving the pressure platen, and the second speed is set by lowering a power supply frequency for driving the geared motor. Mold thickness adjusting method for toggle type mold clamping device.

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