JP2006159440A - Mold clamping method of toggle type mold clamping device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To always achieve the certain protection of a mold without being affected by the magnitude of set mold clamping force and to detect the accurate closing position of a movable platen. <P>SOLUTION: Predetermined mold clamping force not larger than the maximum mold clamping force is preset as a changeover value Pc and, when a molding clamping force Pd becoming lower than the changeover value Pc is set, the position of a crosshead 2 is controlled by setting a toggle link machanism 4 to a non-lock-up state Xn to perform mold clamping and, when mold clamping force Pu exceeding the changeover value Pc is set, the toggle link machanism 4 is set to a lock-up state Xu by adjusting the position of a pressure receiving platen 5 to perform mold clamping. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mold clamping method of a toggle type mold clamping device suitable for use in a toggle type mold clamping device in which a toggle link mechanism is interposed between a cross head and a movable platen.

  In general, a toggle type mold clamping device for clamping a mold provided in an injection molding machine is known (Japanese Patent Laid-Open No. 62-32020). The toggle type mold clamping device has a function of connecting the movable plate supporting the movable die and the crosshead moving forward and backward by the drive unit by a toggle link mechanism, and increasing the pressure applied to the crosshead and transmitting it to the movable platen. Therefore, a predetermined clamping force is generated based on the extension of the tie bar when the toggle link mechanism is almost extended. In this case, in the mold clamping operation, the high-speed mold closing is usually performed from the mold opening position, and when the preset low-speed switching position is reached, the process shifts to the low-speed mold closing. This low-speed mold closing becomes a mold protection section (foreign matter detection section), and a molded product or the like that has not been normally discharged is detected as a foreign matter. When the preset high pressure switching position is reached, the high pressure mold clamping is performed by shifting to the high pressure mold clamping.

  By the way, the clamping force when performing high-pressure clamping is usually set to the rated clamping force (maximum clamping force), but it is not necessarily set to the rated clamping force depending on the form of the molded product, molding conditions, etc. In this case, it may be desirable to set it smaller than the rated clamping force from the viewpoint of energy saving.

Conventionally, as a method for setting a mold clamping force, an automatic mold clamping force setting method for a toggle type mold clamping device disclosed in Japanese Patent Laid-Open No. 4-86207 is known. In this method, a pressure platen position control means is provided at a predetermined location together with a pressure platen position detector, and when setting the mold clamping force, the mold thickness and mold clamping force are set, and the set mold is determined from those set values. Calculate and set the setting position of the pressure receiving plate that generates the tightening force, move the pressure receiving plate by the pressure receiving plate position control means, and when the set value is reached, stop the movement of the pressure receiving plate and set the stop position of the pressure receiving plate. The detected value is compared with the pressure platen setting position, and it is determined whether the value is an allowable value. If the value is an allowable value, the mold clamping force setting process is terminated. When changing the tightening force, it is automatically changed by changing the set value.
JP-A-62-232020 JP-A-4-86207

  However, the method for changing the mold clamping force using the above-described conventional automatic mold clamping force setting method has the following problems to be solved.

  First, the toggle link mechanism normally has an enlargement ratio characteristic with respect to the mold position (position of the movable platen) as shown in FIG. The enlargement ratio indicates (the amount of movement of the cross head / the amount of movement of the movable plate) × 100 [%], and the pressure applied by the cross head can be increased and transmitted to the movable plate. Therefore, when the mold clamping force is set to be small by moving the position of the pressure receiving plate in a direction away from the fixed platen, the mold clamping force becomes smaller in the mold protection section before the movable plate reaches the closed position. The enlargement ratio (degree of pressure increase) is increased, resulting in a problem that the mold cannot be protected substantially.

  Secondly, in order to accurately detect the closing position of the movable platen, when trying to detect the closing position of the movable platen based on the fluctuation of the physical quantity (load torque, etc.) accompanying the mold closing, Depending on the physical quantity, as shown in FIG. 6, the smaller the mold clamping force, the smaller the fluctuation. For this reason, when the mold clamping force is reduced to about 20%, the fluctuation of the load torque at that time does not reach the threshold value Ts as shown by the characteristic line of To in the figure, and the movable platen is closed. This causes a problem that position detection is virtually impossible.

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

  In order to solve the above-described problem, the toggle type clamping apparatus according to the present invention has a toggle link mechanism 4 interposed between the cross head 2 and the movable platen 3, so that the movement amount of the movable platen 3 and the crosshead can be adjusted. In a toggle type mold clamping device Mc that increases the pressure of the crosshead 2 and transmits it to the movable platen 3 by generating a predetermined enlargement ratio between the movement amounts, a predetermined mold clamping smaller than the maximum mold clamping force in advance. When the force is set as the switching value Pc and the mold clamping force Pd that is equal to or less than the switching value Pc is set, the position of the crosshead 2 is controlled by setting the toggle link mechanism 4 to the unlocked state Xn and the mold clamping is performed. When the mold clamping force Pu exceeding the switching value Pc is set, the position of the pressure receiving platen 5 is adjusted so that the toggle link mechanism 4 is brought into the lock-up state Xu and the mold clamping is performed. That.

  In this case, according to a preferred aspect of the invention, the switching value Pc can be set to a predetermined value of 60% or less of the maximum mold clamping force. Further, the position control of the cross head 2 for setting the mold clamping force Pd that is equal to or less than the switching value Pc is performed by using the clamping plate Am or the clamping plate Am that generates the predetermined mold clamping force Pm in advance in the lock-up state Xu. The reference additional amount Bm of the crosshead 2 corresponding to the above is obtained, and the set additional amount Bs of the crosshead 2 that generates the set clamping force Pd is obtained by calculation from the reference additional amount Bm or the closing margin Am. The position can be controlled based on the set additional amount Bs. On the other hand, the position adjustment of the pressure receiving platen 5 for setting the mold clamping force Pu exceeding the switching value Pc is performed by moving the pressure receiving platen 5 by the mold thickness adjusting mechanism 6 so as to obtain a clamping white Au corresponding to the mold clamping force Pu. The position can be adjusted. On the other hand, a closed position detection mode for obtaining the position (closed position) of the movable platen 3 based on a change in physical quantity accompanying the closing of the mold 7 is provided, and the mold clamping of the target value is performed by executing the closed position detection mode in advance. The closed position where force is obtained is set as the reference value Ds, and the actual closed position (detected value Dd) is obtained by executing the closed position detection mode during production operation, and the deviation between the detected value Dd and the reference value Ds The mold clamping force can be corrected based on E. At this time, when the mold clamping force to be corrected is equal to or less than the switching value Pc, the deviation E can be reflected in the position control of the crosshead 2, and when the mold clamping force to be corrected exceeds the switching value Pc, The deviation E can be reflected in the position adjustment of the movable platen 3.

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

  (1) When performing mold clamping by setting a mold clamping force Pd that is equal to or less than the switching value Pc, the position of the crosshead 2 is controlled by setting the toggle link mechanism 4 to the unlocked state Xn. No movement (adjustment) is required. Therefore, the problem that the enlargement rate of the mold protection zone Zd becomes larger as the mold clamping force is set smaller can be avoided, and reliable mold protection is always achieved without being affected by the magnitude of the mold clamping force to be set. be able to.

  (2) Since the position of the crosshead 2 is controlled by setting the toggle link mechanism 4 to the non-lock-up state Xn, the enlargement ratio at the closed position of the movable platen 3 can be reduced. Therefore, it is possible to avoid the problem that the fluctuation of the physical quantity such as the load torque at the closed position of the movable platen 3 becomes small, and the accurate closed position of the movable platen 3 is always maintained without being affected by the size of the mold clamping force to be set. Can be detected.

  (3) According to a preferred embodiment, if the switching value Pc is set to a predetermined value of 60% or less of the maximum mold clamping force, a problem that the enlargement rate of the mold protection section increases and the load at the closed position of the movable platen 3 It is possible to effectively cover a region where a failure occurs in which a fluctuation in physical quantity such as torque is small, and to reliably avoid such a failure.

  (4) According to a preferred embodiment, the position control of the cross head 2 when setting the mold clamping force Pd that is equal to or less than the switching value Pc is performed in advance by the movable platen 3 that generates a predetermined mold clamping force Pm in the lockup state Xu. The clamping load Am or the reference follow-up amount Bm of the crosshead 2 corresponding to the tightening slide Am is obtained, and the set follow-up amount Bs of the crosshead 2 that generates the set mold clamping force Pd is determined as the reference push-in amount Bm If the position is controlled based on the set additional amount Bs by calculating from the white Am, the mold clamping force Pd below the switching value Pc can be set easily and reliably.

  (5) According to a preferred embodiment, the position of the pressure receiving plate 5 is adjusted when the mold clamping force Pu exceeding the switching value Pc is set, and the pressure receiving plate 5 is molded so as to obtain a clamping white Au corresponding to the mold clamping force Pu. If the position is adjusted by being moved by the thickness adjusting mechanism 6, the mold clamping force Pu exceeding the switching value Pc can be set easily and reliably.

  (6) According to a preferred embodiment, a closed position detection mode for obtaining the closed position of the movable platen 3 based on a change in physical quantity accompanying the closing of the mold 7 is provided, and the target value is obtained by executing the closed position detection mode in advance. The closed position for obtaining the mold clamping force is set as the reference value Ds, and the actual closed position (detected value Dd) is obtained by executing the closed position detection mode during production operation. The detected value Dd and the reference value are obtained. If the mold clamping force is corrected based on the deviation E of Ds, it is possible to reliably detect the closed position of the movable platen 3 and perform highly accurate correction for the mold clamping force.

  (7) According to a preferred embodiment, when the mold clamping force to be corrected is equal to or less than the switching value Pc, the deviation E is reflected in the position control of the crosshead 2 and the correction mold clamping force P exceeds the switching value Pc. If the deviation E is reflected in the position adjustment of the movable platen 3, highly accurate correction for the mold clamping force can be reliably performed regardless of the size of the mold clamping force to be set. In particular, when the deviation E is reflected in the position control of the crosshead 2, correction can be performed without moving the pressure receiving platen 3, so that correction accuracy is improved, quick correction processing is realized, and correction processing is simplified. Etc. can be achieved.

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

  First, a configuration of a toggle type mold clamping device Mc capable of performing the mold clamping method according to the present embodiment will be described with reference to FIGS. 3 and 4.

  In FIG. 3, an 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 5 that are spaced apart from each other. The fixed platen 21 is fixed on a machine base (not shown), and the pressure platen 5 moves forward and backward on the machine table. Supported as possible. Further, four tie bars 22 are installed between the stationary platen 21 and the pressure receiving platen 5. In this case, the front ends of the tie bars 22 are fixed to the stationary platen 21 and the rear ends of the tie bars 22 are inserted through the pressure receiving plate 5.

  On the other hand, the movable platen 3 is slidably loaded on the tie bars 22. The movable platen 3 supports the movable die 7m, the fixed platen 21 supports the fixed die 7c, and the movable die 7m and the fixed die 7c constitute the mold 7. Further, a toggle link mechanism 4 is disposed between the pressure receiving plate 5 and the movable plate 3. The toggle link mechanism 4 includes a pair of first links 4a and 4a that are pivotally supported by the pressure receiving plate 5, a pair of output links 4c and 4c that are pivotally supported by the movable plate 3, and the first links 4a and 4a and the output links 4c, A pair of second links 4 b and 4 b coupled to the support shaft of 4 c are provided, and the second links 4 b and 4 b are pivotally supported on the cross head 2.

  A mold clamping drive unit 25 is disposed between the pressure receiving plate 5 and the crosshead 2. The mold clamping drive unit 25 includes a ball screw portion 26 that is rotatably supported by the pressure receiving platen 5, and a ball nut portion 27 that is screwed into the ball screw portion 26 and provided integrally with the crosshead 2. 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 2 integrated with the ball nut portion 27 moves forward and backward, the toggle link mechanism 4 bends or extends, and the movable platen 3 moves forward and backward in the mold opening direction (retracting direction) or the mold closing direction (forward moving direction). To do.

  On the other hand, a mold thickness adjusting mechanism 6 is attached to the pressure receiving platen 5. The mold thickness adjusting mechanism 6 is formed with screw portions 36 on the rear end sides of the four tie bars 22 and screw mechanisms 38 formed by screwing adjustment nuts 37 on the screw portions 36 (FIG. 4). ). In this case, the adjusting nuts 37 also serve as stoppers for the pressure receiving plate 5. As a result, if the adjustment nuts 37 are rotated, they are displaced relative to the screw portions 36, so that the pressure receiving platen 5 can be moved back and forth.

  Further, a geared motor 40 serving as a drive source for moving the pressure receiving plate 5 is attached to the side surface of the pressure receiving plate 5. This geared motor 40 is a drive motor for adjusting the mold thickness. The geared motor 40 includes a motor main body 41, and the motor main body 41 includes a motor portion by an induction motor provided in the second half and a reduction gear mechanism that inputs rotation of the motor portion by being 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, there exists an advantage which can contribute to the miniaturization of the whole small size similarly to the servomotor with an encoder.

  On the other hand, as shown in FIG. 4, the drive gear 51 is attached to the front end side of the output shaft 42, and the small gears 52 are integrally attached to the adjustment nuts 37. 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 disc 5. That is, the small gears 52 are arranged at the four corner positions 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 40 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 plate 5 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 servomotor 30, the rotary encoder 31, the geared motor 40, the motor brake unit 43, and the rotary encoder unit 44.

  Next, a mold clamping method according to this embodiment including the operation (function) of the toggle mold clamping apparatus Mc having such a configuration will be described with reference to FIGS.

  First, a predetermined mold clamping force smaller than the maximum mold clamping force is previously set in the controller 61 as the switching value Pc. In this case, the switching value Pc can be set to a predetermined value of 60 [%] or less, preferably 40 [%] or less of the maximum mold clamping force. FIG. 10 shows the enlargement ratio [%] characteristic at the closed position of the mold 7 with respect to the set clamping force [%]. As in the prior art, the magnitude of the set clamping force [%] is shown. Correspondingly, when the pressure receiving platen 5 is moved and adjusted, it becomes like a characteristic line Qr shown in the figure, and the enlargement ratio increases rapidly as it becomes smaller than the vicinity of the mold clamping force 40 [%]. That is, the degree of the problem that the enlargement rate of the mold protection zone Zd described above becomes large and the fluctuation of the physical quantity such as the load torque at the closed position of the movable platen 3 becomes small increases. Accordingly, the switching value Pc is optimally 40 [%] or less, and preferably 60 [%] or less in consideration of the margin. Accordingly, it is possible to effectively cover a region where such a problem occurs and reliably avoid these problems. In the present embodiment, the switching value Pc is set to 40 [%].

  Further, in the present embodiment, when setting the mold clamping force Pd that is equal to or lower than the switching value Pc with the switching value Pc (40 [%]) as a boundary, the mold clamping is performed in the first mold clamping mode, When setting the mold clamping force Pu exceeding the switching value Pc, mold clamping is performed in the second mold clamping mode. Therefore, a sequence program for performing mold clamping in the first mold clamping mode and the second mold clamping mode is set in the controller 61 in advance.

  Hereinafter, a specific mold clamping method will be described with reference to the flowchart shown in FIG. Now, it is assumed that the mold clamping force is set to N [%] (step S1). In the example, the maximum mold clamping force (rated mold clamping force) 100 [%] is set. The mold clamping with the maximum mold clamping force of 100% is the same as the conventional mold clamping. FIG. 1B shows a case where mold clamping is performed with a maximum mold clamping force of 100%.

  On the other hand, it is assumed that the operator changes the setting of the mold clamping force by changing the mold (step S2). In this case, if the mold clamping force to be changed is equal to or less than the switching value Pc, mold clamping is performed in the first mold clamping mode (step S4). For example, when the mold clamping force is changed to 20 [%], the mold clamping force Pd that is equal to or less than the switching value Pc (40 [%]) is set, so that the mold clamping is performed in the first mold clamping mode. In the first mold clamping mode, mold clamping is performed to control the position of the crosshead 2 by setting the toggle link mechanism 4 to the non-lock-up state Xn.

  This first mold clamping mode will be described more specifically. In the first mold clamping mode, the pressure receiving platen 5 is not moved by the mold thickness adjusting mechanism 6. The position of the pressure receiving platen 5 can be fixed at a position where a predetermined mold clamping force Pm is generated when the toggle link mechanism 4 is brought into the lock-up state Xu. An example is a mold clamping force Pm of 40%, but is not limited to this. In the first mold clamping mode, first, the reference additional amount Bm of the crosshead 2 corresponding to the clamping margin Am of the movable platen 3 that generates a predetermined mold clamping force Pm by the lock-up state Xu is obtained (step S401). Note that the closing margin Am of the movable platen 3 may be obtained instead of the reference additional amount Bm. FIG. 1 (b) shows the fastening white Am. This tightening Am can be obtained from a database obtained by experiment (actual measurement) or the like. Further, the conversion from the tightening Am to the reference additional amount Bm of the corresponding crosshead 2 can be easily converted using a known conversion formula.

Further, the set additional amount Bs of the cross head 2 that generates the set mold clamping force Pd is obtained by calculation from the clamping arm Am (step S402). This set additional amount Bs is
Bs = (Ks × Pd × (Lc−Dm + D) / Lt) + Ko
However, Ks: proportionality constant (derived from tightening white Am)
Pd: Clamping force to be set
Lc: Tie bar effective length
Dm: Maximum mold thickness
D: Mold thickness
Lt: Head of tie bar
Ko: Constant (offset amount)
Can be calculated. Note that Ks is an inclination derived from the relationship with the clamping force Am when the mold clamping force to be set is generated, and this relationship is shown in FIG. The tie bar effective length Lc (see FIG. 1) indicates the tie bar length from the pressure receiving plate 5 to the fixed platen 21.

  If the set additional amount Bs is obtained, the position of the crosshead 2 is controlled so that the set additional amount Bs is obtained when performing mold clamping (step S403). That is, when the movable platen 3 reaches the closed position (Cs), control is performed to move the crosshead 2 by the set additional amount Bs. FIG. 1A shows this state. In FIG. 1A, As is a closing margin of the movable platen 3 corresponding to the set additional amount Bs. A characteristic line Qi shown in FIG. 10 is an enlargement ratio characteristic when the mold is clamped in the first mold clamping mode. As is apparent from the characteristics, even when the mold clamping force is set to a small value, the enlargement rate at the closed position of the movable platen 3 does not increase, and is almost the same as the enlargement rate of the mold clamping force 40% in the locked-up state. Become.

  As described above, the position control of the cross head 2 when setting the mold clamping force Pd that is equal to or less than the switching value Pc is applied to the clamping arm Am of the movable platen 3 that generates the predetermined mold clamping force Pm in advance in the lock-up state Xu. The reference additional amount Bm of the corresponding crosshead 2 is obtained, and the set additional amount Bs of the crosshead 2 that generates the set clamping force Pd is obtained from the reference additional amount Bm by calculation, and this set additional amount Bs. Therefore, the mold clamping force Pd below the switching value Pc can be set easily and reliably.

  On the other hand, when the operator changes the setting of the mold clamping force in step S2, if the mold clamping force to be changed exceeds the switching value Pc, mold clamping is performed in the second mold clamping mode (step S5). ). For example, when the mold clamping force is changed to 80 [%], the mold clamping force Pd exceeding the switching value Pc (40 [%]) is set, so that the mold clamping is performed in the second mold clamping mode. In the second mold clamping mode, the mold clamping is performed to adjust the position of the pressure receiving platen 5 to bring the toggle link mechanism 4 into the lock-up state Xu.

  This second mold clamping mode will be described more specifically. In the second mold clamping mode, first, the lockup state Xu is set, and the clamping white Au of the movable platen 3 that generates the set mold clamping force Pu is obtained (step S501). This fastening white Au can be obtained from a database obtained by experiment (actual measurement) or the like. FIG. 1C shows a state set by the second mold clamping mode. Then, when the clamping white Au is obtained, the mold thickness adjusting mechanism 6 is controlled to move the pressure receiving plate 5 so as to obtain the clamping white Au corresponding to the mold clamping force Pu (step S502). On the other hand, when performing mold clamping, the toggle link mechanism 4 is set to the lock-up state Xn (step S503). As shown in FIG. 10, the second mold clamping mode is an area where the mold clamping force exceeds 40%. Since this area is originally an area where the enlargement ratio is small, the conventional mold clamping method is used as it is. Even if it is applied, the above-mentioned problems do not occur. In this way, the position of the pressure receiving platen 5 when the mold clamping force Pu exceeding the switching value Pc is adjusted, and the pressure receiving platen 5 is adjusted to the mold thickness adjusting mechanism 6 so as to obtain a clamping white Au corresponding to the mold clamping force Pu. Therefore, the mold clamping force Pu exceeding the switching value Pc can be set easily and reliably.

  Therefore, according to the mold clamping method according to the present embodiment, when the mold clamping force Pd that is the switching value Pc or less is set and the mold clamping is performed, the toggle link mechanism 4 is brought into the non-lock-up state Xn to cross Since the position of the head 2 is controlled, there is no need to move (adjust) the pressure receiving platen 5. Therefore, the smaller the mold clamping force is set, the more the problem that the enlargement ratio of the mold protection section becomes larger can be avoided, and always reliable mold protection is achieved without being affected by the size of the mold clamping force to be set. Can do. Further, since the position of the crosshead 2 is controlled by setting the toggle link mechanism 4 to the non-lock-up state Xn, the enlargement ratio at the closed position of the movable platen 3 can be reduced. Therefore, it is possible to avoid the problem that the fluctuation of the physical quantity such as the load torque at the closed position of the movable platen 3 becomes small, and the accurate closed position of the movable platen 3 is always maintained without being affected by the size of the mold clamping force to be set. Can be detected.

  Although the case where the mold clamping force is changed has been described above, the present invention can also be used in the same manner when the mold clamping force is corrected. Next, a method for correcting the mold clamping force will be described. First, the controller 61 is provided with a closed position detection mode. In the closed position detection mode, the closing point Cs of the mold 7 is detected based on a change in physical quantity accompanying the closing of the mold 7, and the position of the crosshead 2 in the toggle link mechanism 4 when the closing point Cs is detected is determined. It has a function of detecting and obtaining the position (closed position) of the movable platen 3 at the closing point Cs from the detected position of the crosshead 2.

  In this case, the load torque T is desirable as a physical quantity associated with the closing of the mold 7. In addition, a threshold value Ts for the load torque T is set in the controller 61 (see FIG. 6). This threshold value Ts detects the increase in the load torque T accompanying the closing point Cs of the mold 7, that is, the movable mold 7m touches the fixed mold 7c, and can be set to an arbitrary level. If necessary, it can also be set by performing trial mold clamping a predetermined number of times.

  Hereinafter, the processing procedure of this closed position detection mode will be described according to the flowchart shown in FIG.

  Now, it is assumed that the mold 7 is in the mold open position (fully open position). Therefore, the crosshead 2 in the toggle link mechanism 4 is in the mold opening position Xa shown in FIG. When the mold clamping operation is started, the servo motor 30 is operated, and the movable platen 3 moves forward from the mold opening position to the mold closing direction. At this time, the movable platen 3 is first fast-closed to move forward at high speed (step S11). On the other hand, when the movable platen 3 moves forward in the mold closing direction and the crosshead 2 reaches the preset low speed switching point Xb, the process shifts to the low speed mold closing (steps S12 and S13). In this low-speed mold closing, as shown in FIG. 6, the foreign substance detection processing is performed by the mold protection section (foreign substance detection section) Zd set in the preceding stage, and if this mold protection section Zd is completed, the latter stage is set. The detection process of the closing point Cs for the mold 7 is performed by the closed point detection section Zc.

  That is, in the mold protection zone Zd, the magnitude of the load torque T is monitored, and if a preset threshold value is exceeded, it is determined that there is a foreign object, and abnormal processing such as mold opening control is performed. Moreover, if it passes through the mold protection zone Zd and shifts to the closing point detection zone Zc, monitoring for detecting the closing point Cs of the die 7 is performed (steps S14 and S15). In this case, if the load torque T reaches a preset closing point detection threshold value Ts, it is detected as a closing point Cs of the mold 7, and from this time of detection, the process shifts to high pressure clamping, and high pressure clamping is performed. At the same time, the position of the crosshead 2 at the time of detection is detected (steps S16 and S17). Further, the position of the crosshead 2 is detected using the encoder pulse of the rotary encoder 31 that detects the rotational speed of the mold clamping servomotor 30. In this case, the rotary encoder 31 is an incremental encoder and detects an absolute position based on the number of encoder pulses generated with respect to the reference position. Based on the position of the crosshead 2, the closed position of the movable platen 3 is obtained by calculation using a known conversion formula (step S18).

  In this case, if the obtained closing position is the initial setting, that is, the execution of the closing position detection mode at the time of the initial setting for obtaining the target mold clamping force, the obtained closing position is set (stored) as the reference value Ds. (Steps S19 and S20). On the other hand, if it is execution of the closed position detection mode at the time of the production operation mentioned later, it will be taken in into the controller 61 as detection value Dd (step S21). The above description is a basic mode of the closed position detection mode. Note that the actual reference value Ds and the detection value Dd can be obtained from the average of a plurality of closed positions obtained by executing the closed position detection mode a plurality of times, as will be described later.

  In FIG. 6, load torques Tf and Tr indicated by phantom lines indicate cases where the mold clamping force varies. The load torque Tr is a fluctuation curve when the mold 7 is heated and thermally expanded, and shows a state where the threshold Ts is reached at a closing point Cr before the normal closing point Cs. In this case, the mold clamping force increases. Further, the load torque Tf is a fluctuation curve when the tie bars 22 are heated and thermally expanded, and shows a state where the threshold Ts is reached at the closing point Cf after the normal closing point Cs. In this case, the mold clamping force is reduced. Even the closing points Cs, Cf, Cr related to the fluctuation of the mold clamping force can be accurately detected by the above-described closing position detection mode. Xd represents the mold clamping end position.

  Next, the processing procedure of the mold clamping force correction method using such a closed position detection mode will be described with reference to the flowchart shown in FIG.

  Assume that the production operation is performed by automatic molding (step S31). In this case, the reference value Ds described above is set in advance. During production operation, when the preset closing position detection time or the number of closing position detection shots is reached, the closing position detection mode is automatically executed (steps S32 and S33). The execution interval of the closed position detection mode is sufficient for practical use even if it is several times a day, and can be set in consideration of the degree of fluctuation of the mold clamping force in the actual machine. Note that the execution interval of the closed position detection mode can be arbitrarily set, and may be performed every time a shot is made, for example. Even if it is performed every time, the number of times of actual correction is about several times a day as described above, and it hardly affects the production efficiency.

  In the closed position detection mode, the detection value Dd related to the closed position of the movable platen 3 is obtained in accordance with the processing procedure described above. In the example, the closed position detection mode is executed a plurality of times set in advance, and the detection value Dd is obtained from the average of the obtained multiple closed positions (steps S34 and S35). If the detected value Dd is obtained, the deviation E from the preset reference value Ds, that is, E = Ds−Dd is obtained (step S36). Further, since an allowable range for the deviation E is preset in the controller 61, this allowable range is compared with the obtained deviation E to determine whether or not the deviation E exceeds the allowable range. When the deviation E is within the allowable range, the mold clamping force is not corrected. Therefore, the production operation is continued as it is (steps S37 and S31). On the other hand, when the deviation E exceeds the allowable range, the detection value Dd is detected again (steps S37, S38, S31). That is, the detection value Dd is continuously detected a plurality of times, and if the obtained deviation E continuously exceeds the allowable range, the mold clamping force is corrected (steps S39 and S40).

  Next, a correction processing procedure for the mold clamping force will be described with reference to a flowchart shown in FIG.

  In this case, when the mold clamping force to be corrected is equal to or less than the switching value Pc, the deviation E is reflected in the position control of the crosshead 2. That is, a correction amount for the set additional amount Bs is calculated based on the deviation E (steps S51 and S52). In this case, the correction may be performed multiple times by using a predetermined correction amount. The correction amount corresponding to the deviation E can be obtained by the same procedure as that for changing the mold clamping force described above, and the set additional amount Bs is corrected by the obtained correction amount. On the other hand, if the corrected set additional amount Bs is obtained, the position of the crosshead 2 is controlled so as to obtain the corrected set additional amount Bs when performing mold clamping (step S53). In this way, by reflecting the deviation E in the position control of the crosshead 2, correction can be performed without moving the pressure receiving platen 3, so that correction accuracy is improved, quick correction processing is realized, and correction processing is simplified. Etc. can be achieved.

  On the other hand, when the mold clamping force to be corrected exceeds the switching value Pc, the deviation E is reflected in the position adjustment of the movable platen 3. In this case, first, the controller 61 monitors whether or not a predetermined timing (a period other than the high-pressure mold clamping period, a mold opening period, a protruding period, etc.) has been reached (step S54). When a specific timing is reached, a correction command is output, and the pressure platen 5 is moved by controlling the mold thickness adjusting mechanism 6 (steps S55, S56, S57). In this case, the pressure receiving plate moving drive motor 40 is driven and controlled based on the correction amount, and the pressure receiving plate 5 is displaced in a direction in which the deviation E is eliminated. Note that the pressure receiving platen 5 is moved at a lower speed than the normal speed. Thus, when the pressure receiving platen 5 is moved to the target position corresponding to the correction amount, the mold thickness adjusting mechanism 6 (drive motor 40) is controlled to stop (steps S58 and S59). Therefore, by using such a correction method, it is possible to reliably detect the closed position of the movable platen 3 and perform highly accurate correction for the mold clamping force. In particular, when the mold clamping force to be corrected is less than or equal to the switching value Pc, the deviation E is reflected in the position control of the crosshead 2, and when the mold clamping force P to be corrected exceeds the switching value Pc, the deviation E is reflected on the movable platen. Therefore, regardless of the size of the mold clamping force to be set, highly accurate correction for the mold clamping force can be reliably performed.

  Although the best embodiment has been described in detail above, the present invention is not limited to such an embodiment, and the detailed configuration, method, quantity, numerical value, and the like do not depart from the spirit of the present invention. It can be changed, added, or deleted arbitrarily.

Action explanatory drawing of the mold clamping method concerning the best embodiment of the present invention, A flowchart showing a processing procedure of the mold clamping method, Side view of a toggle type mold clamping device capable of performing the same mold clamping method, A rear view in which a part of the toggle type mold clamping device is omitted, Explanatory drawing when obtaining the additional set amount in the same mold clamping method, Variation curve diagram of load torque with respect to the position of the crosshead for explaining the mold clamping method, The flowchart which shows the process sequence of the closed position detection mode at the time of performing correction | amendment of mold clamping force by the mold clamping method, A flowchart showing a processing procedure when correcting the mold clamping force by the mold clamping method, A flowchart for correcting the clamping force by the same clamping method; Enlargement ratio characteristics diagram against mold clamping force Magnification characteristics diagram for mold position,

Explanation of symbols

2 Crosshead 3 Movable platen 4 Toggle link mechanism 5 Pressure receiving plate 6 Mold thickness adjusting mechanism 7 Mold Mc Toggle type clamping device Pc Switching value Xn Non-lock-up state Xu Lock-up state Am Tightening iron Au Tightening whitening Bm Standard additional amount Bs setting additional amount

Claims (7)

  A toggle link mechanism is interposed between the cross head and the movable platen, and a predetermined enlargement ratio is generated between the moving amount of the movable plate and the moving amount of the cross head, thereby increasing the pressure of the cross head and In the mold-clamping method of the toggle-type mold clamping device that transmits to the movable platen, when setting a predetermined mold clamping force smaller than the maximum mold clamping force in advance as a switching value and setting a mold clamping force that is less than this switching value The position of the crosshead is controlled by setting the toggle link mechanism in a non-lock-up state, and clamping is performed, and when setting the clamping force exceeding the switching value, the position of the pressure receiving plate is adjusted. A mold clamping method for a toggle type mold clamping apparatus, wherein mold clamping is performed with the toggle link mechanism in a locked-up state.   2. The mold clamping method for a toggle type mold clamping apparatus according to claim 1, wherein the switching value is set to a predetermined value of 60% or less of the maximum mold clamping force.   The position control of the crosshead for setting the mold clamping force that is equal to or less than the switching value is performed by the clamping of the movable platen that generates a predetermined mold clamping force in a locked-up state in advance or the crosshead corresponding to the clamping shiro. Obtaining the reference additional amount, calculating the set additional amount of the crosshead that generates the mold clamping force to be set by calculation from the reference additional amount or the closing margin, and controlling the position based on the set additional amount The mold clamping method of the toggle type mold clamping apparatus according to claim 1.   The position adjustment of the pressure receiving plate that sets the mold clamping force exceeding the switching value is characterized in that the position of the pressure receiving plate is adjusted by moving the pressure receiving plate by a mold thickness adjusting mechanism so as to obtain a clamping margin corresponding to the mold clamping force. The method for clamping a toggle type mold clamping apparatus according to claim 1.   Closed position detection mode that obtains the position of the movable platen (closed position) based on the change in physical quantity associated with mold closing is provided, and the closing position detection mode is executed in advance to obtain the target mold clamping force. In addition to setting the position as a reference value and executing the closed position detection mode during production operation, the actual closed position (detected value) is obtained, and the mold clamping force is corrected based on the deviation between this detected value and the reference value. The method for clamping a toggle type mold clamping apparatus according to claim 1, wherein:   6. The method of clamping a toggle type mold clamping apparatus according to claim 5, wherein when the mold clamping force to be corrected is equal to or less than the switching value, the deviation is reflected in the position control of the crosshead.   6. The mold clamping method of a toggle type mold clamping apparatus according to claim 5, wherein when the mold clamping force to be corrected exceeds the switching value, the deviation is reflected in the position adjustment of the movable platen.

Images