JP4724050B2 - Mold clamping control method of injection molding machine - Google Patents

Description

  The present invention relates to a mold clamping control method for an injection molding machine suitable for use in injection molding by a toggle type mold clamping apparatus using a pressure control pattern in which mold clamping forces are set in multiple stages.

  Conventionally, as a mold clamping control method of an injection molding machine that performs injection molding (compression molding) with a toggle type mold clamping device using a pressure control pattern in which a plurality of different mold clamping forces (compression pressures) are set in multiple stages, for example, A mold clamping control method used for a method for forming an information recording medium substrate disclosed in JP-A-5-237894 is known.

This molding method (clamp control method) is a toggle type injection molding machine equipped with a toggle mechanism that extends a toggle link and obtains a clamping force by the tensile force of a tie bar. In a method for forming a substrate for an information recording medium by providing a mold cavity constituted by members, injecting and filling a molten resin made of a thermoplastic resin material into the cavity, and performing compression molding, After the molten resin is injected and filled to the initial set pressure, a step of controlling the compression of the molten resin in the mold cavity step by step based on the compression program profile set in multiple stages is included.
JP-A-5-237894

  However, the conventional mold clamping control method (molding method) in the above-described injection molding machine has the following problems.

  In other words, a toggle type mold clamping device for clamping a mold uses a toggle link mechanism to connect a movable plate that supports a movable die and a cross head that is advanced and retracted by a drive unit supported by a pressure receiving plate, thereby adding a cross head. It has a function to increase the pressure and transmit it to the movable platen. Therefore, at the time of mold clamping, a predetermined mold clamping force is generated based on the extension of the tie bar in a state where the toggle link mechanism is fully extended, and compression molding and injection molding using such a toggle link mechanism, When compression molding or injection molding is performed using a pressure control pattern in which multiple mold clamping forces are set, there is a problem that the responsiveness of pressure control becomes unstable.

  5 and 6 show an example of the pressure control pattern. The pressure control pattern Cx shown in FIG. 5 shows the case where the maximum mold clamping force Px is set to 100 [%], and the pressure control pattern Cy shown in FIG. 6 shows the case where the maximum mold clamping force Py is set to 50 [%]. . The pressure control patterns Cx and Cy indicated by the solid lines in FIGS. 5 and 6, that is, the pressure control patterns Cx and Cy in which a plurality of different mold clamping forces Px, Pxa, Pxb... Py, Pya, Pyb. FIG. 5 and FIG. 6 show the characteristics when the mold clamping control method according to the present invention (this embodiment) is used, but when the same pressure control patterns Cx and Cy are used by the conventional mold clamping control method. As shown by the phantom lines Pxe ..., Pye ..., parts with poor response (bad), disturbance of behavior, undershoot and overshoot occur, and the pressure control response becomes unstable and high accuracy. There was a problem that pressure control could not be performed.

  An object of the present invention is to provide a mold clamping control method for an injection molding machine that solves the problems existing in the background art.

  The mold clamping control method of the injection molding machine M according to the present invention is a toggle type using pressure control patterns Cx and Cy in which a plurality of different mold clamping forces Pxa... Pya. When performing injection molding by the mold clamping device Mc, the correlation between the pressure compensation constants Kxsa..., Kysa... With respect to the magnitude of the mold clamping force Psa. A plurality of pressure compensation constants Kxsa..., Kysa... That are set by functions Fx, Fy that approximate the correlation using the compensation constants Kxsa. The pressure compensation constants Kxa ..., Kya corresponding to the magnitudes of the mold clamping forces Pxa ..., Pya ... in the pressure control patterns Cx, Cy are set by Bd. Are calculated and the pressure compensation constants Kxa ..., Kya ... are changed in response to changes in the size of the mold clamping forces Pxa ..., Pya ... caused by the pressure control patterns Cx, Cy. It is characterized by doing so.

  In this case, the pressure compensation gain in the pressure feedback control system Up can be applied to the pressure compensation constants Kxa..., Kya. The correlation can include at least two correlations with different maximum clamping forces Px and Py. At this time, the pressure compensation constant at the maximum mold clamping force Pe other than the maximum mold clamping forces Px and Py can be obtained by estimation based on at least two correlations.

  According to the mold clamping control method of the injection molding machine M according to the present invention by such a technique, the following remarkable effects are obtained.

  (1) Even when injection molding is performed using pressure control patterns Cx, Cy in which a plurality of different mold clamping forces Pxa ..., Pya ... are set in multiple stages, mold clamping forces Pxa ... by the pressure control patterns Cx, Cy ... , Pya..., And the pressure compensation constants Kxa..., Kya. Thus, the pressure control response can be stabilized and high-precision pressure control can be performed.

  (2) Since the pressure compensation constants Kxa..., Kya... Are set with the appropriate correlation between the pressure compensation constants Kxsa..., Kysa. When setting the compensation constants Kxa ..., Kya ..., optimum pressure compensation constants Kxa ..., Kya ... corresponding to the mold clamping forces Pxa ..., Pya ... can be set.

  (3) Since the correlation can be set by functions Fx and Fy that approximate the correlation using pressure compensation constants Kxsa..., Kysa... Corresponding to the magnitudes of different mold clamping forces Psa. Appropriate pressure compensation constants Kxa..., Kya.

  (4) Since the correlation can set a plurality of pressure compensation constants Kxsa... Kysa... Corresponding to different sizes of the plurality of mold clamping forces Psa. It can be set by simple processing without any problem.

  (5) If the pressure compensation gain in the pressure feedback control system Up is applied to the pressure compensation constants Kxa..., Kya... According to a preferred embodiment, the control system Up can be implemented easily and at low cost. it can.

  (6) According to a preferred embodiment, at least two correlations in which the maximum mold clamping forces Px and Py are made different are included, and the pressure compensation constant at the maximum mold clamping force Pe other than the maximum mold clamping forces Px and Py is If it is determined by estimation based on at least two correlations, the pressure compensation constant at the maximum mold clamping force Pe other than the maximum mold clamping forces Px and Py can be obtained by using the minimum amount of data. Can be obtained easily and reliably.

  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 control method according to the present embodiment will be described with reference to FIGS. 2 and 3.

  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 11 and a pressure receiving plate 12 that are spaced apart from each other. The fixed platen 11 is fixed on a machine base (not shown), and the pressure receiving plate 12 moves forward and backward on the machine base. Supported as possible. Further, four tie bars 13 are laid between the fixed platen 11 and the pressure platen 12. 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 12.

  On the other hand, the movable platen 14 is slidably loaded on the tie bars 13. The movable platen 14 supports the movable die 15m, the fixed platen 11 supports the fixed die 15c, and the movable die 15m and the fixed die 15c constitute a mold 15. Further, a toggle link mechanism L is disposed between the pressure receiving platen 12 and the movable platen 14. The toggle link mechanism L includes a pair of first links La and La that are pivotally supported on the pressure receiving platen 12, a pair of output links Lc and Lc that are pivotally supported on the movable platen 14, a first link La and La, and an output link Lc, A pair of second links Lb and Lb coupled to the support shaft of Lc are provided, and the second links Lb and Lb are pivotally supported on the cross head 16.

  A mold clamping drive unit 17 is disposed between the pressure receiving plate 12 and the cross head 16. The mold clamping drive unit 17 includes a ball screw portion 18 that is rotatably supported by the pressure receiving plate 12, and a ball nut portion 19 that is screwed into the ball screw portion 18 and is provided integrally with the cross head 16. A ball screw mechanism 20 is provided, and a rotation drive mechanism portion 21 that rotates the ball screw portion 18 is provided. The rotation drive mechanism 21 includes a mold clamping servo motor 22, a rotary encoder 23 attached to the servo motor 22 to detect the rotation speed of the servo motor 22, and a drive gear 24 attached to the shaft of the servo motor 22. A driven gear 25 attached to the ball screw portion 18 and a timing belt 26 spanned between the drive gear 24 and the driven gear 25 are provided.

  Accordingly, when the servo motor 22 is operated, the drive gear 24 is rotated, and the rotation of the drive gear 24 is transmitted to the driven gear 25 via the timing belt 26, and the ball screw portion 18 is rotated to thereby rotate the ball nut. Part 19 moves forward and backward. As a result, the cross head 16 integrated with the ball nut portion 19 moves forward and backward, the toggle link mechanism L bends or extends, and the movable platen 14 moves forward and backward in the mold opening direction or the mold closing direction (mold clamping direction).

  On the other hand, the pressure receiving platen 12 is provided with a mold thickness adjusting unit 27. The mold thickness adjusting portion 27 is formed with screw portions 28 on the rear end sides of the four tie bars 13 and screwed with adjusting nuts 29 to the respective screw portions 28. In this case, the adjusting nuts 29 also serve as stoppers for the pressure receiving plate 12. As a result, if each of the adjustment nuts 29 is rotated, the pressure receiving platen 12 can be displaced forward and backward because the adjustment nuts 29 are displaced relative to the screw portions 28. Further, a geared motor 31 serving as a drive source for moving the pressure receiving plate 12 is attached to the side surface of the pressure receiving plate 12. The geared motor 31 is a drive motor for adjusting the mold thickness. The geared motor 31 has a rotary output shaft 32 protruding from the front end and a rotary encoder 33 for detecting the rotation speed of the motor shaft at the rear end.

  On the other hand, a drive gear 34 is attached to the rotation output shaft 32, and small gears 35 are integrally attached to the adjustment nuts 29, respectively. In this case, the adjustment nuts 29 and the small gears 35 are positioned on the same axis. Further, large gears 36 that mesh with the small gears 35 and the drive gear 34 are arranged. The large gear 36 is formed in a ring shape, and a rail portion provided along the inner peripheral surface is supported by a plurality of support rollers (not shown) attached to the pressure receiving plate 12. As a result, the small gears 35 are simultaneously meshed with the large gear 36, and when the geared motor 31 is operated, the large gear 36 is rotated by the rotation of the drive gear 34, and the small gear 35 is rotated by the rotation of the large gear 36. ... rotate at the same time. Since the adjustment nuts 29 that rotate integrally with the small gears 35 advance and retract along the screw portions 28 of the tie bars 13, the pressure receiving plate 12 also advances and retracts, and the position in the front-rear direction is adjusted. .

  On the other hand, a molding machine controller 50 connects the mold clamping servo motor 22, the rotary encoder 23, the geared motor 31, and the rotary encoder 33. The molding machine controller 50 has a computer function for controlling the entire injection molding machine M, and includes a touch panel display (not shown).

  FIG. 3 shows a specific functional block diagram of the control system U for the main part configuration of the molding machine controller 50, in particular, the mold clamping servomotor 22. The mold clamping servomotor 22 and the rotary encoder 23 are the same as those described above. In FIG. 3, 51 is a deviation calculation unit, 52 is a pressure sensor, 53 is a pressure compensation unit, 54 is a switching unit, 55 is a switching determination unit, 56 is a deviation calculation unit, 57 is a speed compensation unit, and 58 is current / power control. , 59 is a current detector, 60 is a speed conversion unit, 61 is a processing unit (computer processing unit) including a CPU and the like, 62 is a memory, and the signal system of each unit is as shown.

  In this case, the pressure sensor 52 is a sensor that detects the clamping force in the clamping process, and uses a tie bar sensor attached to the tie bar 13 as shown in FIG. This tie bar sensor (pressure sensor 52) detects the extension amount of the tie bar 13 due to the generation of the mold clamping force, and the mold clamping force can be obtained by converting the detected elongation amount into the magnitude of the pressure. In addition, as the pressure sensor 52, a load cell that detects a clamping force applied to the mold 15 (movable mold 15m) can be used. The pressure compensation unit 53 is a circuit that performs pressure compensation in the pressure feedback control system Up, and a PID constant (pressure compensation constant) is set. The pressure compensation unit 53 is connected to the processing unit 61. As a result, when performing the injection molding, the processing unit 61 becomes a P constant in the pressure compensation unit 53 in response to changes in the mold clamping forces Px, Pxa..., Py, Pya. Processing for changing the pressure compensation gains Kx, Ky, Kxa..., Kya. Since such pressure compensation gains Kx, Ky, Kxa..., Kya... Are changed, there is an advantage that the pressure feedback control system Up can be implemented easily and at low cost.

  On the other hand, the memory 62 stores a control program Ap for executing the mold clamping control method according to the present embodiment, and at least various data used for the mold clamping control method, that is, a plurality of different data to be described later. Pressure control patterns Cx, Cy, pressure compensation gains Kxa, Kya, etc., in which the mold clamping forces Pxa, Pya, etc. are set in multiple stages, and pressure compensation gains Kxsa, Kysa corresponding to different sizes of the mold clamping forces Psa, ... Various data such as the functions Fx and Fy that approximate the correlation of ..., the target value (speed target value) Vs for the mold closing speed, and the target value (pressure target value) Ps of the mold clamping force are set (registered) as the database Bd. Has been. The function of each part in the molding machine controller 50 will be described later together with a description of the mold clamping control method.

  Next, a mold clamping control method according to the present embodiment using such a toggle mold clamping device Mc will be described according to the flowchart shown in FIG. 1 with reference to the drawings.

  In the mold clamping control method according to the present embodiment, an appropriate (optimum) correlation between pressure compensation gains Kxsa ..., Kysa ... corresponding to the magnitudes of a plurality of different mold clamping forces Psa ... is approximated to this correlation in advance. It sets by function Fx, Fy to perform (steps S1-S5). The functions Fx and Fy can be obtained experimentally.

  Hereinafter, a specific procedure for setting the functions Fx... Will be described. FIG. 4 shows an example of two functions Fx and Fy, and the exemplary functions Fx and Fy can be obtained from two correlations with different maximum clamping forces Px and Py, respectively. In this case, the maximum mold clamping force Px uses 100 [%], and the maximum mold clamping force Py uses 50 [%]. The maximum mold clamping force Px of 100 [%] is a mold clamping force that is rated (maximum) in the toggle mold clamping device Mc generated when the toggle link mechanism L is fully extended, and the maximum mold clamping force Py is 50 [%] is a mold clamping force set so that a mold clamping force of 50 [%] with respect to the rating is generated with the toggle link mechanism L fully extended.

  First, the maximum mold clamping force Px is set (step S1). If the maximum mold clamping force Px is set, the optimum pressure corresponding to a plurality of (three examples) mold clamping forces Psa (100 [%]), Psb (90 [%]), Psc (50 [%]) Compensation gains Kxsa, Kxsb, Kxsc are obtained (steps S2, S3). The optimum pressure compensation gain Kxsa... Means that when the specific mold clamping force Psa, Psb, Psc is changed according to the assumed pressure control pattern, the response is dull (bad) or the behavior is disturbed or undershoot and overshoot. This is a gain that does not cause a shoot.

  If all the pressure compensation gains Kxsa... At the maximum mold clamping force Px are obtained, then the maximum mold clamping force Py is set (steps S4 and S1). Then, as in the case of the maximum mold clamping force Px, optimum pressure compensation gains Kysa, Kysb, Kysc corresponding to a plurality of (three examples) mold clamping forces Psa, Psb, Psc are obtained (steps S2, S3). .

  Therefore, as shown in FIG. 4, a function Fx that approximates this correlation is obtained by the correlation between the three pressure compensation gains Kxsa, Kxsb, and Kxsc with respect to the mold clamping forces Psa, Psb, and Psc. Similarly, as shown in FIG. 4, a function Fy that approximates this correlation is obtained by the correlation between the three pressure compensation gains Kysa, Kysb, and Kysc with respect to the mold clamping forces Psa, Psb, and Psc. Then, the obtained functions Fx and Fy are registered (set) as the database Bd in the memory 62 (step S5).

  Thus, the pressure compensation constants Kxa..., Kya... Are set with appropriate correlations between the pressure compensation constants Kxsa..., Kysa... With respect to the magnitude of the mold clamping force Psa. When setting the pressure compensation constants Kxa..., Kya..., There is an advantage that the optimum pressure compensation constants Kxa... Kya. Further, since this correlation is set by functions Fx and Fy that approximate the correlation using pressure compensation constants Kxsa..., Kysa... Corresponding to the magnitudes of at least different mold clamping forces Psa. There is an advantage that appropriate pressure compensation constants Kxa..., Kya.

  On the other hand, when producing a product (for example, a DVD disk), a pressure control pattern used at the time of injection molding corresponding to the product to be produced is input to the molding machine controller 50 (step S6). As an example, assume that the pressure control pattern Cx shown in FIG. 5 is input. The pressure control pattern Cx is different from an actual pressure control pattern for producing a product. When the pressure control pattern Cx is input to the molding machine controller 50, the processing unit 61 includes the mold clamping force Px (100 [%]) in the pressure control pattern Cx, as well as each mold clamping force Pxa (5 [%]), Pressure compensation gains Kx, Kxa, Kxb, Kxc and Kxd corresponding to Pxb (90 [%]), Pxc (40 [%]) and Pxd (70 [%]) are obtained (steps S7 and S8). In this case, it can be easily obtained from the registered function Fx. When all the pressure compensation gains Kx, Kxa, Kxb... Are obtained, they are set in the memory 62 as molding conditions for the product to be produced (steps S8, S9).

  On the other hand, in actual production, the operation in the mold clamping process for performing injection molding is as follows. Now, it is assumed that the toggle type mold clamping device Mc is in the mold open state. With the start of the mold clamping process, the movable platen 14 at the mold opening position moves forward. In this case, since the servo motor 22 is driven and controlled, the rotation of the servo motor 22 is transmitted via the drive pulley 24, the timing belt 26, and the driven pulley 25, and includes a ball screw mechanism including the ball screw portion 18 and the nut portion 19. 20 is converted into a straight movement (forward movement) by 20 and transmitted to the movable platen 14 via the cross head 16 and the toggle link mechanism L, and the movable platen 14 moves forward.

  At this time, the rotation of the servo motor 22 is detected by the rotary encoder 23 and converted into a mold closing speed (speed detection value) Vd by the speed conversion unit 60, and the speed detection value Vd is inverted by the deviation calculation unit 56. It is given to the input part. Since the switching unit 54 is switched to the side for selecting the speed target value Vs by the switching determination unit 55, the preset speed target value Vs is given to the non-inverting input unit of the deviation calculating unit 56. Since the deviation between the speed detection value Vd and the speed target value Vs is obtained from the output unit of the deviation calculation unit 56, the deviation is speed compensated by the speed compensation unit 57 in which the PID constant is set, and then the current / power control is performed. Further, the current / power control unit 58 supplies power to the servo motor 22. The current flowing through the servo motor 22 is detected by the current detector 59 and applied to the current control unit 58, thereby performing minor loop feedback control on the current (electric power). The above is the feedback control system for the speed, and the feedback control for the mold closing speed is performed so that the speed detection value Vd matches the speed target value Vs. The speed target value Vs is set with a high-speed closing speed at the front stage and a low-speed closing speed at the rear stage.

  When the movable platen 14 reaches the target mold clamping position, the rotation of the servo motor 22 is stopped, and the switching determination unit 55 switches the switching unit 54 to the side for selecting the pressure compensation unit 53. On the other hand, on the injection device Mi side, an injection filling process is performed, and injection filling of the molten resin into the mold 15 is performed.

  At this time, an injection molding process using the pressure control pattern Cx is executed on the mold clamping device Mc side. That is, after the switching unit 54 is switched to the side for selecting the pressure compensation unit 53, the pressure sensor 52 detects the mold clamping forces Px, Pxa (pressure detection value Pd), and the inverting input of the deviation calculating unit 51 is detected. The pressure target value Ps based on the pressure control pattern Cx is given to the non-inverting input part of the deviation calculating part 51. Thereby, a deviation between the pressure target value Ps and the detected pressure value Pd is obtained at the output part of the deviation calculating part 51, and this deviation is given to the pressure compensating part 53 in which the PID constant is set. In this case, since the pressure target value Ps is given as the pressure control pattern Cx, the mold clamping forces Px, Pxa,... Change. The processing unit 61 monitors changes in the mold clamping forces Px, Pxa, and controls the pressure compensation unit 53 to set pressure compensation gains Kx or Kxa corresponding to changes (switching) in the mold clamping forces Px, Pxa,. Is performed (step S10).

  As described above, even when the injection molding is performed using the pressure control pattern Cx in which a plurality of different mold clamping forces Px, Pxa,... Are set in multiple stages, the change in the mold clamping force Pxa. Since the pressure compensation constants Kx, Kxa,... Are changed, the pressure control pattern Cx prevents the occurrence of dull (bad) responsiveness, disturbance of behavior, undershoot and overshoot, and pressure control response. Can be stabilized, and highly accurate pressure control can be performed. The solid line shown in FIG. 5 shows the pressure control pattern Cx when the mold clamping control method according to the present embodiment is used. The pressure control pattern Cx has a dull (bad) responsiveness, a disordered behavior, an undershoot and an overshoot. Shooting is effectively prevented.

  The output from the pressure compensation unit 53 is given to the non-inverting input unit of the deviation calculation unit 56 through the switching unit 54 as the pressure compensation speed Vp. When the injection molding (clamping process) is completed, a cooling process, a mold opening process, and a protruding process are obtained and one molding cycle is completed. In this example, the case where the pressure control pattern Cx shown in FIG. 5 is used is shown. However, even when the pressure control pattern Cy shown in FIG.

  Further, as shown in FIG. 4, the maximum mold clamping force Pe other than the function Fx related to the maximum mold clamping force Px (100 [%]) and the function Fy related to the maximum mold clamping force Py (50 [%]) is also obtained. In this case, it can be obtained by estimation based on the functions Fx and Fy indicating two correlations. That is, as an example, when 80% is applied as the maximum mold clamping force Pe, the target pressure compensation gain can be obtained by proportional distribution between the functions Fx and Fy. Thus, by using the minimum amount of data, even the pressure compensation gain Kea... At other maximum clamping force Pe other than the maximum clamping force Px, Py can be easily and reliably obtained. There are advantages.

  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 embodiment, the case where the pressure compensation gain in the pressure feedback control system Up is applied as the pressure compensation constants Kxa..., Kya..., But other pressure compensations such as the I constant and the D constant of the PID constant are necessary. It can also be applied to constants. Moreover, although the case where the functions Fx and Fy that approximate the correlation are set using the pressure compensation constants Kxsa..., Kysa... Corresponding to the magnitudes of different mold clamping forces Psa. A plurality of pressure compensation constants Kxsa... Kysa... Corresponding to the magnitude of the tightening force Psa. If such a database Bd is used for setting, there is an advantage that it can be set by simple processing without any computation. Furthermore, although the case where two correlations with different maximum clamping forces Px and Py are included is shown in the correlation, three or more correlations may be included.

The flowchart for demonstrating the mold-clamping control method of the injection molding machine which concerns on the best embodiment of this invention, A plan view of a toggle type mold clamping device capable of performing the mold clamping control method, Functional block diagram of a molding machine controller used for the toggle type mold clamping device, Explanatory diagram of functions used to implement the same mold clamping control method, Explanatory drawing of the pressure control pattern used for implementation of the same mold clamping control method, Explanatory drawing of the other pressure control pattern used for implementation of the same mold clamping control method,

Explanation of symbols

  M: injection molding machine, Mc: toggle type clamping device, Pxa ...: clamping force, Pya ...: clamping force, Psa ...: clamping force, Px: maximum clamping force, Py: maximum clamping force, Pe : Other maximum clamping force, Cx: Pressure control pattern, Cy: Pressure control pattern, Kxa ...: Pressure compensation constant, Kya ...: Pressure compensation constant, Kxsa ...: Appropriate pressure compensation constant, Kysa ...: Appropriate pressure compensation Constant, Fx: Function, Fy: Function, Up: Pressure feedback control system, Bd: Database

Claims (4)

  In a mold clamping control method of an injection molding machine in which injection molding is performed by a toggle type mold clamping device using a pressure control pattern in which a plurality of different mold clamping forces are set in multiple stages, a pressure compensation constant for the magnitude of the mold clamping force in advance. Is set by a function that approximates the correlation using pressure compensation constants corresponding to different magnitudes of a plurality of mold clamping forces, or a plurality of pressures corresponding to different magnitudes of the mold clamping forces. Compensation constants are set by a database, and by this correlation, pressure compensation constants corresponding to the magnitudes of the respective mold clamping forces in the pressure control pattern are respectively determined and set, and the pressure control is performed when performing the injection molding. A mold clamping control method for an injection molding machine, wherein the pressure compensation constant is changed in accordance with a change in a mold clamping force due to a pattern.   2. The mold clamping control method for an injection molding machine according to claim 1, wherein the pressure compensation constant is a pressure compensation gain in a pressure feedback control system.   3. The mold clamping control method for an injection molding machine according to claim 1, wherein the correlation includes at least two correlations with different maximum mold clamping forces.   4. The mold clamping control method for an injection molding machine according to claim 3, wherein the pressure compensation constant at the maximum mold clamping force other than the maximum mold clamping force is obtained by estimation based on at least two correlations.

Images