JPWO2008143277A1 - Mold clamping device and mold clamping device control method - Google Patents

Abstract

A mold clamping device having an electromagnet for driving a mold clamping operation and a mold opening / closing drive unit, and variably controls the mold opening / closing drive unit during generation of a mold clamping force by the electromagnet. As described above, a mold clamping device capable of improving the accuracy of the position where the mold clamping force is generated in relation to the mold opening / closing drive unit is provided.

Description

  The present invention relates to a mold clamping device and a mold clamping device control method.

  2. Description of the Related Art Conventionally, in an injection molding machine, resin is injected from an injection nozzle of an injection device, filled into a cavity space between a fixed mold and a movable mold, and solidified to obtain a molded product. ing. A mold clamping device is provided for moving the movable mold relative to the fixed mold to perform mold closing, mold clamping, and mold opening.

  The mold clamping device includes a hydraulic mold clamping device that is driven by supplying oil to a hydraulic cylinder, and an electric mold clamping device that is driven by an electric motor. It is widely used because it has high controllability, does not pollute the surroundings, and has high energy efficiency. In this case, by driving the electric motor, the ball screw is rotated to generate a thrust, and the thrust is expanded by a toggle mechanism to generate a large mold clamping force.

  However, since the electric mold clamping device having the above-described configuration uses a toggle mechanism, it is difficult to change the mold clamping force due to the characteristics of the toggle mechanism, and the responsiveness and stability are improved. The mold clamping force cannot be controlled during molding. Therefore, a mold clamping device is provided in which the thrust generated by the ball screw can be directly used as a mold clamping force. In this case, since the torque of the electric motor and the mold clamping force are proportional, the mold clamping force can be controlled during molding.

  However, in the conventional mold clamping device, the load resistance of the ball screw is low and a large mold clamping force cannot be generated, and the mold clamping force fluctuates due to torque ripple generated in the electric motor. In addition, in order to generate the mold clamping force, it is necessary to constantly supply current to the motor, and the power consumption and heat generation amount of the motor increase. Therefore, it is necessary to increase the rated output of the motor by that amount. The cost of the device becomes high.

Therefore, a mold clamping device using a linear motor for the mold opening / closing operation and utilizing the attractive force of an electromagnet for the mold clamping operation is conceivable (for example, Patent Document 1).
WO05 / 090052 pamphlet

  However, in the mold clamping device described in Patent Document 1, a mold opening / closing drive part and a mold clamping drive part (electromagnet) are provided independently of each other. Therefore, if the timing for closing the mold and the timing for applying the clamping force are not properly controlled, there is a possibility that a molding failure or a mold breakage may occur.

  For example, if the torque limit value of the drive unit for opening and closing the mold is set to 0 before entering the mold clamping process (when supply of current to the drive unit for opening and closing the mold is stopped), mold clamping force is generated. In the meantime, the position of the mold that should have been position-controlled once will shift. If it does so, it will become difficult to generate | occur | produce a mold clamping force in the position which was anticipated, and there exists a possibility of producing the above-mentioned shaping | molding defects.

  In particular, in ultra-high precision molding, there is a method called opening molding in which resin is injected before a mold clamping force is applied. In this case, highly accurate position control on the order of several μm is necessary, and a slight shift in the position of the mold cannot be ignored.

  The present invention has been made in view of the above points, and can provide a mold clamping device and a mold clamping device control method capable of improving the accuracy of a position where a mold clamping force is generated in relation to a mold opening / closing drive unit. The purpose is to provide.

  Accordingly, in order to solve the above problems, the present invention provides a mold clamping device having an electromagnet for driving a mold clamping operation and a mold opening / closing drive unit, and the mold opening / closing drive unit during generation of a mold clamping force by the electromagnet. Is variably controlled.

  According to the present invention, the mold opening / closing drive unit is a linear motor, and a current for position control is supplied to the linear motor during the step-up process by the electromagnet.

  Further, the present invention is characterized in that a current for position control is supplied to the linear motor during the step of boosting by the electromagnet.

  Further, the present invention is characterized in that the current is supplied to the linear motor until a clamping force by the electromagnet reaches a predetermined value.

  Further, the present invention is characterized in that the predetermined value is larger than a force related to cogging or the like of the linear motor.

  Further, the present invention is characterized in that the supply of current to the linear motor is stopped after the mold clamping force reaches the predetermined value.

  Further, the present invention is characterized in that the current is supplied to the linear motor in a predetermined period after generation of the clamping force by the electromagnet.

  According to the present invention, it is possible to provide a mold clamping device and a mold clamping device control method capable of improving the accuracy of the position where the mold clamping force is generated in relation to the mold opening / closing drive unit.

It is a figure which shows the state at the time of the mold closing of the metal mold apparatus and mold clamping apparatus in embodiment of this invention. It is a figure which shows the state at the time of the mold opening of the metal mold | die apparatus and mold clamping apparatus in embodiment of this invention. It is a figure for demonstrating operation | movement of the mold clamping apparatus in a mold closing process and a mold clamping process. It is a figure which shows the modification which applied the rotary motor which closed the generation | occurrence | production area | region of the magnetic field with the motor frame.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this embodiment, for the mold clamping device, the moving direction of the movable platen when closing the mold is the front, the moving direction of the movable platen when opening the mold is the rear, and the injection device is the injection The description will be made assuming that the moving direction of the screw when performing the measurement is the front and the moving direction of the screw when performing the measurement is the rear.

  FIG. 1 is a view showing a state of a mold apparatus and a mold clamping apparatus when the mold is closed in the embodiment of the present invention, and FIG. 2 is a state when the mold apparatus and the mold clamping apparatus are opened in the embodiment of the present invention. FIG.

  In the figure, 10 is a mold clamping device, Fr is a frame of an injection molding machine, Gd is laid on the frame Fr to form a rail, and supports the mold clamping device 10 as a first guide member for guiding it. The two guides (in the figure, only one of the two guides Gd is shown) 11 is placed on the guide Gd and fixed to the frame Fr and the guide Gd. A fixed platen as a first fixing member, and a rear platen 13 as a second fixing member is disposed at a predetermined distance from the fixed platen 11 and opposed to the fixed platen 11, and the fixed platen A tie bar 14 (only two of the four tie bars 14 are shown in the figure) is laid between 11 and the rear platen 13 as four connecting members. The rear platen 13 is placed on the guide Gd so that it can move slightly with respect to the guide Gd as the tie bar 14 expands and contracts.

  In the present embodiment, the fixed platen 11 is fixed with respect to the frame Fr, and the rear platen 13 can move slightly with respect to the guide Gd. However, the rear platen 13 is moved to the frame Fr and the guide. The stationary platen 11 can be moved slightly with respect to the guide Gd.

  A movable platen 12 as a first movable member is disposed along the tie bar 14 so as to face the fixed platen 11 so as to be movable back and forth in the mold opening / closing direction. For this purpose, a guide hole (not shown) for penetrating the tie bar 14 is formed at a position corresponding to the tie bar 14 in the movable platen 12.

  A first screw portion (not shown) is formed at the front end portion of the tie bar 14, and the tie bar 14 is fixed to the fixed platen 11 by screwing the first screw portion and the nut n1. Further, a guide post 21 as a second guide member having an outer diameter smaller than that of the tie bar 14 is protruded rearward from the rear end surface of the rear platen 13 at a predetermined portion at the rear of each tie bar 14, and It is formed integrally with the tie bar 14. A second screw portion (not shown) is formed in the vicinity of the rear end surface of the rear platen 13, and the fixed platen 11 and the rear platen 13 are connected by screwing the second screw portion and the nut n2. The In the present embodiment, the guide post 21 is formed integrally with the tie bar 14, but the guide post 21 may be formed separately from the tie bar 14.

  A fixed mold 15 as a first mold is fixed to the fixed platen 11, and a movable mold 16 as a second mold is fixed to the movable platen 12. Accordingly, the fixed mold 15 and the movable mold 16 are brought into contact with and separated from each other, and mold closing, mold clamping, and mold opening are performed. As the mold clamping is performed, a plurality of cavity spaces (not shown) are formed between the fixed mold 15 and the movable mold 16, and the molding material injected from the injection nozzle 18 of the injection apparatus 17 is used as a molding material. Resin (not shown) is filled in each cavity space. A mold device 19 is configured by the fixed mold 15 and the movable mold 16.

  A suction plate 22 as a second movable member disposed in parallel with the movable platen 12 is disposed behind the rear platen 13 so as to be able to advance and retract along the guide posts 21 and is guided by the guide posts 21. Is done. The suction plate 22 is formed with guide holes 23 through the guide posts 21 at locations corresponding to the guide posts 21. The guide hole 23 is opened at the front end surface, and has a large diameter portion 24 that accommodates the ball nut n2 and a sliding surface that is opened at the rear end surface of the suction plate 22 and is slid with the guide post 21. A small diameter portion 25 is provided. In the present embodiment, the suction plate 22 is guided by the guide post 21, but the suction plate 22 can be guided not only by the guide post 21 but also by the guide Gd.

  By the way, in order to move the movable platen 12 forward and backward, a linear motor 28 as a first drive unit and as a mold opening / closing drive unit (mold opening / closing drive unit) is provided between the movable platen 12 and the frame Fr. It is arranged. The linear motor 28 includes a stator 29 as a first drive element and a mover 31 as a second drive element. The stator 29 is parallel to the guide Gd on the frame Fr. In addition, the movable platen 12 is formed corresponding to the moving range of the movable platen 12, and the movable element 31 is formed at a lower end of the movable platen 12 so as to face the stator 29 and over a predetermined range.

  The mover 31 includes a core 34 and a coil 35. The core 34 includes a plurality of magnetic pole teeth 33 that are protruded toward the stator 29 and formed at a predetermined pitch, and the coil 35 is wound around the magnetic pole teeth 33. The magnetic pole teeth 33 are formed in parallel to each other in a direction perpendicular to the moving direction of the movable platen 12. The stator 29 includes a core (not shown) and a permanent magnet (not shown) formed to extend on the core. The permanent magnet is formed by magnetizing the N-pole and S-pole magnetic poles alternately and at the same pitch as the magnetic pole teeth 33.

  Here, since a permanent magnet is used for the linear motor 28, the strength of the magnetic field is formed in the magnetic field formed between the stator 29 and the mover 31. Due to the strength of the magnetic field, cogging in which the position is restricted by the magnetic force of the permanent magnet occurs in the mover 31. For this reason, it is necessary to supply the coil 35 with a current sufficient to overcome cogging.

  When the linear motor 28 is driven by supplying a predetermined current to the coil 35, the movable element 31 is moved forward and backward, and accordingly, the movable platen 12 is moved forward and backward to perform mold closing and mold opening. it can.

  In the present embodiment, the permanent magnet is disposed on the stator 29 and the coil 35 is disposed on the mover 31, but the coil is disposed on the stator and the permanent magnet is disposed on the mover. You can also. In this case, since the coil does not move as the linear motor 28 is driven, wiring for supplying power to the coil can be easily performed.

  When the movable platen 12 is moved forward and the movable mold 16 abuts against the fixed mold 15, the mold is closed and subsequently the mold is clamped. In order to perform mold clamping, an electromagnet unit 37 is disposed between the rear platen 13 and the suction plate 22 as a second driving unit and as a mold clamping driving unit. A rod 39 as a clamping force transmission member that extends through the rear platen 13 and the suction plate 22 and connects the movable platen 12 and the suction plate 22 is disposed so as to freely advance and retract. The rod 39 advances and retracts the suction plate 22 in conjunction with the advance and retreat of the movable platen 12 when the mold is closed and opened, and transmits the mold clamping force generated by the electromagnet unit 37 to the movable platen 12 during mold clamping. To do.

  The mold clamping device 10 is configured by the fixed platen 11, the movable platen 12, the rear platen 13, the suction plate 22, the linear motor 28, the electromagnet unit 37, the rod 39, and the like.

  The electromagnet unit 37 includes an electromagnet 49 as a first driving member formed on the rear platen 13 side, and an attracting portion 51 as a second driving member formed on the attracting plate 22 side. A predetermined portion of the front end surface of the attracting plate 22, in the present embodiment, is formed in a portion that surrounds the rod 39 and faces the electromagnet 49 in the attracting plate 22. In addition, in the present embodiment, two grooves 45 as coil arrangement portions having a rectangular cross-sectional shape are parallel to each other at a predetermined portion of the rear end surface of the rear platen 13, slightly above and below the rod 39. A core 46 having a rectangular shape is formed between the grooves 45, and a yoke 47 is formed in another portion. A coil 48 is wound around the core 46.

  In addition, although the said core 46 and the yoke 47 are comprised by the integral structure of a casting, they may be formed by laminating | stacking the thin plate which consists of a ferromagnetic material, and may comprise an electromagnetic laminated steel plate.

  In the present embodiment, the electromagnet 49 is formed separately from the rear platen 13, and the attracting portion 51 is formed separately from the attracting plate 22. The electromagnet is formed as a part of the rear platen 13, and the attracting portion is formed as a part of the attracting plate 22. It can also be formed.

  Therefore, in the electromagnet unit 37, when an electric current is supplied to the coil 48, the electromagnet 49 is driven to attract the attracting part 51 and generate the mold clamping force.

  The rod 39 is connected to the suction plate 22 at the rear end and is connected to the movable platen 12 at the front end. Therefore, the rod 39 is moved forward as the movable platen 12 moves forward when the mold is closed to advance the suction plate 22, and is moved backward as the movable platen 12 is moved backward when the mold is opened. Retreat.

  For this purpose, a hole 41 for penetrating the rod 39 and a hole 42 for penetrating the rod 39 are formed in the central portion of the rear platen 13 and the central portion of the suction plate 22. A bearing member Br1 such as a bush that slidably supports the rod 39 is provided facing the opening. Further, a screw 43 is formed at the rear end of the rod 39, and the screw 43 and a nut 44 as a mold thickness adjusting mechanism supported rotatably on the suction plate 22 are screwed together.

  By the way, when the mold closing is completed, the suction plate 22 is brought close to the rear platen 13, and a gap δ is formed between the rear platen 13 and the suction plate 22. However, the gap δ becomes too small or large. If it is too large, the adsorbing part 51 cannot be adsorbed sufficiently, and the mold clamping force becomes small. The optimum gap δ changes as the thickness of the mold apparatus 19 changes.

  Therefore, a large-diameter gear (not shown) is formed on the outer peripheral surface of the nut 44, and a die thickness adjusting motor (not shown) as a die thickness adjusting driving unit is disposed on the suction plate 22. A small-diameter gear attached to the output shaft of the motor is engaged with a gear formed on the outer peripheral surface of the nut 44.

  Then, when the mold thickness adjusting motor is driven according to the thickness of the mold device 19 and the nut 44 is rotated by a predetermined amount with respect to the screw 43, the position of the rod 39 with respect to the suction plate 22 is adjusted, The position of the suction plate 22 with respect to the fixed platen 11 and the movable platen 12 is adjusted, and the gap δ can be set to an optimum value. That is, the mold thickness is adjusted by changing the relative positions of the movable platen 12 and the suction plate 22.

  The mold thickness adjusting device is configured by the mold thickness adjusting motor, the gear, the nut 44, the rod 39, and the like. In addition, a rotation transmitting portion that transmits the rotation of the mold thickness adjusting motor to the nut 44 is constituted by the gear. The nut 44 and the screw 43 constitute a movement direction conversion unit, and the rotation direction of the nut 44 is converted into a straight movement of the rod 39 in the movement direction conversion unit. In this case, the nut 44 constitutes the first conversion element, and the screw 43 constitutes the second conversion element.

  The driving of the linear motor 28 and the electromagnet 49 of the mold clamping device 10 is controlled by the control unit 60. The control unit 60 includes a CPU, a memory, and the like, and also includes a circuit for supplying current to the coil 35 of the linear motor 28 and the coil 48 of the electromagnet 49 according to the result calculated by the CPU. A load detector 55 is also connected to the control unit 60. The load detector 55 is installed at a predetermined position (a predetermined position between the fixed platen 11 and the rear platen 13) of at least one tie bar 14 in the mold clamping device 10, and detects a load applied to the tie bar 14. . In the drawing, an example in which a load detector 55 is installed on two upper and lower tie bars 14 is shown. The load detector 55 is constituted by, for example, a sensor that detects the extension amount of the tie bar 14. The load detected by the load detector 55 is sent to the control unit 60. The control unit 60 is omitted for convenience in FIG.

  Hereinafter, the operation of the mold clamping apparatus 10 having the above-described configuration will be described.

  The mold closing process is controlled by the mold opening / closing processor 61 of the controller 60. In the state of FIG. 2 (the state at the time of mold opening), the mold opening / closing processor 61 supplies current to the coil 35. Subsequently, the linear motor 28 is driven, the movable platen 12 is advanced, and the movable mold 16 is brought into contact with the fixed mold 15 as shown in FIG. At this time, a gap δ is formed between the rear platen 13 and the suction plate 22, that is, between the electromagnet 49 and the suction portion 51. Note that the force required for mold closing is sufficiently reduced compared to the mold clamping force.

  Subsequently, the mold clamping processing unit 62 of the control unit 60 controls the mold clamping process. The mold clamping unit 62 supplies current to the coil 48 and attracts the attracting part 51 by the attracting force of the electromagnet 49. Along with this, the clamping force is transmitted to the movable platen 12 via the suction plate 22 and the rod 39, and clamping is performed. Under this structure, in the present embodiment, when the mold clamping force is changed, such as at the start of mold clamping, the mold clamping processing unit 62 is the target mold clamping force to be obtained by the change, that is, in a steady state. Target clamping force (hereinafter, this mold clamping force is referred to as “steady mold clamping force”) A steady current (hereinafter, this current is referred to as “rated current”) necessary to generate a target clamping force. Is controlled to be supplied to the coil 48.

  The mold clamping force is detected by the load detector 55. The detected mold clamping force is sent to the control unit 60, where the current supplied to the coil 48 is adjusted so that the mold clamping force becomes a set value, and feedback control is performed. During this time, the resin melted in the injection device 17 is injected from the injection nozzle 18 and filled in each cavity space of the mold device 19.

  When the resin in each cavity space is cooled and solidified, the mold opening / closing processor 61 controls the mold opening process. The mold clamping processing unit 62 stops the supply of current to the coil 48 in the state of FIG. Along with this, the linear motor 28 is driven, the movable platen 12 is moved backward, and the movable mold 16 is placed in the retracted limit position as shown in FIG.

  The mold closing process and the mold clamping process will be described in more detail. FIG. 3 is a view for explaining the operation of the mold clamping device in the mold closing process and the mold clamping process. In the graph shown in FIG. 3, four broken lines or curves are shown. The horizontal axis of the graph is common to each broken line or curve and indicates time (elapsed time). The vertical axis of the graph differs depending on each line or curve.

  A broken line a indicates a torque output limit (limit value) of the linear motor 28 output from the mold opening / closing processor 61 of the controller 60. For the broken line a, the vertical axis indicates the torque value. A curve b indicates the position of the movable platen 12 that is moved by the linear motor 28. For the curve b, the vertical axis indicates the position. A broken line c indicates a command value of the mold clamping force output from the mold clamping processing unit 62 of the control unit 60. Curve d shows the actual value of the clamping force detected by the load detector 55. For the broken line c and the curve d, the vertical axis indicates the magnitude of the clamping force.

In the graph of FIG. 3, the period between time t _{1 and} t ₂ corresponds to a mold closing process. That is, the mold clamping device 10 is in the state shown at time t ₁ in FIG. 2, the state shown at time t ₂ in FIG. 1.

In FIG. 3, the mold closing process includes a traveling section and a low pressure section. At time t ₁ , when a current is supplied to the coil 35 based on the control of the mold opening / closing processor 61, the traveling section is started. In the traveling section, as indicated by the broken line a, a command for opening (maximizing) the torque output limit is input from the mold opening / closing processing unit 61 to the linear motor 28. As a result, the movable platen 12 moves forward (in the direction of the mold touch position) at a high speed as indicated by the curve b. Accordingly, the gap δ between the rear platen 13 and the suction plate 22 is also reduced by the advance amount of the linear motor 28. By moving the movable platen 12 at a high speed during the traveling period, the molding cycle can be shortened and the productivity can be improved.

  When the mold opening / closing processor 61 detects that the position of the movable platen 12 has reached a preset low pressure start position (start position of the low pressure section), the torque output limit is set to a preset torque value (low pressure torque). A command for narrowing (decreasing) is input to the linear motor 28. The linear motor 28 is provided with a position detector such as an encoder (not shown), and information indicating the position of the linear motor 28 (that is, the position of the movable platen 12) is sent to the control unit 60 from the position detector. Have been entered.

By restricting the torque output limit, the mold is prevented from being damaged when a foreign object is sandwiched between the molds. In accordance with this, the movable platen 12 is decelerated (the forward speed is reduced) as shown by the curve b. Movable platen 12 (linear motor 28) is a position control at a sufficiently decelerated state so as not to damage the mold apparatus 19 or the like, to stop according to the position control to reach the mold clamping start position at time t _2.

Time t ₂ later, it corresponds to the mold clamping process. Here, when clamping is performed using the electromagnet 49, since the clamping force is generated by narrowing the gap δ due to the electromagnetic force, the gap δ is large when the electromagnetic force is generated. For this reason, the rising responsiveness from when an electric current is passed through the electromagnet 49 until a predetermined mold clamping force is generated between the molds is poor, and it takes time. In ultra-high precision molding, there is a method called opening molding in which resin is injected before the mold comes into full contact. In the mold clamping device 10 using the electromagnet 49, the gap δ when the electromagnetic force is generated is larger in the opening molding than in the normal molding. For this reason, it takes time until the mold clamping force is generated. In this case, strictly speaking, the mold clamping process is started after the electromagnetic force is generated in a state where the mold does not contact (touch). In view of such points, the “mold touch position” in the present embodiment refers to the position of the movable platen 12 where the mold clamping process should be started regardless of whether or not the mold is in contact.

As indicated by the broken line c, at the mold touch position (time t ₂ ), the mold clamping processing unit 62 outputs a command for generating a steady mold clamping force. In response to the command, a rated current is supplied to the coil 48 of the electromagnet 49, and an electromagnetic force is generated in the gap δ between the rear platen 13 and the suction plate 22. Thereby, as shown by the curve d, the electromagnetic force generated by the electromagnet 49 increases, and the mold clamping force also increases. With increasing clamping force, the movable platen 12 is advanced further, the movable mold 16 abuts the stationary mold 15 at time t _4, complete mold closing is performed. At this time, in the mouth opening molding, the filled resin is compressed as the distance between the molds is reduced. As indicated by the curve d, the clamping force can then be continued to increase, reaching the rated clamping force at time t _5, then the mold clamping step is rated clamping force is maintained. Section from the t ₂ to the clamping force of up to t ₅ reaches the rated clamping force, the boost step in the mold clamping process.

  On the other hand, the mold opening / closing processor 61 supplies current to the coil 35 of the linear motor 28 in order to perform position control for maintaining the position of the movable platen 12 at the mold touch position even after reaching the mold touch position. Continue. However, as indicated by the broken line a, the torque output limit after reaching the mold touch position is limited to such an extent that the displacement of the position of the linear motor 28 is prevented by cogging (holding torque). In the opening molding, even if the resin is filled, the output of the linear motor 28 is an output that can counter the pressure of the filled resin so that the linear motor 28 does not move backward.

  When the mold clamping force generated by the electromagnet increases and the cogging of the linear motor 28 is negligible (that is, when the mold clamping force becomes larger than the force related to cogging) (time t3 in the figure), the mold opening / closing process is performed. The unit 61 variably controls the supply of current to the coil 35 of the linear motor 28. Specifically, the supply of current is stopped. Thereby, the influence on the mold clamping force due to the position control of the linear motor 28 is eliminated. The timing of stopping the supply of current to the coil 35 may be based on the passage of time, not the mold clamping force. In other words, after the start of the generation of the clamping force, the time until the clamping force becomes larger than the force related to cogging is calculated in advance or obtained by an empirical value, current is supplied for the period related to the time, You may make it stop supply of an electric current after progress. In this manner, by continuing the supply of current to the linear motor 28 until the mold clamping force larger than the output of the linear motor 28 is generated after the electromagnetic force is generated, the injection operation is performed before the mold closing is completed. Even in the case of the mouth opening molding, the resin leakage from between the movable mold 16 and the fixed mold 15 can be prevented.

  Note that the torque output limit of the linear motor 28 may be decreased in multiple stages in the travel section, the low pressure section, and the mold clamping process.

  As described above, according to the mold clamping device 10 in the present embodiment, even after the mold clamping process is started (a process in which the mold clamping force increases), current is supplied to the linear motor 28 to control the position at the mold touch position. Is done. Therefore, the shift of the mold touch position due to the cogging of the linear motor 28 can be prevented, and the mold clamping force can be generated from the planned position (mold touch position). Thereby, the incidence of molding defects and the like can be reduced.

  In the present embodiment, an electromagnet 49 is formed on the rear end surface of the rear platen 13, and the attracting portion 51 is disposed on the front end surface of the attracting plate 22 so as to be capable of moving forward and backward. However, it is possible to dispose the electromagnet on the front end surface of the suction plate 22 so as to be able to advance and retreat, with the suction portion opposed to the suction portion on the rear end surface of the rear platen 13.

  Note that the mold clamping device control method in the present embodiment may not be a mold clamping device that performs the mold opening and closing operation by driving the linear motor 28. In particular, in the case of the linear motor 28, there is a possibility that dust or the like adheres because the magnet is exposed on the surface of the frame. For this reason, the modification of this application which applied the rotary type motor which closed the magnetic field generation | occurrence | production area | region with the motor frame, without using the linear motor 28 as a type | mold opening / closing drive part is shown in FIG.

  The description of the electromagnet unit as the second drive unit is the same as in FIGS. A mold opening / closing motor 74 as a first driving section and as a mold opening / closing driving section (mold opening / closing driving section) is attached to a motor support 73 fixed to the frame so as not to move. Here, as the mold opening / closing motor 74, a rotary motor in which a magnetic field generation region is closed by a motor frame is applied. A motor shaft (not shown) projects from the rotary motor, and the motor shaft is connected to the ball screw shaft 72. The ball screw shaft 72 is engaged with the ball screw nut 71 to constitute a motion direction conversion device that converts the rotational motion generated by the rotary motor into a straight motion. The ball screw nut 71 is non-rotatably disposed on the movable platen flange portion 12 a protruding from the lower portion of the movable platen 12. Thereby, when the mold opening / closing motor 74 rotates, the movable platen 12 moves back and forth, and the mold opening / closing operation of the movable mold 16 can be performed.

  Further, a position detector 75 is attached to the rear end of the mold opening / closing motor 74, and the position of the movable platen 12 can be grasped by reading the rotation angle of the mold opening / closing motor 74. As a result, the mold opening / closing processor 61 controls the mold opening / closing motor 74.

  In this configuration, when the mold clamping force is being applied to the mold apparatus 19 by the electromagnet, more specifically, after the start of pressure increase, the mold opening / closing processing unit 61 is eliminated when there is no risk of occurrence of the mold displacement. Variably controls the supply of current to the mold opening / closing motor 74. Specifically, the supply of current is stopped. Thereby, the influence on the mold clamping force due to the position control of the mold opening / closing motor 74 is eliminated.

  As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to such specific embodiment, In the range of the summary of this invention described in the claim, various deformation | transformation・ Change is possible.

  This international application claims priority based on Japanese Patent Application No. 2007-134623 filed on May 21, 2007, and the entire contents of 2007-134623 are incorporated herein by reference.

Claims (14)

A mold clamping device having an electromagnet for driving a mold clamping operation and a mold opening / closing drive unit,
A mold clamping apparatus, wherein the mold opening / closing drive unit is variably controlled while a mold clamping force is generated by the electromagnet. The mold opening / closing drive unit is a linear motor,
2. The mold clamping apparatus according to claim 1, wherein a current for position control is supplied to the linear motor during the step of boosting by the electromagnet. The mold opening / closing drive unit is a rotary motor,
2. The mold clamping apparatus according to claim 1, wherein a current for position control is supplied to the rotary motor during the step of boosting by the electromagnet.   2. The mold clamping apparatus according to claim 1, wherein the current is supplied to the linear motor until a mold clamping force by the electromagnet reaches a predetermined value.   The mold clamping apparatus according to claim 4, wherein the predetermined value is larger than a force related to cogging of the linear motor.   The mold clamping device according to claim 4, wherein the supply of current to the linear motor is stopped after the mold clamping force reaches the predetermined value.   2. The mold clamping apparatus according to claim 1, wherein the current is supplied to the linear motor for a predetermined period after generation of the mold clamping force by the electromagnet. A method for controlling a mold clamping device having an electromagnet for driving a mold clamping operation and a mold opening / closing drive unit,
A mold clamping device control method, wherein the mold opening / closing drive unit is variably controlled while a mold clamping force is generated by the electromagnet. The mold opening / closing drive unit is a linear motor,
9. The mold clamping device control method according to claim 8, wherein a current for position control is supplied to the linear motor during the step of boosting by the electromagnet. The mold opening / closing drive unit is a rotary motor,
9. The mold clamping device control method according to claim 8, wherein a current for position control is supplied to the rotary motor during the step of boosting by the electromagnet.   9. The mold clamping device control method according to claim 8, wherein the current is supplied to the linear motor until a mold clamping force by the electromagnet reaches a predetermined value.   The mold clamping device control method according to claim 11, wherein the predetermined value is larger than a force related to cogging of the linear motor.   12. The mold clamping device control method according to claim 11, wherein the supply of current to the linear motor is stopped after the mold clamping force reaches the predetermined value.   9. The mold clamping device control method according to claim 8, wherein the current is supplied to the linear motor for a predetermined period after the mold clamping force is generated by the electromagnet.

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