TWI405658B - Locking device and mode - locked control method - Google Patents

Abstract

A clamping device for exerting clamping force by an electromagnet comprises a first current command generating unit for generating a current command to be given to the electromagnet according to the target clamping force, a clamping force detecting unit for detecting the clamping force exerted by the electromagnet, and a second current command generating unit for generating a correction command for correcting the current command according to the detected value of the clamping force detected by the clamping force detecting unit. Thus, the clamping device capable of properly controlling the clamping force exerted by the electromagnet is provided.

Description

Clamping device and mode locking control method

The invention relates to a clamping device and a mode locking control method.

Conventionally, in an injection molding machine, a resin is injected from an injection nozzle of an injection device, and is filled in a cavity space between a fixed mold and a movable mold, and is solidified, thereby obtaining a molded article. Further, in order to move the movable mold to the fixed mold and perform mold closing, mold clamping, and mold opening, a mold clamping device is disposed.

The mold clamping device has a hydraulic type clamping device driven by supplying oil to the hydraulic cylinder, and an electric clamping device driven by a motor. The electric clamping device has high controllability and does not It will pollute the surrounding area and is energy efficient, so it is often used. In this case, by driving the motor, the ball screw is rotated and thrust is generated, and the thrust is amplified by the toggle mechanism to generate a large clamping force.

However, in the electric mold clamping device of this configuration, a toggle mechanism is used, and it is difficult to change the clamping force due to the characteristics of the toggle mechanism, and the responsiveness and stability are poor, and the clamping force cannot be controlled during molding. Accordingly, there is provided a mold clamping device which is constructed to directly use the thrust generated by a ball screw as a clamping force. In this case, since the torque of the motor is proportional to the clamping force, the clamping force can be controlled during the forming.

However, in the conventional mold clamping device, the load resistance of the ball screw is low, and not only a large mold clamping force cannot be generated, but also the mold clamping force fluctuates due to the torque fluctuation generated by the motor. Further, in order to generate the clamping force, it is necessary to always supply a current to the motor. Since the power consumption and the amount of heat generated by the motor are increased, it is necessary to increase the rated power of the motor, and the cost of the mold clamping device becomes expensive.

Therefore, a mold clamping device (for example, Patent Document 1) has been conceived, which uses a linear motor in the opening and closing mode operation and a suction force of the electromagnet in the mold clamping operation. In the mold clamping device, feedback control is applied to the clamping force in order to keep the clamping force in the mold clamping step constant. Conventionally, the control unit that performs the feedback control has the following configuration.

Fig. 1 is a view showing a configuration example of a conventional control unit. In Fig. 1, 100 denotes a mold clamping device. 160 denotes a control unit that controls the clamping force of the mold clamping device 100. The control unit 160 has an adder 161, an integrator 162, and an amplifier 163. The adder 161 inputs a mold clamping force command (instruction indicating the magnitude of the target clamping force (target clamping force)) from the upper-order controller (not shown), and the clamping force detector of the self-locking device 100 155 Enter the detected value of the clamping force. The adder 161 calculates an error (clamping force error) for the target clamping force based on the clamping force command value and the clamping force detection value, and outputs it to the integrator 162. The integrator 162 calculates a current value for correcting the clamping force error by integrating the clamping force error, and outputs a current command indicating the current value to the amplifier 163. The amplifier 163 supplies a current of a current value indicated by a current command to the electromagnet 49. Thereafter, the clamping force detection value is sequentially input to the adder 161, and feedback control is performed.

Patent Document 1: Japanese Patent Publication No. Hei 10-244567

However, only the general feedback control is performed, and it is difficult to control the clamping force in a preferable state in view of the characteristics of the electromagnet.

Fig. 2 is a view for explaining the clamping force obtained by the conventional feedback control. In Fig. 2, the horizontal axis represents the passage of time, and the vertical axis represents the detected value of the clamping force. The curve L0 represents the clamping force obtained by the feedback control described above in response to the passage of time.

After the start of mode locking, the slope of curve L0 is small. This is caused by the poor responsiveness of the electromagnet. In other words, even if the electromagnet is supplied with a current of a certain current value, since the electromagnetic force is small when the distance between the gaps is large, the force corresponding to the current value cannot be instantaneously acted upon. Therefore, it takes a certain amount of time until the detected value of the clamping force reaches the target clamping force.

Thus, in the simple feedback control, there is a problem that the target clamping force cannot be obtained quickly. When the time until the target clamping force is reached becomes longer, the forming cycle also becomes longer, and the productivity is lowered.

The present invention has been made in view of the above problems, and an object thereof is to provide a mold clamping device and a mode locking control method capable of appropriately controlling a clamping force generated by an electromagnet.

Therefore, in order to solve the problem, the present invention is a mold clamping device that generates a clamping force by an electromagnet, and is characterized in that the first current command generating portion generates a current for the electromagnet in response to a target clamping force. a clamping force detecting unit that detects a clamping force by the electromagnet; and a second current command generating unit that generates a correction command based on the detected value of the clamping force detected by the clamping force detecting unit. Correct the current command.

Further, the present invention is characterized in that the correction current command calculation unit calculates the electromagnetic command based on the current command generated by the first current command generating unit and the correction command generated by the second current command generating unit. Correct current command for iron supply.

Further, the present invention is characterized in that the first current command generating unit generates a current command having a rising current command for generating the clamping force and a holding current command for maintaining the generated clamping force.

Further, the present invention is characterized in that the second current command generating unit generates the error based on the error of the clamping force maintained by the holding current command and the detected value of the clamping force detected by the clamping force detecting unit. Correct the instruction.

Further, the present invention is characterized in that the first current command generating unit generates a current command when starting the mode locking, and indicates a current value larger than a current corresponding to the target clamping force.

Further, the present invention is characterized in that the second current command generating unit generates the correction command based on an error between the target clamping force and the detected value of the clamping force.

Moreover, the present invention is characterized in that the switching unit has a switching unit that switches the operation and the stop of the second current command generating unit based on the detected value of the clamping force.

Further, the present invention is characterized in that the switching unit switches the operation and the stop of the second current command generating unit when the current is controlled by the holding current command in the current command generated by the first current command generating unit.

Further, the present invention is characterized in that the switching unit operates the second current command generating unit while maintaining the target clamping force.

Further, the present invention is characterized in that the switching unit stops the second current command generating unit for a predetermined period of time after the start of mold clamping.

Further, the present invention is characterized in that the switching unit stops the second current command generating unit for a predetermined period of time when the target clamping force is changed.

Further, the present invention is characterized in that the switching unit stops the second current command generating unit when the target clamping force is zero.

According to the present invention, it is possible to provide a mold clamping device and a mode locking control method which can appropriately control the clamping force generated by the electromagnet.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Further, in the description of the present embodiment, in the mold clamping device, the moving direction of the movable platen when the mold is closed is set to the front, and the moving direction of the movable platen when the mold is opened is set to the rear. In the injection device, the moving direction of the screw when the injection is performed is set to the front, and the moving direction of the screw when the measurement is performed is set to the rear.

3 is a view showing a state in which the mold apparatus and the mold clamping apparatus according to the embodiment of the present invention are closed, and FIG. 4 is a view showing a state in which the mold apparatus and the mold clamping apparatus according to the embodiment of the present invention are opened. Figure.

In the figure, a 10 series mold clamping device, a frame of an Fr injection molding machine, and a Gd system as two guide members of the first guiding member (only one of the two guide members Gd is shown in the drawing) is laid. Forming a rail on the frame Fr, and supporting and guiding the clamping device 10, 11 as a fixed platen of the first fixing member, which is placed on the guide Gd, and the frame Fr and the guide Gd is fixed, spaced apart from the fixed platen 11 by a predetermined interval, and a back plate 13 as a second fixing member and four tie bars 14 as connecting members are disposed opposite to the fixed platen 11 (only the figure is shown in the drawing) Two of the four tie bars 14 are mounted between the fixed platen 11 and the back plate 13. Further, the back plate 13 is placed on the guide Gd in such a manner that the guide Gd can be slightly moved as the tie bar 14 expands and contracts.

Further, in the present embodiment, although the fixed platen 11 is fixed to the frame Fr and the guide Gd, and the back plate 13 can slightly move the guide Gd, the back plate 13 can be fixed to the frame Fr and the guide Gd. And the fixed platen 11 can slightly move the guide Gd.

The movable platen 12 as the first movable member is disposed to face the tie rod 14 and the fixed platen 11 so as to be able to advance and retreat in the mold opening and closing direction. Therefore, a guide hole (not shown) through which the tie rod 14 is inserted is formed at a position corresponding to the tie bar 14 of the movable platen 12.

A first screw portion (not shown) is formed at a distal end portion of the tie rod 14, and the tie rod 14 is fixed to the fixed platen 11 by screwing the first screw portion and the nut n1. Further, in a predetermined portion behind the respective tie bars 14, the guide post 21 having the outer diameter smaller than the tie bar 14 as the second guide member protrudes rearward from the rear end surface of the back plate 13, and is integrated with the tie bar 14. Ground formation. Further, a second screw portion (not shown) is formed in the vicinity of the rear end surface of the back plate 13, and the fixed platen 11 and the back plate 13 are coupled by screwing the second screw portion and the nut n2. In the present embodiment, the guide post 21 and the tie bar 14 are integrally formed, but the guide post 21 and the tie bar 14 may be formed separately.

Moreover, the fixed mold 15 as the first mold is fixed to the fixed platen 11, and the movable mold 16 as the second mold is fixed to the movable platen 12, and the mold 15 and the movable mold are fixed as the movable platen 12 advances and retreats. 16 is close to or away from, and is closed, mold-locked, and opened. Further, 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 molded material which is emitted from the injection nozzle 18 of the injection device 17 is not shown. Resin is filled in the cavity spaces. Further, the mold device 19 is constituted by the fixed mold 15 and the movable mold 16.

On the other hand, the suction plate 22 as the second movable member disposed in parallel with the movable platen 12 is disposed to be advanced and retracted along the guide posts 21 behind the back plate 13, and guided by the guide post 21. Further, in the suction plate 22, a guide hole 23 through which the guide post 21 is inserted is formed at a position corresponding to each of the guide posts 21. The guide hole 23 is provided with a large-diameter portion 24, which is formed in the front end surface processing opening, and accommodates the ball nut n2. The small-diameter portion 25 is formed in the rear end surface of the suction plate 22, and is provided with the guide post 21 Sliding sliding surface. In the present embodiment, the suction plate 22 is guided by the guide post 21, but not only the guide post 21 but also the guide plate Gd can guide the suction plate 22.

In order to advance and retract the movable platen 12, a linear motor 28 as a driving unit for opening and closing the mold is disposed between the movable platen 12 and the frame Fr, and the linear motor 28 is provided. The stator 29 as the first driving element and the movable member 31 as the second driving element are formed on the frame Fr in parallel with the guide Gd and corresponding to the moving range of the movable platen 12, which is formed. The movable member 31 is opposed to the stator 29 at the lower end of the movable platen 12, and is formed within a predetermined range.

The movable member 31 includes a core 34 and a coil 35. Further, the core 34 is provided with a plurality of magnetic pole teeth 33 which protrude toward the stator 29 and are formed at a predetermined distance, and the coil 35 is wound around the magnetic pole teeth 33. Further, the magnetic pole teeth 33 are formed in parallel with each other in a direction perpendicular to the moving direction of the movable platen 12. Further, the stator 29 is provided with a core (not shown) and a permanent magnet (not shown) which is formed by extending the core. The permanent magnet is formed by alternating magnetic poles of the N pole and the S pole and magnetizing at the same pitch as the pole teeth 33.

Therefore, when the linear motor 28 is driven by supplying a predetermined current to the coil 35, the movable member 31 advances and retreats, and as the movable platen 12 advances and retracts, mold closing and mold opening can be performed.

Further, in the present embodiment, the permanent magnet is disposed in the stator 29, and the coil 35 is disposed in the movable member 31. However, the coil may be disposed in the stator, and the permanent magnet may be disposed in the movable member. In this case, as the linear motor 28 is driven, since the coil does not move, the wiring for supplying power to the coil can be easily performed.

On the other hand, when the movable platen 12 advances and the movable mold 16 and the fixed mold 15 abut each other, the mold is closed, and then the mold is clamped. On the other hand, in order to perform the mold clamping, the electromagnet unit 37 as the second drive unit and the drive unit for the mold clamping is disposed between the background plate 13 and the suction plate 22. On the other hand, the rod 39 as a communication member is disposed to advance and retreat freely. The rod 39 extends through the background plate 13 and the suction plate 22, and connects the movable platen 12 and the suction plate 22. When the rod 39 is closed and opened, the suction plate 22 is moved forward and backward in conjunction with the advancement and retreat of the movable platen 12, and the clamping force generated by the electromagnet unit 37 is transmitted to the movable platen 12 during the mold clamping. .

Further, the mold clamping device 10 is constituted by the fixed platen 11, the movable platen 12, the back plate 13, the suction plate 22, the linear motor 28, the electromagnet unit 37, and the rod 39.

Further, in the mold clamping device 10, the operation of the linear motor 28 as the drive unit for opening and closing the mold and the operation of the electromagnet unit 37 as the drive unit for the mold clamping are controlled by the control unit 60. Details of the control unit 60 will be described later.

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

Further, although the core 46 and the yoke 47 are configured by a single body structure of a casting, they may be formed by laminating thin plates made of a ferromagnetic material to constitute an electromagnetic laminated steel sheet.

In the present embodiment, although the electromagnet 49 is formed separately from the back plate 13, and the suction portion 51 is formed separately from the suction plate 22, an electromagnet may be formed in a part of the back plate 13 to form a part of the plate 22. Suck the department.

Therefore, when the electromagnet unit 37 supplies a current (direct current) to the coil 48, the electromagnet 49 is driven to suck the suction portion 51, and the clamping force can be generated.

Further, the rod 39 is disposed to be coupled to the suction plate 22 at the rear end portion, and coupled to the movable platen 12 at the front end portion. Therefore, the rod 39 advances as the movable platen 12 advances when the mold is closed, and the suction plate 22 advances, and retracts as the movable platen 12 retreats during mold opening, and the suction plate 22 retreats.

Therefore, in the central portion of the back plate 13, a hole 41 for penetrating the rod 39, and a hole 42 for penetrating the rod 39 through the central portion of the suction plate 22 are formed, and a bearing member such as a bushing is disposed. Br1, which faces the opening at the front end of the hole 41, supports the rod 39 to slide freely. Further, a screw 43 is formed at the rear end portion of the rod 39, and the screw 43 is screwed to a nut 44 which is supported as a mold thickness adjusting mechanism for freely rotating the suction plate 22.

A large-diameter gear (not shown) is formed on the outer circumferential surface of the nut 44, and a mold thickness adjusting motor (not shown) as a driving portion for adjusting the thickness is disposed on the suction plate 22, and is attached to the mold thickness. The gear having the small diameter of the output shaft of the adjustment motor meshes with the gear formed on the outer circumferential surface of the nut 44.

Further, the mold thickness adjusting motor is driven in a manner corresponding to the thickness of the mold device 19, and when the nut 44 is rotated by the screw 43 by a predetermined amount, the position of the adjusting lever 39 against the plate 22 is adjusted, and the suction plate 22 is adjusted. The position of the fixed platen 11 and the movable platen 12 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.

Further, in the present embodiment, the core 46, the yoke 47, and the suction plate 22 are entirely composed of an electromagnetic laminated steel sheet, but may be formed of an electromagnetic laminated steel sheet around the core 46 of the back plate 13 and the suction portion. 51. In the present embodiment, the electromagnet 49 is formed on the rear end surface of the back plate 13, and the suction portion 51 is disposed to advance and retreat at the distal end surface of the suction plate 22 so as to face the electromagnet 49. The suction portion may be disposed on the rear end surface of the back plate 13, and the electromagnet may be disposed to advance and retreat at the front end surface of the suction plate 22 so as to face the suction portion.

Next, the details of the control unit 60 will be described. Fig. 5 is a view showing an example of the structure of a control unit according to the first embodiment. In the first embodiment, the control unit 60a is described by the control unit 60a. The control unit 60a is composed of a higher-order controller 601, a current pattern generator 602, an integrator 603, an amplifier 604, adders 605 and 606, and the like.

The upper controller 601 is provided with a CPU, a memory, and the like, and controls the operations of the linear motor 28 and the electromagnet 49 by the CPU processing the control program recorded in the memory. The upper controller 601 outputs an instruction (clamping force command) indicating the magnitude of the clamping force and an instruction (position command) indicating the position at which the linear motor 28 should move. Further, in the present embodiment, a detailed description of the control of the linear motor 28 will be omitted. Therefore, even in the drawings, constituent elements for controlling the linear motor 28 are omitted.

The clamping force command from the upper stage controller 601 is input to the current pattern generator 602. The current pattern generator 602 is constituted, for example, by a servo card, and generates a current pattern in response to the clamping force indicated by the clamping force command. Here, the current pattern means a current value indicating a series of times when the electromagnet 49 (coil 48) is supplied. The current pattern generator 602 sequentially outputs a signal (current command) indicating the current value supplied to the electromagnet 49 to the adder 606 in accordance with the generated current pattern in response to the passage of time.

The clamping force command from the upper controller 601 is also input to the adder 605. The adder 605 also inputs the detected value (actual value) of the clamping force detected by the clamping force detector 55 provided to the mold clamping device 10. The adder 605 calculates an error (clamping force error) of the actual value of the clamping force command based on the value of the clamping force (the clamping force command value) and the clamping force detection value indicated by the clamping force command. The calculated clamping force error is input to the integrator 603. Further, the clamping force detector 55 may also use a sensor for detecting the elongation of the tie rod 14 or a load detector such as a load cell disposed on the rod 39, or between the detecting electromagnet 49 and the suction portion 51. The magnetic flux sensor is constructed.

In order to eliminate the clamping force error, the integrator 603 calculates a correction value for the current command by integrating the clamping force error, and sequentially outputs a signal (correction command) indicating the correction value to the adder 606.

The adder 606 as the correction current command unit corrects the current value (current) indicated by the current command input from the current pattern generator 602 based on the current value (correction command value) indicated by the correction command input from the integrator 603. The command value is), and a signal indicating the corrected current value (correction current command) is sequentially output to the amplifier 604.

The amplifier 604 is constituted, for example, by a driver card, and supplies a current corresponding to the correction current command input from the adder 606 to the electromagnet 49. The electromagnet 49 is driven in response to the supply of the current.

Further, in the present embodiment, the current pattern generator 602 constitutes the first current command generation unit 610, and the adder 605 and the integrator 603 constitute the second current command generation unit 620.

Next, the operation of the mold clamping device 10 of this configuration will be described.

The control unit 60 performs opening and closing mode processing, and supplies current to the coil 35 in the state of Fig. 4 when the mold is closed. Next, the linear motor 28 is driven, and the movable platen 12 advances. As shown in Fig. 3, the movable mold 16 and the fixed mold 15 abut. At this time, an optimum gap δ is formed between the back plate 13 and the suction plate 22, that is, between the electromagnet 49 and the suction portion 51. In addition, the force required to close the mold is much smaller than the clamping force.

When the movable platen 12 reaches a predetermined position (a position at which the movable mold 16 and the fixed mold 15 abut, or a position slightly before the abutment), the mold clamping step starts. That is, the upper-order controller 601 outputs a clamping force command indicating the target value (target clamping force) of the preset clamping force to the current pattern generator 602 and the adder 605. The current pattern generator 602 generates a current pattern in response to the clamping force command, and according to the current pattern, outputs a current command in response to the passage of time. Here, a current pattern is generated to improve the rise responsiveness of the clamping force by the electromagnet 49.

Figure 6 is a diagram for explaining the pattern of current generated by the current pattern generator. In Fig. 6(A), the current pattern L1 is indicated by a broken line of a broken line. (A) The vertical axis of the graph represents the current value, and the horizontal axis represents the passage of time. On the other hand, in the diagram (B), the transition of the clamping force obtained in the case where the current value corresponding to the current pattern is directly supplied to the coil 48 is indicated by the curve L2. (B) The vertical axis of the graph represents the clamping force, and the horizontal axis represents the passage of time. Further, the passage of time between the horizontal axis of (A) and the horizontal axis of (B) is the same.

As shown in Fig. 6, the current pattern L1 includes a rising current command for generating a clamping force at a predetermined period (t1 to t2) from the start of mold clamping, and then (after t2), includes a mold clamping force. Maintain current command. In the rising current command, for example, a current exceeding a current value (rated current) corresponding to the target clamping force of the maximum current (a current of a maximum current value that can be appropriately supplied from the control unit 60a) is used as a current command value. While maintaining the current command, the rated current is taken as the current command value. According to this current pattern, the coil 48 is supplied with a current far exceeding the rated current during the period from t1 to t2. As a result, the slope of the portion (the period from t1 to t2) indicated by the symbol a in the curve L2 in (B) of Fig. 6 becomes large. That is, the rise responsiveness of the electromagnet 49 is improved. In this manner, the current pattern generator 602 generates a current pattern that can improve the rise responsiveness of the electromagnet 49.

However, the clamping force obtained by the electromagnet 49 is affected by the hysteresis of the electromagnet 49, the error of the gap δ between the electromagnet 49 and the suction portion 51, or the error caused by the deformation of the resin, etc. It is not always possible to get the same size for the same current value. Therefore, even if the rated current is supplied, the target clamping force is not necessarily obtained. As shown in (B) of Fig. 6, a clamping force error e is generated between the target clamping force and the actual value.

Therefore, the control unit 60a does not directly supply the current according to the current pattern to the coil 48 in order to prevent the occurrence of the clamping force error e, but performs control based on the correction command based on the detected value of the clamping force detector 55. The supply current to the coil 48 is corrected.

That is, the adder 605 calculates the clamping force error based on the clamping force command value and the clamping force detection value sequentially input from the self-locking force detector 55, and outputs it to the integrator 603. The integrator 603 calculates a correction value for the current supplied to the electromagnet 49 in order to eliminate the clamping force error by integrating the clamping force error from the start of the mold clamping, and outputs a correction command indicating the correction value to the adder 606. .

The adder 606 corrects the current value indicated by the current command input from the current pattern generator 602 based on the current value indicated by the correction command input from the integrator 603, and outputs a current value indicating the corrected value to the amplifier 604. Signal (correct current command). The amplifier 604 supplies the coil 48 of the electromagnet 49 with a current corresponding to the correction current command input from the adder 606.

The electromagnet 49 is driven by supplying a current to the coil 48, and the suction portion 51 is sucked by the suction force of the electromagnet 49. As the mold clamping force is transmitted to the movable platen 12 via the suction plate 22 and the rod 39, the mold clamping is performed.

In the mode locking, the clamping force is controlled as follows by the control of the current pattern by the control unit 60a and the control based on the correction command based on the detected value of the clamping force detector 55.

Fig. 7 is a view for explaining control of the clamping force by the control unit of the first embodiment. In the seventh embodiment, the same portions as those in the sixth embodiment are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

In (A) of Fig. 7, a curve L3 indicates the transition of the current value (current value of the correction current command) of the current actually supplied from the amplifier 604 to the coil 48 in accordance with the self-correcting current command. Further, in (B) of Fig. 7, the curve L4 indicates the result of supplying the current indicated by the curve L3 to the coil 48, and the detected clamping force.

As shown by the curve L3, the control unit 60a supplies the maximum current for a predetermined period (t1 to t3) from the start of the mold clamping. This is the result of the control of the rising current command according to the current pattern L1. By supplying the maximum current for a short period of time from the start of mold clamping, the rise responsiveness of the electromagnet 49 is increased, and the clamping force is rapidly increased (portion indicated by the symbol a in the curve L4).

Further, in the first embodiment, the integrator 603 of the control unit 60a starts integrating the mold clamping force error from the start of mold clamping. In other words, in the first embodiment, the control according to the correction command is started from the start of the mold clamping, and the correction command is based on the detection value of the clamping force detector 55 based on the clamping force of the rising current command.

As shown by the curve L3, the control unit 60a supplies the maximum current during a period (t1 to t3) longer than the period (t1 to t2) specified by the current pattern L1. The reason is that, at the time t2, the clamping force does not reach the target clamping force, and the integrator 603 integrates the clamping force error by the control of the correction command based on the detection value of the clamping force detector 55. The current command according to the current pattern L1 is corrected based on the correction command from the integrator 603. Therefore, when the maximum current is supplied until the target clamping force is obtained, and the target clamping force is obtained, the control unit 60a lowers the supply current to the rated current based on the holding current command of the current pattern L1. However, the responsiveness of the electromagnet 49 is not only rising, but also in the opposite direction (downward), so after the supply current starts to decrease (after t3), as indicated by the symbol b of the curve L4, the lock The mold force has also continued to increase. The clamping force error generated by the result is also controlled based on the correction command based on the detected value of the clamping force detector 55, and the integrator 603 integrates the clamping force error and outputs a correction command. As a result, at the adder 606, the sustain current command from the current pattern generator 602 is corrected in accordance with the correction command, and as indicated by the symbol c of the curve L3, the coil 48 is supplied with a current lower than the current value of the rated current. The clamping force begins to decrease behind the supply current and approaches the target clamping force.

Then, for example, as shown in FIG. 6(B), when the target clamping force is not obtained at the rated current, the integrator 603 outputs the correction command by integrating the clamping force error e. By correcting the sustain current command in accordance with the correction command, as indicated by the symbol d of the curve L3, the coil 48 is supplied with a current larger than the rated current. As a result, at t4 in Fig. 7, the target clamping force is reached and becomes a steady state. After becoming the steady state, also in the mode-locking, the clamping force detection value detected by the lock-mode force detector 55 is sequentially input to the adder 605 by the correction command based on the detected value based on the clamping force detector 55. The current supplied to the coil 48 is adjusted by the control. As a result, the mold clamping is performed with a stable clamping force.

During this period, the resin melted in the injection device 17 is ejected from the injection nozzle 18, and is filled in each cavity space of the mold device 19. Further, as the load detector, a load cell disposed on the rod 39, a sensor for detecting the amount of elongation of the tie rod 14, and the like can be used.

Then, when the resin in each cavity space is cooled and solidified, the control unit 60a stops supplying current to the coil 48 in the state of FIG. 3 when the mold is opened. As the linear motor 28 is driven, the movable platen 12 is retracted. As shown in Fig. 4, the movable mold 16 is positioned at the retreat limit position and the mold is opened.

As described above, according to the mode locking device having the control unit 60a according to the first embodiment, the current pattern generator 602 generates a current pattern in consideration of the characteristics of the electromagnet, and controls the clamping force based on the current pattern. Therefore, the rising responsiveness of the clamping force can be improved, and the forming cycle can be shortened. Further, since the clamping force is controlled by the correction command based on the detected value of the mold clamping force detector 55 by the integrator 603, the adder 605, the adder 606, and the like, the target clamping force can be appropriately maintained.

Next, a second embodiment will be described. As shown in the seventh (B) diagram, the control unit 60a of the first embodiment generates a phenomenon in which the clamping force exceeds the target clamping force during t3 to t4 (that is, the mold clamping force is excessive). From the viewpoint of protecting the mold and preventing molding failure, the over-clamping force is not good. Therefore, in the second embodiment, an example of solving this problem will be described.

Fig. 8 is a view showing a configuration example of a control unit according to the second embodiment. In the eighth embodiment, the same portions as those in the fifth embodiment are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. In the second embodiment, the control unit 60 is described by the control unit 60b.

The control unit 60b further includes a switching monitor 607 as a constituent element in addition to the constituent elements of the control unit 60a. The switching monitor 607 switches ON/OFF of the integrator 603, that is, the switching monitor 607 is based on the clamping force command value input from the upper-order controller 601 and the clamping force detection value input from the self-locking force detector 55. The integrator 603 is operated at an appropriate timing and stopped at an appropriate timing. The integrator 603 action means a control action based on a correction command based on the detected value of the clamping force detector 55. Further, the stop of the integrator 603 means that the control is stopped according to the correction command based on the detected value of the clamping force detector 55.

Hereinafter, the control of the clamping force by the integrator 60b having the switching monitor 607 will be described. Fig. 9 is a view for explaining control of the clamping force by the control unit of the second embodiment. In the ninth embodiment, the same portions as those in the seventh embodiment are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

In the second embodiment, the switching monitor 607 stops the integrator 603 by outputting a stop command to the integrator 603 in advance when the mold clamping is first started. Therefore, in Fig. 9, during the period from t1 to t5, the integration of the clamping force error by the integrator 603 is not performed, and the current of the adder 606 based on the rising current command from the current pattern generator 602 is not performed. Correction of the command value. As a result, as shown in (A) of Fig. 9, the current indicated by the current pattern L1 is supplied to the coil 48 during the period from t1 to t5. Further, in the graph (A), although the trajectory of the curve L3 coincides with the current pattern L1 during the period from t1 to t5, the visibility indicating the broken line of the current pattern L1 is considered, and the solid line indicating the curve L3 is not described.

Here, the reason why the mold clamping force starts to stabilize and the operation of the integrator 603 is stopped is that the integral of the mold clamping force error at the time of starting the mold clamping can be cited as the reason why the mold clamping force is excessively generated in the first embodiment. one. That is, in Fig. 7(B), in order to correct the clamping force error integrated during the period from t1 to t2, the period during which the maximum current is supplied is extended, and as a result, the clamping force reaches t3 after the target clamping force is reached. The reason for crossing. Therefore, in the second embodiment, after the mold clamping is started, the monitor 607 is switched to stop the integrator 603 during the period (t1 to t5) in which the clamping force is unstable.

When the clamping force starts to become stable according to the maintenance current command (t5), the switching monitor 607 outputs an operation command to the integrator 603. Further, the switching monitor 607 detects the stability of the clamping force by monitoring the change in the clamping force detection value input from the self-locking force detector 55 in response to time. For example, if the change in the clamping force detection value is within a predetermined value within a predetermined time, the switching monitor 607 determines that the clamping force becomes stable.

The integrator 603 starts the action (ie, the integral of the clamping force error) in response to the action command. In the example of Fig. 9(B), the detection value of the clamping force according to the sustain current command at t5 at the start of integration is lower than the target clamping force. Therefore, the integrator 603 outputs a correction command for correcting the clamping force error to the adder 606. The adder 606 corrects the current command value according to the sustain current command from the current pattern generator 602 based on the correction command value. As a result, as shown by the curve L3, the supply current becomes a value exceeding the rated current. As the supply current increases, the clamping force increases, and in the 9th (B) diagram, the target clamping force is reached at t6. Further, in the second embodiment, since the integration of the clamping force error is started after the clamping force is stabilized by the holding current command, the current command value is not rapidly corrected, and the clamping force is reduced. Sex. Therefore, when the target clamping force is reached at t6, it becomes a steady state. Even if it becomes steady state, the switching monitor 607 also causes the integrator 603 to operate during mode-locking (during the period in which the target clamping force should be maintained). Therefore, the current supplied to the coil 48 is adjusted by the control of the correction command based on the detected value of the clamping force detector 55 based on the clamping force detection value input by the clamping force detector 55. As a result, the mold clamping is performed with a stable clamping force.

Further, although omitted in FIG. 9, the clamping force command for reducing the clamping force is input from the upper-order controller in the clamping step (ie, the clamping force indicating that the clamping force is lower than the current clamping force) At the time of the command, the switching monitor 607 outputs a stop command to the integrator 603 to stop the integrator 603. Therefore, in this case, the current of the current pattern generated by the current pattern generator 602 in response to the clamping force command is directly supplied to the coil 48. As a result, the clamping force begins to decrease and becomes stable near the clamping force indicated by the clamping force command. When the clamping force starts to stabilize, the switching monitor 607 causes the integrator 603 to operate. In this way, by not integrating the clamping force error during the rapid decrease of the clamping force, the clamping force is prevented from being excessively lowered.

Further, the mold clamping step ends, and when the clamping force indicated by the clamping force command from the upper controller 601 becomes 0, the switching monitor 607 stops the integrator 603. Therefore, although the current value of the current command outputted from the current pattern generator 602 is prevented from being zero, the clamping force is increased by the control of the correction command based on the detected value of the mold clamping force detector 55. That is, when the integrator 603 is still operating, the correction command is output from the integrator 603 by integrating the clamping force error, and the current of the current value indicated by the correction command is supplied to the coil 48. Further, since a loop is formed which supplies a current to the coil 48, and the mold clamping force error becomes larger, a correction command having a large absolute value is output from the integrator 603 in order to correct the mold clamping force error. According to the correction command, the current supply of the current value having a large absolute value is thus circulated to the coil 48. In addition, since the magnitude of the force is proportional to the square of the current value, even if the current value of the correction command is a negative value, it does not act in a direction to lower the clamping force.

As described above, according to the control unit 60b of the second embodiment, the switching monitor 607 stops the detection value based on the clamping force detector 55 during the period in which the clamping force is unstable (in the case of rising or falling). Control of the correction instructions. Therefore, the possibility that the clamping force is excessively generated can be reduced. As a result, compared with the first embodiment, the arrival time to the target clamping force can be shortened, and the molding cycle can be shortened.

Further, in the present embodiment, since the mold clamping force detecting unit preferably uses the mold clamping force detector 55 for detecting the load applied to the mold, an example in which the mold clamping force detector 55 is used is shown. However, the mold clamping force detecting unit is also used. A magnetic flux density detector that detects the magnetic flux density of the electromagnet may be used, and a distance detector that measures the gap δ between the back plate 13 and the suction plate 22 may be used.

Further, in the method of controlling the mold clamping device of the present embodiment, the mold clamping device that performs the opening and closing operation by the driving of the linear motor 28 may not be used. Especially in the case of the linear motor 28, since the magnet is exposed on the surface of the frame, there is a possibility that dust or the like adheres. Therefore, Fig. 10 shows a modification of the present invention in which the rotary mold motor in which the opening and closing mold drive unit does not use the linear motor 28 and the motor frame is opened by the motor frame.

Since the description of the electromagnet unit as the second driving unit is the same as that of the first and second figures, the description thereof will be omitted. The opening/closing mold motor 74, which is a first drive unit and a drive unit (opening and closing mold drive unit) for opening and closing the mold, is attached to the motor mount 73 fixed to the frame so as not to be movable. Here, the opening/closing mold motor 74 is applied to a rotary motor in which a motor frame is sealed by a motor frame. A motor shaft (not shown) protrudes from the rotary motor, and the motor shaft and the ball screw shaft 72 are coupled. The ball screw shaft 72 and the ball screw nut 71 are screwed together to form a motion direction changing device that converts the rotational motion generated by the rotary motor into a linear motion. Further, the ball screw nut 71 is rotatably disposed on the movable platen flange portion 12a that protrudes from the lower portion of the movable platen 12. Therefore, the movable mold plate 12 can be moved back and forth by the opening and closing mold motor 74, and the movable mold 16 can be opened and closed.

Further, the position detector 75 is attached to the rear end of the opening and closing mold motor 74, and after reading the rotation angle of the opening and closing mold motor 74, the position of the movable platen 12 can be grasped. Therefore, the opening and closing mold processing unit 61 controls the opening and closing mold motor 74.

In the present configuration, in the case where the clamping force is generated by the electromagnet on the mold device 19, more specifically, when the possibility of the positional deviation of the mold disappears after the start of the boosting, the opening and closing mold processing portion 61 variably controls the opening and closing. The mold motor 74 supplies current. Specifically, the supply current is stopped. Therefore, the influence of the position control of the opening and closing mold motor 74 on the clamping force does not exist.

The present invention is not limited to the specific embodiment, and various modifications and changes can be made without departing from the spirit and scope of the invention.

The present patent application is based on the priority of Japanese Patent Application No. 2007-221573, filed on A.

10. . . Clamping device

11. . . Fixed platen

12. . . Movable platen

12a. . . Movable platen flange

13. . . Backstage board

14. . . Tie

15. . . Fixed mold

16. . . Movable mold

17. . . Injection device

18. . . Injection nozzle

19. . . Mold unit

twenty one. . . Guide column

twenty two. . . Suction plate

twenty three. . . Guide hole

twenty four. . . Large diameter department

25. . . Small diameter department

28. . . Linear motor

29. . . stator

31. . . Movable

37. . . Electromagnet unit

39. . . Rod

41, 42. . . hole

43. . . Screw

44. . . Nut

45. . . Coil arrangement (groove)

46. . . core

47. . . yoke

48. . . Coil

49. . . Electromagnet

51. . . Suction department

55. . . Clamping force detector

71. . . Ball screw nut

72. . . Ball screw shaft

73. . . Motor bearing

74. . . Open and close mold motor

75. . . Position detector

601. . . Upper controller

602. . . Current pattern generator

603. . . Integrator

604. . . Amplifier

605, 606. . . Adder

607. . . Switch monitor

Br1. . . Bearing member

Gd. . . Guide

Fr. . . frame

N1, n2. . . Nut

Fig. 1 is a view showing a configuration example of a conventional control unit.

Fig. 2 is a view for explaining the clamping force obtained by the conventional feedback control.

Fig. 3 is a view showing a state in which the mold apparatus and the mold clamping apparatus according to the embodiment of the present invention are closed.

Fig. 4 is a view showing a state at the time of mold opening of the mold device and the mold clamping device according to the embodiment of the present invention.

Fig. 5 is a view showing an example of the structure of a control unit according to the first embodiment.

6(A) to 6(B) are diagrams for explaining a current pattern generated by a current pattern generator.

7(A) to 7(B) are diagrams for explaining control of the clamping force by the control unit of the first embodiment.

Fig. 8 is a view showing a configuration example of a control unit according to the second embodiment.

Figs. 9(A) to 9(B) are views for explaining control of the clamping force by the control unit of the second embodiment.

Fig. 10 is a view showing a modification of the present invention to which a rotary motor in which a magnetic field generation region is blocked by a motor frame is applied.

10. . . Clamping device

11. . . Fixed platen

12. . . Movable platen

13. . . Backstage board

14. . . Tie

15. . . Fixed mold

16. . . Movable mold

17. . . Injection device

18. . . Injection nozzle

19. . . Mold unit

twenty one. . . Guide column

twenty two. . . Suction plate

twenty three. . . Guide hole

twenty four. . . Large diameter department

25. . . Small diameter department

28. . . Linear motor

29. . . stator

31. . . Movable

33. . . Magnetic pole tooth

34. . . core

35. . . Coil

37. . . Electromagnet unit

39. . . Rod

41. . . hole

42. . . hole

43. . . Screw

44. . . Nut

45. . . groove

46. . . core

48. . . Coil

49. . . Electromagnet

51. . . Suction department

60. . . Control department

Br1. . . Bearing member

Fr. . . frame

Gd. . . Guide

N1, n2. . . Nut

δ. . . gap

Claims (13)

A clamping device for generating a clamping force by an electromagnet, comprising: a first current command generating portion for generating a current command to the electromagnet according to a target clamping force; and a clamping force detecting portion for detecting The second current command generating unit generates a correction command for correcting the current command based on the detected value of the clamping force detected by the clamping force detecting unit; and the switching unit is configured according to the clamping force of the electromagnet; The detection value of the clamping force is switched to the operation and the stop of the second current command generating unit. The mode locking device according to claim 1, wherein the correction current command calculation unit is configured to generate the current command generated by the first current command generation unit and the correction command generated by the second current command generation unit. The correction current command supplied to the electromagnet is calculated. The mode locking device of claim 1, wherein the first current command generating portion generates a current command having a rising current command for generating the clamping force and maintaining the generated clamping force Current command. The mold clamping device of claim 3, wherein the second current command generating portion is based on a clamping force maintained by the holding current command and a detected value of the clamping force detected by the clamping force detecting portion. The correction command is generated by an error. The mode locking device of claim 1, wherein the first current command generating unit generates a current command when starting the mode locking, which indicates the comparison The current value at which the current of the target clamping force is large. The mode locking device of claim 1, wherein the second current command generating unit generates the correction command based on an error between the target clamping force and the detected value of the clamping force. The mode locking device according to claim 1, wherein the switching unit switches the operation of the second current command generating unit when the current is controlled by the current command in the current command generated by the first current command generating unit. And stop. The mold clamping device according to claim 1, wherein the switching portion operates the second current command generating portion while maintaining the target clamping force. A mode locking device according to claim 1, wherein the switching unit stops the second current command generating unit for a predetermined period of time after the start of mode locking. The mold clamping device according to claim 1, wherein the switching portion stops the second current command generating portion for a predetermined period of time when the target clamping force is changed. The mold clamping device according to claim 1, wherein the switching portion stops the second current command generating portion when the target clamping force is zero. A mode locking control method for generating a clamping force by using an electromagnet, characterized in that: generating a current command to the electromagnet according to a target clamping force; detecting a clamping force by the electromagnet; and switching the action of the correction command and Stop, according to the clamping force Correct the current command by detecting the value. The mode locking control method according to claim 12, wherein the correction current command supplied to the electromagnet is calculated based on the current command and the correction command.