JP4732226B2 - Mold clamping apparatus and mold clamping force control method - Google Patents

Description

  The present invention relates to a mold clamping device and a mold clamping force control method, and more specifically to a mold clamping device that generates a mold clamping force with an electromagnet and a method for controlling the mold clamping force.

  2. Description of the Related Art Conventionally, a molding machine, for example, an injection molding machine, includes an injection device, a mold device, and a mold clamping device. By injecting resin from an injection nozzle of the injection device, filling the cavity space of the mold device, and solidifying the resin. A molded product is obtained. The mold apparatus includes a fixed mold and a movable mold, and operates the mold clamping apparatus to move the movable mold forward and backward with respect to the fixed mold, thereby closing the mold, clamping and opening the mold. It can be carried out.

  The mold clamping device includes a fixed platen to which the fixed mold is attached, a movable platen to which the movable mold is attached, an electric motor, a ball screw shaft connected to an output shaft of the motor, and the ball screw. A ball screw composed of a ball nut screwed to a shaft, a cross head connected to the ball nut, a toggle mechanism disposed between the cross head and a movable platen, and the like, by driving the motor The mold can be closed and clamped by advancing the crosshead and extending the toggle mechanism.

  However, in the mold clamping apparatus having the above-described configuration, a toggle mechanism is used to generate a mold clamping force. Therefore, a bending moment acts on the movable platen, and the mold mounting surface of the movable platen is distorted. Will occur.

  Moreover, since the mold clamping is performed by extending the toggle mechanism, it becomes difficult to control the mold clamping force.

  Therefore, there is provided a mold clamping device that includes an electric motor and an electromagnet, and uses the torque of the motor for mold closing and mold opening operations, and uses the attraction force of the electromagnet for mold clamping operations (for example, Patent Document 1). reference).

  In the mold clamping device, a rear platen is disposed at a predetermined interval from the fixed platen, and a movable platen is disposed so as to be movable back and forth along a tie bar provided between the fixed platen and the rear platen. An electromagnet is fixed to the rear end surface of the rear platen, and an adsorption plate is disposed behind the rear platen so as to be movable back and forth. A link mechanism is disposed between the adsorption plate and the movable platen. It can be bent and stretched by a motor.

Therefore, after closing the mold by driving the motor and extending the link mechanism, the current is supplied to the coil constituting the electromagnet to drive the electromagnet, and the magnetic force according to the magnitude of the current is applied. Clamping can be performed by generating and adsorbing the adsorption plate. In this case, an electromagnet is used to generate the mold clamping force, so that the bending moment does not act on the movable platen, and the mold mounting surface is not distorted. Can be controlled.
Japanese Patent No. 3190600

  However, when changing the clamping force, such as at the start of clamping, even if a current is supplied to the coil constituting the electromagnet, an eddy current in the direction to cancel the magnetic field is generated, and the current is supplied, but the desired current is supplied. A state in which a magnetic field cannot be obtained may occur.

  FIG. 1 shows a graph for explaining such a state. The vertical axis of the graph shown in FIG. 1A shows the magnitude of the current supplied to the electromagnet coil, the horizontal axis shows the time for supplying the current to the electromagnet coil, and the graph shown in FIG. The vertical axis represents the magnitude of the attractive force generated in the electromagnet, and the horizontal axis represents the time for supplying current to the coil of the electromagnet.

Referring to FIG. 1, is started clamping at time t _0, be supplied with the rated current I _R is the current required to operate the electromagnet, by the generation of the eddy current, for performing mold clamping the can not be obtained immediately suction force a _R required to adsorb the suction plate to the electromagnet, the first time the suction force a _R turned passed about a few seconds t ₁ generated.

  As described above, even when a current is supplied to the coil constituting the electromagnet in order to change the mold clamping force at the start of mold clamping, it takes a certain time to generate a desired mold clamping force. This is not a steady process in the mold clamping process and is unique to the rise characteristics when the mold clamping force is changed. Not desirable. In particular, when the molding cycle is short, it is necessary to improve the productivity of the molded product by reducing the generation time of the mold clamping force as much as possible.

  Therefore, the present invention has been made in view of the above points, and is a mold clamping device that generates a mold clamping force with an electromagnet, and shortens the time until a desired mold clamping force is generated. It is an object of the present invention to provide the mold clamping device and the mold clamping force control method capable of improving the rising characteristics in the mold clamping process.

According to one aspect of the present invention, the mold closing operation is performed by the mold opening and closing drive unit, the suction force current from the current supply section with respect to the mold clamping driving unit having an electromagnet and the suction portion is supplied to the electromagnet a mold clamping device mold clamping operation is performed by generating a, a control unit for controlling the mold opening and closing unit and the current supply section, wherein, prior to changing the clamping force, wherein the current supply unit to supply a current to the electromagnet to generate the suction force, the mold clamping apparatus, wherein said to generate thrust to offset the suction force to the mold opening and closing drive unit is provided.

  The control unit causes the current supply unit to supply the current to the electromagnet to generate the adsorption force until the mold feed of the movable mold is completed, and cancels the adsorption force to the mold opening / closing drive unit. The thrust may be generated. The control unit may cut off the generation of the thrust by the mold opening / closing drive unit when changing the mold clamping force, and let the current supply unit supply a rated current to the electromagnet. Also good.

  Furthermore, the responsiveness of the mold opening / closing drive unit may be faster than the responsiveness of the electromagnet. The mold opening / closing drive unit may include a linear motor or a motor, and a ball screw that is rotated by the motor and can be advanced and retracted.

According to another aspect of the present invention, there is provided a mold clamping device in which a mold opening / closing operation is performed by a mold opening / closing drive unit , and a mold clamping operation is performed by a mold clamping drive unit having an electromagnet and an attracting unit. A control unit for controlling the opening / closing drive unit, the electromagnet includes a permanent magnet, and the control unit generates a magnetic flux of the electromagnet to generate an attractive force before changing the mold clamping force, A mold clamping device is provided in which a thrust that cancels the adsorption force is generated in an opening / closing drive unit.

According to yet another aspect of the present invention, there is provided a magnet and method for controlling a mold clamping force generated with the suction unit in the clamping device, before causing changes the mold clamping force, the current to the electromagnet A mold clamping force control method is provided, wherein the mold clamping force control method is characterized in that a suction force is generated by supplying and a thrust for canceling the suction force is generated in a mold opening / closing drive unit that performs a mold opening / closing operation.

  The thrust for supplying the current to the electromagnet to generate the attracting force and canceling the attracting force to the mold opening / closing drive for performing the mold opening / closing operation until the mold feed of the movable mold is completed. May be generated. Further, when the mold clamping force is changed, generation of the thrust may be cut off, or a rated current may be supplied to the electromagnet.

  According to the present invention, it is a mold clamping device that generates a mold clamping force with an electromagnet, and can shorten the time until a desired mold clamping force is generated, thereby improving the rising characteristics in the mold clamping process. The mold clamping device and the mold clamping force control method can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  In the following, 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 when performing the injection In the following description, the moving direction of the screw is assumed to be the front, and the moving direction of the screw when measuring is assumed to be the rear.

  FIG. 2 is a schematic configuration diagram of a mold apparatus and a mold clamping apparatus according to the embodiment of the present invention.

  In FIG. 2, 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 and guides the mold clamping device 10. These are two guides as one guide member. In the figure, only one of the two guides Gd is shown.

  Reference numeral 11 denotes a fixed platen as a first fixing member that is placed on the guide Gd and fixed to the frame Fr and the guide Gd. A rear platen 13 as a second fixing member is disposed at a predetermined interval from the fixed platen 11 and facing the fixed platen 11. Between the fixed platen 11 and the rear platen 13, four tie bars 14 (only two of the four tie bars are shown in the figure) are installed as 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.

  A movable platen 12 as a first movable member is disposed along the tie bar 14 so as to be capable of moving forward and backward in the mold opening / closing direction (moving in the left-right direction in the drawing). 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 of the movable platen 12.

  A first screw portion (not shown) is formed at a front end portion (right end portion in the figure) 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. Fixed to. In addition, a guide post 21 as a second guide member having a smaller outer diameter than the tie bar 14 is provided at a predetermined portion on the rear side (left side in the figure) of each tie bar 14, and the rear end face (left end face in the figure). ) Projecting rearward and 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 of each guide post 21. The fixed platen 11 and the rear platen 13 screw the second screw portion and the nut n2. Are linked by 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. A resin (not shown) is filled in each cavity space.

  A mold apparatus 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 that penetrate the guide posts 21 at locations corresponding to the guide posts 21.

  The guide hole 23 is opened at the front end surface (right end surface in the drawing), is opened at the rear end surface of the large diameter portion 24 that accommodates the ball nut n2 and the suction plate 22, and is slid with the guide post 21. A small-diameter portion 25 having a sliding surface 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.

  Incidentally, in order to move the movable platen 12 back and forth, a linear motor 28 as a first drive unit and as a mold opening / closing drive unit is disposed between the movable platen 12 and the frame Fr. The linear motor 28 includes a stator 29 as a first drive element formed on the frame Fr in parallel with the guide Gd and corresponding to the moving range of the movable platen 12, and the movable platen 12. A movable element 31 as a second driving element is provided at the lower end of the second element so as to face the stator 29 and to be formed over a predetermined range.

  The mover 31 includes a core 34 projecting toward the stator 29 and having a plurality of magnetic pole teeth 33 formed at a predetermined pitch, and a coil 35 wound around each magnetic pole tooth 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 so as to extend on the core. The permanent magnet alternates between the magnetic poles of N pole and S pole, and the magnetic poles. It is formed by magnetizing at the same pitch as the teeth 33.

  Accordingly, when the linear motor 28 is driven by supplying a predetermined current to the coil 35, the movable element 31 moves forward and backward, and accordingly, the movable platen 12 moves forward and backward, and mold closing and mold opening can be performed. .

  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.

  By the way, when the movable platen 12 is moved forward (moved in the right direction in the figure) and the movable mold 16 comes into contact with the fixed mold 15, the mold closing is completed, and then the mold clamping is performed. In order to perform mold clamping, an electromagnet unit 37 as a second drive unit and as a mold clamping drive unit is disposed between the rear platen 13 and the suction plate 22.

  In order to transmit the mold clamping force generated by the electromagnet unit 37 to the movable platen 12 at the time of mold clamping, the suction plate 22 is moved back and forth in conjunction with the advance and retreat of the movable platen 12 at the time of mold closing and mold opening. 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 mold clamping device 10 is constituted 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 disposed on the rear platen 13 side, and an attracting portion 51 as a second driving member disposed on the suction plate 22 side.

  The attracting portion is formed at a predetermined portion of the front end surface of the attracting plate 22, in the present embodiment, the portion surrounding the rod 39 in the attracting plate 22 and facing the electromagnet 49. Further, in the present embodiment, a predetermined portion of the rear end surface of the rear platen 13, slightly above and below the rod 39, extends in the horizontal direction, and two grooves 45 are formed in parallel to each other. A core 46 having a rectangular shape between 45 and a yoke 47 is formed in other portions. An exciting coil 48 is wound around the core 46.

  Therefore, in the electromagnet unit 37, when a current is supplied to the exciting coil 48 provided in the groove 45, the electromagnet 49 is driven to attract the attracting portion 51 and generate the mold clamping force.

  Referring to FIG. 2 again, the rod 39 is connected to the suction plate 22 at the rear end (left end in the drawing) and connected to the movable platen 12 at the front end. Accordingly, the rod 39 is advanced as the movable platen 12 advances when the mold is closed, and advances the suction plate 22, and when the mold is opened, the movable platen 12 moves backward (moves leftward in the figure). Then, the suction plate 22 is moved backward.

  Therefore, a hole 41 for passing the rod 39 and a hole 42 for penetrating the rod 39 are formed in the central portion of the rear platen 13, and an opening at the front end of the hole 41. A bearing member Br1 such as a bush for slidably supporting the rod 39 is disposed. Further, a screw 43 is formed at the rear end portion of the rod 39, and the screw 43 and a nut 44 rotatably supported with respect to the suction plate 22 are screwed together.

  The mold clamping device 10 is connected to the control unit 4 and the drivers 5 and 5 '. More specifically, the exciting coil 48 of the electromagnet 49 and the coil 35 of the linear motor 28 are connected to the drivers 5 and 5 ′ as the respective current supply units. The control unit 4 controls the operations of the drivers 5 and 5 ′ and controls the current supplied to the exciting coil 48 of the electromagnet 49 and the coil 35 of the linear motor 28.

  Under this structure, in this embodiment, before changing the clamping force, such as before starting the clamping process, current is supplied to the exciting coil 48 of the electromagnet 49 to generate an attracting force. The motor 28 generates a force that cancels the adsorption force. This will be described with reference to FIG. 3 in addition to FIG.

  Here, FIG. 3 is a graph for explaining the basic concept of the present invention. More specifically, FIG. 3A is a graph showing the force generated by the electromagnet 49 before and after changing the mold clamping force, the force generated by the linear motor 28, and the change in mold clamping force according to the present invention. The vertical axis indicates the magnitude of each force, and the horizontal axis indicates time. FIG. 3B is a graph for comparison with the present invention, and is a graph showing a change in force generated by the electromagnet before and after changing the mold clamping force of the conventional technique, and the vertical axis is The magnitude of the attractive force generated in the electromagnet, and the horizontal axis indicates the time for supplying current to the coil of the electromagnet.

Referring to FIGS. 3A and 3B, at time t ₀ , for example, to start the mold clamping operation, to change the magnitude of the mold clamping force in multiple stages, or after the mold clamping process, A command to change the clamping force is issued from the control unit 4 to the driver 5 in order to change the clamping force, such as to apply a clamping force and a negative force to cut the magnetic field and perform mold opening. It is done.

Conventionally, as shown in FIG. 3B, current is supplied to the coil of the electromagnet at the time t ₀ , but the suction plate is used as an electromagnet for clamping the mold due to the generation of the eddy current. suction force a _R required to adsorb can not be obtained immediately, the first time the suction force a _R becomes time t ₁ is generated.

In contrast, in the present invention, as shown in FIG. 3 (a), supplies current to the exciting coil 48 of the electromagnet 49 before the time t _0, is generating suction force F _1. Further, before the time t ₀ , the linear motor 28 generates a force −F ₁ that cancels the adsorption force F ₁ . Accordingly, the suction force F ₁ is to be offset by the force -F ₁ generated by the linear motor 28, the clamping force is not generated before the time t _0. At time t ₀ , the supply of current to the coil 35 of the linear motor 28 is cut off, and the target mold clamping force on the exciting coil 48 of the electromagnet 49, that is, the target mold clamping force (steady state) When a steady current (“rated current”) necessary for generating (clamping force) is supplied, the attractive force F ₁ by the electromagnet 49 increases rapidly, the mold clamping force increases rapidly, and the time t ₁ it is possible to obtain the suction force a _R needed to make the mold clamping at the point of which the time t _0.5 is faster than. In FIG. 3 (a), the solid line indicating the clamping force and the dotted line indicating the force generated by the electromagnet 49 are shown so as not to overlap in consideration of the visibility of the figure. From the point of time t ₀ , both are substantially the same, resulting in overlapping curves.

Due to the characteristic of the electromagnet that the attractive force of the electromagnet is proportional to the square of the magnetic flux, the change (rise) of the attractive force with respect to the change (rise) of the magnetic flux is very small at a low magnetic field. On the other hand, if the magnetic field is high,
With respect to the change (rise) of the magnetic flux, the attractive force changes (rises) greatly. That is, for example, the change in the attractive force when the magnetic flux is increased from 0.5 Tesla to 1 Tesla is larger than the change in the attractive force when the magnetic flux is increased from 0 Tesla to 1 Tesla.

Therefore, in the present invention, by supplying a current to the exciting coil 48 of the electromagnet 49 before the time t _0, to generate a suction force F _1, further, in order not to cause the mold clamping force is earlier than time t ₀ A linear motor 28 generates a force −F ₁ that cancels the adsorption force F ₁ .

At time t ₀ , the supply of current to the coil 35 of the linear motor 28 is cut off, and a rated current necessary for generating a steady mold clamping force is supplied to the excitation coil 48 of the electromagnet 49. Then, already attracting force of the electromagnet 49 which generates a suction force F ₁ is more rapidly increased. That is alleviated rate of change of magnetic flux density, it is possible to suppress the influence of eddy currents, it is possible to obtain the suction force A _R required for performing mold clamping, very short time rise clamping force Can be made.

  Based on the basic concept described above, a specific method for generating the attractive force of the electromagnet 49 will be described with reference to FIG. 4 in addition to FIG.

  Here, FIG. 4 is a graph for explaining a specific method for generating the attractive force of the electromagnet in the present invention. More specifically, FIG. 4A is a graph showing the change over time of the moving speed of the movable mold 16 provided in the movable platen 12, and FIG. 4B is a graph showing the excitation coil 48 of the electromagnet 49. FIG. 4C is a graph showing the time change of the attracting force generated by the electromagnet 49, and FIG. 4D is the time of the thrust of the linear motor 28. FIG. It is a graph which shows a change.

  FIG. 4 shows a process from the mold closing process to the start of the mold clamping process.

Steps from time T ₀ until T ₄ in FIG. 4, i.e., from the movable die 16 is separated from the fixed mold 15, and the parting face of the movable mold 16 is parting face of the stationary mold 15 The process in which the movable mold 16 is brought close to the fixed mold 15 in the state until contact is referred to as a mold closing process. Also, the steps from the time T ₄ in FIG. 4 until T _5, i.e., the step of filling by injecting a molten resin from the injection nozzle are omitted injection apparatus shown into a cavity of the mold apparatus of the injection process. Further, since the process after time T ₅ in FIG. 4, that is, the parting surface of the movable mold 16 is in contact with the parting surface of the fixed mold 15, further force acts on the movable mold 16. The process in which the fixed mold 15 is pressed by the movable mold 16 is referred to as a mold clamping process.

When the mold closing process is started at time T ₀ , current is supplied to the coil 35 of the linear motor 28 to generate a thrust L ₀ , and the movable mold 16 approaches the fixed mold 15 while being accelerated at a constant rate. To do. Further, the current I ₀ is supplied to the exciting coil 48 of the electromagnet 49, but no attracting force is immediately generated in the electromagnet 49. The current I ₀ continues to be supplied to the exciting coil 48 of the electromagnet 49 until time T ₅ is reached.

When the time becomes T _1, the moving speed of the movable mold 16 which has been accelerated reaches V _1. At the same time, the supply of current to the coil 35 of the linear motor 28 is cut off, the thrust of the linear motor 28 is generated is zero, the moving speed of the movable mold 16 is a constant velocity remains of the velocity V _1. Even at this time, no attracting force is generated in the electromagnet 49.

At time T ₂ , a thrust −L _{0 in the} direction opposite to the thrust L ₀ of the linear motor 28 generated during the time T ₀ to T ₁ is generated, and the moving speed of the movable mold 16 toward the fixed mold 15 is increased. begins to decelerate at a constant rate from the speed V _1.

At time T ₃ , an attractive force that has not been generated in the electromagnet 49 starts to be generated. Here, normally, the linear motor 28 is driven by position control. However, when an attracting force starts to be generated, an external force that further moves forward acts on the linear motor 28. Therefore, an attempt linear motor 28 to maintain the position, further in the same direction as the thrust -L _0, begins to occur a large thrust linear motor 28 than the thrust -L _0.

When the time becomes T _4, the moving speed of the movable mold 16 which has been decelerated time T ₂ later it becomes zero. That is, the mold feeding of the movable mold 16 is completed, and the mold closing process is completed. Then, the molten resin is injected from the injection nozzle of the injection apparatus and filled into the cavity space of the mold apparatus (injection process).

When the time becomes T _4, the suction force generated by the electromagnet 49 becomes the suction force A _4. The suction force _{A 4} corresponds to the adsorption force _{F 1} in FIG. Meanwhile, thrust was increased in the same direction as the thrust -L ₀ is a thrust -L ₄ when it is time _{T 4.} This thrust -L ₄ corresponds to the force -F ₁ generated by the linear motor 28 in FIG. In other words, the linear motor 28 generates a thrust −L ₄ that cancels the adsorption force A ₄ . This state continues until time _{T 5.}

When the time becomes T _5, wherein the injection step is completed, the mold clamping step is started. The time _{T 5} corresponds to a time _{t 0} in FIG. 3. The exciting coil 48 of the electromagnet 49, a large current I _R is supplied than the current I ₀ which has been supplied to it.

Current I _R is the target to become the mold clamping force constant current needed to generate the (constant clamping force) (rated current). On the other hand, the current supply to the coil 35 of the linear motor 28 is cut off and becomes zero. Then, the suction force by the electromagnet 49 is rapidly increased, as described with reference to FIG. 3, it is possible to obtain a suction force A _R required for performing mold clamping, constant type than prior art in a short time A tightening force can be generated.

Thus, in this example, before the mold clamping force is changed, such as before the mold clamping process is started (in this example, until the mold feed of the movable mold 16 is completed), the exciting coil 48 of the electromagnet 49 is applied. while generating a predetermined suction force a ₄ by supplying a current smaller than the rated current I _R, the linear motor 28 controls the thrust generated by controlling the current supply to the coil 35 of the linear motor 28, the It is generating thrust -L ₄ to cancel the suction force _{a 4.} When changing the mold clamping force, the supply of current to the coil 35 of the linear motor 28 is cut off. Since the response of the linear motor 28 is faster than the response of the electromagnet 49, the thrust generated by the linear motor 28 can be controlled efficiently.

Then, already attracting force of the electromagnet 49 which generates a suction force A ₄ further rises sharply. That is alleviated rate of change of magnetic flux density, it is possible to suppress the influence of eddy currents, it is possible to obtain the suction force A _R required for performing mold clamping. Therefore, a mold clamping force having the same value as the steady mold clamping force can be generated in a short time, and eddy current loss can be compensated. Therefore, it is possible to improve the rising characteristics of the clamping process using an electromagnet, and to improve the productivity of the molded product.

In the above-described example, the linear motor 28 is used as a mold opening / closing drive unit for moving the movable platen 12 including the movable mold 16 back and forth. However, the present invention is not limited to this example. As long as it is possible to generate a thrust -L ₄ (-F ₁ ) that cancels a predetermined attraction force A ₄ (F ₁ ) generated by the exciting coil 48 of the electromagnet 49, for example, the motor and the motor can rotate and advance and retreat. A combination of various ball screws may be used. Also in this case, the same effect as the effect of the embodiment of the present invention described above can be obtained.

In the above example, such as before starting the mold clamping process, a predetermined suction force A ₄ by supplying a current smaller than the rated current I _R to the exciting coil 48 of the electromagnet 49 before changing the clamping force Although generated beforehand, the present invention is not limited to such an example. For example, the electromagnet 49 may include a permanent magnet, and a predetermined attracting force A ₄ (F ₁ ) may be generated in advance based on the magnetic flux by the permanent magnet. Also in this case, the same effect as the effect of the embodiment of the present invention described above can be obtained.

Furthermore, when a reverse force is applied to the linear motor 28, it is necessary to pass a current in advance. However, when a permanent magnet is used, a predetermined A ₄ (F ₁ ) is applied by the force of the permanent magnet. Since it can be generated, the current can be made zero (0) while the attracting force is not generated. As a result, power consumption can be reduced.

  Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment, and various modifications and changes are within the scope of the gist of the present invention described in the claims. It can be changed.

It is a graph for demonstrating the problem resulting from generation | occurrence | production of an eddy current. It is a schematic block diagram of the metal mold apparatus and the mold clamping apparatus in embodiment of this invention. It is a graph for demonstrating the basic concept of this invention. It is a graph for demonstrating the specific method for generating the attractive_force | adsorptive_power of an electromagnet in this invention.

Explanation of symbols

4 Control unit 5, 5 ′ Driver 10 Clamping device 12 Movable platen 15 Fixed mold 16 Movable mold 28 Linear motor 35 Linear motor coil 37 Electromagnet unit 48 Excitation coil 49 Electromagnet

Claims (12)

Mold opening and closing operation by the mold opening and closing drive unit is carried out, the mold clamping operation by generating a suction force current is supplied from the current supply section to the electromagnet against the mold clamping driving unit having an electromagnet and suction unit A mold clamping device,
A control unit for controlling the mold opening / closing drive unit and the current supply unit;
Wherein, prior to changing the clamping force, the electromagnet is supplied with current to generate the suction force, to generate a thrust force that cancels the suction force to the mold opening and closing drive unit in the current supply unit A mold clamping device characterized by that. The mold clamping device according to claim 1,
The control unit causes the current supply unit to supply the current to the electromagnet to generate the adsorption force until the mold feed of the movable mold is completed, and cancels the adsorption force to the mold opening / closing drive unit. A mold clamping device that generates the thrust. The mold clamping device according to claim 1 or 2,
The said control part interrupts | blocks generation | occurrence | production of the said thrust by the said mold opening / closing drive part, when changing the said mold clamping force, The mold clamping apparatus characterized by the above-mentioned. The mold clamping device according to claim 3, wherein
The control unit causes the current supply unit to supply a rated current to the electromagnet when changing the mold clamping force. The mold clamping device according to any one of claims 1 to 4,
The mold clamping device according to claim 1, wherein the responsiveness of the mold opening / closing drive unit is faster than the responsiveness of the electromagnet. The mold clamping device according to any one of claims 1 to 5,
The mold clamping apparatus, wherein the mold opening / closing drive unit is a linear motor. The mold clamping device according to any one of claims 1 to 5,
The mold opening / closing drive unit includes a motor and a ball screw that is rotated by the motor and can be advanced and retracted. A mold clamping device in which a mold opening / closing operation is performed by a mold opening / closing drive unit , and a mold clamping operation is performed by a mold clamping drive unit having an electromagnet and an adsorption part ,
A control unit for controlling the mold opening and closing drive unit;
The electromagnet includes a permanent magnet,
Before the mold clamping force is changed, the control unit generates a magnetic flux of the electromagnet to generate an attracting force, and the mold opening / closing drive unit generates a thrust to cancel the attracting force. Fastening device. A method of controlling a mold clamping force generated using an electromagnet and an attracting portion in a mold clamping device ,
Before causing changes the mold clamping force, by supplying current to the electromagnet to generate a suction force, further characterized by generating a thrust to offset the suction force to the mold opening and closing drive unit for performing mold opening and closing operation Mold clamping force control method. The mold clamping force control method according to claim 9,
The thrust for supplying the current to the electromagnet to generate the attracting force and canceling the attracting force to the mold opening / closing drive for performing the mold opening / closing operation until the mold feed of the movable mold is completed. A mold clamping force control method characterized by generating The mold clamping device according to claim 9 or 10,
A mold clamping force control method, wherein when the mold clamping force is changed, the generation of the thrust is cut off. The mold clamping device according to claim 11, wherein
A mold clamping force control method, wherein when the mold clamping force is changed, a rated current is supplied to the electromagnet.

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