JP5694106B2 - Injection molding machine - Google Patents

Description

  The present invention relates to an injection molding machine including an electromagnet that drives a mold clamping operation.

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

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

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

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

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

WO05 / 090052 pamphlet

  By the way, in the case of using a mold clamping device that uses the attractive force of an electromagnet as described in Patent Document 1, there is a problem of response delay due to generation of eddy current, iron loss, heat generation due thereto, and the like.

  Accordingly, an object of the present invention is to provide an injection molding machine capable of appropriately blocking the flow path of eddy currents and improving the responsiveness.

In order to achieve the above object, according to one aspect of the present invention, a first fixing member to which a fixed mold is attached;
A second fixing member disposed opposite to the first fixing member;
A first movable member to which a movable mold is attached;
A second movable member connected to the first movable member and moving together with the first movable member,
The second fixed member and the second movable member constitute a mold clamping force generation mechanism that generates a mold clamping force by an attractive force of an electromagnet,
At least one member of the second fixed member and the second movable member is configured by combining two or more divided bodies ,
An injection molding machine is provided that includes a reinforcing member that reinforces the joint between the divided bodies, and a cooling mechanism is provided on the reinforcing member .

  ADVANTAGE OF THE INVENTION According to this invention, the injection molding machine which can interrupt | block the flow path of an eddy current appropriately and can improve responsiveness is obtained.

It is a figure which shows the state at the time of the mold closing of the mold clamping apparatus in the injection molding machine of embodiment of this invention. It is a figure which shows the state at the time of the mold opening of the mold clamping apparatus in the injection molding machine of embodiment of this invention. It is a perspective view which shows the single article state of the rear platen 13 provided with the division structure by one Example (Example 1). It is explanatory drawing of the symmetry plane of a magnetic field. It is explanatory drawing of the eddy current flow-path cutting | disconnection effect | action of the rear platen 13 provided with a division structure. It is a figure which shows an example of the coupling | bonding aspect between division body 13A, 13B. It is a figure which shows an example of the reinforcement member 90 provided in the coupling | bond part between division body 13A, 13B. It is a perspective view which shows the single article state of the rear platen 13 provided with the division structure by Example 2. FIG.

  The best mode for carrying out the present invention will be described below with reference to the drawings. In the present embodiment, for the mold clamping device, the moving direction of the movable platen when closing the mold is the front, the moving direction of the movable platen when opening the mold is the rear, and the injection device is the injection The description will be made assuming that the moving direction of the screw when performing the measurement is the front and the moving direction of the screw when performing the measurement is the rear.

  FIG. 1 is a diagram showing a state when a mold clamping device is closed in an injection molding machine according to an embodiment of the present invention, and FIG. 2 is a state when the mold clamping device is opened in the injection molding machine according to the embodiment of the present invention. FIG. In FIGS. 1 and 2, the hatched members show the main cross section.

  In the figure, 10 is a mold clamping device, Fr is a frame (frame) of an injection molding machine, Gd is a guide movable with respect to the frame Fr, 11 is a guide not shown or fixed on the frame Fr. A rear platen 13 is arranged at a predetermined distance from the fixed platen 11 and opposed to the fixed platen 11, and four tie bars 14 (in the figure) are disposed between the fixed platen 11 and the rear platen 13. Shows only two of the four tie bars 14). The rear platen 13 is fixed with respect to the frame Fr.

  A screw portion (not shown) is formed at the front end portion (right end portion in the figure) of the tie bar 14, and the front end portion of the tie bar 14 is fixed to the fixed platen 11 by screwing and tightening the nut n1 to the screw portion. Is done. The rear end of the tie bar 14 is fixed to the rear platen 13.

  A movable platen 12 is disposed along the tie bar 14 so as to face the fixed platen 11 so as to be movable back and forth in the mold opening / closing direction. For this purpose, the movable platen 12 is fixed to the guide Gd, and a guide hole or notch (not shown) for penetrating the tie bar 14 is formed at a position corresponding to the tie bar 14 in the movable platen 12. A suction plate 22 described later is also fixed to the guide Gd.

  A fixed mold 15 is fixed to the fixed platen 11 and a movable mold 16 is fixed to the movable platen 12. The fixed mold 15 and the movable mold 16 are brought into contact with and separated from each other as the movable platen 12 advances and retreats. Then, mold closing, mold clamping and mold opening are performed. As the mold clamping is performed, a cavity space (not shown) is formed between the fixed mold 15 and the movable mold 16, and resin (not shown) injected from the injection nozzle 18 of the injection device 17 is formed in the cavity space. Charged to A mold device 19 is configured by the fixed mold 15 and the movable mold 16.

  The suction plate 22 is fixed to the guide Gd in parallel with the movable platen 12. As a result, the suction plate 22 can move forward and backward behind the rear platen 13. The suction plate 22 may be formed of a magnetic material. For example, the suction plate 22 may be configured by an electromagnetic laminated steel plate formed by laminating thin plates made of a ferromagnetic material. Alternatively, the suction plate 22 may be formed by casting.

  The linear motor 28 is provided on the guide Gd in order to advance and retract the movable platen 12. The linear motor 28 includes a stator 29 and a mover 31, and the stator 29 is formed on the frame Fr in parallel with the guide Gd and corresponding to the moving range of the movable platen 12. Is formed at a lower end of the movable platen 12 so as to face the stator 29 and over a predetermined range.

  The mover 31 includes a core 34 and a coil 35. The core 34 includes a plurality of magnetic pole teeth 33 that are protruded toward the stator 29 and formed at a predetermined pitch, and the coil 35 is wound around 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 to extend on the core. The permanent magnet is formed by alternately magnetizing the N and S poles. When the linear motor 28 is driven by supplying a predetermined current to the coil 35, the movable element 31 is advanced and retracted, and accordingly, the movable platen 12 is advanced and retracted by the guide Gd to perform mold closing and mold opening. it can.

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

  The movable platen 12 and the suction plate 22 are not limited to be fixed to the guide Gd, and a movable element 31 of the linear motor 28 may be provided on the movable platen 12 or the suction plate 22. Further, the mold opening / closing mechanism is not limited to the linear motor 28, and may be a hydraulic type or an electric type.

  When the movable platen 12 is moved forward and the movable mold 16 abuts against the fixed mold 15, the mold is closed and subsequently the mold is clamped. An electromagnet unit 37 for clamping the mold is disposed between the rear platen 13 and the suction plate 22. A center rod 39 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 center rod 39 advances and retracts the attracting plate 22 in conjunction with the advance and retreat of the movable platen 12 when the mold is closed and opened, and transmits the attracting force generated by the electromagnet unit 37 to the movable platen 12 when the mold is clamped. To do.

  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 center rod 39, and the like constitute the mold clamping device 10.

  The electromagnet unit 37 includes an electromagnet 49 formed on the rear platen 13 side and a suction portion 51 formed on the suction plate 22 side. Further, a predetermined portion of the rear end surface of the rear platen 13, in this embodiment, a groove 45 is formed around the center rod 39, a core 46 is formed inside the groove 45, and a yoke 47 is formed outside the groove 45. Is done. A coil 48 is wound around the core 46 in the groove 45. In addition, the core 46 and the yoke 47 may be configured by an integral casting structure.

  In the present embodiment, the electromagnet 49 may be formed separately from the rear platen 13, and the adsorption portion 51 may be formed separately from the adsorption plate 22, or the electromagnet may be adsorbed as a part of the rear platen 13 and adsorbed as a part of the adsorption plate 22. A part may be formed. Further, the arrangement of the electromagnet and the attracting part may be reversed. For example, the electromagnet 49 may be provided on the suction plate 22 side, and the suction portion may be provided on the rear platen 13 side.

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

  The center rod 39 is connected to the suction plate 22 at the rear end and is connected to the movable platen 12 at the front end. Therefore, the center rod 39 is advanced together with the movable platen 12 when the mold is closed to advance the suction plate 22, and is retracted together with the movable platen 12 when the mold is opened to retract the suction plate 22. For this purpose, a hole 41 for penetrating the center rod 39 is formed in the central portion of the rear platen 13, and a bearing such as a bush that slidably supports the center rod 39 facing the opening at the front end of the hole 41. A member Br1 is provided.

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

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

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

  Subsequently, the mold clamping processing unit 62 of the control unit 60 controls the mold clamping process. The mold clamping unit 62 supplies current to the coil 48 and attracts the attracting unit 51 by the attracting force of the electromagnet 49. Along with this, the clamping force is transmitted to the movable platen 12 through the suction plate 22 and the center rod 39, and clamping is performed. When changing the clamping force such as at the start of clamping, the clamping unit 62 generates a target clamping force to be obtained by the change, that is, a target clamping force in a steady state. Control is performed so that the necessary steady-state current value is supplied to the coil 48.

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

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

  Here, a characteristic configuration of the present invention will be described with reference to FIG.

  FIG. 3 is a perspective view showing a single product state of the rear platen 13 having a divided structure according to one embodiment (first embodiment). In FIG. 3, arrows h and V indicate the left and right direction (horizontal direction) and the vertical direction (vertical direction) of the rear platen 13, respectively. However, these directions change depending on the installation state (orientation) of the injection molding machine, and are merely convenient. An arrow f indicates the front of the rear platen 13. FIG. 4 is an explanatory diagram of the plane of symmetry of the magnetic field, and is a diagram schematically showing the rear platen 13 and the suction plate 22 in a sectional view.

  In the present embodiment, the rear platen 13 is configured by coupling two divided bodies 13A and 13B divided by the magnetic field symmetry plane X1. At this time, the divided bodies 13A and 13B are coupled in a manner that is electrically insulated from each other. For example, the divided bodies 13A and 13B may be coupled to be separated from each other via an insulating member. In this case, an air layer (insulating layer) is formed between the divided bodies 13A and 13B, and insulation is ensured. Alternatively, an insulating material may be coated (for example, laminated) on the coupling surfaces of the divided bodies 13A and 13B.

  Here, the magnetic field symmetry plane X1 is a symmetry plane of the magnetic field (see the magnetic force lines P schematically shown in FIG. 4) formed on the rear platen 13 and the suction plate 22 when the electromagnet 49 is driven. In this example, the magnetic field symmetry plane X1 is a plane parallel to the horizontal direction h of the rear platen 13 through the center of the vertical direction V of the rear platen 13, as shown in FIG.

  FIG. 5 is an explanatory diagram of the eddy current flow path cutting action of the rear platen 13 having a split structure. FIG. 5 (A) shows a comparative example without splitting, and FIG. 5 (B) shows the present embodiment. FIG. 6 is a plan view of the rear platen 13 on which the coil 48 is disposed as viewed in the mold clamping direction from the suction plate 22 side.

When the rear platen 13 is not divided, as shown by an arrow I in FIG. 5A, an eddy current flows around the hole for the center rod in the central portion (core) of the rear platen. Such an eddy current causes problems such as deteriorating the responsiveness (responsiveness of mold clamping force) when the electromagnet 49 is driven as described above. On the other hand, according to the present embodiment, the rear platen 13 is configured by connecting two divided bodies 13A and 13B divided by the magnetic field symmetry plane X1, and therefore, the arrow I _{1 in} FIG. 5B. , I ₂ , the path of the eddy current around the hole 41 for the center rod is cut at the dividing plane (that is, the magnetic field symmetry plane X1). In this way, by appropriately changing the flow path of the eddy current, the responsiveness when driving the electromagnet 49 can be enhanced. Further, since the split surface of the rear platen 13 (that is, the connecting surface between the two split bodies 13A and 13B) is the magnetic field symmetry plane X1, there is no magnetic gap, and the influence on the output when the electromagnet 49 is driven by splitting. Can be minimized.

  FIG. 6 is a diagram illustrating an example of a coupling mode between the divided bodies 13A and 13B. In FIG. 6, for the sake of convenience, one half of the rear platen 13 is shown in the ½ model, but the same may be applied to the other half.

  As shown in FIG. 6, the divided bodies 13 </ b> A and 13 </ b> B may be coupled by fitting the concave portion 132 and the convex portion 131 through the insulating members 136 and 138. Specifically, the divided body 13A has a convex portion 131 on the coupling surface with the divided body 13B, and correspondingly, the divided body 13B has a concave portion 132 on the coupling surface with the divided body 13A. . The convex 131 is covered with an insulating member 136, and an insulating member 138 is provided in the concave 132. In addition, the height of the convex part 131 may be set larger than the depth of the concave part 132. Thereby, the coupling surfaces of the divided bodies 13A and 13B may be separated by a predetermined distance after the coupling.

FIG. 7 is a diagram illustrating an example of the reinforcing member 90 provided at the joint between the divided bodies 13A and 13B. In FIG. 7 , for the sake of convenience, one half of the rear platen 13 is shown in the 1/2 model, but the same may be applied to the other half.

  As shown in FIG. 7, a reinforcing member 90 may be provided at the joint between the divided bodies 13 </ b> A and 13 </ b> B. This reinforcing member 90 fulfills the function of compensating for strength reduction due to division. Thereby, the strength required for the rear platen 13 can be maintained while improving the responsiveness by the division. In the example shown in FIG. 7, the reinforcing member 90 is made of a plate material such as a metal plate that is electrically insulated from the rear platen 13. However, the reinforcing member 90 may be formed of a plastic or the like (reinforced plastic) as long as the strength is maintained. The reinforcing member 90 may be coupled to the divided bodies 13A and 13B by bolts, welding, or the like. In this case, the reinforcing member 90 also functions to couple the divided bodies 13A and 13B.

  The reinforcing member 90 may include a cooling mechanism. The cooling mechanism may be, for example, a pipe through which cooling water flows or a cooling plate in which a cooling water passage is formed. In the latter case, the reinforcing member 90 itself may be formed of a cooling plate.

  FIG. 8 is a perspective view showing a single product state of a rear platen 13 ′ having a divided structure according to the second embodiment.

The rear platen 13 ′ according to the second embodiment is different in the dividing direction from the rear platen 13 according to the first embodiment. Specifically, the rear platen 13 ′ is configured by joining two divided bodies 13A ′ and 13B ′ divided by the magnetic field parallel plane X2. At this time, the divided bodies 13A ′ and 13B ′ are coupled in such a manner that they are electrically insulated from each other. For example, the divided bodies 13A ′ and 13B ′ may be coupled to be separated from each other via an insulating member. In this case, an air layer (insulating layer) is formed between the divided bodies 13 A ′ and 13 B ′, and insulation is ensured. Alternatively, an insulating material may be coated (for example, laminated) on the coupling surfaces of the divided bodies 13A ′ and 13B ′. Further, the divided bodies 13A ′ and 13B ′ may be coupled in the coupling mode as described with reference to FIG. 6, or may be provided with the reinforcing member 90 as described with reference to FIG. .

  The magnetic field parallel plane X2 is a parallel plane of the magnetic field (see the magnetic force lines P schematically shown in FIG. 4) formed on the rear platen 13 ′ and the suction plate 22 when the electromagnet 49 is driven. Therefore, the magnetic field parallel plane X2 corresponds to a plane parallel to the cross section shown in FIG.

  Even with such a divided structure, the eddy current path (see FIG. 5A) around the hole 41 for the center rod is divided into divided surfaces (that is, magnetic field parallel surfaces X2), as in the divided structure according to the first embodiment. ) And cut. In this way, by appropriately changing the flow path of the eddy current, the responsiveness when driving the electromagnet 49 can be enhanced. Further, since the split surface of the rear platen 13 ′ (that is, the joint surface between the two split bodies 13A ′ and 13B ′) is the magnetic field parallel plane X2, there is no magnetic gap, and the output when driving the electromagnet 49 by splitting is performed. Can be minimized.

  In the second embodiment, the rear platen 13 ′ is divided into two parts, but the number of divisions is arbitrary. That is, the rear platen 13 ′ may be divided into three or more parallel to the magnetic field parallel plane X2. In the second embodiment, the two divided bodies 13A ′ and 13B ′ are divided at substantially the center (the center in the left-right direction h) of the rear platen 13 ′, but the rear platen 13 ′ is an arbitrary one in the left-right direction h. It may be divided at the points.

  The divided structure according to the second embodiment can be combined with the divided structure according to the first embodiment described above. That is, the rear platen 13 ′ may be further divided by the magnetic field symmetry plane X1.

  In the embodiment described above, the “first fixed member” in the claims corresponds to the fixed platen 11, and the “first movable member” in the claims corresponds to the movable platen 12. . The “second fixing member” in the claims corresponds to the rear platens 13 and 13 ′, and the “second movable member” in the claims corresponds to the suction plate 22.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, as described above, the electromagnet 49 may be provided on the suction plate 22 side, and the suction portion may be provided on the rear platens 13 and 13 ′ side. In this way, when the electromagnet 49 is provided on the suction plate 22 side, a similar divided structure may be realized for the suction plate 22 formed by casting.

  Further, even when the electromagnet 49 is formed on the rear platens 13 and 13 ′, the suction plate 22 may be formed by casting to realize a similar divided structure with respect to the suction plate 22. Thereby, since the flow path of the eddy current is similarly changed also on the suction plate 22 side, it is possible to contribute to improving the responsiveness when the electromagnet 49 is driven. In this case, the suction plate 22 is preferably divided so that the division positions of the rear platens 13 and 13 ′ are the same. That is, the suction plate 22 is preferably divided by the same dividing surface of the rear platens 13 and 13 ′.

  In the above-described embodiments, water is used as a cooling fluid, but fluids other than water (for example, oil or gas) may be used.

  In the above-described embodiment, the rear platen 13 is formed with the one-pole electromagnet 49. However, the rear platen 13 may be provided with an electromagnet so that a plurality of poles are formed (that is, multipolarization is possible). May be realized).

  In the above description, the mold clamping device 10 having a specific configuration is illustrated, but the mold clamping device 10 may have any configuration as long as the mold clamping is performed using an electromagnet.

Br1 bearing member Fr frame Gd guide 10 mold clamping device 11 fixed platen 12 movable platen 13, 13 'rear platen 13A, 13B, 13A', 13B 'divided body 14 tie bar 15 fixed mold 16 movable mold 17 injection device 18 injection nozzle 19 Mold device 22 Adsorption plate 28 Linear motor 29 Stator 31 Movable element 33 Magnetic pole teeth 34 Core 35 Coil 37 Electromagnet unit 39 Center rod 41 Hole 45 Groove 46 Core 47 Yoke 48 Coil 49 Electromagnet 51 Adsorption part 55 Load detector 60 Control part 61 mold opening / closing process part 62 mold clamping process part 131 convex part 132 concave part 136 insulating material 138 insulating member 90 reinforcing member X1 magnetic field symmetry plane X2 magnetic field parallel plane

Claims (5)

A first fixing member to which a fixed mold is attached;
A second fixing member disposed opposite to the first fixing member;
A first movable member to which a movable mold is attached;
A second movable member connected to the first movable member and moving together with the first movable member,
The second fixed member and the second movable member constitute a mold clamping force generation mechanism that generates a mold clamping force by an attractive force of an electromagnet,
At least one member of the second fixed member and the second movable member is configured by combining two or more divided bodies ,
An injection molding machine comprising a reinforcing member that reinforces a joint between the divided bodies, and a cooling mechanism is provided on the reinforcing member .   The injection molding machine according to claim 1, wherein the divided bodies are joined in a manner that is insulated from each other.   The injection molding machine according to claim 1 or 2, wherein the divided bodies are coupled to each other while being separated from each other.   The injection molding machine according to any one of claims 1 to 3, wherein the divided bodies are coupled by a magnetic field symmetry plane or a parallel plane in a member on which a coil forming the electromagnet is disposed. . The second fixed member and the second movable member are both configured by combining two or more divided bodies, and a coupling surface of the divided bodies constituting the second fixed member; and the second The injection molding machine according to any one of claims 1 to 4 , wherein the joining surfaces of the divided bodies constituting the movable member are the same.

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