JP5749127B2 - 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 type mold clamping device having the 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. Unfortunately, the 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 a configuration using a mold clamping device using the attractive force of an electromagnet as described in Patent Document 1, the movable member constituting the mold clamping force generation mechanism by the electromagnet is used to prevent its falling. It must be supported in contact with the center rod. However, in such a configuration, magnetic leakage from the movable member to the center rod becomes a problem.

  Therefore, the present invention aims to provide an injection molding machine capable of preventing magnetic leakage from the member attracted by the electromagnet to the center rod while preventing the member attracted by the electromagnet from falling. To do.

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 and through which a center rod penetrates;
A first movable member to which a movable mold is attached;
A first movable member and a second movable member that is connected by the center rod and moves 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,
Said second movable member has a through hole in which the center rod is passed, the peripheral wall of the through hole, seen including a contact portion in contact with the center rod, and a non-contact portion away from said center rod ,
The contact part and the non-contact part are formed such that a peripheral wall of the through hole in the second movable member has a stepped shape, and an injection molding machine is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the injection molding machine which can prevent the magnetic leakage from the member by the side attracted to an electromagnet to a center rod can be obtained, preventing the member by the side attracted by an electromagnet from falling.

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. 4 is a cross-sectional view showing the relationship between the suction plate 22 and the center rod 39. 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. As shown in the figure, the guide Gd may be provided separately for each of the suction plate 22 and the movable platen 12, or may be configured by a single unit common to the suction plate 22 and the movable platen 12. .

  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. The core 46 and the yoke 47 are formed of an integral casting structure, but may be formed by laminating thin plates made of a ferromagnetic material to form an electromagnetic laminated steel plate.

  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 through which the center rod 39 passes is formed in the central portion of the rear platen 13.

  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 (strain) detected by the load detector 55 is sent to the control unit 60. The controller 60 detects the mold clamping force based on the output of the load detector 55. 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 cross-sectional view showing the relationship between the suction plate 22 and the center rod 39, and corresponds to the details of the Y portion in FIG.

  In the example shown in FIG. 3, the nut pressing member 44 b of the mold thickness adjusting mechanism 44 is fastened behind the suction plate 22. The nut pressing member 44 b holds a nut 44 a that meshes with a screw 39 a formed on the peripheral surface of the center rod 39. The mold thickness adjusting mechanism 44 is a mechanism that adjusts the relative position of the movable platen 12 and the suction plate 22 (that is, the distance between them) in accordance with the thickness of the mold apparatus 19. For example, the mold thickness adjusting mechanism 44 varies the position of the center rod 39 with respect to the suction plate 22 by rotating a gear 44c coupled to the nut 44a by a mold thickness adjusting motor (not shown). Thereby, the position of the center rod 39 with respect to the suction plate 22 is adjusted, and the position of the movable platen 12 with respect to the fixed platen 11 is adjusted. That is, the mold thickness is adjusted by changing the relative positions of the movable platen 12 and the suction plate 22.

  The suction plate 22 has a through hole 90 through which the center rod 39 passes. As shown in FIG. 3, the peripheral wall of the through hole 90 includes a contact portion 22 a that contacts the center rod 39 and a non-contact portion 22 b that is separated from the center rod 39. The contact portion 22a and the non-contact portion 22b may be formed so that the peripheral wall of the through hole 90 has a stepped shape. That is, the non-contact portion 22 b may be configured by a step (concave portion) formed on the peripheral wall of the through hole 90. Further, the non-contact part 22 b may be formed by cutting out the peripheral wall of the through hole 90. That is, the non-contact part 22b may be formed by a notch that enlarges the diameter of the through hole 90.

  The contact portion 22a may be provided over the entire circumference in the circumferential direction of the center rod 39, or may be provided discretely. Similarly, the non-contact part 22b may be provided over the entire circumference in the circumferential direction of the center rod 39, or may be provided discretely. Moreover, the position in the axial direction of the center rod 39 of the contact part 22a and the non-contact part 22b is arbitrary. In the illustrated example, the contact portion 22a is provided on the rear platen 13 side, and the non-contact portion 22b is provided on the mold thickness adjusting mechanism 44 side, but the reverse may be possible. That is, the non-contact part 22b may be provided on the rear platen 13 side, and the contact part 22a may be provided on the mold thickness adjusting mechanism 44 side. Further, a plurality of contact portions 22 a may be provided in the circumferential direction of the center rod 39, and similarly, a plurality of non-contact portions 22 b may be provided in the circumferential direction of the center rod 39.

  Thus, according to the present embodiment, the suction plate 22 is supported by being in contact with the center rod 39 at the contact portion 22a. Therefore, the suction plate 22 can be prevented from falling down. On the other hand, the suction plate 22 is supported in contact with the center rod 39 only by the contact portion 22a, and is separated from the center rod 39 by the non-contact portion 22b. That is, in the suction plate 22, the entire peripheral wall of the through hole 90 does not contact the center rod 39, but only the portion of the peripheral wall of the through hole 90 where the contact portion 22 a is formed contacts the center rod 39. Thereby, the contact area between the adsorption | suction board 22 and the center rod 39 can be reduced, and the magnetic leakage from the adsorption | suction board 22 which may arise at the time of the action | operation of the electromagnet unit 37 to the center rod 39 can be reduced.

  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 platen 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, in the above description, the mold clamping device 10 having a specific configuration is illustrated, but the mold clamping device 10 may be any configuration that performs mold clamping using an electromagnet. Furthermore, the mold clamping device 10 may be other than a mold clamping device using an electromagnet, and may be, for example, a toggle type configuration.

Fr frame Gd guide 10 mold clamping device 11 fixed platen 12 movable platen 13 rear platen 14 tie bar 15 fixed mold 16 movable mold 17 injection device 18 injection nozzle 19 mold device 22 suction plate 22a contact portion 22b non-contact portion 28 linear motor 29 Stator 31 Movable element 33 Magnetic pole teeth 34 Core 35 Coil 37 Electromagnet unit 39 Center rod 41 Hole 44 Mold thickness adjusting mechanism 45 Groove 46 Core 47 Yoke 48 Coil 49 Electromagnet 51 Adsorption part 55 Load detector 60 Control part 61 Type opening / closing processing part 62 Clamping processing part 90 Through hole

Claims (3)

A first fixing member to which a fixed mold is attached;
A second fixing member disposed opposite to the first fixing member and through which a center rod penetrates;
A first movable member to which a movable mold is attached;
A first movable member and a second movable member that is connected by the center rod and moves 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,
The second movable member has a through hole through which the center rod passes, and a peripheral wall of the through hole includes a contact portion that contacts the center rod, and a non-contact portion that is separated from the center rod,
The contact portion and the non-contact portion, the peripheral wall of the through-holes in the second movable member is formed to have a stepped form, the molding machine out morphism. A first fixing member to which a fixed mold is attached;
A second fixing member disposed opposite to the first fixing member and through which a center rod penetrates;
A first movable member to which a movable mold is attached;
A first movable member and a second movable member that is connected by the center rod and moves 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,
The second movable member has a through hole through which the center rod passes, and a peripheral wall of the through hole includes a contact portion that contacts the center rod, and a non-contact portion that is separated from the center rod,
The non-contact portion is formed by cutting the peripheral wall of the through hole in the second movable member, the molding machine out morphism. The injection according to any one of claims 1 to 2 , further comprising a mold thickness adjusting mechanism that adjusts a relative position between the center rod and the second movable member in an axial direction of the center rod. Molding machine.

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