JP3190600B2 - Mold clamping device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold clamping device.

[0002]

2. Description of the Related Art Conventionally, in an injection molding machine, a resin is injected from an injection nozzle of an injection device, filled into a cavity space between a fixed die and a movable die, and solidified to form a molded product. Is to be obtained. Then, a mold clamping device is provided for moving the movable mold with respect to the fixed mold to close, close, and open the mold.

[0003] The mold clamping apparatus includes a hydraulic mold clamping apparatus driven by supplying oil to a hydraulic cylinder and an electric mold clamping apparatus driven by an electric motor. BACKGROUND ART Fastening devices are widely used because they have high controllability, do not stain surroundings, and have high energy efficiency. In this case, a thrust is generated by rotating a ball screw by driving an electric motor, and the thrust is expanded by a toggle mechanism to generate a large mold clamping force.

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

[0005]

However, in the above-mentioned conventional mold clamping device, the load resistance of the ball screw is low, not only a large mold clamping force cannot be generated, but also a torque ripple generated in the electric motor. The mold clamping force fluctuates. In addition, in order to generate a mold clamping force, it is necessary to constantly supply a current to the motor, and the power consumption and heat generation of the motor increase, so the rated output of the motor needs to be increased accordingly. The cost of the device increases.

Therefore, a mold clamping device using a linear motor for the mold opening and closing operation and utilizing the attraction force of an electromagnet for the mold clamping operation is considered. However, the linear motor generally has a higher force density (thrust per unit area) than a servomotor.
Not only is low, but also the energy efficiency is low, so it is necessary to use a large linear motor, and the mold clamping device becomes large.

Further, when a mold clamping force is applied to the movable iron core of the linear motor, it becomes difficult to maintain a gap related to the attraction force of the electromagnet, and the electromagnet and the fixed coil come into contact with each other. Lower. Furthermore, since the suction plate has a long stroke, the suction plate may be inclined.If the suction plate is inclined and sucked by the electromagnet, the gap between the electromagnet and the suction plate is closed when the mold closing is completed. A small portion and a large portion are formed. And since the attraction force is inversely proportional to the square of the distance between the electromagnet and the attraction plate, the attraction force is increased in the portion where the gap is small, and the attraction force is decreased in the portion where the gap is large, The suction plate is further inclined.

As a result, the electromagnet and the attraction plate come into contact with each other, and the electromagnet itself receives a part of the attraction force, so that the electromagnet cannot be used as a mold clamping force and the mold clamping force is reduced. . The present invention solves the problems of the conventional mold clamping device, can change and control the mold clamping force during molding, can stably generate a large mold clamping force, and reduce the cost. It is an object to provide a mold clamping device that can be lowered.

[0009]

For this purpose, in the mold clamping apparatus of the present invention, a fixed platen, a fixed die attached to the fixed platen, and a predetermined distance from the fixed platen are arranged. A rear platen, a movable platen disposed to be able to advance and retreat along a tie bar provided between the fixed platen and the rear platen, a movable mold attached to the movable platen, an electromagnet and an attraction plate, An electromagnet and an attraction plate unit in which one of an electromagnet and an attraction plate is fixed to the rear surface of the rear platen, and the other member is movably disposed, and is axially movable with respect to the rear platen by a bearing. A pressurizing piston supported at one end and fixed to the movable platen and the other end connected to the other member via a link mechanism; It is in the back connection to the link mechanism, and a motor which can be driven in forward and reverse.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a front view showing a first state of the mold clamping device according to the embodiment of the present invention, and FIG. 2 is a second view of the mold clamping device according to the embodiment of the present invention.
FIG. 3 is a plan view showing a second state of the mold clamping device according to the embodiment of the present invention.

In the drawing, reference numeral 11 denotes a fixed platen;
A rear platen 13 is arranged at a predetermined distance from the fixed platen 11, and four tie bars 14 (only two are shown in the figure) are installed between the fixed platen 11 and the rear platen 13. . And the tie bar 14
The movable platen 1 faces the fixed platen 11 along
2 are provided so as to be able to advance and retreat (move in the horizontal direction in the figure) freely.

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 moved as the movable platen 12 advances and retreats. Are brought into and out of contact with each other. In addition,
When the fixed mold 15 and the movable mold 16 are brought into contact with each other, a cavity space (not shown) is formed between the fixed mold 15 and the movable mold 16, and resin injected from an injection nozzle (not shown) is formed in the cavity space. Is filled.

An electromagnet 18 as one member is embedded in the rear surface (left surface in the figure) of the rear platen 13,
The electromagnet 18 includes an electromagnetic laminated steel sheet 19 and a coil 21 for generating a magnetomotive force. An attraction plate 22 as the other member is movably disposed so as to face the electromagnet 18. The suction plate 22 includes an electromagnetic laminated steel plate 52 and an adsorption plate frame 23 that supports the electromagnetic laminated steel plate 52. In this case, the electromagnet 18 and the attraction plate 22 constitute an electromagnet / attraction plate unit.

In the present embodiment, the rear platen 1
The electromagnet 18 is fixed to the back of the rear plate 3 and the suction plate 22 is movably disposed.
2 can be fixed and the electromagnet 18 can be disposed movably. On the back of the rear platen 13, four guide posts 71 (only two guide posts are shown).
Are arranged so as to project rearward (to the left in the figure), and the suction plate 22 is guided by the guide post 71. The guide post 71 includes a rod portion 72 that is longer than the thickness of the suction plate 22 by the air gap amount δ, and a head portion 73 formed at the tip of the rod portion 72. The guide post 7 is provided on the suction plate frame 23.
A guide hole 74 is formed to allow the through hole 1 to pass therethrough. The guide hole 74 includes a large-diameter portion 75 opened to the rear platen 13 side and a small-diameter portion 76 opened to the back side of the suction plate 22, and a guide bush 77 is fitted into the small-diameter portion 76. The guide bush 77 and the rod 7
2 is slidable. Since the diameter of the head portion 73 is larger than the diameter of the small diameter portion 76, the movement of the suction plate 22 is restricted by the head portion 73. A cylindrical gap (gap) is formed between the large diameter portion 75 and the rod portion 72, and a coil spring 78 is disposed in the gap. The coil spring 78 separates the suction plate 22 from the rear platen 13. Energize in the direction to release. Therefore, usually, the optimum air gap amount δ is maintained between the rear platen 13 and the suction plate 22. In this case, when the air gap amount δ is small, the electromagnet 18 and the attraction plate 22 come into contact with each other, and when the air gap amount δ is large, the attraction force generated by the electromagnet 18 is reduced accordingly, and the mold clamping force is also reduced. Become smaller.

A cylindrical pressure piston 17 is supported by a bearing 81 movably in the axial direction with respect to the rear platen 13. One end of the pressure piston 17, that is, a front end (right end in the figure) is a load detector. 25, is fixed to the movable platen 12 through the electromagnet 18 and the rear platen 13 and extends rearward.
7 is connected to the suction plate frame 23 via a link mechanism 61 at the other end, that is, the rear end (left end in the figure). The link mechanism 61 includes a first link 62 supported swingably with respect to the pressure piston 17, a pin 63 serving as a central axis of the first link 62, and the suction plate frame 2.
3 includes a second link 64 swingably supported with respect to the shaft 3, a shaft 65 serving as a center axis of the second link 64, and a pin 66 connecting the first link 62 and the second link 64. 1 and an extended state shown in FIGS. 2 and 3.

In this case, since the pressure piston 17 is supported by the bearing 81 so as to be axially movable with respect to the rear platen 13, the pressure piston 17 is moved when the mold is closed, when the mold is closed, and when the mold is opened. Never lean against. Therefore, the movable platen 12 can be stably supported, and the parallelism between the fixed platen 11 and the movable platen 12 can be increased.

A pair of brackets 84 are formed on the rear surface of the suction plate frame 23 so as to protrude therefrom. The shaft 65 is connected to the suction plate frame 23 via a bearing 85 provided on the bracket 84. Supported rotatably. The shaft 65 is connected to a speed reducer 82.
The link mechanism 61 can be expanded and contracted by driving the electric servomotor 83 as an electric motor via the motor.

Further, one end of the tie bar 14 extends through the fixed platen 11 and is protruded therefrom, and is screwed with a mold thickness adjusting nut 24. The mold thickness adjusting nut 24 is rotatably supported by the fixed platen 11 and is restrained by the fixed platen 11 in the axial direction (the mold opening and closing direction). Therefore, the fixed mold 15
When the mold thickness adjusting nut 24 is rotated in accordance with the thickness of the movable mold 16, the position of the suction plate frame 23 with respect to the fixed platen 11 is adjusted. As a result, the distance between the fixed platen 11 and the rear platen 13 becomes an optimal value, and a large mold clamping force can be sufficiently generated.

When an electric current is supplied to the coil 21, the attraction plate 22 is moved by the attraction force of the electromagnet 18 to the electromagnet 1
Sucked in 8. In this case, since the electromagnet 18 includes the electromagnetic laminated steel sheet 19 and the suction plate 22 includes the electromagnetic laminated steel sheet 52, the responsiveness and stability of the mold clamping device during suction can be improved. By the way, as shown in FIG. 3, the electromagnet 18 and the electromagnetic laminated steel plate 52 are divided into right and left (up and down in FIG. 3), and the pressurizing piston 17 penetrates between the left and right rear platens 13 and the left and right electromagnets 18. The link mechanism 61 extends and contracts between the left and right suction plates 22. Therefore, since there is no need to dispose a pressurizing piston, a link mechanism, and the like outside the rear platen 13 and the suction plate 22, the size of the mold clamping device can be reduced.

Next, the adjustment of the mold thickness of the mold clamping device having the above-described structure will be described. First, the electric servomotor 83 is driven in the forward direction to rotate the shaft 65 in the forward direction, and the link mechanism 61 is placed in the extended state to perform mold thickness adjustment. That is, the link mechanism 61 is placed in the extended state, and a motor or the like (not shown) is driven to rotate the mold thickness adjusting nut 24 to form a predetermined gap between the fixed mold 15 and the movable mold 16. Link mechanism 6
When the fixed mold 15 and the movable mold 16 come into contact with each other when the first platen 1 is put in the extended state, the mold thickness adjusting nut 24 is rotated to move the fixed platen 11 and the rear platen 13 between the fixed platen 11 and the rear platen 13. Is increased so that the predetermined gap is formed between the fixed mold 15 and the movable mold 16. Subsequently, while the link mechanism 61 is in the extended state, the mold thickness adjusting nut 24 is gradually rotated, and the fixed mold 1 is rotated.
When the state where the mold 5 and the movable mold 16 are in contact with each other and the mold clamping force is 0 is formed, the rotation of the mold thickness adjusting nut 24 is stopped.

Next, the operation of the mold clamping device having the above configuration will be described. First, in the state of FIG. 1, the electric servomotor 83 is driven in the forward direction to rotate the shaft 65 forward,
The link mechanism 61 is placed in the extended state. Thereby, the movable platen 12 is advanced, and as shown in FIGS. 2 and 3,
The fixed mold 15 and the movable mold 16 are brought into contact with each other, and the mold is closed. At this time, the rear platen 13 and the suction plate 22
, That is, between the electromagnet 18 and the attraction plate 22, an optimal air gap amount δ is maintained. The force required for closing the mold is sufficiently smaller than the mold clamping force.

Subsequently, in the state shown in FIGS. 2 and 3, a current is supplied to the coil 21 and the attraction plate 22 is attracted by the attraction force of the electromagnet 18. As a result, the bracket 84,
Link mechanism 61, pressurizing piston 17, and load detector 25
The movable platen 12 is further advanced, and the mold is clamped. At this time, the mold clamping force is detected by the load detector 25, and the detected mold clamping force is sent to a control device (not shown), where feedback control is performed so that the mold clamping force becomes a set value. Will be The mold clamping force is maintained until the mold is opened.

In this case, the mold clamping force can be controlled during molding by changing the value of the current supplied to the coil 21. The link mechanism 61 is placed in the extended state, and the first link 62 and the second link 64 are placed on a straight line.
, The force for rotating the first link 62 to contract the link mechanism 61 is hardly generated.
Therefore, the torque generated by the electric servomotor 83 can be reduced, and the holding current supplied to the electric servomotor 83 can be reduced. As a result, the power consumption and heat generation of the electric servomotor 83 can be reduced, and the rated output of the electric servomotor 83 can be reduced accordingly, so that the cost of the mold clamping device can be reduced.

Further, since the mold clamping force is generated only by the attractive force of the electromagnet 18, even if torque ripple occurs in the electric servomotor 83, the mold clamping force does not change. Subsequently, when the cavity space is filled with resin, cooled and solidified, supply of current to the coil 21 is stopped, and the attraction force by the electromagnet 18 becomes zero. Next, in this state, when the electric servomotor 83 is driven in the reverse direction to contract the link mechanism 61, the pressurizing piston 17 is retracted, and the movable platen 12 is further retracted. Then, as shown in FIG. 1, the fixed mold 15 and the movable mold 16 are separated, and the mold is opened.

As described above, during the closing, closing and opening of the mold, the guide post 71 allows the suction plate 22 to be closed.
Is guided, and the stroke of the suction plate 22 is short, so that the parallelism between the electromagnet 18 and the suction plate 22 can be increased. Therefore, the attraction plate 22 does not tilt due to the assembly accuracy of the mold clamping device, friction when the attraction plate 22 is moved, and the like, and the attraction plate 22 is not attracted by the electromagnet 18 in the tilted state.

Before completion of the mold clamping, the electromagnet 18
Therefore, all of the suction force can be transmitted to the movable platen 12 via the pressurizing piston 17. As a result, a large mold clamping force can be generated stably. It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified based on the gist of the present invention, and they are not excluded from the scope of the present invention.

[0027]

As described above in detail, according to the present invention, in a mold clamping device, a fixed platen, a fixed mold attached to the fixed platen, and a predetermined distance from the fixed platen. A movable platen disposed movably along a tie bar provided between the fixed platen and the rear platen; a movable mold attached to the movable platen; an electromagnet; An electromagnet and an attraction plate unit, wherein one of the electromagnet and the attraction plate is fixed to the rear surface of the rear platen, and the other member is movably disposed; A pressure piston having one end fixed to the movable platen and the other end connected to the other member via a link mechanism; In the back of the square of the member is connected to the link mechanism, and a motor which can be driven in forward and reverse.

In this case, when the electric motor is driven, the link mechanism is extended, the movable platen is advanced, and the fixed mold and the movable mold are brought into contact with each other to close the mold. In this state, a certain gap is formed between the electromagnet and the attraction plate. Next, when a current is supplied to the coil of the electromagnet, the suction plate is attracted by the attraction force of the electromagnet,
The mold is clamped. The mold clamping force is maintained until the mold is opened.

Therefore, by changing and controlling the value of the current supplied to the coil, the mold clamping force can be controlled during molding. In addition, since the link mechanism is placed in the extended state, even if the mold clamping force is transmitted to the link mechanism, almost no force for contracting the link mechanism is generated. Since the torque generated by the motor can be reduced, the holding current supplied to the motor can be reduced. As a result, the amount of power consumption and the amount of heat generated by the motor can be reduced, and the rated output of the motor can be reduced accordingly, so that the cost of the mold clamping device can be reduced.

Further, since the mold clamping force is generated only by the attraction force of the electromagnet, the mold clamping force does not fluctuate even if torque ripple occurs in the electric motor. Since the pressurizing piston is supported by the bearing so as to be movable in the axial direction with respect to the rear platen, the pressurizing piston does not tilt with respect to the rear platen when closing, closing, and opening the mold. Therefore, the movable platen can be stably supported, and the parallelism between the fixed platen and the movable platen can be increased.

Further, since the electric motor is disposed on the back of the other member, a pressure piston, a link mechanism and the like are disposed through the rear platen and the electromagnet / adsorption plate unit. Therefore, the size of the mold clamping device can be reduced. Since the stroke of the suction plate is short, the degree of parallelism between the electromagnet and the suction plate can be increased. Therefore, the assembling plate does not tilt due to the assembly accuracy of the mold clamping device, friction when moving the absorbing plate, and the like.
The attraction plate will not be attracted by the electromagnet in the inclined state. Further, since the electromagnet and the attraction plate do not come into contact with each other before the mold clamping is completed, all of the attraction force can be transmitted to the movable platen via the pressure piston. As a result, a large mold clamping force can be generated stably.

[Brief description of the drawings]

FIG. 1 is a front view showing a first state of a mold clamping device according to an embodiment of the present invention.

FIG. 2 is a front view showing a second state of the mold clamping device according to the embodiment of the present invention.

FIG. 3 is a plan view showing a second state of the mold clamping device according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Fixed platen 12 Movable platen 13 Rear platen 14 Tie bar 15 Fixed mold 16 Movable mold 17 Pressurized piston 18 Electromagnet 22 Suction plate 61 Link mechanism 81 Bearing 83 Electric servo motor

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-277523 (JP, A) JP-A-5-147088 (JP, A) JP-A-61-154823 (JP, A) JP-A-5-154823 237893 (JP, A) JP-A-6-63954 (JP, A) JP-A-8-169040 (JP, A) JP-A-50-16757 (JP, A) JP-A-8-281175 (JP, A) JP-A-7-112469 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 45/64-45/68 B22D 17/26

Claims (1)

(57) [Claims] 1. A fixed platen, (b) a fixed mold attached to the fixed platen, (c) a rear platen disposed at a predetermined distance from the fixed platen, (d). (E) a movable mold attached to the movable platen, the movable mold being mounted on the movable platen along a tie bar provided between the fixed platen and the rear platen, and (f) an electromagnet and an attraction plate. One of the electromagnet and the attraction plate is fixed to the rear surface of the rear platen, and the other member is movably disposed.
A suction plate unit, and (g) a bearing supported axially movably with respect to the rear platen by a bearing, one end fixed to the movable platen, and the other end connected to the other member via a link mechanism. Pressure piston and (h)
A mold clamping device, comprising: a motor connected to the link mechanism on a back surface of the other member and capable of being driven in forward and reverse directions.