JP3155477B2 - 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 molded product can be obtained by injecting a resin from an injection nozzle of an injection device, filling the resin into a cavity space of a mold device, and solidifying the resin. Has become. The mold device includes a fixed mold, a movable mold disposed to be able to advance and retreat with respect to the fixed mold, and moving the movable mold to close, close, and clamp the mold device. It has a mold clamping device for opening 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. Tightening devices are increasingly being used because they are not only highly controllable, but also clean and energy efficient. In this case, the electric motor is driven to rotate the ball screw to generate a thrust, 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. And the stability is reduced, and 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 conventional mold clamping device, the mold clamping force fluctuates due to the torque ripple generated in the electric motor. In addition, in order to generate a mold clamping force, it is necessary to constantly supply a current to the motor, and the amount of power consumption and heat generation of the motor increases.
It is necessary to increase the rated output of the electric motor accordingly, which increases the cost of the mold clamping device.

In view of the above, there is considered a mold clamping device in which an electromagnet and a suction plate are arranged to face each other, a suction force is generated by the electromagnet to suck the suction plate, and the suction force is used as a mold clamping force. Can be However, the assembly accuracy of the mold clamping device, the suction plate may be inclined due to friction or the like when moving the suction plate, and when the suction plate is inclined and sucked by the electromagnet, when the mold closing is completed, A portion where the gap between the electromagnet and the attraction plate is small and a portion where the gap is large are formed. The attraction force is inversely proportional to the square of the distance between the electromagnet and the attraction plate. Therefore, the attraction force is increased at a portion where the gap is small, and the attraction force is decreased at a portion where the gap is large. The board tilts further.

As a result, the electromagnet and the attraction plate come into contact with each other, and the electromagnet itself receives a part of the attractive force.
It 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 easily change the mold clamping force, can control the mold clamping force during molding, and stabilize the large mold clamping force. It is an object of the present invention to provide a mold clamping device which can be generated at a low cost and can reduce the cost.

[0008]

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 / adsorption plate unit in which one member of an electromagnet and an adsorption plate is fixed to the rear surface of the rear platen, and the other member is movably disposed; one end is attached to the other member; A pressurizing piston fixed to a platen, a motor operable in forward and reverse directions, a molding machine disposed between the motor and the pressurizing piston, A rotation direction conversion means for converting the rotational movement of the electric motor into a linear movement and transmitting the linear movement to the pressurizing piston, and disposed between the one member and the other member; And a mold thickness adjusting nut that is disposed between the other member and the pressure piston and that adjusts the position of the other member with respect to the pressure piston by rotating the guide member. .
In another mold clamping device of the present invention, the mold thickness adjusting nut is supported rotatably with respect to the other member, and is constrained by the other member in the axial direction. Screwed with the piston. In still another mold clamping device of the present invention, the movement direction changing means may further include a ball nut fixed to an inner periphery of a rear end of the pressurizing piston, and a ball screw screwed with the ball nut. Become. The rear end of the ball screw is rotatably supported on the molding machine frame by a bearing, and is connected to the electric motor.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a mold opening state of the mold clamping device according to the embodiment of the present invention, and FIG. 2 is a diagram showing a mold clamping state of the mold clamping device according to the embodiment of the present invention. In the figure, reference numeral 11 denotes a fixed platen, a rear platen 13 is disposed at a predetermined distance from the fixed platen 11, and four tie bars 14 (in the figure, four tie bars 14) are provided between the fixed platen 11 and the rear platen 13.
Only two tie bars 14 are shown. ) Is erected. A movable platen 12 is disposed along the tie bar 14 so as to face the fixed platen 11 so as to be able to advance and retreat (move in the left-right direction in the figure).

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 the cavity space is filled with resin as the resin is injected. .

An electromagnet 18 is fixed as one member to the back (left side in the figure) of the rear platen 13. The electromagnet 18 is composed of an electromagnetic laminated steel sheet 19,
Electromagnet frame 2 for fixing the frame to the rear platen 13
0, a guide bush 71 disposed at three or more positions of the electromagnet frame 20, and a coil 21 for generating a magnetomotive force. And, facing the electromagnet 18,
The suction plate 22 is movably provided along the rail 51 as the other member. The suction plate 22 is made of the electromagnetic laminated steel sheet 5.
2. Suction plate frame 2 supporting the electromagnetic laminated steel sheet 52
3, and at a position corresponding to the guide bush 71, the guide bush 71 can be fitted (slidably) and slidably fitted.
Guide pin 7 movably arranged on suction plate frame 23
Consists of two. In this case, the electromagnet 18 and the attraction plate 22
The guide bush 71 and the guide pin 72 constitute guide means, respectively. In addition, 54 is a linear guide.

In this 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. Further, in the present embodiment, the guide bush 71 is provided on the electromagnet frame 20 and the guide pin 72 is provided on the attraction plate frame 23. However, the guide pin 72 is provided on the electromagnet frame 20, and the guide plate 72 is provided on the attraction plate frame 23. Each of the bushings 71 can be provided.

The suction plate 22 has one end of the cylindrical pressure piston 17 at the rear end (the left end in the figure).
Is fixed, and the pressure piston 17 is fixed to the fixed platen 11.
, And penetrates the electromagnet 18 and the rear platen 13, and the other end, that is, the front end (right end in the figure) is fixed to the movable platen 12. Therefore, as the suction plate 22 moves, the movable platen 12 also moves forward and backward.

A mold thickness adjusting nut 24 is disposed between the suction plate frame 23 and the pressure piston 17, and the mold thickness adjustment nut 24 is rotatably supported by the suction plate frame 23. Further, in the axial direction (the mold opening and closing direction), it is restrained by the suction plate frame 23 and is moved forward and backward together. The mold thickness adjusting nut 24 and the pressurizing piston 17 are screwed together, and by rotating the mold thickness adjusting nut 24 via the gear 25, the position of the suction plate 22 with respect to the pressurizing piston 17 is changed. Can be adjusted. Therefore, the gap between the electromagnet 18 and the attraction plate 22 can be set to an optimum value in accordance with the thickness of the fixed mold 15 and the movable mold 16, and a sufficiently large mold clamping force can be generated.

When a current is supplied to the coil 21, the attracting force of the electromagnet 18 causes the attraction plate 22 to move the electromagnet 1
Sucked in 8. In this case, since the electromagnet 18 is provided with the electromagnetic laminated steel plate 19 and the suction plate 22 is provided with the electromagnetic laminated steel plate 52, the responsiveness and stability of the mold clamping device at the time of suction can be improved. The guide bush 71 has an inner diameter slightly larger than the outer diameter of the guide pin 72, and the guide pin 72 enters the guide bush 71 as the suction plate 22 advances (moves rightward in the drawing). Then, the guide pins 72 are guided by the guide bush 71 and are slid in the horizontal direction with respect to each other. In this case, since the parallelism between the electromagnet 18 and the suction plate 22 can be increased, the suction plate 22 does not tilt due to assembly accuracy of the mold clamping device, friction when moving the suction plate 22, and the like. The attraction plate 22 is no longer attracted by the electromagnet 18 in the inclined state.

Since the electromagnet 18 and the suction plate 22 do not come into contact with each other before the mold clamping is completed, all of the suction force is transferred to the movable platen 12 via the pressure piston 17.
Can be transmitted to As a result, a large mold clamping force can be generated stably. The length of the guide pin 72 is set such that the guide pin 72 enters the guide bush 71 when the suction plate 22 advances by a set distance. In this case, the guide pin 72 is guided by the guide bush 71 and is slid in the horizontal direction only in a range where the attraction force by the electromagnet 18 is large, so that the load applied to the servomotor 27 as the electric motor is reduced accordingly. The amount of power consumption and the amount of heat generated by the servo motor 27 can be reduced. In addition, the guide pin 72 is extended, and the guide pin 72 is
You can always be guided by.

A ball nut 56 is fixed to the inner periphery of the rear end of the pressure piston 17.
6 and the ball screw 26 are screwed together. The movement direction converting means is constituted by the ball nut 56 and the ball screw 26, and the rotational movement generated by the servomotor 27 and transmitted to the ball screw 26 is converted into a linear movement and transmitted to the pressure piston 17. . To this end, the rear end of the ball screw 26 is rotatably supported by a bearing 28 on a molding machine frame 29 and is connected to a servomotor 27. The front end of the ball screw 26 is made to enter the inside of the pressure piston 17.

In this embodiment, the ball screw 26 and the servomotor 27 are directly connected, but may be connected via a not-shown pulley, belt or the like. Next, the operation of the mold clamping device having the above configuration will be described. In the state shown in FIG. 1, when the servo motor 27 is driven in the forward direction to rotate the ball screw 26 forward, the ball nut 56 screwed with the ball screw 26 is advanced, and the ball nut 56 is moved forward. And pressurized piston 1
7 and the suction plate 22 are advanced, and the movable platen 1
2 is advanced. Then, as shown in FIG. 2, the fixed mold 15 and the movable mold 16 are brought into contact with each other, and the mold is closed. The force required for closing the mold is sufficiently smaller than the mold clamping force.

When the mold closing is completed, the electromagnet 1
In order to form a fixed gap between the suction plate 8 and the suction plate 22, the position of the suction plate 22 with respect to the pressure piston 17 is adjusted in advance by the mold thickness adjusting nut 24. next,
When a current is supplied to the coil 21 in the state of FIG.
The attraction plate 22 is attracted by the attraction force of the electromagnet 18, and at this time, the attraction force of the electromagnet 18 is sequentially transmitted to the electromagnetic laminated steel sheet 52, the attraction plate frame 23, the mold thickness adjusting nut 24, the pressure piston 17, and the movable platen 12. Then, the movable mold 16 is pressed against the fixed mold 15 as a mold clamping force to perform mold clamping. The mold clamping force is maintained until the mold is opened.

In this case, the mold clamping force can be changed during molding by changing the value of the current supplied to the coil 21. Since the mold clamping force is received by the pressurizing piston 17 and is not applied to the ball screw 26, the ball screw 26 can be made as strong as necessary for closing the mold. Therefore, the cost of the mold clamping device can be reduced, and the durability can be improved.

Since the mold clamping force is generated solely by the attraction force of the electromagnet 18, even if torque ripple occurs in the servomotor 27, the mold clamping force does not fluctuate. Further, since the servomotor 27 can be stopped at the time of mold clamping, it is not necessary to constantly supply current to the servomotor 27. Therefore, the power consumption and heat generation of the servomotor 27 can be reduced, the rated output of the servomotor 27 can be reduced, and the cost of the mold clamping device can be reduced.

Subsequently, when the cavity space is filled with resin, cooled and solidified, the current supplied to the electromagnet 18 is cut off. As a result, there is no suction force and no mold clamping force. In this state, the servo motor 2
7 is driven in the reverse direction to rotate the ball screw 26 in the reverse direction, and the ball nut 56 screwed with the ball screw 26 is rotated.
Is retracted, and as the ball nut 56 is retracted, the pressure piston 17 and the suction plate 22 are 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.

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.

[0024]

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 / adsorption plate unit in which one member of an electromagnet and an adsorption plate is fixed to the rear surface of the rear platen, and the other member is movably disposed. Pressurizing pistons each having an end fixed to the movable platen, a motor capable of driving in forward and reverse directions, disposed between the motor and the pressurizing piston, and Supported by the molding machine frame, converting the rotational motion of the electric motor into a linear motion, and transmitting the linear motion to the pressurizing piston; and a motion direction converting means disposed between the one member and the other member. A guiding means for preventing the member from tilting, a mold thickness adjusting nut disposed between the other member and the pressurizing piston, and rotating to adjust the position of the other member with respect to the pressurizing piston. Having.

In this case, when the motor is driven to operate the movement direction changing means, the pressurizing piston and the other member are advanced, the movable platen is further advanced, and the fixed mold and the movable mold come into contact with each other. The mold is closed. When the mold closing is completed, the position of the other member with respect to the pressure piston is adjusted by the mold thickness adjusting nut to form a constant gap between the one member and the other member. Subsequently, when a current is supplied to the coil of the electromagnet, the attractive force of the electromagnet is transmitted to the other member, the mold thickness adjusting nut, the pressurizing piston, and the movable platen in order, and becomes a mold clamping force to fix the movable mold to the fixed mold. The mold is pressed and the mold is clamped. When the mold is closed, the guide member disposed between the one member and the other member prevents the other member from tilting. Therefore, the parallelism between the one member and the other member can be increased, so that the other member is tilted due to the assembly accuracy of the mold clamping device, friction when moving the other member, or the like. Is no longer sucked.

Since one member and the other member do not come into contact with each other, all of the suction force can be transmitted to the movable platen. As a result, a large mold clamping force can be generated stably. Further, by changing the value of the current supplied to the coil of the electromagnet,
The mold clamping force can be changed during molding. Further, since the mold clamping force is received by the pressurizing piston and is not applied to the movement direction changing means, the strength of the movement direction changing means can be made as strong as required for closing the mold.
Therefore, the cost of the mold clamping device can be reduced, and the durability can be improved.

Since the mold clamping force is generated solely by the attractive force of the electromagnet, the mold clamping force does not fluctuate even if torque ripple occurs in the electric motor. further,
Since it is not necessary to constantly supply an electric current to the electric motor in order to generate the mold clamping force, the amount of power consumption and the amount of heat generated by the electric motor can be reduced. Therefore, the rated output of the electric motor can be reduced, and the cost of the mold clamping device can be reduced. Further, by rotating the mold thickness adjusting nut, the position of the other member with respect to the pressure piston can be adjusted. Therefore, the gap between one member and the other member can be set to an optimum value according to the thickness of the fixed mold and the movable mold, and a sufficiently large mold clamping force can be generated.

[Brief description of the drawings]

FIG. 1 is a diagram showing a mold opening state of a mold clamping device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a mold clamping 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 26 Ball screw 27 Servo motor 56 Ball nut 71 Guide bush 72 Guide pin

Claims (3)

(57) [Claims] (A) 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; (E) a movable mold attached to the movable platen, the movable mold being mounted on the movable platen so as to be able to advance and retreat along a tie bar provided between the fixed platen and the rear platen; An electromagnet / adsorption plate unit in which one of the electromagnet and the adsorption plate is fixed to the rear surface of the rear platen, and the other member is movably disposed; and (g) one end is connected to the other member. other end is pressure piston which is fixed to the movable platen, an electric motor can be driven in forward and reverse (h), disposed between the (i) the electric motor and the pressure piston, Or
A movement direction converting means supported by the molding machine frame, converting the rotational movement of the electric motor into a linear movement, and transmitting the linear movement to the pressurizing piston; (j) between the one member and the other member; Arranged,
Disposed of in between the guiding means for preventing tilting of the other member, and (k) the other member and the pressure piston
The rotation of the
A mold thickness adjusting nut for adjusting the position of the member . 2. The mold thickness adjusting nut is connected to the other member.
To be rotatable with respect to
Of the pressure piston and the screw
The mold clamping device according to claim 1, which is combined. 3. (a) The movement direction converting means includes:
A ball nut fixed to the inner circumference at the rear end of the pressure piston, and
And a ball screw screwed with the ball nut.
Ri, (b) the rear end of the ball screw, the molding machine by bearings
While being rotatably supported with respect to the frame,
The mold clamping device according to claim 1, which is connected to an electric motor.