JPH10151651A - Mold clamping device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a mold clamping force during a molding and make it possible to stably generate a large mold clamping force by a method wherein either one of an electromagnet and a suction plate is fixed and the other one is arranged movably and a means for transmitting the rotary motion of a motor after being converted to a straight-line motion to a pressurizing piston and the like are equipped. SOLUTION: By fixing a ball nut 56 into the inner periphery of the rear end of a pressurizing piston 17, a moving direction covering means, to which a ball screw 26 is threaded, is provided. The rotary motion, which generates from a servo motor 27 and is transmitted to the ball screw 26, is converted by the moving direction converting means to a straight-line motion so as to be transmitted to the pressurizing piston 17. When the servo motor 27 is driven clockwise, the pressurizing piston advances, resulting in bringing a fixed mold 15 and a movable mold 16 into contact with each other so as to clamp the molds. Next, by feeding a current to a coil 21, the suction plate 22 is attracted by means of the attraction of the electromagnet 18. At this time, the attraction of the electromagnet 18 is transmitted to a movable platen 12 as a mold clamping force. By changing the value of the current to be fed to the coil 21, the mold clamping force during a molding is changed.

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.

[0004]

However, in the above-mentioned conventional electric type mold clamping device, a toggle mechanism is used. Therefore, it is necessary to change the mold clamping force due to the characteristics of the toggle mechanism. Difficult, responsiveness and stability are reduced, and the mold clamping force cannot be controlled during molding.

[0005] Therefore, there has been provided a mold clamping device in which a thrust generated by a ball screw can be directly used 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. However, since a large load is applied to the ball screw with the mold clamping, a large mold clamping force cannot be generated. In addition, the mold clamping force fluctuates due to the torque ripple generated in the electric motor. Further, in order to generate the mold clamping force, it is necessary to constantly supply a current to the motor, and the power consumption and the heat generation of the motor increase. Therefore, it is necessary to increase the rated output of the electric motor, which increases the cost of the mold clamping device.

The present invention solves the above-mentioned problems of the conventional mold clamping device, and can easily change the mold clamping force, control the mold clamping force during molding, and further increase the size of the mold. An object of the present invention is to provide a mold clamping device capable of stably generating a clamping force and reducing costs.

[0007]

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, an electric motor that can be driven in forward and reverse directions, and a motor disposed between the electric motor and the pressurized piston. The rolling motion is converted into linear motion and a motion direction converting means for transmitting the pressure piston.

In another embodiment of the present invention, the electromagnet and the attraction plate each include an electromagnetic laminated steel plate. In still another mold clamping device of the present invention,
A mold thickness adjustment nut is provided between the other member and the pressure piston, and the position of the other member with respect to the pressure piston is adjusted by rotating the mold thickness adjustment nut.

[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 and a coil 21 for generating a magnetomotive force. Then, the suction plate 22 is provided as the other member so as to face the electromagnet 18 and to be movable along the rail 51. 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 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. The suction plate 22 has a cylindrical pressure piston 1.
7 is fixed at one end, that is, the rear end (left end in the figure), and the pressurizing piston 17 extends toward the fixed platen 11, penetrates through the electromagnet 18 and the rear platen 13, and the other end, that is, the front end (in the figure) (Right end) is fixed to the movable platen 12. Therefore, the movable platen 12 is moved forward and backward as the suction plate 22 moves.

A mold thickness adjusting nut 24 is provided 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 pressurizing piston 17
A ball nut 56 is fixed to the inner periphery of the rear end, and the ball nut 56 and the ball screw 26 are screwed together.
The movement direction conversion means is constituted by the ball nut 56 and the ball screw 26. In this case, the rotational motion generated by the servomotor 27 as an electric motor and transmitted to the ball screw 26 is converted into linear motion by the motion direction converting means and transmitted to the pressurizing 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
7 is entered.

In the present 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 of FIG. 1, when the servomotor 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 moved forward (moved rightward in the figure). With the advance of the ball nut 56, the pressurizing piston 17 and the suction plate 22 are advanced, and the movable platen 12 is further 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
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 so that a certain gap is formed between the suction plate 8 and the suction plate 22. Next, in the state of FIG. 2, when a current is supplied to the coil 21, 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
2. It is sequentially transmitted to the suction plate frame 23, the mold thickness adjusting nut 24, the pressurizing piston 17, and the movable platen 12, and as a mold clamping force, presses the movable mold 16 against the fixed mold 15 to perform mold clamping. The mold clamping force is maintained until the mold is opened.

In this case, by changing the value of the current supplied to the coil 21, the mold clamping force can be changed during molding. 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 attractive force of the electromagnet 18, even if torque ripple occurs in the servo motor 27, the mold clamping force does not change. 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 a resin is filled in a cavity space (not shown), and the resin is 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, when the servo motor 27 is driven in the reverse direction and the ball screw 26 is rotated in the reverse direction, the ball nut 56 screwed with the ball screw 26 is retracted (moves leftward in the drawing), and the ball nut 56 With the retraction, the pressurizing 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.

[0021]

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, an electric motor that can be driven in forward and reverse directions, disposed between the electric motor and the pressurizing piston, And a motion direction converting means for the rotational movement of the motive is converted into linear motion and transmits the pressure piston.

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. Subsequently, when current is supplied to the coil of the electromagnet, the other member is attracted to one member, and at this time, the attraction force of one member is applied to the other member, the mold thickness adjusting nut, the pressurizing piston, and the movable platen. The movable mold is pressed against the fixed mold, and the mold is clamped.

In this case, the mold clamping force can be changed during molding by changing the value of the current supplied to the coil. Further, since the mold clamping force is received by the pressurizing piston and is not applied to the movement direction changing means, the movement direction changing means 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.

Further, 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 a current to the motor in order to generate the mold clamping force, the amount of power consumption and the amount of heat generated by the 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.

In another mold clamping device according to the present invention, the electromagnet and the attraction plate each include an electromagnetic laminated steel plate. In this case, the responsiveness and stability of the mold clamping device during suction can be improved by the electromagnetic laminated steel sheet. In still another mold clamping device of the present invention, a mold thickness adjustment nut is further provided between the other member and the pressure piston, and by rotating the mold thickness adjustment nut, The position of the other member is adjusted.

In this case, by setting the gap between one member and the other member to an optimum value in accordance with the thickness of the fixed mold and the movable mold, a sufficiently large mold clamping force is generated. Can be done.

[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 19, 52 Electromagnetic laminated steel plate 22 Suction plate 24 Thickness adjustment nut 26 Ball screw 27 Servo motor 56 Ball nut

Claims (3)

[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.
(G) a pressure piston having one end fixed to the other member and the other end fixed to the movable platen, and (h) an electric motor that can be driven in the forward and reverse directions. i) a mold clamping device which is provided between the electric motor and the pressurizing piston and has a motion direction converting means for converting a rotational motion of the electric motor into a linear motion and transmitting the linear motion to the pressurizing piston. 2. The mold clamping device according to claim 1, wherein the electromagnet and the attraction plate each include an electromagnetic laminated steel plate. 3. A mold thickness adjusting nut is provided between the other member and the pressure piston, and the position of the other member with respect to the pressure piston is adjusted by rotating the mold thickness adjustment nut. The mold clamping device according to claim 1.