JPH0474625A - Mold clamping device of motor-driven injection molding machine - Google Patents

Abstract

PURPOSE:To enlarge a transmission quantity of torque even in the course of mold clamping and control sudden mold clamping, by a method wherein the title device possesses an arm rocking a lever by being turned by a motor and a relative distance between a sliding part and the rotary center is specified. CONSTITUTION:The title device possesses an arm 30 which is slid with a lever 27 arranged on a link-connected part between arms 23, 24 of a crank mechanism and is turned by a motor 7. When the motor 7 is turned, following which the arm 30 is turned and a movable platen 1 is reciprocated by rocking a crank mechanism through the lever 27. At this time, the motor 7 is arranged to such a position that the distance between a part where the lever 27 slides with the arm 30 and the rotary center of the motor 7 becomes short gradually at the time of mold clamping and long gradually at the time of mold break. With this construction, at the time of the mold clamping, generated torque can be transmitted sufficiently to a crank mechanism by the motor 7 and at the time of the mold break, a sufficient mold breaking force can be obtained until completion of the mold break. Moreover, since mold clamping force is generated generously, the mold can be protected.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a mold clamping device for an electric injection molding machine.

(Prior art) Conventionally, a molding material that has been heated and fluidized in a heating cylinder is injected into a mold under high pressure, and is cooled and solidified in the mold.
Next, in an injection molding machine that opens the mold and takes out the molded product, the mold is tightened with sufficient pressure to prevent it from opening against the high pressure of the molten resin injected into the mold. A mold clamping device is provided.

The linear mold clamping device is connected to a movable platen that supports a movable mold, and can be moved toward and away from the fixed platen by a hydraulic, electric, or other drive device.

Furthermore, mold clamping devices are classified into direct pressure type mold clamping devices and toggle type mold clamping devices depending on the driving method.

The direct pressure type mold clamping device connects a mold clamping cylinder to the rear of the movable platen, and by supplying pressure oil to the mold clamping cylinder,
The piston inside the mold clamping cylinder moves back and forth to close the mold via a rod, and performs mold clamping, mold opening, etc.

In the case of the direct pressure type mold clamping device, the mold clamping force is generated by a hydraulic cylinder, so stable mold clamping force can be obtained, but the mold opening/closing mechanism, mold clamping force generation mechanism, and the hydraulic circuit for this are complicated. However, in the case of a toggle type mold clamping device, there is no need to provide a complicated mechanism and it is possible to increase the opening and closing speed.

The conventional single toggle type mold clamping device described above is shown in FIG.

In the figure, 1 is a movable platen that supports a movable mold 2 and is movable back and forth. A fixed platen 3 supports a fixed mold 4 and is disposed at a fixed position so as to face the movable platen 1. 5 is a toggle support, and a tie bar 6 connects the toggle support 5 and the fixed platen 3, and the movable platen 1 slides along the tie bar 6 to close the mold, open the mold, clamp the mold, etc. I do.

The movable platen 1 is driven by a mold opening/closing servo motor 7. The mold opening/closing servo motor 7 and the movable platen 1 are connected by links 8 and 9, and the rotation of the linear opening/closing servo motor 7 is decelerated by a reduction gear (not shown) to swing the link 8. The links 8.9 expand with the dynamic movement to close and clamp the mold, and contract to open the mold.

Reference numeral 10 denotes a mold thickness adjustment motor, and the rotation of the mold thickness adjustment motor 10 is reduced by a speed reducer (not shown), and the rotation is reduced to gear 1.
1 rotates, the nut gear 13 rotates via the synchronous gear 12. The nut gear 13 is screwed into a screw 14 formed on the tie bar 6, and as the nut gear 13 rotates, the tie bar 6 can be extended to adjust the mold thickness.

(Problem to be Solved by the Invention) However, in the mold clamping device of the conventional electric injection molding machine described above, a single toggle mechanism is adopted, but this mechanism Since mold clamping force is generated, not only is the low-pressure mold clamping force insufficient on the way to the vicinity of the dead center, but also the necessary amount of mold opening force is required for the required section when opening the mold. can't get it.

Furthermore, since mold clamping force is suddenly generated near the dead center, it becomes difficult to protect the mold.

Therefore, in order to obtain sufficient mold clamping force and mold opening force other than near the dead center, we increased the capacity of the mold opening/closing servo motor 7,
The reduction ratio of the reducer must be increased, resulting in high costs.

The present invention solves the problems of the mold clamping device of the conventional electric injection molding machine described above, and achieves low-pressure mold clamping during mold closing without increasing the capacity of the mold opening/closing servo motor or increasing the reduction ratio. An object of the present invention is to provide a mold clamping device for an electric injection molding machine that can obtain sufficient mold opening force when opening the mold and protect the mold.

(Means for Solving the Problems) For this purpose, the mold clamping device of the electric injection molding machine of the present invention includes a fixed platen, a toggle support disposed opposite to the fixed platen, and the fixed platen and toggle support. a tie bar disposed between; a movable platen that moves toward and away from the fixed platen along the tie bar; and a movable platen disposed between the toggle support and the movable platen, and a a crank mechanism; a lever disposed at a link connecting portion between the first and second arms of the crank mechanism; and a lever disposed to be slidable on the lever and rotated by a motor to swing the lever It has a third arm that moves.

The motor is arranged at a position such that the distance between the part where the lever slides on the third arm and the rotation center of the motor gradually becomes shorter when the mold is closed, and gradually becomes longer when the mold is opened. It is intended to be done.

(Function) According to the present invention, as described above, the fixed platen, the togefure support arranged opposite to the fixed platen, the tie bar arranged between the fixed platen and the toggle support, and the tie bar a movable platen that moves toward and away from the fixed platen along the axis; a crank mechanism disposed between the toggle support and the movable platen and consisting of a first arm and a second arm; It has a lever disposed at a link connecting portion between the second arms, and a third arm slidably disposed on the lever and rotated by a motor to swing the lever.

Therefore, when the motor is driven and rotates, the third arm rotates accordingly, swinging the crank mechanism via the lever and reciprocating the movable platen.

At this time, the motor is arranged at a position such that the distance between the part where the lever slides on the third arm and the rotation center of the motor gradually becomes shorter when the mold is closed, and gradually becomes longer when the mold is opened. Therefore, during the mold clamping process, the distance between the rotation center of the motor and the sliding part is shortened.
The torque generated by the motor can be sufficiently transmitted to the crank mechanism.

Further, when opening the mold, the distance between the rotation center of the motor and the sliding portion is gradually increased, so that sufficient mold opening force can be obtained until the mold opening is completed.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

1 is a top view of the mold clamping device of the electric injection molding machine of the present invention, FIG. 2 is a front view of the mold clamping device of the electric injection molding machine of the present invention, and FIG. 3 is a top view of the mold clamping device of the electric injection molding machine of the present invention. FIG. 3 is a diagram showing the mold opening state of the mold clamping device of the injection molding machine.

In the figure, 1 is a movable platen that supports a movable mold 2 and is movable back and forth. A fixed platen 3 supports a fixed mold 4 and is disposed at a fixed position so as to face the movable platen 1. 5 is a toggle support, and a tie bar 6 connects the toggle support 5 and the fixed platen 3, and the movable platen 1 slides along the tie bar 6 to close the mold, open the mold, clamp the mold, etc. conduct.

The arm 2 is connected to the toggle support 5 via the bin 21.
3 is rotatably attached to the movable platen 1, and an arm 24 is rotatably attached to the movable platen 1 via a pin 22.

Further, the arms 23 and 24 are rotatably connected by a pin 25. A lever 27 is rotatably attached to the pin 25, and as the arm 23 rotates around the bin 21, the pin 25 swings in a similar trajectory. A through hole is formed in the lever 27, and the arm 30 passes through the through hole.

The arm 30 is fixed to the shaft of a mold opening/closing servo motor, and when the mold opening/closing servo motor 7 is driven, the arm 30 rotates and the lever 27 slides on the arm 30. That is, at the time when mold closing is completed, the arm 30 is in a horizontal state as shown in FIG.
It will be destroyed. At this time, the lever 27 moves to the position closest to the rotation center of the mold opening/closing servo motor on the arm 30.

Furthermore, when the mold opening starts, the arm 30 rotates counterclockwise in the figure and moves upward, and when the mold opening ends, it stops at a point beyond the vertical position as shown in Figure 3. . At this time, the lever 27 moves to the farthest position on the arm 30 from the center of rotation of the mold opening/closing servo motor.

As mentioned above, when the mold opening/closing servo motor 7 is driven, the arm 30 turns, and the lever 27 and pin 2 are rotated accordingly.
5 swings around the rotation axis of a mold opening/closing servo motor 7. This rocking motion is transmitted to the movable platen 1 via a crank mechanism constituted by an arm 23 and an arm 24, and causes the movable platen 1 to move forward and backward. Note that the lever 9 slides on the arm 30 along with the swinging movement.

In the mold clamping process, the mold opening/closing servo motor 7
Center-to-center distance between the center and the bin 25 (lever 27)! 1 becomes smaller, and the center-to-center distance it between the pin 25 and the bottle 22 and the above-mentioned center-to-center distance! , the ratio it/11 increases. Therefore, a sufficient mold clamping force can be generated with a smaller torque than when the arm 23 is pivoted around the pin 21 as in the mold clamping device of a conventional electric injection molding machine.

Further, when the movable platen 1 is moved toward the toggle support 5 side such as in the mold closing process or the mold opening process, when the mold opening/closing servo motor 7 rotates and the arm 30 is rotated, the lever 27 is moved to the arm 30. 30 and gradually move away from the center of rotation of the mold opening/closing servo motor 7. That is, the above ratio it/i! , I changes, and the force for moving the movable platen also changes.

For example, during mold closing, the above ratio j
2 As t/l + changes, the movable platen 1
moves toward the fixed platen 3, but since the pressing force increases with each inquiry, sufficient low-pressure mold clamping force can be obtained before starting the mold clamping process.

Also, while opening the mold, the above ratio ff
i,#! As , changes, the movable platen 1 moves toward the toggle support 5, but since the pressing force decreases with each inquiry, a sufficient mold opening force can be obtained.

Since the mold clamping force is prevented from being generated suddenly, the mold can be protected.

Further, since the mold clamping force is received by the arms 23 and 24, there is no fear that the mold opening/closing servo motor 7 will receive a radial load, and the life of the mold opening/closing servo motor 7 can be extended.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

(Effects of the Invention) As described above in detail, according to the present invention, a crank mechanism consisting of a first arm and a second arm is disposed between a toggle support and a movable platen, and the first arm of the crank mechanism
It has a lever disposed at a link connection portion between the second arms, and a third arm disposed slidably on the lever and rotated by a motor to swing the lever, The motor is arranged at a position such that the distance between the part where the lever slides on the third arm and the rotation center of the motor gradually becomes shorter when the mold is closed, and gradually becomes longer when the mold is opened. It's Nishide.

Therefore, during the mold clamping process, the distance between the rotation center of the motor and the sliding part is short, and the torque generated by the motor can be sufficiently transmitted to the crank mechanism, and the amount of torque transmitted can be reduced even during the mold clamping process. Due to the large size, sufficient low-pressure mold clamping force can be obtained.

Further, when opening the mold, the distance between the rotation center of the motor and the sliding portion is gradually increased, so that sufficient mold opening force can be obtained until the mold opening is completed.

Therefore, the capacity of the motor can be reduced, and the mold can be protected since sudden mold clamping is not performed.

[Brief explanation of the drawing]

1 is a top view of the mold clamping device of the electric injection molding machine of the present invention, FIG. 2 is a front view of the mold clamping device of the electric injection molding machine of the present invention, and FIG. 3 is a top view of the mold clamping device of the electric injection molding machine of the present invention. FIG. 4 is a diagram showing a mold opening state of a mold clamping device of an injection molding machine, and is a diagram showing a conventional toggle type mold clamping device. 1... Movable platen, 2... Movable mold, 3... Fixed platen, 4... Fixed mold, 5... Toggle support, 6... Tie bar, 7... For opening and closing the mold. Servomotor,
23.24゜30...Arm, 27...Lever Patent applicant Sumitomo Heavy Industries, Ltd. sub-agent Patent attorney Makoto Kawai (one other person) Fig.

Claims (1)

[Claims] (a) a fixed platen; (b) a toggle support disposed opposite the fixed platen; (c) a tie bar disposed between the fixed platen and the toggle support; (d (e) a crank mechanism disposed between the toggle support and the movable platen and comprising first and second arms; (f) a lever disposed at the link connecting portion between the first and second arms of the crank mechanism; (g) a lever disposed slidably on the lever and rotated by a motor to operate the lever; (h) The distance between the part where the lever slides on the third arm and the rotation center of the motor gradually becomes shorter when the mold is closed, and when the mold is opened. A mold clamping device for an electric injection molding machine, characterized in that the motor is disposed at a position that gradually becomes longer.