JPH0813489B2 - Clamping device for injection molding machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mold clamping device of an injection molding machine that enables mold clamping with a small and small output motor.

(Prior Art) FIG. 2 shows a mold clamping device of a conventional electric injection molding machine.
1 is a motor and 2 is a coupling. The rotation of the motor 1 is transmitted to the ball screw 3 connected by the coupling 2. When the ball screw 3 rotates, the ball screw nut 4 advances. Then, the rod 5 advances, the thrust is generated by the link mechanism 6, the movable platen 8 advances, and mold clamping is performed.

2A shows the mold open state, FIG. 2B shows the mold closing process, and FIG. 2C shows the mold closing state.

Now, in the electric injection molding machine using the motor as described above, the mold clamping device is divided into two types, that is, when it is driven at high speed and low torque and when it is driven at low speed and high torque, considering from the side of the motor.
There are two cases in one cycle. In order to satisfy both of these, a high-speed, high-torque, high-power motor is required.

(Problems to be Solved by the Invention) Since it is necessary to satisfy both the case where the mold clamping motor of the electric injection molding machine is driven at low speed and high torque and the case where it is driven at high speed and low torque, high speed and high torque It is intended to solve the problem of requiring a large output motor.
That is, it is an object of the present invention to provide a mold clamping mechanism that improves the conventional mold clamping mechanism and enables mold clamping with high torque even with a small and small output motor.

(Means for solving the problem) The rotation of the motor is converted into a linear movement via a ball screw,
In a mold clamping device in which the linear movement is transmitted to a link mechanism via a rod and the movable platen is moved from the link mechanism, the linear movement of the ball screw is also transmitted to a piston that reciprocates in the cylinder and is generated in the cylinder. 2 hydraulic pressure
Of two pipes, one of which is connected to one cylinder via a switching valve and the other of which is connected to a linear cylinder by a pipe. When low speed and high torque are required, the switching valve is switched and driven by two cylinders. I decided to do it.

(Example) It demonstrates based on FIG. 1 is a motor, 2 is a coupling, 3 is a ball screw, and 4 is a ball screw nut.
6 is a link mechanism, 7 is a fixed platen, 8 is a movable platen, and 9 is a tie rod. The above is exactly the same as the second one.

A cylinder rod 10 is connected to the ball screw nut 4. Reference numeral 11 is a cylinder, and a piston 11a attached to the tip of the cylinder rod 10 moves therein. 1
Reference numeral 2 is an electromagnetic switching valve, 13 and 14 are cylinders, and each rod of these cylinders is connected to one rod 5 and is connected to the link mechanism 6.

The piston-side oil chamber A of the cylinder 11 is connected to the cylinder 14 by a pipe a, and is connected to the cylinder 13 by a pipe b via an electromagnetic switching valve 12. The rod side oil chamber B of the cylinder 11 is connected to the electromagnetic switching valve 12 by a pipe c.
T is a tank connected to the pipe c.

(Operation) When the motor 1 is rotated from the mold open state shown in FIG. 2 and the ball screw nut 4 moves forward, pressure is generated in the cylinder 11. In the initial stage of mold closing, thrust is not required and the electromagnetic switching valve 12 is kept in the state shown in the figure in order to increase the closing speed. Then, the hydraulic pressure generated in the cylinder 11 is
At 14, it is converted into the thrust of the rod 5, and the movable platen 8 is moved forward. When the movable platen 8 comes close to the final position, the state is detected by a limit switch or the like, and the electromagnetic switching valve 12 is automatically switched. Then, the hydraulic pressure generated in the cylinder 11 is supplied to the cylinders 13 and 14. At this time, the forward speed of the rod 5 is halved, but on the contrary, the thrust is doubled and a large mold clamping force is obtained.

Although the two cylinders 13 and 14 have been described in the above embodiments, it is needless to say that the same can be applied to the case of three or more cylinders. The same effect can be obtained even if the pressure receiving area is changed by using the composite cylinder.

Further, the driving mechanism of the present invention can be applied not only to the injection molding machine but also to driving a plunger driving cylinder of an IC sealing press, for example.

(Effect) High-speed, low-thrust characteristics are obtained by converting the rotational torque of the motor into hydraulic pressure once through the ball screw, enabling it to be driven through multiple cylinders, and changing the number of cylinders that generate thrust by switching the switching valve. And, low speed and high thrust characteristics can be switched. As a result, 1) In the conventional method, a large speed thrust was required, but by inserting a hydraulic mechanism in the middle, the speed and the conversion ratio to thrust can be changed, and a small motor can be made. It was

2) Since there is a hydraulic mechanism in the middle, the elasticity of the oil can reduce the shock during mold clamping.

3) Since the arrangement of the motor and the ball screw can be arbitrarily selected (for example, in the base of the molding machine), the total length of the molding machine can be shortened and the size can be reduced.

[Brief description of drawings]

 FIG. 1 shows a mold clamping device according to the present invention. FIG. 2 shows a conventional mold clamping device. In the figure: 1 ... Motor, 2 ... Coupling 3 ... Ball screw, 4 ... Ball screw nut 5 ... Rod ... 6 ... Link mechanism 7 ... Fixed platen, 8 ... Movable platen 9 ... Tie rod, 10 …… Cylinder rod 11 …… Cylinder, 11a …… Piston 12 …… Electromagnetic switching valve, 13 …… Cylinder 14 …… Cylinder

Claims (1)

[Claims] 1. A mold clamping apparatus for converting rotation of a motor into linear movement via a ball screw, transmitting the linear movement to a link mechanism via a rod, and moving a movable platen from the link mechanism, wherein the ball screw is used. The linear movement of the cylinder is transmitted to a piston that reciprocates in the cylinder, and the hydraulic pressure generated in the cylinder is branched into two pipes, one of which is connected to one cylinder via a switching valve and the other of which is directly connected to the cylinder. A mold clamping device for an injection molding machine, characterized in that the switching valve is switched and driven by two cylinders when low speed and high torque are required.