JPH085786Y2 - Mold clamping device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a mold clamping device that reliably and efficiently performs mold opening / closing operations in an injection molding machine.

(Prior Art) Conventionally, as a mold clamping device in an injection molding machine of a medium size or more (200 tons or more as a guide), a hydraulic type is adopted in order to increase the force to be generated. However, the ratio of the force required to open and close the mold and the force required to clamp the mold is approximately 1:
Since it is as large as 10: 1: 20, various methods have been devised to expand the power.

A conventional mold clamping device will be described with reference to FIGS. 4 and 5. This is a composite mold clamping device called a hydromechanical system. FIG. 4 shows a sequence of mold opening / closing and mold clamping operation of an injection molding machine and its operation. FIG. 5 shows the outline of the structure and hydraulic circuit of the compound mold clamping device.

From the mold closing acceleration to the mold closing low speed, that is, in the stages 1 to 4 in FIG. 4, the mold opening / closing cylinder 4 provided on the fixed platen 1 is supplied with the pressure oil from the hydraulic source 14 from the port A of the solenoid valve 11. The movable platen 2 is moved to the fixed platen 1 side in the order of acceleration → high speed → deceleration → low speed. Further, the mold clamping pressure increasing and mold clamping holding, that is, the operations of the stages 5 and 6 in FIG. 4 are performed as follows. That is, when the movable mold 7 and the fixed mold 7a come into close contact with each other, the screw groove 3a formed in the tip portion of the tie bar 3 is inserted into the center hole of the mold clamping ram 5a slidably mounted on the movable platen 2. hand,
The engagement position with the half nut 6 is reached. Then, by supplying pressure oil from the hydraulic pressure source 16 to the cylinder 6a from the A port of the solenoid valve 13, the half nut 6 meshes with the thread groove portion 3a of the tie bar 3.

Next, pressure oil from the hydraulic pressure source 15 is supplied to the mold clamping cylinder 5 from the B port of the solenoid valve 12, the mold clamping ram 5a moves to the left in the drawing, and a force is applied to the half nut 6. At this point, the tie bar 3 and the half nut 6 are firmly meshed with each other, and the tie bar 3 is pulled with a strong force to generate a mold clamping force. Further, the screw groove portion 3a has a shape as shown in FIG.
It has a shape that transmits force in one direction (mold clamping side), and the mold clamping ram 5a only pushes the half nut 6 in the mold clamping direction.

Further, in the stage 7 of FIG. 4 which performs the step-down operation, the pressure oil supplied to the mold clamping cylinder 5 is released to the tank, and the pressure oil is supplied from the port B of the solenoid valve 13 to the cylinder 6a, so that the half nut 6 Open to release the mesh with the thread groove 3a of the tie bar 3. Also, the stage 8 of the releasing operation is
This stage is for separating the molded product from the fixed mold 7a. This stage has a low speed and speed stability, but requires a relatively large force (7% to 10% of the mold clamping force). The operation from the mold release to the mold opening stop, that is, the stage 8
12 to 12 are performed by supplying pressure oil to the mold opening / closing cylinder 4 from the B port of the solenoid valve 11.

(Problems to be solved by the invention) However, the mold releasing operation of the conventional mold clamping device requires a very large force, and since this is performed by the mold opening / closing cylinder, a large mold opening / closing cylinder is required. There was a problem that a large capacity hydraulic pump was required. Further, in order to avoid this, a pressure booster was sometimes used.

The present invention has been proposed to solve the above conventional problems.

(Means for Solving the Problem) Therefore, the present invention provides a fixed plate for holding a fixed mold, a movable plate for holding a movable mold, a means for moving the movable plate forward and backward with respect to the fixed plate, The movable plate approaches the fixed plate,
After the fixed mold and the moving mold are closed, the tie bar is fixed to the fixed platen or the movable platen and fixed to the fixed platen or the movable platen, and the tie bar is fixed to the movable platen or the fixed platen. In the mold clamping device, which is performed by a half nut or a half ring that opens and closes in a direction substantially perpendicular to the tie bar, a ball screw driven by an electric motor is used as a means for moving the movable plate forward and backward with respect to the fixed plate. A mold clamping cylinder is provided as a means for generating a force, and a protrusion and a collar are provided so that the mold clamping ram inserted into the cylinder and the half nut cannot move relative to each other in the front-rear direction, and the groove portion of the tie bar and the half nut. Has a parallel groove,
There is a slight gap between the protrusion and the collar and between the parallel grooves when the half nut is closed, and this is a means for solving the problem.

(Operation) By performing the mold release operation by the mold clamping cylinder, it is possible to easily generate a large force, and to reduce the capacity of the parts that perform the mold opening / closing operation such as the electric servomotor and the ball screw, and to reduce the size, Cost reduction can be achieved.

(Embodiment) The present invention will be described below with reference to embodiments of the drawings.
1 to 3 show an embodiment of the present invention. The invention is based on the sequence diagram of FIG.
The step-down operation is performed by hydraulic pressure, and the structure and operation are exactly the same as those in the conventional example, and therefore the description thereof will be omitted.

Now, in the figure, a ball screw 21 is rotatably attached to a fixed platen 1 through a bearing 23, and a nut (for ball screw) 22 is fixed to a movable platen 2,
The movable platen 2 can be moved forward and backward by the rotation of the ball screw 21. In addition, the ball screw 21 is
1. It is connected via a belt 40 to a pulley 36 connected to the output shaft of the electric servomotor 30.

2 and 3 are detailed views of the half nut and the mold clamping ram portion. In the figure, half nut 6 and tie bar 3
The parallel groove portions are provided with sawtooth-shaped parallel grooves such as the groove portions 6b and 3b so that the half nuts are both restrained on the forward and backward sides in a state where a slight gap is left between the parallel groove portions. Further, the half nut 6 and the mold clamping ram 5a are separable from each other as shown by X so that the half nut 6 is restrained with a slight clearance when the half nut 6 is engaged with the tie bar 3. Provide a locking part.

Next, the operation will be described. In the conventional mold closing acceleration to low speed in the sequence diagram shown in FIG. 4, that is, in the stages 1 to 4, the output of the electric servomotor 30 is transmitted to the pulley 36 and the ball screw is passed through the belt 40. The pulley 41 fixed to 21 is driven. The rotary motion of the ball screw 21 is converted into a linear motion by the nut 22 fixed to the movable platen 2 and moves the movable platen 2 in the mold closing direction. Further, the servo motor 30 is configured with a position closed loop system so as to move in a required set pattern. At this time, the mold clamping ram 5a is supplied with pressure oil in the oil chamber B and is in the lower half state of FIG. 2, and the relative position between the movable platen 2 and the mold clamping ram 5a is fixed.

Next, the mold clamping pressure up to holding, that is, the stages 5 and 6 in FIG.
This is done as follows. With respect to the position where the movable mold 7 and the fixed mold 7a are in close contact, the required mold release stroke plus a slight amount, and the position where the half nut 6 meshes with the tie bar 3 is calculated in advance, and this position can be moved. Set the target position for the board 2 and move the board 2 to this position by the servo motor 30.
To stop. At the same time, the half nut 6 is closed by the hydraulic cylinder 6a, and the tie bar 3 and the half nut 6 are closed.
The parallel grooves 3b and 6b provided on the above-mentioned mesh with each other, and the mold clamping ram 5a and the collar 6c provided on the half nut 6 mesh with each other.

Next, pressure oil is supplied to the oil chamber A of the mold clamping cylinder 5 to perform the mold clamping pressure increasing and holding operations. Further, since the mold clamping ram 5a pushes the half nut 6 coupled to the tie bar 3 in the forward direction, the movable platen 2 moves in the mold closing direction, the mold is brought into close contact, and the oil pressure in the oil chamber A rises. Then, the tie bar 3 is pulled with a strong force to generate a mold clamping force (this is shown in the upper half state of FIG. 2).

Further, the step-up, that is, the operation of the stage 7 is the same as that of the conventional example, and the description thereof will be omitted.

Next, the mold release, that is, the stage 8 is performed as follows. That is, in the upper half state of FIG. 2, the pressure oil is supplied to the oil chamber B, and the oil chamber A is opened to the tank (not shown).
Further, the mold clamping ram 5a moves to the right and catches on the collar 6c of the locking portion, and tries to move the half nut 6 to the retracted side. Then, when the half nut 6 and the parallel groove portions 3b and 6b of the tie bar 3 come into contact with each other, the force acts as a force for moving the movable platen 2 to the mold opening side, and a great releasing force is generated. Then, the mold clamping ram 5a moves until it comes into contact with the stopper 2a.

Next, the mold opening acceleration-stop, that is, the stages 9-12, the mold closing acceleration-low speed, that is, the same as the stages 1-4, the servo motor
The ball screw 21 is driven by 30. At this time, pressure oil is being supplied to the oil chamber B, and the relative positions of the mold clamping ram 5a and the movable platen 2 are fixed. In addition, the mold opening and closing operation,
The hydraulic cylinder may be used as in the conventional example, but in this case the positioning accuracy becomes poor, so a positioning device for determining the relative positions of the half nut 6, the mold clamping ram 5a and the movable platen 2 is required.

(Effects of the Invention) The present invention is configured as described in detail above, and since the releasing operation is also performed by the mold clamping cylinder, the capacity of parts such as the electric servomotor and the ball screw can be greatly reduced.

[Brief description of drawings]

FIG. 1 is a plan sectional view of a mold clamping device according to an embodiment of the present invention,
FIG. 2 is a detailed sectional view of a half nut according to an embodiment of the present invention, in which the upper and lower portions of the mold clamping ram are in different operating states, and FIG. 3 is a half nut and a mold in which the operating state is different from that of FIG. FIG. 4 is a sectional view showing only the upper half of the clamping ram portion, FIG. 4 is a sequence diagram showing a mold clamping operation of a conventional injection molding machine, and FIG. 5 is a plan sectional view showing a conventional mold clamping device with a hydraulic circuit. The figure is a cross-sectional view showing a coupled state of the half nut and the tie bar. Description of main parts of the figure 1 …… Fixed plate 2 …… Movable plate 3 …… Tie bar 3b …… Parallel groove 5 …… Clamping cylinder 5a …… Clamping ram 6 …… Half nut 6b …… Parallel groove 30 …… Servomotor

Claims (1)

[Scope of utility model registration request] 1. A fixed plate for holding a fixed mold, a movable plate for holding a movable mold, means for moving the movable plate forward and backward with respect to the fixed plate, and the movable plate approaching and fixed to the fixed plate. After the mold and the moving mold are closed, the tie bar is fixed to the fixed platen or the movable platen to perform mold clamping, and the tie bar is fixed to the movable platen or the fixed platen. Joining and fixing is performed by a half nut or half ring that opens and closes in a direction substantially perpendicular to the tie bar,
A ball screw driven by an electric motor is used as a means for moving the movable platen forward and backward with respect to the fixed platen, and a mold clamping cylinder is provided as a means for generating a mold releasing force, and the mold clamping ram and the half nut inserted through the cylinder. Is provided with a protrusion and a collar so that the front and rear cannot be moved relative to each other, a parallel groove is provided in the groove portion of the tie bar and the half nut, and the protrusion and the collar and the parallel groove between the half nut are closed. A mold clamping device characterized by having a slight gap.