JP2000263610A - Mold clamping device for vertical injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exclude an influence by an own weight at an overall stroke by operating a mold clamping device in a direction for diminishing its own weight at the overall stroke of opening and closing a mold by a toggle linkage by using a toggle link type mold clamping device. SOLUTION: When a servo motor 20 is driven to rotate a ball screw shaft 15 by a belt 23, an engaging ball nut 16 is moved down. Since a toggle support 6 is simultaneously lowered, a toggle linkage 7 is extended down at a pin 10 as a fulcrum through a crosshead 12 and an operating link 13. A lower link 9 and an upper link 8 of the linkage 7 tend to extend by a power of a movable unit of the mold clamping device. Then, a weight 4 is operated in a direction for bending the links 9, 8 through a lever 11, and operated at the support 6 in a direction for raising it to cancel the gravity of the device. When a spring 5 is used together, the spring 5 becomes a reaction force to a rising of the weight, thereby simplifying its constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toggle link type mold clamping device for a vertical injection molding machine. In particular, the present invention relates to a mold clamping device having a mechanism for canceling its own weight.

[0002]

2. Description of the Related Art In a mold clamping device provided with a toggle mechanism in a vertical position, a spring member is used to offset the gravity of the toggle mechanism by using a spring member to solve the difficulty of mold clamping control caused by the gravity of the toggle mechanism. Japanese Patent Application Laid-Open No. 10-11396
No. 4 (hereinafter referred to as known technology). This known technique will be described briefly below.

In FIG. 2, reference numeral 31 denotes a mold table fixed horizontally on the upper surface of a machine base 32, and reference numeral 33 denotes a double link toggle mechanism provided vertically inside the machine base 32 with the mold table 31 side as a reaction force. At the four corners of a pressure receiving plate 36 which is pin-connected to the lower portions of upper and lower links 34 and 35 which expand and contract vertically, a traction shaft 37 for mold clamping is provided movably up and down through the mold table 31. The lower ends are connected. A movable plate 38 is connected to the upper end of the towing shafts 37, 37 horizontally with respect to the mold table 31.

Although not shown in the drawing, an injection device having a heating cylinder provided with a nozzle at the tip is directed vertically above the movable platen 38. In addition, molds 39a, 3 for injection molding are provided on opposing surfaces of the mold placing plate 31 and the movable plate 38.
9b are mounted separately, and the mold 39 is mounted on the movable platen 3
8 is opened and closed by raising and lowering.

The toggle mechanism 33 includes an upper link 34 and a lower link 35 rotatably connected together with an operating link 41 by a pivot pin 40. The upper link 34 and the lower link 35 form a pair. The pair of lower links 35 are connected to the pressure receiving plate 36 with pins.

In the center of the toggle mechanism 33, a ball screw shaft 44 screwed with a ball nut 43 provided in the link operating member 42 is rotatably held by a bearing member 41a fitted and fixed to the pressure receiving plate 36. Have been. The actuating member 42 and the actuating link 41 rotatably connect side lugs by pins 47.

A pulley 46 for rotational driving is attached to a shaft end of the ball screw shaft 44 protruding downward from a bearing member 45, and the rotational force of an electric servomotor (not shown) is driven on the pulley 46. The ball screw shaft 44 rotates, and the rotation causes the operating member 42 to move in the axial direction to pull or press the portion of the pivot pin 40 to move the upper and lower links 34 and 35 vertically. Expand and contract.

Reference numeral 48 denotes a gravity canceling device mounted on both sides of the pressure receiving plate 36, and bearings 49 screwed to the side surfaces of the pressure receiving plate 36.
And a support rod 50 supported vertically by a bearing 49, a grounding member 52 attached to the lower end of the support rod 50 by a bolt 51 so as to be adjustable in height, and a bearing 49 and a flange 53 at the lower end of the rod. The support rod 50 is provided with a coil spring 54 disposed therebetween.
0a is provided.

The height of the grounding member 52 is adjusted so that the grounding member 52 comes into contact with the frame 55 at the bottom of the machine base before the toggle mechanism 33 is fully extended. The mold 39a is a mold 39b on the mold table 31 side.
Is closed to the vicinity of the frame 55 and is grounded. The spring 54 receives a load by grounding and resists the gravity acting on the pressure receiving plate 36. As a result, the upward force acting as the reaction force of gravity is removed from the ball nut 43 in the link operating member 42 screwed with the ball screw shaft 44, and the load on the ball screw shaft 44 is also eliminated. Therefore, the rotational force other than the set value of the ball screw shaft 44 due to the load is removed, and the dies 39a and 39b come into contact with each other at a low pressure,
Mold clamping control near the completion of mold closing can also be easily performed by the electric servomotor.

Due to the offset of gravity by the spring 54, even when the toggle mechanism 33 is provided vertically, a change in the rate of force and a change in speed due to the operating position unique to the toggle can be obtained.
In addition, since control from mold closing to mold clamping can be performed without being affected by gravity, even when an electric servomotor is used as a drive source, the mold can be protected during mold clamping. That is.

However, in this known technique, the lower pressure receiving plate 3
Although a gravity canceling mechanism by a spring 54 is provided in the vicinity of the lower limit of 6, the gravity canceling is not possible in the entire stroke of opening and closing the mold.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a vertical injection molding machine such as the above-mentioned prior art which can eliminate the influence of the weight of the mold clamping device by its own weight in all strokes. I do.

[0013]

Means for Solving the Problems (1) In an electric vertical injection molding machine using a toggle link type mold clamping device, the entire length of the mold opening / closing stroke by the toggle link mechanism is opposed to the weight of the mold clamping device. A self-weight canceling mechanism that acts in the direction of reducing the weight is provided. (2) The self-weight canceling mechanism of the above (1) is provided with a lever having one end connected via a pin to an upper link pin-connected to the lower part of the lower platen or a lower link pin-connected to the upper part of the toggle support. The other end of the lever is located between the lower platen and the toggle support, and is pin-connected to a weight that is vertically movably inserted into a tie bar connecting the upper platen and the toggle support. (3) In the configuration of (2), one end of the lever is connected to a pin connecting the upper and lower links. (4) In the configuration of (3), a spring is interposed between the lower platen and the weight.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. FIG.
Where 1 is the upper platen, 2 is supported on the upper platen 1,
The tie bar penetrates the lower platen 3. Reference numeral 4 denotes a weight which the tie bar 2 penetrates and is guided by the tie bar 2 to move up and down. A spring 5 is mounted between the weight 4 and the lower platen 3. Reference numeral 6 denotes a toggle support, which is fixed to the lower end of the tie bar 2. The toggle link mechanism 7 has the following structure. An upper link 8 pin-connected to a protrusion provided at the lower portion of the lower platen 3 and a lower link 9 pin-connected to a protrusion provided at an upper portion of the toggle support 6 are connected by pins 10. Further, between the upper link 8 and the lower link 9, another lever 11 having one end connected to a pin 10 for connecting the tip of the upper link 8 and the lower link 9 is pin-connected. The other end of the lever 11 is the weight 4
Is pin-connected.

The crosshead 1 is located at an intermediate position of the lower link 9.
An actuation link 13 connected to the end of the second is pinned. A ball screw shaft 15 is provided at an intermediate position of the crosshead 12.
Is supported via a bearing 14. The ball screw shaft 15 is screwed with a ball nut 16 attached to the toggle support 6, and the lower end thereof is provided on a support 17 provided on a base 17.
A pulley 19 rotatably installed at 8 is spline-connected to a spline provided therein so as to be vertically slidable.

Reference numeral 20 denotes a servomotor supported by a frame 21 for driving a pulley 19 provided with a spline portion therein through a belt 23 wound around a pulley 22 driven by the servomotor.

When the mold is closed, the servomotor 20 is driven to rotate the ball screw shaft 15 by the belt 23, and the ball nut 16 screwed with the shaft is lowered. Then, the toggle support 6 is simultaneously lowered, so that the toggle link mechanism 7 extends downward with the pin 10 as a fulcrum via the crosshead 12 and the operating link 13. At this time, as shown in FIG. 1B, the lower link 9 and the upper link 8 of the toggle link mechanism 7 are about to be extended (linearly) by the gravity of the movable portion of the mold clamping device. At this time, the weight 4 acts in the direction of bending the lower link 9 and the upper link 8 via the lever 11. This works in a direction to raise the toggle support 6. As a result, it serves to offset the gravity of the mold clamping device. Further, at this time, by using the spring 5 together, the spring 5 acts as a reaction force against the rise of the weight 4, so that the weight 4 can be reduced accordingly and the configuration can be made compact. Although one end of the lever 11 is connected to the pin 10,
The pin may be directly connected to the lower link 9 or the upper link 8.

[0018]

In the entire stroke of opening and closing the mold, another lever is provided on the upper link or lower link of the toggle link mechanism via a pin, and the other end of this lever is moved up and down by being guided by a tie bar. With the connection, the own weight of the mold clamping device can be offset. Further, by mounting the spring 5 between the weight 4 and the platen, the size of the weight 4 can be reduced and the configuration can be made compact. Thus, up and down opening and closing can be performed smoothly and safely over the entire stroke when the mold is opened and closed with a simpler configuration than in the prior art.

[Brief description of the drawings]

1A and 1B are schematic front views of a mold clamping device provided with a self-weight canceling mechanism according to the present invention, wherein FIG. 1A shows a mold opened, and FIG. 1B shows a mold fully closed.

FIGS. 2A and 2B show a mold clamping device provided with a self-weight canceling device of a known invention, wherein FIG. 2A shows a mold closing time and FIG. 2B shows a mold opening time.

[Explanation of symbols]

1 upper platen 2 tie bar 3 lower platen 4 weight 5 spring 6 toggle support 7 toggle link mechanism 8 upper link 9 lower link 10 pin 11 lever 12 crosshead 13 operating link 14 bearing 15 ball screw shaft 16 ball nut 17 base 18 support 19 Pulley 20 Servo motor 21 Frame 22 Pulley 23 Belt

Claims (4)

[Claims] In an electric vertical injection molding machine using a toggle link type mold clamping device, the toggle link mechanism acts in the direction of reducing the weight of the mold clamping device against its own weight in all strokes of opening and closing the mold. A mold clamping device for a vertical injection molding machine, wherein a self-weight offset mechanism is provided. 2. A self-weight canceling mechanism is provided with a lever having one end connected via a pin to an upper link pin-connected to a lower portion of a lower platen or a lower link pin-connected to an upper portion of a toggle support. 2. The vertical injection device according to claim 1, wherein the end is located between the lower platen and the toggle support, and is pin-connected to a weight that is vertically movably inserted into a tie bar connecting the upper platen and the toggle support. Mold clamping device for molding machines. 3. An end of the lever is connected to a pin connecting an upper link and a lower link.
A mold clamping device for the vertical injection molding machine as described in the above. 4. The mold clamping device for a vertical injection molding machine according to claim 3, wherein a spring is interposed between the lower platen and the weight.