JPH07121540B2 - Crank type injection mechanism - Google Patents

Description

TECHNICAL FIELD The present invention relates to an injection function of an injection molding machine.

Prior art Crank type injection mechanism 1 in an injection molding machine (Fig. 2)
Basically includes a front plate 2, a rear plate 3, and a pusher plate 4 and a crank mechanism 5 between these plates.

A cylinder 6 is attached to the front surface of the front plate 2,
The screw 7 is arranged in the inside along the injection axis a. The base of the screw 7 penetrates the front plate 2 and is rotatably supported on the front surface of the pusher plate 4 by a measuring pulley 8
It is fixed to the sleeve by spline connection.

The pusher plate 4 and the rear plate 3 are connected to each other by a crank mechanism 5 by pivotally supporting an operating end b of the crank mechanism 5 on the rear surface of the pusher plate 4 and a driving end c on the front surface of the rear plate 3. , Pusher plate 4
Is moved back and forth (left and right in the figure) with respect to the rear plate 3.

The crank mechanism 5 basically connects a connecting arm 9 whose front end is the working end b and a crank arm 10 whose rear end is the drive end c to each other at their other ends to form a rotation node d. The rotation of the crank arm 10 is converted into a linear movement of the working end b.

Looking at the characteristics of thrust and speed at the operating end b of the crank mechanism 5 as described above, as shown in FIG.
Is rotated from 0 ° (top dead center, the position on the rear plate 3 side in FIG. 2 that coincides with the injection axis a) to 180 ° (bottom dead center), the thrust (a) is at top dead center, It is large near bottom dead center, and the speed (b) is largest near the middle of top dead center and bottom dead center.

Therefore, in molding a thick material (for example, a lens), it is preferable to use the operating region A having the above characteristics to obtain a large thrust in order to maintain a sufficient holding pressure higher than the injection speed.
In the molding of a thin product (master disc master), it is advantageous to use the operating region B to obtain a large injection speed in order to quickly spread the injection resin in the mold rather than the thrust.

The operation area is determined by the rotation start point (initial phase) of the crank arm 10 and its rotation range (rotation angle).

However, in the conventional crank type injection mechanism 1, since the distance e between the front plate 2 and the rear plate 3 is constant, when the operating region of the crank mechanism 5 is changed, the initial phase of the crank arm 10 changes. Or a change in stroke associated with a change in the rotation angle changes the most advanced position f of the screw 7 with respect to the cylinder 6, causing the tip of the screw 7 to collide with the cylinder 6 (usually around 1 mm for safety). Of the resin 11) formed at the tip of the cylinder 6 at the end of the measuring process.
Is increased and the amount of resin at this point exceeds the required injection amount, and the resin remaining inside deteriorates after each injection, or the fluidity becomes excessive, which adversely affects the quality of the molded product. Therefore, the operating region of the crank mechanism 5 could not be set arbitrarily.

SUMMARY OF THE INVENTION An object of the present invention is to provide a crank type injection mechanism capable of arbitrarily adjusting the operating region of the crank mechanism.

Means for Solving the Problems A front plate and a rear plate, and a pusher plate that is movable between them and can be moved back and forth.

The front plate and rear plate are connected by tie rods arranged in parallel.

The pusher plate and the rear plate are connected by a crank mechanism that moves the pusher plate back and forth.

The distance between the front plate and the rear plate can be adjusted.

And the whole can be moved back and forth with respect to the mold clamping mechanism.

Action The configuration that allows the distance between the front plate and the rear plate to be adjusted is the most advanced position f of the screw relative to the cylinder.
It is possible to arbitrarily adjust the operating region of the crank mechanism without changing the.

Embodiments FIGS. 1 and 4 show a crank type injection mechanism 1.

It has a front plate 2 and a rear plate 3, and a pusher plate 4 located between them.

The front plate 2 and the rear plate 3 are connected by two tie rods 12 arranged in parallel, and the pusher plate 4 is fitted on both sides of these tie rods 12 and is connected to the rear plate 3 by a crank mechanism 5. The rear plate 3 is movable in the front-rear direction along the injection axis a.

A cylinder 6 is attached to the front surface of the front plate 2,
The point that the base of the screw 7 located inside thereof is spline-fitted and attached to the sleeve of the measuring pulley 8 axially supported on the front surface of the pusher plate 4 is similar to the conventional case.

The crank mechanism 5 is composed of a link 13 and a speed reducer 14 and a servomotor 15 attached to the rear plate 3,
A front end of 13 is rotatably connected to an operating side pin 16 formed on a rear surface of the pusher plate 4, and a rear end thereof is rotatably connected to a drive side pin 18 provided at an eccentric position of an output shaft 17 of the speed reducer 14. Has been done.

The centers of the operation side pin 14 and the output shaft 15 are on the injection axis a in plan view, and the distance from the center of the output shaft 15 to the drive side pin 18 corresponds to the crank arm 10.

Here, the effective length of each tie rod 12 is determined by a rod head 19 that contacts the rear surface of the rear plate 3, a nut 20 and a stopper 21 that are screwed onto the front surface of the front plate 2.

The entire structure described above is such that the front plate 2 and the rear plate 3 are fitted into the left and right parallel guide bars 22 and 22, so that a mold clamping mechanism (not shown) is provided along the injection axis a. It is possible to move back and forth.

Reference numeral 23 is an injection mechanism side connection portion of the nozzle touch device.

In the injection / measuring process of the injection molding machine, the servomotor 15 is driven to operate the crank mechanism 5, and the drive side pin shaft 18 at the eccentric position of the output shaft 17 is rotated via the speed reducer 14. As a result, the pusher plate 4 moves back and forth, and the screw 7 moves back and forth with respect to the cylinder 6 at a predetermined position.

At this time, the most advanced position f of the screw 7 with respect to the cylinder 6 is determined by the operating region of the crank mechanism 5, but the electric injection molding machine sets the initial phase and rotation angle (stroke) corresponding to the required operating region. A nut 20, which is taught to the NC controller normally equipped, and then screwed to the tie rods 12, 12.
Loosen the lock nut 21, move the front plate 2 back and forth with respect to the rear plate 3, and fasten these nuts 20 and 21 again to adjust the distance e between the front plate 2 and the rear plate 3 to the above-mentioned initial phase and stroke. Accurate adjustment is made in accordance with the adjustment amount t of the most advanced position f of the screw due to the change (FIG. 5).

In the case of the embodiment, the initial phase and the rotation angle are set with respect to the output shaft 17.

As a result, even if the operating area of the crank mechanism 5 is changed,
The most advanced position of the screw 7 with respect to the cylinder 6 can always be set to the optimum position, and inconvenient situations such as collision with the cylinder 6, deterioration of resin, and excessive fluidity do not occur.

EFFECTS OF THE INVENTION In the crank type injection mechanism, an arbitrary operation region can be selected without any trouble in the operation of the mechanism and the molded product.

Since injection molding can be performed in the operating region having the most advantageous characteristics according to the target molded product, it is possible to obtain high-quality molded products for thick and thin products with one injection molding machine.

[Brief description of drawings]

FIG. 1 is a schematic plan view, FIG. 2 is a front view for explaining the mechanism, FIG. 3 is a view showing characteristic curves and operating regions, FIG. 4 is a front view, and FIG. 5 is a front view for explaining the mechanism. It is a figure. 2 ... Front plate, 3 ... Rear plate, 4 Pusher plate, 5 ... Crank mechanism, 12 ... Tie rod, 15 ... Servo motor, 20 ... Nut, 21 ... Stop nut, 22 ... Guide bar.

Claims (1)

[Claims] 1. A front plate and a rear plate, and a pusher plate positioned between them, which is movable in the front-rear direction, and the front plate and the rear plate are connected by a plurality of tie rods arranged in parallel. The distance between the plates is adjustable, the pusher plate and the rear plate are connected by a crank mechanism that moves the pusher plate back and forth, and the whole is movable back and forth with respect to the mold clamping mechanism. Crank type injection mechanism.