JPH03189122A - Crank injection mechanism - Google Patents

Abstract

PURPOSE:To regulate arbitrarily an actuation sphere of a crank mechanism without changing the foremost position of a screw in relation to a cylinder, by making a distance between a front plate and rear plate regulatable. CONSTITUTION:A crank mechanism 5 is actuated by driving of a servomotor 15 and a driving side pin shaft 18, which is in an eccentric position of an output shaft 17 of the crank mechanism, is turned through a reduction gear 14, in an injection and measuring processes of an injection molding machine. With this construction, a screw 7 is moved longitudinally in relation to a cylinder in a fixed position by moving a pressure plate 4 longitudinally. In this instance, though the most advanced position (f) of the screw 7 in relation to the cylinder 6 is decided with an actuation sphere of the crank mechanism 5, the initial phase and turning angle (stroke) corresponding to the necessary actuation sphere are established in relation to the output shaft 17. With this construction, even if the actuation sphere of the crank mechanism 5 is changed, the most advanced position of the screw 7 in relation to the cylinder 6 can be established at the optimum position always, and the improper situation such as collision of the screw 7 with the cylinder 6 or a change of properties and excessive flowability of the resin is not generated.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an injection mechanism for an injection molding machine.

A crank-type injection mechanism 1 (FIG. 2) in a conventional injection molding machine 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 of the front plate 2,
A screw 7 is arranged inside it along the injection axis a. The base of the screw 7 passes through the front plate 2 and is connected to a measuring pulley 8 which is pivotally supported on the front surface of the pusher plate 4.
It is splined and fixed to the sleeve.

The pusher plate 4 and the rear plate 3 are connected to each other by a crank mechanism 5, with an operating end C of the crank mechanism 5 rotatably supported on the rear surface of the pusher plate 4, and a drive end C rotatably supported on the front surface of the rear plate 3. , pusher plate 4
is configured to be moved back and forth (to the left and right in the figure) with respect to the rear plate 3.

The crank mechanism 5 basically consists of a connecting arm 9 whose front end is the above-mentioned operating end, and a crank arm 10 whose rear end is the above-mentioned driving end C, which are connected at their other ends to form a rotational node d. The rotation of the crank arm 10 is converted into a linear motion of the working end.

Looking at the characteristics of thrust and speed at the working end of the crank mechanism 5, as shown in Fig. 3, the crank arm 1
0 is 0° (Top dead center, in Figure 2, rear plate 3
During the rotation from the position (which coincides with the injection axis a) to 180° (bottom dead center), the thrust (a) is large near the top dead center and bottom dead center, and the speed (b) is large near the top dead center and the bottom dead center. It is largest near the middle of bottom dead center.

Therefore, when molding a thick material (for example, a lens), it is preferable to use the operating region A of the above characteristics to obtain a thrust force greater than the injection speed in order to maintain sufficient holding pressure.
In the molding of a thin product (cassette disk master), it is advantageous to use the operating region B to obtain a higher injection speed than the thrust force in order to spread the injected resin more quickly within the mold.

Note that the operating range 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, the distance e between the front plate 2 and the rear plate 3 is constant, so when the operating range of the crank mechanism 5 is changed, the initial phase of the crank arm 10 is changed. Or, due to a change in the stroke due to a change in the rotation angle, the most forward position f of the screw 7 relative to the cylinder 6 changes, and the tip of the screw 7 collides with the cylinder 6 (normally, for safety reasons, it is The resin pool 11 formed at the tip of the cylinder 6 at the end of the metering process expands and the amount of resin at this point exceeds the required injection amount, causing the resin remaining inside to change quality with each injection. or
The operating range of the crank mechanism 5 could not be arbitrarily set depending on the molded product because the fluidity would become excessive and adversely affect the quality of the molded product.

Problems to be Solved by the Invention An object of the present invention is to provide a crank-type injection mechanism in which the operating range of the crank mechanism can be arbitrarily adjusted.

Means for Solving the Problems The present invention has a front plate, a rear plate, and a pusher plate located between them and movable back and forth.

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

The pusher plate and 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.

The whole can be moved back and forth relative to the mold clamping mechanism.

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

Example 1 and 4 show a crank type injection mechanism 1. FIG.

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

The front plate 2 and rear plate 3 are connected by two tie rods 12 arranged in parallel, and the pusher plate 4 is fitted on both sides into these tie openings/rods 12.
A crank mechanism 5 connected between the rear plate 3 and the rear plate 3 is capable of moving forward and backward along the injection axis a with respect to the rear plate 3.

A cylinder 6 is attached to the front of the front plate 2,
The base of the screw 7 located inside the pusher plate 4 is spline-fitted to the sleeve of a metering pulley 8 pivotally supported on the front surface of the pusher plate 4, as in the conventional case.

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

The centers of the operating 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 driving 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, and a nut 20 and a locking nut 21 screwed onto the front surface of the front plate 2. .

The entire configuration described above consists of the front plate 2 and the rear plate 3 having two parallel guide bars 22, 22 on the left and right.
By being fitted into the mold, it can be moved back and forth with respect to the mold clamping mechanism (not shown) along the injection axis a.

Reference numeral 23 is a connecting portion of the nozzle touch device on the injection mechanism side.

In the injection/metering process of the injection molding machine, the servo motor 15 is driven to operate the crank mechanism 5, and the drive side pin shaft 18 at an eccentric position of the output shaft 17 is rotated via the reduction gear 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 relative to the cylinder 6 is determined by the operating range of the crank mechanism 5, but the electric injection molding machine can adjust the initial phase and rotation angle (stroke) corresponding to the required operating range. Then, the nuts 20 and locking nuts 21 screwed onto the tie rods 12.12 are loosened, the front plate 2 is moved back and forth with respect to the rear plate 3, and the nuts 1-20.21 are again tightened. and accurately adjust the distance e between the front plate 2 and the rear plate 3 in accordance with the adjustment amount t of the screw most forward position f due to the change in the initial phase and stroke (Fig. 5). ).

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

As a result, even if the operating range 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 at the optimum position, and disadvantageous situations such as collision with the cylinder 6, deterioration of the resin, excessive fluidity, etc. do not occur.

Effects of the Invention In the crank-type injection mechanism, any operating range can be selected without causing any problems to the operation of the mechanism or the molded product.

Since injection molding can be carried out in the operating range with the most advantageous characteristics depending on the intended molded product, high-quality molded products can be obtained for both thick and thin products using a single injection molding machine.

[Brief explanation of drawings]

Figure 1 is a schematic plan view, Figure 2 is a front view explaining the mechanism, Figure 3 is a diagram showing characteristic curves and operating areas, Figure 4 is a front view, and Figure 5 is a front view explaining the mechanism. It is a diagram. 2...Front plate, 3...Rear plate, 4
...Pusher plate, 5...Crank mechanism, 1
2... Tie rod, 15... Servo motor, 20...
... Nut, 21... Locking nut, 22... Gaito Noku - Procedural amendment (method) % formula % Display of case 1999 Patent Application No. 327396 2゜Name of invention Crank type injection mechanism 3゜Amendment Relationship with cases involving persons who commit

Claims (1)

[Claims] It has a front plate, a rear plate, and a pusher plate located between them that can move back and forth.
The front plate and rear plate are connected by multiple parallel tie rods, and the distance between both plates is adjustable, and the pusher plate and rear plate are connected by a crank mechanism that moves the pusher plate back and forth. Moreover, the crank type injection mechanism is characterized in that the entire part can be moved back and forth relative to the mold clamping mechanism.