JP2597921B2 - Injection section of electric injection molding machine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection section of an electric injection molding machine, and more particularly to an injection section in which a movable plate is moved back and forth through a crank mechanism.

Conventional technologyElectric injection molding machines are equipped with an NC control device, mold clamping and mold opening, and use a servomotor for each drive of injection, weighing or ejection, precisely controlling the injection molding process,
Accurate molded products can be obtained under clean conditions without oil stains.

On the other hand, since the movement of each part in the injection molding process is almost linear reciprocation, the electric injection molding machine has a mechanism for converting the rotation of the servo motor into a linear movement.

Looking at this for the injection section, the rotation of the injection servomotor is converted to linear motion via a ball screw / nut mechanism, and the movable plate is moved forward. A large number of various parts are required, such as a ball screw nut and belts and gears for transmitting the rotation of the servomotor to the ball screw nut or the ball screw. In addition, since the transmission is performed by the belt, it is necessary to periodically check the belt tension.

Further, it is difficult to obtain a quick reciprocating linear motion with a ball screw / nut mechanism.

SUMMARY OF THE INVENTION An object of the present invention is to provide an injection unit in an electric injection molding machine which has a small number of parts, has a sufficient stroke, and can quickly move an injection / metering screw back and forth. And

Means for Solving the Problems A movable plate having an injection / metering screw is provided between a front plate and a rear plate so as to be movable back and forth along an injection axis.

The movable plate and the rear plate are connected by a double flank mechanism.

The double crank mechanism includes a sliding body that moves back and forth along the injection axis, a crank drive mechanism driven by an injection servomotor, and a pair of crank links including a first link and a second link.

One end of a pair of first links in the crank link is fixed to the output shaft of the crank drive mechanism with a phase difference of 180 °, and one end of a second link is rotatably connected to each other end,
The other end of one second link is connected to the rear plate, and the other
The other end of the link is rotatably connected to the movable plate.

Operation When the injection servomotor is driven, the movable plate is moved forward with respect to the front plate via the pair of crank links, and the resin is injected by the injection / metering screw mounted on the movable plate.

At this time, the sliding body to which the injection servomotor is attached moves in the same direction with a half stroke of the movable plate.

The movable plate retreats when the injection / metering screw is pushed back by the resin pressure in the metering process.

Embodiment FIGS. 1 and 2 schematically show an injection section 1 of an electric injection molding machine, and a front plate 3 is mounted on an extruder base 2.
And a rear plate 4 are fixed at an interval in the front-rear direction, and a movable plate 5 is mounted between the two plates 3 and 4 so as to be movable in the front-rear direction on a tie rod 6 connecting the two plates 3 and 4 to each other.

The movable plate 5 has a front surface on which the base of the injection / metering screw 7 is only allowed to rotate and is supported by a shaft. The movable plate 5 is provided with a metering servomotor (not shown) for rotationally driving the base.
The screw 7 is inserted into a cylinder assembly 8 fixed to the front surface of the front plate 3 and moves back and forth.

The movable plate 5 and the rear plate 4 are connected by a double crank mechanism 9.

The double crank mechanism 9 is mounted on the tie rod 6 and is capable of moving back and forth along an injection axis a (a line in the front and rear direction coinciding with the axis of the injection / metering screw 7).
And a crank drive mechanism 12 attached thereto and driven by an injection servomotor 11, and first links 13a and 13b and a second
A pair of first links 13a and 13b of the crank links 15 and 16 are connected to the output shaft 17 of the crank drive mechanism 12;
It is fixed with a phase difference of 80 °, and the second link 14
a and 14b are rotatably connected to one end of one second link 14a.
The other end of the second link 14b is attached to the front surface of the rear plate 4 and the other end of the
They are rotatably connected at 8,19.

The injection servomotor 11 is attached to the lower part of the sliding body 10 with the motor axis vertical, and a speed reducer 20 having a high reduction ratio is directly connected. The crank drive mechanism 12 includes such a servo motor 11 and a speed reducer 20, and the output shaft 21 of the speed reducer 20 is the output shaft 17 of the crank mechanism 12.

When the injection servomotor 11 is driven during the injection process of the injection molding machine, the first link 13a,
13b is driven and rotated from the home position (A) to the injection completion position (B) in FIG.
The movable plate 5 is extended to the front plate 3
And an injection is performed.

The injection completion position (B) is a position immediately before the first links 13a and 13b and the second links 14a and 14b of the crank links 15 and 16 become straight.

In addition, home position (A), injection completion position (B)
Can be adjusted by changing the parameters on the NC control.

Next, in the measuring process, the injection servomotor 11 is set to a light power supply state for controlling the back pressure, while the injection / metering screw 7 is driven and rotated by the measuring servomotor so that the tip end of the cylinder assembly 8 ( Since the resin is fed into the resin reservoir), the screw 7 moves backward due to the back pressure of the resin, the crank links 15 and 16 are reversed, and the first links 13a and 13b return to the home position (A).

At this time, as shown in FIG. 3, the lengths of the first links 13a and 13b are La and Lb, and the lengths of the second links 14a and 14b are Ma and Mb.
Assuming that the rotation angles of the links 13a and 13b are θ °, the strokes Sa and Sb of the movable plate 5 by the crank links 15 and 16 are provided.
Is almost Since the sliding body 10 moves, the overall stroke [S] of the movable plate 5 is [S] = Sa + Sb. The stroke of the sliding body 10 is Sb and the crank link 16
It is about minutes.

Usually, the first links 13a and 13b and the second links 14a and 14b are equal in length (La = Lb, Ma = Mb), and therefore Sa = Sb. In some cases, Sa ≠ Sb may be changed by changing the length of one to the other. Further, the length of each link can be proportionally increased or decreased to adjust the magnitude of the stroke.

 The above is the embodiment.

The injection servomotor 11 may be arranged on the upper surface side of the sliding body 10 with the motor shaft horizontal.

Each of the crank links 15, 16 may have a double crank structure in parallel with itself.

Advantages of the Invention Since the double crank structure has the crank links arranged in front and back with a sliding body movable in front and back, the movable plate can have a large stroke and can be operated quickly.

Since the injection servomotor and the crank drive mechanism can be arranged collectively on the sliding body, the intermediate transmission mechanism is omitted, and the number of parts can be relatively small.

Further, since the injection servomotor and the crank drive mechanism are arranged close to each other, the rigidity of the power transmission mechanism for injection is high, and maintenance is easy.

[Brief description of the drawings]

FIG. 1 is a simplified plan view, FIG. 2 is a front view including a cross section taken along line II of FIG. 1, and FIG. 3 is a diagram for explanation. 1 ... Ejection unit, 3 ... Front plate, 4 ... Rear plate, 5 ... Movable plate, 9 ... Crank mechanism, 10
… Sliding body, 11… injection servomotor, 12… crank drive mechanism, 13a, 13b… first link, 14a, 14b… second
Link, 15,16 …… Crank link, 17 …… Output shaft, 20
…… a reducer.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masaki Oka 3580 Kobaba, Oshino-za, Oshino-mura, Minamitsuru-gun, Yamanashi Inside FANUC CORPORATION Product Development Laboratory (56) References

Claims (1)

(57) [Claims] A movable plate having an injection / metering screw is provided between a front plate and a rear plate so as to be movable back and forth along an injection axis, and the movable plate and the rear plate are connected by a double crank mechanism. The double crank mechanism is a sliding body movable back and forth along the injection axis, a crank drive mechanism mounted on the slide body and driven by an injection servomotor, and a pair of crank links each including a first link and a second link. And one end of the pair of first links in the crank link is fixed to the output shaft of the crank drive mechanism, and the other end is arranged with a phase difference of 180 ° with respect to the rotation direction of the output shaft. One end of each of the two links is rotatably connected, the other end of one of the second links is connected to the rear plate, and the other end of the other second link is a movable press. Injection of electric injection molding machine, characterized in that are respectively pivotally connected to and.