JPH0620582Y2 - Bi-cylinder actuator for plastic injection molding machines - Google Patents

Description

TECHNICAL FIELD The present invention relates to an injection actuator for a plastic injection molding machine, and more particularly to an injection hydraulic actuator having an auxiliary hydraulic actuator for arbitrary operation.

PRIOR ART As is known, in plastic injection molding machines, two parallel hydraulic actuators (1) of a single cylinder as shown in FIG. 1 are usually used. The pair of hydraulic actuators (1) are symmetrically provided on both sides of the screw conveyor (7). The screw conveyor (7) is a device well known in the field of plastic injection molding technology and has a frame (71). This frame (71) has a rotating shaft (72) extending outward and rearward.
And a shaft (73) extending outward and forward.

Each of the hydraulic actuators (1) has a cylinder (1
0), the cylinder (10) is sealed at the two sealed ends (14), (15), and inside the cylinder (10) is liquid-tight at the sealed end (14). Is provided with a linearly movable piston rod (11). At the end of the piston rod (11) in the cylinder (10),
A linear piston (12) integrated with the piston packing (121) is arranged. The piston rod (11) projects from the closed end (14) and extends parallel to the axis of rotation (72) of the screw conveyor (7). The two piston rods (11) and the rotating shaft (72) extend to and are fixed to the bearing (4), as shown in FIG.

In FIG. 2, two hydraulic actuators (1), bearings (4) and electric drive hydraulic motors (3) joined to a screw conveyor (7) are mounted on a slidable platform (51). There is. During operation, the hydraulic motor (3) is switched on and the rotary shaft (72) is driven to rotate together with the screw (not shown) of the screw conveyor (7), thereby supplying the raw material and then the hydraulic actuator. By (5), the platform (51) is slid forward to a predetermined position, and the hydraulic actuator (1), screw conveyor (7), bearing (4)
And move all of the hydraulic motor (3) to the injection position. The hydraulic fluid or oil is introduced into the cylinder (10) and 2
The piston (12) and piston rod (11) of the two hydraulic actuators (1) are moved forward.

The forward movement of the two synchronous hydraulic actuators (1) causes the screw conveyor (7) to inject through the bearings (4), which results in the injection operation of the plastic injection molding machine. After that, the platform (51) slides back to the original position to prepare for the next work cycle.

(Problems to be Solved by the Invention) In practice, individual injection pressure is required for each product produced by the plastic injection molding method.
The injection pressure of the hydraulic actuator (1) of the conventional plastic injection molding machine is determined by its size. The various injection molding pressures mentioned above can only be obtained by adjusting the output of the hydraulic pump. Therefore, in the case of the conventional plastic injection molding machine, a high output hydraulic pump that increases the manufacturing cost is required. In view of such a situation, the inventor of the present invention has developed an improved hydraulic actuator for use in a plastic injection molding machine which can eliminate the conventional drawbacks.

(Means for Solving the Problems) It is an object of the present invention to provide a pair of hydraulic actuators for use in a plastic injection molding machine that reduces the drawbacks of known injection molding machines.

Another object of the present invention is to provide a hydraulic actuator which can be arbitrarily operated within a predetermined injection pressure and speed range and can be preferably used in a pair form in a plastic injection molding machine.

(Example) As shown in FIG. 3, a pair of parallel bi-cylinder injection actuators for a plastic injection molding machine are symmetrically fixed laterally on both sides of a frame 71 of a conventional screw conveyor 7. There is. The screw conveyor 7 is exactly the same as the screw conveyor (7) shown in FIG. Each hydraulic actuator is a bi-cylinder hydraulic actuator including a combination of a main hydraulic actuator 1 and an auxiliary hydraulic actuator 2 axially attached to the main hydraulic actuator 1.

The main hydraulic actuator 1 has a main cylinder 10, which is sealed at both ends by a front end packing retainer 15 (front sealing end) and a rear end packing retainer 14 (rear sealing end). . Movable piston rod 1
In the main cylinder 10, a rear end packing retainer 14 (rear closed end) is provided in a liquid-tight manner and linearly. A linear main piston 12 is arranged at the end of the piston rod 11 in the main cylinder 10, and an appropriate piston packing 121 is fitted in the main piston 12. The piston rod 11 has a rear end packing presser 14
It projects from (rear closed end) and extends parallel to the rotation shaft 72 of the screw conveyor 7. The two piston rods 11 and the rotary shaft 72 extend to and are fixed to the bearing 4, as shown in FIG.

The front end packing presser 15 (front closed end) and the rear end packing presser 1 of the main cylinder 10, which are closed ends.
4 (rear closed end) has two first openings 141, 1
52 are provided respectively, and these first openings 14
1, 152 communicate with the rear end chamber 101 and the front end chamber 102 divided by the main piston 12 inside the main cylinder 10.

Similarly, the auxiliary hydraulic actuator 2 also has the auxiliary cylinder 2
This auxiliary cylinder 20 is axially attached to the main cylinder 10 by the front end packing retainer 15 (front closed end). The size of the auxiliary cylinder 20 is preferably smaller than the main cylinder 10, and the auxiliary cylinder 20 preferably has a smaller cross-section, but the same length or much longer, compared to the main cylinder 10. The auxiliary cylinder 20 has an auxiliary piston 22, which is integrated with a suitable piston packing 221.

The auxiliary piston 22 and the main piston 12 are the shaft connecting rod 16
The shaft connecting rods pass through the front end packing retainer 15 (front closed end) and are made liquid-tight at the front end packing retainer 15 (front closed end). It is held and further extends to the nut 251 to fix the auxiliary piston 22. The front end packing retainer 15 (front closed end) is further provided with an opening 151 communicating with the inner chamber 201 of the auxiliary cylinder 20, and a circular cap 25 is attached to the front end of the auxiliary cylinder 20. Has been. The circular cap 25 has a shaft hole 250, and the nut 251 moves in and out by reciprocating motion through the shaft hole 250. By providing the auxiliary hydraulic actuator 2, at an injection pressure and an injection speed within a predetermined range of the plastic injection molding machine,
It becomes possible to operate arbitrarily. As shown in FIG. 4, in the case of an ultra-high pressure injection operation, the hydraulic fluid, that is, oil, is introduced into the rear end chamber 101 and the internal chamber 201 by the hydraulic pump through the first opening 141 and the second opening 51. And the hydraulic fluid or oil in the front end chamber 102 is returned via the first opening 152. As a result of introducing the pressure medium liquid, that is, oil into the rear end chamber 101 and the internal chamber 201, the main piston 12 and the auxiliary piston 22 move forward synchronously and inject the molten plastic material into the mold. In contrast, hydraulic fluid or oil is the first
The front end chamber 102 of the main cylinder 10 passes through the opening 152.
When the main piston 12 and the auxiliary piston 22 are pushed back, the pressure medium liquid or oil in the rear end chamber 101 and the internal chamber 201 is returned through the first opening 141 and the second opening 151. Ultra high pressure injection molding is achieved by the movement of the auxiliary piston 22 and the main piston 12.

In the case of a high-speed injection molding operation, as shown in FIG. 5, the main hydraulic actuator 1 is in the idle state, and the hydraulic fluid or oil is introduced only into the inner chamber 201 of the auxiliary cylinder 20. Since the size of the auxiliary cylinder 20 is small, the injection speed provided by the auxiliary piston 22 is high. If the pressure medium liquid, that is, oil is introduced into the front end chamber 102 of the main cylinder 10, the main piston 12 and the auxiliary piston 22 are returned to their original positions. Similarly, the low speed injection molding operation is performed with the first opening 141.
This can be done by introducing the hydraulic fluid, that is, oil, only into the rear end chamber 101 of the main cylinder 10 via the above.

In the case of ultra-low speed injection operation, as shown in FIG.
The hydraulic fluid or oil is simultaneously introduced into the rear end chamber 101 and the inner chamber 201. Since this bi-cylinder actuator has a large storage capacity for the hydraulic fluid, that is, oil, it is possible to perform ultra-low speed injection.

Although the present invention has been described in accordance with the embodiments that are considered to be the most practical and preferred, the present invention should not be limited to the disclosed embodiments. On the other hand, the present invention covers various modifications and equivalent arrangements included in the spirit and scope of the claims of utility model. It should be noted that the above-mentioned utility model registration claim should be broadly construed so as to cover all such modifications and equivalent structures.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a pair of known hydraulic actuators fixed to a known screw conveyor. FIG. 2 is a front view of a plastic injection molding machine having a hydraulic actuator of the present invention. FIG. 3 is a partial sectional view of a pair of hydraulic actuators of the present invention fixed to a known screw conveyor. FIG. 4 is a schematic sectional view of the hydraulic actuator of the present invention in an ultra-high pressure injection operation. FIG. 5 is a schematic sectional view of the hydraulic actuator of the present invention in a high-speed injection operation. FIG. 6 is a schematic sectional view of the hydraulic actuator of the present invention in an ultra-low speed injection operation. Description of main parts of the figure 1 …… Main hydraulic actuator 2 …… Auxiliary hydraulic actuator 7 …… Screw conveyor 10 …… Main cylinder 11 …… Piston rod 12 …… Main piston 14 …… Rear end packing retainer 15 …… Front End packing retainer 16 …… Shaft connecting rod 20 …… Auxiliary cylinder 22 …… Auxiliary piston 25 …… Circular cap

Claims (2)

[Scope of utility model registration request] 1. A main cylinder (10) having two closed ends, a front closed end (15) and a rear closed end (14) for containing a hydraulic fluid, and a main cylinder (10). It is slidably provided and inside the main cylinder (10) the front end chamber (10
2) and the main piston (12) forming the rear end chamber (101), and the first opening for introducing and returning the hydraulic fluid and communicating with the front end chamber (102) and the rear end chamber (101), respectively. Part (141, 152) and the rear closed end part (14) so as to be slidable in a liquid-tight manner, and the end part outside the main cylinder (10) is connected to the bearing of the plastic injection molding machine. A piston rod (11) whose inner end is attached to the main piston (12); and an auxiliary cylinder (coaxially attached to the front closed end (15) of the main cylinder (10). 20) and an auxiliary piston (which is slidably provided in the auxiliary cylinder (20) and forms an internal chamber (201) for sealingly engaging the inner surface of the auxiliary cylinder (20) and storing the hydraulic fluid. 22) and the hydraulic fluid A second opening (151) for entering and returning and communicating with the internal chamber (201) in the auxiliary cylinder (20)
And a shaft that is slidably provided in a liquid-tight manner through the front closed end (15) and interconnects the main piston (12) of the main cylinder (10) and the auxiliary piston (22) of the auxiliary cylinder (20). A bi-cylinder actuator for a plastic injection molding machine comprising a connecting rod (16). 2. A shaft hole (25) is provided at the end opposite to the end of the auxiliary cylinder (20) attached to the main cylinder (10).
2. A bi-cylinder actuator for a plastic injection molding machine according to claim 1, further comprising a circular cap member (25) having a (0).