JP3069964U - In-line injection molding machine - Google Patents

Abstract

(57) [Summary] In a motor driven injection molding machine, the pressure of a molten resin in a heating cylinder is kept constant. SOLUTION: An in-line type injection molding machine in which a screw 5 in a heating cylinder 4 is rotated by a screw rotation motor 6 and the screw 5 is advanced to an injection side by rotating a screw shaft 7 by the injection motor 8. In the above, a brake 9 is provided in a rotation transmission system between the injection motor 8 and the screw shaft 7, and when the screw 5 is retracted by the pressure of the molten resin in the heating cylinder 4, the brake 9 is applied to the rotation of the screw shaft 7. By controlling the pressure, the pressure of the molten resin in the heating cylinder 4 is maintained within an allowable range.

Description

[Detailed description of the invention]

[0001]

[Field to which the invention belongs]

 The present invention relates to a motor driven in-line injection molding machine.

[0002]

[Prior art]

 Conventional in-line injection molding machines use a hydraulic pressure to advance the screw to inject the molten resin, and when measuring and kneading the molten resin in the heating cylinder, apply a constant oil pressure to the injection molding machine to adjust the height. Kneading and weighing were performed by rotating the screw while applying pressure. The above-mentioned injection molding machine equipped with a hydraulic injection mechanism must be provided with a hydraulic device, which increases the size and weight of the entire device and increases the cost of hydraulic maintenance.

[0003] Therefore, an injection molding machine driven by a motor instead of a hydraulic pressure has been implemented. It has a screw rotation motor for rotating the screw, and an injection motor for rotating the screw shaft to advance the screw in the injection direction. The injection motor is a servomotor, and also controls the back pressure applied to the resin during the measurement and kneading of the molten resin in the heating cylinder.

[0004]

[Problems to be solved by the invention]

 The injection motor is driven so that the screw is advanced in the injection direction by limiting the output torque by the torque mitting means so that the back pressure applied to the molten resin becomes the set back pressure.

When the pressure of the molten resin becomes larger than the set back pressure due to the rotation of the screw, the screw retreats, and the injection motor is reversed via the screw shaft. As a result, the set back pressure is applied to the molten resin, but since the injection motor rotates in the direction opposite to the movement command direction, the error register in the servo register of the injection motor is set in the error register. Positional deviation increases.

As a result, if the measured value of the molten resin is large and the screw retreat amount is large, the position deviation amount stored in the error register becomes a large value, so that the capacity of the error register is increased more than necessary. Must be.

In general, a control device that controls a servo circuit stops a control operation and issues an alarm when a position error amount stored in an error register exceeds a predetermined value, even if some trouble occurs. It is common to use However, if there is no abnormality at the time of weighing, an increase in the weighing value increases the positional deviation and issues an alarm to stop the operation, resulting in reduced workability.

The present invention clarifies a motor-driven in-line type injection molding machine that solves the above-mentioned problems.

[0009]

[Means to solve the problem]

 In the in-line injection molding machine of the present invention, the screw (5) in the heating cylinder (4) is rotated by the screw rotation motor (6), and the advance of the screw (5) to the injection side is performed by the injection motor (8). In the in-line type injection molding machine in which the screw shaft (7) is rotated in step (1), a brake (9) is provided in a rotation transmission system between the injection motor (8) and the screw shaft (7). And

[0010]

[Action and effect]

 When the screw (5) retreats due to the pressure of the molten resin in the heating cylinder (4), the screw (7) is rotated by applying a load by applying a brake (9) to the rotation of the screw shaft (7). Therefore, the pressure of the molten resin in the heating cylinder (4) can be maintained within an allowable range.

At the time of injection, the brake (9) is released, the screw shaft (7) is rotated by the injection motor (8), and the screw (5) is advanced by screw thrust. The problem of the prior art in which the control of the servomotor gives resistance to the retraction of the screw (5) is solved.

[0012]

[Embodiment of the invention]

 FIG. 1 is a front view of an injection unit (2), which is a main part of the present invention, of the injection molding machine, and FIG. 2 is a plan view. A slide block (3) having a screw (5) and a screw shaft (7) on the same straight line is slidably provided on a base (1).

[0013] The slide block (3) is slidably supported by four guide shafts (23), both ends of which are supported by support plates (21) and (22). And a screw shaft (7) is protruded. A heating cylinder (4) projects forward from a front support plate (21), and the screw (5) is rotatably housed in the heating cylinder (4). Is connected to a hopper (41).

A screw rotation motor (6) is mounted on the slide block (3), and a pulley (61) provided on a rotation shaft of the motor and a pulley (51) provided on a rear end of the screw (5). Are linked by a belt (62).

The screw shaft 7 is a ball screw shaft having a small frictional resistance. The screw shaft 7 rotates behind the slide block 3 by a distance slightly longer than the maximum stroke of the screw 5 at the time of injection so that it can move back and forth. The screw shaft 7 is screwed together, and a rear portion of the screw shaft 7 is a round shaft 70 rotatably penetrating the support plate 22.

An injection motor (8) is provided on a rear support plate (22), and is provided behind a small pulley (81) provided on a rotary shaft of the motor and a round shaft (70) of the screw shaft (7). The large pulley (71) provided at the end is linked by a timing belt (82). The injection motor (8) is a high-precision control motor such as a servomotor.

A brake (9) is connected to a rotation transmission system between the injection motor (8) and the screw shaft (7). The brake (9) is an electromagnetic brake in the embodiment, but may be any as long as it can control the brake pressure.

A pressure sensor (not shown) for the molten resin in the heating cylinder (4), an injection motor (8), a brake (9), and the screw rotation motor (6) are connected to a control unit (200). The kneading and measurement of the molten resin by the rotation of the screw (5) in the heating tube (4), and the advance speed of the screw (5) for maintaining the set injection pressure are controlled. When the screw (5) moves backward, the voltage to the electromagnetic brake is controlled in accordance with the signal from the pressure sensor to adjust the brake strength, and the rotation of the screw shaft (7) causes the heating cylinder to rotate. (4) A load for maintaining the pressure of the molten resin within an allowable range is applied.

The injection unit (2) is connected to a nozzle touch device (100) by a motor (101) and a screw shaft (102) rotated by the motor, and moves the entire injection unit (2) slightly back and forth. By doing so, the nozzle (42) at the tip of the heating cylinder (4) can be brought into contact with and separated from the fixed mold (300).

However, as shown in FIG. 1, the screw (5) is rotated at a position where the screw (5) is most advanced, and the pellets in the hopper (41) are guided into the heating cylinder (4) to be melted. To the front of the heating cylinder (4).

When the molten resin is filled in the front part of the heating cylinder (4), a force for pushing the screw (5) backward acts on the screw (5) rotating in a direction for feeding the molten resin forward. I do. The power to the injection motor (8) is cut off, and if there is no brake (9), the slide block (3) rotates the screw shaft (7) with the force pushing the screw (5) backward. And the pressure of the molten resin in the heating cylinder (4) falls below the allowable range.

In the present invention, when the screw (5) is retracted, the brake (9) is actuated to pull the screw shaft (7) through the pulley (81), the timing belt (82), and the pulley (71). A load can be applied to the rotation to maintain the pressure of the molten resin in the heating cylinder (4) within an allowable range, and resistance can be given to the retraction of the slide block (3). Thereby, the pressure of the molten resin in the heating cylinder (4) can be maintained within the set range.

At the time of injection, the brake on the screw shaft (7) is released, and the screw shaft (7) is rotated by the injection motor (8) in the direction in which the slide block (3) moves forward. 5) is advanced, and the molten resin may be injected into the fixed mold (300) from the nozzle (42) at the tip of the heating cylinder (4).

The present invention is not limited to the configuration of the above embodiment, and various modifications can be made within the scope described in the claims for utility model registration.

[Brief description of the drawings]

FIG. 1 is a front view of a main part of an injection molding apparatus.

FIG. 2 is a plan view of the same.

[Explanation of symbols]

 (3) Slide block (4) Heating tube (5) Screw (6) Screw rotation motor (7) Screw shaft (8) Injection motor (9) Brake

Claims (2)

[Utility model registration claims] A screw (5) in a heating tube (4) is rotated by a screw rotation motor (6), and the screw (5) is advanced to an injection side by an injection motor (8). ), The brake (9) is provided in the rotation transmission system between the injection motor (8) and the screw shaft (7), and the molten resin in the heating cylinder (4) is rotated. When the screw (5) moves backward due to the pressure of the brake (9)
An in-line type injection molding machine characterized by imparting resistance to the rotation of the screw shaft (7) by maintaining the pressure of the molten resin in the heating cylinder (4) within an allowable range. 2. The injection motor (8) is a servomotor, and the brake (9) is an electromagnetic brake.
(9) The injection motor (8) and the screw (5) are connected to the control unit (2
2. The in-line injection molding machine according to claim 1, which is linked to (00).