Plastic article or earthenware shaping or treating: apparatus – Female mold and charger to supply fluent stock under... – With coupling between charger and mold
Patent
1986-05-07
1987-06-30
Woo, Jay H.
Plastic article or earthenware shaping or treating: apparatus
Female mold and charger to supply fluent stock under...
With coupling between charger and mold
425574, 26432811, B29C 4507
Patent
active
046767304
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a nozzle touch mechanism of an injection molding machine, which urges a nozzle against a mold.
BACKGROUND ART
A nozzle touch mechanism of a conventional injection molding machine hydraulically urges a nozzle against a mold using a hydraulic cylinder. When the nozzle touch mechanism is not driven hydraulically but by a motor, the nozzle must be constantly urged against the mold at a predetermined pressure. For this purpose, a geared motor with a brake is employed. The nozzle is urged against the mold at the predetermined pressure, the motor is braked, and current supply to the motor is simultaneously cut off.
When the nozzle touch mechanism is driven using a geared motor with a brake, a drive current to the motor is cut off and the brake is actuated, thereby stopping the motor. In this case, however, it is difficult to stop the motor at a precise rotating position and to urge the nozzle with an appropriate urging force through the nozzle touch mechanism driven by the motor. In addition, the entire nozzle touch mechanism is expensive.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide an inexpensive motor-driven nozzle touch mechanism wherein an appropriate urging force of the nozzle against the mold is easily set and the nozzle is kept at this position.
In order to achieve the above object, there is provided according to the present invention a nozzle touch mechanism for driving a ball screw with a motor, moving a ball nut engaged with the ball screw and a pressure plate fixed to the ball nut, and moving an injection unit with the pressure plate through a spring, thereby urging a nozzle against a mold by a force generated by flexure of the spring, wherein a threaded portion of the ball screw is formed such that the ball screw is disengaged from the ball nut at a position where a predetermined flexure of the spring is generated to urge the nozzle against the mold at an appropriate urging force.
In this manner, according to the present invention, the ball screw is rotated by the motor, and the pressure plate to which the ball nut is fixed is moved forward, so that the injection unit and the nozzle are moved forward by the spring, thereby urging the nozzle against the mold. In addition, the threaded portion of the ball screw allows the ball screw and the ball nut to be disengaged from each other at a position where an appropriate urging force is generated by a repulsive force caused by the flexure of the spring, i.e., at a position where the compression or the amount of tension on the spring reaches a predetermined value. The ball nut is abutted against the end of the threaded portion of the ball screw, at which point the ball nut is stopped, and the injection unit and the nozzle are also stopped and held thereat. The ball nut cannot then be moved even if the power source of the motor is cut off. Therefore, the predetermined urging force of the nozzle against the mold can be easily set, and the nozzle is held at the predetermined urging force.
In this manner, according to the present invention, only the position for the threaded portion of the ball screw must be accurately designed to stably supply a predetermined urging force with a considerably simple configuration, thereby providing an inexpensive, energy-saving nozzle touch mechanism.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a schematic side view of a nozzle touch mechanism with its peripheral arrangement, according to an embodiment of the present invention; and
FIG. 2 is a partial enlarged bottom view of a drive member and a ball screw shown in FIG. 1.
BEST MODE OF CARRYING OUT THE INVENTION
FIG. 1 shows an embodiment of the present invention, in which reference numeral 1 denotes an injection unit; 2, a cylinder; 3, a nozzle; and 4, a mold. Reference numeral 5 denotes an injection unit base to which the injection unit 1 is fixed; 6, an extruder base; 7, a slide base; and 8, a drive member. The injection unit base 5, the extruder base 6, and the drive member 8 are integra
REFERENCES:
patent: 3924994 (1975-12-01), Aoki
patent: 4090836 (1978-05-01), von der Ohe et al.
Fanuc Ltd.
Heitbrink Timothy W.
Woo Jay H.
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