Plastic article or earthenware shaping or treating: apparatus – Control means responsive to or actuated by means sensing or... – Feed control of material en route to shaping area
Patent
1986-03-06
1987-09-15
Woo, Jay H.
Plastic article or earthenware shaping or treating: apparatus
Control means responsive to or actuated by means sensing or...
Feed control of material en route to shaping area
264407, 366 78, 425149, 425159, 425376B, 425582, 425583, 425587, B29C 4577
Patent
active
046936769
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a screw-rotating/injection mechanism of an injection molding machine which rotates a screw and performs injection through forward movement of the screw. Background Art
In a conventional injection molding machine, an electric motor or a hydraulic motor is used as a drive unit for rotating a screw, and a hydraulic unit is usually used as a drive unit for moving the screw forward to inject a molding material into a mold. Another conventional injection molding machine has also been developed which uses a motor as the injection drive unit.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide a screw-rotating/injection mechanism of an injection molding machine using a motor as a drive unit for rotating a screw and as an injection drive unit for forward movement of the screw, wherein injection control can be easily performed.
In order to achieve the above object, the present invention comprises a drive shaft fixed to a rear portion of a screw shaft and rotatably fixed to a pressure plate, a nut spline-coupled to a spline shaft which is formed on the drive shaft at a rear side of the drive shaft with respect to the pressure plate, a first transmission unit coupled to the nut, a screw rotating motor for driving the nut through the first transmission unit, a plurality of ball nuts fixed to the pressure plate, a plurality of ball screws threadedly engaged with corresponding ones of the plurality of ball nuts, a second transmission unit coupled to the plurality of ball screws, and an injection servo motor for driving the plurality of ball screws simultaneously through the second transmission unit.
In this manner, according to the present invention, when the screw is rotated the screw rotating motor is driven, and when the screw is moved forward, the injection motor is driven to rotate the plurality of ball screws simultaneously, the rotation of which moves the pressure plate forward so that the screw fixed to the pressure plate is drivingly separated from the screw rotating mechanism by the spline shaft, thereby moving only the screw forward. To perform injection, the screw rotating mechanism is first drivingly separated and a servo motor M2 for injection then drives only a second transmission mechanism for moving the screw forward and the screw. Since no unnecessary load mechanism is included, injection can be performed with a good response characteristic, and the pressure plate can be moved smoothly forward, thereby performing excellent injection control.
BRIEF DESCRIPTION OF DRAWING
The accompanying drawing is a partially sectional side view of an embodiment of the present invention.
BEST MODE OF CARRYING OUT THE INVENTION
The accompanying drawing shows an embodiment of the present invention. In the drawing, a screw shaft 1 has a screw at its distal end. A cylinder 2 storing the screw extends though a central hole 17a of a front base 17. A drive shaft 1' is coupled to be stationary to the screw shaft 1 at the rear portion of the screw shaft 1, but is rotatably fixed to a pressure plate 4 through thrust bearings 3 and 3', disposed at large-diameter portions at two ends of a central stepped hole 4a in the pressure plate 4. A rear portion of the drive shaft 1', away from the pressure plate 4, constitutes a spline shaft 4 having a spline engaging portion on an outer surface thereof. The spline shaft 5 extends through a central hole 17'a in a rear base 17' and through a spline coupling nut 6 disposed in the central hole 17'a, and engages with the spline coupling nut 6 through a spline. The nut 6 is fixedly fitted in an inner hole 10a in a shaft 10 of a timing belt gear 9. A timing belt 15 extends between the timing belt gear 9 and a timing belt gear 13 fixed to the motor shaft of a servo motor M1. Ball nuts 7 and 7' are fixed to the pressure plate 4. Ball screws 8 and 8' threadedly engaged with the ball nuts 7 and 7' extend through insertion holes (not shown) in a peripheral portion of the pressure plate 4, and are parallel to the screw sh
REFERENCES:
patent: 3262154 (1966-07-01), Valyi
patent: 3859400 (1975-01-01), Ma
patent: 4540359 (1985-09-01), Yamazaki
Fanuc Ltd
Heitbrink Timothy W.
Woo Jay H.
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