Plastic article or earthenware shaping or treating: apparatus – Control means responsive to or actuated by means sensing or... – Mold motion or position control
Patent
1988-03-08
1989-10-31
Housel, James
Plastic article or earthenware shaping or treating: apparatus
Control means responsive to or actuated by means sensing or...
Mold motion or position control
318 66, 318432, 318625, 318811, 425162, 425168, 425451, 4254519, 425589, B29C 4566
Patent
active
048773883
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a mold clamping apparatus for use in an injection molding machine, and more particularly to a spindle driving device in a mold clamping apparatus, which is low in cost and has an improved responsiveness.
2. Description of the Related Art
In injection molding machines, mold clamping apparatus have been known of a type comprising a drive source consisting of an electric motor (hereinafter referred to as a motor), and a power transmission system for converting a turning force generated by the drive source into a driving force for axially driving a spindle, and wherein a movable platen arranged to be movable in unison with the spindle is axially driven by the drive source through the power transmission system so as to perform mold-opening, mold-closing and mold-clamping. In a mold clamping apparatus of this kind, the drive source may consist of a single general-purpose motor capable of generating a required mold clamping force of from 5 to 10 tons in case of a small or medium apparatus. In a large mold clamping apparatus requiring a larger mold clamping force, however, the drive source must be of a specially ordered high-output type. For this reason, a considerable cost increase occurs and further operational responsiveness of the motor deteriorates since the inertia of the rotor becomes large.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a mold clamping apparatus for use in an injection molding machine, which is low in cost and has an improved responsiveness.
In order to achieve the above-mentioned object, the mold clamping apparatus of the present invention comprises a plurlity of general-purpose motors, each coupled through a coupling means to a spindle of the mold clamping apparatus, so as to drive the spindle by means of the plurality of motors.
Since the spindle of the mold clamping apparatus is adapted to be driven by means of a plurality of the motors, the spindle driving device of the mold clamping apparatus is low in cost. Moreover since the rotor of each motor is relatively small in diameter the sum of the rotor inertia of the plural motors is smaller than that of a single special motor having a large rotor. Hence the operational responsiveness of the motor, in particular, the acceleration/deceleration characteristics thereof can be improved.
These, together with other objections and advantages, which will be subsequently apparent, reside in the details of construction and operation as more fully hereinafter described and claimed, reference being made to the accompanying drawings forming a part thereof, wherein like numerals refer to like parts throughout.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspectie view showing a spindle driving device of a mold clamping apparatus, according to an embodiment of the present invention;
FIG. 2 is a perspective view showing, by way of example, a conventional spindle driving device; and
FIG. 3 is a circuit diagram showing a control unit for driving the motor of FIG. 1.
DESCRIPTION OF THE REFERRED EMBODIMENT
Referring to FIG. 2, a conventional spindle driving device for use in a mold clamping apparatus of an injection molding machine will be explained. In FIG. 2, a ball screw 2 which constitutes a spindle is rotatably supported by a rear platen 1, and a ball nut 3 is threadedly engaged with an outer portion of the ball screw 2 projecting rearwardly of the rear platen 1. A timing pulley (hereinafter referred to as a pulley) 4 is coupled to the ball nut 3 in a manner so as to be rotatable integrally with the ball nut. Further, the pulley 4 is operatively coupled to a servomotor 5 through a timing belt 7 which is wound around the pulley 4 and a second pulley 6 fixed to the output shaft of the motor 5. The ball screw 2 has its inner end coupled to a movable platen (not shown) through a crosshead (not shown) of the mold clamping apparatus (in the case where the apparatus has a toggle mechanism) or coupled directly thereto (in the case of
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Inaba Yoshiharu
Tokunaga Shigeo
Fanuc Ltd.
Housel James
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