Plastic article or earthenware shaping or treating: apparatus – Female mold and charger to supply fluent stock under... – With product ejector
Patent
1991-11-27
1993-03-23
Heitbrink, Tim
Plastic article or earthenware shaping or treating: apparatus
Female mold and charger to supply fluent stock under...
With product ejector
264334, 425444, B29C 4540
Patent
active
051962136
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an ejector mechanism in an injector molding machine, and more particularly, to an ejector mechanism having a simple structure.
BACKGROUND ART
In general, an injection molding machine is provided with an ejector mechanism for taking out a molded article from a mold. As shown in FIG. 3, by way of example, an ejector mechanism installed in a motor-driven injection molding machine is arranged to drive an ejector pin 10', which extends through a movable platen 1', by means of a drive mechanism 20' including a motor 24', so as to push out a molded article to the outside of a mold. A ball screw 21' of the drive mechanism 20' is screwed into the ejector pin 10', and a ball nut 22' threadedly engaged with the ball screw 21' is rotatably supported by a casing 30' fixed to the movable platen 1' and is coupled to the motor output shaft through a belt 23'. The ejector mechanism further includes a plurality of guide rods 40' extending in parallel with the ejector pin 10', and a guide plate 41' arranged for reciprocal motion between the movable platen 1' and the casing 30' along the rods 40'. The ball screw 21' is securely fixed at a front end thereof to a central portion of the plate 41' by a key 42', so as to be unrotatable. As the motor 24' rotates, the ball nut 22' is rotated, so that the ejector pin 10' is moved toward the mold in unison with the ball screw 21', to thereby push out the molded article.
In the above-mentioned ejector mechanism, it is essentially required to provide the plurality of guide rods 40' and the guide plate 41', in order to accurately move the ejector pin 10' along the ejector axis 100'. This, however, leads to an increased number of parts of the ejector mechanism and to complicated structure. Moreover, these constituent parts of the ejector mechanism must be manufactured and the ejector mechanism must be assembled with such a high precision that the ejector pin 10' and the guide rods 40' are exactly parallel with the axis 100' and at the same time an error in the distance between the axes of adjacent guide rods 40' falls within a stringent allowable range of .+-.20-30.mu..
DISCLOSURE OF THE INVENTION
The object of the present invention is to provide an ejector mechanism in an injection molding machine which is simple in structure and can be easily manufactured and assembled.
To achieve the above object, according to the present invention, there is provided an ejector mechanism installed in an injection molding machine having a movable platen, which mechanism comprises a ball screw-spline shaft having a ball screw portion, a spline portion integral with the ball screw portion, and a distal end portion extending through the movable platen and serving as a molded article-ejecting portion; a ball nut threadedly engaged with the ball screw portion; a spline nut spline-fitted on the spline portion; and a drive mechanism, wherein one of the ball nut and the spline nut is fixed to the movable platen, and the other of the ball nut and the spline nut is rotatably supported by the movable platen and drivingly coupled to the drive mechanism.
As described above, the ejector mechanism according to the present invention can be constituted by the ball screw-spline shaft, the ball nut, the spline nut, and the drive mechanism, and thus requires lesser parts and is simple in structure, as compared with a conventional ejector mechanism including a guide plate and a plurality of guide rods. Further, since the ball screw-spline shaft is arranged to be supported by the ball nut threadedly engaged therewith and the spline nut fitted thereon, the ball screw-spline shaft can be brought into alignment with the ejector axis by simply disposing these nuts in such a manner that the axes of the nuts are aligned with the ejector axis. Thus, the manufacture and assembling of the ejector mechanism are facilitated. Moreover, since the distal end portion of the ball screw-spline shaft serves as the molded-article ejecting portion, the ejecting portion can be moved along t
Muranaka Masaki
Tai Ryuji
Watanabe Kikuo
Fanuc Ltd.
Heitbrink Tim
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