Plastic article or earthenware shaping or treating: apparatus – Female mold and charger to supply fluent stock under... – With means to close mold
Patent
1989-03-30
1990-07-03
Woo, Jay H.
Plastic article or earthenware shaping or treating: apparatus
Female mold and charger to supply fluent stock under...
With means to close mold
4254516, 4254517, 425595, B29C 4566
Patent
active
049386824
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a mold clamping apparatus for use in an injection molding machine, and more particularly to a mold clamping apparatus having a toggle mechanism of the double toggle link type, which is capable of uniformly applying a pressing force onto a movable platen.
BACKGROUND ART
Typically, a toggle type mold clamping apparatus which is mounted on an injection molding machine comprises a double toggle link type toggle mechanism having a pair of toggle sections (toggle links) which are disposed between a rear platen and a movable platen of the injection molding machine and which are symmetric with each other with respect to an axis of the clamping apparatus in the vertical direction. The toggle sections are coupled to each other by means of a crosshead which is threadedly engaged with a ball screw disposed on the axis of the mold clamping apparatus. The mold clamping apparatus is arranged so that, as the crosshead is moved toward the movable platen along the ball screw with rotation of the ball screw, two links of each of the toggle sections for generating a pressing force gradually expand to be switched from a state in which these links are bent to another state in which the links are stretched to establish a straight line relationship therebetween, so as to apply a pressing force onto the movable platen. With a mold clamping apparatus of the kind having a pair of toggle sections which are disposed symmetrically, it is possible to apply the pressing force generated by the toggle mechanism to the movable platen uniformly over the entire surface of the movable platen to a considerable extent. However, since primary parts of the mold clamping apparatus such as the ball screw, crosshead, etc., are disposed and concentrated on the axis of the clamping apparatus, flexure of the toggle mechanism is liable to occur, resulting in poor uniformity of the pressing force applied to the movable platen. Moreover, when flexure of the ball screw occurs due to the weight of the ball screw and the weight of the crosshead and the like, forces resulting from this flexure are exerted on the upper and lower toggle sections, which are separated from each other in the vertical direction of the clamping apparatus, in opposite directions from each other with respect to operational phases of these toggle sections. In this connection, the pressing force applied to the movable platen lacks uniformity. Consequently, parallelism between the rear platen and the movable platen deteriorates, as does the parallelism between the movable platen and the front platen. Accordingly, a guide pin disposed between mold halves respectively mounted on these platens is liable to be damaged, when a mold is employed.
DISCLOSURE 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 capable of suppressing generation of flexure of a toggle mechanism, and of compensating for ununiformity of a pressing force applied to a movable platen resulting from flexure of the toggle mechanism.
To achieve the above-mentioned object, according to the present invention, a mold clamping apparatus for use in an injection molding machine having a movable platen disposed for reciprocal motion between a front platen and a rear platen, includes a first ball screw disposed in facing relation with a peripheral edge portion of the rear platen and extending in parallel with an axis of the mold clamping apparatus; a second ball screw disposed in facing relation with a peripheral edge portion of the rear platen and at a side opposite the first ball screw with respect to the axis of the mold clamping apparatus and extending in parallel with the same axis; a first toggle section disposed inwardly of the first ball screw and having a head which is threadedly engaged with the first ball screw, and a plurality of links; a second toggle section disposed inwardly of the second ball screw and having a head which is threadedly engaged with the second ball screw,
REFERENCES:
patent: 4273524 (1981-06-01), Smith
patent: 4285384 (1981-08-01), Wunder
patent: 4545757 (1985-10-01), Romi
patent: 4642044 (1987-02-01), Ishikawa
Kadoriku Shinji
Watanabe Kikuo
Fanuc Ltd
Heitbrink Timothy W.
Woo Jay H.
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