Apparatus clutch controlled closure means for a molding

Details Apparatus clutch controlled closure means for a molding Apparatus clutch controlled closure means for a molding

1987-07-16

1989-01-10

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

192 483, 192 97, 425590, 425DIG223, B29C 4564

Patent

active

047970863

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND ART

The present invention relates to a molding machine which is arranged to perform molding with the use of at least one mold constituted by a pair of mold parts, and more particular to a mold clamping apparatus for use with an injection molding machine employing an electrical motor.


TECHNICAL FIELD

Japanese Patent Unexamined Publication No. 125619/1985 discloses a mold clamping apparatus for use with an injection molding machine of the type which has a fixed platen holding one of a pair of mold parts. The mold clamping apparatus has a shaft rotatably supported by a stationary frame. One end of the shaft is drivably coupled with an electrical motor and the portion of the shaft adjacent to the end has a first threaded portion while the portion of the same adjacent to the other end has a second threaded portion with a lead smaller than that of the first threaded portion. First and second nut members are respectively screwed onto the first and second threaded portions, the first and second nut members capable of being rigidly coupled with a rod via first and second clutches, respectively. The rod is rigidly coupled with a movable platen which holds the other of the aforesaid pair of mold parts and which is disposed for reciprocal movement toward and away from the aforesaid one of the same pair. The first clutch is capable of traveling between an engagement position which allows the first nut member to be moved along the shaft during rotation of the shaft with the first nut member rigidly coupled with the rod and a disengagement position which allows the first nut member to be moved along with the shaft during rotation of the shaft with the first nut member released from such rigid coupling with respect to the rod. The second clutch is likewise capable of traveling between an engagement position which allows the second nut member to be moved along the shaft during rotation of the shaft with the second nut member rigidly coupled with the rod and a disengagement position which allows the second nut member to be moved along with the shaft during rotation of the shaft with the second nut member released from such rigid coupling with respect to the rod.
Mold closing is performed as follows. The first clutch is placed in its engagement position while the second clutch is placed in its disengagement position. When the shaft is rotated, the movable platen which holds the one of the pair of mold parts is moved toward the other mold part at a relatively high feed rate in cooperation between the first threaded portion having a relatively large lead and the first nut member screwed onto the same. The mold part held by the movable platen and the mold part held by the fixed platen are combined with each other, thereby completing the mold closing step.
Upon completion of mold closing, the first clutch is placed in its disengagement position while the second clutch is placed in its engagement position. When the shaft is rotated, the other mold part is forced against the one at a relative slow speed, that is, with a relatively large mold clamping force, in cooperation between the second threaded portion with a relatively small lead and the second nut member screwed thereonto.
The above-described mold clamping apparatus of the prior art has advantage in that the opening and closing of the mold at a relatively high feed rate and mold clamping with a large mold clamping force can be performed by means of an electrical motor with a relatively small capacity and in that the molding cycle can be reduced. However, when either of the first and second nut members is rigidly coupled with the rod, the other thereof is necessarily released from rigid coupling with respect to the rod. It is therefore necessary to form the first and second threaded portions along the axis of the shaft over a relatively long range thereof. Accordingly, the shaft must be lengthened and this may result in the disadvantage that the overall size of the molding machine increases.
It is therefore an object of the present invention to provide a moldi

REFERENCES:
patent: 2332862 (1943-10-01), Tourneau
patent: 2521607 (1950-09-01), Rohn

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