Patent ID: 7484954
Filing Date: 2009-02-03
Classification: B29C

Abstract:
1. A molding system for manufacturing molded articles, the molding system comprising: a stationary platen being adapted to mount a stationary mold portion; a movable platen being movable relative to the stationary platen, the movable platen being adapted to mount a movable mold portion; an injection unit being operatively coupled with the stationary mold portion; clamping mechanisms being mounted to corners of the stationary platen; molding-system locks being mounted to corners of the movable platen; a lock-drive assembly being coupled with the molding-system locks, the lock-drive assembly for synchronously locking and unlocking the molding system locks; tie bars extending from respective clamping mechanisms to respective molding-system locks, each of the tie bars being received in a respective molding-system lock, each of the molding-system rocks selectively lockably engaging and lockably disengaging the tie bars with the movable platen, the clamping mechanisms for applying a clamping force to the tie bars and the clamping force may be transferred to the stationary platen and the movable platen so as to hold the movable mold portion closed against the stationary mold portion during injection of a molding material from the injection unit to a mold cavity, the mold cavity being defined by the stationary mold portion and the movable mold portion being held closed against each other, each of the tie bars including a distal end having bar-interrupted teeth extending over a length of the tie bars, and the bar-interrupted teeth include: (i) tie-bar teeth extending from the tie bars, and (ii) tie-bar slots defined through the tie-bar teeth extending longitudinally along the tie bars; each of the clamping mechanisms including: (i) a clamp cylinder being formed in the stationary platen, and (ii) a clamp piston being positioned in the clamp cylinder, the clamp piston being connected to a corresponding tie bar, the clamp piston being placable in a hard stop position, the tie bars and respective clamp pistons being movable axially toward the stationary platen when each clamp cylinder becomes actuated, the tie bars and each clamp piston being movable toward the movable platen; an actuator being coupled with the clamp piston, the actuator for pushing the clamp piston back into the hard stop position; a stroke actuator being coupled with the movable platen, the stroke actuator for moving, after the clamping mechanisms are de-actuated so as to remove the clamping force, the movable platen away from the stationary platen so that the stationary mold portion and the movable mold portion may be separated from one another so as to allow extraction of a molded article; and a mold-break actuator being operatively coupled with the stationary mold portion and the movable mold portion, the mold-break actuator for applying a mold-break force to the stationary mold portion and the movable mold portion; each of the molding-system locks including a rotatable sleeve, the rotatable sleeve accommodating locking and unlocking of the tie bars relative to the movable platen, and the rotatable sleeve permits mold shut-height adjustment of the tie bars, each rotatable sleeve being coupled with the lockdrive assembly; and fixed sleeves being rigidly attachable to the corners of the movable platen so that the clamping force may be transmitted to the movable platen via the tie bars, each of rotatable sleeves being rotatably engagable with a respective fixed sleeve, each of the fixed sleeves includes fixed-sleeve threads extending toward the rotatable sleeve, the fixed sleeves allowing the rotatable sleeve to be threadably movable relative to the movable platen so that the rotatable sleeve may accommodate mold shut-height adjustment of the tie bars and the movable platen, the rotatable sleeve includes externally-extending sleeve threads that are engagable with the fixed-sleeve threads, the rotatable sleeve includes a tie-bar facing surface, and the tie-bar facing surface of the rotatable sleeve includes sleeve interrupted teeth that are interlockable with the bar-interrupted teeth of the tie bars, the sleeve-interrupted teeth include sleeve-teeth and sleeve slot extending through the sleeve-teeth which are selectively engagable and disengagable with respective tie-bar slots and the tie-bar teeth, a sufficient length of the externally-extending sleeve threads and of the fixed-sleeve threads being provided such that the rotatable sleeve is rotationally positionable over a length that is greater than a pitch of the sleeve-interrupted teeth of the rotatable sleeve, a sufficient axial-tooth clearance being provided in the sleeve-interrupted teeth and the bar-interrupted teeth, such that when: (i) the rotatable sleeve is rotated between a locked position and an unlocked position; and (ii) the tie bars are in a correct position relative to the rotatable sleeve, a small amount of axial movement between the externally-extending sleeve threads and the fixed-sleeve threads does not result in contact between the rotatable sleeve and the tie bars, whereby the molding-system locks allow stroking of each clamp piston to be reduced to a minimum so that stroking of each clamp piston may be performed for only what is required for tooth clearance and for straining molding-system components under a clamp-up condition, and cycle time may be improved because active re-positioning of each clamp piston is not required for locking or unlocking of the tie bars.