Clamping mechanism in an injection molding machine
First Claim
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1. A clamping mechanism for use within an injection molding machine, the mechanism comprising:
- a clamping cylinder with a front chamber and a rear chamber, the front chamber having an internal diameter, the rear chamber having an internal diameter, the internal diameter of the rear chamber being greater than the internal diameter of the front chamber;
a main piston located within the clamping cylinder, the main piston being movable within the clamping cylinder between an open position, an intermediate position and a closed position, the main piston being located within the rear chamber when the main piston is in the open position, the main piston being located within the front chamber when the main piston is in the intermediate position, the main piston being located within the front chamber when the main piston is in the closed position, the main piston having an outermost periphery, the outermost periphery of the main piston having a diameter, the diameter of the outermost periphery of the main piston being less than the internal diameter of the rear chamber of the clamping cylinder such that fluid flows around the outermost periphery of the main piston when the main piston moves from the open position to the intermediate position, the diameter of the outermost periphery of the main piston being equal to the internal diameter of the front chamber of the clamping cylinder such that fluid cannot flow around the outermost periphery of the main piston when the main piston moves from the intermediate position to the closed position;
a clamping ram which is fixed to the main piston;
a booster ram which is coaxial with the clamping ram, a portion of the booster ram being located inside of the clamping ram;
charging means supplying fluid to and receiving fluid from the clamping cylinder, the charging means including a charge cylinder which is in communication with the clamping cylinder, a charge piston which is located within the charge cylinder, and which is movable within the charge cylinder, a charge piston rod which is fixed to the charge piston, the charge piston rod being connected to the clamping ram such that movement of the main piston toward the closed position causes the charge piston to discharge fluid from the charge cylinder into the clamping cylinder; and
a large diameter passage which extends outside of the clamping cylinder, the large diameter passage being connected to the front and rear chambers of the clamping cylinder such that fluid flows through the large diameter passage from the front chamber to the rear chamber when the main piston moves from the intermediate position to the closed position;
wherein the dimensions of the main piston, the clamping ram, the booster ram and the charge piston are such that pressure within the clamping cylinder and the charge cylinder has a net effect of biasing the main piston from the open position toward the closed position.
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Abstract
A clamping mechanism which includes a cylinder and a piston. The diameter of the piston is less than the internal diameter of a rear chamber of the cylinder such that fluid flows around the piston when the piston moves from an open position to an intermediate position. The diameter of the piston is equal to the internal diameter of a front chamber of the piston such that fluid cannot flow around the piston when the piston moves from the intermediate position to a closed position. To prevent cavitation within the cylinder, fluid is charged to the cylinder in accordance with the movement of the piston.
49 Citations
12 Claims
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1. A clamping mechanism for use within an injection molding machine, the mechanism comprising:
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a clamping cylinder with a front chamber and a rear chamber, the front chamber having an internal diameter, the rear chamber having an internal diameter, the internal diameter of the rear chamber being greater than the internal diameter of the front chamber; a main piston located within the clamping cylinder, the main piston being movable within the clamping cylinder between an open position, an intermediate position and a closed position, the main piston being located within the rear chamber when the main piston is in the open position, the main piston being located within the front chamber when the main piston is in the intermediate position, the main piston being located within the front chamber when the main piston is in the closed position, the main piston having an outermost periphery, the outermost periphery of the main piston having a diameter, the diameter of the outermost periphery of the main piston being less than the internal diameter of the rear chamber of the clamping cylinder such that fluid flows around the outermost periphery of the main piston when the main piston moves from the open position to the intermediate position, the diameter of the outermost periphery of the main piston being equal to the internal diameter of the front chamber of the clamping cylinder such that fluid cannot flow around the outermost periphery of the main piston when the main piston moves from the intermediate position to the closed position; a clamping ram which is fixed to the main piston; a booster ram which is coaxial with the clamping ram, a portion of the booster ram being located inside of the clamping ram; charging means supplying fluid to and receiving fluid from the clamping cylinder, the charging means including a charge cylinder which is in communication with the clamping cylinder, a charge piston which is located within the charge cylinder, and which is movable within the charge cylinder, a charge piston rod which is fixed to the charge piston, the charge piston rod being connected to the clamping ram such that movement of the main piston toward the closed position causes the charge piston to discharge fluid from the charge cylinder into the clamping cylinder; and a large diameter passage which extends outside of the clamping cylinder, the large diameter passage being connected to the front and rear chambers of the clamping cylinder such that fluid flows through the large diameter passage from the front chamber to the rear chamber when the main piston moves from the intermediate position to the closed position; wherein the dimensions of the main piston, the clamping ram, the booster ram and the charge piston are such that pressure within the clamping cylinder and the charge cylinder has a net effect of biasing the main piston from the open position toward the closed position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An injection molding machine, the machine comprising:
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(A) a mold which includes a fixed plate and a movable plate; and (B) a clamping mechanism for opening and closing the mold, the clamping mechanism including; (a) a clamping cylinder with a front chamber and a rear chamber, the front chamber having an internal diameter, the rear chamber having an internal diameter, the internal diameter of the rear chamber being greater than the internal diameter of the front chamber; (b) a main piston located within the clamping cylinder, the main piston being movable within the clamping cylinder between the open position, an intermediate position and a closed position, the main piston being located within the rear chamber when the main piston is in the open position, the main piston being located within the front chamber when the main piston is in the intermediate position, the main piston being located within the front chamber when the main piston is in the closed position, the main piston having an outermost periphery, the outermost periphery of the main piston having a diameter, the diameter of the outermost periphery of the main piston being less than the internal diameter of the rear chamber of the clamping cylinder such that fluid flows around the outermost periphery of the main piston when the main piston moves from the open position to the intermediate position, the diameter of the outermost periphery of the main piston being equal to the internal diameter of the front chamber of the clamping cylinder such that fluid cannot flow around the outermost periphery of the main piston when the main piston moves from the intermediate position to the closed position; (c) a clamping ram which is fixed to the main piston and which is fixed to the movable plate; (d) a booster ram which is coaxial with the clamping ram, a portion of the booster ram being located inside of the clamping ram; (e) charging means supplying fluid to and receiving fluid from the clamping cylinder, the charging means including a charge cylinder which is in communication with the clamping cylinder, a charge piston which is located within the charge cylinder and which is movable within the charge cylinder, a charge piston rod which is fixed to the charge piston, the charge piston rod being connected to the movable plate such that movement of the main piston toward the closed position causes the charge piston to discharge fluid from the charge cylinder into the clamping cylinder; and (f) a large diameter passage which extends outside of the clamping cylinder, the large diameter passage being connected to the front and rear chamber of the clamping cylinder such that fluid flows through the large diameter passage from the front chamber to the rear chamber when the main piston moves from the intermediate position to the closed position; wherein the dimensions of the main piston, the clamping ram, the booster ram and the charge piston are such that pressure within the clamping cylinder and the charge cylinder has a net effect of biasing the main piston from the open position toward the closed position.
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Specification