Cincinnati Milacron Inc.

Milacron Inc.

Uniloy Milacron Usa, Inc.

M Barr Klaus

Norman L Steffens

Todd R Brown

David S Bernardi

An apparatus for injection molding comprises an injection unit comprising a plunger, the plunger being translated with accumulation of plasticized material in preparation for injection and being advanced to inject the accumulated plasticized material into mold cavities. At least one electric motor is engaged with the plunger to resist translation as melt is accumulated and to inject plasticized material into the mold cavities. At least one hydraulic actuator selectably operates the plunger during a pack and hold interval to supply supplemental force when force supplied by the electric motors is limited to maintain the operation of the motors within the applicable continuous duty rating thereof. The electric motors are advantageously selectably operatively engaged with the plunger to inject plasticized material into the mold cavities and the hydraulic actuators are operated to inject plasticized material into the mold cavities when the motors are not engaged therefore.

Apparatus and method for injection molding

A molded part ejection tystem ( ) includes a drive mechanism having a reversible servomotor ( ). The drive mechanism for the ejection system includes a cam-and-follower arrangement whereby a circular cam member ( ) is driven by the servomotor ( ) through a drive shaft ( ) that is connected with the cam member ( ) and is offset from the center of the circular cam track ( ). A cam follower ( ) connected with an ejector drive rod ( ), and the cam follower ( ) rides in the cam track ( ) to cause linear movement of the ejector drive rod ( ) as the cam follower ( ) follows the circular cam through its non-circular path of motion. Rotation of the servomotor ( ) in one direction of rotation operates the part ejection system, while rotation of the servomotor in the opposite direction of rotation provides power to another portion of the machine during another portion of a molding machine operating cycle, such as a core-pull system. The servomotor drive shaft ( ) includes a pair of one-way clutches that are each operable in a different direction of rotation of the motor drive shaft ( ). In one direction of rotation, the motor ( ) actuates a part ejection mechanism and in the other direction of rotation, the motor ( ) can provide power to operate a different system of the molding machine. The present invention thus permits a single motor to perform two functions at different times during the operating cycle of an injection molding machine.

Electrically driven apparatus for ejecting injection molded parts

A two-stage, electrically-powered injection unit for an injection molding machine includes an extruder for plasticating material, and a separate melt accumulator to receive the plasticated material. The accumulator includes an injection plunger that is slidably positioned to inject the plasticated material from the accumulator into a mold. The plunger is rotated and translated by an electrically-driven linear actuator, such as a roller screw mechanism. The plunger extends outwardly of the accumulator barrel at the commencement of an injection stroke and is peripherally supported by a bushing at the outer end of the accumulator barrel. The outwardly-extending portion of the plunger can also be supported by a movable intermediate support member to minimize lateral deflection of the plunger and enable a longer injection stroke to be employed. The injection pressure imposed upon the plasticated material can be varied from a relatively low initial injection pressure, to minimize lateral deflection of the plunger, to a relatively higher injection pressure as the length of the portion of the plunger that extends outwardly of the accumulator barrel decreases.

Method for electrically operated plastics injection

The invention is directed to a bi-directional check ring for a two-stage injection unit. More specifically, a close fitting ring is inserted behind the plunger head of the melt accumulator so that normal running clearances between the plunger and barrel bore can be used. The outer diameter of this check ring has a very close fit with the inner diameter the injection barrel, but is not rigidly connected to the plunger. Accordingly, the plunger is free to &ldquo;floats&rdquo; while injection and plastication/filling take place. The open volume between the ring and plunger is small, but sufficient to permit the ring to &ldquo;float&rdquo; very close to the barrel inner diameter, without being influenced by the alignment of the plunger and injection drive motor.

Bi-directional check ring for a two-stage injection unit

A two-stage, electrically-powered injection unit for an injection molding machine is disclosed. The injection unit includes an extruder for plasticating material, and a separate melt accumulator to receive the plasticated material. The accumulator includes an injection plunger that is slidably positioned to inject the plasticated material from the accumulator into a mold. The plunger is rotated and translated by an electrically-driven linear actuator, such as a roller screw mechanism. The plunger extends outwardly of the accumulator barrel at the commencement of an injection stroke and is peripherally supported by a bushing at the outer end of the accumulator barrel. The outwardly-extending portion of the plunger can also be supported by a movable intermediate support member to minimize lateral deflection of the plunger and enable a longer injection stroke to be employed. The injection pressure imposed upon the plasticated material can be varied from a relatively low initial injection pressure, to minimize plunger lateral deflection, to a relatively higher injection pressure as the length of the portion of the plunger that extends outwardly of the accumulator barrel decreases.

Electrically operated injection apparatus

An electro-mechanical drive apparatus uses a single variable speed motor, two one-way clutches, a hydraulic pump stack and a hydraulic accumulator to provide both hydraulic power for linear motion axes and rotation of a driven element of an electromechanical drive system in an injection molding machine. When engaged, the first one-way clutch couples the drive motor to the pump stack, while the second one-way clutch couples the motor to the driven element. During rotation of the drive motor in a forward direction, (a) the first one-way clutch engages, rotating the shaft of the hydraulic pump stack to power the machine's hydraulic systems and charge an accumulator; and (b) the second one-way clutch slips. When the drive motor is rotated in a reverse direction, (a) the second one-way clutch engages, rotating the driven element, and (b) the first one-way clutch slips.

Hybrid injection molding machine

The invention is directed to a two-stage, all-electric injection unit. More specifically, an injection unit in which the feed screw is preferably used only for plastication and the injection of the plasticized material is accomplished by a separate accumulator having an electrically driven linear actuator, such as a ball screw mechanism. The plunger of the accumulator is configured with a helical flight and is rotatable by way of a one-way clutch interposed between the plunger and the ball screw.

Two-stage electric injection unit with rotating plunger

An electro-mechanical drive apparatus uses a single variable speed motor, two one-way clutches, and a hydraulic accumulator to provide both hydraulic power for the linear motion axes and rotation of the plasticizing screw in an injection molding machine. When engaged, the first one-way clutch couples the drive motor to the pump stack, while the second one-way clutch couples the motor to the feed screw. During rotation of the drive motor in a forward direction; (a) the first one-way clutch engages, rotating the shaft of the hydraulic pump stack to power the machines hydraulic systems and charge the accumulator; and (b) the second one-way clutch slips. When the drive motor is rotated in a reverse direction, (a) the second one-way clutch engages, rotating the feed screw, and (b) the first one-way clutch slips. Preferably, the drive apparatus is associated with a double shaft motor mounted adjacent separate drive couplings for the feed screw and hydraulic pump stack.

Injection molding machine having a hydraulically operated clamping system

The invention is directed to a two-stage, all-electric injection unit. More specifically, an injection unit in which the feed screw is preferably used only for plastication and the injection of the plasticized material is accomplished by a separate accumulator having an electrically driven linear actuator, such as a ball screw mechanism. The accumulator is configured so that the ratio of the piston stroke to the piston diameter is preferably in the range of ten to fifteen. In the preferred embodiment there are separate motors for rotation of the screw and operation of the accumulator. An alternate embodiment is disclosed wherein the system is driven with a single motor and one-way clutches.

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Cincinnati, OH, United States of America

M Barr Klaus