Clamp force control
AssigneeCincinnati Milacron Inc.
InventorsJohn C. Catanzaro, Ronald M. Sparer
Life of this patent
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Abstract
A method for controlling clamping force on an injection molding machine by determining a toggle position at which the molds are in initial contact. That toggle position is determined as a function of a selected clamping force and a selected mold protect force and is effective to produce the desired clamping force when the toggle is fully extended.
Claims14
A method for providing a desired clamping force to hold first and second mold elements on a molding machine in contact, said molding machine having a clamp for generating a clamping force by operating a toggle mechanism to a fully extended configuration in response to control signals generated by a machine control, the method comprising the steps of:
- a. producing a first value representing the desired clamping force;
- b. producing a second value representing a desired initial clamping force;
- c. determining in response to the first and second values a desired mold touch position representing a first configuration of the toggle mechanism upon the mold elements achieving initial contact, said configuration being effective to produce the desired clamping force upon the toggle mechanism being operated to the fully extended configuration;
- d. producing a first control signal representing the desired mold touch position;
- e. operating the clamp in response to the first control signal to move the toggle mechanism to the first configuration simultaneously with mold elements achieving initial contact;
- f. producing a second control signal representing the fully extended configuration of the toggle mechanism;
- and
- g. operating the toggle mechanism to the fully extended configuration in response to the second control signal thereby applying the desired clamping force to the mold elements.
A method for establishing a desired clamping force exerted by a movable mold element against a stationary mold element, said movable mold element being connected to a toggle mechanism operable to move the movable mold element from a first position of no contact with the stationary mold element to a second position of contact with the stationary mold element at which second position a clamping force is applied to said mold elements upon the toggle mechanism being in a fully extended position, the position of the toggle mechanism and the movable mold element being adjustable relative to the stationary mold element, the method comprising the steps of:
- a. determining a desired mold touch position required to provide the desired clamping force independent of a mold protect force;
- b. producing a control signal in response to the desired mold touch position;
- c. operating the toggle mechanism in response to the control signal to move the movable mold element into contact with the stationary mold element;
- d. terminating operation of the toggle mechanism in response to a clamping force between the mold elements exceeding the mold protect force;
- e. producing a feedback signal representing an actual mold touch position of the toggle mechanism upon motion of the movable element being terminated;
- f. testing for equality between the desired mold touch position and the actual mold touch position;
- g. adjusting the position of the toggle mechanism and the movable platen relative to the stationary platen in response to an absence of equality between the desired mold touch position and the actual mold touch position;
- h. iterating steps b. through g. until there is equality between the desired mold touch position and the actual mold touch position;
- i. producing a second control signal representing the fully extended position of the toggle mechanism;
- and
- j. operating the toggle mechanism to the fully extended position in response to the second control signal thereby applying the desired clamping force to the mold elements.
A method for establishing a desired clamping force exerted by a movable platen against a stationary platen on an injection molding machine, said movable platen being connected to a toggle mechanism operable to move the movable platen from a first position of initial contact with the stationary platen through a lock over displacement to a second position of contact with the stationary platen at which second position a clamping force is applied to said platens upon the toggle mechanism being in a fully extended position, said movable platen and toggle mechanism being slidably supported on bars having ends connected between the stationary platen and a support platen movable with respect to the machine, said bars being stretched in response to the toggle mechanism applying a clamping force between the movable and stationary platens, the method comprising the steps of:
- a. selecting a desired clamping force being effective to stretch the bars by a first magnitude;
- b. selecting a mold protect force being effective to stretch the bars by a second magnitude;
- c. determining in response to the desired clamping force and the mold protect force a desired mold touch position representing a position of the movable platen relative to the stationary platen upon the mold elements achieving initial contact;
- d. producing a first control signal representing the desired mold touch position;
- e. operating the toggle mechanism in response to the first control signal to move the toggle mechanism to the desired mold touch position thereby applying a clamping force equal to the mold protect force and stretching the bars a total amount equal to the second magnitude;
- f. producing a second control signal representing the fully extended configuration of the toggle mechanism;
- and
- g. operating the toggle mechanism to the fully extended configuration in response to the second control signal thereby applying the desired clamping force and stretching the bars a total amount equal to the first magnitude.
Dependencies are inferred from the claim text.