Abstract: A method for compensating for variations in the operating efficiency of electric motors used in plastic processing machines. The current to the motor is continually monitored during all periods of operation to identify variations in the motor's actual efficiency as it relates to measurable machine performance. Normal operation of the electric motor is monitored to establish baseline current usage for the various periods of the operating cycle under given conditions. With a baseline established, variations in motor efficiency can be detected by monitoring the current during closed loop control of specific parameters and comparing the results to the baseline. Since the parameter is held constant by virtue of the closed loop, a deviation in current from the baseline indicates a change in efficiency. Based on the identified variance, the current to the motor during other (open loop) operations can be adjusted accordingly.

Abstract: A dynamic braking system for the electric motors in an injection molding machine uses the electric heater bands on the barrel of the injection unit as resistors to dissipate the energy generated by the electric motors during an emergency stop. This system includes suitable switching circuitry to disconnect the heaters from their normal power source and connect them to the motor windings for the short term dynamic braking function.

Abstract: A manual data input facility of a machine control includes graphically assisted input. An MDI main display and lead-through graphic displays are generated to facilitate selection of functions and entry of associated data. The displays make use of graphic icons and text recognizable by an operator. Input devices advantageously include a contact actuated touch screen and numeric keypad. A graphic assisted MDI mode of operation generates instruction blocks conforming to a predetermined user programming convention in response to operator selections and numeric data input. The operator initiates execution of instruction blocks so generated, one block at a time, by operation of a Cycle Start input.

Abstract: The method of the present invention relates to reducing cycle time in injection molding machines that are running large capacity molds, such as multiple cavity preform molds, and require a high volume supply of quality melt. Specifically, the present invention proposes using a continually plasticizing extruder to supply two melt accumulators which will alternately operate to inject the plastic material into the mold. To accomplish this, a rotary valve at the end of the extruder is controlled to fill the pots, and ball check valves are positioned to control flow direction and limit pressure in certain parts of the system. A shuttle valve between the shot pots and before the nozzle facilitates decompression.

Abstract: A segmented presser member for laying fiber tows and producing composite plastic articles has a plurality of presser element disks. The disks, stacked side-by-side, are independently movable and biased against a work surface such as a mandrel or mold. An elastic band is provided on the rotary outer periphery of each disk. Each band is unconnected to elastic bands on adjacent disks. The disks and their respective bands are radially movable during the laydown and compaction of the fiber tows over the changing contour of the workpiece surface. The elastic band has a low friction face, such as, for example, a (TEFLON) film, for engaging the fiber tows.

Abstract: Torque ripple in brushless DC motors is reduced by compensation of signals controlling energization of motor stator windings. Motor current magnitude is compensated in response to compensation factor values correlated to the ratio of actual torque to ideal torque at constant current at various relative positions of a motor rotor and stator. A motor current command component associated with a commanded torque is compensated for cogging torque associated with motor magnetization. Measured relative position values are compensated to account for torque profile distortions associated with motor current magnitude.

Abstract: A method for efficiently interpolating sub-span position commands for control of a machine member. The method includes storing a set of coefficients defined by a parametric function relating member position and time, calculating the distance between a target coordinate axis position command and a current coordinate axis position command, generating first and second command modifiers from the stored coefficients, the calculated distance, and a current coordinate axis position command, and summing the current coordinate axis position command and the first and second command modifiers to generate a subspan position command.

Abstract: A machine with a movable element, such as a machine tool and its spindle carrier, that is powered by a motive means to move the element is provided with a counterbalancing system having at least two counterforce means operably connected to the movable element for exerting a counterbalance force on the movable element in opposition to the first force and wherein a first one of the counterforce means has a controllable servomotor means. The control means controls the servomotor means so as to cause the counterbalancing system to exert a substantially constant counterbalance force on the movable element in opposition to the first force. The second one of the counterforce means may be a hydraulic means having a hydraulic cylinder operably connected to an accumulator and a hydraulic piston operably disposed in the cylinder and connected to the movable-element.

Abstract: Aqueous machining fluid compositions, especially aqueous metalworking fluid compositions, are provided that exhibit improved reduction of friction and forces in the mechanical shaping and working of metallic and solid non-metallic workpieces. These compositions comprise a) water, b) a sulfurized organic material selected from the group consisting of sulfurized unsaturated aliphatic carboxylic acids having from 6 to 22 carbon atoms and salts thereof, sulfurized unsaturated esters of aliphatic carboxylic acids having 1 to 22 carbon atoms, sulfurized polymerized unsaturated fatty acids and salts and esters thereof, and mixtures thereof, c) a sulfurized hydrocarbon and d) an aliphatic ester of a dialkyldithiocarbamic acid.

Abstract: The total alkalinity of an aqueous metalworking fluid is monitored and controlled by a continuous titration method that continuously supplies a stream of the metalworking fluid, at a known, controllable flow rate, to a flow through chamber having therein a static mixing element. Simultaneously and separately a stream of acid titrant, of known acid concentration is injected into the flow through chamber at a known controllable flow rate. The acid titrant and metalworking fluid mix and react in the chamber and the reacted metalworking fluid exiting the chamber passed over the tip of a pH electrode. The pH of the reacted metalworking fluid is continuously monitored and the output of the pH electrode used to adjust the flow of acid titrant to the chamber until an endpoint pH valve (typically a pH of 4) is reached.

Abstract: Positioning errors of a moveable machine member are reduced by compensation for cyclic errors attributable to anomalies of a position transducer. Compensation values are produced which are unique only within the pitch of transducer measurement and are applied to correct the representation of measured position produced by the transducer. Positioning errors not attributable to the position transducer are corrected by compensation of position commands using compensation values associated with fixed calibration points. Use of both compensations is effective to eliminate residual errors in position correction which arise from use of calibration data created without correction of transducer cyclic errors.

Abstract: Spaced headstock shafts are supported in common headstock walls such that their ends are inaccessible. The shafts are connected by an active timing belt. A spare timing belt is assembled around, but held out of contact with the shafts. At replacement time, the worn active belt is cut and removed and the spare belt is axially moved into its place. The drive may also include a belt tensioner.

Abstract: A method and apparatus for limiting current through a switching device supplying current to a load. A control evaluates a model representing the switching device temperature as a nonlinear function of current and time. The model compares the temperature of the switching device to a maximum allowable temperature. The current limit is defaulted to peak current; and in response to the model detecting a temperature in excess of the maximum allowable temperature, a nominal current limit is set. The current limit reset to peak current after the model detects a switching device temperature a predetermined magnitude below the maximum allowable temperature.

Abstract: A moving slide has a pair of flexible curtains mounted to its front and rear surfaces, the curtains being attached at opposite ends to front and rear support posts mounted to a base. The support posts have upper and lower pulleys. A cable is connected to the front of the slide and runs in this fashion: first horizontally across the top pulley, thence to the lower pulley, thence to the other support post, thence upwardly and finally around to the horizontal portion which connects to the rear of the slide. The cable is tensioned to a predetermined load which remains constant throughout the slide travel as the front and rear horizontal portions of the cable move. The flexible curtains are suspended from, but are not rigidly attached to, the cable. Thus, as the curtains expand and contract, the moving horizontal portions of the tensioned cable ride smoothly through the curtains, maintaining curtain support.

Abstract: An injection molding machine utilizing vector controlled AC induction motors in its servomechanism drive systems. Vector controlled AC induction motors provide a cost effective high power drive system which superior performance capabilities. Further system efficiencies are realized when the control is configured to run multiple motors by multiplexing the computer controller circuits for the power sections of each motor.

Abstract: An improved tape laying machine, more particularly an improved tape laying head assembly is provided for laying plastic tape onto a work surface to produce a reinforced plastic structure. The improvement provides means for transferring the vertical movement of at least one segment of a stacked plate segmented shoe presser member, of the head assembly, as it engages the work surface to a non-terminal segment of the stacked plate segmented shoe and a sensor means, e.g. a linear variable differential transformer, sensing the movement of the non-terminal segment to produce a signal related to the movement of the non-terminal segment that can be employed to control and direct the movement of the head assembly and/or presser member. The improvement of the invention produces a smooth shimless transition of the presser member onto the work surface, from a work surface non-engaging position, in a tape laying operation.

Abstract: A damped, cantilevered support arm for a machine tool position monitoring device rigidly attached to the machine tool by a pair of spaced bolts for relative movement with a machine part along a longitudinal axis. The line of centers through the bolts is oriented along the longitudinal axis and the arm is mounted with shims located between its base and the machine tool part to allow limited effective freedom of movement of the support arm around the line of centers in a direction normal to the longitudinal axis. A squeeze-film damping chamber is provided between the spaced shims for reducing the response of the support arm in the normal direction during relative movement along the longitudinal axis. A boundary O-ring seal together with the thickness of the spacers, defines the damping chamber.

Abstract: Plural electrical loads supplied with power from a single source are monitored to detect defective loads. Each load is periodically individually energized and current delivered by the source is measured. Measured current for each load is compared with limit values to detect abnormal values. To overcome consequences of supply voltage fluctuations, supply voltage is also measured and admittance of each load is determined from measured current and measured voltage. The admittance value thus determined for each load is compared with limit values to detect abnormal values. Load monitoring of loads energized according to a control algorithm proceeds by periodic momentary suspension of energization according to the control algorithm and energization of selected individual loads.