Abstract: An electronic current control device for energizing and de-energizing an electromagnet, such as a magnetic chuck, includes a DC power source preferably in the form of a phase-controlled SCR power unit. A conduction angle control signal is routed to positive or negative gates in the power unit to determine polarity and amplitude of direct current through the electromagnet windings. In the "on" mode an analog current feedback loop maintains a predetermined magnetizing level of current through the windings. In the demagnetize mode, a digital system decreases the current amplitude stepwise while alternating the polarity. When the sensed current attains the selected peak level for a given step, a digital count is decremented. The polarity is reversed according to the odd or even count, and a new peak reference level is established corresponding to the digital count.

Abstract: To initiate a scheduled speed change at the correct point in the operating cycle of a machine, a speed change command is subjected to a variable delay. Attaining the commanded speed level too early or too late in one cycle results in the speed change command being correspondingly delayed or advanced in the next cycle. In the preferred embodiment, a low point controller is designed to control the high-to-low speed transition in a multiple spindle bar or screw machine to achieve "feed" speed at the optimum point to decrease cycle time while avoiding damage to the cutting tools.

Abstract: A drive system for a multiple spindle machine tool which includes a separate servo motor for powering the drum shaft which serves as the basic control element for the timing and movement of tools which are operable upon the workpieces carried in the spindles. The speed of the servo motor is regulated by a tachometer in a feedback loop to hold the speed of the motor at any chosen value. The drum shaft rotates at either high speed during tool traverse or low or feed speed during machining operations. A second tachometer driven by the spindle drive system generates a signal proportional to the spindle speed and that signal coordinates the low feed speed of the drum shaft with the spindle speed. Conventional clutches for high-speed and reverse operation of the drum shaft are replaced by switches and potentiometers.

Abstract: A computer controlled machine tool contouring system having a cutting element which is positioned relative to a workpiece support table. An actuating means controls the workpiece support table to synchronously rotate about a first axis and slide along a second axis in response to a set of control signals. The actuating means further controls the cutting element to translate along a third axis (the third axis being parallel to the first axis and perpendicular to the second axis) in response to a further set of control signals. The control signals are generated by a control means from stored data signals which are representative of the coordinates of points on the desired workpiece contour, the desired pressure angle of the cutting element at each contour point, the current radius of the cutting element, and the desired cutting element motion along the third axis.