Kinematic structure of gear-and screw-cutting machines with standardized hydraulic couplings in shaping systems

Abstract

Structurally, step hydraulic drives may be represented as three components: the source of working fluid; a hydraulic step motor; and a control device, which forms control pulses and distributes them over the working chambers of the motor. When using a step hydraulic motor to drive a kinematic shaping system in such machine tools, the relation between the blank and the tool depends on the conversion of the flow rate of working fluid into a certain sequence of hydraulic pulses by means of the working slots of the distributor. These pulses are distributed over the working chambers of the hydraulic step motor. Each pulse corresponds to a certain angle of rotation of the motor’s output shaft. Thus, the speed and total angle of rotation of this shaft will be proportional, respectively, to the frequency of the control pulses and the number of pulses. The gear ratio between the blank and the tool also depends on the frequency ratio of the hydraulic control pulses supplied to the step motors rotating the blank and the tool. The use of a discrete hydraulic motor significantly simplifies the machine tool’s control system and ensures sufficient machining accuracy, thanks to the unique relation between the number and frequency of the control pulses and the magnitude and frequency of the discrete displacements (angular or linear) of the executive element.