In a machine tool, a component such as a grinding wheel acts on a workpiece to form the latter into a circularly asymmetric shape, for example, a crankpin. Movement of the grinding wheel is controlled by a control signal which is derived from theoretical relative positions and positional velocities of the grinding wheel relative to the workpiece. In the course of at least one revolution of the workpiece, the respective positions of the grinding wheel relative to the workpiece are measured for each of a succession of angular positions of the workpiece. The measured positions are compared with corresponding theoretical positions and data indicative of any differences are stored, and then used to modify the control signal during a subsequent revolution of the workpiece so as to compensate for any of said differences and thereby reduce the magnitude of any error which would have resulted from the measured positional differences.
An apparatus for, and method of, grinding crankpins of a crankshaft wherein the machine is under computer control and the grinding wheel is advanced and retracted under computer control so as to follow the planetary motion of the crankpin as the crankshaft rotates. This maintains grinding contact between the wheel and the crankpin to allow the grinding of the latter. The crankshaft is mounted between centers and is rotated by a drive unit, drive being transmitted to the end of the crankshaft via a connecting device which is torsionally rigid in a plane perpendicular to the axis of rotation of the crankshaft but which is readily deformable in other planes to accommodate misalingnment and so as to decouple the crankshaft from the drive other than to transmit pure rotation to the crankshaft.
It is an object of the present invention to provide a machine tool that the process accuracy does not deteriorate even if the accuracy of the machine itself changes to some extent. A work support means 3 of a spindle 8 etc. to support a work (W), a cutting means 4 of a movable feed bar 9 to the work support means 3 to process the work (W) and a tool base 10 and the like and a control unit 2 are provided. The control unit 2 controls the movement of the cutting means 4 by the measured positional information based on a process origin (O.sub.w) of the work support means 3. The position measurement means 25 like a linear sensor is provided as the means to measure the position to the moving direction of the cutting means 4 based on the process origin (O.sub.w).
The present invention provides a device and method for determining the stable speeds for a rotating milling tool by non-cuttingly exciting the milling tool, by vibrating the milling tool, and measuring how the milling tool is excited. The present invention also provides a device and method for determining the stable speeds for a lathe tool by non-cuttingly exciting the lathe tool, by vibrating the tool using an excitation device mounted on a rotating lathe test bar, and measuring how the lathe tool is excited.
A numerical controller capable of driving a controlled axis in synchronism with a reference axis at a desired speed not restricted by a speed of the reference axis in a path table operation and capable of performing auxiliary function, spindle function and tool wearing compensation function, and changing a position of starting the path table operation of the controlled axis. Data tables are provided storing command positions of controlled axes to be associated with positions of the reference axis and for the auxiliary, spindle and tool wearing compensation functions. The number of pulses of a reference pulse signal from the reference axis is counted and multiplied by an override scale factor and the result is stored in a reference position counter. The controlled axes are driven based on command positions of the controlled axes determined based on the reference position counter, referring to the path and function data tables.
The invention relates to a process and a device for machining of workpieces (10) like crankshafts or similar components which are rotated about their own axis during machining, at least two mutually independently operating rotary milling tools (15, 16, 21, 22) performing material-removing operations simultaneously at different points on a workpiece. In order to maximize the edge life of the tools used, with special regard to the most uniform wear possible on all the rotary milling tools, it is proposed that the rotation speed of the tools be matched or varied to provide an optimum cutting operation and the rotation speed of the second and any other rotary milling tool be controlled dependently upon the tool rotation speed predetermined by the matching or variation.
