Abstract: A process planning apparatus extracts a region to be machined based on the difference of the shape data before and after machining of the workpiece, replaces the extracted region into combinations of the predetermined machining features, allocates a predetermined fixed cycle to each of the replaced machining features, and applies an assessment function relating to a machining time and a life of the end mill to each of the combinations of the machining features to which the fixed cycles are respectively allocated, thereby selecting a group of the fixed cycles which makes an assessment value obtained by the assessment function optimum as the optimal process. By these steps, it becomes possible to design the process for causing the NC machine employing end mills as a cutting tool to perform a predetermined machining of a workpiece without relying on the experience of the designer, and without necessitating complicated work.

Abstract: End-mill machining control method and apparatus in which cutting forces tangential and normal to tool motion are detected and machining is controlled based on the detected cutting force values. A primary component Ft and motion axis components Fx, Fy of a cutting force are determined from current values of a spindle motor and motion axis motors for tool feed. A cutting-engaged angle &agr;en is determined from a radius R of a tool and a depth of cut I into a workpiece. A motion direction angle &bgr; is determined from distribution motion amounts &Dgr;X, &Dgr;Y to the axes. The cutting forces Fm, Fs tangential and normal to tool motion are determined from the primary component Ft and a motion axis component Fx or Fy whichever is the largest, the cutting-engaged angle &agr;en, the motion direction angle &bgr;. The accuracy of the determined cutting forces Fm, Fs is high since they are determined from the primary component Ft less affected by disturbance and the largest axis component of the cutting force.

Abstract: A numerical control (NC) device 10 for a machine tool 1 provided with a measurement probe 2b effects measurements of a work 4 on the machine table 5 after a working process. A measurement program, generated by the NC device by modifying a working program, controls the relative movement of the probe 2b with respect to the workpiece 4 such that the probe 2b moves along the contour of the worked portion of the workpiece 4 with a displacement from the neutral position thereof, wherein the displacement of the probe is sampled at a predetermined sampling period. A working error calculation program 17 calculates the working error from the sampled displacements. If the working error is judged correctable, a outside tolerance range and correction re-working is effected so as to reduce the working error. The measurement/re-working cycles are repeated until the working error is within tolerance.

Abstract: A numerical control device comprising a lost motion correction data calculating device having a table/function which represents the motor current of a servo motor, in a servo mechanism for servo-controlling a mechanical movable part. The motor current is detected at a given time instant, and the corresponding amount of lost motion correction is then calculated. The position error caused by the lost motion can be corrected with high accuracy.

Abstract: When a drill is overloaded, while cutting a hole in a workpiece, a torque limiter disconnects the drill from a main spindle. As the drill is disconnected from the main spindle, the torque limiter generates high-level elastic waves. The elastic waves are converted by a transducer into a voltage signal. The level of the voltage signal is compared with a threshold value.