Abstract: Flat rolled magnetic steel sheets and strip or a die is turned in the press forming process. Rotor cores are stacked with turning through an angle which is an odd number multiple of about (360°/(number of slots in the motor×natural number n×2)) and stator cores are stacked with turning through an angle which is an odd number multiple of (360°/(number of poles in the motor×natural number n×2)). Stacking with turning through an angle which is an odd number multiple converts the phases of cogging torques into mutually opposite phases and cancels and reduces the cogging torque caused by magnetic anisotropy.

Abstract: A rotary encoder easily position-adjusted in relation to a rotary shaft and is reduced in accuracy deterioration attributable to rotational unstableness and the like which is caused after attachment to the rotary shaft. The encoder is a device attached to the rotary shaft to outputting signals with the rotation of the shaft. The encoder includes a rotary disk, a detector for detecting rotational position of the rotary disk, a disk holder for fixedly attaching the rotary disk to the rotary shaft, and a housing for fixing the detector such that the detector is opposed to the rotary disk. The encoder comprises a retainer attachable to and detachable from the disk holder and the housing for retaining positional relation between the disk holder and the housing.

Abstract: A floppy disk drive apparatus in which, when a floppy disk is used as the memory medium for numerical control data, control is performed in such a manner that data to be transferred via an interface (4) is read out whenever there is a data transfer request from a numerical control unit (8). In particular, to an arrangement where a data read head is constantly in contact with the floppy disk, disk wear is made as small as possible by stopping the drive motor as the occasion may demand, and it is necessary that data be transferred to the numerical control unit without interruption. The drive apparatus of the invention performs optimum drive control in terms of prolonging the service life of the disk.

Abstract: An involute interpolation method for use in machining by a numerical control apparatus.A rotational direction (G03.1) of an involute curve, coordinates of an end point (Xe, Ye), a center position (I, J) of a base circle as viewed from a start point, and a radius (R) of the base circle are instructed, from two equations representing the involute curve sequence of points are obtained, and interpolation of the involute curve is performed while interpolating those points in a range of the angle .theta. corresponding to the start point on the involute curve to the end point thereon.The increment of .theta. is decremented in proportion to the increment of the angle owing to the factor K/ (R.multidot..theta.), so that the interpolation is performed in such a manner that the speed in the tangential direction is made at constant, whereby a machining speed of the involute curve is maintained at constant.