Abstract: An abnormal state detecting apparatus of a machine tool having a servomotor. The apparatus is provided with a device for detecting an abnormal acceleration and an abnormal torque of the servomotor and a device for detecting an abnormal operation state of the servomotor from the directions of the detected acceleration and torque. When the torque, acceleration and operation state are all abnormal, the machine tool is judged to be in an abnormal state and the servomotor is controlled, thereby protecting the machine tool from an impact in an abnormal operation state.

Abstract: For machining male or female screws, especially of considerably large size diameter, variable pitch or tapered, as desired, a machining center is used which is composed of a work table mounting the work fixedly thereon, and a rotatable machining spindle exchangeably fitted with a thread-cutting tool. Axial feed and rotational speed of the spindle are driven by respective drive motors. In addition, the work table is fed bilaterally on a plane perpendicular to the axis of the spindle by respective feed motors. All these four motors are controlled synchronously by respective controllers which are subjected to control by a single parent numerical controller.

Abstract: In a feedback controller for NC controlled machine tools, the position and the velocity of a work is detected and compared with the desired position. By this comparison, the work velocity is calculated and compared with the current velocity, which determines torque of a driving motor. A torque compensation signal generator, receiving the current velocity, generates a compensation signal according to a predetermined velocity/torque function. The signal is composed with a torque signal passed to a driving motor, and torque compensation is performed. A periodic reaction detector detects periodic fluctuation of the work caused by periodic load fluctuation, and a torque compensation direction causes a signal generator to suppress the fluctuation at desired occasions.

Abstract: A method of machining a member included a screw-shaped portion which is used when the member is ground at the screw-shaped portion by means of a machine tool, in particular, a grinder. A configuration of the tool that projects corresponding to the thread-groove configuration on a section normal to the axis of the screw-shaped portion to be machined is prepared. The axis of the tool is positioned in parallel with the axis of the screw-shaped portion to be machined, and the relevent surface of the screw-shaped portion is machined by moving the tool relative to the screw-shaped portion while their axes are being kept in parallel with each other. According to the present invention, the lead of a small-diameter, deep-grooved female screw-shaped portion may be able to be machined. In addition, an ordinary NC machine tool can be used to machine leads of screw-shaped portions simply by making changes in the NC program.

Abstract: For machining male or female screws, especially of considerably large size diameter, variable pitch or taper, as desired, a machining center is used which is composed of a work table mounting the work fixedly thereon, and a rotatable machining spindle exchangeably fitted with a thread-cutting tool. Axial feed and rotational speed of the spindle are driven by respective drive motors. In addition, the work table is fed bilaterally on a plane perpendicular to the axis of the spindle by respective feed motors. All these four motors are controlled synchronously by respective controllers which are subjected to control by a single parent numerical controller.

Abstract: A feed-screw support structure is adapted to absorb thermal expansion of a feed screw in a machine tool. It comprises a main-body member, a bearing-holder at the one end of the feed screw slidably arranged in the main-body member, a clamping member provided between the bearing-holder member and the main-body member and adapted to fix these members, and a device for operating the clamping member in accordance with factors and matters related to heat generation in the feed-screw. The bearing-holder member being normally held in a stationary condition by the clamping member, the feed screw being allowed to relieve thermal expansion by temporarily releasing the stationary condition when heat generation in the feed screw takes place to a relatively large degree.

Abstract: In a knitting machine, a needle selector having jacks fitted respectively in needle grooves formed in one of a cylinder, a dial and a needle bed is provided. A jack groove cam has a raising cam face for moving the jacks along their respective axes. A control electromagnet is arranged in facing relation to one of the jacks at a yarn feeding position on a stationary side. The control electromaget is excited in response to a needle-selecting signal to attract the jack to bring its butt into engagement with the raising cam face. A jack holding cam is arranged in juxtaposed relation to the other rocking end of the jack at the yarn feeding position. The jack holding cam has a cam face which is so magnetized as to attract the jack toward the jack groove cam. A welt cam is arranged at such a position as to clamp the jack between the cam face of the jack holding cam and a cam face of the welt cam, which is magnetized to attract the jack.

Abstract: A method of cleaning a machined surface comprises: mounting a chip removing tool having two flow paths for compressed air and cooling water, respectively, on a main spindle of a machining center; and simultaneously jetting out the compressed air and cooling water from a mutual outlet, thereby to remove chips attached to a machined surface of a workpiece.A chip removing tool, for use in the above method, which includes a rotatable body attachable to a main spindle of a machining center, has a casing and compressed gas and liquid supply in the casing.

Abstract: An automatic tool replacing device for use in a machining center of the type equipped with a tool storage magazine having a linear portion in which a plurality of tools are arrayed in a row at a predetermined pitch. The tool replacing device has a turret having a plurality of tool holding sections and adapted to make an indexing rotation to bring any one of the tool holding sections to an index position adjacent to the linear portion. A plurality of tool grippers are attached to each of the tool holding sections of the turret and adapted to grip tools in such a manner that the axes of the gripped tools extend in the same direction as the axes of the tools stored in the linear portion of the tool storage magazine and that the axes of the gripped tools are spaced from adjacent ones by the same distance as that between adjacent tools stored in the linear portion of the tool storage magazine.

Abstract: A numerically controlled, dual-turret lathe includes a pair of indexing turrets mounted on respective cross slides which in turn are slidably mounted on respective saddles for movement in the transverse direction of the lathe, the saddles themselves being mounted on a lathe bed for sliding movement in the longitudinal direction of the lathe. The turrets have mounted thereon a cooperative pair of gripper pawls capable of releasably holding work therebetween. As dictated by a prescribed program a numerical control system controls the movements of the cross slides and the saddles so as to cause the gripper pawls to carry the work from a preassigned standby position on the lathe bed into the chuck on the work spindle of the lathe, preparatory to the machining of the work by tools carried by the turrets.

Abstract: A multipolar resolver is so constructed that the need of the conventionally indispensable coil on the resolver rotor is eliminated by providing a center coil on a stator, and 5n or 3n rotor poles and 4n stator poles are provided where n is a positive integer. Sine and consine coils are wound on the stator poles alternately, thus simplifying the construction of the multipolar resolver.

Abstract: A system for the automatic management (detection and control) of tool life in a numerically controlled machine tool having means for automatically measuring the dimension of workpieces and correcting the tool offset of a cutting tool depending on wear on the cutting tool. In the system, the mechanical deformation error component (radial deviation component of a spindle of the machine tool) due to heat is removed from the amount of tool offset value (tool feed position compensation) so as to accumulate solely the net tool wear component, and the cutting tool is exchanged when the accumulated value attains a predetermined setting.

Abstract: A numerical control system for a machine tool having a plurality of saddles; comprising saddle discriminating means for discriminating the saddles from each other, in which saddle discriminating means the cutting work program for controlling the machine tool is described by the use of the same word addresses for each of the saddles but by adding codes for discriminating the saddles from each other at the head of the respective words indicating the same word addresses.

Abstract: An angular position control apparatus for a machine tool circular table comprises a circuit for discriminating whether a command from a command register is such that the output from an absolute position detector for the table passes over the figure zero and an angular converter for converting a present or stopped position of the table detected by the position detector into an angular value. The output of the angular converter is compared with the command to drive the circular table. The resulting compared difference controls the clockwise or counterclockwise rotation of the table and table rotation in the neighborhood of the figure zero of the position detector is smoothed.

Abstract: A machine tool having a plurality of independently and parallelly movable tool posts includes a system for preventing the interference between the tool posts, by means of that the information on the contour position of the tool post represented is added to the information on the position of a reference point set in for each tool post, and the results of addition are compared and calculated.

Abstract: In a position-correctable numerical control system for machines without any device for detecting the absolute position of an object to be controlled, a plurality of equidistantly-spaced reference marks providing standard ranges of control of the object are determined by a reference mark detection pulse generator. Reference positions corresponding to the reference marks are stored in advance in a non-volatile memory. The actual position of the object is compared with a reference position stored in said non-volatile memory, each time the object to be controlled passes each of the reference marks, so that the actual position of the object is corrected in accordance with a difference, if any, between the actual position and the reference position.

Abstract: A reading system for a hybrid A-D converter having, in combination, code disk A-D converters for converting an analog quantity such as a rotation angle or the like into a digital quantity and a neighborhood absolute value detector such as an inductosyn, a resolver or the like for providing the absolute value of a rotation within a small range thereof to, thereby extend the neighborhood absolute value region. Each of the code disk A-D converters supplies an output signal l and a carry signal Cr(1) which is generated depending on whether an output signal from a lower order code disk A-D converter is included in a predetermined upper group to a corresponding one of the logical circuits which are provided so as to correspond in number to the code-disk A-D converters. The logical circuit performing the logical operation L = l .multidot. (Cr.multidot.l-1+Cr.multidot.l+1) provides a signal representative of one digit whereby the outputs from the A-D converters are prevented from errors upon carrying.

Abstract: A reference point detection pulse generator determines normally-equidistant reference points which provide references over the whole control axis range of a numerically controlled machine. On the basis of the outputs of the reference point detection pulse generator and a moving amount detection pulse generator, the position of a moving part is numerically calculated by a moving part position calculator means. The position of the moving part based on the output of the moving amount detection pulse generator is compared with that based on the output of the moving part position calculator means, and if an error is present therebetween an alarm is issued.

Abstract: A system for controlling the operation of a numerically controlled machine tool used for cutting threads on workpieces, in which means are provided so that the quality of the products may not be adversely affected even when the thread cutting operation is interrupted for some reasons incidental to the thread cutting.