Toshiba Kikai Kabushiki Kaisha

Ichiro Matsumoto

Jun Fujita

Kouichi Katoh

Minoru Hamamura

A servo motor controlling method includes: directly or indirectly detecting a position of a moving body which performs a circular-arc interpolation feeding motion by a servo motor; performing a feedback control for enabling the position of the moving body to comply with a position command; and at a quadrant changing time when a moving direction of the moving body is changed, performing torque correction on a torque command value according to a distance from a position where the moving direction is changed. By this method, a quadrant protrusion and a torque change with respect to a friction caused from a free zone at a time of reversion of a ball screw can be appropriately corrected. Especially, by performing a first torque correction for a static friction at the position where the moving direction is changed, and by performing a second torque correction for a moving friction after movement by the distance corresponding to the free zone, more appropriate correction can be obtained.

Servo motor controlling method

Upon analyzing a processing program () in an analyzer (), a numerical control apparatus extracts information about a contact position between a tool and a workpiece, and based on the information, it calculates a main spindle revolution instruction value in a main spindle revolution calculator). In a CAM system, information about the contact position between the tool and the workpiece to be supplied to the numerical control apparatus is calculated and added to the processing program.

Numerical control apparatus and CAM system

A numerical controlling unit includes: an inputting part into which a machining program is inputted; an analyzing part that analyzes the machining program to generate an instructed spindle rotational speed and calculates a spindle load ratio of a load applied to a spindle under a machining condition according to the machining program to a spindle load caused when the workpiece is machined: and a distributing part that generates, based on the machining program, a distribution amount per unit period inputted into a feed-axis servo driver. A spindle-rotational-amount-command outputting part receives the instructed spindle rotational speed and outputs a spindle-rotational-amount command for commanding a rotational amount per unit period which is inputted into a spindle driver. A cutting-load-for-judgment calculating part calculates a reference torque value based on the spindle load ratio, the distribution amount, and the spindle-rotational-amount command. A spindle-load comparing part compares the reference torque value with a load torque value which is feedback inputted by the spindle driver and outputs a tool-breakage detecting signal when the load torque value is higher than the reference torque value.

Numerical controlling unit having tool-breakage detecting function

A numerical controlling unit that accelerates or decelerates a feeder-driving system includes; an acceleration setting part that can set a volume and a timing of an acceleration that should be supplied to the feeder-driving system, based on a predetermined target condition; and a controlling part that can supply the acceleration set by the acceleration setting part to the feeder-driving system. The acceleration setting part is adapted to set: a first acceleration that starts to be supplied at a timing of starting to accelerate; and a second acceleration that has a volume and that starts to be supplied overlappedly with the first acceleration at a timing, the volume and the timing being determined so as to damp vibration of the feeder-driving system that is generated by starting to supply the first acceleration.

Numerical controlling unit

The invention relates to a numerical controlling unit that includes: a instructing part that provides a command acceleration for a servomotor, a parameter storing part that stores a threshold parameter about a load of the servomotor, and a load measuring part that measures the load of the servomotor. The load measured by the load measuring part and the threshold parameter are compared by a load comparing part, and an acceleration adjusting part changes the command acceleration for the servomotor based on a result compared by the load comparing part. A controlling part controls the servomotor based on the changed command acceleration. According to the invention, the command acceleration for the servomotor is suitably changed based on the result of comparing the load measured by the load measuring part and the threshold parameter. Thus, it can be prevented that the servomotor is subjected to an overload while using the maximum performance in feeding a work piece.

A numerical control apparatus of a machine tool capable of shortening a machining time while maintaining a machining precision of a workpiece, provided with an analyzer for analyzing a machining program defining machining process of a workpiece by the machine tool to extract information for specifying a feed speed of a cutting tool to the workpiece and cutting/non-cutting information for defining actual cutting by the cutting tool added to a cutting feed command program from the cutting feed command program contained in this machining program, a feed speed optimizer for calculating a permissible feed speed of the cutting tool in accordance with content of the cutting/non-cutting information based on the extracted information and optimizing the feed speed of the cutting tool so as to be within the permissible feed speed, and a distribution unit for calculating control commands to be distributed to the control axes of the machine tool based on the optimized feed speed.

Numerical control apparatus and control method of machine tool

The numerical controlling unit includes an inputting part for inputting an inputting program. The inputting program includes a NC program defining a relative feed speed and a relative rotational number between a tool and a work, and also includes additional machining information. The inputting part is connected to an analyzing part, which is adapted to recognize the NC program and the additional machining information respectively from the inputting program inputted by the inputting part. The analyzing part is connected to a distributing part, which is adapted to make distributing information for the tool based on the NC program recognized by the analyzing part. The analyzing part and the distributing part are connected to a fusing part, which is adapted to fuse the distributing information and the additional machining information into controlling information for the tool. According to the numerical controlling unit, a more accurate numerical control can be achieved.

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Numazu, Japan

Ichiro Matsumoto