Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems
Patent
1987-10-19
1989-09-12
Ro, Bentsu
Electricity: motive power systems
Positional servo systems
Program- or pattern-controlled systems
318569, 318600, G05B 1933, G05B 1929
Patent
active
048663603
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION 1. Field of the Invention
The invention relates to the optoelectronic instrumentation engineering and data processing and measurement technology, and in particular it deals with cutting process control systems for CNC (computer numerical control) metal cutting machine tools.
2. Description of the Prior Art
Known in the art is an apparatus (SU, A, 772730) for controlling a machine-jig-tool-work system comprising a long feed drive, a comparator, and a negative feedback control channel, the apparatus being designed for correcting the relative position of the tool and workpiece and thickness of the removed layer.
However, the metal machining process is only controlled by indirect parameters of elastic deformation of individual members of the machine-jig-tool-work system without taking into account wear of the tool and kinematic errors in the servo drives of the carriage so that the accuracy of manufacture of parts is low. In addition, roughness of the workpiece surface is not controlled so that the machining process is not adaptive to the part quality.
The closest known prior art is an apparatus (SU, A, 1076859) for controlling the cutting process, comprising an optical transducer mounted on a metal cutting machine tool in the zone of a tool movement, the transducer comprising a laser, a narrow-field slit diaphragm mounted in the path of the laser beam, a reference half plane extending in the plane of the axis of rotation of the workpiece, a Fourier lens and an electronic interface unit comprising a series circuit including an image receiver and an analog-to-digital converter connected to the input of a CNC device.
The apparatus is designed for measuring the amount of dimensional wear of the cutting tool and for automatically compensating for such wear by effecting the cross feed of the tool by moving the carriage by the amount of the dimensional wear.
This apparatus does not, however, allow the kinematic error in servo drives of the carriage to be controlled; roughness of the part surface is not controlled, and the carriage position is only controlled in accordance with wear of the tool.
SUMMARY OF THE INVENTION
The invention is to provide a cutting process control system for CNC metal cutting machine tools, wherein the structural arrangement of an optical transducer and electronic interface unit allows direct measurement of diameter and roughness of the profile of the workpiece surface.
This object is achieved by a cutting process control system for CNC metal cutting machine tools, comprising an optical transducer mounted on a metal cutting machine tool in the zone of movement of a tool, the transducer comprising a laser, a narrow-field slit diaphragm mounted in the path of the laser beam, a reference half plane extending in the plane of the axis of rotation of the workpiece, a Fourier lens, and an electronic interface unit comprising a series circuit including an image receiver and an analog-to-digital converter connected to the input of a CNC device. According to the invention, the optical transducer is mounted on a carriage of the metal cutting machine tool, and the reference half plane is disposed on the side opposite to the apex of the cutting wedge of the tool with respect to the workpiece so as to define, with the profile surface of the workpiece, an optically transparent slit, the length of the reference half-plane being equal to the nipping radius of the beam of the laser enabling a two-mode generation, and the electronic interface unit comprises a series circuit including a memory and a switching circuit connected between the image receiver and the analog-to-digital converter as well as a series circuit including a differentiating circuit having an input connected to the output of the image receiver and a pulse former having its outputs connected to the memory and the switching circuit.
The invention makes it possible to improve quality of manufactured parts owing to a continuous control of their diameter with a maximum error of 2 .mu.m and control of roughness of th
REFERENCES:
patent: 4234837 (1980-11-01), Winslow
patent: 4276503 (1981-06-01), Peiffert et al.
patent: 4493968 (1985-01-01), Brown
patent: 4497996 (1985-02-01), Libby et al.
patent: 4588339 (1986-05-01), Bilz
Kolomeets Sergei D.
Krivoshlykov Alexei J.
Ostafiev Vladimir A.
Tymchik Grigory S.
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