Development of a laser doppler system for in-process evaluation of diameters on computer numerical controlled turning machines

Abstract

The diameter of the workpiece is measured, while the workpiece is located on the CNC (computer numerical controlled) turning machine, using a new laser instrument and technique. The optical instrument is based on the laser Doppler principle, using an He—Ne laser as a light source. It obtains data by detecting the scattered light from the surface of a rotating workpiece, processing this data with respect to the rotation of the spindle and providing a value representing the workpiece diameter. The basic resolution of the system depends on the wavelength of the laser and geometry of the optics. Higher resolution can be achieved by obtaining the data from the workpiece surface over more than one complete revolution of the spindle. The resolution for one revolution of the spindle is 0.5μm and for ten 0.05μm. The measurement system is also integrated with the CNC turning machine, particularly for autofocusing of the instrument. The instrument is mounted on the tool holder of the CNC turning machine, which is focused by means of a tool offset parameter for non-contact measurement of each different diameter. Autofocusing is carried out using the MI5 machine tool interface unit which is already established for the Renishaw probe system, according to CNC part programming. The performance of the proposed technique and instrument is verified through the experiments.

Keywords

in-process measurement non-contact measurement control of workpiece diameter

References

Nokikov

N. I.

Makarevich

B. K.

Automatic measuring of dimensions in turning. Izmeritel'naya Tekhnika, June 1961, 6, 5–6; Translated in Measurement Techniques, December 1961, 6, 431–433.

Ivanov

B. N.

Mel'nichuk

V. A.

Measuring the diameter of cylindrical articles by the method of running a roller over their surfaces. Izmeritel'naya Tekhnika, September 1964, 9, 14–16; Translated in Measurement Techniques, September 1964, 9, 772–775.

Anon. 3 Dimensional touch trigger probes for machining centres and lathes. Commercial 16-page brochure, Renishaw Electrical Limited, Wotton-under-Edge, Gloucestershire, 1984.

Takesa

Sato

Tani

Measurement of diameter using charge coupled device (CCD). Ann. CIRP, 1984, 33(1), 377–381.

Novak

Sensing of workpiece diameter, vibration, and outoff-roundness by laser-way to automate quality control. Ann. CIRP, 1981, 30(1), 473–476.

Shiraishi

In-process control of workpiece dimension in turning. Ann. CIRP, 1979, 28(1), 333–337.

Mergler

H. W.

Sahajdak

In-process optical gauging for numerical machine tool control. In Proceedings of 3rd International Conference on Automated Inspection and Product Control, University of Nottingham, April 1978, pp. 57–64.

Shiraishi

Sato

Dimensional and surface roughness controls in a turning operation. Trans. ASME, J. Engng for Industry, 1990, 112(78), 78–83.

Fan

K. C.

Choo

Y. H.

In-process dimensional control of the workpiece during turning. Precision Engng, 1991, 13(1), 27–32.

10.

Drain

L. E.

The Laser Doppler Technique, 1980 (John Wiley, Chichester).

11.

Durst

Melling

Whitelaw

J. H.

Principles and Practice of Laser Doppler Anemometry, 2nd edition, 1981 (Academic Press, London).

12.

Lading

Wigley

Bunchave

Optical Diagnostics for Flow Processes, 1994 (Plenum, New York).

13.

Simpson

D. G.

Lamb

D. G. S.

A laser Doppler system for the measurement of torsional vibration. Report 639, National Engineering Laboratory, 1977.

14.

Wigley

The sizing of large droplets by laser anemometry. J. Physics E: Scient. Instrum., 1978, 11, 639–642.

15.

Anon. LSV–laser surface velocimeter. Commercial 6-page brochure, Polytec, UK Distributor–Lambda Photometrics Limited, Batford Mill, Harpenden, Hertfordshire, 1994.

16.

Brooker

Manual of British Standards in Engineering Metrology, 1984, pp. 30–31 (Hutchinson, London).