Practical Measurement and Evaluation of Thermal Behavior of NC Lathe and its Application to Turning Process Modification

Abstract:

The measuring method for thermal effects in NC machine tools was drawn-up as ISO 230-3 in 2001. After that, this international standard was introduced as JIS B 6193 in 2003. In connection with this, the measurement of thermal effects becomes achievable also not only in a machine tool builder but in a user side. Therefore, in this research, practical measurement and evaluation of thermal behavior in CNC lathe are performed from a user's viewpoint. Primarily in the experimental measurement, the spindle speed required for turning of the workpiece for a trial-production was given as a load pattern. Then the thermal displacement between cutting tool and workpiece was measured based on the above-mentioned standard and the evaluation result was reported. Secondarily, the consideration was done for the modification of the turning process of the most influential thermal effect. The thermal behavior by applying the modified load pattern was re-measured successively, and comparative evaluation was carried out. As a result, it was verified that an extensive reduction of the thermal effects was possible in the sensitive direction to the accuracy.

• Periodical: Key Engineering Materials (Volumes 407-408)
• Pages: 59-62
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.407-408.59
• Online since: February 2009
• Authors: Masayuki Okabe, Mitsuru Sakakibara
• Keywords: CNC Lathe, Spindle System, Thermal Displacement, Turning Accuracy, Turning Process

References

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[2] J. B. Bryan: International Status of Thermal Error Research, Annals of the CIRP, Vol. 16, No. 2 (1968), pp.203-215.

[3] J. B. Bryan: International Status of Thermal Error Research, Annals of the CIRP, Vol. 39, No. 2 (1990), pp.645-656.

DOI: 10.1016/s0007-8506(07)63001-7

[4] ISO 230-3: 2001, Test code for machine tools - Part 3: Determination of thermal effects (2001).

[5] JIS B 6193: 2003, Test code for machine tools - Determination of thermal effects (2003) -40 -30 -20 -10.

[10] [20] [30] [40] [50] [60] [70] [0] [20] [40] [60] [80] 100 120 140 160 180 200 220 240 260 280 Time [min] Displacement [μm].

[15] [20] [25] [30] [35] [40] [45] [50] 55Temperature [°C] (1) (2) Δx Δy Δz Atmosphere temperature Temperature of spindle stock.

500 1000 1500 2000 2500 -20.

[20] [40] [60] [80] 100 120 140 160 180 200 220 240 260 280 Time [min] Rotational speed [min-1] (1) (2) Standard warm-up process Taper side roughing Thread side roughing Rough grooving Reverse and centering Thread side semi-finishing Finishing of thread Relief grooving of thread Threading Thread side finishing Grooving Eccentric turning Centering Taper side semi-finishing Taper side finishing Tapering Taper finishing Fig. 5 Thermal effects by standard turning process -40 -30 -20 -10.

DOI: 10.1016/s0026-0576(02)80869-8

[10] [20] [30] [40] [50] [60] [70] [0] [20] [40] [60] [80] 100 120 140 160 180 200 220 240 260 280 Time [min] Displacement [μm].

[15] [20] [25] [30] [35] [40] [45] [50] [55] Temperature [°C] (1) (2) Δz Atmosphere temperature Temperature of spindle stock.

500 1000 1500 2000 2500 -40 -20.

[20] [40] [60] [80] 100 120 140 160 180 200 220 240 260 280 Time [min] Rotation speed [min -1] Grooving Taper side finishing Finishing of thread Thread side finishing (1) (2) Fig. 6 Thermal effects by modified turning process Enough warm-up process.