Intelligent functions of modern machine tools, including different types of software error compensation, are becoming a crucial part of the contemporary technological development in the manufacturing industry.
Generally, software error compensation includes techniques to reduce various types of machine tool errors (e.g., geometric, kinematic, dynamic, thermal, etc.) that are widely applied because of their cost-effectiveness and ease of implementation. There are almost no additional hardware costs, especially for software thermal error compensation, which is a considerable advantage. Furthermore, thermal errors account for 40% to 70% of total errors in machine tools. Therefore, the importance of software thermal error compensation continues to grow and thermal compensation, as an essential intelligent function of modern machine tools, plays a key role in precision manufacturing today.
The principle of thermal compensation is that the estimation of the relative thermal displacements between the tool and the workpiece (thermal errors) can be computed with various numerical algorithms in contrast to direct measurements of thermal errors, which reduces machine productivity due to interruption of the machining cycle during probing. Thereafter, thermal errors predicted by numerical algorithms are used as a feedback control signal to activate a controller, thus bringing the tool and workpiece to their correct relative position. Herein, the use of a feedback control system to affect the desired compensation emerges as a logical and practical solution.
The WHT 110 C machining center, produced by TOS VARNSDORF company, is equipped with a TOS Control programming environment that integrates in itself a standard machine control system and additional functions in the form of applications, which further extend the range of machine use and facilitate its full integration with the Industry 4.0 concept.
One of these functions is the unique thermal error compensation developed in cooperation with CTU in Prague. A numerical algorithm of thermal compensation is based on transfer functions. The transfer function contains the nature of the heat transfer principles. Thus, the calibration of the empirical parameters is simple, and the model is, in addition, more reliable with untested inputs and can even be used reliably to extrapolate data.
The ability to predict thermal behavior beyond the training phase with no or limited displacement measurements is very crucial and valuable because of the minimization of nonproductive manufacturing time. Furthermore, the modelling of thermally induced displacements of machine tools using TF requires fewer model inputs (typically temperatures of the machine structure, ambient temperatures or spindle speed, etc.) in comparison with commonly employed numerical algorithms.
Due to the developed software thermal error compensation, a higher accuracy of the WHT 110 C machining center is achieved by up to 75%.
For more information contact:
TOS TRADE North America, LLC
3710 Hewatt Court
Snellville, GA 30039
800-984-2620
info@tostrade.com
www.tostrade.com
Flint Machine Tools
3710 Hewatt Court
Snellville, GA 30039
800-984-2620
info@flintmachine.com
www.flintmachine.com