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1

Improving the contouring accuracy of a HSC linear motor milling machine

Pandilov Z., Durakbasa N., Dukovski V.

Journal of Machine Engineering

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2011

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Vol. 11, No. 4

130--137

EN

In recent years, instrumentation circular profile tests have been specified to assess the contouring accuracy of CNC machine tools. Such an instrumentation type test is the HEIDENHAIN grid encoder system, which is particularly appropriate for dynamic measurements, especially at high feed rates. In this paper influence of the position loop gain and sampling period on the contouring accuracy are effectively studied.

2

One approach towards analytical determination of the CNC machine tool servo drives position loop gain

Pandilov Z., Dukovski V.

Journal of Machine Engineering

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2009

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Vol. 9, No. 2

63--69

EN

One of the most important factors which influences the dynamical behaviour of the servo drives for CNC machine tools is position loop gain or Kv-factor. It directly influences the contouring accuracy of the machine tool. Usually position loop gain is experimentally tuned on the already assembled CNC machine tool. This paper gives one approach towards its analytical calculation. The difference between analytical calculated and experimentally obtained Kv-factor is smaller than 5%, which is completely acceptable.

3

Analytical calculation of the CNC machines servo drives position loop gain

Pandilov Z., Dukovski V.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 37, nr 2

578-583

EN

Purpose: One of the most important factors which influence on the dynamical behavior of the servo drives with rotary and linear motors for CNC machine tools is position loop gain or Kv factor. Design/methodology/approach: From the magnitude of the Kv-factor depends tracking or following error. In multi-axis contouring the following errors along the different axes may cause form deviations of the machined contours. Generally position loop gain Kv should be high for faster system response and higher accuracy, but the maximum gains allowable are limited due to undesirable oscillatory responses at high gains and low damping factor. Usually Kv factor is experimentally tuned on the already assembled machine tool. Findings: This paper presents a simple method for analytically calculation of the position loop gain Kv. A combined digital-analog models of the 6-th order (for rotary motors) and 4-th order (for linear motors) of the position loop are presented. In order to ease the calculation, the 6-th order system or 4-th order system is simplified with a second order model. With this approach it is very easy to calculate the Kv factor for necessary position loop damping. The difference of the replacement of the 6-th order system and 4-th order system with second order system is presented with the simulation program MATLAB. Analytically calculated Kv factor for the servo drives with rotary motors is function of the nominal angular frequency ů and damping D of the servo drive electrical parts (rotary motor and regulator), nominal angular frequency ům and damping Dm of the mechanical transmission elements, as well as sampling period T. Kv factor for the servo drives with linear motors is calculated as function of the nominal angular frequency ům and damping D of the linear motor servo drive electrical parts (motor and regulator) and sampling period T. Research limitations/implications: The influence of nonlinearities was taken with the correction factor Originality/value: Our investigations have proven that experimentally tuned Kv factor differs from analytically calculated Kv factor less than 10%, which is completely acceptable.

4

Analytical determination of the position loop gain for linear motor CNC machine tool

Pandilov Z.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 26, nr 2

171-174

EN

Purpose: One of the most important factors which influence on the dynamical behavior of the linear motor servo drives for CNC machine tools is position loop gain or Kv factor. Design/methodology/approach: From the magnitude of the Kv-factor depends tracking or following error. In multi-axis contouring the following errors along the different axes may cause form deviations of the machined contours. Generally position loop gain Kv should be high for faster system response and higher accuracy, but the maximum gains allowable are limited due to undesirable oscillatory responses at high gains and low damping factor. Usually Kv factor is experimentally tuned on the already assembled machine tool. Findings: This paper presents a simple method for analytically calculation of the position loop gain Kv. A combined digital-analog model of the 4-th order of the position loop is presented. In order to ease the calculation, the 4-th order system is simplified with a second order model. With this approach it is very easy to calculate the Kv factor for necessary position loop damping. The difference of the replacement of the 4-th order system with second order system is presented with the simulation program MATLAB. Analytically calculated Kv factor is function of the nominal angular frequency ω and damping D of the linear motor servo drive electrical parts (motor and regulator), as well as sampling period T. Research limitations/implications: The influence of nonlinearities was taken with the correction factor. Originality/value: Our investigations have proven that experimentally tuned Kv factor differs from analytically calculated Kv factor less than 10%, which is completely acceptable.

5

Analytical calculation of the CNC machines position loop gain

Pandilov Z., Dukovski V.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 23, nr 1

71-74

EN

Purpose: One of the most important factors which influence on the dynamical behavior of the feed drives for CNC machine tools is position loop gain or Kv factor. Design/methodology/approach: From the magnitude of the Kv-factor depends tracking or following error. In multi-axis contouring the following errors along the different axes may cause form deviations of the machined contours. Generally position loop gain Kv should be high for faster system response and higher accuracy, but the maximum gains allowable are limited due to undesirable oscillatory responses at high gains and low damping factor. Usually Kv factor is experimentally tuned on the already assembled machine tool. Findings: This paper presents a simple method for analytically calculation of the position loop gain Kv. A combined digital-analog model of the 6-th order of the position loop is presented. In order to ease the calculation, the 6-th order system is simplified with a second order model. With this approach it is very easy to calculate the Kv factor for necessary position loop damping. The difference of the replacement of the 6-th order system with second order system is presented with the simulation program MATLAB. Analytically calculated Kv factor is function of the nominal angular frequency omega e and damping De of the feed drive electrical parts (motor and regulator), nominal angular frequency omega m and damping Dm of the mechanical transmission elements, as well as sampling period T. Research limitations/implications: The influence of nonlinearities was taken with the correction factor. Originality/value: Our investigations have proven that experimentally tuned Kv factor differs from analytically calculated Kv factor only 10%, which is completely acceptable.