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Simulation testing of the machine tool equipped with the active feed drive

Sveda J., Valasek M., Sika Z.

Journal of Machine Engineering

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2009

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Vol. 9, No. 2

81--92

EN

The vibration of a machine tool is mainly caused by the dynamic acceleration of a motion axis and by the forces that act on it. All the disturbance forces are transmitted to the machine tool frame through the drive (motor) and its regulation loop and they excite its vibrations. Thus the achievable dynamics and machining quality is negatively influenced. There are several possibilities how to suppress the excited vibrations including the recently introduced "motor on motor" technique which is based on the serial connection of two linear motors. This paper presents new simulation results performed on the simulation model of a real machine tool. The maximal achievable tuning of the regulation loop parameters of the motion axis equipped with the "motor on motor" technique was confronted with the conventional feed drive setting. The "motor on motor" feed drive properties were also tested in the virtual machining operation mode where the real measured cutting force was used. The sensitivity analysis of the reaction force and the middle mass movement of the "motor on motor" feed drive solution to the predicted cutting force introduced to the feed drive control has been investigated. The middle mass is represented by the shared part of both linear motors which absorbs the high frequency part of the reaction force by its movement.

2

Measurement and calibration of machine tools in 6 DOFs in large workspace

Benes P., Valasek M., Sveda J.

Journal of Machine Engineering

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2009

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Vol. 9, No. 3

77--87

EN

The measurement and calibration of machine tools in the large workspace (for example 10x20x3m) and in all 6 DOFs (3 cartesian translations and 3 rotations) is not an easy task. A new device called RedCaM (Redundant Calibration and Measurement Machine) has been developed that enables simultaneously to measure all 6 DOFs in the workspace. The RedCaM machine was designed with redundant number of sensors and therefore as a parallel kinematical structure. Thus it profits from the fact that the sensor errors are not chaining. It is equipped only with the sensors and it is operated by the drives of the measured machine tool after the attachment of the platform into the machine tool spindle. The redundancy of sensors provides better accuracy, self-calibration property and very good ratio between the errors of particular sensors and the resulting error of the end effector position. This has been optimized and has proven the improved (minimized) transfer of the errors between the sensors and the position in space in 6 DOFs. In particular the used redundancy of sensors (9 sensors for 6 DOFs) enables the self-calibration (all kinematical parameters are calibrated during the first motions in the workspace) and the minimized transfer of errors between the sensors and the 6 DOFs of the platform that has been experimentally proven to be 1:1. The paper deals with the description of the modification of RedCaM for the usage in the large workspace of machine tools that are in principle unlimited.

3

Experimental testing of active feed drive

Sveda J., Valasek M., Sika Z.

Journal of Machine Engineering

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2008

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Vol. 8, No. 4

43--58

EN

The main disturbances of the machine tool frame are caused by operation of motion axes. Movement of high dynamic motion axes is connected with powerful force stroke that excite machine tool frame vibration and deteriorate machining surface quality and productivity. There are several possibilities how to suppress this vibration. This deals with the simulation and experimental testing of new advanced conception where the main motor is connected with the frame by an active element that is controlled by intelligent control technique.