Machine tools which compensate for thermal deformation

A method for positioning an upright base of a machine tool along a bench extending along a main axis, comprising the steps of:

• acquiring at least one temperature value of an optical line or linear encoder arranged along the bench, wherein for the optical line a point of reference can be identified as origin of the reference system;
• detection of the movement of the reference point of the optical line;
• processing the temperature value to determine the shift value due at least to the temperature incurred by an ideal position of the optical line and to determine a correct position along the optical line depending on the ideal position and the shift value, on the basis of the linear heat expansion coefficient of the optical line and according to the shift of the reference point;
• and
• translating the upright base along the bench to the correct position.

A machine tool comprising:

• a bench extending along a main axis;
• an upright base, which surmounts the bench and is supported by it, translatable in a controllable manner along the main axis;
• an upright, fixed to the upright base and supported by it, extending mainly along a vertical axis;
• a carriage supported by the upright, translatable in a controllable manner along the vertical axis;
• carriage translation command devices suitable for controlling the imposed translation of the carriage;
• a carriage position sensor, suitable for detecting the position of the carriage along the vertical axis, comprising an optical line or linear encoder, fixed to the upright, for which a point of reference is identifiable as the origin of a reference system;
• temperature detection elements of the optical line suitable for measuring the temperature of the optical line in at least one position along the vertical axis and to generate respective temperature signals;
• detection elements for detecting the shift of the reference point of the optical line suitable for generating a point of reference shift signal;
• and
• management elements operatively connected to the temperature detection elements of the optical line and to the translation control elements of the carriage and to the point of reference shift detection elements suitable for processing the temperature signals, the point of reference shift signal and the signals of said carriage translation control elements to determine a correction signal for the carriage translation control elements.

A machine tool comprising:

• a bench extending along a main axis;
• an upright base, which surmounts the bench and is supported by it, translatable in a controllable manner along the main axis;
• an upright, fixed to the upright base and supported by it, extending mainly along a vertical axis;
• a carriage supported by the upright, translatable in a controllable manner along the vertical axis;
• a mandrel-holder, supported by the carriage, and a mandrel supported by the mandrel-holder, rotatable around a work axis, at right angles to the vertical axis and the main axis, to carry out the processing, wherein the mandrel-holder is translatable in a controlled manner in the direction of said work axis;
• a position sensor of the mandrel-holder, suitable to detect the position of the mandrel-holder along the work axis, comprising an optical line or linear encoder, fixed to the upright, for which a point of reference is identifiable as the origin of the reference system;
• temperature detection elements of the optical line suitable for detecting the temperature of the optical line in at least one position along the work axis and to generate respective temperature signals;
• detection elements for detecting the shift of the point of reference of the optical line, suitable for generating a point of reference shift signal;
• management elements operatively connected to the temperature detection elements of the optical line and to the translation control elements of the mandrel-holder, and to detection elements for detecting the shift of the point of reference, suitable for processing the temperature signals, the reference point shift signal and the signals of said control elements of the translation of the mandrel-holder to determine a correction signal for the control elements of mandrel-holder translation.