A thermal displacement compensation apparatus for compensating a dimensional measurement error due to a thermal displacement of a workpiece, including a machine learning device for learning shape measurement data at the time of inspection of the workpiece, wherein the machine learning device observes image data showing the temperature distribution of the workpiece and shape data after machining as state variables representing the current state of the environment, acquires judgment data indicating the shape measurement data at the time of inspection, and learns the image data showing the temperature distribution of the workpiece and shape data after machining and the shape measurement data at the time of inspection in association with each other using the observed state variables and the acquired judgment data.

In at least one embodiment, a method of analyzing and characterizing the thermal growth of a CNC machine is provided. The method may include mounting an artifact having a bore onto a CNC machine and performing a test cycle. The test cycle may include probing the bore of the artifact to determine its location relative to the CNC machine and performing a dry cycle including one or more CNC machining processes. The method may further include calculating a deviation of the bore location from a reference relative location between the bore and CNC machine. The method may be used to improve, troubleshoot, or assess the effectiveness of CNC machine thermal compensation mechanisms. The method may start at ambient temperature and include repeating test cycles until a steady state temperature is reached in the machine.

A work method for a Cartesian machine tool includes the following steps

starting machining of a workpiece;

carrying out a machining cycle; and

carrying out a qualification operation, i.e., an operation to check a relative positioning system, on board the machine tool, by way of comparison with a positioning system with absolute reference for calibration, which is adapted to check the displacement of the indications of the positioning systems on board the machine, i.e., of the relative reference system, with respect to the positions of an absolute reference system for calibration. The method further includes the steps of

checking the outcome of the qualification operation,

If the qualification operation is passed successfully, then proceed with an operation to measure the workpiece prior to finishing.

If the qualification is not passed, then proceed with a compensation step, which includes one or more compensation operations.

A measurement, calibration and compensation system for machine tool includes a first positioning base; two first speckle image sensors for sensing speckle positions of an object holding unit at a first XY plane and a first XZ plane of the first positioning base before and after the machine tool is started for machining; a second positioning base; two second speckle image sensors for sensing speckle positions of a cutter holding unit at a second XY plane and a second YZ plane of the second positioning base before and after the machine tool is started for machining. Thus, the thermal expansion at all axes of the machine tool can be measured in a simplified and low-cost way, and the absolute positioning coordinates of all axes of the machine tool can be calibrated in real time to avoid reduced positioning accuracy due to the thermal expansion of the multi-axis machine tool.

A thermal displacement correction device for a machine tool is provided with detection result determination unit configured to determine, based on an actual position and a reference position detected by position detection unit, whether or not the actual position is based on correct detection, correction error calculation unit configured to calculate a correction error in the actual position if it is determined that the result of detection is based on correct detection, and correction amount modification unit configured to modify a thermal displacement correction amount based on the correction error.

A method for operating a gear cutting machine comprising the following steps: machining a first workpiece (1) in the machine, wherein the first workpiece (1) heats up due to the machining, determining at least one characteristic workpiece variable in the first workpiece (1) in the heated state, wherein a measuring device of the machine is used for the determination, determining a compensation on the basis of the at least one characteristic workpiece variable of the first workpiece (1) and at least one characteristic workpiece variable of a reference workpiece, wherein the characteristic workpiece variable of the reference workpiece is determined in the machine after a steady-state temperature has been reached, at least one compensation value is determined in the course of determining the compensation, adjusting of the machine setting by taking into account the at least one compensation value, and machining a further workpiece (2) in the machine.

A position command value is compensated by predicting a thermal displacement amount of each part of a machine tool and adding a thermal displacement compensation amount which cancels the predicted thermal displacement amount to the position command value of a feed axis. This thermal displacement compensation amount is adjusted from the error amount between this compensated position command value and an actual machining point. Upon adjustment of this thermal displacement compensation amount, it is possible to determine whether to increase or decrease the thermal displacement amount based on a direction in which an operator moves a tool image or a workpiece image on a screen.