A thermal displacement correcting apparatus includes a correction amount estimating device and a parameter automatic selecting device that, in a machine tool having two different sets of specifications that differ due to the presence/absence of a scale and different methods of measuring the lengths of a bed and a table, estimate a thermal displacement correction amount of the machine tool of each set of specifications. The two devices store a collection of parameters for an estimated thermal displacement calculation corresponding to each of the bed, the scale, the table, and a workpiece, as a database, and select the parameters belonging to the set of specifications from the database based on machine information according to each set of specifications, calculate estimated thermal displacements of the bed, the table, and the workpiece, or also the scale, according to the selected parameters, and combine the estimated thermal displacements.

To provide a wire electric discharge machine which can appropriately perform thermal displacement correction of upper/lower guides even when the installation environment changes. Provided are a storage unit that stores temperatures of machine elements as temperature data, and a rendering unit that digitizes the installation environment and renders as environmental data. Additionally provided are a position command unit that commands a relative position of the upper/lower guides; and a relational expression calculation unit that sets the temperature data environmental data as input data, sets the relative position as training data, and calculates the relational expression by way of machine learning. Further provided are a relational expression decision unit that calculates a correction amount by substituting the temperature of the machine element into this relational expression, and in the case of error between the relative position of the upper/lower guides based on this correction amount and the relative position commanded by the position command unit being small, decides this relational expression as a formal relational expression; and a correction execution unit that performs correction on the relative position of the upper/lower guides using this relational expression.

To provide a wire electric discharge machine capable of suitably and simply performing thermal displacement correction on upper and lower guides. Provided are a storage unit that stores temperatures of machine elements and actual values for relative positions of upper and lower guides to be associated with each other as associated data; and a relational expression calculation unit that infers and calculates a relational expression between the temperature of the machine element and the relative positions of the upper and lower guides by way of machine learning with this associated data as training data. Additionally provided are a position estimation unit that substitutes temperatures of the machine element into the relational expression and calculates an estimated value for the relative position of the upper and lower guides; and a correction amount calculation unit that calculates a correction amount for the upper and lower guides, based on the estimated value for the relative position. Further provided is a correction execution unit that performs correction of the relative position of the upper and lower guides based on this correction amount.

A machine tool includes a workpiece holding unit to hold a workpiece. A tool holding unit holds a tool. At least one of the workpiece holding unit and the tool holding unit is drivingly rotatable or drivingly movable in a predetermined direction to machine the workpiece with the tool. Temperature sensors are attached to members constituting the machine tool. An estimator calculates an environmental temperature system thermal displacement amount due to a heat source outside the machine tool. A correction magnification processor calculates an environmental temperature system thermal displacement correction amount. Another estimator calculates a driving system thermal displacement amount due to a heat source in the machine tool. A thermal displacement correction amount adder obtains and outputs a total thermal displacement correction amount based on which the machine tool performs thermal displacement correction control.