Control device and recording medium encoded with program

A control device which controls a wire electrical discharge machine having a servomotor causing a wire electrode and a workpiece to relatively move, the control device measuring a relative position of the wire electrode and the workpiece by detecting contact between the wire electrode and the workpiece which had been made to relatively move, the control device comprising a CPU, the CPU being configured to:

• set a pulse cycle of a detection voltage applied to an electrode gap between the wire electrode and the workpiece;
• control a power supply connected to the control device to apply the detection voltage to the electrode gap at the set cycle;
• control relative movement speed by way of the servomotor;
• and
• detect contact between the wire electrode and the workpiece, based on a change in the applied detection voltage detected by a sensor,
• wherein the CPU, after executing a first detection operation of contact between the wire electrode and the workpiece at a first relative movement speed and a first pulse cycle of the detection voltage applied by the power supply, executes a second detection operation of contact between the wire electrode and the workpiece, at a second relative movement speed which is slower than the first relative movement speed, and at a second pulse cycle of the detection voltage applied by the power supply which is longer than the first pulse cycle, and
• wherein the CPU, after execution of the first detection operation, and prior to execution of the second detection operation, causes the wire electrode and the workpiece to relatively move in a distancing direction.