A monitoring device for monitoring an operation condition of a machine tool includes: an information acquiring section that acquires event information generated by operation of the machine tool and state information of the machine tool; a judging section that when, after generation of the event information, there has occurred a predetermined change of state of the machine tool corresponding to content indicated by the event information, judges whether or not the content indicated by the event information has been resolved, based on the event information and the state information; and a notifying section that, in the case where when there has occurred the predetermined change of state of the machine tool corresponding to the content indicated by the event information, it has been judged that the content indicated by the event information has not been resolved, re-notifies of the generated event information.

In a wire electric discharge machine of the present invention, a control variable detection apparatus is an inter-pole voltage detection apparatus and detects an average inter-pole voltage as a control variable correlating with an inter-pole distance. The wire electric discharge machine comprises a machining feed speed calculation apparatus determining a machining feed speed on the basis of a deviation between target voltage set by a target value setting apparatus 7 and the average inter-pole voltage so as to eliminate the deviation. The wire electric discharge machine further comprises a feed speed distribution apparatus and a relative movement apparatus. The inter-pole distance can be kept constant by the relative movement of a wire electrode and a workpiece made on the basis of a command of thus determined machining feed speed.

In a wire electric discharge machine of the present invention, a control variable detection apparatus is an inter-pole voltage detection apparatus and detects an average inter-pole voltage as a control variable correlating with an inter-pole distance. The wire electric discharge machine comprises a machining feed speed calculation apparatus determining a machining feed speed on the basis of a deviation between target voltage set by a target value setting apparatus 7 and the average inter-pole voltage so as to eliminate the deviation. The wire electric discharge machine further comprises a feed speed distribution apparatus and a relative movement apparatus. The inter-pole distance can be kept constant by the relative movement of a wire electrode and a workpiece made on the basis of a command of thus determined machining feed speed.

An electric discharge machine includes an electrode, a shaft-feed driving unit that, a voltage/current applying unit, a shaft-feed control unit that causes the shaft-feed driving unit to perform a jump operation, and a machining-condition setting and changing unit that sets a voltage applied between the electrode and a workpiece and an electric current flowing between the electrode and the workpiece. The machining-condition setting and changing unit determines whether the electric discharge between the electrode and the workpiece stabilizes after the jump operation ends and, in at least a part of a period before determining that the electric discharge stabilizes, sets at least one of the voltage and the electric current to a condition in which electric discharge more easily occurs than in the condition in applying the electric discharge machining.

An electric discharge machine includes an electrode, a shaft-feed driving unit that, a voltage/current applying unit, a shaft-feed control unit that causes the shaft-feed driving unit to perform a jump operation, and a machining-condition setting and changing unit that sets a voltage applied between the electrode and a workpiece and an electric current flowing between the electrode and the workpiece. The machining-condition setting and changing unit determines whether the electric discharge between the electrode and the workpiece stabilizes after the jump operation ends and, in at least a part of a period before determining that the electric discharge stabilizes, sets at least one of the voltage and the electric current to a condition in which electric discharge more easily occurs than in the condition in applying the electric discharge machining.

A control device includes a speed setting unit configured to set a relative movement speed of a wire electrode with respect to a workpiece depending on the average of gap voltage per unit time, i.e., average gap voltage, and set the relative movement speed so as to move the wire electrode backward when the average gap voltage is less than a threshold, and a map compensation unit configured to change the threshold from a first threshold that is set when the amount of change in the average gap voltage is lower than a predetermined variation, to a second threshold that is greater than the first threshold, when the average gap voltage has changed in a decreasing direction and the amount of change in the average gap voltage becomes equal to or greater than the predetermined variation.

Provided is a wire electric discharge machining device and method capable of reliably terminating a short circuit between a wire electrode and a workpiece. The invention relates to a wire electric discharge machining device that starts machining of a workpiece (3) by generating an electric discharge in a machining gap formed between the workpiece and a wire electrode (2) threaded through a start hole (4) in the workpiece. The wire electric discharge machining device includes: a tension control device (56) that controls tension of the wire electrode so as to maintain the tension at a set value; a short circuit detector (57) that detects a short circuit between the wire electrode and the workpiece; and a short circuit termination system that reduces the tension of the wire electrode and vibrates the wire electrode in order to terminate a short circuit when the short circuit detector has detected the short circuit.

An electric discharge machine includes an electrode, a shaft-feed driving unit that, a voltage/current applying unit, a shaft-feed control unit that causes the shaft-feed driving unit to perform a jump operation, and a machining-condition setting and changing unit that sets a voltage applied between the electrode and a workpiece and an electric current flowing between the electrode and the workpiece. The machining-condition setting and changing unit determines whether the electric discharge between the electrode and the workpiece stabilizes after the jump operation ends and, in at least a part of a period before determining that the electric discharge stabilizes, sets at least one of the voltage and the electric current to a condition in which electric discharge more easily occurs than in the condition in applying the electric discharge machining.

An electric discharge machine includes an electrode, a shaft-feed driving unit that, a voltage/current applying unit, a shaft-feed control unit that causes the shaft-feed driving unit to perform a jump operation, and a machining-condition setting and changing unit that sets a voltage applied between the electrode and a workpiece and an electric current flowing between the electrode and the workpiece. The machining-condition setting and changing unit determines whether the electric discharge between the electrode and the workpiece stabilizes after the jump operation ends and, in at least a part of a period before determining that the electric discharge stabilizes, sets at least one of the voltage and the electric current to a condition in which electric discharge more easily occurs than in the condition in applying the electric discharge machining.

Electric discharge machining is halted during machining program operation, and a position of the machining halt point is stored. A wire electrode is retreated from the machining halt point to an arbitrary position in which a short-circuit with a workpiece is removed (retreat position), by interrupt operation in which axis movement is performed manually. Then, a return is made from the retreat position to the machining halt point while electric discharge machining is performed, machining program operation is started from the machining halt point, and electric discharge machining is restarted.