Patent ID: 8753516

Claim:
A corrosion preventing apparatus comprising: a water purifying part that includes a hydrogen-ion form resin and a hydroxy-ion form resin; an anticorrosive part that includes a cation form resin and an anion form resin having anticorrosive ions supported thereon; wherein the anticorrosive ions of the anion form resin is one of nitrite ions, molybdate ions, and tungstate ions; a conductivity measuring part that measures a measured value of conductivity of a machining liquid; and a control part that controls a flow of the machining liquid to the water purifying part and the anticorrosive part on the basis of the conductivity measuring part; wherein, on the basis of predetermined first and second conductivities and the measured value measured by the conductivity measuring part, the control part performs control such that the machining liquid flows into the water purifying part and the anticorrosive part until the measured value of the machining liquid reaches the first conductivity, when the measured value reaches the first conductivity, the control part performs control such that the flow of the machining liquid into the water purifying part stops and the machining liquid flows into only the anticorrosive part, and when the measured value increases up to the second conductivity, the control part performs control such that the flow of the machining liquid into the water purifying part restarts and the machining liquid flows into the water purifying part and the anticorrosive part.