US Patent 7114895 Machine tool provided with cooling mechanism

A spindle motor as a heating element and a spindle head having a spindle that is driven by the spindle motor are coupled to each other by a cooling flange. The cooling flange is provided with a cooling passage, the cross-sectional area of which gradually increases with distance from its gas inlet toward its gas outlet. When a high-pressure gas is injected into the cooling passage through the gas inlet, it is adiabatically expanded and cooled by the cooling passage having the gradually increasing cross-sectional area. Thus, the cooling flange restrains heat generated from the spindle motor from being transmitted to the spindle head.