| 摘要 |
PURPOSE:To hold working accuracy by calculating the difference in the temp. of a return coolant and the reference temp. of an instrument or in atmosphere, comparing it with plural set temp. and controlling the mixture ratio of the coolant and/or the flow of the coolant. CONSTITUTION:The difference in the temp. of a return coolant and the reference temp. in the atm. or an instrument 2 is calculated and this calculation value is compared with plural set values. The mixture ratio of the coolant fed from the coolant tank 10 at the temp. close to the reference temp. and the coolant tank 11 of comparatively low temp. and the coolant amt. are adjusted by in which range this temp. exists. The adjustment of the mixture ratio and coolant amt. is ordinarily performed by switching switch valves 25, 34. In the method like this, in case of changing the respective mixture ratio and coolant amt. in two stages, for example, the setting of the cooling strength in four stages max. becomes possible by the combination of the both and more fine control corresponding to the work load can be done, so the thermal deformation of the instrument 2 can be prevented without frequently performing the switching of the switch valves 24, 34. |
