METHOD FOR CONTROLLING PRESSURE OF VACUUM EXHAUST SYSTEM IN CONTINUOUS VACUUM DEPOSITION PLATING LINE

摘要

PURPOSE:To prevent the adhesive properties of a vapor deposition plated film from being reduced by always controlling the pressure of gaseous N2 incorporated in a buffer tank of a vacuum exhaust system in a continuous vacuum deposition plating line at positive pressure. CONSTITUTION:A steel sheet taken out from a pretreating furnace 10 is introduced into a vacuum deposition chamber 12 via an inlet-side inert gas chamber 15 and an inlet-side sealing roll chamber 11 equipped with sealing rolls 4 and its surface is vapor- deposited with plating metal and thereafter the steel sheet is taken out to the outside of the apparatus via an outlet-side sealing roll chamber 13 and an outlet-side inert gas chamber 16. In this case, after N2 incorporated in the inert gas chambers 15, 16 of the inlet and outlet sides is discharged with vacuum pumps P1, P2 and stored in a buffer tank 5, gaseous N2 14 purified via a booster pump 2 and a gas purifier 3 is again sent to the inert gas chambers 15, 16. In this case, the pressure of gaseous N2 incorporated in the buffer tank 5 is always maintained at positive pressure by opening and closing an on-off valve 17 provided to the other feed line 9 of gaseous N2 with a controller 18, and the adhesive properties of the plated film are prevented from being lowered by oxidation of the plated steel sheet or the like which is caused by mixing of air from the outside.