Vacuum pump, spiral plate provided with vacuum pump, rotating cylinder, and method for manufacturing spiral plate

摘要

PROBLEM TO BE SOLVED: To provide a vacuum pump which is excellent in an exhaust capacity, and can be obtained at a low cost, a spiral plate, a rotating cylinder body and a manufacturing method of the spiral plate.SOLUTION: In this vacuum pump, a spiral plate at the downstream of a slit is not arranged on an extension line of a spiral plate at the upstream of the slit, but arranged by being moved in a direction in which a clearance formed of the slit is reduced. A moving amount of the spiral plate at the downstream side is an amount at which a clearance between the spiral plates at the upstream side and the downstream side is eliminated, and the plates are overlapped on each other. When cutting out the spiral plate, a radius of a processing end mill is set smaller than a slit width of the spiral plate. The radius of the processing end mill is set smaller than a phase difference between the upstream-side spiral plate and the downstream-side spiral plate. Furthermore, chamfering processing is applied to an end part at which the slit of the spiral plate is formed.SELECTED DRAWING: Figure 3