Patent ID: 7645412

Claim:
A method for manufacturing a sealing device for sealing an annular clearance between two members assembled to rotate relative to each other, said sealing device including a seal lip for sliding on a circumference of one of said two members, said seal lip having a sliding face extending along said circumference, an atmospheric side slope inclined to enlarge the clearance gradually between the slope and said circumference from an atmospheric side end edge of said sliding face, and a screw ridge formed along said atmospheric side slope and a portion of said screw ridge being arranged on said sliding face being formed to have a shape that two slopes constructing said portion appear to be cut off respectively from end portions on a side of the other portion of said screw ridge arranged on said atmospheric side slope so as to make a tip of said screw ridge of the portion intersect with said sliding surface, said method comprising the steps: forming a recess in a molding die for forming the sealing device corresponding to a screw shape of the screw ridge of the sealing device by only a single cutting operation of a single cutter, forming said cutter with an arcuate blade edge extending continuously constantly from one side of the cutter to an opposite side of the cutter and removing one end of the arcuate blade edge at the one side of the cutter to disrupt the continuously constant extension of the arcuate blade edge of the single cutter from the one side to the opposite side of the single cutter and thereby forming a cut-off blade edge recessed from the arcuate blade edge, and pouring an elastic material into said molding die, and vulcanizing and shaping the elastic material to obtain the sealing device.