Patent ID: 7328602

Claim:
A pipe expanding device for moving an operation rod by reciprocation of a piston using a cylinder, and partially pressing and extruding an inner circumference of a pipe by means of a pipe shaping unit connected thereto, the pipe expanding device comprising: a cylinder ( 10 ) having a substrate ( 11 ) coupled to a fixing plate ( 13 ) by screws ( 12 ); a hollow support pipe ( 22 ) receiving a circular support frame ( 14 ) having a movable plate ( 15 ) that reciprocates an operation rod ( 21 ) by means of the cylinder ( 10 ) by fixing a piston ( 16 ) and the operation rod ( 21 ) to an inside thereof, and also receiving the operation rod ( 21 ) with a circular section and a long ring shape at one side of the circular support frame ( 14 ); a fixing member ( 23 ) having one end ( 23 b ) having a step around the operation rod ( 21 ) and firmly coupled to one end of the support pipe by specialized welding and the other end ( 23 a ) at a vertical inner end that is partially tapered so that a moving member ( 25 ) is only partially received on a slant surface and a ring-shaped spring ( 24 ) is lifted up; a single-circumference ring-shaped spring ( 24 ) fitted into an outer circumference of the operation rod ( 21 ) wherein a steel wire made of elastic material processed with a slope to an angle at which contact portions ( 24 a )( 24 b ) are engaged with facing to extend contact length of both ends thereof is bent and wound to divide a part of its body; and a moving member ( 25 ) having one contact end ( 25 a ) tapered and corresponding to the fixing member ( 23 ) and the other end at which a cut groove ( 25 b ) receiving a screw ( 26 ) and a screw part ( 21 b ) to be engaged with the operation rod ( 21 ) on an inner circumference thereof so as to form a pipe shaping unit ( 20 ).