Abstract: Disclosed is a pipe expanding device for expanding a thin pipe with a small diameter using elasticity and compressing and bending characteristics of a spring. Steel wires whose opposite contact sections are processed with a slope to be engaged in parallel so that contact length of both ends thereof are extended are bent and wound to form a ring spring having a single circumference with its body being partially cut off. This ring spring is used as a mold so as to expand an outer diameter of a pipe as much as a circumferential length of both ends that are widened rather than a normal circumferential diameter due to elasticity of the spring while the ring spring presses the pipe. This pipe expanding device employing the ring spring is simple and economical and allows even an unskilled person to use it easily.

Abstract: Disclosed is a pipe expanding device for expanding a thin pipe with a small diameter using elasticity and compressing and bending characteristics of a spring. Steel wires whose opposite contact sections are processed with a slope to be engaged in parallel so that contact length of both ends thereof are extended are bent and wound to form a ring spring having a single circumference with its body being partially cut off. This ring spring is used as a mold so as to expand an outer diameter of a pipe as much as a circumferential length of both ends that are widened rather than a normal circumferential diameter due to elasticity of the spring while the ring spring presses the pipe. This pipe expanding device employing the ring spring is simple and economical and allows even an unskilled person to use it easily.