The invention relates to an expansion tool for expanding tube ends. The expansion tool has an expansion mandrel and a counter-support, said expansion mandrel consisting of a tow-bar and an elastic rubber expansion element surrounding it. The counter-support supports the expansion element on the base extremity and radially surrounds it at a distance. In order to improve an expansion tool of the above-described kind, the tow-bar is anchored in a bolt fastening element and the counter-support can be impinged upon via a pressure bar element that projects beyond the bolt fastening element in the longitudinal direction of the tow-bar.
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.
