To surely expand the diameter of a fixed ring 10 for a corrosion proof core of a pipe and fix the ring 10.
Both of expansion and contraction members 31a and 31b contact in parallel via a guide shaft 33. An auxiliary member 37 can be fixed at an arbitrary position of the shaft 33 by a thumb screw 39. An engagement element 34 is fitted into a hole 16 for a tool of the fixed ring 10 in a state of approaching direction force applied to both the expansion and contraction members 31a and 31b by a spring 38. By rotating an adjusting shaft 32 by an electric drill with a torque limiter from this state to separate both the expansion and contraction members 31a and 31b and the fixed ring 10 is expanded in diameter (prescribed expansion diameter force works on the fixed ring 10) according to the separation. At this time, even if the fixed ring 10 is made into an excessively expanded diameter state by excessively rotating the adjusting shaft 32, expansion and contraction force due to the excessive rotation is absorbed by elongation and contraction of the spring 38. As a result, the fixed ring 10 has no possibility of damage, etc. due to generation of deformation distortion, etc. by expanding and contracting the fixed ring 10 in diameter more than required.
YAMAMOTO YOSHIHIKO
Higashio Masahiro
Torii Kazuhisa
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