Clamp device

A clamp device in which a main clamp body comprises a pair of tightening grooves each being delimited by a pair of groove-delimiting wall sections; the tightening grooves each having a U- or V-shaped transverse cross-section; and first and second lobe parts disposed in the vicinity of end portions of the tightening grooves; the main clamp body presenting a ring shape when a bolt and a nut are mounted in position on the lobe parts disposed facing each other; the bolt and the nut when screw-tightened relative to each other developing a force of fastening together at least two objects placed within the tightening grooves; wherein,neach of the first and second lobe parts comprises:a pair of sidewall sections respectively contiguous to the pair groove-delimiting wall sections that delimit the tightening groove;a curved outer end wall section interconnecting the pair of sidewall sections at an outer end of each lobe part; anda seat surface wall section contiguous to the pair of sidewall sections and to the outer end wall section; the seat surface wall section providing a seat surface for the bolt or the nut;an arcuately shaped fulcrum part being formed on the curved outer end wall section of each lobe part so as to extend along a curving direction of the outer end wall section, andend portions reaching the side wall in the fulcrum part projecting from the side wall.