Structure for preventing escape of jack bolts in apparatus to mechanically stress a bolt-type fastener

DETAILED DESCRIPTION The present invention provides an apparatus to stress a fastener which includes a shank part extending to a flange having a plurality of spaced-apart holes spaced about an outer peripheral part thereof to overlie a support member, and a plurality of jack bolts threadedly engaged with the holes to separately receive a torque, the jack bolts having end parts extending from the holes and adapted to abut against the support member under an applied torque to develop a stress sufficient to tension the shank part by applying a compressive reaction force against the support member.
The support member may include a washer-like member that can be pressed against a suitable face surface of the support structure.
A face surface of a washer-like member directed in a generally confronting relation to the flange on the shank part of the fastener can be hardened to withstand the force of the jack bolts, or, if desired, the face surface can be made soft relative to the material of the jack bolts to avoid upsetting contacting end faces of the jack bolts.
The flange is provided with an opening or threads to engage with a shank of a bolt, stud or shaft.
When the flange takes the form of a ring, a retainer such as a split ring, a snap ring, or interlocking fastener, is used to secure the flange to the shank.
The magnitude of the compressive force on each jack bolt is only a fractional part of the stress imparted to the shank portion of the fastener.
A nut member, or a head portion of a standard nut and bolt assembly, provides sufficient space for threaded engagement of bolts about one or more bolt circles to stress the shank part of the bolt to a magnitude that will at least equal the strength of the bolt shank.
Moreover the apparatus of the present invention is equally useful in specialized applications including a roll assembly for a rolling mill in which the roll assembly includes arbor members that are pulled together against opposite sides of a sleeve under a tremendous clamping force