Screw tightening construction, and screw and screw tightening tool

Abstract

The slope angle (alpha) of the arcuate portion of a fitting projection is larger than the slope angle (beta) of the arcuate portion of a recess, and the axial intermediate portion of the fitting projection is engaged with the opening edge of the recess to transmit the tightening torque; therefore, compared with the case where alpha<beta and the front end of the fitting projection is engaged with the intermediate portion of the recess, the diameter of an engaging region becomes larger, so that in the case of tightening with the same tightening torque, the force applied to the engaging region becomes smaller in inverse proportion and recess in the engaging region is suppressed, or it becomes possible to satisfactority tighten a small-diameter screw with higher tightening torque. Further, if the force applied to the engaging region becomes smaller, the component of force produced on the basis of the slope of the arcuate portion in a direction of axial separation becomes smaller, thereby suppressing the come-out of a bit rising up from the recess stabilizing the tightened state of the small-diameter screw.

Description

technical field [0001] The present invention relates to a screw fastening structure, and particularly relates to a bolt and a screw fastening tool capable of fastening a small-diameter bolt with a thread portion diameter of about 3 mm or less with a large torque. Background technique [0002] The root of screw connection is to convert the tightening torque applied to the torque transmission part into the tightening axial force of the bolt, so as to fix two or more parts and components together. Therefore, the shape of the torque transmission portion provided on the bolt and the fitting state of the screw fastening tool (pliers, etc.) that directly transmits the tightening torque must generally be considered together. Especially in recent years, various products are being thinner and thinner, and the parts used are also becoming smaller. Even bolt parts are required to be smaller and relatively higher tightening torque is required more and more. [0003] In view of this, Jap...

AI Technical Summary

Problems solved by technology

Therefore, the radial dimension of the joining part is small, and the force applied to the joining part becomes larger when tightening with the same torque, which may locally cause damage to the fitting convex part and deformation of the fitting hole, etc.

In addition, in proportion to the force applied to the joint, since the component force in the direction of axial separation becomes larger, it is easy to cause a tripping phenomenon in which the screw fastening tool floats, and the bolt connection state may become unstable.

In particular, because of deformation of the bonded portion, etc., if the portion (such as image 3 If the front end surface 28 on the outer peripheral side of the torque transmission part 22 and the front end surface 36 on the outer peripheral side of the torque transmission part 30, etc.)

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