小ねじ強度試験機の試作と評価

概要

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A new tester for the strengths of tightened machine screws was designed for getting tightening torque, tensile force and thread torque every rotational angle. Experiment using this tester was conducted on finding the relation between tightening conditions and the strengths in the case of cross recessed head machine screws (M2 x 0.4 mm). The following results were clarified : (1) The lubrication on thread produced a larger effect for maximum tightening torque, tensile force and torque coefficient ; the use of plain washer and the lubrication of bearing face, for tightening torque and torque coefflcient ; the materials of internal thread, for tensile force and torque coefiicient ; but the Cr-plating screw, less effects for the strengths. (2) The optimum testing conditions for machine screws were able to be judged using a parameter of sensitivity of the strengths, i. e. SN-ratio, and the then errors were indicated. (3) The measurement errors of the test (e. g. about 10-20% of axial force) were confirmed to agree with that of the data already reported.
1987-12-05