Nauka i Tehnika (Oct 2015)
INFLUENCE OF SELF-TAPPING SCREW ELECTRO-ARC MACHINING ON ITS TWISTING-IN IN SPECIMENS MADE OF VARIOUS MATERIALS AND TWISTING-OUT PROCEDURE
Abstract
The paper provides an experimental evaluation pertaining to the influence of steel self-tapping screw on its twisting-in specimens made of various materials and its twisting-out process. Main principles of the investigation methodology including description of technological scheme of self-tapping screw electro-arc machining and specimens applied while executing the experiments and hardware measuring tools used for fixation of torque which has been applied to the self-tapping screw during its twisting-in in the specimen and its twisting-out process have been presented in the paper. It has been established that the self-tapping screw electro-arc machining initiates formation of dimples (holes) which have solidified metal flows along their edges. The flows give a cutting ability to the screw and so they exert an influence on the conditions of screw’s interaction with the specimen during its twisting-in and twisting-out processes.The paper presents results of experimental investigations that demonstrate an impact of self-tapping screw electro-arc machining on its twisting-in in the specimens made of various materials and twisting-out procedure. In particular, it has been ascertained that torque value applied to the self-tapping screw with modified surface during twisting-in process is less in comparison with the self-tapping screw having an initial state of its surface and in the case of its twisting-out process the value is higher. In this respect difference between the indicated torque values is increasing when material hardness of the specimen becomes higher.
