Analysis of the Fracture and the Repair of the Screw Spindle of a Friction Screw Press

The drive mechanism of a friction screw press consists of a screw transmission, a friction transmission and a belt transmission. Improper maintenance and axial misalignment of the screw spindle and the press are the main possible causes of screw spindle failure. The causes of the screw spindle fracture are investigated in the first part of this paper. A visual examination of the screw spindle is carried out in the first step. In the second step, the chemical composition and mechanical properties of the material from which the screw spindle of the drive mechanism is made are experimentally examined, and a metallographic examination of the fracture surfaces on the screw spindle is carried out using an electronic microscope. In the second part of this paper, the effects of screw spindle disturbances on the fracture are analyzed by applying the finite element method. The third part of this paper shows how the problem of repairing the damaged screw spindle of the drive mechanism of the friction screw press is solved. Firstly, the repair solution is described. Then, a safety check of the welded joint is presented. The final part refers to the techno-economic justification of the performed repair of the screw spindle. The obtained research results are important because the same problems or similar problems could appear in machine elements of various types of machine tools.