Optimizing the mode of contact butt welding of railway rails

Abstract

Optimization of the technological process of manufacturing long-length rail lashes is a difficult task, since in addition to a large number of operations, the equipment used today for contact butt welding of railway rails by pulsating reflow has a large number of technical parameters (input factors) affecting the quality of the resulting welded joint (output factors). Such a number of parameters does not allow us to fully select the optimal welding modes and leads to the impossibility of using a full or fractional factor experiment. In the work, data processing of 79 experimental welds was carried out using regression analysis. The main stages of the welding process are highlighted: the first stage is melting; the second stage is melting, forcing, precipitation. Based on the obtained oscillograms of the welding process on the K1100 rail welding machine, average values of current, voltage, speed of movement of the movable bed were obtained at various stages of melting, as well as precipitation forces, precipitation time under current, precipitation paths at the last stage when welding R65 rails of the DT350 category. The obtained regression equations determining the results of tests for static three-point bending were analyzed and unsatisfactory parameters according to the Student’s t-criterion were excluded from them. These equations in the end take into account the influence of each technological stage of the process of contact butt welding of railway rails on the output properties and the model is adequate according to the Fischer’s F-criterion. With the help of these regression models, the recommended modes of contact butt welding by pulsating reflow were obtained and their testing was carried out at a rail welding company.