Gas-air heater for heating rotation parts during welding and surfacing

Abstract

Kassov V. D., Kabatsky A. V., Berezhnaya E. V., Malygina S. V. Gas-air heater for heating rotation parts during welding and surfacing // Herald of the DSEA. – 2019. – № 2 (46). – P. 17–21.

One of the important stages of the technology for surfacing massive oversized parts is their heating to the required temperature. Moreover, the inability to maintain the accepted heating parameters inevitably leads to the formation of defects in the deposited layer (cracks, delamination, etc.). The aim of the work was to improve equipment for stable and safe maintenance of the process of heating parts during welding and surfacing. The design of a gas-air heater for welding is proposed. At the same time, the inner sheet of the heater is heated by the gas-air flame of the burners, the component radiated by heat from it. Hot gases, combustion products are diverted to a safe place. Calculation of heater burners is based on their heat output. Given the inevitable heat loss during surfacing, as well as for structural reasons, three burners with a capacity of 55,000 kcal / h are installed in the heater. A check calculation of the burners was also carried out. A calculation was made for the absence of a flamethrough, which showed the safety of their use. The size of the burner outlet nozzle was also calculated. Based on the recommendations, it was found that the nozzle diameter should be 2.3 mm. The heater consists of two split halves (front and rear), which are cavities inside which burners are installed. Two burners are located in the rear half of the heater, and one in the front half. Both halves freely translationally move in the direction of the longitudinal axial line of the installation, which is convenient when installing the part for surfacing, as well as when removing it. Above and below, the halves of the heater close, forming gaps for the convenience of surfacing and moving the welding head at the top, and cleaning the flux peel and flux below. Since the torches are located in the enclosed space of the heater, the ingress of hot gases (combustion products) onto the welding head is eliminated, and the working conditions of the weld beads are improved and the quality of the metal is improved. The heater operates at high temperatures, so it is made of stainless heat-resistant sheet steel with a thickness of 4 mm. As tests have shown, the selected design of the heater allows to ensure stability and safety of the process of heating parts during welding and surfacing, significantly reduce heat loss and perform surfacing without interruptions. The use of a heater can be recommended for welding and surfacing of rotation parts in production conditions.