Keyword: «thermal process»

The paper studies the evolution of the thermal process during electrofusion welding of polyethylene pipes at low ambient temperatures. It is proposed to preheat the pipe assembly with a coupling by means of a built-in heater mounted in the body of the connecting part. To obtain a temperature distribution close to uniform in the heat-affected zone, alignment is carried out. The duration of heating and leveling are determined by calculation. It is proposed to control the cooling process using a built-in heater. The power of the embedded heater with controlled cooling is determined by the solution of the inverse problem of controlling the thermal regime of the technological process.

The paper proposes a study of the thermal process in a radial self-lubricating polymer sliding bearing operating in a swinging motion mode. The thermal process in a sliding bearing is described by a three-dimensional heat conduction equation in cylindrical coordinates. The technique for determining the kinematic conditions is proposed on the basis of a numerical analysis of the temperature field in the contact zone of the shaft and the bearing, under which the mathematical model of the thermal process must take into account the speed of the shaft. The results obtained can be used in thermal diagnostics of friction in real sliding bearings.

A fundamental hypothesis has been made in technology development for welding polyethylene pipes at low ambient temperatures. The priority of the thermal process is shown, which is the key for all processes occurring during welding. We propose to introduce additional preheating operations, equalize temperatures in the heat-affected zone (HAZ) to the temperature acceptable for welding, and ensure cooling of the HAZ according to a pattern typical for welding at regulated temperatures. Mathematical modeling methods are used to determine the parameters of heating, temperature equalization, the dimensions of the heat-insulating chamber, or the thickness of the layer of heat-insulating material for specific low ambient air temperatures.