Technological features of restoration of rims of support rollers for tracked vehicles
Date
2023-02-28
Journal Title
Journal ISSN
Volume Title
Publisher
Видавництво Львівської політехніки
Lviv Politechnic Publishing House
Lviv Politechnic Publishing House
Abstract
The use of tracked (caterpillar) vehicles enables us to meet the requirements
concerning harmless impact upon the environment, the considerable amounts of work to be fulfilled
being saved. In particular, as compared to wheeled vehicles, there is less pressure upon the ground;
there is also the opportunity to work in specific conditions of marshy, sandy, and low-bearing soils;
stable performance in hard climatic conditions, etc. is also possible there. A necessary and important
part of the tracked vehicle is its special suspension. Such a suspension contributes to smoother
motion of the mechanism, it also cushions shocks, and ensures transmission of motion from the
engine to the tracks. Independently of the design of the suspension, there are always several couples
of support rollers. These rollers make up the intermediate link between the mover and the carrier
frame, they transmit not only great weight but also the created loading, they guide the tractor’s
caterpillars, etc. In the course of their work, the support rollers of tracked vehicles experience
intensive wear and tear of the outer surface of their rims. As a result, changing them is necessary;
dismounted ones are to be repaired.
The use of restorative technology through overlaying (building up) by means of the electric
arc is considered in this paper. This enables us to ensure cost savings and to repair support rollers of
hardly loaded track vehicles. It is also possible to increase their serviceability by optimizing the
overlayed metal; in particular, by increasing the hardness of the overlayed layer and increasing its
resistance against impact and abrasive wear.
The weldability of the main metal of a support roller has been analyzed. It is shown that the
use of high-carbon material complicates the conditions for overlaying the outer rim. It is necessary
to use pre-heating to high temperatures. This reduces the tendency of the material to form hardening
structures and cracks after the overlaying.
Investigations of peculiarities of overlaying a cylindrical surface of the rim of a tractor’s roller
have been conducted. In particular, the limit values of the length of a weld pool depending on the
diameter (value of wear) of the overlayed rim of a roller have been determined. It is shown that it is
necessary to carry out the displacement of the arc from the zenith. This ensures the necessary
formation of the weld-pool and the absence of spreading of the metal overlayed on the rim.
The determination of the value of heat input of overlaying a roller has been carried out, the
heat input is considered as a function of parameters of the electrode wire. Verification calculation of
the obtained values of specific power for the permissible length of the weld-pool has been
conducted. Concretization of the obtained results was carried out by taking into account the optimal
range and permissible rate of cooling in overlaying the main material of a support roller. According
to special nomograms, the dependence between the rate of cooling and the heat input of overlaying
has been established.
Especially, there were investigated the temperature conditions during overlaying the weld
beads. It is shown that heating the roller takes place at the expense of neighboring weld beads. It is
established that in overlaying at the determined values of heat input (per unit length) there can be
achieved the temperature of auto heating is sufficient for the pre-heating of a roller.
Description
Keywords
support roller of a tracked vehicle, the rim of the roller, overlaying on a roller, wear and tear of support rollers, electric-arc overlaying, heat input in welding, electrode core-wires, wear-resisting coatings, heat affected zone, heating for overlaying, hardening structures, weld pool
Citation
Technological features of restoration of rims of support rollers for tracked vehicles / Andrij Dzyubyk, Liudmyla Dzyubyk, Yaroslav Zinko, Oleh Dzhaliuk // Ukrainian Journal of Mechanical Engineering and Materials Science. — Lviv : Lviv Politechnic Publishing House, 2023. — Vol 9. — No 2. — P. 1–11.