The article considers the question of practicability for use of different variations of welding reinforcement in terms of technological efficiency. Solid-metal ploughshares in the as-received state and ones after welding reinforcement of their points have been experimentally investigated.
The hardness of working surface of ploughshares is very significant for their abrasive wear resistance. Knowing this mechanical property is especially important for manufacturing and hardening of ploughshares, since their wear is not uniform. In this regard, the research problems include studying of hardness distribution in the most loaded nose part of ploughshare, depending on its design and on welding reinforcement as a hardening method. Ploughshares after reinforcement and ploughshares in as-delivered condition after their taking out of service are submitted as objects of the research. Reinforcement included bead welding in the area of share point perpendicularly to the leading edge with the pitch of 30-40 mm. The validity of results was provided by measurement of four parts on each object of research. The total number of tested ploughshares was eight. Hardness was measured with a mobile hardness gage. Measurement results were recorded on Rockwell hardness scale (HRC) with subsequent conversion to Brinell hardness (HB). It is shown that for ploughshares without hardening, the hardness distribution in considered part has the non-uniform character, that is caused by the non-uniformity of processes of recrystallization because of unequal thickness of walls in separate volumes of a product. The hardness values of ploughshares in as-delivered condition are not high (230 HB maximum) and cannot provide the proper abrasive wear resistance. The lowered value of hardness (175 HB) is noted on the deepening part of a ploughshare. Application of welding reinforcement increases hardness (by 200 HB on the deepening part), that is connected with manifestation of heat hardening due to the formation of hardening structures. Traces of reinforcing beads make positive impact on the increase in hardness, which contributes to the growth of abrasive wear resistance.
Wear intensity of working surface of a part is the major factor influencing its durability. To reduce the wear of parts of working organs of tillage machines, a number of processing methods of their hardening is created; one of them is welding reinforcement. The assessment of ploughshare thickness wear and of influence of its surface reinforcement on wear intensity is carried out. Ploughshares in as-delivered condition and ploughshares after reinforcement according to three processing methods are used as objects of the research. Wear of reinforcing beads height and wear of ploughshare thickness between them are determined. Attrition of the beads occurs unevenly along the length of sock because of the high pressure of soil on ploughshare sock. It is also necessary to consider the fan-shaped soil movement along the ploughshare sock. It is shown that reinforcing beads essentially slow down the abrasive wear of ploughshare thickness between them. That is related to the fact that riffles create the conditions for the formation of fluidized layer between them, and thereby less soil particles get into contacting area. The quantity of abrasive particles contacting with working surface and their pressure on ploughshare body are decreased. When attrition of welding bead is flush with working surface, the composite surface is formed; thereon the maximum hardness is observed, which contributes to the increase in abrasive wear resistance. Traces of reinforcing beads with high degree of hardness also have a positive effect. Due to breaking-in of surface and forming of composite surface, the wear intensity decreases.
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