Method of justification of machine parts hardening modes

Abstract

Based on an overview of methods for hardening and restoring parts of agricultural machines, it has been found that the methods currently used are highly labour intensive and are not well suited for hardening the cutting edge of tillage machine discs. A method of electromechanical hardening of ploughshare discs due to simultaneous thermal action and plastic deformation is disclosed. Electromechanical hardening modes are justified on the example of standard cylindrical samples. The developed technique contains the following stages: determining the steel grade of a part; planning of the experiment based on the plan of the full two-factor three-level experiment with selection of influences and response function; experimental hardening of laboratory samples at the installation; microstructural analysis of hardened samples; numerical processing of experiment results. Based on the optical emission analysis, it was found that the samples are made of steel 65G. The factors of influence are: current strength X1(Ir) = 800...1200 A on the reinforcing tool in the form of a roller and the pressing force X2(Fk) = 100...300 N of the tool to the part. The hardness of the surface layer Y(HRC) is adopted as the response function. Microstructural analysis showed that a layer consisting of several zones was formed on the hardened surface of the sample: white, light non-flowing and dark martensitic, passing into the ferrite-pearlite structure of the base. On the basis of multiple regression analysis, an empirical mathematical model is obtained and its graphical interpretation in the studied area of factors values is given. According to the criterion of providing wear resistance of working edges of disks, maximum hardness is achieved at current strength X1(Ir) = 1060 A and force X2(Fk) = 210 N in the contact zone. Developed technique and tested modes of electromechanical hardening are suitable for development of process of hardening of disk ploughshares of grain-grass seeders.

Surface Roughness Modeling of Hard Turning 080A67 Steel

“…Some studies were carried out to evaluate the characteristics of this steel type such as evaluating the degree of deformation when hot rolling [3], and evaluating friction coefficient [4]. Many studies have been carried out to improve the advantages of this type of steel, such as improving wear resistance by the heat treatment method [5][6][7][8], improving compressive residual stress in magnetic processing [9], developing technical solutions to produce high-quality products from the casting process [10], investigation of solutions to reduce microcracking on the surface [11], studies on the solutions to increase the hardness of the surface [12][13], etc. This type of steel is increasingly used to manufacture parts with high-quality requirements, which usually need some finished faces to assemble with other parts.…”

Improving the Quality of Friction Surface by Applying Antifriction Materials to Them

“…Agricultural producers are forced to use old equipment. The service life of machines exceeds the standard by 2-3 times [4]. The reliability indicators of such equipment are quite low.…”

Predicting the Thickness of the Hardening Coating during Diffusion Metallization of Cast Iron

“…Methods of chemical-thermal treatment are the most promising methods for hardening the surface of products made of high-strength cast iron. Methods of diffusion metallization are widely used among them [1,2,3,4]. Diffusion metallization restores parts with low wear, high surface hardness and working under conditions of friction with a variety of mating materials [5].…”