Mathematical modeling and experimental investigation of the process of electrocontact coating on inner cylindrical surfaces of agricultural machinery

The article discusses the development and justification of a device for electrocontact coating on the inner cylindrical surfaces of worn parts of machines of the agro-industrial complex, which ensures stable and uniform pressing of the anodes. The theoretical part of the work includes a Hertz model of elastic contact interaction and a description of the distribution of contact pressure, contact resistance, and current density, which allowed us to obtain an expression for the average integral deposition rate of the coating. Experimental studies were performed according to a second-order central composite plan with a variation of the cathode current density i = 10-35 A/dm², the clamping force of the anode F = 20 - 100 N and the rotation speed of the device w = 20-80 min^-1; the deposition rate of the coating v, um/h was used as the response. It was found that the deposition rate varies in the range of 930-1180 μm/h, while the cathode current density has a rational effect, an increase in which from 8-12 to 30-35 A/dm² leads to an increase in v by 180-230 μm/h. The clamping force of the anode has a significant effect (an increase of 120-160 μm/h at F = 80-100 N), while the rotation speed of the device has a secondary, corrective effect. A quadratic regression model of the second order is constructed, which adequately describes the experimental data (R² = 0.97) and makes it possible to determine rational modes of electrocontact coating, ensuring high deposition rate and stable coating quality.