Improving the quality of piston-type hydraulic machines

BACKGROUND: The paper discusses the issues of improving the quality of piston-type hydraulic machines. The base case is the mud pump. The service purpose of the mud pump is to supply mud.

The main problem that occurs when operating hydraulic machines of this type is increased wear of the working surfaces of the cylinder sleeves. This is mainly due to the presence of fractions in the drilling mud, which have increased abrasive properties. To increase the durability of the assembly, high-chromium alloyed cast irons of the IChKh-22 type are used as a material for making the sleeve. However, these parts are expensive. It should also be noted that high-quality cast iron has worse foundry properties compared to other types of cast iron (for example, gray cast iron).

AIM: Evaluation of the possibility of improving the quality of piston-type hydraulic machines by improving the design of the cylinder assembly.

METHODS: To improve the quality of piston-type hydraulic machines, it is proposed to use gray cast iron, which is hardened by heating in contact with a mixture of oxides of alloying elements. Considering the fact that quality is a complex property, it is reasonable to evaluate it based on a comparison of both technical and economic aspects. The complex assessment was carried out using a differential method based on technical and economic indicators: tightness of the connection of the “sleeve-rod” pair, wear rate of the surface layer of the cylinder sleeve, strength, rigidity and cost. The tightness and wear were determined by calculation using experimental data on the properties of the hardened layer, and the strength and stiffness of the bushings were determined using the finite element method.

RESULTS: The results obtained show that the proposed variant is not inferior to the basic one in terms of wear resistance and tightness, and is significantly more efficient in terms of cost. Analysis of the options was carried out without taking into account technological aspects such as processing performance and the percentage of defects. As a perspective for further research, these criteria should also be looked at.

CONCLUSION: In the course of the research, it was found that the working part of the sleeve, which is made of alloy cast iron, can be replaced with modified gray cast iron. As a result of the assessment of the quality level, it was found that the resulting quality indicator for the proposed option is higher than for the basic one. Although the specific quality indicators characterizing the functional purpose for modified cast iron are somewhat lower, the economic effect of using such bushings is significantly higher than its counterpart. Thus, the resulting indicator characterizing the quality of bushings in general for modified gray cast iron significantly exceeds its analogues.