Metalloobrabotka № 3 (129)/2022

METAL CUTTING

Shabalin D. N., Romanov A. S., Anukhin I. V., Sitkin D. S., Solodilova N. A. Determination of wear of grinding grains by shearing and the law of its distribution

In the course of the work, the process of wear of the grinding wheel during the machining of parts was studied. The main causes of wear of the working surface of the wheel during the grinding process are named. An experimental processing of the material on a circular grinding machine was carried out. As a result of the processing of experimental data, the law of distribution of radial wear of grain tips during chipping and its parameters depending on the depth at which chipping occurs was revealed.

Keywords: abrasive processing, grinding, mathematical model, wear.

Smolkina A.A., Alexandrov A.S., Vasilkov D.V., Golikova V.V. Determination of cutting forces when milling the working surfaces of rotors of screw compressors with disc shaped cutters

The article is devoted to the determination of cutting forces when milling the working surfaces of the rotors of screw compressors with disc shaped cutters. It is a logical continuation of the work [1] published in the journal Metalloobrabotka, No. 4(124), 2021. The basis for the development of the algorithm for determining cutting forces is based on the methodology of the Rybinsk Scientific School, the heads of which are Silin S.S. and Bezylazny V.F., a detailed description of the algorithm blocks is performed: construction of a contact spot; immersion of the milling cutter tooth into the metal of a cylindrical part during milling; determination of the thickness and width of the cut; determination of the cutting force acting on the milling tooth; determination of the cutting force during multi-tooth milling. As a result of calculations, it was found that when the number of teeth of the milling cutter varies, the productivity changes. The use of a milling cutter with a number of teeth from 15, cutting occurs with two teeth, which contributes to a more uniform cutting. In comparison of single-tooth and multi-tooth milling with a maximum number of 10 and 24 teeth, respectively, the uniformity of milling increases and productivity increases by 30%. This means that the use of a tool with a large number of teeth is preferable and has a comparable force effect on the elements of the technological machining system.

Keywords: screw compressor rotor, milling, disc shaped cutters, cutting forces, algorithm.

1. A. Ivanov, V. A. Levko, O. V. Litovka Modeling and experimental development of abrasive pot treatment of the inner surface of workpieces of non-circular cross-section

The current article presented results of the study on modeling the shear flow of the working medium and the subsequent experimental testing of the inner surface of a bended tubular parts of rectangular section by an abrasive flow.

Modeling was carried out using the Shvedov-Bingham rheological model with the selected mesh quality and boundary conditions. The calculated results on the pressure distribution differ significantly from the experimental results obtained earlier. A scheme of pressure distribution is proposed for a steady flow of a medium of limited volume in a curved channel. The strength calculation of the workpiece was performed during the flow of the working medium.

Experimental testing of the process showed the effectiveness of finishing with an abrasive flow of a non-circular tubular billet made of brass alloy, taking into account the selected composition of the working medium

Keywords: abrasive flow machining, modeling, working environment, flow pressure, roughness.

1. A. Evgenieva, I. P. Nikiforov, E. A. Aleksandrov Electrical contact method for determining the degree of grinding wheel abrasion

The article proposes a method of determining the degree of grinding wheel sintering based on the measurement of transient contact electrical resistance in the cutting zone. A simulation geometric model of interaction of single abrasive grains with rough surface irregularities of the workpiece, which allows determining the actual instantaneous contact area, is developed. For grinding wheels made of white aluminium oxide critical values of contact resistance, corresponding to the moment of dressing necessity, depending on the grinding depth are determined.

Keywords: flat grinding, working profile of a wheel, grinding wheel dressing, grinding burn-on, transient contact resistance.

METAL FORMING

1. Sannikov, Т. Stoyanov The influence of design factors of tape-screw cone expanders on the process of tube expanding in thick tubesheets.

The influence of the geometric parameters of the tool in question on the qualitative characteristics of tube-tubesheet connections. Experimental comparison of tape-screw cone expanders with different angles of rotation of the rollers and different taper. Determination of optimal values of geometric parameters of the tape-screw cone expander.

Keywords: experimental evaluation, expanding, thick-walled tube, thick tubesheet. tape-screw cone expander.

MACHINES AND EQUIPMENT

Efremova E.S., Vasilkov D.V. Improvement of the sealing system of the power hydraulic cylinder

A significant part of the failures of hydraulic systems are associated with the wear of the sealing elements of hydraulic cylinders. The main reason for the malfunction of the hydraulic cylinder is the wear of rubber seals. A new design solution for the transition to modern seals made of polymer and composite materials is indispensable. For these purposes, the design of the piston, rod and cover has been modernized. A combination of piston and rod bearing and sealing assemblies made of polymer materials is proposed, providing a multiple increase in the durability of power hydraulic cylinders. The use of dirt collectors as part of the seals allowed to provide protection from contamination in fairly harsh atmospheric conditions.

Keywords: power hydraulic cylinder, rubber seals, seals made of polymer and composite materials, piston, rod, support and sealing units.

Batsko Yu. I. Corrosion protection of steel equipment operating in an aggressive environment (on the example of technological equipment in sugar factories)

Corrosion processes quite often become one of the most large-scale problems associated with the rapid wear of process equipment. In addition, today there are practically no perfect methods for providing equipment with protection against corrosion, which comes from a small degree of research into all the chemical processes that take place. This became the prerequisite for the organization of this study, focused on studying the interaction of metals used in the manufacture of equipment with some aggressive environments, which are the main causative agent of corrosion (on the example of sugar refinery equipment when interacting with juices and acids). As a result, it was revealed that a high level of wear of parts of equipment of sugar factories, subjected to aggressive conditions of corrosion processes, consists of a whole range of factors: exposure to temperatures, abrasion and erosion, the presence of aggressive additives, continuity of the production cycle. Moreover, the most significant from the point of view of the rate of occurrence of corrosion processes is the influence of an aggressive environment - diffusion juice and standard syrup. Evaluation of the effectiveness of the use of protective anti-corrosion coatings showed that they can not only reduce the rate of corrosion, but also at the same time significantly reduce the costs of the plant for the replacement of equipment.

Keywords: sugar industry, corrosion, aggressive environment, anticorrosive coating, adhesion, abrasive cleaning