Ukrainian Journal of Mechanical Engineering and Materials Science
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Item Study of durability in the connection “cone-tungsten carbide insert” for tension dependence(Видавництво Львівської політехніки, 2023-02-28) Slipchuk, Andrii; Jakym, Roman; Bembenek, Michal; Lviv Polytechnic National University; Drohobych State Pedagogical University by name I. Franko; AGH University of Science and Technology in KrakówDuring and after the technological operation of pressing these factors significantly determine the residual stress states of tungsten carbide inserts, as well as in the areas near the holes of the cones’ crowns of the cone. The stressed state of the inserts and the magnitude of the stress concentration determine their fatigue strength of them and the durability of the inserted carbide rockblasting equipment of the cones in the area where the inserts the cone. Dimensional analysis was done for the inserts and holes in the cones of bit and it was established that size errors of component links of dimensional chains are distributed according to laws that are similar to the normal law of distribution of random variables. The test was carried out according to the criteria of Pearson and Kolmogorov. The influence of various random and systematic factors results to the dispersion of dimensions on the dimensional processing of conjugated surfaces. The amount of tension is a function of the dimensions for mating surfaces during assembly operations. Dispersion of dimensions for the component links of the dimensional chain of a press connection causes the formation of a practical field of dispersion of the closing link. Accuracy control for the closing link in the dimensional chain is impossible if there are no direct measurements of the constituent links. A mathematical model of the process of assembling “cone-tungsten carbide insert” joints was created. For this, the methods of mathematical statistics were applied in the study. It was established that the tension values have a greater influence on the force of pressing inserts into the holes of drill steels 14 NiCrMo1, when its hardness value is HRC 59–60 compared to HRC 48-50. This dependence has a linear character within the limits of the studied tension values. The established relationships make it possible to reasonably and most accurately form selective groups of inserts and mark holes for them. This method significantly reduces losses in the production of drilling tools.Item Improvement in the construction of the “Tungsten carbide insert cutter – cone” joint for tricone drill bits(Видавництво Львівської політехніки, 2022-02-22) Slipchuk, Andrii; Jakym, Roman; Novitskyi, Jurii; Lviv Polytechnic National University; Drohobych State Pedagogical University by name I. FrankoMeet a claim is quite difficult in real production, even in specialized drilling manufacturers. Therefore, the development of reliable criteria for approaches to improving the technology of tricone drill bits is an urgent problem. This is great practical importance for domestic enterprise. The task is set to create rock-destroying insert in the basis of the developed construction. This allows you to increase the reliability of the connection between the cutter insert and the body of the cone. Favourable conditions should be provided for the rational distribution of contact stresses in conjugate surfaces “carbide cutter insert – bush – body of cone”. Crucial part here is required rigidity of the carbide cutter insert. Advanced requirements are placed on them regardless of the design and dimension-type of tricone drill bits. They must have higher requirements such as: high reliability, durability of responsible elements of support and rock-destroying equipment, productivity, ability is stand destructive forces and torque are brought through a bit for influence on a face. This increases the reliability of its connection with the body of the drill bit. Requirements apply to the design to provide favorable conditions for the rational distribution of contact stresses in conjugate surfaces “carbide cutter – bush – body of the bit cone”. The obtained results of stress state modeling indicate that, as expected, with the same forces acting on the insert cutter from 42 kN to 57 kN, the most intense place on the cone will be the “collar” near the cutter. The intensity of stress will be up to 1050 MPa in this place for cones with serial rock-destroying equipment. At the same time, the intensity of stress will be up to 900 MPa for cones with developed destructive equipment, this is 14 % less.Item Evaluation of the permissible moment in a roller cone drill bit providing the prescribed reliability of work(Lviv Politechnic Publishing House, 2018-01-29) Slipchuk, Andriy; Kuk, Andriy; Lviv Polytechnic National UniversityAfter analyzing the nature of the damage of surfaces was discovered the traces of the compression effect which arise along the cutters axis when squeezing it into the rock of delve. There were also founded the traces of deformation from the action of bending to the cutter, depending on the orientation of its slip on the face. We noticed the rubbing, fretting-corrosion, damage the local areas of the apertures walls caused by scrolling the cutter around its axis in the aperture of cones crown. In the case of the use of cutters with symmetrical aggravation of the rockdestructive part, the orientation of the generating line of active part of the cutter is determined by an effective angle to the axis of the crown of the cone. Calculations show that an angle of 45° is optimal. We noticed the rubbing, fretting-corrosion, damage the local areas of the apertures walls caused by scrolling the cutter around its axis in the aperture of cones crown. The analysis of types of rock-destructive equipment of cones damages has been revealed that with increasing the magnitude of the axial load on the bit, cases of splitting, destruction of hard-alloyed cutters increase. For this purpose, it is necessary to protect the drill`s crowns from cementation. If carbide cutters are located in several rows in the cone drill, then milling of the sites on cemented layer`s depth is effective. This prevents the removal of parts of cone`s crown. The allowable moment is proportional to the square of the height, so the connections which perceive the considerable bending moments cannot be performed with small values of the diameter or small height of the cutter shank.Item Lathe turning mode optimisation for parts working under conditions of cyclic loading(Publishing House of Lviv Polytechnic National University, 2016) Barandych, Catherine; Vyslouh, Sergey; Antoniuk, Victor; Tymoshenko, Oleksandr; Koval, ViktorThis work is devoted to questions of technological cyclic durability maintenance, of the material for parts working under cyclic loading conditions, by lathe processing optimization. The analysis of the impact of the surface layer quality on fatigue characteristics is described for parts operating under cyclic loads. Survey of methods for evaluating cyclic durability is completed, which showed lack of information about the mathematical relation between the cyclic durability of the part’s material and technological conditions of its production. A fatigue experimental study was carried out, the results of which allowed to create a mathematical model of cyclic durability of the material from lathe processing mode and tension cycle. The complex objective function that takes into account the dependence of cyclic durability of turning from technological conditions of handling and processing was developed. It is proposed to determine tension cycle for the most unsafe parts of a constructive element with consideration of conditions of service using the finite element method. The mathematical model of lathe processing of parts working under conditions of variable cyclic loads is developed and represented by total complex target function and system of constraints, including set of constrains on: feed, speed, strength and power of cutting, cutting precision, tool life and roughness of the workpiece. In addition, this mathematical model takes into account the actual characteristics of the material and expands its use to other materials of alloyed chromium steel. Submitted multi-criteria task is solved by using the method of sliding clearance. Steel 40Х GOST 4543-71 was used as an example for the proposed mathematical model of the part turning process, part operates under cyclic loading, and best values for feed and cutting speed are calculated.