Investigation of Electromagnetic Properties of Tool Hard Alloys under the Influence of High Temperatures

The article shows the developed installation for determination of temperature of maximum operability of replaceable cutting hard-alloy plates on the basis of study of change of electromagnetic properties. The method of research is given. Tests of images were carried out to time of heating of the replaceable cutting plates from solid B35 alloy. The heating temperature interval was selected according to the temperature mode of the process of cutting difficult materials. Heating was carried out to 1000˚ C. The results of the study were obtained to determine the temperature of maximum operability of replaceable cutting hard alloy plates based on the study of the change in electromagnetic properties for alloy В35 amounted to 460-730 ° С.

RESULTS OF INDUSTRIAL TESTING OF CARBIDE CUTTING TOOLS BY PULSED MAGNETIC FIELD TREATMENT AND THE EFFECT ON THE INCREASE OF THE CUTTING PROCESS EFFICIENCY

The task of increasing the efficiency of machining parts on heavy machines was determined, scientifically substantiated and solved by hardening a carbide tool the pulsed magnetic field processing (PMFP). The efficiency of machining of parts is understood as an increase in its productivity, a reduction in the cost and costs of tool materials, and an increase in instrument reliability. The working conditions of cutting tools at heavy engineering enterprises are analyzed. The wear resistance of carbide cutting tools, which have been strengthened by the PMFP, was investigated using forced test methods and modeling of the cutting process. The mechanism of changing the properties of a hard alloy under the action of a pulsed magnetic field is established. The main factors affecting the change in the wear resistance of a hard alloy under the action of a pulsed magnetic field are identified. The effect of pulsed magnetic field processing on the performance of carbide cutting tools under production conditions is investigated. The effect of hardening on productivity, cost of operation and instrumental costs is established. The interrelation of the parameters of the PMFP, the parameters of the process of machining parts and production efficiency is investigated. A statistical model has been developed that allows determining the productivity of mechanical processing depending on the properties of the tool material and the processing parameters of a pulsed magnetic field.

TECHNOLOGY OF DEPOSITION OF COATINGS FROM HARD ALLOYS ON THE WORKING SURFACES OF FRICTION UNITS

A technology has been developed for applying explosively to the surface of centrifugal pump parts for pumping overheated distillate under NPP conditions of hard alloy coatings of the CrC-Ti system, which ensures high hardness of the coatings and the strength of their connection with the surface to be coated, and the best tribotechnical materials in comparison with existing materials friction characteristics against siliconized graphite in water.

Research of the frictional interaction of a powder coating and a metal counterbody during sliding friction

Methods of metallographic analysis and profilometry are used to study the friction surfaces of wear-resistant coatings with CоAl2O4 and CuAl2O4 modifying additives of ultradispersed spinels during sliding friction with counterbodies made of VK6 hard alloy and St6 steel. To describe the frictional interaction of a powder coating with a metal counterbody during steady-state wear, a statistical model is developed based on the binomial distribution of removed particles. Keywords: coating, counterbody, sliding friction, frictional interaction, wear, statistical modeling, binomial distribution. [email protected]

DESIGN FEATURES OF CARBIDE ASSEMBLY WORKING ELEMENTS OF DEFORMING BROACHES

Разработан алгоритм и проведена оценка прочности сборных твердосплавных элементов со сплошной и дискретной рабочими поверхностями. Получены зависимости, позволяющие установить связь между конструктивными параметрами сборных деформирующих инструментов и их прочностью. Выполнены прочностные расчеты деформирующего инструмента для обработки отверстий значительного диаметра со сплошной и дискретной рабочими поверхностями. Численным моделированием, методом конечных элементов получены распределения эквивалентных напряжений в элементах инструмента и контактных напряжений по поверхности контакта твердосплавная вставка-корпус, что позволило проанализировать прочность инструмента под нагрузкой. Определены конструктивные параметры инструмента и приведены алгоритмы последовательности расчета сборных деформирующих элементов (ДЭ). Разработан алгоритм последовательности расчета сборного ДЭ для дискретного протягивания. Предложенная конструкция сборного рабочего элемента позволяет не только улучшить обрабатываемость изделия резания, но и уменьшить расход остродефицитного твердого сплава по сравнению с твердосплавным ДЭ аналогичных размеров на 6 кг. Полученные результаты можно использовать в инженерных расчетах при проектировании сборного инструмента для дискретного деформирования, а также для оценки прочности сборных инструментов, например, фрез, зенкеров, разверток при уточнении внешних нагрузок We developed an algorithm and assessed the strength of prefabricated carbide elements with solid and discrete working surfaces. We obtained dependencies that make it possible to establish a relationship between the design parameters of prefabricated deforming tools and their strength. We performed strength calculations of the deforming tool for machining holes of significant diameter with solid and discrete working surfaces. We obtained the distributions of equivalent stresses in the elements of the tool and contact stresses over the contact surface of the hard-alloy insert - body by numerical modeling, by the finite element method, which made it possible to analyze the strength of the tool under load. We determined the design parameters of the tool and here we give algorithms for the sequence of calculation of prefabricated deforming elements (DE). We developed an algorithm for the sequence of calculating the prefabricated DE for discrete broaching. The proposed design of the prefabricated working element allows not only to improve the machinability of the cutting product but also to reduce the consumption of an acutely deficient hard alloy in comparison with a hard alloy DE of similar dimensions by 6 kg. The results obtained can be used in engineering calculations when designing a prefabricated tool for discrete deformation, as well as for assessing the strength of prefabricated tools, for example, cutters, countersinks, reamers when specifying external loads

Investigation of the electrospark coating, alloying and strengthening technology

Introduction. The work objectives were the analysis and application of the technology of electrospark deposition of wear-resistant metal coatings on cutting tools or machine parts for their hardening or dimensional restoration.Materials and Methods. The technology, device and principle of operation of the modernized installation intended for electric spark application of wear-resistant metal coatings with composites T15K6, VK8 and VK6 are considered.Results. To determine the parameters of the upgraded electrospark alloying plant, experiments were carried out on hardening of polished samples made of steel 45 with hard alloy T15K6 with dimensions of 25×25×25 mm. As a result of using the experiment planning method, the possibility of selecting and adjusting the installation parameters was confirmed. The following parameters were selected for hardening samples made of steel 45 with hard alloy T15K6: current I = 1-2–A, voltage U = 40-75 V, capacitor bank capacity = 60–100 µF.Discussion and Conclusions. The use of carbon dioxide as a protective medium enables to increase the number of passes and, accordingly, the number of coating layers to twenty, to obtain a total thickness of up to 0.3 mm with a dense structure without oxides. Coatings of this thickness make it possible not only to strengthen, but also to restore the dimensions of worn machine parts. The parameters of the technological modes of electrospark alloying significantly affect the intensity of coating application and the quality of the resulting surface. A rise in the electrical parameters causes an increase in the intensity of each individual discharge and, within certain limits, contributes to an increase in the amount of the transferred coating material, as well as to deeper transformations of the coated surface in the discharge zone. Thus, an electrospark alloying plant equipped with monitoring and diagnostic tools, as well as with a protective gas supply system, can be used for hardening and restoring machine parts and cutting tools.

Evaluation of the stressed state of cutting elements of coated end-milling hard-alloy combined cutters

This paper compares stresses arising in the tool material of combined end-milling cutters and their admissible values with the purpose of preventing cutter destruction. The limit stress values of tool materials for the developed endmilling hard-alloy combined cutters having an interfaced cutting part and tailpiece were investigated. The cutting part was made of a tool-grade hard alloy, and the tailpiece was made of structural steel. To determine stresses, simulation modelling was carried out in the ANSYS and Deform software. The cutting force components were found experimentally. It was assumed that lower cutting force components lead to lower stresses in the tool material. This results in a lower probability of tool material destruction. The process of cutting the hard-to-cut stainless steel 12Kh18N10T was considered at the following parameters: a cutting speed of 70 m/min, a cutting depth of 1 mm, and a feeding of 0.1 mm/tooth. The tool material VK8 with no coating and with various coatings promoting the reduction of cutting force components was studied. It was confirmed that a combined end-milling cutter 16 mm in diameter and 92 mm long can be used to cut parts with the same accuracy as using a solid end-milling hard-alloy cutter. An increase in the length of combined cutters decreases the cutting accuracy; however, for lengths 123 and 180 mm, these cutters can be used to manufacture parts applied in general machine building. Therefore, combined end-milling cutters can compete with solid cutters in terms of the manufacturing accuracy and resilience period, which limits the existing applicability of solid cutters. The cost of combined cutters is 10–60% lower than that of solid cutters.

METHODS FOR ESTIMATING THERMFISICAL PROPERTIES OF THE "TOOL - STEEL WORKPIECE" CONTACT PAIR AND THE POSSIBILITY OF THEIR USE IN CALCULATION OF THE PARAMETERS OF THE TURNING PROCESS

The analysis of methods for assessing the properties of contact pairs "hard alloy tool - steel workpiece" with the aim of improving the reliability of the choice of turning modes in generations of CNC systems equipped with technical intelligence. The models for calculating the cutting speed, the cutting force, the value of roughness Ra, have been corrected by introducing into their structure an additional informative value about the properties of each contact pair - the thermoEMF of the trial cut.

MILLING EFFECTIVENESS INCREASE BY MEANS OF HARD-ALLOY COMPOUND END MILLING CUTTERS

The investigation purpose: the effectiveness increase of hard-alloy end milling cutters at the expense of new milling cutter design development conventionally called compound milling cutters. The problem solved during investigation: the reveal of the most efficient fields of compound milling cutter use. The scientific novelty of the work: the formation of a new kind of hard-alloy end milling cutter design, to avoid milling cutter destruction in the place of shank end mounting in the chuck of the machine a shank end is made of structural steel and soldered with a hard-alloy cutting part of the milling cutter. As a result of the investigation it was defined: a) compound milling cutters compete with monolithic milling cutters in accuracy during billet production of parts at a lower cost of milling cutters; b) a compound milling cutter with a diameter of 16 mm and a milling cutter length of 92 mm substitute successfully a monolithic milling cutter by production accuracy and ensures cost reduction of a product by 4%; c) a compound milling cutter with a length of 220 mm as compared with a monolithic milling cutter ensures product cost reduction by 38% and applicable for general aims at engineering enterprises.