Influence of the Microstructure of Cutting Ceramics on the Efficiency of the Machining Process

The article deals with the determination of the efficiency of a multi-bladed tool equipped with inserts made of oxide-carbide cutting ceramics, depending on the microstructural parameters of the tool material. The microstructural parameters of the oxide-carbide cutting ceramic, which affect the performance of the tool, are proposed to be determined according to the electrical resistance of the tool material. In order to implement the method for determining the working capacity of the instrument, a basic design of the device for measuring the electrical resistance of the material of the instrument is proposed. The device for measuring the electrical resistance of ceramic plates consists of a body made of a dielectric material, with channels for supplying a conductive material and a groove for installing a case with a test sample. During the test, the channels are filled with a liquid conductive material, which fills the cavity formed by the channel of the case, the groove of the case and the plate itself under test. To ensure uniform filling of the cavity, after the introduction of the liquid conductive material, metal balls are installed into the channels, which are made in such a size as to ensure free sliding along the channel, but not to let the liquid pass into the upper part of the channel. The tested ceramic plate is installed in the walls of the removable case. The walls of the removable case include electrodes, which, when the device is in operation, are inserted into a cavity with a liquid conductive material at one end, and are connected to an ohmmeter at the other. Using a device for measuring the electrical resistance of ceramic plates, it is possible to determine the operability of the tool and guarantee its operation without rejection for a certain period of time, which was confirmed by experimental research in the milling of workpieces of machine parts made of gray cast iron. Experimental studies in multi-edge machining with cutters with different values ​​of electrical resistance of ceramic plates made it possible to plot graphs of the dependence of the quality of machining during milling on the operability of the tool and on the time of the machining process.

A study of the cutting temperature during turning of hardened steels used for the manufacture of marine parts

В статье представлено решение задачи исследования температуры резания соответствующей оптимальным режимам твердого точения конструкционной легированной закаленной стали 15Х (HRC 55) применяемой для изготовления деталей машин входящих в конструкцию морских судов. В качестве параметра оптимизации принята радиальная составляющей силы резания и температура резания при обработке закаленной стали режущей керамикой. Исследовали влияние двух факторов скорости резания и подачи на оборот. Представлена методика проведения эксперимента и его результаты. На основе полученных экспериментальным путем зависимостей с помощью программы «Microsoft Office Excel» по зависимости силы резания и температуры резания от скорости резания представлены эмпирические зависимости радиальной составляющей силы резания и температуры резания от скорости резания и подачи на оборот. Определен характер влияния каждого фактора на параметр оптимизации. В итоге были определены оптимальные значения факторов, соответствующие минимальному значению радиальной составляющей силы и соответствующую этому значению температуру резания. The article presents a solution to the problem of studying the cutting temperature corresponding to the optimal modes of solid turning of structural alloy hardened steel 15KH (HRC 55) used for the manufacture of machine parts included in the design of marine vessels. The radial component of the cutting force and the cutting temperature when processing hardened steel with cutting ceramics are used as optimization parameters. The influence of two factors of cutting speed and feed rate on the turnover was investigated. The method of the experiment and its results are presented. The empirical dependences of the radial component of the cutting force and the cutting temperature on the cutting speed are presented on the basis of the experimental dependences obtained with the help of the program "Microsoft Office Excel" on the dependence of the cutting force and the cutting temperature on the cutting speed and feed per revolution. The nature of the influence of each factor on the optimization parameter is determined. As a result, the optimal values of the factors corresponding to the minimum value of the radial component of the force and the corresponding cutting temperature were determined.

Prediction of Cutting Material Durability by T = f(vc) Dependence for Turning Processes

This article is focused on the prediction of cutting material durability by Taylor’s model. To create predictive models of the durability of cutting materials in the turning process, tools made of high-speed steel, sintered carbide without coating and with Titanium nitride (TiN) coating, cutting ceramics without coating and with TiN coating were applied. The experimental part was performed on reference material C45 using conventional lathe—type of machine SU50A and computer numerical control machine—CNC lathe Leadwell T-5 in accordance with International Organization for Standardization—ISO 3685. Implementation of the least-squares method and processing of regression analysis made predictions of cutting tool behaviour in the turning process. Using the method of regression analysis, a correlation index of 93.5% was obtained, indicating the functional dependence of the predicted relationship.

Influence of Structural Parameters of Cutting Ceramics on Quality of Processing of Machine Slideways of Metal-Cutting Equipment in Selective Formation of Instrumentation

Modern methods of machining of bed slideways with the required parameters of accuracy and quality of the processed surfaces are considered in order to increase productivity in the treatment of the surface of machine stands. To improve productivity, the finishing sanding operation has been replaced with finishing milling to ensure the required roughness, flatness and parallelism. The method of replacement of technological operations as exemplified by processing of a bed made of gray cast iron of grade “СЧ-20” is studied. The priority method of increasing the productivity of the processing of machine slideways of metal-cutting equipment, based on the use of cutting ceramics during the processing of the bed as a final technological operation, is determined. Based on the microstructural characteristics of oxide-carbide cutting ceramics, a uniform method of equipping cutters with cutting inserts with equal lifespan is used to increase productivity and achieve the required surface finish. This method of the milling cutter layout allows for longer life and provides the required margin of tool accuracy as well as allows predicting premature wear of the cutting tool. The results of the work are the identification of the patterns of influence of structural parameters of cutting ceramics on the quality of machine slideways of metal-cutting equipment in the selective formation of instrumentation. Studies have shown that the quality of machining depends on the microstructure characteristics of each insert used in the machining process when using interchangeable multi-sided oxide carbide ceramic inserts. The increase in productivity and quality of machining is achieved by monitoring the microstructure of the cutting oxide-carbide ceramics.

INVESTIGATION OF CONTACT AREA AT STEEL C12M CUTTING BY MINERAL-CERAMICS VOK-71

At present there is synthesized a wide scale of tool synthetic materials and cutting ceramics. Basic regularities of a cutting process are insufficiently analyzed, the recommendations for their use are often too general and sometimes a contradictory have character. Some opinions widespread in technical literature contradict to industrial experience. In the paper there is carried out an investigation of hardened steel cutting by cutters having cutting ceramics with the use of modern physical methods such as a raster electronic microscopy and a microroentgenospectral analysis. The peculiarities of contact processes at hardened steel turning by the example of Ch12M hardened steel turning with plates of VOK-71 mineral ceramics are theoretically substantiated and experimentally confirmed. A concept of wear mechanism is formulated, a topography of worn areas and physical chemical interactions of worked and tool material at cutting are in-vestigated. Ways to increase tool life are defined and conditions for hardened steel working are recommended. It is established that at hardened steel turning with cutters of cutting ceramics the physical-stress-strain properties of tool material impact greatly tool wear-resistance.

Simulation of Physical and Mechanical Properties to Increase the Strength of the Cutting Ceramics

According to studies [1], cutting tools with plates made of cutting ceramics alloyed with carbide-forming elements have higher heat resistance than standard plates made of cutting ceramics in the delivery stage, since their properties do not meet the requirements. Cutting ceramics with the addition of a nickel alloying element to its main standard fraction has a low heat resistance. With the addition of the manganese alloying element, heat resistance and corrosion resistance and wear resistance of cutting tools equipped with cutting ceramics are reduced. The main alloying element is chromium, which, depending on its quantity, indicates increased or high heat resistance in cutting ceramics.