Features of Machining Rotor Shafts of Diesel Engine Turbochargers with a Multilayer-Coated Tool

Introduction. The paper presents the results of experimental studies of power parameters when hard alloy steels are machined with tools, the cutting units of which have multilayer hard, heat-resistant and wear-resistant coatings. The obtained data will make it possible to optimize machining hard-to-machine materials. Materials and Methods. The aim of the study is to measure the power parameters of turning products and to create experimental formulas of power parameters for different technological modes. For this purpose, a special measuring multicomponent complex was used to estimate the influence of the mode parameters on the change in the cutting force components. Results. The numerically controlled machine tool was retooled by combining it with a three-component dynamometer and tooling. The cutting unit of the tool was coated with a multi-layer hard, heat-resistant and wear-resistant coating. The tool was equipped with instruments connected to a personal computer for measuring and processing experimental data. According to the results of the study, there have been obtained graphical dependences and empirical formulas, which take into account the influence of the mode parameters on the cutting force components when machining the units of alloy steels of high hardness, heat resistance and wear resistance. Discussion and Conclusion.The study allowed us to obtain experimental formulas of cutting force components for different mode parameters when machining parts by the tool equipped with cutting plates. The plates are coated with multilayer hard and wear-resistant coatings of titanium carbonitride, aluminum oxide and nickel nitride. The coating increases significantly the hardness, heat and wears resistance of the tool cutting unit and provides quality machining.

Power-Based Estimation of Cutting Forces During Turning of Aluminium Biomass Ash Particulate Composite

Aluminum-Biomass Ash Particulate Composite is a reinforced composite material of aluminum and biomass ash particles. The composite offers significant mechanical properties advantage and low-cost advantage because of the use of waste as the reinforcement material and as a result, it is gaining increased industrial attention because of the many advantages they offer over conventional Aluminium Matrix Composites. These materials are mostly accessed on the basis of their mechanical, microstructural and chemical properties with very limited interest on their machinability relative to the base material. The specific cutting force coefficients and cutting forces of the composite were estimated during CNC turning operations and the effects of reinforcement on the machinability responses were studied. In this work, power-based force estimation approach was adopted for this purpose for the first time. This approach is less expensive compared to the dynamometric approach since it relies on adapting existing equipment developed for other purposes. This was done by measuring the electric power of the direct-drive motors of the CNC machine during the turning process and the power measurements were analyzed to obtain the force coefficients. The cutting force components were observed to decrease as the percentage rice husk ash (RHA) reinforcement increased. This agrees with known results for the composite based on the dynamometric approach. Since the cutting force components decrease with increase in reinforcement, it can be deduced that increasing RHA in the Aluminium might reduce friction at the tool-chip interface and extend tool life, in other words, improving machinability. The composite therefore promises to be more cost effective than the base material in machinability terms.

Features of virtual duplicate creation of the turning process

The interdisciplinary approach of MC-SUITE implementation of the Industry 4.0 concept and the main requirements for digital models (virtual duplicates) of cyber-physical systems regarding virtual processes compliance to the real ones and the possibility of real-time operation have been described. The main condition for creating an adequate dynamic model of technological processing system (TPS) interaction with the cutting process has been defined and a model for such interaction for the longitudinal turning has been developed. On example of developed turning process structural scheme the possibility of describing the interaction of the TPS input parameters (cutting depth and longitudinal feed) with the output parameters (deformations in the respective directions) due to changes in the model internal parameters in a form of cutting force components have been demonstrated. Such representation of the model allows virtual turning process adjusting by specifying the cutting stiffness and functional dependences for the cutting forces components based on the results of intelligent analytical processing of the monitoring results of the TPS operation.

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.

Diamond tool wear monitoring by sensory analysis in milling of absolute black granite

Diamond tools suitable for machining operations of natural stones can be divided into two groups: cutting tools, including blades, the circular blades and the wires, and the surface machining ones, involving mills and grinders, that can be of different shapes. For the stone sawing process, the most adopted tool type is the diamond mill, whose duration and performance are influenced by various elements such as: the mineralogical characteristics of the material to be machined; the working conditions such as the depth of cut, the feed rate and the spindle speed; the production process of the diamond segment and the characteristics of both the matrix and the diamond, such as the size, the type and the concentration of the diamonds and the metal bond formulation hardness. This work allows to indirectly assess the wear of sintered diamond tools by signal analysis (in time and frequency domain) of the cutting force components acquired in the process. The results obtained represent a fundamental step for the development of a sensory supervision system capable of assessing the tool wear and hence to modify the process parameters in process, in order to optimize cutting performance and tool life.

Metallurgical methods of improving the machinability of structural steels to increase the productivity of processing in the conditions of automated production

The influence of non-metallic inclusions on the main indicators of steel machinability is investigated. The influence of non-metallic inclusions on the cutting force is determined. Generalized formulas for calculating tool life, cutting speed and cutting force components are proposed. Keywords: machinability, productivity, structural steel, non-metallic inclusions. [email protected]

USING ANSYS WB FOR OPTIMIZING PARAMETERS OF A TOOL FOR ROTARY FRICTION BORING

The authors developed a special design of a rotary friction tool with a self-rotating cup cutter for rotary friction boring of large holes. This paper presents the results of parametric optimization of stressed components of the rotary friction tool by virtual experiments in ANSYS WB. The authors predicted the cutting force components at the worst position of the cup cutter, which was 20 degrees as contact forces in the process of boring a large diameter hole, and built a design model. Using the Johnson-Cook model as the failure criterion for the elements of the mesh, projections of the cutting forces resulting from the hole processing were obtained. The relation between input and output parameters (stresses) is established, optimization criteria are specified, and optimal parameters of the tool stresses components are chosen. It was also found that the averaged values of the force at the initial moment (cutting into the workpiece) change linearly, then becoming practically constant. The idea of parametric optimization consisted in carrying out several virtual experiments, in which the possible range of variation of the basic dimensions was indicated and the optimization criteria were set, the optimal parameters of the tool design were selected from the presented candidates. The optimization method bypasses the design cycle, which is costly and time-consuming due to prototype testing and subsequent refinement.

High-Performance Face Milling of 42CrMo4 Steel: Influence of Entering Angle on the Measured Surface Roughness, Cutting Force and Vibration Amplitude

High feed Milling is a new milling method, which allows to apply high feed rates and increase machining efficiency. The method utilizes face cutters with a very small entering angle, of about 10°–20°. Thus, the cut layer cross-section is different than in traditional milling. In order to examine the high feed milling (HFM), experimental tests were conducted, preceded by an analysis of cutting zones when milling with an HF face cutter. The face milling tests of 42CrMo4 steel with the use of an HF cutter characterized by an entering angle, dependent on axial depth of cut ap and insert radius r values, as well as with a conventional face cutter with the entering angle of 45° were performed. The study focused on analyzing the vibration amplitude, cutting force components in the workpiece coordinate system, and surface roughness. The experimental tests proved, that when milling with constant cut layer thickness, the high feed cutter allowed to obtain twice the cutting volume in comparison with the conventional face cutter. However, higher machining efficiency resulted in an increase in cutting force components. Furthermore, the results indicate significantly higher surface roughness and higher vibration amplitudes when milling with the HF cutter.

Tool geometry analysis for plunge milling of lead-free CuZn-alloys

Plunge milling is a critical process step in mass manufacturing of rectangular shapes in electrical connector components. These shapes are manufactured by drilling a pilot hole and subsequent plunge milling with a radial offset (pitch) one or more times. The plunged cavity serves as guidance for the final broaching cut. In light of new legislative initiatives, the electronics industry is forced to use lead-free Cu-Zn-Alloys for mass manufacturing of these connectors. The plunging tool is deflected due to the higher cutting forces experienced in machining of lead-free CuZn-alloys in comparison to alloys with lead. This results in an offset of the milled cavity and negatively impacts tool guidance in the subsequent broaching process. Therefore, the geometric tolerances cannot be met. In this paper, the effect of tool geometry and cutting parameters on the workpiece geometry in plunge milling is investigated. The effect of the microstructure of the work-piece materials CuZn37, CuZn42 and CuZn21Si3P on the tool deflection and cutting force components is examined. The tools used vary regarding the design of the corner in terms of the corner chamfer and the inner shaft thickness. Friction between chips in the tools inner flutes and the cavity walls reduced workpiece accuracy. Improvements were achieved by reducing the width of the cutting corner chamfers, using large inner flutes and applying low cutting parameters.