scholarly journals Strain Rate of Metal Deformation in the Machining Process from a Fluid Flow Perspective

2020 ◽  
Vol 10 (9) ◽  
pp. 3057
Author(s):  
Keguo Zhang ◽  
Keyi Wang ◽  
Zhanqiang Liu ◽  
Xiaodong Xu
Keyword(s):  
Fluid Flow ◽  
Strain Rate ◽  
High Speed ◽  
Metal Cutting ◽  
Cutting Speed ◽  
Shear Plane ◽  
Cutting Process ◽  
Machining Process ◽  
Rake Face ◽  
Metal Deformation

Metal cutting speeds are getting faster with the development of high-speed cutting technology, and with the increase in cutting speed, the strain rate will become larger, which makes the study of the metal cutting process more inconvenient. At the same time, with the increase in strain rate, the dislocation movement controlling the plastic deformation mechanism of metal will change from thermal activation to a damping mechanism, which makes the metal deformation behave more like a fluid. Therefore, it is necessary to explore new ways of studying machining from the perspective of fluid flow. Based on this, a fluid model of the metal cutting process is established, and a method for calculating the strain rate is proposed from the point of view of flow. The results of the simulation and measurements are compared and analyzed. The results show that the strain rate on the rake face will be affected by the friction between the chip and tool; the nearer the distance between the chip layer and tool rake face, the bigger the strain rate will be. The strain rate in the central shear plane is much larger than in other areas along the shear plane direction, and in which two ends are the biggest. It can achieve rougher, quantitative research. This shows it is feasible to study machining from the viewpoint of fluid flow, though it still needs a lot of theoretical support and experimental confirmation.

An Integral Method to Determine Workpiece Flow Stress and Friction Characteristics in Metal Cutting

2015 ◽  
Vol 9 (6) ◽  
pp. 775-781
Author(s):  
Norfariza Wahab ◽  
◽  
Yumi Inatsugu ◽  
Satoshi Kubota ◽  
Soo-Young Kim ◽  
...  
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Cutting Forces ◽  
High Speed ◽  
Metal Cutting ◽  
Cutting Edge ◽  
Cutting Process ◽  
Machining Parameters ◽  
Friction Characteristics ◽  
High Speed Cutting

In recent times, numerical simulation techniques have been commonly used to estimate and predict machining parameters such as cutting forces, stresses, and temperature distribution. However, it is very difficult to estimate the flow stress of a workpiece and the friction characteristics at a tool/chip interface, particularly during a high-speed cutting process. The objective of this study is to improve the accuracy of the present method and simultaneously determine the characteristics of the flow stress of a workpiece and friction at the cutting edge under a high strain rate and temperature during the cutting process. In this study, the Johnson-Cook (JC) flow stress model is used as a function of strain, strain rate, and temperature. The friction characteristic was estimated by minimizing the difference between the predicted and measured results of principal force, thrust force, and shear angle. The shear friction equation was used to estimate the friction characteristics. Therefore, by comparing the measured values of the cutting forces with the predicted results from FEM simulations, an expression for workpiece flow stress and friction characteristics at the cutting edge during a high-speed cutting process was estimated.

New Development in the Theory of the Metal-Cutting Process: Part II—The Theory of Chip Formation

1961 ◽  
Vol 83 (4) ◽  
pp. 557-568 ◽  
Author(s):  
P. Albrecht
Keyword(s):  
Shear Zone ◽  
Tool Life ◽  
Chip Formation ◽  
Metal Cutting ◽  
Cutting Speed ◽  
Shear Plane ◽  
Cutting Process ◽  
Chip Formation Mechanism ◽  
Bending Stresses ◽  
Set Up

Introduction of the concept of ploughing into the metal-cutting process lead to the abandoning of the assumption of collinearity of the resultant force on tool face and on the shear plane. With this understanding the tool face force is found to produce a bending effect causing bending stresses in the shear zone. Study of the chip formation mechanism when varying cutting speed showed that increased bending action reduces the shear angle and vice versa. A set-up for the development of an analytical model of the chip formation process based on the combined effect of shear and bending stresses in the shear zone has been given. Application of the gained insight to the design of the cutting tool for maximum tool life by controlling of the chip-tool contact was suggested. Brief introduction to the study of cyclic events in chip formation and their relation to the tool life is presented.

Cutting Force and Friction Modelling in High Speed End-Milling

2015 ◽  
Author(s):  
Sunday J. Ojolo ◽  
Olumuwiya Agunsoye ◽  
Oluwole Adesina ◽  
Gbeminiyi M. Sobamowo
Keyword(s):  
Temperature Field ◽  
Temperature Distribution ◽  
Cutting Forces ◽  
High Speed ◽  
Metal Cutting ◽  
Cutting Tool ◽  
End Milling ◽  
Cutting Process ◽  
Machining Process ◽  
Work Piece

Temperature field in metal cutting process is one of the most important phenomena in machining process. Temperature rise in machining directly or indirectly determines other cutting parameters such as tool life, tool wear, thermal deformation, surface quality and mechanics of chip formation. The variation in temperature of a cutting tool in end milling is more complicated than any other machining operation especially in high speed machining. It is therefore very important to investigate the temperature distribution on the cutting tool–work piece interface in end milling operation. The determination of the temperature field is carried out by the analysis of heat transfer in metal cutting zone. Most studies previously carried out on the temperature distribution model analysis were based on analytical model and with the used of conventional machining that is continuous cutting in nature. The limitations discovered in the models and validated experiments include the oversimplified assumptions which affect the accuracy of the models. In metal cutting process, thermo-mechanical coupling is required and to carry out any temperature field determination successfully, there is need to address the issue of various forces acting during cutting and the frictional effect on the tool-work piece interface. Most previous studies on the temperature field either neglected the effect of friction or assumed it to be constant. The friction model at the tool-work interface and tool-chip interface in metal cutting play a vital role in influencing the modelling process and the accuracy of predicted cutting forces, stress, and temperature distribution. In this work, mechanistic model was adopted to establish the cutting forces and also a new coefficient of friction was also established. This can be used to simulate the cutting process in order to enhance the machining quality especially surface finish and monitor the wear of tool.

Effects of Strain Rate and Temperature in Orthogonal Metal Cutting

1966 ◽  
Vol 8 (3) ◽  
pp. 264-275 ◽  
Author(s):  
G. Boothroyd ◽  
J. A. Bailey
Keyword(s):  
Theoretical Analysis ◽  
Strain Rate ◽  
Metal Cutting ◽  
Single Phase ◽  
Orthogonal Cutting ◽  
Cutting Speed ◽  
Rake Angle ◽  
Cutting Process ◽  
Strain Rates ◽  
Continuous Chip

A new theoretical analysis of the orthogonal cutting process is described which is based on the known behaviour of a single phase metal at high strains, strain rates and temperatures. The theoretical analysis applies to the case where a continuous chip is produced under non-lubricated conditions with the absence of a built-up edge on the tool face and indicates the important parameters in the cutting process. The theory is examined experimentally and its validity established. Finally, from a knowledge of the effects of strain rate and temperature on the yield stress of a single phase metal, the theory is used to predict the effects of changes in cutting speed and tool rake angle on the tool forces and geometry of the cutting process. These predictions are compared qualitatively with the results of cutting tests.

Effects of Thermal Expansion on Surface Error in Metal Cutting

2000 ◽  
Author(s):  
Chung_sheng Wu ◽  
Chuan-Hsien Kuo ◽  
Wen-Jei Yang
Keyword(s):  
Surface Roughness ◽  
Thermal Expansion ◽  
Metal Cutting ◽  
Cutting Speed ◽  
Surface Profile ◽  
Time History ◽  
Cutting Process ◽  
Machining Process ◽  
Expansion Time ◽  
Cutting Point

Abstract An experimental study is performed to measure thermal expansion and surface roughness of 6061 aluminum workpiece subjected to a cutting process in turning on a lathe. Four capacitance probes are used to detect changes in the air gap between the probes and the surface of the workpiece during the machining process, and after the workpiece is cooled down to the initial temperature. The signal output from the probes is filtered before being fed into a data acquisition system. Operational conditions are varied. The thermal expansion-time history of the workpiece is obtained at different locations behind the cutting point, together with the filtered surface profile of the workpiece. The effects of cutting speed, flank wear length, and workpiece diameter on thermal expansion and average surface roughness are determined. A novel approach is developed to correlate thermal expansion against surface roughness, both in dimensionless form. It is disclosed that these two quantities are linearly related on a semi-logarithmic plot, with all test data falling within upper and lower limits. A quantity analogous to the elastic modulus is defined to characterize the surface roughness of materials resulting from the cutting process in turning. This approach will suggest new directions for the study of surface roughness in machining.

Fluid Characteristics of Material Flow in High Speed Metal Cutting Process

2012 ◽  
Vol 500 ◽  
pp. 544-549
Author(s):  
K.G. Zhang ◽  
Zhan Qiang Liu
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Metal Cutting ◽  
Deformation Model ◽  
Rake Face ◽  
Maximum Value ◽  
Finished Surface ◽  
Better Than ◽  
Fluid Characteristics

In high speed metal cutting momentum would be large and the strain rate can be exceedingly high, the viscosity of material must take into account in studying the chip deformation. Model the high speed machining as fluid flow is much better than as solid. A laminar flow method is applied in this paper to analyze the velocity distribution, the pressure distribution, the temperature distribution and the strain rate distribution of high speed metal cutting. Analytical results showed that a speed stagnation point is located at some distance from the tool tip on the tool rake face, on which the maximum value of the pressure occurs, with zero speed; its location influences the life of the tool and the quality of the finished surface. The value of the pressure decrease along the rake face and reaches zero at some point away from the tool tip, which is the point of separation of the chip from the tool; The value of strain rate get a rapid increase from the tool tip to the free surface corner then decreased outwards.

Finite Element Analysis of High Speed Cutting Tool

2012 ◽  
Vol 268-270 ◽  
pp. 496-499 ◽  
Author(s):  
Wei Fan ◽  
Xin Liu
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Metal Cutting ◽  
Cutting Tool ◽  
Cutting Process ◽  
Machining Process ◽  
Tool Geometry ◽  
High Speed Machining ◽  
High Speed Cutting ◽  
Finite Element Software

The cutting principle of high speed machining is analyzed, and the key technology of building high speed cutting finite element simulation model is systemic explained. By simplifying high speed cutting process, using the fastest solution of nonlinear finite element software ADINA which is development in recent years to establish the three dimensional finite element model of high speed metal cutting, and to predict the cutting force of different cutting tool geometry parameter combination of high speed cutting process, the high speed cutting processing cutting tool analysis and processing parameter optimization analysis method are put forwarded, so as to provide a new tool for the research of high speed machining process and provide basis for the cutting tool choice during high-speed nc cutting process.

Analysis and Fabrication of a Mechanical Quick-Stop for Research on Chip Formation in Hard Turning Process

2019 ◽  
Vol 889 ◽  
pp. 87-94
Author(s):  
Nguyen Thi Quoc Dung
Keyword(s):  
Chip Formation ◽  
Hard Turning ◽  
Manufacturing Industry ◽  
Metal Cutting ◽  
Cutting Speed ◽  
Cutting Process ◽  
Machining Process ◽  
Machining Parameters ◽  
Machining Processes ◽  
On Chip

Metal cutting is one of the most important machining processes in manufacturing industry. Thorough understanding of metal cutting process facilitates the optimization in selection of cutting tools and machining parameters. There are several methods used for studying phenomena in metal cutting process. Using a quick-top device is an efficient technique for investigation cutting process in which cutting action is stopped so suddenly that the “froze” specimen called the chip root honestly depicts what happened during cutting action. Design strategies of a quick-stop are accelerating cutting tool away from the workpiece or decelerating the workpiece remaining in engagement with the tool. Operation of a quick-stop device can be either mechanically or by explosive. Quick-stop devices can be utilized for various types of machining processes such as: turning, milling, drilling. This paper described the analysis, fabrication, and testing of a quick-stop device which is used for researching on chip formation in hard turning. This device has simple and safe operation which utilizes spring forces to retract the tool from workpiece during cutting. The results of performance at cutting speed of 283 m/min show that the separation distance is quite small, less than 0.2mm so that the deformations on the root chip are close to that while actual machining process. This indicates that the device has satisfied the requirements of an equipment for studying on chip formation.

Material Characterization for Metal-Cutting Force Modeling

1989 ◽  
Vol 111 (2) ◽  
pp. 210-219 ◽  
Author(s):  
D. A. Stephensen
Keyword(s):  
Shear Stress ◽  
Strain Rate ◽  
Cutting Force ◽  
Metal Cutting ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Shear Plane ◽  
Stress And Strain ◽  
Force Model ◽  
Wide Range

Widely applicable machining simulation programs require reliable cutting force estimates, which currently can be obtained only from process-dependent machinability databases. The greatest obstacle to developing a more basic, efficient approach is a lack of understanding of material yield and frictional behavior under the unique deformation and frictional conditions of cutting. This paper describes a systematic method of specifying yield stress and friction properties needed as inputs to process-independent cutting force models. Statistically designed end turning tests are used to generate cutting force and chip thickness data for a mild steel and an aluminum alloy over a wide range of cutting conditions. Empirical models are fit for the cutting force and model-independent material parameters such as the tool-chip friction coefficient and shear stress on the shear plane. Common material yield behavior assumptions are examined in light of correlations between these parameters. Results show no physically meaningful correlation between geometric shear stress and strain measures, a weak correlation between geometric stress and strain rate measures, and a strong correlation between material properties and input variables such as cutting speed and rake angle. An upper bound model is used to fit four- and five-parameter polynomial strain-rate sensitive constitutive equations to the data. Drilling torques calculated using this model and an empirical turning force model agree reasonably well with measured values for the same material combination, indicating that end turning test results can be used to estimate mean loads in a more complicated process.

Metaheuristics in Manufacturing

2018 ◽  
pp. 118-142 ◽  
Author(s):  
Mohammad Zadshakoyan ◽  
Vahid Pourmostaghimi
Keyword(s):  
Tool Wear ◽  
Metal Cutting ◽  
Cutting Speed ◽  
Cutting Process ◽  
Machining Process ◽  
Turning Process ◽  
Effective Parameters ◽  
Crater Wear ◽  
Tool Wear Estimation ◽  
Industry Automation

The state of a cutting tool is an important factor in any metal cutting process as additional costs in terms of scrapped components, machine tool breakage and unscheduled downtime result from worn tool usage. Therefore, tool wear prediction plays an important role in industry automation for higher productivity and acceptable product quality. Therefore, in order to increase the productivity of turning process, various researches have been made recently for tool wear estimation and classification in turning process. Chip form is one of the most important factors commonly considered in evaluating the performance of machining process. On account of the effect of the progressive tool wear on the shape and geometrical features of produced chip, it is possible to predict some measurable machining outputs such as crater wear. According to experimentally performed researches, cutting speed and cutting time are two extremely effective parameters which contribute to the development of the crater wear on the tool rake face. As a result, these parameters will change the chip radius and geometry. This chapter presents the development of the genetic equation for the tool wear using occurred changes in chip radius in turning process. The development of the equation combines different methods and technologies like evolutionary methods, manufacturing technology, measuring and control technology with the adequate hardware and software support. The results obtained from genetic equation and experiments showed that obtained genetic equations are correlated well with the experimental data. Furthermore, it can be used for tool wear estimation during cutting process and because of its parametric form, genetic equation enables us to analyze the effect of input parameters on the crater wear parameters.

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