scholarly journals Research on Chip Shear Angle and Built-Up Edge of Slow-Rate Machining EN C45 and EN 16MnCr5 Steels

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 956 ◽  
Author(s):  
Katarina Monkova ◽  
Peter Pavol Monka ◽  
Adriana Sekerakova ◽  
Jozef Tkac ◽  
Martin Bednarik ◽  
...  

One of the phenomena that accompanies metal cutting is extensive plastic deformation and fracture. The excess material is plastically deformed, fractured, and removed from the workpiece in the form of chips, the formation of which depends on the type of crack and their propagation. Even in case of the so-called ‘continuous’ chip formation there still has to be a fracture, as the cutting process involves the separation of a chip from the workpiece. Controlling the chip separation and its patterning in a suitable form is the most important problem of the current industrial processes, which should be highly automated to achieve maximal production efficiency. The article deals with the chip root evaluation of two EN C45 and EN 16MnCr5 steels, focusing on the shear angle measuring and built-up edge observation as important factors influencing the machining process, because a repeated formation and dislodgement of built-up edge unfavorably affects changes in the rake angle, causing fluctuation in cutting forces, and thus inducing vibration, which is harmful to the cutting tool. Consequently, this leads to surface finish deterioration. The planing was selected as a slow-rate machining operation, within which orthogonal and oblique cutting has been used for the comparative chips’ root study. The planned experiment was implemented at three levels (lower, basic, and upper) for the test preparation and the statistical method, and regression function was used for the data evaluation. The mutual connections among the four considered factors (cutting speed, cutting depth, tool cutting edge inclination, and rake angle) and investigated by the shear angle were plotted in the form of graphical dependencies. Finally, chips obtained from both steels types and within both cutting methods were systematically processed from the microscopic (chip root) and macroscopic (chip pattern) points of view.

1990 ◽  
Vol 112 (2) ◽  
pp. 184-189 ◽  
Author(s):  
D. V. Hutton ◽  
Qinghuan Yu

Experimental evidence is presented which indicates that the presence of a built-up edge can significantly affect the generation of acoustic emission in metal cutting. Results for machining SAE 1018 and 4140 steels show that the built-up edge can mask the generally accepted AE-cutting speed relation when cutting tools having small rake angles are used. Under cutting conditions conducive to development of a built-up edge, it is shown that increased acoustic emission is generated as a result of increased effective rake angle and corresponding increase of shear angle in the primary deformation zone. Three distinct types of built-up edge have been observed and classified as immature, periodic, or developed, according to effect on acoustic emission.


2019 ◽  
Vol 889 ◽  
pp. 87-94
Author(s):  
Nguyen Thi Quoc Dung

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.


1998 ◽  
Vol 120 (1) ◽  
pp. 13-20 ◽  
Author(s):  
R. Stevenson ◽  
D. A. Stephenson

It has been proposed several times in the metal-cutting literature that the machining process is non-unique and that the instantaneous machining conditions depend on the prior machining conditions (e.g. depth of cut, rake angle etc.). To evaluate the validity of this concept, a series of experiments was conducted using a highly accurate CNC machining center. For these experiments, the machining conditions were changed during the course of an orthogonal cutting experiment in a repeatable manner and the measured forces compared as a function of prior history. Tests were conducted on several tempers of 1100 aluminum and commercial purity zinc to evaluate the effect of material properties on the machining response. It was found that the change in measured cutting forces which could be ascribed to prior machining history was less than 3 percent and that material properties, particularly work hardening response, had no discernible effect on the magnitude of the difference.


1997 ◽  
Vol 119 (1) ◽  
pp. 86-94 ◽  
Author(s):  
D. A. Stephenson ◽  
P. Bandyopadhyay

Obtaining accurate baseline force data is often the critical step in applying machining simulation codes. The accuracy of the baseline cutting data determines the accuracy of simulated results. Moreover, the testing effort required to generate suitable data for new materials determines whether simulation provides a cost or time advantage over trial-and-error testing. The efficiency with which baseline data can be collected is limited by the fact that simulation programs do not use standard force or pressure equations, so that multiple sets of tests must be performed to simulate different machining processes for the same tool-workpiece material combination. Furthermore, many force and pressure equations do not include rake angle effects, so that separate tests are also required for different cutter geometries. This paper describes a unified method for simulating cutting forces in different machining processes from a common set of baseline data. In this method, empirical equations for cutting pressures or forces as a function of the cutting speed, uncut chip thickness, and tool normal rake angle are fit to baseline data from end turning, bar turning, or fly milling tests. Forces in specific processes are then calculated from the empirical equations using geometric transformations. This approach is shown to accurately predict forces in end turning, bar turning, or fly milling tests on five common tool-work material combinations. As an example application, bar turning force data is used to simulate the torque and thrust force in a combined drilling and reaming process. Extrapolation errors and corrections for workpiece hardness variations are also discussed.


2010 ◽  
Vol 443 ◽  
pp. 657-662
Author(s):  
Jun Zhou ◽  
Jian Feng Li ◽  
Jie Sun

In this paper, the micro-scale machining characteristics of a non-ferrous structural alloy, aluminum 7050-T7451 is investigated through a series of cutting experiments. The effects of cutting speed and undeformed chip thickness on the chip geometry, cutting ratio, effective rake angle and shear angle in orthogonal micro-scale cutting of Al 7075-T7451 are presented. Explanations for the observed trends are also given.


2004 ◽  
Vol 471-472 ◽  
pp. 196-200 ◽  
Author(s):  
P. Fu ◽  
A.D. Hope ◽  
G.A. King

Metal cutting operations constitute a large percentage of the manufacturing activity. One of the most important objectives of metal cutting research is to develop techniques that enable optimal utilization of machine tools, improved production efficiency, high machining accuracy and reduced machine downtime and tooling costs. Machining process condition monitoring is certainly the important monitoring requirement of unintended machining operations. A multi-purpose intelligent tool condition monitoring technique for metal cutting process will be introduced in this paper. The knowledge based intelligent pattern recognition algorithm is mainly composed of a fuzzy feature filter and algebraic neurofuzzy networks. It can carry out the fusion of multi-sensor information to enable the proposed intelligent architecture to recognize the tool condition successfully.


2013 ◽  
Vol 589-590 ◽  
pp. 38-44
Author(s):  
Gang Liu ◽  
Ming Chen ◽  
Peng Nan Li ◽  
Qing Zhen Bi ◽  
Bao Cai Guo

The concept of multi-constrained analysis of the cutting process is presented for the first time in the paper. The paper adopts a method to solve an important problem which is how to judge the influence of constrains during the cutting process. The research results are applied for HSS drills for cutting stainless steel. On the basis of the multi-constrained analysis combined with methods of simulations and standard experiments, the optimum methods are provided for structure, coating and cutting parameters of cutting tools. For geometric structure of tools, optimization is to increase thickness of cutting and rake angle. Coating optimization strategy is choosing high temperature hardness and low thermal conductivity coating. Optimization of cutting parameter is to adjust feed fate, then select proper cutting speed. The conclusion of paper is helpful for the cutting optimization.


2020 ◽  
Vol 10 (9) ◽  
pp. 3057
Author(s):  
Keguo Zhang ◽  
Keyi Wang ◽  
Zhanqiang Liu ◽  
Xiaodong Xu

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.


2004 ◽  
Vol 471-472 ◽  
pp. 201-205 ◽  
Author(s):  
Pu Qing Chen ◽  
Wei Xia ◽  
Zhao Yao Zhou ◽  
Wei Ping Chen ◽  
Yuan Yuan Li

Metal cutting operations constitute a large percentage of the manufacturing activity. One of the most important objectives of metal cutting research is to develop techniques that enable optimal utilization of machine tools, improved production efficiency, high machining accuracy and reduced machine downtime and tooling costs. Machining process condition monitoring is certainly the important monitoring requirement of unintended machining operations. A multi-purpose intelligent tool condition monitoring technique for metal cutting process will be introduced in this paper. The knowledge based intelligent pattern recognition algorithm is mainly composed of a fuzzy feature filter and algebraic neurofuzzy networks. It can carry out the fusion of multi-sensor information to enable the proposed intelligent architecture to recognize the tool condition successfully.


Author(s):  
Vishnu Vardhan Chandrasekaran ◽  
Lewis N. Payton

The current study focuses on building a 2-Dimensional finite element model to simulate the orthogonal machining process under a dry machining environment in a commercially available FEA solver LS DYNA. One of the key objectives of this thesis is to carefully document the use of LS Dyna to model metal cutting, allowing other researchers to more quickly build on this work. Actual force data is obtained using an Orthogonal Tube Turning apparatus that has been statistically validated to an accuracy of 99+%. The work material used in this study is Aluminum 6061-T6 alloy. The tool material is tool steel, which is modeled as a rigid body. A Plastic Kinematic Material Hardening model is used to define the work material. Chip formation is based on the effective failure plastic strain. A constant coefficient of friction between the tool and work piece is used, obtained from the actual experimental results. The simulation is carried out with the same constant velocity, different rake angles and depth cuts as in the real world experiment. The cutting force and thrust force values obtained for each combination of rake angle and cut depth are validated against the experimental data obtained at Auburn University. The resulting model is considered valid enough to use for sensitivity analysis of the metal cutting process in aluminum alloy 6061-T6 in the university environment. The model is available publicly to any university from a website provided.


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