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Reply to comments on “Transition from ploughing to cutting during machining with blunt tools”
387
together with the reverse position leading to negative errors, would tend to provide more precision. Unfortunately this was not done and therefore higher values of the neutral point angle (28” - 33”) were obtained than the actual values. The values of the critical rake angles (-62” - -57”) are more positive than those reported elsewhere [4 - 61. The authors’ reasons for the discrepancy between theory and experiment are not unconvincing. I agree with their proposal that the tool edge friction conditions and tool edge radius affect the value of the neutral point angle. That is why any analytical determination of that angle, even if valid, is deemed to be approximate.
1 P. K. Basuray, B. K. Misra and G. K. Lal, Transition from ploughing to cutting during machining with blunt tools, Wear, 43 (1977) 341. 2 P. Alhrecht, New developments in the theory of metal cutting process, J. Eng. Ind., 63 (1961) 557. 3 R. M. Toupes, An analysis of the natural sharpness radius of a cutting tool, M. SC. Thesis, Georgia Inst. Technol., Atlanta, September 1961. 4 R. Komanduri, Some aspects of machining with negative rake tools simulating grinding, Int. J. Mach. Tool Des. Res., 11 (1971) 223. 5 C. Rubenstein, F. K. Grozman and F. Koenigsberger, Force measurements during cutting tests with single tools simulating the action of a single abrasive grit, Proc. Znt. Industrial Diamond Conf., Oxford, Industrial Diamond Information Bureau, London, 1966. 6 K. Okushima, K. Yoshiaki, S. Hagihara and S. Hashimoto, A stress analysis in the orthogonal cutting by the photo-elasto-plasticity method, Bull. Jpn Sot. F’recis. Eng., 5 (1971). (Received October 10,1979)
M. ES. ABDEL MONEIM 5 Abdel Aziz Fahmy Street, Villa Abdel Moneim, Heiiopolis, Cairo, Egypt
Reply to comments on “Transition from ploughing to cutting during machining with blunt tools” I would like to thank Dr. Abdel Moneim for his comments on our paper
111.
The natural sharpness of a cutting tool edge obviously depends on many factors and the formation of a nose radius on the cutting edge is an idealization of the actual geometry. The range of nose radii used in the experiments was exaggerated for ease in recording the transition zone. The three regions generally considered in such cases are rubbing, ploughing and cutting. The contribution of rubbing to the total energy expended in the absence of cutting is usually small and has been neglected to simplify the analysis. During cutting, all three actions occur simultaneously but the contribution of each to the total energy expended is different. Because of the stable built-up edge formation with rounded tools, the rubbing and cutting energies become significant and only these have been considered in the analysis. The analysis is far from rigorous and was presented only as an approximate solution.
388
During the experiments, cutting was terminated by reversing the feed motion and the data points presented were the average of several tests. These included feeding the workpiece in both directions. With this method fairly repeatable results were obtained. Preliminary tests were performed with reverse taper on the workpiece, i.e. by feeding the higher end of the workpiece first. These tests, however, provided rather unreliable data with practically no repeatability of results. Comparison of these results with those obtained with sharp tools is not valid since the mechanisms involved are quite different, particularly with regard to ploughing.
1 P. K. Basuray, B. K. Misra and G. K. Lal? Transition machining with blunt tools, Wear, 43 (1977) 341. (Received
February
28, 1980)
from ploughing
to cutting
during
G.K. LAL Department of Mechanical Engineering, Indian Institute of Technology, Kanpur, Utter Pradesh, India
together with the reverse position leading to negative errors, would tend to provide more precision. Unfortunately this was not done and therefore higher values of the neutral point angle (28” - 33”) were obtained than the actual values. The values of the critical rake angles (-62” - -57”) are more positive than those reported elsewhere [4 - 61. The authors’ reasons for the discrepancy between theory and experiment are not unconvincing. I agree with their proposal that the tool edge friction conditions and tool edge radius affect the value of the neutral point angle. That is why any analytical determination of that angle, even if valid, is deemed to be approximate.
1 P. K. Basuray, B. K. Misra and G. K. Lal, Transition from ploughing to cutting during machining with blunt tools, Wear, 43 (1977) 341. 2 P. Alhrecht, New developments in the theory of metal cutting process, J. Eng. Ind., 63 (1961) 557. 3 R. M. Toupes, An analysis of the natural sharpness radius of a cutting tool, M. SC. Thesis, Georgia Inst. Technol., Atlanta, September 1961. 4 R. Komanduri, Some aspects of machining with negative rake tools simulating grinding, Int. J. Mach. Tool Des. Res., 11 (1971) 223. 5 C. Rubenstein, F. K. Grozman and F. Koenigsberger, Force measurements during cutting tests with single tools simulating the action of a single abrasive grit, Proc. Znt. Industrial Diamond Conf., Oxford, Industrial Diamond Information Bureau, London, 1966. 6 K. Okushima, K. Yoshiaki, S. Hagihara and S. Hashimoto, A stress analysis in the orthogonal cutting by the photo-elasto-plasticity method, Bull. Jpn Sot. F’recis. Eng., 5 (1971). (Received October 10,1979)
M. ES. ABDEL MONEIM 5 Abdel Aziz Fahmy Street, Villa Abdel Moneim, Heiiopolis, Cairo, Egypt
Reply to comments on “Transition from ploughing to cutting during machining with blunt tools” I would like to thank Dr. Abdel Moneim for his comments on our paper
111.
The natural sharpness of a cutting tool edge obviously depends on many factors and the formation of a nose radius on the cutting edge is an idealization of the actual geometry. The range of nose radii used in the experiments was exaggerated for ease in recording the transition zone. The three regions generally considered in such cases are rubbing, ploughing and cutting. The contribution of rubbing to the total energy expended in the absence of cutting is usually small and has been neglected to simplify the analysis. During cutting, all three actions occur simultaneously but the contribution of each to the total energy expended is different. Because of the stable built-up edge formation with rounded tools, the rubbing and cutting energies become significant and only these have been considered in the analysis. The analysis is far from rigorous and was presented only as an approximate solution.
388
During the experiments, cutting was terminated by reversing the feed motion and the data points presented were the average of several tests. These included feeding the workpiece in both directions. With this method fairly repeatable results were obtained. Preliminary tests were performed with reverse taper on the workpiece, i.e. by feeding the higher end of the workpiece first. These tests, however, provided rather unreliable data with practically no repeatability of results. Comparison of these results with those obtained with sharp tools is not valid since the mechanisms involved are quite different, particularly with regard to ploughing.
1 P. K. Basuray, B. K. Misra and G. K. Lal? Transition machining with blunt tools, Wear, 43 (1977) 341. (Received
February
28, 1980)
from ploughing
to cutting
during
G.K. LAL Department of Mechanical Engineering, Indian Institute of Technology, Kanpur, Utter Pradesh, India