An Analysis of the Mechanism of Orthogonal Cutting and Its Application to Discontinuous Chip Formation

1961 ◽  
Vol 83 (4) ◽  
pp. 545-555 ◽  
Author(s):  
Keiji Okushima ◽  
Katsundo Hitomi
Keyword(s):  
Chip Formation ◽  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Plastic Region ◽  
Flow Region ◽  
Shear Plane ◽  
Experimental Result ◽  
Conventional Theory ◽  
Boundary Lines ◽  
Continuous Chip

Instead of the conventional theory of the mechanics of metal cutting based on a process of shear confined to a single shear plane, the concept of flow region, a fairly large transitional deformation zone which exists between the rigid region of work and the plastic region of steady chip, was developed. The mechanics of orthogonal cutting was analyzed, theoretical equations for angles of boundary lines of the flow region and for strain in chip were deduced in the case of simple continuous chip formation and confirmed in cutting tests on lead. The concept of flow region was also applied to discontinuous chip formation, and theoretical expressions for angles of boundary lines of the flow region were ascertained to be in agreement with the experimental result for carbon steel.

A New Analysis of the Forces in Orthogonal Metal Cutting

1965 ◽  
Vol 87 (4) ◽  
pp. 480-486 ◽  
Author(s):  
J. D. Cumming ◽  
S. Kobayashi ◽  
E. G. Thomsen
Keyword(s):  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Minimum Energy ◽  
Cutting Speed ◽  
Shear Plane ◽  
Force Model ◽  
Shearing Stress ◽  
Orthogonal Metal Cutting ◽  
Linear Force ◽  
Dynamic Shearing

The mechanics of orthogonal cutting have been reexamined and for the shear-plane concept of metal cutting, linear and quadratic-force models were suggested. It was shown that for steel SAE-1213, investigated under variable cutting conditions, the dynamic shearing stress remained constant and the linear-force model correlated with those experimental data which were obtained under the absence of a BUE. The angle λ formed by the shear plane and the direction of the resultant force remained constant for each test condition but varied with cutting speed. Neither the Ernst and Merchant minimum energy, nor the Lee and Shaffer solutions are in agreement with experimental observations.

The Influence of Extreme Speeds and Rake Angles in Metal Cutting

1963 ◽  
Vol 85 (1) ◽  
pp. 49-64 ◽  
Author(s):  
W. N. Findley ◽  
R. M. Reed
Keyword(s):  
Coefficient Of Friction ◽  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Shear Plane ◽  
Rake Angle ◽  
Lateral Extrusion ◽  
Tool Force ◽  
Steep Decrease ◽  
Peak Value ◽  
Antimony Alloy

A study is presented of the effect of wide variations in speed of cutting and rake angle on orthogonal cutting of several metals—mainly a lead-antimony alloy. It was observed that enormous decreases in tool forces occurred in the lead-antimony with increase in speed from 6 to 3800 fpm, and decrease in rake angle from +30° to −60°. Explanations for these variations are proposed. An unusual observation was that a transition as speed increased from continuous to discontinuous chips occurred at large negative rake angles. Possible causes of this behavior are discussed. Another unusual observation was that a steep rise in tool force occurred with increase in speed for rake angles of 0° and +30°. The rise to a peak value was followed by an equally steep decrease in tool forces. Other observations discussed include the appearance of side spikes on the chips, chip curl, lateral extrusion of chips, influence of normal stress occurring on the shear plane, and the apparent coefficient of friction.

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.

Measuring fracture toughness from machining tests

2009 ◽  
Vol 223 (12) ◽  
pp. 2861-2869 ◽  
Author(s):  
Y Patel ◽  
B R K Blackman ◽  
J G Williams
Keyword(s):  
Fracture Toughness ◽  
Aluminium Alloy ◽  
Coefficient Of Friction ◽  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Shear Plane ◽  
Rake Angle ◽  
Sufficient Information ◽  
The Coefficient Of Friction ◽  
Adhesion Toughness

An analysis of the forces involved in orthogonal cutting or machining is presented in which yielding on a shear plane is assumed. The fracture toughness Gc is included and it is observed that Gc may be determined by measuring the cutting and transverse forces together with the chip thickness for a range of cutting depths. This latter measurement enabled the shear plane angle ϕ to be determined experimentally. A simplified version of the analysis is also given in which ϕ is predicted by a cutting force minimization scheme. Neither scheme requires any details of the friction condition to be known since the transverse force is sufficient information for any type to be included in the analysis. A friction model including a coefficient of friction and an adhesion toughness is also utilized. Data for both polymer and metal cutting are taken from the literature and Gc is determined. In some datasets the tool rake angle α is also varied and the values of Gc and the yield stress σY are found to be independent of α. The force minimization method gives a good estimate of ϕ for most polymers. For metals (aluminium alloy, steel, and brass) the method worked well. For aluminium alloy Gc was independent of α and the predicted and measured ϕ values agreed. For steel and brass this was not so. Gc was mostly independent of α except at low values where high values of Gc were observed. A constant value of the coefficient of friction was observed for each α value but values for both the coefficient of friction and the adhesion toughness varied significantly with increasing rake angle.

The Effect of Superheated Water Vapor as Coolant and Lubricant on Chip Formation of Difficult-to-Cut Materials in Green Cutting

2008 ◽  
Vol 375-376 ◽  
pp. 172-176 ◽  
Author(s):  
Rong Di Han ◽  
Yue Zhang ◽  
Yang Wang ◽  
Guo Fan Cao ◽  
Jie Liu
Keyword(s):  
Water Vapor ◽  
Chip Formation ◽  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Contact Length ◽  
Cutting Fluid ◽  
Environment Friendly ◽  
Cutting Zone ◽  
On Chip ◽  
Deformation Coefficient

Green cutting is ecologically desirable and have been a tendency in the industry field. Water vapor can be introduced in metal cutting as coolant and lubricant due to its pollution-free, generating easily and unneeded disposal. Therefore, water vapor is an environment-friendly coolant and lubricant in machining. This study attempts to understand the effect of water vapor as coolant and lubricant on chip formation. In the comparison experiments to dry and wet cutting, water vapor jet flow from a developed generator is applied into cutting zone directly. When YG8 (K20 in ISO) tools are used to turn titanium alloy TC4 (Ti-6Al-4V), Ni-based super alloy GH3030 and stainless steel 1Cr18Ni9Ti in orthogonal cutting, through quick-stop tests, the photos of polished chip sections microstructure were obtained. And the results suggest that the application of water vapor produces the least BUE, tool-chip contact length but the largest deformation coefficient and shear angle. The water vapor as coolant and lubricant could be a substitution of cutting fluid to carry out green cutting in the machining of difficult-to-cut materials.

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.

Inclined Moving Heat Source Model for Calculating Metal Cutting Temperatures

1984 ◽  
Vol 106 (3) ◽  
pp. 179-186 ◽  
Author(s):  
P. R. Dawson ◽  
S. Malkin
Keyword(s):  
Heat Source ◽  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Shear Plane ◽  
Source Model ◽  
The Finite Element Method ◽  
Heat Source Model ◽  
Orthogonal Machining ◽  
Creep Feed ◽  
Wide Range

The analysis of an inclined plane heat source moving along the surface of a semi-infinite solid is presented. Material passing by the heat source is eliminated from the analysis to simulate its removal by an orthogonal cutting process. The solution, expressed in terms of dimensionless parameters, is obtained by solving the heat equation numerically with the finite element method for a wide range of cutting conditions. The solution is used to evaluate shear plane temperatures in orthogonal machining and grinding zone temperatures in conventional and creep feed grinding.

A Coupled Finite Element Model of Thermo-Elastic-Plastic Large Deformation for Orthogonal Cutting

1992 ◽  
Vol 114 (2) ◽  
pp. 218-226 ◽  
Author(s):  
Z. C. Lin ◽  
S. Y. Lin
Keyword(s):  
Finite Element ◽  
Energy Density ◽  
Large Deformation ◽  
Chip Formation ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Metal Cutting ◽  
Orthogonal Cutting ◽  
Elastic Plastic ◽  
Chip Separation

In this paper, a coupled model of the thermo-elastic-plastic material under large deformation for orthogonal cutting is constructed. A chip separation criterion based on the critical value of the strain energy density is introduced into the analytical model. A scheme of twin node processing and a concept of loading/unloading are also presented for chip formation. The flow stress is taken as a function of strain, strain rate and temperature in order to reflect realistic behavior in metal cutting. The cutting tool is incrementally advanced forward from an incipient stage of tool-workpiece engagement to a steady state of chip formation. The finite difference method is adopted to determine the temperature distribution within the chip and tool, and a finite element method, which is based on the thermo-elastic-plastic large deformation model, is used to simulate the entire metal cutting process. Finally, the chip geometry, residual stresses in the machined surface, temperature distributions within the chip and tool, and tool forces are obtained by simulation. The calculated cutting forces agree quite well with the experimental results. It has also been verified that the chip separation criterion value based on the strain energy density is a material constant and is independent of uncut chip thickness.

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