Analysis of Tool Life Functions in Hard Turning

Varga

2022

Machines

Surface roughness is an important factor in metal cutting, and usually different surface roughness characteristics are used to control the quality of the machined surfaces. However, as the cutting tool wears out during the cutting process, the roughness values change. In most cases, theoretical roughness values are calculated without taking the wear characteristics of the tool into account. For this reason, the calculated and measured roughness values may differ from each other, and the tendency of their change may also be different. This paper presents a method for the determination of the theoretical roughness of hard turned surfaces considering the wear of the cutting tool. The purpose of the analyses performed was to show the effect of wear trace on the tool and the roughness of the machined surface and to give a possible method to take the wear into account when calculating the theoretical roughness values. During the investigations, the shape of the actual (worn) edge section of the cutting tool was recorded by an optical microscope, and the theoretical surface roughness values were calculated with that profile by a CAD modeling method developed earlier. Cutting experiments were conducted on a lathe machine with two similar cutting tools, one of them has significant tool wear, while the other was a completely new one. The calculated theoretical roughness values were compared with real measured roughness values, and the error of the estimates was between 8.7 and 68.3%, larger errors were found at lower feeds.

Section: State Of the Art Of Surface Roughness And Wear Modeling In H...mentioning

confidence: 99%

Theoretical Roughness Modeling of Hard Turned Surfaces Considering Tool Wear

Varga

2022

Machines

“…An important feature of this function is that there is a well-utilized relationship between its two local extremes and the constant C2, C3 [10][11][12][13]:…”

Section: About the General Tool Life Functionmentioning

confidence: 99%

“…3. General tool life function for hard turning of a hardened ball bearing ring [10][11][12][13] (ap = 0.15 mm, fz = 0.05 mm/rev, tool: Composite 10) An important feature of function ( 1) is that a third degree polynomial can be fitted to the middle section of Fig. 2, which illustrates the effect of the constant C2.…”

Section: About the General Tool Life Functionmentioning

confidence: 99%

Analysis of the general tool life function of cutting tools by application of the catastrophe theory

Pálmai

Kundrák

Proceedings of the Institution of Mechanical Engineers, Part B:

2022

Production technology planning requires information on tool life T and its relation to cutting speed v. These technological parameters fundamentally affect the economics of the operation of the entire production system. The aim of the present study is to investigate the v-T relationship under technological conditions where this relationship cannot be described by the methods used so far – typically the Taylor formula. As the Taylor formula often cannot be linearized on an log-log scale, a general tool life function has been developed for describing a v-T function with a convex-concave part. The function was validated by the boring of hardened ball bearing rings with the technological data D = 45, 75 and 100 mm, ap = 0.14 mm, fz = 0.005 mm/rev. The general v-T tool life function has been transformed into a quadratic polynomial known in catastrophe theory as cusp catastrophe and allows the description of abrupt changes in the system under study. Using catastrophe theory, an analogy is established between the general tool life function and the cusp catastrophe, allowing topological mapping of the general v-T function. Results were verified by machinability tests in the turning of C35 and C60 conventional and specially deoxidized C-steels during steelmaking. Cutting tests were performed on specimens with a diameter of Dexp = 76 mm and a length of L = 700 mm at a speed of v = 100, 150, 200 m/min and a carbide tool of category P20. It was found that in the convex-concave section of this function, 2–3 cutting speeds can be selected for a given tool life, which is advantageous for harmonizing tool changes in multi-operation technology.

Analysis of the General Tool Life Function of Cutting Tools by Application of the Catastrophe-Theory

Pálmai

Kundrák

2021

Preprint

Production technology planning requires information on tool life T and its relation to cutting speed v. As the Taylor formula often cannot be linearized on an lg-lg scale, a general tool life function has been developed for describing a v-T function with a convex-concave part. Using catastrophe theory, an analogy is established between the general tool life function and the cusp catastrophe, allowing topological mapping of the general v-T function. Results were verified by machinability tests in the turning of C35 and C60 conventional and specially deoxidized C-steels during steelmaking. It was found that in the convex-concave section of this function, 2–3 cutting speeds can be selected for a given tool life, which is advantageous for harmonizing tool changes in multi-operation technology.