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1 Journal of Achievements in Materials and Manufacturing Engineering
1 Prace Naukowe Instytutu Technologii Maszyn i Automatyzacji Politechniki Wrocławskiej. Monografie

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Variation cutting speed on the five axis milling

Boujelbene M., Moisan A., Bouzid W., Torbaty S.

Journal of Achievements in Materials and Manufacturing Engineering

2007

Vol. 21, nr 2

7-14

Purpose: The aim of this research is to make a study of the effective cutting speed variation in milling with a ball end tool. Then an experimental study of the effect of finishing strategies on surface texture, roughness is described. The material of a specific HB 300 pre-hardened mould steel Super Plast (SP 300). Design/methodology/approach: The methodology has consisted to determine cutting speed of each mode of tilt tool in five axes machining, and of proving a series of configurations and parameters combinations: cutting speed Vc, feed rate Vf, and tilt tool in multi-axis milling. Findings: This paper has investigated the effect of the tool orientation on the variation effective cutting speed, on the surface texture, while multi-axis milling. Experimental results have shown that disadvantages of three axes machining results from the existence of very low cutting speeds, even null when the tool axis is normal to the machined surface. This mode of machining generates a bad surface quality. Surfaces have a poor topography and important anisotropy. A suitable slope of the cutting tool by the means of the fifth machine tool axis, improves considerably work piece machined surface quality; Good micro-geometrical surface topography and lower surface roughness. Research limitations/implications: A possible future work would be the development of a general the phenomenal of the residual stress of the cutting on the five axis machining. The behavior of the residual stress studies are planed in the future. Practical implications: The relationship found between the effective cutting speed and surface texture work piece has an important practical implication since it allows selecting the best cutting condition combination from the points of view both the security and the economy for the established requirements in each case. Results are of great importance in for aerospace and automotive industry. Originality/value: The paper is original since the bibliographical review has allowed testing that, although works about these themes exist, none approaches the problem like it has been made in work.

Efektywność kształtowania skrawaniem przedmiotów osiowosymetrycznych w zintegrowanym wytwarzaniu

Cichosz P.

Prace Naukowe Instytutu Technologii Maszyn i Automatyzacji Politechniki Wrocławskiej. Monografie

1998

Vol. 70, nr 21

3-200

Zanalizowano strukturę funkcji czasu i kosztów operacji obróbki skrawaniem przedmiotów osiowosymetrycznych dla różnych możliwości obróbkowych narzędzi i obrabiarek. Badania dotyczyły warunków współczesnych, a także tych, które będą mogły być zrealizowane dopiero w przyszłości. Pozwoliło to na określenie najskuteczniejszych kierunków badań i poszukiwań możliwości zwiększenia efektywności wytwarzania na tokarkach sterowanych numerycznie. Udowodniono, że funkcje czasu i kosztów operacji mogą mieć miejsca nieciągłości i nieoznaczoności. Zbadano charakter i wielkość tych nieciągłości, a także warunki, w których mogą one osiągać największe wartości, zakłócające przebieg funkcji celu. Opracowano funkcje celu, opisujące złożone warianty pracy narzędzi, a także uwzględniające specyficzny charakter wykonywania operacji w zintegrowanym wytwarzaniu. Wiele uwagi poświecono narzędziom wielozadaniowym, których rola, w wytwarzaniu na obrabiarkach sterowanych numerycznie, jest coraz bardziej znacząca. Opracowano metodykę optymalizacji, pozwalającą na znacznie dokładniejsze wyznaczanie najkorzystniejszych warunków obróbki w porównaniu z dotychczasowymi metodami optymalizacyjnymi. Przeanalizowano przeszkody utrudniające zwiększanie efektywności obróbki przedmiotów osiowosymetrycznych.

The monograph presents the current state-of-the-art in the domain's scope, which is at present the subject of investigation. This became a starting point for the formulation of the aim, theses, and scope of the work. The analytical investigation performed confirms the submitted propositions. It has been demonstrated that the time and cost functions can reveal places of discontinuity and indeterminancy. They relate to those situations, frequently experienced in a real production, which require the preemptive exchange of tool. Such an exchange is done when the tools residual lifetime is shorter than its usage duration in the next operation, rather than it becomes excessively blunt. Additional deviations from the aim function continuity have been found which result from the impossibility to fully exploit residual lifetimes of the tools at the end of the production job. The character and intensity of the deviations have been investigated as well as the conditions in which the discontinuities tend to attain maximum values and the areas where they are insignificant. Novel operation-time/cost functions have been worked out to allow for the cost of optimization itself. The functions were employed as the aim functions in the optimization of cutting parameters; they also constituted a basis for the analytical investigation of the operation time/cost function structure. The effect of running up, and changing the rotational speed of the spindle on the time and cost of manufacturing has been assessed. It has been noted that these times can significantly influence the aim function for those cutting processes, in which extremely high rotational speeds of the spindle are employed. The functions therefore allow for the fact by including more accurate relationships. Much attention has been paid to multi-purpose tools whose role in the NC-machine-tool manufacturing is becoming increasingly important. Aim functions have been worked out for the cutting with these tools and a methodology proposed for the optimization of cutting parameters. The methodologies proposed, aiming at the optimization of NC lathe operations, make it possible to choose cutting parameters while allowing for the different types of cutting edge materials used in each of the tools. They enable to allow for a great number of nonlinear boundary constraints and, additionally, include enforced conditions such as a determined (maximum, minimum, equal, whole) number of tools allocated for the production job, the ratio of the tools lifetime and the duration of the tools engagement in the operation Tc/tsÎ (1,2,3,,...,n), etc. The constraints in question in can be imposed globally on the entire operation, and locally on the individual passes that the tools perform. A computer program CEZETA, designed for analysis of NC programs and extraction of data necessary for the optimization of cutting parameters, has been developed and verified in industrial environment. Analytical investigation was based on the data collected by polling a number of industrial enterprises. The type of change in the aim function structure has been evaluated for the conditions thus determined, which were assumed as a reference. Extensive variations of the individual factors were taken into account. The structures of the operation time/cost functions were analyzed for various machining capacities of tools and machines, within the range of conditions currently attainable as well as for hypothetical conditions which will be possible in the future only. This made it possible to determine relationships and trends from which conclusions were drawn as to the most effective directions of investigation and research for the possibilities of the increasing the NC-lathe production efficiency. The sophistication of numerical methods and the exellent performance of computer hardware available today offered a great help in the realization of the work. This allowed quite an extensive investigation to be conducted efficiently, complicated optimization procedures to be feasible, and the graphical visualization of calculational data helpful in the analysis of the results obtained. Without the facilities this scope of work would be impossible. Due to the considerable volume of analytical investigation results, only a small portion of them have been documented in the work.