Wyniki wyszukiwania - BazTech

1

New aspects of metrology of frictional behaviour in metal cutting

Rech J., Claudin Ch., Polly P., Courbon C.

Mechanik

|

2016

|

R. 89, nr 11

1751--1753

EN

This paper introduces a method for a fast identification of friction and heat partition models in cutting. Based on a special tribometer able to simulate wide ranges of contact pressures and sliding velocities, the method is applied for a wide spectrum of work materials and lubrication conditions.

PL

Artykuł wprowadza nową metodę szybkiej identyfikacji modeli tarcia i partycji ciepła w skrawaniu. Umożliwia to symulacja w szerokim zakresie nacisków kontaktowych i szybkości poślizgu z wykorzystaniem specjalnego tribometru. Metoda może być stosowana do szerokiego spektrum materiałów i warunków smarowania.

2

Pomiar rozkładu temperatury w strefie skrawania za pomocą kamery termowizyjnej

Kiszka P., Grzesik W., Rech J.

Mechanik

|

2015

|

R. 88, nr 3

197--200

PL

Przedstawiono wyniki pomiaru rozkładu temperatury w strefie skrawania uzyskane za pomocą kamery termowizyjnej podczas toczenia ortogonalnego żeliwa sferoidalnego (perlityczno-ferrytycznego) ostrzami z ceramiki azotkowej i CBN. Program eksperymentu obejmował pomiar średniej i maksymalnej temperatury kontaktowej oraz uzyskanie kolorowych termogramów.

EN

Reported are the results of temperature distribution measurements in the cutting zone carried out by means of a thermal image camera during orthogonal turning of the pearlitic-ferritic (PF) spheroidal cast iron (EN-GJS-500-7 grade) using CBN and nitride ceramic tools. The experiment consisted of measurements of the average and the maximum cutting contact temperatures and color thermal photographs.

3

Optimization of a Multi-Drilling Sequence with MQL Supply to Minimize Thermal Distortion of Aluminum Parts

Faverjon P., Rech J., Valiorgue F., Orsetti M.

Journal of Machine Engineering

|

2015

|

Vol. 15, No. 3

75--89

EN

The drilling process with solid carbide tools with minimum quantity lubrication is under development in the automotive industry due to its high productivity and its environmental benefit. Because of the poor cooling performance when using MQL, a high amount of heat remains in the workpiece, which induces macroscopic thermal distortions and inaccurate parts. This paper presents a methodology to model the thermal distortion of a complex part having a large number of holes. The heat flux entering into the workpiece during each drilling operation is calibrated based on embedded thermocouples and on geometrical observations of the drill surface. Finally, it is shown how the model enables the optimization of a drilling sequence so as to minimize the thermal distortion and the accuracy of the machined part.

4

Topografia powierzchni po bardzo dokładnym szlifowaniu taśmą ścierną

Grzesik W., Rech J.

Mechanik

|

2014

|

R. 87 nr 10

806--808

PL

Przedstawiono urządzenie i warunki technologiczne szlifowania taśmowego z minimalnym smarowaniem (MQL) powierzchni uprzednio toczonej ostrzem z CBN. Dokonano kompleksowej charakterystyki stereometrii powierzchni dla parametru Sa ok. 0,05 μm (50 nm), co praktycznie mieści się w zakresie nano. Przeprowadzono analizę właściwości eksploatacyjnych uzyskanych powierzchni.

EN

This paper presents special belt grinding head and specifies process requirements for such operation using minimum quantity of lubrication supply (MQL). Described are belt ground surfaces after finish hard turning by means of a CBN bit. A complex review of the surface was carried out for the roughness parameter Sa 0,05 μm (50 nm), which actually should be categorized as nano-range. Functional properties of the produced surfaces were examined.

5

Identification of friction and heat partition model at the tool-chip-workpiece interfaces in dry cutting of an Inconel 718 alloy with cBN and coated carbide tools

Zemzemi F., Rech J., Salem W. B., Dogui A., Kapsa P.

Advances in Manufacturing Science and Technology

|

2014

|

Vol. 38, nr 1

5--22

EN

This paper aims at characterizing the frictional behaviour at the cutting tool-workmaterial interface during the dry machining of a Inconel 718 in its aged state with various coated carbide tools and c-BN tools. A specially designed open tribometer has been used to characterize friction coefficient, heat partition coefficient under extreme conditions corresponding to the ones occurring in cutting. The tribometer provides the evolution of the apparent friction coefficient and of the heat partition coefficient for a large range of sliding velocity and contact pressure. It has been shown that friction coefficient as well as heat partition coefficient decrease with sliding velocity or contact pressure. A threshold effect of the contact pressure has been highlighted. On the contrary, any sensitivity to coatings deposited on carbide has been observed, whereas c-BN leads to very low friction coefficients.

PL

W pracy określono charakterystykę tarciowego zachowania się strefy kontaktu wiór-ostrze obrabianego w toczeniu na sucho nadstopu Inconel 718 po starzeniu narzędziami wykonanymi z różnych gatunków węglików spiekanych z naniesionymi powłokami i polikrystalicznego CBN. Zaprojektowano i wykonano tribometr do wyznaczania wartości współczynnika tarcia i współczynnika podziału ciepła. Badania prowadzono w warunkach ekstremalnych zbliżonych do występujących w procesie skrawania na sucho. Tribometr umożliwia pomiary w czasie wartości pozornego współczynnika tarcia i przepływ ciepła dla dużego zakresu wartości prędkości skrawania i nacisku normalnego. Wykazano, że zarówno współczynnik tarcia, jak i podziału ciepła zmniejszają się przy wzroście prędkości i siły normalnej skrawania. Określono graniczny efekt nacisku kontaktowego. Nie stwierdzono wpływu rodzaju powłoki na ostrzu z węglika spiekanego na wartość współczynnika tarcia. Natomiast skrawanie narzędziami z ostrzem p-CBN prowadzi do uzyskania bardzo małej wartości współczynnika tarcia.

6

Characterization of Friction Properties During Machining of Various Stainless Steels

Naisson P., Rech J., Paris H.

Engineering Transactions

|

2013

|

Vol. 61, iss. 4

239--248

EN

Many issues in machining are related to interface characteristics, such as the friction coefficient, adhesive layer, or heat transfer coefficient. A specially designed tribometer is used to quantify these contact parameters in the case of four stainless steels (three austenite grade with controlled composition and an austenito-ferritic one). The sensitivity to sliding velocity and coatings is investigated. It is highlighted that the contact pressure effect is limited compared with the influence of sliding speed. Moreover, tool damage can also be explained by local phenomena exhibited by the tribometer, such as adhesion layer or thermal aspects, which are critical in case of stainless steels.

7

Surface integrity on hardened steel parts produced by hybrid machining sequences

Grzesik W., Rech J., Wanat T.

Journal of Achievements in Materials and Manufacturing Engineering

|

2008

|

Vol. 31, nr 2

654-661

EN

Purpose: Of this paper is the investigation of surface integrity generated in hard turning and subsequent finish abrasive machining. The primary reason for undertaking this problem was insufficient magnitude of compressive residual stresses after hard turning which determines the fatigue resistance of highly loaded transmission parts. Design/methodology/approach: Employed uses 2D and 3D description of the surface roughness/surface microstreometry and the X-ray diffraction method for measurements of residual stresses. The main scope of this research program is to record the relevant changes of surface layer features resulting from the application of finish abrasive passes. Findings: Can be distinguished into two groups. First, finish belt grinding produces the residual stresses with the maximum value of-1000 MPa, which is satisfactory for improving fatigue life. Second, the bearing properties improve due to displaying negative values of the skew. Research limitations/implications: Deal with the identification range of 3D roughness parameters and the lack of modern equipment for robust measurements of residual stresses: Future research should be focused on the stronger correlation between technological and exploitation properties of the surfaces produced by hard and abrasive technologies. However, it needs more detailed inputs from automotive industry. Practical implications: Are related to the automotive industry, especially to manufactures of such transmission elements as synchronizing cones/planes on gear wheels. The sequences of new hybrid machining processes are partly verified in terms of industry needs (machining conditions, machine tools, special equipment, cutting and abrasive tools). Originality/value: Of this industry-oriented contribution is based on the aggregating hard cutting and abrasive machining processes. The practical value of the paper is that it proposes a very beneficial machining process for highly loaded hardened parts.

8

Surface integrity of hardened steel parts in hybrid machining operations

Grzesik W., Rech J., Wanat T.

Journal of Achievements in Materials and Manufacturing Engineering

|

2006

|

Vol. 18, nr 1-2

367--370

EN

Purpose: Purpose of this paper is the investigation of surface integrity generated in hard turning and subsequent finish abrasive machining. The primary reason for undertaking this problem was insufficient magnitude of compressive residual stresses after hard turning which determines the fatigue resistance of highly loaded transmission parts. Design/methodology/approach: Methodology employed uses 2D and 3D description of the surface roughness/surface microstreometry and the X-ray diffraction method for measurements of residual stresses. The main scope of this research program is to record the relevant changes of surface layer features resulting from the application of finish abrasive passes. Findings: Findings can be distinguished into two groups. First, finish belt grinding produces the residua stresses with the maximum value of–1000 MPa, which is satisfactory for improving fatigue life. Second, the bearing properties improve due to displaying negative values of the skew. Research limitations/implications: Research limitations deal with the identification range of 3D roughness parameters and the lack of modern equipment for robust measurements of residual stresses: Future research should be focused on the stronger correlation between technological and exploitation properties of the surfaces produced by hard and abrasive technologies. However, it needs more detailed inputs from automotive industry. Practical implications: Practical implications are related to the automotive industry, especially to manufactures of such transmission elements as synchronizing cones/planes on gear wheels. The sequences of new hybrid machining processes are partly verified in terms of industry needs (machining conditions, machine tools, special equipment, cutting and abrasive tools). Originality/value: Originality of this industry–oriented contribution is based on the aggregating hard cutting and abrasive machining processes. The practical value of the paper is that it proposes a very beneficial machining process for highly loaded hardened parts.