Cold Forging with Lubricated Tools

2014 ◽  
Vol 611-612 ◽  
pp. 971-980 ◽  
Author(s):  
Christoph Müller ◽  
Lena Rudel ◽  
Deniz Yalcin ◽  
Peter Groche
Keyword(s):  
Friction Coefficient ◽  
Compression Test ◽  
High Impact ◽  
Cold Forging ◽  
Ecological Awareness ◽  
System A ◽  
Tribological System ◽  
Single Bath ◽  
Definition Of ◽  
Sliding Compression Test

Cold forging processes require high-capability tribological systems in order to ensure sound forming results. Due to a rising ecological awareness, alternatives to the established and reliable conversion coatings are necessary. Single bath systems like polymers and salt wax coatings with integrated lubrication appear to be the most promising approach to prevent galling. For an optimization and investigation of the tribological system a definition of the tribological loads is necessary. However, only insufficient values are available in literature. Especially, long sliding distances, which occur in multistage operations, can cause a breakdown of the lubricant. Therefore, approaches are necessary to enable long sliding distances. This paper presents the results obtained with a cold forging tribometer, the Sliding Compression Test, which reveal the high impact of remaining lubricant on the friction coefficient. Also, tests with prelubricated tools show the ability to reduce the friction and the results of investigations with rough tool surfaces are presented.

A New Concept of the Sliding Compression Test to Independently Investigate the Contact Normal Stress and the Surface Enlargement

2014 ◽  
Vol 939 ◽  
pp. 473-480
Author(s):  
Peter Groche ◽  
Christoph Müller ◽  
Mira Keller
Keyword(s):  
Friction Coefficient ◽  
Normal Stress ◽  
Compression Test ◽  
The Other ◽  
Cold Forging ◽  
Efficient Process ◽  
Highly Efficient ◽  
Other Hand ◽  
Sliding Compression Test

Cold forging is a highly efficient process to produce components. However, the occurring tribological loads are tremendous. Therefore, complex tribological systems are necessary. They can be influenced by numerous factors. Most important are the tribological loads, which can usually be investigated independently. On the other hand, the contact normal stress and the surface enlargement are coupled in tribometer tests. In order to investigate them independently, a new concept for the Sliding Compression Test is presented and verified. This procedure reveals that both values have an influence on the friction coefficient. However, the influence of the surface enlargement is with about two-thirds higher.

scholarly journals Zur exakten Behandlung von kollektiven Rotationen Teil A: Theorie / On the Exact Treatment of Collective Rotations Part A: Theory

1973 ◽  
Vol 28 (2) ◽  
pp. 206-215
Author(s):  
Hanns Ruder
Keyword(s):  
Coordinate System ◽  
Perturbation Expansion ◽  
Rotational Energy ◽  
The Body ◽  
System A ◽  
N Body Problem ◽  
Definition Of ◽  
Fixed System ◽  
Body Fixed Coordinate System ◽  
Groundstate Energy

Basic in the treatment of collective rotations is the definition of a body-fixed coordinate system. A kinematical method is derived to obtain the Hamiltonian of a n-body problem for a given definition of the body-fixed system. From this exact Hamiltonian, a consequent perturbation expansion in terms of the total angular momentum leads to two exact expressions: one for the collective rotational energy which has to be added to the groundstate energy in this order of perturbation and a second one for the effective inertia tensor in the groundstate. The discussion of these results leads to two criteria how to define the best body-fixed coordinate system, namely a differential equation and a variational principle. The equivalence of both is shown.

XV.—The Placoderm Fish Rhachiosteus pterygiatus Gross and its Relationships

1966 ◽  
Vol 66 (15) ◽  
pp. 377-392 ◽  
Author(s):  
Roger S. Miles
Keyword(s):  
Sensory System ◽  
System A ◽  
The Family ◽  
Definition Of

SynopsisThe holotype and only known specimen of Rhachiosteus pterygiatus Gross is partially redescribed and new restorations are given. Attention is drawn to important points in its osteology and the possible development of a cutaneous sensory system. A definition of the family Rhachiosteidsæ Stensiö is given. This family differs from all other described groups of euarthrodires in the lack of posterior lateral and posterior dorsolateral flank plates. Rhachiosteus is a pachyosteomorph brachythoracid, as defined in the text, and may be fairly closely related in some way to the (coccosteomorph) family Coccosteidsæ. There is no indication that it is closely related to any other known pachyosteomorph, or to other groups of arthrodires, such as the Rhenanida and Ptyctodontida, in which there are no posterior flank plates.

scholarly journals Bank Stability Measures in Dual Banking System: A Critical Review

2019 ◽  
Vol 5 (2) ◽  
pp. 59
Author(s):  
Norzitah Abdul Karim ◽  
Amirul Afiff Muhamat ◽  
Azreen Roslan ◽  
Sharifah Faigah Syed Alwi ◽  
Mohamad Nizam Jaafar
Keyword(s):  
Global Financial Crisis ◽  
Financial Institution ◽  
Banking System ◽  
Banking Supervision ◽  
Basel Committee ◽  
System A ◽  
Overall Stability ◽  
Regulatory Bodies ◽  
Banking Stability ◽  
Definition Of

The 2007-2009 Global Financial Crisis showed that despite reported as ‘healthy’ financial institution prior to crisis had indeed suffered many problems including liquidity during the crisis. Thus, there is confusion on the healthy financial institutions, leading to loss of confidence on the overall stability of the banking system. Thus, there is an urgent need to review the current measures of financial as well as banking stability. This paper aims to look at the definition of ‘stability’ used in the academic researches and by different regulatory bodies, like International Monetary Fund, Basel Committee for Banking Supervision (BCBS) and central banks in selected countries with dual banking systems. It is then, critically review indicators used as measures of financial as well as banking stability. This review is hope to identify areas of strengths as well as weaknesses of the current measures of stability and serves as foundation for further research in future.

Influence of the Preforming Material State in Common Tribological Tests

2016 ◽  
Vol 1140 ◽  
pp. 75-82
Author(s):  
Bastian Zimmermann ◽  
Marion Merklein
Keyword(s):  
Compression Test ◽  
Work Hardening ◽  
Test Sample ◽  
Wire Drawing ◽  
Cold Forging ◽  
The Real ◽  
Friction Factors ◽  
Ring Compression ◽  
Material State ◽  
Rolled Wire

Different tests to determine friction factors for cold forging processes are given in the literature. The double cup extrusion test, the ring compression test and the T-shape compression test are three of the common tests, which are compared in this investigation. From former investigations it is known that there is an influence of the work-hardening of the test sample on the friction factor, which is determined by the test. At this study, the influence of the work-hardening of the material on the three named tests is investigated by using a wire drawing process. In addition, the drawn wire from the originally thermo mechanical rolled wire is also annealed to have a second material state without any work-hardening. The used material and its numerical modelling as well as the analyzed tribological conditions of the real specimens are described. Afterwards the three test setups are explained for the numerical as well as for the real experiments. In the end, the influence of the drawing respectively the work-hardening for the three tests is presented and discussed.

An indexing system for the relevance of academic production and research from digital repositories and metadata

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Jared David Tadeo Guerrero-Sosa ◽  
Víctor Hugo Menéndez-Domínguez ◽  
María Enriqueta Castellanos-Bolaños
Keyword(s):  
Open Access ◽  
High Impact ◽  
Practice Research ◽  
Research Groups ◽  
Content Type ◽  
University Campuses ◽  
Easy Integration ◽  
Definition Of ◽  
The Impact ◽  
The Prestige

Purpose This paper aims to propose a set of quantitative statistical indicators for measuring the scientific relevance of research groups and researchers, based on high-impact open-access digital production repositories. Design/methodology/approach An action research (AR) methodology is proposed in which research is associated with the practice; research informs practice and practice is responsible for informing research in a cooperative way. AR is divided into five phases, beginning with the definition of the problematic scenario and an analysis of the state of the art and ending with conducting tests and publishing the results. Findings The proposed indicators were used to characterise group and individual output in a major public university in south-eastern Mexico. University campuses hosting a large number of high-impact research groups. These indicators were very useful in generating information that confirmed specific assumptions about the scientific production of the university. Research limitations/implications The data used here were retrieved from Scopus and open access national repository of Mexico. It would be possible to use other data sources to calculate these indicators. Practical implications The system used to implement the proposed indicators is independent of any particular technological tool and is based on standards for metadata description and exchange, thus facilitating the easy integration of new elements for evaluation. Social implications Many organisations evaluate researchers according to specific criteria, one of which is the prestige of journals. Although the guidelines differ between evaluation bodies, relevance is measured based on elements that can be adapted and where some have greater weight than others, including the prestige of the journal, the degree of collaboration with other researchers and individual production, etc. The proposed indicators can be used by various entities to evaluate researchers and research groups. Each country has its own organisations that are responsible for evaluation, using various criteria based on the impact of the publications. Originality/value The proposed indicators assess based on the importance of the types of publications and the degree of collaborations. However, they can be adapted to other similar scenarios.

Gaia Photometric Catalogue: the calibration of the DR2 photometry

2018 ◽  
Vol 14 (A30) ◽  
pp. 466-470
Author(s):  
D. W. Evans ◽  
M. Riello ◽  
F. De Angeli ◽  
J. M. Carrasco ◽  
P. Montegriffo ◽  
...  
Keyword(s):  
Scientific Community ◽  
Photometric Data ◽  
Photometric System ◽  
Gaia Dr1 ◽  
System A ◽  
Data Release ◽  
Definition Of ◽  
High Level ◽  
Crucial Part ◽  
Gaia Dr2

AbstractGaia DR2 was released in April 2018 and contains a photometric catalogue of more than 1 billion sources. This release contains colour information in the form of integrated BP and RP photometry in addition to the latest G-band photometry. The level of uncertainty can be as good as 2 mmag with some residual systematics at the 10 mmag level. The addition of colour information greatly enhances the value of the photometric data for the scientific community. A high level overview of the photometric processing, with a focus on the improvements with respect to Gaia DR1, was given. The definition of the Gaia photometric system, a crucial part of the calibration of the photometry, was also explained. Finally, some of the photometric improvements expected for the next data release were described.

Research on Spurious Trip of 1oo2 Safety Instruments of Petrochemical Installation with Repair Considered

2010 ◽  
Vol 118-120 ◽  
pp. 596-600
Author(s):  
Jian Xin Zhu ◽  
Xue Dong Chen ◽  
Shi Yi Bao
Keyword(s):  
Failure Rate ◽  
System Reliability ◽  
Repairable System ◽  
Time To Failure ◽  
Redundant System ◽  
Common Cause ◽  
System A ◽  
Definition Of ◽  
Mean Time ◽  
Complex Influence

An innovative nuisance trip calculation method based on Markov model was proposed in this paper which was used to evaluate the effect of repairment on system reliability. By analysis of the availabilities of classic 1 out of 2 (1oo2) repairable system, a new definition of spurious trip was put forwarded where online repair was considered. Compared with the benefits obtained by online repairment, the repair-caused-nuisance-trip was analyzed in this paper. Numerical calculation revealed that the online repair is helpful for anti-spurious trip in 1oo2 redundant system. Dangerous failures, if not repaired or cannot be online fixed, have complex influence on system reliability. The dangerous failure is sometimes benefit for anti-spurious performance if it is not repaired. But Mean Time To Failure Spurious (MTTFs) reduces with the increase of dangerous failure provided that dangerous failure rate is bigger than safe failure rate. Meanwhile, the finding that common cause can reduce the chance of nuisance trip was also proposed in this paper, though the influence is too small to be neglected.

Querying and Integrating P2P Deductive Databases

2009 ◽  
pp. 410-416
Author(s):  
Luciano Caroprese ◽  
Sergio Greco ◽  
Ester Zumpano
Keyword(s):  
Query Optimization ◽  
Deductive Databases ◽  
The Other ◽  
Mapping Rules ◽  
System A ◽  
Definition Of ◽  
P2p System

Recently, there have been several proposals that consider the integration of information and the computation of queries in an open-ended network of distributed peers (Bernstein, Giunchiglia, Kementsietsidis, Mylopulos, Serafini, & Zaihrayen, 2002; Calvanese, De Giacomo, Lenzerini, & Rosati, 2004; Franconi, Kuper, Lopatenko, & Zaihrayeu, 2003) as well as the problem of schema mediation and query optimization in P2P (peerto- peer) environments (Gribble, Halevy, Ives, Rodrig, & Suciu, 2001; Halevy, Ives, Suciu, & Tatarinov, 2003; Madhavan & Halevy, 2003; Tatarinov & Halevy, 2004). Generally, peers can both provide or consume data and the only information a peer participating in a P2P system has is about neighbors, that is, information about the peers that are reachable and can provide data of interest. More specifically, each peer joining a P2P system exhibits a set of mapping rules, in other words, a set of semantic correspondences to a set of peers that are already part of the system (neighbors). Thus, in a P2P system, the entry of a new source, or peer, is extremely simple as it just requires the definition of the mapping rules. By using mapping rules as soon as it enters the system, a peer can participate and access all data available in its neighborhood, and through its neighborhood it becomes accessible to all the other peers in the system.

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