| 1. |
- Luks, T., et al.
(författare)
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Contact stress distribution and roll surface temperatures in the roll gap analyzed with different sensors
- 2014
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Ingår i: La Metallurgia Italiana. - : Associazione Italiana di Metallurgia. - 0026-0843. ; 106:1, s. 19-25
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the contact stresses and temperatures during hot and cold rolling have been measured. A work roll containing three different sensors was used for the measurements. There were two contact devices for directly measuring forces and one temperature sensor. One sensor was the "ROLLSURF" sensor. Results obtained with this sensor have been presented earlier [1-3], The measurement principle is based on deformation measurements with strain gauges which were placed on an internal cradle-type roll insert. The second sensor was a friction pin sensor. The forces on the top of the pin were measured by three axis piezoelectric-transducers. The pin sensor was mounted inside the work roll opposite to the ROLLSURF sensor. The third sensor was a thermocouple placed next to the pin sensor. The temperatures were measured very close to the roll surface. The surface boundary conditions including the heat flux and surface temperatures were computed using inverse modelling calculations developed at Brno University of Technology. The main task of this paper is to show a comparison of the contact forces and contact length measured with the strain-gauge sensor and the pin-sensor.
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| 2. |
- Lagergren, J., et al.
(författare)
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A new transducer for local load measurements of friction and roll pressure in cold flat rolling
- 2006
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Ingår i: Steel Research International. - 1611-3683 .- 1869-344X. ; 77:6, s. 430-438
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Tidskriftsartikel (refereegranskat)abstract
- The only way to establish the true rolling pressure and the true friction condition in cold rolling is to conduct measurements in the roll bite. A new transducer design is therefore proposed, in order to overcome problems in previous measurements In the past 70 years. The new idea Is to increase the contact surface of the transducer, to be larger than the arc of contact. This Is in contrast to the smaller and smaller contact pin design that has been prevailing. The measurements were conducted during cold dry rolling of both copper strips and stainless steel strips In a pilot mill. The recordings were selected from a steady state with no disturbance from the material flow. The transducer was able to simultaneously measure both the normal pressure and the friction stress. An estimation of the coefficient of friction was accordingly performed. The new transducer works very well, it was seen to be robust and able to avoid signal disturbance. The pressure and friction stress distribution results was as expected by the authors and showed good reproducibility, together with a proven agreement between recorded and simulated signals.
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| 3. |
- Presz, W., et al.
(författare)
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Application of surface load - A new calibration method
- 2011
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Ingår i: Proceedings of the 10th International Conference on Technology of Plasticity, ICTP 2011. - 9783514007840 ; , s. 1265-1269
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Konferensbidrag (refereegranskat)abstract
- A special kind of transducer making it possible to measure normal and tangential contact stresses during rolling has been developed. As normal stresses are approximately ten times larger than the tangential, and since cross signals must occur, a proper calibration of the sensor is essential. Calibration must consist of a number of simultaneous applications of known normal and tangential loads. This problem was solved with an especially designed apparatus called Surface Loader (SL). The design makes it possible to apply a force of known value and direction to a small area of the surface. If the value and direction of force is known it might be treated as applying normal and tangential load using the force components. The contact end of the force actuator has a low carbon steel nose, making it possible to reach high friction coefficients. A precise determination of the applied force direction is possible by the invented method of loading. It is applied by a special construction of SL, controlling of the bending moment acting on the actuator by measuring the reaction force and using a special loading procedure: (i) Applying normal force on the sensor surface - a lateral support is used, (ii) Removing the lateral support, (iii) Developing friction by horizontally moving the platform until the moment in the actuator disappears. © 2011 IBF (RWTH Aachen) & IUL (TU Dortmund).
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| 4. |
- Tahir, Mohammed, 1961-, et al.
(författare)
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Evaluation of tool material Vancron 40 with regard to wear, surface quality and galling
- 2012
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Ingår i: Proceedings of JSI 2012 - 30th International Steel Industry Conference, December 18-19, Paris, France. - Paris : B&W.
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Konferensbidrag (refereegranskat)abstract
- Resistance to adhesive wear on tool material can be improved by increasing the tool hardness, high ductility and decreasing of friction coefficient between the tool and the work material. In a similar way, resistance to galling can be increased by increasing the tool hardness and decreasing of friction. The purpose of this project was to investigate the use of Vancron 40 as work rolls in cold rolling of stainless steel in cluster rolling mills. Considerable factors were among others, the influence of different industrial lubricants, minimizing of temperature rising during rolling, lowering of rolling forces, longer life of rolls, easier grinding of rolls, increase the oil film bearing at normal cold rolling conditions and improving surface roughness of the final products.For using of work rolls in cold rolling cluster mills, roll material Vancron 40 was evaluated with regard to roll wear, surface quality and galling. Currently used roll type ASP23 was used as reference roll in the evaluation. The experiments were performed, as much as possible, in accordance to steel industries recommendations. The experiments were conducted with a 4-high pilot rolling mill at Swerea MEFOS in Luleå which is equipped for rolling of both flat and long products. The experiment was done for different industrial mineral-based lubricants. Lubrication was applied in a controlled form to the upper and lower work rolls and in the contact zone. To achieve the proposed final thickness, five passes were rolled. The characteristic of the upper and the lower work rolls, during rolling, was also examined. The pilot experimental results gave promising result in surface roughness, galling and roll material hardness. Due to its chemical and physical properties, Vancron 40 is believed to be the best solution to resist adhesive wear and galling in cold rolling process that require higher accuracy.
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| 5. |
- Tofigh, Ali, et al.
(författare)
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Detecting LGTs using a novel probabilistic modelintegrating duplications, LGTs, losses, rate variation,and sequence evolution
- 2009
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The debate over the prevalence of lateral gene transfers (LGTs) has been intense.There is now to a large extent consensus around the view that LGT is an important evolutionary force as well as regarding its relative importance across species. This consensus relies, however, mainly on studies of individual gene families.Up until now, the gold standard for identifying LGTs has been phylogenetic methods where LGTs are inferred from incongruities between a species tree andan associated gene tree. Even in cases where there is evidence of LGT, several concerns have often been raised regarding the significance of the evidence. One common concern has been the possibility that other evolutionary events have caused the incongruities. Another has been the significance of the gene trees involved in the inference; there may for instance be alternative, almost equally likely, gene trees that do not provide evidence for LGT. Independently of these concerns, there has been a need for methods that can be used to quantitatively characterize the level of LGT among sets of species, but also for methods able to pinpoint where in the species tree LGTs have occurred.Here, we provide the first probabilistic model capturing gene duplication, LGT,gene loss, and point mutations with a relaxed molecular clock. We also provide allfundamental algorithms required to analyze a gene family relative to a given speciestree under this model. Our algorithms are based on Markov chain Monte Carlo(MCMC) methodology but build also on techniques from numerical analysis and involve dynamic programming (DP).
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