Review of Contact and Dynamic Phenomena in Cold Roll Forming

This review reflects the state of the art in study of contact and dynamic phenomena occurring in cold roll forming. The importance of taking these phenomena into account is determined by significant machine time and tooling costs spent on worn out forming rolls replacement and equipment adjustment in cold roll forming. Predictive modelling of the tool wear caused by contact and dynamic phenomena can reduce the production losses in this technological process

Clustering of Steel Strip Sectional Profiles Based on Robust Adaptive Fuzzy Clustering Algorithm

In this paper, the intelligent techniques are applied to enhance the quality control precision in the steel strip cold rolling production. Firstly a new control scheme is proposed, establishing the classifier of the steel strip cross-sectional profiles is the core of the system. The fuzzy clustering algorithm is used to establish the classifier. Secondly, a novel fuzzy clustering algorithm is proposed and used in the real application. The results, under the comparisons with the results obtained by the conventional fuzzy clustering algorithm, show the new algorithm is robust and efficient and it can not only get better clustering prototypes, which are used as the classifier, but also easily and effectively detect the outliers; it does great help in improving the performances of the new system. Finally, it is pointed out that the new algorithm's efficiency is mainly due to the introduction of a set of adaptive operators which allow for treating the different influences of data objects on the clustering operations; and in nature, the new fuzzy algorithm is the generalized version of the existing fuzzy clustering algorithm

The Development of a Heat Assisted Section Rolling Process for Strip

This research aims to examine the feasibility of a new concept in section rolling of thick strip, which either could not be rolled at present due to cracking at bent corners. Whereas, the second moment of area of sections could be increased through sharpened corners and increased gauge thickness. A heat assisted section rolling process is proposed. This process is based on application of high intensity heat on the inner surface of the strip, immediately prior to rolling. To investigate the new section rolling concept, the following work has been carried out. Firstly, the material property of the S450 steel has been determined using the Gleeble simulator, followed by thermal conductivity tests. Since a freon was used to increase temperature gradient, the heat transfer coefficient for the freon-hot surface interaction was determined. Finally, the four point hot bending tests were conducted to validate the simulation model. For this purpose, a hot bending test rig was designed and fabricated, utilizing an halogen heater as the heat source. The results between experiment and simulation were compared and a good correlation was found. Then, finite element analyses of a single pass hot rolling process has been adopted to investigate the neutral axis shift and section thickening effects. It is revealed that localised heating creates bulging on the compressed surface. The bulged surface affects the both neutral axis and thickening of the formed parts. This research has demonstrated that localised heating has a potential to be employed in section rolling operations. It shows that the neutral axis of the bent region shifted closer to the tensile surface would reduce the tendency for surface cracking. In addition, the increase in thickness that arises at a bend would enhance the stiffness of rolled sections. Ultimately a process window for heat assisted section rolling has been established.Imperial Users Onl

Numerical Modelling and Simulation of Metal Processing

This book deals with metal processing and its numerical modelling and simulation. In total, 21 papers from different distinguished authors have been compiled in this area. Various processes are addressed, including solidification, TIG welding, additive manufacturing, hot and cold rolling, deep drawing, pipe deformation, and galvanizing. Material models are developed at different length scales from atomistic simulation to finite element analysis in order to describe the evolution and behavior of materials during thermal and thermomechanical treatment. Materials under consideration are carbon, Q&T, DP, and stainless steels; ductile iron; and aluminum, nickel-based, and titanium alloys. The developed models and simulations shall help to predict structure evolution, damage, and service behavior of advanced materials

Design & Development of Three Roller Sheet Bending Machine

Metal forming can be defined as a process in which the desired size and shapes are obtained through plastic deformation of a material without any significance loss of material. Bending is a metal forming process in which straight length is transformed into a curved length. Roller forming is a continuous bending operation in which a long strip of metal is passed through consecutive sets of rollers, until the desired cross sectional profile is obtained. The roller bending process usually produces larger parts of cylindrical or conical cross sections in large quantity. Normal practice of the roller bending still heavily depends upon the experience and skill of the operator. Trial and Error is a common practice in the industry. Rolling process always began with crucial operation of pre bending both ends of the work piece. This operation eliminates flat spot when rolling a full cylindrical shape and ensures better closure. DOI: 10.17762/ijritcc2321-8169.15081

Factors affecting the heat transfer during the dip testing of potential third generation advanced high strength steels

A dip tester was designed and built at Missouri University of Science and Technology to test the effects of the primary alloying elements (Mn, Si, and Al) of Fe-Mn-Al-Si-C type 3rd generation advanced high strength steel (AHSS) alloys, dipping superheat, and dipping speed on the heat transfer during rapid solidification. The difficulties associated with casting 3rd generation AHSS were compiled as well to serve as a best-practices guide. An extensive list of potential 3rd generation AHSS alloys was developed and tested, and the effects of various dip testing parameters were examined. Manganese was found to increase the heat flux by coating the copper blocks with MnO, reducing the air gap and improving the thermal conduction. Aluminum increased the heat flux by shifting the solidification path through multiple phase fields and thereby increasing the amount of enthalpy (heat) rejected upon solidification. The consequences however, were an increase in the secondary dendrite arm spacings and segregation within the microstructure resulting from a longer freezing range. Silicon was found to have no effect on the heat flux. It provided no substantial shift of the solidification path, nor did it increase the heat flux by improving the contact between the melt and copper blocks. Increasing the dipping superheat increased the heat flux by decreasing the melt viscosity and improving the wettability between the melt and copper blocks. An increase in the superheat also increased the driving force for heat transfer from the solidifying sample to the copper blocks --Abstract, page iii

Ultrasonic Measurements of the Strip Thickness, Lubricant Film Thickness, Roll Deflection and Roll Stress in the Roll Bite in the Cold Rolling of Steel

In cold rolling the interface between the roll and strip, known as the roll bite, is key to the finish and geometry of rolled products. This interface is complex and operates in the mixed regime with part asperity contact and part fluid film. The factors which affect this are of interest to the cold rolling community. The inaccessibility of the interface has made direct measurement of its condition difficult. In this thesis ultrasonic approaches have been developed to measure the state of the roll bite, in-situ and in real time. The thesis starts by introducing the background theory underpinning modern cold rolling. The theory behind the proposed ultrasonic measurements is developed. It is proposed that the proportion of longitudinal and shear waves reflected by the asperity and lubricant film components of the mixed mode interface are dependent on their respective stiffnesses. From these the lubricant layer thickness can be calculated. It is also shown how time-of-flight measurements can be used to measure strip thickness, roll stress, roll deflection and roll material properties. Ultrasonic sensor systems were incorporated into pilot and semi-industrial cold-rolling mills. Measurements were taken as steel was rolled under a range of lubrication conditions, with rolling velocities from 25 m/min to 1200 m/min and elongations from 5% to 50%. Stiffness and lubricant film thickness measurements were demonstrated for films from 0.3 µm to ~6 µm. Roll bite contact lengths of 9.13mm to 15.34mm were recorded for elongations from 9.7% to 40%. For these same elongations average radial roll stresses of 180 MPa to 340 MPa and roll deflections of 30 µm to 55 µm at the roll bite centre were measured. Time-of-flight measurements yielded thickness profiles of strip reduced from 2.8mm to 2.154mm. Validation was provided by multiple numerical models which showed good agreement with the ultrasonic results