13th International Conference on the Technology of Plasticity (ICTP 2021): Rolling
Program Organizers: Glenn Daehn, Ohio State University; Libby Culley, The Ohio State University; Anupam Vivek, Ohio State University; Jian Cao, Northwestern University; Brad Kinsey, University of New Hampshire; Erman Tekkaya, TU Dortmund; Yoshinori Yoshida, Gifu University

Friday 9:15 AM
July 30, 2021
Room: Virtual: Room D
Location: Virtual

Session Chair: Warren Poole, University of British Columbia


Hot Ring Rolling and Cold Expanding Strengthening of Mn18Cr18N Thick-wall Hollow Ingots: Huiqin Chen1; Huihan Wen1; Jinliang Wang1; Fei Li1; Wenwu He1; 1Taiyuan University of Science and Technology
    A short route manufacturing process of retaining rings was put forward, which composed of hollow ingots manufacturing by ESR, hot ring rolling and cold expanding strengthening. And microstructure mechanisms, deformation characteristics and process parameters during both of hot ring rolling and cold hydraulic expanding strengthening were investigated. The results show that the multi-pass flow stresses decreased with increase of interval time. During multi-pass compression, grain refined at lower temperature of 1050C by static recrystallization, then grain refined at higher temperature of 1150C by both of dynamic and static recrystallization. Based on the influence of the contact arc length ratio on strain penetration in the wall deformation zone, the driving roller radius of 500mm and the pressure roller radius of 130mm were determined for the ring rolling process ofφ712mm/308mm902mm thick-wall hollow ingot. The optimum rotate velocity of the driving roller should be 0.8rad/s. And the feeding velocity of the pressure roller should to be 1mm/s for matching. During cold deformation, planar slip and twinning predominated at small and large deformation respectively to increase strength. For the hydraulic expanding process of 937/672×1034mm hollow forging, the optimum matching of 60 punch angle and 5mm contact seal height can be adopted for obtaining well-shaped strengthened forgings.

Fundamentals of Continuous Helicoid Auger Flighting Rolling - Deformation Mechanics, Kinematics and Applications: Ming He1; 1The Timken Company
    An auger flighting is a helical-shaped circular product to transfer bulk materials in broad applications. Continuous auger flightings are formed from straight steel strips by a specialty rolling mill. Because of the geometry and configuration of the auger flighting, the rolling is more complex than the ordinary longitudinal rolling while the publication describing the theoretical features of the auger flighting rolling was hardly seen. In this article, fundamental kinematics and mechanics of the auger flighting rolling are mathematically developed, from which the contact area, rolling force and torque are calculated and the affecting factors are evaluated. Slip characteristics between the strip and forming rolls and the effects of roll offset are studied. The design considerations, primarily of the main roll shafts and the required rolling mill power, are also given. The application results were compared to the actual rolling readings with satisfactory agreements.

Decoupling of Adverse Effect of Inter-roll Thrust Force on Steering Control during Strip Rolling: Kazuma Yamaguchi1; Atsushi Ishii1; 1Nippon Steel Corporation
     Inter-roll thrust force due to roll misalignment in 4-high strip rolling mill affects difference in roll forces measured by load cell on the work side and that on the drive side. Since the roll force difference is utilized for strip steering control, in which roll gap tilting control is done assuming the roll force difference reflects strip off-centering behavior, the inter-roll thrust force gives serious disturbance to the steering control, and may cause troubles like tail crash. In this paper, an inter-roll thrust force decoupling method for the steering control is proposed. The method utilizes measured thrust counter forces acting against work roll chocks to obtain effective roll force difference for the steering control. Validity of the decoupling method is confirmed using a laboratory 4-high mill which can control cross angles between rolls and measure the work roll thrust counter forces.

Effect of Delivery Angle on Longitudinal Buckling in Temper Rolling of Thin Steel Strips: Toshiro Okazaki1; Yukio Kimura1; Hideo Kijima1; Masaru Miyake1; 1JFE Steel Corporation
    In temper rolling of double reduced thin sheet strips, shape defect called “longitudinal buckling” appears. In previous study, the effect of several rolling conditions on the longitudinal buckling was investigated. However, effect of delivery angle over 4 degree has not been experimented. In this paper, effect of large delivery angle is investigated in laboratory rolling. Results show that by increasing delivery angle, the buckling appears clearly and the number of waves decreases, and by delivery angle over 24 degree the buckling disappears. Next we calculate the buckling characteristics of the sheet which twines around the work roll by the elementary theory. We find that the change of number of waves by delivery angle calculated from the analysis almost agrees with the experimental result when delivery angle is larger than 10 degree. It is estimated that the shape of sheet which twines around the work roll affects the longitudinal buckling phenomenon.

A Fast Computational Model for the Local Stress Distribution and Mechanical and Thermal Work Roll Deformations with Effects on Strip Profile and Flatness during Hot Rolling of Strip in Four-high Mills: Christian Overhagen1; 1University of Duisburg-Essen
    A fast model is presented for the three-dimensional stress and roll force distribution along the strip width. This local data is used to calculate the 3D deformation of the work roll barrel by flattening and deflection using a combined analytical and finite element procedure. Detailed information about the work roll deformation can therefore be obtained because the model does not rely on a constant roll force. The local strip and work roll temperatures are calculated by numerical solution of the heat equation and the evolution of thermal roll crown is calculated for a given rolling campaign. The strip shape is found by intersection of the deformed roll with the initial strip. An upper-bound technique is applied for the resulting strip flatness. Typical methods of profile and flatness adjustment (roll crown, roll bending, zonal roll cooling, CVC) are discussed with effects on strip profile and flatness.

Study on the Transferability of Rolling with Ordered Texturing Roll: Yasuyuki Fujii1; 1Kobe Steel/Mechanical Working Research Section
     The texture rolling is to transfer the roughness on the strip from the textured roll surface. From our previous studies, it was confirmed that the relative velocity in the roll bite is an important factor in the prediction of transferability, and that these depends on the pseudo friction coefficient.In this paper, we investigated the relationship between the roll surface morphology and the friction coefficient using the ordered texturing roll. We carried out the experiments with the 3 kinds of rolls which have 1) RD and 2) TD and 3) 45 degree groove. From these experiments, we evaluated the pseudo friction coefficients of each conditions by using rolling load. As the result, we found that the roll with higher transferability has higher friction coefficient. These pseudo friction coefficients come from the geometrical shear stress.

A Computational Study on the Producible Rolling Thickness in Ultra-thin Strip Rolling: Xiao Liu1; Hong Xiao1; Chao Yu1; 1Yanshan University
    It is very difficult to continue the cold rolling process of a thin strip when the strip has been thinned to a certain thickness. The Stone formula is the most common approach for predicting this limit, but it was found that the results obtained from this formula are rather inaccurate when applied in experiments or the production of ultra-thin strip rolling. In this paper, the variation law of the contact profile and rolling pressure of ultra-thin strips with different conditions were obtained by FEM, which provide a new definition for the Stone minimum thickness. Furthermore, a theoretical computational model of producible rolling thickness for an ultra-thin strip based on the Fleck theory was established, providing theoretical guidance for practical production by defining the product specification ranges and rolling regulations for existing rolling mills and determining the roller diameters and force and energy parameters for the design of rolling mills.

Investigation of a Novel Constructive Hot Ring Rolling Process for Double Metal Composite Ring: Jiadong Deng1; Zhe Cheng1; Dongsheng Qian1; Jikang Liu1; Rongwen Wu1; 1Wuhan University of Technology
    Double metal composite ring has the advantages of two materials, which is widely used in specific fields. The traditional manufacture method is welding. And some scholars try to use ring rolling process to produce a composite ring. However, the interface connection quality is not well. In this paper, a novel constructive hot ring rolling process to manufacture a seamless double metal composite ring is proposed. First, two separate rings with different metals are assembled together. And then the surface interface area on the upper and lower of the assembled ring are welded in oxygen-free environment, which can suppress the interfacial oxidation during heating process. After that, the surface welded ring is cleaned and heated. Finally, the target double metal composite ring is formed by hot ring rolling. An experiment of constructive hot ring rolling process for double metal composite ring was carried. The interface healing effect of the composite ring was detailed studied. The result indicated that the interface healing degree was significantly improved by this method.

Achieving an Interference Fit between Two Rings during Composite Ring Rolling: Christopher Cleaver1; Julian Allwood1; 1University of Cambridge
    Composite ring rolling could bring substantial material, cost and energy savings and allow for lighter weight components, by joining concentric rings with different material properties. For there to be any possibility of achieving a material bond, an interference fit between the rings must be maintained. In this paper, a force equilibrium-based model is introduced to predict when such a fit is possible. This model, for radial composite rolling, predicts a limit to the flow stress of the inner ring relative to the outer ring; suggesting a maximum ratio of about 160%. It also shows that the inner tool’s diameter must often be significantly smaller than the outer tool’s. The model was successfully tested in four composite ring rolling experiments with two grades of Aluminium alloy, 1050 and 6063, and different tool sizes, suggesting it could be a valuable new guide to designing composite ring rolling processes.

Advanced Design of Work Roll Contours for Different Roll Mill Types: Xiawei Feng1; Xiaochen Wang1; Quan Yang1; Zedong Wu1; 1University of Science and Technology Beijing
     Modern steel producers are competing to roll Non Grain Oriented Silicon (NGOS) steel strip with 1.25 meter in width, 0.5 to 0.35 mm in thickness and a profile deviation that is less than 5 micron-meters. Mathematical models are indispensable tools to study the mechanism of work roll contours during rolling, but industrial try-outs are required to validate their effects on strip profile. Thus, this paper presents the effects of various work roll contours designed for: 1) the 6th and 7th stand of a 4-high hot tandem rolling mill; 2) single stand 6-high reversing cold mill; 3) 1st, 2nd and 3rd stand of a 6-high tandem cold mill; Results show that the NGOS strip profile hit rate of 5 micron-meters is increased by the implementations of advanced work roll contours.

A Novel Flexible Skew Rolling Process for Step Shafts: Feasibility Study: Longfei Lin1; Baoyu Wang1; Jinxia Shen1; 1School of Mechanical Engineering, University of Science and Technology Beijing
    This paper develops a novel flexible skew rolling (FSR) process to produce step shafts. The process includes four stages: radial rolling, rollers inclining, skew rolling and rollers levelling. Each roller has three freedoms (circle rotation, radial rotation and radial-feeding motion), which can manufacture different axles by programming different rollers’ movements that can achieve flexible rolling with same tools. A flexible skew rolling mill with dual-rotatable-shafts (DRM-80) was invented and manufactured, and feasibility experiments were performed at this mill. A shaft (total length 605 mm, minimum diameter 50 mm) was formed, and has well dimensional accuracy. The main forming defects include knurled pockmarks, helical grooves, side cavity, and diameter tolerance. The experimental FSR part is free from internal cracks by observing the transverse and longitudinal section. The study results verified that the novel flexible skew rolling process is positive and the new type DRM-80 mill is reliable.