Cold rolling theory pdf

This book discusses the basic theory and principles of rolling processes. Slab analysis is a widely di used method for evaluating the contact pressure in cold rolling processes 16. Shown is a typical stressstrain curve for this material fig 1. It has been observed that increasing cold rolling reduction increases the r m value, at least up to 90% 34. Our products today are sold world wide for all types of metals, including carbon and stainless steels, titanium, copper, brass, bronze, beryllium copper and aluminum alloys.

Fundamentals of roll cooling and control of flatness at. Cold rolling speeds vary but modern mills operate at exit speeds as high as 3000 m per. Lab iii coldworking and annealing of brass study questions 1. Pdf a theory of cold rolling of thin gauge strip is presented which, within the idealizations of homogeneous deformation and a constant coefficient of. The starting material is usually large pieces of metal, like semifinished casting products, such as slabs, blooms, and billets. Secondary scale on hot strip and the impact on wear is another issue. A rolling mill is a complex machine having two or more working rollers, supporting rollers, roll stands, drive motor, reducing gear, flywheel, coupling gear etc. Material is passed between cast or forged steel rolls, which compress it and drag it forward. Perhaps the most important parameters in the production of a strong 111 recrystallization texture are the annealing temperature and the time of holding 35. Contributions to the theory and practice of cold rolling. Comprised of seven chapters, this book begins with an overview of the three principal methods of rolling, including longitudinal, transverse, and skew rolling. Stresses from hertzian pressure in 4high cold mill back up rolls were measured. Define the theory for prediction of specific roll force is central to the development of a model for tandem cold rolling.

After the grains deform during processing, they recrystallize, which maintains an equiaxed microstructure and prevents the metal from work hardening. Rolling is a metal forming process, in which stock of material is passed between one or more pairs of roller to reduce and maintain the uniform thickness. Coiling methods provide improvement of production efficiency and the quality of coldrolled sheet steel by preventing the appearance of such rolling defects as. Based on the theory of the slit beam, this special cold rolling of thin strip was calculated using an influence function method. This seminar provides a comprehensive overview of cold rolling. Furnace is lined with several layers of refractory bricks. Cold mills, in a wide range of types and sizes are available. The course covers fundamentals, equipment, rolling theory, control, threading, rolls, lubrication, measurement, safety and new technology. Theory, simulation and practice find, read and cite all the research you. This is followed by a comparison of the accuracy of previous theory and that of suggested theory in real conditions of chatter. Freshwater, i simplified theories of flat rollingi. Theoretical and experimental analysis of chatter in tandem. One of the most relevant faults in the cold rolling process of steel is called. Reheating furnace x cold stocks are heated to make them soft and thus suitable for rolling.

This is done by introducing defects into the crystal structure of the metal creating a hardened microstructure which prevents further slip. Steel rolling technology handbook 2nd revised edition. Fundamental concept of metal rolling 1 the arc of contact between the rolls and the metal is a part of a circle. This stateoftheart volume examines steelrolling technology in a systematic and comprehensive mannerproviding an excellent synthesis of current information from three different branches of sciencephysics, metallurgy, and engineering.

Metal forming science and practice the flattening rate w is a function of the real area of contact area ratio a and the ratio p y of the mean contact pressure to the plane strain yield stress of the strip, i. Figure 2 represents the strip in the roll bite area, the incoming. The characteristics of the shop equipment for metal forming and technology of the main metal forming methods have been given in separate sections. Attendees will leave this course with a better understanding of the basic metallurgy involved, the different types of products and product attributes, the types of mills used and equipment. Now there is another rolling process, which is a cold rolling process. In the present lecture we consider the analysis considering various stresses acting on an elemental strip. Our experience with cold rolling oils dates back more than 60 years when we blended our first product for a sendzimir mill rolling stainless steel in pennsylvania.

Rolling is an economical method of deformation if metal. Strip thickness control of cold rolling mill with roll. Then, a new theory for explaining chatter mechanism using wave propagation in elastic solids is developed. In this regard, gr is more flexible, thus allowing rolling schedules that ensure a fuller utilization. The course was designed to provide a comprehensive overview of cold rolling, including fundamentals, roll mill designs, rolling theory, gauge and flatness control, inspection practices, lubrication systems, hydraulic systems, roll cooling, roll characteristics, cold mill safety, and operational bottlenecks. Stresses from hertzian pressure in 4high cold mill back up rolls were measured years ago, the results were never published, but of high interest also, maybe later.

With the publication of this book, newcomers to the field of steel rolling have a complete introductionto the cold rolling process, including the history of cold rolling, the equipment currentlyin use, the behavior of the rolling lubricant, the thermal and metallurgical aspects of the subject, mathematical models relating to rolling force and power requirements, strip shape, and thefurth er. The tandem cold mill vibration known as chatter or rumble is a rolling phenomenon occurring in mills throughout the world. The plastic deformation occurring in the rolling mill process can be modelled and studied according to various methods proposed in the scienti. The dependences of the stressstrain state of the coils on the strain degree, temperature, velocity, strip rolls surface roughness during cold strip rolling are considered. Rolling is classified according to the temperature of the metal rolled. Hotrolling refers to a mill process in which you roll the steel at a temperature above its recrystallization temperature. Rolling is an economical method of deformation if metal is required in long lengths of uniform cross section. Cold rolling reduction is an important factor that affects drawability of if steel. Introduction the optimization of manufacturing and product quality is possible when the effect of each process stage and its influence on the process parameters are known. Rolling is a metal forming process in which metal stock is passed through a pair of rolls. Visual analysis of a cold rolling process using databased. Rolling process animation rolling mill machine concept. In the process of rolling the most significant aspect is the generation of heat through friction and deformation in the roll bite and in a typical cold tandem mill, work roll temperatures normally fall in the range of 55oc 70oc with strip recoil temperatures and interstand strip temperature rarely exceeding 160 oc depending on product.

Longstanding experience as a leading supplier of coldrolling mills as a lifecycle partner for coldrolling mills, primetals technologies offers complete solutions and support packages for coldrolling mills that extend from the initial investment idea, to mill planning, layout, engineering and construction, up to turnkey plant installations and fullscale plant modernizations. The correct way to fix a leaking joint unsoldering got2learn. Cuttingedge coldrolling mills primetals technologies. Research article multiplemodalcoupling modeling and.

To produce high quality products in tandem cold rolling with the trend towards thinner rolled strips. Rolling is the process of reducing the thickness or changing the cross section of a long workpiece by compressive forces applied through a set of rolls, as shown in figure 51. Cold rolling precision forming of shaft parts theory and. Chapter 4 surface finish and friction in cold metal rolling. Mechanics of cold rolling of thin strip intechopen. The mechanism of cold rolling forming is extremely complex, and research on the processes, theory and mechanical analysis of spline cold rolling forming has remained very limited to date. In cold rolling the work material is likely to undergo strain hardening as it comes out of the rolls. Steels of different grades can be produced as hotrolled or coldrolled. The fundamental of metal forming theory, the theories of processes of rolling, forging and stamping as well as drawing and pressing extrusion have been given. Hot rolling is a metalworking process that occurs above the recrystallization temperature of the material. Efficient cold rolling and coiling modes springerlink.

The thickness decreased and width increased as expected, an example would be the first test run where the thickness and width before cold rolling were 2. Report on best available techniques bat in the german. Roll pressure distribution of the classical theories. Forged steel rolls were also improved for cold rolling to give higher hardness penetration after. An advantage of gr is in a greater number of independent control parameters than in sr and rd three against two and one, respectively.

Hotrolling and coldrolling should not be mistaken for different grades of steel. Mechanics of cold rolling of thin strip 443 where yiw is the vertical deflection of the work roll at element i, gijw, is the influence function for the work roll deflection due to the combined bending and shear forces generated by rolling load, giwf is the influence function for the work roll deflection due to the force generated by the roll bending mechanism, k represents the minimum element. The domino theory was a cold war policy that suggested a communist government in one nation would quickly lead to communist takeovers in neighboring states. This increases the yield strength and hardness of the metal.

This rolling process is done below the recrystallization temperature of the metal it varies upon the metal, room temperature can also be a below recrystallization temperature. Rolling rolling is the most important metal working process and can be performed on either hot or cold metal. Hidden potential of cold sheet rolling springerlink. This is the starting point of the hot rolling mill practice. Consider a piece of metal being deformed in tension. Pdf a new theory for cold flat rolling researchgate. Fundamentals of rolling presents the theoretical knowledge of longitudinal rolling in a comprehensive procedure. Symmetric rolling sr where the roll speeds are equal and rollingdrawing rd where the roll speed ratio is limiting are versions of general rolling gr. In practice, the forming processes and production methods used are mainly. The calculated results show that the specific forces such as the rolling force, intermediate force and the shape and profile of the strip for this special rolling process are significantly different from the forces in the traditional cold rolling process, and those form a new theory of metal plasticity in metal rolling. The tension modes of coldrolled strip coiling are analyzed. Cold rolling is a process which passes metal through rollers at temperatures below its recrystallization temperatures.