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. Vladimir panjkovic when it comes to metal rolling, understanding and controlling frictional phenomena is essential to improving product and developing a more effective approach to friction reduction. It is essential that in a metal rolling process the level of friction between the rolls and work material is controlled, lubricants can help with this. Friction and surface microstructure in steel cold rolling. Assumes no friction and thus predicts lower roll force than the actual value. Hot rolling of steel manufacturing engineering and materials processing by william l. In this paper, a nonlinear quadratic expression of the coefficient of friction at both entry and exit sides have been derived from the equations of rolling load in hot rolling bland and fords program hrbf. At that higher temperature the steel is transformed in to a single austenite phase from the dual phases of perlite and cementite at room temperature. Friction is therefore a necessary part of the rolling operation, but too much friction can be detrimental for a variety of reasons. The study developed a numerical model for the estimation of coefficient of friction for steel hc ss316 of different thicknesses on two high reversing mills.
Friction and the hot rolling of steel contains a large body of technical information that includes various chemical. Prediction of effect of rolling speed on coefficient of friction in hot. Hot rolling of steel is relatively new technique, probably due to the fact that steel was not available in large quantities until the end of seventeenth century. When the reheating time is increased, the average thickness of oxide scales of stainless steels increases, which results in relatively rough surface after hot rolling.
A welldefined boundary condition is important for generating an accurate model for simulating metal forming process. Secondary scale on hot strip and the impact on wear is another issue. Erik lundberg department of mechanical engineering, institute. Rolling reducing the thickness or changing the cross. The mill trials were further carried out with a hard, alloyed steel type.
Friction coefficients numerical determination for hot. Study on surface roughness and friction during hot rolling of stainless steel 301. It is carried out below the recrystallization temperature and introduces work hardening. Chapter 4 surface finish and friction in cold metal rolling. Hot rolling is often characterized by a condition called sticking, in which the hot work surface adheres to the rolls over the contact arc. Calculate the rolling load if steel sheet is hot rolled 30% from a 40 mmthick slab. Finite element analysis of hot rolling of structural steel yellappa m 1, satyamurthy n2, uday m, giriswamy b g1 and puneet u1 corresponding author. Evaluation of friction in the hot rolling of steel bars by.
Friction modelling of a hot rolling process by means of. At that higher temperature the steel is transformed in to a single austenite phase from the dual phases of perlite and cementite at. Friction and friction coefficients engineering toolbox. Rollers may be plain or grooved depends upon the shape of rolled product. Roberts pdf, epub ebook d0wnl0ad number ten of the manufacturing engineering and material processing series. Request pdf friction and the hot rolling of steel when it comes to metal rolling, understanding and controlling frictional phenomena is essential to improving. When it comes to metal rolling, understanding and controlling frictional phenomena is essential to improving product and developing a more effective approach to friction reduction. Friction and the hot rolling of steel request pdf researchgate. Friction and the hot rolling of steel crc press book. Rolling friction is also sometimes called rolling drag or rolling resistance. As hot rolling is a process with high energy consumption, norton results to be the more complete law for the simulation of rolling processes. However, from these papers, though the values of the coef. Study 20 terms ch 15 multiple choice qs flashcards. Study on surface roughness and friction during hot rolling.
The goal of this project was to develop, on as fundamental a level as possible, a friction model based upon the physics of the process to be applied to the hot rolling of steel. Rolling friction coefficient, formula and examples of. Accordingly a tailor made new hot rolling oil, oil a with high lubrication and excellent dispersion property in water was developed for flat rolling of mild steel and field evaluation was conducted. Friction and the hot rolling of steel contains a large body of technical information that includes various chemical and physical properties of relevant materials, mathematical models, and plant and laboratory observations. One of the prequisites of the hot rolling practice is heating the input bloombilletslab from the room temperature to the rollable temperature. L ubrication plays a vital role in the steel cold rolling process as it determines friction, roll forces and surface quality. Study on the rolling friction and wear properties of.
Evaluation of friction in the hot rolling of steel bars by means of on. Reciprocating friction \ud experiments, which provided a controlled environment in which to investigate friction,\ud were conducted to verify the application of this theory to high temperature conditions\ud and metaloxide contacting materials. In industrial hot rolling processes, oxide scales are inevitably formed on steels by hightemperature oxidation under air. Study on the rolling friction and wear properties of surface densified powder metallurgy fe2cu0. Rolling of ball or wheel on the ground is an example of rolling friction. Counterbodywas driven by a motor via rotation axel, and the tested. Fundamental modelling of friction during the hot rolling. However, scaling is a major issue during hot rolling, due to which dimensional accuracy is difficult to maintain. The effects of oxide scale on the friction condition and surface roughness transfer in hot rolling depend on.
The hot rolling process california steel industries, inc. It is important to characterize the features of the oxide scale in hot rolling of stainless steel strip. The effect of scale thickness on the coefficient of friction in the hot rolling of a low carbon and a microalloyed steels is examined. The objectives are to obtain a desired shape, to improve cast steel s physical properties which are not suitable for most applications, and to produce a surface suitable for a specific use. Previously published data obtained during hot rolling of steel note that comparable data on hot rolling of aluminum was not located in the technical literature indicated certain trends on the dependence of the coefficient of friction on temperature, not all of them in full agreement with oneanother.
The effect of scaling on interfacial friction in hot. The differences between hot and cold rolling can be. It connects the theoretical concepts, laboratoryscale observations, and phenomena in other areas of science and engineering to the largescale industrial process of hot rolling. It also addresses roll properties, oxidation, wear and chemical composition of rolls and their impact on friction, the evolution of friction over schedules and roll campaigns, and mathematical modelling of friction in hot rolling. Surface roughness and friction in hot rolling of stainless. Better strip cleanliness was found, but the differences between the two emulsions remained, both in terms of cleanliness and friction.
Pdf in this paper the friction conditions between the rolls and the workpiece of a hot skew roll piercing mill are studied. Evaluation of friction in the hot rolling of steel bars by means of on line forward slip measurements sven. Friction is one of the most significant physical phenomena influencing metal forming, yet in comparison with metallurgy, heat transfer and mechanics it remains the least understood. Temperature loss during hot rolling by seredynski 1973 is. F r rolling resistance or rolling friction n, lb f. Pdf friction modelling of a hot rolling process by means of the. Accounts for 90% of all metals produced by metal working.
The effect of temperature on the coefficient of friction. This condition often occurs in the rolling of steels and hightemperature alloys. Forming processes convert solidified steel into products useful for the fabricating and construction industries. Cser, mathematical and physical simulation of the properties of hot. Pdf hot friction and wear behaviour of high speed steel.
In this type of friction, there is a restriction on the bodys movement as only one side of the body is in contact with the surface. Chapter 4 surface finish and friction in cold metal rolling michael p. Index termsfem, friction law, friction modelling, rolling process. It also addresses roll properties, oxidation, wear and chemical composition of. The hot rolling process the primary function of the hot strip mill is to reheat semifinished steel slabs of steel nearly to their melting point, then roll them thinner and longer through 12 successive rolling mill stands driven by motors totaling 77,000 hp, and finally coiling up the lengthened steel sheet for transport to the next process. Rolling friction is the resistive force offered by any surface which opposes the rolling motion of any object that rolls over it, thus causing it to slow down and eventually stop. 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. Tribology in metal forming at elevated temperatures. Hot oxidation and hot rolling experiments were undertaken in order to investigate scale formation and its effect on the frictional conditions in the hot flat rolling of steels. Hot friction and wear behaviour of high speed steel and high chromium iron for rolls. Friction in the roll bite under various hot rolling. A similar mechanism can occur in stainless steel rolling, where the shotblast finish on the hot band prior to rolling tends to generate pits. Hot rolling of ingot or a continuously cast slab converts it to.
Friction in the roll bite during steel rolling has always been a topic of interest. By the end of seventeenth century, hot mills using grooveless flat rolls were being employed to reduce the thickness of cuboids into sheets. Friction and the hot rolling of steel contains a large body of technical information that includes various chemical and physical properties of relevant materials, mathematical models, and plant. The force that resists the motion of a body rolling on a surface is called the rolling resistance or the rolling friction. Rolling friction definition, examples, coefficient. Friction in the roll bite under various hot rolling conditions. Cold rolling of hot rolled steel is important, due to high accuracy and lack of oxide scaling. Friction between dry surfaces is the result of the microscopic and submicroscopic r roughness of the two surfaces that come in contact. Hot rolling of steel manufacturing engineering and. Friction and the hot rolling of steel asm international.
Hot rolling results in residual stressfree product. Providing a historical perspective that goes as far back as the days of leonardo da vinci and continues up until the present day, friction and the hot rolling of steel. As reported in reference 12, friction affects significantly the rolling load, roll wear, and strip shape, and, the. Rolling friction occurs when a spherical or round object rolls across a surface.
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