Using a simple one-dimensional model of the flat rolling process, in which the elastic deformation of the roll is analysed using the theory of elasticity (Roychoudhury and Lenard, 1984) and the stress–strain relations, the forces are calculated and found to be quite close to those measured. The flat rolling process is usually taken to be essentially two-dimensional in the sense that the width of the product does not change much during the pass when compared to thickness and length changes and this makes the assumption of plane-strain plastic flow 5 quite realistic. 3. Harshit Aggarwal. One comment was received: “Our analyses are performed to get insight into the mechanics of the process, not for predictions”. The well-known Hitchcock formula (1935) is used in these models to estimate the magnitude of the radius of the flattened but still circular work roll while in a more refined 1D version (Roychoudhury and Lenard, 1984) the elastic deformation of the roll is analysed, using the 2D theory of elasticity. The choice was made to discuss the traditional models and their possible refinements, exclusively. These calculations compare well to experimental data. As mentioned above, the 55% reduction in the second passes caused the roll forces to increase due to increased frictional resistance and the predictions of the model indicate that this is, in fact, the case. 5:17 mins. Sign up for free. Two of these are chosen for a comparison of their predictions: the hyperbolic sine stress–strain rate equation and Shida's equations, both developed to model hot deformation of lowcarbon steels. _abc cc embed * Powtoon is not liable for any 3rd party content used. 1. c. The bite angle in degrees. They simply give the predictions. By DanishBaki  |  Updated: July 4, 2020, 2:10 a.m. * Powtoon is not liable for any 3rd party content used. Of course, the width changes in the flat rolling process and this and its effect on the resulting product have been considered in numerous publications. It is accomplishes in rolling mills. Lenard, ... L. Cser, in Mathematical and Physical Simulation of the Properties of Hot Rolled Products, 1999. The objectives here are similar to those above: that of the calculation of the roll separating force and the roll torque. The present author has been involved in the study of 1D models of the flat rolling process for quite some time. Rolling is also classified according to … The roll radius R=300 mm, the entry speed of the material is 5 m/s, the entry sheet thickness is 3 mm, the draft d=0.3 mm. The reasons are clearly demonstrated in Figure 8.16. These include the necessary theory of plasticity in addition to the application of the theories to the analysis bulk and sheet metal forming problems. In a practical situation, constant magnitudes for both suffice, making use of the best available information. While rolling soft aluminium strips, the coefficient appears to be approximately 20% higher; when harder alloys are rolled, the coefficient is about 10% higher than that for steels. In that model, two values of the coefficient of friction are used, one near entry and one near the exit. J.G. The Steckel mill, the Sendzimir mill and the planetary mill were discussed, accompanied by several illustrations. (1991). One of the outstanding ones, mentioned already in Chapter 4, has been made available by the American Iron and Steel Institute, the details of which can be obtained from the website www.integpg.com/Products/HSMM.asp. (1990), Hodgson and Gibbs (1992), Yada (1987), Beynon and Sellars (1992), Sakai (1995), Kuziak et al. In this lesson, flat rolling process have been explained. An interesting review of on-line and off-line mathematical models for flat rolling was recently published by Yuen (2003). The exception is the formula of Wankhede and Samarasekera (1997) for the coefficient of heat transfer in terms of the pressure, to be used when hot rolling strips or plates. A discussion of modelling the rolling process has been given in Chapter 16 of the Handbook of Workability and Process Design (2003). Select a size, the embed code changes based on your selection. Predict variables which cannot be easily measured (e.g. Definition. Perform sensitivity analyses to determine which process variables should be measured and controlled to achieve the required quality, or final properties, of the product. However, during the process of rolling, the rolled products adopt flatness defects and … When the research studies began to appear in the technical literature, using finite-element models to investigate the flat rolling process, the following suggestion was made to several authors: experimental data would be provided and let us all compare our predictions. Each of the models can be used for modeling and predicting the variables of the process as long as the original objectives of the procedure are kept in mind. This step and the additional assumption of the plane-strain plastic flow condition1 ensure that there will be only one independent variable in the equations: the distance along the direction of rolling or the angular variable around the roll. 5) The velocity of the rolls is assumed to be constant. Their advantages, including their flexibility, and ease of handling, overcome the usual objections of engineers, used to having an equation with which predictions may be made: neural networks don't reveal the details of the relationships among the inputs and the outputs. • Rolling is the most widely used forming process, which provides high production and close control of final product. Material for further reading was also included, classified into two sections. These equations are based on the studies of Sellars (1979,1990)Sellars (1979)Sellars (1990), Roberts et al. (1993). 2.1: Rolling is done both hot and cold. In this process, the threaded dies are fitted on cylindrical rollers of the rolling machine. 6) The metal only extends in the rolling direction and no extension in the width of the material. A model that is accurate only sometimes and for which an error analysis has not been considered5 in the study is essentially useless. The predictions of the model for the Al 6111 aluminium alloy are given in Table 15.4 and the conclusions are as for the two steel alloys. Another comment needs to be mentioned in the context of using the models for predictions of rolling load, etc. The elastic and plastic regions of the rolled strip are considered. Concepts, ideas and expressions concerning the flat rolling process were developed, derived or simply stated in the previous chapters. Material and metallurgical attributes are the topic of Chapter 8 while tribology is treated in Chapter 9. The integrated steel mill and hot strip mill, including its components, were described in some detail. SHARE THE AWESOMENESS. As well, their magnitudes are higher than those found in the case of the 1030 steel, showing the applicability of the adhesion hypothesis and the enhanced ease of the formation of adhesive bonds with the softer steel. A brief presentation of some mill configurations was also given, including two-, four- and six-high arrangements. There are two concepts to consider, however, before good predictive ability is to be acknowledged. These techniques are used with increasing frequency in the manufacturing industry. Examples of raw materials include sheets used in personal computers, appliances, cars, planes, and locomotives. Based on work temperature : – Hot Rolling – most common due to the large amount of The mathematician may consider abandoning the usual technique of developing a model, conducting a few tests and claim success or otherwise when the limited number of comparisons are satisfactory. The final product is usually less than 6 mm thick. In addition to the care in the formulation of the models, the predictive ability of all of them depends, in a very significant manner, on the appropriate description of the rolled metal’s resistance to deformation and on the way the frictional resistance at the contact surfaces is expressed. This is followed by a comparison of the measured powers required for reducing a strip to the recommendations of Avitzur and Roberts. - The process was considered a hot process where the temperature range from an initial workpiece and die temperature These are accuracy and consistency. 8:56 mins. Table 15.3 gives similar results for the 1008 steel. The authors add set-up and on-line control of the rolling mills and the rolling process to the use of the models, in addition to the following (the list is quoted directly from the reference): Minimize mill trials for product and process development. The conclusion is inescapable: the frictional coefficients, thus obtained, are useful for comparative evaluation but, close as they are to the actual magnitudes, they are estimates. He concluded that more sophisticated models are expected to be adopted for on-line applications and added that there is an “urgent need for robust algorithms in order to implement these superior models”. In flat rolling processes, during industrial manufacture, the rolls may typically be 24 to 54 inches in diameter. This is an no question simple means to specifically get lead by on-line. The ingots is a product of continuous casting and heated in soaking pit furnaces. The magnitudes of the coefficient of friction are again realistic and are as published elsewhere (Lenard, 2001). The first section deals with the sensitivity of the predicted magnitudes of the roll separating forces and the roll torques by the mathematical models considered in Chapter 5 to various independent parameters such as the coefficient of friction, the reduction, the strain hardening coefficient and the entry thickness. You’re almost there. Flat-rolled steel is manufactured by rolling, which is performed by starting and ending with a material that has a rectangular cross-section. They are applicable equally well to hot, warm or cold rolling. Overview of the Course. Table 15.2. It is also important to reinforce that the volume The development of the metallurgical structure of the rolled strips is then reviewed and empirical relations, allowing the calculation of these parameters, are listed. When one is to study roll bending and the attendant changes of the shape of the rolled metal in addition to the changes of the field variables across the width – stress, strain, strain rate, temperature, grain distributions – a change from the 2D mathematical formulation to 3D is unavoidable. Comparison of the Measurements with the Predictions of a Simple Model; Rolling of the 1008 Steel Strips, Table 15.4. The flat rolling processes. Lesson 3 of 13 • 6 upvotes • 8:16 mins. The next level of modeling is to determine the forward slip, and, as pointed out above, this requires a still more complex technique. The rolling process is shown in Fig. As expected, they decrease as the reduction is increased. By DanishBaki | Updated: July 4, 2020, 2:10 a.m. Loading... Slideshow Movie. Admittedly this is not much of a change, but it is not taken to be insignificant. Further, the predictive abilities of the models are presented and compared to each other and to experimental data. While the researchers have several possible avenues to follow, one of the approaches, given below, will likely be chosen: Conduct independent testing to determine the metal’s mechanical attributes and use non-linear regression analysis to develop a model for later use. FLAT ROLLING PROCESS. These are the thickness of the oil film at the entry to the roll gap as a function of the viscosity–pressure coefficient and the flow strength of the rolled metal as well as the rate of wear of the work roll as a function of the reduction and the projected length of contact. Having sufficient number of data points, necessary for the development of the empirical relations suggested above, one may consider the use of artificial neural networks (see Chapter 9 for details and case studies). These objectives may include the following: a simple, fast calculation of the roll separating forces; in addition to the roll separating force, the roll torque, the temperature rise and the required power are to be calculated; in further addition to the above, the determination of the metallurgical parameters and the material attributes as a result of the hot and cold rolling are to be determined. A few comments, concerning the propensity of researchers to comment on the predictive capabilities of their models, are appropriate here. About 0% of these are Granulators, 0% are Feed Processing Machines, and 0% are Other Food Processing Machinery. Finite-element models. Tandem cold rolling process involves large number of interrelated parameters. An example of these is presented by Schey (2000). The comments of Barber (1991), quoted above, are still valid. In general terms, increasing viscosity, speed and reduction cause a drop of the coefficient. 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