Idle Roll Research Articles

Flatness defect control during cold rolling of SUS430 stainless steel

Abstract A statics finite element (FE) model as well as a dynamics FE model for Sendzimir mill have been established. It is in order to solve the bilateral wave defect caused by loose edge rolling during the cold rolling process with SUS430 stainless steel strip. The profile and flatness control effects are quantitatively analyzed by adjusting various roll contour configurations such as work roll crown, the second intermediate idler roll crown, the first intermediate roll taper depth and taper length. The coupling relationship between strip edge-drop and flatness under different roll contour configurations has been studied to analyze their effects on flatness defect control. The first intermediate roll taper depth is the most effective way to control edge wave. The first intermediate roll taper depth has been adjusted from 0.4 mm to 0.6 mm in the industrial production line. The overall profile has been improved by 21.5 %. The deviation of residual stress at strip edges has been reduced by 32.9 %. An excellent flatness defect control result has been achieved for the industrial production of SUS430 stainless steel. The present work is responsible for providing a theoretical basis and practical experience for the flatness defect control technology of a Sendzimir mill.

A multi-objective optimization workflow of ring-rolling process parameters based on production energy and time

Our industrial era is characterized by a significant attention to environmental aspects and production sustainability. Under this point of view, the minimization of the process energy represents a milestone leading to a consistent reduction of pollution. However, to promptly react to the high production rate market request, companies employ time saving manufacturing strategies, often in contrast with this principle. Considering this, an optimization concerning the reduction of both production time and energy, results to be strategical, especially when energy-intensive processes, such as ring rolling, are considered. Ring rolling is a shaping process performed by a dedicated equipment, composed of a driving roll, an idle roll, and a couple of axial rolls, allowing to obtain seamless rings while simultaneously reducing their height and thickness, while enlarging diameter. The kinematics of each component of the equipment can be set independently. This leads to several process conditions influencing quality, energy, and times, and makes it difficult the selection of the most suitable configuration. In this paper, a multi-objective optimization workflow is presented. Starting from validated FEM simulation campaign results, the proposed methodology allowed to individuate the best process parameters combination for limiting energy and time, encouraging its application to a wider range of energy-consuming processes.

Abrasive wear resistance of idler roll polymeric materials

Idler rolls are an integral part of belt conveyors. Recently, steel idler rolls have been replaced with polymeric ones in low to middle load applications, bringing several advantages due to the polymer’s lightweight and low abrasiveness in the conveyor belt. However, using polymeric material for high load application brings challenges, particularly presenting similar structural and abrasion resistance to steel. This work puts forwards a methodology using a rubber-wheel tribometer to evaluate the abrasion resistance of polymeric idler rolls in their most severe operating condition (halted idler roll) and defines a threshold limit based on the results obtained with steel idler rolls. The methodology was applied to 07 different polymeric materials. To further understand materials abrasions resistance, scratching tests were performed, and the main wear mechanisms, verified by scanning electron microscopy (SEM) and abrasion factor (FAB), were discussed along with the material properties. The main conclusions are: i) some polymeric materials present abrasion resistance similar to steel rolls; ii) the wear micromechanisms, verified by SEM and FAB, are good indicators of abrasion resistance of the materials but insufficient because they do not include temperature and fatigue effects resulting from multi abrasive events; iii) the additive fillers significantly altered the abrasive resistance of materials, although they do not change the material properties significantly.

Investigation of The Dynamic Deflection of Conveyor Belts Via Simulation Modelling Methods on Idler Factor

Belt conveyor is today’s very important mechanism in material handling industries and is most commonly used to transport bulk materials such as grain, salt, coal and sand. Belt deflection indicates belt is loosening. It occurs between the idler roll sets due to the self-weight of the belt and the forces from the bulk material. This paper includes detailed analysis of the conveyor belt deflection under pragmatic load conditions. The aim of the project is to develop a Finite Element Method (FEM) simulation model for the deflection analysis of a conveyor belt using load data for bulk material calculated by a coupled Discrete Element Method (DEM) simulation. The scope of this project is on idler roll aspects. Two types of three-trough idlers were used in this project which were made of steel and plastic respectively. A variety of idler spacing were used to determine the most efficient configuration for the belt. This paper will explain the FEM procedures for the modelling of the belt behavior and the working principle of a coupled FEM-DEM analysis. Experimental results were presented and compared based on parameters. Comparisons showed plastic idler-rollers with smaller gap is better than the rest and it could be optimized to improve the performance and efficiency.

An innovative constraining ring rolling process for manufacturing conical rings with thin sterna and high ribs

Conical rings with thin sterna and high ribs (CRTSHR) are key bearing-load parts of aerospace equipment, which are required to be manufactured with high performance and efficiency. Traditional ring rolling is the most preferred method for manufacturing high-performance ring parts, but it can hardly achieve the forming of CRTSHR due to the extreme geometry of CRTSHR. To solve this difficulty, an innovative constraining ring rolling process (CRR) is proposed in this paper to manufacture CRTSHR. To evaluate the proposed CRR and reveal its deformation behaviors, a thermomechanical coupled FE model for CRR of CRTSHR is established. Then, the experiment for CRR of CRTSHR is performed on a modified ring rolling machine, which proves that CRR of CRTSHR is feasible and the established FE model is reliable. Based on the reliable FE model, the metal flow mode in deformed CRTSHR is analyzed, and the deformation characteristics such as the stress state, strain distribution and the evolution of power parameters in CRR of CRTSHR are revealed. Finally, the influences of key parameters such as the friction factor between ring and molds, the diameter of idle roll and the feed velocity of idle roll on CRR of CRTSHR are investigated by FE simulation.

The Acoustic Camera as a Tool to Identify Belt Conveyor Noises

This paper explores the possibilities of using an acoustic camera as a tool that allows the verification of the correct construction and operation of individual elements of a belt conveyor. Based on the simultaneously recorded components - a video camera and measuring microphones, the sound pressure level map of the belt conveyor was created. The tests were carried out in laboratory conditions and covered the location and identification of individual noise sources. The verification consists not only of searching for dominant sound sources, but above all, of searching for frequencies in the analysed spectrum that should not occur during their proper operation. The tests allow for the identification of frequencies and the determination of the sound pressure level for three noise sources: the electric motor noise, the idler roll bearing noise as well as the noise on the tail pulley caused by belt misalignment.

Ring Rolling speed rolls optimization to improve ring quality and reduce production time

In this paper, an analysis of the production time reduction as a function of the Idle and Axial rolls speed law in a Ring Rolling process was examined. Starting from an industrial case study, the authors defined a new milling curve able to produce a better ring quality with lower loads. From this result, the authors tested the effect of the production time reduction till the 40% of the initial one. The Ide roll velocity was varied in a range between 0.71 and 1.13 mm/s while the Axial roll between 0.35 and 1.70 mm/s. Geometrical and load parameters have been taken into account to compare the results achieved. The authors identified in the external ring diameter and in the Idle roll maximum load the most critical parameter to control; in particular, a break-even point was determined in order to select a set of rolls speed laws able to produce a good quality ring with lower production time (about 20%) and lower loads (about 10 %). In this research both experimental and numerical approaches were followed.

Analysis of conveyor belt flexure resistance

The University of Newcastle has designed and built a large test facility to measure the combined indentation rolling resistance and belt flexure resistance. This test facility allows tests to be conducted on a full-sized conveyor belt over a range of tensions and belt velocities and is designed in accordance with an Australian standard [1]. The test facility applies tension to the conveyor belt using two hydraulic rams and applies a vertical load by deflecting the conveyor belt over two adjustable height rolls via hold down rolls set apart at equal distances to the measurement idler roll.Experimental results from the University of Newcastle test facility include measurements of both indentation rolling resistance and belt flexure resistance in combination. A way is needed to separate the indentation rolling resistance and belt flexure resistance into their individual components. One approach is to predict the belt flexure resistance component and validate the prediction by measuring the indentation rolling resistance using the DIN22123 [2] experimental method. In this experimental method the belt is tensioned by two hydraulic rams and the vertical load is applied with an idler roll placed above the measurement idler roll. The setup has the advantage of applying the vertical load without flexing the conveyor belt. The results from the DIN standard will provide indentation rolling resistance individually, and this can be compared to the Australian Standard [1] of measuring the combined indentation rolling resistance and belt flexure resistance.Two methods of measuring indentation rolling resistance and belt flexure resistance components will be discussed in this paper, analytical models will be presented and, in combination with laboratory test data, trends identified to reduce the motion resistance.

A parametric study on the dynamics of two-span roll-to-roll microcontact printing system

The recent trend towards micro-patterning of thin film webs brought stricter manufacturing tolerances than traditionally admissible vibration levels. Therefore, one has to consider roll-to-roll (R2R) systems with their system dynamics model encompassing all systems’ components, namely, the axially moving web(s), the rotating rolls and other accessories. In this study, the dynamic characteristics of an axially moving web in a two-span R2R system are investigated. Influence of geometrical parameters on the R2R dynamics and the parametric resonances of the moving web is presented. The time variations of web axial speed and web-transmitted tension are rigorously obtained by solving the web tension–roller angular speed equation, which is obtained from the conservation of mass law. The effects of system parameters such as length of the web, inertia of idler roll and radius of the rewinding/unwinding roll on the angular speed and web-transmitted tension have been discussed. The axially moving web was modelled as a string, which was mathematically represented by a second-order hyperbolic partial differential equation. The effect of the frequency of the disturbance at the roll on the web dynamics is also discussed. The transverse vibration response at selected points on the web shows higher frequency fluctuations corresponding to lower transport axial speed. It is noted that instability in the transverse response will occur when the first and second frequencies of the oscillation converge.

Investigation of the dynamic deflection of conveyor belts via experimental and modelling methods

In a belt conveyor system the belt and conveyed bulk material experience cyclic movement due to the presence of the belt sag during operation. This dynamic belt deflection results in the trampling resistance of the belt conveyor. Dynamic belt deflection is complicated as it depends on the properties of the belt and bulk material, belt and material interaction and the configuration of the belt conveyor such as the idler spacing, belt tension and speed. To investigate belt deflection for variable dynamic conditions, a specially designed test facility has been constructed, which replicates the relative movement of a belt and idlers by moving several idler roll sets underneath a fixed belt. The main components of the test facility are described in this paper. A new experimental approach based on a photogrammetry technique is proposed for dynamic belt deflection measurements. Moreover, a coupled Finite Element Method (FEM) and Discrete Element Method (DEM) model is developed to predict the dynamic belt deflection. Experimental results were presented and compared to the results from the theoretical calculations and simulations. Comparisons showed a good correlation between simulation and experimental results.

Microstructure and Mechanical Properties of As-cast 42CrMo Ring Blank During Hot Rolling and Subsequent Quenching and Tempering

The hot rolling of as-cast 42CrMo ring blank and its subsequent quenching and tempering were conducted based on the casting-rolling compound forming technique. The effects of feed rate and tempering temperature on the microstructure were studied by optical microscopy and scanning electron microscopy. The mechanical properties of the rolled rings were examined. The results show that when the feed rate of the idle roll increases, the degree of grain refinement becomes slightly smaller and the average grain size is approximately 44 μm through the whole thickness of the rolled ring. The microstructure is inhomogeneous near the center-layer and minimum spread region, which is characterized by a small amount of irregular and coarse grain. The strength and hardness of the hot-rolled rings are high, and the plasticity and toughness are relatively low. The depth and diameter of the dimples in the fracture of the ring fabricated with a low feed rate are larger than those of the ring fabricated with a high feed rate. The carbide particles cannot be observed in the rolled rings after the rings are quenched and tempered at 803 K, but the fine and dispersed particles are precipitated by tempering at 863 K. As a result, the mechanical properties are significantly improved and satisfy the technical demands after quenching and tempering. The fractures of both tensile and impact specimens are characterized by regular and fine dimples at a higher tempering temperature, which indicates that a dimple fracture and an excellent combination of strength, plasticity and toughness are obtained.

Force Model and Elastic Deformation Analysis of 20-High Sendzimir Mill Rolls

A 20-high Sendzimir mill is widely used in cold rolling. The deformation of rolls within the roll system as a whole is analyzed without pin-pointing upon each roll and impact on the rolling process. The mechanical model of the work roll, first intermediate roll, second intermediate driven roll, and second intermediate idler roll was proposed and the contact force of each roll was calculated in the rolling process. The finite element model was constructed on the basis of calculation results, the elastic deformation of each roll was analyzed in three rolling passes. It was found that the resultant force of the work roll was the maximum of all rolls, and the maximum elastic deformation of each roll was observed in the second rolling pass; the radial elastic deformation of each roll would influence the plate, its quality, viz. an uneven strip thickness. Each roll is subjected to cyclic stress, so the bending deformation of roll can reduce its service life, producing the fatigue crack.

Laboratory measurement of the indentation rolling resistance of conveyor belts

Abstract The indentation rolling resistance of conveyor belts is an important design consideration for long belt conveyors and can also be important for heavily loaded belt conveyors. Indentation rolling resistance is dependent on the properties of the conveyor belt, including the carcass and bottom cover as well as properties of the belt conveyor including induced loads, belt speed, ambient temperature and idler roll diameter. A purpose built laboratory test facility is described to measure the indentation rolling resistance of conveyor belts. The test facility is designed to accept both fabric and steel cord belts and test over a range of typical operating parameters and conditions. Results are presented for a range of test parameters, including; load, belt speed, idler roll diameter, ambient temperature and bottom cover compound. Application of the test data to conveyor design is also presented with the aim being to show how the test facility can be used to improve the accuracy of conveyor belt tension calculations by more accurately evaluating the performance of different rubber compounds and belt constructions.

Influence of tension and release in piped conveyor belt on change of normal contact forces in hexagonal idler housing for pipe conveyor loaded with material

Every kind of transported bulk material influences operational characteristics of the pipe conveyors significantly. Therefore it is necessary so that users of the pipe belt conveyors are able to perform a more detailed investigation and monitoring of these characteristics. Thanks to information concerning the operational characteristics it is possible to analyse durability of the conveyor belt and extent of belt wearing. However, the process of data collection and identification is demanding and expensive on condition that such process would be realised only by means of measuring equipment. Much more effective is obtaining of the needed information using generalized knowledge in the form of graphs. Every operator of the pipe belt conveyor is able to obtain the required information based on known input values using the corresponding graphs. Afterwards, the obtained information can be applied in a real operation. This article deals with determination of the contact force values for a certain type of the conveyor belt. The contact forces can be estimated in the intersection of axis at the individual idler roll positions in dependence on the tension force and in dependence on the filling rate of the cross-sectional area of the piped belt with the material, taking into consideration the performed experimental measurements.

The indentation rolling resistance of spherically profiled idler rolls

The energy loss due to indentation rolling resistance in a conveyor belt system can account for up to 60% of the total power usage. It arises due to an asymmetric pressure distribution as a viscoelastic belt cover is indented by a rigid idler roll. This causes a retarding moment on the idler roll, dependent on the load, speed, idler diameter and the properties of the conveyor belt cover. As pouch conveyor systems become more prevalent in industry, the supporting structure, and thus the indentation rolling resistance of such systems is of importance. These designs typically employ curved belt profiles, or spherical idlers in order to aid belt tracking and closing. From this, a spherical indentation into a generalised Maxwell backing is modelled, and compared with experimental values. In addition to this, the strain dependency across the contact is investigated.

Speed Idle Roll Law Optimization in a Ring Rolling Process

Ring Rolling is a complex hot forming process where different rolls are involved in the production of seamless rings characterized by extreme dimensions (i.e. external diameter higher more than 1m). Because each roll can be independently controlled from the other ones different speed laws must be set; usually, in the industrial environment, a milling curve is introduced to monitor the shape of the workpiece during the deformation in order to ensure a correct ring production. In former works the authors focused their attention on the influence of different milling curves for an industrial case and the results underlined that a ring produced with a good quality and lower loads and energy could be obtained imposing a linearly descending trend to the Idle roll speed law. However different approaches could be used in order to evaluate the mentioned speed law.In this work the authors enhanced the knowledge about the optimization of the Idle roll speed law: different Idle roll speed laws were designed and simulated and the results were compared in order to identify the best speed law that guarantees a good quality ring with lower loads and energy required for manufacturing.

Milling Curves Influence in Ring Rolling Processes

Ring Rolling is a complex hot forming process used for the production of shaped rings, seamless and axis symmetrical workpieces. The main advantage of workpieces produced by ring rolling, compared to other technological processes, is given by the size and orientation of grains, especially on the worked surface which give to the final product excellent mechanical properties. In this process different rolls (Idle, Axial, Guide and Driver) are involved in generating the desired ring shape. Since each roll is characterized by a speed law that can be set independently by the speed law imposed to the other rolls, an optimization is more critical compared with other deformation processes. Usually, in industrial environment, a milling curve is introduced in order to correlate the Idle and Axial roll displacement, however it must be underlined that different milling curves lead to different loads and energy for ring realization. In this work an industrial case study was modeled by a numerical approach: different milling curves characterized by different Idle and Axial roll speed laws (linearly decreasing, constant, linearly increasing) were designed and simulated. The results were compared in order to identify the best milling curve that guarantees a good quality ring (higher diameter, lower fishtail) with lower loads and energy required for manufacturing.

Analysis of asymmetrical effect of tension forces in conveyor belt on the idler roll contact forces in the idler housing

This paper analyses an impact of asymmetrical tension forces, which are occurring in the conveyor belt, on the contact forces in the guiding idlers. It describes causes of an increased wear-out of the conveyor belts due to an asymmetric tensioning of the transport belt. There were investigated five measuring points loaded with a symmetrical and asymmetrical tensioning of a specimen section of the pipe conveyor transport belt, using the Friedman test for the factor of asymmetry. The tension force determines also changes of the contact force layouts in the individually investigated idler rolls. A newly developed method was applied in order to identify states of the particular experimental phases for the process of the transport belt tensioning and relaxation. This method is based on differences of the contact force time behaviours. It is possible to present a hypothesis, taking into consideration the obtained results that a side slipping of the running conveyor belt is caused by the tension force asymmetry also on the real operational conditions.

Technology and experiments of 42CrMo bearing ring forming based on casting ring blank

Bearing ring is the crucial component of bearing. With regard to such problems as material waste, low efficiency and high energy consumption in current process of producing large bearing ring, a new process named “casting-rolling compound forming technology” is researched by taking the typical 42CrMo slew bearing as object. Through theoretical analysis, the design criteria of the main casting-rolling forming parameters are put forward at first. Then the constitutive relationship model of as-cast 42CrMo steel and its mathematical model of dynamic recrystallization are obtained according to the results of the hot compression experiment. By a coupled thermal-mechanical finite element model for radial-axial rolling of bearing ring, the fraction of dynamic recrystallization is calculated and recrystallized grains size are predicated. Meanwhile, the effects of the initial rolling temperature and feed rate of idle roll on material microstructure evolution are analyzed. Finally, the industrial rolling experiment is designed and performed, based on the simulation results. In addition, mechanical and metallographic tests are conducted on rolled bearing ring to get the mechanical parameters and metallographic structure. The experimental data and results show that the mechanical properties of bearing ring produced by casting-rolling compound forming technology are up to industrial standard, and a qualified bearing ring can be successfully formed by employing this new technology. Through the study, a process of forming large bearing ring directly by using casting ring blank is obtained, which could provide an effective theoretical guidance for manufacturing large ring parts. It also has an edge in saving material, lowering energy and improving efficiency.

FE simulation and experimental research on cylindrical ring rolling

During the conventional ring rolling process, the ring mainly produces the incremental deformation of wall-thickness reduction and diameter expansion, which makes it difficult to manufacture the cylindrical ring with small diameter and large height. In this paper, a new method for manufacturing the cylindrical ring using a ring blank with smaller height, i.e. cylindrical ring rolling, is proposed and its feasibility is verified. For evaluating the cylindrical ring rolling process and to better understanding its deformation characteristics, a 3D elastic–plastic FE model of cylindrical ring rolling is first established. Then, the comparison between conventional ring rolling and cylindrical ring rolling is investigated using this 3D FE model. Finally, the effects of the process parameters, such as the feed rate of the idle roll, diameter of the idle roll and friction coefficient between the rolls and ring, on cylindrical ring rolling are numerically revealed. The experiment is carried out on a vertical NC ring rolling machine and the good agreements between the experimental and simulation results verify the validity of the established 3D FE model of the cylindrical ring rolling.