Rolling Process Parameters Research Articles

Molecular dynamics study on the effects of nanorolling processes on the properties of nickel-based superalloy GH4169

Rolling is a process that can improve the performance and roughness of machined parts and has a special economic value; therefore, the optimization of rolling process parameters is crucial to workpiece performance. In this paper, three rolling methods are used in molecular dynamics (MD) rolling simulations to study their effects on the surface of nickel-based superalloy GH4169 at the nanoscale. The surface and subsurface of the workpiece after rolling with the three different rolling methods are studied separately; in particular, a comparative analysis of the dislocation generation and movement on the subsurface, crystal defect evolution, and surface roughness was performed. The results show that the increase in subsurface dislocation density by average rolling has a significant influence on the work hardening effect, and the average roughness of the rolled groove surface is the lowest. This is an important reference for the optimization of the parameters of actual rolling processes.

Research on variation law of workpiece temperature of three roll skew rolling hollow axle

To explore the variation law of workpiece temperature in the process of three roll skew rolling (TRSR) hollow axle, the process of TRSR hollow axle is tested and simulated in this paper. Firstly, the working principle of TRSR hollow axle is described; Then the blank and rolling process parameters are selected according to the actual performance of TRSR mill; Next, the finite element model is established, and the changes of workpiece temperature are studied; Finally, the simulation results are verified by experiments. The results show that the simulation results are basically consistent with the experimental results. The temperature change of workpiece in the rolling process is very small as a whole, and the temperature drop will be greater only at the place in contact with the die.

Evaluation Method and Application of Cold Rolled Strip Flatness Quality Based on Multi-Objective Decision-Making

Flatness is a vital quality index that determines the dimensional accuracy of the cold-rolled strip. This paper designs a local shape wave extraction algorithm and a fuzzy classification algorithm for overall flatness defect classification based on cosine distance. By introducing the small displacement buckling theory of thin plates, the plate stress buckling model of overall and local shape waves is studied, and the critical buckling elongation difference of the overall shape and the local shape under the given conditions are obtained. Finally, using the multi-objective decision-making evaluation method, a comprehensive evaluation model of the flatness quality is established. The model is applied to the actual cold rolling production. The on-site flatness data are used to verify the flatness quality determination model both locally and overall. The results show that the model can accurately identify the local and overall flatness defects of cold-rolled strips, realizes the accurate identification and evaluation of the cold-rolled flatness quality, and provides strong support for the optimization of rolling process parameters and the improvement of the quality of thin strip products.

Effect of hot rolling process parameters on the microstructure and mechanical properties of continuously cooled low-carbon high-strength low-alloy (HSLA) steel

Abstract In this work, high-strength low-alloy (HSLA) steel with 0.22 wt% carbon was produced in laboratory scale and hot rolled with a total deformation of 42% via 4, 5, or 6 passes. After multipass hot rolling process, samples were examined either in as-rolled (AR) or as-rolled and heat-treated (ARH) conditions. The results indicated that microstructural and mechanical properties of HSLA steels are influenced by hot rolling conditions for both cases. It was observed that strength values in AR samples have a tendency to increase with increment in rolling pass number. In contrast to AR samples, it was seen that the mechanical properties were slightly decreased in ARH samples that were austenitized at 1150 °C for 45 min and then cooled in still air. Microstructural investigations showed that finer precipitates in AR samples are obviously more than that of ARH samples, as an evidence for higher strength results by precipitation hardening. In addition to precipitation strengthening, refinement of lath bainite and amount of blocky martensite/austenite in AR samples favor the increase in strength.

Prediction and mechanism analysis of the force and shape parameters using cubic function model in vertical rolling

Vertical rolling has been widely applied to control slab widths in hot plate rolling plants. In this research, due to the high ratio of width/thickness of the slab in vertical rolling, a symmetric cubic function model is established to depict the three-dimensional dog bone shape of the slab. The three-dimensional kinematically admissible velocity and strain rate fields are innovatively established based on the dual-stream function (DSF) method and the boundary conditions. According to the first variational principle of rigid-plastic, the numerical results of the force and shape parameters are obtained. To decrease the computation load and time, the Geometrical Approximation (GA) yield criterion, the Pavlov projection principle, and the mean value theorem are utilized to calculate the plastic deformation, shear, and friction power terms separately, and the analytical results of the slab shape and rolling force are received later. To certify the effectiveness of the submitted model, the computed slab shapes are compared with the results of other models and the rolling forces are compared with the measurements in a plate plant. Good agreement is found. Furthermore, the effects of key rolling process parameters, such as width reduction, thickness, and vertical roll radius, on the slab shape and stress state are illustrated. The variation mechanisms of the force and shape parameters are used to process parameters setting and adjusting.

Analysis of thread rolling process using an analytical single tooth rolling model based on the slip line field theory and slab method

A thread rolling process is one of manufacturing techniques for producing high performance thread parts. Despite the importance of the process, its design has been dependent on mostly experience of experts, and the parameters of the thread rolling process may not have been systematically optimized. In this study, a new analytical model is proposed for the thread rolling process simplified as a single tooth rolling. The modeling with the slip line field (SLF) theory is used to calculate the protrusion height of workpiece, and the force and torque of the thread rolling are analytically calculated from the classical slab method. Then, the proposed model is used to analyze the effects of lubrication and plastic deformation on the performance of formed part. Moreover, experiments on the single tooth rolling process are carried out to validate the proposed modeling approach. The parametric study shows that the model can predict the force and torque of the thread rolling process with certain accuracy. The viscosity of lubricant has a significant effect on the lubrication pressure, and the friction factor determines the stress during plastic deformation. Also, it is found that the radial feed of the roller has more dominant effect on the lubrication pressure than the tangential speed by squeezing the lubrication during process.

Strengthening [formula omitted]-carbide steels using residual dislocation content

A steel with nominal composition Fe-28Mn-8Al-1.0C in mass percent was hot rolled at two temperatures, 1100 °C and 850 °C and subsequently aged at 550 °C for 24 h. The lower temperature rolling resulted in a yield strength increment of 299 MPa while still retaining an elongation to failure of 26%. The large improvement in strength was attributed to an increase in residual dislocation density which was retained even after the ageing heat treatment. A homogeneous precipitation of κ-carbides in both samples also showed that the high residual dislocation density did not adversely affect precipitation kinetics. These findings demonstrate that the tensile properties of this class of steel can yet be improved by optimising hot rolling process parameters.

Microstructure Evolution of Graphene and the Corresponding Effect on the Mechanical/Electrical Properties of Graphene/Cu Composite during Rolling Treatment.

Rolling enables the directional alignment of the reinforcements in graphene/Cu composites while achieving uniform graphene dispersion and matrix grain refinement. This is expected to achieve a breakthrough in composite performance. In this paper, the process parameters of rolling are investigated, and the defects, thickness variations of graphene and property changes of the composite under different parameters are analyzed. High-temperature rolling is beneficial to avoid the damage of graphene during rolling, and the prepared composites have higher electrical conductivity. The properties of graphene were investigated. Low-temperature rolling is more favorable to the thinning and dispersion of graphene; meanwhile, the relative density of the composites is higher in the low-temperature rolling process. With the increase of rolling deformation, the graphene defects slightly increased and the number of layers decreased. In this paper, the defect states of graphene and the electrical conductivity with different rolling parameters is comprehensively investigated to provide a reference for the rolling process of graphene/copper composites with different demands.

Hydrodynamic effect of technological lubrication and friction modes formation at sheet rolling

One of the main engineering industries is the processing of metals by pressure. Its purpose is the formation of products from metal blanks of simple forms. An important role in this case belongs to the technology of sheet rolling. The solution of issues related to the choice of optimal modes of sheet rolling is relevant for specialists in the field under consideration. The process of rolling metal products is special, since the contact stresses can exceed the deformation resistance of rolled metal by several times. The tasks of predicting the quality of products, taking into account the prevention of sheet metal continuity defects, as well as the study of technological operations reliability of rolling process are associated with the solution of industrial and scientific problems in this area. Domestic and foreign researchers have noted a significant influence of external friction in the deformation center on the technological parameters of rolling process and quality of the resulting metal products. It is known that rolling is impossible without external friction between metal and roll. The reduction of friction provides an opportunity to increase the economic indicators of sheet rolling, and the rolling production technology itself has significant opportunities for further improvement. Technology of sheet rolling in the conditions of hydrodynamic friction mode allows modeling of friction conditions in the deformation zone. Taking into account the hydrodynamic effect of lubrication allows us to assess the influence of technological factors on the conditions of contact friction during metal pressure treatment and to control the rolling process. Regularities of the flow of liquid Newtonian lubricant are investigated, taking into account features of the deformation zone geometry during sheet rolling. Pumping capacity of the lubricating wedge during rolling is determined, which allows us to explain the regularities of lubrication influence on friction conditions. As an example, the results of calculation of the lubricant pressure depending on the rolling speed are presented. The rolling speeds that provide a liquid friction mode are given. The obtained relations allow us to estimate the influence of contact friction on technological parameters of sheet rolling and can be used in technological calculations of this process

Research on dynamic measurement of hot ring rolling dimension based on machine vision

In the process of ring rolling, the rolling process parameters of the equipment have an important influence on the forming process and forming quality of the ring. The ring rolling process has the characteristics of non-linearity, easy interference, rapid growth and asymmetric shape. These factors have resulted in the inability to measure the dimensions of the ring directly. In this work, we established a vision measurement system, and performed a series of operations on the image, such as threshold segmentation, hot ring contour extraction, oxide scale filtering, inner and outer ring extraction, inner and outer ring sampling, data visualization, etc. Moreover, we measured the dynamic dimension characteristics of small and medium size hot ring in the rolling process. The circularity, dimensional difference, center swing and vibration characteristics of the ring in the rolling process are obtained through the algorithm design, which characterizing the size change of the hot ring. The study provides practical methods and theoretical guidance for the subsequent measurement of large-size rings and feedback control of the rolling ring.

Comprehensive evaluation of surface integrity and parameter optimization of 45 steel subjected to ultrasonic surface rolling process

In order to explore the influence of ultrasonic surface rolling process (USRP) parameters on 45 steel surface integrity, the significance of static pressure, amplitude, feed rate and rolling times on rolling effect was analyzed. The grey relational degree of the comprehensive index of surface integrity after USRP was obtained by orthogonal test and grey relational analysis, and the optimal combination of process parameters was obtained. The feasibility of process parameter optimization was verified by experiments. The results show that the significant influence of USRP parameters on 45 steel workpiece surface integrity was as follows: rolling times> feed speed> static pressure> amplitude. The optimal process parameters are rotational rolling times 9 times, feed speed 3200 mm⋅min-1, static pressure 300 N and amplitude 6 μm. Under the optimum combination of process parameters, the surface roughness decreases by 70.8 %. The surface hardness and the surface residual compressive stress increase by 16.5 % and 134 % respectively compared with the surface performance parameters of the material before rolling.

Optimization and Prediction Model of Flatness Actuator Efficiency in Cold Rolling Process Based on Process Data

The accuracy of flatness actuator efficiency (FAE) is a prerequisite to achieve high precision automatic flatness control. This study proposes an accurate acquisition approach of FAE based on the combination of simulation modeling and data‐driven modeling for flatness control of cold‐rolled strip. First, a 3D rolling feature space model is constructed according to the change interval of rolling process parameters based on rolling conditions. A 3D finite element simulation model is subsequently established to determine the prior value of actuator efficiency at each node in the feature space model. Then, to improve the accuracy of prior value, an online optimization model is developed by means of data‐driven mechanism. The sorting algorithm and the central limit theorem are introduced to filter the measured process data and calculate the variable weighting. The processed data are imported into the model to improve the fitting model. Finally, a linear output prediction model based on the trend extrapolation method is proposed to realize the accurate acquisition of FAE under any rolling conditions. The data analysis of the production process shows that the model is adaptive and accurate, which can realize high precision flatness control.

Investigation of cavity filling in profile ring rolling process for T-shape ring

In this paper, key parameters affecting the cavity filling in single and double T-shape profile rings are comprehensively investigated via numerical and experimental analysis. A three-dimensional finite element model was developed in Abaqus\Explicit to assess the influence of crucial ring rolling process parameters, including feed speed, main roll rotational velocity, the existence and the absence of axial rolls on the cavity filling of single and T-shape rings and the main roll torque. Besides, a ring rolling machine was built to conduct practical experiments and validate the numerical evaluation, while for the first time, the role of the axial roll and the main roll torque on the quality of the cavity filling is experimentally evaluated. Power requirements and the final ring profile geometry were obtained by the simulation method, and the results were confirmed by the experiments. The results showed that axial rollers significantly reduced the cavity filling rate, and in contrast, the effect of mandrel feed speed and the main roll rotational velocity was much lower. Also, the axial forces were considerably less than the radial forces. However, the rolling operation was done in both radial and axial directions. The existence of axial rolls had an intensive effect on the process’ required power, as a result the main roll torque increased more than three times in case of applying axial rolls, compared with not considering them. Severe effects of axial rollers on increasing force and decreasing cavity filling rate can be attributed to frictional forces between the ring and axial rolls, restricted ring motion, which has to be compensated by a higher torque of the main roll. When the axial rolls are used, the material flow in the ring’s height direction is restricted. Therefore, the material cannot move easily to form the profile. All experimental and simulation results, including mandrel force, cavity filling, and ring profile geometry, were in good agreement, and in all cases, the simulation error was less than 10%.

COMPREHENSIVE STUDY OF THE DYNAMICS OF THE RETAINING MECHANISM OF THE AUTOMATIC MILL

The results of the study of the dynamics of the mechanism for holding the mandrel of an automatic TPA mill are presented. The value of the axial force acting on the mandrel and the rod system of the mechanism of its holding is determined. Developed models of the mandrel retention mechanism have been developed, which made it possible to establish the nature of the development of dynamic processes on the output side of the automatic mill, taking into account the force parameters of the longitudinal rolling process of the sleeve and the parameters of the output side of the automatic mill. Mathematical models of the mandrel retention mechanism have been developed, taking into account the parameters of the technological process and the inertness of the rolled sleeve. The solution of the system of differential equations with variable coefficients is implemented numerically using the Runge-Kutta method for the corresponding dynamic models of the mandrel retention mechanism on the example of calculating the automatic mill TPA 350. The picture of the formation of dynamic processes in the mandrel retention mechanism during the implementation of the entire technological process of pipe production on an automatic mill has been clarified. taking into account the variable impact from the deformation zone and the change in the mass of the rolled sleeve. For various dynamic models, numerical solutions of problems were implemented, which made it possible to select the necessary technological and dynamic parameters of the mechanical system, to assign stable modes of rolling the sleeves on the automatic mill TPA 350. It is shown that the refined solution of the problem for three developed dynamic models of the mechanical system differs significantly from the previously known mathematical models. It has been established that the dynamics of the mechanism for holding the mandrel of the automatic TPA 350 mill is equivalent to the formation of the mechanism for the formation of different wall thickness of pipes. A mechanism for stabilizing the dynamics of the mandrel holding mechanism by separating the sections of the output side of the mill is proposed.

Plane Strain Compression of Nb-10Hf-1Ti alloy: Effect on Microstructure and Micro-Texture

The development of microstructure in the course of warm deformation of niobium-10 hafnium-1 titanium (wt%) alloy (C103) was studied by plane strain compression (PSC) testing in the range of 500–650 °C and two strain rates (ἑ) 0.01 and 1 s−1 which are commercially being practiced for rolling of the alloys. A total of 75% reduction in thickness was imparted to the samples during the warm deformation. The purpose of the study was to establish the warm rolling process parameters (ἑ and T) useful in the optimization of thermomechanical processing schedules to realize thin sheets of this difficult to process refractory material. Weak softening was noticed at temperatures of 600 °C (~ 0.35Tm) and above in the stress–strain plots. Partial dynamic recrystallisation was observed at the regions where maximum strain was observed in the sample during deformation at high temperatures as evidenced by electron backscatter diffraction (EBSD). Samples deformed in the temperature range of 500 °C to 600 °C and at ἑ of 1 s−1 showed dynamic recovery. High angle grain boundary fraction is higher for the sample deformed at a temperature of 650 °C and ἑ of 0.01 s−1 compared to the sample deformed at a ἑ of 1 s−1. Based on detailed microstructural observations, it was concluded that C103 alloy can be warm rolled at a temperature of 650 °C and ἑ of 0.01 s−1 to obtain localized dynamically recrystallized grain structure in the material and it is expected that a dynamic recrytallization will further advance with increase in reduction during deformation.

Effects of process parameters on surface quality of shaft parts formed by warm cross-wedge rolling

The difference between the warm cross-wedge rolling process and the traditional cross-wedge rolling is that the rolling temperature is controlled below the recrystallization temperature of the workpiece, which has the advantages of reducing energy costs, decarburizing, and improving the surface quality of the workpiece. In this paper, through the combination of simulation and experiment, the effect of process parameters on the surface quality of shafts formed by warm cross-wedge rolling was systematically explored. The results displayed that, for the shafts with large cross-section reduction, increasing the rolling temperature and selecting a small forming and a large stretching angle can improve the surface quality. The selection principles of the stretching angle and the forming angle in the warm cross-wedge rolling process were determined. With comparison, the average error between the experiment and simulation was 1.12%, which verified the reliability of the warm cross-wedge rolling process. The research results provide a theoretical reference for the selection of the process parameters of the warm cross-wedge rolling forming shafts.

A COMPUTER SYSTEM FOR ACQUISITION AND ANALYSIS OF MEASUREMENT DATA FOR A SKEW ROLLING MILL IN MANUFACTURING STEEL BALLS

The article presents the concept and capabilities of a computer system for analysing measurement data for a skew rolling mill used to produce steel balls. The computer system for data acquisition and analysis consists of cooperating systems designed to perform control and measurement tasks during the operation of a skew rolling mill. Their main task is to collect and record data related to the measured physical parameters of the batch rolling process. This system registers the current and analyses the radial forces and torque acting on the rolled element by the rolling tool. The process of data acquisition, analysis and archiving is carried out by means of an NI USB 6009 measuring card together with the attached systems of transducers and force and torque sensors and a computer with an installed application. The measurement application was developed in the LabVIEW environment. The application algorithm is based on the state machine architecture and enables the configuration of measurement elements and technical parameters, checking the functioning of the control and measurement system and the acquisition and archiving of measurement data.

Prediction of Surface Wrinkle Defect of Welding Wire Steel ER70S-6 in Hot Bar Rolling Process Using Finite Element Method and Experiments

High quality products are demanded due to increasingly fierce market competition. In this paper, the generation of surface wrinkle defect of welding wire steel ER70S-6 was studied by the combination of the experimental method and finite element simulation. Firstly, a thermal compression test was conducted on the Gleeble-3500 thermosimulator under different strain rates and temperatures and a strain dependent Arrhenius-type constitutive function was employed to fit the flow stress–strain curves obtained from the experiments. Then, the elastoplastic constitutive relationship was implemented using radial return mapping algorithm by means of the user subroutine VUMAT of Abaqus/Explicit. A new instability criterion was proposed to predict the possibility of the surface wrinkle defect during the multipass hot bar rolling process. In order to verify the reliability of the finite element model of the six-pass continuous rolling process, the simulated results were compared with experimental data. Finally, the effects of groove width and groove radius on the billet were investigated by the orthogonal test method, and the friction coefficient and rolling temperature. The results show that the groove width and groove radius are key factors to suppress the surface wrinkle defect. Decreasing the groove width can be beneficial for improving the surface quality and reducing the fillet radius. The optimized combination of the rolling process parameters was further applied in an industrial test and the surface quality of the billet was greatly improved.

Investigation of Self-Oscillations and the Development of a Procedure of Stabilization of the Process in a Continuous Mill for Strip Cold Rolling

We study the problem of operation of sheet rolling mills under the conditions of nonstationary technology, the stochasticity of the parameters in the presence of negative self-oscillation vibration processes associated with the “chatter” phenomenon. We determine the parameters of stability of the process of sheet rolling, reveal the main causes of the chatter phenomenon, and describe the mechanism of their initiation. We also propose a procedure for the identification of this phenomenon by continuous statistical processing of the parameters of rolling process. As a result of the performed investigations, we developed a method aimed at the adjustment of the technology, which excludes vibration and enables us to enhance the productivity of rolling mills by means of increasing the average speed of rolling.

Effects of thread rolling processing parameters on mechanical properties and microstructures of high-strength bolts

Abstract Bolt production with a grade of 10.9 class quality made from AISI4140 material with a low thread rolling index is usually implemented in accordance with the thread rolling method (cold forming) in industrial applications. In this method, the effects of die revolutions and multiple passes are unknown in the thread forming process as the devices are usually operated with respect to geometrical dimensions but not the mechanical properties and microstructures of the material. In the literature there are few studies on microstructures of low-carbon steel having a higher thread rolling index in bolt production. This study experimentally examined the effects of the processing parameters on the mechanical properties and microstructures. Parameters such as forming speed and single or multi-pass influences were considered in the production of M12 × 1.75 and M20 × 2.5 fasteners widely used in industrial applications. The experiments identified the behavior of the mechanical properties, microstructures and micro-hardness of the AISI4140 material at two forming speeds (rpm) and three passes in the thread rolling process. Thus, significantly sensible outcomes as a function of processing parameters were obtained considering the thread strength viewpoints.