A methodology of roll pass design calculation for rails rolling using regression equations

In process of shaped profiles experimental rolling, it is often necessary to make adjustments to new roll pass design to ensure their physical filling, control between gaps in the values of real broadenings and reductions. In order to reduce number of possible adjustments in roll pass design process and mastering new profiles, the task of developing a model for calculating roll passes becomes actual. A model for calculating roll pass design for rolling railway rails presented. This model based on roll pass design for rolling R65 rails. The regression equations of deformation logarithmic degree were derived using example of two pre-finishing and finishing roll passes, which were used to calculate UIC60E1 rail roll pass design. A high degree of convergence of the geometry of the calculated and operating roll pass has been established. The maximum deviations from geometry of existing roll pass and calculated ones according to proposed method did not exceed 1-2 mm on each of them. It was shown that the developed model calculates exact roll pass geometry, which can be loaded into the program of a processing machine. The proposed calculation methodology can be used at roll pass design of shaped profiles of the same type of different profile sizes of the same mill, resulting in significant reduction of roll pass designed development time and number of adjustments.

Tire/Road Rolling Resistance Modeling: Discussing the Surface Macrotexture Effect

This paper deals with the modeling of rolling resistance and the analysis of the effect of pavement texture. The Rolling Resistance Model (RRM) is a simplification of the no-slip rate of the Dynamic Friction Model (DFM) based on modeling tire/road contact and is intended to predict the tire/pavement friction at all slip rates. The experimental validation of this approach was performed using a machine simulating tires rolling on road surfaces. The tested pavement surfaces have a wide range of textures from smooth to macro-micro-rough, thus covering all the surfaces likely to be encountered on the roads. A comparison between the experimental rolling resistances and those predicted by the model shows a good correlation, with an R2 exceeding 0.8. A good correlation between the MPD (mean profile depth) of the surfaces and the rolling resistance is also shown. It is also noticed that a random distribution and pointed shape of the summits may also be an inconvenience concerning rolling resistance, thus leading to the conclusion that beyond the macrotexture, the positivity of the texture should also be taken into account. A possible simplification of the model by neglecting the damping part in the constitutive model of the rubber is also noted.

Comparative analysis of damage criteria for screw rolling using computer simulation

Two-high screw rolling of billets was carried out using a MISIS-130D rolling mill. AISI 321 steel billets were deformed with feed angles of rolls of 6°, 12°, 18° and 24°. The diameter reduction was 17%, with the initial billets’ diameter being 60 mm. An axial fracture, the so-called Mannesmann effect, of the billets was observed after screw rolling. The experimental rolling was simulated using QForm finite element method software. Initial and boundary conditions were set in concordance with the experimental rolling. Several damage criteria were used for fracture prediction during computer simulation. The results of computer simulation of fracture prediction were compared with the billets fracture after screw rolling for stationary and non-stationary stages. The most effective parameter (in terms of fracture prediction) is triaxiality. The distribution of this parameter showed that the higher the feed angle value is, the lower the fracture risk is. Notably, the risk of fracture is lower at a stationary stage compared with the same risk of fracture at a non-stationary stage; the listed trends agree with experimental rolling results. The Oyane, Ayada, Brozzo, and Cockroft-Latham Normalized criteria are partly effective. These criteria are ineffective for fracture prediction 6 degrees feed angle of rolls because they showed that fracture is most probable at the billet’s surface, which contradicts the experimental rolling results. All these criteria are partly effective when predicting a less fracture risk at a stationary stage compared with the same criteria at a non-stationary stage or when predicting a decrease of fracture with increasing the rolls feed angle.

Analysis of pipe piercing on PRP 70-270 with FEM modeling

The article analyzes the piercing and rolling process of seamless pipes on PRP 70-270 of JSC “VMP” in terms of power parameters, piercing time and geometric sizes of pipes. The research results were compared with the results of computer simulation on software package QFORM 3D. For simulation, the deformation zones were designed for piercing a mold tube with dimensions of 203×16.5 mm in one pass on a mandrel with diameter of 162 mm and in two passes of piercing and rolling-off on mandrels with diameter of 76 and 162 mm, respectively. From the obtained data on the power parameters, it was found that from the point of view of energy consumption, piercing in one pass seems more appropriate. However, when piercing in one pass, wear resistance of the mandrels sharply decreases, since the contact time between the tool and the hot metal increases. This leads to a decrease in quality of the pipes’ inner surface, more frequent replacement of the tool and increased downtime of the equipment. During simulation, the selected parameter of the friction factor has a significant impact on the value of power parameters (torque and power consumption) and piercing time. The dependences of changing power parameters and piercing time on the friction factor during piercing in a two-roll mill with guards are obtained. With increase of the friction factor, piercing time decreases and torque and rolling power increase. The simulation results are correlated with results of experimental rolling. With a correctly chosen value of the friction factor, power parameters and geometry of the mold tube can be quite accurately predicted by computer modeling.

Perfection of rolls sizing in bar & wire rod mill 370/150 to ensure accuracy in rolled product profile

An actual problem of production bars with increased geometry accuracy at existing mill 370/150 at OJSC “BMZ -management company of Holding “BMC” has been reviewed. The object of research was reducing-sizing mill, composed of three finishing stands. The subject of research was rolling process in finishing stands aiming at achieving highly accurate geometry in the finished profile. In the work, based on empirical data, efficiency of existing methods of sizing by statistical method to produce a profile of regular accuracy and highly accurate profile was assessed. By the method of finite elements the rolling processes were simulated, approximated to real conditions by means of numerical modeling. Empiric and theoretic data revealed drawbacks of existing systems of sizing, as well as let determine further direction of research. Analytical description of key factors of rolling affecting creation of profile enabled to come to conclusion that the basis for achieving geometry sizes of transversal profile depends on pressure of steel on to rolls and the inter-stand tension. On this basis the new method of sizing has been developed. On the basis of the new method of sizing, rolling processes at different frequencies of rolls rotation were simulated. The process of mathematical simulation to the maximum approximated to real conditions of rolling. Thanks to this it became possible to obtain reliable results of research, enabling to achieve highly accurate geometry of transversal profile. Obtained results of research are the basis for further study of inter-stand deformation to be followed by experimental rolling at mill 370/150.

Forming of rail car axles in a CNC skew rolling mill

This study relates to an innovative method for forming rail car axles by skew rolling in a CNC 3-roll mill. The rolling mill was constructed at the Lublin University of Technology. The use of this machine makes it possible to produce elongated axisymmetric parts that are up to 55 mm in diameter and up to 1000 mm in length. Experimental rolling tests are performed (in 1:5 scale) using this machine. Two types of axles are analysed: one manufactured in accordance with North American standards (AAR Class E) and one manufactured in compliance with European standards (BA302). Diameters of produced axles have a dimensional accuracy of ± 0.4 mm. Produced axles are free from internal cracks, and their surface defects (shallow helical grooves) can easily be removed by machining. The major shortcoming of the proposed method is the presence of chucking allowance. To eliminate this allowance, it is proposed that the forming process should be performed in two operations: rolling extrusion and skew rolling. Results of a numerical analysis were performed using the Simufact.Forming program confirms that rail car axles can be formed by the proposed method.

Forming Features and Properties of Titanium Alloy Billets After Radial-Shear Rolling

Radial-shear rolling (RSR) of titanium alloy billets was realized in a three-high rolling mill. Experimental rolling was simulated using DEFORM software. The purpose was to reveal how stress-strain state parameters, grain structure and hardness vary along the billet’s radius in the stationary stage of the RSR process. It was also the goal to establish a relation between stress state parameters, hardness and grain structure. Changes in the accumulated strain and the stress triaxiality were established by computer simulation. Hardness and grain size changes were obtained after experimental rolling. The novelty aspect is that both computer simulation and experimental rolling showed that there is a ring-shape area with lowered strength in the billet’s cross-section. The radius of the ring-shape area was predicted as a result of the research.

Theoretical And Experimental Analysis Of Aluminium Bars Rolling Process In Three-High Skew Rolling Mill

Technology of round bars rolling on a three-high skew rolling mills allows rolling of standard materials such as steel and aluminum, as well as new materials, especially hard deformable materials. The paper presents the results of theoretical and experimental rolling process of aluminum bars with a diameter of 20 mm. As the stock round bars with a diameter of 25 mm made of aluminum grade 1050A and aluminum alloy grade 2017A were used. The rolling process of aluminum bars has been carried out in a single pass. The numerical analysis was carried out by using computer program Forge2011®. On the basis of theoretical research it has been determined the state of deformation, stress and temperature distribution during rolling of aluminum bars. In addition, the results of theoretical research allowed to determine the schema of the metal plastic flow in the roll gap. Verification of the theoretical research was carried out during the rolling of aluminum bars on the RSP 40/14 laboratory three-high skew rolling mill. From the finished bars were taken the samples to set the shape and compared with the results of theoretical research. Finished aluminum round bars were characterized by low ovality and good surface quality.

Development of Radial-Axial Ring Rolling Experimental Equipment and Calculation of Ring Rolling Forces

By referring to the heavy duty radial-axial ring rolling mill in production, a radial-axial ring rolling experimental equipment was designed and developed. Based on the principle of similarity, the mathematical relationship and calculation method between experimental rolling forces and actual ones in the process of radial-axial ring rolling were established. This experimental equipment has many advantages, such as compact structures, full functions, small deformation and more safety and reliability, which can be used in experimental study and calculation of ring rolling forces.

Modelling Static Recrystallisation Textures Using a Coupled Crystal Plasticity-Phase Field Technique

An integrated crystal plasticity-phase field model has been developed to simulate the static recrystallisation textures of both Face-Centred Cubic (FCC) and Body-Centred Cubic (BCC) metals. Nucleation sites are determined using the Orientation Dependent Recovery (ODR) theory. Both the interface mobility and the grain boundary energy are set to be dependent on mis-orientation angles in the simulations. A pre-deformed microstructure without a particular texture is generated using a Monte Carlo simulation. Plane strain compression textures before recrystallisation are predicted by a Crystal Plasticity Finite Element (CPFE) model showing a good agreement with the typical experimental rolling textures. It is shown that the typical recrystallisation textures for FCC and BCC metals can be simulated correctly using a Phase Field (PF) method by choosing appropriate critical values for the nucleation criterion. A comparison between the two different nucleation criteria based on the ODR theory or the stored energy is also presented.