Profile Design of the Grooved Die and Rolling Force Prediction in the Cold Pilger Rolling Process

The objective of this study was to design the die groove profile and predict the rolling force produced when employing the variable curvature rolls and mandrel for manufacturing seamless pipes using the cold pilger rolling process. The parameters of the key process design were the diameter of the initial tube and final product, as well as the feed amount, reduction area, principal deformation zone, and roller radius. The rolling forces during the pilger rolling process were theoretically calculated to enable their prediction, and the characteristics of the cold pilger rolling process were identified. The calculated values were in close agreement with the experimental data. The die groove design is important in the prediction process because the dimensional accuracy of the tubes and the life of the dies are highly dependent on this design. The presented design method can be successfully applied to fulfill this objective. The tube shape and adequate tolerance can be attained by using the proposed design method. The mechanical properties of the pipe are evaluated by calculating the Q factor.

Optimization of the interference parameters of an Orbit motor using genetic algorithm

In the present study, the leakage of fluid due to gap generation at the contact points is eliminated by introducing interference between the rotor and the stator of an Orbit motor. Interference is incorporated in the system by modifying the roller radius, the chordal thickness, and the pitch circle radius. In an Orbit motor of interference-fit type, the contact points and the rotor center deviate from their original positions as found in an Orbit motor of perfect-fit type. A corrective technique based on minimization of the potential energy of the system is used to obtain the rotor center of an interference-fit motor. The rotor profile is initially generated around the geometrically obtained center of a perfect-fit motor. It is then shifted in the direction of decreasing potential energy, until the rotor center corresponding to minimum energy is attained. The main drawback of introducing interference is the generation of an unbalanced torque which affects the output torque of the motor. Thus, optimization of interference parameters using genetic algorithm is carried out to determine a system for which no gap is generated at the contacts and simultaneously it is ensured that the unbalanced torque ripple amplitude is minimum.

Working out of design procedure of sheet metal straightening parameters on roller-type straightening machine in rollers of different diameter

It is installed that non-uniform deviations from planeness of sheet different in magnitude, and also having negative and positive curvature at straightening on the traditional roller-type straightening machine, as rule, are not corrected, as the car has equal diameters of all working rollers which affects on planeness defect of sheet with equal curvature of rollers barrels. Dependences for calculation of roller radius and return bend angle are presented. It is shown that if the return bend angle is equal to initial bend angle of sheet at counter-camber the sheet is completely detected; if the return bend angle is less than initial bend angle of sheet return bend occurs partially, the sheet also is detected partially; if the return bend angle is more than initial bend angle of sheet the sheet is bent towards return bend. Dependences for calculation of powers of the editing spent for alternating bending of sheet, the power spent for friction of rolling motion of rollers on surface of sheet, the power spent for overcoming of frictional force on necks of carrying rollers in roller-type straightening machine with rollers of different diameters. Calculation of power consumption of the main drive electric motor at straightening of sheets from low-alloy steel for 5 —7-roller straightening machines with different diameters of rollers is presented. Difference between calculation results and the experiment data showed, difference makes 10...20 % that testifi es to adequacy of model and about possibility of its practical use for calculations of straightening parameters of sheet products on roller-type straightening machine with different diameters of rollers.

Investigation on the Backlash of Roller Enveloping Hourglass Worm Gear: Theoretical Analysis and Experiment

This paper proposes a single-roller enveloping hourglass worm gear design and verifies its advantages compared to the existing double-roller worm gear system and the conventional worm gear set. Our hypothesis is that the single-roller worm gear with appropriate configurations and parametric values can eliminate the backlash in mating gear transmission while maintaining advantages of the double-roller worm gears. Also, the self-rotation of the rollers when they are in the worm tooth space (TS) will help the gear system to avoid jamming and gear tooth scuffing/seizing problems caused by zero backlash and thermal expansion. In order to test that hypothesis, a mathematical model for the single-roller enveloping hourglass worm gear is developed, which includes a gear engagement equation and a tooth profile equation. Using that model, a parametric study is conducted to inspect the influences of center distance, roller radius, transmission ratio, and the radius of base circle on the worm gear meshing characteristics. It is found that the most effective way in eliminating the backlash is to adjust the roller radius and the radius of base circle. Finally, a single-roller enveloping hourglass worm gear set is manufactured and scanned to generate a 3D computer model. That model is compared with a theoretical model calculated from the developed mathematical model. Comparison results show that both models match very well, which verifies the accuracy of the developed mathematical model and our initial hypothesis that it is possible to achieve transmissions with zero backlash by adjusting the design parameters.

Analysis of multi-sensory CMM use for the measurement of rolling bearing elements

The possibility of using the multi-sensory coordinate technology for measuring the selected elements of rolling bearings is presented. The results of spherical cap of conical roller radius and angle between the main and auxiliary track of the conical bearing inner ring measurements are also presented.

Modelling the Meshing of Cycloidal Gears

Cycloidal drives belong to the group of planetary gear drives. The article presents the process of modelling a cycloidal gear. The full profile of the planetary gear is determined from the following parameters: ratio of the drive, eccentricity value, the equidistant (ring gear roller radius), epicycloid reduction ratio, roller placement diameter in the ring gear. Joong-Ho Shin’s and Soon-Man Kwon’s article (Shin and Know, 2006) was used to determine the profile outline of the cycloidal planetary gear lobes. The result was a scatter chart with smooth lines and markers, presenting the full outline of the cycloidal gear.

Prediction of Edge Crack in Cold Rolling of Silicon Steel Strip Based on an Extended Gurson–Tvergaard–Needleman Damage Model

Edge cracking is commonly observed in cold rolling process. However, its failure mechanism is far from fully understanding due to the complex stresses and plastic flow conditions of steel strip under the rolling condition. In this paper, an extended Gurson–Tvergaard–Needleman (GTN) damage model coupled with Nahshon–Hutchinson shear damage mechanism was introduced to investigate the damage and fracture behavior of steel strip in cold rolling. The results show that extended GTN damage model is efficient in predicting the occurrence of edge crack in cold rolling, and the prediction is more accurate than that of the original GTN damage model. The edge cracking behavior under various cold rolling process parameters is investigated. It comes to the conclusion that edge crack extension increases with the increase of the reduction ratio, tension and the decrease of the roller radius and friction coefficient. The influence of shear damage becomes more significant in rolling condition with a larger reduction ratio, smaller roller radius, lower friction force, and tension.

Nonlinear Evolution of the Travelling Waves in Roll Coating Flows of Thin Viscoelastic Polymer Falling Films

Roll coating is widely used to apply a thin liquid film to a continuous, flexible substrate. It is known that macroscopic instabilities of the film system can result in a non-homogenous film growth to fluid flow. The influence of the Rossby number, the viscoelastic parameter, and the roller radius on the nonlinear hydrodynamic stability of a thin viscoelastic polymer fluid film coating flow down a rotating vertical roller is investigated. In contrast to most previous studies, the solution scheme employed in this study is based on a numerical approximation approach rather than an analytical method. The size of the explosive supercritical instability region increases significantly as the roller rotates. It is shown that the stability of the liquid film is enhanced by reducing the viscoelastic effect or decreasing the speed of the rotating roller. At higher values of the Reynolds number, the tendency of the rotation effect to prompt thin-film instability increases with an increasing roller radius.

THE STABILITY AND FREE VIBRATIONS OF A COLUMN SUBJECTED TO A CONSERVATIVE LOAD GENERATED BY A HEAD WITH A PARABOLIC CONTOUR

The boundary value problem concerning the free vibrations of a slender system subjected to a specific load has been formulated and solved in this work. Heads with parabolic contour have been used to realize the specific load for the first time. The boundary value problem has been formulated using Hamilton's principle. The critical load and the characteristic curves in the plane load–natural frequency have been determined on the basis of the kinetic criterion of stability. Numerical calculations have been assigned to different values of the parameters of the considered system for which the parabolic parameter and the parameter of the roller radius are ranked. The roller is the head of the receiving load. The accuracy of the mathematical model was confirmed on the basis of experimental research based on frequency and modal analysis.

Simulation and Technology Optimization for Rolling Web Wave of Large Size H-Beam

The rolling process of large size H-Beam NH800×300 in multiple working conditions was simulated by using of commercial finite element method software LS-DYNA. the web wave emerged during rolling of H-Beam was specially demonstrated. The main factor which affected the rolling force during the rolling process has been illustrated. The rolling process under the condition of different horizontal roller radius, different friction coefficient and flange/web stretching ratio were numerically simulated. By means of simulation with different flange/web stretching ratio, it could be concluded that the crucial situation to generate the rolling web wave in typical rolling pass is that the flange/web stretching ratio is about lower than 0.93, which may cause the web unstable and the rolling wave.