Method for approximate analysis of interaction of material with rolls in a vibroroll grinder

The article presents the results of a study of the process of material grinding in roller aggregates with various kinematic features. As the object of research, the design of a vibroroller unit is selected, which has great prospects for use in production. A characteristic feature of this unit is a significant influence on the grinding process of inertia forces. As the main method of research in relation to the movement of the working bodies of the roller and vibroroller shredder and the crushed material, a method of modeling is adopted. It is presented an approximate analysis of the interaction of the crushed material in roll units with rolls. The crushed material is modeled by a set of horizontal elementary layers. At the first stage, the material is crushed in rolls with constant kinematic parameters. Analytical dependencies of the roll pressure on the material are established. At the second stage, the grinding of materials in a vibroroller shredder is considered. A distinctive feature of the vibroroller shredder is the presence of an eccentrically installed roll. The variant is presented when the eccentric performs a curvilinear translational motion, and the roll performs harmonic fluctuation (vibrations) along the coordinate axes with an amplitude of e. The resulting inertia forces and oscillatory motions of the roll are considered. The analysis of the total force in the unit under consideration, which makes it possible to implement crushing-shear and vibration effects on the crushed material, is carried out. The force interaction of the roll with the material is described by two systems of forces: the elastic forces resulting from the contraction of the model layers according to Hooke’s law, and the forces caused by the vibration of the roll (inertia forces). The results obtained are of practical importance in the design of roller units and vibration equipment, as well as for the analysis of the operation of such designs of grinders.

Comparative study of superelastic Ti–Zr–Nb and commercial VT6 alloy billets by QForm simulation

A comparative simulation of hot radial shear rolling (RSR) of billets made of a superelastic Ti–Zr–Nb and a commercial VT6 alloy was performed using the QForm finite element modeling program. Rolling in 48 modes with a variable feed angle and elongation ratio at 4 levels and initial rolling temperature at 3 levels was investigated for each alloy. The Ti–Zr–Nb alloy rheology during hot deformation was determined experimentally by hot upset forging and imported into the QForm program. The presence of maxima on the flow curves at the initial stage of deformation, which are absent in the VT6 alloy, is revealed. Simulation results are presented in the form of fields of the stiffness coefficient, strain rate intensity, cumulative strain degree in the maximum reduction section depending on the rolling mode. General regularities of the Ti–Zr–Nb and VT6 behavior in RSR are similar. The gradient of the fields studied decreases, and the roll pressure and torque increase with an increase in the feed angle and elongation ratio. The initial rolling temperature does not significantly affect the deformation pattern, but it significantly affects the roll pressure and torque. At the same time, the experimental alloy demonstrated the greater tendency to localize deforming forces in the near-contact zone and to increase the gradient of stress-strain state parameters over the billet section. The study of the tightening shape and depth of rolled billet ends showed that the Ti–Zr–Nb alloy has a 3.5–9.6 % greater tightening depth. It is shown that experimental alloy rolling requires 1.6–2.4 times higher roll pressure and torque as compared to the commercial alloy.

Effects of varying friction coefficient on rolling pressure distribution

Accurate characteristics of roll pressure distribution is essential in the estimation of the energy and power requirements for parts undergoing plastic deformation. The nature of the pressure distribution is very sensitive to the friction coefficient between the roller and the deformed part. The physics of the deformation process points to a variable friction coefficient, however, current research and practices result in the use of a constant friction coefficient. This work explored the development of a technique to determine a quantitative relationship between the variable friction coefficient and the process parameters. The pressure distribution was then developed within the contact region using the variable friction coefficient model. Results show that current approach used by industry (‘the rule of thumb’) overestimates the pressure distribution, compared to the current research, thus wasting power needed for the rolling operation by about 18%. Keywords: Rolling; varying friction coefficient; pressure distribution; power

Review on Parameters Influencing the Rice Breakage and Rubber Roll Wear in Sheller

The present review deals with parameters influencing the rice breakage during rice milling operations and the effect of rubber roll Sheller in rice husk removal process. The main objective of rice milling system is to remove the husk and bran layer to produce the white rice. In this process, rubber roll sheller is used to remove husk from the grains by friction process. If the rubber material is too soft, there may not be sufficient shear force to husk the paddy. Wear will be minimum for rubber material with high hardness but indeed it pronounce the breakage of rice. Hence, for efficient husking the rubber roll material should possess the balance of physico-mechanical properties. Rice breakage depends on several other parameters like the type of harvest, drying temperature, drying methods, physical characteristics of paddy, husking characteristics, paddy moisture content, rubber roller speed, rubber roll pressure, paddy feed rate and fissures. Rubber roll wear depends on the type of rubber material attached to the roller, feed rate, roller speed, pressure etc.

Surface Sizing Aided Effect on the Printing Performance of Decorative Base Paper

With the development of estate and decoration industry, decorative paper become more and more popular, people's needs and requirements are also increasing. However, compared with imported decorative base paper, domestic decorative base paper have a lot of quality problems. In order to improve the performance of domestic decorative paper, surface sizing was used to improve the printing performance and final product quality of domestic decorative base paper in this study. Starch and styrene-acrylic emulsion (SAE) were used as the surface sizing agents for the surface treatment of decorative base paper by the German SUMET coating machine in this paper. Under the conditions of sizing roll pressure of 250N, sizing speed 9m/min, drying temperature and time of 100°C and 70s respective, the effects of metering roller type (No.40 and No.30) and different ratios of starch and SAE ratio (10:1, 15:1, 20:1, 25:1 and 30:1) on the decorative base paper printing performance were investigated in this paper. The optimal sizing conditions and formulation for decorative base paper were as follows: roll pressure 250N, sizing speed 9m/min, drying temperature and time of 100°C and 70s respective, No.30 metering roll, the ration of starch and SAE 20:1. Under this conditions, printing runnability of decorative base paper such as the tensile strength, smoothness were increase greatly and the pH value reached the national standard, the printability such as the color density, tone reproduction range were improved.

Analysis on Crack Propagation of Roll by the Finite-Element

Roller is a main tool and consumption parts for steel rolling. With analysis test on the fatigue property of roller, the development incentives of crack propagation were realized, the service life of roller was improved and the cost of Production was reduced in a large extent. Roller is a circular column, which do fixed-axis rotation under combined action of roll pressure, bearing reaction, Support roller reaction force and torsion. The failure types of roll such as flaking, fracture and crack. Simulate and analysis on damage of the roller crack by the fracture mechanics of knowledge and ANSYS, which shown that compressive was large with the ring and axial and compressive was small with the radial direction, so the compressive of radial direction the analysis had little effect on roll surface.

Through-Thickness Shear Strain in Silicon Steel under Asymmetric Rolling

Through-thickness shear strain variation with speed/radius/friction ratio in cold rolled silicon steel under different asymmetric rolling modes was analyzed by finite element method (FEM). Cold rolling textures were also investigated quantitatively to correlate with the calculated shear strain. With increasing speed/radius/friction ratio, shear strain distribution under differential-speed and differential-radius rolling exhibits similar characteristic in contrast to differential-friction rolling. Unidirectional shear strain develops through sheet thickness when asymmetric speed and radius ratio exceeds 1.125, whereas it does not appear even at friction ratio of 1.5. Shear strain distribution dependent on asymmetric rolling modes can be well understood by forward and backward slip zones as well as roll pressure as a function of speed/radius/friction ratio.