Roll Design Research Articles

Study of the dynamic processes of the vibratory drum rebound from the compacted surface

Fast dynamic processes of material compaction by vibration rollers represent random dynamic processes, wherein characteristics of the strength of compacted material, humidity, temperature, types of materials and their characteristics change stochastically. However, from the total set of these processes it is possible to single out such processes, which belong to the category of random ones because of their insufficient state of knowledge but they are deterministic. Such processes may include the vibratory drum dynamic vertical movements during the material compaction. In the process of the study the vibratory drum downward and upward movement modes are considered under the action of the dynamic driving force, which while projecting onto a vertical axis turns into a harmonic force acting periodically downwards and upwards and it is a deterministic parameter. Other mass and kinematic characteristics of the vibratory drum are also deterministic ones. On the basis of classic laws of dynamics the vibratory drum bouncing dynamic processes in the final stage of the compaction technological process and accompanying process of the vibratory drum vertical downward movement have been analytically considered. The necessity to solve such problem is justified by the fact that the dynamic process parameter determination by experimental methods is connected with significant physical and material expenses. New knowledge has been obtained that is necessary for the improvement of the vibration roller designs and modes of their operation.

Mathematical and experimental study of deformations of a steel roll of a road roller with a variable geometry of a contact surface

Abstract The lack of a common methodology on compaction theory stimulates developers of road construction equipment to create various approximate methods for their calculation, the number of which, at the present time, is comparable with the nomenclature of the proposed designs of rollers. The article presents the analysis of the deformable shell behavior of a road roller, and the compacted material under its compacting roller, in a situation when a rigid circular shell of the roller is replaced by a forcefully deformable elliptical shape, which, unlike the circular design, allows variation, adjustment and optimization of the road roller impact on the material to be compacted.

Experimental study on leveling mechanism for material-jetting-type color 3D printing

PurposeThe material-jetting-type (MJ) 3-D printing technology has advantages in resolution and color printing. During the printing process, a leveling technique is needed to precisely control the thickness and flatness of each layer. Roller-type leveling mechanism has been adopted in commercial MJ 3-D printers, but it is lack of research on roller leveling process parameters and establishing experimental procedures. Therefore, in this study, a roller-type leveling mechanism for a MJ color 3 D printer was developed, and experimental approaches were utilized to determine process parameters.Design/methodology/approachThe roller-type leveling mechanism was chosen to provide functions of flattening and removal of excess material. The parameters studied were roller speed and rotational direction. Surface roughness, Ra, of printed single-layered specimens was measured at 15 locations for plane roughness and along five lines for line roughness to evaluate the leveling results. Adopting suitable parameters, color samples with and without leveling were printed for comparison and verification.FindingsAccording to plane roughness results, forward rotation achieved better leveling. Plane roughness was the major criteria to determine roller speed with the assistance of standard deviation of line roughness. The best parameters of the self-developed MJ color 3-D printer were found to be rolling forward at 1,100 rpm. In addition, printed color samples showed great improvement in surface roughness with leveling and no obvious color mixing after leveling.Research limitations/implicationsLeveling is important to achieve desired layer thickness, smooth surface and good color quality in color 3-D printing. For MJ 3-D printing, only patents were revealed regarding roller design, but paper publications have not been presented. This research practically proposed to use experimental approach to understand the effects of roller operating parameters and to find the suitable ones based on surface roughness results.Practical implicationsThis research established the experimental procedures and also suggested guidelines of experimentally obtaining suitable roller leveling process parameters. Developers can refer to this study results to design and adjust leveling mechanism in a new MJ 3-D printer.Originality/valueThe experimental approach can be applied to similar MJ 3-D printing systems if different materials are introduced or the platform speed is changed. The observed trends suggested several guidelines to plan limited experiments only to obtain suitable roller process parameters.

The Design of Rollers for Rolling Corrugations in the Ribbon

Corrugated stainless steel ribbon is used as a working element in modern heat exchangers designed for high working temperatures (up to 1000°C). Making corrugations on the ribbon is the most time-consuming operation, which determines the relevance of the study subject. The article offers a method for calculating the tool profile, provided that the centroid is on the outer diameter of the tool. According to the results of calculations and practical studies, this method should be applied. The profile of the rollers was profiled depending on the specified ribbon profile, limits of ribbon profile parameters are determined. The study subject is to determine the grooves profile of the rolling rollers and to determine rational methods for visualizing the rolling process in order to simulate it. To accomplish this aim, the following tasks are to be solved: 1. To determine the rational position of the centroid during the rolling of corrugations on rollers. 2. To determine the parameters of the profiles when the tool centroids are located on the outer diameter of the rollers in the rolling process.

Analytical study of oscillating horizontal vibrations of a road roller

Horizontal oscillating vibrations of a vibratory road roller are of secondary importance in comparison with vertical vibrations that compact soil and asphalt concrete. The consideration of horizontal vibrations is required for the improvement of the vibratory roller design aimed at reducing the overall accompanying vibration on the vibratory roller and on a human operator, as well as for the calculation of vibration exciter rolling bearings and rubber-metal shock absorbers. Two research tasks of vibratory drum horizontal vibrations on a solid non-deformable base have been solved in the article. The assumption has been made in the first task that there is sliding friction between the cylindrical roller and bearing surface; in the second research task of horizontal vibrations the cylindrical drum rolls over a solid bearing surface without slipping. The mode of horizontal oscillating vibrations differs in phase from the mode of vertical oscillating vibrations by the angle φ = 0.5π. When creating vibratory rollers, manufacturing companies strive for increasing the operation efficiency of vibratory rollers at the expense of increasing the centrifugal exciting force while maintaining or reducing the total weight of the vibratory roller. As a result of which the oscillation mode appeared where negative effects of additional loading of rubber-metal shock absorbers were found, connecting the vibratory drum with the roller front frame and increasing the overall vibration of the vibratory roller. Dependences of horizontal travels, speed and acceleration of a vibratory drum have been determined during the road roller forward movement. During one turn of the vibration exciter rotation the forward movement of the drum becomes a non-uniform one, i.e. it takes an oscillating vibrating nature. Rules and recommendations have been developed for the study of sliding conditions, vibratory drum balancing over the bearing surface etc.

Optimal design of side roller to minimize the roundness errors of lead wire sides

This study improved the roundness error of the side portion of a lead wire produced by rolling operations. In the conventional method, the side portion is cut after rolling. As an improvement, a side roller was designed for use after flat rolling to directly form the side portion of the lead wire to reduce the roundness error. A rolling analysis of lead wires was performed using LS-DYNA, which is a simulation program capable of analyzing the dynamic behavior of the material. Finite element modeling of the lead wire was carried out, and the change of the cross section was observed after the wire rolling process. The shape of the side roller was optimized to reduce the roundness error. The angle of the side roller, the installation position, and the shape radius were selected as the design variables. PIAnO (Process Integration, Automation, and Optimization), a commercial PIDO (Process Integration and Design Optimization) tool, was used for the optimum design of the side roller, and the results confirmed that the roundness error was reduced.

Structure design and effects of conical gear roller on restraining rabbit ear defects during gear rolling

The gear rolling process using a conical gear roller was developed recently and has been proved to be feasible for forming cylindrical gears. However, the rabbit ear defect, which is normally present in the traditional rolling process, still exists. Therefore, an innovative structure for the conical gear roller is proposed to prevent rabbit ear defects. The size of the dedendum circle during the tooth forming stage is determined according to the height of the growing tooth on the blank at each moment, and the volume of the roller pressed into the blank is equivalent to that of the objective gear’s tooth space. Both simulations and experiments are carried out to investigate the effects of the revised rollers on the rolling process. The results show that the formation of the tooth profiles can be effectively confined to the desired volume cavity, so that there is no extra space for the formation of rabbit ears. The tooth is fully filled, and the rabbit ear defects are obviously reduced. The experimental results agree well with the numerical simulation. The present study can help in improving the integrity and accuracy of the formed teeth for the gear rolling process.

On discontinuous dynamical behaviors of a 2-DOF impact oscillator with friction and a periodically forced excitation

In this paper, a 2-DOF (two-degree-of-freedom) impact oscillator with friction and a periodically forced excitation is investigated via using the flow switchability theory in discontinuous dynamical systems. Based on the discontinuities caused by friction and impact between the two masses, the phase space is partitioned into different boundaries and domains. Using the G-functions and vector fields, the analytical conditions of grazing motions and passable motions are discussed, and the appearing and vanishing conditions of sliding motions and side-stick motions are also developed. The periodic motions with stick or non-stick are described through the generic mappings. For better understanding of the analytical conditions of periodic motions, grazing motions, stick motions and passable motions, the velocity and displacement time-histories, G-function responses and trajectories are presented. The investigation on such a 2-DOF impact oscillator with friction may be helpful for achieving optimal design of the single row cylindrical roller bearing systems. Besides, it has an important significance to the noise suppression in mechanical systems with clearance.

Analysis of acting forces on rollers under the billet caster mould in the zone of secondary cooling

Abstract Performance of secondary cooling zone rollers manufactured by «VAI FUCHS» and installed on the mould have been examined to determine such factors as the influence of the design of the mold foot rollers on the parameters of the billet. Calculations confirming the feasibility of the proposed solution have been made. The values of the bending moments and shear forces of the three-roller assembly are lower and fluctuate within 10%, which, if used, can reduce the likelihood of ingot bleeding and, consequently, can lead to an increase in the performance of the continuous casting machine.

Substantiation of the design and technological parameters of the spiral roller for the onion harvesting machine

The peculiarity of harvesting onion sets is that the composition of the impurities of the onion-soil heap coming from the digging working bodies to the separating working bodies is made up by soil lumps commensurate in size with the onion-seed bulbs, which are difficult to separate at slotted (bar elevators, screens) working bodies. This problem is most relevant in the selection of onion sets from rolls, because together with the bulbs, the separating working bodies receive the soil layer, loosened by the digging working bodies in the first phase of harvesting onion sets, which are the basis of fractional composition and is hardly separable on slotted working bodies. This circumstance is explained by the fact that after the soil is digged together with commercial products, a significant amount of soil lumps, which are difficult to separate on the separating working bodies and lead to damage of root crops and bulbs during their interaction, come to the separating working bodies. In addition, the release of soil lumps on the slit working bodies (rod conveyors and screens) occurs according to dimensional signs and this does not lead to a solution to the existing problem - separation of soil lumps commensurate in size with onion bulbs. Conse-quently, to ensure quality indicators of harvesting onion sets, namely, the completeness of the separation of bulbs from soil impurities, it is necessary to ensure a reduction or complete exclusion of the receipt of soil lumps on the separating working bodies in the second phase of harvesting, which intensifies the onion harvesting roller. The article presents the design of device for onion harvesting, which intensifies the maximum completeness of separation of onion heaps from soil impurities, including comparable soil lumps during the second phase of onion harvesting. The results of theoretical studies of the device for on-ion harvesting based on the design and technological parameters are given.

DETERMINATION OF THE DEPTH OF HARDENED LAYER AFTER CENTRIFUGAL ROLLING OF LOW-RIGID SHAFTS

The issues regarding improving the quality of low-rigid shafts are considered through studying the stressed state of their surface layer. The depth of hardening, value and distribution of the residual stresses in the surface layer have a direct impact on the geometrical stability of low-rigid shafts. The main goal of hardening consists in providing the uniformity of the stressed state in the bulk. A novel design of a centrifugal roller is proposed to ensure effective hardening of low-rigid shafts. A notion of a mutual impact zone is introduced. Theoretical dependences providing determination of the optimal depth of the hardened layer of low-rigid shafts are presented. The experimental results regarding determination of the hardening depth as a function of the rotational frequency of a centrifugal roller are presented. The experimental data show that the quality of treating low-rigid shafts with a centrifugal roller depends on the characteristics and thickness of the mutual impact zone, which is determined by the average grain size of the microstructure. The developed design of a centrifugal roller provides an unchanged value of the working force, stability of deformation and stresses along the workpiece length. The optimal depth of hardening of the surface layer of low-rigid shafts attained upon finishing-hardening by surface plastic deformation (SPD), which is proved both theoretically and experimentally, should not exceed the size of the mutual impact zone.

Design of Hard Compaction Rollers for Automated Fiber Placement on Complex Mandrel Geometries

Design of Hard Compaction Rollers for Automated Fiber Placement on Complex Mandrel Geometries

Studies of The Durability of Belt Conveyor Idlers with Working Loads Taken into Account

The results of laboratory and operational studies conducted in the Machinery Systems Division of Wroclaw University of Technology in recent years have became the basis for selecting proper belt conveyor roller designs optimized for specific strength and operational criteria. The usefulness of the results for assessing the energy intensity of idlers, estimating their durability and determining modernization policies has been confirmed. Methods of estimating the durability of carrying idlers on the basis of the identified output stream distributions are presented. Results of studies carried out using an analytical method and a laboratory method are reported. It has been shown that the operational durability of a roller is determined by its design, the roller set parameters (the spacing and the angle of bevel) and the operating conditions having a bearing on the irregularity of the transported output stream.

A New Engineering Technique in Roller Design to Prevent Thinning of Sheet in Roll Forming Process

These days sheet metal forming is a widely used in different industrial fields with large production volumes. Formability of metal sheets is limited by localized necking and plastic instability. In sheet metal forming processes like drawing and stamping the main challenge is thinning of the metal sheet in some regions. To reduce thinning of the sheet product, roll forming has been suggested instead of stamping process. Thinning strain can cause necking, tearing or wrinkling which are failure of the metal sheet. In this study a new engineering technique is proposed in order to prevent thinning of the steel galvanized hot coil commercial (SGHC) in roll forming process. An explicit finite element code, ABAQUS software, was used to simulate the roll forming process. The results show that the proposed technique has an important effect on thinning of the sheet and can reduce it significantly. Investigation on the second and third and fourth rollers show the effect of modified roller dimension as on reducing the thickness. These reductions in second, third and fourth rollers are from 4 percent to 0.5 percent, 2.8 to 1.4 percent and from 1.4 to 0.7 percent respectively. The reasons of the new techniques effect were also discussed.

Investigation of forming parameters on springback for ultra high strength steel considering Young’s modulus variation in cold roll forming

Ultra High-Strength steels (UHSS) is increasingly used in automotive industry to reduce weight and improve consumers’ safety. However, prediction of springback in cold roll forming is one of the crucial problems to be solved for ensuring dimensional tolerances. The variation of Young's modulus is a significant challenge to accurate springback prediction. In this work, two mechanically-measured tests, such as uniaxial and loading unloading loading cycle test, were performed to determine the Young’s modulus variation with the increase of plastic strain. One mathematical model that considers Young’s modulus variation was proposed and applied in 3D Finite Element Analyses (FEA) to simulate the cold roll forming process. Roll forming tests of hat-shaped section and the relational springback analyses were implemented to compare with FEA simulation results. The calculated accuracy of springback used nonlinear elastic modulus considerably improved by 18% to Swift’s material model. The springback prediction was significantly improved if the Young’s modulus variation was taken into the FEA simulations. The developed model is applied for comparing the effects of different forming parameters on the product springback, showing that springback increases with increasing flange width, sidewall height, roll gap and the distance, decreases with increasing the strip thickness and the web width. The findings are hoped to help roll forming designers predict springback tendency before the roller design is applied in practical production.

Modelling of a mecanum wheel taking into account the geometry of road rollers

During the process planning in a company one of the basic factors associated with the production costs is the operation time for particular technological jobs. The operation time consists of time units associated with the machining tasks of a workpiece as well as the time associated with loading and unloading and the transport operations of this workpiece between machining stands. Full automation of manufacturing in industry companies tends to a maximal reduction in machine downtimes, thereby the fixed costs simultaneously decreasing. The new construction of wheeled vehicles, using Mecanum wheels, reduces the transport time of materials and workpieces between machining stands. These vehicles have the ability to simultaneously move in two axes and thus more rapid positioning of the vehicle relative to the machining stand. The Mecanum wheel construction implies placing, around the wheel free rollers that are mounted at an angle 450, which allow the movement of the vehicle not only in its axis but also perpendicular thereto. The improper selection of the rollers can cause unwanted vertical movement of the vehicle, which may cause difficulty in positioning of the vehicle in relation to the machining stand and the need for stabilisation. Hence the proper design of the free rollers is essential in designing the whole Mecanum wheel construction. It allows avoiding the disadvantageous and unwanted vertical vibrations of a whole vehicle with these wheels. In the article the process of modelling the free rollers, in order to obtain the desired shape of unchanging, horizontal trajectory of the vehicle is presented. This shape depends on the desired diameter of the whole Mecanum wheel, together with the road rollers, and the width of the drive wheel. Another factor related with the curvature of the trajectory shape is the length of the road roller and its diameter decreases depending on the position with respect to its centre. The additional factor, limiting construction of the road rollers, is their bearings. Depending on the load, carried by the vehicle and the rotational speed of the drive wheel, the bearings themselves can greatly affect the diameter of the rollers and the whole Mecanum wheels. The solution of this problem is presented in the paper. It is illustrated with virtual models elaborated in advanced program of the CAE class.

Mathematical modeling of a controlled electromechanical actuator for special assembly and coupling equipment

The article presents theoretical and experimental bases for the creation of a driving gear with an actuating mechanism based on a planetary roller drive to improve the fidelity of the specified motion law and velocity performance of the support equipment actuators and engineering systems of missile and space-rocket complexes, as well as for integrated tests of heavy missiles. We present a mathematical model of a controlled electromechanical actuator for special assembly and coupling equipment. The results of the tests carried out lead to the conclusion that in order to create a high precision electromechanical drive, it is necessary to use transmission with a smaller gap between the mating elements, high accuracy and reliability of operation. A new design of a planetary roller drive and the advantages of using a stepper motor are described. Thus, mathematical modeling of an electromechanical actuator with a planetary roller drive with a mockup test on an assembly and coupling tilting device makes it possible to create an electromechanical actuator with improved technical and operational characteristics for a tilting device of the space head of a super heavy launch vehicle. This reduces the probability of emergency situations during conducting government and commercial space programs.

Research on roll-forming bending angle distribution function based on five boundary conditions

The bending angle is an important parameter in roll forming, in which the rationality of the bending angle distribution in each pass directly impacts roller design, the smoothness of the roll-forming process and product quality. In the past research, it is generally recognized that the projection track of the edge of the profile section in the horizontal plane follows a cubic curve, which can be used to determine the bending angle of each pass according to the boundary conditions. However, this method has some limitations and does not guarantee that the distribution of the bending angle is the most acceptable one. In this study, a hat-shaped steel channel is chosen as the research object and the different bending angle distribution methods are discussed. In addition, a bending angle distribution function based on five boundary conditions is proposed and the curve equation for the projection track of the edge of the profile section in the horizontal plane is constructed. At the same time, different bending angle distribution results are obtained by adding various boundary conditions, furthermore, the numerical simulations and comparative analyses are performed. Finally, combining the numerical simulation with the experiment, the optimal bending angle distribution results are obtained.

Justification of the working surface of the conical rollers of row crop seed drills

It is determined that the main factors that influence the rolling process are the design of the working body and the physical and mechanical properties of the soil. The process of soil compaction in interaction with the most common types of rollers of row crop seed drills is experimentally studied. It is established that the conical rollers meet the requirements of agrotechnics most fully. An improved design of the conical rollers of row crop seed drills is proposed

Cooling Roller Steady-state Heat Flux and Temperature Analysis in Amorphous Ribbon Preparing Process

Temperature of cooling roller is a key issue affecting the quality of the amorphous ribbon. To this end, heat flux distribution acting on cooling roller outer wall was calculated by fluid dynamics software Fluent. Cooling roller steady temperature field was analyzed with a finite element method with heat flux boundary conditions. The cooling roller inner and outer wall temperature distribution was obtained and the temperature of cooling roller as a function of cooling roller thickness and water passage height was discussed. Results show that cooling roller outer wall temperature decreases with roller thickness and the cooling water passage height decrease; cooling roller inner wall temperature decreases with roller thickness increases and the cooling water passage height decreases. Meantime, the appropriate roller thickness and passage height were selected to keep both inner and outer wall temperature of cooling roller within the certain range. The study result provides theoretical support for cooling roller design and optimization.