Identification of dynamic contact parameters between contact roller and filament package

During the high-speed winding of polyester filament, a contact roller must be applied to press on the filament package’s surface to ensure the filament is placed stably and precisely on the package surface. Thus, a twin-rotor system with contact coupling characteristics between the contact roller and the filament package is formed. Identifying the contact parameters between the contact roller and the package are prerequisite to precisely analyze the dynamic behavior of the winding system, as well as to determine the technical parameters. In this paper, an approach was proposed to identify the equivalent contact stiffness and contact damping coefficients by means of coordination through experiment and simulation. First, based on the forced non-resonance method of a single-degree-of-freedom system, the testing scheme was drawn up in consideration of the winding process parameters. Then, an experimental device for the twin-rotor system was developed, and the dynamic contact parameters just in the working frequency band corresponding to low linear speed of winding were obtained by the experiment, due to the requirement of the forced non-resonance theory and economic limitations of the experimental device. Third, the basic parameters including equivalent radial Young’s modulus and damping ratio of the package were obtained through experimental test. Furthermore, the contact parameters in the working frequency band corresponding to high linear speed of winding were obtained through simulation. Finally, the curve fitting of contact parameters was finished; in addition, the comparative results between the simulation and the experiment are in good agreement. The dynamic contact parameters present nonlinear frequency variation characteristics.

Experimental Studies on the Influence of Electrochemical Dimensional Processing on the Surface Fatigue of Rolls in Rolling Machines

The state of surface layer in large part determines the performance characteristics of products, especially those operating at high contact loads, and in particular of rolls in rolling machines. As a rule, grinding is the final processing of rolls, but high specific work and high local heating in the cutting area lead to the appearance of a large variety of defects in the surface layer of the machined part. Subsequent electrochemical dimensional processing can significantly reduce their number. This article presents the results of comparative tests for surface fatigue of samples made of alloy steel 9Cr2MoV. The sequence of samples preparation for experimental studies is considered, they underwent a cycle of heat treatment according to a single standard mode, which made it possible to obtain a martensitic structure in the presence of inclusions of small carbides. Then the samples were ground to the height of irregularities Ra = 0.3-0.2 microns. Some of the ground samples were subjected to electrochemical dimensional processing at rational modes, when 0.2 mm thick metal layer was removed per side in the time equal to 0.5 min. The result was practically flaw-free surface with the microroughness height Ra = 0.25-0.18 microns. The sample tests for surface fatigue were carried out on a two-contact roller machine under rolling conditions with relative slip between the sample surface and pressure rollers at the peripheral speed of sample rotation 1.3 times lower than the circumferential speed of pressure roller rotation. The analysis on the contact stress diagram of the samples showed that higher resistance to fatigue fractures is observed in the samples after electrochemical dimensional processing. The number of cycles at which the limit of material contact endurance occurs for these samples is almost twice as large as for the samples after grinding.

A dynamic modeling approach for a high-speed winding system with twin-rotor coupling

This paper continues the previous study and presents a dynamic modeling approach for a high-speed winding system. To meet the requirements of high-speed winding, a twin-rotor coupling structure is adopted in the winding system. It is a complex spindle system, due to its high speed, heavy load, frequency-dependent coupling parameters, and time-varying rotational speed. In this paper, an approach to establishing a finite element model of the winding system is proposed to predict its dynamic behavior characteristics during the winding process. First, the spindle and contact roller models of the discrete single component are developed based on Timoshenko beam theory. Bending, transverse shear effects, and gyroscopic moment are considered in the models. The contact stiffness between the contact roller and the packages to be wound on the spindle is simplified by a nonlinear spring. The contact stiffness is identified by dynamics analysis in ANSYS® 17.0. Next, a fully dynamic model of the winding system, which consists of the spindle subsystem, the contact roller, and the flexible coupling elements, is established. Third, the Newmark method is used to develop the program to solve the dynamic equations in MATLAB® 2013b. Finally, the effects of the supporting system and contact state on the winding system's dynamic response are investigated. The results indicate the model of the winding system presented in this paper is suitable for predicting dynamic performance during the winding process.

SLP Turned Roller Derby Girl Takes Vegas

Nelson is one of the newest recruits in a league that welcomes all ages—from college graduates to grandmothers—and enthralls crowds with some full-contact Roller Derby. Cheering her on rink side will be her coworkers from Nevada Early Intervention Services, where she works by day as a speech-language pathologist in early intervention.

Finite Element Analysis of Multi-Roller Contact Roller-Gear Cam Reducer

This paper presents the multi-roller contact roller-gear cam reducer. It’s a special kind of the indexing roller-gear cam that changes the stopping stage of the indexing cam to zero and chooses the equal-velocity law. And with multi-roller contact the carrying capacity is greatly improved. In this paper, we created the 3D solid model of the main components of the reducer: the cam, the turntable and the rollers. After that, we used the FEA software ANSYS Workbench to calculate the static structural behavior and the results showed us the weak or dangerous part of the mechanism so that we can optimize the structural. However the static structural behavior does not always shows the working condition. Thus we calculated the flexible dynamic behavior of the reducer and it showed us vividly that which part is weak and we could see the real deformation and stress distribution of the structural while working. Then we can pay more attention to these parts.

Influence of Different Viscosity Lubricant to Finite Line Contacts on Elastohydrodynamic Lubrication (EHL) under Oscillating

To make further researches into the elastohydrodynamic lubrication properties of a finite line contact roller, oscillating experiments were carried out on made overload experimental rig for oil film measurement using optical interference technique. Film thickness and shape were measured in two kinds of viscosity polyisobutylene. This study indicates that both lubricant viscosity and roller entrainment velocity play an important role on EHL of finite line contacts. On motion, the more increase in viscosity or speed, the thicker the oil film thickness, simultaneity edge effect is distinctly intensified and film thickness increases less on roller end, difference of the film thickness is increased between roller end and the central. Above two parameters are significant for logarithmic profile roller in crowning design.

Spherical Head Surface Roughness Analysis and Experimental Research Based on the Abrasive Belt Grinding

Surface roughness is one of the most important parameters in grinding, which directly affects the quality of the processed surface and has quite a lot of effect on the shape and position accuracy, installation accuracy of the workpiece. In the grinding process, the surface roughness is formatted from the abrasive which effects on the surface of spherical head, and is the result of mutual interference between abrasive and spherical head. Many factors affect the surface roughness, such as the shape and size of contact roller, abrasive morphology, grinding method, the stiffness of machine tool and workpiece, abrasive wear and vibration in the machining process. All of these have an impact grinding surface roughness. In this paper, analyzed the belt speed, workpiece speed, abrasive size, workpiece diameter, sand-planting density on the surface roughness of spherical head in experimental. And the effect trend of factors on surface roughness of workpiece was analyzed. Some valuable information was provided for selecting suitable parameter in spherical head grinding.