Models of Transverse Vibration in Conveyor Belt—Investigation and Analysis

The transverse vibration frequency of conveyor belts is an important parameter describing the dynamic characteristics of a belt conveyor. This parameter is most often identified from theoretical relationships, which are derived on the basis of an assumption that the belt is a stationary elastic string. Belt vibrations have a number of analogies to other tension member systems, such as, for example, power transmission belts. Some research findings suggest that in the case of a limited length of the belt section, a more accurate description of its vibration can be obtained with a beam model rather than with a string model. Experimental research has so far mostly revolved around measurements of stationary belts. This article presents the results of vibration measurements performed for a moving belt and obtained for various operating parameters of the conveyor, as well as for several configurations of the distance between idler supports. The analysis was conducted on a moving steel-cord belt. Belts of this type are commonly used in the majority of mines and industrial plants. The measurement results were compared with the model of a string and with the model of a beam in tension. Both of the theoretical models allowed for the belt speed, whose influence was demonstrated in both theoretical calculations and experimental tests to be negligible. On the other hand, the tensile force in the belt was observed to have a significant impact on the vibration frequency. Depending on the idler spacing, the measurement results are approximate to those of the beam model or of the string model. For spacing smaller than 1.6 m, the belt shows properties approximate to an elastic beam, while for spacing greater than 1.6 m, the belt behaviour can be better represented through a string model. A beam model is, therefore, more applicable in analyses of vibrations in the upper strand of the belt, while a string model is more useful in analyses of vibrations in the lower strand.

GROUPS OF INTEREST IN THE RUSSIAN SOCIAL POLICY: THE EXAMPLE OF ALL-RUSSIAN SOCIETIES OF DISABLED, BLIND, DEAF

There is a research gap in the study of interest groups in the social sphere, arguing the possibility of examination the activities of all-Russian public organizations of the disabled, blind, and deaf in interaction with the state authorities in the Russian system of social protection of disabled people. The context of reforming the social sphere in Russia is important because it is suggesting the opposite to conservative principles the transition to market relations and effective management of institutions of social protection. The researchers consider public organizations created in the USSR as of “the power transmission belts” of the state, however these actors may represent interest groups preserving the conservative practices in the social sphere. The aim of the article is to verify whether all-Russian public associations of people with disabilities are interest groups in Russian social policy. The investigation compares the actions of conservative nongovernmental organizations with the theoretical characteristics of interest groups. To argue that the selected actors promote certain interests in the social protection system, a review of the research literature of characteristics of interest groups was conducted. Then, the characteristics were traced in the statutory activities of the investigated organizations. The analysis of the legislation and statutory activities of All-Russian organizations of people with disabilities revealed the possibilities of the organizations to influence political decision-making in relation to persons with disabilities, as well as to contribute to the persistence of the conservative course of social policy, despite the introduced innovations in Russian legislation.

Butt Welding of Round Drive Belts

The on-going rapid development of industry encourages development of new production technologies and designing of machines that use inventive mechanical engineering solutions, a big demand for parts of such machines being a natural consequence. Polymeric power transmission belts are a good example of that. This paper proposes an improvement in the process of production of such belting. Their production includes cutting to length and splicing of elastic round belts to obtain endless belts of the specified length. This is the key phase of the whole production process. A number of splicing methods are available using different physical phenomena. One of them is butt welding technique. In this process heat is applied on the material through an additional heating element called the heat platen. The effect depends on several factors, including preparation of the work pieces. Due to its characteristics the process is often carried out by hand. The need for automated manufacturing was created by important factors associated with manufacturing on an industrial scale: cost, time and quality. The proposed butt welding machine, complete with a control system is an answer to this need. The practical benefits include improved repeatability of splices, time savings and less work load for the operator.

Modeling the Flexural Dynamic Behavior of Axially Moving Continua by Using the Finite Element Method

Mechanical systems including conveyor belts, band saw blades, and power transmission belts are influenced by the lateral motion of the moving structure. This phenomenon was studied in the literature both using the theory of the continuous linear and nonlinear systems and following the multibody technique. The subject is studied by using the finite element method (FEM) validated with reference to the analytical models described in the literature. The contributions of the Coriolis forces, the negative stiffness linked to the transport speed, and the bending stiffness due to the transverse moment of inertia are discussed. The dynamic behavior of a prototypical belt transmission layout with two fixed pulleys and an automatic tensioner is then analyzed. The results show the effect of the transport speed on the reduction of the flexural natural frequencies of the mode shapes strictly related to the lateral motion of the belt span and evidence the design strategy that needs to be followed for a correct operation of the whole system.