مدل شبیه سازی جدید برای پوشش ابعاد تسمه نقاله

Cover bands are a rather seldom deployed conveying technology having nevertheless a lot of potential for industrial applications. Especially for the vertical transportation, for the handling of a large article range, or for the achievement of a highly dynamic goods behavior cover bands own distinct advantages compared to classical means of transportation. However, the adjustment of belt tensioning forces is a highly crucial element that has not yet been studied in depth. This paper introduces two models (geometric and physical) and a simulation based upon these for the determination of system inherent forces and for finding design parameters.

Cover bands are traditionally used to convey bulk goods in the form of packages, piece goods, sacks, or gravel-like material in order to cross mainly vertical distances of several meters, e.g., when unloading a freight hold of a ship or conveying cases inside a racking structure ([6], p. 24 et sqq.). Fig. 1 shows some examples of these applications and depicts their basic elements. The required conveying forces are actuated by adherence: The goods are covered by two driven flat belts or a driven flat belt and a (folding) plate. Pressing force is applied by the tension of the belts and additional pin rollers. A possible effect of this conveying method, which is sometimes made use of, is that the objects are being turned upside-down when they arrive at the output side of the conveyor, e.g., for the production of deep-drawn parts such as cans or cups described in [4]. As is implied by the above examples, different sizes of the cover band drive are possible depending on the case of application.

The presented model is used to simulatively analyze cover bands. The simulation is based on a geometric-physical model. In a first step, the geometry of the cover band system is animated in two dimensions, with the goods being reduced to a set of randomly sized and arranged circles. The results are used in a second step as input for a physical model of the belt system. A linear simplification of the belt physics is applied. By means of this model, the belt pretension can be predicted and several other parameters, like force transmitted to the goods, can be derived. The model even allows for the calculation of the special case of objects showing a compliance under force. The underlying mechanical model of the simulation appears rather simple and contains a comparably small amount of parameters. On the one hand, this means that it is not possible to capture and analyze all possible physical effects. Especially the linearization of the belt material is a simplification which may not be valid in any case. Non-linear material effects become significant at high belt velocity, for example. For detailed belt analyses of this kind, finite element models are currently being developed and improved, by means of which even non-linear contact and frictional forces can be investigated. On the other hand, machine designers need a way of modeling a machine which is as simple as admissible in order to be able to quickly check variations in the machine design. Currently available finite element models—especially for the described cover belt systems as a multi-component systems in which randomly arranged objects dynamically alter the geometry—are cumbersome and not easy to handle due to numerous parameters and degrees of freedom involved. In some cases, an accurate modeling may not even pay off as the belt materials available in practice vary in their quality and thus physical properties.