Estimation of the perforation force for polymer composite conveyor belts taking into consideration the shape of the piercing punch

Abstract

Due to the improvement of the mechanical properties of polymer composite belts used in vacuum belt conveyors, its perforation process causes a lot of technical issues for manufacturers worldwide. The objective of this paper is to analyze the belt punching process with two cutting edges and present the influence of the piercing punch shape on the perforation force. Based on the analysis, the analytical stress model was derived and validated by using both empirical and FEM tests. The application of the proposed model was proved by presenting the methodology used to estimate the perforation force for the flat piercing punch based on the mechanical properties of the belt obtained from simple strength tests (uniaxial tension, compression, and shear), with an error between 4 and 15%. In this report, the analysis of the piercing punch profiles was made and eight different piercing punch profiles were tested. Presented results confirmed that the spherical bowl punch may be considered as a most effective tool for belt punching, because it reduced the perforation force by 60% and the precision of the created holes was the best among the tested punch profiles for all three groups of polymer composite belts. By combining the obtained results, in the form of shape factors β, with the perforation force approximation model, it is possible to calculate peak force value for the specified tool profile and belt type and use this data in the design process of the punching dies.

Determination of the effective geometrical features of the piercing punch for polymer composite belts

“…1), which consists of the punching die with replaceable tools. Its construction was described in details in [2]. The main advantage of the test stand is the zero backlash linear guide, which makes it possible to use a very small clearance between the punch and the die (down to 0.05 mm).…”

“…For the quality analysis, the most important factor taken into account is the presence or absence of the typical defects that occur in the perforated belts. Based on the previous research [2] as the common defects of belt perforation, we can distinguish: conicity or ovality of the holes, fiber pull-out, uneven edge or side surface, and deformation of the covers of the belt. In Fig.…”

“…Nevertheless, if we consider that the peak value of the perforation force is crucial information in the punch optimization, we can consider the presented model as useful enough. This approach was previously presented in [2,3] and the obtained results have proved that considering the composite as an equivalent homogenous material in FEM analyses may be used in this application and it was supported with multiple examples found in scientific literature [23][24][25][26][27][28][29][30][31]. However, using only FEM analyses may give some false results connected with the mesh or poorly chosen failure parameters, which is why authors used a combination of both methods of research in which the experimental tests results are used for model verification.…”

“…This indicates that the simplest mechanical method of belt perforation-punching with two cutting edges (a piercing punch which cooperates with a die)-may be considered as an optimal one, if the effective geometry of the piercing punch will be determined. Based on the previous research presented in [2], the concave piercing punches, especially the one with spherical bowl, may greatly reduce the perforation force. According to Talaśka and Wojtkowiak [3], polymer composite belts may be divided into three groups: elastic light belts reinforced with fabrics, rigid belts with increased strength with thick films as their cores, and durable flexible belts reinforced with cords.…”

Shaping the Parameters of Cylindrical Belt Surface in the Joint Area

“…Industrial grade belts, both used in drives and conveyors, are commonly utilized in machine building for transferring torque between the connected workstations or for transporting products on manufacturing lines. Both full cross-section and perforated conveyor belts are utilized in transportation; the latter are utilized in vacuum transportation of light objects (Wojtkowiak et al, 2018;Wojtkowiak and Talaśka, 2019). On the other hand, the most commonly used types of drive belts are flat, toothed and shaped belts.…”