Experimental Investigation of the Shear Cutting Behaviour of Sandwich Panels

Abstract

Continually increasing exhaust emission standards for automobiles and an increasing environmental awareness push design engineers to develop new constructive and material concepts. So-called sandwich panels, consisting of stiff facings and light-weight cores, offer the possibility to combine properties of different materials synergistically. When processing large quantities, as is the case in the automotive industry commonly used manufacturing processes for cutting sandwich panels, like sawing or milling, are not applicable. A common manufacturing process to cut metal sheets in high quantities is shear cutting. However, pre-trials of shear cutting of sandwich panels have shown that it is not possible to achieve flawless cutting surfaces with current process layouts. Characteristic types of failure like high bending of the facings, delamination effects, burr formation and an undefined cracking of the core material were ascertained. Thus, in this study, the influence of cutting parameters, such as the clearance and the punch diameter, on these types of failure is examined. Five different clearances between 0.025 mm and 0.4 mm with two punch diameters, 8 mm and 32 mm, were investigated. In order to compare the influence of different materials, three commercially available sandwich panels were studied. The chosen sandwich panels differ both in the face sheet thickness and the core material. Finally, the shear cutting force is measured to identify a possible correlation between the cutting force and the face bending. As a result, optimal clearances to minimize the face bending are derived. Additionally, the influence of the core stiffness on the cutting force is determined.

Experimental and analytical investigation of the force requirements in shear cutting of metal-polymer-metal composites

“…While the LDPE core has a density of 0.92 g/cm 3 , the PP core has a density of 0.50 g/cm 3 only. This difference leads to different cutting behaviours and force progression curves [10]. The skin sheets are always attached to the core adhesively.…”

“…As measuring amplifier, a HBM QuantumX MX840A is used. A detailed describtion is given by Stein et al [10].…”

“…For a sound cutting result, the use of a small cutting clearance is indispensable. Stein et al [10] studied the influence of the clearance, the punch diameter and the core material on typical failures such as bending of the facings, the cutting angle and the burr formation. They determined that a small clearance as well as a stiff core material are necessary for a sound cutting surface geometry.…”

Numerical investigation of blanking for metal polymer sandwich sheets

“…Even though several authors investigated the blanking of sandwich panels experimentally [1,2,7], the number of studies on the simulation of the blanking process of sandwich sheets is limited. However, Chen et al [3] have presented a numerical investigation of half-sandwichpanels with only one skin sheet.…”

“…As single or multiple blanking occur in the process chain of all sheet metal parts, a physical understanding of the blanking process has high technological relevance. In particular, the knowledge of the stress state is important because it provides information on the load of tools, but is also assumed to be closely connected to the attributes of the finished product, such as the cut surface quality [2].…”