A patent for Prof. Dr. Sadeq Hussein Bakhy, University of Technology / Department of Mechanical Engineering, and several academic staff members.
Design and Fabrication of Resistance Spot Welding Machine to Manufacture Honeycomb Core for Sandwich Panels
Composite materials are used in the aircraft and automotive industries and in various engineering applications because they have lightweight, high resistance and energy absorption. Sandwich panel with honeycomb core is one of the most important composite material classifications, it consists of relatively thin but stiff face sheets and a thick but soft honeycomb-type core, which has several types of shapes and materials.
The existence of adhesives material in the manufacture of these panels is essential. Due to the dynamic stresses and high vibrations in the real application, adhesives are considering one of the most important causes of the failure of these panels because they do not have all the mechanical properties to maintain the form of this structure.
The proposed idea attempts to overcome these industrial constraints by using spot resistance welding instead of adhesive material in the manufacture of sandwich panels with honeycomb core. Due to the unavailability of a machine with specifications that allow the manufacture of honeycomb core for sandwich panels, the machine is designed with a controller that allows control of spot welding conditions (welding time, squeezing force, and squeezing time after welding).
Shear stress test was performed on specimens jointed by three types of adhesive material and specimens joint by spot welding by the proposed machine, according to the American Welding Society (AWS). It was observed that shear stress in welded samples under optimal conditions is 60 times greater than shear stress with glued samples. Therefore, the proposed spot-welding machine can be used in the production of sandwich panels for the aircraft and automobile industry.