Formation of metal sheets connection by a cold moulding method

Krzysztof Tubielewicz, Krzysztof Turczyński

New technical solutions in connection of thin metal sheets were presented in the paper. The method of sheets connection by a cold moulding consists in a simultaneous formation of indentation from one side and protuberance from other side in two sheets and then in pressing of such connection using punch and die block what result in the permanent connection. Lack of additional connecting element such as rivet or weld is an advantage of such a method of connection. Such a connecting method can also be used in joining the sheets covered by protective coatings and in the case of proper geometry of such a joint the connection has a significant static and fatigue strength. Development of technology of formation of the shape connection by the method of cold moulding to modernize the manufacture of present joints made by the traditional welding technology, which due to the changes in a material structure, mainly in the result of thermal stresses, leads to a destruction of protective coatings and causes the contact corrosion, was the project objective. A comprehensive analysis was carried out as regards minimization of joints size, keeping the same physical-and-mechanical properties of metal sheets, especially their outside surfaces, with a possibility of elimination of technologies that are dangerous to health. The rule of formation of the joint, with determination of microhardness distribution in the joint area, resulting from changing the material structure, was given. Practical use of developed technology and strength tests of the product manufactured by that method were discussed. Also ergonomic analysis of the suggested method of sheets connection in comparison to the present welding technology was made.