1. What is the role of projection welding in modern industry?
Projection welding plays a major role in modern industry by providing a method for quickly joining thin sheets and plates with thicknesses below 3 mm. It is based on the resistive effect of electric current that generates localized melting and welded spots formation. The process involves locating joining areas through small grouped protrusions, which act as effective electrical contact points. The dimensions of the projection are determined according to the thickness and characteristics of the materials to be welded. The optimal projection height is considered to be 0.2 mm. Proper adjustment of projection dimensions and welding regime parameters is necessary to obtain a correct joint. Contaminating elements on the surfaces to be welded must be removed to ensure high-quality welds. An advantage of projection welding is a lower rate of electrode wear due to the use of flat electrode surfaces. The paper presents the effect of welding regime parameters on the quality of joints made by projection welding between two steel plates with 1.2 mm thickness, demonstrating the influence of electrode pressing forces, current, and welding time on the shear resistance of the welded joint.
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2. What devices were used to control welding parameters?
The welding parameters were controlled using dedicated devices such as hydraulic manometers for measuring welding force and a hydraulic dynamometer for measuring pressure force at the electrodes. Additionally, the electrical parameters were measured using the AMADA WELD TECH MM-315B apparatus, which can measure welding current, welding time/cycles, electrical conductivity level, and power percentage.
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3. What is the purpose of aluminization in projection welding?
Aluminization is a process of covering surfaces with thin layers of aluminum to improve corrosion behavior and wear during operation. However, it can cause problems during welding due to the formation of hard compounds at the welded interface. In projection welding, aluminized steel sheets are used to concentrate the current in discrete points, ensuring better welding performance and reducing the risk of compound formation. This process involves using a mold with pins to create projections that deform the sheets and create pairs of protrusions, which are essential for achieving strong and reliable welds.
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4. What parameters were determined during destructive testing?
During destructive testing, parameters such as rigidity, maximum force value (Fmax), failure coordinates, and energy were determined. Rigidity was determined by regression on the linear portion of the curve, with curve shape adjustment. Fmax was the maximum force value during the test. Failure was identified by the coordinates of the first weld failed point. Energy was calculated by the area under the curve from (0,0) to the first failure. These parameters are presented in Table 2 and Figure 6, with maximum Fmax values obtained for the first batch samples.
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