Custom Sheet Metal Welding: Key Technologies to Improve Welding Quality and Efficiency
In the field of metal plate engineering, welding is one of the core technologies for connecting components, and its quality is directly related to the stability and safety of the overall structure. When dealing with metal plates with a thickness of up to 80mm, preheating, process control during welding, and post-heating treatment are crucial. This article will delve into the key stages of these construction technologies, aiming to provide readers with a comprehensive, scientific, and practical guide.
For thicker metal plates, the welding process involves rapid local heating and cooling, which can easily cause welding stress, deformation, and even cracks. The main purpose of preheating is to reduce the temperature difference between the weld zone and the base material, which minimizes welding stress and deformation. It also enhances the plasticity and toughness of the weld metal, preventing cold cracks.
Flame Heating: Uses an oxy-acetylene or oxy-propane flame gun for local or overall preheating, suitable for metal plate components of various shapes and sizes. The heating should be uniform to avoid localized overheating, which could deteriorate material properties.
Electric Heating: Uses equipment like resistance heating plates, electric heating belts, or far-infrared heaters to produce heat through electrical currents for preheating. This method provides uniform heating and is easy to control but has higher equipment costs.
Induction Heating: Uses the principle of electromagnetic induction to generate eddy currents within the metal plate, thereby heating it. This method is fast and efficient, especially suitable for preheating large and complex metal plate components.
The selection of preheat temperature should be based on the type of base material, thickness, welding method, and environmental conditions. Generally, the preheat temperature for low carbon steel and low alloy steel can be set between 100-300℃; for high alloy steel or low-temperature steel, the preheat temperature might be higher. During the preheating process, temperature measuring instruments (such as infrared thermometers) should be used to monitor the temperature in real-time to ensure uniform preheating and compliance with predetermined requirements.
Welding parameters include welding current, voltage, welding speed, and electrode diameter. The reasonable selection of these parameters is key to ensuring custom sheet metal welding quality. For metal plates with a thickness of up to 80mm, multi-layer multi-pass welding or submerged arc automatic welding are commonly used efficient welding methods. After selecting the welding method, the optimal welding parameters should be determined through experiments or calculations based on the characteristics of the base material, plate thickness, and weld position.
A reasonable welding sequence can effectively reduce welding stress and deformation. For large complex structures, symmetrical welding, segmented backstep welding, and other process measures are often used. Additionally, controlling the interpass temperature is crucial. It should be maintained above the preheat temperature and not exceed the allowable maximum interpass temperature to ensure the structure and performance of the weld metal.
Post-weld heat treatment involves heating and holding the weld and its vicinity after welding to facilitate hydrogen diffusion out of the weld metal, eliminate residual welding stress, and improve the structure and performance of the weld. This process is significant for preventing delayed cracks, increasing joint strength, and extending the service life of the structure.
Overall Heat Treatment: The entire welded structure is placed in a heating furnace and treated according to predetermined heating, holding, and cooling procedures. This method provides uniform heating and good results but is energy-intensive and suitable for large, important structures.
Local Heat Treatment: Uses flame heating, electric heating, or induction heating to treat only the weld and its vicinity. This method is flexible and convenient, suitable for medium and small-sized components or on-site construction.
By reasonably applying these welding technologies, especially the introduction of custom sheet metal welding, the welding quality and efficiency of metal plate components can be effectively improved. For industrial applications requiring high precision and high reliability, custom sheet metal welding offers more precise and flexible solutions that can meet the metal plate connection needs of different processes, promoting the successful implementation of projects.
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