During the welding process, the workpiece and the solder melt form a molten area, and the molten pool cools and solidifies to form a connection between the materials. There are many energy sources for welding, including gas flame, arc, laser, electron beam, friction and ultrasonic.
Start the oil pump motor, clamp the workpiece with an elastic chuck, adjust the hydraulic system pressure, working pressure, clamping pressure, upsetting pressure, and check the lubrication of the spindle box. A special wrench is used for loading and unloading fixtures, and it is not allowed to use spring clips whose surface is deformed into a cone shape. The oil drum of the machine tool shall have good grounding protection and shall not be disassembled.
Since the metal will chemically react with oxygen and nitrogen in the atmosphere at high temperatures during the welding process, the resulting voids and compounds will affect the strength of the joint. Manual arc welding using consumable electrodes as electrodes developed in the 1950s and quickly became the most popular metal arc welding technology. In 1957, flux cored arc welding first appeared, and its self-shielding wire electrode can be used for automatic welding, greatly increasing the welding speed.
In the welding process, if the atmosphere is in direct contact with the high-temperature molten pool, the oxygen in the atmosphere will oxidize the metal and various alloy elements. Nitrogen and water vapor in the atmosphere enter the molten pool, and the weld forms defects such as pores, slag inclusions, and cracks during the subsequent cooling process, which affects the quality and performance of the weld. For example, gas shielded arc welding is to isolate the atmosphere with argon, carbon dioxide and other gases during the welding process to protect the arc and the molten pool rate. The common feature of various pressure welding methods is to apply pressure during the welding process without adding fillers. Most pressure welding methods, such as diffusion welding, high frequency welding, cold welding, etc., do not have a smelting process, so there is no problem such as welding, which is conducive to the burning of alloy elements and harmful elements invade the weld, thereby simplifying the welding process. Many materials that are difficult to weld with fusion welding can usually be welded to high-quality joints with the same strength as the substrate.
During the welding process, both sides of the weld are affected by welding heat, and the structure and properties change. The welding material and welding current are different during the welding process. Preheating before welding, heat preservation after welding and heat treatment after welding can improve the welding quality of weldments. Due to the constraints of the surrounding workpiece body, the welding area cannot expand and contract freely, and the welding stress and deformation occur after the weldment cools. Modern welding techniques have been able to weld seams without internal or external defects and mechanical properties equal to or even higher than those of welded joints. The mutual position of the welded body in the space is called a welded joint. The strength of the welded joint is affected by the quality of the welded seam. It is also related to the geometry, size, stress and working conditions of the welded seam.