Welding, also known as melting and linked, is a manufacturing process and technology that combines metal or other thermoplastic materials such as plastic or other thermoplastic materials such as heating, high temperature or high pressure.The purpose of welding through the following three ways to achieve the purpose of the joint: the workpiece of heating desire combination to make the local melting to form a melting pond. After the melting tank is cooled and solidified, it can be combined if necessary.No melting workers themselves, the capillary of the capacity of the weld is connected to the workpiece (such as soft welding, hard welding); at the temperature equivalent to or lower than the melting point of the workpiece, it is supplemented by high pressure, stacked squeeze or vibration, etc.Combine.
Welding symbol
Welding symbols are a kind of engineering language that can simply and clearly explain the shape, geometric size and welding method of the weld in the drawing.my countrys welding symbols are stipulated by the national standard GB324.
1. Welding symbols can be expressed:
1. The location of the welded seam.
2. The shape of the welding section (shape of the slope) and the size of the slope.
3. The shape characteristics of the weld surface.
4. Indicate some characteristics or other requirements of the weld.
Second, weld formation and slope size
The method of welding seams on the drawing and the size of the slopes is generally expressed by technical drawing on the drawings.In order to simplify the representation method of welding seams on the graph, the welding seam symbols and the size of the slope size are now adopted.
Welding process
Different welding methods have different welding processes.The welding process is determined based on the material, license plate, chemical composition, weld structure type, and welding performance requirements of the welders.First of all, it is necessary to determine the welding method, such as hand arc welding, buried arc welding, tungsten pole arc welding, melting polar gas protection welding, etc. There are many types of welding methods, and you can only choose according to the specific situation.After determining the welding method, formulate the welding process parameters. The types of welding process parameters are different.Layer, number of roads, inspection methods, and so on.1. Principles The preheating preheating is conducive to reducing the maximum hardness of the medium -carbon steel thermal influence area and preventing cold cracks. This is the main process measure of carbon steel in welding.Preheating can also improve the plasticity of the joints and reduce the residual stress after welding.Generally, the preheating temperature of 35 and 45 steel is 150-250 ° C.When the carbon content is high or due to the large thickness and rigidity, when the crack tendency is large, the preheating temperature can be increased to 250-400 ° C.If the welded parts are too large and the overall preheating is difficult, it can be preheated. The area of ??the preheating heating is 150 to 200mm on the sides of the weld.
Welding method
There are more than 40 metal welding methods, which are mainly divided into three categories: melting welding, pressure welding and pyrine welding.The melting welding is the method of heating the workpiece interface to the melting state during the welding process, and the welding method is not completed without pressure.During the welding, the heat source will heat and melt quickly at the interface of the two workpieces to be welded to form a melting pond.Move forward with the heat source, forming continuous welds after cooling, and connecting the two industries into one.Pressive welding is a combination of atoms in the solid under pressure under pressure conditions, also known as solid -state welding.The commonly used voltage welding process is resistance to welding. When the current passs through the connection end of the two workpieces, the temperature rises due to the large resistance. When heating to plastic state, connecting into one in the action of axial pressure becomes one.The welding is a metal material that uses lower metal materials than the melting point of the workpiece as the material. The workpiece and ingredients are heated to the temperature that is higher than the melting point and below the melting point of the workpiece.The method of welding between the atoms is spreading each other.
Welding Technology
Welding technology is under high temperature or high -pressure conditions. The welding material (welding or wire) is used to connect two or more of the mother material (workpiece to welding) into an overall operation method.
1. Inception of welding safety welding accident
1. When welding and cutting operations, especially when the gas is cut, due to the use of compressed air or oxygen flow, the Mars, Mel is beads and iron dregs splashing around) When there are flammable, explosive items or gases in the operating environment, fire and explosion may occur.
2. When welding and cutting operations at high altitude, the flammable and explosive items within the range of Mars are not cleaned up. The operators throw the bean head in the process of work.
3. The acetylene generator was not placed in accordance with the requirements of the regulations during the work of gas welding and gas cutting, and the safety device of the welding (cut) torch, rubber pipe and aceta generator was not checked as required before work.

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