No. one, master a certain knowledge of welding theory
Welding theory comes from practical operation, and the summarized theory guides operation. Only skill operation and theory are closely combined to be a good "electric welder".
The theoretical knowledge of welding is very rich and extensive. Many welders have too little knowledge of welding in their initial work. Most of the welders only know the fur from the process of passing on the craftsmanship of some old masters, and only master a relatively simple operation technology. I do not know how to solve the problem of welding.
For example, when the stainless steel material is welded by the carbon steel electrode welding method, the weld formation will be very poor. This is because the thermal conductivity of the stainless steel material is poorer than that of the carbon steel material, and the molten pool formed by the arc is not easy to solidify.
With the development of science and technology and the development of materials, processes and methods, it is very necessary for welders to learn and master more theoretical knowledge.
No. two, learn to master the knowledge of welding materials
During the welding process, many metal materials will be contacted, and each material has its own characteristics. For example, the mechanical properties of metal materials include strength, plasticity, hardness, toughness, etc.; the physical properties of metal include density, melting point, thermal expansion, thermal conductivity, etc. Conductivity and magnetism, etc. These are closely related to the welding process.
For example, when austenitic stainless steel is welded, due to its physical properties such as large thermal expansion coefficient, large deformation, and poor thermal conductivity, it is difficult to control the appearance of the weld.
Therefore, when welding stainless steel, it is necessary to use small line energy, small current and short arc fast welding, speed up the cooling rate, make it stay in the sensitization temperature zone for a short time, strictly control the interlayer temperature, prevent intergranular corrosion, and reduce welding stress and deformation. .
Avoiding welding defects can also be analyzed from macro to micro combined with theoretical knowledge. For example, the welding pores on the construction site are theoretically divided into three types: hydrogen pores, nitrogen pores and CO pores. Through the macro characteristics of the three types of pores, the welding seam pores on the site can be analyzed. Identify and characterize, and analyze the site and welding conditions in combination with the theoretical cause of the qualitative porosity, find the cause and overcome measures, so as to avoid the generation of porosity.
In this way, many on-site welding phenomena can be answered through the research and analysis of theoretical knowledge. At the same time, the development of welding materials is emerging one after another, and the welder needs to study hard to become a "senior welder".
No. three, Learn to master welding "regulations"
Welding "regulations" are welding standard specifications, welder assessment rules, etc., which are the basis for the implementation of welding processes. Just like people must abide by laws and regulations in society, the welding process method of each material has been passed through several generations. After repeated research, experiments, and exploration, and after repeated verification, only products welded by this process can meet the requirements for use.
The welding procedure standard is a set of technical regulations in the welding process. Including welding method, preparation before welding, welding materials, welding equipment, welding sequence, welding operation, process parameters and post-weld heat treatment, etc. Different welding methods have different welding processes.
The welding process is determined according to the material, grade, chemical composition, structure type of the weldment, and welding performance requirements of the workpiece to be welded. In addition to the work of electric welders, it is also necessary to strengthen the study and mastery of relevant welding specifications and standards.
At the same time, many relevant welding specifications and standards have been issued by the international, national, industry and local governments. As an electric welder, you should always consult and inquire.
No.four, Welding environmental factors
It is the influence of environmental factors, environmental protection, labor protection awareness and the environment on the welding process. If you want to pay attention to the influence of rainy and wet weather on welding process and welding defects.
There is also the pollution of the welding environment and the impact of safety on people. The third is the harm caused by smoke, splashing, etc., and the impact of bad habits on the human body
No. Five, Exercise excellent operating skills
Many welders only know how to complete the work quickly and do not seek good operating skills, so that they feel tired after work and slow to improve their skills. How can I have a strong skill level?
First of all, in addition to mastering certain theoretical knowledge of welding, it is also necessary to understand the relevant knowledge of metal materials, welding pool characteristics, etc., pay attention to observe the shape of the molten pool during welding, and select the correct welding method and welding angle in time to complete a good welding. Welds
Of course, a good welder must fully understand the role of each part of the body, skillfully choose the appropriate welding posture during welding, and make good use of the role of each part of the body.
For example, the wrist is used to control the swing of the electrode to ensure the width of the welding seam, and the elbow is used to control the feeding speed of the electrode. Coordinate all parts of the body, the welding posture is comfortable, and the physical exertion will naturally be less.
No. Six To fully understand the role of each part of the body in the welding operation
During the welding operation, the welder's eyes, elbows, waist, wrists and other parts have corresponding functions, and should be used reasonably in welding.
For example, the eyes mainly play the role of observation during the welding operation. It is not easy to observe the changes of the molten pool from far and near, which is easy to cause visual errors, resulting in confusion of the molten pool, unsightly welded seams, and prone to defects.
Likewise, the elbows play the role of feeding in the welding operation, and the body or waist cannot be used in place of the feeding action. The wrist plays the role of the swing of the electrode. The width, swing frequency and pattern of the welding seam are completed by the wrist. The swing of the electrode cannot be performed by the elbow swing.
Therefore, welders should fully understand the role of various parts of the body. At the construction site, it is often seen that some welders use their bodies to feed the welding rod, and the welder's entire body must be attached to it. cause some damages.
Many welders suffer from lumbar and cervical spine diseases at a young age because they have not developed good welding positions and postures.
No.7 Welder's position and welding posture
As the saying goes, "Standing has a standing position, and sitting has a sitting position." Of course, the welder must have the correct standing position and welding posture when operating. The correct position and welding posture not only help the welder to complete the welding task with half the effort, but also can effectively avoid the welder's scald and protect the joints, lumbar and cervical vertebrae from damage.
The correct station generally requires the welder to choose a reasonable position according to the spatial position of the weld. When standing, it is necessary to consider the role of various parts of the body to effectively play, such as the distance between the glasses and the welding seam, will it affect the swing of the wrist, etc.
Welding posture is also very important. The correct welding posture means that when the welder is welding, all parts of the welder can fully play their roles. The physical exertion is small, it is not easy to burn, and the vision is good. The welder should be easier to operate.
This requires welders to abandon the mentality of "make do" from subjective and objective factors when welding on site, and take it seriously, analyze carefully, and try repeatedly. Over time, the experience of correct welding posture will become richer and richer objectively. It is also necessary to actively eliminate factors that may cause incorrect welding posture.
No. Eight, Understand the principle of molten pool
A weld with beautiful appearance and excellent quality is achieved by the welder controlling the welding pool according to the process card and reasonable skills. Welders are required to fully understand the molten pool temperature field and the principle of arc transition.
Generally, the temperature of the weld pool is basically the highest in the center of the weld pool, the molten iron has good fluidity, and the temperature on both sides and the back side gradually decreases, and the temperature field of the weld pool changes. Moved by 1-2-3-4-N
Since the arc frequently passes through the center of the weld pool, the heat in the middle of the weld pool is the highest, so it feels that the molten iron in the middle is thin. , resulting in defects such as excessive weld height and undercut on both sides.
According to this principle, when welding by hand, the welder must avoid the uniform movement of the arc in the weld. Generally, it is required to pause on both sides of the weld and make a rapid transition in the middle to balance the heat of the molten pool, thereby controlling the quality of the weld and beautiful appearance.
No. Nine, Welding method
1. The arc temperature of argon arc welding is generally between the plasma arc and the manual arc welding arc. The arc temperature is 9000-10000K, the plasma arc is 16000-32000K, the manual arc is 5000-6000K, and the melting electrode argon arc welding arc temperature is 10000 -14000K, oxyacetylene flame is 3100-3200K mainly because welding dust causes respiratory tract infection and lung infection; welding arc light causes eye myopia; noise causes hearing loss.
2. Electric welding is that the workpiece and the electrode are connected to different poles (positive or negative) of the power source. The instantaneous contact between the electrode and the workpiece causes air ionization to generate an arc. The arc has a very high temperature, about 5000-6000K, which melts the surface of the workpiece to form a molten pool. The metal is melted and coated on the workpiece surface to form a metallurgical bond.
3. "Oxyacetylene flame" refers to the flame of acetylene (commonly known as calcium carbide gas, which is produced by the reaction of calcium carbide and water) in oxygen. The reaction text expression is: acetylene + oxygen carbon dioxide + water.
In this reaction, a lot of heat is released, so that the temperature of the oxyacetylene flame can reach more than 3000 ℃, and the steel will soon melt when it comes into contact with the oxyacetylene flame. Taking advantage of this property, oxyacetylene flames are commonly used in production to weld or cut metals, usually referred to as gas welding and gas cutting.
Gas welding is to use the high temperature of oxyacetylene flame to weld two metals together. The key is to prevent the metal at high temperature from being oxidized by oxygen in the air. For this reason, the amount of oxygen must be controlled to make the acetylene burn insufficiently.
In this way, the flame contains carbon monoxide and hydrogen produced by incomplete combustion of acetylene and has reducing properties.
This kind of flame prevents the metal parts to be welded and the welding rod from being oxidized to change the composition when they are melted, and the welding seam will not be stained by oxides...
4. Water welding should be a welding technology under special conditions.
5. The temperature of the oxyhydrogen flame can be as high as 2500~3000°C, and even quartz with a high melting point (melting point at 1715°C) can be melted under the oxyhydrogen flame. Therefore, oxyhydrogen flame can be used to process quartz products.
The application of C2H2 flame and HO flame are different. O of HO flame has strong oxidizing property. In some cases, in order to prevent the metal from being oxidized during welding, HO flame is not used.
On the contrary, the -1 valence C in C2H2 has reducibility. C2H2 flame can not only weld metal, but also use C2H2 as shielding gas to prevent O in the air from oxidizing the welded metal electrodes: commonly used E43 and E50 series welding machines : The working principle of an ordinary welding machine is similar to that of a transformer, which is a step-down transformer.
At both ends of the tooth and the coil, the workpiece and the electrode are welded, the arc is ignited, and the gap of the workpiece and the electrode are fused in the high temperature of the arc. The welding transformer has its own characteristics, that is, it has the characteristics of a sharp drop in voltage.
After the electrode is ignited, the voltage drops; when the electrode is short-circuited by adhesion, the voltage also drops sharply. The reason for this phenomenon is the characteristics of the iron core of the welding transformer.
The adjustment of the working voltage of the machine, in addition to the one-time 220/380 voltage conversion, the secondary coil also has a tap to change the voltage, and it is also adjusted by the iron core. The lower the welding voltage.
