01-02

Learning brazing knowledge brazing process steps

2023-01-02

Today I talk to you about the basic steps of the brazing process. The brazing process includes the following steps: 1) the surface treatment of the workpiece: including the removal of oil, the removal of excessive oxide skin, and sometimes the need for surface plating of various metals conducive to brazing; 2) Assembly and fixing: to ensure the mutual position of the workpiece parts is unchanged; 3) the best configuration of brazing filler metal and brazing filler position, so that the liquid brazing filler metal can obtain the most ideal direction in the vertical and horizontal complex brazing seam; 4) When the solder does not flow into the brazing seam on the surface of the workpiece, it is sometimes necessary to apply a flow retardant to regulate the flow direction of the solder; 5) Correct selection of brazing process parameters, including brazing temperature, heating rate, post-weld insulation time, cooling rate, etc; 6) Cleaning after brazing to remove flux residues that may cause corrosion or deposits that affect the shape of the brazing seam; 7) When necessary, brazing seam and the whole workpiece shall be plated after welding, such as plating other metal protective layer, oxidation or passivation treatment, painting, etc. The above procedures are different for different brazing base materials.

01-01

Why has the soldering process endured and will continue in the future?

2023-01-01

There are three compelling reasons: (1) Stress connection: At room temperature, pure solder is a plastic self-annealing alloy, which can absorb stress under the condition of work hardening phenomenon or fatigue damage due to stress cycling. This unique property makes it possible to join materials with different coefficients of expansion, rigidity and strength without imposing some of the typical technical requirements of mechanical assemblies. For example, the design of printed circuit boards violates all structural design principles related to stress concentration, material strength, load distribution and vibration resistance. Without the solder connection method and its stress connection ability, it is impossible to have the well-known printed circuit board today; if other stress yield welding methods, such as brazing or other welding methods, may cause damage to the laminate, The circuit shedding and the failure of the glass-metal intermetallic seal of the components on the board. (2) Reliability: Because soldering can be welded at a lower temperature (below 450°C), the plastic and the welded components are usually not deformed and degraded due to heat. (3) Economy: The soldering method is particularly economical because of the simple equipment used for soldering, the low cost of materials and the controllable soldering process. In the near future, as long as we also use wires, semiconductor devices and insulating materials, based on the principle of electrical and magnetic pulses to manufacture circuits, soldering is an essential technical means. In general, the durability of soldering depends on the ability of the welding process to absorb process stress during product processing and product service; the ability to control the quality of the welded parts without causing damage during the welding process; and the ability to facilitate welding at low cost. (The point of view of this article comes from "1100 Questions on the Application of Modern Electronic Joint Engineering")

12-31

Welding method and basic operation of oxygen welding

2022-12-31

Oxygen welding method and basic operation: 1. Inspection before operation: the fasteners of 1.1 acetylene generator (acetylene bottle), oxygen bottle, hose connector and valve shall be fastened firmly without looseness, damage and air leakage. Do not stick oil to oxygen accessories, hoses and tools. 1.2 oxygen cylinders and acetylene pipes shall not be used due to leakage, aging, cracking and other reasons. Pipes shall be kept clean and free of debris. 2. Operation steps: 2.1 acetylene cylinder gas welding (cutting) Operation steps: 2.1.1 Reliably connect acetylene pressure reducer with acetylene cylinder valve, oxygen pressure reducer with oxygen cylinder valve, oxygen hose with oxygen pressure reducer, acetylene hose with acetylene pressure reducer, oxygen and acetylene hose with welding (cutting) torch. 2.1.2 Open the acetylene cylinder valve and the oxygen cylinder valve respectively. 2.1.3 Butt welding (cutting) torch can only work after ignition. 2.1.4 After the work is completed, first close the welding (cutting) acetylene valve and oxygen valve in turn, then close the acetylene cylinder valve and oxygen cylinder valve, then remove the oxygen and acetylene hoses, check and clean the site, and extinguish the fire before leaving. 2.2 Gas welding (cutting) operation steps of medium pressure acetylene generator: 2.2.1 reliably connect and weld (cut) the oxygen pressure reducer and oxygen cylinder valve, oxygen hose and oxygen pressure reducer, acetylene generator, oxygen and acetylene hose. 2.2.2 Rinse the acetylene generator with clean water to remove mortar and residue. 2.2.3 Put the calcium carbide of suitable size into the calcium carbide basket, and the amount of calcium carbide added at one time should not be too much. 2.2.4 Put the calcium carbide basket into the acetylene generator, add an appropriate amount of water, and tighten the upper cover. 2.2.5 Open the oxygen cylinder valve. 2.2.6 Ignite the butt welding (cutting) torch to start work. 2.2.7 After the work is finished, close the acetylene valve and oxygen valve of the welding (cutting) torch in turn, then close the oxygen cylinder, open the drain valve of the acetylene generator, then open the cover, rinse it, check the site and leave after eliminating the kindling. 3. Operation precautions: It is forbidden to store inflammable and explosive materials at the 3.1 welding site, and it is equipped with fire fighting equipment, sufficient lighting and good ventilation. 3.2 acetylene generator (acetylene cylinder) and oxygen cylinder within 10m, no fireworks. The distance between the acetylene generator and the oxygen cylinder shall not be less than 7m. The protective overalls used by 3.3 welders shall not be tucked into the trousers, the trouser legs shall not be rolled, and the shoe mouth shall not be tied outside the trouser legs. 3.4 Each acetylene hose must have tempering facilities, and the use of floating barrel acetylene generators is prohibited. 3.5 check equipment, accessories and piping for leaks and test with soapy water. Open fire or smoking is not allowed around. Copper shall not be used for 3.6 acetylene generator parts and random tools to prevent explosion caused by copper acetylene contact with acetylene. Copper alloys with a copper content of less than 70% may be used. 3.7 calcium carbide shall have suitable lumpiness. The amount of calcium carbide added at one time should not be too much. Do not focus on the use of small pieces of calcium carbide, do not use the last fragrance, in order to prevent acetylene generator pressure rise caused by violent reaction and explosion. 3.8 When medium pressure acetylene generator is used (when the working pressure reaches 1.5Mpa, pressure gauge and safety valve shall be installed in addition to anti-backfire device), the pressure shall be kept at the rated value, the safety valve shall operate reliably, the water shall be kept clean frequently, and the mortar decomposed by calcium carbide shall be removed in time. The air chamber, air pressure extrusion chamber and flashback preventer of 3.9 stamping acetylene generator shall be installed with pressure relief film of corresponding area, and the flashback preventer shall be equipped with one-way valve device. 3.10 when oxygen is used indoors or outdoors, it must be properly placed to prevent dumping. When there is outdoor operation, the oxygen cylinder should be installed in the pergola to avoid strong sunlight. 3.11 oxygen cylinders should generally be placed upright. Individual cases need to lie down, the bottle strength is slightly higher. 3.12 oxygen cylinder and acetylene cylinder are prohibited from being stained with grease. Do not use greased gloves to handle oxygen and acetylene cylinders. The cap of the 3.13 oxygen cylinder must be unscrewed by hand or with a wrench. 3.14 loosen the oxygen bottle and acetylene bottle valve not too fast, in order to prevent pressure flow surge, resulting in the valve out of the accident. The nozzle of the 3.15 oxygen cylinder shall not be contaminated with grease. In winter, if the bottle mouth freezes, it is not allowed to bake with fire, and can only be heated with hot water or steam. 3.16 do not use up the oxygen in the oxygen cylinder, and finally leave at least 0.05Mpa of oxygen. 3.17 acetylene bottle can not be subjected to severe vibration and impact, so as to avoid the bottle of porous filling sink to form a cavity, affecting the storage of acetylene. 3.18 acetylene bottles should be placed upright when working to prevent copper from flowing out with acetylene to avoid danger. The surface temperature of 3.19 acetylene cylinder shall not exceed 30-400 ° C. Too high temperature will reduce the solubility of copper propylene to acetylene, resulting in a sharp rise in acetylene pressure in the bottle. The connection between the 3.20 pressure reducer and the bottle valve must be reliable. No air leakage is allowed to avoid explosion accident. It is 3.21 not to use up all the acetylene in the acetylene bottle. Finally, leave 0.1Mpa acetylene gas and close the cylinder valve. When opening the oxygen or acetylene valve 3.22, it is strictly forbidden to hit to prevent sparks. After the 3.23 work is completed, the oxygen valve and acetylene valve should be closed in time, and the welding torch is not allowed to be placed in the container or under the workbench. When the 3.24 acetylene pipeline is blocked, it is strictly prohibited to use oxygen compressed air to blow it off. When the 3.25 is tempered, close the oxygen valve first, and then close the acetylene valve; when the acetylene pipeline is on fire, the method of bending the pipeline can be used to extinguish the fire. 3.26 For pressure vessels, airtight containers, various oil drums, pipelines, and workpieces containing flammable liquids, toxic, harmful, flammable and explosive substances, they must be removed in advance to release the pressure of the container and pipeline, and eliminate the airtight state of the container (Open the opening and unscrew the lid) before it can work. When 3.27 welding and cutting closed hollow, there must be an air outlet. Welding in the container must be supervised outside and ventilation measures must be taken. Welding in painted or sprayed plastic containers is prohibited. When 3.28 high-altitude welding, in addition to complying with the relevant provisions of the "high-altitude operation operating procedures", safety measures should also be taken. There are people on the ground watching. Put down the flammable and explosive materials must be moved 10 meters away. After the 3.29 work is completed, the acetylene generator should be cleaned, and the work site should be checked and cleaned, and the fire can be extinguished before leaving.

12-30

Explain the secret of the hard welding process in detail.

2022-12-30

Brazing: a welding method in which the filling solder with a melting point lower than that of the welding part is heated to a temperature higher than that of the welding part, so that it has sufficient fluidity and is fully filled between two welding parts by capillary action (called wetting), and then connects several welding parts after solidification. Processing cost: mold cost (none), single-piece cost (low) Typical products: electronic products, metal or ceramic jewelry and kitchen utensils, etc. The yield is suitable: from small batch to large batch. Quality: High-strength welded joints, close to the strength of one-piece molding. Speed: Short production cycle (1 -10 minutes) Applicable Materials Brazing is suitable for welding most metals and ceramic materials. The most common metals include aluminum, copper, carbon steel, stainless steel, nickel, titanium, and metal matrix composites. Design Considerations 1. The applicable materials and welding methods for brazing are very wide, which can be divided into manual welding and automatic welding. Therefore, it can be manufactured in a single piece, or in small or large batches. Or single-piece or small-batch production generally uses hand-controlled heat welding guns and filling rods; mass production is to send solder and welding parts to the melting furnace for heating and welding through the conveyor belt. 2. The filled solder can make up the gap between the weldments, so brazing can also complete complex welding nodes. 3. The type of filler determines the welding temperature and strength. 4. The welding node area of brazing is large, which will affect the decoration of the product to a certain extent.

12-29

Welding process in welding production process

2022-12-29

(1) the content of the development of welding process 1) Reasonably select the welding method and determine the corresponding Welding materials. 2) Select reasonable welding parameters, such as electrode diameter, welding current, arc voltage, welding speed, welding sequence, number of welding layers, etc. during arc welding; Submerged arc welding shall also specify flux type; Gas shielded welding shall specify gas type, flow rate, wire extension length, etc. 3) Formulate other measures and specify parameters, such as requirements for preheating and slow cooling, requirements for post-weld heat treatment such as post-heat and intermediate heating, and requirements for tire fixtures. (2) The principle to be followed in formulating the welding process is to ensure the quality, that is, the welding joint must meet the requirements of technical conditions regardless of its external dimension or internal quality; Then, the production efficiency should be considered, that is, it should be convenient for welding, good accessibility and few turnover times. The welding parts can be welded at the most convenient position by using tire clamps and mechanized auxiliary devices, or mechanized or automatic welding can be realized, in short to have a higher economic efficiency. In order to optimize economical, high-quality and efficient welding process methods, in addition to the knowledge of welding methods introduced in professional books and materials such as arc welding, electroslag welding, resistance welding and brazing, it is also necessary to understand the production characteristics of various process methods. These characteristics refer to the applicable scope of various process methods, such as the type, thickness, welding position and weld length of basic metal. Requirements for material processing technology and assembly technology, such as groove preparation, pre-weld cleaning, post-weld heat treatment requirements; the requirements for auxiliary equipment and tools required for welding, the complexity of the auxiliary process; the quality of welded joints and their stability; economic indicators, such as labor productivity, equipment investment, etc. The production cost, the labor conditions of workers, etc.

12-28

Welding production assembly process

2022-12-28

The assembly process of welded structure production is the process of fixing the parts and blanks that make up the structure in the correct mutual position to form components, parts or structures. The finished product (structure, component, assembly) can be produced by welding. The poor assembly quality makes it impossible to obtain high-quality products, which first affects the quality of welding. The more highly mechanized and automated the welding process, the higher the requirements for assembly quality. The assembly process is still a heavy process, accounting for about 25% to 35% of the total processing workload of the structure. The fixed parts of the assembly commonly used positioning welding, assembly welding fixture to achieve. For fixing parts by tack welding, the tack weld is required to have certain strength and rigidity. For example, when the fixed parts are taken out of the assembly fixture or assembly position and transported to the welding station, welding and excessive deformation shall not be caused. The tack weld shall also be able to reduce welding deformation. The location and size of the tack weld shall be convenient for welding and shall not affect the quality and working capacity of the welded joint and structure. The weld section size of tack welding should not be too large, and it should be arranged at the position of basic weld as far as possible, so that it can be completely remelted during welding. Where tack welds must be placed without welds, they shall be carefully removed after structural welding has been completed. Some in the assembly welding fixture to complete the assembly welding sequence, you do not need to tack welding. (1) Assembly process method 1) According to the positioning method, it is divided into marking assembly method and tire fixture assembly method. For a single piece of small batch, simple structure of the product can be used to assemble, called the line assembly method. According to the design drawing in the parts of the mutual position line, and then use simple spiral, wedge and cam clamp to fix the parts, meet the requirements of the drawing to be fixed, such as crane beam assembly. Crane metal structure assembly, analysis frame assembly, etc. Another assembly method is suitable for the assembly of tire fixtures in batch and mass production, such as using a template or positioning device to find the right position, or assembling positioning welding on a special assembly welding fixture, or directly completing the welding. This requires less assembly workers than scribing assembly requires less skill level of workers, and has higher efficiency, and the labor intensity of workers is reduced. Therefore, even if a single piece is produced in a small batch, it can be assembled by a universal assembly jig. 2) According to the assembly and welding sequence, it is divided into: overall assembly and welding; Welding while assembling; Assemble and weld according to components; Finally, there are three types of assembly and welding. ① After the individual parts are assembled into a structure one by one, all the welding is completed. This is only applicable to products with a small batch and simple structure. ② The individual parts are assembled one by one, and then welded, re-assembled, and re-welded until the entire structure is completed. This assembly method is similar to ①, because the structure is more complex, it is difficult to complete the assembly at one time, this method is also suitable for a single piece of small batch production structure, such as large vertical oil tank, spherical container construction site. ③ Divide the structure into several components and parts, assemble and weld each component and part separately, and then assemble the qualified components and parts into the structure and weld the total assembly weld. This method is called sub-component assembly method. Commonly used in large quantities and batch production conditions, and for some complex structure of the product, even a single piece of small batch production nature, the use of sub-component assembly method also has great advantages. This method has high assembly welding quality and improves the working conditions of workers, because this method divides large and complex structures into light, small and simple structures (components, parts, etc.), which is convenient for assembly and welding, and can change some space position welds into flat welding welds, which can greatly increase the workload in the workshop and workshop, thereby reducing the workload in the field conditions, but also can easily control the welding stress and deformation, easy to use the assembly welding fixture. This sub-component assembly method, can improve labor productivity, shorten the production cycle, this is because the sub-components to facilitate the implementation of specialized production, workers need to master the production process is relatively simple, and can be more use of tire clamps, eliminate or reduce the waiting time between the various processes. The assembly by this method also simplifies the tire fixture, reduces the cost, and obtains higher technical and economic indicators. 3) According to the location of assembly work, it is divided into fixed location assembly method and flow assembly method. In actual production, the location of product assembly may be fixed, and workers of all types of work serve the products to be made, which are mostly heavy-duty structures with small output, such as beams of large hydraulic presses, turbine wheels, etc. Product assembly locations are more likely to flow along the station, with workers assembling and welding at fixed stations, such as the assembly and welding of gondola cars and tankers. (2) The formulation of the assembly process The contents of the assembly process include the assembly sequence of parts, components and components, the assembly sequence, the assembly method used in each step, and the specifications and models of tire fixtures, tools and equipment used in the assembly. In the development of the assembly process to consider and before and after the process of convergence, especially for the future of each process, welding process should bring favorable effects, such as easy to weld, easy to control stress and deformation. When developing the assembly process, pay attention to the selection of the positioning base and part tolerance. There are two ways to assemble and weld the structure with machined parts: first, the whole structure is finished, and then machined after annealing to eliminate stress, such as the welding base of the internal combustion engine of the diesel locomotive, the seat ring of the water turbine, the three beams of the 60000kN hydraulic press, etc. The other is to process the parts first, and then use a special device with sufficient rigidity for assembly and welding, such as the arm of the car crane, the frame of the excavator, etc.

12-27

Processing technology, assembly and welding technology of Welding materials

2022-12-27

The welding production process can be attributed to the welding production of materials (including basic metal materials and various auxiliary, filling materials, purchased blanks and parts, etc.) manufactured by equipment (material preparation equipment, assembly welding equipment, etc.) The process of making products. The main body of this process is the staff involved in production, including direct (basic production workers, auxiliary workers, engineering and technical personnel) and indirect (management personnel, service personnel) production personnel and inspection personnel. Of course, it is also necessary to start the machine's energy (I. e. power) and a certain amount of production space (I. e., the production workshop site) to carry out this production process. Therefore, welding production is composed of materials, equipment, sites, power and staff, which are part of welding production. Today, Xiao Bian will learn the material processing technology, assembly and welding technology of welding production together with everyone. 1. Material processing technology The material processing of welding production including steel pretreatment refers to the preparation and processing before assembly welding, which refers to a series of processing of the basic material of most welding structures-metal rolling, such as steel pretreatment including correction (straightening), cleaning, surface protection treatment, pre-blanking, etc; marking (marking), cutting (blanking), edge processing, forming (including bending) and groove finishing before welding. It accounts for about 25% to 60% of the total processing workload. If the material processing technology is poor, that is, the blank quality is poor, or the size error is large, the lack of interchangeability, or the groove processing is not appropriate, or the parts are irregular, deformation, etc., which make the assembly difficult, welding quality decline, sometimes can not be assembled, the need for trimming, thus greatly reducing the production efficiency. The use of mechanized and automated assembly welding technology, the requirements are more stringent, otherwise it will produce welding defects, so in order to obtain a stable welding production process, to ensure excellent product quality, to develop a reasonable material processing technology is very important. The following are some of the main material processing technology: (1) Pretreatment of steel 1) Correction: Due to transportation, storage, rolling, cooling and other links, the rolled steel has undesirable deformation such as wave, overall bending, local protrusion, edge bending, etc. Some rolled materials, such as steel with a thickness of 5mm or less, are supplied in rolls and must be flattened and corrected before being put into welding production, otherwise the accuracy of marking, material marking, cutting and other processes will be affected. 2) surface cleaning and surface protection treatment: removal of rust, oil and oxide on the surface of steel and parts is a process that is often ignored in welding production. The result of this may destroy the normal production, such as the continuous NC cutting blocked; the use of efficient welding methods difficult, or even can not be carried out, such as submerged arc welding, narrow gap welding, resistance spot welding and seam welding. (2) lofting, marking and marking this process is used to check the correctness of design drawings, determine the blank blanking size of parts, and make templates, etc. The design structure is drawn according to the scale of 1:1 (enlarged sample), which is called lofting. Lofting is a precise, meticulous and highly skilled work that has a great impact on future processing. Generally, lofting is carried out in the lofting room. In order to improve the lofting efficiency and quality, optical lofting and computer lofting are used in modern welding production. The parts or blanks to be processed are marked on metal materials for cutting or assembly. This process is called marking, while marking with a template is called marking. Marking and marking shall be carried out on a dedicated platform, which shall be within the scope of crane activities. When using profiling template blanking or using CNC cutting machine blanking, marking and marking may not be carried out in advance. (3) cutting welding production is called metal tailoring, so the cutting of various metal materials is an important step. The introduction has been introduced in the welding production of the major progress of the cutting process, mainly refers to the mechanization and automation of the thermal cutting process, coupled with the progress of the thermal cutting itself, the original that the thermal cutting production efficiency is low, the concept of poor quality of the cut has undergone a fundamental change. In some factories, all or most of the steel products with a thickness of more than 6mm are cut by mechanized and automated (numerical control) thermal cutting process, and the marking and marking steps are omitted, thus greatly improving the cutting quality. The edges of many products are the products of mechanized thermal cutting, with smooth cuts and correct part sizes, thus greatly improving the product quality. (4) bending and forming welding structure in the manufacture of bending and forming work occupies a large proportion, some structures of metal materials 80% ~ 90% need to be bent and forming processing. For example, long-distance pipeline structure, boilers, pressure vessels, spherical vessels and other chemical petroleum equipment belong to this type of structure.

12-26

Mirror welding operation method, the original details are full.

2022-12-26

Mirror welding operation method (1) Bottom welding A. Internal thread adding method Fix the welding torch in the welding arc starting area to start the arc, and the welding wire is delivered to the post-arc through the front groove gap. Observe the formation of the root with the naked eye, and observe the internal arc and appearance of the lens from time to time. Use the "two slow and one fast" method to operate the welding gun. Control the thickness of the bottom layer to 2.5~3.0mm .. 6 to 9 o'clock welding, and then 6 to 3 o'clock welding. The bottom layer soldering is completed in the sequence shown in FIG. 2. B. External filament method The arc consumed by the prefabricated welding wire, and then the welding gun is fixed on the nozzle weld at an angle of 60 degrees to start the arc. Note the arc in the lens and the wire feed in the molten pool. The wire feeding can be continuous or broken. The reflection of the lens is very easy to mislead the operation: for example, it is difficult to distinguish the welding wire in the real object from the welding wire reflected in the lens, which can easily lead to defects such as too high temperature of the molten pool, tungsten collision, pores, depression, etc. Therefore, the operation is to concentrate on the mirror, consciously hook the arc of the welding wire with the groove, and feed the wire evenly. The welding gun operates in a "two slow and one fast" mode, and the angle of the welding gun is adjusted according to the arc in the lens. Avoid the arc too long and the bottom layer too thick caused by the angle of the welding gun, and prevent the occurrence of defects such as incomplete welding. When welding to the position between 8 o'clock and 9 o'clock, you can see a part of the actual arc, and operate in combination with the physical and mirror conditions. Finish 1/4 of the nozzle weld before starting the mirror welding of the other 1/4 of the weld. The 6-point joint is one of the important operations of mirror welding, and defects are prone to appear in the opposite direction. During operation, in order to ensure the quality of the joint, the arc should be started at about 8~10mm of the front weld, and then the arc should be stably brought to the joint at 6 o'clock of the front weld. When the weld pool is formed at the joint, the welding wire should be added for normal mirror welding operation. Finally, complete the front (non-mirror welding) underwelding in the order shown in Figure 2, and complete the sealing. (2) Welding of overlay 1) Difficulty analysis Since the position of the weld in the mirror is opposite to the actual position, undercut, groove edge incomplete fusion, internal interlayer incomplete fusion, porosity or tungsten electrode damage during operation are prone to occur. 2) Operation requirements for cover welding Before welding, it is necessary to simulate the running track of the welding torch, adjust the angle of the lens and the arc curvature of the prefabricated welding wire. During welding operation, the welding muzzle shall be aligned with the groove at 6 o'clock for arc preheating. After preheating, with the brightness of the arc, the prefabricated arc welding wire is extended from the tube side to the position where the arc burns in the lens, and the wire is fed. The best wire feeding method is to slowly hook the arc-curved welding wire into the weld of the pipe and feed the wire into the molten pool continuously and evenly, and observe the growth process of the weld edge and the droplet transition and the arc length of the tungsten electrode in the lens. Press "two slow and one fast" and then move the lens to the other 1/4 of the weld on the back to adjust and fix the trajectory simulation. Improper operation of the 6-point interface can also cause welding defects, and it is a defective dense section. It is best to start the arc heating of the weld before 6 o'clock. When the joint melts into a puddle, the wire is added for normal mirror welding operations. Note the edge of the melting, according to the first section of the method of operation, until 3 o'clock arc extinguished. Then, the welded portions are welded in accordance with the regular method, thereby completing the welding of the covering layer of the entire pipe. 5. Preventive measures The mirror placement technique is very important. The farther the lens is from the object or the less parallel it is to the object, the greater the accuracy of the operation. ② The farther the lens and physical objects are from the operator, the more difficult the operation is; ③ Strictly control the gap between the pairs, the angle of the welding torch should be appropriate, the welding should be carried out in order, and the wire in the mirror should be clear.

12-25

Mirror welding process, as well as difficult analysis.

2022-12-25

1. Mirror welding principle Mirror welding is a welding operation technology based on the mirror principle, supplemented by mirror observation to control the welding operation process. It is mainly used for the welding of welds that cannot be directly observed due to the narrow welding position. Painting Generally, there are two requirements for the fixed position of the mirror. One is to facilitate the naked eye to observe the situation of the molten pool through the reflection of the mirror, and the other is not to affect the position of the argon arc welding gun and the walking and swing of the welding gun during the welding process. The relative position of the mirror and the weld is adjusted according to the distance between the tube rows. 2. Preparation before welding (1) Strictly control the butt gap of spot welding, generally 2.5~3.0mm is appropriate, and the spot welding seam position should be on the front of the pipe. (2) Placement of the lens: Place the lens horizontally in the initial welding area, simulate the welding trajectory with a welding gun, and adjust the distance and angle of the lens to make the lens in the best position for welding observation. (3) Check that the argon flow rate is generally 8~9 L/min, the tungsten electrode extension length is 3~4mm, and the arc curvature of the welding wire is prefabricated. 3. Difficulty Analysis of Mirror Welding (1) Mirror imaging is reflection imaging. During the welding operation, the welder sees that the radial direction of the nozzle is opposite to the actual direction. In the welding process, it is easy to feed the wire to the molten pool in the mirror, which affects the normal welding. Therefore, the swing of the welding arc and the action of the filling wire are difficult to be coherent, consistent and coordinated, which is easy to cause phenomena such as the arc is too long, the tungsten is clamped, the filling wire is not in place, and the end of the welding wire collides with the tungsten electrode. Painting (2) The lateral swing and movement of the welding arc are not flexible enough, which is easy to cause incomplete penetration, depression, incomplete fusion, undercut and poor root forming; if the welding speed is too slow, defects such as pores are easy to occur. (3) Through the mirror observation of the molten pool, the arc reflection is very strong, and it is difficult to see the tungsten rod. When feeding the wire, it is easy to cause the welding wire to collide with the tungsten rod, deform the tip of the tungsten rod, affect the stability of the arc, and easily produce defects such as tungsten clamping. (4) The weld seen through the mirror is a flat image. The three-dimensional sense of the weld in the mirror is not strong, and the mirror images of the arc and the molten pool are superimposed on each other. The arc is too strong and it is difficult to clearly distinguish the molten pool. Therefore, the control of weld thickness and straightness will directly affect the forming quality of the weld.

12-24

Five kinds of welding methods are explained in detail. How many have you seen?

2022-12-24

1. Gas welding: The use of oxygen acetylene or other gas flame heating base metal and filler metal, to achieve the purpose of welding. The flame temperature is about 3000°C. Suitable for thinner workpieces, small diameter pipes, non-ferrous cast iron and brazing. 2. Manual arc welding: Using the arc as a heat source to melt the welding rod and the base metal to form a weld by manual welding method, the arc temperature is about 6000-8000 ℃. Suitable for ferrous metal and some non-ferrous metal welding, a wide range of applications, especially for short welds, irregular welds. 3. Submerged arc welding: (Sub-automatic and semi-brake) The arc burns under the flux area, and granular flux is used as the covering layer of the metal molten pool to isolate the air so that it cannot enter the molten pool. The welding wire is continuously fed into the arc zone by the wire feeding mechanism, and the welding direction and moving speed of the arc are completed manually or mechanically. It is suitable for welding straight welds and regular welds of carbon steel, low alloy steel, stainless steel and copper of medium and heavy plate materials. 4. Gas welding: (Gas Shielded Welding) Arc welding in which a welding zone is protected by a shielding gas. The protective gas acts as a protective layer for the metal bath to isolate the air. The gases used are inert gases, reducing gases, oxidizing gases for carbon steel, alloy steel, copper, aluminum and other non-ferrous metals and their alloys welding. Oxidizing gases for carbon steel and alloy steel alloys 5. Ion arc welding: The use of gas in the arc ionization, and then through the thermal contraction effect, mechanical contraction effect, magnetic contraction effect produced by an ultra-high temperature heat source for welding, the temperature can reach about 20000 ℃.