01-12

Welding method of aluminum alloy doors and windows

2023-01-12

Aluminum alloy doors and windows welding method: 1, gas welding: such as carbon dioxide and other gases, gas welding can be used for welding quality requirements are not high aluminum sheet and casting repair welding, 2. Electrode arc welding: It can be used for repair welding of aluminum alloy castings and is a relatively common welding method. 3, inert gas welding: the use of inert gas to isolate the air, the protection of the welding point is the most used method of aluminum and aluminum alloy welding method. 4. Tungsten AC argon arc welding or tungsten pulse argon arc welding. Aluminum alloy doors and windows can be tungsten helium arc welding, argon helium mixed tungsten gas shielded welding, metal gas shielded welding, pulse metal gas shielded welding, etc. 5. Resistance spot welding and seam welding. This kind of welding requires large current and high productivity. It is suitable for mass-produced parts. aluminum alloy doors and windows welding pay attention to matters: 1. Cleaning before welding: Aluminum alloy doors and windows need to strictly remove the oxide film and oil on the surface of the welding joint and welding wire before welding, and chemical cleaning and equipment cleaning can be used! 2. Pad plate: Aluminum alloy has low strength at high temperature and will become liquid. Liquid aluminum has good fluidity and is prone to collapse during welding. A backing plate is needed to hold the molten pool and nearby metal to ensure penetration and no collapse. 3. Preheating before welding: Aluminum alloy doors and windows generally need to be preheated before welding when the thickness is ~. According to different types of aluminum alloy preheating temperature, it is generally: ℃ ~ ℃. 4. When welding: the cable of the welding torch should not be too long. In order to prevent the welding from not being able to pass through, the arc should be closed with a small current to fill the pit. 5 after welding: aluminum alloy doors and windows after welding need to clean up the remaining flux and welding slag left in the weld and nearby, otherwise these substances may damage the passivation film on the aluminum surface, and sometimes corrosion of aluminum alloy doors and windows. Summary: There are many welding methods for aluminum alloy doors and windows. The most common one is inert gas welding. Aluminum alloy doors and windows need to be strictly operated according to the precautions before, during and after welding to ensure the stability of aluminum alloy doors and windows.

01-11

Preparation before welding for vacuum brazing

2023-01-11

1) Before vacuum brazing, check whether the cemented carbide has cracks, bending or uneven defects. The brazing surface must be smooth, if it is spherical or rectangular carbide brazing surface should also conform to a certain geometric shape, to ensure good contact between the alloy and the substrate, in order to ensure the quality of brazing. 2) sandblasting hard alloy. Without sandblasting equipment, hard alloy can be held by hand and the oxide layer and black brand letters on the brazing surface can be ground on the rotating green silicon carbide grinding wheel. If the oxide layer on the brazing surface of the cemented carbide is not removed, the brazing filler metal is not easy to wet the cemented carbide. Experience has proved that if there is an oxide layer or black brand letters on the brazing surface, sandblasting should be carried out, otherwise the brazing material is not easy to wet the hard alloy, and obvious black letters will still appear in the brazing seam, which will reduce the brazing area and cause deswelding. 3) when cleaning the hard alloy brazing surface, it is best not to use chemical mechanical grinding or electrolytic grinding and other methods, because they all rely on the binder (cobalt) that corrodes the hard alloy surface layer to speed up grinding or improve grinding efficiency, and after the cobalt on the hard alloy surface is corroded, the brazing filler metal is difficult to re-wet the hard alloy, which is easy to cause welding off. The surface of the material must be cleaned before vacuum brazing. The method is: apply W3.5 diamond grinding paste on the cast iron block, and polish the hard alloy brazing part until it is bright. Also on the 40Cr steel surface treatment: first in the W150 water sandpaper to remove the surface dirt, and then in the W40 sandpaper sanding. The solder shall also be sanded on W150 sandpaper to make the surface clean. Finally, 40Cr steel, YG8 hard alloy and brazing filler metal are cleaned in acetone to remove surface oil stains. After the treatment, the brazing filler metal is placed between hard alloy and 40Cr steel (hard alloy is located in the upper part), and then put into the fixture together. Under special circumstances, when the hard alloy brazing surface must be treated by the above method or electric spark wire cutting, the treated hard alloy can be sandblasted again or the surface layer can be ground with silicon carbide grinding wheel. The cemented carbide after sandblasting can be cleaned with gasoline and alcohol to remove oil stains. 4) Before vacuum brazing, carefully check whether the groove shape on the steel substrate is reasonable, especially for hard alloy workpieces with crack grades and large brazing surfaces, which should be strictly required. The knife slot is also sandblasted and cleaned to remove oil. When the amount of cleaning is large, the alkaline solution can be boiled for 10~15min. High-frequency or immersion copper brazing multi-blade tools and complex measuring tools, it is best to use saturated borax aqueous solution boiling 20~30min, take out and dry before welding. 5) before using the brazing filler metal with alcohol or gasoline wipe, and according to the brazing surface cutting shape. When brazing general carbide tools or molds, the thickness of the brazing filler metal is about 0.4~0.5mm, and the size is similar to the brazing surface. When heating with continuous nitrogen protection brazing furnace, the brazing material can be increased appropriately. When brazing hard alloy multi-blade tools, measuring tools and other workpieces, the area of the brazing sheet should be reduced as much as possible. Generally, the brazing sheet can be cut into about 1/2 of the brazing surface. When the brazing technology is skilled, the brazing sheet can be reduced to 1/3 or less of the brazing surface. Reducing the brazing filler metal can make the appearance of the workpiece after welding more convenient.

01-10

Vacuum Brazing Process of Cemented Carbide

2023-01-10

Vacuum Brazing Process of Cemented Carbide 1. Selection of Cemented Carbide Solder Cemented carbide and steel brazing filler metal according to the melting point and brazing temperature is divided into high temperature brazing filler metal, normal temperature brazing filler metal and low temperature brazing filler metal three categories. Brazing temperature above 1000 ℃ solder is called high temperature solder, such as copper and 106 solder, etc. The brazing temperature of medium temperature solder is between 850 and 1000 ℃, such as H62, H68 brass solder, etc. Low temperature solder refers to the brazing temperature between 650 and 850 ℃, such as B- Ag-1 and L-Ag-49 and other silver-containing solder. The main requirements for hard alloy brazing filler metals are as follows: 1) The brazing filler metal should have good wetting ability to brazed carbide and steel substrate to ensure that the brazing filler metal has good fluidity and permeability. 2) One of the characteristics of cemented carbide is that it has high red hardness, so it is necessary to ensure that the brazing weld has sufficient strength at room temperature and high temperature. 3) The melting point of the brazing filler metal should be as low as possible to reduce the brazing stress and prevent cracks, but the melting point of the brazing filler metal should be higher than the working temperature of the weld by 300 ℃ to ensure that the tool can work normally during high-speed cutting. 4) The solder should not contain elements with low evaporation point, so as not to affect the quality of the joint or harm to human health due to the evaporation of the elements in the solder during brazing heating. Cemented carbide brazing commonly used brazing material grades and uses a brief description of the following: 1) The brazing temperature of the copper solder is high and the weld strength is low, and it is mostly used for vacuum brazing. Pure copper brazing filler metal is a single-phase organization, relatively easy to control the brazing temperature, all kinds of cemented carbide has good wetting ability, good plasticity, the price is the cheapest. The shear stress of copper brazing weld is about 150MPa, which can be used below 400 ℃. 2) The brazing temperature of H68 brass is much lower than that of copper, but it is not used frequently because of the low weld strength. 3) The melting point and brazing temperature of H62 brass are relatively low, and the weld has a certain room temperature strength, which is a more commonly used cemented carbide brazing filler metal. It is generally used for brazing carbide tools used under medium and small load conditions. 4) the need for high temperature strength of the weld or welding surface is small, should use 105 brazing filler metal. 5)L-Ag-49 low temperature silver solder is widely used in foreign countries, because of its low melting point (690~710 ℃), good wettability to cemented carbide, convenient brazing and low stress. When necessary, copper sheets can be used as compensation gaskets, which can almost completely eliminate brazing stress and avoid brazing cracks. It can be used to braze some cracked carbide or some carbide tools with large brazing surfaces. As the workpiece brazed with L-Ag-49 silver solder with the use of temperature increases, the weld strength decreases rapidly, so the workpiece with L-Ag-49 solder working temperature should be limited to 200 ℃ or less. The flux used in conjunction with L-Ag-49 silver solder contains more fluoride and chloride, which requires higher cleaning work after welding, otherwise it will cause corrosion on the surface of the workpiece due to unclean cleaning. 6)B-Ag-1 brazing filler metal is a kind of ultra-low temperature silver brazing filler metal, the melting point is about 600~610 ℃, which can further reduce the residual stress of hard alloy joint, and can also be used as compensation gasket to braze some easily cracked workpieces. Due to the ultra-low melting point of B- Ag-1 silver solder and good wettability to tungsten carbide, it is also suitable for brazing some diamond tools such as diamond saw blades. However, B- Ag-1 silver solder has high price and low high temperature strength, it is only suitable for use at temperatures below 150°C. The cadmium content in the solder is 24%, and it is easy to evaporate when the brazing temperature is high, which is harmful to human health. In addition to the brazing temperature must be controlled during brazing, an exhaust device should be installed at the brazing operation. After brazing, the workpiece should also be cleaned to avoid corrosion of the workpiece.

01-09

Is the principle for determining the brazing temperature the same for different brazing materials?

2023-01-09

For different brazing materials, the temperature range required to be higher than the melting point of the brazing material itself is different, and sometimes even lower than the melting point of the brazing material itself. For the brazing filler metal with strong interaction with the base metal, a new alloy will be formed due to the great change of its composition during the filling process. At this time, the brazing temperature should be determined according to the melting point of the new alloy formed in the brazing seam. Brazing temperature is too high, easy to cause the solder and the base metal interaction is excessive, resulting in the base metal corrosion, resulting in brittle metal layer, so that the mechanical properties of the joint deterioration, at the same time will make the base metal brittle. If the brazing heating temperature is low, the brazing material flow distribution and infiltration are insufficient, so that the joint gap is not easy to be filled, thus forming a bad joint. In addition, for some brazing methods (such as furnace brazing, etc.), the requirements of the material heat treatment specification should also be taken into account when determining the brazing temperature, so that the brazing and heat treatment processes can be completed in the same heating and cooling cycle. This not only saves man-hours, but also avoids the possible adverse consequences of post-weld heat treatment.

01-08

Process setting of brazing temperature

2023-01-08

When brazing, is the higher the temperature the better? The brazing temperature is one of the most important parameters in the welding process. At the brazing temperature, in addition to the brazing filler metal melting, filling and interaction with the base metal to form a joint, some welding methods (such as furnace brazing, etc.) can also complete the post-brazing heat treatment process (such as solid solution treatment, etc.) to improve the performance of the brazed joint. Brazing temperature is too high, easy to cause the solder and the base metal interaction is excessive, resulting in the base metal corrosion, resulting in brittle metal layer, so that the mechanical properties of the joint deterioration, at the same time will make the base metal brittle. If the brazing heating temperature is low, the brazing material flow distribution and infiltration are insufficient, so that the joint gap is not easy to be filled, thus forming a bad joint. How should the brazing temperature be determined? In general, the brazing temperature should be suitably higher than the melting point of the pin, and is usually set to be 25 to 60 ° C. higher than the liquidus temperature of the brazing material. On the one hand, the higher temperature is used to improve the wetting and filling of the solder, and the needle and the base metal can fully interact with each other, thereby improving the strength of the joint; On the other hand, it avoids the high temperature may cause the evaporation of the low boiling point components in the solder and the melting corrosion caused by the excessive interaction between the base metal and the solder, the formation of brittle compounds and intercrystalline infiltration, so as to avoid the decline of the strength of the joint. In addition, for some brazing methods (such as furnace brazing, etc.), the requirements of the material heat treatment specification should also be taken into account when determining the brazing temperature, so that the brazing and heat treatment processes can be completed in the same heating and cooling cycle. This not only saves man-hours, but also avoids the possible adverse consequences of post-weld heat treatment.

01-07

Five Common Brazing Process Questions

2023-01-07

With the continuous development of industry, brazing is involved in various industries, and its role is also increasing. Although it is used more and more frequently, in the process of using it, it is still found that there are many common sense errors, including many operators are not very clear. Here, let's make a simple summary of the most common problem: 6. What is the main application of solder paste? Solder paste can be widely used in flame brazing, induction brazing and furnace brazing process. The addition of flux to the solder paste will increase the formulation of the solder paste. When using vacuum brazing or atmosphere protection brazing, the solder paste will not need to add flux. 7. What form of joint assembly should be used for brazing? A number of different joint forms can be employed in brazing, the most widespread of which are butt joints, lap joints, and butt-lap joints. According to the different needs of customers, customers can read the article "Joint Design Principles" to systematically understand and calculate the required lap length of the joint. 8. To what extent can the strength of the brazed joint reach? The strength of brazed joint is mainly determined by many different factors, including the type of base metal, the control of joint gap and the choice of brazing filler metal. With the different choice of base metal and brazing filler metal, the strength of the joint is also changed, the strength of the brazed joint is also closely related to the gap, and the strength of the joint will decrease with the increase of the gap. Typically, the strength of the resulting brazed joint is equal to or greater than the strength of the base metal, depending on the correct solder selection, appropriate joint clearance, and other brazing process operations. Can the temperature of vacuum brazing of stainless steel be lower than 927 ℃? The vacuum brazing temperature of stainless steel cannot be lower than 927 ℃, mainly because the formation of chromium oxide will hinder the flow and spreadability of the solder on the stainless steel base metal. The minimum brazing temperature for vacuum brazing of stainless steel is usually recommend to reach 954 ℃. If nickel plating is performed on the surface of the stainless steel plate, the brazing temperature may be lower than 927°C. 10. What kind of brazing filler metal should be used for 300 series stainless steel in service environment in contact with water? Brazing of stainless steel in water service should use nickel-containing brazing filler metal. Nickel-containing brazing filler metals can improve the corrosion resistance of stainless steel brazed joints.

01-06

Common brazing process problems

2023-01-06

With the continuous development of industry, brazing is involved in various industries, and its role is also increasing. Although it is used more and more frequently, in the process of using it, it is still found that there are many common sense errors, including many operators are not very clear. Here, let's make a simple summary of the most common problem: 1. What is the difference between brazing, soldering and welding? Brazing-According to the definition of the American Welding Association, the process of melting and filling the brazing seam by heating to above 450 ℃ (higher than the liquid phase point temperature of the brazing filler metal and lower than the solid phase point temperature of the base metal) to form a reliable connection of materials. Soldering-soldering has a similar definition to brazing, except that the brazing heating temperature is lower than 450°C (higher than the liquid phase point temperature of the brazing filler metal and lower than the solid phase point temperature of the base metal). Fusion welding-in the fusion welding process is the base metal and filler material are heated and melted, solidified after the formation of the connection. 2. What are the forms of solder? The form of the solder is mainly wire, tape, powder, paste, etc., which is mainly determined by the selected metal composition. Of course, many brazing materials can also be used for preform processing according to customer needs. 3. What is the form of flux? According to the type of flux mainly provide paste, slurry, liquid and powder flux. And these high-quality fluxes, such as the products of the world's number one brazing company Lukos, are all water-based. Such fluxes are more environmentally friendly and can reduce pollution to the furnace. I believe it is also the direction of flux development in the future. 4. How to remove the flux remaining after welding? The simplest way to remove the residual flux after welding is to quench the solder in hot water after solidification of the joint. For flux residues that are difficult to remove, 25% HCl solution is required for cleaning. Of course, we can also mix special cleaning agents according to our specific needs.

01-05

Process flow of induction brazing

2023-01-05

1, first of all, according to the material characteristics of the workpiece processing, dimensions, the actual welding conditions to design the appropriate sensor; 2, select the power of the power supply, for small workpieces, roughly estimate can do equipment selection. For the large volume of the workpiece and the short heating time, detailed power calculation is required to avoid insufficient welding power; 3. Calculate the specifications of the solder according to the external dimensions and welding requirements of the welding workpiece. Note: The melting point of the solder must be lower than the melting point of the base metal; After melting, the solder can wet and flow well on the surface of the base metal; Can be combined with the base metal to form a strong joint; The ingredients are stable, non-toxic and harmless. 4. Remove the oxide film and oil on the surface of the workpiece; 5. When positioning, supporting and fixing the workpiece to ensure mass brazing production, the relative position of the workpiece and the inductor will remain unchanged, and the brazing filler metal will be added in a ring shape to the part to be welded. 6. Setting of heating parameters: control the brazing temperature and heating speed by adjusting the heating current and heating time; When setting the heating parameters, first switch to the manual mode. In the "manual mode", observe the melting of the solder, and manually "click" to heat to achieve a good welding effect. At the same time, record the approximate heating time to make a good basis for the next adjustment of automatic parameters. Switching the "automatic mode" According to the heating current and the required time in the "manual mode", an automatic parameter can be roughly called out, and heating is performed under the parameter, the heating situation is observed, and the parameter is fine-tuned accordingly, and finally A suitable parameter is obtained. 7, brazing post-treatment: directly put the workpiece into the water, or use other chemical cleaning agent.

01-04

Introduction to Non-cremation Brazing

2023-01-04

Non-cremation brazing, understood from the surface meaning is a brazing method that does not produce flame during the entire welding process, so non-cremation brazing is a clean and safe welding method. Today we say no cremation brazing mainly refers to induction brazing. Induction brazing is one of the many brazing methods, it is not through the heat radiation to heat the metal, but the use of electromagnetic induction principle to make The genus produces its own heat. This heating method has high energy utilization rate and rapid heating, and only uses electric energy, has the characteristics of low energy consumption, low pollution and low harm, so it has been widely concerned. For many years, the application of induction brazing in aluminum welding is not ideal due to the restriction of equipment precision and control mode. But until the emergence of Beichen Yike's all-digital induction heating equipment, and the rich experience we have accumulated in aluminum alloy welding over the years. We have improved the accuracy of the equipment and changed the control mode of the traditional induction heating power supply. Our all-digital software control mode and high-precision heating power supply make the induction brazing of aluminum alloy become a reality.

01-03

The difficulty of aluminum metal connection

2023-01-03

The welding of aluminum metal has always been a pain point in the industry. Whether it is traditional flame welding or tunnel furnace welding, there are problems of poor welding effect and leakage welding. Especially in mass welding, the existing welding process is difficult to ensure product consistency and high pass rate. However, due to some physical characteristics of aluminum metal, aluminum metal plays an important role in industrial manufacturing. In the development of modern materials science, we have not found a particularly cost-effective material to replace aluminum metal. Therefore, the welding of aluminum metal is an unavoidable problem in actual production. About why aluminum metal is difficult to weld, there are mainly the following points: aluminum alloy is more difficult to braze than other alloys, the main reasons are: 1, aluminum alloy surface is easy to produce a layer of dense oxide film, the nature of the oxide film is very stable. Covering the surface of the workpiece will hinder the wetting of the solder on the surface of the workpiece, thus affecting the quality of brazing. The melting point of the oxide film on the surface of aluminum alloy is very high, and at the brazing temperature of 500 to 600 degrees Celsius, the thickness of the oxide film will increase to about 20 to 40 times at room temperature, which seriously hinders the wetting and bonding of the solder and the base metal. This is also the reason why it is difficult to reweld aluminum alloy after brazing; 2. When brazing aluminum alloy, because the melting point of the brazing filler metal is not much different from the melting point of the aluminum alloy, the brazing temperature must be strictly controlled, otherwise it is easy to cause the workpiece to burn out; It should be pointed out that the brazing performance of the material cannot be changed, but we can improve the quality of welding by changing the brazing process.