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  • 控制工业风扇叶片不变形的方法
  • 本站编辑:杭州雅田机电有限公司发布日期:2019-11-14 18:25 浏览次数:

目前市面上的工业风扇叶片都是以铝合金为主,这是因为铝合金材料的密度低且强度高,热电导率高,耐腐蚀的能力强,拥有较好的物理特性及力学方面性能。

      但是因为焊接方法和焊接工艺参数选取不当,会导致叶片焊接以后因力过于集中化而产生严重的机械变形,或者因焊缝气孔、夹渣和未焊透等等不足,致使焊缝金属裂纹或者材质疏松,从而严重的影响产品质量与性能。

      

      铝为银白色轻金属,有良好的可塑性,比较高的导电性、导热性,还具有抗氧化及抗腐蚀性能。铝极易氧化产出三氧化二铝薄膜,在焊缝中生出夹杂物,而破坏金属的连续性及其均匀性能,降低它的机械性能及耐腐蚀的性能。

      这是在焊接铝合金是很难避免的事,所以我们需要了解铝合金焊接时应该注意的地方。

      (1)易被氧化。空气中,铝易和氧化合,产生致密的三氧化二铝薄膜(厚度约0.1-0.2mm),熔点很高(约2050°C),大大地超过铝及铝合金的熔点(约600°C左右)。

      (2)容易产生气孔。铝及铝合金焊在接时生出气孔主要因素是氢,由于液态铝可溶解大量氢,但固态的铝基本不会溶解氢,所以当熔池温度快速冷却与凝固的时候,氢来不及逸出,易在焊缝里面形成气孔。氢气孔当前难完全免除,氢的来源有很多,

      (3)焊缝时候变形及形成裂纹的倾向较大。铝线膨胀系数及结晶收缩率都约比钢要大出两倍,易生成比较大的焊接变形内应力,刚性较大的结构将会加速热裂纹的生成。

      (4)合金元素的蒸发的烧损。铝合金中含有低沸点的元素(如镁、锌、锰等),在高温电弧作用下,极易蒸发烧损,从而改变焊缝金属的化学成分,使焊缝性能下降。

      (5)温强度和塑性低。高温时铝的强度和塑性很低,破坏了焊缝金属的成形,有时还容易造成焊缝金属塌落和焊穿现象。

      当然这只是焊接时应该注意的问题,这些了解后,我们需要明白工业风扇叶片焊接工艺方法。

      (1)焊前的准备

      运用化学和机械的方法,严格的清理焊缝坡口两侧的表面氧化性膜。

      (2)确定装配间隙和定位焊间距

      施焊的过程中,铝板受热膨胀,使焊缝坡口间隙减小,焊前装配间隙若留得太小,焊接过程中便会引起两板坡口的重叠,增加焊后板面不平度及变形量装。配间隙若过大,施焊困难,并有烧穿的可能性。一定的定位焊间距可保证所需要的定位焊间隙,选择合适的装配间隙和定位焊间距,为减少变形的有效措施。

      (3)选择焊接的设备

      当前市场上焊接产品种类较多,通常最好用交流钨极氩弧焊(即TIG焊)。它为在氩气保护作用下,利用钨电极及工件问产生的电弧热熔化母材及填充焊丝的一种焊接方法。

      (4)选择焊丝通常选用301纯铝焊丝及311铝硅焊丝。

      (5)选取焊接方法参数通常以左焊法进行,焊炬和工件会成60°角。焊接厚度15mm时,用右焊法进行,焊炬与工件会成90°角。焊接的壁厚在3mm以上的时候,开V形坡口,夹角是60°~70°,间隙不可大于1mm,用多层焊的方法去完成。壁厚在1.5mm以下的时候,不开坡口,也不留间隙,也不会加填充丝。焊固定管子对接接头的时候,若管径为200mm,壁厚为6mm的时候,宜采用直径为3~4mm的钨极,用220~240A的焊接电流,直径为4mm的填充焊丝,用1~2层焊完。


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At present, the industrial fan blades on the market are mainly made of aluminum alloy, because of its low density and high strength, high thermal conductivity, strong corrosion resistance, and good physical and mechanical properties. However, improper selection of welding method and welding process parameters will lead to serious mechanical deformation of Blade due to over-concentration of welding force, or due to insufficient weld porosity, Slag Inclusion and incomplete penetration, etc. The quality and performance of the products are seriously affected by the weld metal crack or material porosity. Aluminum is a silver-white light metal with good plasticity, high conductivity, thermal conductivity, oxidation resistance and corrosion resistance. Aluminum is highly oxidised to produce aluminium oxide films, which produce inclusions in welds, which damage the metal's continuity and uniformity, reducing its mechanical properties and corrosion resistance. This is in the welding of aluminum alloy is very difficult to avoid, so we need to understand the aluminum alloy welding should pay attention to the place (1) easy to be oxidized. In the air, aluminum easily oxidizes, resulting in a dense aluminium oxide film (thickness about 0.1-0.2 mm) with a very high melting point (about 2050 °c) , which greatly exceeds the melting point of aluminum and its alloys (about 600 °c) (2) prone to blowhole. Hydrogen is the main factor for the formation of pores in aluminum and aluminum alloys during welding. Because liquid aluminum can dissolve a large amount of hydrogen, but solid aluminum can hardly dissolve hydrogen, so when the bath temperature is rapidly cooled and solidified, hydrogen can not escape POROSITY is easily formed in the weld. At present, it is difficult to completely eliminate the hydrogen hole, the hydrogen source has many, (3) when the weld deformation and the forming crack tendency is big. Aluminum Linear Expansion Coefficient and crystallization shrinkage are about twice larger than steel, easy to generate greater welding deformation stress, rigid structure will accelerate the formation of hot cracks (4) burning of the alloy elements by evaporation. Aluminum alloys contain low boiling point elements (such as magnesium, zinc, manganese, etc.) . Under the action of high temperature arc, it is easy to evaporate and lose, thus changing the chemical composition of the Weld metal and reducing the weld performance (5) low temperature strength and plasticity. The strength and plasticity of aluminum is very low at high temperature, which destroys the formation of weld metal and sometimes causes the collapse and wear of weld metal. Of course, this is only welding should pay attention to the problem, these understanding, we need to understand the industrial fan blade welding process (1) the preparation before welding, the use of chemical and mechanical methods, Strictly Clean The weld groove on both sides of the surface oxide film (2) to determine the assembly gap and the positioning welding distance. During the welding process, the aluminum plate is expanded by heat, which reduces the gap between the welding seams and the groove. If the pre-welding assembly gap is too small, the overlap of the groove between the two plates will occur during the welding process Increase the flatness and deformation of the welded plate. If the clearance is too large, it is difficult to weld, and there is the possibility of burning through. A certain distance between the two welds can ensure the required distance between the two welds, and the suitable distance between the two welds can be selected as an effective measure to reduce deformation (3) choose welding equipment, there are many kinds of welding products in the market, usually it is best to use AC TIG (TIG welding) . The utility model relates to a welding method for welding a base metal and a filling welding wire by using an electric arc generated by a tungsten electrode and a workpiece under the protection of Argon Gas (4)301 pure aluminum wire and 311 aluminum-silicon wire are usually used for selecting welding wire (5) welding method parameters are usually selected by left welding method, welding torch and workpiece will be 60 angle. When the thickness of welding is 15mm, the right welding method is used, and the welding torch and the workpiece will form a 90 angle. When the thickness of the welding wall is more than 3mm, open the V-groove, the angle is 60 ~ 70, the gap can not be more than 1mm, with multi-layer welding method to complete. When the wall thickness is less than 1.5 mm, there is no groove, no gap and no filling wire. When welding the butt joint of fixed pipe, if the pipe diameter is 200mm, the wall thickness is 6mm, should use the tungsten electrode with the diameter of 3 ~ 4mm, the welding current of 220 ~ 240A, the filler wire with the diameter of 4mm, and use 1 ~ 2 layers to weld.

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