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硬铝塑性较差,挤压时由于流动的金属与模具间剧烈的摩擦,引起附加拉应力,降低表面质量,甚至使零件表面产生裂纹和其它缺陷,致使冷挤失败。为了改善金属流动条件,必须在冷挤前进行表面处理,以便在冷挤毛坯表面形成冷挤时能够贮存润滑剂的复膜。目前国内冷挤硬铝前,对坯料进行氧化处理,挤出零件的表而光洁度可达?4～?6。为了适应生产需要,进一步提高硬铝冷挤零件的表而质量,西安仪表厂和西北工业大学两单位进行协作,对硬铝冷挤前的表面处理进行了新的试验研究。在生产条件下的试验研究表明,我们选择的对硬铝坯料在冷济前进行表而处理的磷化方案可以提高冷挤零件的表面光洁度1级至3级,一般可达?7以上。而单位挤压力与现行的表面氧化处理后冷济时差不多。因此,西安仪表厂决定,对于表面质量要求高的硬铝冷挤零件,在冷挤前,将坯料进行表面磷化处理,采用工业菜油润滑。
Hard aluminum plastic is poor, extrusion due to the intense friction between the metal flowing and the mold, causing additional tensile stress, reducing the surface quality, and even parts of the surface cracks and other defects, resulting in cold extrusion failure. In order to improve the metal flow conditions, it is necessary to perform surface treatment before cold extrusion in order to be able to store the lubricant film when the cold extrusion is performed on the blank surface. At present, before the domestic cold extrusion of hard aluminum, the billet is oxidized, the surface of the extruded parts is up to 4 ~ 6. In order to meet the production needs, to further improve the quality of the surface of hard aluminum cold-extruded parts, Xi’an Instrument Factory and Northwestern Polytechnical University two units to collaborate on the surface treatment of cold-forging of aluminum before and after a new pilot study. Experimental studies under production conditions have shown that our choice of phosphating solutions for hard-aluminum blanks before they are cold-worked can improve the surface finish of cold-extruded parts from Grade 1 to Grade 3, generally up to ?7. The unit squeeze pressure and the current surface oxidation after the cold economy almost. Therefore, Xi’an Instrument Factory decided that for the surface quality requirements of hard-cold aluminum extrusion parts, cold extrusion before the surface of the blank phosphate treatment, the use of industrial vegetable oil lubrication.