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本文在多年试验和实践基础上,提出一种对大直径的内螺纹的高精度挤压加工方法,(在此之前其应用仅对铝、铜等有色金属和低炭结构钢并局限于16mm以下小直径)。总结出内螺纹的螺纹精度直接取决于丝锥的精度,而螺纹孔的位置精度却有赖于攻丝前螺纹底孔的位置精度。到本文发表时止,已成功地发展出一种高速精钻工艺来制备铬钼合金钢连杆的螺纹底孔,和一种尺寸达22—36mm的系列无槽丝锥的挤压攻丝技术以精加工内螺纹。其结果是一次挤压可获得一级螺纹精度和V7的表面光洁度,螺纹抗拉强度增加20—30％,抗剪强度增加5—10％,表面硬度增加40％和一个0.15mm的硬化深度,这对螺纹的抗疲劳性能有好处。目前,内螺纹挤压已经技术鉴定,并已在铁道部系统推广使用。
Based on many years of experiments and practices, this paper presents a high-precision extrusion of large-diameter internal thread method (prior to its application only to aluminum, copper and other non-ferrous metals and low carbon structural steel and is limited to 16mm below Small diameter). It concludes that the thread accuracy of the internal thread depends directly on the accuracy of the tap. The position accuracy of the threaded hole depends on the position accuracy of the bottom hole of the thread before tapping. By the time this article was published, a high-speed, precision-boring process has been successfully developed for the production of threaded bottom holes in chrome-molybdenum alloy steel connecting rods and a series of tap-tapping techniques with a range of 22-36 mm Finishing the internal thread. The result is a single-pass extrusion to obtain first-order thread accuracy and V7 surface finish with a 20-30% increase in thread tensile strength, 5-10% increase in shear strength, 40% increase in surface hardness, and a 0.15 mm depth of cure, This is good for the anti-fatigue properties of the thread. At present, the internal thread extrusion technology has been identified and has been promoting the use of the Ministry of Railways system.