不锈钢弯管的皱波问题及其预防措施(上)

The Wrinkle Problem of Stainless Steel Elbow Pipe and Its Preventive Measures(Ⅰ)

为了预防不锈钢冷弯管时出现的皱波问题,首先从管件制造标准化角度考察和评估了冷弯方法的优点及其合理的应用范围,然后分析了不锈钢冷弯时发生皱波的"薄"壁条件、影响因素,并通过两个典型案例进行了分析。分析指出,皱波的实质是拱腹压缩塑性变形区的"压杆"失稳屈折现象。依据钢管的t_o/d_o和R_o/d_o决定的弯管"薄"壁度,合理设置芯棒型式及其他模具加工和安装精度确定的"间隙",以从力学上增强"压杆"抗压稳定度,这是预防皱波的必要保障。不锈钢管制造标准允许的t_o和d_o公差带往往大于"薄"壁弯管所必须的模具间隙,有时会在小批量多品种规格不锈钢弯管时产生皱波,但只要把握"薄"壁度,重视芯棒结构,模具间隙及弯管参数的合理调整,不锈钢冷弯管时的皱波问题是可以解决的。

In order to prevent wrinkling wave problem during stainless steel pipe cold bending, first of all, from the perspective of pipe fittings manufacturing standardization, it inspected and evaluated the advantages of cold bending method and its reasonable application scope, then analyzed the ＂thin＂ wall condition and influence factors when stainless steel c＇old bending through two typical cases. The analysis indicated that the essence of the wrinkling wave is pressure rod unstability and buckling phenomenon in intrados compressive plastic deformation area. According to the steel pipe ＂thin＂ wall degree decided by tod,, and R,]do, set up reasonably mandrel type, anti the clearance determined by other mold processing and installation presicion, to strengthen the stability against crushing of compression bar from mechanics, this is a necessary safeguard against wrinkling wave. The tolerance zone of to and do specified in stainless steel pipe manufacturing standard is often than the die clearance of ＂thin＂ wall thickness bends, sometimes the wrinkling wave appear in small batch multivarietal specifications stainless steel elbow pipe. However, as long as grasp the ＂thin＂ wall thickness degree, pay attention to the core rod structure, reasonably adjust die clearance and bending pipe parameters, the wrinkling wave problem of stainless steel cold bend can be solved.