The processing of the elbow is easy to produce the following quality defects, especially in the bending of the elbow.
(1) thinning of wall thickness, wrinkling, such as the outside of the bending deformation zone will produce thin wall thickness. The maximum deformation of the parts in the maximum deformation, when the thin excessive lead to rupture of the pipe. From the point of view of deformation mechanics, the ring is a problem which is too large. If the inside of the bending deformation zone will produce wall thickness increase. If the degree of deformation is too large, the inner wall of the tube will be unstable and thick, severe wrinkling. Therefore, the instability is not only under the effect of tensile stress will appear, under the effect of stress, the same instability problem. Such defects occur in the wall thickness of the tube bending.
(2) section shape distortion in the elbow bending process, if you do not take the necessary measures (such as in the tube filler or placed mandrel support), elbow cross section after bending in the absence of internal support can easily become oval.
Therefore, it is very important to prevent the production of the above defects in order to select reasonable technological process and take necessary technological measures. Production practice shows that the elimination or reduction of quality defects, in order to meet the requirements of the use of pipe fittings, is the key process of processing.
Source: Yaang Pipe Industry Co., Limited (www.yaang.com)