The plastic working of the press elbow tends to suffer […]
The plastic working of the press elbow tends to suffer from the following quality disadvantages, especially in the tortuous processing of the pipe.
(1) The wall thickness becomes thinner and wrinkles, such as a thinning of the outer side of the tortuous deformation zone. The portion where the thinning amount is the largest is at the maximum deformation, and when the thinning is excessive, the pipe is broken. From the point of view of deformation mechanics, it is a problem that the plastic hoop tensile stress is too large. An increase in wall thickness occurs on the inside of the tortuous deformation zone. If the degree of deformation is too large, the inner tube wall is unstable and thickened, and wrinkles are caused in severe cases. Therefore, the instability is not only presented under the tensile stress, but under the action of compressive stress, the same instability problem exists. Such quality defects occur when the pipe with a large wall thickness is tortuous.
(2) Distortion of cross-sectional shape During the tortuous process of the pipe, if the necessary method is not adopted (such as filling the material in the pipe or placing the mandrel support, etc.), the cross-section of the bent pipe will simply become elliptical when there is no internal support.
Therefore, it is very important to avoid the above shortcomings in order to select a reasonable process and adopt the necessary process. The production practice indicates that eliminating or minimizing the quality defects and satisfying the application requirements of the pipe fittings is the key to the plastic processing of the pipe.