Description Of Corrugated Pipes-shishangqiyi

Business Various types of corrugated pipe are known such as that described in DE 44 32 584 C1, which stems from the same applicant and in which the outer contours are designed as flattened or segmentally enlarged circles. In this embodiment the corrugations extend over all radial angular sectors in the longitudinal direction of the pipe. This results in the disadvantages explained below. Other embodiments of corrugated pipes result from EP 0 671 582 A1; DE 43 21 575 C1 and GB 1 209 569. These known embodiments of corrugated pipes all contain outer contours which assure a wave line in all radial angular sectors on the pipe jacket surface. Traditionally, air-conduction parts and liquid lines, e.g. coolant lines, are preferably manufactured out of rubber pipes and rubber hoses reinforced with textiles. Pipes and hoses of thermoplastic plastics offer considerable savings of expense and weight and have, in addition, an improved recycling potential. In this material substitution a bending flexibility .parable to that of rubber pipes is required from the thermoplastic pipes. The greater material stiffness of the relevant thermoplastics can be .pensated for by a corrugated structure of the pipe jacket surface. This geometry, known as corrugated pipe , is known in various embodiments. However, the bending flexibility achieved therewith makes the tensile stiffness worse, i.e., a greater expansion in longitudinal direction of the pipe upon tension must be accepted. Corrugated pipe geometries resulting in an increase of the tensile stiffness are known from the above-named publications. However, all these embodiments have the problem, explained in detail below, of the coupling of tensile stiffness and bending stiffness. Especially in the case of air-conduction parts and coolant lines in the automobile sector a high bending flexibility is required in addition to a high resistance to inner pressure in order to be able to create a tolerance .pensation in connections between movable structural parts and in order to facilitate assembly. When a corrugated pipe is selected, a tensile flexibility and .pression flexibility of the pipe is achieved by the surface corrugated in the longitudinal direction of the pipe which is far greater than that of a pipe with a smooth surface. A tensile deformation or .pressive deformation occurring in a straight line in the longitudinal direction of the pipe is taken up in the wall of the corrugated pipe by uniformly distributed bending deformations in the individual profile corrugations. In a bending deformation (curvature) of an entire corrugated pipe the mean casing surface of the pipe wall, which can be imagined as hose-shaped, is stretched on the side with the greater radius of curvature (outside) and is .pressed on the side with the smaller radius of curvature (inside), according to its distance from and its position relative to the curved neutral plane (plane without tensile or .pressive tension), in which the curved pipe axis runs. The stretching and .pressing is made possible analogously to the deformations in a tensile loading/.pressive loading by bending deformation (pulling apart or .pressing) of the corrugations. The plane in which the bending takes place is designated thereby as the bending plane. It therefore stands perpendicularly on the neutral plane and is not bent itself. Thus, since the same deformation mechanisms apply to a bending deformation and a tensile or .pressive deformation of a corrugated pipe in the corrugated profile, tensile stiffness/.pressive stiffness and bending stiffness are mechanically coupled for traditional corrugated pipes. This means that a conventional bending-soft corrugated pipe is also automatically tension-soft and pressure-soft. The loading of a pipe, whether smooth or corrugated, by inner pressure acts via the force of pressure on the contour of the inner pipe cross section like a tensile force applied from the outside. This means for traditional, bending-soft corrugated pipes with low tensile stiffness that as a result of the mechanical coupling of the stiffness the inner pressure loading results in a strong change in length of the pipe. This results in particular in problems for the use of corrugated pipelines with fluctuating pressure load like those which typically occur with air-conduction parts and coolant lines in the automobile sector but also in water lines of washing machines. The changes in length occurring as a result of the variations in pressure often collide with restrictions of the possible mounting space. The alternating bending stress occurring in the profile corrugations constitutes an additional strain on the material and thus reduces the attainable service life. About the Author: 相关的主题文章: