What Are The Winding Processes For Finned Tubes?

There are mainly several types of winding processes: (1) Wrapping L-shaped smooth fins. The metal thin strip is pressed into an L-shape on the winding machine (the short side length is equal to the fin spacing, and the long side is equal to the fin height), and then the short side is tightly wrapped and pressed on the surface of the pipe through a roller mechanism. This process is widely used both domestically and internationally. The material of the pipes is not limited, and carbon steel pipes, stainless steel pipes, copper pipes, and aluminum pipes can be used. However, the fins can only be made of metals with good ductility and high tensile strength, such as copper and aluminum. (2) After cleaning the metal base tube with embedded smooth fins, the outer surface is extruded into a spiral groove at the front of the inlay machine tool, with a depth of o. l~0 5mm. According to the depth and shallowness of the groove, it is called "heavy inlay" or "light inlay". The pitch of the slot is the pitch of the fin, and the slot is approximately 0.1mm wider than the root of the fin. The forming part in the middle of the inlay machine is similar to the winding process mentioned above, where the metal strip is spirally wound onto the pipe to form fins. The root of its fins is embedded into the spiral groove on the surface of the pipe, and then squeezed by a roller die at the tail of the machine tool, so that the fins are firmly embedded in the pipe wall. It can manufacture finned tubes with high fins, small spacing, and high finning coefficient. But the equipment process is relatively complex. In addition, there is also a winding process in France, which basically belongs to the inlay process. Its characteristic is that the spiral groove is not squeezed out on the pipe wall, but spirally wound with a layer of flat steel strip outside the pipe. The wide surface of the steel strip is closely attached to the pipe wall, and its pitch is slightly wider than the width of the steel strip, forming a gap slightly larger than the thickness of the fins. After the steel strip is wound, it is welded together with the pipe, forming a spiral groove on the surface of the pipe, and the thickness of the steel strip is equal to the depth of the groove. Then insert the fin strip along the formed spiral groove. This process seems more complicated and has low production efficiency, so it is not used much. (3) In the above two processes, when the fin strip is wound horizontally along the tube, the inner edge (root of the fin) is compressed and compressed, while the outer edge (end of the fin) is stretched and stretched. Therefore, materials with good ductility and tensile strength must be used. In order to expand the material of fins, such as steel strips, the wrinkling and winding process has emerged. It first compresses the metal strip on one side of the inner edge into corrugated folds before winding, shortening the inner edge, and then winding it. After winding, the root of the fins presents ripples and folds. The tangential direction of the end is slightly stretched and thinned, and the finned tube produced by this process has a slightly increased contact area between the fins and the tube, while also increasing the disturbance of the airflow, which is conducive to heat transfer. However, it is precisely because of this crease that the air resistance is increased. In addition, due to the large spacing between fins and the difficulty in improving the wing coefficient, this process has poor economic efficiency. (4) Other winding processes, as the form of winding fins is still evolving, are also constantly improving their manufacturing equipment and methods.