There are many different pipe bending processes in practice, and there are many different automatic pipe bending machine mold classifications from different perspectives. In engineering, the bending is usually divided into cold bending and hot bending according to whether the pipe is heated or not. According to whether there is filler during bending, it is divided into cored bend and coreless bend. Copper pipes, especially thin-walled copper pipes, are bent by cold bending. law. The cold bending method is to bend the pipe into shape at room temperature. Since the pipe does not need to be heated, it is more suitable for bending stainless steel pipes, aluminum pipes and copper pipes. Commonly used cold bending methods include roll bending, stretch-wound bending, push-wound bending and pressure bending, etc. Now we mainly introduce the related problems of tube fittings in stretch-wound bending. In general, the bending radius of cold bending should not be less than 1.5 times the pipe diameter. Because the tube has a certain degree of elasticity, when the external force applied during bending is eliminated, the tube will bounce back to an angle, and the tube bender mold must have a certain amount of bending during bending. The amount of springback is related to the mechanical properties, wall thickness and bending radius of the pipe material. Generally, the springback angle of copper pipes is about 2 to 4 when bending. Stretch bending is to clamp the pipe on the pipe bending machine mold and rotate with the pipe bending mold. When the pipe is pulled through the pressure block, the pressure block will bend the pipe on the bending mold, which belongs to the forming mold bending process.
With the development of the CNC machine tool industry, the use of advanced CNC pipe bending machine tools, equipped with reliable and accurate pipe bending machine molds to achieve the bending process can greatly improve production efficiency and ensure product quality. As the process parameters can be adjusted conveniently, the CNC pipe bending machine can accurately and stably complete the straightening, rounding, feeding, bending and other actions, ensuring the bending accuracy of the control parts. However, the quality of bent copper pipes is more sensitive to process parameters, so there is sufficient preliminary preparation and trial production for the requirements, especially for bending thin-walled copper pipes. If the process parameters of the pipe bender die are not properly selected, it is prone to wrinkles. , Resulting in scrapped parts. How to efficiently and accurately obtain these process parameters and fully guarantee the quality of the bending products is the research hotspot of CNC bending technology. In draw-winding, the position of the core rod relative to the bending point is very important. The core rod advances a certain position relative to the bending point (the working end of the core rod enters the bending section of the tube) although the ellipticity can be reduced, but when the core rod is too advanced The tube wall thinning will increase in a long time, so the position of the mandrel should be determined after 3 to 4 samples are bent. In addition, the core rod must move backwards when bending thick-walled tubes, and the core rod must move forwards when bending thin-walled tubes.