Analysis of the main causes of the quality decline of
steel bending pipe and methods of attention. When the pipe is purely bent, under the action of the external force distance M, the outer arm wall of the neutral layer of the pipe is thinned by the tensile stress &1, and the inner side is subjected to compressive stress. It thickens due to the action of N1 and N2, and the cross-section of the tube changes due to the combined force of N1 and N2. Based on this factor, the main reasons for the decline in steel bending pipe quality are RX and SX. Therefore, in GBJ235-82, the RX value and the amount of outer thinning under various pressure levels are clearly defined. The purpose is to control the values of RX and SX to ensure quality.
When a steel bending pipe is used, the outer side of the material is under tension. When it comes to the inner side of the steel bending pipe, the position of the neutral axis is different from the steel bending pipe method. When working in top bending (compression bending), the neutral axis is about 1/2 away from the outer wall. 3. When working in swivel bending (return bending type), the neutral axis is located 2/3 away from the outer wall. Therefore, it is beneficial to use the spiral bending method for thin-walled pipe bending.
The accuracy of tire bending is also a factor that affects the quality of steel bending pipe. The bending function and surface erosion of the pipe itself may also affect the quality of steel bending pipe. During on-site construction, the operator also needs to understand the material and processing performance of the pipe being processed and make production judgments on surface erosion.
