Bend is bent by a complete set of bending equipment, which is divided into two processes: cold simmering and hot pushing. No matter what kind of machinery, equipment and pipelines, most of them use elbows, which are mainly used for oil, gas, liquid infusion, engineering bridge construction, etc.
Analysis of the main reasons for the decline in the quality of elbows and attention methods:
1. During pure bending, under the action of the external force distance M, the outer arm wall of the neutral layer is thinned by tensile stress &1, and the inner side is subjected to compressive stress. The thickness increases due to the action, and the resultant forces N1 and N2 change the cross-section of the pipe. Based on this factor, RX and SX are the main reasons for the quality decline of the elbow. Therefore, in GBJ235-82, the RX value and the outer thinning amount under various pressure levels are clearly specified, the purpose is to control the RX with the value of SX, thus ensuring quality.
2. As mentioned in the previous article, when the pipe is bent, the outer side of the material is stretched, and the position of the neutral axis under pressure on the inner side is different from the pipe bending method. When the top bending (compression bending) works, the neutral axis is about 1/1/2 away from the outer wall. 3, when working in a swivel (return-bend) operation, the neutral axis is at 2/3 of the outer wall. Therefore, thin-walled pipes are bent, and it is beneficial to use the whirling method.
3. The accuracy of the bending tire is also one of the factors affecting the quality of the bending pipe. When we manufacture curved tires, in addition to the specification and size requirements to be controlled within a certain tolerance range, we also require users to select corresponding curved tires according to the bending pipe diameter when using.
4. The bendability and surface corrosion of the pipe itself may also affect the quality of the pipe bend. During on-site construction, the operator also needs to know the material of the pipeline to be processed, the processing performance and make a production judgment on the surface corrosion.
5. R is now available. (Bending radius/Tube outer diameter) relationship graph for reference when selecting the relationship between tube diameter and wall thickness. Reflecting the influence of relative bending radius and relative wall thickness on the quality of elbow, according to the acceptance specification for pipeline processing: cold-formed steel pipeline is 4D for medium and low pressure, and 5D for high pressure. Therefore, our bending tire design is R=4D (special case), so for the pipe bending machine produced by our factory, the relative wall thickness SX is mainly selected. The upper part of the picture is the mandrel-free area, and the middle part of the picture It is the common mandrel area, and the lower part of the figure is the special mandrel area. Because the design and manufacture of special mandrels are very difficult and the operation is not very convenient, our factory generally does not supply them. Special circumstances may be negotiated separately.
6. The influence of lubrication on product quality during the molding process:
In the traditional pipe bending production process, enterprises will take many measures to obtain better surface quality of the curved pipe, including: using more advanced and high-end pipe bending machines, using higher strength molds, or using lubricating products, etc. Method. The use of high-end pipe bending machines and high-strength molds often requires a large investment in enterprises. Only the use of pipe bending lubricating products is relatively inexpensive and fast to meet the product quality requirements of enterprises. However, in the traditional production process: oil-based elbow lubrication products can meet the quality requirements of enterprises in elbow production, but the oil-based elbow lubrication products are not easy to clean and pollute the environment. , so the enterprise must use more means to eliminate the impact of oil-based elbow lubrication products on the quality of the final product, and invest more energy and money for this. The arrival of IRMCO elbow water-based lubricating grease not only meets the requirements of enterprises for the quality of elbow products, but also avoids and reduces the increased investment of enterprises due to the use of oil-based elbow lubrication products, and completely optimizes the production process of enterprises.
