Stainless Steel Weld Elbow is a cold-drawn seamless pipe with good size and surface finish for mechanical structures and hydraulic equipment. The use of seamless pipes to manufacture mechanical structures or hydraulic equipment can save machining time, improve material utilization, and help improve product quality. Seamless insulated elbows are widely used and can be divided into low-medium pressure seamless insulated elbows, high-pressure seamless insulated elbows, and stainless steel seamless insulated elbows according to different requirements. They can be used for industrial pipelines such as water vapor, air, oil, and gas at different pressures. Seamless insulated elbows have uneven deformation during the cold drawing process, which produces additional stress. After cold drawing, this additional stress becomes residual stress and remains in the pipe. The degree of uneven deformation of seamless insulated elbows determines the size and distribution of its residual stress. The cold drawing deformation of seamless insulated elbows is determined by their deformation characteristics. Since there is no mandrel involved in the processing of the pipe wall during the air drawing process, and the thickness of the pipe wall does not change much after deformation, the deformation conditions and deformation states of the inner and outer layers of the seamless insulated elbows are very different, resulting in uneven deformation. Cold drawn elbows use hot rolled steel coils as raw materials, and are cold rolled after pickling to remove the oxide scale. The finished product is hard rolled coils. The cold work hardening caused by continuous cold deformation increases the strength and hardness of the hard rolled coils, and reduces the toughness and plasticity index. Therefore, the stamping performance will be reduced, and it can only be used for parts with simple deformation. Hard rolled coils can be used as raw materials for hot dip galvanizing plants, because hot dip galvanizing units are equipped with annealing lines.

Due to the uneven deformation during the cold drawing of seamless insulated elbows, the deformation degree is different from the outer surface layer to the inner surface layer. The additional bending deformation and additional shear deformation near the outer surface layer are larger, so the total deformation degree of the outer layer is larger than that of the inner layer. Therefore, the outer grain is finer and the hardness is better, while the inner layer is the opposite. If the tube wall is thicker, the friction coefficient is larger, the taper angle of the die is larger, the difference in the total deformation degree of the inner and outer layers is also greater, and the degree of uneven organization and performance increases. Because the deformation degree of the inner and outer layers is different, the organization and performance of the inner and outer layers of the seamless insulated elbow are inconsistent after deformation. The drawing speed of the seamless insulated elbow has a great influence on the productivity of the tube drawing machine. Drawing can shorten the drawing cycle and improve the productivity of the drawing machine. At present, the drawing speed of domestic technical machines has reached 40m/min (adjustable speed), and the drawing speed of the drawing machine has reached 100m/min.

Causes of cracks in seamless insulated elbows in stainless steel pipe fittings:

1. Raw material factors. Poor quality tube billets will have internal and external warping, scarring, cracks, etc.;

2. Temperature factors. An important process in the production of seamless insulated elbows is heating. Poor heating (uneven, insufficient temperature, etc.) will cause internal warping, etc.;

3. Equipment factors. From the beginning of the furnace, each equipment component will affect the final quality of the pipe. For example, the collision and scraping of equipment components will cause external warping and pits; if the perforator is not smooth, it will cause the head of the tube billet to be sprayed with water and difficult to bite into or the head to warp;

4. Process problems. The process problems are also quite complicated. There are adjustment problems, equipment failure problems, and pipe quality problems caused by wear of process components (head, guide plate, roller, etc.). The problems caused are all-encompassing.

Anti-wrinkle characteristics of seamless insulated elbows and anti-wrinkle mold usage characteristics

1. Seamless insulated elbows use high-frequency welded pipes, seamless insulated elbows and square tubes as blanks. Medium-frequency electromagnetic interference heating is pushed into shape through molds or bent into shape through rockers according to a predetermined trajectory. The material does not change arbitrarily after the product is formed.

2. Seamless insulated elbows comply with the corresponding standards and performance use and control, showing good performance and playing a good role.

3. The anti-wrinkle mold for seamless insulated elbows includes three parts: a movable mold, a fixed mold and a bending turntable.

4. The anti-wrinkle mold for the bending pipe is improved on the basis of the existing bending anti-wrinkle mold through structural improvements, avoiding the incorrect structure of the existing anti-wrinkle mold movable part and the bending turntable, and improving the strength and wear resistance of the opposite parts.

5. The anti-wrinkle mold for the bending pipe is characterized in that the fixed mold and the bending turntable are connected and fixed to the fixed mold base on the machine tool by bolts respectively.

6. The movable die is connected to the movable slide on the machine tool through bolts. The contact part between the movable die and the bending turntable is comb-shaped, inlaid with each other, and can slide relatively. The use of steel structure bending pipe is equivalent to its parent material, and the surface quality is smooth.