2D elbows generally refer to metallic elbows used in plumbing and drainage engineering. Small-diameter elbows can be obtained through bending processes; cold bending or hot bending. Typically, medium and small-sized elbows are processed using cold bending methods, while larger diameters require hot bending. Bending processing usually refers to on-site completion.
The basic process for a 2D elbow is as follows: First, weld a cross-section that is polygonal into a multi-faceted ring shell or a multi-faceted fan-shaped shell with both ends closed. After filling the internal cavity with pressure medium, apply internal pressure. Under this pressure, the cross-section gradually transitions from a polygonal shape to a circle, eventually forming a round ring shell. Depending on requirements, one circular ring shell can be cut into four 90° elbows, six 60° elbows, or other specifications of elbows. This process is suitable for manufacturing any specification of large elbows where the ratio of the outer diameter to the inner diameter of the elbow is greater than 1.5. It is currently the ideal method for producing large pressure-bearing elbows. The main advantages are as follows:
(1) No need for pipe blanks as raw materials, which can save on pipe-making equipment and mold costs, and can produce elbows of any large diameter with relatively thin walls.
(2) The blank is a flat plate or developable surface, making material cutting simple, precision easy to ensure, and assembly welding convenient.
(3) Due to the above two reasons, the manufacturing cycle can be shortened, and production costs significantly reduced. As no special equipment is required, it is especially suitable for on-site processing of large elbows.
Elbows can be classified as: stamped elbows, steel plate butt-welded elbows, alloy elbows, forged elbows, U-shaped elbows, segmented elbows (shrimp waist), wear-resistant elbows, bi-directional steel wear-resistant elbows, 180° elbows, 2D, 2.5D, 3D elbows, bent pipes, and bent elbows.
Stamped elbows: Most elbows used in water systems in engineering (especially those with large diameters) can be purchased as finished products. The processing method involves stamping, ensuring good product consistency.
Pushed elbows: In the late 1980s, there was contact with the process of pushing steel elbows using machinery + molds + mid-frequency heating. However, later on, due to difficulties in controlling wall thickness on both the inside and outside, practical applications became rare.
There are many foreign flange standards.
Elbow classification methods: According to their radius of curvature, they can be divided into long-radius elbows and short-radius elbows. Long-radius elbows have a curvature radius equal to 1.5 times the pipe's outer diameter, i.e., R = 1.5D. Short-radius elbows have a curvature radius equal to the pipe's outer diameter, i.e., R = D. Here, D represents the elbow's diameter, and R represents the curvature radius. If classified by pressure grade, there are approximately seventeen types, consistent with American pipe standards, including: Sch5s, Sch10s, Sch10, Sch20, Sch30, Sch40s, STD, Sch40, Sch60, Sch80s, XS; Sch80, Sch100, Sch120, Sch140, Sch160, XXS, among which the most commonly used are STD and XS types. By angle, there are 45° elbows, 90° elbows, and 180° elbows. Thus, there are many types of elbows. Orders often use the following notation: For example, "LR STD 90o 8" indicates a long-radius elbow, pressure grade STD, 90°, 8" elbow; another example, "SR XS 45o 4" indicates a short-radius elbow, pressure grade XS, 45°, 4" elbow. The above is the general classification situation for elbows.
Elbows come in 90° and 45°. The bending radius is standardized. There are also distinctions between long and short radius elbows.
This article source: Zhuohui 2D Elbow (http://www.hbzhuohui.com/wtgj/2dwt.html).