Design and manufacture of tooling: The large flange is composed of two clamping bottom plates that form 900 pieces, two flange support plates, two vertical plates, and four reinforcing rib plates welded together. To ensure the rigidity of the fixture, the welding seams of the connecting plates should be beveled and fully welded, with a welding angle height of 20-30mm. Corresponding bolt holes are drilled on the flange support plate to ensure accurate connection between the flange and the flange support plate with bolts. There is a gap between the back of the small end flange and the support plate that can accommodate a small manual jack. At the same time, a notch is made on the flange support plate in the direction of the vertical plate to fit the elbow into the fixture. A fixture with a similar groove structure made of thicker steel plates can meet the rigidity requirements during cutting. The two flange faces of a large flange are perpendicular to each other, while the worktable of a vertical lathe rotates horizontally. Therefore, the main function of this fixture is to use the bolt holes on the large end flange to connect the fixture with the flange. When the fixture is clamped on the workbench, it should be ensured that the flange plane being processed is concentric and parallel to the vertical lathe workbench.

　　When processing flanges, we first need to understand that such a component may have certain defects during the welding process. If the welding defects of stainless steel flanges are more serious, they are basically polished by manual machinery. This polishing method is used to make up for it, which may produce a series of polishing marks, which may cause uneven surface and directly affect the appearance of the entire equipment. During flange machining, it is possible to polish unevenly, making it difficult to achieve a more uniform treatment effect for workpieces with larger areas during a series of acid pickling and passivation treatments. Therefore, if this effect cannot be achieved, more time will be spent during the machining process, and the material consumption for some auxiliary materials is relatively high. There is also a problem encountered during the processing.

　　There may be some scratches on the flange, which are very difficult to remove. Therefore, during overall passivation, under the conditions of corrosive media, a series of chemical corrosion often occurs, resulting in some rust. To reduce the number of fixtures, the fixture should be able to change the clamping position, ensuring that two ends of the elbow flange can be machined on one fixture. At the same time, the fixture must have sufficient stiffness, otherwise it will seriously affect the processing quality of the flange sealing ring groove. Therefore, in order to meet the usage requirements, the height of the fixture should be reduced as much as possible, which can improve stiffness and facilitate operation. The turning radius of the fixture fixed to the large flange should not exceed the working radius of the vertical lathe, and it should be easy to clamp and adjust, making it convenient for cutting. When the force model of the cantilever beam with slot structure is turned, it undergoes bending and torsion under the force, and its deflection and rotation angle should be verified. Through the above verification, the maximum deflection of 7.27 × lO-7m and the maximum rotation angle of 8.969 × 10-5 are both extremely small deformations. And reinforcement ribs have been added to relevant parts, with a stiffness far exceeding the calculated value. The stiffness can fully meet the requirements of cutting force. The maximum rotation diameter of the fixture combined with the elbow flange is 2.42m<3.50m (double column vertical lathe rotation diameter).