The bending method of stainless steel elliptical tube generally adopts cam principle method. Cam principle and method have been used for machining multi-arc thin-walled stainless steel oval tubes many times. Therefore, everyone has heard of cams. When the camshaft rotates, the follower is connected with the cam contour, and the follower moves back and forth. According to this principle, as long as five arcs are designed on a mold, the length of each arc center layer is equal to the length of the product arc center layer (R on the mold is smaller than R on the product due to large rebound), and the mold with large included angle between the arc centers is used as the rotation center, and the follower is selected as the cylinder. Due to the compressibility of gas, pneumatic pressure can be adjusted by reducing valve. If the bending pressure is high, the booster cylinder can be selected, the piston rod is connected with the bending roller seat, and there is a pressure reducing valve below the roller seat. The key factors affecting the wrinkling of elliptical tube are bending speed and lining material of elliptical tube. How to control the bending speed can be controlled by proportional flow valve. When the bending radius r is small, the speed control should be appropriate.