The requirements for ship elbows are relatively strict. Most of the materials used are carbon steel 20 # seamless elbows, which save space and reduce the weight of the ship. For large-diameter elbows, R=1 times the elbow will be chosen. The production process of 1 times the elbow is more complex than that of 1.5 times the elbow, with several additional processes. The first step is to produce a finished elbow that is 1.5 times 60 degrees, which is equivalent to 2/3 of the mass of a 90 degree elbow that is 1.5 times. Heat the 60 degree elbow and press it into a mold that doubles the elbow, resulting in a 90 degree elbow blank. However, the current blank has an irregular circular inner diameter, which is a bit elliptical and needs to be processed. We need to prepare 3-4 balls with different diameters (choose the diameter of the ball according to the inner diameter of the elbow). First, place the elbow in the mold, select a suitable ball and place it on one end of the elbow's diameter. Use a press to press in the inner diameter of the elbow. Then, select the larger ball and continue to press in the same way as before. Use a small ball to push out all the balls inside the elbow. Measure whether the outer diameter of the elbow and the half waist of the elbow are regular circles. If they are not qualified, they need to be reprocessed