1. Cutting: Cut the steel pipe or prefabricated welded pipe billet into pipe segments of the specified length. Generally, the
segment length is equal to or slightly greater than the height of the finished reducer. Grind the excess height of the weld seam on the welded pipe billet flush with the base material.
2. Local heating: Place the pipe billet in a cylindrical induction heating coil, and start the medium-frequency power supply to heat the section of the billet that needs deformation and necking to the specified temperature, ensuring that the billet is heated evenly and without overheating.
3. Press forming: Vertically place the heated tube billet with the hot end downward into a mold with the large end facing upward. Start the press slider to press the billet until the end is flush with the mold, and the heated part is necked along the inner wall of the mandrel. Then, the mold is lifted and flipped upside down by the press slider using iron chains, pushing the billet into the corresponding workstation tool. After that, use a steel pipe with the same diameter as the small end of the reducer to push the formed reducer out of the mandrel using the press slider, completing the forming of the reducer.
4. End shaping: According to process specifications, cut off the excess parts of the reducer pipe at both ends while leaving a certain machining allowance, then heat both pipe ends and shape them on a hydraulic press to achieve the requirements for machining the pipe end bevel.
5. Weld inspection: Perform 100% radiographic and ultrasonic non-destructive testing on the
longitudinal seams of seam pipes pressed into reducer pipes. Defective areas exceeding the standard are repaired according to the qualified weld repair procedure, and the same area shall not be repaired more than twice.
6. Heat treatment: Perform the corresponding heat treatment according to the material's heat treatment process specifications, so that the crystal structure inside the product, which was distorted or damaged due to extrusion forming and thermal processing, is restored to the original material's structure, ensuring that the finished reducer has the same performance state as the original material. After treatment, conduct surface hardness tests on each reducer individually.
7. Surface treatment: The surface treatment of hot press-molded reducers and the machining of end bevels are the same as those for other pipe fittings.
8. Finished Product Inspection: The finished reducer pipes that have passed process flow inspections are fully measured on the testing platform for appearance, dimensions, and geometric deviations. Products that pass the dimensional measurements undergo comprehensive non-destructive testing.