Manufacture process of thin-wall U-shaped bend pipe with small bending radius

Abstract

The invention discloses a manufacture process of a thin-wall U-shaped bend pipe with small bending radius. The manufacture process comprises the following steps: (A) filling sands: filling sands into a pipe fitting fully and closing two ends; (B) prebending: assembling the pipe fitting on a top-upsetting pipe-bending machine: clamping one end of the pipe fitting by a top-upsetting clamp, fixing the other end of the pipe fitting by a pipe bending mold and a clamping block, driving the pipe bending mold to rotate by a main shaft, applying axial pushing force to the top-upsetting clamp by an oil cylinder, and enabling the pipe fitting to be bent to have the preset bending radius R1; (C) hot extrusion: heating the pipe fitting to preset temperature, placing the pipe fitting into an extrusion mold to be extruded to have the bending radius R0, then placing into a forming mold with a U-shaped cavity, extruding the pipe fitting to enter a cavity formed by an upper mold piece and a lower mold piece through mold closing, thereby realizing forming, wherein the final bending radius of the pipe fitting is R0, and R0<R1; D) removing end covers at two ends of the pipe fitting and the sands in the pipe. According to the manufacture process, the deformation of the bend pipe can be reduced, the ball-through diameter requirement can be met, the rate of finished product is high, the working procedures are less, the processing operation is simple, the cycle is short and the production cost is low.

Description

technical field [0001] The invention relates to a manufacturing process for thin-walled U-shaped elbows with small bending radius. Background technique [0002] In some gasification furnaces, U-shaped (180°) elbows (such as φ38X4) of nickel-based stainless steel have small bending radii (R20 and R25) and thin tube walls. The heat flow is greater, and the appropriate water flow is the key parameter, so the requirements for passing the ball are much higher than ordinary boilers and ASME related standards; there are two main manufacturing processes for the existing thin-walled small bending radius U-shaped elbow: 1) in the stretch bending After pre-bending on the pipe bender or side-assisted pipe bender, hot extrusion is performed again; in this method, due to the pressure on the inner wall of the bend section and the tension on the outer wall during pre-bending, the diameter reduction on the outer side is relatively large. Its roundness is poor, and the diameter of the throug...

AI Technical Summary

Problems solved by technology

[0002] In some gasification furnaces, U-shaped (180°) elbows (such as φ38X4) of nickel-based stainless steel have small bending radii (R20 and R25) and thin tube walls. The heat flow is greater, and the appropriate water flow is the key parameter, so the requirements for passing the ball are much higher than ordinary boilers and ASME related standards; there are two main manufacturing processes for the existing thin-walled small bending radius U-shaped elbow: 1) in the stretch bending After pre-bending on the pipe bender or side-assisted pipe bender, hot extrusion is performed again; in this method, due to the pressure on the inner wall of the bend section and the tension on the outer wall during pre-bending, the diameter reduction on the outer side is relatively large. Its roundness is poor, and the diameter of the through-ball of the subsequent finished product is reduced; during hot extrusion, due to the thin wall and poor rigidity, it is easy to lose stability and wrinkle, and the inner wall is easy to thicken, and the diameter of the through-ball is also affected, resulting in this item The indicators are difficult to meet the requirements, and the scrap rate is high; 2) U-shaped solid forgings are made, and then formed by machining U-shaped through holes; although the diameter of the through ball can meet the standard in this method, there are many process steps, difficult processing, and long cycle time. Disadvantages of high cost

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