Pipe End Arc Punch Cutting for Burr-Free Welding Fits
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Solution Overview
Problem
Existing methods for shaping pipe ends for welding, particularly in T-junctions, face challenges such as incomplete cutting due to cutting burrs, difficulty in automation, and tool durability issues when cutting outwardly from within the pipe, as they often fail to ensure a gapless engagement of the branch pipe's surface with the main pipe's surface.
Innovation Solution
A method and apparatus that utilize a punching tool with an arc-shaped cutting edge and a mold with a contour arc matching the cutting edge, allowing for two successive cutting phases with the cutting arc's chord exceeding or matching the pipe's external diameter, enabling complete cutting without internal burrs and facilitating automation through a readily replaceable tool arrangement and automated operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If cutting is performed outwardly from within the pipe using a punching tool, then cutting burrs in the internal corner are eliminated and gapless engagement is achieved, but the cutting tool durability is insufficient and automation is difficult
Solution Approach 1:
The cutting process is divided into two successive phases: first cutting one arc-rimmed piece, then rotating the pipe 180° and cutting the second piece. This segmentation allows the punching tool to maintain adequate support and structural integrity during each cutting phase, improving tool durability while achieving complete cutting without internal burrs.
Solution Approach 2:
The pipe is rotated 180° between the two cutting phases, transforming the static single-direction cutting approach into a dynamic two-directional process. This enables the punching tool to cut from both directions, ensuring complete material removal and eliminating internal burrs while maintaining tool durability through proper support during each phase.
2Manufacturing precision
If the pipe is rotated 180° between cutting operations to perform complete cutting, then gapless engagement is achieved, but automation becomes difficult and time consumption increases
Solution Approach 1:
The punching tool is designed with a universal capability to cut from both directions after pipe rotation. The same tool performs both cutting phases, and the mold can accommodate pipes of various sizes within a given range. This multi-functionality simplifies the automation system by using a single tool rather than requiring separate tools for each direction.
Solution Approach 2:
The pipe is pre-positioned in the mold with proper alignment before cutting begins. The mold is designed to hold the pipe securely, and the punching tool is pre-aligned with the pipe axis. This preliminary preparation ensures that the 180° rotation and subsequent cutting can be automated efficiently without complex repositioning operations.
3Device complexity
If a single punching tool is used for both cutting directions, then tool complexity is reduced, but tool durability is insufficient
Solution Approach 1:
The cutting operation is segmented into two phases with the pipe rotated 180° between them. This allows a single punching tool to cut from both directions while maintaining adequate support and structural integrity during each phase, improving tool durability without requiring multiple tools or complex tool arrangements.
Solution Approach 2:
The system uses dynamic rotation of the pipe rather than a complex multi-directional tool. The single punching tool remains relatively simple while the pipe rotation provides the necessary cutting directions, maintaining tool durability through proper support during each cutting phase.
4Manufacturing precision
If the cutting arc chord matches the internal diameter of the pipe, then complete cutting is achieved, but the tool requires major use of force and durability is reduced
Solution Approach 1:
The cutting arc chord is designed to substantially exceed the internal diameter of the pipe, providing excessive cutting action that ensures complete material removal without requiring the tool to exert major force. The larger cutting arc distributes the cutting force more effectively while guaranteeing complete cutting and elimination of internal burrs.
Data Source
Figure 1~3
Figure 4~6
AI summary
The invention relates to a method and apparatus for shape cutting a pipe end. An arched cutter (4) of a punching tool (3, 4) is inserted into an end of a pipe (1) for penetrating the same into a wall of the pipe (1) in a plane of the arched cutter. Then, the punching tool is displaced in a direction perpendicular to a center axis (C) of the pipe (1), whereby the arched cutter (4), while moving outwards from inside the pipe, shears off a piece that matches its shape. The punching tool (3, 4) is withdrawn out of a pipe end, the punching tool is rotated 180°, it is re-inserted into the pipe end and the punching tool (3, 4) is displaced in a direction which is perpendicular to the pipe center axis (C) and opposite to the previous displacement direction, thus enabling the shearing off the pipe end a second piece matching the shape of the arched cutter (4).