Seamless Pipe R-Chamfering to Prevent Metal Chips
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Solution Overview
Problem
Cold rolling of seamless pipes generates metal chips from end portions, leading to indentation formation and compromising surface quality, with existing methods failing to effectively inhibit chip generation.
Innovation Solution
R-chamfering the end portions of seamless pipes at both the starting and finishing sides, with the radius of the R-chamfer satisfying the condition (T0−T1)/2≦R≦T0/2, to prevent metal chip formation during cold rolling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cold rolling is performed on seamless pipes using a Pilger mill, then a high degree of reduction can be achieved, but metal chips are generated from end portions causing indentation formation and poor surface quality
Solution Approach 1:
The end portions of the seamless pipe are R-chamfered before cold rolling to prevent metal chip generation during the rolling process. By performing this preliminary action of rounding the edges, the patent eliminates the root cause of chip formation that would otherwise occur during cold rolling, thereby maintaining high surface quality while achieving the required degree of reduction
2Ease of manufacture
If the end portions of seamless pipes are not chamfered, then the cold rolling process can be performed without additional preparation, but metal chips are generated leading to indentation formation
Solution Approach 1:
R-chamfering of the end portions is performed as a preliminary action before cold rolling. This simple preparatory step rounds the sharp edges that would otherwise generate metal chips during rolling, thereby preventing indentation formation and maintaining good surface quality without significantly complicating the manufacturing process
3Object-generated harmful factors
If R-chamfering with inappropriate radius is applied to end portions, then chip generation may be reduced, but the chamfering process becomes more complex or the pipe geometry is compromised
Solution Approach 1:
The patent specifies precise parameter ranges for the R-chamfering radius (R) based on the pipe wall thickness (t): 0.05t ≤ R ≤ 0.2t. By optimizing this geometric parameter within specific bounds, the invention effectively prevents metal chip generation during cold rolling while maintaining simple and straightforward chamfering operations that do not overly complicate the manufacturing process
Data Source
AI summary
In performing cold rolling on a seamless pipe as a mother pipe, it is possible to inhibit the generation of metal chips from the end portions of the mother pipe, and to prevent the formation of indentations therein that may be caused by the metal chips to thereby provide good surface appearance. This is made possible by using a mother pipe (1) having end portions at the cold rolling starting side and finishing side that have been R-chamfered, at each outer edge and at each inner edge, such that (T0−T1)/2≦R≦T0/2 is satisfied, where R is a radius (mm) of the R-chamfer on the outer edges and the inner edges of the end portions, T0 is a wall thickness of the mother pipe, and T1 is a wall thickness of the pipe after cold rolling.