Tube Rolling Mill Mandrel Traction to Eliminate Push Bars
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Solution Overview
Problem
Existing rolling mills for seamless tubes face issues with mandrel stability, high maintenance costs, and dimensional tolerance deterioration due to the use of push bars, which require extensive guides and complex setup for different diameters, leading to safety risks and inefficiencies.
Innovation Solution
A rolling mill design that uses traction on the mandrel to move both the mandrel and the tubular blank through mill stands, eliminating the need for push bars and associated guides, and incorporating a switchable operating head with rocker arms to facilitate smooth translation and engagement, reducing the complexity and cost of operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a push bar is used to move the mandrel through mill stands, then the mandrel can be pushed through the rolling mill, but the system requires extensive guides and containment structures, increasing device complexity and maintenance costs
Solution Approach 1:
Instead of pushing the mandrel from behind using a push bar, the invention applies traction by pulling the mandrel from the front through the mill stands. This inversion eliminates the need for extensive guides and containment structures that were required to stabilize the push bar-mandrel assembly, thereby reducing device complexity while maintaining operational effectiveness.
2Force
If a push bar of length greater than the mandrel is used, then the mandrel can be effectively pushed, but the overall system length increases, requiring more space and larger containment guides
Solution Approach 1:
The invention replaces the long push bar with a shorter traction mechanism that pulls the mandrel from the front. This eliminates the need for a push bar longer than the mandrel itself, reducing the overall system length and space requirements while maintaining effective force application to move the mandrel through the mill stands.
3Productivity
If the mandrel is pushed through the mill stands, then the blank can be rolled into tubes, but twisting movements occur, deteriorating dimensional tolerances
Solution Approach 1:
By changing from pushing to traction, the mandrel is pulled through the mill stands in a more controlled manner that prevents twisting movements. This inversion of the force application method maintains the productivity of tube production while significantly improving dimensional tolerances by eliminating the instability inherent in push bar systems.
4Ease of operation
If push bar and mandrel are used together, then the blank can be fed through the rolling mill, but side loads are applied to the mill stands, risking damage and requiring robust fixing systems
Solution Approach 1:
The traction system pulls the mandrel through the mill stands rather than pushing it, which eliminates side loads on the mill stands. This inversion of the force direction removes the harmful lateral forces that required robust fixing systems and posed damage risks, while maintaining effective blank feeding through the rolling mill.
Data Source
Figure 1a~1h
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AI summary
A rolling mill for rolling hollow or, in all cases, concave rod-shaped bodies, in particular tubes, in particular seamless tubes, said rolling mill comprising a rolling section (10) with a plurality of mill stands and/or rolling dies (11) arranged in succession to define a rolling axis Y, said rolling mill further comprising moving means for moving a mandrel (20) and a tubular blank (21) fitted onto an end portion (22) of said mandrel (20) along said rolling axis and through said mill stands or rolling dies (11) in succession; wherein said moving means are structured so as to move said mandrel (20) and said blank (21) along said rolling axis Y and through said mill stands or rolling dies (11) in succession by applying a traction on said mandrel.