Multi-roll Mandrel Mill Internal Bearing Design
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Solution Overview
Problem
Multi-roll mandrel mills face limitations in designing the roll diameter ratio to prevent underfill and overfill due to interference of roll chock portions, particularly in producing small-diameter tubes, which restricts the adjustment of the roll diameter ratio and leads to fin flaws and through-wall defects.
Innovation Solution
The solution involves a multi-roll mandrel mill design where bearings are internally contained within the grooved roll body, eliminating the need for external bearing boxes and allowing for adjustable gap settings between rolls, and optimizing the design of roll chock portions by replacing parts based on tube-making setups to prevent underfill and overfill.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If external bearing boxes are used for grooved rolls, then the roll support structure is simple and easy to manufacture, but the roll chock portions interfere with each other in multi-roll mandrel mills, restricting the adjustment of roll diameter ratio and causing underfill or overfill
Solution Approach 1:
The bearing is nested inside the grooved roll body, forming an integrated structure. This eliminates the external bearing box and prevents interference between roll chock portions in multi-roll mandrel mills, enabling flexible adjustment of roll diameter ratio for different tube specifications
Solution Approach 2:
The bearing and grooved roll body are merged into a single integrated component. The bearing is positioned within the grooved roll body and fixed in place, combining the support function with the rolling function in one element, thereby eliminating the need for separate bearing boxes
2Manufacturing precision
If the roll diameter ratio is adjusted to prevent underfill and overfill, then the manufacturing precision improves, but the device complexity increases due to the need for interchangeable roll shafts and roll chock portions
Solution Approach 1:
The mandrel mill is designed with interchangeable roll shafts and roll chock portions that can be dynamically adjusted based on the tube specification being produced. This allows the roll diameter ratio to be optimized for each production run, preventing underfill and overfill while maintaining manufacturing flexibility
Solution Approach 2:
The roll diameter ratio is changed as a parameter to optimize the rolling process for different tube specifications. By selecting appropriate roll shafts and roll chock portions with different dimensions, the system adapts the roll diameter ratio to prevent underfill and overfill conditions
Data Source
Figure 1(a)~2
Figure 3~4(b)
Figure 5
AI summary
Provided is a multi-roll mandrel mill in which "compacting of roll chock portions" is achieved, a plurality of grooved roll bodies is included as a roll pass which performs the reduction rolling of a shell, and a plurality of roll stands each having backup rolls for driving the grooved roll bodies are included, wherein bearings are internally contained in the grooved roll body. A multi-roll mandrel mill in which "optimizing the design of roll chock portions etc. for every setup" is achieved is a mandrel mill provided with a plurality of grooved roll bodies as a roll pass which performs the reduction rolling of a shell and a plurality of roll stands each having roll shafts and roll chock portions for driving the grooved roll bodies, wherein according to a tube-making setup of the mandrel mill, at least one of either or both of the roll shafts and the roll chock portions is replaced with a part(s) having a different shape(s) in addition to the grooved roll bodies. Both cases are elongation rolling mills effective in preventing underfill and overfill.