Three-Roll Inclined Rolling for Variable-Wall Seamless Tubes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing two-roll-type inclined rolling mills used in the Mannesmann process for producing seamless metal tubes face issues such as Mannesmann fracture, leading to inner flaws, and outer flaws due to damage from disk rolls, limiting the production of tubes with small wall thickness and requiring frequent maintenance of disk rolls.
Innovation Solution
A three-roll-type inclined rolling mill is adapted to produce seamless metal tubes with varying wall thicknesses by adjusting the cross angles and lateral surface angles of the inclined rolls, eliminating the need for guiding tools and reducing material thrusting, thus preventing flaws and allowing for the production of both thin-walled and thick-walled tubes without quality issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a two-roll-type inclined rolling mill is used for piercing rolling, then the structure is simple and ease of manufacture is improved, but Mannesmann fracture occurs causing inner flaws and the reliability deteriorates
Solution Approach 1:
The rolling process is divided into two distinct stages: piercing rolling using a two-roll-type inclined rolling mill to create the hollow shell, followed by elongating rolling using a separate three-roll-type inclined rolling mill to eliminate Mannesmann fracture. This segmentation allows each process to be optimized independently, maintaining manufacturing simplicity while improving final product reliability
Solution Approach 2:
The hollow shell produced in the first piercing rolling stage serves as an intermediary product that transfers the workpiece between two different rolling mill types. This intermediary form allows the subsequent elongating rolling process to correct the Mannesmann fracture issue without requiring complete process redesign
2Device complexity
If a two-roll-type inclined rolling mill with guiding tools is used, then the structure is simple, but outer flaws occur due to disk roll damage and maintenance frequency increases
Solution Approach 1:
The guiding tools (disk rolls) that cause outer flaws and maintenance issues are completely removed from the system. The three-roll-type inclined rolling mill performs elongating rolling without requiring any guiding tools, eliminating the source of outer flaws and reducing maintenance needs while maintaining structural simplicity
Solution Approach 2:
Instead of using guiding tools to control the workpiece during rolling, the invention inverts the approach by using the three-roll configuration itself to naturally control and guide the hollow shell through the rolling process, eliminating the need for separate guiding components
3Reliability
If a three-roll-type inclined rolling mill is used for piercing rolling, then Mannesmann fracture is prevented and reliability is improved, but the ability to produce tubes with small wall thickness is limited and adaptability deteriorates
Solution Approach 1:
The system achieves universality by making the three-roll-type inclined rolling mill serve multiple functions: it performs elongating rolling to eliminate Mannesmann fracture, and by adjusting the cross angle of the inclined rolls, it can produce tubes with various wall thicknesses including small wall thickness tubes, thus combining reliability improvement with enhanced adaptability
Solution Approach 2:
The cross angle of the inclined rolls in the three-roll-type inclined rolling mill is made adjustable rather than fixed. This dynamic parameter allows the same equipment to adapt to different production requirements, enabling the production of tubes with diverse wall thicknesses while maintaining the reliability benefits of the three-roll configuration
4Adaptability or versatility
If the cross angle of inclined rolls is increased to produce thin-walled tubes, then adaptability is improved, but material thrusting increases and manufacturing precision deteriorates
Solution Approach 1:
The invention changes the parameter configuration by setting the cross angle within a specific range (0° to 15°) rather than using large angles. This parameter optimization allows thin-walled tube production while controlling material thrusting, and the entrance-side lateral surface angle is also optimized to prevent engagement failure, thereby maintaining manufacturing precision while achieving adaptability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method enables the practical use of three-roll-type inclined rolling mills for producing seamless metal tubes with diverse wall thicknesses, preventing Mannesmann fracture and outer flaws, and reducing maintenance needs, thereby enhancing production efficiency and quality.
Implementation Method 1
the central portion of the rolling workpiece receives a compression stress, which acts in the direction in which the inclined rolls face each other
Implementation Method 2
a tensile stress, which acts in the direction in which the guide members face each other
Implementation Method 3
The workpiece moves forward on the pass line while rolling around its own axis and is piercing-rolled by the inclined rolls and the plug
Data Source
AI summary
A method disclosed herewith is a method for producing a first seamless metal tube with a first wall thickness and a second seamless metal tube with a second wall thickness by using a three-roll-type inclined rolling mill, and the method includes a first inclination rolling step (#5), a setting changing step (#10), and a second inclination rolling step (#15). At the first inclination rolling step, a first workpiece is rolled by the inclined rolling mill. At the setting changing step, a setup condition of the inclined rolling mill is changed in a manner (a) or (b) as described below. At the second inclined rolling step, a second workpiece is rolled by the inclined rolling mill under the changed condition. (a) When the second wall thickness is smaller than the first wall thickness, the cross angle of each of the inclined rolls is made greater than the cross angle set for the first inclination rolling step. (b) When the second wall thickness is larger than the first wall thickness, the cross angle of each of the inclined rolls is made smaller than the cross angle set for the first inclination rolling step.