Multi-stand Rolling Mill Drive Shaft Dynamics
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Solution Overview
Problem
Existing multi-stand rolling mills with four motorized rolls have complex mechanical systems for rotating rolls and radial position adjustment, leading to increased size and reliability issues, particularly in transversal and vertical dimensions.
Innovation Solution
A rolling mill design where each roll is actuated independently by a separate drive motor, with drive shafts that can extend and retract reversibly and incline between reference positions, allowing for a simpler and more compact structure, and using an eccentric adjustment system integrated with the drive shafts for radial position adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If four-roll mill stands with complex split ratio motors and 90° transmissions are used to achieve uniform peripheral speed and reduced pinching effect, then product quality is improved, but device complexity and transversal size increase significantly
Solution Approach 1:
The drive system is segmented into four independent drive units, each with its own motor and drive shaft. This eliminates the need for complex split ratio motors and transmission assemblies, while maintaining the four-roll configuration that ensures uniform peripheral speed and reduced pinching effect for high product quality
Solution Approach 2:
The complex transmission assembly (split ratio motor with 90° transmission) is extracted and removed from the system. Each roll is directly driven by its own motor through a simple drive shaft, eliminating the disturbing complex mechanical transmissions while preserving the essential four-roll mill stand functionality
2Ease of operation
If long drive shafts inclined at 22.5° are used to connect motors to rolls in the EP 2 391 460 configuration, then roll actuation is achieved, but transversal extension of the rolling mill increases considerably
Solution Approach 1:
The drive shafts are oriented vertically rather than horizontally inclined at 22.5°. Motors are positioned above each roll with vertically extending drive shafts, changing the spatial dimension of the drive system from horizontal to vertical. This eliminates the need for long transversal drive shafts while achieving effective roll actuation
Solution Approach 2:
The drive shafts are designed to be retractable, allowing them to extend when motors need to be positioned away from rolls for maintenance or replacement, and retract when motors are in position. This dynamic configuration enables compact operation while facilitating ease of maintenance without requiring long fixed transversal extensions
3Adaptability or versatility
If eccentric adjustment devices with worm screw reducers are integrated into mill stand structure to control eccentric rotation, then radial position adjustment is achieved, but device complexity and reliability issues arise
Solution Approach 1:
The complex eccentric adjustment device with worm screw reducer is extracted from the mill stand structure. Radial position adjustment is achieved through simpler means integrated with the drive shaft system, eliminating the need for separate complex adjustment mechanisms while maintaining adaptability for radial position control
Solution Approach 2:
The radial position adjustment functionality is merged with the drive shaft system. The drive shafts incorporate features that enable both motor actuation and radial position adjustment through a unified, simpler mechanism rather than separate complex adjustment devices, reducing overall system complexity and improving reliability
4Stability of the object's composition
If adjustment device is configured to interact with mill stand structure to define retainer for mill stand, then mill stand retention is achieved, but adjustment device complexity increases further
Solution Approach 1:
The drive shaft system is designed with multi-functionality, serving both for motor actuation of rolls and for providing retention support for the mill stand. This eliminates the need for the adjustment device to perform dual functions of both radial position control and mill stand retention, thereby reducing its complexity while maintaining stability through the integrated drive shaft structure
Data Source
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AI summary
The present invention relates to a rolling mill (1) for tubular bodies comprising rolling mills (10) with four rolls. The rolling mill comprises a structure defining a housing (4) for the mill stands (10) and a plurality of drive shafts (31, 32, 33, 34) for rotating a corresponding roll (11, 12, 13, 14) for each mill stand. Each drive shaft (31, 32, 33, 34) extends in reversible manner from a retracted configuration, in which it is operatively disconnected from said corresponding roll (11, 12, 13, 14), to an extended configuration, in which it is operatively connected to said corresponding roll (11, 12, 13, 14). According to the invention, each drive shaft (31, 32, 33, 34) is actuated independently from the other drive shafts and at least one of said drive shafts, when it is in said retracted configuration, is inclinable between a first reference position and a second reference position, so that said at least one drive shaft is outside the space comprised between the two planes which vertically delimit the housing (4).