Worm and Rack Rest Bar Assembly for Rolling Mill Guides
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Solution Overview
Problem
Conventional rest bar assemblies in rolling mills face issues with binding and damage in adjustment mechanisms, leading to increased weight, cost, and complexity due to oversized designs and varied mounting configurations, which complicate aftermarket support and increase torsional loading.
Innovation Solution
A rest bar assembly with a central fixed core, removable keyed mounting plates, and a self-locking worm and rack adjustment mechanism, where the worm is externally mounted on the core and meshes with a helically cut rack, allowing for easy adjustment and minimal damage, and separate mounting plates that can be designed to fit different roll stand configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a threaded shaft and nut adjustment mechanism is used, then the saddle can be adjusted along the core, but the mechanism is prone to binding, bending, seizing, and physical damage to threads
Solution Approach 1:
The patent replaces the traditional threaded shaft and nut mechanism with a worm gear and rack system. The worm gear (212) engages with the rack (204) cut into the core (200), providing a more reliable adjustment mechanism that resists binding and seizing. This mechanical substitution eliminates the thread damage and seizing problems inherent in traditional screw mechanisms while maintaining the ability to adjust the saddle (208) position along the core.
Solution Approach 2:
The adjustment mechanism is segmented into distinct components: the worm gear (212) mounted on the saddle and the rack (204) integrated into the core. This segmentation allows independent optimization of each component and facilitates easier maintenance and replacement. The worm gear can be replaced without damaging the core, and the rack is protected within the core structure, reducing overall system vulnerability.
2Reliability
If the threaded shaft is located close to the center of the saddle to reduce binding, then the saddle becomes excessively large and creates excessive torsional loading
Solution Approach 1:
The patent moves the adjustment mechanism from a longitudinal arrangement (threaded shaft along the core length) to a transverse arrangement (worm gear engaging the rack on the back side of the core). This dimensional change allows the mechanism to be positioned optimally for both reliability and structural integrity, eliminating the need to compromise between these conflicting requirements.
3Strength
If mounting plates are integrated with the core as a single weldment or casting, then rigidity is improved, but new designs are required for each mounting configuration increasing complexity and cost
Solution Approach 1:
The mounting plates (220, 222) are segmented from the core (200) and designed as separate, interchangeable components. This allows the core to be standardized while mounting plates can be varied to accommodate different roll stand configurations. The segmentation maintains rigidity through proper connection mechanisms while reducing design complexity by allowing modular adaptation to different applications.
Solution Approach 2:
The core (200) is designed as a universal component that can work with multiple types of mounting plates (220, 222) for different roll stand configurations. This universality reduces the need for custom-designed cores for each application, simplifying manufacturing and inventory while maintaining the required rigidity through the standardized core design.
4Adaptability or versatility
If the rest bar assembly is designed to accommodate varied mounting configurations, then adaptability is improved, but weight, material usage, and cost increase
Solution Approach 1:
The system is segmented into a standardized core (200) and interchangeable mounting plates (220, 222). This allows adaptability to different mounting configurations through plate selection rather than core redesign, significantly reducing the weight and material usage compared to designing unique assemblies for each configuration.
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 solution reduces the likelihood of binding, minimizes damage, and allows for standardized core production, reducing weight, cost, and torsional loading while simplifying the design and inventory process by enabling smaller adapter plates and adaptable mounting configurations.
Implementation Method 1
an adjustment mechanism comprising a helically cut rack that is mounted externally on a back side of the fixed core, and a worm carried by the saddle that meshes collinearly with the rack
Implementation Method 2
The meshing of the worm and rack is such that it is self-locking, so that when the rest bar is mounted in a vertical orientation, and the saddle is unclamped, the saddle will not move down the core without turning the worm
Implementation Method 3
an adjustment mechanism comprising a helically cut rack that is mounted externally on a back side of the fixed core, and a worm carried by the saddle that meshes collinearly with the rack
Data Source
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AI summary
A rest bar assembly (40) for a guide (38) that is employed in a rolling mill (32) to direct a hot rolled product either entering or exiting from the roll pass of a roll stand. The rest bar assembly comprises a core extending transversely with respect to the mill pass line. A saddle (46) is movable along the core and is adapted to carry the guide. An adjustment mechanism serves to move the saddle along the core. The adjustment mechanism comprises a worm rack extending along a back side (42b) of the core, and a rotatable worm carried by the saddle and in meshed relationship with the worm rack.