Threaded Two-Piece Dragline Bushing for Fast Field Replacement
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Solution Overview
Problem
The existing methods for attaching bushings to dragline bucket rigging links, such as welding or pressing, are time-consuming and costly, requiring specialized equipment and causing production downtime, and are bothersome due to smoke generation or need for expensive cooling methods.
Innovation Solution
A two-piece bushing assembly comprising a flanged bushing with external threads and a retaining ring with internal threads, along with a tool for easy attachment and detachment, allowing for quick and efficient installation without the need for welding or pressing, using a rigging link with a tang portion and pocket anti-rotation feature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding is used to attach the bushing to the rigging link, then the bushing attachment strength is improved, but the installation time and cost increase significantly
Solution Approach 1:
The bushing assembly is divided into two separate pieces: the bushing body and the retaining ring. This segmentation allows the bushing to be installed without welding by using the retaining ring to secure it in place, dramatically reducing installation time while maintaining attachment strength through the threaded connection mechanism.
Solution Approach 2:
The welding process (thermal/mechanical system) is replaced with a mechanical fastening system consisting of external threads on the bushing and internal threads in the retaining ring. This substitution eliminates the need for welding equipment and reduces installation time while providing sufficient attachment strength for the application.
2Strength
If welding is used to attach the bushing, then the bushing attachment strength is improved, but the complexity and cost of equipment increase
Solution Approach 1:
By segmenting the bushing assembly into a bushing body and a separate retaining ring with threaded connections, the design eliminates the need for welding equipment. The mechanical fastening system uses simple, standard components that reduce overall system complexity and equipment requirements.
Solution Approach 2:
The complex welding system (requiring welding machines, safety equipment, and skilled operators) is replaced with a simple mechanical threading system. The external and internal threads provide a straightforward assembly mechanism that eliminates expensive and complex welding equipment while maintaining adequate attachment strength.
3Loss of time
If the bushing is pressed into the bore, then the installation time is reduced, but the need for specialized cooling equipment increases
Solution Approach 1:
The bushing assembly is segmented into a bushing body and a retaining ring, allowing the bushing to be installed without the need for thermal shrinking or cooling equipment. The retaining ring secures the bushing through threaded engagement, eliminating the requirement for liquid nitrogen or other cooling systems.
Solution Approach 2:
The thermal shrinking process (requiring liquid nitrogen or cooling equipment) is replaced with a mechanical threading system. The external threads on the bushing engage with internal threads in the retaining ring, providing a simple mechanical fastening method that eliminates the need for expensive and complex cooling equipment.
4Strength
If welding is used to attach the bushing, then the bushing attachment strength is improved, but harmful smoke is generated affecting the work area
Solution Approach 1:
The welding process that generates harmful smoke is replaced with a mechanical threading system. The external threads on the bushing engage with internal threads in the retaining ring through a cold-forming process that produces no smoke or harmful emissions, eliminating the air quality issues associated with welding while maintaining adequate attachment strength.
Solution Approach 2:
The harmful welding process is extracted and removed from the assembly process. Instead of using welding to attach the bushing, the design uses a separate retaining ring with threaded connections, completely eliminating the source of harmful smoke and improving work area air quality.
Data Source
AI summary
A bushing assembly comprises a flanged bushing including a flange portion including a flange anti-rotation feature, and a shaft portion with an outer cylindrical surface extending from the flange portion, terminating at a free end, the outer cylindrical surface including external threads disposed proximate the free end, and a retaining ring including an annular configuration defining an inner cylindrical surface defining internal threads complimentarily shaped to mate with the external threads of the outer cylindrical surface.