Lockbolt Collar Cutting for Clean Pin-Safe Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for removing swaged-collar type fasteners, such as lockbolts, are inefficient and often damage the coupled elements or cutting tools due to the flange formation during the cutting process, making it difficult to centralize the cutting implement and achieve a clean cut without damaging the pin or collar.
Innovation Solution
An apparatus with a connection member and moveable cutting members that allow for relative movement to centralize the collar between the cutting members, ensuring balanced cutting forces and minimizing deflection, while an opposing member provides a reaction surface and can assist in cutting from diametrically opposite directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If a cutting implement is used to cut the collar after swaging, then the collar can be removed for maintenance, but the flange formation causes the cutting implement to ramp up or kick, resulting in damaged coupled elements or cutting tools
Solution Approach 1:
The collar is segmented into two parts by making two diametrically opposite cuts simultaneously. This segmentation allows the collar to be divided into two half-collars that can be easily removed without damaging the pin or coupled elements, resolving the contradiction between ease of repair and prevention of damage.
Solution Approach 2:
The opposing member acts as a counterbalance to the moveable cutting member, providing a reaction force that prevents the cutting implement from ramping up or kicking on the flange. This counteracting force eliminates the harmful effects while enabling clean collar removal for maintenance.
2Device complexity
If a single cutting member is used to cut the collar, then the apparatus is simpler, but it is difficult to centralize the cutting implement and achieve a clean cut without damaging the pin or collar
Solution Approach 1:
The cutting function is segmented into two separate cutting members positioned diametrically opposite each other. This segmentation enables precise centralization of the collar between the two cutting members, ensuring clean cuts on both sides simultaneously while maintaining relatively simple apparatus design.
Solution Approach 2:
The apparatus uses asymmetric positioning of the moveable cutting member relative to the opposing member, allowing the moveable cutting member to be precisely positioned and centralized against the collar during operation, thereby achieving high cutting precision without excessive complexity.
3Device complexity
If the collar is cut without simultaneous opposing cuts, then the cutting process is simpler, but the collar cannot be easily removed from the pin after cutting
Solution Approach 1:
The collar is cut into two separate segments by simultaneous diametrically opposite cuts. This segmentation causes the collar to split into two half-collars that can be easily pulled off the pin without requiring additional removal tools or operations, resolving the contradiction between cutting simplicity and ease of collar removal.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Apparatus (2) is disclosed for attaching to a lockbolt via a swaged-mounted collar (18). The apparatus includes an element (40, 42) which permits relative movement between a cutting blade (28) and an opposing surface (32) so that the collar (18) is held centrally within the apparatus during cutting.