Ribbon Cassette Segmentation for Jam Reduction
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Solution Overview
Problem
Ribbon cassettes in impact printing systems face issues with ribbon jamming due to high ribbon density, leading to increased energy storage and rapid release of folds, which can cause jams at the exit gate, especially when the ribbon pack exceeds a certain limit, resulting in reduced capacity and reliability.
Innovation Solution
The introduction of spherical bumps on the floor and ceiling, along with arched retaining walls, creates distinct zones within the cassette that manage ribbon density and tension, preventing jams by allowing the ribbon to exit unimpeded while maintaining high ribbon capacity, without increasing part count or manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the ribbon pack density is increased to maximize ribbon capacity, then the ribbon length that can be stored increases, but the ribbon tension and energy storage increase causing the ribbon to jam at the exit gate
Solution Approach 1:
The stuff-box area is segmented into multiple zones using retaining walls and guide ribs that create distinct regions for ribbon storage and exit. This segmentation controls ribbon flow by preventing high-density packed ribbon from directly contacting the exit gate, thereby reducing jamming while maintaining high capacity
Solution Approach 2:
Retaining walls and guide ribs act as intermediary structures between the high-density ribbon pack and the exit gate. These intermediaries manage ribbon tension and redirect ribbon flow, allowing high capacity storage while preventing the ribbon from jamming at the exit gate
2Productivity
If the ribbon web is forced through a narrow gate from a high-density stack, then the ribbon can be delivered to the print station, but the ribbon becomes wedged causing excessive tension and jamming
Solution Approach 1:
The guide ribs and retaining walls are positioned to dynamically guide ribbon flow as it transitions from the high-density pack to the exit gate. The structures adapt to ribbon movement, gradually redirecting the ribbon web to reduce wedging and excessive tension during delivery
Solution Approach 2:
The retaining walls and guide ribs extend in multiple dimensions within the stuff-box area, creating a three-dimensional ribbon management system. This dimensional approach allows ribbon to be guided through a controlled path, reducing one-dimensional wedging forces at the exit gate
3Reliability
If retaining walls are placed close to the exit gate to prevent jamming, then ribbon tension is reduced, but the ribbon pack density decreases reducing overall capacity
Solution Approach 1:
Multiple retaining walls are positioned at different locations and distances from the exit gate, creating segmented zones within the stuff-box. This segmentation allows the system to maintain high overall capacity while specific zones near the gate manage tension to prevent jamming
Solution Approach 2:
The retaining walls have varying heights and positions optimized for their specific locations. Walls closer to the exit gate are positioned to manage tension and prevent jamming, while walls farther away allow for higher density storage, creating local quality variations that optimize both capacity and reliability
Data Source
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AI summary
In one embodiment, a ribbon cassette includes two rows of spherical bumps extending between sidewalls of the cassette on both a floor and ceiling of the cassette and a pair of concentric arched retaining walls on both the floor and ceiling between an exit gate and the rows of bumps. In another embodiment, there is only one row of bumps and one retaining wall on the floor and ceiling. In another embodiment, the retaining walls are straight. The two rows and retaining walls, along with cassette sidewalls, form three distinct zones for densely packing the ribbon, unpacking the ribbon, and isolating the ribbon, resulting in less jamming with longer lengths of ribbon.