Counter-Rotating Shredder Roller Strippers for Polymer Banknote Jamming
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Solution Overview
Problem
Existing shredding apparatus for value documents, such as banknotes, suffer from incomplete removal of shreds, interlocking issues, and the formation of 'shredder beards' which require frequent manual intervention, especially when shredding polymer banknotes.
Innovation Solution
The apparatus features counter-rotatable roller-shaped cutting devices with strategically positioned stationary stripper elements that engage cutting edges on the front side but not the back, creating sufficient space for unstripped shreds to be removed, and a suction device to prevent jamming and facilitate the removal of remaining shreds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a stripper is used to remove shreds from cutting edges, then shred removal is improved, but shreds remain hanging between cutting edges and interlocking occurs
Solution Approach 1:
The stripper is divided into multiple stripper elements (at least two) that are distributed around the circumference of the cutting device. Each stripper element is responsible for removing shreds from a specific sector, allowing comprehensive coverage of the cutting edge perimeter and preventing shreds from remaining in any zone.
Solution Approach 2:
The stripper elements are arranged not only axially but also radially and circumferentially around the cutting device. This three-dimensional arrangement ensures that stripper elements engage cutting edges at multiple points and positions, completely clearing shreds from all areas of the cutting perimeter.
2Ease of operation
If stripper elements engage cutting edges on both front and back sides, then shred removal is improved, but space for unstripped shreds is reduced causing jamming
Solution Approach 1:
The stripper elements are configured with asymmetric engagement: they actively engage and remove shreds from the front side of the cutting edges where material is fed, while deliberately leaving the back side unengaged. This localized differentiation allows shreds to be removed from the critical cutting zone while maintaining space behind for any unstripped shreds to pass through without jamming.
3Productivity
If cutting devices rotate at high speed, then productivity is improved, but shred removal completeness deteriorates
Solution Approach 1:
The stripper elements are positioned to engage the cutting edges before the shreds fully form or detach during the cutting rotation. By performing the removal action in advance, while the cutting device is still rotating at high speed, the system ensures complete shred clearance without requiring speed reduction. The stripper elements continuously clear shreds throughout the rotation cycle.
Data Source
AI summary
A shredding apparatus for value documents, includes two mutually counter-rotatable roller-shaped cutting devices which are disposed opposite each other with reference to a transport path of the value documents to be shredded, in order to cut up the value documents transported along the transport path with the aid of the cutting edges into a multiplicity of value document shreds. A stripper is allocated to each of the cutting devices, which stripper has several stripper elements arranged parallel to each other, which stripper elements engage between the cutting edges of the respective cutting device in order to remove the value document shreds from the cutting edges. The shape of the stripper elements is chosen such that the stripper elements on the front side of the respective cutting device, the front side facing the transport path of the value documents, engage between the cutting edges of the respective cutting device.