Sheet Deceleration via Deflected Trailing Edges
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Solution Overview
Problem
Existing cross-cutting machines face challenges in safely decelerating sheets from high speeds to a lower deposition speed without causing disturbances or marking issues during stacking.
Innovation Solution
The implementation of rotatingly drivable clamping elements with clamping zones and a deflection device, such as a suction box, allows for controlled deceleration of sheets by deflecting trailing edges downwards, providing sufficient braking time and preventing slipping or marking, using a non-uniform rotary drive and CFRP components for efficient deceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If sheets are decelerated using conventional clamping elements without deflection device, then braking function is provided, but braking time is insufficient and following sheets cannot approach closely enough
Solution Approach 1:
The deflection device bends the trailing edge of the sheet downward out of the infeed plane, creating a vertical dimension separation. This allows the following sheet to approach horizontally while the preceding sheet is being braked vertically at the trailing edge, effectively extending the braking time without reducing productivity.
2Duration of action of moving object
If clamping zones reach far into infeed plane to increase braking time, then braking time increases, but following sheet cannot move forward unbraked and stacking is disturbed
Solution Approach 1:
By deflecting the trailing edge downward in the vertical dimension, the clamping zones can extend further into the infeed plane horizontally without interfering with the following sheet's forward movement. The spatial separation in vertical dimension allows both sheets to coexist without stacking disturbances.
Solution Approach 2:
The braking action is localized to the trailing edge region through the deflection device, separating the braking function from the overall sheet transport. This segmentation allows the following sheet to move forward unbraked while the preceding sheet undergoes braking at its trailing edge.
3Productivity
If high infeed speed is maintained for productivity, then productivity is high, but sheets cannot be decelerated safely without marking or jamming
Solution Approach 1:
The deflection device preliminarily positions the trailing edge downward before the clamping zones engage, creating optimal conditions for braking. This preliminary action ensures that when high-speed braking occurs, the sheet is properly positioned to prevent marking and jamming while maintaining high productivity.
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
This solution enables safe and mark-free deceleration of sheets from 400 m/min to 80 m/min, facilitating an imbricated stream for smooth stacking without jamming or marking issues.
Implementation Method 1
A device for deflecting sheet trailing edges downwards is preferably a cyclically switched suction box with suction openings on the upper side, which sucks in the sheet trailing edges arranged below the infeed plane of the sheets and thus moves them downwards.
Implementation Method 2
The clamping elements are connected to a non-uniform rotary drive, by which the peripheral speed of the clamping zones changes during one revolution of the clamping zones.
Data Source
Figure 1
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AI summary
The invention relates to an apparatus for decelerating sheets (9), especially paper or cardboard sheets, which are to be placed on a stack (6). Said apparatus comprises rotatably driven clamping elements (16) which are disposed across the width of the apparatus on at least one side of the conveying plane of the sheets (9) and are provided with clamping zones (17) that intermittently reach all the way to the feeding plane of the sheet (9) when revolving. The inventive apparatus further comprises a mating element (18) which is rotationally disposed on the opposite side of the conveying plane of the sheets (9) such that a sheet can be clamped between the clamping zones (17) and the mating element (18). The clamping elements (16) are connected to an asymmetrical rotary drive unit while being equipped with ring segment-shaped clamping zones (17) on a section of the circumference thereof. Furthermore, a deflecting device (13) which deflects the rear edges of the sheet from the feeding plane in a downward direction is arranged at a distance from and upstream of the clamping elements (16) in the direction of travel of the sheets.