Web Folding System for Flat Signatures in High-Speed Book Manufacturing
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Solution Overview
Problem
Current methods for folding paper in manufacturing printed products, such as buckle folders, plow folders, and knife folders, fail to produce flat signatures efficiently at high speeds, especially when dealing with multiple formats and varying cut lengths, and often require additional steps or waste paper due to limitations in perforation and format changes.
Innovation Solution
A method and system that involves sequentially printing a web of material, transversely cutting it into individual sheets, and longitudinally folding them along one or two weakening lines extending parallel to the web's longitudinal direction, allowing for flexible folding configurations and on-the-fly changes while maintaining a flat signature, which can be efficiently bound and trimmed to form books of different sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a buckle folder with parallel fold is used to enable perforation before or after cutting, then the folding speed can be increased, but the paper has to change direction before folding which cannot keep up with the speed of the highest speed printers
Solution Approach 1:
Instead of changing the paper direction before folding as in conventional buckle folders, the invention maintains the paper flow direction and performs folding in the same direction as paper conveyance. The folding unit folds the paper web along the direction of paper flow, eliminating the need for direction change and enabling synchronization with high-speed printers.
2Productivity
If a plow folder is used to enable in-line perforation before cutting, then high speed folding is achieved, but the folder must stop and reset to change paper size making on-the-fly changes impossible
Solution Approach 1:
The invention employs a dynamic folding system where the folding unit can be repositioned along the paper web to accommodate different paper sizes and formats. The folding unit's position and configuration can be adjusted without stopping the paper flow, enabling on-the-fly format changes while maintaining high-speed operation.
3Ease of manufacture
If a buckle folder with initial fold across paper flow is used, then folding can be performed, but the signature cannot be made flat and additional steps are required
Solution Approach 1:
The invention performs preliminary perforation along the folding line before the folding operation. This preliminary action creates a weakening line that guides the fold and ensures the signature folds flat without requiring additional post-folding steps to achieve flatness.
4Ease of manufacture
If perforation is performed across the web before the initial fold in a buckle folder, then the fold can be made, but the paper stack is not as flat and the process is uneconomical
Solution Approach 1:
The invention performs preliminary perforation along the folding line in the direction of paper flow before folding. This approach creates an accurate folding line that ensures flat signatures, eliminates the need for additional steps, and reduces paper waste by optimizing the folding process.
Data Source
Figure 1
Figure 2a~2c
AI summary
For manufacturing books having different sizes and comprising a plurality of text pages constituting a book block, a web of material having a given width is sequentially printed in a digital printing station. The printed web of material is then provided either with one weakening line extending parallel to the longitudinal direction of the web of material or with two weakening lines arranged spaced apart and extending parallel to the longitudinal direction of the web of material. Thereafter the printed web of material is transversely cut to produce individual text sheets which are provided with either one weakening line or two weakening lines. These text sheets are then longitudinally folded along the either one weakening line or in sequence along each of the two weakening lines. The folded text sheets belonging to a particular book block are stacked to a stack. The stacks are either temporarily stored for a later binding process or directly supplied to a binding station.