Rotary Printing Press Roller Speed Control for Print Length
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Solution Overview
Problem
Rotary printing machines face challenges in maintaining consistent print lengths across a web of printing material due to varying web tensions, which can lead to deviations in print lengths, especially when printing on both sides of the material, and are limited in their ability to adjust for non-stretchable materials like paper and aluminum foil.
Innovation Solution
Measuring the print length and adjusting the peripheral speed of the printing roller to match a target length without altering web tension, allowing for precise control of print length without changing the web tension, thus accommodating stretch-resistant materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If web tension is adjusted to correct print length deviations, then print length consistency is improved, but the method is limited for rigid materials like paper and aluminum foil where tension adjustment has virtually no effect
Solution Approach 1:
The invention changes the control parameter from web tension to printing roller circumferential speed. By adjusting the circumferential speed of the printing roller independently from the impression cylinder speed, the system can achieve print length correction that works for all material types including rigid materials like paper and aluminum foil, where tension adjustment is ineffective.
2Length of moving object
If web tension is increased to achieve shorter repeat length, then print length is reduced, but excessive web tension can permanently alter the substrate by causing permanent plastic deformation
Solution Approach 1:
The invention replaces web tension adjustment with printing roller speed adjustment. This allows repeat length to be modified without applying excessive forces to the substrate, thereby preventing permanent plastic deformation and maintaining substrate integrity while achieving the desired print length.
3Length of moving object
If web tension is decreased to achieve longer repeat length, then print length is increased, but web tension cannot be arbitrarily low as a minimum is required to reliably feed the material web through the machine
Solution Approach 1:
The invention decouples repeat length control from web tension by adjusting the printing roller circumferential speed. This allows repeat length to be extended without reducing web tension below the minimum required for reliable material feeding, thus maintaining both print length flexibility and feeding reliability.
4Manufacturing precision
If the peripheral speed of the printing roller is changed to adjust print length, then print length precision is improved, but the peripheral speeds of the printing roller and impression cylinder are no longer the same
Solution Approach 1:
The invention introduces dynamic speed adjustment of the printing roller independent from the impression cylinder. The printing roller's circumferential speed can be varied to achieve precise print length control, while the impression cylinder maintains its speed for reliable substrate feeding. This dynamic decoupling allows both precision and reliability to coexist.
Data Source
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AI summary
The invention relates to a method and to a device for printing a print stock web (7) within a rotary printing press (1). A printed image is applied to the print stock (7) by means of at least one printing roller (5), wherein the printing roller (5) rotates at a circumferential velocity. By means of at least one measuring device (20) arranged within the rotary printing press, a print length is measured and the circumferential velocity of the at least one printing roller (5) is altered if the measured print length deviates from a target print length.