Flexographic Print Deck Bearing Preload for Print Bounce Control
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Solution Overview
Problem
Flexographic printing presses face issues with print bounce and banding due to mandrel movement and torque spikes, which are not fully addressed by stiffening mandrel roll bodies with composite materials, and are exacerbated by internal clearances in mandrel support bearings.
Innovation Solution
Implementing two adjacent mandrel bearings with radial loading in opposite directions, adjustable via lever or spring actuators, to increase mandrel stiffness, and using a torque feed-forward control system to minimize disturbances caused by print bounce.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If internal clearances are provided in mandrel support bearings to allow side shifting and bearing removal, then ease of operation is improved, but mandrel stability deteriorates causing print bounce and banding
Solution Approach 1:
The bearing support is divided into two separate bearings instead of a single bearing with internal clearance. Each bearing is preloaded in opposite directions, eliminating the need for internal clearance while maintaining mandrel stability and enabling side shifting through coordinated bearing movement.
Solution Approach 2:
The bearing configuration changes from a single bearing with internal clearance to two preloaded bearings with opposite radial loads. This parameter change eliminates backlash and increases mandrel stiffness while maintaining the ability to shift the mandrel for printing operations.
2Strength
If composite materials are used to stiffen mandrel roll bodies, then mandrel stiffness is improved, but print bounce and banding are not completely eliminated
Solution Approach 1:
Two preloaded bearings act as intermediaries between the mandrel and the bearing support carriage. These bearings eliminate backlash and provide stable support that complements the composite mandrel stiffness, together eliminating print bounce and banding that neither solution could achieve alone.
3Ease of manufacture
If single front bearing or two front bearings are used in rigid common bore, then manufacturing simplicity is improved, but mandrel stability deteriorates due to required internal clearances
Solution Approach 1:
The bearing assembly is segmented into two separate bearings mounted in the bearing support carriage rather than a single bearing or two bearings in a rigid common bore. This segmentation eliminates the need for internal clearances while maintaining manufacturing feasibility through standardized bearing components.
Data Source
AI summary
A device and a method is disclosed to maintain plate and anilox mandrel position stability in print decks of a flexographic printing press. In one aspect, the mandrel bearings associated with at least one of the plate roll and the anilox roll are preloaded for the purpose of eliminating backlash and increasing the positional stiffness of the bearings, and thus the mandrel. In another aspect, the roll drive motor control system is enabled to provide a torque additive command the torque profile to maintain rotational consistency and otherwise overcome torque transients experienced by the motor during print bounce. Accordingly, the problem commonly referred to as print bounce and or print banding is alleviated.