Drive Control for Elastic Roll Elements in Flexographic Printing
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Solution Overview
Problem
In flexographic printing, elastic deformation of roll elements during contact leads to unpredictable changes in effective radii and linear velocities, causing torque imbalances and resulting in horizontal stripes in printed images, which are difficult to prevent without manual intervention and operator expertise.
Innovation Solution
A method combining speed correction and retrospective control methods to automatically adapt setpoint velocities and correct for deviations in roll element speed consistency by analyzing drive torque curves and applying correction signals, minimizing peripheral velocity differences between roll pairs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manual intervention and operator expertise are used to prevent horizontal stripes, then printing quality is improved, but operator dependency and complexity increase
Solution Approach 1:
The control system automatically detects and compensates for velocity deviations in roll elements without requiring manual intervention. The system monitors the actual velocities of rolls during operation and self-corrects by adjusting drive torques based on detected deviations, eliminating the need for operator expertise in preventing horizontal stripes.
Solution Approach 2:
The system continuously measures actual velocities of roll elements and feeds this information back to the control unit. Based on this feedback, the control unit calculates and applies corrective torques to maintain synchronized velocities, creating a closed-loop control system that automatically prevents printing defects.
2Adaptability or versatility
If elastic deformation of roll elements is allowed during contact, then flexibility and comfort are improved, but velocity consistency deteriorates
Solution Approach 1:
The system dynamically adjusts the setpoint velocities of roll elements based on detected actual velocities. By changing the velocity parameters in real-time according to measured deviations, the system compensates for velocity inconsistencies caused by elastic deformation while maintaining the flexibility benefits of elastic roll elements.
3Force
If torque exchange between rolls is permitted due to elastic deformation, then elastic contact is achieved, but velocity synchronization is compromised
Solution Approach 1:
The control system applies preliminary corrective torques to rolls before velocity deviations significantly affect printing quality. By detecting velocity differences and applying counteracting torques through the drive system, the system prevents torque exchange from causing harmful velocity synchronization errors.
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 method effectively prevents horizontal stripes in printed images by synchronizing roll velocities, reducing torque imbalances, and enhancing printing quality without requiring operator expertise or additional production efforts.
Implementation Method 1
Due to the action of the contact force, a body, which is referred to hereafter in a nonrestrictive manner as a roll element, is elastically deformed when it rolls on a counter surface. The respective effectively acting radius of the roll element changes due to this elastic deformation.
Implementation Method 2
the curve of a value characteristic for a drive torque of the roll arrangement is determined in at least one of the subintervals, a parameter for an increase of this value in the subinterval is derived therefrom
Data Source
AI summary
A method for controlling a drive of a machine having at least one first roll element, which rolls with a surface on a counter surface at least in subintervals of a revolution cycle with the action of a contact force under elastic deformation, that includes a speed correction method, which automatically compensates for deformation-related deviations of the peripheral velocity of the first roll element by way of an adaptation of the setpoint value for the velocity of the first roll element, and a retrospective method, which automatically compensates for deviations of the speed consistency of the first roll element within a revolution cycle by applying a correction signal determined from the curve of a control variable, in particular an actual velocity or actual position of the first roll element, in a preceding revolution cycle or in multiple preceding revolution cycles, are applied in combination.