Inkjet Head Collision Avoidance via Segmented Actuation
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Solution Overview
Problem
In digital sheet-fed printing machines, existing methods for avoiding collisions between sheets and inkjet heads result in high manual labor and productivity losses due to extended stoppage times, as they require manual removal of defective sheets and cannot maintain continuous operation when lowering the inkjet heads.
Innovation Solution
A method involving continuous monitoring of sheet position and edges using sensors or cameras, with actuator-based sequential raising and lowering of inkjet heads to avoid collisions, allowing continuous operation and minimizing rejects by only raising defective sheets, and using a control system to optimize lifting and lowering movements based on defect size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the inkjet heads are lowered to avoid collisions with defective sheets, then the productivity is improved by avoiding stoppages, but the risk of damage to the inkjet heads increases
Solution Approach 1:
The system performs preliminary detection of defective sheets using sensors before the sheets reach the inkjet heads. By detecting defects in advance (e.g., through sensors positioned upstream), the control system can proactively raise the inkjet heads before collisions occur, preventing damage while maintaining continuous operation and avoiding productivity losses.
2Object-affected harmful factors
If the machine is stopped to remove defective sheets manually, then the inkjet heads are protected from damage, but the productivity decreases due to extended stoppage times
Solution Approach 1:
The system enables automatic protection of inkjet heads through self-service mechanisms. Sensors automatically detect defective sheets, and the control system autonomously raises the inkjet heads to avoid collisions. This eliminates the need for manual intervention and machine stoppages, allowing continuous operation while protecting the inkjet heads from damage.
3Object-affected harmful factors
If all inkjet heads are raised simultaneously to avoid collisions, then the safety is improved, but the productivity is reduced due to complete stoppage
Solution Approach 1:
The system segments the inkjet heads into individually controllable units. Instead of raising all inkjet heads simultaneously, the control system can selectively raise only the specific inkjet heads that pose a collision risk based on real-time sheet position detection. This segmented approach maintains safety while allowing other inkjet heads to continue printing, thereby preserving productivity.
4Object-affected harmful factors
If the transport element is lowered to avoid collisions, then the harmful factors are reduced, but the continuous transport capability is lost
Solution Approach 1:
The system dynamically adjusts the position of inkjet heads based on real-time detection of sheet conditions. The inkjet heads can be raised or lowered on-demand according to the specific situation (e.g., when a defective sheet is detected), rather than permanently lowering the transport element. This dynamic adjustment maintains continuous transport capability while avoiding collisions with defective sheets.
Data Source
AI summary
A method for avoiding collisions in a digital inkjet printing machine, a method and a device for actuator-based lifting movement of inkjet heads. A sensor/camera monitors the sheets as they travel towards the inkjet heads. In order to avoid collisions, the inkjet heads are raised and lowered again individually and in an oscillation-optimized manner when a defective sheet is detected. The machine does not need to be stopped in the event of defective sheets. Advantageously, rejects can thus be reduced and the performance of the machine can be exploited better.