Digital Printing Web Coil Switching and Splicing
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Solution Overview
Problem
High-speed digital printing systems face challenges in managing continuous web printing with interruptions due to coil fullness, defects, and urgent work orders, leading to downtime and waste of unusable web sections.
Innovation Solution
A high-speed digital printing system with two unwinding machines, an input cutting and splicing equipment, and two rewinding machines, controlled by an electronic unit that automatically switches between reference and switched configurations to manage coil replacement, printing defects, and urgent orders without stopping the printing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If coil replacement is performed manually when a coil is exhausted, then the printing system can switch to a new coil, but the downtime can last up to fifteen minutes affecting 25% of the operating cycle
Solution Approach 1:
The system prepares a standby coil in advance with the web edge manually prepared with adhesive and held on a retaining member. When the operating coil is full, the system can immediately switch to the pre-prepared standby coil without stopping the printing process, eliminating the 15-minute replacement downtime.
Solution Approach 2:
A cutting and splicing unit acts as an intermediary device between the operating coil and the standby coil. It automatically cuts the web from the full coil and splices it to the standby coil, mediating the transition without requiring manual intervention or stopping the printing process.
2Productivity
If sections of empty or defective web are rewound together with printed sections, then the rewinding coil can be fully utilized, but the unusable sections must be removed creating waste and downtime
Solution Approach 1:
The system segments the web into printed sections and unprinted/defective sections, rewinding them separately. The cutting and splicing unit identifies where printing starts and stops, cutting the web to separate usable printed portions from unusable portions, allowing only the printed sections to be rewound and utilized.
Solution Approach 2:
The system discards unprinted or defective web sections at the point where printing stops, rather than rewinding them. The cutting and splicing unit cuts away the unusable portions, recovering only the valuable printed sections for rewinding and subsequent use, eliminating waste of good material.
3Device complexity
If urgent work orders are printed on the operating coil together with scheduled work orders, then additional printing lines are not needed, but the urgent work can only be carried out after complete re-winding of the coils
Solution Approach 1:
The system dynamically manages multiple coils and work orders, allowing flexible assignment of urgent and scheduled work to different coils. The electronic control unit can redirect urgent work to a standby coil while the operating coil completes its current batch, enabling parallel processing and eliminating delays without adding physical printing lines.
Solution Approach 2:
The system maintains continuous printing operation by having multiple coils available. While one coil is being used for scheduled work, another coil can be prepared or is already containing urgent work, ensuring that useful printing action continues without interruption or delay for urgent orders.
4Reliability
If the rewinding coil reaches full condition before completing a given work, then the coil can be replaced, but the work must be printed in two different coils disadvantageously
Solution Approach 1:
When the operating coil reaches full condition, the system extracts the printed web from the coil and transfers it to a standby coil using the cutting and splicing unit. This allows the work to continue on the new coil without interruption, maintaining work integrity while managing coil capacity.
Solution Approach 2:
The system creates a composite printing solution by combining multiple coils into a continuous workflow. The cutting and splicing unit joins webs from different coils seamlessly, allowing a single work order to span across multiple coils as if it were one continuous medium, maintaining adaptability and work integrity.
Data Source
Figure 1
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Figure 3~3a
AI summary
A high-speed digital printing system (24) comprises two unwinding machines (32 and 33) for two input coils (38 and 41) for a paper web (39 and 42), an input unwinding and splicing installation(34) and a printing station (27) and in which the input installation supplies, in turn, the printing station with the web of the two coils. The system (24) also comprises a splicing and rewinding installation (28) with an output cutting and splicing equipment (146) for an incoming web (144) emerging from the printing station and two rewinding machines (148 and 149) with two output coils(151 and 152). The output equipment feeds alternatively the rewinding machines with the incoming web by cutting and splicing of a web (154 and 156) of the two output coils without stopping printing. An electronic controller (153) switches the functionality of the output cutting and splicing equipment (146) and of the rewinding machines (148 and 149 with setting of the output coils (151 and 152) as an operating coil and a waiting coil and, vice versa, as a waiting coil and an operating coil.