Printing Drum Vacuum Insert Sliding Mechanism
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Solution Overview
Problem
Existing printing devices for producing identity and security documents face challenges in reliably and distortion-free fixing and transporting sheet-like substrates, as they often rely on either mechanical gripping elements or vacuum fixation, which are inadequate for ensuring precise image quality and efficient processing.
Innovation Solution
A drum with a vacuum fixing device featuring a sliding vacuum insert accommodated in a recess, supported by a spring for tensioning, and actuated by an eccentric mechanism, which allows for secure clamping of the substrate on the drum's lateral surface, combining mechanical and vacuum fixation for improved image quality and distortion-free handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only mechanical gripping elements are used to fix the substrate, then the structure is simple, but the substrate may deform or fail to attach reliably
Solution Approach 1:
The patent combines mechanical gripping elements with a vacuum fixing device into a unified system. The mechanical grippers provide initial substrate capture and positioning, while the vacuum device maintains reliable attachment during transport. This merging of mechanical and pneumatic systems resolves the contradiction by achieving high reliability without excessive complexity, as the two methods complement each other's strengths.
Solution Approach 2:
The vacuum fixing device acts as an intermediary between the mechanical grippers and the substrate. While mechanical elements provide initial capture, the vacuum field serves as a mediating force that distributes pressure evenly across the substrate surface, preventing deformation and ensuring reliable attachment during the printing process.
2Reliability
If only vacuum fixation is used to fix the substrate, then the substrate remains flat, but the gripping force may be insufficient for secure attachment
Solution Approach 1:
The patent merges vacuum fixation with mechanical gripping elements to achieve both secure attachment and substrate flatness. The vacuum provides distributed holding force that keeps the substrate flat, while mechanical grippers concentrate force at specific points to ensure secure attachment. This combination resolves the contradiction by leveraging the complementary advantages of both fixation methods.
3Adaptability or versatility
If the drum uses a fixed vacuum system, then the setup is simple, but it cannot adapt to different substrate types or printing requirements
Solution Approach 1:
The patent implements a dynamic vacuum system where the vacuum insert can be moved radially along the drum surface and positioned at different locations. This dynamic positioning capability allows the system to adapt to different substrate types, sizes, and printing requirements. The mechanical-vacuum combination can be adjusted independently, providing versatility without requiring complete system redesign for different applications.
4Manufacturing precision
If mechanical grippers are used alone, then the device is simple, but the substrate may experience distortion during transport
Solution Approach 1:
The patent combines mechanical grippers with vacuum fixation to prevent substrate distortion during transport. The mechanical elements provide initial capture and positioning, while the vacuum field distributes holding force evenly across the substrate surface, preventing bending or warping. This merged system achieves high transport precision without excessive complexity by leveraging the complementary strengths of both fixation methods.
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 solution enables reliable, distortion-free fixing and transportation of sheet-like substrates, enhancing the quality of printed images and reducing cycle times by ensuring secure attachment and smooth processing, particularly in the production of documents like passports.
Implementation Method 1
a vacuum fixing device for temporarily fixing a second substrate area of the arc-shaped substrate to the drum shell by means of a vacuum
Implementation Method 2
the at least one vacuum insert is supported or acted upon by a spring, and if the spring is designed to exert a restoring force on the vacuum insert in a direction opposite to the direction of rotation of the drum shell
Implementation Method 3
the at least one vacuum insert is adjusted by means of an actuator, in particular by means of an eccentric, so that the at least one vacuum insert can be concentrically adjusted with respect to the longitudinal axis of the drum
Data Source
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AI summary
The invention relates to a drum (202A, 202B) for a printing device (200) for printing an arc-shaped substrate (300), with a drum shell that can be rotated about a longitudinal drum axis (204) and which has a shell surface (206) on which at least one arc-shaped substrate (300) can be fixed at least partially, with a first fixing device for temporarily fixing a first substrate area (302) of the arc-shaped substrate (300) to the drum shell, and with a vacuum fixing device (210) for temporarily fixing a second substrate area (304) of the arc-shaped substrate (300) to the drum shell by means of a vacuum.The vacuum fixing device (210) comprises at least one vacuum insert (240) received in a recess of the drum shell, which is slidably mounted concentrically with respect to the longitudinal axis (204) of the drum along the shell surface (206) between two stops, and which temporarily provides a vacuum on its side of the shell surface (206) for fixing the second substrate area (304). The invention also relates to a pressure device (200) and a method for temporarily fixing an arc-shaped substrate (300) to a drum (202A, 202B).