Offset Printhead Nozzle Spacing for Coating Uniformity
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Solution Overview
Problem
Existing drop-on-demand printheads have a minimum nozzle distance limited by the diameter of the actuators, leading to coating agent droplets being too far apart to form a coherent film on a component surface, necessitating the rotation of the printhead to reduce the effective nozzle distance.
Innovation Solution
The printhead design allows for a nozzle distance smaller than the outer dimension of the actuators by offsetting the control valves and actuators, enabling spatial pulling-apart and connecting nozzles to control valves via flow channels, reducing the nozzle distance without altering the external dimensions of the actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If actuators are arranged along the nozzle row with their outer dimension limiting the minimum distance, then the structural simplicity is maintained, but the nozzle distance becomes too large to form a coherent coating film
Solution Approach 1:
The control valves are arranged in a second row offset from the nozzle row, transitioning from a one-dimensional linear arrangement to a two-dimensional spatial configuration. This allows the nozzle distance to be reduced independently of the actuator diameter, as the actuators can be positioned above or below the nozzle row rather than being constrained to a linear sequence along it.
Solution Approach 2:
The control system is segmented into separate control valves arranged in a second row, decoupling the control function from the nozzle arrangement. This segmentation allows independent optimization of nozzle spacing and actuator positioning, enabling smaller nozzle distances without increasing actuator size.
2Manufacturing precision
If the printhead is rotated to reduce effective nozzle distance, then coating droplets can form a continuous film, but the device complexity increases and coating uniformity may be compromised
Solution Approach 1:
Instead of rotating the printhead in three-dimensional space, the patent uses a two-dimensional offset arrangement of control valves in a second row. This eliminates the need for rotation while achieving the same effect of reducing effective nozzle distance, thereby maintaining coating uniformity without adding rotational complexity.
Solution Approach 2:
The control valves are extracted from the nozzle row and arranged in a separate second row. This extraction allows the nozzle row to be optimized for coating quality without the constraint of actuator positioning, eliminating the need for printhead rotation and maintaining coating uniformity.
3Manufacturing precision
If control valves are offset from the nozzle row, then nozzle distance can be reduced below actuator diameter, but the flow channel length increases
Solution Approach 1:
The flow channels are designed to connect nozzles in the first row to control valves in a second row through a two-dimensional spatial path. By offsetting the control valves laterally and positioning them in a separate row, the flow channel length is managed through optimized routing that leverages the vertical and lateral dimensions rather than simply extending the horizontal path.
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 design allows for a closer packing of nozzles, enabling the formation of a continuous coating film without the need for printhead rotation, while maintaining uniform coating agent delivery through pressure compensating means.
Implementation Method 1
The individual nozzles (22-28) are connected via flow channels (45-51) with control valves (31-41)
Implementation Method 2
The control valves (31-41) are controlled by actuators (35-44), whereby the actuators (35-44) each move a valve membrane (67)
Implementation Method 3
the valve membrane (67) is deflected by a valve stem (69) which can be moved by an actuator in the direction of the double arrow. In a closed position, the valve stem (69) presses the valve membrane (67) onto the valve seat (64) and thus seals it
Implementation Method 4
Pressure compensating means (59) are arranged in the shorter flow channels (58), so that the different nozzles (22-28) have a uniform discharge behaviour
Data Source
AI summary
The disclosure relates to an applicator, in particular a printhead, for applying a coating agent, in particular a paint, to a component, in particular a motor vehicle body component or an add-on part for a motor vehicle body component, having at least one nozzle row with a plurality of nozzles for dispensing the coating agent in the form of a coating agent jet, the nozzles are arranged one behind the other in a nozzle plane along the nozzle row at a specific nozzle spacing, and having a plurality of actuators for controlling the release of coating agent through the individual nozzles, the actuators each having an outer dimension along the nozzle row. The disclosure provides that the nozzle distance between the adjacent nozzles of the nozzle row is smaller than the outer dimension of the individual actuators along the nozzle row.