Conformal Coating Applicator Valve Stem Damping
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Solution Overview
Problem
Conventional conformal coating applicators experience disruptions in liquid flow due to rebounding movement of the valve stem upon impact with the hard stop element, resulting in an undesirable 'hammer head' or wider shape at the leading edge of the coating film, especially with faster actuation valves.
Innovation Solution
Incorporating a resilient dampening element, such as an elastomeric material, between the valve stem and the hard stop element to provide a biasing force that reduces or eliminates rebounding movement, ensuring a cleaner and sharper leading edge of the applied coating pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If faster actuation valves are used to increase machine speed, then productivity is improved, but rebounding movement occurs causing disruptions in liquid flow pattern
Solution Approach 1:
A resilient dampening element is positioned between the valve stem and the hard stop element to absorb impact energy before the valve stem can rebound. This cushioning element is compressed during the opening stroke and expands during the closing stroke, preventing the rebounding movement that causes hammer head defects while allowing fast actuation speeds to be maintained.
2Length of moving object
If the valve stem impacts against the hard stop element, then the valve stem travel distance is limited, but rebounding movement causes a wider leading edge shape
Solution Approach 1:
The resilient dampening element is positioned to be compressed by the valve stem before the valve seat fully closes. This pre-compression absorbs the impact energy and prevents rebounding, ensuring the valve stem comes to a smooth stop without creating the hammer head effect that widens the leading edge of the coating pattern.
Solution Approach 2:
The resilient dampening element changes the mechanical parameters of the valve system by introducing compliance and damping. This transforms the rigid impact-closure mechanism into a controlled compression-expansion cycle, maintaining precise stroke length while eliminating the rebounding motion that distorts the coating shape.
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
The use of a resilient dampening element ensures a more uniform and precise application of conformal coatings by minimizing disruptions in the flow pattern, resulting in a sharper leading edge and improved coating consistency.
Implementation Method 1
A resilient dampening element is operatively coupled between the body assembly and the valve stem. The resilient dampening element provides a biasing force against the valve stem as the valve stem moves from the closed position to the open position.
Implementation Method 2
The resilient dampening element provides a biasing force against the valve stem as the valve stem moves from the closed position to the open position. This eliminates, or at least reduces rebounding movement of the valve stem toward the closed position
Data Source
AI summary
An applicator for dispensing a liquid conformal coating material onto a substrate. The applicator includes a body assembly with a liquid flow passage having a liquid inlet adapted to receive the coating material and a liquid outlet. A valve seat is positioned between the liquid flow passage and the liquid outlet. A valve stem is mounted in the body assembly for reciprocating movement between an open position and a closed position. The valve stem includes a first end and a second end. The first end of the valve stem engages the valve seat in the closed position to stop flow of the liquid coating material through the outlet and disengages from the valve seat in the open position to allow flow of the liquid coating material through the outlet. A valve actuating mechanism is operative to move the valve stem from the open position to the closed position and is further operative to move the valve stem from the closed position to the open position. A resilient dampening element is operatively coupled between part of the body assembly and the valve stem. The resilient dampening element provides a biasing force against the valve stem as the valve stem moves from the closed position to the open position to reduce rebounding movement of the valve stem toward the closed position.