Polyurethane Spray Head Self-Cleaning Mechanism
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Solution Overview
Problem
Existing methods for applying reactive polyurethane to substrates face issues with clogging due to fast-reacting raw material systems, aerosol generation, and the need for complex and costly extraction systems, leading to equipment outlay and raw material losses.
Innovation Solution
A method and device utilizing a cylindrical mixing chamber with a gas stream introduction into a flow channel for mixing and spraying, followed by mechanical cleaning with an axial ejector, which minimizes aerosol production and enables uninterrupted operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-pressure mixers with miniaturized mixing chambers are used for fast-reacting raw material systems, then clogging of the mixing head is reduced, but the system requires complex equipment with multiple mixing heads and frequent cleaning
Solution Approach 1:
The invention extracts the cleaning function from a separate maintenance operation and integrates it into the spray head design itself. A cleaning nozzle is built into the spray head that can be activated to blow out reactive material residues from the mixing chamber and channels, allowing the spray head to clean itself without external intervention or disassembly.
Solution Approach 2:
The spray head performs self-cleaning through the integrated cleaning nozzle system. By activating the cleaning function, the spray head automatically removes its own residues using compressed air or inert gas flow, eliminating the need for external cleaning equipment or manual intervention.
2Speed
If spray mixing heads are made small and lightweight for rapid robot movements, then spray precision and speed are improved, but aerosol generation increases and requires complex extraction systems
Solution Approach 1:
The invention uses pneumatic flow of inert gas or compressed air through the mixing chamber and spray head to control the spraying process. The gas flow carries the reactive material through the mixing chamber and out through the spray nozzle, allowing precise control of spray patterns and minimizing aerosol generation through optimized flow dynamics.
Solution Approach 2:
The invention introduces an inert gas atmosphere into the mixing chamber and spray head to prevent premature reaction of the reactive materials. The inert gas flow also helps contain and control aerosol particles, directing them toward the substrate rather than allowing uncontrolled dispersion into the surrounding environment.
3Productivity
If conventional spray nozzles are used for reactive materials, then spraying capability is achieved, but frequent clogging occurs requiring production interruption for cleaning
Solution Approach 1:
The invention prepares for clogging prevention in advance by integrating a cleaning nozzle system into the spray head design. The cleaning function can be activated before actual clogging occurs during scheduled maintenance intervals or between production batches, preventing residue buildup that would lead to clogging and production interruptions.
Solution Approach 2:
The invention enables continuous operation by making the cleaning function an integral part of the spray head that can be performed without disassembly or production stoppage. The cleaning nozzle can be activated to maintain the spray head in a clean state throughout operation, ensuring continuous productive action without interruption for manual cleaning.
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 solution allows for efficient, uninterrupted production with minimized aerosol content, reduced equipment maintenance, and optimized mixing quality, enabling rapid cycle times and precise application of polyurethane layers without the need for additional spray nozzles.
Implementation Method 1
in the area of the inlet opening a gas stream is additionally fed into the flow channel
Implementation Method 2
the mixing chamber is cleaned mechanically by means of an ejector that can be moved axially in the mixing chamber
Implementation Method 3
both the end face of the ejector and the flow channel are cleaned by the gas flow
Implementation Method 4
the reactive mixture thus produced is then fed through an inlet opening into a flow channel... and hardens thereon
Data Source
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AI summary
The invention relates to a method and a device for producing molded pieces containing a polyurethane layer in an injection operation in which the reactive components are mixed in a cylindrical mixing chamber (10), whereupon the obtained reactive mixture flows through a duct (12), is sprayed onto the surface of a substrate (18), and cures thereupon, and the duct is subsequently cleaned by means of a gas flow.