Polyurethane Spray Device with Multi-Point Gas Injection
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Solution Overview
Problem
Existing spray systems struggle to produce perfect spray layers on complex molded parts with narrow depressions and undercuts, and often become clogged during shot interruptions, leading to suboptimal surface finish and increased raw material usage.
Innovation Solution
Introducing a gas stream at multiple positions within the flow channel of the spray device, with a specific distance ratio to the channel diameter, ensures the reactive mixture is broken into droplets and transported effectively, preventing clogging and maintaining spray quality even during interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the spray mixing head is miniaturized to enable fast robot movements, then the weight and response time are improved, but the capability to spray three-dimensional layers with narrow depressions and undercuts deteriorates
Solution Approach 1:
The flow channel is divided into multiple sections with gas injection points at different locations, creating segmented zones that work together to atomize and transport the reactive mixture effectively through complex geometries
Solution Approach 2:
Gas streams are introduced into the flow channel to provide pneumatic assistance for atomizing the reactive mixture and transporting spray droplets, enabling the miniaturized head to achieve better spray penetration and coverage in narrow depressions and undercuts
2Productivity
If the spray system operates continuously without interruption, then productivity is improved, but the risk of discharge element clogging with reactive mixture deteriorates
Solution Approach 1:
Gas streams are introduced in advance into the flow channel to prevent reactive mixture from stagnating and clogging the discharge element, maintaining system readiness for immediate resumption of spraying after interruptions
Solution Approach 2:
The gas flow maintains continuous movement of reactive mixture through the flow channel, ensuring that the spray system remains fully functional and ready for immediate operation after any interruption without requiring cleaning or maintenance
3Device complexity
If a single gas injection point is used in the flow channel, then device complexity is reduced, but the effectiveness of droplet formation and transport deteriorates
Solution Approach 1:
The flow channel is divided into multiple sections with gas injection points at different locations, creating segmented zones that work together to atomize and transport the reactive mixture effectively
Solution Approach 2:
Gas injection is extended from a single point to multiple points distributed along the flow channel length, adding a spatial dimension to the gas injection strategy and improving droplet formation and transport efficiency
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 approach allows for precise and efficient application of polyurethane layers on complex surfaces, minimizing raw material use and cycle times, while keeping the spray system clean and functional, enabling flexible spray pattern and mass distribution.
Implementation Method 1
a gas stream is introduced into the flow channel of the spray device at at least two positions... causes the reactive mixture to break up into a stream of spray droplets, but then also causes these spray droplets to be transported through the flow channel
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a method and a device for the production of moulded pieces comprising a layer of polyurethane by spraying, wherein a gas stream is introduced into the flow channel (11) of the spray device (3) in at least two positions.