Expandable Foam Injection Head with Rotary Anti-Seize Control
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Solution Overview
Problem
Existing injection heads for polyurethane foams face issues with cured foam residue obstructing passages and causing rod seizure, requiring frequent maintenance due to inefficient cleaning solutions.
Innovation Solution
An injection head design featuring a guiding cage with helical grooves and guide pins that impose a rotary motion to the shutter stem, preventing surface adhesion and facilitating the unblocking of polyurethane residue during the shutter's sliding movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the control rod is moved to a forward position to close the inlet ports, then the injection nozzle is cleaned of residing residual components, but cured foam residue remains and obstructs passages, leading to rod seizure
Solution Approach 1:
The invention transforms the static sliding motion of the control rod into a dynamic rototranslational motion by introducing a guiding cage with helical grooves. The control rod simultaneously slides along the longitudinal axis and rotates about it, creating a complex motion that prevents foam adhesion and effectively removes residue from the injection nozzle and mixing duct.
Solution Approach 2:
The helical grooves in the guiding cage introduce a curved, rotational path to the control rod's motion. This curved motion pattern prevents the control rod from sticking to the injection nozzle surfaces by continuously changing the contact orientation, thereby preventing foam adhesion and residue accumulation.
2Productivity
If longitudinal sliding motion is used to remove fouling, then some cleaning is achieved, but cleaning efficiency is low and seizure problems occur
Solution Approach 1:
The invention upgrades the simple longitudinal sliding motion to a dynamic rototranslational motion through the guiding cage mechanism. The control rod performs both sliding and rotational movements, which significantly enhances cleaning efficiency by mechanically scraping residue from surfaces while preventing adhesion through the rotational component.
Solution Approach 2:
The guiding cage structure is pre-configured with helical grooves that automatically impart rotational motion to the control rod during its sliding operation. This preliminary mechanical design ensures that the rototranslational motion occurs naturally during normal operation, preventing foam adhesion before it can cause seizure problems.
Data Source
AI summary
An injection head (1) for making hardening foams is disclosed, including a housing in which are housed an inflow and mixing body (5) equipped with a central supply duct connected to an injection nozzle (6) and a plurality of supply ducts (5a) of fluid components to be mixed converging on said central supply duct, and a shutter stem (3, 30) mounted sliding longitudinally at least partially in said central supply duct and injection nozzle (6) according to an alternating forward and backward movement which respectively closes and opens inflow ports of said supply ducts (5a) in said central supply duct, further including a guiding cage (7) arranged around said plug stem (3, 30) arranged to guide said shutter stem (3, 30) according to a rotation on its longitudinal axial upon said longitudinal sliding.