Vacuum-Drawn Cover Layer for Reinforced Flexible Hose
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Solution Overview
Problem
Existing methods for manufacturing flexible hoses require high vacuum pressures and excessive material to cover the reinforcing layers, leading to inefficiencies and aesthetic issues, such as material accumulation in uncovered areas and potential damage during the extrusion process.
Innovation Solution
A production line with a final extruding station using a telescopically coupled extruding die with a central bore under vacuum, allowing for the precise extrusion of a thin tubular film that uniformly covers both the reinforcing yarns and uncovered portions of the inner layer, reducing material waste and improving aesthetic appeal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high vacuum pressure is applied to draw the annular member towards the semifinished hose, then the cover layer adheres well to the reinforcing layers, but excessive material is used to fill gaps and material cost increases
Solution Approach 1:
The patent applies local quality by creating different surface characteristics in different areas. The reinforcing layers are positioned to create uncovered portions on the inner layer, and the cover layer is designed to uniformly cover both the yarns and these uncovered portions without requiring excessive material, achieving proper adhesion locally where needed while avoiding waste in other areas
Solution Approach 2:
The patent changes the vacuum pressure parameter from the conventional high vacuum (70-80 mmHg or less) to a lower vacuum level (higher absolute pressure of 200-700 mmHg). This parameter change allows the cover layer to be drawn onto the hose without requiring excessive material to fill gaps, thereby reducing material usage while maintaining adequate adhesion
2Reliability
If high vacuum pressure is used to extrude the cover layer, then the cover layer fills all gaps on the semifinished hose, but the hose aesthetic appeal deteriorates due to material accumulation
Solution Approach 1:
The patent creates a uniform cover layer that provides complete coverage of gaps and uncovered portions without creating visible accumulations or irregularities. The cover layer is designed to conform to the underlying structure while maintaining a smooth, aesthetically pleasing surface appearance
Solution Approach 2:
By changing the vacuum pressure parameter to a lower level (200-700 mmHg absolute pressure), the patent achieves complete gap coverage without the material accumulation that occurs at higher vacuum levels, thereby maintaining aesthetic appeal while ensuring proper coverage
3Reliability
If conventional extruding die is used with high vacuum, then the cover layer is drawn towards the semifinished hose, but the manufacturing cost increases due to excessive material usage
Solution Approach 1:
The patent changes the vacuum pressure parameter from conventional high vacuum (70-80 mmHg or less) to a lower vacuum level (200-700 mmHg absolute pressure). This parameter change reduces material usage by approximately 30% while maintaining adequate adhesion and coverage, thereby reducing manufacturing costs
Solution Approach 2:
The patent optimizes the distribution of cover layer material to provide adequate coverage only where needed - on the reinforcing layers and uncovered portions of the inner layer - rather than uniformly thick coverage everywhere, thereby reducing overall material usage and cost
4Reliability
If high vacuum is applied during extrusion, then the annular member is drawn onto the hose, but the extrusion process becomes less efficient due to material waste
Solution Approach 1:
By changing the vacuum pressure parameter to a lower level (200-700 mmHg absolute pressure), the patent improves manufacturing efficiency by reducing material waste by approximately 30%. This reduces the amount of material that needs to be extruded and handled, thereby improving productivity while maintaining adequate cover layer application quality
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 method achieves efficient and cost-effective hose manufacturing with a thinner, uniformly applied cover layer that maintains burst pressure resistance while reducing material usage and enhancing the hose's aesthetic appeal by allowing higher linear forwarding speeds and lower material costs.
Implementation Method 1
a central bore (34) susceptible to be put under vacuum by a vacuum pump (50), in such a manner to draw the tubular film in close contact with the semifinished hose (125)
Data Source
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AI summary
A method for continuously manufacturing a reinforced flexible hose (100), in particular a garden hose, comprising the steps of providing a semifinished hose (125) including at least one inner layer (110) and at least one textile reinforcing layer (120) wound on the outer surface thereof and extruding a thermoplastic polymer material onto the semifinished hose (125) to form a cover layer (130). The extruding step is accomplished by an extruding die (31) having a central bore (34) defining a forwarding axis (X) for housing the semifinished hose (125) and a peripheral channel (35) including a slanted tubular portion (42') and a substantially horizontal tubular portion (42") in correspondence of the outlet (37) thereof. The extruding step is accomplished by putting the central bore (34) under vacuum to draw the cover layer (130) in close contact with the semifinished hose (125). The thickness (T) of the extruded tubular film (130) is of 0,05 mm to 0,35 mm. The absolute pressure in the central bore (34) is no lower than 250 mmHg. The invention also relates to a production line and an extruding station to perform the method, as well as to a hose obtainable thereby.