Movable Vacuum Nozzle for Internal Thread Coating
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Solution Overview
Problem
Existing methods for applying thermoplastic powder coatings to internally threaded fasteners often result in powder contamination of external surfaces, leading to fouling and welding issues, and lack the ability to selectively coat chamfers.
Innovation Solution
A spray nozzle assembly with a vacuum nozzle system that allows for precise control over the application of thermoplastic powder, preventing external contamination by aligning the spray and vacuum nozzles to ensure the powder only coats internal threads and optional chamfers, using a machined bushing and compression spring to maintain alignment and seal during the coating process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a fixed vacuum nozzle is positioned above the nut to collect over-sprayed powder, then powder can be collected, but the chamfers cannot be coated while keeping the outside surfaces clean
Solution Approach 1:
The vacuum nozzle is made movable rather than fixed, allowing it to be positioned dynamically during the coating process. The nozzle moves to align with the bore opening during coating operations and can be repositioned for chamfer coating, enabling both powder collection and precise chamfer coating control.
Solution Approach 2:
The coating process is segmented into distinct phases: internal thread coating with the vacuum nozzle positioned to collect powder, and chamfer coating with the vacuum nozzle repositioned. This segmentation allows each operation to be optimized independently, solving the contradiction between powder collection and chamfer coating control.
2Reliability
If thermoplastic powder is applied to internal threads including chamfers, then thread protection is improved, but external surfaces become contaminated
Solution Approach 1:
The harmful effect of powder contamination on external surfaces is extracted and eliminated by using the movable vacuum nozzle to selectively collect powder only where needed. The nozzle is positioned to collect powder during internal thread coating but is repositioned away from external surfaces during chamfer coating, preventing contamination while maintaining thread protection.
Solution Approach 2:
The movable vacuum nozzle acts as an intermediary that controls powder distribution. By dynamically positioning the nozzle, it mediates between the need for comprehensive thread protection (including chamfers) and the need to keep external surfaces clean, allowing selective powder collection based on process requirements.
3Manufacturing precision
If the spray nozzle is positioned to coat internal threads, then internal coating is achieved, but external surfaces and weld projections become contaminated
Solution Approach 1:
The vacuum nozzle is dynamically positioned during the coating process. It is placed to align with the bore opening during internal thread coating to collect over-sprayed powder, then repositioned during chamfer coating operations. This dynamic positioning prevents powder from contaminating weld projections while maintaining precise internal thread coating.
4Loss of substance
If a movable vacuum nozzle is used to align with the bore opening, then powder containment is improved, but device complexity increases
Solution Approach 1:
The movable vacuum nozzle system is designed to automatically position itself relative to the fastener bore opening during coating operations. The system uses the fastener's own geometry (the bore opening) as a reference point for nozzle positioning, eliminating the need for complex external positioning mechanisms and reducing overall device complexity while maintaining effective powder containment.
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
Effectively prevents powder from reaching external surfaces, allowing for controlled coating of internal threads and chamfers, reducing fouling and welding failures while maintaining cleanliness and operational efficiency.
Implementation Method 1
a vacuum nozzle (36) movable to a position where its open end is in spaced relationship with the fastener so as to remove excess powder from the fastener
Implementation Method 2
a spray nozzle assembly (38) movable to a position where the spray nozzle is in communication with the interior of the fastener so as to spray thermoplastic powder onto the internal threads of the fastener
Data Source
Figure 1~2
Figure 3
Figure 4A~4D
AI summary
An apparatus for applying a thermoplastic powder to internal threads of a fastener includes a vacuum nozzle (36) having an end adapted to engage a first surface of the fastener. A spray tube is sized to be inserted within the bore of the fastener and communicates with a source or sources of thermoplastic powder and pressurized air. A bushing (56) is mounted on the spray tube (54) so that the spray tube (54) is able to slide with respect to the bushing. The bushing is adapted to engage a second surface of the fastener. The spray tube and bushing are movable between clamping positions, where the vacuum nozzle and the bushing engage the first and second surfaces of the fastener, and release positions where the vacuum nozzle (36) and the bushing (56) do not engage the first and second surfaces of the fastener. A fastener holder holds the fastener between the vacuum nozzle and the bushing so that when the vacuum nozzle (36) and the bushing (56) are in the clamping positions, the spray tube (54) enters the bore of the fastener and sprays thermoplastic powder on the internal threads of the fastener with excess thermoplastic powder collected by the vacuum nozzle (36). The vacuum nozzle (36) and bushing (56) may be machined and to permit either, both or neither of first and second chamfers of the fasteners to also be coated.