Spray Gun Connection Part Gap Design
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Solution Overview
Problem
The existing connection parts for paint spray guns, made of plastic and metal, suffer from manufacturing tolerances that lead to damage and plastic chipping during assembly and disassembly, resulting in a less tight fit and surface contamination.
Innovation Solution
A cover with a connection part featuring a hollow-cylindrical connection piece, a partial external thread, and a screw wedge element with a triangular or trapezoidal profile, along with a stop element and a gap to prevent overtightening and minimize contact between the metal counter-element and plastic, ensuring a secure and chip-free attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a screw wedge connection is made between a plastic connection piece and a metal counter-element, then a secure attachment is achieved, but the harder metal counter-element digs into the softer plastic connection piece causing damage and plastic chips
Solution Approach 1:
The patent changes the geometric parameters of the screw wedge element by providing a flattened incline at the upper end and a smaller cross-section in certain areas. This modifies the contact pressure distribution between the metal counter-element and plastic connection piece, reducing the digging effect that causes chipping while maintaining the necessary attachment strength.
Solution Approach 2:
The patent applies local quality by making the screw wedge element non-uniform in structure - with a flattened incline at the upper end and varying cross-section along its length. This allows different regions of the screw wedge element to have optimized properties: the flattened upper end prevents digging into the plastic, while the overall structure maintains sufficient engagement for secure attachment.
2Reliability
If the screw wedge connection is overtightened to ensure a tight fit, then connection reliability is improved, but plastic chips are removed and manufacturing precision deteriorates
Solution Approach 1:
The patent modifies the geometric parameters of the screw wedge element to include a flattened incline and reduced cross-section in critical areas. This allows the connection to achieve sufficient reliability without requiring excessive tightening force, thereby preventing plastic chip removal and maintaining manufacturing precision.
Solution Approach 2:
The flattened incline at the upper end of the screw wedge element acts as a cushioning feature that prevents overtightening. This structural element absorbs excess tightening force before it can reach the plastic connection piece, protecting it from damage while still allowing the connection to achieve its required reliability.
3Ease of manufacture
If the screw wedge element has a uniform cross-section to simplify manufacturing, then ease of manufacture is improved, but the harder counter-element digs into the plastic material during assembly and disassembly
Solution Approach 1:
The patent applies local quality by making the screw wedge element non-uniform - with a flattened incline at the upper end and varying cross-section. This localized structural modification prevents plastic digging during assembly and disassembly while adding minimal complexity to the manufacturing process.
Solution Approach 2:
The patent changes the cross-sectional parameters of the screw wedge element along its length, providing a flattened incline at the upper end and varying thickness. This geometric modification prevents the metal counter-element from digging into the plastic while remaining compatible with standard injection molding processes.
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 provides a secure, leak-tight connection that prevents plastic chipping and maintains a tight fit during repeated use, reducing surface contamination and extending the lifespan of the connection parts.
Implementation Method 1
a screw wedge element (8) adjoining the external thread (7) and running around the outer circumference of the connecting piece (5) is formed. The screw wedge element (8) is used to produce a screw wedge connection between the connection part (3) and the gun body (19) of the spray gun (20).
Data Source
Figure 1(a)~1(d)
Figure 2(a)~2(b)
Figure 3(a)~4(b)
AI summary
The invention relates to a connecting part (3) for connecting a material supply device (10) to a spray gun (20), comprising a hollow cylindrical connecting nozzle (5), a screw wedge element (8) circumferentially around the outer circumference of the connecting nozzle (5) with a lower beginning (8a) and an upper end (8b), which serves to produce a screw wedge connection with a counter element (15) arranged on the gun body (19) of the spray gun (20), and a stop element (14) which forms an end stop when producing the screw wedge connection.In order to prevent the counterpart element on the spray gun (20) from digging into the soft plastic connection nozzle (5) and lifting plastic chips there, the connection element (3) according to the invention is provided that the stop element (14) is arranged circumferentially at a distance from the upper end (8b) of the screw wedge element (8), thereby forming a gap (11) between the stop element (14) and the upper end (8b) of the screw wedge element.