Conductive Screw Thread Structure for Thick Coating Film Removal
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Solution Overview
Problem
Existing screw threads with recessed portions for coating film removal struggle to maintain conductivity and workability with thick film coatings, as they require increased screwing torque and are inefficient in removing thick coatings.
Innovation Solution
A screw thread design featuring recessed portions with stepped portions and a bulging ridge-shape, where the stepped portions overhang to contact the internal screw thread, reducing screwing torque and stabilizing conductivity by compressing and retaining the removed coating film, and the bulging ridge-shape enhances contact pressure for low axial forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a simple recessed portion is provided on the screw thread ridge to remove coating film, then coating film removal is achieved, but screwing torque increases and workability deteriorates when dealing with thick film coatings
Solution Approach 1:
The screw thread ridge is divided into multiple sections along the screwing direction, with each section having different ridge heights. The distal end portion has a lower ridge height to reduce contact with thick coating and minimize screwing torque, while the rear end portion has a higher ridge height to effectively remove coating film. This segmentation allows different portions of the screw thread to perform different functions optimally.
Solution Approach 2:
Different portions of the screw thread ridge are given different local properties: the distal end portion has reduced ridge height for low torque operation, while the rear end portion has increased ridge height for effective coating removal. This local differentiation allows each section to be optimized for its specific function along the screwing path.
2Ease of operation
If the ridge height is reduced in the distal end portion to reduce screwing torque, then workability improves, but coating film removal capability deteriorates
Solution Approach 1:
The screw thread is segmented into distal end portion with lower ridge height for easy screwing and rear end portion with higher ridge height for effective coating removal. This segmentation resolves the contradiction by assigning different ridge heights to different functional zones along the screwing direction.
Solution Approach 2:
The distal end portion with lower ridge height performs the preliminary action of entering the nut and initiating screwing with reduced torque requirement. Once the screw thread is engaged, the rear end portion with higher ridge height then performs the coating film removal function effectively.
3Object-affected harmful factors
If conventional screw thread design is used with thick film coatings, then coating protection is maintained, but conductivity between screw thread and nut deteriorates
Solution Approach 1:
The screw thread design creates dynamic interaction with the coating film through varying ridge heights. The distal end portion with lower ridge height dynamically engages with the thick coating to reduce torque, while the rear end portion with higher ridge height dynamically removes coating to expose metal surfaces for conductivity, thus maintaining both protection and conduction.
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 design achieves reduced screwing torque and stable conductivity even with thick film coatings, ensuring efficient coating film removal and improved conducting performance.
Implementation Method 1
a pressure-side flank surface of the screw thread ridge other than the first recessed portion is brought into pressure contact with an original surface of the internal screw thread from which the coating film has been removed to enable conduction. Furthermore, an angle of a clearance-side flank surface of the screw thread ridge is made smaller than an angle of the pressure-side flank surface to form a gap for retaining the removed coating between the internal screw thread and the clearance-side flank surface.
Implementation Method 2
a coating film on an internal screw thread side can be removed by an edge portion of the first recessed portion
Implementation Method 3
a pressure-side flank surface of the screw thread ridge other than the first recessed portion is brought into pressure contact with an original surface of the internal screw thread from which the coating film has been removed to enable conduction
Data Source
Figure 1(A)~1(C)
Figure 2(A)~2(C)
Figure 3(A)~3(D)
AI summary
To provide a screw thread which achieves a further reduction in screwing torque while securing removability of a coating film or the like and which is capable of stabilizing conductivity. In a screw thread in which a recessed portion (7) is partially provided on a flank surface (131) of a screw thread ridge provided on a screw thread shaft main body (5), a screw thread ridge (13) in a section where the recessed portion (7) is formed is smaller than a regular screw thread ridge (3), and a ridge height (H12) in a distal end portion in a screwing direction is lower than a ridge height (H11) in a rear end portion in the screwing direction W.