Fastened Structure With Folded Portion For Thin Metal Plates
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Solution Overview
Problem
Thin metal plates in mechanical apparatuses face challenges in achieving sufficient fastening torque and stability due to short thread engaging lengths, which can lead to deformation and inadequate electrical conductivity, especially when using conventional screw fastening methods.
Innovation Solution
A fastened structure is developed using a male screw with a flange portion and a folded-back portion on the fastened material, allowing for increased bearing surface torque and improved axial force distribution, enhancing the fastening torque and stability without additional parts, while maintaining electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the plate thickness of the fastening material is reduced to achieve weight reduction and energy saving, then the weight of the apparatus is reduced, but the thread engaging length becomes short leading to insufficient breakdown torque and fastening reliability
Solution Approach 1:
A burring portion is formed in advance on the fastening material at the screw fastening position. This preliminary action creates a protruding structure that extends the thread engaging length beyond the limited plate thickness, ensuring sufficient engagement length and breakdown torque even when using thin metal plates for weight reduction
Solution Approach 2:
The burring portion adds a vertical dimension (burring height) to the fastening structure. By creating a protruding feature that extends perpendicular to the plate surface, the effective thread engaging length is increased in the vertical direction, compensating for the reduced plate thickness and maintaining adequate engagement length for reliable fastening
2Ease of manufacture
If conventional screw fastening is used on thin metal plates without burring, then the manufacturing process is simple, but the thread engaging length is insufficient causing deformation and inadequate breakdown torque
Solution Approach 1:
A burring portion is formed in advance on the fastening material at the screw fastening position. This preliminary action creates a protruding structure that extends the thread engaging length beyond the limited plate thickness, ensuring sufficient engagement length and breakdown torque even when using thin metal plates for weight reduction
3Strength
If a rubber-mode elastic member is added between the screw head and fastened material to improve fastening torque, then the breakdown torque is increased, but the number of parts increases leading to higher cost and assembly complexity
Solution Approach 1:
The burring portion on the fastening material serves dual functions: it extends the thread engaging length to provide sufficient breakdown torque, and simultaneously creates a bearing surface for the screw head. This self-service structure eliminates the need for separate elastic members or washers, maintaining simple assembly while achieving the required fastening performance
Solution Approach 2:
The invention merges the functions of thread engagement extension and bearing surface provision into a single integrated burring structure. By combining these two functions that would otherwise require separate components (such as elastic members and washers), the design achieves sufficient breakdown torque while minimizing the number of parts and assembly complexity
4Reliability
If the thread engaging length is increased to ensure sufficient breakdown torque, then the fastening reliability is improved, but the plate thickness must be increased which contradicts the weight reduction requirement
Solution Approach 1:
The burring portion adds a vertical dimension (burring height) to the fastening structure. By creating a protruding feature that extends perpendicular to the plate surface, the effective thread engaging length is increased in the vertical direction, compensating for the reduced plate thickness and maintaining adequate engagement length for reliable fastening
Solution Approach 2:
A burring portion is formed in advance on the fastening material at the screw fastening position. This preliminary action creates a protruding structure that extends the thread engaging length beyond the limited plate thickness, ensuring sufficient engagement length and breakdown torque even when using thin metal plates for weight reduction
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 significantly improves the breakdown torque by 45% and loosening torque resistance by 26-36%, ensuring reliable fastening and electrical connection without increasing the number of parts, even with thin metal plates.
Implementation Method 1
the frictional force between the elastic member and the screw head by an anti-loosening resistance of the elastic member are increased
Implementation Method 2
normal reaction by a repelling force of the elastic member are increased
Implementation Method 3
a male screw fastening the first member and the second member with each other and including a male screw portion, and a head portion having a bearing surface, wherein the male screw portion is threaded in the female screw through the opening of the second member
Implementation Method 4
a free end having an edge pressed against the bearing surface of the male screw
Data Source
AI summary
a fastened structure comprising: a first member provided with a female screw; a second member provided with an opening; and a male screw fastening the first member and the second member with each other and including a male screw portion, and a head portion having a bearing surface, wherein the male screw portion is threaded in the female screw through the opening of the second member, wherein the second member is provided with a substantially circular folded portion including a curved surface defining the opening and including a free end having an edge pressed against the bearing surface of the male screw.