Tapping Screw Joining with Dynamic Pressure for Stacked Plates
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Solution Overview
Problem
Existing joining methods using tapping screws often result in plastic deformation of plate members due to constant pressurizing force, leading to unacceptable joining states, especially when the screw penetrates members with varying rigidity.
Innovation Solution
A method and apparatus that dynamically adjust the pressurizing force applied to the tapping screw by reducing the pressure when the screw penetrates each plate member, based on the thickness and material properties of the members, to prevent plastic deformation and ensure proper joining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a constant pressurizing force corresponding to the total thickness of all plate members is applied during through-hole formation, then the tapping screw can penetrate all plate members, but plastic deformation occurs in plate members with smaller rigidity
Solution Approach 1:
The pressurizing force is changed dynamically during the through-hole formation process. The force is reduced in stages as the tapping screw penetrates each plate member, transitioning from a first pressurizing force (corresponding to total thickness) to a second pressurizing force (corresponding to remaining thickness). This dynamic adjustment prevents plastic deformation while ensuring complete penetration.
Solution Approach 2:
The pressurizing force parameter is changed based on the penetration depth and remaining plate thickness. By adjusting the force parameter from a higher initial value to a lower final value, the system adapts to the changing mechanical conditions during the joining process, preventing excessive force application to less rigid plate members.
2Manufacturing precision
If the pressurizing force is reduced when the tapping screw penetrates the first plate member, then plastic deformation is suppressed, but the screw may not penetrate all plate members sufficiently
Solution Approach 1:
The through-hole formation process is segmented into multiple stages, with each stage corresponding to penetration through a specific plate member. The pressurizing force is adjusted at each segment boundary, reducing from the first pressurizing force to the second pressurizing force when transitioning from one plate member to the next. This segmentation ensures adequate force is applied at each stage without causing deformation.
3Strength
If a high pressurizing force is applied to penetrate thick plate members, then the screw can form through-holes in all members, but the rigidity of individual members may be compromised
Solution Approach 1:
The pressurizing force is applied dynamically, starting high to ensure penetration capability through thick plate members, then reducing to lower forces as penetration progresses. This dynamic force application maintains the structural integrity of individual members while achieving complete penetration through all stacked plate members.
Data Source
AI summary
A joining method is a method of joining a plate set composed by a plurality of stacked plate members including a first plate member and a second plate member by using a tapping screw. When the tapping screw is advanced into the plate set while the tapping screw is rotated in a state of applying a pressure onto the plate set so as to form through-holes in the first plate member and the second plate member, a first pressure applied onto the tapping screw is reduced down to a second pressure at the time when the tapping screw penetrates the first plate member.