Flow Drill Screw Control Using Axial Position Volatility
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Solution Overview
Problem
Existing flow drill screw (FDS) installation methods struggle with inconsistent penetration and thread formation due to reliance on axial position or velocity thresholds, which can lead to incomplete penetration and joint failure, especially when these thresholds are lagging indicators of the actual process conditions.
Innovation Solution
A method and system that utilize volatility calculations of axial position data, specifically using algorithms like True Range or Standard Deviation, to determine the optimal switch from high to low rotational speed and axial force settings, ensuring precise penetration and thread formation by anticipating process changes earlier than traditional methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If axial position or velocity threshold methods are used to control the switch from high to low RPM, then the control system is simple to implement, but penetration consistency and thread formation quality deteriorate due to lagging indicators
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors axial position data and calculates volatility in real-time. The controller adjusts RPM based on the calculated volatility threshold, creating a closed-loop control system that responds to actual process conditions rather than relying on predetermined thresholds. This feedback approach eliminates the lagging indicator problem while maintaining control system feasibility.
Solution Approach 2:
The patent replaces traditional mechanical control methods (predetermined position/velocity thresholds) with a computational approach using volatility calculation algorithms. By substituting the control mechanism from fixed mechanical thresholds to dynamic computational analysis of position data volatility, the system achieves superior penetration consistency without significantly increasing overall system complexity.
2Force
If high RPM and force are maintained until penetration is detected, then penetration force is sufficient, but thread forming quality deteriorates due to excessive speed and force at critical moments
Solution Approach 1:
The patent implements dynamic control of RPM and force by continuously adjusting these parameters based on real-time volatility calculations. The system transitions from static predetermined thresholds to dynamic adaptation, allowing optimal force application during penetration while automatically reducing speed and force during thread forming. This dynamic approach ensures both sufficient penetration force and high thread forming quality.
Solution Approach 2:
The patent changes the control parameter from fixed position/velocity thresholds to volatility-based thresholds that adapt during the process. By monitoring changes in axial position data volatility and adjusting RPM and force parameters accordingly, the system maintains optimal penetration force while ensuring quality thread formation. The parameter changes are continuous and responsive to actual process conditions.
3Manufacturing precision
If RPM and force are reduced early to ensure thread forming quality, then thread formation is controlled, but penetration reliability deteriorates due to insufficient heat and force generation
Solution Approach 1:
The feedback mechanism monitors axial position volatility in real-time and only reduces RPM and force when the volatility threshold indicates penetration has been achieved. This ensures that sufficient heat and force are maintained throughout the penetration process, eliminating the risk of incomplete penetration while still providing controlled thread formation. The feedback loop prevents premature parameter reduction.
Solution Approach 2:
The system performs preliminary monitoring and calculation of position data volatility before making any parameter adjustments. By analyzing the volatility trend in advance and predicting when penetration will be achieved, the system ensures that RPM and force are maintained at optimal levels throughout the penetration phase, then transitions smoothly to thread forming control.
4Device complexity
If predetermined position thresholds are used for control switching, then the control logic is simple, but process adaptability deteriorates due to inability to respond to varying material conditions
Solution Approach 1:
The patent transforms the control parameter from fixed predetermined position thresholds to dynamic volatility-based thresholds that automatically adapt to varying material conditions. The volatility calculation inherently responds to changes in material properties, penetration resistance, and process conditions, providing superior adaptability while keeping the control logic relatively simple through standardized volatility algorithms.
Solution Approach 2:
The feedback mechanism continuously monitors axial position data and calculates volatility, allowing the system to adapt to varying material conditions in real-time. Unlike predetermined thresholds that cannot respond to material variations, the volatility-based feedback automatically adjusts the control point based on actual process conditions, enhancing process adaptability across different materials and conditions.
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
This approach provides more accurate and timely control over the FDS installation process, reducing the risk of incomplete penetration and joint failure by using volatility as a leading indicator, thereby enhancing process reliability and consistency.
Implementation Method 1
The lower substrate is typically metal and the total number of substrates is typically two to four, though other numbers can be used. The upper substrate(s) may or may not have a preformed thru-hole.
Implementation Method 2
The typical FDS automatic tool does not directly control axial position. This high RPM, force generates the friction that heats the substrate
Data Source
AI summary
A method of installing a flow drill screw (FDS) into a substrate includes engaging the FDS with an automatic tool and operating the tool at a first setting to drive the FDS into the substrate. The first setting rotates the FDS at a first rotational speed and applies a first axial feed force. The first setting causes flow of the substrate to permit the FDS to penetrate the substrate. The method includes detecting, via a sensor, axial position data of the FDS while operating the automatic tool and calculating, via a controller, volatility of the axial position data. The method includes switching the automatic tool from the first setting to a second setting in response to the volatility. The second setting rotates the FDS at a second rotational speed and applies a second axial feed force to the FDS. The second rotational speed is less than the first rotational speed.