Flow Drill Screw Control Using Axial Acceleration Switching
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Solution Overview
Problem
Existing methods for installing flow drill screws (FDS) into substrates lack precision and efficiency, particularly in controlling the rotational speed and axial force to ensure successful penetration and thread formation without overshooting and stripping the joint.
Innovation Solution
A method and system that utilize an automatic tool to engage the FDS, operating at a first setting to penetrate the substrate and then switching to a second setting based on axial acceleration data exceeding a predetermined value, thereby reducing the rotational speed and axial force to facilitate thread formation and tightening at lower speeds and forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the automatic tool operates at high RPM and high axial force to generate sufficient heat for penetration, then the substrate can be successfully penetrated, but the torque may rise above the rated torque value and strip the joint
Solution Approach 1:
The patent applies dynamics by continuously monitoring axial acceleration in real-time and dynamically adjusting operational parameters. The system transitions from high RPM/high force to low RPM/low force based on measured acceleration data, allowing the system to adapt to the actual penetration state and prevent torque from exceeding rated values that would strip the joint.
Solution Approach 2:
The system implements feedback control by measuring axial acceleration during penetration and using this information to trigger parameter changes. The feedback loop monitors the penetration process and automatically adjusts operational parameters to maintain reliability while preventing harmful effects like joint stripping.
2Object-affected harmful factors
If the RPM and axial force are reduced early to prevent joint stripping, then the torque remains within rated limits, but the FDS may not fully penetrate the substrate
Solution Approach 1:
The system uses self-service by measuring the axial acceleration of the FDS itself during penetration. This self-measured data directly controls the parameter adjustment timing, eliminating the need for external estimation or predetermined thresholds and ensuring penetration completion while preventing joint stripping.
Solution Approach 2:
The patent applies parameter changes by switching from high RPM/high axial force to low RPM/low axial force based on measured acceleration. This dynamic parameter adjustment ensures sufficient heat generation for complete penetration while preventing torque from exceeding rated values that would cause joint stripping.
3Ease of operation
If the trigger condition is based on axial position or axial velocity threshold, then the process control is simplified, but the precision of determining the optimal parameter change moment is insufficient
Solution Approach 1:
The patent replaces mechanical/position-based control with acceleration-based control. Instead of using axial position or velocity thresholds, the system measures axial acceleration to determine the optimal parameter change moment, providing more precise timing while maintaining ease of operation through automated monitoring.
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 enhances the precision and reliability of FDS installation by ensuring that the rotational speed and axial force are reduced at the optimal moment, preventing incomplete penetration and joint stripping, and allowing for controlled tightening and process completion.
Implementation Method 1
The typical FDS automatic tool does not directly control axial position. This high RPM, high force generates the friction that heats the substrate and is maintained until the automatic tool detects a trigger condition
Implementation Method 2
causing flow of the substrate to permit the FDS to penetrate 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, operating the tool at a first setting to drive the FDS into the substrate by causing flow of the substrate to permit the FDS to penetrate the substrate, and switching the automatic tool from the first setting to a second setting in response to a controller analyzing axial acceleration data of the FDS. The first setting is configured to rotate the FDS at a first rotational speed and to apply a first axial feed force. The first setting is further configured to cause flow of the substrate to permit the FDS to penetrate the substrate. The second setting is configured to rotate the FDS at a second rotational speed and to apply a second axial feed force. The second rotational speed is less than the first rotational speed.