Pulse Fastening Control Device for Rigidity Variations
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Solution Overview
Problem
Existing fastening technologies, such as those described in Japanese Patent Application Publication No. 6-79552, fail to accurately account for differences in the rigidity of fastened members, leading to variations in fastening accuracy and quality, especially when targeting a specific torque.
Innovation Solution
A control method and device for a fastening tool that applies torque in a pulse-like fashion, adjusting pulse strength and time based on real-time feedback of last fastening torque, allowing the fastening tool to dynamically adjust torque application to match a target torque by varying pulse strength and time, ensuring consistent target torque achievement regardless of fastened member rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed torque curve is used for fastening control, then the control method is simple, but fastening accuracy deteriorates when rigidity of fastened members varies
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed torque curve to a dynamic torque control method that adjusts torque based on real-time detection of fastening state and rigidity characteristics. The control system dynamically modifies torque application during the fastening process to accommodate variations in fastened member rigidity, thereby maintaining fastening accuracy across different rigidity conditions.
Solution Approach 2:
The patent implements feedback by detecting fastening torque and fastening state in real-time, then using this information to adjust subsequent torque application. The system monitors the fastening process continuously and modifies the torque curve based on detected rigidity characteristics and fastening progress, creating a closed-loop control system that improves fastening accuracy while adapting to varying conditions.
2Manufacturing precision
If pulse strength and time are adjusted dynamically, then fastening accuracy improves, but control complexity increases
Solution Approach 1:
The system uses real-time feedback from torque detection to dynamically adjust pulse strength and time parameters. By monitoring fastening torque during each pulse and comparing it with target values, the control system automatically modifies subsequent pulse characteristics to achieve precise fastening control, reducing the need for complex manual calibration.
Solution Approach 2:
The patent applies preliminary action by pre-setting a torque curve and control parameters before the fastening process begins. This preliminary configuration provides a baseline control strategy that simplifies real-time adjustments, as the system only needs to deviate from the pre-set curve based on detected rigidity characteristics rather than calculating all parameters from scratch during operation.
3Ease of operation
If torque is applied continuously, then fastening process is simple, but reaction forces increase and workability deteriorates
Solution Approach 1:
The patent implements periodic action by applying torque in discrete pulses rather than continuously. This pulsed torque application allows the fastening system to build up torque incrementally, reducing peak reaction forces and improving workability. The periodic nature of pulse application also provides natural pause points that reduce cumulative reaction forces on the fastening member and operator.
Solution Approach 2:
The patent applies segmentation by dividing the continuous torque application process into discrete pulse segments. Each pulse represents a separate torque application event with controlled duration and magnitude. This segmentation allows for better control of reaction forces, as each pulse can be independently optimized and terminated before excessive force buildup occurs.
Data Source
AI summary
A control method according to an aspect of the invention includes a process for setting target fastening torque, a pulse interval of neighboring pulses, and an elevated value of torque per pulse, detecting last fastening torque at an Nth pulse (N is a natural number of 1 or more) after seating of a fastening member, setting pulse loading time at an N+1th pulse and pulse strength at the N+1th pulse based on the last fastening torque at the Nth pulse so that fastening torque at the N+1th pulse coincides with a multiple of the elevated value, controlling a fastening tool based on the pulse interval, the pulse loading time, and the pulse strength so that last fastening torque at an N+Mth pulse (M is a natural number of 1 or more) reaches target fastening torque.