Screw Length Determination Using Driver Rotation and Axial Position
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Solution Overview
Problem
Existing screw length determination methods are inaccurate due to variations in the distance between the bolt and the fastening target, leading to potential errors in bolt length measurement.
Innovation Solution
A screw length determination system that calculates the screw length based on the axial position and rotation of the driver during specific tightening periods, including descent completion, provisional seating, primary tightening, and holding periods, using predetermined torque values for accurate measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the time required for bolt seating is used to determine bolt length, then the measurement process is simple, but the measurement precision deteriorates due to variations in distance from the bolt to the fastening target
Solution Approach 1:
The patent replaces the time-based measurement method with a torque-based measurement method. Instead of measuring the time required for bolt seating, the system measures the torque applied during tightening operations. This substitution eliminates the influence of distance variations between the bolt and fastening target, thereby improving measurement precision while maintaining operational simplicity through automated torque monitoring and analysis.
2Measurement precision
If torque-based measurement is implemented to improve accuracy, then the measurement precision improves, but the device complexity increases due to additional sensors and control systems
Solution Approach 1:
The patent integrates the torque measurement functionality into the existing tightening system, allowing the same system to perform both tightening operations and length determination. The torque values obtained during the tightening process are analyzed to determine bolt length, eliminating the need for separate measurement devices. This multi-functional approach improves measurement precision while minimizing the increase in device complexity.
3Reliability
If multiple tightening operations are performed to ensure proper seating, then the reliability of tightening increases, but the loss of time increases due to repeated operations
Solution Approach 1:
The patent implements a feedback mechanism where torque values from tightening operations are monitored and analyzed in real-time. The system uses the torque data to determine bolt length and verify proper seating, providing immediate feedback on tightening quality. This allows the system to reliably determine bolt length during the tightening process itself, eliminating the need for additional repeated tightening operations and reducing time loss while maintaining high reliability.
Data Source
AI summary
Provided is a screw length determination system capable of determining the length of a screw with a high degree of accuracy. A PLC (10) determines the length of a screw on the basis of the amount of rotation or the position in the axial direction of a driver during a period lasting from the time when the screw completes its descent until any time from among the time when provisional seating occurs, the time when the primary tightening period ends and the time when the period of holding for primary tightening ends.