Dual-Motor Tightening Socket for Precise Bolt Tension Control
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Solution Overview
Problem
Existing tightening devices for bolt/nut fasteners require complex mechanisms for automation, making them inefficient and prone to variations in tightening force, leading to increased size and weight of fastened objects due to over-tightening for safety considerations.
Innovation Solution
A tightening device with a drive socket, nut holder, tension rod, and dual motors, where the first motor rotates the tension rod and the second motor rotates the drive socket, with a sensor to detect tensile force, allowing precise and automated tightening by synchronizing the rotation of the nut and tension rod to achieve the target tightening force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a planetary gear mechanism and clutch are used to transmit drive force to the female screw member or nut, then the tightening device can precisely control the tightening force, but the device complexity increases due to the need for attaching and detaching multiple members
Solution Approach 1:
The patent combines the functions of the planetary gear mechanism and clutch into a single integrated mechanism. The drive force from the motor is transmitted through a planetary gear mechanism that directly engages with the nut, eliminating the need for separate clutch mechanisms and member attachment/detachment operations. This merging reduces structural complexity while maintaining precise tightening force control through the inherent mechanical advantages of the planetary gear system.
Solution Approach 2:
The planetary gear mechanism is designed to serve multiple functions: it provides both the torque multiplication needed for precise tightening force control and the engagement/disengagement capability previously requiring a separate clutch. The mechanism can automatically engage and disengage from the nut based on the tightening process requirements, making it a multi-functional component that reduces overall device complexity.
2Reliability
If the fastener size is increased to provide sufficient tightening force, then the safety margin is improved, but the space required and the weight of the fastening target object increase
Solution Approach 1:
The patent changes the key parameter from fastener size to tightening method precision. By using a planetary gear mechanism that enables precise control of tightening force (achieving accuracy within ±5% or better of the target value), the system maintains adequate safety margins without requiring oversized fasteners. This parameter change allows the use of appropriately sized, lighter fasteners while preserving structural safety through controlled tightening.
3Reliability
If the fastener size is increased to accommodate safety considerations, then the reliability is improved, but the space where the fastener is disposed increases
Solution Approach 1:
The patent shifts the approach from increasing fastener dimensions to improving tightening process control. By implementing precise tightening force control through the planetary gear mechanism, the system achieves reliable safety margins with standard-sized fasteners, thereby minimizing the space required for fastener disposal while maintaining structural integrity and safety requirements.
Data Source
AI summary
Tightening device can fasten a fastening element by a target tightening force with good accuracy and facilitate automation. The tightening device includes a cylindrical drive socket holding a nut in the lower end opening thereof; a nut holder disposed inside the drive socket, a bolt passing through a bottom thereof, and regulating movement of the nut held by the drive socket toward the tip end of a threaded par; a tension rod which is disposed inside the nut holder and the lower end face of which has a threaded hole into which a portion of the threaded part that is further on the tip end side than the nut is screwed; a sensor for detecting tension force; a first motor for turning the tension rod around an axis that extends in the vertical direction; and a second motor for turning the drive socket around an axis.