Impact Rotation Tool Torque Control via Angular Acceleration
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Solution Overview
Problem
Conventional impact rotation tools face challenges in accurately calculating the tightening torque, leading to potential overtightening or undertightening of fasteners due to the inclusion of torque for rotating the main shaft in the measured torque, which can differ from the target torque.
Innovation Solution
The impact rotation tool and attachment incorporate a drive source, impact force generation unit, torque measurement unit, rotation angle measurement unit, and a controller that calculates tightening torque based on angular acceleration and measured torque, allowing for precise control of the drive source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If torque measurement unit measures torque applied to the shaft, then torque can be detected, but the measured torque includes torque for rotating the main shaft which cannot be separated from the tightening torque
Solution Approach 1:
The patent segments the torque measurement by separating the tightening torque from the main shaft rotation torque. The rotation angle measurement unit measures only the rotation angle of the bit (not the main shaft), and the tightening torque calculation unit calculates tightening torque based on this bit rotation angle and the measured torque, effectively segmenting the measurement to exclude main shaft rotation components.
Solution Approach 2:
The patent introduces a rotation angle measurement unit as an intermediary that measures the rotation angle of the bit. This intermediary measurement allows the system to calculate the actual tightening torque by relating the bit's rotation to the measured torque, thereby mediating between the raw torque measurement and the actual tightening effect.
2Ease of operation
If motor is stopped when measured torque reaches target torque, then control is simplified, but the actual tightening torque may completely differ from target torque
Solution Approach 1:
The patent implements feedback control by continuously calculating the actual tightening torque based on real-time measurements of rotation angle and torque. The controller uses this feedback information to determine when to stop the motor, ensuring that the actual tightening torque reaches the target value with high precision rather than relying on simplified predetermined thresholds.
Solution Approach 2:
The patent replaces the simple mechanical torque threshold comparison with a more sophisticated calculation system that uses rotation angle measurement and torque measurement combined with moment of inertia data. This substitution of the control mechanism enables precise control of actual tightening torque.
3Force
If impact rotation tool generates high torque, then workability is improved, but overtightening of fasteners occurs
Solution Approach 1:
The patent applies dynamics by calculating the actual tightening torque in real-time during the tightening process. The system dynamically adjusts the motor operation based on the calculated actual tightening torque, allowing the tool to deliver high impact torque when needed while automatically stopping before overtightening occurs, thus adapting the torque delivery to the actual fastening requirements.
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 solution enables high-accuracy calculation and control of tightening torque, ensuring that fasteners are tightened to the desired strength without overtightening or undertightening.
Implementation Method 1
converts the decelerated rotation force to a pulsed impact torque using hydraulic pressure or hammer impacts
Implementation Method 2
converts the decelerated rotation force to a pulsed impact torque using hydraulic pressure or hammer impacts
Implementation Method 3
a torque measurement unit configured to measure torque applied to the shaft as measured torque
Implementation Method 4
a rotation angle measurement unit configured to measure a rotation angle of the shaft
Implementation Method 5
a tightening torque calculation unit configured to calculate an angular acceleration from the rotation angle and calculate a tightening torque based on the angular acceleration and the measured torque
Implementation Method 6
multiplying the angular acceleration with the moment of inertia
Data Source
AI summary
An impact rotation tool including a drive source, an impact force generation unit that generates an impact force for converting power from the drive source to pulsed torque, a shaft that transmits the pulsed torque to a bit used to perform a tightening task, a torque measurement unit that measures torque applied to the shaft as measured torque, a rotation angle measurement unit that measures a rotation angle of the shaft, a tightening torque calculation unit that calculates an angular acceleration from the rotation angle to calculate a tightening torque based on the angular acceleration and the measured torque, and a controller that controls the drive source based on the tightening torque.