Rotary Impact Tool Torque Control
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Solution Overview
Problem
Rotary impact tools face challenges in accurately tightening screws with a wide range of target torques, often resulting in excessive tightening or insufficient torque due to the high torque characteristic, requiring multiple tools for different screw sizes.
Innovation Solution
A rotary impact tool with a control means that adjusts the increased torque value and motor parameters based on the target torque, allowing for accurate tightening across a wide range of torques using a single tool by reducing torque for smaller screws and limiting motor output, rotation speed, and acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a high torque characteristic is used to quickly tighten large bolts, then tightening speed is improved, but tightening accuracy deteriorates for small bolts
Solution Approach 1:
The rotary impact tool dynamically adjusts its impact torque based on the target torque value. The control unit varies the motor's rotational speed and/or the impact mechanism's energy output according to the set target torque, enabling the same tool to accurately tighten both large and small bolts with different torque requirements without sacrificing tightening speed.
Solution Approach 2:
The tool changes operational parameters (motor rotational speed, impact frequency, impact energy) based on the target torque setting. By adjusting these parameters, the tool can deliver appropriate torque levels for different bolt sizes while maintaining efficient tightening performance across the full torque range.
2Device complexity
If a single rotary impact tool is used for all torque ranges, then device complexity is reduced, but tightening accuracy deteriorates for specific torque ranges
Solution Approach 1:
The rotary impact tool is designed with multi-functionality to handle the complete range of tightening applications. The control unit receives target torque inputs and automatically adjusts operational parameters to achieve accurate tightening across all torque ranges, making a single tool universally applicable for both small and large bolts without requiring multiple specialized tools.
3Measurement precision
If the motor output is limited for small torque applications, then tightening accuracy is improved, but power capability deteriorates
Solution Approach 1:
The motor output is dynamically controlled based on the target torque requirement. The control unit adjusts the motor's rotational speed and torque output in real-time, delivering limited output for small torque applications to ensure accuracy while maintaining full power capability for large torque applications, thus resolving the contradiction between precision and power.
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
Enables precise tightening of various screws with reduced error, ensuring the target torque is reached accurately and efficiently without the need for multiple tools, enhancing control and accuracy.
Implementation Method 1
a torque sensor that detects torque applied to the output shaft
Implementation Method 2
an impact generation device that generates impact
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A rotary impact tool comprises: a motor 2 that is a rotation driving source; an impact generation device for generating a pulse impact by rotation of the motor and applying a rotational torque to an output shaft 7 by the impact; a torque sensor 10 for measuring the torque applied to the output shaft; and a control means C for halting the motor when the torque measured by the torque sensor has reached a target torque having been set. The control means is configured to change an increased torque value for one impact according to the target torque having been set.