Pulse Tool Torque Control Using Reverse Pulses and Feedback
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Solution Overview
Problem
Existing hand-held pulse tools face challenges in accurately controlling the torque applied to screw joints due to uncertainties in friction, leading to inefficiencies and potential under or over-tightening, which affects operator ergonomics and productivity.
Innovation Solution
An electric hand-held pulse tool equipped with sensors to monitor torque pulses and a control unit that adjusts torque increments based on real-time feedback, allowing for precise control of installed torque and clamp force by reversing motor direction to assess joint friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If torque is applied in pulses to tighten joints, then tightening speed is improved, but torque control precision deteriorates due to friction uncertainty
Solution Approach 1:
The system uses a sensor to monitor a parameter reflecting the delivered torque pulse and feeds this information back to a control unit. The control unit adjusts subsequent torque pulses based on the monitored parameter, enabling closed-loop control that maintains precision despite friction variations while preserving high-speed pulsed operation.
Solution Approach 2:
The control unit dynamically changes torque parameters (magnitude, frequency, duration of pulses) based on real-time feedback from the sensor. This allows the system to adapt to varying friction conditions and maintain accurate torque control throughout the tightening process without sacrificing speed.
2Manufacturing precision
If torque increments are decreased as torque approaches target torque, then torque control precision is improved, but tightening time increases
Solution Approach 1:
The feedback mechanism allows the system to maintain larger torque increments closer to the target value by continuously monitoring the actual torque delivered and making real-time adjustments. This eliminates the need to progressively reduce torque increments, thereby reducing total tightening time while maintaining precision through active control rather than passive step reduction.
Solution Approach 2:
The control system automatically adjusts torque delivery based on its own monitoring of the tightening process, making real-time decisions about optimal torque increment size. This self-regulating capability allows the system to maintain precision without requiring conservative, time-consuming torque reduction strategies.
3Ease of operation
If reaction torque is reduced for operator comfort, then ease of operation is improved, but torque delivery capability deteriorates
Solution Approach 1:
The feedback control allows the system to deliver high torque pulses while compensating for reaction forces through intelligent pulse timing and magnitude adjustment. The control unit can deliver aggressive torque pulses when needed while using feedback to prevent excessive reaction torque accumulation, maintaining both operator comfort and torque delivery capability.
Solution Approach 2:
The pulsed nature of torque delivery inherently reduces continuous reaction torque exposure to the operator. By delivering torque in controlled pulses rather than continuous application, the system maintains high peak torque capability while limiting the average reaction force on the operator, thus resolving the contradiction between torque delivery and operator comfort.
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 approach enables rapid and reliable tightening operations with reduced operator reaction force and time, improving both ergonomics and productivity by accurately adjusting torque increments to achieve target values without slowing down the process.
Implementation Method 1
a sensor for monitoring a parameter reflecting a delivered torque pulse
Implementation Method 2
an electric motor arranged to deliver torque in pulses in a first rotational direction
Implementation Method 3
a control unit for controlling the electric motor during the tightening operation based on said monitored parameter
Data Source
Figure 1
Figure 2~3
AI summary
An electric pulse tool (10) for performing tightening operations where torque is delivered in pulses to tighten screw joints, the pulse tool comprising a bidirectional electric motor (11), an output shaft (12), a sensor (14,15,25) for monitoring a parameter reflecting a delivered torque pulse, and a control unit (16) for controlling the electric motor (11), wherein the sensor (14,15,25) is arranged to provide information regarding the monitored parameter to the control unit (16). The control unit (16) is arranged to, during a tightening operation performed by the electric pulse tool (10) in a first direction, control the motor to provide at least one torque pulse in a second direction that is opposite to the first direction.