Impact Wrench Torque Control via Rotary Impact Phasing
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Solution Overview
Problem
Existing methods for tightening threaded connections in steel construction are labor-intensive and pose a risk of user injury due to the need for applying high torque, especially when dealing with multiple screws, and direct measurement of output torque is challenging in impact wrenches due to mechanical decoupling and structural element deformation.
Innovation Solution
A three-phase control method for an impact wrench that analyzes the threaded connection and structural elements to determine a setpoint torque and final rotational angle, using a predefined number of rotary impacts to achieve the setpoint torque and then applying additional impacts to reach the final rotational angle, with adaptive pattern estimation and sensor-based torque estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual tightening of threaded connections is performed, then torque application can be directly controlled, but user effort increases and risk of injury increases
Solution Approach 1:
The patent replaces manual mechanical torque application with an automated impact wrench system that uses electronic control and sensor feedback. The impact mechanism delivers controlled rotary impacts to tighten threaded connections, eliminating the need for manual torque application while maintaining precision through electronic torque estimation and adaptive control algorithms.
2Measurement precision
If direct torque measurement is implemented in impact wrench, then precise torque control is achieved, but device complexity increases due to mechanical decoupling
Solution Approach 1:
The patent introduces torque estimation as an intermediary approach rather than direct measurement. It uses sensor data (rotational angle, impact frequency, current) combined with adaptive pattern recognition algorithms to estimate torque indirectly. This mediator approach bypasses the complexity of direct torque sensing in the mechanically decoupled impact wrench system while achieving sufficient measurement precision for controlled tightening.
Solution Approach 2:
The patent replaces direct mechanical torque measurement with an electronic estimation system. Instead of using complex mechanical torque sensors that would interfere with the impact mechanism, it substitutes a software-based torque estimation algorithm that processes data from existing sensors (current, rotational angle, impact frequency) to infer torque values, thereby simplifying the overall device architecture.
3Measurement precision
If adaptive pattern recognition is used for torque estimation, then measurement accuracy improves, but computational requirements and processing time increase
Solution Approach 1:
The patent performs preliminary action by pre-storing reference patterns and characteristics of threaded connections in the control unit. During operation, the system compares real-time sensor data against these pre-stored patterns using adaptive recognition algorithms, enabling fast torque estimation without extensive real-time computation. This preliminary preparation of reference data significantly reduces processing time while maintaining high measurement precision.
Data Source
AI summary
A control method for tightening a threaded connection executes, in response to actuation of a pushbutton key, a sequence with consecutive phases. In a first phase, an impact mechanism of an impact wrench exerts a predefined number of rotary impacts on the threaded connection. During the first phase, a profile of a rotational angle over time is estimated. A pattern is adapted to the profile and on the basis of the pattern a setpoint torque is determined for a second phase and a final rotational angle or a final number of impacts is determined for a third phase. During the second phase, rotary impacts are exerted until an estimated torque reaches the setpoint torque. During the third phase, rotary impacts are exerted on the threaded connection until a number of rotary impacts corresponds to the final number or a rotational angle corresponds to the final rotational angle.