Hand-Held Power Tool Variable Speed Control for Screw Setting
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Solution Overview
Problem
Hand-held power tools used for setting screws in the construction industry often apply excessive force, leading to incomplete thread formation in drywall elements and potential material weakening, especially when used at high repetition rates.
Innovation Solution
A hand-held power tool with a motor and magnetic coils that adjusts its rotational speed to between 6,800 RPM and 9,000 RPM, with a controller that continuously determines torque and adjusts speed based on applied force, ensuring optimal screw penetration and thread formation without excessive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the screw is pressed against the drywall element with great force to work at high repetition rate, then productivity is improved, but the screw may be pressed through so quickly that thread formation is incomplete, worsening manufacturing precision
Solution Approach 1:
The patent applies dynamics by implementing variable speed control of the rotary shaft throughout the screw setting cycle. The controller adjusts the rotational speed dynamically: higher speeds during penetration to maintain productivity, and reduced speeds during thread formation to ensure quality. This dynamic adjustment resolves the contradiction between high repetition rate and proper thread formation.
Solution Approach 2:
The patent employs periodic action through cyclic speed variation during the screw setting process. The motor operates in distinct phases with different speed characteristics: an initial high-speed phase for rapid penetration, followed by a controlled deceleration phase for proper thread engagement. This periodic speed modulation allows both high productivity and manufacturing precision to be achieved at different stages of the same operation.
2Productivity
If the rotational speed is increased to improve productivity, then screw penetration speed is improved, but material weakening and potential disengagement issues occur, worsening reliability
Solution Approach 1:
The system uses dynamic speed control to adjust rotational velocity based on real-time operating conditions. The controller monitors the setting process and modulates motor speed to optimize penetration while preventing excessive force that would cause material weakening or disengagement. This dynamic approach maintains reliability while improving productivity.
Solution Approach 2:
The patent implements feedback control where the controller continuously monitors the screw setting process and adjusts motor operation accordingly. By detecting conditions such as abnormal torque or speed variations, the system can reduce speed to prevent material damage or disengagement, ensuring reliable operation while maintaining high productivity during normal conditions.
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
The tool efficiently sets screws with improved thread formation and reduced material weakening, optimizing screw penetration speed and minimizing user fatigue, while preventing disengagement issues at higher speeds.
Implementation Method 1
providing electric current to the one or more magnetic coils to rotationally drive the shaft
Data Source
AI summary
A machine and a method for drilling a hole or setting a screw is provided, wherein the machine comprises a motor having a shaft and one or more magnetic coils, providing electric current to the one or more magnetic coils to rotationally drive the shaft, and switching the electric current at a commutation frequency to define a rotational speed of the shaft. A signal may be generated when a force towards the machine applied to the shaft increases and/or a torque applied to the shaft increases and the rotational speed of the motor may be increased to a first rotational speed when the signal is received. The rotational speed may be at least 6,800 RPM and at most 8,500 RPM.