Hand-Held Tool Control Method for Blockage Clearance
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Solution Overview
Problem
Existing rotary hammer control methods fail to effectively manage uncontrolled swinging due to drill bit blockages, leading to user safety risks and difficulties in restarting the tool after clearing the blockage.
Innovation Solution
A control method that interrupts continuous rotation and alternates between reverse and forward directional energy pulses to maintain user control and facilitate blockage clearance, with less energy provided for reverse movement to manage torque effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rotary hammer continuously rotates in forward direction to maintain drilling operation, then productivity is maintained, but when blockage occurs the user loses control and experiences dangerous reverse torque
Solution Approach 1:
The patent implements periodic reverse rotation cycles during blockage detection. Instead of continuous forward rotation, the system alternates between forward rotation and brief reverse rotation pulses. This periodic action allows the drill bit to oscillate and break through blockages while preventing dangerous reverse torque accumulation, as the reverse rotation is limited in duration and magnitude compared to continuous forward operation.
Solution Approach 2:
The system dynamically changes rotational parameters when blockage is detected. The control method modifies rotation direction, speed, and duration based on detected blockage conditions. Specifically, it transitions from continuous high-speed forward rotation to controlled reverse rotation with lower energy input, then gradually increases forward rotation energy as the blockage clears, optimizing both safety and effectiveness.
2Reliability
If the safety device interrupts continuous rotation to protect the user, then safety is improved, but the user has difficulty restarting the hammer drill with the blocked drill bit
Solution Approach 1:
The system performs preliminary blockage-clearing action by executing controlled reverse rotation cycles before allowing normal operation to resume. When blockage is detected, the hammer drill automatically initiates reverse rotation sequences that work to free the blocked drill bit. This preliminary action clears the blockage before the user needs to restart the tool, eliminating the need for manual intervention to free a stuck bit.
Solution Approach 2:
The safety system provides self-service by automatically detecting blockages and executing counter-rotation sequences to clear them without user intervention. The control device monitors operational parameters, detects blockage conditions, and autonomously implements the reverse rotation clearing mechanism. This self-service capability eliminates the need for the user to manually free a blocked drill bit, making the tool easier to operate safely.
3Productivity
If equal energy is supplied in both reverse and forward direction during protective method, then the tool can oscillate to clear blockage, but the user experiences excessive reverse torque in the direction they are accustomed to
Solution Approach 1:
The patent applies asymmetric energy distribution between reverse and forward rotation. During protective operation, the system supplies less energy for reverse rotation than for forward rotation. This asymmetry creates a net forward torque that maintains user control comfort while still enabling effective blockage clearance through the oscillatory motion. The reverse rotation is sufficient to loosen blockages but limited in magnitude to prevent excessive reverse torque.
Solution Approach 2:
The control method applies different energy characteristics to different phases of the rotation cycle. Reverse rotation receives limited energy input specifically tailored for breaking blockages, while forward rotation receives full energy input for productive drilling. This localized quality differentiation ensures that blockage clearance is effective without compromising overall user control and comfort during normal operation.
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 method ensures user safety by maintaining tool activity and aiding in blockage clearance, allowing for smoother restarts by maintaining a mean forward torque sensation and reducing the risk of injury or tool damage.
Implementation Method 1
a rotary drive (4), which rotates the tool holder (2) around its working axis (5)
Data Source
Figure 1~2
Figure 3
AI summary
A control method according to the invention for a power tool (1) for rotary tools provides the following steps: A tool holder (2) is rotated continuously in a forward direction about a working axis (5) by means of a rotary drive (4) when an operating switch (7) is actuated. The continuous rotation in the forward direction is interrupted by a protective process when a protective device (14) senses blocking of the tool holder (2). During the protective process, one or more cycles are executed, in which the rotary drive (4) is actuated successively in accordance with an unimpeded rotary movement in a reverse direction and in accordance with an unimpeded rotary movement in the forward direction. The rotary drive (4) is supplied with a first amount of energy for the rotary movement in the reverse direction and with a second amount of energy for the rotary movement in the forward direction. The first amount of energy is smaller than the second amount of energy.