Drill Mode Setting Device Torque Control
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Solution Overview
Problem
Existing drilling machines face challenges in reliably setting and maintaining various operating modes over a long period, particularly in ensuring accurate torque transmission and mode switching between impact drilling, drilling, and screwing functions.
Innovation Solution
A hand drill with a drive device featuring a planetary gear and a mode setting device that includes a support ring and pressure ring for torque adjustment, allowing for fixed torque coupling in percussion drilling and drilling modes while enabling adjustable torque in screwing mode, using a sinusoidal or sawtooth wave profile locking mechanism and a spring device for torque setting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid torque coupling is used in impact drilling and drilling modes, then torque transmission is reliable, but the device cannot provide adjustable torque for screwdriving mode
Solution Approach 1:
The patent employs a mode setting device with a support ring and pressure ring that can dynamically change the torque coupling characteristics. In impact drilling and drilling modes, the pressure ring is axially fixed to provide rigid torque coupling. In screwdriving mode, the pressure ring can lift axially to provide adjustable torque through a spring assembly, thus adapting the system behavior to different operating requirements.
Solution Approach 2:
The torque transmission path is segmented into different zones: a fixed torque coupling zone for impact drilling and drilling modes, and an adjustable torque zone for screwdriving mode. This is achieved through the mode setting device that can selectively engage different torque transmission mechanisms based on the selected operating mode.
2Reliability
If the pressure ring is axially fixed to the gearbox housing, then torque limitation is prevented in impact drilling and drilling modes, but the mode setting device cannot provide torque adjustment for screwdriving mode
Solution Approach 1:
The mode setting device acts as an intermediary mechanism between the user input (mode setting sleeve) and the torque coupling system. It translates rotational movement into axial positioning of the pressure ring, enabling reliable mode switching between fixed torque coupling (impact drilling/drilling) and adjustable torque coupling (screwdriving) without compromising the stability of either state.
3Measurement precision
If circumferential grooves on the gearbox housing interlock with the projection on the pressure ring, then setting accuracy is maintained over long periods, but the axial adjustment mechanism becomes more complex
Solution Approach 1:
The patent uses circumferential grooves on the gearbox housing that interlock with a projection on the pressure ring to maintain precise axial positioning. This dimensional constraint in the circumferential direction ensures high setting accuracy over long operating periods while the axial adjustment is achieved through the mode setting device's rotational-to-axial movement conversion.
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
Ensures high setting accuracy and reliable operation over time by allowing precise torque control and mode switching, preventing torque limitation in percussion and drilling modes while allowing adjustable torque in screwing mode, thus enhancing the drill's versatility and longevity.
Implementation Method 1
a spring assembly (10) which exerts an axial force on the pressure ring (9)
Implementation Method 2
a detent mechanism in which a sinusoidal or sawtooth wave profile is scanned, and the resulting axial movement is transmitted to the tool spindle (4)
Implementation Method 3
a gearbox coupled to the drive unit, for example, a planetary gearbox
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A drill with impact drilling, drilling, and screwdriving functions has a gearbox for transmitting the drive motion of a drive unit to a tool spindle (4). Furthermore, two detent elements (16, 17) are provided, which are engaged in the impact drilling position and disengaged in the drilling or screwdriving position. A mode setting device (7) has a rotatable support ring (8) and a pressure ring (9) that is rotationally fixed to the support ring (8) and is axially displaceable on the gearbox housing (3) in the screwdriving position.