Tool Spindle Braking Torque Control for Power Tools
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric machine tools with tool-free clamping devices and spindle brakes face challenges in ensuring safe braking, as the moment of inertia can cause the tool to loosen, posing a risk of injury or damage, especially when the self-tightening clamping device's locking state is uncertain.
Innovation Solution
A method that determines the locking state of the tool on the spindle using sensors and adjusts the braking torque accordingly, applying a selected time-braking torque function or maximum braking torque to ensure safe and optimal braking without releasing the tool, using a combination of sensors to monitor locking force, imbalance, operating speed, angular acceleration, and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a brake arrangement is added to stop the tool spindle after switching off, then operational safety is improved by preventing the tool from continuing to rotate, but the moment of inertia causes the tool to loosen on the clamping device, creating a new safety risk
Solution Approach 1:
The braking torque is dynamically adjusted based on the detected locking state of the clamping device. The control unit selects from multiple braking torque functions or maximum braking torque values depending on whether the tool is securely locked, manually clamped, or in transition, allowing the braking behavior to adapt to the current mechanical state and prevent tool loosening
Solution Approach 2:
The system changes the braking parameter (braking torque magnitude) based on the locking state detection. Different locking states correspond to different braking torque levels, with lower braking torque applied when the locking state is uncertain or transitional, preventing the tool from loosening while still providing adequate braking when secure
2Ease of operation
If a tool-free clamping device with self-tightening function is used, then ease of operation is improved by eliminating manual tool attachment, but the locking state may be uncertain, making safe braking difficult to guarantee
Solution Approach 1:
A sensor arrangement provides feedback about the locking state of the clamping device to the control unit. The sensor detects parameters such as clamping force, position, or mechanical state, allowing the control unit to determine whether the tool is securely locked or in a transitional state, and adjust braking accordingly
Solution Approach 2:
The system performs preliminary detection of the locking state before applying full braking torque. By checking the locking state in advance through sensors and only applying appropriate braking torque after confirmation of secure locking, the system prevents tool loosening while maintaining ease of operation
3Productivity
If high braking torque is applied to quickly stop the spindle, then productivity is improved by reducing stop time, but the risk of tool detachment increases due to the moment of inertia
Solution Approach 1:
The braking torque parameter is changed based on the locking state detection. When secure locking is confirmed, higher braking torque can be applied for faster stopping. When locking state is uncertain or transitional, lower braking torque is applied to prevent tool detachment, optimizing both productivity and safety dynamically
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 ensures reliable and safe braking by matching the braking torque to the tool's locking state, preventing tool detachment and enhancing operational safety without the need for complex mechanical constructions, thus providing a balanced safety and simplicity in design.
Implementation Method 1
due to the inertia of the tool, it wants to move on with the remaining moment of inertia and transmits this moment of inertia to the clamping device
Data Source
Figure 1~2
Figure 3~5
AI summary
The invention relates to a method for braking a tool spindle (2) of a power tool (1), comprising the following steps: - Determining a locking state of a tool (3) on the tool spindle (2) by means of a sensor arrangement (5); - Selecting a time-braking torque function and/or a maximum braking torque (MB1, MB2) based on the determined locking state; and - Braking the tool spindle (2) by means of a braking arrangement (4) according to the selected time-braking torque function and/or in such a way that the selected maximum braking torque (MB1, MB2) is not exceeded.