Clamping Device Motor Current Control
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Solution Overview
Problem
Existing clamping devices require separate position sensors to determine the clamped or relaxed state, which can be cumbersome and require precise current consumption measurements for electric motor-driven systems.
Innovation Solution
The clamping device uses electrical operating variables of the electric motor, such as motor current, to measure the clamping force, allowing the motor to be switched off when the desired force is reached, eliminating the need for precise current consumption measurements and enabling contact detection with the workpiece.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate position sensors are used to determine the clamping position, then the position detection is reliable, but the device complexity increases
Solution Approach 1:
The patent combines the position detection function with the existing electric motor by utilizing its encoder, eliminating the need for separate position sensors. The encoder that already exists for motor control is repurposed to determine clamping position, merging two functions into one component.
Solution Approach 2:
The encoder of the electric motor is given multiple functions: it serves both for motor control and for position detection of the clamping element. This multi-functionality reduces the overall number of components needed in the system.
2Measurement precision
If current consumption measurement is used to determine clamping force, then the measurement precision is high, but the ease of operation decreases
Solution Approach 1:
The patent replaces complex mechanical measurement systems with electrical measurements. By using the electric motor's current consumption and encoder data, the system determines clamping force electronically rather than through mechanical sensors, simplifying the overall system while maintaining precision.
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 allows for precise control of clamping force without the need for separate position sensors, improving efficiency and reliability in clamping processes by using the motor's current and revolution count to determine the clamping force and switch-off time.
Implementation Method 1
an electric motor (10, 33, 31) for mechanically driving the clamping element (2, 38, 25, 26)
Implementation Method 2
a first spring element (9, 39, 30) which is loaded during a tensioning process and relieved during a relaxation process
Implementation Method 3
the first spring element pressing the clamping element with a specific spring force
Implementation Method 4
a second spring element forming a frictional connection between the electric motor and the tensioning element during a relaxation process
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
The invention relates to a clamping device (1), for example swing tensioners (1), bracing elements, machine vises or block cylinders, with a movable clamping element (2) for clamping a workpiece with a defined clamping force, and with an electric motor (10) for mechanically driving the clamping element (2), also with a control unit that controls the electric motor (10). The invention provides that the control unit detects an electrical operating parameter of the electric motor (10) as a measure of the clamping force. The contact of the clamping element with the workpiece is detected in this manner. Subsequently, the electric motor (10) is then driven further by a defined number of revolutions, the number of revolutions after contact with the workpiece defining the clamping force. The invention further comprises a corresponding control method.