Pneumatic Dancer Device Torque Transmitter for Low Tension Control
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Solution Overview
Problem
Existing dancer devices face challenges in maintaining a constant tensile force, especially for long goods sensitive to tension, due to inertia and breakaway torque issues when using electric motors for restoring moments, particularly at low pull-off forces less than 30 N.
Innovation Solution
A torque transmitter is used that generates a restoring torque independent of the dancer arm's position, utilizing a compressed air source to create an imbalance and adjust the pivot axis, allowing for precise control of tensile force without significant increases, even with small speed deviations, and featuring a pointer-shaped lever with air gaps for contact-free operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If an electric motor is used to apply restoring moment to the dancer arm, then the tensile force can be regulated, but the inertia of the rotor and breakaway torque from standstill cause problems for low pull-off forces
Solution Approach 1:
The patent replaces the electric motor-driven torque transmitter with a pneumatic torque transmitter that uses compressed air to generate restoring torque. This substitution eliminates the rotor inertia and breakaway torque problems associated with electric motors, enabling precise control of low tensile forces less than 30 N while maintaining the ability to regulate the dancer arm position.
Solution Approach 2:
The invention employs a pneumatic system where compressed air acts on a pointer-shaped lever to generate the restoring torque. The pneumatic torque transmitter uses air pressure to create the necessary counterbalancing force on the dancer arm, providing smooth, inertia-free control that is particularly suitable for tension-sensitive long goods with very low pull-off forces.
2Speed
If the dancer arm is deflected from its target position to control line speed, then speed deviations can be corrected, but this causes momentary increase in tensile force for tension-sensitive long goods
Solution Approach 1:
The patent implements a feedback control system where the angular position of the dancer arm is continuously detected and used to generate a control signal that adjusts the drive speed. This closed-loop feedback enables correction of speed deviations without requiring large deflections of the dancer arm, thereby maintaining tensile force within narrow limits even for tension-sensitive long goods.
Solution Approach 2:
The pneumatic torque transmitter provides dynamically adjustable restoring torque that can respond quickly to speed deviations without causing abrupt changes in tensile force. The pneumatic system's inherent compliance allows for smooth, gradual adjustments that maintain force stability while correcting speed variations in real-time.
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 solution maintains the lowest possible tensile force levels and allows for sensitive regulation, reducing breakaway effects and maintaining constant draft in the processing line, even with small speed changes, by using a torque transmitter with minimal mass inertia and adjustable air pressure.
Implementation Method 1
the torque transmitter should be acted upon by a compressed air source in one direction of rotation of the dancer arm, so that the torque transmitter is not acted upon by compressed air in the opposite direction
Implementation Method 2
the sealing of the lever with respect to the surfaces of the housing swept by the lever takes place only via air gaps which are small in size but always remain contact-free
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a dancer device (1) for drawing off elongated products (2), wherein the restoring torque is produced by a torque transmitter (40), the torque being independent of the respective rotational orientation of the dancer arm (6).