Packaging Machine Tensioning Device with Dual Drive Rollers
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Solution Overview
Problem
Existing packaging machines for producing sealed packages of pourable products face challenges in maintaining precise and reliable tension control of the packaging material, leading to variations in package formation and quality.
Innovation Solution
The packaging machine incorporates a tensioning device with multiple rollers and motors, including a second drive roller with a servo motor, and a control unit that adjusts the angular speed and acceleration of the rollers to maintain consistent tension, using a free loop mechanism to compensate for cyclic forces and variations in advancement speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a tensioning assembly with a single drive motor is used to control web tension, then the device complexity is reduced, but the manufacturing precision and reliability of tension control deteriorate due to uncontrolled tension variations
Solution Approach 1:
The tensioning assembly is segmented into two independently controllable drive rollers (first drive roller and second drive roller), each equipped with its own drive motor. This segmentation allows independent control of each roller's angular speed, enabling precise tension control by coordinating the rotation of both rollers rather than relying on a single drive mechanism.
Solution Approach 2:
The control unit dynamically adjusts the angular speed parameter of the second drive roller based on real-time tension feedback and the cyclic operational phase. By varying the rotation speed parameter of the second roller while the first roller maintains constant speed, the system compensates for tension variations without requiring complex mechanical adjustments.
2Reliability
If the second drive roller is controlled with variable angular speed to compensate for cyclic forces, then the reliability of tension control is improved, but the device complexity increases due to additional control requirements
Solution Approach 1:
The control unit implements a feedback mechanism that monitors the cyclic operational phase and tension conditions, then adjusts the angular speed of the second drive roller accordingly. This closed-loop control ensures that tension variations caused by cyclic forces (such as package formation and cutting operations) are automatically compensated, maintaining reliable tension control throughout the production cycle.
Solution Approach 2:
The control system applies periodic speed adjustments to the second drive roller that correspond to the cyclic nature of the packaging operation. By synchronizing the variable speed control with the operational cycle (filling, sealing, cutting phases), the system proactively counteracts anticipated tension variations rather than merely reacting to them.
3Ease of operation
If constant rotation speed is maintained for simplicity, then the ease of operation is improved, but the manufacturing precision deteriorates due to inability to compensate for speed variations
Solution Approach 1:
The drive system is divided into two independent roller control channels, allowing one roller (first drive roller) to operate at constant speed for simplicity while the other roller (second drive roller) handles variable speed control for precision. This segmentation separates the simple constant-speed function from the complex variable-speed compensation function.
Solution Approach 2:
The second drive roller acts as an intermediary element between the constant-speed web feed and the cyclic package formation process. By positioning this roller as the controlled variable-speed element, it mediates between the simple constant-speed operation and the complex cyclic forces, absorbing the variability through its adjustable speed while maintaining overall system simplicity.
Data Source
AI summary
A packaging machine includes a conveying device for advancing a packaging material web at least to a tube forming station at which the web is formed into a tube and for advancing the tube to a tube forming and sealing device to form and longitudinally seal the tube, a tensioning device to control tension of the web and/or of the tube and a control unit to control operation of the packaging machine. The tensioning device has at least one tensioning assembly having at least first and second drive rollers, a first drive motor connected to the first drive roller to rotate the first drive roller and a second drive motor connected to the second drive roller to rotate the second drive roller. The control unit controls the first and second drive motors such that a free loop of the web expands and/or advances between the first and second drive rollers.