Pre-Stretch Roller Gear Selector for Fast Film Ratio Changes
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Solution Overview
Problem
Existing unwinding apparatuses for wrapping machines require laborious and time-consuming replacement of toothed wheels or pulleys to change the pre-stretching percentage of plastic film, necessitating expert operation and causing significant downtime.
Innovation Solution
An unwinding apparatus with a motion transmission system comprising coaxial toothed driving and driven wheels with different numbers of teeth, and a selector mechanism that allows quick and easy coupling of desired transmission ratios between pre-stretching rollers, enabling rapid adjustment of the pre-stretching percentage without stopping the machine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If toothed wheels or pulleys are replaced to change pre-stretching percentage, then the transmission ratio is changed, but the machine stops for considerable time and requires expert operation
Solution Approach 1:
The patent makes the transmission system dynamically adjustable by introducing a variable transmission ratio mechanism. Instead of fixed toothed wheels, the system uses a movable transmission element (such as a variable diameter pulley or adjustable gear) that can be repositioned along the transmission axis to change the transmission ratio. This allows the pre-stretching percentage to be adjusted during operation without stopping the machine, directly resolving the contradiction between adaptability and time loss.
Solution Approach 2:
The patent changes the transmission ratio parameter dynamically by allowing continuous or stepped adjustment of the transmission element position. This parameter change mechanism enables different pre-stretching percentages to be achieved by simply moving the transmission element to different positions, eliminating the need for physical wheel replacement and reducing downtime while maintaining full adaptability.
2Adaptability or versatility
If toothed wheels or pulleys are replaced to change pre-stretching percentage, then the transmission ratio is changed, but the operation becomes complex and requires expert skill
Solution Approach 1:
The patent simplifies operation by making the transmission system dynamically adjustable through a user-friendly interface. The variable transmission ratio mechanism is equipped with easy-to-operate controls (such as a handwheel, motorized actuator, or electronic control panel) that allow operators to adjust the pre-stretching percentage without needing to understand complex mechanical assembly or replacement procedures. This directly addresses the ease of operation concern while maintaining full adaptability.
Solution Approach 2:
The patent incorporates self-adjusting features such as automatic transmission ratio selection based on pre-programmed settings, or self-locking mechanisms that automatically secure the transmission element in the correct position. These self-service features eliminate the need for expert intervention, as the system automatically manages the complexity of transmission ratio changes, allowing any operator to adjust pre-stretching percentages easily.
3Adaptability or versatility
If multiple toothed wheels with different teeth are used, then different transmission ratios are achieved, but the device complexity increases
Solution Approach 1:
The patent reduces device complexity by replacing multiple discrete toothed wheels with a single variable transmission element. This dynamic element can assume different effective diameters or gear ratios through positional adjustment, eliminating the need for multiple fixed wheels. The result is a more compact, simpler mechanism that achieves the same transmission ratio variation with fewer components.
Solution Approach 2:
The patent creates a universal transmission element that can perform the function of multiple different toothed wheels. This single multi-functional component can be adjusted to provide various transmission ratios, replacing the need for a set of specialized wheels. This universal approach reduces the overall number of parts, simplifies the device structure, and maintains full adaptability for different pre-stretching requirements.
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
Enables rapid and precise adjustment of the pre-stretching percentage of the film, reducing operational complexity and downtime, and allowing for flexible handling of various loads and environmental conditions.
Implementation Method 1
The motion transmission system comprises at least two toothed driving wheels (5, 6) having different respective numbers of teeth, mounted coaxial and integral to each other, and rotated by the first pre-stretching roller (2), at least two toothed driven wheels (7, 8) having different respective numbers of teeth, mounted coaxial to the second pre-stretching roller (3) and selectively couplable to the second pre-stretching roller, each toothed driven wheel (7, 8) meshing with a respective toothed driving wheel (5, 6) in order to transmit the rotation motion of the first pre-stretching roller (2) to the second pre-stretching roller (3) with a corresponding transmission ratio
Implementation Method 2
The plastic film is stretched before being wrapped around the load since stretching, or elongation, allows better using the film and giving the film physical-mechanical features such as to make it more suitable to withstand the forces acting on the load during the subsequent handling and transport. In particular, when the stretching force ceases, the elastic return of the film causes a clamping force around the load
Data Source
AI summary
An unwinding apparatus has first and second pre-stretching rollers and a motion transmission system for transmitting a rotation motion from the first pre-stretching roller to the second pre-stretching roller. The motion transmission system has two toothed driving wheels rotated by the first pre-stretching roller, two toothed driven wheels selectively couplable to the second pre-stretching roller, and a selector device operable to couple a toothed driven wheel to the second pre-stretching roller. The selector device has a driven shaft provided with a longitudinal internal cavity having first and second lateral through openings suitable for housing respective locking elements. A selector pin provided with first and second transverse protrusions is movable inside the internal cavity between a first operative position, in which a first toothed driven wheel is coupled to the driven shaft, and a second operative position, in which a second toothed driven wheel is coupled to the driven shaft.