Thermoplastic Film Stretching Machine with Localized Assistance Sub-assemblies
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Solution Overview
Problem
Current thermoplastic film stretching machines face limitations in achieving high negative stretching rates and varying clamp spacings, leading to inadequate film quality and mechanical stress on drive chains, especially when stretching films at low temperatures or requiring simultaneous transverse and negative longitudinal stretching.
Innovation Solution
The introduction of localized assistance sub-assemblies within the heating tunnel, featuring thrust members and adjustable drive systems, which relieve the drive chain of significant forces and allow for closer gripper spacing and real-time speed adjustments to manage stretching forces effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high negative stretching rates are implemented, then film quality improves, but mechanical stress on drive chains increases significantly
Solution Approach 1:
The patent divides the stretching function into two independent systems: a first stretching means for longitudinal stretching and a second stretching means for transverse stretching. This segmentation allows each system to be optimized independently, enabling high negative stretching rates to be achieved through the transverse stretching system without overwhelming the longitudinal drive chains, thus improving film quality while managing mechanical stress.
Solution Approach 2:
The patent introduces a heating tunnel as an intermediary element that heats the film before stretching. By pre-heating the film to make it more pliable, the required stretching forces are reduced, allowing high negative stretching rates to be achieved with less mechanical stress on the drive chains.
2Productivity
If clamp spacing is reduced for higher stretching rates, then productivity improves, but drive chain forces increase
Solution Approach 1:
By segmenting the stretching function into longitudinal and transverse components, the patent allows closer clamp spacing to be used in the transverse direction without proportionally increasing the load on the longitudinal drive chains. The transverse stretching means can operate independently at high speeds with reduced spacing, improving productivity while the longitudinal system maintains manageable force levels.
3Manufacturing precision
If simultaneous transverse and negative longitudinal stretching is implemented, then film quality improves, but device complexity increases
Solution Approach 1:
The patent achieves simultaneous transverse and negative longitudinal stretching by using two independent stretching means operating in parallel. The longitudinal stretching means handles the longitudinal direction while the transverse stretching means handles the transverse direction. This segmented approach enables complex simultaneous stretching operations while keeping each individual system relatively simple and manageable.
4Use of energy by moving object
If stretching is performed at low temperatures, then energy consumption decreases, but stretching forces increase significantly
Solution Approach 1:
The patent uses a heating tunnel as an intermediary that pre-heats the film before stretching. This controlled heating makes the film more pliable, allowing stretching to be performed with significantly reduced forces. The heating tunnel acts as a mediator between the energy input and the stretching process, enabling low-temperature stretching to achieve adequate film ductility without requiring excessive stretching forces.
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 enables higher negative stretching rates with improved film quality and reduced mechanical stress on the drive chain, allowing for a wider range of clamp spacings and adaptable stretching settings without mechanical intervention, effectively addressing the limitations of existing machines.
Implementation Method 1
a heating tunnel 2 allowing the heating of the plastic material of the film F to be stretched
Implementation Method 2
at least one assistance sub-assembly (10) including a plurality of thrust members (20) connected in succession to said chain or belt... capable, at the level of this strand, of pushing said slides (8)
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
This machine includes a pair of guide rails (5i, 5e) on each side of the film and assemblies of slides (6, 8) respectively movable on these respective rails and connected by connecting rods (7); the machine also includes at least one assist sub-assembly (10) including: - an endless chain or belt (16); - a plurality of thrust members (20), connected to said chain or belt (16) in succession to one another and projecting from said chain or belt (16), and - a means (21) for driving said chain or belt (16), several thrust members (20) being brought into the path of the slides (8) connected to the film gripping clips (4) (F), so that at least one of the thrust members (20) comes to bear against at least one of these slides (8) and exerts on this slide a thrust to assist the movement of this slide along the rail (5e) on which this slide moves.