Vacuum Forming Machine Pressure Control for Sheet Sagging
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Solution Overview
Problem
Existing vacuum forming machines struggle to prevent sagging of decorative sheets during the forming process, leading to misalignment and a ruined appearance of the final vacuum formed product, especially when dealing with base members of varying surface unevenness.
Innovation Solution
A vacuum forming machine equipped with temperature and pressure sensors, and a controller that adjusts the pressure difference between upper and lower boxes based on real-time temperature and pressure data, allowing independent control of pressure reduction in each space to maintain the decorative sheet's position and prevent sagging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the decorative sheet is heated to soften it for attachment, then the adhesive achieves sufficient adhesiveness, but the decorative sheet sags and loses its position
Solution Approach 1:
The patent applies preliminary anti-action by creating a counter-pressure environment before the harmful effect (sagging) occurs. The lower box maintains higher pressure than the upper box during heating, which counteracts the gravitational force on the softened sheet and prevents sagging before it can ruin the appearance. This preventive measure is taken in advance during the heating phase rather than correcting sagging after it occurs.
Solution Approach 2:
The patent changes the pressure parameter dynamically during the process. Specifically, it maintains a pressure difference between the upper and lower boxes, with the lower box at higher pressure during heating to prevent sagging, then adjusts pressures for the vacuum forming stage. This parameter change allows the sheet to be heated sufficiently for adhesive activation without experiencing excessive sagging.
2Manufacturing precision
If the pressure inside the chamber is reduced to attach the sheet to the base member, then the sheet conforms to the surface shape, but the base member may expand or collapse
Solution Approach 1:
The patent segments the pressure control into two independent spaces: the upper box containing the sheet and the lower box containing the base member. This segmentation allows different pressure conditions to be applied to each space simultaneously. The upper box can be evacuated to create vacuum for sheet attachment, while the lower box maintains higher pressure to support the base member structure and prevent collapse or expansion.
Solution Approach 2:
The patent applies local quality by creating different pressure conditions in different locations. The upper space has low pressure to enable sheet conforming, while the lower space has higher pressure to maintain base member integrity. This localized pressure differentiation allows both requirements to be satisfied simultaneously in their respective regions.
3Reliability
If the upper and lower boxes are connected airtight for vacuum forming, then the forming process can proceed, but the volume requirements constrain the machine size
Solution Approach 1:
The patent applies dynamics by making the partition wall between upper and lower boxes movable rather than fixed. This movable partition allows the volumes of the two spaces to be adjusted dynamically based on the specific forming requirements. When small parts are being formed, the volumes can be reduced, thereby reducing the overall machine size while still maintaining the ability to create the necessary vacuum forming conditions.
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
The solution effectively prevents sagging of the decorative sheet, ensuring a precise and aesthetically pleasing attachment to the base member, even with complex surface shapes, and allows for reduced machine size due to independent pressure control and volume flexibility.
Implementation Method 1
the decorative sheet 10 is heated with the heater 528
Implementation Method 2
the upper and lower chamber boxes 522 and 524 are evacuated by establishing communication with the vacuum tank 507, thereby creating a reduced pressure state
Implementation Method 3
if compressed air is introduced into the upper chamber box 522 by making the upper chamber box 522 communicate to the compressed air tank 508, the decorative sheet 10 is pressed more strongly against the base member 16
Implementation Method 4
an adhesive is applied onto the surface of the decorative sheet 10
Data Source
AI summary
A vacuum forming machine includes a holder arranged to hold a decorative sheet, upper and lower boxes separated by the decorative sheet and the holder, a pressure reducer arranged to reduce pressures inside the upper and lower boxes, a first valve arranged to adjust a degree of pressure reduction inside the upper box, a second valve arranged to adjust a degree of pressure reduction inside the lower box, a heater arranged to heat the decorative sheet, a temperature information collector arranged to collect temperature information about the temperature of the decorative sheet, and a controller programmed to control opening/closing operations of the first and second valves by reference to the temperature information while the pressure reducer is operating.