Sealing Device Cooling Tray via Differential Pressure
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Solution Overview
Problem
Thin-walled plastic trays deform due to heat generated during the sealing process on conventional tray sealing machines, particularly in vacuum skin packaging, where the preheated top film transfers heat to the tray, leading to undesirable material distortion.
Innovation Solution
A sealing device with a lower tool part equipped with a cooling device that uses differential pressure to effectively dissipate heat from the tray by pressing or pulling it against a cooling surface, preventing material distortion by maintaining the tray below a critical temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the top film is preheated to achieve desired elasticity for sealing, then the sealing quality is improved, but heat is transferred to the thin-walled tray causing material distortion
Solution Approach 1:
The tray is cooled in advance before the sealing process begins. The cooling device is activated prior to sealing to establish a temperature gradient that protects the tray from heat transfer during subsequent sealing operations, preventing material distortion while allowing proper sealing to occur.
Solution Approach 2:
A cooling device acts as an intermediary between the tray and the heat source (preheated top film). This cooling device absorbs and dissipates heat away from the tray during the sealing process, serving as a thermal buffer that protects the tray from direct heat exposure while allowing the sealing process to proceed.
2Device complexity
If conventional sealing without cooling is used, then the sealing process is simple, but thin-walled trays deform due to heat absorption
Solution Approach 1:
The cooling device is integrated into the lower tool part of the sealing device, merging the cooling function with the existing sealing structure. This combination allows the sealing process to include cooling capabilities without requiring a completely separate cooling system, thus limiting the increase in device complexity while achieving the desired protection against tray deformation.
3Temperature
If the tray is pressed against the cooling surface with high differential pressure, then heat dissipation is improved, but the force required increases
Solution Approach 1:
The cooling surface is designed to match the geometry of the tray, creating a form-fitting interface that increases the contact surface area. This geometric adaptation allows heat dissipation to occur over a larger area, reducing the need for high differential pressure to achieve effective cooling, thus distributing the required force more efficiently.
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 material distortion by ensuring the tray remains below a critical temperature during the sealing process, allowing for the production of thin-walled packaging without significant deformation.
Implementation Method 1
The achievable heat transfer performance for cooling the tray depends on the differential pressure acting on the tray, by means of which the tray is pressed or pulled into contact with the surface used for cooling
Implementation Method 2
The sealing device is designed to generate a differential pressure that holds the tray against the tray-cooling surface of the cooling device
Data Source
Figure 1
Figure 2
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AI summary
The invention relates to a sealing device (3) for a tray sealing machine (1), comprising a lower tool part (8) with a cooling device (10) by means of which at least one tray (T) can be cooled, and an upper tool part (9) with a sealing unit (29) by means of which a sealing process for sealing at least one tray (T) received in the lower tool part (8) with a top film (6) can be carried out, wherein the cooling device (10) forms at least one surface (14a, 14b) in contact with the tray (T) received in the lower tool part (8) for cooling the tray (T), wherein the sealing device (3) is designed to generate a differential pressure (P) that holds the tray (T) against the cooling surface (14a, 14b) of the cooling device (10) at least temporarily during the sealing process and/or at least temporarily after the sealing process. Furthermore, the invention relates to a method for cooling at least one tray (T).