Thermoplastic Resin Welding Device With Pneumatic Compression
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Solution Overview
Problem
Conventional welding methods for thermoplastic resin tubes face challenges such as pinhole formation, uneven pressure application, difficulty in handling heat-shrinkable tubes, and limited applicability to tubes with different diameters or configurations, including butt welding and flat articles.
Innovation Solution
A welding device that uses a compressor with adjustable pressure and heating mechanisms to ensure uniform compression and heating of thermoplastic resin articles, preventing pinhole formation and allowing for the welding of tubes with different diameters and configurations, including internal heating for combinations where the outer tube has a lower melting point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If external heating is used to weld thermoplastic resin tubes, then the welding process is simple, but the outer tube may deform before the inner tube melts when the outer tube has a lower melting point
Solution Approach 1:
The patent inverts the heating approach by placing the heat source inside the inner tube rather than outside the outer tube. This internal heating method ensures that the tube with the higher melting point (inner tube) is heated first and reaches melting temperature before the outer tube, preventing premature deformation of the outer tube while achieving proper weld quality.
2Force
If a pressurizing tube is used to compress the welding part, then the compression force can be applied, but the pressurizing tube cannot be quickly cooled after welding
Solution Approach 1:
The patent uses a blowout bag inflated with compressed air or nitrogen to provide the compression force. After welding, the gas supply is stopped and the gas is discharged, allowing the blowout bag to cool down rapidly. This pneumatic approach enables quick cooling and removal of the pressing unit, significantly reducing the loss of time compared to conventional pressurizing tubes.
3Force
If a heat-shrinkable tube is used for welding, then the overlapping parts can be compressed, but it is difficult to automate the setting and removal processes
Solution Approach 1:
The patent replaces the heat-shrinkable tube with an inflatable blowout bag that can be automatically inflated and deflated using compressed air or nitrogen supply systems. This allows for automated setting and removal processes, as the blowout bag can be quickly inflated to provide compression during welding and then rapidly deflated and removed without manual intervention, significantly improving automation capability.
4Device complexity
If the compressed surface region is not extended, then the welding process is simple, but pinholes remain in the welded part
Solution Approach 1:
The patent implements a dynamic compression process where the blowout bag is initially inflated to a first pressure to compress the welding part and force out air, then further inflated to a second higher pressure to extend the compressed surface region along the tube axis. This dynamic, two-stage pressure application eliminates pinholes by ensuring complete air evacuation and proper material flow, while the blowout bag's flexibility allows this complex process to be achieved with a simple device structure.
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 device achieves a smooth weld surface without pinholes, allows for precise pressure control, quick cooling of the compressor, and enables the welding of various thermoplastic resin articles with different sizes using a single device by replacing the pressing unit.
Implementation Method 1
a pump (5) connected to said compressor (3), for applying a fluid pressure to said blowout bag (4)
Implementation Method 2
a heater (6), for heating said thermoplastic resin articles (2a, 2b)
Implementation Method 3
a valve (8) connected to said compressor (3), for releasing said fluid pressure
Data Source
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AI summary
A welding device includes a compressor configured to compress a welding part and its adjoining surfaces of thermoplastic resin articles (2a, 2b) in directions perpendicular to the axis of a core (1), and a heater, and is configured such that: the surface of the welding part of the thermoplastic resin articles is compressed with a predetermined pressure by the compressor, the compression of the thermoplastic resin articles is then continued to extend a compressed region along the axis of the core without changing a relative position between the compressor in the compressed region and the surface of the welding part of the thermoplastic resin articles, the welding part of the thermoplastic resin articles is heated and welded by the heater, and after the welding, the pressure applied by the compressor is lowered to stop the compression of the thermoplastic resin articles such that the thermoplastic resin articles fitted on the core can be taken out of the welding device.