Thermal Back Seam Welder for Thermoplastic Bags
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Solution Overview
Problem
Existing bag production machines are unable to weld the back seam of bags using only heat and compression without the use of adhesives, hot melt glue, or stitching, which are distinct from the bag material.
Innovation Solution
A thermal back seam welder that heats and compresses thermoplastic sheet material to form a welded back seam, using a weld heater and compression mechanism, while breaking incidental welds with a weld breaker to ensure the seam is formed solely from the bag material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive, hot melt glue, stitching or other separate materials are used to seal bag seams, then sealing reliability is improved, but device complexity and material usage increase
Solution Approach 1:
The invention extracts and eliminates the need for separate sealing materials (adhesives, hot melt glue, stitching) by implementing a thermal welding system that directly fuses the thermoplastic panels together through heat and compression, achieving sealing without additional materials
Solution Approach 2:
The invention replaces mechanical sealing methods (stitching, adhesives) with a thermal field-based welding system that uses heated rollers to melt and fuse the thermoplastic material, substituting mechanical fastening with thermal bonding
2Reliability
If adhesive, hot melt glue, stitching or other separate materials are used to seal bag seams, then sealing reliability is improved, but production cost increases
Solution Approach 1:
The invention removes the requirement for separate sealing materials by implementing direct thermal welding of the thermoplastic panels, eliminating consumption of adhesives, hot melt glue, and stitching materials
Solution Approach 2:
The invention achieves sealing using the same thermoplastic material that forms the bag panels themselves, creating a homogeneous structure where the seam is made of the same material as the bag body, eliminating the need for heterogeneous sealing materials
3Quantity of substance
If thermal welding is used to seal bag seams, then material usage is reduced, but manufacturing precision must be controlled
Solution Approach 1:
The invention incorporates a preheating assembly that preheats the thermoplastic panels before they enter the main welding zone, ensuring the material is at the appropriate temperature for welding and reducing variability in welding outcomes
Solution Approach 2:
The invention uses heated rollers with controlled temperature and pressure that apply consistent thermal and mechanical energy to the overlapping panels, maintaining precise control over the welding process to ensure uniform seam formation
4Manufacturing precision
If a weld breaker is added to break incidental welds, then seam formation accuracy is improved, but device complexity increases
Solution Approach 1:
The weld breaker extracts and removes the harmful incidental welds that form between overlapping panels during the thermal welding process, eliminating defects that would compromise seam quality
Solution Approach 2:
The invention converts the harmful effect of incidental welds (which create defects) into a benefit by using the controlled breaking action to define the precise seam location and ensure clean separation of panels, improving overall seam accuracy
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 the rapid production of bags with sealed back seams using only heat and compression, eliminating the need for additional materials like adhesives or stitching, and ensuring the seam is integral to the bag's structure.
Implementation Method 1
heating the sheet material along the overlap region with a weld heater
Implementation Method 2
compressing the first and second panel segments together with a compression mechanism downstream of the weld heater to form a welded back seam
Implementation Method 3
breaking incidental welds extending between the welded back seam and the first panel with a weld breaker
Data Source
AI summary
A thermal welder is configured to weld a back seam of a bag formed of thermoplastic sheet material. The welder may include a weld heater and a compression mechanism downstream of the weld heater to compress the sheet material to form the back seam. The welder may also include a weld breaker downstream of the compression mechanism to break apart incidental welds which are formed adjacent the back seam.