Single-Piece Gas-Assisted Injection Molding for Supermarket Trolley Handles
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Solution Overview
Problem
Existing push handles for supermarket trolleys are complex and costly to manufacture due to their multi-piece construction, requiring multiple molds and more plastic material, which results in higher weight and lower robustness.
Innovation Solution
A single-piece push handle is created using partly gas-assisted injection molding, where a central plastic portion is formed in a main mold cavity, and pressurized gas is used to transfer plastic material into secondary cavities to form hollow L-shaped side portions, eliminating the need for assembly and reducing plastic usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple separate plastic pieces are used to form the push handle, then the structural complexity is reduced for assembly, but the manufacturing cost increases and the weight increases
Solution Approach 1:
The patent merges multiple separate plastic pieces into a single integrated push handle component. The handle, shelf, and side portions are formed as one unified piece through gas-assisted injection molding, eliminating the need for separate assembly operations while reducing the total amount of plastic material required compared to multiple discrete components.
2Ease of manufacture
If multiple separate plastic pieces are used to form the push handle, then the manufacturing process becomes simpler in terms of molding, but the production cost increases and productivity decreases
Solution Approach 1:
The manufacturing process merges multiple molding operations into a single gas-assisted injection molding cycle. The handle, shelf, and side portions are all formed in one continuous process within a single mold, eliminating sequential molding steps and assembly operations, thereby significantly improving production efficiency while maintaining ease of manufacture.
3Strength
If more plastic material is used to form the push handle, then the robustness decreases, but the manufacturing cost increases
Solution Approach 1:
The patent employs gas-assisted injection molding where pressurized gas is injected into the mold cavity during the molding process. This creates hollow sections within the plastic parts, reducing the overall amount of plastic material required while maintaining structural integrity and robustness through the optimized hollow geometry and material distribution.
Solution Approach 2:
The invention changes the physical parameters of the plastic material during processing by controlling the injection pressure, gas pressure, and cooling conditions. These parameter changes enable the formation of hollow sections with optimized wall thicknesses that provide sufficient strength and robustness while minimizing material usage.
4Weight of moving object
If a single-piece construction is used, then the manufacturing complexity increases, but the weight is reduced and robustness is improved
Solution Approach 1:
The gas-assisted injection molding process uses pressurized gas to create hollow sections within the single-piece push handle. This technique reduces the weight by removing unnecessary material while maintaining structural strength, and the integrated single-piece design eliminates assembly joints that would add weight and potential failure points.
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 method simplifies manufacturing, reduces material costs, and results in a lighter, stronger push handle with reduced weight and lower production costs while maintaining robustness.
Implementation Method 1
supplying a dual flow of a pressurized gas, into two secondary cavities of the mold
Implementation Method 2
partly gas-assisted injection molding
Data Source
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AI summary
A push handle (1) for supermarket trolleys having a central shelf portion (2) and two essentially L-shaped side portions (3), characterized in that it is formed of one single piece of plastic material made by partly gas-assisted injection molding, with the two side portions (3) having a hollow conformation.