Plastic Vessel Welding with Thinned Angular Edges
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Solution Overview
Problem
Traditional methods for manufacturing plastic containers, such as extrusion blow molding and injection blow molding, face issues like slow production, aesthetic defects, irregular material thickness, and difficulty in achieving high-quality, smooth, and regularly shaped containers suitable for cosmetic or pharmaceutical products, due to limitations in mold design and material adaptation.
Innovation Solution
A method of welding a neck and a body of a plastic container using thinned edges with angular contact surfaces, where a force is applied to cause elastic deformation and localized melting, followed by cooling, to create a bead-free weld, allowing for precise control of the welding process and material thickness, and using ultrasound or rotational energy to facilitate the welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If extrusion blow molding or injection blow molding is used, then containers can be produced with basic functionality, but production speed is slow and productivity is limited
Solution Approach 1:
The container is divided into two separately manufactured parts (first part and second part) that are welded together. This segmentation allows each part to be optimized independently for both production efficiency and thickness uniformity, resolving the contradiction between productivity and manufacturing precision
Solution Approach 2:
The invention replaces traditional mechanical blowing processes with a welding-based assembly process. By substituting the single-step blowing mechanism with separate manufacturing followed by welding, the system achieves both higher productivity and better thickness control
2Ease of manufacture
If traditional blowing molds are used, then containers can be manufactured, but aesthetic defects appear due to ribs along the parting line
Solution Approach 1:
By dividing the container into two parts welded together, the invention eliminates the parting line that causes aesthetic defects in traditionally molded containers. The welding joint can be positioned and finished to provide a smoother, more aesthetically pleasing surface
Solution Approach 2:
The invention changes the manufacturing parameters from single-step blowing to two-step manufacturing with welding. This parameter change allows for better control of surface quality and elimination of parting line defects while maintaining ease of manufacture
3Ease of manufacture
If molding processes are used, then containers can be produced, but thermal equilibrium cannot be achieved due to two moving parts in the mold
Solution Approach 1:
The invention segments the manufacturing process into separate steps for each part, allowing each part to be manufactured under optimal thermal conditions independently. This eliminates the thermal equilibrium problems caused by moving parts in traditional two-part molds
4Ease of manufacture
If air vents are used in molds, then air can be evacuated during blowing, but surface defects occur and shiny surfaces cannot be obtained
Solution Approach 1:
The invention replaces the air venting mechanism with a welding-based assembly process. By eliminating the need for air evacuation during manufacturing, surface defects are prevented and high-quality shiny surfaces can be achieved
5Ease of manufacture
If direct contact with ambient air at extruder outlet is allowed, then material can be extruded, but climatic variations affect adjustment parameters and generate faults
Solution Approach 1:
The invention replaces the extrusion process with injection molding and welding. This substitution eliminates the direct contact between molten material and ambient air, thereby preventing climatic variations from affecting process parameters and improving reliability
6Ease of manufacture
If blow molding parameters are optimized for one material, then that material can be processed, but changing material requires changing the mold
Solution Approach 1:
The welding-based assembly process serves as a universal joining method that can accommodate different materials without requiring mold changes. This multi-functional approach enables the same manufacturing system to process various materials, improving adaptability and versatility
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 enables the production of high-quality, smooth, and regularly shaped containers with consistent thickness, suitable for large quantities, and addresses the limitations of traditional methods by ensuring a seamless and aesthetically pleasing weld without visible burrs, making it suitable for containers used in the cosmetic and pharmaceutical fields.
Implementation Method 1
a supply of energy melts the plastic material of the contact surfaces then assembled together in hollowed out local areas in these surfaces to form a volume of molten material (E)
Implementation Method 2
This melting step is followed by a cooling step
Implementation Method 3
using ultrasound or rotational energy to facilitate the welding
Data Source
Figure 1~2
Figure 3a~3b
Figure 4a~4d
AI summary
The purpose of the invention is to provide any shape of high-quality vessels that can be easily manufactured in large quantities, and that can be used e.g. for cosmetics or pharmaceuticals. For this purpose, the invention comprises making a vessel by welding parts having edges with a reduced thickness and having different leading angles. A vessel according to the invention comprises contact walls (401, 402) of the neck (41) and/or the body (42) to be welded, that have a partially and linearly reduced thickness. The contact walls (401, 402) of the members (41, 42) to be assembled then exhibit portions (Sa1 Sa') of the contact surfaces (Sc, Sc') inclined relative to the main axis (X'X) in order to form between them an angular gap of at least substantially 3 to 5° on a portion (Sa, Sa') of said contact walls. The dimensions of the contact walls (401, 402) are such that the contact wall of one member (41, 42) is brought into contact. The thin walls have a structure that is radially deformable during the advance of the wall. Welding is carried out between the contact surfaces (Sc, Sc'), once the advance has stopped, when the contact surfaces are opposite each other, which makes it possible to assemble the contact surfaces by the fusion of the plastic material in local areas (Zc, Zc') dug in said surfaces and defining a fusion space (E).