Blow Pin Integration in Thermoplastic Blow Molding
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Solution Overview
Problem
Existing methods for producing extrusion blow-molded plastic articles with built-in parts, such as fuel tanks, require complex and expensive tools due to the need for precise insertion and fixation of components during the molding process, which complicates the integration of functional components like pumps and sensors.
Innovation Solution
A method involving a tubular preform introduced into a multi-part blow mold, where a first holding means (loading mandrel) positions the built-in part, and a second holding means (blow pin) pierces the preform's wall to secure and expand it using differential pressure, simplifying the tooling required and optimizing the number and size of openings on the finished container.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If slides / preformers are provided in the tool to fix the built-in part, then the built-in part can be securely fixed in the preform, but the tool becomes relatively expensive and complex
Solution Approach 1:
The patent combines the fixation function and the blowing function into a single blow pin. The blow pin serves dual purposes: it pierces the preform wall to secure the built-in part (fixation function) and simultaneously serves as the medium through which pressure medium is introduced to expand the preform (blowing function). This eliminates the need for separate slides or preformers, thereby reducing tool complexity while maintaining reliable fixation of the built-in part.
Solution Approach 2:
The blow pin is designed as a multi-functional element that performs multiple operations: it acts as a piercing tool to create an opening in the preform, serves as a fixation means to secure the built-in part in position, and functions as a conduit for introducing pressure medium for the blowing process. This multi-functionality replaces what would traditionally require multiple separate tool components, thus reducing overall device complexity.
2Manufacturing precision
If multiple separate holding means are used for insertion and fixation, then precise positioning is achieved, but the number of openings and tool complexity increases
Solution Approach 1:
The patent merges the positioning and fixation operations into a single step performed by the blow pin. As the blow pin pierces the preform wall and the built-in part is introduced, the part becomes fixed in position through the piercing action itself, eliminating the need for separate positioning fixtures or multiple holding means. This reduces the number of openings required in the tool while maintaining precise positioning of the built-in part.
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 approach reduces tool complexity and cost while enabling efficient integration of built-in parts, particularly in fuel tanks, by using the blow pin for both fixation and expansion, resulting in a more streamlined production process with fewer necessary openings on the finished product.
Implementation Method 1
the preform is expanded and deformed by the application of pressure medium with the second holding means or by the second holding means itself
Data Source
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AI summary
The invention relates to a method for producing an item made of thermoplastic plastic, wherein a tubular preform (1) is introduced into a multi-part blow mold (3a, 3b) and expanded and molded under the application of differential pressure, wherein at least one insert part is introduced into the preform by means of a first retaining means before the preform is molded and wherein the insert part is taken over by at least one second retaining means piercing the wall (7) of the preform before the preform is molded, wherein the second retaining means is designed as a blowing mandrel (8) and the preform is expanded and shaped by the application of a pressure medium using the second retaining means.