Hot Wire Cutting for Plastic Container Separation
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Solution Overview
Problem
Current blow molding methods for manufacturing plastic containers, such as fuel tanks, face issues with incomplete separation of container halves due to the formation of plastic links or threads during the tearing process, leading to quality defects and inefficiencies in the manufacturing process.
Innovation Solution
The method involves using a blow-molding tool with a hot wire cutting element to thermally sever any unintentionally formed plastic links or threads during the lateral tearing process, ensuring clean separation of the container halves, and employing a mechanism where the mold parts can be closed to generate internal pressure using a gaseous pressurizing medium to pre-mold the container before complete separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If lateral tearing is used to separate container halves, then separation is achieved, but plastic links or threads form causing incomplete separation
Solution Approach 1:
The harmful plastic links and threads are extracted from the container halves using a hot wire cutting element that severs them thermally, removing the defect caused by incomplete separation
Solution Approach 2:
The mechanical tearing process is supplemented by introducing thermal energy through a hot wire cutting element, replacing purely mechanical separation with a combined thermal-mechanical process to achieve cleaner separation
2Manufacturing precision
If mold parts are closed completely for blow molding, then container shape is formed, but access to container interior for inserting built-in parts is lost
Solution Approach 1:
The container interior is accessed and built-in parts are inserted before the mold parts are completely closed and the blow molding process begins, performing the necessary operation in advance when access is still possible
Solution Approach 2:
The mold parts transition from an open state allowing access to a closed state for forming, dynamically changing their configuration to enable both operations at different stages of the process
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 ensures precise and complete separation of container halves, reduces manufacturing defects, and allows for the integration of built-in parts during the production process, enhancing the efficiency and quality of plastic container manufacturing.
Implementation Method 1
a hot wire cutting element (181) is disposed between the stationary inner holding claws (141) and the movable outer tearing claws (142) and is laterally displaceable, on account of which the plastic links and/or plastic threads (A') are severed
Implementation Method 2
closing the molding tool (100) and molding or pre-molding from the preform (200) a container (220) by internal pressure, that is to say by generating an internal pressure in the interior region of the preform (200) by way of a gaseous pressurizing medium
Data Source
AI summary
A method for manufacturing a plastic container by internal pressure forming including positioning a tubular preform between the die parts of a molding die having a die cavity; closing the molding die and forming or preforming a container from the preform using internal pressure, wherein a peripheral portion of the preform is pressed out of the die cavity through a die gap; laterally withdrawing the peripheral portion pressed out of the die cavity, as a result of which the container is divided into two container halves; and thermally separating plastic bridges and/or plastic threads which arise during the lateral withdrawal of the peripheral portion. Also disclosed is a molding die suitable for carrying out the method.