Seamless Threaded Plastic Container Mold Dynamics
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Solution Overview
Problem
Conventional molding processes for threaded containers often result in mold lock conditions, requiring cumbersome unscrewing or the use of segmented molds, leading to undesirable seams and flash on the threads.
Innovation Solution
The development of a molded plastic container with a seamless external thread segment, enhanced sealing end surface, and a design that allows for removal from a mold without unscrewing, utilizing a bead and flange structure formed by coining, which provides increased sealing area and rigidity for easy ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional injection or blow molding processes are used to produce threaded containers, then the containers can be manufactured with threads, but the threads will have mold seams, parting lines, or flash due to the need for segmented molds or unscrewing
Solution Approach 1:
The mold is divided into a stationary portion and a rotating portion that can independently move relative to each other. The rotating portion includes a thread forming tool that can rotate within the mold cavity to form threads on the container neck without requiring segmented molds or post-molding unscrewing operations, thereby eliminating mold seams and flash on the threads
Solution Approach 2:
The mold incorporates a rotating tool or die that can dynamically rotate within the mold cavity during the molding process. This dynamic rotation allows the thread forming surface to continuously engage with the thermoplastic material, forming seamless external threads while the mold itself remains intact as a single piece
2Ease of operation
If the container is designed with external threads, then the container can be threaded, but the container must be unscrewed from the mold in a cumbersome process to avoid mold lock conditions
Solution Approach 1:
The mold includes a rotating portion that can independently rotate relative to the stationary portion. After molding, the rotating portion rotates to a predetermined position where the formed container can be easily ejected without unscrewing, as the thread forming tool has already created the threads in a single continuous operation
Solution Approach 2:
The threads are formed on the container during the molding process itself rather than after ejection. The rotating thread forming tool creates the external threads while the container is still in the mold, so no subsequent unscrewing or thread formation operations are needed
3Manufacturing precision
If segmented molds are used to produce threaded containers, then the container can be threaded, but undesirable mold seams, parting lines, or flash will appear on the thread segments
Solution Approach 1:
While the mold is segmented into stationary and rotating portions, these segments work together as an integrated system. The rotating portion contains the thread forming tool that creates seamless threads, while the stationary portion provides the mold cavity. This segmentation enables thread formation without requiring multiple separate molds or post-molding operations
Solution Approach 2:
The mold combines thread formation and container molding into a single integrated process. The rotating thread forming tool and stationary mold cavity work simultaneously to form both the container body and its external threads in one operation, eliminating the need for separate threading operations or multiple molds
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
The solution enables seamless external threads, enhanced sealing, and easy mold ejection without damage, eliminating the need for unscrewing or segmented molds, thereby improving manufacturing efficiency and product quality.
Implementation Method 1
vacuum is applied to pull a portion of the thin sheet into conformity with one of the mold cavities
Data Source
AI summary
A molded plastic container includes a bottom wall to define a closed end of the container, a side wall extending generally axially away from the bottom wall, and a neck finish terminating the side wall to define an open end of the container. The neck finish includes a finish wall having an inner and outer surfaces. Also, the neck finish may include a seamless external thread segment projecting from the outer surface of the finish wall, and/or a flange extending radially outwardly from the finish wall and also extending axially downwardly and having a section thickness less than that of the finish wall, and/or a bead extending radially inwardly from the inner surface of the finish wall wherein the thickest section of any of the walls of the container extends through the bead.