Hinged Plastic Part Assembly During Demolding
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Solution Overview
Problem
Existing methods for injection molding of thermoplastic articles with hinged parts require complex systems and long cycle times, as the mold opening, part assembly, and demolding steps must occur separately, making it inefficient for quick-acting presses and prone to deformation in articles with thin thickness or plane walls.
Innovation Solution
A method and apparatus that utilize linear movements of a conventional injection molding press to assemble hinged parts directly during the demolding step, using a hinge pin and annular element with snap-on coupling, eliminating the need for additional devices and control systems, and allowing assembly without risking deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mold opening, part assembly, and demolding steps are carried out separately, then each step can be performed with dedicated equipment, but the working cycle time increases and device complexity increases
Solution Approach 1:
The patent combines the demolding device and assembly device into a single integrated system. The demolding device includes a demolding plate that simultaneously performs demolding and assembly functions, eliminating the need for separate equipment and reducing cycle time while maintaining assembly precision through coordinated movement of the integrated components
2Extent of automation
If additional assembling devices and control systems are used, then part assembly can be automated, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent implements self-service automation where the demolding device's linear movement automatically drives the assembly operation. The hinge pin and annular element are positioned and connected through the natural demolding motion, eliminating the need for separate control systems while achieving automatic assembly
Solution Approach 2:
The demolding device is designed to perform multiple functions: it simultaneously executes demolding, positioning, and assembly operations. This multi-functionality reduces device complexity by eliminating dedicated assembly equipment while maintaining full automation capability
3Productivity
If articles with thin thickness or plane walls are assembled separately after molding, then deformation can be avoided, but productivity decreases
Solution Approach 1:
The patent performs assembly during the demolding step itself, which is a preliminary action before the article is removed from the mold. This timing allows the article to still be supported by the mold structure, providing mechanical support that prevents deformation of thin-walled sections while enabling simultaneous assembly
Data Source
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AI summary
A method and an apparatus for injection co-molding and assembling of articles made of plastic material and an injection molded article made plastic triatrial, the articles comprising a first part (10) provided with a hinge pin (14), and a second part (11) provided with an annular element (15) designed to be connected to each other by hinging. The apparatus comprises a mold (20, 21) having separate mold impressions for two parts (10, 11) of the article to be produced; a first molding member (40), defining the impression of the pin (14), and a second molding member (41), defining the impression of the annular element (15), are axially movable and operatively connected to cam control means (46, 47) forming part of the same injection mold. The cam control means (46, 47) are shaped and arranged in such a way as to cause, after the opening of the mold (20, 21 ) , the automatic assembling of the plastic article, by means of a selective sequence of axial movements of the two molding members (40, 41), during the demolding step of the molded article.