Directional Driver Demolding Mechanism for Undercut Parts
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Solution Overview
Problem
Current demolding mechanisms for injection molded parts with undercuts in injection molds face issues with wear and tear, leading to increased cycle times, maintenance costs, and potential mold collisions due to complex mechanical coupling and precise coordination requirements.
Innovation Solution
A demolding mechanism featuring a first pair of drivers that allows form fitting only during the ejection direction, preventing accidental engagement during the return movement, and a second pair for retraction, ensuring wear-free operation and avoiding collisions by using beveled or rounded components to allow sideway movement and resilient mounting for the first driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex mechanical coupling system with multiple drivers is used to demould parts with undercuts, then the demoulding function is achieved, but wear and tear increases leading to longer cycle times and higher maintenance costs
Solution Approach 1:
The patent extracts the form-fitting engagement function from the return movement by designing drivers that only engage in the ejection direction. The first driver is designed to disengage automatically during return movement, separating the ejection function from the return function, thereby reducing wear during the more frequent return movements and reducing maintenance time.
Solution Approach 2:
The patent applies dynamics by making the first driver resiliently mounted, allowing it to dynamically adapt its engagement state based on movement direction. The driver can engage during ejection when force is applied in one direction, and automatically disengage during return when force reverses, reducing wear and maintenance requirements.
2Manufacturing precision
If precise coordination of drivers and slides is required for proper demoulding, then the demoulding accuracy is improved, but the risk of mold collisions due to wear and positioning errors increases
Solution Approach 1:
The patent applies preliminary anti-action by designing the first driver to automatically disengage before the slide can cause a collision during return movement. The resilient mounting and directional engagement design prevent the driver from forcing the slide into a collision position, proactively eliminating the collision risk rather than reacting to it.
Solution Approach 2:
The resilient mounting of the first driver acts as a cushioning mechanism that absorbs positioning errors and wear variations. The spring element provides a buffer zone that prevents hard impacts and collisions, accommodating variations in slide position without causing damage.
3Device complexity
If form fitting is maintained during both ejection and return movements, then the mechanical coupling is simplified, but accidental engagement during return movement causes wear and potential collisions
Solution Approach 1:
The patent applies asymmetry by designing the first driver with a ratchet-like mechanism that engages only in the ejection direction. The driver geometry is asymmetric, allowing form-fitting engagement when force is applied during ejection, but automatically disengaging when force reverses during return movement, preventing wear and collisions.
Solution Approach 2:
The patent segments the mechanical coupling into two distinct functions: the first driver handles ejection movement with form-fitting engagement, while the second driver handles return movement. This segmentation allows each driver to be optimized for its specific function, with the first driver disengaging during return to prevent wear.
Data Source
Figure 1A~1B
Figure 2A~2C
AI summary
The invention relates to a demoulding mechanism (2) for demoulding an injection-moulded part having undercuts from an injection mould, having an ejector frame (4) for ejecting the injection-moulded part from a mould half (8) in an ejection direction and at least one pusher (6) movable and guided obliquely to the ejection direction for releasing the undercuts in the injection-moulded part. The ejector frame (4) and the pusher (6) comprise a first driver pairing (10, 16) , by means of which the ejector (4) can move the pusher (6) from the injection position obliquely to the ejection direction sufficiently far that the first driver pairing (10, 16) disengages because of the increasing distance between ejector (4) and pusher (6). According to the invention, the first driver pairing (10, 16) is designed in such a way that an interlocking connection is formed between ejector frame (4) and pusher (6) when the ejector frame (4) is moved in the ejection direction and an interlocking connection is not formed between ejector frame (4) and pusher (6) when the ejector frame (4) is moved in the opposing, return direction.