Eccentric Core Alignment in Pipette Injection Molding
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Solution Overview
Problem
The production of thin-walled elongated bodies like pipettes often results in misalignment and asymmetry due to tool misalignment and tolerances, leading to incorrect positioning of the outlet opening, which causes issues with automatic pipetting and results in rejects.
Innovation Solution
A device featuring an eccentric interlocking design between the stripping sleeve and bushing allows for simple alignment of the core by rotary movement, enabling correction of deviations directly within the injection molding tool, ensuring the tip lies on the geometric axis of symmetry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional injection molding tools are used, then production speed is maintained, but manufacturing precision deteriorates due to mold misalignment and tooling tolerances causing asymmetrical pipettes
Solution Approach 1:
The core element is designed with dynamic adjustment capability through the eccentric bushing and wiper sleeve assembly, allowing the core position to be shifted radially by rotating the bushing relative to the sleeve. This dynamic adjustment enables compensation for mold misalignment and tooling tolerances, transforming a static mold structure into one that can adapt its core position to achieve symmetrical pipette production.
Solution Approach 2:
The mold incorporates self-adjustment mechanisms where the eccentric bushing and wiper sleeve allow the core position to be corrected through simple rotary movement without requiring complex external adjustment systems or removal of the mold from the injection machine. The operator can directly adjust the core position within the mold assembly to compensate for alignment issues.
2Manufacturing precision
If mold misalignment is corrected by removing and repositioning the mold, then manufacturing precision improves, but productivity deteriorates due to machine downtime
Solution Approach 1:
The adjustable core element with eccentric bushing allows rapid repositioning of the core within the mold without removing the mold from the injection machine. This dynamic adjustment capability enables quick correction of alignment issues during production, maintaining high productivity while achieving precise core alignment.
Solution Approach 2:
The mold is designed with preliminary adjustment capabilities built into the core assembly structure, allowing alignment corrections to be made in advance or during brief pauses without interrupting the overall production flow. The eccentric mechanism enables pre-positioning of the core for optimal symmetry before production begins.
3Manufacturing precision
If the core position is fixed during molding, then device complexity is reduced, but manufacturing precision deteriorates due to inability to correct deviations
Solution Approach 1:
The core assembly incorporates a dynamic adjustment mechanism using an eccentric bushing that can be rotated relative to a wiper sleeve to shift the core position radially. This relatively simple rotational mechanism provides precise control over core positioning to ensure the outlet opening is correctly located, without requiring complex multi-axis adjustment systems.
Solution Approach 2:
The core position is adjusted by changing the rotational parameter of the eccentric bushing relative to the wiper sleeve. By rotating the bushing to different angular positions, the core is shifted radially to correct alignment deviations, enabling precise control of the outlet opening position through a single rotational parameter change.
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 solution allows for the precise manufacture of thin-walled elongated bodies with constant wall thickness, enabling easy correction of deviations without removing the injection mold from the machine, thus reducing rejects and improving pipette production accuracy.
Implementation Method 1
The eccentric design of the interlocking eccentric bushing (33) and the wiper sleeve (25) makes it possible to connect them in such a way that the position of the core (15) can be aligned by a simple rotary movement of one of the two elements.
Data Source
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AI summary
The device for producing a thin-walled elongate body from thermoplastic material comprises a removable sleeve (25) and a bush (33), wherein the casing of the removable sleeve (25) and the bore (31) in the bush (33) are arranged eccentrically with respect to the axis of symmetry of the core and, by rotation relative to one another, a deflection of the core can be achieved both in terms of magnitude and also in relation to the deflection angle.