Syringe Inner Surface Calibration During Blow Moulding
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Solution Overview
Problem
Syringes produced through extrusion and blow moulding with multi-cavity forming moulds often have irregular and uneven inner surfaces, leading to suboptimal sealing issues when a movable insert, such as a piston, is introduced, resulting in air or liquid leakage during medical treatments.
Innovation Solution
A process that involves extruding plastic material into a multi-cavity forming mould and calibrating the inner surface of the medical containers while still in a molten state to create a smooth, continuous surface, allowing for precise and watertight coupling with the movable insert, using shaped tools for calibration and blow moulding to form the containers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-cavity forming mould is used for blow moulding, then productivity increases by producing multiple containers simultaneously, but manufacturing precision deteriorates due to irregular and uneven inner surfaces at junction edges
Solution Approach 1:
The patent applies preliminary action by performing calibration of the inner surface while the plastic material is still in a molten or malleable state, before the material fully solidifies. This allows the calibration tools to effectively smooth the irregular junction edges formed by multi-cavity moulding, ensuring a smooth continuous inner surface that will maintain its precision after solidification.
Solution Approach 2:
The patent utilizes parameter changes by exploiting the temperature-dependent properties of plastic material. The calibration process is performed when the material is in a molten or malleable state (high temperature), making it soft and deformable enough to be calibrated by the tools. After calibration, the material solidifies, locking in the smooth surface geometry.
2Device complexity
If irregular inner surface is accepted from multi-cavity moulding, then device complexity is reduced by avoiding additional calibration steps, but reliability deteriorates due to poor sealing and air leakage
Solution Approach 1:
The calibration step is integrated into the moulding process itself, performing the smoothing action while the material is still malleable and within the mould cavity. This preliminary calibration ensures that the inner surface is properly prepared for the movable insert before the container is removed from the mould, maintaining reliability without significantly increasing overall process complexity.
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 process ensures a high degree of sterility and a perfect seal between the container and insert, minimizing air or liquid leakage and enhancing the safety and effectiveness of medical treatments by maintaining the smoothness and regularity of the inner surface, even when using existing manufacturing technologies.
Implementation Method 1
extrusion of plastic granules into the forming mould kept opened, creating a hollow heated tube made of malleable plastic material, at the molten state
Implementation Method 2
The production process continues with the closing of the 'parison' between the half shells of the forming mould and, in such conditions of closed forming mould, the subsequent blow moulding
Implementation Method 3
the subsequent blow moulding of one or more medical containers in their definitive and final shape, by blowing compressed air and/or suction creating vacuum
Implementation Method 4
by blowing compressed air and/or suction creating vacuum
Data Source
Figure 1~6
Figure 6a
Figure 7~8
AI summary
A process for producing medical instruments (7) comprising the operations of extruding plastic material in order to obtain a heated tubular element (1) made of molten state plastic material, performing on the tubular element (1 ) a blow moulding in order to obtain a plurality of medical containers (6). The process comprises the operation of calibrating the inner surface (6a) of the various medical containers (6), performed after the operation of extruding plastic material, in order to make smooth and continuous the inner surface (6a) of each of the medical containers (6).