Eccentric Mandrel Label Transfer in Injection Moulding
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Solution Overview
Problem
In the field of in-mould labelling, existing methods face challenges such as jamming and damage during mandrel introduction due to tight tolerances, label warping, and the risk of 'donkey's ears' preventing accurate label transfer in injection-moulding processes, which affect the speed and accuracy of the injection-moulding process.
Innovation Solution
The mandrel and mould are arranged such that the first axial axis of the mould cavity and the second axial axis of the mandrel are eccentric during label transfer, allowing for a larger annular gap for easier mandrel introduction while maintaining accurate label positioning, with the mandrel's peripheral wall being smaller than the mould cavity's inner periphery to reduce jamming risks and using air or electrostatic means for label transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the distance between the outer periphery of the mandrel and the inner periphery of the injection mould is kept as small as possible, then the label transfer accuracy is improved, but the mandrel introduction may result in jamming and damage due to tight tolerances
Solution Approach 1:
The mandrel is designed with an adjustable diameter that can be dynamically changed during the process. The mandrel starts with a smaller diameter for easy introduction into the mould, then expands to a larger diameter for accurate label transfer, resolving the contradiction between easy introduction and precise positioning
Solution Approach 2:
The physical parameter of the mandrel (its diameter) is changed during the process. By varying the mandrel's diameter from small to large, the system transitions from a state suitable for introduction to a state suitable for precise label transfer, eliminating the need to choose between tight tolerances and easy introduction
2Strength
If the mandrel is made heavier to maintain structural integrity, then the mandrel strength is improved, but the acceleration and deceleration during high-speed injection-moulding become more difficult
Solution Approach 1:
The mandrel's mass is made variable rather than fixed. During high-speed operations, the mandrel operates in a collapsed state with minimal mass for easy acceleration and deceleration. When structural integrity is needed, the mandrel expands to a rigid state, providing strength only when required
Solution Approach 2:
The mandrel uses a collapsible structure that can be rapidly deployed and collapsed, effectively creating a lightweight, temporary structure for each cycle that provides strength only during the brief moment when needed for label transfer
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 approach increases the tolerance for mandrel introduction, reduces the risk of damage, and ensures accurate label positioning within the mould cavity, allowing for efficient and precise injection-moulding processes, even with larger mandrel dimensions, and minimizes the occurrence of 'donkey's ears' during label transfer.
Implementation Method 1
using air or electrostatic means for label transfer
Implementation Method 2
using air or electrostatic means for label transfer
Data Source
AI summary
Methods and structures are shown for a variety of ways to arrange a label in a mould cavity. One is a method for arranging a label in a mould cavity of a mould, which mould cavity is delimited by an internal peripheral surface that defines a first axial axis of the mould cavity, the method comprising: providing a mandrel having a peripheral wall that defines an axial direction and a peripheral direction, wherein the peripheral wall further defines a second axial axis, the peripheral wall being provided with: a peripheral part having a shape that substantially corresponds to a shape of a part of the internal peripheral surface of the mould cavity, and a non-convex part that extends in the axial direction of the peripheral wall of the mandrel, arranging the label around the peripheral wall of the mandrel, which label comprises a first side edge part and a second side edge part, in which the label is arranged around the peripheral wall of the mandrel in such a manner that the second side edge part overlaps the first side edge part viewed in the peripheral direction of the mandrel at a location of the non-convex part of the peripheral wall of the mandrel, introducing the mandrel with the label arranged around the peripheral wall thereof into the mould cavity, transferring the label from the peripheral wall of the mandrel to the internal peripheral surface of the mould cavity, wherein the mandrel and the mould are arranged with respect to one another in such a manner during transfer of the label from the peripheral wall of the mandrel to the internal peripheral surface of the mould cavity, that the first axial axis of the internal peripheral surface of the mould cavity and the second axial axis of the peripheral wall of the mandrel are eccentric with respect to one another.