External Sensor Kit for Injection Molding Strain Amplification
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Solution Overview
Problem
Current indirect sensors for injection molding, such as strain gauge sensors on mold surfaces, face challenges in accurately approximating conditions within the mold cavity due to inconsistent strain measurement across the mold surface and noise interference, requiring time-consuming testing to identify optimal placement and struggling to distinguish meaningful from noise measurements.
Innovation Solution
An external sensor kit, including a strain gauge sensor, coupon, support bracket, and hammer, is designed to amplify meaningful strain measurements by optimizing material, geometry, and support structure, allowing for pre-amplification of strain data to accurately approximate internal mold conditions like pressure and melt flow front position without the need for extensive testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If strain gauge sensors are placed on mold surfaces to indirectly measure internal conditions, then the need for direct cavity sensors is eliminated, but the measurement precision deteriorates due to inconsistent strain distribution and noise interference across the mold surface
Solution Approach 1:
A coupon is introduced as an intermediary element between the mold cavity and the strain gauge sensor. The coupon is strategically positioned to experience concentrated strain at its neutral axis during cavity filling, serving as a mediator that translates internal pressure conditions into measurable surface strain while filtering out noise from other mold surface locations
Solution Approach 2:
Instead of placing sensors on the general mold surface where strain distribution is inconsistent, the solution focuses on a specific localized region - the coupon's neutral axis - where strain concentration occurs predictably during cavity filling. This local measurement approach eliminates the noise problem associated with measuring at inappropriate mold surface locations
2Device complexity
If strain gauge sensors are placed directly on the mold surface, then the device complexity is reduced, but the time required to identify optimal sensor placement increases due to the need for extensive testing
Solution Approach 1:
The coupon is pre-positioned and pre-loaded onto the mold surface at the optimal location before actual sensing begins. This preliminary placement ensures that the sensor will measure strain at the correct location (neutral axis) from the start, eliminating the need for time-consuming testing and repositioning that would otherwise be required to identify the optimal sensor placement
3Adaptability or versatility
If strain measurements are taken from various mold surface locations, then the adaptability of the sensing system is improved, but the reliability of the measurements deteriorates due to noise interference and inconsistent strain signals
Solution Approach 1:
The system achieves reliable measurements by focusing exclusively on a specific local region - the coupon's neutral axis - where strain concentration occurs predictably during cavity filling. This localized measurement approach eliminates the reliability problems associated with measuring at inappropriate mold surface locations, while the coupon itself can be positioned at different mold locations to maintain adaptability
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 external sensor kit effectively eliminates the need for hunting and testing to find suitable sensor placement, reduces noise interference, and provides reliable approximations of internal mold conditions, enabling real-time adjustments to the injection molding process.
Implementation Method 1
The strain gauge sensor is placed on a surface of the coupon and measures the strain in the coupon
Implementation Method 2
a hammer on the second mold side downstream of the nozzle and configured to contact the coupon when the mold is in a closed position
Data Source
AI summary
Embodiments within the scope of the present disclosure are directed to external sensor kits that may be included in new injection molds or retrofitted into existing injection molds in order to approximate conditions within a mold, such as pressure or the location of a melt flow front. Such kits are designed to amplify meaningful measurements obtained by the external sensor kit so that noise measurements do not prevent the approximation of conditions within a mold. In some embodiments within the scope of the present disclosure, an external sensor kit includes a strain gauge sensor, a coupon, a support bracket, and a hammer. The strain gauge sensor is placed on a surface of the coupon and measures the strain in the coupon.