Unshielded Strain Gage Sensor Cable Shielding in Injection Molds
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Solution Overview
Problem
Strain gage sensors in injection molding face challenges with electromagnetic interference (EMI) due to the requirement for shielding, difficulty in finding small enough connectors, and high costs of connectors that meet size and shielding constraints, limiting the use of multichannel connectors.
Innovation Solution
The use of unshielded cables and connectors within a tightly sealed shielding enclosure inside the mold, along with a shielded extension cable tied 360° to the multichannel connector, addresses EMI issues and allows for smaller, less expensive connectors, enabling the use of multichannel connectors with strain gage sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shielded cables and connectors are used for strain gage sensors, then signal noise from EMI is prevented, but connector size increases and cost increases
Solution Approach 1:
The system is divided into two distinct parts: unshielded connectors inside the mold and shielded extension cables outside the mold. This segmentation allows each component to be optimized independently - small unshielded connectors for space-constrained mold installation and shielded cables for EMI protection during signal transmission to the signal conditioner.
Solution Approach 2:
The mold itself acts as an intermediary shielding enclosure between the unshielded connectors inside and the external environment. By utilizing the mold's metallic structure as a Faraday cage, the system achieves EMI protection without requiring shielded connectors at the sensor connection point, thus reducing connector size and cost.
2Reliability
If shielded connectors are used to carry cable shield through, then EMI protection is maintained, but connector size increases and availability decreases
Solution Approach 1:
The shielding function is separated from the connector function. Unshielded connectors are used for sensor attachment inside the mold, while shielding is provided by the mold enclosure and shielded extension cables for signal transmission outside the mold. This separation makes standard unshielded connectors available for use.
Solution Approach 2:
The mold structure itself provides the shielding service that would otherwise require specialized shielded connectors. The metallic mold enclosure acts as a built-in Faraday cage, eliminating the need for externally attached shielded connectors and making standard connectors universally available.
3Reliability
If shielded connectors meeting size and shielding constraints are used, then EMI protection and space constraints are satisfied, but cost increases significantly
Solution Approach 1:
The system separates expensive shielded components from inexpensive unshielded components. Standard inexpensive unshielded connectors are used inside the mold where space is constrained, while shielded extension cables are used outside the mold where EMI protection is needed but space is not a constraint, achieving both goals at lower overall cost.
Solution Approach 2:
The mold enclosure serves as an intermediary shielding structure that eliminates the need for expensive shielded connectors. By utilizing the existing mold structure as a Faraday cage, the system achieves EMI protection without the added cost of specialized shielded connectors.
4Ease of operation
If signal conditioning is mounted directly on the mold, then connection simplicity is improved, but signal conditioning is exposed to heat and shock damage
Solution Approach 1:
The signal conditioning unit is extracted from the mold environment and mounted externally where it is protected from heat and shock. A single shielded extension cable connects the mold interior to the external signal conditioner, maintaining connection simplicity while improving durability through physical separation of the sensitive electronics from the harsh mold environment.
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 configuration effectively reduces signal noise from EMI, lowers connector costs, and allows for easier reconfiguration while maintaining signal quality, providing a cost-effective solution for strain gage sensors in injection molding.
Implementation Method 1
tightly enclosing the unshielded cables and connectors within a tightly sealed shielding enclosure inside the mold. Here, the mold and the multichannel connector, tightly sealed, provide this shielding
Implementation Method 2
A shielded extension cable, with its shield tied 360° to the multichannel connector, is then used to carry the signal to the signal conditioner
Implementation Method 3
Strain gage sensors, on the other hand, require cables with four conductors: two of the connectors providing excitation voltage and two that carry the millivolt signal
Data Source
AI summary
An unshielded strain gage sensor cable that is tightly sealed within an injection mold to prevent electromagnetic interference from interfering with the sensor signal. The use of the unshielded cable significantly reduces the cost and allows for quick installation and a mobility that does not exist with shielded cables.