U-Shaped Yoke Alignment in Relay Injection Molding
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Solution Overview
Problem
Conventional methods for manufacturing electromagnetic relays face challenges with tolerances in injection molding processes, leading to misalignment and fluctuations in pick-up and drop-out voltage, which require complex adjustments and increase costs.
Innovation Solution
A method involving an injection mold with a fixing device that precisely aligns a U-shaped yoke during overmolding, ensuring minimal tolerances between the yoke and armature bearing, allowing for precise positioning and reduced deviations in the coil system, thereby simplifying the assembly process and enhancing the relay's performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional injection molding process is used to manufacture coil body, then manufacturing cost is reduced, but manufacturing precision deteriorates due to tolerance fluctuations in pick-up and drop-out voltage
Solution Approach 1:
The patent applies preliminary action by pre-positioning the yoke in a defined orientation within the injection mold before the injection process. The mold includes positioning elements that establish the correct spatial relationship between the yoke and armature bearing before plastic material is injected, ensuring precise alignment is built into the tooling itself rather than achieved through post-processing or complex multi-stage molding.
Solution Approach 2:
The patent uses an intermediary approach by introducing a fixing device as a mediator between the yoke and the injection mold. This fixing device includes positioning elements that act as intermediaries to transfer and maintain the precise spatial relationship during the injection process, allowing the yoke to be held in the correct position without requiring complex mold structures.
2Manufacturing precision
If multi-stage encapsulation process is used as described in DE 196 39 876 A1, then manufacturing precision is improved, but device complexity increases and manufacturing cost rises
Solution Approach 1:
The patent merges multiple process stages into a single injection molding operation. By integrating the positioning function into the mold itself and using a fixing device that maintains precise alignment throughout the injection process, the patent combines what would otherwise require multi-stage encapsulation into one streamlined process, reducing both device complexity and manufacturing cost while maintaining high precision.
Solution Approach 2:
The patent applies universality by designing the injection mold to perform multiple functions simultaneously: it provides the shaping function, the positioning function through integrated positioning elements, and the fixing function through the fixing device. This multi-functional mold design eliminates the need for separate positioning and fixing operations that would be required in multi-stage processes.
3Reliability
If tolerances are specified by conventional injection molding, then ease of manufacture is maintained, but reliability deteriorates due to fluctuations in contact life
Solution Approach 1:
The patent applies preliminary action by pre-establishing the precise spatial relationship between the yoke and armature bearing through positioning elements in the mold before the injection process begins. This preliminary positioning ensures that critical dimensions and alignments are determined during tooling design rather than left to variation during manufacturing, thereby improving reliability and contact life stability.
Data Source
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AI summary
The method involves producing a coil body (12) in an injection mold by partial insert molding a yoke (11) with plastic and then the coil body is provided with a coil. The yoke is fixed in the injection mold such that an exactly defined alignment of pole surfaces (11a,11c) of the yoke relative to an armature bearing (13) of the coil body is carried out, at which an armature (20) is coupled with the coil body. An independent claim is included for an injection mold for the manufacturing a coil body.