Segmented Inner Mandrel for Reusable Composite Spring Molding

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Solution Overview

Problem

Existing tooling for forming variable taper components like composite coil springs is costly and time-consuming due to the destruction of inner mandrels and bismuth core mandrels after each use, requiring remanufacturing and increasing part costs.

Innovation Solution

The development of a reusable tooling system comprising an inner mandrel with a master insert and interlocking pieces, along with a tapered inner sleeve and outer mandrel, which allows for the formation and easy disassembly of variable taper components without destroying the tooling, enabling the reuse of the inner mandrel and reducing material waste.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If traditional inner mandrels are used for forming variable taper composite coil springs, then the component can be formed, but the inner mandrel becomes locked inside and must be destroyed after each use

Engineering Contradiction:

Improveease of tooling removalVSAvoidtooling destruction

Core Design Contradiction:

Ease of manufactureVSLoss of substance

Solution Approach 1:

The inner mandrel is divided into multiple segments (first inner mandrel segment, second inner mandrel segment, third inner mandrel segment) that can be independently removed after forming. Each segment has corresponding removal features that allow sequential extraction from the formed component without destroying the entire mandrel structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A bismuth core mandrel is introduced as an intermediary material that can be melted and removed from the formed component. The bismuth core mandrel serves as a temporary placeholder that facilitates component removal while being easily extractable through melting, preventing permanent tooling entrapment.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If bismuth core mandrels are used and melted out after forming, then component removal is enabled, but part cost increases significantly

Engineering Contradiction:

Improvecomponent removalVSAvoidmaterial cost

Core Design Contradiction:

Ease of operationVSQuantity of substance

Solution Approach 1:

The segmented inner mandrel design allows for recovery and reuse of the mandrel components after forming. Instead of discarding the entire mandrel or using consumable bismuth material, the segments can be extracted, recovered, and reused for subsequent forming operations, reducing material costs.

Inventive Principle:

Principle #34Discarding and recovering

3Productivity

If the inner mandrel is destroyed after each use, then component release is achieved, but production time increases due to remanufacturing

Engineering Contradiction:

Improveproduction cycle timeVSAvoidtooling remanufacturing time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

By segmenting the inner mandrel into removable portions, the tooling can be quickly disassembled and reassembled for the next production cycle without requiring time-consuming remanufacturing processes.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The mandrel segments are recovered and reused across multiple production cycles, eliminating the repeated remanufacturing time associated with traditional single-piece mandrels that must be destroyed after each use.

Inventive Principle:

Principle #34Discarding and recovering

4Manufacturing precision

If variable taper components are formed with traditional tooling, then the component shape is achieved, but the tooling becomes trapped and cannot be removed

Engineering Contradiction:

Improvevariable taper geometryVSAvoidtooling extraction

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The inner mandrel is segmented into multiple sections with corresponding removal features on each segment. This segmentation allows the tooling to maintain precision for forming variable taper geometry while enabling sequential extraction of each segment from the formed component.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of designing a solid mandrel that is removed by force or destruction, the invention inverts the approach by creating a mandrel with internal cavities and removal features that allow the mandrel itself to be extracted from the formed component in reverse order of insertion.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS11780148B2Permanent tooling for composite coil spring compression molding

Publication Date: 2023.10.10 FORD GLOBAL TECH LLC

AI summary

An inner mandrel for forming a variable taper component includes a master insert and a plurality of interlocking pieces. The master insert includes opposed tapered edge faces, each tapered edge face defining at least one locking feature, a first surface having a variable taper and a plurality of recesses configured to receive a portion of the variable taper component, and a tapered second surface opposite the first surface. Each interlocking piece includes opposed tapered edge faces, one of the opposed tapered edge faces defining a locking feature and another of the opposed tapered edge faces defining a receiving feature to engage the locking feature of an adjacent interlocking piece, a first surface defining a variable taper and a plurality of recesses configured to receive a portion of the variable taper component, and a tapered second surface opposite the first surface.