Additive Insert Thread Geometry for Accurate Wire Thread Inserts

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Solution Overview

Problem

Additive manufacturing processes face challenges in producing components with accurate threads due to geometric deviations, especially for materials like nickel-based alloys and titanium, which require costly post-processing and are difficult to machine, and existing methods lack practical implementation in real geometries and materials.

Innovation Solution

An additive manufacturing method that involves creating an insert thread with adjusted dimensions using correction factors to accommodate a wire thread insert, allowing for the formation of a standard thread by combining the insert thread with a wire thread insert, thereby reducing geometric deviations and enabling accurate thread formation without post-processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If additive manufacturing is used to produce threads directly, then design freedom and production efficiency are improved, but geometric precision and thread accuracy deteriorate due to layer structure deviations

Engineering Contradiction:
Improveproduction efficiencyVSAvoidthread accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The thread structure is divided into two separate components: an additively manufactured insert thread and a wire thread insert. The insert thread provides the base geometry with corrected dimensions, while the wire insert provides the final thread reinforcement and accuracy, separating the manufacturing processes to overcome the limitations of direct additive manufacturing

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The dimensions of the insert thread are deliberately modified using correction factors (enlarged nominal diameter, core diameter, and pitch) to compensate for additive manufacturing geometric deviations. These parameter changes ensure that when the wire insert is installed, the final thread geometry meets standard requirements

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If post-processing is applied to correct thread geometry, then thread accuracy is improved, but production time and costs increase

Engineering Contradiction:
Improvethread accuracyVSAvoidproduction time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The correct thread geometry is built into the insert thread during the additive manufacturing process itself by using corrected dimensions. This preliminary correction eliminates the need for subsequent post-processing operations, as the insert thread is designed to work with the wire insert to achieve the final accurate thread geometry

Inventive Principle:
Principle #10Preliminary action

3Ease of manufacture

If conventional thread production methods are used for difficult-to-machine materials, then thread formation is achieved, but manufacturing complexity and costs increase due to cooling and lubrication requirements

Engineering Contradiction:
Improvethread formation capabilityVSAvoidmanufacturing process complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The mechanical thread formation process (cutting, threading) is replaced with an additive manufacturing process that builds the insert thread layer by layer. This substitution eliminates the need for mechanical cutting tools, coolants, and lubricants, making the process suitable for difficult-to-machine materials like nickel-based alloys and titanium

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 method enables the production of components with reduced geometric deviations, allowing for accurate thread formation and connection without the need for costly post-processing, and is applicable to various materials, including difficult-to-machine alloys like nickel-based alloys and titanium.

Implementation Method 1

additive manufacturing process of a component with a thread opening and an insert thread arranged on its radial inner wall

Methodology Applied
Scientific EffectLaser melting: Laser

Implementation Method 2

additive manufacturing method of a component with a thread opening and an insert thread arranged on its radial inner wall

Methodology Applied
Scientific EffectSelective laser sintering: Selective Laser Sintering

Data Source

PatentEP4151339A1Component produced using additive manufacture with insert thread, method of manufacturing same and component with wire threaded insert installed in the insert thread
Publication Date: 2023.03.22 BOLLHOFF VERBINDUNGSTECHNIK GMBH
  • EP4151339A1 patent drawingFigure 1~2
  • EP4151339A1 patent drawingFigure 3~4
  • EP4151339A1 patent drawingFigure 5

AI summary

An additive manufacturing process for a component 10 with a threaded opening 12 and an insert thread 16 arranged on its radial inner wall, which is adapted to a wire thread insert 30 to be received for thread reinforcement in order to form a standard thread from the insert thread 16 and the wire thread insert 30, comprises the following steps: Providing a three-dimensional component drawing with the threaded opening 12 and the insert thread 16 (S1) arranged therein, which is defined by DHC≥DHC min=d+0.75×Ptanα2 D1HC≥D1HC min=d+0.125×Ptanα2 D1HC≤D1HC max=d+0.125×Ptanα2+0.373×P−0.192×P1.21 PHC=DHC min−D1HC min×1,6×tanα2 with d nominal diameter of the screw thread to be inserted into the thread with wire thread insert α flank angle of the screw thread to be inserted into the thread with wire thread insert P pitch of the screw thread to be inserted into the thread with wire thread insert DHC nominal diameter of the thread DHC min smallest nominal diameter of the thread D1HC core diameter of the thread D1HC min smallest core diameter of the thread D1HC max largest core diameter of the thread PHC pitch of the thread Adjusting S2, S3, S4, S5 of the dimensions of the thread 16 to additive manufacturing using correction factors, converting the three-dimensional component drawing with the adjusted dimensions into a layer model for additive manufacturing S5 and additive manufacturing of the three-dimensional component S6.