Titanium Diffusion Bonding for Thick Aircraft Structural Stock
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The long lead times and limited availability of titanium alloys in required thickness and properties for large aircraft structural parts pose challenges in conventional manufacturing methods, leading to delayed program schedules and increased costs.
Innovation Solution
A method involving diffusion bonding of two pieces of titanium alloy metal stock to form a thicker, stronger piece with improved mechanical properties, using a process that includes surface smoothing, cleaning, heating below the melting temperature, and applying pressure to create a bonded metal piece without the need for die forging or extrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If die forging is used to manufacture large aircraft structural parts from titanium alloys, then high strength performance is achieved, but very long lead times (60+ weeks) and limited availability of required thickness and properties occur
Solution Approach 1:
The patent divides a thick titanium alloy workpiece into multiple thinner plates that are diffusion bonded together. This segmentation allows each plate to be manufactured with shorter lead times using available stock, while the bonded assembly achieves the required thickness and mechanical properties, thereby reducing overall production time while maintaining strength performance.
Solution Approach 2:
The patent changes the manufacturing parameters by using diffusion bonding process with controlled temperature (below melting point) and pressure to join plates. This parameter change enables the creation of thick sections from thinner plates with available properties, avoiding the 60+ week die forging lead time while maintaining the required mechanical properties for aircraft structural parts.
2Loss of time
If plate stock is machined to required thickness, then shorter lead times and better availability are achieved, but sufficient mechanical properties for intended loading cannot be guaranteed
Solution Approach 1:
Instead of machining a single thick plate with insufficient properties, the patent segments the thick section into multiple thinner plates that are diffusion bonded. Each plate can be manufactured with adequate mechanical properties, and the bonded interface maintains or enhances the overall strength, thereby achieving both shorter lead times and sufficient mechanical properties for intended loading.
Solution Approach 2:
The patent creates a composite structure by diffusion bonding multiple titanium alloy plates together. This composite approach allows each individual plate to have optimized thickness and properties, while the assembled bonded structure achieves the required overall thickness and mechanical performance, solving the contradiction between availability and property requirements.
3Ease of manufacture
If conventional manufacturing methods are used, then traditional processes are followed, but program manufacturing schedules are severely delayed
Solution Approach 1:
The patent applies segmentation by dividing the manufacturing process into plate preparation, surface smoothing, cleaning, and diffusion bonding stages. This segmented approach allows parallel processing of multiple plates and eliminates the sequential bottlenecks of conventional methods, thereby improving productivity and meeting manufacturing schedules while maintaining ease of manufacture through standardized processes.
Solution Approach 2:
The patent implements preliminary action by performing surface smoothing and cleaning of plates before the diffusion bonding process. This preliminary preparation ensures that bonding occurs efficiently and achieves the required mechanical properties, thereby reducing the overall manufacturing cycle time and improving productivity without compromising the ease of manufacture.
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 thicker titanium alloy pieces with enhanced mechanical properties, reducing lead times and costs by eliminating the need for traditional forging processes and ensuring the availability of parts with specific properties for aircraft structural components.
Implementation Method 1
heating the first piece and the second piece to a temperature sufficient for diffusion bonding and below a melting temperature of the stock metal
Implementation Method 2
applying a pressure comprising pressing the first contact surface and the second contact surface together while the first piece and the second piece are at the temperature
Implementation Method 3
bonding the first piece to the second piece so as to form a bonded metal piece having the first contact surface bonded to the second contact surface, the bonding including (i) heating the first piece and the second piece to a temperature sufficient for diffusion bonding
Data Source
AI summary
A method for making a bonded metal piece, including (a) obtaining a first piece of stock metal comprising a first surface and a second piece of the stock metal comprising a second surface; (b) smoothing the first surface so as to form a first contact surface and smoothing the second surface so as to form a second contact surface; (c) cleaning the first contact surface and the second contact surface; (d) loading the first piece and the second piece into a furnace; and (e) bonding the first piece to the second piece so as to form a bonded metal piece comprising the first contact surface diffusion bonded to the second contact surface. The bonding includes (i) heating the first piece and the second piece to a temperature below a superplastic forming temperature of the stock metal; and (ii) applying a pressure comprising pressing the first contact surface and the second contact surface together while the first piece and the second piece are at the temperature. In one or more examples, the bonded metal piece is machined (without forging or working into shape) into an aircraft part.