Induction Brazing Tie Wire Temperature Feedback Control
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Solution Overview
Problem
Typical torch brazing processes for joining tie wires with turbine buckets often result in overheating, leading to hard spots and stress corrosion cracking due to uncontrolled heating, while underheating compromises the quality and strength of the brazed joint.
Innovation Solution
A system and method utilizing an induction heating coil with magnetic flux concentrators within a braze chamber, controlled by a temperature feedback system to heat the tie wire to a specific temperature range, ensuring precise heating and preventing overheating, while maintaining an oxygen-free atmosphere for optimal braze alloy flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If torch brazing process is used to join tie wire with workpiece, then the brazing operation can be performed, but overheating occurs leading to hard spots and stress corrosion cracking
Solution Approach 1:
The system employs a temperature feedback control mechanism where a temperature sensor continuously monitors the actual temperature of the tie wire during induction heating, and the controller adjusts the heating power accordingly to maintain the temperature within the specified range (705°C to 810°C), preventing both overheating and underheating
Solution Approach 2:
The patent replaces the manual torch brazing process with an automated induction heating system that uses electromagnetic fields to generate heat directly in the tie wire, eliminating the uncontrolled thermal field of torch heating and enabling precise temperature management through electrical control
2Reliability
If torch brazing process is used to join tie wire with workpiece, then the brazing operation can be performed, but uncontrolled heating leads to stress corrosion cracking
Solution Approach 1:
The temperature feedback control system prevents excessive heating that would create hard spots and residual stresses, thereby eliminating the root cause of stress corrosion cracking by maintaining temperature within the optimal brazing range
Solution Approach 2:
The system uses a braze chamber that provides a controlled atmosphere environment, preventing oxidation and corrosion during the brazing process by excluding harmful atmospheric elements from the heated zone
3Temperature
If underheating is performed to compensate for overheating, then overheating is avoided, but the quality and strength of the brazed joint is compromised
Solution Approach 1:
The feedback control system ensures the temperature reaches and maintains the optimal brazing range (705°C to 810°C) by continuously monitoring and adjusting heating power, guaranteeing both proper joint strength and prevention of overheating
Solution Approach 2:
The system precisely controls multiple parameters including temperature (705°C to 810°C range), heating time (30 sec to 10 min), and atmospheric conditions to optimize the brazing process, ensuring adequate heat input for strong joints without exceeding limits that cause defects
4Device complexity
If manual torch brazing is used, then the process can be performed with simple equipment, but operator variability affects consistency
Solution Approach 1:
The induction heating system with feedback control is self-regulating, automatically adjusting heating parameters based on real-time temperature measurements, eliminating the need for operator judgment and skill while ensuring consistent results
Solution Approach 2:
The patent replaces manual operator control with an automated control system that uses temperature sensors and programmable logic to manage the brazing process, substituting human variability with precise electronic control
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 approach consistently produces high-quality brazed joints without hard spots or stress corrosion, reducing operator variability and allowing for repeatable results across different geometries and work sites with minimal training, thereby enhancing the reliability and durability of the joint.
Implementation Method 1
an induction heating coil with magnetic flux concentrators within a braze chamber
Implementation Method 2
applying an electrical current to the induction heating coil to heat the section of the tie wire therebetween
Implementation Method 3
the induction heating coil having magnetic flux concentrators thereon
Implementation Method 4
a controller receiving a temperature feedback signal from a temperature sensor on a tie wire
Implementation Method 5
applying a braze alloy in contact with the section of the workpiece and the section of the tie wire to be brazed
Data Source
AI summary
A system for forming a brazed joint between a tie wire and a workpiece, and methods therefor are presented. The system includes: a braze chamber including an induction heating coil, the induction heating coil having magnetic flux concentrators thereon; and a controller receiving a temperature feedback signal from a temperature sensor on a tie wire and controlling a temperature of a section of the tie wire to be brazed by controlling an electrical current applied to the induction heating coil.