This chapter of the free Fluxtrol induction heating course walks through case story – design of stress relieving coil and process in 12 slides. View the slides below, or skim the outline and slide text.
Chapter outline
- $avings Due to Induction Coil and Process Optimization
- Problem Description
- Step 1: Analysis of Process Conditions
- Step 2: Simulation of Existing Process
- Step 3: Initial Inductor Design Using Power Ramping
- Step 4: Optimal Process and Coil
- Temperature Evolution with New Coil
- New Inductor Sketch (Top and Side Views)
- Final Results
Slide text
$avings Due to Induction Coil and Process Optimization
- Increased production rates
- Lower maintenance costs
- Fewer downstream operations
- Reduced part scrap
- Shorter change-over times
- Energy savings Everyone must produce “Good Parts”, but there are ways to make them Better, Faster and more Economically !
Problem Description
- Problem:
- The Customer the following:
- made contact due
- System they purchase d could meet required production rate to not
- To achieve marginal parts, they had to run at half the promised speed
- Even at half speed, they did not meet customer specifications because the heated zone was too narrow and the part was experiencing low temperature on seam bottom
- Difficulties were because the machine was built based upon experience in seam annealing, not stress relieving Inductor for seam annealing on spiral welded big diameter pipe
Step 1: Analysis of Process Conditions
- Limited space on spiral welding mill
- Power supply and other equipment with frequency 3 kHz and power 500 kW already exists
- Heat tube material:
- Steel 1040
- Wall thickness 12.7 mm
- Relatively small temperature window
- Tmax = 650 C
- Tmin = 550 C
- Heat Affected Zone (HAZ) 60 mm
- Required heating time 16 seconds
- Flux concentrator: Laminations on original coil later replaced with Fluxtrol “A”
Step 2: Simulation of Existing Process
- Temperature evolution in Outside (1) and Inside (2) seam points These results are close to experimental data and very far from specifications Temperature color end of heating map Flux 2D program at the
Step 3: Initial Inductor Design Using Power Ramping
- The easiest way to improve temperature distribution is to use power profiling along the coil length. It may be achieved by variation of concentrator geometry.
- Results are much better but specifications are still not met
Step 4: Optimal Process and Coil
- Proposed solution:
- Make central coil leg of two parallel conductors to increase Heat Affected Zone 2. Power ramping holding temperature and precise maximum 3. Use Fluxtrol concentrator with profile variation Temperature color map for new coil and process at the end of heating
Temperature Evolution with New Coil
- Temperature evolution in Outside (1) and Inside (2) seam points for optimized process Temperature profile along the pipe OD surface at the end of heating Minimum temperature in HAZ (point 2) reached required material exceeding maximum acceptable temperature value without
New Inductor Sketch (Top and Side Views)
- Concentrator has full C-shaped profile at ramping stage. When maximum permissible temperature was reached, concentrator shape started to change by cutting pole length then complete removal of concentrator.
- Top view of concentrator (hatch ed) Fluxtrol concentrator Fluxtrol concentrator Side view of induction coil
Final Results
- Customer manufactured induction coil according to Fluxtrol suggestions
- Induction user was able to produce parts in specs with desired production rate
- Final customer was completely satisfied See Seam Anneal Video