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Electric Resistance Welded Tubing (Low Frequency Resistance Welding) High Frequency Induction Welding.

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Presentation on theme: "Electric Resistance Welded Tubing (Low Frequency Resistance Welding) High Frequency Induction Welding."— Presentation transcript:

1 Electric Resistance Welded Tubing (Low Frequency Resistance Welding) High Frequency Induction Welding

2 ERW & High Frequency Welding Lesson Objectives When you finish this lesson you will understand: The difference between low frequency Electric Resistance Welding and High Frequency Welding Applications of each Learning Activities 1.View Slides; 2.Read Notes, 3.Listen to lecture 4.Do on-line workbook 5.Do Homework Keywords Electric Resistance Welding, High Frequency Welding, Tube Welding, Proximity Conductor, Induction Coil, Induction Current, Impeder, Seam Annealing

3 Resistance Tube Welding (ERW) W. Stanley, Resistance Welding McGraw-Hill, 1950

4 The Making Shaping & Treating of Steel, USS Corp, 1964

5 The Making Shaping & Treating of Steel, USS Corp, 1964

6 Current Flow in a conductor as a function of Frequency DC60 HZ AC KiloHertz AC High Frequency

7 Appreciating Hig-Frequency Welding Welding Journal, July 1996 High Frequency Induction Welding

8 Metals Handbook, Vol 6 ASM International, 1983

9 Impeder Inside the Core Promotes Path ADC Linnert, Welding Metallurgy AWS, 1994

10 High Frequency Welding Applications [Reference: Welding Handbook, Volume 2, p.653, AWS] Tube Butt SeamTube Butt SeamTube Mash Seam HF Induction Coil

11 High Frequency Welding Applications (CONT.) Strip Butt T-Joint Spiral Tube Spiral Tube Fin HF [Reference: Welding Handbook, Volume 2, p.653, AWS]

12 High Frequency Welding Applications (CONT.) Projection Seam Pipe Butt Bar Butt HF Induction Coil [Reference: Welding Handbook, Volume 2, p.653, AWS]

13 AWS Welding Handbook

14 Typical Tube Welding Conditions for Steels 30 m/min (100 ft/min)at: 600 kW power for 12 mm-wall (1/2 in); diameter of mm ( in) m/min ( ft/min) kW power mm walls ( in) diameter of mm (1 - 2 in) Note high speed

15 Frequency KHz Current Penetration Depth, in Meter

16 Metals Handbook, Vol 6 ASM International, 1983

17 Circuitry & Control

18 Control Devices Input Voltage Regulation SCR’s control input voltage constant Filters used on rectifier output to reduce ripple Variations cause intermittent fusion “stitching” Speed Control Feedback Control on weld power as a function of mill speed Reduces scrap on start and stop Weld Temperature Control Optical Pyrometer aimed at “v” adjusts weld power

19 AWS Welding Handbook 460 V 60 Hz Reduce Ripple Solid State % Efficient >80% Efficient DC Circuit Made of Three Components Filter Tube or SS HF Converter Tank Circuit

20 I p =Plate Current I g = Grid Current E p = Plate Voltage If Efficiency is Below 55% Modifications are needed Nominal Target =75% Ishizaka, HF Resistance Seam Welding, The Fabricator, Nov 1993

21 Efficiency Improvements Can Come From Two Sources The Power Circuit The Workpiece Arrangement

22 Ishizaka, HF Resistance Seam Welding, The Fabricator, Nov 1993 Proper Matching Relationship between the plate voltage and plate current; and the relationship between plate voltage and grid current are nearly coincident with the rated impedance line.

23 Ishizaka, HF Resistance Seam Welding, The Fabricator, Nov 1993 Overload Matching Occurs when load impedance is too small in comparison with the rated impedance Increase the turns ratio of current transformer Reduce tank capacitance

24 Ishizaka, HF Resistance Seam Welding, The Fabricator, Nov 1993 Light Load Matching Reduce the turns ratio of current transformer Increase tank capacitance

25 Current flows more to edge when Edges are closer “v” length is shorter Caution: Can get Premature Arcs

26 Insert Impeder Impeder Mass Closer to Tube Cool Impeder

27 Effect of Weld Speed on Power and Performance Power = E*I B = Fixed Power (losses etc) A*Sp = Weld Power U=The relative power B:A B has less of an effect at higher travel speeds

28 AWS Welding Handbook Induction Coils Cu Tubing or Bar Normally water cooled Surround = efficiency Mag. Strength reduces with distance = 1/8 - 1 inch between coil and work

29 AWS Welding Handbook Contacts Cu or Hard Cermets in Amps Cooling required lbs force Life = 1K - 300K feet

30 Impeders (Current Flow Around inside Surface of Tubes can cause reduced efficiency. The impeder increases the inductive reactance around inside wall of tube.) Ferritic Material Cooled: keep below Curie Temp Extend from “v” to 1 1/2 tube diameters upstream of “v” Mandrels Used to treat inside weld bead shape or scarfing Nonmagnetic Material like Austenitic SS (Impeders also needed)

31 Seam Annealing Robotron Web Site

32 Advantages of High-Frequency Welding Produce welds with very narrow heat-affected zones High welding speed and low-power consumption Able to weld very thin wall tubes Adaptable to many metals Minimize oxidation and discoloration as well as distortion High efficiency

33 Limitations of High-Frequency Welding Special care must be taken to avoid radiation interference in the plant’s vicinity Uneconomical for products required in small quantities Need the proper fit-up Hazards of high-frequency current

34 Some Products of High-Frequency Welding [Reference: Welding Handbook, Volume 2, p.665, AWS]

35 HF Welding


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