Lesson Plan. Preparation

Transcription

1 Course Title: Advanced Welding Lesson Plan Session Title: Mig Welding - Oxy Fuel Cutting Performance Objective: Upon completion of this assignment, the student will be able to set up and shut down the equipment properly, and be able to cut a straight line using Oxy Fuel Cutting equipment. Specific Objectives: 1. Explain oxyfuel cutting safety. 2. Identify and explain oxyfuel cutting equipment. 3. Identify and explain oxyfuel flames 4. Identify and explain backfire and flashbacks 5. Set up oxyfuel equipment 6. Light and adjust an oxyfuel torch. 7. Shut down oxyfuel equipment 8. Change empty cylinders 9. Perform oxyfuel cutting straight line TEKS Correlations: Preparation This lesson, as published, correlates to the following TEKS. Any changes/alterations to the activities may result in the elimination of any or all of the TEKS listed. Advanced Welding: (c)(8)(A)(B)(C) observe safe operating practices; apply safe handling of compressed gases; and perform advanced cutting processes according to accepted welding standards. Interdisciplinary Correlations: English: (6)(A)(B) expand vocabulary development through wide reading, listening, and discussing; rely on context to determine meanings of words and phrases such as figurative language, idioms, multiple meaning of words, and technical vocabulary; 1

2 Instructor/Trainer References: 1. Jeffus, Larry; Welding Principles and Applications Third Edition, Delmar Publishers Inc. ISBN ; Chapter 7 2. Gellerman, Mike: Welding Fundamentals, Delmar Publishers Inc., ISBN Unit 3 Instructional Aids: Oxy Weld PowerPoint Presentation Oxy Weld Safety Precautions Handout Labs 1 & 2 Handout Terminology Handout Oxy Weld Test Oxy Weld Test Answers Materials Needed: Steel plate Personal safety equipment Equipment Needed: Learner Oxygen cylinder (with cap) Fuel gas cylinder Regulators oxygen and gas Hose set Combination cutting torch One-piece cutting torch Wrenches and torch lighter Demonstrated knowledge of safety in welding. Introduction 2

3 Introduction (LSI Quadrant I): SAY: Oxyfuel cutting is a process used to separate metal by heating it to a kindling temperature between 1400 and 1800 degrees F, then oxidizing and blowing the metal from the cut with a stream of oxygen. SAY: At the end of the lesson you will be able to use the oxyfuel to cut a straight line in order to make coupons to prepare for welding exercise. Outline (LSI Quadrant II): Steps I. Safety A. Handling and using equipment B. Personal Protective Equipment C. Ventilation D. Area Safety II. Equipment A. Oxygen Gas and Cylinders B. Acetylene and Cylinders C. Regulators D. Hoses E. Torches F. Cutting Tips III. Cutting Procedure A. Straight line cut B. Inspecting the cut I. Review Safety Sheet II. Lab 1: Outline PROCEDURE FOR TURNING OFF THE OXYFUEL RIG 1. Turn off the acetylene at the torch body (the flame will go out and the oxygen will blow out the carbon). 2. Turn off the oxygen at the torch. 3. Turn off the acetylene cylinder valve. 3

4 4. Bleed the acetylene hose and regulators, then close the torch valve (both gauges will drop to zero). 5. Screw out the acetylene regulator adjusting screw until loose. 6. Turn off the oxygen cylinder valve. 7. Bleed the oxygen hose and regulators and close the torch valve (both gauges will drop to zero). 8. Screw out the oxygen regulator adjusting screw until loose. 9. Recheck the valve and roll up the hose. If rig is not to be used for some time, remove the regulators and put the safety caps back on the cylinders. II. Lab 2: PROCEDURE FOR TURNING ON THE OXYFUEL RIG 1. Valves on the torch body should be closed. 2. The adjusting screws on the regulators must be loose. 3. Turn on acetylene cylinder valve ¼ to ½ turn; if wheel type, open all the way. 4. Tighten the regulator adjusting screw to the desired working pressure. 5. Open the oxygen cylinder valve all the way. 6. Tighten the regulator adjusting screw to the desired working pressure. 7. If the cutting attachment is being used, open the torch body oxygen valve all the way. 8. Crack the acetylene valve and light. Blow the flame off the tip and slowly adjust in back. 9. Adjust to a neutral flame with the oxygen valve. The oxygen pressure can be 5 to 10 times higher than the acetylene pressure when cutting. Never exceed 15 pounds pressure per square inch on acetylene. When welding, the ratio of oxygen to acetylene is approximately 1:1. Oxygen and acetylene settings will vary depending on the attachment tip and thickness of metal to cut or weld. Guided Practice (LSI Quadrant III): Application 4

5 The instructor will demonstrate all procedures before students attempt them. The students will point out all safety procedures during the demonstrations to ensure the proper use of equipment by the students. Independent Practice (LSI Quadrant III): Students will work in labs to complete the following: Lab 1 Set-up Equipment and Shut down Lab 2 Cutting of Steel Review (LSI Quadrants I and IV): Summary Review the key concepts of the lesson. Monitor the students as they are cutting Continue to review safety rules Informal Assessment (LSI Quadrant III): Evaluation Observe students as they set up the equipment and make their cuts. Formal Assessment (LSI Quadrant III, IV): The students will show mastery of 70% on the assessment. Extension/Enrichment (LSI Quadrant IV): Those that master the test will practice cutting to make coupons for welding as the teacher continues to work with students have difficulties with making the cuts. 5

6 SAFETY PRECAUTIONS FOR OXYFUEL 1. Keep oil and grease away from all parts of the welding and cutting apparatus. 2. Secure the cylinders in an upright position so they cannot be overturned. 3. Face the regulator gauges up toward the ceiling, making it impossible to stand in front of them. 4. Store and use oxyfuel units in well-ventilated areas. 5. Acetylene pressure in the lines should never exceed 15 pounds per square inch. 6. Open the acetylene cylinder valve ¼ to ½ turn; if it is the wheel type, open all the way 7. Use a friction spark lighter to light the torch; never use matches or cigarette lighters. 8. Never use oxygen in pneumatic tools, to blow out lines, air up tires, or dust off clothing. 9. Never hang clothing on cylinders, running the risk of saturating them with oxygen and acetylene. 10. Do not convert an acetylene regulator to an oxygen regulator or vice versa. 11. Slowly open the oxygen cylinder valve to prevent a sudden surge. 12. Release or loosen the regulator adjusting screw before opening a cylinder valve. 13. Do not walk with a lighted torch or lay down a lighted torch. 14. Blow out hoses before attaching the torch. 15. Repair hoses with proper hose splicers, not friction tape. Never use a leaky hose. 16. Test for leaks with soap and water, not matches 17. If valves on cylinders are faulty or too tight, notify the supplier, undue force would be dangerous. 18. Keep a fire extinguisher handy at all times. 19. Dress properly and wear eye protection. 20. Prevent heat and sparks from getting to cylinders and hoses. 21. Do not arc on or hit a cylinder with a metal object. 22. Never use a cylinder as a ground in an electrical circuit. 23. Never make a guess; get the correct information from a qualified person and mark or otherwise designate empty cylinders. 6

7 LAB 1 PROCEDURE FOR TURNING OFF THE OXYFUEL RIG 1. Turn off the acetylene at the torch body (the flame will go out and the oxygen will blow out the carbon). 2. Turn off the oxygen at the torch. 3. Turn off the acetylene cylinder valve. 4. Bleed the acetylene hose and regulators, then close the torch valve (both gauges will drop to zero). 5. Screw out the acetylene regulator adjusting screw until loose. 6. Turn off the oxygen cylinder valve. 7. Bleed the oxygen hose and regulators and close the torch valve (both gauges will drop to zero). 8. Screw out the oxygen regulator adjusting screw until loose. 9. Recheck the valve and roll up the hose. If rig is not to be used for some time, remove the regulators and put the safety caps back on the cylinders. 7

8 LAB 2 PROCEDURE FOR TURNING ON THE OXYFUEL RIG 1. Valves on the torch body should be closed. 2. The adjusting screws on the regulators must be loose. 3. Turn on acetylene cylinder valve ¼ to ½ turn; if wheel type, open all the way. 4. Tighten the regulator adjusting screw to the desired working pressure. 5. Open the oxygen cylinder valve all the way. 6. Tighten the regulator adjusting screw to the desired working pressure. 7. If the cutting attachment is being used, open the torch body oxygen valve all the way. 8. Crack the acetylene valve and light. Blow the flame off the tip and slowly adjust in back. 9. Adjust to a neutral flame with the oxygen valve. The oxygen pressure can be 5 to 10 times higher than the acetylene pressure when cutting. Never exceed 15 pounds pressure per square inch on acetylene. When welding, the ratio of oxygen to acetylene is approximately 1:1. Oxygen and acetylene settings will vary depending on the attachment tip and thickness of metal to cut or weld. 8

9 Terminology 9

10 Oxy Fuel Welding Test - BURNING TEST DIRECTIONS: Mark the T if the statement if true. Mark the F if the statement is false. T F 1. Oxygen is a colorless, odorless, tasteless gas, and will support combustion. T F 2. Full cylinder for oxygen is 2,400 to 3,600 psi. T F 3. Beside cutting and welding with the oxyfuel flame, it can be used for cutting wood and cutting glass. T F 4. Check for leaks with oil or gas line after making repairs on torch hose or if you smell gas. T F 5. Full cylinder pressure for acetylene is approximately 250 psi. T F 6. A neutral flame has a rounded inner cone, quiet sound, and an equal mixture of oxygen and acetylene. T F 7. While cutting and welding, the tip of the inner cone should be held 5/16 to ½ inch above the metal. T F 8. Oxygen cylinders are equipped with double seated valves and should be opened all the way. T F 9. Acetylene cylinders not having the wheel type valve opener should be opened less than one turn. T F 10. Pressure in the acetylene hose line should never exceed 15 pounds psi. T F 11. Matches may be used for lighting the torch. T F 12. An oily wipe cloth should be used to clean out the oxygen cylinder fittings. T F 13. Cutting metal should be done over concrete floors. 10

11 Oxy Fuel Welding Test Answers Answer key to Burning Test 1. T 2. F 3. F 4. F 5. T 6. T 7. F 8. T 9. T 10. T 11. F 12. F 13. F 11