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The diagram illustrates the process of submerged arc welding - Leaving Cert Engineering - Question 5 - 2007
Question 5
The diagram illustrates the process of submerged arc welding. Describe the main features of this type of welding making reference to: (i) principle of operation; (i... show full transcript
Worked Solution & Example Answer:The diagram illustrates the process of submerged arc welding - Leaving Cert Engineering - Question 5 - 2007
Step 1
principle of operation
Answer
In submerged arc welding, a bare wire electrode is used. It is fed automatically from a spool and generates an electric arc to heat the metal. The flux in powder form is fed from a hopper to completely cover the joint and the tip of the electrode. The arc creates heat to melt the joint, flux, and electrode. A slag is formed to produce a protective coating for the weld. The excess flux powder can be collected and reused. Submerged arc welding is a fully controlled process.
Step 2
Step 3
Redraw the incomplete welding transformer circuit shown and insert the missing components for A and B
Answer
The incomplete welding transformer circuit should depict a step-down transformer that converts high AC voltage (220V) to a lower voltage suitable for arc welding. Component A could represent a smoothing capacitor, which ensures a more uniform direct current (DC) output, while Component B might represent a rectifier to convert AC to DC.
Step 4
Describe the purpose of the components A and B
Answer
Component A, the step-down transformer, is used to reduce high voltage AC to a lower voltage suitable for welding. Component B, the smoothing capacitor, stabilizes the current output and minimizes fluctuations, providing a more consistent welding environment.
Step 5
Step 6
Outline three safety precautions associated with the preparation of materials and equipment for welding
Answer
- Ensure that all equipment is well maintained with cables secured and insulated properly to prevent electric shock.
- Clean and degrease surfaces to be welded to minimize harmful fumes during the welding process.
- Wear appropriate protective clothing, including gloves and aprons, to safeguard against heat and splatter. Install welding curtains or cubicles to protect others from UV light emitted during the welding process.
Step 7
Describe, with the aid of a suitable diagram, the main features of one of the following: Resistance seam welding
Answer
Resistance seam welding is a process that utilizes copper roller electrodes to provide a continuous flow of overlapping spot welds. The rollers supply current in pulses, leading to the formation of spot welds as the workpiece moves between them. The timer ensures that the duration of the current pulses is sufficient to achieve reliable welding without overheating the material.