Construction Of A Welding Machine 220V/250A

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Overview

This project is titled the designing and construction of an electric A.C arc welding machine. Electric Arc Welding Machine of 220 Volts and output voltage of 32volts. A core type step-down transformer and choke are essential as the voltage or the arc is 32v. The choke is necessary to displace the phase relationship of the voltage and current so that the heat of the arc may be maintained by ensuring that zero points of current and voltage are as far apart as possible. This welding machine is able to deliver a current 250Amps at voltage of 220 volts, the transformer is mounted on a rectangular metal frame and its enclosed by a case which has opening at a regular internal order to provide air for the cooling of the transformer. A double insulation technique is employed for better protection from electric shock and short circuit in the machine or when working in moist environment. An all-purpose electrode holder is connected across one or the output terminal of the transformer so that various size of electrode can be held properly. After the transformer had been constructed, the primary terminals were connected to source of supply. Then the secondary terminal was connected to the welding circuit, as a source of supply, with the aid of welding cable, by which one of the terminal was \connected to the ground clamp and the other to the electrode holder. A.C. Electric Arc Welding Machine uses alternating (AC) current, and consumable or non-consumable electrodes. The welding region is usually protected by some type of shielding gas, vapor, and/or slag.

The aim of this work is to design and construct an electric welding arc that can be used to weld metals.

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWLEDGMENT

ABSTRACT

TABLE OF CONTENTS

CHAPTER ONE

1.0 INTRODUCTION

1.1 BACKGROUND OF THE PROJECT

1.2 AIM/OBJECTIVE OF THE PROJECT

1.3 SIGNIFICANCE OF THE PROJECT

1.4 SCOPE OF THE PROJECT

1.5 PURPOSE OF THE PROJECT

1.6 LIMITATION OF THE PROJECT

1.7 TYPES OF ELECTRIC ARC WELDING

1.8 APPLICATION OF THE PROJECT

1.9 PROBLEMS OF THE PROJECT

1.10 PROJECT ORGANISATION

CHAPTER TWO

2.0 LITERATURE REVIEW

HISTORICAL BACKGROUND OF THE PROJECT
TRANSFORMER DESIGN
REVIEW OF TYPES OF ARC WELDING ELECTRODE METHODS:
REVIEW OF WELDING EQUIPMENT
FACTORS AFFECT WELD QUALITY

CHAPTER THREE

3.0 CONSTRUCTION METHODOLOGY

BLOCK DIAGRAM
BASIC PRINCIPLE OF ARC WELDING MACHINE
THEORY AND DESIGN OF WELDING TRANSFORMERS
SYSTEM OPERATION
DESIGN CALCULATION
COST ANALYSIS

CHAPTER FOUR

4.0 RESULT ANALYSIS

CONSTRUCTION PROCEDURE
CASING AND PACKAGING
ASSEMBLING SECTION
SYSTEM TESTING
DESIGN PRECAUTION

CHAPTER FIVE

CONCLUSION AND RECOMMENDATION
- CONCLUSION
- RECOMMENDATION
- REFERENCES

CHAPTER ONE

1.0 INTRODUCTION

An Arc welding machine is a type of welding machine that uses a welding power supply to create an electric arc between an electrode and the base material to melt the metals at the welding point. The arc welding is a fusion welding process in which the welding heat is obtained from an electric arc struck between the work(or base metal) and an electrode. The temperature of the heat produced by the electric arc is of the order of 6000°C to 7000°C [Weman Klas, 2003].

They can use either direct (DC) or alternating (AC) current, and consumable or non-consumable electrodes. The welding region is usually protected by some type of shielding gas, vapor, or slag. Arc welding processes may be manual, semi-automatic, or fully automated. First developed in the late part of the 19th century, arc welding became commercially important in shipbuilding during the Second World War. Today it remains an important process for the fabrication of steel structures and vehicles [Weman Klas, 2003].

Arc welding machine has Main cable that receives energy from the source (220 or 440 Volts AC), the starter or switch, the transformer, the controls of tension (Voltage) and current (Amps-or-Amperage), the two secondary wires: one is to ground the machine to the building + structure + part that you are to weld, the other is to put your electrode and produce the welding

The direction of current used in arc welding also plays an important role in welding. Consumable electrode processes such as shielded metal arc welding and gas metal arc welding generally use direct current, but the electrode can be charged either positively or negatively [Faraday Michael, 1834]. In welding, the positively charged anode will have a greater heat concentration and, as a result, changing the polarity of the electrode has an impact on weld properties. If the electrode is positively charged, it will melt more quickly, increasing weld penetration and welding speed. Alternatively, a negatively charged electrode results in more shallow welds. Non-consumable electrode processes, such as gas tungsten arc welding, can use either type of direct current (DC), as well as alternating current (AC). With direct current however, because the electrode only creates the arc and does not provide filler material, a positively charged electrode causes shallow welds, while a negatively charged electrode makes deeper welds. Alternating current rapidly moves between these two, resulting in medium-penetration welds. One disadvantage of AC, the fact that the arc must be re-ignited after every zero crossing, has been addressed with the invention of special power units that produce a square wave pattern instead of the normal sine wave, eliminating low-voltage time after the zero crossings and minimizing the effects of the problem [Weman Klas, 2003].

AIM AND OBJECTIVE OF THE PROJECT

The aim of this work is to design and construct an electric arc machine that can be used to weld irons. To design and construct an electric machine that will create an electric arc between an electrode and the base material to melt the metals at the welding point.

The objective of this work is:

At the end of the work an electric arc welding is been built with a power source of 220 VAC with 32 a.c output taps ranging from 140VAC to 220VAC which are used to step the arc voltage and current to the required level.
- PURPOSE OF THE PROJECT

The purpose of his work is to design an electrical machine that uses a welding power supply to create an electric arc between an electrode and the base material to melt the metals at the welding point. They can use on alternating (AC) current, and consumable or non-consumable electrodes.

1.3 SIGNIFICANCE OF THE STUDY

AC Arc Welding Transformers are extensively used today in machine building and general purpose maintenance and fabrication work. Light medium and heavy structural work as a Power Source.
The safety advantages of switching to welding machine include reduced health hazards for workers. From limiting exposure to hazardous fumes to decreased risk of arc burn, arc welding machine help to save workers from a once dangerous job.
It has high welding efficiency and speed.
It provides better welding environment.
It gives consistent quality of weld.
It forms the strong bond in between the joined metals.
It has simple welding equipment.
Power source is not so expensive.
It is fast and reliable process.
Equipments can be used for multiple functions.
Welders can use standard domestic current.

1.4 LIMITATION OF THE PROJECT

1) Higher initial setup cost

2) Atmosphere surrounding the welding process has to be stable (hence the shielding gasses), therefore this process is limited to draught free conditions

3) Higher maintenance costs due to extra electronic components

4) The setting of plant variables requires a high skill level

5) Less efficient where high duty cycle requirements are necessary

6) Radiation effects are more severe

7) the rated output current is 250A

1.5 BENEFIT OF THE PROJECT

An arc welding machine uses a process which applies intense heat to metal at a joint, causing the metal to melt and intermix. Arc welding machine has several benefits, including improved weld consistency, decreased cycle times, and enhanced efficiency.

1.6 APPLICATION OF THE PROJECT

Arc welding utilizes an electric arc between an electrode and a metal base using either consumable or non consumable electrodes. This welding machine is commonly found in steel product and automobile manufacturing. Other applications include [Lincoln Electric, 1994]:

Construction: Arc Welding processes are a foundational aspect of all large-construction industries, ensuring strong, sustainable connections within buildings, bridges and other infrastructures.

Mechanical: For more rugged applications that involve thicker metal dimensions, arc welding provides the control and effectiveness necessary to firmly bond heavier pieces together. In the automotive industry, arc welds bond heat shields, exhaust systems and hydraulic lines to the chassis. Metal furniture pieces like office desks, file cabinets and shelving units are often welded. Heating, ventilation and air conditioning units are usually constructed using welding processes.

Equipment: Most, if not all, of today’s industries rely on properly functioning equipment, and welding processes are vital to the success of those machines.

Farm equipment: In agriculture, farm machines that plow, plant, seed and harvest are fundamental to the country’s food supply. Those machines are welded throughout their frames and processes. On the chassis, the cab frame, fenders and brackets are formed by welds. Motor structure and electrical functions are fused, as are the features of specialized tools such as threshers and spreaders. These machineries can be welded using arc welding machine [Weman Klas, 2003]

Lawn and garden: Lawn mowers, trimmers, power saws and other garden equipment have long lives due to the strength of their welded frames. Other metal garden features enhance the enjoyment of outdoor life, such as barbecue grills, enclosures, seating and watering systems [Kalpakjian, Serope; Schmid, Steven R. 2001].

Highway equipment: Maintenance of safe and passable roads also depends on secure welds. Manhole cover plates and the sewer and utility systems that frequently run under roads are also usually constructed with welding processes.

Institutional equipment: Hospitals, medical facilities, schools and homes all rely on well-functioning appliances to keep food warm or cold, run accurate testing operations and clean clothing or dishes. Virtually every appliance in use today was constructed at least in part with a arc welding process.

1.7 TYPES OF ELECTRIC ARC WELDING

Arc welding can be direct current (D.C) or alternating current (A.C) arc welding, but the types of arc welding depending upon the type of electrode [Weman Klas, 2003]:

(A): Unshielded arc welding:

When a large electrode or filler rod is used for welding, it is said to be un- shielded arc welding.

(B): Shielded arc welding:

When the welding rods coated with fluxing material are used, then it is called shielded arc welding [Kalpakjian, Serope; Schmid, Steven R. 2001].

1.8 PROBLEM OF THE PROJECT

High skilled operator is required to do arc welding and also heavy to carry because of the iron cores and copper wires.

1.9 PROJECT WORK ORGANISATION

The work is organized as follows: chapter one discuses the introductory part of the work, chapter two presents the literature review of the study, chapter three describes the methods applied, chapter four discusses the results of the work, chapter five summarizes the research outcomes and the recommendations.

CHAPTER TWO

2.0 LITERATURE REVIEW

2.1 HISTORICAL BACKGROUND OF ELECTRIC ARC WELDING

In 1802, Vasily Petrov discovered the continuous electric arc and subsequently proposed its possible practical applications, including welding. The French electrical inventor Auguste de Méritens produced the first carbon arc torch, patented in 1881, which was successfully used for welding lead in the manufacture of lead-acid batteries. In 1881–1882, a Russian inventor…