Design and Construction of an Inverter Type Arc Welding Machine
Chapter One
AIMS AND OBJECTIVES OF THE PROJECT
The main aim and objective of this project is to design and build and arc welding machine that operates on 36vdc at variable frequency which of benefit to urban area. This reduces the weight and size of the transformer use for welding.
To have an arc welding machine that is more efficient which produce neat welding.
Chapter Two
LITERATURE REVIEW
HISTORY OF ARC WELDING MACHINE
The history of joining metals goes back several millennia that are Bronze Age or Iron Age in Europe and the Middle East. At that age, the process of joining similar or dissimilar materials is by forge welding. Arc welding did not come into practice until much later. In 1802, Vasily Petro discovered continues electric arc [5] and subsequently proposed its possible practical application including welding. The French electrical inventor Auguste De Metitens produced the first carbon arc torch, patended in 1881, which was successfully used for welding lead in the manufacture of lead-acid batteries. In 1881-1882, a Russian inventor Nikolai Bernados created the electric arc welding method for steel known as carbon arc welding. This type of arc welding uses carbon electrodes.
The advantages in arc welding continued with the invention of metal electrodes in the late 19th century by a Russian Nikolai Slavyanor (1888), and an American, L.C Coffin. Around 1900, A.P Strohmenger released in Britain a coated metal electrode which gave a more stable arc. In 1905 Russian scientist Vladimir Mitkerich proposed the usage of three phase electric arc for welding. In 1919, alternating current welding was invented by C.J Hoslag but did not become popular for another decade [6]. Competing welding processes such as resistance welding and oxyfuel welding were developed during this time as well, [6] but both, especially the later, faced stiff competition from arc welding especially after metal coverings (known as flux) for the electrode, to stabilize the arc and shield the base material from purities, continued to be developed [3].
During World War I, welding started to be used in ship building in Britain in place of riveted steel plates. The Americans also became more accepting of the new technology when the process allowed them to repair their ships quickly after a German attack in the New York Harbor at the beginning of the war. Arc welding was first applied to aircraft during the war as well, and some German airplane fuselages were constructed using this process [1]. In 1919, the British shipbuilder Cammell Laird started construction of merchant ship, the fullagar, with an entirely welded hull.
During the 1920s, Major advances were made in welding technology. Shielding gas became a subject receiving much attention as scientist attempted to protect welds from the effects of oxygen and nitrogen in the atmosphere. Porosity and brittleness were the primary problems and the solutions that developed included the use of hydrogen, argon, and helium as welding atmospheres. During the following decade, further advances allowed for the welding of reactive metals such as an aluminum and magnesium. This in conjunction with developments in automatic welding, alternating current, and fluxes fed a major expansion of arc welding during the 1930s and then during World War II [1].
Many new welding methods were invented in the middle of the century. Submerged arc welding was invented in 1930 and continues to be popular today. In 1932 a Russian, Konstantin Khrenor successfully complemented the first underwater electric arc welding. Gas tungsten arc welding was perfected in 1914 and gas metal arc welding followed in 1948, allowing for fast welding of non- ferrous materials but requiring expensive shielding gases. Using a consumable electrode and a carbon dioxide atmosphere as a shielding gas, it quickly became the most popular metal arc process. In 1957, the flux-cored arc welding process debated in which the self shielded wire electrode could be used with automatic equipment, resulting in greatly increased welding speeds. In that same year, plasma arc welding was invented. Electroslag welding was released in 1958 followed by Electrogas welding in 1961.
Arc welding is a type of welding power supply to create an electric arc between and electrode and the base material to melt the metals at the welding point. 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, and/or slag.
PROCESS OF ARC WELDING
- Gas metal arc welding
- Flux-cored arc welding(FCAW)
- Submerged arc welding(SAW)
CONSUMABLE ELECTRODE AND NON-CONSUMABLE ELECTRODE METHODS
CONSUMABLE ELECTRODEMETHODS
One of the most common types of arc welding is shielded metal arc welding (SMAW), which is also known as manual metal arc welding (MMAW) or stick welding. An electric current is used to strike an arc between the base material and a consumable electrode rod or stick. The electrode rod is made of a material that is compatible with the base material being welded and is covered with a flux that gives off vapors that serve as a shielding gas and providing a layer of slag, both of which protect the weld area from atmospheric contamination. The electrode core itself acts as filler material, making separate filler unnecessary. The process is very versatile, requiring little operator training and inexpensive equipment. However, weld times are rather slow, since the consumable electrodes must be frequently replaced and because slag, the residue from the flux, must be chipped away after welding.[3] Furthermore, the process is generally limited to welding ferrous materials, though specialty electrodes have made possible the welding of cast iron, nickel, aluminum, copper and other metals. The versatility of the method makes it popular in a number of applications including repair work and construction.
CHAPTER THREE
METHODOLOGY AND SYSTEM ANALYSIS
METHODOLOGY
My approach to this project is realized through the design and implementation of its input subsystem, control unit and output subsystem. The welding of a metal occurs when the control unit and the output subsystem links together through the conductive objective to be welded. Welding is the process of joining two or more similar or dissimilar material with/without the application of heat and/or pressure with or without using the filler material.
DESIGN METHOLOGY
In the design I started with the overall system and begin to partion it into systems. The handy tool used at this stage is the block diagram shown below in fig3.1 the block diagram depicts the hierarchy of how the inverter sub-circuits will interact and interface with each other. A computer aided design software known as proteus (ISIS professional) was used for the design simulation of the paper design before the first hardware prototype was actualized or realized on an experimental breadboard. This was achieved through the implementation of the inverter input subsystem to the output subsystem. These were carefully done according to the project block diagram and the final schematic circuit diagram.
The system block diagram of the inverter arc welding machine project is shown in fig3.1
CHAPTER FOUR
SYSTEM DESIGN AND IMPLIMENTATION
INTRODUCTION
In this chapter we are to elaborate on each stage seen in chapter 3. Each stage is associated to a group of components/ device, which is aimed at achieving a specific purpose. In design a circuit, we first have to determine the power to the load and some other necessary parameters as the case may be. Stage 1 is the power supply, stage 2 is the oscillator, stage 3 is the power amplifier, and finally the transformer stage.
CHAPTER FIVE
SYSTEM TESTING AND INTEGRATION
TESTING
After the design and implementation phase, the system built has to be tested for Durability, Efficiency, and Effectiveness and also ascertain if there is need to modify this design. The system was first assembled using a breadboard. All components were properly inserted into the breadboard according to the designed circuit and tests were carried out at various stages. To ensure proper functioning of components’ expected data, the components were tested using a digital multimeter (DMM).
TEST PLAN AND TEST DATA
This chapter entails an overall system testing of the integrated design of the voltage measurement device. The testing and integration is done to ensure that the design is functioning properly as expected thereby enabling one or even intended users for which the project was targeted for, appreciate its implementation and equally approaches used in the design and integration of the various modules of the project. However, this involves checks made to ensure that all the various units and subsystems function adequately. Also there has to be a good interface existing between the input/output unit subsystems. When the totality of the modules was integrated together, the system was created and all modules and sections responded to as specified in the design through the power supply delivering into the system designed.
CHAPTER SIX
SUMMARY, RECOMMENDATION AND CONCLUSION
This section of this project report forms the concluding part of the write up and takes a look at some of the problems encountered during the progressive job on the system and also brings in suggestions for further improvement and/or enhancement for the system design.
SUMMARY OF ACHIEVEMENT
The design and development of this project has really been challenging, as I have been faced with choices far beyond what I expected. But in the long run the result paid off. After the complete design of the system, the deviation between the expected result and the actual result was very close. The performance and efficiency was beyond expectation and from every ramification, the design of the project was a success.
PROBLEMS ENCOUNTERED AND SOLUTION
During the course of the design of this system, there were series of problems which came in the way of achieving the design goals of this project, most of them where over come via share troubleshooting, in some cases some parts require redesigning and the software debugging also created a bit of a problem. One major setback of this project is the availability of components required to build the hardware of the system. In most cases I had to look through electrical catalogs to obtain replacements of some of the components which are not available in the market. After developing the transformer, it was very difficult to find a clamp. This posed serious problem as it brought about delay in the design time and it was also costly, this also affected the overall cost of the system. The final packaging of the design was also another trouble. This was actually one of the most challenging aspects of the circuit implementation phase.
RECOMMENDATION
This design of inverter arc welding machine can still be improved to get more efficient, portable inverter welding machine. To achieve this I recommend the following;
- Engineering students need early exposure to the use of electronic componentsfor practical work, this will enable them know some high power semiconductor and low power
- Further research in the field of electronic switching, transformer design will go a long way in getting better inverter arc welding
- Ensure that accurate components are used to avoid endangering the operatorand for reliability
CONCLUSION
Welding is a fabrication process that joins materials, usually metals or thermoplastics. This is often done by melting the work-piece and adding a filler material to form a pool of molten material (the weld pool) that cools become a strong joint. The melting is achieved with pressure sometimes used in conjunction with heat, to produce the weld. Different power supply can be used for welding which include inverter arc welding power supply. Inverter arc welding machine transform low voltage low amperage primary power into the low voltage, high amperage power used for welding at high frequency. This high frequency transformation helps to reduce the weight and size of the transformer. The output power is precisely control by the inverter due high operating frequency.
REFRENCES
- Lincolin E., pg 1.1- 6 (1994). “the Procedure Handbook of Arc Welding” : Cleveland,Ohio
- Kalpakjian, Serope,Steven (2001). “Manufactuering Engineering and Technology”: Prentice hall
- Weman Klas, pg 16, 26 (2003). “Welding Process Handbook”: New York, CRC press
- Http: //miller welds. Com/ education/ articles/ article 31.html
- Great Soviet Encyclopedia, Article “ElectricArc”
- Cary, Howard B., Helzer Pg 5-7, 9 (2005).”Modern Welding Technology”: upper saddle river, NewJersey
