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Modification Of An Existing Metal Sheet-bending Machine
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3.2.2. Mechanical Properties of Metal
The mechanical properties of metals are those which are associated with the ability of the material to resist mechanical force and loads. These mechanical properties of metal include strength, stiffness, elasticity, plasticity, ductility, brittleness, malleability, toughness, resilience, creep and hardness (Ryder, 1969).
1. Strength: It is the ability of a material to resist external applied forces without breaking or yielding. The internal resistance offered by a part to an externally applied force is called stress.
2. Stiffness: It is the ability of a material to resist deformation under stress. The modulus of elasticity is the measure of stiffness.
3. Elasticity: It is the property of a material to regain its original shape after deformation when the external forces are removed. This property is desirable for the materials used in tools and machines.
4. Plasticity: It is the property of a material which retains the deformation produced under load permanently. This property of materials is necessary for forging, stamping images on coins and ornamental works.
5. Ductility: It is the property of a material enabling it to be drawn into wire with the application of a tensile force. A ductile material must be both strong and plastic. The ductility is usually measured by the terms, percentage elongation and percentage reduction in area. The ductile material commonly used in engineering practice (in order of diminishing ductility) are mild steel, copper, aluminum, nickel, zinc, tin and lead.
6. Brittleness: It is the property of a material opposite to ductility. It is the property of breaking of material with little permanent distortion. Brittle material when subjected to tensile loads, snap off without giving any sensible elongation. Cast iron is a brittle material.
7. Malleability: It is a special case of ductility which permits materials to be rolled or hammered into thin sheets. A malleable material should be plastic but it is essential to be so strong. The malleable materials commonly used in eng practice (in order of diminishing malleability) are lead, soft steel, wrought iron, copper and aluminum..
8. Toughness: It is the property of a material to resist fracture due to high impact loads like hammer blows. The toughness of the material decreases when it is heated. It is measured by the amount of energy that a unit volume of the material as absorbed after being stressed up to the point of fracture. This property is desirable in parts subjected to shock and impact loads.
9. Machinability: It is the property of a material which refers to a relative ease with which a material can be cut. The machinability of the material can be measured in a number of ways such as comparing the tool life for cutting different materials or thrust required to remove the material at some given rate or the energy required to remove a unit volume of the material. It may be noted that brass can be easily machined than steel.
10. Resilience: It is the property of a material to absorb energy and to resist shock and impact loads. It is measured by the amount of energy absorbed per unit volume within elastic limit. This property is essential for spring materials.
11. Creep: When a part is subjected to a constant stress at high temperature for a long of time, it will undergo a slow and permanent deformation called creep. This property is considered in designing internal combustion engines, boilers and turbines.
12. Fatigue: when a material is subjected to repeated stresses or loads, it fails at stress below the yield point stresses. Such type of failure of a material is known as fatigue The failure is caused by means of a progressive crack formation which are usually fine arid microscopic in size. This property is considered in designing shafts, connecting rods, springs, gears e.t.c.
13. Hardness: It is a very important property of metals and has a wide variety of meanings. It embraces many different properties such as resistance to wear, scratching, deformation and machinability. It also means the ability of a metal to cut another metal. The hardness is usually expressed in number which are dependent on the method of making the test. The hardness of mental may be determined byt the following test:
a. Brinell hardness test
b. Rockwell hardness test
c. Vicker’s hardness (also called diamond pyramid) test
d. shore scleroscope
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ABSRACT - [ Total Page(s): 1 ]ABSTRACT IS COMING SOON ... Continue reading---
TABLE OF CONTENTS - [ Total Page(s): 1 ]TABLE OF CONTENTFront page Certification Dedication Acknowledgment Abstract Table of content Project topic Aim Procedures Selected materials Equipment CHAPTER ONE1.0 INTRODUCTION 1.1 Importance of Sheet Metal Work and Bending Machines 1.2 Historical Review and Classification of Bending Machines. 9-121.3 Operational Characteristic of the Bending Machine CHAPTER TWO2.0 BENDING TECHNOLOY 2.1 Principles of Bending 2.2 The mechanics of Bending 2.3 Pla ... Continue reading---
CHAPTER ONE - [ Total Page(s): 4 ]CHAPTER ONE1.0 INTRODUCTION1.1 Importance of Sheet Metal Work and Bending MachineWhat is a metal? It is a strong shinny, which conducts electricity and melts when you make it hot enough. But surely metal must be something more than this because there are other substances such as carbon,, glass and rubbers, which are, obviously not metals but can also variously claim to have strength, elasticity or electrical conductivity.Furthermore, most of the metals will melt when heated sufficien ... Continue reading---
SELECTED MATERIALS - [ Total Page(s): 1 ]SELECTED MATERIALSGauge Dimension• 4mm plate - 1200 x 1200mm• H Channel (8inch x 5inch) - 2.550mm• 12mm Plate (8ft x 1ft) - 2.850mm• 12mm Plate - 304 x 2550mm• 50mm Plate - 2,352 x 588mm•  40mm Shaft ... Continue reading---
AIM - [ Total Page(s): 1 ]To design and construct a mental sheet-bending machine component which is manually operated. A machine with working capacity to complete a 90o fold of a full-length plate (8ft = 2400mm) and up to 2.5mm thickness. ... Continue reading---
PROEDURES - [ Total Page(s): 1 ]These are the procedures for designing and constructing a metal sheet-bending machine.- Initial Machine Design - Materials Selection- Costing- Purchasing of the selected Materials- Equipment Used for the Construction ... Continue reading---
EQUIPMENTS - [ Total Page(s): 1 ]EQUIPMENTSï¶ Moulding flaskï¶ Hack Sawï¶ Grinding Stonesï¶ Cutting Stoneï¶ Shearing Machineï¶ Arc Welding Machineï¶ Drilling Machineï¶ Grinding Machineï¶ Lathe Machineï¶ Metal Bending Machineï¶ Shapping machine ï¶ Muilding machine ï¶ Driving machineï¶ Feed taping tool ... Continue reading---
CHAPTER TWO - [ Total Page(s): 4 ]Fig 2.6: Over bending to compensate for spring back.The nose of the bending blade is at an angle of 45° to allow for over bending when bending at 900. After the force applied is released, the material spring back and the required bend is achieved. Fig 2.6(b) shows a bend having a spring back angle i.e. distance between the over bending and the assumed position.2.6 Method of Determining Angle of Spring BackThe only practicable method to determine spring back is by experiment, others are based ... Continue reading---
CHAPTER FOUR - [ Total Page(s): 1 ]CHAPTER FOURCOMPONENT DESIGN AND CONSTRUCTION Sand casting is one of the quickest and most cost effective methods adopted in the production of metal prototypes and is an excellent solution for low to medium run of pasts that do not require a specific or precise shape repeatability. The summary of making a cast material using sand casting process are as follows.1. A mold was created by placing the mixture of sand, clay and water on a pattern, and when the pattern was removed ... Continue reading---
CHAPTER FIVE - [ Total Page(s): 1 ]CHAPTER FIVE5.1 Analysis Every sector of the economy is experiencing changes. The production sector is not left out of the changes, infact it is more affected. Sheet metal today is used for doors, windows, frames, gates, etc.It’s worthy to mention, however that the road side welders have developed various ways of bending sheet metal manually, but most often, they generally have poor finishing. As a result, their output does not justify their effort or input.It could be said, that th ... Continue reading---
REFRENCES - [ Total Page(s): 1 ]REFERENCESCourtney, J.V. (1980): Workshop Processes and Materials. Van Nosh Reinhold Company Ltd Workinghan, England, Pg. 21.John, R. Walker (1976), Exploring Metal Work-Basic Fundamentals. Good Head-will Cox, South Holland, Pg. 78-80.Khurmi, R.S. and Gupta J.K. (1979). A textbook of Machine Design. Eurasia publishing house (pvt) ltd New Delhi, Pg. 15.Smith, F.J.M. (1982): Basic Fabrication, and Welding Engineering: Longman, England, Pg. 23-24Surenda, Singh (1979): Strength of material, Vikas Pu ... Continue reading---
