1 Lecture 1 Fundamentals of Metal Forming Course Hour: 3 Basic requirements: Recalling the principles and concepts of the course “Metal forming: mechanics and principles” Acquainting with classification of forming processes, Acquainting with temperature in metal working, hot working, cold working, strain rate effects, metallurgical structure, hydrostatic pressure, workability, residual stresses; acquainting with friction and lubrication in metal forming processes mechanics of metal working Emphasis: classification of forming processes and temperature in metal working, Temperature in metal working, friction and lubrication in metal forming processes Difficulties: Mechanics of metal working, Residual stress Home work: Read the textbook from pages 287-297
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1 Lecture 1 Fundamentals of Metal Forming Course Hour: 3 Basic requirements: Recalling the principles and concepts of the course “Metal forming: mechanics.
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Lecture 1 Fundamentals ofMetal Forming
Course Hour: 3Basic requirements: Recalling the principles and concepts of the course “Metal forming: mechanics and principles” Acquainting with classification of forming processes, Acquainting with temperature in metal working, hot working, cold working, strain rate effects, metallurgical structure, hydrostatic pressure, workability, residual stresses; acquainting with friction and lubrication in metal forming processes mechanics of metal workingEmphasis: classification of forming processes and temperature in metal working, Temperature in metal working, friction and lubrication in metal forming processesDifficulties: Mechanics of metal working, Residual stressHome work: Read the textbook from pages 287-297
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Metal Forming
Plastic Deformation to Change Shape
No Volume Change Stresses > Yield Good Forming Properties
Low Yield Strength
High Ductility
Elevated temperature low strain
rate and lubrication can Help
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Bulk forming
◆ Characterized by significant deformations and massive shape changes◆ "Bulk" refers to workparts with relatively low surface area-to-volume ratios◆ Starting work shapes include cylindrical billets and rectangular bars
Rolling
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Forging
Extrusion
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Drawing
Sheet Metal
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Bulk Deformation Significant Deformations Massive Shape Changes (w/o Waste) “Blacksmith” Work in Plastic Region Flow Stress
Yf= Kn
Flow Stress Curve
Material Behavior – Flow StressMaterial Behavior – Flow Stress
= K = K nn
Concept of Concept of flow stressflow stress, Y, Yff – the instantaneous stress required to deform the material – the instantaneous stress required to deform the material
YYf f = K = K nn
Process force considerations:Process force considerations:
* during compression, determine instantaneous force from Yf
* max force is often all that is required, typically at end of stroke* force analysis may be based on average stresses and strains
K and n depend on working temperature, characterized by 3 ranges: Cold working, Warm working, K and n depend on working temperature, characterized by 3 ranges: Cold working, Warm working, Hot workingHot working