Introduction to Manufacturing Processes docx

1 1 ME 4563 Fall ’05 Dr. S. Haran (10.06.2005) (10.06.2005) (10.06.2005) Fall 2005 College of Engineering Arkansas State University Fall 2005 Fall 2005 College of Engineering College of Engineering Arkansas State University Arkansas State University Introduction to Manufacturing Processes Introduction to Manufacturing Introduction to Manufacturing Processes Processes ME 4563 ME 4563 ME 4563 2 ME 4563 Fall ’05 Dr. S. Haran Bulk Deformation Bulk Deformation 2 3 ME 4563 Fall ’05 Dr. S. Haran Rolling Rolling 4 ME 4563 Fall ’05 Dr. S. Haran What is Rolling ? What is Rolling ?   A process of reducing the thickness A process of reducing the thickness (or changing the cross (or changing the cross - - section of long section of long work work - - piece piece   By applying compressive forces By applying compressive forces through a set of rolls through a set of rolls 3 5 ME 4563 Fall ’05 Dr. S. Haran Some Rolling Facts Some Rolling Facts … …   Process developed in late 1500 Process developed in late 1500 ’ ’ s s   Accounts for over 90% of all metals produced by Accounts for over 90% of all metals produced by metalworking process by volume metalworking process by volume   Various cross Various cross - - sectional shapes are achieved sectional shapes are achieved   Major metal that is rolled is Steel, followed by Major metal that is rolled is Steel, followed by Aluminum Aluminum   Can be carried out Hot or Cold Can be carried out Hot or Cold   Machinery for Rolling (called Machinery for Rolling (called “ “ Mills Mills ” ” ) have a variety ) have a variety of configurations of configurations   Several parameters to be considered in practice, in Several parameters to be considered in practice, in the design and selection of machines the design and selection of machines 6 ME 4563 Fall ’05 Dr. S. Haran Schematic outline of Schematic outline of various flat various flat - - and and shape shape - - rolling rolling processes. processes. Source Source : : American Iron and American Iron and Steel Institute. Steel Institute. Rolling Rolling 4 7 ME 4563 Fall ’05 Dr. S. Haran • • Plates Plates • • Sheets Sheets • • Rods Rods • • Foil Foil • • Pipes and tubes Pipes and tubes • • Shape rolled products such as channel, I, L, T, Shape rolled products such as channel, I, L, T, etc. etc. • • Other structural shapes also made Other structural shapes also made Rolling Rolling – – Products include Products include 8 ME 4563 Fall ’05 Dr. S. Haran Major Metals that are Rolled include: Major Metals that are Rolled include: • • Steel Steel • • Aluminum Aluminum • • Others like Copper, Brass, Lead, etc. Others like Copper, Brass, Lead, etc. • • Special applications Special applications – – Titanium and Titanium and other other exotic metals exotic metals Rolling Rolling 5 9 ME 4563 Fall ’05 Dr. S. Haran Direct Applications Direct Applications - - where rolled where rolled plates/sheets are used plates/sheets are used • • Aircraft bodies Aircraft bodies • • Ship hulls Ship hulls • • Reactor vessel Reactor vessel walls walls • • Boilers Boilers • • Bridges Bridges • • Tanks, etc. Tanks, etc. Rolling Rolling Indirect Applications Indirect Applications - - where rolled plates/sheets where rolled plates/sheets are used after further are used after further processing processing • • Locomotives Locomotives • • Automobiles Automobiles • • Appliances Appliances • • Food/Beverage Food/Beverage containers containers • • Office equipment, Office equipment, • • Construction, etc. etc. Construction, etc. etc. 10 ME 4563 Fall ’05 Dr. S. Haran Classifications of Rolling Material Classifications of Rolling Material Rolling material is separated into classifications based Rolling material is separated into classifications based on the material's cross on the material's cross - - sectional dimensions sectional dimensions Cross Cross - - Section Section Thickness Thickness Width Width Bloom Bloom Square Square > 6 in. > 6 in. < 2 * thickness < 2 * thickness Billet Billet Square or Circular Square or Circular < 6 in. < 6 in. < 2 * thickness < 2 * thickness Slab Slab Rectangular Rectangular > 2 * thickness > 2 * thickness Plate Plate 0.25 in. < x < 12 in. 0.25 in. < x < 12 in. Sheets Sheets 0.008 in. < x < 0.25 in. 0.008 in. < x < 0.25 in. Foil Foil <0.008 in. <0.008 in. Rolling Rolling 6 11 ME 4563 Fall ’05 Dr. S. Haran What kind of Thickness are we talking about ? What kind of Thickness are we talking about ? When Manufactured: When Manufactured: Rolled Plates: normally > 6mm Rolled Plates: normally > 6mm Rolled Sheets: normally < 6mm Rolled Sheets: normally < 6mm • • Aircraft Body: 1 Aircraft Body: 1 – – 2mm thick 2mm thick • • Aluminum beverage cans: 0.1 Aluminum beverage cans: 0.1 – – 0.28mm thick 0.28mm thick • • Aluminum Foil: 0.008mm thick (wrapping) Aluminum Foil: 0.008mm thick (wrapping) And the range of applications And the range of applications … … Rolling Rolling 12 ME 4563 Fall ’05 Dr. S. Haran Two Major types of rolling processes Two Major types of rolling processes - - • • Flat rolling Flat rolling – – to produce Plates to produce Plates and and Sheets of metal Sheets of metal • • Profile (or Shape) rolling Profile (or Shape) rolling – – to to produce all other possible produce all other possible shapes shapes Rolling Rolling 7 13 ME 4563 Fall ’05 Dr. S. Haran Flat Rolling Flat Rolling Hot Rolling Hot Rolling Cold Rolling Cold Rolling Pack Rolling Pack Rolling Flat Rolling Process can be Flat Rolling Process can be divided into THREE major divided into THREE major types: types: Rolling Rolling 14 ME 4563 Fall ’05 Dr. S. Haran Flat Rolling Process Flat Rolling Process Hot Rolling Hot Rolling Cold Rolling Cold Rolling Pack Rolling Pack Rolling Converts a cast structure into a Converts a cast structure into a wrought structure; rolled above the wrought structure; rolled above the re re - - crystallization temperature crystallization temperature (process in which new (process in which new equiaxed equiaxed / strain free / strain free grains are formed, replacing old grains) grains are formed, replacing old grains) Carried out a room temperature; Carried out a room temperature; better finish, mechanical properties better finish, mechanical properties Two or more layers of metals are Two or more layers of metals are rolled together; improves rolled together; improves productivity (Al foil) productivity (Al foil) Rolling Rolling 8 15 ME 4563 Fall ’05 Dr. S. Haran Other Flat Rolling Process Other Flat Rolling Process Temper Rolling Temper Rolling Leveling Leveling Sheets subject to a final pass Sheets subject to a final pass – – strain strain in the sheets are removed (sheets in the sheets are removed (sheets undergo yield point elongation undergo yield point elongation during rolling); also called during rolling); also called skin pass; skin pass; 0.5 to 1.5% reduction in thickness 0.5 to 1.5% reduction in thickness To improve flatness. Sheets may To improve flatness. Sheets may not be sufficiently flat due to not be sufficiently flat due to various reasons such as roll gap various reasons such as roll gap and process parameters and process parameters Rolling Rolling 16 ME 4563 Fall ’05 Dr. S. Haran Flat Rolling Process Flat Rolling Process Continuous Continuous Casting or Ingots Casting or Ingots Blooms Blooms Slabs Slabs Billets Billets Preliminary Rolling Preliminary Rolling :: :: Initial breakdown of Ingot or cast Initial breakdown of Ingot or cast slab slab Hot Hot Rolling Rolling Rolling Rolling 9 17 ME 4563 Fall ’05 Dr. S. Haran Blooms Blooms Slabs Slabs Billets Billets Preliminary Rolling :: Preliminary Rolling :: About 6 About 6 ” ” square in cross square in cross section; various lengths section; various lengths Thinner rectangular cross Thinner rectangular cross section; various lengths (thinner section; various lengths (thinner version of a bloom) version of a bloom) Smaller square cross sections; Smaller square cross sections; various lengths various lengths Rolling Rolling Flat Rolling Process Flat Rolling Process 18 ME 4563 Fall ’05 Dr. S. Haran Continuous Continuous Casting or Ingots Casting or Ingots Blooms Blooms Slabs Slabs Billets Billets Preliminary Rolling Preliminary Rolling :: :: Hot Hot Rolling Rolling Continuous Flat Rolling Continuous Flat Rolling Process Process – – A Schematic A Schematic Casting 10 19 ME 4563 Fall ’05 Dr. S. Haran Slabs Slabs Hot Strip Hot Strip Mill Mill Directly to Directly to Rolling Rolling Pre Rolling Pre Rolling Plates Plates Tubes Tubes Pickling Pickling Cold Cold Rolling Rolling (acid bath) (acid bath) Flat Rolling Process Flat Rolling Process - - Products Products Rolling Rolling 20 ME 4563 Fall ’05 Dr. S. Haran Billets Billets Hot Rolled Hot Rolled Bars Bars Rods Rods Tube Tube Rounds Rounds Wire & wire Wire & wire products products Seamless Seamless Tubes Tubes Cold Cold - - drawn drawn Bars Bars Flat Rolling Process Flat Rolling Process - - Products Products Rolling Rolling [...]... increase is called SPREADING • Controlled with: • high width -to- thickness ratio width- to roll radius to strip thickness ratio • decreasing friction between rolls and material Spreading can be observed when dough is rolled with a rolling pin ME 4563 Fall ’05 Dr S Haran 67 Defects due to Rolling Successful Rolling depends upon various factors including material properties, process variables, and lubrication... Alligatoring – resulting from inhomogeneous material deformation during rolling and defects in the original cast ingot itself ME 4563 Fall ’05 Dr S Haran 69 Defects due to Rolling Schematic illustration of typical defects in flat rolling: (a) wavy edges; (b) zipper cracks in the center of the strip; (c) edge cracks; and (d) alligatoring alligatoring ME 4563 Fall ’05 Dr S Haran 70 35 Defects due to Rolling... screws, bolts No loss of material – smaller diameter rods to start with Greater strength due to cold working, as compared to a regular thread cutting process Ductility of material is crucial as well as good lubrication in the process Typically faster - at three times the cutting process ME 4563 Fall ’05 Dr S Haran 34 17 Thread Rolling Thread-rolling processes: Thread(a) and (c) reciprocating flat dies;... Piercing A hot-working process – used to make long thick hotwall seamless tubing When a round bar is subject to radial compression tensile stress develops in the center of the rod Can be demonstrated using a round eraser and rolling it on the table ! ME 4563 Fall ’05 Dr S Haran 41 Rolling D Rotary Tube Piercing When subject to cyclic compressive stresses a cavity begins to form in the center By means of... Productivity • Chatter (self excited vibration) can occur in rolling as well as other processes (extrusion, drawing, machining, etc.) • Related to the dynamics of the rolling action • In Rolling – predominantly occurs in Tandem mills • variation in thickness, poor surface finish, high levels of scrap • frequencies related to the resonance as well as other natural frequencies of the system • Controlled by... V-Section ME 4563 Fall ’05 Dr S Haran 27 Rolling B Ring Rolling Smaller diameter thick ring is expanded into a larger diameter thinner ring System consists of two rolls – one which performs the rolling and the other to support and guide With each rotation, the thickness is reduced as the rings come closer together ME 4563 Fall ’05 Dr S Haran 28 14 Ring Rolling (a) Schematic illustration of a ringringrolling... Defects: • inclusions and impurities in the material • scale, rust, dirt, roll marks, etc., caused due to prior treatment and working of the material • Remedy: precondition the material by cleaning it by various means ME 4563 Fall ’05 Dr S Haran 68 34 Defects due to Rolling • Structural Defects: distort or affect the integrity of the rolled product • Wavy Edges – Edges are thinner than the center caused... (via Hot rolling) • Provide backup rolls (four high) • Camber rolls to compensate roll deflection • Bend rolls back ME 4563 Fall ’05 Dr S Haran 59 Reducing the Roll Force • Lowering the friction • Friction is lower for cold rolling than for hot With effective lubricant: Cold Rolling - friction = 0.2 to 0.3 Hot Rolling - friction = 0.2 to 0.7 • Choose the right material for rolls • Modify the lubrication... rolled continuously through a number of stands to smaller gauges with each pass Each stand has its own set of rolls and controls A groups of stands is called a Train ME 4563 Fall ’05 Dr S Haran 54 27 Rolling Mills Roll Arrangements Tandem Mills Dimensions at different stages … ME 4563 Fall ’05 Dr S Haran 55 Rolling Mills - Rolls Strength and Resistance to wear Made of Cast iron, cast steel & forged... – Problems with Rolls Roll Flattening • The forces of rolling will flatten the rollers elastically – similar to tires on the road surface (Roll radius, Modulus of elasticity, roll forces) • This flattening causes an increase in the contact area • The increased contact area causes the forces to increase • Roll Flattening can be reduced by: • Using a roller material with a higher modulus of elasticity . State University Arkansas State University Introduction to Manufacturing Processes Introduction to Manufacturing Introduction to Manufacturing Processes Processes ME 4563 ME 4563 ME 4563 2 ME. – – smaller diameter rods to start with smaller diameter rods to start with   Greater strength due to cold working, as compared to a Greater strength due to cold working, as compared to a regular thread. skin pass; 0.5 to 1.5% reduction in thickness 0.5 to 1.5% reduction in thickness To improve flatness. Sheets may To improve flatness. Sheets may not be sufficiently flat due to not be sufficiently