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Rolling and Forging

Rolling and Forging. Manufacturing Processes. Outline. Temperature Rolling Flat Rolling Shape Rolling Operations Thread Rolling Seamless Tubing and Pipe Rolling Nonmetallic Materials Forging Open-Die Forging Closed-Die Forging Roll Forging Heading Rotary Swaging Forging Machines

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Rolling and Forging

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  1. Rolling and Forging Manufacturing Processes

  2. Outline • Temperature • Rolling • Flat Rolling • Shape Rolling Operations • Thread Rolling • Seamless Tubing and Pipe • Rolling Nonmetallic Materials • Forging • Open-Die Forging • Closed-Die Forging • Roll Forging • Heading • Rotary Swaging • Forging Machines • Dies • Economics

  3. Rolling and Forging Rolling The thickness of a slab of a slab or plate is reduced by cylindrical rolls which rotate to pull the material between them and compress it Forging A workpiece is compressed between opposing dies so that the material is forced into the die shape

  4. Temperature in Metal Forming Cold working (room temperature or slightly higher) Warm working (30% - 50% of the melting temperature) Hot working (50% - 75% of the melting temperature) Isothermal forming Tools are preheated to prevent surface cooling during forming

  5. Structure/Property Modification

  6. Cold Working Advantages • No heating required • Better surface finish • Better dimensional accuracy • Parts are interchangeable • Better strength, fatigue and wear properties • Directional properties can be imparted • Minimal contamination problems

  7. Cold Working Disadvantages • Higher forces required • More powerful equipment required • Less ductility is available • Surfaces must be clean • Intermediate anneals may be needed to restore ductility • Directional properties may be detrimental • May produce undesirable residual stresses

  8. Typical Rolled Products

  9. Typical Rolled Products

  10. Rolling Process

  11. Rolling Process

  12. Rolling Process

  13. Rolling Process

  14. Rolling Process

  15. Example of a Hot Rolling Line

  16. Rolling Defects

  17. Shape Rolling Uses a series of specially shaped rolls to form a beam with a specific cross section (such as an I-beam)

  18. Ring Rolling Uses rolls to form a thick, small-diameter ring into a thin, larger-diameter ring

  19. Ring Rolling

  20. Thread Rolling Uses moving dies with grooves to form threads on cylindrical parts

  21. Thread Rolling

  22. Material Property Changes

  23. Roll Piercing Uses compressive stresses on a cylindrical part to cause tensile forces at the interior, creating a hole to form a thick-walled tube

  24. Example of a Tube Rolling Mill

  25. Rolling Nonmetallic Materials • Paper • Plastic sheets • Rubber products • Reinforced fabric Calendering Passes material through a series of gaps between rolls to form a thin sheet

  26. Calendering

  27. Calendering Example of a calendered rubber sheet with two layers Courtesy Cooper Tire

  28. Calendering of Rubber

  29. Coated Products

  30. Reinforced Materials Coating on both sides of reinforcing material coating material spools comb reinforcing material coating material windup

  31. Reinforced Materials Example of a polyester-reinforced rubber sheet with fibers exposed Courtesy Cooper Tire

  32. Reinforced Materials Example of a steel-belted rubber sheet with the belt exposed Courtesy Cooper Tire

  33. Calender Control Systems

  34. Calendering Thickness Sensors Emitter X rays or beta radiation (electrons) some radiation is blocked, depending on thickness Detector

  35. Milling Squeezes material between rolls to mix or preheat it for further processes

  36. Forging Forging A deformation process in which the material is compressed between dies, using impact or gradual pressure to form the part

  37. Forging

  38. Example of a Forging Machine

  39. Example of a Forging Machine

  40. Working Temperature Hot Forging Material is above its recrystallization temperature Cold Forging Increased strength from strain hardening

  41. Forging Billet A piece of material with a square or circular cross section; usually produced by a deformation process such as rolling or extrusion

  42. Open Die Forging Compresses the work between flat or nearly flat dies

  43. Open Die Forging

  44. Open Die Forging

  45. Open Die Forging Advantages Simple, inexpensive dies; wide range of sizes; good strength Limitations Simple shapes only; difficult to hold close tolerances; machining necessary; low production rate; poor utilization of material; high skill required

  46. Closed Die Forging Also called impression-die forging; compresses the material into the shape of the die cavity

  47. Closed Die Forging

  48. Closed Die Forging Advantages Good utilization of material; better properties than open die forging; good dimensional accuracy; high production rate; good reproducibility Limitations High die cost for small quantities; machining often necessary

  49. Roll Forging Uses grooved rolls to reduce thickness and increase length of round or flat bars

  50. Roll Forging

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