Page 454 - 04. Subyek Engineering Materials - Manufacturing, Engineering and Technology SI 6th Edition - Serope Kalpakjian, Stephen Schmid (2009)

434 Chapter 16 Sheet-Metal Forming Processes and Equipment

Smith, D., Fundamentals of Pressworking, Society of Tool and Manufacturing Engineers Handbook, 4th ed., Vol. 2:
Manufacturing Engineers, 1994. Forming. Society of Manufacturing Engineers, 1984.
Suchy, I., Handbook of Die Design, 2nd ed., McGraw-Hill, Tschaetch, H., Metal Forming Practice: Processes, Machines,
2005. Tools, Springer, 2007.
Szumera, J., Metal Stamping Process, Industrial Press, 2003.

REVIEW QUESTIONS

l6.I. How does sheet-metal forming differ from rolling, l6.9. Why do tubes buckle when bent? What is the effect of
forging, and extrusion? the tube thickness-to-diameter ratio?
|6.2. What causes burrs? How can they be reduced or l6.l0. Define normal anisotropy, and explain why it is im-
eliminated? portant in determining the deep drawability of a material.
|6.3. Explain the difference between punching and blanking. l6.l I. Describe earing and why it occurs.
I6.4. Describe the difference between compound, progres- l6.l2. What are the advantages of rubber forming? Which
sive, and transfer dies. processes does it compete with?
l6.5. Describe the characteristics of sheet metals that are l6.l3. Explain the difference between deep drawing and
important in sheet-forming operations. Explain why they are redrawing.
important. l6.I4. How is roll forming fundamentally different from
|6.6. Describe the features of forming-limit diagrams (FLDS). rolling?
l6.7. List the properties of materials that influence spring- l6.|5. What is nesting? What is its significance?
back. Explain why and how they do so. l6.l 6. What is microforming?
l6.8. Give one specific application for each of the common l6.l 7. Explain the advantages of superplastic forming.
bending operations described in this chapter.

QUALITATIVE PROBLEMS

l6.I8. Explain the differences that you have observed l6.26. ls it possible to have ironing take place in an ordi-
between products made of sheet metals and those made by nary deep-drawing operation? What is the most important
casting and forging. factor?
l6.l 9. Identify the material and process variables that influ- l6.27. Note the roughness of the periphery of the flanged
ence the punch force in shearing, and explain how each of hole in Fig. 16.25c, and comment on its possible effects when
them affects this force. the part is used in a product.
l6.20. Explain why springback in bending depends on yield l6.28. What recommendations would you make in order to
stress, elastic modulus, sheet thickness, and bend radius. eliminate the cracking of the bent piece shown in Fig. 16.17c?
|6.2|. Explain why cupping tests may not predict well the Explain your reasons.
formability of sheet metals in actual forming processes. l6.29. Give several specific examples from this chapter in
which friction is desirable and several in which it is not
l6.22. Identify the factors that influence the deep-drawing
desirable.
force, F, in Fig. 16.31b, and explain why they do so.
l6.23. Why are the beads in Fig. 16.35b placed in those l6.30. As you can see, some of the operations described in
particular locations? this chapter produce considerable scrap. Describe your
thoughts regarding the reuse, recycling, or disposal of this
l6.24. A general rule for dimensional relationships for scrap. Consider its size, its shape, and its contamination by
successful drawing without a blankholder is given by metalworking fluids during processing.
Eq. (16.14). Explain what would happen if this limit were
l6.3 I. Through changes in clamping or die design, it is pos-
exceeded.
sible for a sheet metal to undergo a negative minor strain.
l6.25. Section 16.2.1 stated that the punch stripping force Explain how this effect can be advantageous.
is difficult to estimate because of the many factors involved.
Make a list of these factors with brief explanations about l6.32. How would you produce the part shown in Fig. 16.4Ob
why they would affect the stripping force. other than by tube hydroforming?