1 / 17

Chapter 16 Bulk Forming Processes (Part 3) EIN 3390 Manufacturing Processes Spring 2011

Chapter 16 Bulk Forming Processes (Part 3) EIN 3390 Manufacturing Processes Spring 2011. Swaging. Also known as rotary swaging and radial forging Uses external hammering to reduce the diameter or produce tapers or points on round bars of tubes. Swaging.

zurina
Télécharger la présentation

Chapter 16 Bulk Forming Processes (Part 3) EIN 3390 Manufacturing Processes Spring 2011

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 16Bulk Forming Processes(Part 3)EIN 3390 Manufacturing ProcessesSpring 2011

  2. Swaging • Also known as rotary swaging and radial forging • Uses external hammering to reduce the diameter or produce tapers or points on round bars of tubes

  3. Swaging Figure 16-21 (Below) Tube being reduced in a rotary swaging machine. (Courtesy of the Timkin Company, Canton, OH.) Figure 16-23 (Below) A variety of swaged parts, some with internal details. (Courtesy of Cincinnati Milacron, Inc. Cincinnati, OH.) Figure 16-22 (Right) Basic components and motions of a rotary swaging machine. (Note: The cover plate has been removed to reveal the interior workings.) (Courtesy of the Timkin Company, Canton, OH.)

  4. Swaging

  5. Estimation of Drawing Force required: F = Yavg Af ln (A0/Af) Yavg = average true stress of material in the die gap; A0 and Af are the original and final cross-sectional areas of the work. • Assumptions: no friction. Drawing Force

  6. If considering the friction, the actual force is larger than provided by follows. • F = YavgAfln (A0/Af) • In addition to the ratio A0/Af, other variables that influence draw force are die angle, and coefficient of friction at the work-die interface. • A number of methods have been proposed for predicting draw force based on values of these parameters. Drawing Force (-continued)

  7. Drawing of Bar, Rod, or Wire

  8. Schey [1] suggested: F = YavgAf (1 + m/tana) fln (A0/Af) where F – drawing force, lb; m– die-work coefficient of friction; a – die angle (half-angle), degree; f – a factor that accounts for inhomogeneous deformation, which is determined as follows for a round cross section: f = 0.88 + D/Lc Where D – average diameter of work during drawing, in; and Lc = contact length of the work with the draw die, in. D = 0.5 (D0 + Df), and Lc = (D0 – Df)/(2sina) The power required in a drawing operation is the draw force multiplied by exit velocity of the work. [1] Schey, j.A., Introduction to manufacturing Processes, 2nd ed.., McGraw-Hill Book Co., New York, 1987, Chapter 4. Drawing Force (-continued)

  9. The average flow stress (also called the mean flow stress) is the average value of stress over the stress-strain curve from the beginning of strain to the final (maximum) value that occurs during deformation. Stress-strain curve indication location of average flow stress yf in relation to yield strength Y and final flow stress Yf. Flow stress Yavg

  10. The average flow stress is determined by integrating the flow curve equation between zero and the final strain value defining the range of interest. Yavg = Ken/(1 + n) where Yavg – average flow stress, ib/in2; K – the strength coefficient, lb/in2, e - maximum strain value during the deformation process, e= ln (A0/Af); and n – the strain hardening exponent. Finally, we have F = YavgAfln (A0/Af) = [ken/(1 + n)] Afln (A0/Af) Flow stress Yavg(-continued)

  11. force (0.00503) F Example to Calculate Drawing Force 70

  12. Work has to be done to overcome friction. • Force increases with increasing friction. • Cannot increase force too much, or material will reach yield stress. • Maximum reduction in cross-sectional area per pass = 63%. Maximum Reduction per Pass for Drawing

  13. F/Af = Maximum Reduction per Pass for Drawing (-continued)

  14. t0W0v0 = tfw0vf vf = (t0 v0)/tf vf > vr > v0

  15. Rolling Mill Configurations Figure 16-4 The effect of roll diameter on length of contact for a given reduction. • Smaller diameter rolls produce less length of contact for a given reduction and require less force to produce a given change in shape • Smaller cross section provides a reduced stiffness • Rolls may be prone to flex elastically because they are only supported on the ends

  16. Rolling Mill Process Assume: Starting volume of rolling work is equal to the final volume of the rolling work: (Volume)0 = (Volume)f t0 W L0 = tf W Lf (t0 W L0)T = (tf W Lf)T (t0 W v0) = (tf W vf) (t0 v0) = (tf vf) tx = tf + (r – y) = tf + r – SQRT(r2 – x2) if x = 0, tx = tf if x = x0, tx = t0, where x0 = SQRT(r2 – y02), and y0 = r + tf – t0 x x0 xf X r y0 y v0 t0 tx vf tf Y

  17. vx = (t0 v0)/tx = (t0 v0)/[tf + r – SQRT(r2 – x2)] Example: r = 10 in, v0 = 1,000 in/min, t0 - 1 in, and tf - 0.5 in. V x Rolling Mill Process X

More Related