{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

# B piping sink hole at the end of billet under direct

This preview shows page 1. Sign up to view the full content.

This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: let under direct extrusion. c) Surface cracking: High part temperature due to low extrusion speed and high strain rates. Process Variables in Direct Extrusion Figure 15.4 Process variables in direct extrusion. The die angle, reduction in cross-section, extrusion speed, billet temperature, and lubrication all affect the extrusion pressure. Extrusion Analysis Extrusion ratio, rx = Ao Af Assuming all sections are circular, ideal deformation, no friction, no redundant work: = ln rx p = Y f ln rx Ram pressure p = Y f (a + b ln rx ) Taking into account friction, where a =0.8 and b =1.2 to 1.5. Extrusion Analysis For direct extrusion, additional pressure, pf, required by the extruder to overcome the wall friction is related as p f Do2 follows: 4 = pcDo L For the worst case that the friction shear stress at the wall equals to the shear yield strength of the work pc = Ys metal: p f = Yf 2L Do The additional pressure: The total ram pressure: The power required: 2L p = Yf x + Do P = Fv Extrusion Dies For the case of non-circular extruded section, a shape factor has to be introduced: C K x = 0.98 + 0.02 x C c 2.25 where Kx = shape factor Cx = perimeter of...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online