Discussion: “Analysis of Wire Drawing and Extrusion Through Conical Dies of Large Cone Angle” (Avitzur, Betzalel, 1964, ASME J. Eng. Ind., 86, pp. 305–314)

1964 ◽  
Vol 86 (4) ◽  
pp. 315-315
Author(s):  
H. C. Sortais
Keyword(s):  
Cone Angle ◽  
Wire Drawing ◽  
Large Cone Angle

Analysis of Wire Drawing and Extrusion Through Conical Dies of Large Cone Angle

1964 ◽  
Vol 86 (4) ◽  
pp. 305-314 ◽  
Author(s):  
Betzalel Avitzur
Keyword(s):  
Cone Angle ◽  
Wire Drawing ◽  
Wire Radius ◽  
Yield Limit ◽  
Process Variables ◽  
Absolute Value ◽  
Direct Extension ◽  
Yield Value ◽  
Half Angle ◽  
Large Cone Angle

This work is a direct extension of reference [3]. There the problem was treated with the assumption that the cone angle was small. Here this limitation exists no more. The operations of wire drawing and extrusion through conical dies are treated on the assumption that “Mises” material is formed. An upper-bound solution is obtained for the drawing stress in wire drawing and for the pushing stress in extrusion. The effect of each of the process variables on these forces is presented graphically. The process variables are: the cone half-angle (α), initial (Ri) and final (Rf) wire radius, material yield limit (σ0) under uniaxial load, back pull (σxb) and front pull (σxf), coefficient of friction (μ) or shear factor (m), die land (L), exit velocity (vf), and entrance velocity (vi). On the assumption that the maximum front tension cannot exceed the yield limit of the material under uniaxial tension, a solution is obtained for maximum possible reduction in wire drawing. An analogous assumption, i.e., that the absolute value of the pushing stress also cannot exceed the yield value, gives a criterion for maximum possible reduction in extrusion.

scholarly journals Evaluation of Algebraic Iterative Image Reconstruction Methods for Tetrahedron Beam Computed Tomography Systems

2013 ◽  
Vol 2013 ◽  
pp. 1-14
Author(s):  
Joshua Kim ◽  
Huaiqun Guan ◽  
David Gersten ◽  
Tiezhi Zhang
Keyword(s):  
Computed Tomography ◽  
Iterative Reconstruction ◽  
Cone Angle ◽  
Iterative Algorithms ◽  
Projection Data ◽  
Reconstruction Algorithms ◽  
Reconstruction Methods ◽  
Large Cone Angle ◽  
Using Data ◽  
Dual Detector

Tetrahedron beam computed tomography (TBCT) performs volumetric imaging using a stack of fan beams generated by a multiple pixel X-ray source. While the TBCT system was designed to overcome the scatter and detector issues faced by cone beam computed tomography (CBCT), it still suffers the same large cone angle artifacts as CBCT due to the use of approximate reconstruction algorithms. It has been shown that iterative reconstruction algorithms are better able to model irregular system geometries and that algebraic iterative algorithms in particular have been able to reduce cone artifacts appearing at large cone angles. In this paper, the SART algorithm is modified for the use with the different TBCT geometries and is tested using both simulated projection data and data acquired using the TBCT benchtop system. The modified SART reconstruction algorithms were able to mitigate the effects of using data generated at large cone angles and were also able to reconstruct CT images without the introduction of artifacts due to either the longitudinal or transverse truncation in the data sets. Algebraic iterative reconstruction can be especially useful for dual-source dual-detector TBCT, wherein the cone angle is the largest in the center of the field of view.

scholarly journals FABRICATION OF LARGE CONE ANGLE OPTICAL FIBER PROBE BY DYNAMIC CHEMICAL ETCHING METHOD

2001 ◽  
Vol 50 (12) ◽  
pp. 2382
Author(s):  
SUN JIA-LIN ◽  
TIAN GUANG-YAN ◽  
LI QIN ◽  
ZHAO JUN ◽  
GUO JI-HUA ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Chemical Etching ◽  
Cone Angle ◽  
Fiber Probe ◽  
Optical Fiber Probe ◽  
Etching Method ◽  
Large Cone Angle

Helical CT Reconstruction with Large Cone Angle

2006 ◽  
Author(s):  
Alexander A. Zamyatin ◽  
Alexander Katsevich ◽  
Michael D. Silver ◽  
Satoru Nakanishi
Keyword(s):  
Cone Angle ◽  
Helical Ct ◽  
Ct Reconstruction ◽  
Large Cone Angle

Analysis of Central Bursting Defects in Extrusion and Wire Drawing

1968 ◽  
Vol 90 (1) ◽  
pp. 79-90 ◽  
Author(s):  
B. Avitzur
Keyword(s):  
Strain Rate ◽  
Fracture Criterion ◽  
Yield Criterion ◽  
Cone Angle ◽  
Flow Characteristics ◽  
Wire Drawing ◽  
Ductile Material ◽  
Stress Deviator ◽  
Major Conclusion ◽  
Metal Properties

The central burst defect, also called chevroning, in the extruded or drawn product is analyzed. A criterion for the unique conditions that promote this defect has been derived. Measures to prevent the occurrence of central burst are indicated. A major conclusion of the study is that, for a range of combinations of cone angle, reduction, and friction, central bursting is expected in any metal that can be called “Mises’ material.”1 Under such a combination (reduction, cone angle, and friction), even the most ductile material can burst centrally. The flow characteristics, described by Mises’ stress deviator-strain rate relations associated with Mises’ yield criterion, are the only metal properties needed to predict central bursting. No additional fracture criterion is associated with this failure.

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