Hollow-tube drawing or tube sinking theory is based on the concept of continuous distribution of dislocations. Material composition, parameter influence, and die-angle are determining factors in derivation of the theoretical model

Flinn, J. E.

Mura, T.

English

NASA Technical Reports Server

September 1969	 1 Brief 69-10428 
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AEC-NASA TECH BRIEF 
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the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Wall-Thickness Changes Predicted in

Hollow-Drawn Tubing 
A theoretical analysis for prediction of changes in 
wall thickness in hollow-drawn tubing is reported 
(1). Material composition, parameter influence, and 
die-angle are incorporated as determining factors in 
derivation of the theoretical model. 
This theory for hollow-tube drawing or tube sinking 
is based on the concept of a continuous distribution 
of dislocations. More-important facets of this mode 
of tube-drawing are the dimensional changes, pri-
marily in wall thickness, that occur during reduction, 
and the parametric effects on these changes. Clas-
sical interpretation has been only moderately suc-
cessful in prediction of the hollow-drawing behavior 
of "thin-wall" tubes; even then, there are parametric 
discrepancies between theory and experiment. 
Three earlier experimental studies provide the bulk 
of the information available on the dimensional be-
havior of hollow-drawn tubes. From these studies two 
theoretical analyses developed in endeavors to ex-
plain some of the experimental observations. Partic-
ular attention was given to the increase in wall thick-
ness observed during the early stages of the reduction 
sequence, followed by thinning of the walls at the 
heavier reduëtions. The effect of 
o 
on wall-thickness 
behavior, where is the ratio of the initial wall 
thickness to the initial outer radius, was included. 
Regarding the influence of.-yo,two facets cannot 
be explained by the analyses. Firstly the analyses 
result in a differential-slope solution that predicts 
that the wall thickness must increase during the 
initial stages of deformation, or the reduction se-
quence. While the analyses were based primarily on 
"thin-wall" considerations, experimental evidence 
from "thick-wall" tubes of several materials has
shown various degrees of thinning of the wall at all 
stages of reduction. .A more general theory would 
have to predict both thickening and thinning behavior 
of the wall. Secondly the theory predicts for an infi-
nitely thin-wall tube a thickening before thinning 
behavior over a reduction range of approximately 0.5. 
However, experimental observations of thin-wall tubes 
suggest that thickening should continue until reduc-
tions reach almost 100 percent. 
Both theories consider the parametric influence of 
die-angle and work-hardening on the changes in wall 
thickness. Experimental evidence shows that an in-
crease in the die-angle produces a greater wall-
thinning tendency, but a greater wall-thickening 
tendency for a material having a greater work-
hardening capacity. 
The theoretical analysis presented (I) incorporates 
the parametric influences on the wall-thickness 
changes for the tube over the entire tubing range 
0 y0 I. There are several aspects of the hollow-
drawing process that make the application of con-
tinuum-dislocation theory seem very promising. One 
advantage is that the dislocation-density distribution 
is a state quantity; this property is independent of 
the path used for a final reduction. 
Reference: 
1. T. Mura and J. E. Flinn, "A continuum dislocation 
theory model for predicting the wall thickness 
changes of hollow-drawn tubing" (Argonne 
National Laboratory, August 1967). 
Notes: 
I. This information may interest metallurgical re-
searchers or manufacturers of metal tubing. 
(continued overleaf) 
This document was prepared under the sponsorship of the Atomic 
Energy Commission and/or the National Aeronautics and Space 
Administration. Neither the United States Government nor any per-
son acting on behalf of the United States Government assumes any
liability resulting from the use of the information contained in this 
document, or warrants that the use of any information, apparatus, 
method, or process disclosed in this document may not infringe pri-
vately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19690000419 2020-03-16T18:02:02+00:00Z
2. Inquiries concerning this innovation may be di-
rected to:
Office of Industrial Cooperation 
Argonne National Laboratory 
9700 South Cass Avenue 
Argonne, Illinois 60439 
Reference: B69-10428
Source: T.Muraof
Northwestern University

under contract to

National Laboratory
(2) J. E. Flinn
Metallurgy Division
(ARG- 10425)
Patent status: 
Inquiries concerning rights for commercial use of 
this innovation may be made to: 
Mr. George H. Lee, Chief 
Chicago Patent Group 
U.S. Atomic Energy Commission 
Chicago Operations Office 
9800 South Cass Avenue 
Argonne, Illinois 60439 
Brief 69-10428	 Category 02,05


Wall-thickness changes predicted in hollow-drawn tubing

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