Theoretical considerations of drawing a round tube through a conical die and a polygonal plug
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Date
1988Author
Nga'ng'a, Stephen P
Type
ThesisLanguage
enMetadata
Show full item recordAbstract
Theoretical and practical investigations in the
drawing of the following sections directly from an entirely
round stock have been reported: polygonal bars, polygonal
tubes with the outside and bore surfaces geometrically similar,
and tubes with the outside polygonal surface and circular
bore, The derived theoretical solutions enabled the
industrialists to design tools to manufacture tubing or bar
stocks directly from round with minimum amount of energy being
dissipated in the drawing process; the resulting optimal
tools also produced relatively superior polygonal stocks.
This thesis extends the theoretical analysis to the manufacture
of a polygonal tube by drawing an entirely round stock through
a deformation passage formed by a conical die and a polygonal
plug.Using a prescribed shape of the plug and a regular
conical die, two solutions of the drawing loads were derived:
the 10V\erbound and the upper bound. The laver bound load
considered the homogenecusdefonnation and the friction work
and ~,hus ignored the redundant work. The upper bound value
• of the drawing force was derived fran the minimumenergy
associated with the velocity pattern obtained by conformal
mapping. Unlike the axisymnetric drawing on a mandrel, the plug profile was carplex; an equivalent plug semi-angle was
therefore used to enable canparisons to be madebetween
deformation passages formedby a knovn die profile and the
polygonal plugs and also to facilit~te the optirr:rrzationof
the process parameters.
The graphs of the drawing forces drawn against the
various parameterrs such as the die angle, 'the equivalent plug
angle, the reduction of area as well as friction shewed trends
s~lar to those tried practically and reported in the
literature of polygonal tube drawing directly frcm round stock