PROCEDE DE TREFILAGE (FILS, TIGES, TUYAUX, ETC.)

DEVICE FOR DRAWING WIRE, ROD, PIPE OR THE LIKE

Abrégé anglais

ABSTRACT
A device is disclosed for drawing wire, rod, pipe, or the like
under hydrodynamic pressure. The device includes a lubricating duct, pre-
ceding a drawing duct, in which the lubricant pressure builds up. The
lubricating duct tapers conically towards the drawing duct. The nozzle-
shaped drawing duct and the lubricating duct are each arranged in a separate
element, the walls of the lubricating duct being at an angle of between 2
and 10° to the axis thereof.

Revendications

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A device for drawing wire, rod, pipe, or the like under hydro-
dynamic pressure, the said device comprising a lubricating duct open at
one end and preceding a drawing duct, in which the lubricant pressure
builds up, the said lubricating duct tapering conically towards the said
drawing duct, characterized in that the nozzle-shaped drawing duct and
the lubricating duct are each arranged in a separate element, the walls
of the said lubricating duct being at an angle of between 2 and 10° to
the axis thereof and the lubricating duct merging with the drawing duct
without an intermediate gap and without substantial widening thereof.

Description

93
In wire-drawing technology, increasing use has been made in recent
years of pressure lubrication. This is based upon a variety of principles,
the best-known of which are:
a) producing the pressure by means of external pumps;
b) producing the pressure by means of a lubricating duct in which
the pressure builds up as a function of the length and diameter of the duct
in relation to the diameter of the wire, rod or pipe to be drawn;
c) suitably shaped double or multiple drawing dies.
When drawing is carried out using hydrodynamic lubrication, it is
known to use a conical lubricating duct, to which end the said duct is
arranged in the drawing-tool and precedes the deformation zone in the draw-
ing die. In this case, the lubricating duct and deformation zone have
conical walls which merge smoothly into each other and which are at the
same angle to the axis of the duct. One-piece drawing tools of this kind
are described in United States Patents 2,343,118 and 3,763,680.
It is the purpose of the present invention to improve these known
drawing devices. The improvement according to the invention makes it
possible to achieve increased cross-sectional reduction and/or increased
drawing velocity, especially in the case of materials having poor drawing
properties.
According to the invention there is provided a device for drawing
wire, rod, pipe, or the like under hydrodynamic pressure, the said device
comprising a lubricating duct open at one end and preceding a drawing duct,
in which the lubricant pressure builds up, the said lubricating duct tapering
conically towards the said drawing duct, characterized in that the nozzle-
shaped drawing duct and the lubricating duct are each arranged in a separate
element, the walls of the said lubricating duct being at an angle of between
2 and 10 to the axis thereof and the lubricating duct merging with the
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drawing duct without an intermediate gap and without substantial widening
thereof.
: Accommodating the lubricating duct and the drawing die or duct in
separate elements makes it possi~le for the two ducts to be of different
designs adapted to their respective functions. For instance, the diameter,
. conicity and length of the drawing duct may be fully adapted to the lubricant
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to be used and to the desired lubricant pressure at the end of the lubricat-
ing duct, which is a function of the material to be drawn and the drawing
velocity.
Since the drawing duct is arranged in its own element, it may be
shaped to produce optimal deformation. The conical lubricating ducts have
hitherto extended into the drawing ducts at the same conicity, which has
made it impossible for the drawing duct to be shaped to produce optimal
deformation of the relevant material. The high lubricant pressure attain-
able in the drawing duct as a result of the conical shape thereof made it
seem undesirable to allow two elements to abut in this area, since it was
feared that sealing problems might result.
The hydrodynamic pressure does not build up linearly in the lubri-
cating duct, but may lead to a maximum in that duct and therefore before the
drawing duct. With proper choice of duct conicity and length, lubricant
viscosity and drawing velocity, the pressures achieved may be so high that
the material to be drawn is deeormed before it enters the drawing die. This
means that the drawing tool itself performs little deformation. Thus, if
full use is made of the deformation in the drawing die, it is possible to
obtain increased cross-sectional reduction, to wit by the amount which
already occurs in the lubricating duct. Deformation in the lubricating duct
is not at all times uniform, and the drawing die therefore also performs the
function of calibrating the material being drawn.
Depending upon the drawing conditions, therefore, it is possible
to obtain increased cross-sectional reduction per drawing tool, increased
- drawing velocity, or significantly longer drawing-tool life, as compared
with known devices of the type mentioned at the beginning hereof.
With suitable choice of the angle of inclination, the inlet and
outlet diameter of the duct, the length thereof, and the viscosity of the

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lubricant, pressures of up to 20,000 bars may be achieved. Most materials
in practice deform under a maximal pressure of this order.
An embodiment of the device according to the invention is illus-
trated in cross section - in part diagrammatically - in the drawing attached
hereto. In the said drawing, drawing die 1 is located in bore 2 of a tool-
holder 3. The latter has an internal thread into which a nipple 4 is
` screwed which presses drawing die 1 against a shoulder 5 in the tool-holder.
Nipple 4 has a conical duct 6 tapering towards drawing die 1.
; Even when most of the deformation of the material being drawn takes
place before the drawing die, a considerable amount of heat is developed
with large cross-sectional reductions and/or high drawing velocities. For
this reason it may be necessary to cool the drawing die. To this end tool-
holder 3 has an annular duct 7 covered by an annular disc 8 screwed to the
tool-holder, annular seals 9 being provided for sealing. The cooling agent
is supplied and carried away through lines 10 and 11.
The angle between the wall and the axis of the duct depends upon
the viscosity of the lubricant used and thus upon the material being drawn.
For the purpose of drawing copper, or copper-alloy, wire, an angle of
between 4 and 5 has been found particularly satisfactory.