Year: 1895

page_text: Date of Application, 14th Dec., 1895-Accepted, 18th Jan., 1896
We, DOUGLAS GEORGE BRIGHTON and EDWIN MARTYN VENNING, both of
102 Victoria Street, Westminster, London, S.W., Sanitary Engineers, do hereby
declare the nature of this invention and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement:-
This invention relates to an appliance for bending pipes (particularly lead pipes
for plumbing work) to any required curve or reverse curve without kinking and
with less inequality of thickness between the inside (or throat) and the outside of
the bend than when the bending is done in the ordinary way.
The object of this invention is to provide a plumber with an easily manipulated
appliance whereby lead pipes may be bent as required to suit the work in hand,
the same appliance being easily adapted to suit pipes of different thickness of
metal and likewise adaptable within certain limits to suit pipes of different sizes,
although a different apparatus would generally be used for drain pipes and for
those used for water-services.
The invention consists in the combination, with what may be termed a positively
rotated spherical roller mandrel, of a pair of bending rollers positively rotated
about their own axes and also capable of being moved in their own plane about a
neutral axis in order to produce in the pipe a bend of the desired radius and
amplitude.
The invention will be described with reference to the accompanying drawings,
'forming part of this Specification, wherein Figure is a longitudinal section
Figure 2 an end view and Figure 3 a plan of the pipe-bending apparatus. The
same letters of reference denote like parts in all the figures.
The spherical roller mandrel consists essentially of two (or more) hardened steel
rollers A of the form shewn, mounted to rotate each upon its own:axis, their 'axes
being parallel to and equidistant from a common axis about which the rollers are
rotated, the configuration of the rollers being such that their rotation will generate
the figure of a sphere or rather the frustum of a sphere, as indicated by the dotted
circle in Figure 2, whose diameter corresponds to the internal diameter of
the pipe.
The mandrel comprises end plates B, B1, carrying stud centres a, a, upon which
the rollers A rotate, the plates B, B1, being bolted together with an intervening
tubular distance piece b upon a spindle which also carries a supplementary
mandrel D for a purpose hereafter explained. The spindle C is coupled in any
suitable way to a feed screw spindle E through which rotary motion is transmitted
to the mandrel (the axis of revolution of the mandrel being represented by the
line 1-1) whilst the pipe feeder F, threaded to work on the screw, is caused to
advance towards the mandrel to force the pipe along as the formation of the bend
proceeds, the pipe feeder F fitting in the end of the pipe (sbewn by dotted lines
at P, Figure 1) and supporting it concentrically about the mandrel spindle.
G, G, are the bending rollers having their peripheries concaved to correspond to
the external circumference of the pipe so that the two when juxtaposed, as shewn
in Figure 2, enclose a circle corresponding to the external circumference of the
5 pipe. These bending rollers are mounted to revoive between the top and bottom

page_text: plates I, of a supporting frame and their spindles are guided in pairs of
segmental circular slots J, J, in the top and bottom plates I, I, equidistant from
and concentric with the neutral axis represented by the line 2-2, Figure 2, this
axis 2-2 intersecting at right-angles the axis 1-1 of revolution of the roller
mandrel at the centre of the spherical figure generated by the revolution of the
rollers about the axis 1—1. The bending rollers G, G, are moved about the
neutral axis 2-2 by the operator, for which purpose the spindles g, g, are pro-
longed and provided with handles H, H, and are likewise coupled together by
yokes K K which are pivoted upon fixed studs concentric with the axis of
motion 2-2.
Rotary motion is imparted to the bending rollers about their own axes (in the
direction of the arrows, Figure 3) whatever the angular position of the said rollers
about the common axis 2-2, by gear wheels L, L, fast with the rollers G, G, and
in gear with the same wheel M concentric with the axis 2-2 and driven by bevel
gear N, N', from a shaft O, the shaft O and the mandrel or feed screw shaft E
being both geared by pinions Q, Q, with the same wheel R on the fly-wheel S so
that the mandrel and bending rollers are revolved at properly proportioned speeds
to produce the desired effects. The rollers G, G, serve both as guiding and
bending rollers and also to equalize the thickness of the metal, as will be apparent
from the description of the operation of the apparatus.
At starting, the pipe P is fed between the rollers G when the latter are in the
initial position shewn by dotted lines in Figure 3, that is to say the common
plane 3-3 being perpendicular to the axis of the mandrel shaft, and whilst in this
position the pipe is fed through between the rollers G until the point is reached
where the formation of the bend is to be commenced, whereupon the rollers G
whilst rotating, as indicated by the arrows, are swung gradually about the centre 2
in a right or left handed direction, as the case may be, or first in the one and then
in the other direction, to produce an S-bend, the extent and rapidity of this
motion determining the radius of the bend, the minimum radius being equal to that
of the roller G.
Figure 3 shews, in dot and dash lines, a bend in process of formation, that is to
say the part P', of the pipe has passed between the rollers and has been bent, as
shewn, by gradually bringing the bending rollers G, G to the position shewn in
dot and dash lines, the angular position of their common plane being indicated by
the line 3, 3, the line of contact of the mandrel being always a circle in the
common plane of the rollers G.
Assuming that one-half of the intended bend has been formed, as shewn in
Figure 3, the completion of the other half will be effected by gradually bringing
the rollers G back to their normal position whilst continuing to drive the mandrel
and bending rollers and to feed the pipe as before.
In consequence of the rubbing contact of the rollers G with the exterior of the
pipe, caused by their revolution in the directions indicated, in combination with
the rolling contact of the mandrel rollers A, a sort of spinning effect is produced
upon the metal whereby part of the excess of metal due to the thickening under
compression of the metal at the throat or inner radius of the bend, is gradually
worked round towards the outer radius of the bend so as to assist to supply the
deficiency caused by the tendency to draw out the metal at the point where it is
under tension, thus to a certain extent equalizing the thickness of the metal at the
throat and outer side of the bend.
The function of the part D of the mandrel is to prevent the formation of sharp
kinks at the throat of the bend when the pipe is being bent to the minimum radius,
as in the example illustrated.
It will be obvious that the mandrel, instead of being formed by rollers each
revolving about its own, and about a common, axis, might be formed by a solid
frustum of a sphere which might or might not rotate, but such a mandrel would be
less effective than the one described.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is:-
1. The herein described pipe bending apparatus constructed and operating
substantially as specified.
2. In a pipe bending apparatus, the combination of a revolving roller mandrel, such
as described, and of a pair of positively rotated bending rollers adapted to embrace
the pipe and conjointly movable in their own plane about a neutral axis coincident
with the centre of the mandrel, as specified.
3. In a pipe bending apparatus, the combination, of a revolving roller mandrel,
such as described, a screw feed device for the pipe, and a pair of positively driven
bending rollers adapted to embrace the pipe and conjointly movable about a neutral
axis, as described.
4. In a pipe bending apparatus, the combination, with a spherical mandrel, of a
pair of positively driven bending rollers adapted to embrace the pipe and conjointly
movable about a neutral axis, as specified.
Dated this 14th day of December 1895
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.