IMPROVE- MENTS IN MANDRELS FOR BENDING METAL PIPE
Year: 1875

page_text: LETTERS PATENT to John Richards, of Adelphi, Strand, in the County
of Middlesex, Mechanical Engineer, for the Invention of "IMPROVE-
MENTS IN MANDRELS FOR BENDING METAL PIPE." A communication
from abroad by Morris Longstreth Orum, of the City and County
of Philadelphia, State of Pennsylvania, in the United States of
America.
PROVISIONAL SPECIFICATION left by the said John Richards at the
Office of the Commissioners of Patents, with his Petition, on the
16th August 1875.
I, JOHN RICHARDS, of Adelphi, Strand, in the County of Middlesex,
Mechanical Engineer, do hereby declare the nature of the said Inven-
tion for "IMPROVEMENTS IN MANDRELS FOR BENDING METAL PIPE," (a com-
munication to me from abroad by Morris Longstreth Orum, of the City
and County of Philadelphia, State of Pennsylvania, in the United States
of America) to be as follows

page_text: curvature without flattening or perceptible marking at the bend, as well
as, so far as practicable, to guard against breakage of the pipe in the
operation, to which ends these improvements consist.
First. In a flexible metallic mandrel for bending round or elliptical
metal pipes or tubes, said mandrel being a spiral coil of wire, the section
of which is such as to present a flat or flattened surface on the exterior
of the spiral, and which is of sufficient pliability to be readily bent into
any curve desired, while at the same time possessing sufficient strength
to act as an internal support to the pipe and prevent its deformation by
the action of the bending implements.
Second. In a flexible mandrel for bending metal pipes or tubes of
square or polygonal section (such as are used for instance in the manu-
facture of gas fixtures), composed of a spiral coil of wire and two
flexible plates interposed between said coil and the inner surfaces of the
pipe or tube to be bent.
In the process of bending metal pipes or tubes as heretofore practised,
it has been difficult to form a bend of regular circular section by reason
of the tendency of the pipe to flatten at the bend in the operation, and
various expedients have been resorted to for the purpose of obviating
this difficulty.
A process which has been extensively practised consists in filling the
pipe with rosin or analogous material, and removing the same by melting
after the pipe has been bent. This process is for obvious reasons incon-
venient, and further, while involving the expenditure of considerable
time, does not in all cases prevent the flattening of the pipe before
mentioned.
In order to bend a round or elliptical pipe by this Invention, I provide
a flexible mandrel, which is formed of a spiral coil of stout wire, the
diameter of the coil being such that the mandrel may fit easily within
the pipe.
The wire used to form the mandrel should be either of a square, rect-
angular, or triangular section, or more or less flattened upon the exterior
surface of the spiral, so as to afford as much bearing surface as possible
to the pipe, and the spiral should be coiled as closely as practicable for
the same reason. I then introduce the mandrel into the pipe and bend
the latter to the curvature required by the ordinary implements used

page_text: for the purpose, and afterwards withdraw the mandrel from the pipe,
which it has been found in practice is not perceptibly marked or injured
in the operation, and the mandrel is ready for use with another pipe.
The mandrel can be readily withdrawn after bending the pipe by
attaching one of its ends to a lathe spindle, and revolving it in such
direction as to reduce its diameter by screwing up its coil.
According to a modification, a compound mandrel composed of an
outer and an inner coil of wire is made use of, the two coils being right
and left handed screws respectively. When it is desired to withdraw a
mandrel of this form from a pipe the two coils can be turned in reverse
directions so as to speedily reduce its diameter.
In some cases a mandrel may be used having a coil of wire rope
within it and fastened to one of its ends, the purpose of which is to
enable one end to be held fast while the other is being screwed up to
reduce its diameter.
For bending pipes of square or polygonal section I provide a flexible
mandrel, which is formed of a spiral coil of stout wire of such diameter
as to fit easily between two thin plates of flexible metal interposed
between the coil and the inner surface of the pipe upon the two sides of
the latter, which are at right angles to the radius of the curve to be
formed.
Round, square, or flattened wire may be used to form the mandrel, and
the thickness of the said thin plates should be sufficient to prevent them
from being indented or fractured in the bending operation, without
rendering them so stiff as to oppose an undue resistance thereto. Their
width should be somewhat less than that of the pipe, so that they may
be readily inserted and withdrawn.
In the application of this device the mandrel and plates are intro-
duced into the pipe before commencing to bend it; it is then bent to
the curvature required by the ordinary implements, and the mandrel and
plates then withdrawn. The flexible mandrel acts as a support to the
sides of the pipe in the operation, and prevents them from being indented
or injured, and the office of the thin plates, the longitudinal sections of
which are curved in the operation correspondingly with the mandrel, is
to afford a bearing for the pipe thereon for the entire width of the pipe,
instead of at single points, as would be the case if the plates were not
employed.

page_text: It has been found in practice that by the use of these devices the
bend either round or square metal pipes with
that by their introduction time, labour, and
workman is enabled to
ease and celerity, and
material are economized.
.
SPECIFICATION in pursuance of the conditions of the Letters ratent,
filed by the said John Richards in the Great Seal Patent Office
on the 16th February 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
RICHARDS, of Adelphi, Strand, in the County of Middlesex, Mechanical
Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixteenth day of August, in the year
of our Lord One thousand eight hundred and seventy-five, in the
thirty-ninth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said John Richards, Her special
licence, that I, the said John Richards, my executors, administrators,
and assigns, or such others as I, the said John Richards, my exccutors,
administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thercafter during the term
therein expressed, should and lawfully might make, use, excrcise,
and vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands, and Isle of Man, an Invention for "IMPROVE-
MENTS IN MANDRELS FOR BENDING METAL PIPE," (a communication to me from
abroad by Morris. Longstreth Orum, of the City and County of Phila-
delphia, State of Pennsylvania, in the United States of America), upon
the condition (amongst others) that I, the said John Richards, my
executors or administrators, by an instrument in writing under my, or
their, or one of their hands and seals, should particularly describe and
ascertain the nature of the said Invention, and in what manner the
same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately
after the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Richards, my do hereby declare

page_text: is to be performed, to be particularly described and ascertained in
and by the following statement, reference being had to the accom-
panying Drawings and to the letters of reference marked thereon, that
is to say:--
These improvements are designed to provide simple and convenient
devices, by the use of which metal pipes can be bent to any desired
curvature without flattening or perceptible marking at the bend, as well
as, so far as practicable, to guard against breakage of the pipe in tho
operation, to which ends these improvements consist.
First. In a flexible metallic mandrel for bending round or elliptical
metal pipes or tubes, said mandrel being a spiral coil of wire, the section
of which is such as to present a flat or flattened surface on the exterior
of the spiral, and which is of sufficient pliability to be readily bent into
any curve desired, while at the same time possessing sufficient strength
to act as an internal support to the pipe, and prevent its deformation by
the action of the bending implements.
Second. In a flexible mandril for bending metal pipes or tubes of
square (or polygonal) section (such as are used for instance in the manu-
facture of gas fixtures), composed of a spiral coil of wire and two
flexible plates interposed between said coil and the inner surfaces of the
pipe or tube to be bent.
In the process of bending metal pipes or tubes as heretofore practised,
it has been difficult to form a bend of regular circular section by reason
of the tendency of the pipe to flatten at the bend in the operation, and
5 various expedients have been resorted to for the purpose of obviating
this difficulty.
A process which has been extensively practiced consists in filling the
pipe with rosin or analogous material, and removing the same by
melting after the pipe has been bent. This process is for obvious
) reasons inconvenient, and further, while involving the expenditure of
considerable time, does not in all cases prevent the flattening of the
pipe before mentioned.
In the accompanying Drawings, Fig. 1 is partly a side view and
partly a section of a piece of pipe with one of the improved mandrels
applied thereto; Fig. 2, a side view partly in section and on an enlarged
scale of a portion of the mandril shown in Figure 1; Fig. 3, a side view

page_text: partly in section of a portion of square pipe with one of the improved
mandrels applied; Fig. 4, a view of the same taken at right angles to
Fig. 3; Fig. 5, an end view on an enlarged scale of the same; Fig. 6,
a side view of a compound mandrel for round pipe; and Fig. 7, a similar
view of a mandrel having a wire rope core.
In order to bend a round or clliptical pipe by this Invention I provide
a flexible mandrel A, which is formed of a spiral coil of stout wire, the
diameter of the coil being such that the mandrel may fit easily within
the pipe.
The wire used to form the mandrel should be either of a square,
rectangular, or triangular section, or more or less flattened upon the
exterior surface of the spiral, so as to afford as much bearing surface
as possible to the pipe, and the spiral should be coiled as closcly as
practicable for the same reason. I then introduce the mandril into the
pipe and bend the latter to the curvature required by the ordinary
implements used for the purpose, and afterwards withdraw the mandrel
from the pipe, which it has been found in practice is not perceptibly
marked or injured in the operation, and the mandrel is ready for use
with another pipe. The mandrel can be readily withdrawn after bending
the pipe by attaching one of its ends to a lathe spindle, and revolving
it in such direction as to reduce its diameter by screwing up its coil.
Fig. 6 shows a compound mandrel composed of an outer and an inner
coil of wire A, A', the two coils being right and left handed screws
respectively. When it is desired to withdraw a mandrel of this form
from a pipe the two coils can be turned in reverse directions so as to
speedily reduce its diameter.
Fig. 7 shows a mandrel A¹ having a core of wire rope A² within it and
fastened to one of its ends, the purpose of which is to enable one end to
be held fast while the other is being screwed up to reduce its diameter.
For bending pipes of square or polygonal sections, I provide a flexible
mandrel B, which is formed of a spiral coil of stout wire, of such
diameter as to fit casily between two thin plates of flexible metal B¹, B',
interposed between the coil and the inner surface of the pipe upon the
two sides of the latter which are at right angles to the radius of the
curve to be formed.
Round, square, or flattened wire may be used to form the mandrel,
and the thickness of the plates B', B¹, should be sufficient to prevent

page_text: them from being indented or fractured in the bending operation without
rendering them so stiff as to oppose an undue resistance thereto. Their
width should be somewhat less than that of the pipe, so that they may
be readily inserted and withdrawn.
In the application of this device the mandrel and plates are introduced
into the pipe before commencing to bend it; it is then bent to the
curvature required by the ordinary implements and the mandrel and
plates then withdrawn. The flexible mandrel acts as a support to the
sides of the pipe in the operation, and prevents them from being
indented or injured, and the office of the plates B¹, B', the longitudinal
sections of which are curved in the operation correspondingly with the
mandrel, is to afford a bearing for the pipe thereon for the entire width
of the pipe, instead of at single points as would be the case if the plates
were not employed.
It has been found in practice that by the use of these devices, the
workman is enabled to bend either round or square metal pipes with
ease and celerity, and that by their introduction time, labor, and material
are economized.
I do not wish to be understood as broadly claiming a flexible mandrel
but what I do claim as the Invention is,-
First. A flexible mandrel for bending metallic pipe, consisting of a
spiral coil of wire presenting a more or less even surface upon the
exterior of the spiral, substantially as set forth.
Second. The combination of a spiral wire mandrel and flexible plates
interposed between the mandrel and the sides of the tube to be bent
substantially as set forth.
In witness whereof, I, the said John Richards, have hereunto set
my hand and seal, this Sixteenth day of February, in the year of
our Lord One thousand eight hundred and seventy-six.