Improvements relating to Mandrels, applicable for Cold Bending and Manipulating Light Tubes.
Year: 1892

page_text: Date of Application, 16th Dec., 1892
Complete Specification Left. 30th June, 1893-Accepted, 26th Aug., 1893
PROVISIONAL SPECIFICATION.
Improvements relating to Mandrels, applicable for Cold Bending
and Manipulating Light Tubes.
JOHN MILBROWE SMITH 382 High Street West Bromwich Staffordshire Cycle
Manufacturer do hereby declare the nature of this invention to be as follows:-
My invention relates to improvements in mandrels applicable for cold bending
and manipulating light tubes and is designed to facilitate the bending and shaping
of light metal tubes, round or other shapes, and to prevent the crushing and
denting in, of the said tubes, during the opporation of bending and fitting the same.
The mandrel consists of a length of flat square or round steel wire, in either a
single or double coils, and coiled spirally close together round a properly shaped
steel bar, and then turned or dressed to the desired size. The steel bar acting only
as a mould, is then withdrawn from the inside of the coiled wire and a very flexable
hollow mandrel is thus obtained similar to a closely coiled spring and capable of
bending easily in any direction but withstanding considerable pressure of a crushing
or denting action.
By carrying down the inside of the hollow spiral mandrel a chain or a second
wire coiled in an opposite direction and joined to the one end of the outside
mandrel, I can twist both ends, from the opposite end where a handle is provided
with means to secure the twist in various positions.
By this twist, the coils are wound up or unwound, thus varing the outside
diametre of the mandrel so that it can be inserted, and withdrawn easily from the
tubes and yet adjusted to fit tightly inside.
I believe the apparatus will prove useful to manufacturers, and obviate the
present dangerous use of explosive wet sand, or molten lead, now used in bending
tubes.
Dated this Difteenth dan
ambar 1000
JOHN MILBROWE SMITH.
COMPLETE SPECIFICATION.
Improvements relating to Mandrels, applicable for Cold Bending
and Manipulating Light Tubes.
1, JOHN MILBROWE SMITH, 382, High Street, West Bromwich, Staffordshire,
Cycle Manufacturer, 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 :-
My invention relates to improvements in, or to additions to, flexible mandrels or
flexible internal supports for the bending or fashioning of tubes or tubular or hollow
articles, and particularly for the cold bending of light metallic tubes of any cross
section, and has for its object, the providing of an internal support capable of being
readily introduced into and withdrawn from an article under manipulation.
By my invention, the mandrel is both capable of being increased and diminished
in diameter, whilst being longitudinally flexible, so that an instrument or apparatus,
before being introduced into a tube or article to be bent, may be first reduced in
girth, and then introduced, and subsequently expanded to the full bore of the
article under manipulation, or it may be introduced at its normal size, and then
expanded, when the said article can be properly bent without puckering, wrinkling
or bursting the metal or material of the article under treatment.
A mandrel constructed according to my invention consists primarily of a coil of

page_text: steel or other wire, or a compound coil of steel or other wire of any desired section,
fitted or provided interiorly with a coil, chain or other flexible axis or medium for
the closing or contraction of, and consequent diminution or expansion of the
diameter of, the said coil, hence an adjustable and flexible mandrel or internal
support.
The motion transmitting coil, chain or central medium, is preferably joined to
the outer coil at the fore end or fore part, whilst the rear part of the said motion
transmitting medium is fitted with a ratchet, clutch, catch, or other stop means for
securing the coils in their twisted or wound up state.
Thus, by twisting the outer coil, which admits of expanding or contracting
through the medium of the inner coil or the like, the said outer coil is capable of
being varied in diameter for its introduction into, expansion within, and withdrawal
from, the interior of a tube, before, during and after bending.
Figure 1 of the accompanying drawing represents partly in longitudinal vertical
section, and partly in elevation, an adjustable and flexible mandrel constructed and
arranged, and fitted and provided with improvements made according to my
invention.
The middle part of the said mandrel is shown broken off.
Figure 2 shows the handle end portion of the said mandrel in elevation, thereby
exemplifying how motion is communicated to the interior coil or flexible axis, and
how the same may be retained in its twisted and expanded or contracted state by
the crown.ratchet teeth of the one part engaging with the crown teeth of the fixed
part.
Figure 3 represents the handle separately.
Figure 4 is a cross section upon the dotted lines A. B. Figure 1.
Figure 5 is a cross section upon the dotted lines CD of the said figure, whilst
Figure 6 is a cross sect on upon the dotted lines E F Figure 1.
Figure 7 shows the mandrel within a length of tubing about to be bent, and
Figure 8 represents the same bent, and prior to the withdrawal of the mandrel.
The same letters of reference indicate corresponding parts in the several figures
of the drawings.
a is an outer and closely wrapped open coil, made from square sectioned wire,
and is organized so as to admit of the coils or convolutions of the same being
wound up or contracted upon each other, and the diameter thereby reduced or
unwound or untwisted in an opposite direction and the convolutions expanded,
hence an increase of diameter, and which is performed by or through the medium
of a flexible axial or inside coil 6, with the coils as represented wound in an opposite
direction to those of the mandrel coils a.
The fore or contracted nose end a², of the outer coil a, is made square upon its
inside, and within which inside square part, the fore end 62, of the inner and motion
communicating axial coil b, fits, and is thereby prevented from rotating, other than
bodily with the coil a.
The union or connection of the said ends is made by a screw c, taking into the
wormed inside of the end of the inner coil, so that as the coil, is rotated, through
the medium of the handle d, the convolutions of the outer coil are contracted or
expanded, according to the direction in which the flexible axis is turned by the
handle.
Made fast to the back end 63, of the inner coil b, is a barrel or stalk b', carrying
at its rear end, a screw 6, and at its extreme end, an angular shank 65, upon which
an attachable and detachable handle d, takes, for the winding up for expanding or
contracting the said coil.
Surrounding the said screwed part 4, is a traversing nut or screw collar e, coming
against or at the back of a locking or spring coil or coiled spring f, disposed
between the said nut e, and the back of a ratchet or crown pawl-sleeve g, sliding
upon the barrel or stalk 6', and with the teeth g³, of it, adapted to engage with the
opposed ratchet teeth h³, of a fixed casing h, made fast to the inner end a', of the
outer and adjustable coil a, and connection is made between the inner coil and

page_text: the outer coil, with the former capable of twisting or turning within the latter, by
a screw pin i, taking through the walls of the casing, and with the stem passing
into the annular groove h', made within the barrel b
The sleeve pawl or crown ratchet g, has a bayonet slot g³, wherethrough a stud 6º,
on the barrel b', takes, so that the opposed teeth of the one part can be removed
from the opposed teeth of the other part, and the said movable ratchet part held
back.
The screwing up of the screw collar closes up the coils f, into a solid or compact
tubular length, and forms a stop or block against the movement of the ratchet
catch part g, hence the affixing of the outer coil in its wound up and expanded or
contracted state.
Now assuming that a length of tubing as in Figure 7, is required to be bent into
a shape alike unto that represented in Figure 8, and that normal diameter of the
mandrel is greater than can be easily introduced, first rotate the handled from
right to left, as indicated by the full arrow, and by it wind up the coil u, to a slight
extent, whereby its diameter or girth is diminished, and in this state, the said coil,
which is the mandrel coil, is retained by the teeth of the part g, engaging with the
teeth of the part h.
This done, then insert the said wound-up mandrel into the interior of the tube k,
wherein it freely slides.
Now release the said pent-up coils, by drawing back the part g, when the said
coils expand themselves or open out to nearly the full inside bore of the tube to
be bent.
This done, then expand the mandrel coils, by turning the flexible axis by the
handle in the direction indicated by the dotted arrow with the opposed ratchet
teeth of the parts clear of each other. Then when the proper expansion has been
attained, fix the mandrel coils by making the catch teeth of the parts engage with
each other, and be there held by the blocking or closing of the coils of the spring,
by propelling the nut e.
This said spring f, acts ordinarily as a pawl spring when the mandrel coil is
contracted, and as a check or block when the said mandrel coil is expanded.
Now bend the tube together with and upon the mandrel to the desired figure
such as in Figure 8. Now as the mandrel requires to be removed, the same must
have a less girth than the inside of the tube in order to be freely withdrawn, and
to accomplish this, now contract the diameter or draw into less compass the coil,
and this is accomplished by winding up the mandrel coils a, in the direction of the
full arrow and thereby contracting its diameter, and which is automatically held in
its contracted condition by the teeth of the sliding pawl part wiping over the teeth
of the fixed casing part.
It is understood that the motion of the handle is transmitted first through the
barrel, then travels down the coil or flexible axis b, and as torsion proceeds,
then to the end 6, and from thence travelling up from the fore end a², to the inner
end a', of the outer or mandrel coil a, and the coiling proceeds first down the inner
flexible axis, and then up the outer coil, until the convolutions are brought
sufficiently together to make the necessary reduction or enlargement in its diameter.
It is understood that the pent up coils are kept in one state by the rack teeth
automatically engaging with each other, and in the other states by the propelling of
the nute and compressing the spring coils forward of it.
My invention is particularly applicable to the bending of cycle tubes, refrigerator
coils, plumbers lead bend, musical instrument parts, tubular articles, bedstead
tubings, glass tubes and other tubular articles composed of various materials.
I wish it to be understood that any flexible axis, such as chain, a jointed rod
links or other flexible medium may be employed as the means of transmitting
motion from the handle to the mandrel coil in lieu of a coil, and further, I do not
limit myself to the precise means of winding up the mandrel coil, as other means
may be employed with a like or nearly like effect without departing from the
nature of my invention,

page_text: Thus, the mandrel coil may be contracted only, then placed within a tube, and
then allowed to expand to its normal state, which is the full sized bore of the tube
to be bent.
Instead of employing the securing means of the ratchet teeth, I may employ
crown teeth or clutch teeth, or instead of employing a single mandrel coil, I may
employ a compound one, and instead of employing a flexible axis as described, I
nay employ strands or strips of flexible metal as the means for communicating
motion to the mandrel coils.
Or instead of winding up the mandrel coil through the medium of the flexible
axis, I inay make the flexible axis to act as a stay only, whilst the mandrel coil is
wound up for either expansion or contraction, and may be retained or prevented
from re-rotating by a catch of it engaging with a stay or holder.
Figure 9 represents a further form of my invention where no flexible axis is
employed.
a is the mandrel coil, with the terminations of the metal of the same formed into
flexible axial coils or flexible straight rod b, terminated by handles or holding
means d, so that when an article is required to be bent, one of the ends of smaller
diameter is then passed through the same and the two smaller ends twisted in
opposite directions, which then wind up the convolutions of the mandrel coils and
contract the diameter of it, and when held or kept in this state, the said mandrel
coil is drawn into the hollow article or tube, and then allowed to expand to its full
extent, after which the mandrel coil convolutions are then again contracted for
removal.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is-
First. A flexible and adjustable mandrel or internal support for the bending of
tubes and hollow articles, consisting primarily of a mandrel coil or coils, fitted or
provided with a flexible and motion transmitting axis, whereby the convolutions
of the coils admit of being wound up or wound down, and the mandrel coil
diameter increased or decreased or both, substantially as described and set forth in
Figures to 8.
Secondly. A flexible and adjustable mandrel or internal support for the bending
of tubes and hollow articles, consisting primarily of a mandrel coil or coils, fitted or
provided with a flexible axis, upon which the said mandrel coils admit of being
wound up or wound down, and its diameter contracted or increased or both, substan-
tially as described and set forth in Figures 1 to 8.
Thirdly. A flexible and adjustable mandrel consisting of a primary and adjust-
able mandrel coil (or coils) united at its outer end to the outer end of a flexible or
motion-transmitting axis, substantially in the way and by the means as described
and set forth in Figures 1 to 8.
Fourthly. In flexible and adjustable mandrels, locking, fastening or securing the
mandrel coil (or coils) after being wound up, wound down or adjustably expanded
or contracted by means and in the ways substantially as described and set forth.
Fifthly. In flexible mandrels, the general construction, arrangement and com-
bination of the holding parts, with or without the locking means, substantially as
described and set forth in Figures 1 to 8.
Sixthly. A flexible and adjustable mandrel, consisting of a primary bending coil
and secondary or twisting coils or stems provided with turning ends or handles
aubstantially as described and set forth in Figure 9.
Dated this 29th day of June 1893
JOHN MILBROWE SMITH,
By Henry Skerrett,
6, Livery Street, Birmingham, Agent for Applicant.