IMPROVEMENTS IN APPARATUS FOR THE MANUFACTURE OF LEAD, TIN, AND OTHER SOFT METAL PIPING
Year: 1874

page_text: LETTERS PATENT to Walter Francis Pitchford, of Belsize Square,
•
· Hampstead, in the County of Middlesex, for the Invention of
"IMPROVEMENTS IN APPARATUS FOR THE MANUFACTURE OF LEAD, TIN, AND
OTHER SOFT METAL PIPING."
Sealed the 23rd October 1874, and dated the 27th April 1874.
PROVISIONAL SPECIFICATION left by the said Walter Francis Pitchford
at the Office of the Commissioners of Patents, with his Petition,
on the 27th April 1874.
I, WALTER FRANCIS PITCHFORD, of Belsize Square, Hampstead, in
the County of Middlesex, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN APPARATUS FOR THE MANUFACTURE of Lead,'
TIN, AND OTHER SOFT METAL PIPING," to be as follows:-
:
In the manufacture of lead and tin piping by the ordinary method the
apparatus employed consists of a container in which the lead or tin is
placed, a dié being arranged in combination with the said container,
through which the metal is forced by a piston operated by hydraulic
pressure. In the centre of this die there must be a core or mandril

page_text: which forms the bore or interior of the pipe. This mandril has to be
supported in such a manner as to remain in its proper position while the
metal is forced through the die. For this purpose it has been usual to
employ a bridge so constructed as to afford the required support to the
core or mandril while permitting the metal to pass under or over it to
the die. These bridges have heretofore been so constructed and arranged
in relation to the dic as to offer considerable resistance to the passage of
the metal, and therefore great power was required to force the metal
through the die. But according to my Invention I so construct the said
bridge and arrange the same in combination with the die, and I so form
the die itself as to accomplish the operation of forcing the metal through
the die with very little resistance beyond that offered by the adhesiveness
of the metal itself.
In applying my Invention to an apparatus or press wherein the con-
tainer is stationary and has the die in its lower end, and the piston
descends to force the lead through the said die I construct a bridge,
which consists of a semicircular piece of steel, malleable cast iron, or
other suitable metal made very thin, and which is placed across the top
of the die with its convex or curved part upward in the container.
The said convex or curved portion has a sharp or knife edge, so that the
metal meets with very slight resistance as it is forced down by the piston.
And for the same pnrpose the said bridge is curved or chamfered to an
edge at its lower side. The bridge has its two ends or extremities
widened, and rests thereby on the die holder, the surface of the said ends
being level with the top or upper edge of the die, so that there is but a
short space between the top of the die and the top or knife edge of the
bridge.
The mandril or core is formed solidly upon the said bridge, and
projects down centrally through the die. There are apertures between
the feet and mandril, so that the metal after its division by the bridge
meets under the same before it enters the die. The bridge and mandril
are made prefectly smooth and polished. The dies are made with the
upper part smaller in diameter than the lower part, so that they present
an edge instead of a flat or curved surface to the entering metal. The
said dies simply rest in a recess, and are readily removed and replaced,
so that dies of larger or smaller diameter may be put in the press.
In presses where the container is moveable and the die is placed in the
lower end of a stationary or fixed piston the form of the bridge is the

page_text: same as above described, except that its ends have feet or lugs whereby
it is secured by screws to the die holder or box, and which also keep the
die in place.
:
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Walter Francis Pitchford in the Great Seal Patent
Office on the 27th October 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WALTER
FRANCIS PITCHFORD, of Belsize Square, Hampstead, in the County of
Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-seventh day of April, in the year
of our Lord One thousand eight hundred and seventy-four, in the thirty-
seventh year of Her reign, did, for Herself, Her heirs and successors, give
and grant, unto me, the said Walter Francis Pitchford, Her special
licence that I, the said Walter Francis Pitchford, my executors, admi-
nistrators, and assigns, or such others as I, the said Walter Francis
Pitchford, my executors, administrators, and assigns, should at any time
agree with, and no others, from time, to time and at all times thereafter
during the term therein expressed, should and lawfully might make,
use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN APPARATUS For the Manufacture of Lead, TiN, AND OTHER
SOFT METAL PIPING," upon the condition. (amongst others) that I, the
said Walter Francis Pitchford, 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 Walter Francis Pitchford, do hereby
declare the nature of my soid Invention and in what mannen the come

page_text: is to be performed, to be particularly described and ascertained in and by
the following statement, reference being had to the accompanying
Drawing forming a part of this Specification:-
In the manufacture of lead and tin piping by the ordinary method the
apparatus employed consists of a container in which the lead or tin is
placed, a die being arranged in combination with the said container,
through which the metal is forced by a piston operated by hydraulic
pressure. In the centre of this die there must be a core or mandril
which forms the bore or interior of the pipe. This mandril has to be
supported in such a manner as to remain in its proper position while the
metal is forced through the die. For this purpose it has been usual to
employ a bridge so constructed as to afford the required support to the
core or mandril while permitting the metal to pass under or over it to
the die. These bridges have heretofore been so constructed and arranged
in relation to the die as to offer considerable resistance to the passage of
the metal, and therefore great power was required to force the metal
through the die. But according to my Invention I so construct the said
bridge and arrange the same in combination with the die, and I so form
the die itself as to accomplish the operation of forcing the metal through
the die with very little resistance beyond that offered by the adhesiveness
of the metal itself, and the bore is formed before the metal enters the
die, and the splitting of the pipe is prevented as the metal is thoroughly
amalgamated.
In the accompanying Drawing Figures 1, 2, and 3 illustrate the
application of my Invention to an apparatus or press wherein the con-
tainer is stationary and has the die in its lower end, and the piston
descends to force the lead through the said die.
Figure 1 is a plan of my improved apparatus.
Figure 2 is a vertical section of part of a container fitted with the
said apparatus.
Figure 3 is a transverse section on the line x, x, Figure 2.
The bridge a consists preferably of a semicircular piece of steel,
malleable cast iron, or other suitable metal made very thin, and placed
across the top of the die b, with its convex or curved part a¹ upward in
the container c. The said convex or curved portion has a sharp or knife
edge, as shewn in Figure 3, so that the metal meets with very slight

page_text: t
resistance as it is forced down by the piston, and the bridge a is curved
or.chamfered in its transverse section, as shewn in Figure 3, so that its
lower or inner edge a* is also a knife edge. The said bridge has its two
ends or extremities a widened, and rests thereby on the container and
slightly overlaps the die 6, the surface of the said ends being level with
the top or upper edge of the die. And it will be seen by referring to
Figure 2 that there is but a short distance between the top of the die b
and the upper or outer knife edge a¹ of the bridge a.
.
The mandril or core a³ is formed solidly upon or in one piece with the
said bridge a, and projects down centrally through the die b, as shewn.
There are apertures & between the feet a² and mandril a³ so that the
metal after its division by the bridge meets under the same before it
enters the die b. The bridge a and mandril as are made perfectly
smooth and polished to diminish the friction to the lowest possible
quantity. The peculiar formation of the bridge with the upper and
lower or outer and inner cutting edges, and with a deep and narrow
transverse section, as shewn in Figure 3, prevents the breaking of the
bridge, and offers but little obstruction to the passage of the metal, and
the metal after being separated by the upper edge a¹ will pass easily over
the sides of the bridge and unite under the same around the mandril
before entering the die. The shape or configuration of the bridge may
be varied to adapt it to any particular construction of container, but in
all cases it has the outer and inner or upper and lower knife edges with
sufficient depth of metal between them to give the required strength to
the bridge without great thickness.
The die 6 is made taper, that is to say it is smaller in diameter at the
top than at the bottom, as shewn in Figure 2, so that it presents a
cutting edge b' instead of a flat or curved surface to the entering metal.
The said die simply rests in a recess e, and is readily removed and
replaced so that dies of larger or smaller diameter may be put in the
press.
Figures 4 and 5 illustrate the adaptation of my Invention to a press
wherein the container is movable and the die 6 is placed in the lower
end of a stationary or fixed piston. Figure 4 is a vertical section of the
die holder of this press provided with my improved apparatus. Figure 5
is a section on the line y, y, Figure 4. The bridge a has the outer and
inner knife edges, and its form is the same as that above described,
except that its ends have feet or lugs of whereby it is secured by screws

page_text: to the die holder or box g¹, and which also keep the die in place. The
same construction is adapted when the container is stationary and the
metal is moved upward within the same.
With my improved apparatus the pipe is produced with little pressure,
and consequently little wear and tear of the parts of the apparatus and
machinery. The pipe is of uniform thickness throughout its length, and
its bore is perfectly central; it is more rapidly and cheaply manufactured,
and is more durable than piping manufactured by the apparatus hereto-
fore employed.
My Invention is chiefly designed for the manufacture of the smaller
sizes of lead, tin, or composition pipes.
Having thus fully described my said Invention, and the manner of
performing the same, I wish it understood that I claim, the bridge
shaped substantially in the peculiar manner shewn and with a double
knife edge, and the die with a sharp or cutting edge fitted together in
the die holder of a pipe press in such a manner that there is a space
between the under or inner knife edge of the bridge and the edge of the
die, in which space the metal after being separated by the upper or outer
knife edge of the die is readily re-united around the mandril, so that the
bore of the pipe is formed before the metal enters the said die as herein
set forth.
In witness whereof, I, the said Walter Francis Pitchford, have
hereunto set my hand and seal, this Twenty-sixth day of October,
in the year of our Lord One thousand eight hundred and seventy-
four.
Witness,
LEWIS SANDERSON,
...8, Southampton Bdgs.,.
London.
W. F. PITCHFORD. (L.S.)