IMPROVEMENTS IN MACHINERY OR APPARATUS FOR DRAWING STEEL AND OTHER TUBES
Year: 1876

page_text: LETTERS PATENT to Thomas Rickett, of Birmingham, in the County of Warwick,
for the Invention of "IMPROVEMENTS IN MACHINERY OR APPARATUS FOR
DRAWING STEEL AND OTHER TUBES."
Scaled the 14th July 1876, and dated the 5th April 1870.
PROVISIONAL SPECIFICATION left by the said Thomas Rickett at the Office
of the Commissioners of Patents on the 5th April 1876.
THOMAS RICKETT, of Birmingham, in the County of Warwick.
"IMPROVEMENTS
IN MACHINERY OR APPARATUS FOR DRAWING STEEL AND OTHER TUBES."
My improvements in machinery or apparatus for drawing steel and other tubes
have for their object the production of tubes with an internal taper, that is, tubes
thinner at one end than at the other, while the external diameter remains the same.
It is commonly known that locomotive boiler tubes are invariably made taper
inside and parallel outside, that is to say, nearly double the thickness at the "fire-
box" end to what they have at the "smoke box" end; this is done in order to
have the greater thickness where the most wear exists, and the lesser thickness
where not required for wear and tear, to economisc cost and weight, and also
because a thinner tube conducts heat more rapidly than a thicker one.
Brass and copper tubes are made taper inside by drawing them upon a taper bar
or mandril the entire length of the tube, and afterwards stripping the tube off the
mandrit, a process which is not practicable for steel tubes; and at present to the
best of my knowledge there is no plan existing by which steel tubes may be drawn
with an internal taper, as desired, for boiler tubes.
In the process of drawing steel tubes the tubes are usually drawn over a fixed
bulb-headed mandril, adjusted so that the centre or largest part of the bulb end is
in the centre or smallest part of the die, and my improved plan of tapering consists
in having a short taper mandril or plug arranged, so that during the process of
drawing the tubes through a fixed die the taper mandril or plug is moved forwards
or backwards, as required, by any suitable mechanical means, and it is evident that
if a tube be drawn over a taper plug when the small end is in the centre of the die
the tube will be of the thickness equal to the annular space between the small end
of the plug and the centre of the die; and if another tube be drawn over this same
plug when the largest end is in the centre of the die the tube when drawn will be

page_text: thinner than the previous one in proportion to the taper on the plug. If now the
same plug is made to change its position with regard to the dic by mechanical
means during the process of drawing, the small end being in the centre of the die
when the tube is beginning to be drawn, and the plug gradually moving forwards
till the large end is in the centre of the die when the tube is finished drawing a
tube will be produced, having an internal taper corresponding to the taper on the
plug, aud proportionate in length to the relative speed by which it is made to
traverse; that is, if the length of the tube to be drawn taper is 12 feet when
finished, and the length of the taper required on the plug be 1/2 inches, then the
speed of the bench compared with that of the plug will be as 96 to 1, and for an
feet tube as 64 to 1.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thomas Rickett in the Great Seal Patent Office on the 5th October
1876.
THOMAS RICKETT, of Birmingham, in the County of Warwick.
"IMPROVEMENTS
IN MACHINERY OR APPARATUS FOR DRAWING STEEL AND OTHER TUBES."
My improvements in machinery or apparatus for drawing steel and other tubes
have for their object the production of tubes with an internal taper, that is, tubes
thinner at one end than at the other, while the external diameter remains the same.
It is commonly known that locomotive boiler tubes are invariably made taper
inside and parallel outside, that is to say, nearly double the thickness at the "fire-
box end" to what they have at the "smoke box" end; this is done in order to have
the greater thickness where the most wear exists, and the lesser thickness where
not required for wear and tear, to economise cost and weight, and also because a
thinner tube conducts heat more rapidly than a thicker one.
Brass and copper tubes are made taper inside by drawing them upon a taper bar
or mandril the entire length of the tube, and afterwards stripping the tube off the
mandril, a process which is not practicable for steel tubes; and at present to the
best of my knowledge there is no plan existing by which steel tubes may be drawn
with an internal taper, as desired, for boiler tubes.
In the process of drawing steel tubes the tubes are usually drawn over a fixed
bulb-headed mandril, adjusted so that the centre or largest part of the bulb end is
in the centre or smallest part of the dic, and my improved plan of tapering.consists
in having a short taper mandril or plug arranged so that during the process of
drawing the tubes through a fixed die the taper mandril or plug is moved forwards
or backwards, as required, by any suitable mechanical means, and it is evident that
if a tube be drawn over a taper plug when the small end is in the centre of the die
the tube will be of the thickness equal to the annular space between the small end
of the plug and the centre of the die, and if another tube be drawn over this same
plug when the largest end is in the centre of the die, the tube when drawn will be
thinner than the previous one in proportion to the taper on the plug. If now the
same plug is made to change its position with regard to the die by mechanical
means during the process of drawing, the small end being in the centre of the die
when the tube is beginning to be drawn, and the plug gradually moving forwards
till the large end is in the centre of the die when the tube is finished drawing a
tube will be produced having an internal taper corresponding to the taper on the
plug, and proportionate in length to the relative speed by which it is made to
traverse, that is, if the length of the tube to be drawn taper is 12 feet when finished,
and the length of the taper required on the plug be 1½ inches, then the speed of
the bench compared with that of the plug will be as 96 to 1, and for an 8 feet tube
as 64 to 1.
And in order that my said Invention may be more clearly understood and readily

page_text: Sheet I. shows a hydraulic draw bench constructed with hollow or cylindrical
rams, according to the plan described in a Provisional Specification filed by me on
the 21st March, last No. 1206, and having two main hydraulic cylinders A, A,
fixed together one above the other, with the tube to be drawn placed in the centro
between the two cylinders.
Figure 1 is a side elevation, partly in section, showing my new tapering gear
attached to the draw bench.
Figure 2 is a plan of tapering gear chain wheels, showing an endless chain by
dotted lines.
Figure 3 is an end view, showing the tapering gear.
Figure 4 is a transverse section of the draw bench.
a, Figure 1, represents a steel tube in section, attached in the usual manner to
the travelling cross head b of the draw bench; c is the fixed die, through which
the tube is being drawn; d is the taper plug placed in the centre of the die c; the
other end of the stem of the plug is formed into a screw which takes into a
sliding socket c. This sliding socket has collars at both ends, and passes through
the back ends of the cylinder flanges, and it has a feather fixed or formed on its
circumference. f is a bevel wheel placed upon the sliding socket e; it has a slot
cut through its centre corresponding with the feather on the sliding socket; g is a
bevel pinion fixed on a vertical shaft h, and on the upper end of this vertical shaft
there are fixed one or more chain pullies i, and there are corresponding chain
pullies on the other end of the bench; an endless chain j passes round these
pullies, and is attached at any point to the travelling head of the bench by a
bracket fixed to it. When the bench is in notion the chain j attached to the
travelling head b, passing round the pullies i, i, turns the bevel pinion and wheel
and f, which by means of the feather before mentioned communicate motion to the
sliding socket e containing the screwed end of the stem of the taper plug d, the
screwed sliding socket, being turned round while the stem of the plug does not turn,
moves or controls the movement of the taper plug forward or backward in the
centre of the die c, and is so arranged that the taper plug d is moved from the
smallest to the largest diameter while the tube is being drawn over it, thus
producing a tube proportionally thick at the front end and thin at the back end.
On the return stroke of the bench the gearing and screw turn in the contrary
direction, and the plug is drawn back again, so that the small end comes in the
centre of the die c ready to commence tapering the next tube.
9
Sheet 2 shews in Figure a full sized section of a parallel tube passed over the
taper plug d, ready for being tapered by drawing it off again.
Figure 6 shows the commencement of tapering at the small end of the plug.
Figure 7 shows the completion of tapering at the large end of the plug
Figure 8 shows the section of a parallel tube.
Figure 9 shows a section of the same tube after having passed through the
tapering process.
Figure 10 shows a similar tube with a thickened end, giving greater strength for
fixing into boilers.
For some purposes tubes are required parallel inside for a certain distance and
then taper to the end, and when so desired the tubes may be drawn over the taper
plug for the distance required, parallel without the movement of the tapering gear,
and the connection made at whatever point the tapering is required to commence ;
or the plug may be made parallel for a proportionate distance, and the tapering gear
be continued in action the whole time, as may be preferred.
In some cases it would be an advantage to have the thin end of boiler tubes
made thicker for a short distance, say, 2 inches, to give greater support in fixing

page_text: them in the boiler; this can be accomplished by withdrawing the taper plug
entirely for the distance required. The effect will be that the tube will simply
close in on passing through the die, leaving that portion of the tube the original
thickness as at the other end, as shown at Figure 10.
Having thus described the nature of my said Invention, and the manner in which
the same may be carried into effect, I wish it to be understood that I do not confine
myself to the particular mechanical means herein shown and described for actuating
the taper plug while under the tension put upon it by the drawing process, for this
may be varied according to circumstances; but what I claim is, the use of a taper
plug or mandril which has a motion imparted thereto within the tube, while the
latter is being drawn over the same and through the die by mechanical means for
the purpose of varying the internal diameter of the tube, substantially as hercin
shown and described.
In witness whereof, I, the said Thomas Rickett, have hereunto set my hand
and seal, this Thirtieth day of September, in the year of our Lord Onec
thousand eight hundred and seventy-six.
THOMAS RICKETT. (L.S.)