NEW OR IMPROVED MACHINERY FOR THE MANUFACTURE OF SCREWS
Year: 1876

page_text: LETTERS PATENT to Thomas Rickett, of Northfield, near Birmingham, in the
County of Warwick, Manager of Works, for the Invention of "NEW OR
IMPROVED MACHINERY FOR THE MANUFACTURE OF SCREWS."
Sealed the 19th January 1877, and dated the 28th July 1876.
PROVISIONAL SPECIFICATION left by the said Thomas Rickett at the Office
of the Commissioners of Patents on the 28th July 1876.
THOMAS RICKETT, of Northfield, near Birmingham, in the County of Warwick,
"NEW OR IMPROVED MACHINERY FOR THE MANUFACTURE
Manager of Works.
OF SCREWS."
In the ordinary methods of inanufacturing screws a cylindrical bolt or rod is
operated upon by cutting dies or tools, by the action of which portions of the
metal are cut away, leaving a screw thread, the extreme diameter of which is of the
diameter of the bolt or nut operated upon. When cutting dies are employed they
are usually carried in a screw stock, and bear and act upon opposite or equidistant
points, the cutting dies being carried round the, stationary bolt or rod. When
cutting tools are employed they are made to operate on the bolt or rod by the said
bolt or rod being rotated in a lathe, the cutting tool bearing against it and travelling
in a direction parallel or nearly parallel to the axis of the rod or bolt.
My Invention consists of the new.or improved machinery herein-after described
by the action of which on the rod or bolt to be made into a screw a screw thread
is impressed upon the rod or bolt without the cutting away of any portion of the
metal. The said machinery consists essentially of rolls having screw threads cut
upon them by and between which rolls the rod or bolt to be made into a screw is
operated upon. Pressure being applied to the rolls their rotatory motion is com-
inunicated to the rod or bolt situated between them with its axis parallel to their
axes, and the screw threads on the rolls are impressed on the rod or bolt, which is
thus converted into a screw, I use three or more rolls with their axes parallel to
each other. Two of the rolls are placed as close together as possible in the same
plane with the third roll above and midway between them. The rod or bolt to be
screwed is placed between the three rolls, and the said rolls are made to rotate in
the saine direction. The upper roll is caused to approach the two lower rolls by
a parallel screw action or other equivalent mechanical arrangement. By this means
the sharp angles in the rolls are forced into the bolt, forming grooves therein and
raising the metal between the grooves until the threads of the rods are exactly re-
Price Gid]

page_text: produced in the bolt. The roll threads groove the bolt to about half their depth,
and the remainder of the thread is raised or forced up by tho motal displaced in the
embedding of the roll threads.
By this method bolts of any length less than that of the rolls can be made by a
few rotations, or in some cases by only one rotation. The bolts may be operated
upon either hot or cold, but I prefer to operate on the bolt while cold, the density
and strength of the metal being greatly increased by the rolling action when the
metal is operated upon in the cold state.
Screws of steel, iron, brass, copper, or other metals and alloys can be readily
made by the use of my machinery.
In some cases I prefer to make the acting portions of the rolls approach cach
other during each rotation by forming their acting surfaces slightly excentric to
their axes or by fixing them on excentric shafts. They are so arranged that
the portions of largest radius simultaneously approach to and recede from one
another. The screw blank can be introduced and withdrawn when the acting
surfaces are most distant, and when the acting portions of the rolls have approached
nearest to each other they will have formed a perfect thread so that one perfect
screw is made at each rotation of the rolls.
I make the rolls of steel hardened and tempered, the threads being cut upon
them to the depth required on the screws to be made.. When the rolls have the
same diameter as the screws to be made only one screw thread is made on each
roll, but when the rolls are of larger diameter than the screw to be made more
than one thread is made on each roll, the number of threads on the rolls increasing
as their diameters increase. Thus if the rolls have double the diameter of the
screws they have two screw threads each, if of treble the diameter they have three
screw threads and so on. When rolls of small diameter are employed I support or
back them up by larger rolls.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said Thomas Rickett in the Great Seal Patent Office on the 22nd January
1877.
THOMAS RICKETT, of Northfield, near Birmingham, in the County of Warwick,
Manager of Works. "NEW OR IMPROVED MACHINERY FOR THE MANUFACTURE
OF SCREWS."
My Invention consists of the new or improved machinery herein-after described
for the manufacture of screws, by the action of which said nachinery on the rod or
bolt to be made into a screw a screw thread is impressed upon the said rod or bolt
without the cutting away of any portion of the metal of the said rod or bolt.
The said machinery consists essentially of rolls having screw threads cut upon
them, by and between which rolls the rod or bolt to be made into a screw is
operated upon.
Pressure being applied to the rolls their rotatory motion is com-
municated to the rod or bolt situated between them with its axis parallel to their
axes, and the screw threads on the rolls are impressed on the rod or bolt, which is
thus converted into a screw. I use three rolls with their axes parallel to cach
other. Two of the rolls are placed as close together as possible in the same plane
with the third roll above and midway between them. The rod or bolt to be
screwed is placed between the three rolls, and the said rolls are made to rotate in
the same direction. The upper roll is caused to approach the two lower rolls by
mechanism which preserves the parallelism of the three rolls. By the action of the
parallel rolls the sharp edge of the threads of the said rolls are forced into the bolt,
forming grooves therein, and raising the metal between the grooves until the threads
of the rolls are exactly reproduced in the bolt. The roll threads groove the bolt to
about half their depth, and the remainder of the thread is raised or forced up by
the metal displaced in the embedding of the roll threads. By this method bolts

page_text: of any length less than that of the rolls can be made by a few rotations of the
rolls. The bolts may be operated upon either hot or cold, but I prefer to
operate on the bolt while cold, the density and strength of the metal being
greatly increased by the rolling action when the metal is operated upon in the
cold state.
I make the rolls of steel hardened and tempered, the threads being cut upon
them to the depth required on the screws to be made. When the rolls have the
same diameter as the screws to be.inade only one continuous screw thread is made
on each roll; but when the rolls are of larger diameter than the screw to be made
more than one thread is made on each roll, the number of threads on the rolls
increasing-as their diameters increase. Thus if the rolls have double the diameter
of the screws they have two continuous screw threads cach; that is, the threads
formed are those of a double-threaded screw; if of treble the diameter they have
three screw threads, and so on. When rolls of small diameter are employed I
support or back them up by larger rolls.
Screws of steel, iron, brass, copper, or other metals and alloys can be readily
made by the use of the said machinery.
I will now proceed to describe with reference to the accompanying Drawings
the manner in which my Invention may be carried ino effect.
Figure 1 represents in front elevation and Figure 2 in side elevation machinery
constructed according to my Invention for the manufacture of screws by impressing
a screw thread upon a plain rod or screw or bolt blank.
The said machinery consists essentially of three rolls a, b, c, having screw threads
cut upon their peripheries, the axes or shafts a, b, c, of the said rolls being
parallel to each other, and working in bearings in the uprights, d.
The peri-
pherics of the said rolls a, b, c, are concentric to their axes or shafts, and the con-
struction of the said rolls is herein-after particularly described.
The axes or
shafts a, b, of the lower rolls a, b, are situated in the same horizontal plane, and the
third roll c is situated above and midway between the said rolls a, b, (sce Figure 1.)
The upper screw roll c has an automatic rising and falling motion given to it, so
that it is made gradually to approach to and recede from the lower rolls a, b,
during the action of the machine. The lower rolls a, b, are adjustable by the set
screws a, b The axis c² of the rising and falling roll c is carried in the hear-
ings c,, which are capable of -sliding upon the uprights d, d, of the machine.
Above the shaft of the top roll is a parallel shaft y formed with an
eccentric q² between the bearings of the shaft. Working on the eccentric q* is a
metal strap the joint ends or pivots 9", ", of which engage in the sliding bear-
ings c, c, in which the shaft of the upper roll e works, so that by the rotation of
the said shaft q and the action of the eccentric 2 and strap 7, the upper roll c is
made gradually to approach to and recede from the lower rolls a, b. The bearings
of the shaft q are adjusted by the screws and screw nuts at 8. The shaft q makes
one revolution only (while the rolls a, b, c, are making several revolutions. The
rolls a, b, c, and the eccentric shaft q are driven by the following arrangement of
gearing-On the end of the shaft c of the upper rolle is a large toothed wheel c
receiving motion from any prime mover. Or the said shaft & may be driven by a
pulley and band. On the said shaft c is a toothed wheel which gives motion
through the toothed wheels c, c', and pinions c and c to the bottom rolls a, b. In
Figure 2 the toothed wheel co is omitted. The shaft y is driven from the shaft of
the toothed wheel c7 by the toothed gearing, partly indicated in dotted lines in
Figure 1, that is to say, on the shaft of the wheel c' is a pinion co which-gears with
the toothed wheel c₁₁. On the shaft of the wheel c¹ is a pinion c¹ whicli gears
with the toothed wheel c¹³ on the shaft q. The rising and falling of the upper roll c
is thus automatic and may be varied by the use of differential gear to suit different
pitches of screws.
The action of the machine is as follows:-The top screwed roll c being at its
highest point the plain rod or screw blank to be screwed is introduced between the
rolls a, b, c.
As the top roll c descends the rod or blank is seized between it and
.

page_text: the bottom rolls a, b, a rotatory motion is thereby communicated to the rod or blank
by the rotation of the said rolls and screw threads are impressed upon it, and when
the top roll has reached its lowest point a perfect screw thread will have been
impressed upon the rod or blank by the said roll c in conjunction with the bottom
rolls a, b. A bolt marked t is represented in the act of being screwed by the
operation of the rolls a, b, c. On the rising of the roll e the screwed bolt is released
and may be removed from the machine and another plain rod or blank introduced
between the rolls and screwed in the manner described.
The feeding of the blanks to the rolls may either be effected automatically or by
hand.
I do not limit myself to any particular ratio between the diameter of the rolls
by which the screw is formed and the diameter of the bolt to be operated upon,
nor do I limit myself to any particular rate of descent of the upper roll c relative
to the velocity of rotation of the rolls, but I have found the proportions represented
in the Drawings between the rolls and the bolt to be screwed to answer well in
practice, that is to say, the rolls a, b, c, have a diameter three times as great as that
of the bolt t to be operated upon. I have also found the rate of descent of the
upper roll c compared with the velocity of the rolls a, b, c, which rate is produced
by the arrangement of gearing represented in the Drawing to answer well in practice,
that is, the roll c descends from its highest to its lowest position during the time
occupied by the rolls a, b, c, in making three rotations.
In forming the screw threads on the rolls a, b, c. I give the said threads
on the rolls a pitch which is to the pitch of the thread to be produced on the
bolt as the diameter of the rolls is to the diameter of the bolt to be screwed.
Thus, the rolls represented in the Drawing have a diameter three times as
great as that of the bolt to be screwed, and the rise of the threads on the
roll is three times as great as the pitch of thread to be produced on the bolt. By
the pitch of the thread 1 mean the distance between the summit or crest of one
thread, and the summit or crest of the next thread, and by the rise I mean the
distance traversed along the roll by one convolution, the distance referred to being
measured in a line parallel with the axis of the roll. From this method of con-
struction, it follows that there will be several screw threads on the roll, the number
of the said screw threads increasing as the diameter of the roll increases, the thread
to be produced on the bolt remaining the same. Thus in the rolls represented and
having three times the diameter of the bolt to be screwed, the threads on the rolls
have a rise three times as great as that to be produced on the bolt, each of the rolls
having three equi-distant threads. If the rolls were of a diameter four times as
great as that of the bolt to be screwed, then the screw threads on the said rolls
would have a pitch four times as great as that of the thread to be produced on the
bolt, and there would be four of the said screw threads on cach of the rolls, and so
on for other proportions. It is only by adopting the relative proportions described
that the bolt under operation has no tendency to advance into or out of the machine
during the formation of the thread, a condition necessary to the correct figure and
uniform pitch of the screw thread formed.
Figure 3 is a diagram illustrating the construction of the rolls, the said diagram
representing the cylindrical surface of one of the rolls opened out or uncoiled or
opened flat, and the inclined parallel lines represented indicate the inclination and
distance apart of the screw threads formed on the roll.
Figure 4 represents in plan one of the rolls, and the screwed bolt being operated
upon, and shows the parallelism of the single thread produced on the bolt B with
the threads on the roll C.
Although I have found in practice that the mechanism described and represented
for producing the rising and falling parallel motion of the top roll answers every
purpose, yet I do not limit myself to the use of that particular arrangement as other
equivalent mechanical arrangements may be adopted for producing a like motion
in the top roll.
Having now described the nature of my Invention and the manner in which

page_text: the same is to be performed, I wish it to be understood that I do not limit myself
to the precise details herein described and illustrated as the same may be varied
without departing from the nature of my Invention, but I claim as my Invention
of "New or Improved Machinery for the Manufacture of Screws.'
"
First. The combination of a series of rolls having screw threads formed on them,
which screw threads have a proportion both in number and pitch to the screw
thread to be produced on the bolt operated upon similar to the proportion between
the diameter of the said rolls and the bolt operated upon, that is if the rolls have
a diameter three times the diameter of the said bolt, the said rolls have three equi-
distant screw threads, each thread having a pitch three times as great as that of
the thread to be produced substantially as herein-before described and illustrated
in the accompanying Drawings.
Secondly. The automatic rising and falling movement of one of the screwed rolls
by an eccentric or equivalent so that the parallelisin of the axes of all the rolls is
preserved during the action of the inachine as herein-before described and illustrated
in the accompanying Drawings.
In witness whereof, I, the said Thomas Rickett, have hereunto set my hand
and seal, this Seventeenth day of January, in the year of our Lord One
thousand eight hundred and seventy-seven.
Witness,
GEORGE SHAW.
THOMAS RICKETT. (L.S.)