IM- PROVEMENTS IN MACHINERY FOR THE MANUFACTURE OF SCREW HEADS
Year: 1876

page_text: LETTERS PATENT to Frederick Carley Coxhead, of No. 27, Leadenhall Street,
"
in the City of London, Engineer, and Robert Steers, of No. 24, Manor Road,
Walworth, in the County of Surrey, Gentleman, for the Invention of IM-
PROVEMENTS IN MACHINERY FOR THE MANUFACTURE OF SCREW HEADS."
Scaled the 2nd February 1877, and dated the 30th November 1876.
PROVISIONAL SPECIFICATION left by the said Frederick Carley Coxhead
and Robert Steers at the Office of the Commissioners of Patents on the 30th
November 1876.
FREDERICK CARLEY COXHEAD, of No. 27, Leadenhall Street, in the City of
London, Engineer, and ROBERT STEERS, of No. 24, Manor Road, Walworth, in the
County of Surrey, Gentleman. "IMPROVEMENTS IN MACHINERY FOR THE MANU-
FACTURE OF SCREW HEADS."
In the Specification of a former Patent granted to one of us, the said Robert
Steers, the 12th day of April 1875, No. 1326, for "Improvements in Serew Heads
and in Drivers or Tools for the same," is described a screw having a six-sided
tapering aperture or recess formed in the centre of its head, so that a driver or tool
similarly shaped can be inserted to screw up or unscrew, as the case may be. Now
our Invention relates to machinery for making such recesses in screw heads. For
this purpose we first drill a tapering hole in the screw blank by means of a machine,
in which the blank is presented to the drill and held in position whilst being drilled
by and between a set of recessed blocks having projections so formed and arranged -
that the projections of the several blocks constituting a set, when held together by
a suitable ring, form at each side a sort of compound trunnion, which rests in a
bearing, and on which the set of blocks can be rotated. In conjunction with the
blocks is arranged a wedging or tightening device, by one movement of which the
blocks are caused to grip the blank to be drilled; by another movement they are
released, so as to allow of the drilled blank dropping out after the drilling operation.
Having drilled the blanks, we complete the formation of the tapered six-sided aper-
ture or recess by the use of a reciprocating punch in conjunction with a holding
device composed of a couple of discs or plates arranged on a common axis or shaft,
one dise or plate being fixed on the said axis, whilst the other is free to move end-
wise thereon, though not to rotate independently thereof. The two discs or plates

page_text: are near their peripheries recessed on their inner sides or faces at intervals to receive
and hold the blank between them, and the disc or plate fixed on the axis or shaft is
formed or provided with a peculiar star-shaped cam or recess, in gear with which is
a pin or projection travelling with the punch carrier, which carrier also operates a
wedge.
The blank to be operated upon is dropped into position between the discs or
plates, and as they rotate towards the punch the wedge tightens them upon the
blank;
then the rotary movement temporarily ceases; the punch enters the opening
in the blank, completes the formation of the tapered six-sided recess, and afterwards
recedes; as it recedes the wedge is withdrawn, so as to release the loose disc or
plate, which by springs arranged between the two discs or plates is moved away
from the fixed disc or plate, and on the further rotary movement of the discs or
plates the blank with its completed head falls out.
In some cases, for example in the manufacture of machine screws, the preliminary
drilling operation herein-before described may be dispensed with, the recess being
formed whilst the blank is in a highly heated state by inachinery constructed on the
principle last herein-above described.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said Frederick Carley Coxhead and Robert Steers in the Great Seal Patent
Office on the 30th May 1877.
FREDERICK CARLEY COXHEAD, of No. 27, Leadenhall Street, in the City of
London, Engineer, and ROBERT STEERS, of No. 24, Manor Road, Walworth, in the
County of Surrey, Gentleman. "IMPROVEMENTS IN MACHINERY FOR THE MANU-
FACTURE OF SCREW HEADS."
Now
In the Specification of a foriner Patent granted to one of us, the said Robert
Steers, the 12th day of April 1875, No. 1326, for "Improvements in Serew Heads
and in Drivers or Tools for the same," is described a screw having a six-sided
tapering aperture or recess formed in the centre of its head, so that a driver or tool
similarly shaped can be inserted to screw up or unscrew, as the case may be.
our Invention relates to machinery for making such recesses in screw heads. For
this purpose we first drill a tapering or stepped hole in the screw blank by means of
a machine, in which the blank is presented to the drill and held in position whilst
being drilled by and between a set of recessed blocks having projections so formed
and arranged that the projections of the several blocks constituting a set, when held
together by a suitable ring, form at each side a sort of compound trunnion, which
rests in a bearing, and on which the set of blocks can be rotated. In conjunction
with the blocks is arranged a wedging or tightening device, by one movement of
which the blocks are caused to grip the blank to be drilled; by another movement
they are released, so as to allow of the drilled blank dropping out after the drilling
operation. Having drilled the blanks, we complete the formation of the tapered six-
sided aperture or recess by the use of a reciprocating punch in conjunction with a
holding device composed of a couple of discs or plates arranged on a common axis or
shaft, one disc or plate being fixed on the said axis or shaft, whilst the other is free
to move endwise thereon, though not to rotate independently thereof. The two discs
or plates are near their peripheries recessed on their inner sides or faces at intervals
to receive and hold the blank between them, and the disc or plate fixed on the axis
or shaft is formed or provided with a peculiar star-shaped cam or recess, in gear
with which is a pin or projection travelling with the punch carrier, which carrier
also operates a wedge.
The blank to be operated upon is dropped into position between the discs or
plates, and as they rotate towards the punch the wedge tightens them upon the
blank;
then the rotary movement temporarily ceases; the punch enters the opening
in the blauk, completes the formation of the tapered six-sided recess, and afterwards

page_text: recedes; as it recedes the wedge is withdrawn, so as to release the loose disc or
plate, which by springs arranged between the two dises or plates is moved away
from the fixed disc or plate, and on the further rotary movement of the discs or
plates the blank with its completed head falls out.
In some cases, for example in the manufacture of machine screws, the preliminary
drilling operation herein-before described may be dispensed with, the recess being
formed whilst the blank is in a highly heated state by machinery constructed on the
principle last herein-above described.
Such being the nature of our said Invention, we proceed to describe the manner
of carrying it into practical effect, as illustrated by the accompanying Drawings,
whereof,-
Fig. 1 (Sheet 1) is a front elevation of our improved drilling machinery, as to
which we would remark that for convenience we prefer connecting together a
number of machines, which we actuate by a common driving shaft and a common
cam shaft.
Fig. 2 is a side elevation, and Fig. 3 a plan.
Fig. 4 is a separate view in side elevation of the main standard of one of the said
drilling machines as seen from the opposite side to Fig. 2.
Figs. 5 to 31 inclusive are detail views, full size.
The same letters of reference are used to denote like parts in all the views.
Referring to Figs. 1, 2, and 3, a, a, are main frames or standards of the construc-
tion shewn separately in Fig. 4; bis the main driving shaft, having its bearings in
the said frames or standards; c is a cam shaft, shewn separately in Figs. 9 and 10,
working in bearings d; this cam shaft is driven from the main shaft 6 by a pinion e,
wheel, spindle g, with worin g (shewn separately in Figs. 5 and 6), and worm
wheel (see Figs. 7 and 8). Each main standard a is provided with a double
bracket i, into which are fitted the elongated bosses ¹ of two bevil pinionsj, each
receiving motion through a bevil wheel fixed on the shaft b; within each pinion
boss is fitted a drill spindle (shewn separately in Figs. 13 and 14), prevented
from rotating independently by a feather. Between each pair of spindles & is a
plate (see Figs. 15 and 16), one forked end of which enters the annular groove k¹
of each spindle; through this plate passes a connecting rod m (Figs. 17 and 18),
whose lower end is jointed at m to the lever n. Around that portion of the rod m
situate above the plate is a spiral spring m³, surmounted by a cap m³, kept down
by a pin passing through the upper end of the rod. The lever n has its fulcrum at
n in the main standard a and bracket a¹. To the outer or free end of the lever is
jointed a depending rod o (shewn separately in Figs. 19 and 20), which rod at a
lower point has jointed to it (one at each side) two pauls o' (one of which is shewn
separately in Figs. 21 and 22) by a pin o², also shewn separately in Figs. 23 and 24.
To the lower end of the rod o is attached a weight to ensure the lever descending as
the cain shaft continues its rotation after the raising of the lever to the highest
point, as herein-after described.
Underneath each bracket i is arranged a set of recessed blocks p for holding the
screw blanks to be drilled. The construction of these blocks and their arrangement
are shown in Figs. 25 to 29 inclusive, Fig. 25 being a side elevation of one complete
set of blocks, shewing how the several blocks are held together by the rings 22 (one
of which is shewn separately in Figs. 30), and shewing also the ratchet p¹, whereof
the corresponding pawl o¹ on the depending rod o intermittently rotates the set of
blocks; Fig. 26, a plan of the complete set of blocks, shewing its two compound
trunnions and their holding rings p; Fig. 27, an elevation of the reverse side to
Fig. 25; Fig. 28, a view of one of the recessed radial faces of one of the blocks; and
Fig. 29, a side view of the same block. All the blocks composing a set are alike,
except as to the side and consequent direction of the ratchet teeth and wedges, and
the recesses are provided with steel liners or clips p³, such as shown separately in
Figs. 31, which are made to fit the recesses in the blocks and to present spaces of
such dimensions as to suit the sizes of blanks to be operated upon.
The compound trunnions turn in bearings a", and the ratchet of each set of blocks

page_text: is so arranged relatively to its pawl that when the lever n has reached its highest
position the axis of one of the radial recesses will be truly in line with the axis of
the corresponding drill spindle, and the two inclined planes situate at the respective
sides of the said recess will be in position to receive the inclined recess n of the
lever as that lever descends, so that the inclined sides of the said recess will tighten
the two uppermost blocks of the set against the blank, thus holding it firmly during
the drilling operation.
It will be understood that each lever in the arrangement shewn operates.in this
way upon two sets of blocks p simultaneously.
The process of drilling a screw blank by means of this improved machinery is as
follows-Referring to Fig. 2, the set of blocks is supposed to have come to rest,
and the lever n is about to commence its descent; when it has descended and
pressed or tightened together the two upper blocks, and whilst it is holding them, a
fresh blank is inserted in the recess situate at I; during this time the blank in the
upper recess is being drilled. As the shaft c continues its rotation, the cam c¹ comes
round and lifts the lever n, and with it the drill spindle. After the lever has
partially ascended, the pawl o' comes in contact with a tooth of the ratchet p¹,
thereby as it proceeds causing the set of blocks to make a partial rotation, thus
bringing under the drill the screw blank just fed in as described. By this time the
cam c¹ has attained its highest position, and continuing its rotation allows the
lever n to descend and close the two blocks now uppermost upon the blank between
them, simultaneously bringing the drill into operation upon the blank through tho
rod m, spring m2, and plate l.
It is to be understood that the two drills and their respective sets of blocks
operate simultaneously, as first described, and that as the blanks in the uppermost
recesses are drilled, others are inserted in the recesses, as above described; also, that
the drilled blanks are carried round intermittently until they arrive at the position E,
when they fall out, and by suitable tubes are conveyed to the punching machine,
now about to be described.
Fig. 32 is a side elevation of our improved punching machine; Fig. 33 is a plan
of the same; and Figs. 34 to 47 inclusive are detail views, full size, Fig. 34 being a
side view of the main frame, with shaft bearings or bushes; Fig. 35, an end eleva-
tion; Fig. 36, a plan of the same; Fig. 37, a section in the line A, B, of Fig. 36;
Fig. 38, a section in the line C, D, of Fig. 36; and Fig. 39, a section in the line
E, F, of Fig. 36. The other views are herein-after described.
The main frame 1 carries three shafts, namely, a first motion or driving shaft 2,
an eccentric or punch shaft 3, actuated by gearing, as shewn, from the shaft 2, and
a disc shaft 4, actuated intermittently, as herein-after described. On the shaft 3 is
an eccentric 5, whose strap 6 has jointed to it a bar 7, which we call the punch
carrier; this punch carrier is recessed at 8 to receive the stem of a punch (corre-
sponding in external form to the recess to be formed), and is formed with two
extensions 9 and 10. The extension 9 is formed with two parallel portions 11 and
12, joined by an inclined part 13 acting as a wedge, as herein-after described. The
extension 10 is formed with a cylindrical projection or stud 14, gearing with the
cam groove 15 of the disc 16, shewn most clearly in Fig. 46; this disc is fixed on
the shaft 4, and on the same shaft is another disc 17. The juxtaposed faces of these
two discs are recessed, as shewn at 18, in Figs. 44 and 45. The disc 17 is feathered
on the shaft 4, so that it may move along the shaft, but cannot rotate independently
of it. The two discs are normally kept a short distance apart by spiral springs 19
(see Fig. 47) interposed between them. The recesses 18 are provided with steel
liners or clips resembling those shewn in Figs. 31. The bearings or bushes of the
shafts 3 and 4 are made adjustable to provide for wear; to this end the said bushes
have inclined faces 20, against which bear the correspondingly inclined faces of
bolts 21; one of the adjusting bolts of the bearings of the shaft 3 is shewn sepa-
rately in Figs. 40 and 41.
The action of this improved punching machine is as follows:-In Figs. 32 and 33
the machine is supposed to be in operation, a blank having been punched and

page_text: another placed in the recess, which was then at I (Fig. 32), the punch bar retired
releasing the disc 17, which has therefore been forced from the disc 16 by the inter-
posed springs, and the stud or projection 14 of the punch carrier acting in the cam
groove 15 has partially rotated the discs 16 and 17 in the direction of the arrow,
Fig. 32; during the return stroke of the punch carrier the discs 16 and 17 make a
further partial rotation in the same direction, bringing the axis of the blank that
was inserted at I into line with the axis of the punch; thereupon the rotary move-
ment of the disc ceases; during the continued forward motion of the punch carrier
its incline 13 pushes the disc 17 towards the disc 10, thus tightening the steel liners
or clips in the said dises upon the screw blanks about to be punched; the punch then
enters the hole previously drilled in the said blank and forms the desired recess, a
fresh blank being meanwhile inserted at I; the punch then retires, the discs make
a further partial rotation, and so on, the operation being repeated as before. As the
recesses reach the lowest part (E, Fig. 32) in the rotation of the discs, the recessed
blanks fall out.
Punching machinery such as we have just described may be used to form recesses
in blanks whose heads have been made by pressure in dies in such manner that the
fibre of the iron has not been disintegrated; and in recessing such blanks the pre-
vious drilling or heating may be in some cases dispensed with.
Having described the nature of our said Invention, and explained the manner of
carrying the same into practical effect, we desire to have it understood that we do
not intend to claim any of the mechanical parts of the apparatus herein-before shewn
and described when taken separately and apart from the combination or application
thereof as herein described, but what we consider to be novel and original and
therefore claim as secured to us by the herein-before in part recited Letters Patent
is,
First. The combination of parts constituting the improved drilling machinery,
constructed, arranged, and operating as shewn in and described with reference to
Figs. 1 to 31, both inclusive, of the accompanying Drawings.
Secondly. The combination of parts constituting the improved punching machinery,
constructed, arranged, and operating as shewn in and described with reference to
Figs. 32 to 47, both inclusive, of the accompanying Drawings.
In witness whereof, we, the said Frederick Carley Coxhead and Robert Steers,
have hereunto set our hands and seals, this Twenty-ninth day of May, in
the year of our Lord One thousand eight hundred and seventy-seven.
F. C. COXHEAD.
(L.S.)
ROBERT STEERS. (L.S.)