Improvements in Tack Machines.
Year: 1895

page_text: Date of Application, 10th Dec., 1895-Accepted, 18th Jan., 1896
COMPLETE SPECIFICATION.
Improvements in Tack Machines.
I CYRUS DEXTER HUNT, of corner of Union and Walnut Streets, Fairhaven
in the County of Bristol and State of Massachusetts United States of America,
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 :-
The object of my invention is to so construct a tack machine that it can be run
at high speed and secure the following results; good feeding of the plate; the
following of its cam by the gripping lever; diminution of the wear of the leader
knife.
My improvements consist principally in the form of the lazy cam; the form of
the gripping cam; the centreing of the gripping lever.
Reference is to be had to the accompanying drawings forming a part of this
Specification, in which similar letters of reference indicate corresponding parts in
all the figures.
Figure 1 is a side elevation of the improvement ;
Figure 2 is a plan view of the same;
Figure 3 is a front elevation of the same;
Figures 34, 3 and 3° are details showing the relation between the movements
of the blank plate with feeder and the cutting knives, both in the present invention
and in the old machine;
Figure 4 is an enlarged sectional side elevation of the driving shaft, showing the
cam for operating the gripping lever and the lines describing the same;
Figure 5 is a similar view of the driving shaft, showing the cams for the leader
knife and the lazy knife; and
Figures 6, 7, 8 and 9 are reduced sectional side elevations of the machine,
showing the working parts in different positions.
The improved tack machine is provided with a suitably constructed frame A,
supporting at its front end a bed B, having a pocket containing the bed knife C,
resting on top of the bed die D, the said knife and die being securely held in place
by set screws in the usual manner.
The front cutting edge of the bed knife C operates in conjunction with the
leader knife E and the lazy knife E', both made straight and having their adjacent
edges fitting one on the other, as is plainly illustrated in Figure 3. The bed
die D operates in conjunction with the gripping die F, in the manuer hereinafter
more fully described.
The leader knife E and the lazy knife E' are fastened by clamps G and G¹
respectively, to the front or free ends of the levers H and H₁ respectively, hung on
centres H and H³ respectively, carried in the rear of the frame A, as is plainly
illustrated in the drawings. The levers H, H' are provided with straight cam plate
surfaces H and H, formed or secured on the tops of the free ends of the said
levers Hand H¹.
The cam plate surfaces H and H' engage the under side of cams I and II,
secured ou or formed integrally with the cam shaft J, mounted to turn in suitable
bearings in the upper front part of the frame A, the said shaft J being provided
with pulleys J¹, or other suitable mechanism connected with suitable machinery for
imparting a rotary motion to the said shaft in the direction of the arrow a³, see
Figures 6, 7, 8 and 9.
:

page_text: Springs K and K' secured in the rear part of the frame A, engage the levers H
and H¹, so as to press the latter upward, and hold the same with their cam
surfaces Hand H in contact with the cams I and I. The gripping die F is held
in a pocket in the bed L₁ of the tripping lever L, pivoted at L in the lower part
of the frame A, the gripping lever being provided at one side with an upwardly-
extending arm L engaging the front of a cam N, formed or secured on the
shaft J. A spring K2 held on the frame A pulls on the arm L³, so as to hold the
cam surface L of the latter in contact with the cam N.
On the frame A is supported the arm O, Figure 3, extending transversely to the
bed B. This arm supports a springs which pinches and holds the blank b
(Figure 3) after it is cut off, between said spring and the leader knife E, as is
well known, so as to hold the blank cut from the metal plate by the knives E
and E', until the gripping die F clamps the cut-off blank in position on the bed
die D.
As heretofore constructed, the leader knife E and lazy knife E¹ both descend
together and cut the blank as one knife, both remaining down while the feeder is
turning over the plate, the lazy knife remaining stationary when down, while
the leader knife descends lower and carries the blank clamped between it and
the spring, to range of engagement with the gripping dies to which it is then
delivered.
The operation of the invention is as follows;
When the main cam shaft J is rotated in the direction of the arrow a¹ (Figures 6
to 9) the cams I and I¹ impart a downward swinging motion to the levers H
and H, and a return movement of the said levers is produced by the springs K
and K. A forward and backward swinging motion is given the gripping lever L
during each revolution of the cam shaft J, so that all the levers operate in unison.
When the several parts are in the starting position, as illustrated in Figure 6, the
leader knife E and the lazy knife E' are in an uppermost position, that is, their
cutting edges are above the cutting edge of the bed knife C, to permit of feeding
the metal plate between the knives E and E' and the bed knife C. At the same
time, the gripping die F is in a forward position, and on the point of receding on
the further movement of the cam shaft J in the direction of the arrow a¹.
Now, during the first quarter revolution of the cam shaft J, beginning in
Figure 6 and ending in Figure 7, the two cams I and I¹ move the levers H and H
simultaneously and uniformly downward, to cause the knives E and E' to move
simultaneously together and to cat a blank off the metal plate, the cutting being
completed at the end of the quarter movement of the shaft. The cams I and I¹
during this quarter movement are in contact with the levers H and H¹ from the
points a to c, see Figure 5, the point & indicating the commencement of the cutting,
and the point e indicating the end of the cut. During the next half revolution,
(beginning in Figure 7, continuing in Figure 8, and ending in Figure 9) the cam I'
permits the lever H¹ and lazy knife E' carried thereby, to return, while the leader
knife E moves still further downward (see intermediate position Figure 8) owing
to the shape of the cams I and I', as indicated between the points c and d, see
Figure 5. During the next quarter revolution of the shaft J, beginning in
Figure 9 and ending in Figure 6, the lazy knife E' remains (in consequence of the
concentric bearing of its cam) at a standstill in its uppermost position until the
cutting edges of the knives E and E' are again in alignment, the same as at
the beginning of the revolution.
As previously stated, the gripping die F commences its return stroke at the time
the knives E and E' move downward, the arm L³ then beginning to travel on the
cam N, from the point to the point g of Figure 4 or position Figures 6 to 8; the
first are of the eccentric being of it, causes the complete return movement of
the gripping die F, Figure 7; and the second arc, the remaining of the eccentric,
causes (see Figure 8) a forward movement to take hold of the cut-off blank and to
press the same in contact with the bed die D. The die F remains in this forward
clamping position during the rest of the revolution, from g to f, Figure 4, which

page_text: is somewhat less than one-half, and the die begins its return movement at j,
Figure 4, or the position shown in Figure 6, when the knives E and El begin to
move downward at the next revolution of the shaft.
In the machines heretofore in use the two cutting levers are operated by eccentric
cams described around the same centre, really one eccentric, which impart the
necessary downward movement, to the cutting levers and knives attached to them;
but the latter portion of the eccentric operating the lazy knife was cut to a curve
concentric to the axis, whereby the lazy knife, after having cut off the blank,
remained still while the concentric arc of its cam passed over its cam plate.
The lazy knife is thus momentarily down while still, and remains down until the
leader, having carried the blank down between the dies, rises to the point where it
left the lazy knife, when the two knives rise simultaneously, being operated by
eccentrics described around the same centre.
The lazy knife being thus held down while the plate is being turned over,
interferes with the turning and feeding of the plate.
This is shown in Figure 3B, which shows the old relation of the parts where P is
the plate in process of being turned over at the time when the knives E and E' are
down. As the plate is pressed forward against the knives constantly by the weight
that feeds it between the knives, there is unavoidable friction between the rising
edge of the plate and the knives, and as the knives are rising while the opposite
edge is turning down, there is an autagonizing friction on that edge; so there is
friction between both the turning up edge of the plate and the knives, and the
turning down edge, and in the turning down movement the knives are rising with a
liability of the plate riding up with the knife, causing poor feeding. When we
consider that the turning edge of the plate travels more than two miles each ten
hours, it can be seen that the avoidance of this friction is of moment in promoting
rapid feed in tack making.
In this invention the lazy knife rises in unison with the rising side of the plate
whichever way the plate is turned,. (see Figure 3C) and when the plate P is turning
down the lazy knife E' is up and still, as seen in Figure 3. By having the face
of the lazy knife a little forward of the face of the leader; knife, the plate. presses
on the face of the lazy knife and rises simultaneously with it; thus avoiding any
friction between the rising edge of the plate and the face of the knives, as is the
case in the old machine in which the plate begins to turn while the knives are
down.
This, my first improvement, is secured by having the concentric are of the lazy
cam on the lean part instead of on the full part of the cam, and supplementing it
with two continuous arcs of two different eccentrics, which give the required move-
ment of the lazy knife in unison with the movement of the plate as it is being
turned over, and so avoid. all friction between the plate and the lazy knife.
This
return movement of the lazy knife in harmony with the rising edge of the plate
aids the turning of the plate, avoids friction between the plate and the knives, and
secures good feeding of the plate while the machine is running at high speed.
My second improvement consists in the form of the gripping lever cam.
This
In the old machine, the gripping lever cam consists of one eccentric giving the
necessary motion, and a concentric arc described around the centre of the spindle
on the full part of the cam, in order to hold the blank between the dies loug
enough to be headed and to permit the header to leave the head it has formed, to
avoid the breaking of the dies by the gripping die starting too soon.
concentric arc of the cam necessarily requires nearly one half of the cam, ✿, leaving
but little more than one half of the cam, 1, as an eccentric to give the necessary
movement to the gripping die to permit the tack to drop out, and the blank to pass
down between the dies when carried down by the leader knife. In rapid running
the gripping lever will not follow or remain in contact with its cam, but will thump,
due to the rapid pitch of this cam to the centre of the spindle.
.
By my improved form of the gripping cam the time of the travel of the gripping
lever on the cam toward the centre of the spindle is prolonged, and its movement

page_text: rendered more gradual and the travel of the gripping lever is reduced, and yet we
get the necessary space between the dies when the blank is carried down between
them.
This diminished travel of the gripping lever, with the necessary space between
the dies, is secured by the cam having two eccentrics, instead of one, as in the old
machine. Thus, referring to Figure 4, the eccentric of what I term the leaving
part of the cam is shown from 1 to 2, and is constructed by a radius whose centre
is at a and comprises of the eccentric. The are of the coming part of the cam,
shown from 2 to 3, comprises but of the eccentric, and is described from a centre
at y. The arc of the leaving part 1 to 2, is constructed by a shorter radius than
the arc of the coming part of the cam from 2 to 3, and embraces more than half of
the eccentric, and hence the leaving part of the cam is necessarily fuller than the
leaving part of the cam in the old machine, which is shown by dotted lines. The
are comprising the coming part of the cam is formed by a longer radius than the arc
of the leaving part, so that the gripping die does not start to come so soon as in
the old machine, thereby allowing sufficient space between the dies for the blank
to pass down between them, though the gripping die does not travel so far away
from the bed die as in the old machine.
This fullness of the gripping cam on the leaving part and diminished travel of
the gripping lever, obtained by using two eccentrics of different radii, with the arc
of the shorter radius on the leaving part, enables the gripping lever to follow its
cam when running the machine at a high rate of speed, and I secure the maximum
distance between the dies, when the blank is carried down between them, with the
minimum movement of the gripping lever.
My third improvement is the centering of the gripping lever in a line c c,
Figure 1, drawn from the bed die score at a right angle to the plane of the bed
die pocket.
By the universal rule of building tack machines, the gripping lever is centered in
a line drawn from the bed die score perpendicular to the plane of the bed piece, i.e.,
in the line p p of Figure 1. In cutting the blank, it is necessary that the moving
knives should be ground on a bevel, so that the lower surfaces of their cutting
edges will be nearly in the plane with the bed knife.. The blank, held firmly up
against the cutting edge of the leader by the bearer spring is necessarily carried
laterally its whole width across the cutting edge of the leader, by the gripping
die, a distance of over 2000 feet each day.
In the old machine, the gripping die moving in the plane of the bed piece when
it carries the blank into the bed die score, necessarily wears off the cutting edge of
the leader. By my improvement this difficulty is overcome by the direction of the
movement of the gripping die which is parallel to the cutting surface of the leader
knife, and the leader knife will run much longer than in the old machine, because
subject to much less wear on account of the direction of the movement of the
gripping die.
In the old machine the gripping die necessarily moves when gripping the blank,
at an angle with the bed die and the bed knife which rests upon it; and as a result
of this direction of movement of the gripping die, the bed die with the bed knife
resting on it is frequently crowded up from the bottom of the pocket, thereby
preventing that firm foundation for the bed knife that is necessary to secure good
cutting of the blanks.
This difficulty resulting from the bed die being crowded up is overcome by my
improvement of centering the gripping lever so the gripping die will, when in its
forward position, move in the plane of the bed die pocket, and in the line of the
uxis of the bed die while gripping the blank.
Having now particularly described and ascertained the nature of my said inven-
t'on and in what manner the same is to be performed, I declare that what I
claim is:-
:-
:
1. A tack machine, having two cams operating the two levers carrying the

page_text: leader and lazy knives, said cams being constructed and arranged as described to
secure the return movement of the lazy knife in unison with the movement of the
plate as its edge rises to turn over while the leader is moving down, substantially
as described and for the purpose set forth.
2. A tack machine, having two cams operating the two levers carrying the
leader and lazy knives, said cams being constructed and arranged as described to
maintain the lazy knife up and still, while the edge of the plate is turning down,
substantially as described and for the purpose set forth.
3. In a tack machine, the combination with the gripping lever, of its cam formed
with two continuous arcs of eccentrics constructed around different centres, having
the arc of the leaving part longer and fuller than the arc of the coming part,
substantially as described and for the purpose set forth.
4. In a tack machine, the combination with the bed die, of the gripping lever
centred in a line drawn from the bed die score at a right angle to the plane of the
bed die pocket, and a cam for operating said gripping lever, substantially as
described and for the purpose set forth.
5. In a tack machine, the gripping lever as described, so centered that the tangent
of its radius or are at the point of contact of the dies will coincide with the plane
of the bed die, substantially as described and for the purpose set forth.
Dated December 10th 1895
A. M. & WM. CLARK,
53 Chancery Lane, London, Chartered Patent Agents.