Wire coiling machine fluid cutoff

Wire coil cutoff apparatus for a wire coiling machine that forms an axially advancing, rotational, helical wire coil, the advancing coil being momentarily biased into indexing engagement with the cutter blade by pneumatic pressure, and the indexed blade then being shifted into cutoff relation with the coil while the pressure is still applied.

BACKGROUND OF THE INVENTION 
This invention relates to cutoff mechanism for a wire coiling machine. 
Coiling machines employed to continuously form fine wire into wire coil, as 
for electrical resistance elements, typically have employed a flying 
cutter blade to repeatedly sever segments from the forming coil. Although 
these have been in various forms, basically the concept involved was to 
first shift the cutting edge into light engagement with the coil turns for 
indexing, and then further shifting the blade to sever the indexed coil 
segment. In performing this operation, a key factor was to minimize damage 
to the coil and achieve a clean cut with minimal cross sectional area on 
the severed ends of the wire. 
Several years ago, the inventor herein developed an improved cutoff 
mechanism which allowed the cutter to mechanically index with a lightly 
powered shift of the blade against the coil at the face of the die, 
followed by wire cutoff with a highly powered further shift of the blade 
across the coil. This apparatus, set forth in U.S. Pat. No. 3,370,495, 
performed considerably better than prior devices, such that the sensitive 
index allowed cleaner cutoff in many instances. 
In modern production practice, however, the nature of the coil diameter, 
the wire diameter, and the coiling speeds employed are such that the 
complexities caused by attempting to index the wire with known apparatus, 
even that in the above noted patent, are too great. The indexing mechanism 
sometimes does not meet and usually does not hold the required 
sensitivity, causing a constant problem for maintenance personnel. If the 
pressure is not quite enough, proper indexing is not achieved. If the 
blade, in its indexing shift, moves even 0.001 or 0.002 of an inch too 
much, too much pressure is brought to bear on the delicate, fast-moving 
coil which is pushed against the side of the die opposite the blade, 
causing the coil to slow down and swell at this area, thereby rendering 
the coil useless. It is also desirable to attain and maintain accurate and 
sensitive indexing for only a very short time interval of blade engagement 
with the coil. If the blade is retained in indexing engagement for longer 
time intervals, the rotational speed of the spinning coil is retarded at 
the blade and die, again causing the coil diameter in this area to swell, 
thereby rendering the coil useless for uniform electrical resistance as in 
appliances. I.e., the coil portion is then scrap. 
Since maintenance personnel are often unable to maintain necessary cutter 
index sensitivity, the prevailing practice is to forego attempts to index 
altogether. Instead, the machine is set to simply chop off the wire 
without indexing, hoping that the wire will be clean-cut. This, however, 
requires subsequent visual inspection of the individual coil ends, and 
hand nipping of many of them to a clean-cut condition. 
To fully realize the problem the industry has in obtaining clean-cut coil 
ends, it should be understood that well over half of all production is 
so-called close or tight coiled, which is the most difficult form for 
accurate indexing and clean cutting. One technique which is employed to 
assist in this operation is to cause the cutter die to be made with the 
hole through the die at the same angle as the index angle of the coil 
turns, so that the cutter blade "sees" the coil as nearly parallel turns 
of wire. This improves the odds of the blade entering the coil between 
turns, to cause a cleaner cut. However, the results are still far from 
satisfactory and require subsequent visual inspection and manual trimming 
of the individual segments. 
SUMMARY OF THE INVENTION 
This invention provides novel indexing and cutting for the spinning wire 
coil being formed. The cutter is not shifted to the coil for indexing. 
Rather, the coil is specially pneumatically shifted momentarily to the 
cutter blade by the application of a pneumatic pressure differential 
across the coil, preferably from an air jet directed against the opposite 
side of the coil from the blade. This lightly retains the coil screwing 
past the blade edge for a very short index time, e.g. about two tenths of 
a second. The blade is then shifted in the opposite direction, i.e. toward 
the air jet, to cut the indexed coil segment clean, with the air jet 
continuing to maintain the coil against the blade during this blade 
shifting and cutting operation. 
It has been determined through repeat experimentation that there are no 
critical adjustments to be set or maintained using this invention. 
Further, there is no coil swelling or slowing at the blade and die area 
when employing this air indexing, and air assist cutoff. The coil is not 
forced into engagement with the side of the die during indexing. 
The die for the unit can be and preferably is specially cone-shaped inside 
so that the entire cutter can be conveniently rotated to match any coil 
helix angle while the coil continues to travel horizontally. It is no 
longer necessary to know the exact actual helix angle of the coil since 
the operator can simply rotate the entire cutter in one direction until 
the flat cutting face of the cone die is visually aligned with the wire 
turns on the front side of the coil, and then, after this angle is noted, 
the die is rotated this same amount past center in the opposite direction, 
aligning the blade with the wire turns on the rear side of the coil. 
The invention enables high speed, sensitive, accurate, momentary indexing 
of continuously formed helical coils, with minimal set up efforts, 
achieving dependable operation. 
These and other features, objects, and advantages of the apparatus will be 
readily apparent from a review of the detailed description hereinafter, in 
conjunction with the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now specifically to the drawings, the complete assembly 10 there 
depicted includes a wire coiling machine 12 of which only a minor portion 
is depicted and which may be of the type for example set forth in U.S. 
Pat. No. 3,401,557, entitled WIRE COILING MACHINE, issued Sept. 17, 1968 
to the inventor herein, and the disclosure of which is incorporated by 
reference herein. Alternatively, a machine such as that in U.S. Pat. No. 
3,082,810 may be employed, for example. Mounted on the discharge end of 
this wire coiling machine so as to act upon a continuously produced, 
spinning, helical wire coil advancing axially from the coiling machine is 
the novel wire coil cutoff apparatus 14 for severing the advancing wire 
coil into predetermined length segments. 
This cutoff apparatus 14 includes a main support housing 16 adapted to be 
mounted adjacent the discharge end of the wire coiling machine 12, the 
long dimension of this housing being generally transverse to the axis of 
the spinning wire coil C emitted from the wire coiling machine. Housing 16 
is supported in cantilever fashion by having one annular end flange 
retained within a mounting bearing ring 16'. Ring 16' is attached by 
fasteners 21 to a back plate 23 which is supported on a vertical pivot 
column 17 pivotally supported on a bearing block device 19. This pivotal 
arrangement allows the cutoff die to advance a limited amount with the 
coil, as set forth more specifically hereinafter. Housing 16 supports a 
die 18 on the opposite end from the pivot column. The die has a frusto 
conically-shaped through passage 20 with a larger diameter inlet and a 
smaller diameter outlet. The outlet is at a face 18' of the die across 
which a transversely shiftable cutoff knife or blade 22 moves. Blade 22 is 
shiftable from a first position with its edge just protruding into the die 
opening in chordal arrangement, across the outlet opening 20' for severing 
the wire coil C. 
This blade 22, retained in a slide guide 24, is mounted on the end of a 
plunger 26 reciprocably actuable in a forward thrust by attachment to the 
piston of a fluid cylinder 29. Cylinder 29 is retained between ring 16' 
and plate 23. The blade and plunger are retractable by a return coil 
spring 30. Outlet opening 20' of die 18 is larger than the diameter of the 
coil C to be passing therethrough. The coil advances in the direction 
indicated by the arrow in FIG. 3 while rotating, typically at rates of 
about 5,000 rpm. 
In FIGS. 3-6 is shown the details of the first form of the novel apparatus. 
Into the end of housing 16 is a fluid connector 26 attached to a 
compressed air line 28 to communicate with a passage 30 having a 
restricted outlet orifice 30'. Orifice 30' projects into the frusto 
conical die opening 20 near the die outlet 20', on the opposite side of 
coil C from the blade 22. The orifice is directed toward the coil, i.e. 
normal to the die passage. The spinning coil will normally tend to 
approach the side of the die passage opposite the blade. A timer 
controlled valve (not shown) on conduit 28 enables compressed air to be 
jetted from outlet 30' against the coil for a very short predetermined 
time interval of approximately 0.2 seconds, causing coil C to be shifted 
laterally slightly to cause it to engage the sharp edge of blade 22, i.e 
so that the blade edge engages the helical groove between the coil turns, 
thereby indexing the blade with the coil. Then, with the air bias still 
being applied, the blade is shifted in the opposite direction from the air 
bias pressure, across opening 20' of die 18, to sever the coil at the wall 
of the die opposite the blade. By so doing, a predetermined length coil is 
formed. 
In FIGS. 7-10 are shown the details of a modification of the apparatus, 
employing fluid pressure for the biasing function during indexing and 
cutoff, but, instead of the air acting directly upon the surface of the 
coil, it shifts a floating pin or plunger which in turn engages the 
surface of the coil opposite the cutoff blade to bias the coil into 
indexing relationship with the blade and retain it in a biased condition 
during the blade shifting in the opposite direction for cutoff. This is 
particularly advantageous where the coil is of a stiff wire which does not 
readily flex or bend under the direct air jet biasing force into indexing 
relation. It is also advantageous with a coil having an open type 
construction as opposed to a closed coil, because of the lack of 
sufficient wire surface area for the air jet to engage due to the spaces 
between the turns. 
This modified apparatus includes the same housing 16, blade 22, and air 
line connector 26, but a modified die 118 having a pin or plunger 130 
slidably engaged in the die in communication with the air inlet line to 
shift in response thereto. It projects into the frusto conical passage 120 
adjacent the outlet end thereof so as to engage the coil C' on the side 
opposite the blade. 
The spinning of the coil, e.g. in a right-hand direction, causes the coil 
to inherently approach the side of the die passage adjacent this plunger 
or pin, i.e. opposite the side from blade 22. At a predetermined time, 
pressure in the passage causes plunger 130 to be slidably shifted axially 
transverse to the axis of the coil C' into engagement with the coil, 
biasing the coil to a shifted condition in engagement with the sharp edge 
of cutoff blade 22 for indexing. Subsequently, after a fraction of a 
second, e.g. about 0.2 seconds, blade 22 is shifted while biasing pressure 
is still applied by plunger 130 to keep the coil in engagement with the 
blade, the shifting blade causing the coil to be severed at the face of 
the die, followed by retraction of the blade. 
Housing 16 is angularly adjustable by reason of the rotational arrangement 
of its flange in ring 16'. This allows the angle of the cutoff blade to 
match the angle of the coil helix. This angle is set using indicia which 
include a mark 25 on housing 16 (FIG. 1, 11, and 12) and a series of 
cooperative marks 27 on ring 16'. To set the angle of blade 22 and the 
cooperative flat face of die 18, the housing is first rotated in one 
arcuate direction until the blade and die face are aligned with the outer 
readily visible side of the coil (i.e. opposite that side which is 
actually adjacent the blade) then the angle indicia is noted, and the 
housing die and blade are rotated the same amount, in the opposite past 
the zero mark so that the back side of the coil is aligned with the blade. 
The frusto conically-shaped die orifice enables this shift to occur readily 
without the die causing bending of the coil, as can be noted from FIGS. 11 
and 12. 
The novel apparatus has exhibited excellent performance characteristics. It 
is basically quite simple, once understood, and in fact this is one of its 
most admirable attributes.