Reworking and sizing of flat conductor cable

A flat multiconductor cable has a reworked and sized portion in which the span tolerance (distance between the outside conductors in the cable) is substantially reduced as compared to the unsized portion of the cable. An apparatus is also disclosed for reworking and sizing a flat multiconductor cable in order to reduce the tolerances in the reworked cable. A multi contact electrical connector can be installed on the reworked portion of the cable although the same connector may not be capable of accepting the cable in its original condition because of the relatively wide dimensional tolerances in the cable.

FIELD OF THE INVENTION 
This invention relates to methods and apparatus for reworking and sizing 
flat multiconductor cables for the purpose of reducing the dimensional 
tolerances in the cable and thereby permitting an electrical connector to 
be installed on the cable. The invention is also directed to a flat 
multiconductor cable having a reworked and sized portion in which the 
dimensional tolerances have been reduced. 
BACKGROUND OF THE INVENTION 
A widely used type of electrical cable comprises a plurality of parallel 
coplanar conductors in spaced-apart relationship which are embedded in 
plastic insulating material. Electrical connections to the conductors in 
the cable are made by installing a multi contact electrical connector on 
the cable, the connector having a cable-receiving face and having 
terminals extending from the cable-receiving face. The terminals have 
slots that receive the conductors in the cable. The terminals are forced 
through the cable in a manner such that the conductors enter the slots and 
establish contact therewith. Thus, the mere installation of the connector 
on the cable also brings about electrical connections between all of the 
terminals in the connector and all of the conductors in the cable. 
Problems can arise when the connector is installed on the cable as a result 
of dimensional variations in the cable itself. The terminals in the 
connector are relatively precisely positioned and if the cable is perfect 
or nearly so (as regards the center-to-center spacing of the conductors 
and the distance between the outside conductors in the cable) one 
conductor will enter the wire-receiving slot of each of the terminals in 
the connector when the connector is installed on the cable. However, the 
cable can not be manufactured to the same precise dimensional standards as 
can the connector and the spacing between adjacent conductors in the cable 
may vary within relatively wide tolerance limits. U.S. Pat. No. 4,077,695 
explains this problem in detail and presents a solution for certain types 
of flat cable, particularly cable of the type in which each conductor is 
surrounded by a substantially cylindrical insulating sheath and each 
insulating sheath is connected to the next adjacent insulating sheath by a 
thin flexible web of plastic material. At the time the solution presented 
in the above identified U.S. Pat. No. 4,077,695 was developed, the minimum 
spacing between adjacent conductors in a flat conductor cable was 0.05 
inches (1.27 mm) and it is feasible to provide the thin connecting web 
between adjacent conducting sheaths in the cable when the spacing is 
maintained at 1.27 mm. 
Within more recent times, cable suppliers have begun to produce flat 
multiconductor cable in which adjacent conductors are spaced apart by only 
0.025 inches (0.63 mm) and it is impractical to form the cable with a thin 
web as shown in the above U.S. Pat. No. 4,077,695. Because of the close 
spacing of the conductors, it is necessary that the insulating material 
extend as an almost continuous mass with the conductors embedded in the 
insulating material and the thickness of the insulating material varies 
only slightly across the width of the cable. Furthermore, the 
manufacturing difficulties of producing this relatively fine wire cable 
result in wide tolerances in the dimension between the outside conductors 
of the cable, the span tolerance of the cable. As a result, problems can 
be encountered when it is attempted to install a connector on the cable 
for the reason that some of the conductors in the cable may not line up 
with the proper terminals in the connector when the installation is made 
and shorting between adjacent conductors can be caused if a single 
terminal in the connector contacts two conductors in the cable. 
The present invention is concerned with the reworking and sizing of flat 
conductor cable so that a connector can be installed on the reworked 
portion notwithstanding the fact that problems might be encountered in 
attempting to install the same connector on a portion of the cable which 
is not reworked and sized. The invention is further directed to the 
achievement of a method and apparatus for carrying out such reworking. 
THE INVENTION 
In accordance with one embodiment thereof, the invention comprises a 
reworking and sizing apparatus for reworking and sizing a flat 
multiconductor cable. The cable comprises a plurality of side-by-side 
spaced-apart coplanar parallel conductors which are embedded in plastic 
insulating material and which have axes which define a conductor plane. 
The cable has parallel side cable edges and oppositely-facing first and 
second major cable surfaces. Each of the cable surfaces have, in 
transverse cross section, a series of cylindrical opposed and aligned 
convex projections with a conductor centrally located in the cable with 
respect to each pair of opposed projections. The spacing between the axes 
of adjacent conductors is d.+-.x where d is the nominal spacing and x is 
the spacing tolerance. The span distance between the two outside 
conductors, which are immediately adjacent to the cable side edges, is 
(n-1)d.+-.s where n is the number of conductors and s is the span 
tolerance. The span tolerance in such cables is greater than the spacing 
tolerance. The apparatus is characterized in that it comprises first and 
second tooling members and a plurality of punches. The first and second 
tooling members have tool side edges and opposed first and second tool 
surfaces which extend between the tool side edges. The tooling members are 
movable between an open position in which they are spaced apart and a 
closed position in which they are substantially against each other. The 
first and second tool surfaces have side-by-side parallel concave 
depressions which extend parallel to the tool side edges and which conform 
to the convex projections on the cable surfaces. The center-to-center 
spacing between adjacent depressions is d and the outside depressions, 
which are adjacent to the tool side edges, are spaced apart by a distance 
substantially equal to (n-1)d. Each of the first and second tool surfaces 
has a plurality of openings extending therein with an opening between each 
adjacent pair of depressions. The punches are on the first tooling member 
and extend into the openings in the first tool surface. The punches have 
leading ends which are proximate to the first tool surface and are movable 
through the openings in the first tooling member and into the openings in 
the second tooling member. Actuating means are provided for sequentially 
moving the first and second tooling members from their open positions to 
their closed positions and for thereafter moving the punches through the 
openings in the first tooling member and into the openings in the second 
tooling member whereby upon placement of a portion of the cable between 
the first and second tool surfaces with the projections on the cable 
surfaces in approximate alignment with the depressions on the tool 
surfaces, thereafter moving the tooling members to their closed positions, 
at least some of the conductors will be moved laterally in the conductor 
plane so that each conductor will be centrally located between an opposed 
pair of depressions on the first and second tooling surfaces. Upon 
subsequent movement of the punches through the cable and into the openings 
in the second tooling member, holes will be punched in the cable between 
adjacent conductors and the span tolerance of the cable will be reduced. 
In accordance with the method aspect of the invention, a portion of a flat 
conductor cable is reworked and sized by clamping the portion of the cable 
between opposed first and second clamping surfaces which are opposed to 
the first and second cable surfaces. While clamped, at least some of the 
conductors are moved laterally in the conductor plane relative to the 
conductor axes with accompanying deformation of plastic insulating 
material which is between adjacent conductors, the movement of the 
conductors causing a reduction in the span tolerance of the cable. 
Thereafter, holes are punched in the predetermined portion of the cable 
between adjacent conductors and the plastic insulating material which has 
been deformed as a result of movement of the conductors is removed. The 
cable is then unclamped and as a result of these operations, the 
predetermined portion of the cable is sized and reworked and the span 
tolerance is reduced. 
In accordance with a further aspect, the invention comprises a flat 
multiconductor cable which has a reworked and sized portion. In this 
reworked and sized portion, the span tolerance, which is the variation due 
to manufacturing tolerances of the distance between the outside conductors 
in the cable, is substantially reduced so that an electrical connector can 
be installed on the reworked portion of the cable.

THE DISCLOSED EMBODIMENT 
Referring first to FIGS. 8 and 9, a flat conductor cable 2 of the type 
which can be reworked in accordance with the present invention comprises a 
plurality of parallel side-by-side conductors 4 embedded in plastic 
material 6. The conductors are coplanar and define a conductor plane to 
which reference will be made below. The cable has parallel side edges 8, 
and upper or first major surface 10, and a lower or second major surface 
12. 
The upper and lower surfaces 10, 12 have, in transverse cross section, a 
series of cylindrical convex projections 14, each projection having a 
conductor 4 centrally located with respect thereto. The projections on the 
two surfaces 10, 12, are opposed to, and in alignment with, each other. 
The type of cable shown has a continuous thick mass insulating material 
16. FIG. 9, between adjacent conductors rather than a thin membrane as 
with some known types of flat cable. 
FIG. 5 shows a multi contact connector 18 of a type which is installed on a 
cable to establish electrical contact with the conductors in the cable. 
The connector 18 comprises a generally prismatic housing 20 and a cover 22 
for the housing 20. The housing has a cable-receiving face 24 which is 
directed downwardly in FIG. 5 and has terminals 26 which extend from the 
face 24. The terminals shown in FIGS. 5 and 6 are the type described fully 
in U.S. application Ser. No. 704,458 filed Feb. 22, 1985, now U.S. Pat. 
No. 4,600,259. FIG. 13 shows an alternative type of terminal which is 
commonly used in connector housings of the general type shown in FIGS. 5 
and 6. The terminals are usually arranged in two or more parallel rows 
which extend between the endwalls of the connector with the terminals in 
one row staggered with respect to the terminals in the other row. The 
terminals have free ends 30 which are spaced from the cable-receiving face 
24 and wire-receiving slots 28 which extend inwardly from the free end. 
Electrical contact is established by forcing a conductor into a slot so 
that the opposed surfaces of the slot contact the conductor. The upper 
face 32 of the housing 20 has terminal posts 34 extending therefrom which 
are integral with the lower portions 26 of the terminals. 
The cover 22 has a surface 36 which is opposed to the cable-receiving 
surface 24 of the housing and has side-by-side concave depressions 38 in 
the surface 36. These concave depressions have substantially the same 
radius of curvature as do the convex cylindrical projections 14 on the 
cable so that the depressions conform to the surface of the cable. 
Openings 40 extend through the cover so that the leading ends 30 of the 
terminals can be passed through these openings when the connector is 
installed on the cable. The cover is secured to the housing by means of 
latch arms 42 at each end of the cover. 
When a connector as shown in FIG. 5 is to be installed on a cable 2, it is 
merely necessary to position the cable on the cover member with the 
projections on the lower surface of the cable received in the depressions 
38 of the cover. Thereafter, the cover and the housing are assembled to 
each other in a manner such that the terminals move through the cable and 
the individual conductors move into the wire-receiving slots of the 
terminals. 
The assembly procedure briefly described above requires that each of the 
conductors 4 in the cable be in substantial alignment with the 
wire-receiving slot of a terminal to which it is to be connected. If the 
cable is dimensionally perfect, the installation of the connector on the 
cable will proceed as described above. However, all manufactured articles 
have dimensional tolerances; that is to say the dimensions of the article 
are not absolute but rather lie within specified limits. Thus, cable as 
shown at 2 may have a nominal center-to-center spacing d between adjacent 
conductors 4 of 0.05 inches plus or minus (.+-.) a dimensional tolerance 
x. In the case of a cable having conductors on 0.050 centers, this 
tolerance, x, is commonly about 0.003 inches. 
The span of a cable of the type shown at 2 is regarded as the distance 
between the outside conductors, that is the conductors 4 which are 
immediately adjacent to the side edges 8. The span is equal to (n-1)d.+-.s 
where n is the number of conductors in the cable and s is the span 
tolerance. The span tolerance s of a cable 2 is greater by a significant 
amount than the spacing tolerance x for the reason that the variations in 
the positions of the conductors as a result of the spacing tolerance do 
not always cancel each other out and the manufacturers of cables therefor 
establish a span tolerance, s, which is substantially greater than the 
spacing tolerance x. 
The finest or highest density cable presently available (the cable having 
the closest spacing and the smallest conductors) has a nominal spacing d 
between adjacent conductors 4 of 0.025 inches (0.63 mm) with a spacing 
tolerance x of .+-.0.002 inches. The span tolerance s for this type of 
cable is .+-.0.008 inches for a cable having no more than sixty conductors 
therein and is .+-.0.015 inches for a cable having over sixty conductors 
therein. These tolerances are relatively wide and result from the fact 
that it is impossible to make the cable with a higher degree of 
dimensional precision. 
FIG. 13 illustrates the problems which can arise when a connector is 
installed on a cable 2 in accordance with present known practice. In FIG. 
13, it is assumed that the cable is within the span tolerance but close to 
the limit on the minus side. Also in FIG. 13, the terminals 44 are of the 
well-known type which comprise a flat plate-like member having a 
wire-receiving slot 46 therein. The free ends of the terminal are pointed 
as shown at 48 so that the terminal will pierce the insulation as it must 
do when the connector housing is moved relatively downwardly from the 
position shown in FIG. 13. 
It can be seen that the conductor 4c in FIG. 13, which is assumed to be the 
center conductor in the cable midway between the side edges, is in 
alignment with its depression 38. However, the conductor 4e on the 
lift-hand end of the cable is not in alignment with its associated 
depression 38; rather, the cylindrical projection associated with 
conductor 4e is against the ridge or cusp which is between two 
depressions. Similarly, those conductors which are adjacent to conductor 
4e are not in alignment with their associated depressions 38 but are 
rather offset from them. The terminals 44, however, are positioned with a 
very high degree of precision on the connector housing and they are in 
alignment with their associated depressions 38 on the cover member. It 
should be explained that parts such as molded housings and covers for 
connectors can be produced with a very high degree of dimensional 
precision as compared with cables which aree manufactured by extruding 
insulation on wires. 
If the connector housing were to be moved relatively downwardly from the 
position of FIG. 13 and assembled to the connector cover, it is apparrent 
that the left-hand terminal in the foreground in FIG. 13 would contact not 
only the second conductor from the side, conductor 4e.sub.1, but will also 
contact conductor 4e. This would result in the two conductors being 
shorted or connected to each other and is, of course, a totally; 
unacceptable situation. The possibility of shorting is paticularly strong 
if the conductors are stranded wire rather than solid wire. 
FIG. 13 thus demonstrates that serious problems can be encountered when a 
cable is connected to terminals in a connector even if the cable is within 
its dimensional tolerance limits, particularly its span tolerance, these 
problems result from the fact that there is simply a limit to the 
precision with which such cables can be manuffactured. 
In accordance with the present invention, the cable is reworked and size as 
shown in FIGS. 10-12. In FIG. 10, the cable 2 has a reworked portion 50 
which is adjacent to its end 51. In the reworked portion 50, holes 52 are 
provided between adjacent conductors, these holes having been produced by 
punching as described below so that some of the plastic material is 
removed from the cable and the sides 54 of the holes are opposed and 
substantially parallel to each other, see FIG. 12. In addition, the side 
edge 8 is notched as shown at 56. 
In the reworked portion 50, FIG. 10, several of the conductors shown on the 
left have been displaced laterally in the conductor plane with respect to 
their axes as evidenced by the curvature in the axis of each conductor 
adjacent to the reworked section 50. This lateral displacement of the 
conductors in the reworked portion was brought about in order to reduce 
the span tolerance s of the cable and to permit it to be used with a 
connector as shown in FIG. 6. In FIG. 11, the reworked portion 50 has 
conductors which have been displaced rightwardly as viewed in this figure. 
In FIG. 10, the cable in its original condition was undersized (on the 
minus side of the tolerance limits) so that it was necessary to displace 
some of the conductors leftwardly to increase the span in the reworked 
zone. In FIG. 11, the cable in its original condition is oversized so it 
was necessary to reduce the cable span by displacing some of the 
conductors rightwardly. 
In other words, if the width of the cable as received from the manufacturer 
is (n-1)d.+-.s, the width of the cable in the reworked portion 50 is 
(n-1).+-.s' where s' is less than s. 
When the cable is reworked as shown in FIGS. 10-12, it can then be placed 
on the cover 22 of the connector as shown in FIG. 6 and each of the 
conductors will be substantially centered with relationship to its 
associated depression 38. The cylindrical surfaces of the insulating 
sheaths in the reworked portions will be against the surfaces of the 
depressions 38 so that all of the conductors will be aligned with the 
wire-receiving slots 28 of the terminals. Hence, installation of the 
connector on the cable can be carried out with ease. 
FIGS. 1-4 show the apparatus 58 which is used to rework and size the cable. 
The apparatus 58 comprises an upper tooling member 60, and a lower tooling 
member 62. These two tooling members are mounted on guideposts 64 for 
movement towards and away from each other. Tooling member 60 has a 
downwardly facing first tooling surface 61 and tooling member 62 has an 
upwardly facing second surface 63. Concave cylindrical depressions 66 are 
provided in the surface 61 and are opposed to identical concave 
depressions 68 in the surface 63, these depressions extending parallel to 
the tool side edges 65, 67 of the tooling members. Openings 70 and 72 
extend through the tooling members 60 and 62 respectively between adjacent 
depressions. These openings are relatively narrow and are dimensioned to 
receive punches 82 on a punch holder 80 in a manner described below. 
Additionally, openings 74 are provided at the ends of the row of 
depressions so that the side edges of the cable will be notched as shown 
in FIG. 10 at 56. 
The distance between adjacent depressions 66 and depressions 68 on the 
tooling members 60, 62 is substantially equal to the conductor nominal or 
"perfect" spacing in the cables with a manufacturing tolerance. However, 
the manufacturing tolerance of machined parts such as those shown at 60 
and 62 is extremely low as compared to the tolerances in the cable and for 
purposes of the present description, the machining tolerances can be 
disregarded. 
A recess 76 extends into the upper surface 78 of the tooling member 60 and 
is dimensioned to receive a punch holder 80 from which the previously 
identified punches 82 extend. These punches have free ends 84 which are 
spaced from the punch holder and which are received in the openings 70 of 
the tooling member 60. 
The punch holder 80 is secured by fasteners 88 to a crosshead or actuator 
bar 86 which has openings for reception of the upper ends of the 
guideposts 64. A lost motion coupling is provided between the crosshead 
and the tooling member 60 by means of rods 90 having enlarged heads which 
are received in recesses in the crosshead and which have threaded ends 
which are threaded into the tooling member 60. A spring 92 surrounds the 
shank portion 90 of each rod so that the tooling member 60 and the 
crosshead 80 can be moved relatively towards each other with the 
accompanying compression of the springs 92. 
The upper tooling member 60 functions as a pressure pad in that it clamps 
the cable as will be described below and it is desirable to provide set 
screws 94 to serve as stops to limit downward movement of the tooling 
member 60 towards the tooling member 62. 
If desired, a shearing edge 96 can be provided on the punch holder 80 which 
is cooperable with one edge 98 of the lower tooling member 62 so that when 
the sizing operation is carried out, the end portion of the cable will be 
trimmed. 
The use of the apparatus is illustrated in FIGS. 2-4. Normally, the parts 
are in the positions of FIG. 2 with the pressure pad or upper tooling 
member 60 spaced from the lower tooling member 62. The cable is first 
positioned between the two tooling members with the cylindrical 
projections 14 in the depressions 68 on the lower tooling member 62. 
Thereafter the crosshead 80 is moved downwardly by a suitable press ram or 
the like until the cable is clamped between the opposed surfaces 61 and 
63. At this stage, the punch holder 80 will not have moved through the 
pressure pad or upper tooling member 60 and the free ends 84 of the 
punches will be adjacent to the surface 61 as also shown in FIG. 3. Upon 
further downward movement of the crosshead, the springs 92 are compressed 
and the punches moved downwardly through the cable and into the openings 
72 in the lower tooling member. During such movement, the material 16 
between adjacent conductors in the cable is punched out or removed, 
leaving the openings 52 between adjacent conductors. 
It will be apparent from FIGS. 2-4 that if the cable is manufactured within 
its tolerance limits but is on either the plus or minus side as regards 
its span tolerance, the individual conductors will be moved laterally in 
the conductor plane as the pressure pad moves downwardly. Such lateral 
movement of the conductors is brought about by virtue of the fact that the 
surfaces of the depressions in the tooling members engage the convex 
projections on the cable and cause them to move leftwardly or rightwardly 
as required and thereby displace the conductors until the conductors are 
gripped and located between the opposed depressions of the tooling 
members. 
During such compression of the cable, and lateral movement of the 
conductors, the plastic material 16 which is between adjacent conductors 
will be elastically compressed or stretched (depending upon the direction 
of movement of the conductors). It is therefore necessary to remove this 
material by the punching operation so that it does not cause the 
conductors to return to their normal positions when the cable is removed 
from between the clamping surfaces of the tooling members. 
The salient advantage of the invention is, of course, that the cable need 
not be manufactured to exacting physical dimensions in order for it to be 
suitable for use with an electrical connector. The reworking and sizing of 
the cable compensates for any dimensional variations in the cable as a 
result of manufacturing tolerances and a small portion of the cable is 
reworked so that the conductors in that portion of the cable are 
relatively precisely located. 
An added advantage of the invention can be appreciated if FIG. 13 is 
compared with FIG. 6. In accordance with the prior art practice, FIG. 13, 
it is necessary to provide pointed ends 48 on the terminals 44 and to 
drive these terminals through the rather heavy insulating material of the 
cable. This means that substantial force is required to install a 
connector on the cable if terminals as shown in FIG. 13 are used on cable 
which has not been prepared and reworked in accordance with the present 
invention. On the other hand, it can be appreciated from an inspection of 
FIG. 6 that the individual terminals 26 can be moved downwardly with 
relative ease and the rounded leading ends 30 will slip smoothly into the 
openings in the cable while the conductors of the cable will move into the 
wire-receiving slots 28. Installation of the connector on the cable thus 
becomes a less arduous task than is the case with prior art devices. 
An additional advantage acheived in the practice of the invention is that 
the width of the terminals as viewed in FIGS. 6 and 13 can be increased. 
Clearly, the relative widths of the terminals shown in FIG. 13 could not 
be increased beyond that shown without increasing the already present 
possibility of shorting between adjacent conductors as explained above. 
However, when the cable has been reworked and terminals having rounded 
ends 30 are used, there is no danger of shorting even if the terminals 26 
are made wider than the terminals 44 shown in FIG. 13. This advantage is 
important in view of the small size of the terminals; the prior art 
terminals 44 will be inherently weaker than the terminals 26 and will be 
subject to damage. 
It should be mentioned that the reworked and sized cable will not be 
dimensionally pefect and will have a centerline tolerance which is 
significantly less than the tolerance of the cable in its manufactured 
condition. Therefore, the conductors 4 in FIG. 6 will not be perfectly 
aligned with the depressions 38. However, the rounded ends 30 of the 
terminals will move the conductors into substantially perfectly centered 
positions in the depressions 38 while the conductors are moving into the 
slots 28.