Electrical contact

A precision apparatus for controllably shearing a thin workpiece of material to make devices such as electrical contacts of the character having specially configured spaced apart tongues adapted to mate with plug connectors of standard design. The apparatus is designed to rigidly support the workpiece except in the precise area of the shear during the entire shearing step.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates generally to electrical contacts and to a 
method and apparatus of making the same. More particularly the invention 
concerns a precision apparatus for making electrical contacts of the 
character having specially configured spaced apart tongues adapted to mate 
with plug connectors of standard design. 
2. Description of the Prior Art 
Various methods have been suggested in the past for the high volume 
manufacture of electrical contact members. In one common prior art method 
the contact members are stamped or lanced from a suitable piece of sheet 
material and the contact tongues formed or coined as necessary. Another 
method of making electrical contacts by one or more bending operations is 
described in British Pat. No. 836,397. Still another method, wherein the 
electrical contacts are made by splitting a bar of electrically conductive 
metal longitudinally over a portion of its length to form two contact 
tongues, is described in U.S. Pat. No. 4,040,177 issued to Beeler et al. 
In one form of the aforementioned Beeler et al patent, a portion of the bar 
to be split is enclosed between two tools. The tools are then moved, 
sliding along each other perpendicular to the longitudinal dimension of 
the bar in mutually opposed directions, over a distance which is 
sufficient to produce the desired splitting. In another method of 
splitting, the bar to be split is retained over a part of its length such 
that one end is free, after which a wedge is longitudinally driven into 
the bar through this end. 
Experience has shown that in order to repeatedly produce precision 
electrical contacts by a splitting or skieving method, it is absolutely 
essential that the portions of the material immediately adjacent the 
boundaries of the split or slice be rigidly and positively constrained. 
Only in this way can a predictable controlled shear split of the material 
be achieved. The recognition of this problem and its novel solution is at 
the very heart of the present invention As will be better appreciated from 
the discussion which follows, the unique apparatus of the present 
invention, which closely constrains the starting material along the 
boundaries of the skieve or split, overcomes the basic deficiencies of the 
prior art splitting methods, including the Beeler et al method, and for 
the first time permits the low cost, large volume manufacture of very high 
quality precision electrical contacts. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a method and apparatus 
for the precise manufacture of high quality electrical contacts by means 
of a closely controlled material skieving or splitting process. More 
particularly it is an object of the invention to provide an apparatus of 
novel design for use in making the precision electrical contacts wherein 
the starting material from which the electrical contacts are made is 
closely constrained in the area of the shear boundaries so that 
predictable and precisely controlled shearing of the material can 
repeatedly be achieved. 
It is another object of the present invention to provide a method and 
apparatus for making electrical contacts of the aforementioned character 
in which material waste is minimized and manufacturing costs are kept at 
an absolute minimum. 
Another object of the invention is to provide an apparatus of the character 
described in the preceding paragraphs which is of a simple straightforward 
design requiring a minimum amount of maintenance. 
Still another object of the invention is to provide a method and apparatus 
of the character described which is easy to use by untrained workmen and 
is readily susceptible of automating to accomplish very high volume 
production rates.

DESCRIPTION OF THE INVENTION 
Referring to the drawings, and particularly to FIGS. 1, 2 and 3, one form 
of the apparatus for making an electrical contact member from a generally 
planar shaped workpiece of electrically conductive material is generally 
designated by the numeral 12. As best seen in FIG. 3, the starting 
material, or workpiece "W", used in the practice of the method of the 
present invention has first and second generally parallel faces 14 and 16 
of a predetermined area terminating in a perpendicularly extending third 
face, or edge, 18 of a predetermined width. 
The apparatus 12 comprises a die portion including a supporting body 20 
having a first, or front, face 22, a second, or top, face 24 and a bottom 
face 26 adapted to rest on a generally planar, rectangular base 28. A 
vertically extending, generally "U" shaped punch receiving channel 30 is 
formed in body member 20. As best seen in FIG. 3, channel 30 is defined by 
transversely spaced, generally parallel side walls 32 and 34 which join 
with a perpendicularly extending back, or end, wall 36. 
Closely receivable within the lower potion of channel 30 are workpiece 
supporting means for continuously rigidly supporting the first and second 
faces 14 and 16 of the workpiece "W". In the form of the invention 
illustrated in FIGS. 1 through 3, the workpiece supporting means comprises 
supporting elements 40 and 42. Elements 40 and 42 support the entire face 
14 and 16 of the workpiece save in the areas "A" and "B" which correspond 
to the cross-sectional area of transverse grooves 44 and 46 formed in the 
elements 40 and 42. Similarly, in the second form of the apparatus of the 
invention illustrated in FIG. 11, the workpiece supporting means support 
the first and second faces of the workpiece throughout the entire area of 
the first and second faces save for an area designated by the letter "C" 
in FIG. 11. Area "C" on face 14 of the workpiece "W" is of a predetermined 
width and length corresponding to the width and length of groove 44 formed 
in element 40. As indicated in FIG. 11 this first unsupported area extends 
downwardly from the third face, or edge, 18 of the workpiece "W". 
It is to be observed that in both the first and second forms of the 
apparatus of the invention, supporting element 40 is provided with a 
transversely extending channel 44 therethrough, which channel has a 
cross-sectional area substantially corresponding to the previously 
identified unsupported areas "A" and "C". As seen in FIGS. 3 and 11, 
channel 44 is defined by spaced apart parallel walls 44a and 44b which 
join with a perpendicularly extending bottom wall 44c. 
In the first form of the apparatus of the invention shown in FIGS. 1 
through 3, supporting element 42 is also provided with a transversely 
extending channel 46 which is defined by downwardly extending spaced apart 
parallel side walls 46a and 46b which join with in a perpendicularly 
extending bottom wall 46c. As indicated in FIG. 3, the cross-sectional 
area of channel 46 is equal to unsupported area "B" on face 16 of the 
workpiece "W". In the discussion which follows, it will become apparent 
that areas "A" and "B" are equal to the sheared areas, or tongues, formed 
in the workpiece depicted in FIG. 3, while area "C" is equal to the area 
of the skieved, or tongue, portion formed in the workpiece shown in FIG. 
11 and identified therein by the numeral 49. 
Referring particularly to FIG. 11, it is to be noted that the second 
supporting element, designated in this figure by the numeral 42a, does not 
have a transversely extending channel formed therein. Rather, the entire 
front face "F" of supporting element 42a provides support to the entire 
second, or rear, face 16 of the workpiece "W". 
Turning again to FIGS. 1 through 3, the apparatus of the form of the 
invention thereshown further includes shearing, or punch, means closely 
receivable within channel 30 of the supporting body 20 for reciprocal 
movement therewithin. The function of the shearing means is to impart a 
hearing force to the third face, or edge, 18 of the workpiece "W" at a 
location intermediate the first and second faces 14 and 16. The shearing 
means, shown here as punch 50, includes interconnected side walls 52 which 
terminate in a upper wall 54 and a lower wall 56. As best seen by also 
referring to FIG. 9, extending downwardly or outwardly from end wall 56 of 
the punch 50 is a cutter element 58 which has the shape of an isosceles 
triangle in longitudinal cross-section with the apex thereof terminating 
in a cutting edge 60. As indicated in FIG. 1, punch 50 is closely 
receivable within channel 30 of body 20 and is controllably movable 
downwardly in the direction of the arrow of FIG. 1. 
In both forms of the apparatus of the invention shown in the drawings, the 
workpiece clamping or supporting elements 42 and 44 are provided with 
opposing faces adapted to be brought into pressural engagement with faces 
14 and 16 respectively of the workpiece. The supporting or clamping 
elements 40 and 42 are maintained in pressural engagement with the faces 
of the workpiece "W" by means of a plurality of stacked bars 64 which are 
interconnected with face 22 of body 20. As best seen in FIGS. 3 and 10, 
each of the bars 64 is provided with spaced apart apertures 66 which 
receive threaded connectors 68, which connectors are threadably received 
within internally threaded apertures 70 formed in the forward face 22 of 
body 20. As indicated in FIG. 1, with stacked bars 64 securely affixed to 
supporting body 20 in the manner shown, punch 50 is closely receivable 
within an area defined by the rear face of stacked bars 64 and the side 
and end walls 34 and 36 of channel 30. 
Turning once again to FIG. 10, wherein a second form of the apparatus of 
the invention is shown, the punch, there designated by the numeral 50a, is 
of similar construction to punch 50 having a lower end wall 56a. Extending 
outwardly or downwardly from end wall 56a is a cutter element of slightly 
different configuration from that shown in FIGS. 3 and 9. More 
particularly, this cutter element, designated by the numeral 58a, has the 
longitudinal cross-sectional shape of a right triangle terminating at its 
apex in a cutting edge 60a. As will presently be discussed, the apparatus 
of the second form of the invention shown in FIGS. 10 and 11 is used in 
skieving, or slicing, the workpiece "W" in a predeterminable controlled 
manner to form a tongue 62 (FIG. 11). 
In practicing the method of the invention using the apparatus of the form 
of the invention shown in FIGS. 1 through 3, after the clamping bars 64 
are removed from the face of the die body 20 supporting element 42 is 
inserted into the lower portion of "U" shaped channel 30 with its base 
resting on base 28. The workpiece "W" is next inserted into the "U" shaped 
channel with face 16 thereof in surface contact with the outwardly 
extending face of supporting element 42. With the workpiece in place, 
supporting element 40 is then inserted into channel 30 of the die body so 
that the rear face thereof is in intimate contact with the front face 14 
of the workpiece "W". Next, the clamping bars 64 are interconnected with 
the front face 22 of the die body 20 by means of threaded connectors 68 so 
as to securely clamp the workpiece between elements 40 and 42. It is 
important to note that with the workpiece clamped in the die in the manner 
thus described, the first and second faces of the workpiece are firmly and 
securely supported throughout the entire area of their opposing faces save 
for the first unsupported area "A" and the second unsupported area "B" 
(FIG. 3) which are co-extensive with the cross-sectional areas of 
transversely extending grooves 44 and 46 formed in supporting elements 40 
and 42. 
With the workpiece supported within the die in the manner described in the 
preceding paragraphs, the punch 50 is then inserted into the channel 
defined by the rear faces of clamping bars 64 and the faces of the "U" 
shaped channel 30 formed in die body 20. In the embodiment of the 
invention shown in FIGS. 1 through 3, the cutting portion 58 of the punch 
50, which is in the cross-sectional shape of an isosceles triangle, 
contacts the workpiece "W" so that the cutting edge 60 precisely bisects 
the upper edge portion 18 of the workpiece. A downward force exerted on 
the punch 50 in the direction of the arrow in FIG. 1 will cause the 
workpiece to be sheared in the manner shown in FIGS. 2 and 3 forming 
angularly diverging tongues 75 and 77. After shearing, tongue 75 will have 
an area precisely equal to the area "A which, as previously noted, is 
equal to the cross-sectional area of groove 44. Similarly, tongue 77 will 
have an area "B" which is precisely equal in area to the cross-sectional 
area of groove 46 formed in support element 42. 
An important aspect of the present invention resides in the fact that 
because the workpiece "W" is rigidly clamped between supporting elements 
40 and 42 with faces 14 and 16 being supported throughout their entire 
areas, save for the areas "A" and "B", the downward force of the punch 50 
effects a true shearing action of the unsupported areas "A" and "B" along 
side shearlines which are coextensive with the transversely spaced edges 
of the grooves 44 and 46 respectively. This positive support of the 
workpieces immediately adjacent the shearlines of areas "A" and "B" 
permits a degree of precise repeatability which is not possible with prior 
art devices presently in use. 
Turning now to FIGS. 10 and 11, the apparatus of this form of the invention 
is used to controllably skieve a layer of the workpiece "W" to form a 
tongue having a predetermined precisely controlled width and length. As 
indicated in FIG. 10, the support elements 40 and 42a are supported within 
in die body 20 in the same manner as previously discussed herein. However, 
in this form of the invention, support element 42a provides support to the 
entire rear face 16 of the workpiece, while support element 40 provides 
support to the face 14 of the workpiece "W" throughout its entire area, 
save the unsupported area designated in FIG. 11 by the letter "C". As 
previously mentioned, this unsupported area is coextensive with the 
cross-sectional area of the groove 44 formed in support element 40. 
In addition to the different manner in which the workpiece "W" is supported 
in the apparatus of the second form of the invention, it is to be noted 
that punch 50a is also of a different configuration. More particularly, 
the cutting element of punch 50a, while in the shape of a triangle in 
longitudinal cross-section, takes the shape of a right triangle, rather 
than an isosceles triangle, with the apex of the triangle forming the 
cutting edge 60a. 
Once the workpiece "W" is securely clamped between clamping elements 40 and 
42a, a downward pressure on punch 50a in the direction of the arrow in 
FIG. 10 will bring the cutting edge 60a into contact with the upper edge 
18 of the workpiece "W" at a precisely determined location intermediate 
faces 14 and 16 of the workpiece. A continued downward force on punch 50a 
will cause the controllable skieving of a layer of material having an area 
"C", which area is coextensive with the cross-sectional area of the groove 
44 formed in clamping element 40. Once again, because the entire are of 
faces 14 and 16 of the workpiece are positively supported, save for the 
area designated by the letter "C", a downward movement of the punch 50a 
will cause a precise skieving of a layer of material of predetermined 
thickness to form a tongue of the character designated by the numeral 49 
in FIG. 11. This precise skieving of the material can be reproduced time 
after time because of the rigid support and positive constraint of the 
workpieces in the immediate proximity of the shearline defined by the 
edges of groove 44 in element 40. 
Following the shearing, or skieving, of the workpiece in the manner 
described in the preceding paragraphs, the electrical contact is finished 
in the manner illustrated in FIGS. 4 through 8. Referring particularly to 
FIGS. 4 and 5, after shearing the workpiece "W" using the apparatus of 
FIGS. 1, 2 and 3, the rough electrical contact thus formed has angularly 
diverging tongues 75 and 77 each having a thickness of one-half the 
thickness of the workpiece "W". Following the shearing step, the workpiece 
is removed from the die, the tongues 75 and 77 are bent into a closed 
position and the contact is blanked to the desired contour as, for 
example, that shown in FIG. 6. Next the tongues 75 and 77 are, once again, 
spread apart and the contact is coined and pre-formed into the desired 
configuration as for example that shown in FIG. 7. Finally, as a last step 
in forming the electrical contact, the contact of the configuration shown 
in FIG. 7 is bent into final form over a mandrel, or the like, to form the 
contact in a final configuration as, for example, that shown in FIG. 8. 
Referring now to FIG. 12, it is to be understood that the rough electrical 
contact thereshown was formed by the skieving method using the apparatus 
illustrated in FIGS. 10 and 11. 
This electrical contact includes an outwardly extending tongue 79 having a 
thickness approximately equal to one-half the thickness of the starting 
workpiece "W". The rough electrical contact of the configuration 
illustrated in FIG. 12 is prefinished into the desired final configuration 
in the same general manner as previously discussed in connection with the 
finishing of the contact depicted in FIG. 5. 
It should be appreciated that the apparatus shown in the drawing is, for 
sake of simplicity, depicted as a single punch and die acting upon a 
single discrete workpiece "W". In the actual commercial practice of the 
method of the invention, the apparatus would be mechanized so that a 
continuous length of starting material would be fed through an automated 
punch and die apparatus to continuously shear or skieve the material to 
form rough contacts which would then be configured and formed into end 
product electrical contacts on a continuous basis. However, because the 
production apparatus forms no part of the present invention, the details 
thereof are neither shown in the drawings, nor described herein. 
It should also be observed that the configuration of the electrical 
contacts as shown in FIGS. 4 through 8 and 12 are exemplary only. The 
apparatus of the invention can be used to produce electrical contacts 
having a wide variety of tongue shapes and thicknesses depending upon the 
end use to be made of the contacts. 
Turning now to FIGS. 13 and 14, an alternate approach to the shearing tool 
design and workpiece shearing operation of the present invention is there 
illustrated. The apparatus shown in FIG. 13 is somewhat similar to that 
shown in FIGS. 1, 2 and 3 and like numerals are used in FIG. 13 to 
identify like components. Unlike the apparatus earlier described, the 
apparatus shown in FIG. 13 is capable of simultaneously forming a 
plurality of electrical contacts rather than one. As in the previously 
described embodiment, the starting material or workpiece "W", used in the 
practice of the method of the present invention, has first and second 
generally parallel faces 14 and 16 of a predetermined area terminating in 
a perpendicularly extending third face, or edge, 18 of a predetermined 
width. 
The apparatus 80 comprises a die portion including a supporting body 20 
having a first, or front, face 22, a second, or top, face 24 and a bottom 
face 26 adapted to rest on a generally planar, rectangular base 28. A 
vertically extending, generally "U" shaped punch receiving channel 30 is 
defined by transversely spaced, generally parallel side walls 32 and 34 
which join with a perpendicularly extending back, or end, wall 36. 
Closely receivable within the lower portion of channel 30 are workpiece 
supporting means for continuously supporting the first and second faces 14 
and 16 of the workpiece "W". In the form of the invention illustrated in 
FIG. 13 the workpiece supporting means comprises supporting elements 82 
and 83. Elements 82 and 83 support substantially the entire faces 14 and 
16 of the workpiece save in the areas which correspond to the 
cross-sectional area of transverse grooves "X" formed in the elements 82 
and 83. 
It is to be observed that supporting element 82 is provided with 
transversely extending channels CH therethrough, which channels each have 
a cross-sectional area substantially equal to the unsupported areas "A" on 
workpiece "W". Each channel CH is defined by spaced apart parallel walls 
which join with a perpendicularly extending bottom wall. 
Supporting element 83 is also provided with transversely extending channels 
CH, each of which is defined by downwardly extending spaced apart parallel 
side walls which join with in a perpendicularly extending bottom wall. The 
cross-sectional area of these channels is substantially equal to the 
unsupported areas "B" on face 16 of the workpiece "W". Areas "A" and "B" 
are equal to the sheared areas, or tongues, simultaneously formed in the 
workpiece depicted in FIG. 14. 
Turning again to FIG. 13, the apparatus of the form of the invention 
thereshown further includes shearing, or punch, means closely receivable 
within channel 30 of the supporting body 20 for reciprocal movement 
therewithin. The function of the shearing means is to impart shearing 
forces to the third face, or edge, 18 of the workpiece "W" at locations 
intermediate the first and second faces 14 and 16. The shearing means, 
shown here as punch 84, includes interconnected side walls 84a which 
terminate in an upper wall 84b and a lower wall 84c. Extending downwardly 
or outwardly from end wall 84c of the punch 84 are cutter elements 86 each 
of which has the general shape of an isosceles triangle in longitudinal 
cross-section with the apex thereof terminating in a cutting edge 88. As 
indicated in FIG. 13, punch 84 is closely receivable within channel 30 of 
body 20 and is controllably movable in a downwardly direction. 
As in the earlier forms of the apparatus of the invention shown in the 
drawings, the workpiece clamping or supporting elements 82 and 83 are 
provided with opposing faces adapted to be brought into pressural 
engagement with faces 14 and 16 respectively of the workpiece. The 
supporting or clamping elements 82 and 83 are maintained in pressural 
engagement with the faces of the workpiece "W" by means of a plurality of 
stacked bars 64 which are interconnected with face 22 of body 20. Each of 
the bars 64 is provided with spaced apart apertures 66 which receive 
threaded connectors 68, which connectors are threadably received within 
internally threaded apertures 70 formed in the forward face 22 of body 20. 
With stacked bars 64 securely affixed to supporting body 20, punch 84 is 
closely receivable within an area defined by the rear face of stacked bars 
64 and the side and end walls 34 and 36 of channel 30. 
Practice of the method of the invention using the apparatus of the form of 
the invention shown in FIGS. 13, is substantially as previously described 
herein. However, with the configuration of the apparatus shown in FIG. 13, 
three pairs of tongues 89 of the general character illustrated in FIG. 14, 
will simultaneously be formed. Due to the novel character of the method 
and apparatus of the present invention, the spacing between the 
centerlines of tongues 89 can be closely controlled. The apparatus is 
readily adaptable to enable high volume fabrication of strips of contacts 
having conventional 0.100 inch and 0.050 inch centers. Additionally, for 
the first time, fork style contacts of of given thicknesses can be 
produced on very small center distances ranging down to about 0.010 
inches. This has substantial economic advantages in that meaningful 
material savings can be realized, and also for the first time, an integral 
comb, or strip, of contacts on extremely small center distances can be 
formed and assembled into a connector housing as a unit rather than as 
individual contacts, as is typical in the prior art. 
Turning now to FIG. 15, a shearing punch, generally identified by the 
numeral 90, can be seen to be of a different design than the earlier 
described elements. The punch 90 is provided with a body portion 90a 
having inwardly tapering side walls 90b and a workpiece engaging portion 
90c also having inwardly tapering walls identified as 90d which walls 
converge to form an apex 90e. Apex 90e forms the cutting edge of the punch 
and is preferably somewhat rounded rather than being a sharp edge. As will 
be discussed in greater detail hereinafter, by judiciously selecting a 
predetermined included angle "Z" of on the order of sixty degrees, several 
unique and unexpected results are achieved during the shearing operation. 
One of these results, which is extremely important in the forming of 
electrical contacts, is an unexpected burnishing effect which 
automatically produces a highly polished contact surface as the workpiece 
is controllably sheared. Another unexpected result is the progressive 
increase in thickness of the tongue portions during the shearing process 
so that the finished tongues have an average thickness greater than one 
half the thickness of the starting workpiece. Still another unexpected 
result of the shearing operation is the overall shortening of the length 
of the tongue portions with respect to the length of the unsupported areas 
of the workpiece. These surprising results will be discussed in greater 
detail hereinafter. 
As was the case in the shearing operation shown in FIG. 2, and as indicated 
in FIGS. 15 and 16, the workpiece W is closely supported by supporting, or 
clamping, means comprising clamping elements 92 and 94. As previously 
discussed, these important clamping elements support the faces of the 
workpiece as the splitting tool, or punch element, advances in the manner 
shown in FIG. 17. As pointed out in connection with the previously 
described embodiments of the invention, this support of the opposing faces 
of the workpiece in the areas proximate the material shear is of 
substantial importance to the accomplishment of the method of the 
invention and to the production of electrical contacts having the unusual 
configuration described in the preceding paragraph. Experimentation has 
shown that, while very small clearances between the workpiece and the 
clamping means is possible, the quality of the contacts produced tends to 
degrade. 
Referring particularly to FIG. 17 of the drawings, there is illustrated, by 
way of example, the shearing of a phosphor bronze workpiece W in 
accordance with the method of the instant embodiment of the invention. As 
shown in the upper portion of FIG. 17, the workpiece W, which has a 
thickness of about 0.025 inches, or 2 T, is being initially penetrated by 
the punch 90. At the point designated "A", the punch 90 has entered the 
workpiece approximately 0.011 inch and, as shown in the drawings, has 
created a "plowing" like effect on the material. As the punch 90 continues 
downwardly toward point "B" with sufficient force to evenly shear, but not 
tear, the material, substantial pre-shear compressive forces are 
continuously exerted on the workpiece at locations proximate the apex of 
the punch. The imposition of these very high, pre-shear compressive forces 
causes the unexpected burnishing effect to occur on either side of the 
apex of the punch. It is this burnishing action which results in the 
formation of a remarkably fine finish on the sheared surfaces of the 
electrical contact. It is to be appreciated that as the punch moves 
downwardly shearing occurs simultaneously along five shear lines and, as a 
result, six surfaces are simultaneously created. These six surfaces are 
the inner surface of each tongue and the transversely spaced outer edges 
of each tongue. 
By the time the cutter element, or punch, 90 has moved to point "C", it has 
generally bisected the workpiece to a depth of about 0.091 inches and the 
angularly diverging tongues of the contact are beginning to take shape. 
Continued movement of the punch to point "D" which, in the example shown 
in FIG. 17, represents a depth of on the order of 0.191 inches, results in 
the formation of the elongated angularly diverging tongues identified by 
the numeral 97. Examination of the inner surfaces of these tongues reveals 
the existence of a highly polished, very fine finish along their entire 
length. Examination of the tongues also reveals that they have become 
progressively thicker and that, if they were to be bent inwardly toward 
one another, their overall length would be less than the length of the 
unsupported area of the starting workpiece. The apparent reasons for this 
thickening of the tongue walls as well as the foreshortening effect will 
presently be discussed. 
Turning now to FIG. 18, which is a cross-sectional view of tongue 97 taken 
along lines 18--18 of FIG. 17, the thickness T1 of the tongue in the 
present example is on the order of 0.0153 inches. In light of the fact 
that the starting thickness 2T of the workpiece was on the order of 0.025 
inches and one-half this thickness, or T, was on the order of 0.0125 
inches, it is apparent that a marked increase in wall thickness has 
occurred during the formation of tongue 97. 
Experience has shown that for the same starting material, the smaller the 
angle "Z" formed on the punch the smaller will be the pre-shear 
compressive forces generated and the smaller will be the increase in 
average thickness of the angularly diverging tongues. Depending upon the 
character of the starting material, a reduction in the size of angle "Z" 
will also result in a more moderate curling of the diverging tongues. 
Accordingly, it is to be understood that tongue configuration can be 
precisely controlled by choice of materials, and by changing the angle "Z" 
formed on the punch. Additionally, the length of the tongues can be 
controlled by controlling the depth of travel of the punch 90. For 
example, longer tongues 97a can be formed as a result of further downward 
travel of the punch to a point "E" (FIG. 17). However, experimentation has 
revealed that, with most starting materials, after a certain depth of 
penetration of the punch has been reached, the thickness of the tongues 
will stabilize and will not further increase in thickness. 
It is to be understood that the results described in the preceding 
paragraphs vary somewhat depending upon the character of the starting 
material. As a general rule, however, the softer the starting material and 
the more obtuse the shearing punch angle, the greater will be the 
thickening of the tongues and the greater will be their foreshortening. 
The reverse is true when harder starting materials and sharper shearing 
punch angles are employed. The table which follows illustrates these 
results (thicknesses and lengths are expressed in inches and punch angle 
is expressed in degrees). 
__________________________________________________________________________ 
THICKNESS 
SAMPLE 
TEMPER OF PUNCH 
STARTING 
TONGUE 
TONGUE 
NO. MATERIAL 
MATERIAL 
ANGLE 
LENGTH LENGTH 
THICKNESS 
__________________________________________________________________________ 
1 CA260 0.025 40 0.345 0.270 0.017 
annealed 
brass 
2 CA260 0.025 50 0.345 0.2485 
0.0183 
annealed 
brass 
3 CA260 0.025 60 0.345 0.2295 
0.020 
annealed 
brass 
4 CA260 0.025 40 0.345 0.295 0.0156 
3/4 hard 
5 CA260 0.025 50 0.345 0.2735 
0.0158 
3/4 hard 
6 CA260 0.025 60 0.345 0.255 0.0719 
3/4 hard 
7 CA510 0.025 40 0.345 0.3015 
0.0145 
1/2 hard 
phosphor/ 
bronze 
8 CA510 0.025 50 0.345 0.286 0.0152 
1/2 hard 
phosphor/ 
bronze 
9 CA510 0.025 60 0.345 0.273 0.0158 
1/2 hard 
phosphor/ 
bronze 
10 CA510 0.025 40 0.345 0.305 0.0148 
3/4 hard 
11 CA510 0.025 50 0.345 0.290 0.0156 
3/4 hard 
12 CA510 0.025 60 0.345 0.280 0.0162 
3/4 hard 
13 CA510 0.025 40 0.345 0.3155 
0.0143 
full hard 
14 CA510 0.025 50 0.345 0.2995 
0.0148 
full hard 
15 CA510 0.025 60 0.345 0.295 0.0155 
full hard 
16 CA510 0.020 50 0.345 0.3095 
0.0115 
full hard 
17 CA510 0.020 60 0.345 0.2995 
0.0118 
full hard 
__________________________________________________________________________ 
Turning to FIGS. 19 and 20, the present method of slug removal is compared 
with a typical prior art slug removal step. As shown in FIG. 19, which 
illustrates the prior art conditions, the slug, or adjacent part, is 
identified by the numeral 100, the blank punch is indicated by the numeral 
102 and the starting material is identified by the numeral 104. Referring 
to the left hand portion of FIG. 19 the interference between the slug 102 
and the blank 104 is at once apparent. If pressure is exerted in the 
direction of the arrow 105 on the slug knockout punch 106 the interference 
between the slug and the blank resists removal of the slug. Accordingly, 
in the prior art the slug 100 is normally removed in the opposite 
direction as indicated in the right hand portion of FIG. 19. 
Turning to FIG. 20 which illustrates slug removal in accordance with the 
method of the present invention, the slug, or adjacent part, is identified 
by the numeral 108, the blanks by the numeral 110 and the starting 
material by the numeral 112. In light of the highly burnished surfaces 
formed on the electrical contacts due to the shearing by the present 
method of the invention, slug removal takes on greater significance since 
it is highly desirable that the highly polished surfaces be carefully 
preserved. As shown in the right hand portion of FIG. 20, the punch 90 has 
sheared the starting material in a unique manner such that the tongues 110 
conform, not to the die, but rather to the width of the punch. This 
unexpected and unusual phenomenon of the sheared material conforming to 
the shape of the punch rather than to the die, will be discussed in 
greater detail hereinafter. Suffice to point out at this time, that this 
conformation permits ready removal of the slug in the manner shown in the 
left hand portion of FIG. 20. Because of the clearance, which results, the 
knock out punch 114 can more easily remove the slug, or adjacent part, in 
the same direction as the travel of the die and indicated by the arrows. 
Similarly, the sheared tongues can be readily removed from the die, 
without damage. 
Referring now to FIGS. 21 and 22, a contact forming step is there 
illustrated. As previously discussed, and as shown in FIG. 17, as the 
punch advances the angularly diverging tongues of the contact will be 
formed. The converged configuration of the tongues naturally results and, 
as earlier stated, can be controlled to some degree by varying the angle 
"Z" of the punch. Accordingly, the method of the present invention makes 
it possible to produce electrical contacts in a desired final 
configuration by merely exerting controlled bending pressures on the 
diverging tongues using forming dies of the character shown in FIG. 22 and 
designated therein by the numeral 116. By exerting inwardly directed 
pressures on the specially configured dies 116 the tongues 97a of the 
contact can be formed from the as sheared configuration generally 
illustrate by the phantom lines into the desired final configuration 
illustrated by the solid lines. This method of forming the contact in its 
final configuration also tends to further preserve the highly polished 
surfaces of the contact which have been automatically formed during the 
shearing step. 
Turning now to FIGS. 23 through 26, the novel feature of the invention, 
namely the conformation of the tongues to the punch, is further 
illustrated. As discussed in the preceding paragraphs, with the opposing 
surfaces of the workpiece substantially supported throughout their entire 
area, save for an unsupported area of the desired size and configuration, 
the method of the present invention permits the formation of contacts 
having tongues which closely correspond to the configuration of the punch 
of the shearing apparatus. This feature of the invention not only permits 
the forming of contact tongues having a width less than the width of the 
unsupported area of the workpiece, but also permits the forming of contact 
tongues of various cross-sectional configurations. 
As indicated in FIG. 23, the punch P of the apparatus of the invention can 
be formed such that the angularly extending shearing faces P-1 and P-2 of 
the punch are generally concave. When this type punch is used in 
connection with a die of the character illustrated in FIG. 1, contacts 
having tongues 120 with concave surfaces of the character illustrated in 
FIGS. 25 and 26, can be formed. 
Turning to FIGS. 27 through 30, the punch P of the apparatus of the 
invention can be formed such that the angularly extending shearing faces 
P-2 and P-4 of the punch are generally convex. When this type of punch is 
used with dies of the character shown in FIG. 1, contacts having tongues 
122 with convex surfaces of the character illustrated in FIGS. 29 and 30, 
can be formed. In either case tongues having a highly polished inner 
surface are automatically produced. 
It is apparent that the formation of high quality electrical contacts 
having tongues of various cross-sectional configurations, as for example 
concave or convex, has great commercial advantage. In applications where 
the pin with which the electrical contact is to mate is preferably 
cylindrical in shape, contacts having concave surfaces as illustrated in 
FIG. 25, can be expeditiously formed to closely mate with the cylindrical 
pin. Conversely if the pin with which the contact is to mate is of a 
dished out configuration, contacts having the configuration shown in FIG. 
29 can be formed. In a similar manner, a contact can be formed to mate 
with virtually any shaped pin by simply designing the punch of the 
apparatus accordingly. 
It is to be understood that the method and apparatus of the invention, as 
previously described herein, can be used to manufacture a wide variety of 
useful devices. Such devices include; end products such as electrical 
contacts, thermal contacts, fasteners of various kinds, and similar types 
of hardware, as well as interim configurations of these products. When 
electrical contacts are to be fabricated, the starting material is, of 
course, electrically conductive. On the other hand, when thermal contacts, 
such as may be used in heat dissipation systems, ar to be fabricated, 
thermally conductive material is used as the starting material. For other 
types of hardware devices, end product use will govern the choice of 
starting material. 
Having now described the invention in detail in accordance with the 
requirements of the patent statutes, those skilled in this art will have 
no difficulty in making changes and modifications in the individual parts 
or their relative assembly in order to meet specific requirements or 
conditions. Such changes and modifications may be made without departing 
from the scope and spirit of the invention, as set forth in the following 
claims.