Multiple-post connectors and method of making multiple-post connectors

Connectors having multiple posts upstanding from a common cross-connection bus are produced by a method that includes the steps of making an extrusion that encompasses the end projection of the connector including the bus and the posts, and then using hollow end-milling cutters to form the posts.

The present invention relates to a particular form of electrical connector, 
which comprises a row of terminal posts upstanding from a common 
connection bus. More particularly, the invention relates to a method of 
making such connectors. 
BACKGROUND OF THE INVENTION 
Connectors of that form have been produced for many years using castings as 
the starting material, finished by secondary operations. This practice 
follows the common wisdom that production of such terminals should start 
with a casting that embodies the basic structure of the connector, in this 
instance the shaped posts upstanding from the connection bus. Using the 
casting as the starting material avoids machining operations to produce 
the basic shape. It is commonly understood and accepted that resort to 
machining for producing such a basic shape entails costly operations that 
are obviated by the casting step. Undoubtedly, this explains the routine 
use of castings heretofore, in making the electrical connectors here 
involved. 
Separately, neutral bars have long been produced by preparing a simple bar 
by extrusion, then drilling wire-receiving holes and cross-drilling and 
tapping holes for wire-retaining screws. Other connection devices have 
been produced by a process that starts with an extrusion, followed by 
secondary finishing steps. 
SUMMARY OF THE INVENTION 
An object of this invention resides in providing a new and economical 
method of making electrical connectors of the type having a common 
connection bus and a row of terminal posts upstanding from the bus. 
A further object of the invention resides in producing terminals having a 
row of terminal posts upstanding from a common connection bus, without 
resort to casting. When a casting is used as the basic structural shape, 
the finished electrical connection device may have occluded bubbles that 
impair conductivity and that may seriously weaken the structure of the 
connector, in random instances. 
Accordingly, an object of the invention resides in providing a novel method 
of producing electrical terminals of the type having a row of posts 
upstanding from a common connection bus, by a method that is economical 
and which at least largely precludes occluded bubbles. 
Electrical connectors are produced pursuant to this invention by a process 
that includes forming the basic shape replacing the casting by the steps 
of initially preparing an extrusion whose end view encompasses both the 
cross-section of the connection bus and a volume of metal having an 
outline encompassing the side view of the electrical posts, then forming 
the upstanding posts by means of a hollow end-mill directed toward the 
portion of the extrusion that embodies the connection bus. The electrical 
connector is completed by the usual drilling and tapping operations 
performed heretofore on the casting. However, the end result is that the 
costs of the casting mold and of the operation of producing the casting 
are replaced but not augmented in the novel method, and the flaw of 
occasional bubbles in castings is essentially eliminated. 
The nature of the invention and its advantages will he more fully 
appreciated from the following detailed description, to be considered 
together with the accompanying drawings.

Referring now to the drawings, particularly to FIGS. 1 and 2, an electrical 
connector is shown of the type that may be made either by the procedure 
involving a casting or in accordance with the invention. In FIGS. 1 and 2, 
a connector is shown having four terminal posts 10 upstanding from a 
connection bus 12. Each post 10 has a cylindrical lower portion and an 
upper portion having a flat area 14 against which the lug 16 of a circuit 
connector is secured by a fastening screw 18. Bus 12 and a portion of each 
post is covered by a coating of insulation 20. As shown, the circuit 
connection includes an insulated wire in addition to a lug 16, and a boot 
22 of insulation is slidable along the insulated wire and into abutment 
with the coating of insulation 20 on the connector. Boot 22 has a 
cylindrical cavity that fits snugly around the cylindrical lower portion 
of post 10. In this way, some protection is provided for the connection of 
the wire to the connector, against attack by the environment in which the 
connector is used. FIGS. 3 and 4 show a ductile metal extrusion used in 
the present novel method for producing the connector of FIGS. 1 and 2. 
The outline of extrusion 24 encompasses the end projection of the common 
bus connection 12 below the broken line 24a and the cross-section of the 
extrusion also encompasses the outline of the terminal posts 10 (FIGS. 1 
and 2) as viewed from one end of the connector. Thus, above the material 
that is to constitute the connection bus 12, the cross-section of the 
extrusion has a width 24c that is at least equal to the diameter of posts 
10; and the outline of the extrusion includes a top portion 24d that is 
reduced (compared with portion 24c) so as to constitute a preformed 
lateral surface 24e that ultimately is to provide flat areas 14 of the 
terminal posts 10. 
A hollow cylindrical end-milling cutter C (FIG. 12) acts on extrusion 24 
from the top downward to remove bulk metal of the extrusion so as to leave 
one post 10 after another upstanding from bus 12. This may be performed in 
a series of operations, or a pair of hollow end-milling cutters may be 
used to form the first and third terminal posts in one operation and the 
pair of hollow end-milling cutters may be used in another operation to 
form the second and fourth terminal posts 10. As seen in FIG. 7, broken 
lines 26 show the outer circles of the cuts made by the end(s) of the 
end-milling cutter(s). In the example shown, posts 10 are spaced apart by 
little more than the wall thickness of the cutters; with that proportion, 
the cutters form a flat upper surface of common connection bus 12 between 
the posts 10. 
The basic structure of the electrical connector is completed by the 
two-step process of making the extrusion followed by operation of the 
hollow end-mill cutter to form the posts. The electrical connector is 
completed by drilling and tapping holes 28, one per post or (in other 
forms) two per post. Insulation 20 is applied by a conventional 
dip-and-cure treatment. 
As indicated in FIG. 12 and by broken lines 26, the wall of the hollow 
end-milling cutter is quite thick. If the wall of the cutter were thin or 
if the posts were spaced apart wider than they are in FIGS. 5 and 7, the 
areas of broken-line circles 26 would not extend over the whole top 
surface of the common connector bus 12. Then, after the posts have been 
formed by the cutting operation, vestigial projections upstanding from the 
common connection bus would remain as tall as the posts. For many reasons, 
the hollow end-milling cutters should be proportioned to preclude any such 
vestigial projections. 
If the thickness 24c of the extrusion were less than the diameter of the 
posts, or if the hollow end-milling cutters were used carelessly, the 
posts would have lateral flat surfaces. While not fatally defective, such 
flats would constitute passages along the posts when the boots are in 
place. The atmosphere in which the connector is used might then penetrate 
to the circuit connection at the top of each post via that passage, with 
potentially damaging effect. Attention should be given to proper use of 
the hollow end-milling cutters, to avoid lateral flat surfaces on the 
posts. 
Virtually the same novel procedure is followed in producing electrical 
connectors of the form shown in FIGS. 10 and 11. In that connector there 
are four terminal posts 50 upstanding from common connection bus 52. Each 
post 50 has a vertical wire-receiving hole 54 and a horizontal threaded 
hole 56 for a wire-retaining screw (not shown). Tapped hole 56 is in a 
wall see (FIG. 11) of the post that is thicker than the opposite wall; for 
this effect the vertical hole is drilled off-center in its post. 
An extrusion 58 is shown in FIGS. 8 and 9; the cross-section of the 
extrusion includes material below broken line 60 (FIGS. 8 and 9) which is 
to constitute the common connector bus 52. Above line 60 is a part of the 
extrusion whose end view encompasses terminal posts 50 as seen from one 
end of the connector. 
As described above in relation to FIGS. 3-7, a hollow end mill (FIG. 12) is 
used to cut extrusion 58 so as to form cylindrical posts 50 and to develop 
the top flat surface of common connection bus 52. 
Connectors of the type involved here, produced by the novel method, are 
superior to the same type of connectors as produced heretofore, in that 
occluded bubbles and other flaws occasioned in casting are obviated. It is 
striking that the novel method enables production of the superior 
connectors in a manner which not only avoids prohibitive expense, but 
which actually is economical. The dominating consideration is that the 
connectors produced by the novel method are superior to those produced by 
the method used heretofore, involving the use of castings, and that the 
method which yields superior connectors does not entail prohibitive 
manufacturing costs.