Electrical connector housing with improved contact insertion

An electrical connector (10) having a housing (12) of resilient plastic material of a type molded in a closed mold with bores defined by core pins; the housing including at least a bore (22) extending therealong leading from an insertion segment (36) of a given diameter to receive a contact (12) to a reduced diameter defining a support segment (28) supporting the contact in the housing, and a forward segment (25), with the various segments extending along a common axis (A) and with a beveled transition defined by surfaces (34) extending between the bore of the insertion segment and the bore of the support segment as defined by a series of recesses (30) and segments (32) arranged around the support segment periphery to define a lead-in for the said contact and maintain an approximate constant thickness of material to minimize plastic sinking and distortion.

FIELD OF THE INVENTION 
This invention relates to an electrical connector housing of molded plastic 
material having a contact receiving bore facilitating contact insertion. 
BACKGROUND OF THE INVENTION 
A type of electrical connector widely used in interconnecting electrical 
and electronic devices employs a thermoplastic material sufficiently 
resilient to incorporate in one piece bores or cavities to receive 
contacts and hinged elements to facilitate latching and fastening of 
connector halves together. Such connectors are used in high volume and 
accordingly, are made in multiple cavity molds with mold cycle times as 
short as possible, consistent with the material employed and the need for 
minimizing distortion in dimensions to acceptable tolerances. One of the 
practices widely utilized in molding such housings is to maintain wall 
thicknesses throughout the connector relatively constant. By that is meant 
that wall thicknesses varying much more than 50 percent through any 
section of the connector between mold surfaces, between an outer mold 
shell and core pins, may experience not only distortion, but tolerance 
variations and a visual appearance, which is unacceptable. Longer mold 
cycles may remedy some of these shortcomings, though not all, and will 
lead to a substantial increase in cost of housings. 
With respect to one widely used type of thermoplastic housing, the interior 
bore of the housing has been made to include a contact receiving sleeve 
that forms a bearing segment to support the contact radially within the 
housing, the sleeve thickness being made along most of its length 
approximately equal to other wall thicknesses of the housing. This 
interior sleeve typically includes an inwardly directly beveled or tapered 
surface that serves to guide contacts during insertion of such contacts 
within a housing. With respect to male contacts having a rounded forward 
end, such sleeve works generally adequately without stubbing, but with 
female contacts that have a blunt or squared end, problems have arisen due 
to stubbing with the female contact catching on the end of the sleeve if 
the sleeve is not adequately concentric or if the contacts is not properly 
lined up. This sort of problem is aggravated by a lack of concentricity of 
the sleeve caused by high speed mold cycles or variations in plastic 
material. At one time the contact bearing segment was made solidly, but 
problems were experienced with a lack of roundness of the bore through the 
segment causing, on occasion, contact backout due to the lances of the 
contact becoming aligned with an out of round bore segment. 
Another problem associated with housing of the prior art relates to the 
breakage or elongation of the sleeve due to muscle pulls. After the 
housing has been molded, the core pin can stick to the material of the 
sleeve, thereby causing the sleeve to be damaged as the core pin is 
removed. This is a frequent occurrence as the sleeve is not supported over 
its entire length. If the sleeve is torn or elongated, the contacts can 
not be properly seated and locked within the housing. 
Accordingly, it is an object of the present invention to provide an 
improved electrical connector housing that facilitates an easy and 
reliable insertion of electrical contacts within the housing. It is a 
further object to provide a molded plastic housing having a beveled entry 
to facilitate guiding contacts during insertion with minimum distortion 
caused by unduly thick sections of plastic material surrounding the 
contact bearing segment. It is still a further object to provide a 
thermoplastic housing of molded material having a configuration 
facilitating high speed molding with minimum distortion and minimal muscle 
pulls. 
It is a final object to provide a contact housing that includes interior 
beveling or tapering to facilitate contact entry and at the same time, a 
housing geometry facilitating high speed molding with minimum plastic 
distortion. 
SUMMARY OF THE INVENTION 
The present invention features an electrical connector housing, typically 
having a plurality of cavities or contact receiving bores extending 
therethrough. In accordance with the invention, each bore is made to 
include an entry segment of a given diameter leading to a contact bearing 
or support segment of a lesser diameter and a forward segment of a larger 
diameter than the diameter of the bearing segment that overlies a contact 
end. There is provided a step extending radially between the contact 
bearing segment and the forward segment defining a surface receiving the 
end of one or more lances that preclude contact backout. There is provided 
a beveled or tapered surface or surfaces leading from the bore entry 
segment to the contact support segment to receive the end of an inserted 
contact, particularly the blunt end of a female contact and guide such 
contact to enter the bore support segment and pass therethrough into the 
front segment with the contact lance or lances engaging the step to hold 
the contact within the housing. In accordance with the invention in a 
preferred embodiment, the guiding surfaces are comprised of a series of 
beveled surfaces leading from the diameter of the entry segment to the 
diameter of the bearing segment with a series of recesses extending 
between discrete surfaces disposed around the periphery of the bores, such 
recesses extending at least substantially along the length of the bore 
support segment to maintain a thickness of material in that region that is 
approximately constant with respect to the thickness of the portions of 
the housing. The recesses in the present invention are tapered from the 
entry segment toward the forward segment to facilitate tapered core pins 
and an easy withdrawal with minimum distortion of the plastic. In this 
way, the housing is given the tapered interior bore facilitating contact 
insertion, and at the same time, minimizes bore distortion which could 
allow contact backout due to a lance aligning itself with the distorted 
portion of the bore and as well precluding sink marks in the exterior 
surface of the housing and/or other distortions that are objectionable. 
The invention also contemplates that the recesses may be formed from the 
opposite end of that just expressed, namely, leading from the forward end 
toward the entry end to maintain the wall thickness and still allow a 
tapered surface leading from the entry end toward the bore support segment 
.

DETAILED DESCRIPTION OF THE INVENTION 
Referring now to FIG. 1, a connector 10 may be seen to comprise a contact 
12 and a housing 18, made from a material such as nylon. The housing 18 
receives and supports contact 12 for intermating with a contact in a 
further connector, not shown, along an axis A. The contact 12, an end 
portion only being shown, is typically interconnected to a wire that is 
part of a harness utilized to interconnect electrical or electronic 
devices. The contact 12 is typically stamped and formed of a spring grade 
conductive material, such as brass or phosphor bronze, suitably plated, 
with an alloy of tin or, in certain instances, precious metal. The contact 
12 includes at least one lance 14 struck from the outside thereof that is 
utilized to latch the contact within housing 18. Contacts such as 12 may 
be either male or female contacts in accordance with widespread usage. 
Male contacts typically have a rounded end that facilitate insertion into 
housing such as 18, but female contacts have a blunt or sharp edge leading 
to an interior receptacle portion into which is plugged a male contact in 
use. FIGS. 5 and 6 show prior art examples of connectors of the type 
described. FIG. 5 shows an entry end of a connector housing 18' having an 
entry bore 36', an interior sleeve 31 having a bevel 34' leading to a 
contact support bore segment 28'. FIG. 6 shows this in relationship to a 
forward bore 25' and a step 26' extending between the forward portion 25' 
and the contact bearing portion 28'. As can be seen, the sleeve 31 extends 
out into the entry bore segment 36' and as can be seen, a contact 12' 
being inserted within bore 36' if not properly aligned, may stub on the 
end of the sleeve 31, despite the beveled surface 34'. The sleeve 31 
replaced a prior art solid section in the region of the support segment 
28' in order to reduce the distortion of the bore 28' and further 
distortion in the exterior surface of the housing. The resulting 
structure, however, has been realized to cause occasional but undesirable 
stubbing during contact insertion as is depicted in FIG. 6. 
The present invention represents an improvement over this prior art through 
the provision of details to be described. Referring back to FIG. 1, the 
housing 18 may be seen to include a number of features, such as the hinge 
shown as 19, allowing the exterior portion of the housing to flex for 
latching purposes or for engagement purposes. There is a central housing 
portion 20 that contains a pair of apertures or bores 22 that extend 
therethrough along an axis of insertion of the contact and of the mating 
of the connector half and housing 18 with another connector half, not 
shown. The housing 20 includes forwardly projecting sleeves 24 that have 
forward bores 25 leading to a step 26 and a contact support segment in 
bore 28 of a reduced diameter and onto an interior bore 36 that represents 
an entry segment of the bore 22. The bore 36 is of a substantially larger 
diameter than bore 28. As can be seen in FIGS. 1 and 2, the bore 28 has a 
transition to bore 36 in the form of a series of surfaces shown as 34 that 
are beveled or tapered from bore 28 to bore 36 in the manner shown in FIG. 
3. These surfaces 34 are defined by a series of recesses 30 that lead 
interiorly along the segment of bore 28. The recesses 30 are separated by 
segments 32 as shown in FIGS. 2 and 3 that extend along the length of 
segment defined by bore 28 to an end surface 29 as shown in FIGS. 1 and 4. 
As can be appreciated from FIGS. 1 and 2, the recesses 30 are tapered, 
narrowing along the length of segment bore 28. FIG. 3 shows the advantage 
of the configuration to include the tapered or beveled surfaces 34, noting 
the engagement with end 16 of contact 12 on surface 34 tended to guide the 
contact insertion into the support bore 28 and on through the housing to a 
point where the lance 14 of the contact will snap outward to engage the 
step 26 and lock the contact within bore 22 and to housing 18. 
It has been found that providing reliefs and segments with plastic arranged 
as described and shown in FIGS. 1-4 minimizes distortion of the bore 28, a 
sinking of material in the exterior of the housing and as well provides a 
tapered surface leading from bore 36 to bore 28 and easing insertion of 
contacts. The reliefs and segments also prevent muscle pulls from 
destroying the integrity of the bore. As the segments are supported over 
their entire length, the removal of the core pin after molding does not 
tear or elongate the segments. Consequently, the contacts 12 will be 
properly seated in the housing. 
The invention utilized some eight segments 32 in one embodiment, and the 
beveled surfaces 34 were tapered relative to the insertion axis a shown in 
FIG. 3. The invention fully contemplates alternative embodiments as for 
example where the recesses 30 are made to lead from the bore segment 25, 
originating at step 26 and leading rearwardly, tapered as previously to 
accommodate tapered core pins. Alternatively, the recesses 30 could be 
alternated with every other recess leading from the bore 25 and the 
opposite recess leading from bore 36. 
In both the foregoing embodiments, the tapered surface 34 would be 
maintained, the point being that balancing wall thickness minimizes bore 
distortion and plastic surface sinking. The invention contemplates that 
fewer recesses 30 may be employed and fewer surfaces 34, as long as there 
is a beveled guide end leading from the bore 36 to bore 28 guiding contact 
within the housing, and sufficient balance of wall thickness maintained to 
prevent distortion. 
Having now described the invention in terms intended to enable a preferred 
practice thereof, claims are set forth which define what is deemed 
inventive.