Winding contact with rotary fastening for insertion into a contact housing hole with circular cross section

A contact casing (1) rolled from a spring plate blank with a rotary safety zone (30) is present for anchoring and centering of this winding contact in the contact hole of a plastic housing, which rotary safety zone has a centering section (40) encompassing the winding post (3) in the form of a ring and is connected firmly with it and has a clamping section (41). Lateral indentations (34a, 34b) act as spring elements by which the longitudinal seam (37) of the centering section (40) is held closed in the case of acting torques and radial forces. The clamping section (41) comprises clamping arms (42a, 42b) which are firmly connected by way of the base part (32) with the centering section (40) and the claws (44a, 44b) of which project beyond the periphery of the centering section (40). The firm connection of the clamping section (41) and the centering section (40) together with the always closed longitudinal seam (37) of the latter, will ensure that in the case of torques acting on the winding post (3), the claws (44a, 44b) will only be pressed more firmly into the contact hole wall, but the penetration depth will remain limited to the maximum value predetermined by the projection of the claws (44a, 44b) beyond the centering section (40). Thus, even in the case of housings made of a soft plastic, a reliable seat of the winding contact and a minimal damage of the contact holes are ensured.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to a winding contact having a winding post which is 
attached in a contact casing made of spring plate and carrying a contact 
element for the centered and torsional holding of the winding contact in a 
cylindrical contact hole of a contact housing made of electrically 
insulating plastic. 
2. The Prior Art 
In the case of electric plug connections with winding contacts in the case 
of which the wire connection is executed as a nonsoldered connection in 
the so-called winding or wire wrap technique, it is necessary to absorb 
with the contact the torque occurring in the case of winding on the 
winding or wire wrap post, which contact must therefore not rotate in the 
contact hole of the contact housing. Winding contacts therefore must be 
equipped with rotary safeties. 
A constructionally simple rotary safety will be obtained whenever the 
contact hole is made non-round in an axial area and whenever the contact 
is correspondingly constructed. Such a plug connection is described, for 
example, in the German No. OS 26 16 621. Such a rotary safety necessitates 
that, for every contact housing, matching contacts be provided, and this 
contradicts the universality of the contact housing striven for for 
economic reasons because the usually round contacts cannot be then used. 
For the rotary safety of contacts additional parts are frequently used in 
the most varied embodiments, such as described, for example, in the German 
patent No. 23 50 775, the U.S. Pat. No. 4,090,771 and in the French Pat. 
No. 2,263,615. The separate anchoring part will be attached frequently to 
the contact or it is placed over the winding post and may consist of a 
lamella or a peg. Bipartite rotary-secured contacts are expensive in their 
production and uneconomical, and moreover their handling is cumbersome, 
whereby considerable wear and tear often occurs on the contact housing 
since, during the replacement of the contacts, the walls for the contact 
hole may easily be greatly damaged, or as especially in the case of 
multiple contacts with a multiplicity of contacts arranged closely beside 
one another, they could even be destroyed. 
In the market place, one-part rotary-secured contacts are available in 
which the essentially casing-shaped resilient rotary safety is made of the 
same piece of material as the contact body. Known embodiments of such 
single rotary-secured contacts however turn out to be unsatisfactory 
insofar as above all, because of a resilient springiness of the springy 
rotary safety and of the circumstance that stronger torques and radial 
forces acting upon the contact inserted into a contact hole, lead to 
changes of diameter in the case of the rotary safety and/or to a reduction 
of the penetrating depth of the clamping elements in the wall of the 
contact hole, only relatively weak torques must be applied for the 
production of a winding contact, in order to exclude with assurance a 
loosening of the rotary safety in the case of winding, and thus one must 
count with a more frequent occurrence of defective electrical connections 
subject to breakdowns between the conducting wire and the contact piece. 
Therefore, it was the task of the invention to create a rotatably secured 
winding contact of the initially mentioned type in the case of which and 
on the assumption that, whenever it is inserted into a contact hole with a 
circular cross section, it will permit the essentially desirable mobility 
of the contact piece in the contact hole for plug connections and at the 
same time center the plug connection area as well as the winding post 
well, that the rotary safety is unchangeably reliable even after frequent 
contact loads, as they occur especially in the case of plugging 
connections themselves or in the case of a pull on the connected 
conducting wire, and in the case of which torques and radially acting 
forces will not change the penetrating depth of anchoring elements in the 
wall of the contact hole disadvantageously. Furthermore, the 
exchangeability is to be ensured for the winding contact, that is to say, 
the winding contact should be such that upon taking the contact housing 
from the contact hole, the wall of the contact hole will not be destroyed 
or damaged so badly that it no longer satisfies the electric requirements, 
especially with regard to the insulation thickness, and finally, the 
winding contact is to be producible also in an economic mass production. 
SUMMARY OF THE INVENTION 
According to the invention the rotary safety of the winding contact is 
guaranteed solely by a special development of a relatively narrow section 
of the contact casing at the end far away from the contact element, 
whereby for the winding pole there only exists the requirement that it be 
firmly mechanically connected with this rotary safety zone, otherwise 
however, all possibilities are left open for the winding post and for the 
development of the contact element, be that as a plug connection or as a 
peg. The clamping together of the rotary safety zone at two points in the 
contact hole which face each other ensures the desired mobility of the 
contact element in the contact hole, and torques as well as radially 
acting forces do not tend to a reduction of the diameter in the centering 
section of the rotary safety zone but to an enlargement of the diameter, 
which ensures a firm seat of the contact casing in the contact hole and 
thus a good centering of the contact piece and winding post. The 
penetrating depth of the claws in the wall of the contact hole, limited in 
any case to a predetermined maximum value, make the winding contact 
according to the invention usable for contact housings of any kind of 
plastic, so that the contact housing may consist especially also of a soft 
plastic, such as a thermoplastic. As a result of the limited penetrating 
depth, there is no need to fear a stronger damage of the wall of the 
contact hole even when removing the winding contact from a contact hole, 
so that the exchangeability is ensured and in the case of exchanging a 
contact, it will only be necessary for the new winding contact to be 
displaced in the contact hole somewhat as compared to the original 
position, in order to obtain optimum conditions. The contact casing may be 
mass-produced easily by a pipeshaped rolling up of spring plate blanks.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The winding contact shown in FIG. 1, a so-called wire-wrap contact, has a 
contact casing 1 which is rolled in the manner of a pipe from a spring 
plate blank 1' (FIG. 5) and which carries at one end a plug connector or a 
plug peg as a contact element 2 away from which right through the contact 
casing 1, a coaxial winding post 3 extends. The winding post 3 existing 
for the winding contact (wire-wrap-connection) may have a rectangular 
cross section (FIG. 1) of, for example, 0.8 mm.times.1.6 mm or else a 
square cross section (FIG. 2, FIG. 3) of, for example, 1 mm.times.1 mm. 
Contact casing 1, contact element 2 and winding post 3 consist of 
materials customary for such electric plug connections, the contact casing 
for example consists of bronze sheet. The winding contact is plugged into 
a cylindrical contact hole 5 of an electrically insulating housing 4 (FIG. 
2, FIG. 3) made of plastic, for example, of a phenoplast or a thermoplast, 
whereby the outside areas of the contact casing 1 fit against the wall 6 
of the contact hole and the winding contact is centered by way of the 
contact casing 1 in the contact hole 5 and secured against turning around 
the longitudinal axis 7, non-shiftable in longitudinal direction and it is 
supposed to be somewhat moveable in order to facilitate the plugging 
together in the plugging area, which in the case of the winding contact 
according to the invention will be achieved by a special shaping of the 
contact casing 1 which will be described in more detail in the following 
paragraphs with reference to the FIGS. 1 and 4. 
As is shown in the FIGS. 1 and 4, the contact casing 1 essentially has 
three zones, the contact piece-carrier zone 10, the winding post-carrier 
zone 20 and the rotary safety zone 30 which are separated from one another 
by connecting bridges 8, 9 leaving radial recesses, whereby the connecting 
bridges 8, 9 lie one behind the other in a longitudinal direction of the 
casing 1 and every connecting bridge 8 or 9 extends over about 75.degree. 
of the casing periphery. 
In the contact element-carrier zone 10, the contact casing 1 is developed 
as an essentially cylindrical ring 11 which is graduated in order to form 
a projecting shoulder 12 in the direction toward the contact element 2, 
whereby the smaller outside diameter of the stepped ring 11 is not smaller 
than the diameter of the contact element 2. In the case of a winding 
contact inserted into a contact hole, the contact piece-carrier zone 10 is 
located in a corresponding constriction of the hole against which, as is 
customary in the case of plug connections, the shoulder 12 abuts in order 
to prevent a pulling out of the winding contact in case of disengagement 
of the plug connection which, however, permits a certain freedom of 
movement in radial direction for the contact element-carrier zone 10 of 
the contact casing 1 in order to facilitate the plugging together of the 
plug connection. 
In the winding post-carrier zone 20, the contact casing 1 is placed between 
the two connecting bridges 8 and 9 and forms a bearing block 21 for the 
winding post 3 with a flat supporting surface 22 (FIG. 4) which lies so 
far in the inside of the casing that the winding post 3 placed on it is 
coaxial with the stepped ring 11 of the contact element-carrier zone 10 
and the contact element 2 itself. Effectively, transverse grooves 23 are 
provided in the supporting surface 22, in which projections of the winding 
post 3 engage in order to better secure the winding post against 
longitudinal shifting. On the support-surface 22, the winding post 3 is 
attached in such a way that torques acting upon it are transferred to the 
contact casing 1. For this purpose, flaps 24a, 24b protruding laterally 
from the bearing block 21 shown by way of example in the embodiment are 
provided, which flaps are bent around the put on winding post 3 and hold 
the latter firmly against the bearing block 21 of the contact casing 1 in 
a crimp connection. 
In the rotary safety zone 30, following the connecting bridge 9, the 
contact casing 1 in the upper half of the casing in relation to the 
connecting bridge 9 at the end of the casing has a crimping section 41 and 
a centering section 40 following the former in an inward direction, which 
sections are separated from one another by an incision 31a and which have 
a lower half of the rotary safety zone 30 connecting with the connecting 
bridge 9 as a common base part 32. The centering section 40 is made up by 
two centering flaps 35a, 35b starting out laterally from the base part 32 
which are bent together and which abut on the longitudinal joint 37 in 
order to form with the base part 32 of the rotary safety zone 30 a winding 
ring encircling the winding post 3 at a distance, which ring fits into a 
contact hole 5 (FIG. 3) of the housing 4. In the area of the centering 
section 40, the contact casing 1 in its cross section has approximately 
the shape of a bent in oval or of an open eight, as is shown in FIG. 3. 
The base part 32 has a flat bottom 33 which passes over into the 
connecting bridge 9 and the two lateral wave-shaped, flared indentations 
34a, 34b lie partly in the base part 32 and for the other part in the two 
centering flaps 35a, 35b, the free ends of which 36a, 36b abut against 
each other on the longitudinal joint 37. The centering section 40 of the 
rotary safety zone 30 has the task of balancing out tolerances of the 
contact hole 5 in the housing 4 and to keep the inserted winding contact 
centered in the contat hole 5, whereby the indentations 34a, 34b act as 
spring elements and keep the longitudinal seam 37 closed. For an easy 
insertion of the contact casing 1, into a contact hole 5, the centering 
section 40 is developed conically preferably in the area of the 
longitudinal seam 37, as shown in FIG. 4 at 38. 
The clamping section 41 of the rotary safety zone 30 comprises two clamping 
arms 42a, 42b projecting upwards from the base part 32, which are 
separated from the centering flaps 35a, 35b by the incisions 31a, 31b and 
are shorter than the latter. The clamping arms 42a, 42b are directed 
upwards away from the deepest points of the indentations 34a, 34b from the 
bottom 33 of the base part 32 and transversely toward the outside (FIG. 2) 
and at their narrow sides 43a, 43b they have sharp edges forming corners. 
In the case of each clamping arm 42a, 42b, the outside corner farther from 
the centering section 40 serves as a clamp 44a or 44b, whereby the 
clamping arms 42a, 42b in addition are twisted in such a way that the 
clamps 44a, 44b project beyond the outside periphery of the centering 
section 40, the outside corners 45a, 45b close to the centering section 40 
however lie within it, so that these corners 45a, 45b form no resistance 
in the case of insertion of the contact casing 1 into a contact hole 5 
(FIG. 2) and only the clamps 44a, 44b are forced into the perforated wall 
6. 
During the insertion of the winding contact into a contact hole, the 
centering section 40 in the rotary safety zone 30 is compressed by the 
conic surface 38 (FIG. 4) gliding on the perforated edge of the hole, so 
that, as can be seen from the cross section of FIG. 3, the longitudinal 
seam 37 is closed and the centering section 40 is forced against the wall 
6 of the hole of the contact hole 5 firmly by the tension of the 
indentations 34a, 34b acting as spring elements at the two narrow sides, 
that is to say in the area of both sides of the longitudinal seam 37 and 
in the area of the bottom 33 of the base part 32, and furthermore the 
clamps 44a and 44b projecting laterally beyond the periphery of the 
centering section 40, as shown in FIG. 2, are pressed more or less deeply 
into the wall of the hole depending on the hardness of the housing 
material. The contact casing 1 anchored in such a manner at two points in 
the contact hole 6 by the two clamps 44a, 44b of the clamping section 41 
ensures a firm seat of the winding contact in the contact hole 6, whereby 
the winding post 3 is centered in the contact hole 6 and the longitudinal 
seam 37 of the centering section 40 remains closed even whenever in the 
case of producing or detaching of a plug connection, the contact casing 1 
is moved somewhat laterally in radial direction in the area of the contact 
element-carrier zone 10 (FIG. 1) since such small lateral movements 
practically have no influence on the centering section 40 and on the 
clamping in the clamping zone 41 in the case of the distance of the rotary 
safety zone 30 from the contact element-carrier zone 10. 
Whenever in the case of making a winding contact, a torque is exerted on 
the contact element 2 or on the winding post 3, then it is transmitted by 
way of the heating block 21 (FIG. 1) of the winding post-carrier zone 20 
and the subsequent connecting bridge 9 to the base part 32 of the rotary 
safety zone 30, which base part is in common to the centering section 40 
and the clamping section 41. In the case of the centering section 40 (FIG. 
3), a torque tends to widen the longitudinal seam 37 and the enlargement 
of the periphery of the contact casing 1 in this area to be sure, but as a 
result of the resilient action of the indentations 34a, 34b and as a 
result of the perforated wall 6, this tendency is blocked, so that the 
longitudinal seam 37 will always remain closed and the centering section 
40 will also not spread apart in the area of the longitudinal seam 37. In 
the case of the clamping section 41 (FIG. 2), a clockwise torque (solid 
arrows) brings about that the clamp 44a of the in FIG. 2 left-hand 
clamping arm 42a will be more strongly forced into the perforated wall 6 
and a corresponding effect shows a torque counterclockwise (broken arrows) 
in the case of the in FIG. 2 right-hand clamping arm 42b. Because of the 
mechanically solid connection of the clamping arms 42a, 42b with the 
centering section 40 and its always closed longitudinal seam 37, the 
penetrating depth of the clamps 44a, 44b is limited to the maximum value 
given as a result of the projection of the clamps 44a, 44b beyond the 
periphery of the centering section 40, so that even in the case of a 
housing 4 consisting of a soft plastic, for example, a thermoplast, the 
clamps 44a, 44b could not be pressed into the hole of the wall 6 beyond 
this maximum penetrating depth and thus even in the case of a repeated 
insertion of a winding contact into the contact hole 5, only a slight 
damage of the contact hole wall 6 is ensured. 
FIG. 5 shows a preferred spring plate blank 1' for the production of the 
previously described contact casing 1. The blank 1' which is symmetrical 
in relation to a center line 14, has in the area of the three zones 10, 
20, 30 a strip-shaped middle area 15 in the width of the bearing block 21 
from which at both longitudinal sides at one end, flaps 11', 11" start off 
for the formation of the stepped ring 11 (FIG. 1) of the contact 
element-carrier zone 10, in the middle flaps 24a', 24b' for the squeeze or 
crimping flaps 24a, 24b of the bearing block 22 and following that, flaps 
32', 32" for the formation of the two sides of the base part 32 of the 
rotary safety zone 30 with the centering flaps 35a, 35b separated from one 
another by transverse incisions 31a, 31b and clamping arms 42a, 42b. The 
centering flaps 35a, 35b have slanting narrow sides 36a, 36b for the 
formation of the conical area 38 (FIG. 4) and the clamping arms 42a, 42b 
have narrow dies 43a, 43b, preferably parallel to the center line. The 
strip-shaped, middle area 15, as is clear from FIG. 4, is bent along the 
center line 14 in such a way that in the case of the contact casing 1, in 
the contact element-carrier zone 10, the radii of the stepped ring 11 
result, in the winding post-carrier zone 20, the bearing block 21 results, 
and in the rotary safety zone 10, the bottom 33 of the base part 32. The 
flaps 11' and 11" are bent in the shape of a circular arch with adjacent 
narrow sides so that the stepped ring 11 with the longitudinal seam 13 
(FIG. 1) will result, the flaps 24a' and 24b' are bent U-shape in order to 
facilitate the making of the squeezing or crimp connection after placing 
the winding post 3 onto the bearing block 22 and the flaps 32' and 32" 
with the centering flaps 35a, 35b and the clamping arms 42a, 42b are bent 
into the shape provided for the rotary safety zone 30. FIG. 6 shows three 
steps of a bending process possible for the formation of the rotary safety 
zone 30. 
In order to maintain the rotary safety zone 30 in the form described above, 
the clamping arms 42a and 42b are bent downwards in the case of a flat 
spring plate blank 1' in a first bending step (FIG. 6a) in such a way for 
example, that the lower corners distant from the incisions 31a, 31b (FIG. 
5) forming the clamps 44a and 44b project beyond the underside of the 
blank, the corners close to the incisions 31a, 31b however, remain at the 
sectional areas. In a second bending step (FIG. 6b), the centering flaps 
35a and 35b are arched and in a third bending step (FIG. 6c), the flaps 
32' and 32" are bent upwards in order to form the bottom 33 of the base 
part 32 and are bent laterally outwards, in order to maintain the 
indentations 34a and 34b. Such a production of the contact casing 1 from 
spring plate blanks 1' is best suited for an economic mass production. 
With the previously described contact casings 1, the winding contacts can 
be mounted easily and inserted into contact holes, whereby a reliable seat 
of the winding contact in the contact hole will be guaranteed.