Captive ball and socket joint

A captive ball in a socket joint made with a minimum number of units capable of mass production and readily assembled with minimum labor. The ball and socket structure enables easy connection of the ball component to a machine element via open access to the ball component for a power driven tool, such as a pneumatic, rotary driver. The socket unit is a single unitary lug-shaped stamping made from flat sheet metal in which a socket recess with a spherical bottom is stamped or formed with a slotted aperture therethrough. The ball unit is a single unitary screw the head of which is ball-shaped and includes an integral drive device in the ball head. The screw-threaded shank of the ball unit projects through the socket unit aperture with the ball-head received in the socket recess. The slotted aperture permits universal swiveling movement of the ball unit relative to the socket unit. A nut, on the ball unit renders the ball unit captive in the socket unit. The nut is retained in the desired position by conventional cement, lock thread formation or other well known self locking screw and nut structure.

BACKGROUND OF THE INVENTION 
This invention relates to a captive ball and socket joint which is used to 
movably connect two machine elements in a universal manner. Such machine 
elements can be links, levers, and fixed elements such as brackets. This 
invention was developed and will be described in connection with 
automotive link components, namely counterbalance links such as gas 
springs, the two ends of which are connected to and provide a linkage 
between two relatively movable components of the automobile, e.g., the 
trunk and trunk closure lid. The connection joints are sometimes ordinary 
pivotal joints but it is becoming more preferable to use ball and socket 
joints which permit a universally movable pivot connection between the two 
ends of a gas spring and the automotive elements when the link or gas 
spring is not mounted perpendicular to the closure lid hinge center line, 
thereby necessitating an attachment with omnidirectional capability. 
Components such as gas springs are usually furnished for installation with 
part of the end connections, usually an apertured lug or a socket, welded 
or prefastened to the ends of the gas spring. When the spring link is 
installed, the support part of the joint is normally fastened to the 
automobile body or a bracket on the trunk or hatch lid. When the spring 
link is installed with sockets to be mated with a ball, some form of clip 
or separate fastening device is then installed and holds the ball and 
socket together. It is desirable that the element, e.g., spring link, be 
preassembled with complete ball and socket end joints, the ball component 
being held captive in the socket component so they will not become 
separated. The worker then merely has to place the ball component in the 
desired location on the automobile component and secure it in place. 
Ball and socket joints have been proposed in which, when assembled, the 
ball component is retained captive in the socket but either the ball 
component or the socket component or both components are each made from 
multiple elements which require multiple parts to be assembled to result 
in the captive ball in socket joint. 
SUMMARY OF THE INVENTION 
The inventive captive ball in a socket joint is made with a minimum number 
of basic units which can be mass produced, and readily assembled with a 
minimum amount of labor steps, saving time and cost in both production and 
assembly. Moreover, the ball and socket structure is so arranged to permit 
rapid connection of the ball component to a machine element because of 
clear and open access to the ball component for a power driven tool, such 
as a pneumatic, rotary driver. The socket unit is a single, unitary, 
lug-shaped stamping made from flat sheet metal in which a socket recess 
with a spherical bottom is stamped or formed with a slotted aperture 
therethrough. The ball unit is a single unitary screw the head of which is 
ball-shaped and includes an integral drive device in the head. The 
screw-threaded shank of the ball unit is inserted through the socket lug 
aperture so the ball-shaped head is received in the socket recess, and the 
slotted aperture permits universal swiveling movement of the ball unit 
relative to the socket unit. A nut, screwed on the ball unit threaded 
shank to a position spaced from the lug renders the ball unit captive in 
the socket unit. The nut is retained in the desired position by 
conventional means such as cement, lock thread formation or other well 
known self locking screw and nut construction. 
The socket lug can be secured by welding, threaded portions or other 
attachment devices to whatever machine element, e.g., levers, links and 
other structures, are being assembled with a captive ball and socket end 
connector joint. The ball unit and its locking nut can be assembled to the 
socket unit before or after the socket lug is secured to its machine 
element. 
Various examples of ball and socket joints are seen in the following U.S. 
Pat. Nos. 2,513,637 to A. G. Herreshoff et al and 2,854,266 to H. F. Dies 
are two examples of many ball and socket joints with supplemental sheet 
metal clips retaining the ball unit in a socket lug; U.S. Pat. Nos. 
2,601,875 to E. V. Dardani and 3,097,005 to H. Fickler show examples of 
ball and socket joints where the socket unit is assembled from at least 
two joined sheet metal parts and the ball and stud are made from either 
one or two separate parts; U.S. Pat. Nos. 844,421 to B. E. D. Stafford and 
1,293,374 to E. I. Dodds are early examples of captive ball and socket 
joints wherein a separate retaining plug in the socket portion holds the 
ball unit in place, the ball unit having a screw driver kerf in the ball 
head of a stud; and U.S. Pat. Nos. 410,570 to S. Arnold and 1,265,445 to 
J. J. Hagen are examples of single piece socket unit and a single piece 
ball unit on a screw shank. The latter are the closest prior art but both 
have molded or machined socket units, neither one teaches the concept of a 
single unitary socket unit stamped from flat sheet metal. 
The present invention has for a primary object the provision of a ball and 
socket joint in which the socket is a single unitary piece made from a 
piece of flat sheet metal, the ball and its attachment stud or shank is 
received in the socket unit and can be held captive therein by a member 
secured on the ball stud below the socket unit after the ball unit is 
placed into the socket. 
Other novel features reside in the provision in the aforementioned ball and 
socket joint of the socket unit being in the form of a lug stamped from 
flat sheet metal with a socket forming recess formed to extend from one 
side of the lug and having a cylindrical wall and spherical bottom, the 
bottom being pierced with a slotted aperture, enabling the stud portion of 
the ball unit to project therethrough with the ball portion seated in the 
socket recess below the top face of the socket lug. Furthermore the ball 
unit stud may be screw threaded and made to receive a nut to render the 
ball unit captive in the socket lug. The nut may be rendered rigid in its 
desired location on the ball stud by suitable so-called nut locking 
adhesives or structure. The positioning of the nut can predetermine the 
extent of swivel or universal joint movement between the ball and socket 
units. 
Further novel features and other objects of this invention will become 
apparent from the following detailed description, discussion and the 
appended claims taken in conjunction with the accompanying drawings.

GENERAL DESCRIPTION 
A preferred complete assembly of the captive ball and socket joint herein 
described is shown used as the connectors at both ends of the machine 
element seen in FIG. 2, and details of the units of the ball and socket 
joint are described relative to FIGS. 3-6. 
The gas spring link 10, generally depicted in FIGS. 1 and 2, is shown as an 
example of a machine element to which the ball and socket connector joint 
can be attached. The gas spring 10 is a link which can be extended and 
retracted and includes a cylinder 12 and a reciprocable shaft 14. FIG. 2 
shows two captive ball and socket joints 20, one rigidly mounted on the 
end of link cylinder 12 and one mounted on the end of the link shaft 14, 
as by welding 16, or other suitable means. 
The preferred ball and socket joint 20 includes a socket unit 22, a ball 
stud unit 24 and a bushing unit 26. In the preferred embodiment, bushing 
26 is a hexagonal steel nut 26 to which a conical washer 28 is rotatably 
mounted. Socket unit 22 is made from flat sheet metal which can be of a 
thickness to be determined by the size and use of the joint. The parts in 
FIG. 3 are drawn to the same scale from an exemplary ball and socket joint 
and the thickness of the sheet metal (CRS 1008 or 1010) from which the 
socket lug was made was approximately 0.12 mm. If deemed desirable, the 
dimensions of the other parts can be determined from the scaled 
depictions. 
Socket unit 22 can be mass-produced by stamping which can cut the lug shape 
of FIG. 5, pressure deform the socket recess 30 and pierce the aperture 32 
in the recess 30 in a single pressure stamping operation. Recess 30 is 
made by forcing the sheet metal from one flat face into a protrusion which 
has a cylindrical wall 32 portion and a hemi-spherical bottom 34, the 
portions 32 and 34 being dimensioned with a radius to completely receive 
the partially spherical ball head 36, which will be referred to broadly as 
ball 36, of the ball stud 24 in the recess with a close free fit. During 
the same operation, or in a second step in the socket lug forming process, 
the socket recess is pierced to form the slotted aperture 38. 
The aperture 38 through the socket recess 30 is shaped at its midpoint 40 
with a diametral dimension enabling passage of a threaded shank 41 of the 
ball-stud 24. As seen in FIGS. 3 and 5 the slot aperture 38 extends 
longitudinally of the socket lug 22 into the spherical walls 34 and the 
cylindrical walls 32 of the socket recess 30 at 42 and 44. These 
extensions of the slot need not be as wide as the midpart and are to 
permit a swiveled movement of the ball unit in a longitudinal direction 
relative to the socket unit. Varying the width and length of the slot 
extensions will control the extent of longitudinal angular swivel movement 
and varying the diametral dimension of the mid portion 40 of the slot can 
permit more or less lateral relative swivel movement of the ball stud and 
socket if desired. The mid portion 40 of the slot must have at least a 
dimension enabling passage of the threaded portion of the ball stud 24, 
but not the ball head, for assembly purposes. 
Ball stud 24 is a single unitary screw or bolt with a head end, shaped as a 
truncated portion of a spherical ball 36, and a threaded stud portion. 
Note, as shown in FIG. 7, at least the base portion 37 of the ball head 
36' should be spherically contoured to seat in the spherical bottom 34 of 
the lug socket recess 30. The threads 41 terminate a spaced distance from 
the head 36 leaving a cylindrical portion 46 which in assembly is disposed 
with a free fit in the slotted aperture 38. The cylindrical portion 46, as 
shown in FIG. 3, has a smaller diameter than that of the threaded portion 
41, but its diameter can be made larger if desired, as long as it is 
smaller than the diameter of the ball head 36. For example, portion 46 can 
be the same size as the O.D. of the threads or, as shown at 46' in FIG. 7, 
it can be made with a larger diameter than that of the threads, it being 
understood that the width of the slotted aperture 38 in the socket lug 
will be made larger to provide a free fit for the portion 46'. By making 
the aforesaid cylindrical portion 46' a larger diameter than the O.D. of 
the threads, a shoulder 47 is provided, against which the steel nut 26 can 
be seated and thereby located at a desired predetermined distance from the 
base of the ball portion 36. As shown the ball stud 24 is made for use in 
connecting automotive components and has provision of plural flutes 48 on 
the end of the threaded shank to provide thread cleaning and chasing of 
mating female threads in the mounting structure, e.g., an automobile frame 
or bracket component (not shown). 
The ball head 36 is made with a "TORX" drive recess 50, which permits 
screwing of the ball stud by a rotary power driven tool (not shown). 
Provision for receiving such a tool by the ball head 36 can be other 
structure, such as screw driver kerfs, polygonal recesses or protrusions. 
In an event, the drive structure on the ball stud head will be completely 
accessible from the flat face side of the socket lug 22. 
The bushing 26 could be a collar or other similar component rigidly located 
and fastened by crimping, welding or other known means to the ball stud 
24, in a location as shown in FIG. 3, in order to make the ball captive in 
the socket. A preferable bushing is the steel nut 26 as depicted which is 
threaded onto the threaded shank of the ball stud after the stud is 
projected through the socket aperture 38. The nut serves as a bushing 
flange between the exterior surface of the socket recess 30 and the ball 
stud 24, and can determine the extent of swivel movement if desired. When 
properly located on the ball stud 24, the nut is rendered essentially 
rigid with the stud by Locktite thread cement or deformation or otherwise, 
and in effect the threaded ball stud can be screwed into another machine 
structure or component, e.g., automobile body, closure, lever, etc., by 
using a wrench on the hexagonal nut although access is not always 
convenient. As shown, nut 26 is made with a deformable sleeve 52 at one 
end. A special conical or bellville washer 28 is placed on the sleeve 52 
which is then deformed to retain the washer 28 with freedom to rotate 
relative to the nut. When the combined ball stud and nut are screwed into 
an automobile part the washer is forced against and flattened against the 
automobile part by the nut to provide an effective high retention torque 
force retaining the ball stud to the mounting part. 
The previously described joint 20 is adaptable for use in several ways. It 
can be preassembled as a subassembly, captive ball-in-socket joint 
consisting of the socket lug 22, ball headed stud 24 and a bushing 26. At 
any time, as needed, the subassembly can then be rigidly fastened to a 
machine element, e.g., bellcrank, link, etc., by suitable means such as 
welding the end of lug 22 to a part of the machine element. An alternate 
mounting of either or both lugs 22 can be angled relative to the spring 
centerline, as shown by the phantom line lug 22' in FIG. 2, to accommodate 
mounting the spring unit on a support structure which is not necessarily 
parallel to the spring center line. Another way to mount the joint, which 
in certain assemblies might be preferable, is to first rigidly fasten the 
lug to the machine element, as by welding, and later on complete the 
assembly of the ball stud with the bushing or nut to render the ball 
captive in the socket lug. The later procedure is preferable when making 
an attachment of the connection to the shaft and/or cylinder of a gas 
spring because the simple flat socket lug can be welded on the gas spring 
components before they are assembled and will not interfere with 
procedures in automated assembly of the gas spring itself. Furthermore it 
is possible that where the end of a lever or like is to include the socket 
part of a captive ball in a socket arrangement, the lever, or lever arms 
of a bellcrank, could be stamped and shaped in the manner described for 
the sheet metal socket lug so that the socket component will be an 
integral part of a unitary sheet metal lever member. 
The apertured base of the socket recess could be initially deformed so the 
walls are spread apart a distance sufficient for the ball stud to be 
inserted up through the apertured slot. The socket recess walls then 
swaged inwardly to form the slotted socket recess entrapping the ball. If 
assembled in such a manner, the ball and stud with retaining bushing, 
hexagonal or other shape, could be made as a single structurally integral 
part, and the captive ball and socket joint would then consist of but two 
elements. 
The invention may be embodied in other specific forms without departing 
from the spirit or essential characteristics thereof. The present 
embodiment is therefore to be considered in all respects as illustrative 
and not restrictive, the scope of the invention being indicated by the 
appended claims rather than by the foregoing description, and all changes 
which come within the meaning and range of equivalency of the claims are 
therefore intended to be embraced therein.