Abstract:
A ball-and-socket joint for motor vehicles provided, with a joint ball and a pivot pin, a housing part formed of a shaped metal tube having a top end with an opening and having an opposite end with a pivot pin opening through which the pivot pin protrudes and with a molded material molded on a portion of the housing, the molded on material forming functional surfaces on each of an inside and an outside of the housing part.

Description:
FIELD OF THE INVENTION 
   The present invention pertains to a ball-and-socket joint, preferably for motor vehicles, in which a joint ball formed on a pivot pin is mounted movably in a bearing shell consisting of a plastic or other similar material and the bearing shell is surrounded with a housing which provides support to the assembly. The invention also pertains to a process for forming a ball-and-socket joint. 
   BACKGROUND OF THE INVENTION 
   Such ball-and-socket joints of this type are widely used in mechanical engineering, especially in the automotive industry. Ball and socket joints are often made of a housing part that is generally tubular or cup shaped and includes a bearing shell (race insert) that is positioned within the housing part. Additionally, an end plate is sometimes used to close one end of the structure and a bellows (boot) is used connected to the bearing pin and to the housing at the other end. Other structural parts are provided for sealing connections. These include a boot seal or bellows seal structure that provides a seat for the bellows and provides a sealing function. Some ball and socket joints also include further sealing structures cooperating with the bearing shell or otherwise provided to maintain protection in the region of the ball joint. 
   A ball-and-socket is known from DE 296 07 587.6 &amp; DE 296 16 350.3. Such ball-and-socket joint has a ball surrounded by a bearing shell which is molded-in-place or cast in place. To create the joint, a joint housing is held fixed in place and a ball portion of a bearing pin is located within the joint housing with the bearing pin being fixedly held in place to maintain location of the ball portion within the joint housing. A material is then molded-in-place (such as by injection molding) or cast in place between the joint housing and ball portion thus forming the bearing shell. 
   Prior art constructions have proven quite effective in use. However, most designs require significant numbers of manufacturing steps and some sophisticated designs are quite labor-intensive with regard to manufacturing. 
   SUMMARY OF THE INVENTION 
   It is an object of the invention to provide a ball-and-socket joint that may be manufactured economically with few steps and is simple in design and rugged in construction. According to the invention to a ball-and-socket joint for motor vehicles or similar applications has a joint ball incorporated as part of a pivot pin. The pivot pin is commonly used as a mounting for the ball-and-socket joint to a control arm or other component of a motor vehicle. A joint ball resides within the ball-and-socket joint and acts as the point around which the ball-and-socket joint allows articulation. A housing is formed of a shaped metal tube. The housing has a top end with an opening and an end, opposite to the top end, with an opening through which the pivot pin protrudes for connection with the vehicle component. A material molded directly on the housing is used to form a functional surface or surfaces on the inside of the housing where the functional surface serves as a bearing shell for the joint ball, and or on the outer surface of the housing where the molded material can serve as a mounting for a bellows, or other type of sealing element. 
   The molded material forming the inner and outer functional surfaces can be continuous and follow around an edge of the housing as it transitions from one surface to another. Molded in ties can be formed in the molded material, these ties passing through openings or holes in the housing part, thus connecting the inner and outer functional surfaces, positively locking them in relation to the housing part. The bearing shell surface can likewise form a bearing surface for the joint ball which is a contact surface in contact with effectively the entire usable bearing surface of the joint ball. 
   Extension segments (petals) of the molded material can be formed, integral with the molded material and extending from a region of the bearing shell portion of the molded material. The petals utilize an integral hinge or flexible section so they may be folded about the joint ball after the joint ball is inserted into the bearing shell portion of the molded part. The petals, after being folded over, form a remainder of the bearing shell surface in functional contact with the joint ball. The petals are molded with a concave shape on their inner surface so as to correspond to the shape of the joint ball to which they will interface. Often the joint ball will contact the bearing shell and petal surfaces in less than the entire usable joint ball bearing surface. 
   As an alternative to the petals being folded into functional contact with the joint ball, a bearing shell insert can be inserted in the housing adjacent to the molded bearing shell portion. The bearing shell insert may have a bearing surface which cooperates with the molded part to form an adequate bearing interface surface for the joint ball to bear on. 
   As a further alternative, the molded part forming part of or the entire bearing surface can be molded outside the housing and then inserted with, or inserted before, the joint ball into the housing. 
   An end cap may be used to close the opening in the housing top end after insertion of the molded bearing shell and any other bearing shell forming parts, along with the joint ball/pivot pin, into the housing. The end cap is held in place in the opening by a rolling over lip which is rolled over or pressed onto the perimeter of the end cap to retain the end cap in place, thus closing the opening. The end cap can also provide a pre-load on the molded part (bearing shell) against the joint ball to achieve a desired force requirement for movement of the joint ball relative to the bearing shell in rotation and pivoting alike. The folded area can be pressed or crimped onto a lip incorporated into the molded part to lock the molded part to the housing after molding in place or insertion of the molded part. 
   Ribs or other surface texturing features such as knurling can be incorporated into the inner surface of the housing part. The ribs are located in the areas where the molded part is either molded to the housing, or where the molded part, if pre-molded outside the housing, is to come into contact with the housing part. The ribs form an interference fit with the molded part, biting into the molded part and thus preventing a rotation of the molded part relative to the housing as the ball-and-socket joint is used. Ribs may also be used on the outside of the housing part to form an interference fit with the component into which the joint is being mounted. This interference fit prevents a rotation of the housing relative to the component into which it is mounted. 
   Manufacturing of the ball-and-socket joint can be performed starting with a tube which is rolled, spun or hydroformed etc. into a profiled tube comprised of repeated formed sections of housing parts. These sections are then cut to form individual housing parts. In comparison to traditional forming methods, which can also be used to manufacture the housing parts, the cutting of the individual housing parts from the profiled tube avoids the waste associated with flange areas of traditional stamping processes. 
   The individual housing part is then placed in a mold space or fixture where material is injection molded, or otherwise molded, or cast, into the space provided in the mold between an inner mold contour and outer mold support elements onto surfaces of the housing part. The resulting part molded onto the housing part has the functional surfaces incorporated therein to interact with the joint ball as the bearing surface upon which the joint ball acts. A boot groove for the retention of a sealing bellows may be incorporated into the molded part in addition to the joint ball surface and any other functional surfaces of the molded part. The molded part may wrap around the lip of the housing part as it transitions from one functional surface to the next. Holes or openings in the housing part may be incorporated. The holes provide a pass through for the molded material to join during molding from the outside of the housing part to the inside of the housing part thus forming ties. The ties help to affix the inner and outer functional surfaces of the molded part to each other, to resist separation from the housing part, and to prevent a rotation of the molded part relative to the housing part. 
   The molded part may also be molded as a component separate from the housing part, and then inserted into the housing part either prior to or in conjunction with the insertion of the joint ball. A second molded part can also be used to provide functional surface area for the joint ball where the molded part does not provide the entire bearing area needed for the joint ball. 
   The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of tubing used in a process according to one embodiment of the process of the invention; 
       FIG. 2  is a partial sectional view of the tube of  FIG. 1  after a stamping or other shaping procedure; 
       FIG. 3  is a sectional view showing the machined tube of  FIG. 2 , indicating locations for cutting; 
       FIG. 4  is a sectional view showing a further shaping procedure for a housing part of the ball and socket joint according to the invention; 
       FIG. 5  is an illustration of further shaping procedure according to an embodiment of the process of the invention; 
       FIG. 6  is a sectional view of a housing part for the ball and socket joint according to the invention; 
       FIG. 7  is a sectional view showing a molding procedure with surface portions molded upon the housing part; 
       FIG. 8A  is a sectional view showing the particulars of the molded portion according to an embodiment of the invention; 
       FIG. 8B  is an perspective view of the molded part according to the embodiment of  FIG. 8A ; 
       FIG. 9  is a top view of the embodiment  FIG. 8A ; 
       FIG. 10  is a top view of an alternative to the embodiment of  FIG. 9 ; 
       FIG. 11  is a perspective view of the embodiment of  FIG. 8A  showing a stage of the manufacturing process according to the invention; 
       FIG. 12A  is a sectional view illustrating a step in the manufacturing process for forming the ball and socket joint according to the embodiment of  FIG. 8A ; 
       FIG. 12B  is a sectional view illustrating another step in the manufacturing process for forming the ball and socket joint according to the embodiment  FIG. 8A ; 
       FIG. 12C  is another sectional view illustrating another step in the manufacturing process for forming the ball and socket joint according to the embodiment of  FIG. 8A ; 
       FIG. 13  is a sectional view of the final assembled ball and socket joint according to the embodiment  FIG. 8A ; 
       FIG. 14  is the exterior view of the assembled ball and socket joint according to the embodiment of  FIG. 8A ; 
       FIG. 15  is a sectional view showing an assembled ball and socket joint according to an alternative embodiment of the invention; 
       FIG. 16  is a cutaway sectional view showing an assembled ball and socket joint according to another alternative embodiment; 
       FIG. 17A  is a sectional view showing an assembled ball and socket joint according to another embodiment of the invention produced by an alternate process according to the invention; 
       FIG. 17B  is an enlarged detailed sectional view of the embodiment of FIG.  17 A; 
       FIG. 18A  is a sectional view of a one-piece bearing shell according to another embodiment of the invention; 
       FIG. 18B  is a sectional view showing an assembled ball and socket joint using the bearing shell of the embodiment  FIG. 18A ; 
       FIG. 19A  is a sectional view of the housing part in a press forming step; 
       FIG. 19B  is a sectional view of the housing part similar to that of  FIG. 19A ; 
       FIG. 20  is a perspective view of the housing part with outer ribbing; 
       FIG. 21A  is a view of a ribbed housing part prior to insertion of a molded part; 
       FIG. 21B  is a view of the components of  FIG. 21A  after assembly; 
       FIG. 22A  is a view of the joint showing the end cap with the rolled over edge shown in dashed lines; 
       FIG. 22B  is a sectional view of the housing part prior to folding over of an edge on the molded part; and 
       FIG. 22C  is a sectional view of the components of  FIG. 22B  after folding of the folding over edge. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to the drawings in particular,  FIG. 1  shows tubing  5  that can be used according to a process for forming a ball and socket joint according to the invention. The tubing  5  is shaped in a shaping process to produce a shaped tube generally designated  7  ( FIG. 2 ). The shaping process of the tube may utilize techniques such as hydroforming, rolling, etc. The shaped tubing  7  includes contours such as contour  9  forming the base for a bellows support groove. As illustrated in  FIG. 3  the shaped tube  7  is cut at cutlines  11  to form several housing parts  10  of a desired length. The cutting of the tube may also be done in such a manner that a section of scrap material between the housing parts  10  is removed. This section of scrap material may be utilized to absorb excess runout material resulting from the forming process for the housing parts  10  and to allow for tolerances in the manufacturing process. As an alternative to forming a shaped tube which is subsequently cut into individual housing parts  10 , the housing parts  10  may be formed individually by numerous metal forming processes known in the art. 
   To provide a further shaping to the housing part  10 , the housing part  10  is subjected to a stamping procedure or other shaping procedure as illustrated in  FIGS. 4 and 5 . The support  12  is provided and optionally an interior support  14  is also provided to support the housing  10 . The supports  12  and  14  interact with a press  16 . This results in a stamped flange contour  18  as can be seen in  FIG. 6 . As shown in  FIG. 5 , the interior support sets the press fit diameter and corner radius of the interior of the housing part  10 , while the support  12  supports the outside diameter of the housing part and the flange contour  18 . The housing part  10  may optionally be cleaned after forming to remove greases, oils, and any other contaminants which may adversely affect subsequent manufacturing process, in particular the adhesion of molding or coating materials to the housing part  10 . 
   The housing part  10  is disposed at least partially in a mold  15  as shown in  FIG. 7 . The mold  15  has support surfaces for supporting the housing part. The support surfaces may include a support or supports of the exterior of the housing  10  which are not to receive a molded part. This supports the housing part  10  in the mold relative to the mold space. Injectable material is then injected into the mold space to form a molded part  20  with functional surfaces formed by injection molded material. As an alternative to injection molding of material to form part  20 , casting, compression molding or other methods known in the art may be utilized to form the molded part  20 . The functional surfaces of the molded part  20  include a race surface or bearing surface  24  for the ball  3  as well as a sealing boot groove or bellows seal seat  22 . The functional surfaces also may include functional surfaces formed for interaction with the pivot pin  2  and with a top of the ball  3  as shown in  FIG. 13 . In the embodiment of  FIG. 13  (see also  FIG. 8A  and the molding step of  FIG. 7 ) the bearing surfaces for interaction with the top of the ball  3  are provided by integrally formed petals or segments  26 . Other functional surfaces may be provided including surfaces for lubricant sealing at the race or near the pivot pin  2  of the ball pivot  1 . 
     FIG. 8A  depicts the ball  3  seated in the bearing surface  24  of the molded part  20  from the molding procedure of  FIG. 7 . The housing part  10  now has the molded part  20  molded onto it. The molded part includes a folded area  28  connecting the segments  26  to the remaining portion of the molded part  20 . The segments  26  are fold at the folded area  28  to provide an upper bearing surface for the ball part  3  of the ball pivot  1 . 
     FIG. 8B  illustrates the feature of the segments  26  and illustrates the direction of folding of the segments  26  with respect to the folded area  28 . The process including the molding procedure of  FIG. 7  results in an integral unit that provides bearing surfaces at an upper portion, at a middle portion and at a lower portion of the ball pivot  3  (full bearing surface or race) as well as the boot groove or seat  22  for the upper portion of the bellows seal  34  as shown in  FIG. 13 . 
   The segments  26  allow for a manufacturing process in which a single injection or otherwise molding step forms the various surfaces as noted above. The segments  26  may be provided in a convenient number such as the six segments  26  shown in  FIG. 9  or the four segments  26  shown in  FIG. 10 . The exact number of the segments may be related to the diameter of the over all bearing which is available. The number of petals or segments  26  can also be related to the diameter of a rollover lip/edge  32  of the housing part  10  (see  FIG. 11 ). The number of segments  26  may also be selected to optimize the overall ball and socket joint with regard to torques and elasticities. 
   The segments themselves are preferably slightly curved as shown in  FIG. 8A  relative to the remainder of the molded part  20 . The folded area  28  may also include a curved section in the transition between the segment  28  and the remaining portion of the molded part  20 . A slight curve to the structure results in segments being pulled down slightly as the ball is popped into the bearing surface  24 . This is based on insertion of the ball  3  from the top as shown in  FIG. 12A . Depending on the particular design, grease grooves may not be necessary in the molded part  20 , thus allowing more of the bearing surface  24  to contact the ball  3 , in turn providing greater wearing life for the joint. 
     FIG. 11  is a perspective view showing the housing part  10  with the molded part  20  molded thereto showing the bellows seat  22  as well as the segments  26 . The rollover lip  32  is shown in a position ready to interact with an end cap  30  as shown in  FIG. 12C . 
   The closure of the housing with the end cap  30  after the insertion of the ball pivot  1  is illustrated in  FIGS. 12A ,  12 B and  12 C. As shown in  FIG. 12A  the ball pivot  1  is inserted into the assembly of  FIG. 11  with the ball  3  urging the segments  26  into an open position. The segments  26  pivot or flex at the folded area  28  as the ball  3  is inserted into the interior of the housing  10 . As the pivot pin  2  is extended through the housing and the ball  3  is popped into position the segments  26  are pulled somewhat into position as shown in  FIG. 12B . This pulling of the segments  26  is based on the integral nature of the molded part  20  and is based on the shape of the segments  26  and folded area  28  as described above. As shown in  FIG. 12C  the end cap  30  pushes down upon the segments  26 . The roll over portion  32  (as shown in  FIG. 13 ) then rolls over the edge of the end cap  30 . The roll over process may also be used to influence the torques and elasticities of the resulting construction based on the large influence of the end cap  30  pressing the segments  26 . The torques and elasticities may be measured during the application of force on the end cap  30  until the desired range is reached and this range may be set by rolling over the edge  32  to freeze the joint at the selected values of torques and elasticities. 
   The shape of the segments  26 , particularly the interior facing bearing surface, can be varied in order to optimize the wear of this bearing surface. It is also possible to vary the force applied to the end cap  30  to optimize the wear of the bearing surface  24  and the bearing surface of segments  26 . During the procedure shown in  FIGS. 12A–12C  or prior to that, grease or another lubricant may be inserted into the region of the bearing surface  24 . The bearing surface  24  may also have grooves, or other cavities, to hold grease. 
   An assembled ball and socket joint is shown in  FIG. 13 . A bellows or boot  34  is applied with a closure ring  38  to the pivot  2  of the ball pivot  1 . The other end of the bellows  34  is connected to the boot or the bellows seat  22  via a holding ring  36 . The rollover edge  32  can be an edge of the end cap  30  to provide a closure to the interior of the ball and socket joint. 
     FIG. 14  shows the assembled ball and socket joint of  FIG. 13  in a side view.  FIG. 14  shows the bellows  34  as well as the ring  38  and ring  36 . Additionally a small portion of the molded part  20  can be observed, namely the portion at the upper edge of the surface  22 . The end cap  30  is shown closed off by the rollover edge  32 . 
     FIG. 15  shows an alternative design. The embodiment of  FIG. 15  is formed in manner similar to the embodiment of  FIG. 13 . However, the molded part  40  is different form the molded part  20  of  FIG. 13 . 
   Molded part  40  includes a lower portion with the bellows seat  42 . However, the race or bearing surface  24  is provided with a continuous upper and lower portion. The upper portion  46  is not segmented. With this design the ball  3  must be popped or forced into the single unsegmented molded piece  40 . The end cap  30  is applied as shown in  FIG. 15 . The end cap  30  provides a closure and gives support to the unsegmented upper portion  46 . 
     FIG. 16  shows still another embodiment of the ball and socket joint according to the invention. A molded part  50  is provided following a process similar to that described with reference to  FIG. 7 . However, the molded part  50  is provided along only a portion of the interior of housing part  10 . As such, the molded part  50  forms only a lower bearing surface portion  54 , forming only a portion of the overall race or interior bearing surface. Another molded race portion  56  (also made of plastic such as an injectable material) is inserted into the housing part  10  subsequent to inserting the ball pivot  1  to position ball  3  in the housing. The molded part  50  also includes the bellows seat surface  52  (the boot groove). 
     FIG. 17A  shows still another embodiment of the invention. A housing part  60  is formed by a stamping procedure. The housing part  60  is a cup shaped structure with a stamped or shaped flange part  68  as well as rollover edge  62 . This housing part  60  is inserted into a mold following a procedure similar to that described with reference to  FIG. 7 . This results in a molded part  70  which includes various functional surfaces. The functional surfaces include for example the race or bearing surface  76  in the interior of the housing  60  as well as a bellows seat (boot groove)  72 . The molded part  70  is an integral structure based on passages  64  which are filled with injection molded material and form an integral structure (connected at both sides through the passages  64 ). The rollover edge  62  provides a retaining function and extra support to the molded part  70 , supporting the race surface  76 . The through holes or passages  64  are best seen in  FIG. 17B . Instead of the housing part  70  being rolled over the race portion  74  (providing support for the race portion  74 ) a ring may also be provided. The embodiment of  FIG. 17A  requires a popping in of the ball  3  into the housing  60  based on the integral nature of the upper bearing portion  76  in the remainder of the bearing surface  74 . 
     FIG. 18A  discloses an alternative embodiment in which a molded part  80  is formed as a separate molded part. The molded part  80  includes interior bearing surfaces or race surfaces  84  and also includes integral attached segments  86  attached to a remainder of the molded part  80  by folded part  88 . The structure is formed as a single integral piece molded as a separate element from a housing part  90 . The molded part  80  is positioned within the housing part  90 . The housing part  90  may also include functional surfaces such as a bellows seat (boot groove)  94 . After disposing the molded part  80  within the housing part  90 , the ball  3  of the ball pivot  1  is inserted into the housing with the ball  3  in contact with the bearing surfaces  84 . An end cap  30  is then applied and rollover edge  92  closes the assembly. The petals or segments  86  are positioned with an interior bearing surface in contact with an upper portion of the ball  3 . 
     FIGS. 19A and 19B  show incorporation of housing interior ribbing  96  formed on the interior surface of the housing  10 . The housing interior ribbing  96  is formed as the interior support is pressed into the housing part  10  during manufacture, where interior support ribbing  97  on the interior support  14  forms the housing interior ribbing in the housing. Knurling or other surface disruption methods may also be used in place of ribbing. The housing interior ribbing is used to form an interference fit with the molded part  20  as the molded part  20  is inserted into the housing part  10 . The interference fit between the parts prevents the molded part  20  from rotating relative to the housing part  10 . 
     FIG. 20  shows a housing part  10  with housing outer ribbing  98 . The housing outer ribbing  98  is formed in a manner likewise to that used to form housing inner ribbing except that ribbing on the support  12  is used to form the housing outer ribbing  98  during pressing of the housing part  10 . The housing outer ribbing is designed to provide an interference fit between the housing and a component to which it is mounted, such as that of a tie rod end in an automobile, thus preventing a rotation of the housing part  10 , and therefore the aggregate joint assembly, within the component into which it is mounted. Knurling or other surface disruption methods may also be used in place of ribbing. 
     FIGS. 21A &amp; 21B  show the housing part  10  with the housing interior ribbing  96  (as shown in  FIGS. 19A &amp; 19B ) along with the ball  3  of the joint and the molded part  20  in both a pre assembled state ( FIG. 19A ) and a post assembled state ( FIG. 19B ) of the three components. During assembly the housing interior ribbing  96  cuts into the outer surface of the molded part  20  thus providing an interference fit. 
     FIGS. 22A to 22C  show methods of locking the molded part  20  from ejection from the housing part  10  after insertion into the housing part  10 .  FIG. 22A  shows an end cap  30  constraining the molded part  20 . The End cap  30  is then locked in place by rolling over the rollover lip  32  after placement of the end cap  30 . A pre-load or force can be applied to the molded part  20  and in turn to the ball  3  by the forcing of the end cap  30  against the molded part  20  as the rollover lip  32  is rolled over.  FIG. 22B  shows an alternate means of holding the molded part  20  in the housing part  10 . A folded area  28  protrudes to catch a lip on the molded part  20 . The folded area  28  is then pressed down crimping it onto the lip of the molded part  20  thus crimping it in place as shown in  FIG. 22C . 
   While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles. 
   APPENDIX  
   List of Reference Numbers: 
   
       
         1 . Ball pivot 
         2 . Pivot pin 
         3 . Ball 
         5 . Tubing 
         7 . Shaped tubing 
         9 . Contour 
         10 . Housing part 
         11 . Cut lines 
         12 . Support 
         14 . Interior support 
         15 . Mold 
         16 . Press 
         18 . Contour 
         20 . Molded part 
         22 . Bellows seat 
         24 . Bearing surface 
         26 . Segments 
         28 . Folded area 
         30 . End cap 
         32 . Rollover lip 
         34 . Bellows 
         36 . Ring 
         38 . Ring 
         40 . Molded part 
         42 . Bellows seat 
         46 . Upper portion 
         50 . Molded part 
         52 . Bellows seat surface 
         54 . Lower bearing surface portion 
         56 . Housing part portion 
         60 . Housing part 
         62 . Rollover edge 
         64 . Passages 
         68 . Flange part 
         70 . Molded part 
         72 . Bellows seat 
         74 . Race portion 
         76 . Race surface 
         80 . Molded part 
         84 . Bearing surfaces 
         86 . Segments 
         88 . Folded part 
         90 . Housing part 
         92 . Rollover edge 
         94 . Bellows seat 
         96 . Housing interior ribbing 
         97 . Interior support ribbing 
         98 . Housing outer ribbing