Abstract:
A method of manufacturing bearing seal for use in a roller bearing is provided. A steel coil of a preselected width is fed into a ring rolling machine to form a closed coil ring. The closed coil ring is then welded along the butted joint. The welded closed coil ring is then fed to a series of pre-forming machines wherein the desired profiles of the final bearing seal are formed.

Description:
FIELD OF THE INVENTION 
     This invention relates to roller bearings, and more particularly, to a method of manufacturing a seal component for a tapered roller bearing fitted on a railway freight car axle. 
     BACKGROUND OF THE INVENTION 
     Tapered roller bearings on railcar axles support operating loads capable of producing deflections in the axle, and in particular, the end portion of the axle comprising the journal on which the tapered roller bearing is affixed. The stresses imposed by the operating loads are particularly high in the journal portion of the shaft at or near the backing ring. 
     As result of shaft deflections, the backing ring and the journal often experience fretting wear as the backing ring moves relative to the journal. Fretting wear may be sufficient to loosen the backing ring, increasing the axial play of the bearing on the journal. The loose backing ring accelerates wear on the bearing assembly and journal, potentially leading to shaft or bearing failure. 
     It is desirable to retain lubricants in the form of oils or grease within the bearing while also excluding water and abrasives. Such lubricants are held within the bearing by means of a bearing seal, that is a generally ring shaped structure that usually includes a resilient seal member. 
     It is an object of the present invention to provide an improved method for the manufacture of a bearing seal. 
     SUMMARY OF THE INVENTION 
     The present invention provides an improved method of manufacturing a bearing seal component for a tapered roller bearing designed to be fitted on railway freight car axle. The method of the present invention is a significant improvement over the currently known methods which usually involve a stamping operation having several steps requiring dedicated stamping equipment and result in a significant amount of scrap. The method of the present invention involves the use of a sheet of steel, which is the usual material of which a bearing seal is comprised, of the exact width in material needs of the finished bearing seal, such sheet of steel cut and run is initially through a ring forming machine. The formed ring is then welded, and run through the necessary number of pre-forming operations to result in a final formed bearing seal. The method of the present invention is seen to be an improvement from a material use and efficiency point of view. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       In the drawings, 
         FIG. 1  is a sectional view of a first embodiment of the backing ring assembly in accordance with an embodiment of the present invention; 
         FIG. 2  is an enlarged sectional view of the first embodiment of the backing ring assembly in accordance with an embodiment of the present invention; 
         FIG. 3  is a perspective view of a prior art method of manufacture of a bearing seal; 
         FIG. 4  is a perspective view of the waste steel from the prior art method of manufacturing a bearing seal; 
         FIG. 5  is a perspective view of a finished bearing seal in accordance with an embodiment of the present invention; 
         FIG. 6  is a perspective view of a steel coil being fed into a ring forming machine in accordance with an embodiment of the present invention; 
         FIG. 7  is a perspective view of the removal of a weld bead in accordance with an embodiment of the present invention; 
         FIG. 8  is a perspective view of the weld bead being in a flattening operation in accordance with an embodiment of the present invention; 
         FIG. 9  is a perspective view of the first pre-forming operation in accordance with an embodiment of the present invention; 
         FIG. 10  is a perspective view of a second pre-forming operation in accordance with an embodiment of the present invention; 
         FIG. 11  is a perspective view of a third pre-forming operation in accordance with an embodiment of the present invention, and 
         FIG. 12  is a perspective view of a final forming operation in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , an embodiment of the backing ring assembly in accordance with the present invention is illustrated. In this embodiment, the bearing assembly  10  is a tapered roller bearing of the type commonly used in railway applications to support a railcar wheel on an axle. 
     The bearing assembly  10  is typically preassembled before being mounted on railcar axle  14 . At each free end of the axle  14 , a journal  12  terminates in a slightly conical tapered section  15  to facilitate installation of the bearing assembly  10  onto the journal. The bearing assembly  10  is pressed onto the journal  12  of the axle  14  to establish an interference fit. 
     A dust guard  18  with a larger diameter than the journal  12  is located axially inward from the journal  12 . Axially inward from the dust guard  18 , the shaft  14  extends to its largest diameter. The weight of the railcar is transferred through the bearing assembly  10  to the shaft and further transferred to the rails through the railcar wheels (not shown) fitted inboard of the dust guard on the shaft. 
     Some bearing assemblies  10  have wear rings  22 ,  24  fitted over the journal  12  and which about each end of the bearing assembly  10 . The wear rings  22 ,  24  typically have an inner diameter dimension to provide an interference fit with the journal  12  over at least a portion of their length. The wear rings  22 ,  24  rotate with the shaft as it turns. 
     Although the bearing assembly  10  is pressed onto the journal  12 , further restraint is generally required against axial loads. To provide this axial restraint, the bearing assembly  10  is captured between a backing ring assembly  60  at the inboard side and a bearing retaining cap  20  at the outboard side of the bearing assembly  10 . 
     Referring now to  FIG. 2  as well, at the inboard side of the journal  12  portion of axle  14 , the bearing assembly  10  is captured by the backing ring  61  through abutting wear ring  24 . Backing ring  61  has an inner contoured surface  66  allowing a tight surface fit with a complementary surface on the fillet  16  on the inboard end of the journal  12 . The fillet  16  leads to a shoulder  17 , the shoulder extending to form a dust guard  18  having a cylindrical surface  19 . Backing ring  61  has an inboard distal edge  63  at the contoured surface  66 , generally abutting fillet  16 . 
     Locking ring  71 , has a lateral inner end adjacent to the dust guard  18 . Locking ring lateral outer end engages backing ring  61  and restrains backing ring  61 , against deflection and axial displacement. Backing ring  61  and locking ring  71  together form the backing ring assembly  60 . Locking ring  71 , the furthest inboard component affixed to the journal  12 , affixes the bearing assembly  10  against axially inward displacement. 
     At the outboard end of the journal, the bearing assembly  10  is captured by the bearing retaining cap  20  through the interposed and abutting outboard wear ring  22 . Bearing retaining cap  20  is affixed to the free end of journal  12  with cap screws or bolts  21  threaded into a plurality of threaded bores. Bearing retaining cap  20  completes the mounting of the bearing assembly  10  onto the journal  12 , providing a clamping force to restrain the bearing assembly against axially outward displacement. 
     The bearing assembly  10  is preassembled from a number of individual components, including two cylindrical bearing cones  38 ,  40  and a cylindrical bearing cup  31 . Bearing cup  31  has an inner surface having radially inward directed outer raceways  32 ,  34 . The bearing cones  38 ,  40  have radially outward directed inner raceways  39 ,  41 . A center spacer  47  is positioned between the bearing cones  38 ,  40  to maintain the cones in accurately spaced position relative to each other and allow for proper bearing lateral clearance. The outer raceways  32 ,  34  in the bearing cup  31  cooperate with the inner raceways  39 ,  41  in the bearing cones  38 ,  40  to capture and support two rows of the tapered rollers  42 ,  44 . In some embodiments, cages  46 ,  48  maintain the circumferential spatial positioning of the rollers  42 ,  44 . 
     Bearing seals  50 ,  52  cover the ends of the bearing assembly  10  to minimize both lubricant leakage from the bearing and intrusion of contaminants such as water or abrasives into the bearing. In a first embodiment, the bearing seals  50 ,  52  are affixed to the stationary (i.e., non-rotating) side of the bearing assembly  10  (such as the bearing cup  31 ) by interference fit or other appropriate method. 
     A seal body  56 , typically of a generally ring shaped steel construction, is part of bearing seal  50 ,  52  to form a dynamic seal between stationary and moving bearing assembly components. In one embodiment, the seal body  56  is urged against the wear ring  22 ,  24  to seal the bearing assembly  10 . A first radial edge  57  of seal body  56  is received against an inner radial surface  33  of bearing cup  31 . A second radial edge  59  of seal body  56  extends radially inward and has a resilient seal  58  attached thereto. Resilient seal  58  contacts outer radial surface  23  of wear ring  24  and is typically comprised of a rubber or synthetic flexible material. 
     Cylindrical wear rings  22 ,  24  protect the journal  12  against rubbing wear from the seal body by providing a wear surface  23 . 
     Referring to  FIG. 2 , the backing ring assembly  60  of  FIG. 1  is illustrated in an enlarged sectional view. Backing ring  61  has an inner contoured surface  66  adjacent the journal  12  at the complementary surface of the fillet  16 . 
     A slot or cutout section  65  in the axially inward directed surface of backing ring  61  receives the laterally inner end  25  of wear ring  24  in an interference fit. 
     Locking ring  71  further has a lateral outer end  72  of a larger diameter and having a cutout section  76  for receiving a radially outward extending portion  62  of backing ring  61 . Locking ring  71  outer end  72  includes an inner radial surface  75  that is adjacent outer radial surface  67  of backing ring  61 . Locking ring  71  inner end  74  includes an inner radial surface  78  that is adjacent outer radial surface  19  of axle  14 . 
     Locking ring  71 , with its connection between backing ring  61  and the cylindrical surface  19  of the dust guard  18 , reinforces and anchors backing ring  61  against axial displacement and deflection. It is believed that the flexibility of the locking ring  71  allows backing ring  61  to more readily move with the deflection of the journal  12 , yet, still allow locking ring  71  to restrain the axial displacement of backing ring  61 . 
     Referring now to  FIG. 3  and  FIG. 4 , the currently known method for forming a bearing seal or bearing seal case is to stamp the bearing seal case from a flat rolled coil of steel  801 . It is noted that the width of the flat rolled coil of steel  801  is wider than the diameter of the material needed to form the final bearing seal case  807 . The seal case itself is an important component of the entire bearing assembly in that the seal case is utilized to both retain lubricant within the moving components of the bearing assembly and to keep undesired components such as rainwater and dirt out of the moving components of the bearing assembly. 
     The process currently utilized to manufacture bearing seal case  807  is known as a drawing process, wherein the bearing seal is formed in a progressive die stamping operation. These progressive operations are generally shown in  FIG. 3 , with a first stamping operation forming a pre-form bearing seal  802 , a second stamping operation forming a second pre-form bearing component  809 , and a final stamping operation forming a final bearing seal  805 . It is seen that a waste portion of steel  808  ultimately is released during the final forming operation, with initial centrally located steel components from the initial stamping shown as  802 , central component  804  in the second pre-forming operation, and central component  806  formed in the third stamping operation. The ultimate amount of waste product from the known bearing stamping operation is shown in  FIG. 4  as center component  808  and leftover portion  803  of coil  801 . It is an important object of the present invention to provide a more efficient method of manufacturing a bearing seal component. In the second forming operation wherein bearing component  804  is restruck, the seal case  809  is given an initial start of its final geometry. The next operation is a piercing operation wherein bearing seal  805  is coined to its final form. Bottom portion  806  is cut and pressed back into the seal case to be carried to the final forming operation. In the final operation, the pierced bottom section or waste section  808  is removed from bearing seal  807 . 
     Referring now to  FIG. 5 , a finished bearing seal case in accordance with an embodiment of the present invention is shown generally at  701 . Bearing seal case  701  is seen to comprise an inner diameter  705  which is typically the inner diameter of a strengthening lip that begins at pre-form or bent section  709 . Inner diameter section  705  is seen to be at about a 90° angle to main bearing seal case section  711 . Outer diameter  707  is formed as a lip with an initial transfer step  708  extending from main section  711  and ending with a transverse section  713  to form outer diameter  707 . 
     Referring now to  FIG. 6-FIG .  12 , the method of forming bearing seal case  701  in accordance with an embodiment of the present invention is set forth. Steel coil  101  is fed into a ring rolling machine  102  which is comprised of sets of rollers. Steel coil  101  is formed into a closed coil ring  105 , which is cut from steel coil  101 . Closed coil ring  105  is welded with weld fixture  103  in place. 
     Referring now to  FIG. 7 , closed coil ring  201  is shown as being transferred to weld bead removal station  202 . 
     The weld bead formed on welded steel coil ring  301  is flattened in the operation shown in  FIG. 8  by passing welded steel coil ring  301  through flattening rollers  302  and  303 . 
     Referring now to  FIG. 9 , an initial pre-form operation to welded steel coil ring  401  is pre-formed utilizing the combined rollers  404  and  405  mounted on rolling machine  402  with a base  403 . This forms a profile at a ninety degree angle to welded steel coil ring  401  as shown in the included profile of  FIG. 9 . 
     Referring now to  FIG. 10 , a second pre-forming operation is performed to the first pre-formed steel coil ring  501 , by a pre-forming roller  502  combined with an outer shaping roller assembly  503 . This introduces two additional ninety degree bends or near ninety degree bends in first pre-form steel coil ring  501  as shown in the included profile of  FIG. 10 . 
     A third pre-forming operation can be included as shown in  FIG. 11 . Such third pre-forming operation is performed to a second pre-formed steel coil ring  601  by a combination of an internal roller assembly  602  and an external roller form  603 . This third pre-forming operation depends on the ultimate desired profile of bearing seal  701 . 
     Referring now to  FIG. 12 , a final pre-forming operation is performed wherein the final configuration of bearing seal  701  is formed utilizing a combination of tapered key  703  and segmented die  702 . Such forming operation results in the formation of finished bearing seal  701  to its final configuration. It will be noted from the above steps that no waste material is formed from the initial width of steel coil  101  to the final configuration of bearing seal  701 . 
     The material typically utilized for the formation of bearing seal or bearing seal case  701  is usually a steel of selected strength and forming capabilities, such steel is typically an ASTM steel number SAE 1010 of a thickness of 0.073″ to 0.075″ inch. All forming operations as part of the present invention are cold forming operations wherein it is not necessary to preheat the steel coil for any of the interim steps to perform the desired pre-forming operations.