Wear resistant chain joint seal

Abstract: A chain (16) comprising a plurality of pairs of opposed inner sidebars (26) alternating with pairs of opposed outer sidebars (52) connected to the inner sidebars by pins (76) extending through the outer sidebars and through bushings (36) which themselves extend through aligned apertures (34) in the inner sidebars is provided with a sealing member (66) around each end (48, 50) of each bushing (36) and housed between the respective inner and outer sidebars of the chain. Each of the sealing members (66) includes a collar (68; 100) which is pressed onto the end of the bushing and which is positioned in closely spaced relation to the inner sidebar (26). Each collar has a circumferential flange (70) or outer and inner collar portions (104, 106) which extend towards and engage the outer sidebar (52), thereby defining an annular groove (72; 108) surrounding the bushing and facing towards the outer sidebar (52). Each sealing member further includes a resilient sealing ring (74; 110) housed in the annular groove so that it engages in a sealing relation with the outer sidebar (52) engaged by the collar (68; 100) in which it is housed.

Description: The invention relates generally to chains and, more particularly, to chain joint seals. BACKGROUND OF THE INVENTION In chains used in abrasive environments, it is desirable to protect the wear surfaces comprised of the outside surfaces of the chain pins and the inside of the chain bushings by keeping these bearing surfaces lubricated and by preventing abrasive material from entering the space between the bearing surfaces. See for example, U.S. Patent No. 4,464,151, issued to Kahl on August 7, 1984, which is incorporated herein by reference. A problem with prior art chain joint seals is that they wear quickly in certain applications such as when they are exposed to heat and very abrasive materials. For example, prior art chain joint seals wear quickly when used in material handling elevators where they are exposed to fine abrasive materials such as cement, ash, powdery metal (e.g. hot, dry, fine, powdery magnesium), or other materials. If the chain joint seal becomes worn, fine abrasive material can then enter into the chain joint and fill the space between the chain pin and a chain bushing, resulting in pin wear or dry cavitation-erosion type wear. This wear can limit chain life in a conventional chain. With the aim of avoiding this problem, according to the invention there is provided a chain link assembly comprising: a pair of inner sidebars, each having an aperture; a hollow cylindrical bushing having opposite ends and an outside diameter, the opposite ends of said bushing being housed in said apertures in said pair of inner sidebars such that the opposite ends of said bushing extend through said apertures and project beyond and adjacent to said inner sidebars; a pair of outer sidebars each having an aperture having a diameter smaller than the outside diameter of said bushing, one of said outer sidebars being adjacent to one of said opposite ends of said bushing and the other of said outer sidebars being adjacent to the other of said opposite ends of said bushing; a pin extending through said bushing, said pin having a longitudinal axis and opposite ends housed in said apertures in said outer sidebars to form a chain joint; and a pair of sealing assemblies, said sealing assemblies surrounding the opposite ends of said bushing and being housed between the inner sidebars and the outer sidebars, each of said sealing assemblies including a resilient sealing ring surrounding one of said opposite ends of said bushing and engaging in sealing relation said outer sidebar, and a collar through which passes one of said opposite ends of said bushing, the collar having an outer portion surrounding said resilient sealing ring and a second portion between the resilient sealing ring and the adjacent inner sidebar. Each collar is preferably pressed onto one of the ends of the bushing and is positioned in closely spaced relation to one of the inner sidebars. The collar may be disk-shaped and have a periphery including a circumferential flange forming the outer portion of the collar, or alternatively it may be U-shaped, having outer and inner portions which extend from the second portion toward one of the outer sidebars. The collar thus defines an annular groove surrounding the end of the bushing and in which the resilient sealing ring is housed. Other features and advantages of the invention will become apparent to those of ordinary skill in the art upon review of the following detailed description of embodiments of the invention, given by way of example only, with reference to the accompanying drawings, in which:- Figure 1 is top plan view, partially in section, of part of one embodiment of a chain assembly in accordance with the invention; Figure 2 is an enlarged sectional view taken along line 2-2 of Figure 1, and illustrating a sealing assembly of the chain assembly; Figure 3 is a view similar to Figure 2, but showing an alternative embodiment of the invention; and, Figure 4 is a view similar to Figure 2 but showing yet another embodiment of the invention. Illustrated in Fig. 1 is a straight sidebar chain 16 embodying the invention and including a plurality of pairs of opposed, aligned, inner sidebars 26. Each inner sidebar 26 is an integral piece or member having opposite end portions 30 and 32. Each inner sidebar end portion 30 and 32 defines an aperture 34. The chain 16 further includes tubular bushings 36 pressed into the apertures 34 of each pair of inner sidebars 26 so as to be secured to each pair of inner sidebars. Each bushing 36 has opposite ends 38 and 40, respectively, an inside surface 42 having an inside diameter, an outside surface 44 having an outer diameter, a central portion 46, and integral bushing extensions 48 and 50, respectively, at each end of the central portion 46. In the illustrated embodiment, the central portion 46, and the bushing extensions 48 and 50 all have the same outside diameter; however, in an alternative embodiment of the invention (not shown), the extensions 48 and 50 of each bushing have respective outside diameters that are smaller than that of the central portion 46 of the bushing 36. Each bushing 36 is supported by one pair of inner sidebar portions 30 or 32 such that the central portion 46 of that bushing 36 extends between those inner sidebar portions 30 or 32 and into each of the apertures 34 of those inner sidebar portions 30 or 32 and such that the bushing extensions 48 and 50 respectively project outwardly beyond the inner sidebar portions 30 or 32. The chain 16 further includes a plurality of pairs of opposed, aligned outer sidebars 52. Each outer sidebar 52 is an integral piece or member having opposite end portions 54 and 56. Each outer sidebar end portion 54 and 56 includes an opening 58 having a diameter smaller than the outside diameter of the bushing extensions 48 or 50. Each outer sidebar portion 54 of one pair 60 of outer sidebars 52 is adjacent and spaced from one of the inner sidebar portions 32 of one pair 62 of inner sidebars 26. Further, the opening 58 of each outer sidebar portion 54 of the one pair 60 of outer sidebars 52 is aligned with the opening 34 of one of the inner sidebar portions 32 of the one pair 62 of inner sidebars 26. Each outer sidebar portion 56 of the one pair 60 of outer sidebars 52 is adjacent and spaced from one of the inner sidebar portions 30 of a pair 64 of inner sidebars 26 different from the pair 62. The opening 58 of each outer sidebar portion 56 of the one pair 60 of outer sidebars 52 is axially aligned with the inner surface of the bushing extension 48 or 50 supported by one of the inner sidebar portions 30 of the pair 64 of inner sidebar portions 30. The chain 16 further includes a plurality of pairs of sealing assemblies 66. The sealing assemblies 66 of one of the pairs of sealing assemblies respectively surround the bushing extensions 48 and 50 of one bushing, and each of the sealing assemblies 66 is housed between one of the inner sidebar portions 30 or 32, and one of the outer sidebar portions 54 or 56. Each of the sealing assemblies 66 includes (see Figs. 2 and 3) a disk shaped collar 68 of hardened metal (or other suitable material) pressed onto one of the bushing extensions 48 or 50 and positioned in closely spaced relation to one of the inner sidebars 26. Each disk shaped collar 68 has a periphery including a circumferential flange 70 extending toward and engaging one of the outer sidebars 52. Each disk shaped collar 68 defines an annular groove 72 surrounding one of the bushing extensions 48 or 50. The sealing assemblies 66 further include resilient sealing rings 74 of polymeric material respectively housed in the annular grooves 72. Each resilient sealing ring 74 surrounds and engages one of the bushing extensions 48 or 50 and also engages in sealing relation the outer sidebar 52 engaged by the collar 68 in which it is housed. Fig. 2 shows one embodiment of the invention wherein each sealing ring 74 is circular in cross section. Fig. 3 shows an alternative embodiment of the invention wherein each of the sealing rings 74 is generally X-shaped in cross section. In a preferred embodiment of the invention, a space S1 is provided between each sealing assembly 66 and the adjacent inner sidebar end portion 30 or 32 and that dimension (S1) is equal to or greater than the space S2 between the end 98 of the bushing 36 and the outside sidebar 52. This is to reduce any possibility of a sealing assembly 66 being crushed by an inner sidebar portion 30 or 32 during any lateral movement of the inner sidebar portion 30 or 32 during use of the chain 16. The chain 16 further includes a plurality of pins 76 respectively extending through the bushings 36 and respectively having opposite ends 78 and 80 housed in the openings in opposed outer sidebar portions 54 or 56 adjacent to the bushing extensions 48 or 50 of the respective bushings 36 to form chain joints connecting pairs of inner sidebars 26 with pairs of outer sidebars 52. Each pin 76 has a longitudinal axis 82. In the specific arrangement illustrated, the end 80 of each pin has a head 84, and the end 78 of each pin has a cotter pin hole 86 transverse to the longitudinal axis 82 of the one pin. The chain 16 further includes a cotter pin 88 in each cotter pin hole 86. Alternatively, the chain 16 is of riveted construction, does not include cotter pin holes 86 or cotter pins 88, and instead includes a rivet formed head (not shown). For each chain joint, the outer sidebar portions 54 or 56, the inner sidebar portions 30 or 32, the bushing 36, and the sealing assemblies 66 are located axially between the head 84 and the cotter pin 88 (or rivet formed head). The chain 16 has first and second sides 90 and 92, respectively. The heads 84 of pins 76 that are housed in one pair of opposed outer sidebars 60 are on the first side 90 of the chain, and the heads 84 of pins 76 that are housed in an adjacent pair 94 of outer sidebars 60 are on the second side 92 of the chain 16. Optionally, the chain 16 further includes rollers 96 rotatably mounted over each bushing 36 and between opposed inner sidebars 26. In some embodiments of the invention, such as when the chain 16 is used in a centrifugal discharge elevator, the rollers 96 are preferably omitted. The straight sidebar chain 16 is assembled by performing a method which includes in any order steps (a) and (b) defined as follows: (a) Two of the bushings 36 are respectively inserted into opposed, aligned apertures 34 of a pair 62 of inner sidebars 26 such that the central portions 46 of the bushings 36 respectively extend between the inner sidebars 26 and through the opposed apertures 34 of the pair 62, and such that the bushing extensions 48 and 50 of the respective bushings project beyond the inner sidebars 26. Then, disk shaped collars 68 are respectively pressed onto the bushing extensions 48 and 50 at locations spaced from the respective inner sidebar portions. The collars 68 are pressed onto the bushing extensions 48 and 50 in an orientation such that the circumferential flange 70 of each collar on one bushing 36 faces away from the other collar 68 on the same bushing 36 and a portion of the flange 70 extends beyond the end of the bushing 36. The collars 68 are positioned such that they are spaced from the inner sidebar by a dimension greater than the extent of the flange portion beyond the end of the bushing 36. Then, a resilient sealing ring 74 is expanded around each of the bushing extensions 48 and 50 and is forced into the annular groove 72 defined by the collar 68 that is pressed onto that bushing extension 48 or 50. A second pair 64 of inner sidebars 26 is similarly assembled with bushings 36, collars 68, and sealing rings 74 either at the same time as the pair 62, or after assembly of the pair 62. (b) Pins 76 are inserted into an outer sidebar portion 54 for one side 92 of the chain 16 with the heads 84 of the pins on the same side of the outer sidebar portion 54. The method further includes the following steps after steps (a) and (b) above are performed: One of the pins 76 described in step (b), above, is inserted into one of the bushings 36 supported by the pair 62, and the other of those pins 76 is inserted into one of the bushings 36 supported by the pair 64. Then, an outer sidebar 52 for the other side 90 of the chain 16 is placed onto the ends 78 of the pins 76 described in step (b), above, with the openings 58 of that outer sidebar 52 surrounding the ends 78 of the pins 76. Then, cotter pins 88 are respectively inserted into the cotter pin holes 86 of the pins 76 described in step (b) (or a rivet head is formed). A further pair 94 of outer sidebars 52 is similarly connected to the pair 64 of inner sidebars 26, except that preferably the heads 84 of the pins 76 used with the pair 94 are located on the side 90 of the chain (i.e., oriented in the opposite direction to the pins 76 used with the adjacent pair 60 of outer sidebars 52). Chain component sizes are chosen such that, after assembly, the outer sidebars 52 engage the collars 68 as well as the sealing rings 74 in the collars 68, and such that the sealing assemblies 66 engaged by the outer sidebars 52 space the outer sidebars 52 from the bushing extensions 48 or 50. In an alternative embodiment of the invention depicted in Fig. 4, a sealing assembly 99 surrounds the bushing extension 50 of the bushing 36 and is housed between inner sidebar 30 and outer sidebar 52. Sealing assembly 99 includes a collar 100 that is generally U-shaped in cross section pressed onto bushing extension 50 and positioned in elosely spaced relation to inner sidebar 30. U-shaped collar 100 includes a bight portion 102, an outer collar portion 104 and an inner collar portion 106. Outer collar portion 104 and inner collar portion 106 are spaced apart radially and both extend toward and engage the outer sidebar 52. The bight portion 102, the outer collar portion 104 and the inner collar portion 106 define an annular groove 108 surrounding bushing extension 50. Sealing assembly 99 further includes a resilient sealing ring 110 of polymeric material housed in the annular groove 108. Resilient sealing ring 110 surrounds bushing extension 50 and engages in sealing relation with the outer sidebar 52. Fig. 4 depicts the resilient sealing ring 110 as generally X-shaped in cross section. In an alternative arrangement, the resilient sealing ring 110 may be generally circular in cross section. When the alternative embodiment of the invention depicted in Fig. 4 is assembled, resilient sealing ring 110 may be forced into the annular groove 108 of the generally U-shaped collar 100 before or after U-shaped collar 100 is pressed onto the bushing extension 50. Insertion of the resilient sealing ring 110 into the annular groove 108 of the U-shaped collar 100 before the U-shaped collar 100 is pressed onto the bushing extension 50 facilitates manufacturing. While preferred embodiments of the invention have been described, various modifications are possible. It is to be understood that the disclosed chain has applications other than for use in elevators. Further, the disclosed sealing arrangement could be employed with offset sidebars, or other sidebars that are not straight sidebars. Thus, the scope of the invention is to be limited only by the scope and spirit of the following claims.

Claims: A chain link assembly comprising: a pair of inner sidebars (26), each having an aperture (34); a hollow cylindrical bushing (36) having opposite ends (48,50) and an outside diameter, the opposite ends of said bushing being housed in said apertures (34) in said pair of inner sidebars (26) such that the opposite ends (48,50) of said bushing (36) extend through said apertures (34) and project beyond and adjacent to said inner sidebars; a pair of outer sidebars (52) each having an aperture (58) having a diameter smaller than the outside diameter of said bushing (36), one of said outer sidebars (52) being adjacent to one of said opposite ends (48,50) of said bushing and the other of said outer sidebars (52) being adjacent to the other of said opposite ends (48,50) of said bushing; a pin (76) extending through said bushing (36), said pin having a longitudinal axis (82) and opposite ends (78,80) housed in said apertures (58) in said outer sidebars (52) to form a chain joint; and a pair of sealing assemblies (66;99), said sealing assemblies surrounding the opposite ends (48,50) of said bushing (36) and being housed between the inner sidebars (26) and the outer sidebars (52), each of said sealing assemblies (66;99) including a resilient sealing ring (74;110) surrounding one of said opposite ends (48,50) of said bushing and engaging in sealing relation said outer sidebar (52), and a collar (68;100) through which passes one of said opposite ends (48,50) of said bushing, the collar (68;100) having an outer portion (70;104) surrounding said resilient sealing ring (74;110) and a second portion (68;102) between the resilient sealing ring (74;110) and the adjacent inner sidebar (26). A chain link assembly in accordance with claim 1 wherein said collar is a disk-shaped collar (68) having a periphery including a circumferential flange (70) which forms the outer portion of the collar, said disk-shaped collar (68) being positioned in adjacent but spaced relation from the inner sidebar (26). A chain link assembly in accordance with claim 2 wherein said outer circumferential flange (70) engages one of said outer sidebars (52) and maintains the outer sidebar that it engages in spaced relation from the bushing that the collar (68) surrounds. A chain link assembly in accordance with claim 2 wherein said collar (68) is metallic and is pressed onto said bushing (36). A chain link assembly in accordance with claim 1, wherein said collar also has an inner portion (106) spaced radially from the outer portion (104) so that said inner and outer portions (106,104) and said second portion (102) together define an annular groove which opens towards the adjacent outer sidebar (52) and in which the resilient ring (110) is housed.

Inventors: MILLER ROBERT M, SEAMAN GEORGE C, THUERMAN JOHN H, MILLER, ROBERT M., SEAMAN, GEORGE C., THUERMAN, JOHN H.
Applicants: REXNORD CORP, REXNORD CORPORATION
Application year: 1993
Main classification: F16G13
IPC codes: F16G13