Abstract:
A waste container has an axle assembly comprising an axle with opposing axle end caps adapted to mount the wheels of the waste container. The axle comprises a metal rod encapsulated in plastic. An annular axle groove is formed near the ends of the axle in the encapsulating plastic. The metal rod provides the necessary strength for the axle and the encapsulating plastic protects the rod from corrosion while permitting the formation of the annular axle grooves used for mounting the axle to the wheel. The axle can easily be injection molded, reducing the cost and manufacturing time of prior axles while still providing corrosion protection.

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/130,335, filed Apr. 21, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a waste container with an external axle assembly. In one of its aspects, the invention relates to a waste container with an external axle assembly with opposing end caps for retaining wheels on an axle. In another of its aspects, the invention relates to a wheel assembly, especially for a waste container. In yet another aspect, the invention relates to a method for making an axle assembly. 
     2. Description of the Related Art 
     Curbside waste containers with wheels supported by an axle assembly are well known and commonly used in municipal waste collection systems. The wheeled waste containers increase the ease of moving the waste container, which often contains a relatively heavy load, to a curbside where a waste collection vehicle can transfer the contents of the waste container into the waste collection vehicle. Conventional waste containers typically use an external axle assembly incorporating a solid steel axle on which opposing wheels are rotatably mounted. The axles are coated with a rust resistant coating but nonetheless tend to corrode which results in expansion of the axle. The corrosion increases the friction between the axle and the wheels and in some cases freezes the wheels on the axles and can even split the wheels. Further, the solid axles are typically machined to provide mounting grooves and other structural elements for securing the wheel to the axle. The machining of the solid axle and the rust-resistant coating adds to the overall cost of the waste container and increases the manufacturing time of the waste container. Since waste containers are typically high volume items, any small reduction in the manufacturing time and relative cost is a great advantage. 
     SUMMARY OF THE INVENTION 
     According to the invention, a waste container for the storage and collection of residential or commercial waste comprising a receptacle having a bottom wall and a peripheral side wall extending upwardly from the bottom wall and terminating in an upper edge to define a waste compartment with an open top. At least one cover is pivotally mounted to an upper portion of the receptacle and is moveable between an open position, in which the cover is remote of the open top to permit access to the waste receptacle, and a closed position, in which the cover at least partially overlies the open top. In a preferred embodiment of the invention, a handle extends from the upper portion of the receptacle. A wheel assembly is mounted to a lower portion of the receptacle and includes an elongated axle, wheels rotatably mounted on the axle, and wheel retainers mounted to end portions of the elongated body outwardly of the wheels to retain the wheels on the axle. 
     According to the invention, the axle comprises an elongated body formed of a molded synthetic resin; and a reinforcing rod encapsulated within the elongated body to form an internal support therefor and strengthen the elongated body sufficiently to avoid undesirable deformation or failure of the axle under expected loads in the receptacle. In a preferred embodiment of the invention, the elongated body has a groove integrally formed at end portions thereof and the wheel retainers have a lug extending radially inwardly into the groove in the axle to retain the wheels on the axle. In a preferred embodiment, the end portions of the elongated body include a tapered end. 
     In one embodiment, the grooves extend circumferentially around the end portions of the elongated body and the elongated body is cylindrical in shape. The reinforcing rod preferably extends substantially along the length of the elongated body. In one embodiment, the reinforcing rod is made of metal. In another embodiment, the reinforcing rod is made of fiberglass. 
     The reinforcing rod preferably extends throughout the central portion of the axle and to the end portions to prevent deformation of the axle between the wheels. However, the central portion of the axle can have molded ribs or other reinforcements formed of the synthetic resin the enhance the strength of the axle and the reinforcing rod need not extend throughout the entire length of the axle. The reinforcing rod can extend to the end of the axle ends of the axle outboard of the wheels but need not do so. The end portions of the axle outboard of the wheels can be formed entirely of the synthetic resin. 
     The synthetic resin can be a filled or unfilled moldable thermoplastic polymer selected from the group consisting of polyolefins, polyvinyl chloride, Nylon, polyester, acrylonitrile polymers, copolymers, homopolymers and blends thereof. The synthetic resin is corrosion resistant. 
     The wheel retainers can be a variety of shapes. In a preferred embodiment, the wheel retainers comprise a generally circular spring having a first end attached to the lug to bias the lug into the axle groove. Further, the lug includes a keeper extending radially inwardly toward the axle, and the generally circular spring biases the lug or keeper into the axle groove. Desirably, a cover is mounted to the wheel in overlying relationship with the hub opening to cover the wheel retainer. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a perspective view of a waste container according to the invention and including an axle assembly also according to the invention; 
     FIG. 2 is a rear view of the waste container of FIG.  1  and showing the axle, fastener, and cover of the axle assembly in exploded view; 
     FIG. 3 is an enlarged exploded view of the axle assembly of FIG. 2; 
     FIG. 4 is a longitudinal sectional view of the axle taken along line  4 — 4  of FIG. 3 illustrative the internal reinforcing rod and outer layer of the axle; 
     FIG. 5 is a cross section of the axle taken along line  5 — 5  of FIG. 3; 
     FIG. 6 is a sectional view of an injection mold having a cavity in which the reinforcing rod is held by positioning pins during the initial moments of the injection of plastic forming the outer layer; and 
     FIG. 7 is a cross section taken along line  7 — 7  of FIG. 6; and 
     FIG. 8 is a sectional view similar to FIG. 6 with the positioning pins withdrawn from the mold cavity and near the completion of the plastic injection. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1 and 2 illustrate a waste container  10  comprising a body  12  having an open top  14 , which is closed by a cover  16 . The body  12  comprises a bottom wall  13  from which upwardly extends a peripheral side wall  15 , which terminates in an upper edge  17  to define the open top  14 . The cover  16  is preferably hingedly mounted to the body  12  via a handle  18  extending from a rear side of the body  12 . A grab handle  20  is provided in a depressed area  22  on a front side of the body  12 . 
     Referring to FIG. 2, the waste container  10  further comprises a wheel assembly  30 , which is preferably located in an inset portion  32  at the lower rear of the body  12 . The wheel assembly permits a user of the waste container to grab the handle  18  and wheel the waste container  10  to a desired location, such as a suitable position for dumping the contents of the body  12  into a waste collection vehicle. 
     Referring to FIGS. 2 and 3, the wheel assembly  30  comprises an axle  34  for mounting a pair of wheels  36 , which are secured to the axle by a retainer or fastener  38  hidden by a cover  40 . Each wheel  36  comprises a disc  82 , having a hub  84  at the center of the disc and a rim  86  at the periphery of the disc. A plurality of support ribs  88  extend from the hub to the rim  86  to give structural support to the wheel  36 . A tire  90  is mounted to the rim  36  of the wheel  36 . The disc  82 , hub  84 , rim  86  and support ribs  88  of the wheel  36  are preferably molded as a single unit from a suitable thermoplastic material. The disc  82  also has four snap apertures  91  to receive snap fingers  92  in mounting the cover  40  to the wheel  36  and disc apertures  98  to provide access for a tool (not shown) to unlock the wheel retainer  38 . The hub  84  defines a central aperture  93  of the wheel  36  through which the axle  34  passes upon assembly of the wheel assembly  30 . Notches  94  and  96  are located in the wall of the hub  84  and are diametrically opposed to one another. 
     The fastener  38  secures the wheels  36  to the axle  34  and comprises diametrically opposed lugs  100  connected by two semi-circular spring members  104 . The lugs  100  are mirror images of each other. Ring-shaped webs or tool guides  108  extend from the lugs  100  and define tool apertures. Positioning tabs  110  extend away from the tool guides  108  and position the wheel retainer  38  with respect to the disc  82  of the wheel  36 . Spacers  112  extend away from the tool guides  108  in a direction opposite the positioning tabs  110 . The spacers abut the cover  40  when assembled and locate the wheel retainer  38  between the cover  40  and the wheel  36 . 
     The lugs  100  also have keepers  114 , which extend away from the tool guides  108  and toward the center of the aperture defined by the semi-circular springs  104  and lugs  100 . Each of the keepers  114  has a beveled surface to aid the insertion of the axle  34  through the lugs  100  upon assembly of the wheel assembly  30 . The fastener  38  is disclosed in more detail in U.S. Pat. No. 5,716,107, which is incorporated by reference. 
     Referring to FIGS. 3-5, the axle  34  is preferably of a composite construction comprising an elongated body  46  formed of a molded synthetic resin outer layer  42  and a reinforcing rod  44  extending substantially along the length of the elongated body and forming an internal support for the body  46 . The internal reinforcing rod  44  is preferably a metal rod, such as steel. However, non-metallic rods, such as fiberglass rods, can also be used. The synthetic resin is preferably a suitable moldable thermoplastic material. The molded synthetic resin is corrosion resistant, is preferably injection moldable and can include a variety of moldable thermoplastic polymers, filled or unfilled, including polyolefins such as polyethylene, polyester, polypropylene, polyvinyl chloride, Nylon, ABS, acrylonitrile polymers, copolymers, homopolymers and blends thereof. 
     The elongated body  46  comprises a main body  48  and a tapered end cap  52 , separated from the main body  48  by an annular axle groove  54 . The groove  54  is sized to receive the lugs  100  and/or keepers  114  of the fastener  38 . The rod preferably lies in the central portion of the axle as defined by the portion of the axle between the grooves  54 . 
     Although the internal support is preferably a metal rod, other reinforcing rods can be used within the scope of the invention. The internal support can be any structurally suitable element whose structural characteristics are not adversely affected by process of forming the elongated plastic shape. For example, the internal support can be a high temperature plastic or composite material which will withstand the heat of any molding process. The diameter of the rod relative to the diameter of the axle can vary depending on the strength requirement of the container and the overall diameter of the axle. Typically the diameter of the rod will be at least 50% of the thickness of the axle and preferably about 80%. In a specific example, an axle with a diameter of ⅝ inches has a metal rod of low carbon steel of ½ inches and the remainder of the thickness is high impact copolymer polypropylene. 
     To assemble the wheel assembly  30 , the axle assembly  34  is then inserted through opening  70  in support braces  72  located in the inset portion  32  of the waste container body  12 . A spacer (not shown) can be slid over the axle to space the wheel  36  from the support brace  72 . The resilient fastener  38  is pre-assembled to the wheel  36  along with the cover  40 . The assembly of the wheel  36 , fastener  38 , and cover  40  is then slid over each of the end caps  52  by inserting the end caps  52  through openings  93  in the hub of the wheels. The wheels  36  are slid onto the axle a sufficient distance so that the groove  54  is located on the exterior side of the wheel  36 . As the wheel is slid onto the axle  34 , the axle end cap  52  abuts the keepers  114  on the lugs  110  and deflects the keepers outwardly against the bias of the springs  104 . The continued sliding of the wheel aligns the keepers  114  with the axle groove  54 , where the springs  104  bias the keeper  114  into the axle groove  54  to lock the wheel onto the axle assembly  34 . 
     Preferably, the axle is elongated with a circular cross section that forms an overall cylindrical shape. Other cross sections can be used. For example, a multi-faceted cross section, such as triangular, rectangular, pentagonal, or hexagonal can be used. The preferred cross section will be determined by the particular manufacturing process and the anticipated bending forces acting on the axle. For example, a rectangular cross section with a narrow horizontal width relative to the vertical height better resists the bending moments applied to the axle while reducing the material requirement of a circular cross section. The cross section can also vary along the length of the axle. For example, the cross section can be multi-faceted along the central portion of the axle between the support braces  72  and circular along the portion passing through the openings in the support braces  72  to enhance the strength and rigidity of the axle without retarding rotation of the wheels on the axle. The central portion of the axle between the support braces can also have external ribs to enhance the strength and rigidity. 
     The fastener  38  and cover  40  are the preferred form of the invention but it is within the scope of the invention to include other wheel retainers, with or without end covers. Any other suitable means of retaining the wheel on the axle assembly is within the scope of the invention. For example, a transverse opening through the end caps  52  and a cotter pin or similar locking device can be inserted through the opening to affix the wheel to the axle assembly  34 . A cap with deformable fingers extending into the hollow interior of the cap, which is known as a “Timmerman Nut”, can also be used. The cap is driven onto the end of the axle and the fingers deform against the exterior of the axle. Also, the fastener can mount to the hub instead of the wheel, preferably by a set of spring fingers that extend from the lug portion of the fastener and are slidably received in a hub opening to bear against a side of the hub opposite the lugs. Such a fastener is show in U.S. Pat. No. 5,902,018, which is incorporated herein by reference. 
     The grooves  54  need not extend circumferentially around the axle. The groove can be discontinuous as well as continuous. A single or multiple discrete indentations can be used instead of the groove. The continuous nature of the grooves is preferred since only the relative axial movement of the fastener and axle is required to position the lug within the groove, whereas a discontinuous or discrete groove or indentation requires both axial and radial alignment for the lug to be received within the groove or indentation. 
     Referring to FIGS. 6-8, the axle  34  is preferably made with an insert injection molding process that utilizes a moveable mold half  120  and a fixed mold half  122 , which when brought together define a mold cavity  124  defining the exterior shape of the axle. Fluid channels  126  on opposite sides of the mold cavity  124  are formed when the mold halves  120 ,  122  are brought together. The fluid channels  126  fluidly connect to the mold cavity at the location where the end caps  52  will be formed. A gate (not shown) controls the flow of fluid into the fluid channels  126 . 
     The molds are shown in a vertical orientation with the moveable mold half  120  moving laterally relative to the fixed mold half  122 . The mold halves  120 ,  122  could also be horizontally oriented with the moveable mold half moving vertically relative to the mold half  122 . 
     Positioning pins  128 ,  130  locate the reinforcing rod in the mold cavity. The positioning pins are located in the upper and lower mold halves  120 ,  122 , respectively, and can be extended and withdrawn from the mold cavity  124 . Each of the positioning pins  128 ,  130  terminate in an arcuate end  132 ,  134  conforming to the exterior shape of the reinforcing rod  44 . When the paired pins  128 ,  130  extended into the mold cavity  124 , they abut opposing sides of the reinforcing rod to compressibly retain the rod with the mold cavity  124 . 
     The molding process is initiated by placing the reinforcement rod  44  on the pins  130  of the lower mold half  122  while the mold halves are separated. The pins  130  can be magnetized to help retain the reinforcement rod  44 . The mold halves are then brought together to form the cavity  124  and the pins  128  are extending into the cavity to contact the reinforcement rod  44 . 
     The pins  128 ,  130  are preferably actuated by air cylinders. However, the pins  128 ,  130  can be actuated by traditional mechanical devices, such as a cam, or by hydraulic cylinders. The pins function to hold the reinforcement rod  44  in a predetermined position in the mold cavity spaced from the cavity walls and to prevent the rod  44  from deflecting in response to the pressure from the injected plastic. Depending on the bending strength of the material forming the reinforcement rod  44 , there can be more than two sets of pins  128 ,  130 . The number and position of the pin pairs  128 ,  130  can be adjusted as needed. One set of the pins  128 ,  130  also functions as ejector pins when the molding operation is complete. 
     When the reinforcement rod  44  is secured within the mold cavity by the pins  128 ,  130 , molten plastic  136  is injected into the mold cavity  124  through the fluid channels  126 . Preferably, the molten plastic  136  is simultaneously injected under pressure through the opposing channels  126  moves towards the pins  128 ,  130 . The pins  128 ,  130  are withdrawn from the cavity  124  prior to the time the molten plastic  136  flow front reaches the pins but after the molten plastic  136  has effectively fixed the position of the reinforcement rod  44  within the cavity  124 . The timing of the pin withdrawal can controlled by a timer based on empirical data as to when the molten flow front will reach the pins. Alternatively, the timing of the pin withdrawal can controlled by a pressure sensor which controls the withdrawal of the pins based on the pressure in the mold cavity adjacent the pins. 
     Although the molten plastic  136  is preferably injected at opposite ends of the cavity  124 , the injections can occur at only one of the ends. In a single end injection, the pins  128 ,  130  can be withdrawn before the approaching front of the molten plastic. The fluid channels also do not need to be at the ends of the axle. The fluid channels and the corresponding gate can extend into the cavity  124  at a position along the side of the axle. For example, a single fluid channel can extend into the cavity  124  between the pin pairs, with the molten plastic flowing from the central portion of the cavity  124  toward the ends. 
     The injection of the molten plastic  136  continues until the mold cavity  124  is filled to complete the outer layer  42  of the composite axle. When the injection of molten plastic  136  is completed, the mold halves are separated and the axle is removed from the mold. The position pins  130  preferably perform the dual function of positioning the rod and ejecting the rod. When the mold halves are separated, the pins  130  are extended again to eject the completed axle from the lower mold half  122 . Traditional ejector systems, including ejector pins, can be used alone or in combination with the positioning pins  130  to eject the axle. 
     Although the preferred form of applying the outer layer  42  is by injection molding, compression molding and other methods such as coating on the reinforcement rod with molten plastic by dipping can be used. 
     The waste container  10  according to the invention is an improvement over previous waste containers in that the axle  34  comprises a molded plastic axle that can be easily and inexpensively manufactured and assembled, unlike the solid metal machine axle assemblies of prior waste containers. Additionally, the encapsulating layer of the axle according to the invention is made from non-corrosive material that will not corrode over time, unlike the metal axle assemblies of prior waste containers. Therefore, the waste container and axle assembly of the invention is not only more cost effective and easier to manufacture and assemble than previous axle assemblies, but the axle assemblies according to the invention also will have a longer useful-life than previous axle assemblies. 
     While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this description of the invention is by way of illustration and not of limitation. Reasonable variation and modification are possible within the scope of the forgoing disclosure without departing from the spirit of the invention.