Abstract:
A passenger conveyor ( 20 ) includes a handrail assembly ( 30 ) comprising a handrail ( 32 ) having a plurality of co-extruded polymer materials ( 34, 36 ). In one example, an outermost portion ( 34 ) establishes a passenger gripping surface ( 38 ). One example includes an extruded soft, low cost polymer in the middle of the handrail cross section to reduce cost and weight. A disclosed example includes a toothed driving surface ( 40 ) on an inner side made of a selected one of the polymer materials ( 34, 36 ). In one example, the driving surface ( 40 ) and the gripping surface ( 38 ) comprise the same polymer material.

Description:
1. FIELD OF THE INVENTION 
       [0001]    This invention generally relates to passenger conveyors. More particularly, this invention relates to making a handrail for a passenger conveyor. 
       2. DESCRIPTION OF THE RELATED ART 
       [0002]    Passenger conveyors are well known. A plurality of steps typically follow a loop for carrying individuals between landings at opposite ends of the conveyor. A handrail is often provided so that passengers can stabilize themselves as they travel along on the conveyor. 
         [0003]    A typical handrail design has a flat surface that faces upward with rounded edges. The body of the handrail is often made from laminated sheets of material using adhesives, heat or pressure to secure the layers together. Some rubber handrails have been made using a molding process. 
         [0004]    One disadvantage to conventional handrail designs is that they do not provide an easily-gripped surface for a wide variety of passengers. A more ergonomically friendly design is desirable. Conventional manufacturing techniques, however, place limitations upon the shape of a handrail because of material cost and the bending stiffness required for a workable handrail. 
         [0005]    Another shortcoming of conventional handrail designs is that they typically rely upon a pinching drive arrangement that utilizes friction between a handrail and a drive mechanism that creates a normal force against the handrail sufficient for causing the handrail to move with the steps of the passenger conveyor. Such arrangements often cause marking and scuffing on the outer surface of the handrail. This leads to premature replacement of a handrail. 
         [0006]    An alternative drive arrangement is shown in Japanese Patent No. 2735453. In that document, rack teeth are formed on a handrail inner surface to cooperate with a drive mechanism for moving the handrail. While that document shows an improved driving arrangement for a handrail, the overall handrail design and method of manufacture are not ideal. Those skilled in the art are always striving to make improvements. 
         [0007]    This invention provides an improved handrail design and manufacturing technique that allows for implementing non-conventional handrail shapes and an improved driving arrangement. 
       SUMMARY OF THE INVENTION 
       [0008]    An example method of making a handrail for a passenger conveyor includes co-extruding a plurality of polymer materials to establish a passenger gripping surface from a first polymer material and an inner portion from a second polymer material. One example includes forming a toothed driving surface on the handrail. The toothed surface provides a drive surface for interacting with a drive mechanism that has a corresponding surface configuration. 
         [0009]    One example handrail includes a plurality of co-extruded polymer materials. A first one of the polymer materials has properties that establish a gripping surface and a second one of the polymer materials has properties that establish high wear resistance, for example, in an inner portion. The handrail in one example includes a toothed driving surface. 
         [0010]    The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of a currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  schematically shows an example passenger conveyor incorporating a handrail designed according to an embodiment of this invention. 
           [0012]      FIG. 2  is a cross-sectional illustration of an example handrail as seen along the lines  2 - 2  in  FIG. 1 . 
           [0013]      FIG. 3  schematically shows one example driving surface. 
           [0014]      FIG. 4  shows another example driving surface. 
           [0015]      FIG. 5  schematically illustrates a method of making a passenger conveyor handrail according to one embodiment of this invention. 
           [0016]      FIG. 6  schematically illustrates a selected portion of another example method. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0017]      FIG. 1  shows a passenger conveyor  20  that includes a plurality of steps  22  that move in a known manner for carrying passengers between landings  24  and  26 . A handrail assembly  30  is associated with the plurality of steps  22  to allows passengers to brace themselves while riding on the conveyor  20 . The handrail assembly  30  includes a handrail and a balustrade  34 . A handrail guidance (not shown) facilitates the handrail  32  moving relative to the balustrade  34  to move in unison with the steps  22 . 
         [0018]      FIG. 2  shows, in cross-section, one example handrail  32  designed according to an embodiment of this invention. In this example, the handrail  32  comprises a plurality of polymer materials. In this example, a first polymer material  34  and a second polymer material  36  are shown. More than two materials may be used to meet the needs of a particular situation. Two materials are illustrated for discussion purposes. Those skilled in the art who have the benefit of this description will be able to select appropriate materials and combinations of them to meet the needs of their particular situation. 
         [0019]    The first polymer material  34  in one example comprises a thermoplastic polyurethane. In this example, the first polymer material  34  forms a relatively hard outer surface  38  that provides a passenger gripping surface. 
         [0020]    The second polymer material  36  establishes an inner portion of the handrail  32 . Using a second material  36  allows for using a less expensive material on the inside of the handrail, for example. The outer layer or gripping surface  38  must have a certain durability on the surface, for example. The inner portion made of the second polymer material  36  need not have such a characteristic but should have reasonable wear resistance characteristics and cost-savings may be achieved by appropriately selecting one or more second polymer materials  36  to form the inner portion of the handrail  32 . 
         [0021]    In one example, the second material  36  has a stiffness corresponding to a strength in the range from about 40 to about 50 mega pascal. In one example, the material has a shore hardness in a range from about 80 to about 90. Given this description, those skilled in the art will be able to select an appropriate material to meet their particular needs. 
         [0022]    Given the cross-section of the illustrated example, it is expected that relatively more raw material will be required for making the handrail  32  compared to conventional, more flattened-out designs. Using a plurality of materials allows for avoiding increased costs otherwise associated with a circular cross-section compared to the flattened-out designs of the past. In this example, there is some spacing that is not filled between the first polymer material  34  and the second polymer material  36 . This spacing is shown in  FIG. 2  at  39 . Other examples may include a third polymer material filling that spacing. Such a third polymer material can be selected from even less expensive materials as it does not have any outside surface requirements associated with performance of the handrail. One advantage of the illustrated example is that material selections can be made that provide cost savings compared to conventional designs. 
         [0023]    Additionally, selecting various polymer materials allows for controlling the stiffness and bending characteristics of the handrail so that a desired durability and surface texture can be achieved within given cost constraints. Those skilled in the art who have the benefit of this description will realize what material combinations will work best for their particular situation. Commercially available or custom designed materials may be used. 
         [0024]    One feature of the example of  FIG. 2  is that a toothed driving surface  40  is provided on an “inner” side of the handrail  32 .  FIGS. 3 and 4  show example toothed driving surfaces  40 . In each example, recessed portions  42  are interdigitated with teeth  44  that provide a drive surface to be engaged by a toothed sprocket or a toothed belt, for example. In the example of  FIG. 3 , the teeth  44  do not project outward beyond a finished inner surface on the handrail. In that example, the recesses  42  do not extend across the entire length of the drive surface  40 . In the example of  FIG. 4 , the recesses  42  are like grooves across the entire width of the drive surface  40 . 
         [0025]    Referring again to  FIG. 2 , the illustrated example includes a low-friction material slider layer  46  that facilitates the handrail  32  moving along a guidance. In one example, the slider layer material is adhered to the second polymer material  36  after that is extruded and while the material is still warm enough to readily achieve a sufficient bond between the slider layer material and the second polymer  36 . In another example, the slider layer is fed through the extrusion machinery and adheres to the material during the extrusion process. In one example, the low friction slider layer comprises a known material used for conveyor handrail slider layers. 
         [0026]      FIG. 5  schematically illustrates one example technique for forming the handrail  32  and establishing a toothed driving surface  40 . In the example of  FIG. 5 , molding machinery  50  includes a first extruder  52  that extrudes a first one of the polymer materials  34 , which is fed into the machinery  50  at  54 . A second extruder  56  extrudes a second polymer material  36 , which is fed in at  58 . The outputs from the extruders  52  and  56  are provided to a common molding device  60 . In this example, the molding device  60  has a plurality of manifolds  62 ,  64  as inputs for receiving the extruded materials  34  and  36 . A single output  66  is shaped or includes a die to establish the configuration of the handrail  32 . 
         [0027]    The illustrated example uses co-extrusion of a plurality of polymer materials for forming the handrail. Co-extrusion techniques are known and those skilled in the art who have the benefit of this description will be able to select appropriate materials and techniques for achieving a handrail configuration to meet the needs of their particular situation. The example of  FIG. 5  incorporates the use of the laminar flow principle that enables the two molten layers of material  34 ,  36  under proper operating conditions to join them in the common flow channel of the mold  60  with minimum intermixing of the materials at the contacting interface between them. This provides the multi-portion handrail design (i.e., an inner portion and an outer portion) as shown in  FIG. 2 , for example. 
         [0028]    In this example, two chambers following the manifold inlets  62  and  64  each include a width, length and height with a required cross-section to establish the corresponding portions of the handrail. The resulting product  32 ′ is stretched in the air and then passed through an arrangement for finishing the handrail. In the example of  FIG. 5 , a first wheel  70  engages the driving surface  40  on the “inner” side to establish the toothed driving surface  40 . In one example, the wheel  70  has a serrated exterior that induces the teeth on the driving surface  40  by cutting or pressing the extruded handrail material to form the recesses  42 . 
         [0029]    In the example of  FIG. 5 , a gripping surface finishing wheel  72  engages the gripping surface  38  and establishes a desired texture for the gripping surface. At the end of the process, a cooling bath  74  cools the materials of the handrail  32  so that it can be handled in a known manner for packaging and shipping to a job site. 
         [0030]    In another example, the toothed driving surface  40  is established during the co-extrusion process. As shown in  FIG. 2 , a load bearing member  80  is provided within the handrail  32 . In this example, a plurality of steel cords are supported at least partially within the second polymer material  36  to provide the load bearing member  80 . In one example, the toothed driving surface  40  is established in connection with providing the load bearing member  80  within the handrail  32 . 
         [0031]      FIG. 6  schematically shows a mold wheel  82  that is included as part of the extrusion machinery in one example and has a plurality of projections  84  and recesses  86 . The steel cords of the load bearing member  80  are supported along the projections  84  in the extrusion machinery so that the appropriate polymer material at least partially encases the load bearing member  80  and fills the recesses  86  on the mold wheel  82 . As the extruded material and the load bearing member  80  leave the mold wheel  82  the material already has a driving surface similar to that shown in  FIG. 4 . In such an arrangement, the wheel  70  of  FIG. 5  may be a guiding wheel without a serrated exterior surface to guide the handrail  32  toward the cooling bath  74 . The wheel  72  in such an example may be textured to provide a desired texture on the gripping surface on the handrail  32 . One example includes a control system for adjusting a required forming pressure on the driving surface  40 . 
         [0032]    The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this invention. The scope of legal protection given to this invention can only be determined by studying the following claims.