Abstract:
A modular conveyor belt formed of rows of belt modules pivotally interlinked by transverse pivot rods. The modules include a top, product conveying surface and a bottom, sprocket-driven surface. The belt modules have a plurality of first link ends disposed in the direction of travel of the conveyor belt and a plurality of second link ends disposed in the opposite direction. Transverse holes in the link ends are aligned to accommodate a pivot rod. When the link ends of the consecutive rows of side by side modules are intercalated, the pivot rod serves as a hinge pin in a hinged joint between consecutive interlinked rows. The transverse holes are disposed at an angle relative to the top surface of the belt module such that when the belt modules are connected to form a belt the transverse holes in adjacent link ends are disposed at opposite angles.

Description:
FIELD OF INVENTION  
       [0001]     This invention relates to conveyor belts and, more particularly, to modular plastic conveyor belts formed of rows of plastic belt modules pivotally interlinked by transverse pivot rods.  
       BACKGROUND OF THE INVENTION  
       [0002]     Because they are lightweight, do not corrode, and are easy to clean, unlike metal conveyor belts, plastic conveyor belts are used widely, especially in conveying food products. Modular plastic conveyor belts are made up of molded plastic modular links, or belt modules, that can be arranged side by side in rows of selectable width. A series of spaced apart link ends extending from each side of the modules include aligned apertures or holes to accommodate a pivot rod. The link ends along one end of a row of modules are interconnected with the link ends of an adjacent row. A pivot rod journaled in the aligned apertures of the side-by-side and end-to-end connected modules forms a hinge between adjacent rows. Rows of belt modules are connected together to form an endless conveyor belt capable of articulating about a drive sprocket.  
         [0003]     In order to avoid having parts of the goods that are to be conveyed, such as food particles, from entering into the apertures or holes in the link ends and contacting the pivot rods, which can cause unsanitary conditions, modular flat top conveying belts are typically designed such that when they are rectilinear, they form a totally continuous, planar conveying surface. Typically, the link ends are narrow and in an assembled conveyor belt, the interconnected link ends completely enclose the pivot rods where they pass through the link ends. Having large portions of the pivot rods fully enclosed at all times by the link ends prevents thorough cleaning of both the pivot rods and their apertures or holes, unless the conveying belt is dismantled.  
         [0004]     A conveyor belt constructed of modules designed such that the pivot rods and the link end apertures or holes can be cleaned without dismantling the belt is disclosed in U.S. Pat. No. 6,305,530 assigned to Habasit AG, which is the assignee of the present invention, and is incorporated herein by reference.  
         [0005]     While the belt module shown in the &#39;530 patent leaves open space on the side of the rod to allow access for cleaning fluid, the design reduces the link thickness above the oblong hole. This reduction in thickness may weaken the link and therefore limit the length of the oblong hole that is possible. Accordingly, there is a need for a design that provides open space on the side of the rod but does not significantly weaken the link.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention meets the above-described need by providing an endless conveyor belt formed of plastic belt modules having pivot holes in their link ends that are disposed at an angle relative to the plane defined by the top surface of the belt module. In comparison with a completely round hole, the shape of the angled, oblong pivot holes do not reduce the thickness of the module between the pivot holes and the top surface of the module. Therefore the pivot holes of the present invention do not significantly weaken the module and can be extended lengthwise to provide a larger opening for cleaning.  
         [0007]     The modules include first and second module surfaces, i.e., a top, product-conveying surface and a bottom, sprocket-driven surface. An intermediate section extends between the first and second module surfaces and across each module transverse to the direction of belt travel. The intermediate section supports a first plurality of link ends at one end and supports a second plurality of link ends at the opposite end. Elongate transverse holes are disposed in the link ends and are aligned to accommodate a pivot rod. When the link ends of consecutive rows of side-by-side modules are intercalated, the pivot rod serves as a hinge pin in a hinged joint between consecutive interlinked rows.  
         [0008]     The belt is driven by engagement of the teeth on a sprocket as known to those of ordinary skill in the art to which the invention pertains.  
         [0009]     In an assembled conveyor belt, adjacent belt modules align with each other such that the transverse holes in the adjacent link ends are angled in opposite directions. As a result, the pivot rod is captured by the respective holes in an overlapping area so that the pivot rod is confined to a portion of each of the elongate holes and is not free to move along the entire length of either of the holes. The cooperation of the adjacent angled holes prevents translatory motion of the pivot rod, and provides access to the transverse hole and to the pivot rod for cleaning. Accordingly, the present design provides for greater access to the inside of the transverse holes and to the pivot rods for better cleaning and easier maintenance. The enhancement is provided without introducing any undesirable translatory motion or “play” in the belt. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     The invention is illustrated in the drawings in which like reference characters designate the same or similar parts throughout the figures of which:  
         [0011]      FIG. 1  is a side elevational view of a prior art belt module;  
         [0012]      FIG. 2  is a top plan view of the belt module of the present invention;  
         [0013]      FIG. 3  is a bottom plan view of the belt module of  FIG. 2 ;  
         [0014]      FIG. 4  is a side elevational view of a belt module according to the present invention; and,  
         [0015]      FIG. 5  is a side elevational view of the belt of the present invention showing two belt modules with link ends intercalated. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]     In  FIG. 1 , a prior art module is shown, the curved portion  147  of the link end  132  is shown at one end of the figure and at the opposite end of the figure the curved surface  150  at the end of the second link end  138  is shown. Also, first and second elongate transverse holes  168 ,  171  are shown. The transverse holes  168 ,  171  have longitudinal axes  174  and  177  respectively. The transverse holes  168 ,  171  are preferably elongate and oval-shaped. The transverse hole  168  is angled at an angle α which is 10° to 80° relative to the horizontal axis defined by top surface  144 . The preferred embodiment provides for an angle α of approximately 45°. The transverse hole  171  on the opposite end of the module is rotated by approximately 90° such that it is disposed at an angle β approximately 100° to 170° to the top surface  144 . The preferred embodiment for the second hole  171  is an angle β of approximately 135°. As shown, the shape of holes  168  and  171  being elongate and extending at a 45° angle with respect to the top surface  144  results in a reduction in the distance D between the top of hole  168  and top surface  144 . This reduction may weaken the module as discussed above.  
         [0017]     Referring to FIGS.  2  to  5  generally and initially to  FIG. 5 , the flat top modular belt  20  of the present invention is formed from interconnected belt modules  23  and  26 . Although the belt  20  is shown with two modules  23 ,  26 , the belt  20  may include several modules in order to provide belts  20  having different widths. Also, each module does not have to be the same width, and the belt can be formed by arranging the modules  23 ,  26  in “bricklayed” fashion as will be evident to those of ordinary skill in the art.  
         [0018]     Referring to  FIG. 2 , belt module  23  is preferably formed out of plastic or other material suitable for food handling which is lightweight, does not corrode, and may be easily cleaned. The belt module  23  is preferably thermoformed out of a plastic resin raw material as known to those of ordinary skill in the art. The module  23  has an intermediate section  29  that supports a first set of link ends  32  disposed in the direction of belt travel indicated by arrow  35 . The direction of belt travel is provided for reference only as the belt  20  of the present invention may be driven in either direction. The link ends  32  have opposed side walls  33  providing a first transverse thickness  34 . The transverse thickness  34  is connected to the intermediate section  29  at a proximal portion  36  and extends from the intermediate section  29  in a direction of belt travel to a first distal portion  41 .  
         [0019]     The intermediate section  29  also supports a second set of link ends  38  that are disposed in the opposite direction from the first set of link ends  32 . The second link ends  38  also have opposed walls  43  defining a transverse thickness  49  and extending from a proximal portion  45  to a distal portion  48 . The spaces  39  between successive link ends  32 ,  38  are sized so as to accept a link end  32 ,  38  from an adjacent belt module (best shown in  FIG. 5 ). The intermediate section  29  and portions  40 ,  42  of the link ends  32 ,  38 , respectively, are coplanar along the top surface  44  such that the top surface  44  is substantially flat when adjacent modules  23 ,  26  are connected. The ends  47 ,  50  of the link ends  32 ,  38  are curved to fit into the curved section  53  (best shown in  FIG. 4 ) formed along portions of the edge  59  of the intermediate section  29 . Accordingly, when the belt  20  is assembled with pivot rods as described hereafter, the top surface  44  is substantially flat and the gaps, which are located between modules and where food parts can enter the belt  20 , are minimized.  
         [0020]     As shown in  FIG. 3 , the bottom surface  62  of the belt module  23  has a stiffening web  65  disposed along the center of the module  23 . The stiffening web  65  provides structural rigidity to the module  23  and also may be used for a contact point for the sprocket (not shown) that drives the belt  20  from below. As known to those of ordinary skill in the art, a drive sprocket may engage the link ends  32 ,  38  or the web  65  to drive the belt  20  from below. The modules  23 ,  26  are connected end to end as shown in  FIG. 5  and are combined with other modules to form an endless belt that is driven and guided by drive sprockets and idler sprockets (not shown) as known to those of ordinary skill in the art.  
         [0021]     As shown in  FIG. 3 , the curved portion  53  of the intermediate section  29  is disposed adjacent to the spaces  39  between the link ends  32 ,  38  to accept the curved portions  47 ,  50  of the link ends  32 ,  38 .  
         [0022]     Turning to  FIG. 4 , a module  23  has a top surface  44  disposed along an axis  200 . Link ends  32 ,  38  extend in opposite directions with respect to axis  200 . Stiffening web  65  extends downward relative to the top surface  44  and is disposed along a central longitudinal axis of the module  23  disposed normal to the page.  
         [0023]     Link end  32  is provided with a pivot hole  68  capable of receiving pivot rod  80  as shown in  FIG. 5 . The pivot hole  68  has an upper wall  203  disposed along an axis  206 . Upper wall  203  is substantially straight and is disposed substantially parallel to the top surface  44 . The pivot hole  68  also has a substantially straight wall  209  that is disposed along axis  212  which is disposed at an angle θ with respect to upper wall  203 . The angle θ is acute and in the example shown is approximately thirty degrees. Walls  203  and  209  are connected at opposite ends by curved portions  215  and  218 . Curved portion  215  is shorter in length than curved portion  218  because of the angle between the two walls  203  and  209 . Accordingly, because of the angle between the walls, pivot hole  68  has an overall shape that resembles a cone. The distance D 2  between the upper wall  203  and the top surface  44  is the same as for a standard module having a fully round pivot hole.  
         [0024]     The pivot holes  68 ,  71  have a rod receiving portion  72  indicated by broken lines in the figures. The rod receiving portion is disposed adjacent to curved wall  218 . From the rod receiving portion  72  to the opposite end where curved wall  215  is located the holes  68 ,  71  become narrower such that the pivot rod  80  is not capable of translatory motion when adjacent modules are intercalated.  
         [0025]     With reference to the right hand side of  FIG. 4 , pivot hole  71  is a mirror image of pivot hole  68 . When the modules  23  and  26  are intercalated as shown in  FIG. 5 , the holes  68  and  71  from adjacent modules overlap to form a substantially round portion that receives the pivot rod  80 . The remaining portions of the pivot holes  68  and  71  provide access to the pivot rod  80  for cleaning.  
         [0026]     Referring to  FIG. 5 , when the modules  23 ,  26  are intercalated, the pivot rod  80  is captured in the area of overlap of the adjacent holes  68 ,  71  and is not allowed to travel along the length of the elongated holes  68 ,  71 . In this manner and even though the angled holes  68 ,  71  are elongate, the link ends  32 ,  38  are fixed relative to each other and are not capable of translatory movement relative to each other. The link ends  32 ,  38  are only capable of rotating about the pivot rod  80  relative to each other. Accordingly, there is a very small, if any, amount of “play” in the direction of belt travel  35  or the opposite direction, and the modules  23 ,  26  cannot make translatory motion relative to one another.  
         [0027]     Accordingly, because the angled transverse holes  68 ,  71  are oversized and elongate relative to the pivot rod  80 , there is much greater access to the transverse holes  68 ,  71  and to the pivot rod  80  in comparison to conventional transverse holes. Accordingly, the belt  20  of the present invention is easier to clean without disassembling the belt. The link ends  32 ,  38  provide a gap, leaving the pivot rod  80  exposed from the bottom side of the module, whereas it remains totally closed from the top side. During cleaning operation pressurized cleaning fluid such as water spray may easily enter the gap from the bottom of the module and reach the exposed pivot rod  80  through the enlarged holes  68 ,  71 . Further, the transverse holes  68 ,  71  allow the fluid to enter from the side of the link and get access to the pivot rod also inside of the holes  68 ,  71 .  
         [0028]     While the invention has been described in connection with certain preferred embodiments, it is not intended to limit the scope of the invention to the particular forms set forth, but, on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.