Abstract:
An apparatus and method for conditioning conveyor chains in commercial ovens of the type having a continuous conveyor chain supported in a track for transporting bakery products through the oven. A portion of the conveyor chain and supporting track transits outside the heated baking area of the oven and an automatic chain lubricator is positioned along the portion of the track transiting outside the baking area of the oven. A fan for creating a flow of cooling air and at least one air duct are located outside the baking area. The duct receives one end cooling air from the fan and directs the cooling air on to the conveyor chain along the portion thereof located outside the heated baking area of the oven and upstream from the lubricator. Also, an air knife is disposed upstream of the lubricator and directed onto the chain to remove undesired debris, etc., therefrom.

Description:
BACKGROUND OF THE INVENTION 
     Modem bakery operations use conveyorized ovens incorporating long continuous chains supporting grids upon which bakery products in pans are transported throughout the oven for baking. The chain utilized in these ovens can be of considerable length, often greater than 1,000 feet, and since it is in the oven the majority of the time, the chain becomes very hot, rising to temperatures which are close to that of the inside of the oven, often as much as 450° to 480°. The chain is supported on a large number of wheels running in a partially enclosed track. Each of the wheels is rotatingly mounted by a bearing and the proper operation of these wheels and bearings is critical to the efficient operation of the oven. A failure of one or more bearings causes additional loading on adjacent wheels and bearings and can cause premature wear or serious friction damage to the track material. Therefore, in order to keep the bearings operating efficiently they are lubricated by a high speed oil injector system which operates at regular intervals, typically every three to four hours. 
     Because the ovens are used in the preparation of food articles, only a limited number of approved lubricants can be used, and all of the available and affordable lubricants have degraded performance at oven baking temperatures, evaporating quickly or degenerating to carbon deposits which obstruct subsequent lubricant application. 
     The failure of the lubricant to fully penetrate and carry the lubricant to the center of the bearing causes premature bearing failure and thus higher operating costs and increased down time to repair the oven. An alternative method of lubricating the chain and bearings is accomplished by turning the oven off and allowing the chain to cool. After the chain has cooled, the wheels and bearings can be lubricated without the problem of premature evaporation of the lubricant carrier. However, this method requires extensive down time of the oven since the oven must be turned off and allowed to cool prior to lubricating the chain, and this adversely impacts the productivity of the oven. 
     Thus, there is a need within the industry for a new and improved method and apparatus by which such oven conveyor chains may be more effectively lubricated, in a manner such that the lubricant penetrates throughout the bearing while minimizing the down time of the oven. 
     SUMMARY OF THE INVENTION 
     One aspect of the present invention is an apparatus for conditioning conveyor chains in commercial ovens of the type having a continuous conveyor chain supported by a track for transporting bakery products through the oven. A portion of the conveyor chain and supporting track transits outside the heated area of the oven to facilitate the adding and removal of bakery products to be conveyed through the oven for baking. The conditioning apparatus includes a fan for creating a flow of cooling air, and at least one air duct having one end proximate to the fan for receiving a portion of the flow of cooling air and a second end disposed proximate the conveyor chain along the portion thereof located outside the heated baking area of the oven, at a point upstream for the lubricator, wherein the second end of the duct directs a flow of air across the conveyor chain at that point. 
     Another aspect of the present invention is a method of conditioning conveyor chains in commercial ovens of the type having a continuous conveyor chain including wheels and bearings and disposed in or on a fixed track for transporting bakery products through the oven. A portion of the conveyor chain and fixed track transits outside the heated area of the oven to permit the adding and removing of bakery products for baking in the oven. An automatic chain lubricator is positioned along the portion of the fixed track transiting after the cooler outside the heated area of the oven. The method comprises the steps of establishing a flow of cooling air of a lower temperature than the conveyor chain; directing the cooling air flow onto the conveyor chain while the chain is exterior to the heated area of the oven; and, at predetermined intervals, injecting a flow of lubricant into the bearings of the wheels of the conveyor chain. 
     These and other features, advantages and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims and appended drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a plan view showing one example of a conveyorized oven, having a portion of the conveyor exterior to the oven and including a chain-conditioning system embodying the present invention; 
     FIG. 2 is a side elevational view taken along plane II—II of FIG. 1; 
     FIG. 3 is a fragmentary enlarged top plan view of the conditioning system; 
     FIG. 4 is a further enlarged fragmentary cross-sectional view of the conveyor taken along plane IV—IV of FIG. 3; 
     FIG. 5 is a fragmentary sectional elevational view of the conveyor chain in the conveyor track, taken along the plane V—V of FIG. 4; 
     FIG. 6 is a fragmentary sectional top plan view of the conveyor chain in the fixed track, taken along the plane VI—VI of FIG. 5; 
     FIG. 7 is a further enlarged, fragmentary sectional view of the fixed track having a cooling duct attached to the sides of the track, taken along the plane VII—VII of FIG. 3; and 
     FIG. 8 is a fragmentary, cross-sectional view similar to FIG.  7  and on the same scale, showing the fixed track having a cooling duct attached to a bottom of the track, taken along the plane VIII—VIII of FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     For purposes of description herein, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the invention as oriented in FIGS. 1 and 2. However, it is to be understood that the invention may assume various orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
     Reference numeral  10  in FIGS. 1 and 2 generally designates a conveyorized commercial oven system which in this case includes a conveyor chain conditioning system embodying the present invention, which is particularly designed to cool the conveyor chain of such an oven and thereby facilitate proper lubrication thereof. In the illustrated example, a typical conveyorized commercial oven of the “Lanham type” is shown in FIGS. 1 and 2, which includes an oven enclosure  12  within which a conveyor  14  travels on a “figure-eight” shaped (or oval or double oval) vertically layered endless path while carrying product through the oven for baking. While the majority of conveyor  14  is located inside the oven enclosure  12 , a portion  16  of conveyor  14  extends outside of oven enclosure  12  between an entrance opening  18  and an exit opening  20 . Conveyor portion  16  typically has a movable U-shaped section  17  which can be moved and adjusted with respect to the remainder of conveyor  14  to compensate for thermal expansion or contraction and for wear. U-shaped section  17  has connected thereto a chain-cooling system  80  and an “air knife”  70  which comprise one embodiment of the present invention. The most convenient location for the system  80  is in the curve of the conveyor between the load on and load off of the oven, but it could be located on any straight or curved section, best results being achieved by the maximum cooling of the chain before the lubricator (described hereinafter). The structure and operation of the preferred embodiment is discussed in detail below. 
     Referring to FIGS. 3-6, conveyor  14 , of which external portion  16  is a part includes a central fixed track  22  supported in the desired looping and/or spiraling pattern by support structure  21 . Track  22  (as shown in FIGS. 7 and 8) is generally rectangular in cross section having a bottom  28 , an inside track wall  24 , an outside track wall  26 , and a top  30 . Top  30  has a slot  32  therein. Slot  32  extends the entire length of track  22 . As shown in FIGS. 5 and 6, a conveyor chain  34  is housed within track  22  for continuous movement along the length of conveyor  14 . Conveyor chain  34  supports a plurality of regularly spaced pendants  36  therealong which extend vertically through slot  32  and support a plurality of grids  38  for carrying pans or trays of dough or the like to be baked in oven  10 . 
     Referring again to FIGS. 5 and 6, conveyor chain  34  includes a plurality of regularly spaced drive links  50  which support at a central portion thereof a pair of vertical wheels  52  which are rotatingly support by vertical bearings  54 . Successive or adjacent drive links  50  are interconnected one to the other by upper and lower connector links  56  and  57 . Ends of upper connector link  56  overlay a top end surface of adjacent connector links  50  and lower connector links  57  underlay lower surfaces of adjacent connector links  50 . Connector links  56  and  57  are pivotally joined to connector links  50  by connector bolts  58  in such a manner to form conveyor chain  34  of alternating drive links  50  and pairs of connector links  56  and  57 . Vertical wheels  52  support chain  34  on bottom  28  of fixed track  22 . A horizontal wheel  60  is mounted between each upper and lower connector link  56  and  57 , respectively, substantially at a midpoint along connector links  56  and  57 . Horizontal wheel  60  is rotatingly supported by bearing  62  and provides lateral stability to chain  34  by rotating contact with either of side walls  24  or  26 . 
     Referring again to FIG. 3, an automatic lubricating system  64  is typically installed to automatically apply lubricant to vertical and horizontal bearings  54  and  62  as they transit along track  22  along the exterior portion  16  of conveyor  14 . 
     Referring again to FIGS. 3,  7 , and  8 , one embodiment of a cooling apparatus for chain  34  in accordance with the invention is shown generally at  80 . Cooling apparatus  80  includes a high-volume fan  82  which collects ambient air and directs the air into flexible duct  84 . Duct  84  in the preferred embodiment is flexible to permit the stationary mounting of fan  82  while permitting U-shaped section  17  of conveyor  14  to be positionally adjusted to compensate for thermal expansion and wear on conveyor  14 . Flexible delivery duct  84  is connected to air distributor  86 , which distributes the air-flow along the exterior curved portion of track  22  via a plurality of cooling ducts  88  and  90 . Since conveyor chain  34  includes both horizontally and vertically oriented elements, it is desirable to provide both a horizontal and a vertical air flow against chain  34 , to maximize the cooling effect. Thus, in the preferred embodiment shown, both horizontal cooling ducts  88  and vertical cooling ducts  90  are attached to track  22  to deliver cooling air therein. 
     FIG. 7 illustrates the attachment of a horizontal cooling duct to track  22 . Track  22  has an aperture  87  formed in outside wall  26  of track  22 , and horizontal cooling duct  88  is attached thereto so that air flow  94  flows from duct  88  to an interior portion of track  22 . The air circulates around chain  34  and exits through slot  32  into the ambient area of the room or building housing the oven system  10 . As conveyor chain  34  transits through U-shaped section  17  of conveyor  14 , horizontal wheels  60  bear against inside wall  24  of track  22 . It is desirable to maintain a continuous surface for wheel  60  to bear against, for maintaining smooth operation of conveyor chain  34 . Therefore, apertures  87  are formed in outside track wall  26  to prevent discontinuities in the wall surface against which horizontal wheel  60  bears. 
     Similarly, as shown in FIG. 8, bottom apertures  92  are formed in track bottom  28  and vertical cooling ducts  90  are attached thereto in such a manner as to permit air flow  94  to flow from the bottom of track  22  across chain  34  to exit slot  32  in top  30  of track  22 . Apertures  92  are positioned centrally in bottom  28  thereby maintaining a continuous surface adjacent the sides of track  22  upon which wheels  52  will bear as chain  34  transits through U-shaped section  17  of track  22 . Preferably, apertures  92  are slot-like in nature, being elongated along lengthwise of track  22  (see FIG.  9 ), with box-like plenums (not shown) below them (under the track) to help distribute the air flow along their length. It will be understood that the number, location, and orientation slots  92 , of cooling ducts  88  and  90  can be varied and altered to facilitate alternate track and conveyor chain configurations. 
     Referring again to FIG. 3, an air knife system  70  is also preferably included upstream from cooling system  80 . Since the lubricants delivered to the hot chain  34  by automatic lubricating system  64  tend to leave deposits on conveyor chain  34 , and some of these deposits can fall or be dislodged from chain  34 , the flow of cooling air from cooling system  80  could potentially result in the unwanted distribution of dirt particles throughout the ambient air in the vicinity of the area on which baking products are onloaded and offloaded to conveyor  14 . Thus, it is desirable to remove as much of such deposits from conveyor chain  34  as possible. In the present embodiment, these deposits are removed by air knife system  70 . Air knives are generally well-known in industry. The air knife envisioned for use to remove deposits from the conveyor chain  34  includes a high-pressure air supply  72  which directs high-pressure air to one or more air knife nozzles  74  in such a manner as to direct a high velocity, high pressure stream of air across conveyor chain  34 , to dislodge the maximum amount of lubricant and dirt deposits therefrom. Air knife system  70  is preferably positioned upstream from cooling system  80 , so that deposits can be stripped and collected from conveyor chain  34  before it is subjected to cooling air flow and thereby minimizing the amount of dirt particles which are carried into the ambient air by air flow  94 . The deposits and dirt dislodged by nozzles  74  can be collected and disposed of in a generally know manner. 
     In operation, as conveyor chain  34  transits through exit opening  20  of oven enclosure  12  at the beginning of the automatic lubricating system, air knife  70  begins operation to dislodge built-up lubricant deposits and dirt from chain  34 . As chain  34  transits through U-shaped section  17  of track  22 , high-volume fan  82  collects ambient air, typically at 80° to 90° F. and feeds the air through duct  84  to distributor  86 . The air is further distributed to cooling duct  88  and  90 , to be blow across chain  34  at a plurality of locations. Automatic lubricator  64  also begins operation to inject lubricant into bearings  54  and  62  through injectors  68 . Once the entire length of chain  34  has made the complete circuit of conveyor  14 , automatic lubrication system  64 , air knife,  70 , and cooling system  80  are disabled until the next timed automatic lubrication cycle is to be accomplished, wherein the process is repeated. 
     The above description is considered that of the preferred embodiments only. Modifications of the invention may well occur to those skilled in the art and to those who use or otherwise learn of the invention. Therefore, it is understood that the embodiments shown in the drawings and described above are merely for illustrative purposes and should not be used to limit the scope of the invention, which is defined by the following claims as interpreted according to the principles of patent law, including the Doctrine of Equivalents.