Abstract:
A storage buffer for a multi lane conveyor system is provided, which generally consists of a carriage containing a plurality of storage magazines each having a plurality of storage conveyors, means for raising and lowering the carriage such that an article can be fed to and discharged from each storage conveyor, at least two drive systems for running the storage conveyors of each magazine one at a time, and at least two drive means for driving the two drive systems.

Description:
FIELD OF THE INVENTION 
     The invention relates to an apparatus for storing articles on a conveyor system. More specifically, the invention relates to a storage buffer for use in a conveyor system having at least two side-by-side driven lanes 
     BACKGROUND OF THE INVENTION 
     Due to space limitations and the cost of operating conveying lines, the efficiency of a conveyor system is a substantial consideration. Thus, buffer systems are often required to store articles on a conveyor system to maximize throughput efficiency. 
     Two lane conveying systems are desirable because they can effectively double the articles manufactured within a given time period. However, a major concern of two rail conveyor systems is the space required for such systems, particularly when a single lane conveyor, or a portion thereof, is being replaced by a two rail conveyor system. For instance, for the present invention it is desirable to have a space of only approximately one to two inches between the two lanes. 
     U.S. Pat. Nos. 4,964,498 to Klingl and 5,253,743 to Haas, Sr. et al. both disclose conveyors having side by side vertical storage buffers. U.S. Pat. No. 5,176,242 to Wegscheider discloses two buffer magazines 12, 32 positioned one after the other. The Klingl, Haas and Wegscheider conveyor systems, however, use the side by side buffers to efficiently convey articles in a single lane, not two lanes. 
     U.S. Pat. No. 4,561,819 to Wiernicki discloses a conveyor magazine having the shape of a vertical stack for storing printed circuit boards (PCBs). The Wiernicki magazine, however, does not include conveyors on each level of the magazine to load and withdraw articles. The Wiernicki magazine relies on rollers 80 external to the magazine to load and withdraw articles. Relying on an external drive system for a magazine can be disadvantageous if the magazine is being retrofitted to an existing system without an appropriate drive system. 
     None of the above patents discloses a storage buffer for use with a conveyor system having two side-by-side driven lanes. 
     What is desired, therefore, is a two magazine multi-level storage buffer that can convey articles on each storage level and be used with a conveyor system having two side-by-side driven lanes, and that adheres to strict width limitations between the lanes. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide a multi conveying lane storage buffer that occupies a narrow width. 
     It is a further object of the present invention to provide a multi conveying lane storage buffer that includes a conveyor on each level of storage. 
     It is yet another object of the present invention to provide a multi conveying lane storage buffer wherein the drive mechanisms for horizontally conveying articles within the buffer are contained within the buffer walls. 
     It is still another object of the present invention to provide a multi conveying lane storage buffer wherein the opposing side walls for the buffer are identical in construction. 
     These objects of the invention are achieved by a storage buffer for a multi lane conveyor system, which generally consists of a carriage containing a plurality of storage magazines each having a plurality of storage conveyors, drive means for raising and lowering the carriage such that an article can be fed to and discharged from each storage conveyor, at least two drive mechanisms for running the storage conveyors of each magazine one at a time, and at least two drive means for driving the two drive systems. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front isometric view of the storage buffer for a multi lane conveyor in accordance with the present invention. 
     FIG. 2 is an exploded front isometric view of an external wall of the storage buffer of FIG.  1 . 
     FIG. 3 is a partial exposed side view of an external wall of the storage buffer of FIG.  1 . 
     FIG. 4 is a partial front isometric view of a belt mechanism and a drive mechanism of the storage buffer of FIG.  1 . 
     FIG. 5 is a partial front exposed view of the of the storage buffer of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The storage buffer  10  in accordance with the present invention is shown in FIG.  1 . The storage buffer  10  includes a housing  11  and a carriage  12  within the housing having first and second magazines  15 ,  17 . The first magazine has two mirror image side walls  14 ,  16  and the second magazine has mirror image side walls  18  and  20 . Horizontal members  88  and  90  connect the four side walls  14 ,  16 ,  18 ,  20  together. 
     The height of carriage  12  is preferably adjusted by a servo motor  31  having a threaded screw  26 . Alternatively, instead of a motor  31 , other means could be used to adjust the height of carriage  12 , such as a pneumatic or hydraulic motor. A ball bushing  28  has an internal thread and is threadedly attached to the screw  26 . The ball bushing  28  is attached to the buffer carriage  12  and moves the carriage vertically when the bushing moves vertically along the screw  26 . A linear bearings assembly  29  keeps the carriage  12  from tilting as it is moved vertically and is preferably placed on both outside walls of the carriage. The linear bearings assembly includes linear bearings  24  attached to the outside walls of the carriage  12  and linear guides  25  attached to the housing. Each of the linear guides  25  moves through one or more linear bearings  24  which guide the movement of the carriage  12  as it moves vertically. 
     Two width adjustment cranks (not shown) allow the separate adjustment of width of the first and second magazines respectively. One crank adjusts endless belt  84  around wheel  80  which is connected to a threaded shaft  74  that adjusts the width of the first magazine. Another crank adjusts endless belt  86  around wheel  82  which is connected to a threaded shaft  76  that adjusts the width of the second magazine  17 . 
     Each storage magazine  15 ,  17  has a plurality of storage conveyors  23 . Referring now to FIGS. 2,  3  and  5 , each storage conveyor  23  comprises opposing belt mechanisms  50  having endless belts  51  driven by wheels  52  and  53 . Wheel  52  has a shaft that is connected to a spring loaded belt take up  54 . Each belt take up  54  snugly fits into one of a plurality of panel slots  55 , each being located in the side walls  14 ,  16 ,  18 ,  20  at each conveyor level. Wheel  53  is connected to shaft  56  which has connected to it a knurled driven roll  62  between two bearings  58 ,  60 . The shaft  56  fits into one of the holes  68  in the cover  66  of the side walls  14 ,  16 ,  18 , and  20 . The knurled driven roll  62  is connected to shaft  56  by a set screw  64  that is screwed into a dimpled hole that extends through the roll and into the shaft. The knurled driven roll  62  is driven by the endless belt  35  of conveyor drive system  49  when the mechanism  30  is adjacent the knurled driven roll. 
     Each drive mechanism  30  includes a pressure wheel  36  and preferably two opposing rollers  32 ,  34  configured such that an endless belt  35  can pass between the wheel and rollers. The drive mechanism  30  preferably further includes a positioning bar  40  that can slide vertically in a recess  41  to initially position the drive mechanism near the conveyor infeed. The positioning bar  40  can be secured in the recess  41 , for example, by fastening a screw  92  through a slot  94  in the positioning bar. The drive mechanism  30  has covers  38  and  44  to contain the endless belt  35  and positioning bar  40 . A slot  42  is provided for the return passage of the endless belt  35 . 
     Preferably, the wheels herein are toothed wheels and the belts are toothed belts. Alternatively, bands, cords or chains could be used in place of the belts. 
     Each conveyor drive system  49  includes a motor  22 , a drive wheel  46 , a driven wheel  48  and a drive mechanism  30 . With the exception of motors  22 , each buffer side wall  14 ,  16 ,  18 ,  20  has located within its interior a conveyor drive mechanism  49  for driving the conveyors on each level one at a time. Each motor  22  is located at the top of the side wall  14 ,  16 ,  18 ,  20  above the storage conveyors  23 , which drives an endless belt  35  being looped around a drive wheel  46  and a driven wheel  48 . Other drive means instead of motors  22  could be used to drive the conveyor drive system  49 , such as a pneumatic or hydraulic motor. The belt  35  is preferably an endless toothed belt to prevent belt slippage. The endless belt  35  engages the pressure wheel  36  and two opposing rollers  32 ,  34  of the drive mechanism  30 . The drive mechanism  30  remains stationary with respect to the carriage  12  as the carriage moves vertically. 
     When an article is desired to be fed into or discharged from the buffer, the storage conveyor  23  of the buffer is moved near the infeed conveyor  67  by adjusting the height of the carriage  12  using the servo motor  31 . As shown best in FIG. 4, when the desired storage conveyor  23  is horizontally adjacent the drive mechanisms  30 , the rolls  62  from the belt mechanisms  50  come into contact with the endless belts  35  being pressurized by the pressure wheel  36  and the springs  61 . It should be noted that when drive mechanism  30  is moved adjacent to or past a belt mechanism  50  and belt  35  comes into contact with roller  62 , the belt may rotate the roller a small amount. 
     For each magazine  15 ,  17 , the motors  22  connected to its side walls are operated in sync, but with opposite rotation. If the first magazine  15  needs to be loaded or discharged, motors  22  mounted to walls  14  and  16  are run which drives two belt mechanisms  50  for the conveyor  23  of the first magazine  15 . Likewise, if the second magazine needs to be loaded or discharged, motors  22  mounted to walls  18  and  20  are run. For each magazine  15 ,  17 , the two corresponding motors  22  are required to have opposite rotations for two opposing belt mechanisms  50  to operate in union. 
     Preferably, as shown in FIG. 1, the buffer  10  comes with an infeed conveyor  67  and a discharge conveyor  69  that can be disabled. The drive mechanism  30  is located near the infeed conveyor  67  such that the drive mechanism will operate the conveyor of the carriage level near the infeed conveyor. 
     Preferably, to control the operation of the buffer  10 , a microprocessor (not shown) is used to control the vertical adjustment of the carriage  12 . Generally, the buffer  10  will function as either a first-in first-out buffer to keep the articles in a sequential order or a last-in first-out buffer to minimize cycle time of the articles. The microprocessor may be interfaced or networked with other processors or computers that control a manufacturing system used in conjunction with the buffer  10 . 
     In operation, an article  13  such as a printed circuit board (PCB) is transported to the buffer  10  by an infeed conveyor  67 . The microprocessor decides whether the buffer carriage  12  needs to be adjusted vertically to store the article. If necessary, the carriage  12  is adjusted vertically by operating the servo motor  31  which locates the drive mechanisms  30  to the desired level in contact with the belt  35 . Motors  22  are then operated in pairs to move one or both conveyors  23  at the infeed conveyor. The magazines  15 ,  17  are also discharged by vertically adjusting the carriage  12  and operating the motors  22  to move a conveyor  23 . 
     Although the description and drawings show the invention as having two magazines  15 ,  17 , it should be apparent that the present invention could include one or more magazines by removing or adding more side walls  14 ,  16 ,  18 ,  20 , horizontal supports  80 ,  90 , storage conveyors  23 , conveyor drive mechanisms  30 , and motors  22  as described herein. 
     It should be apparent to one skilled in the art that each magazine  15 ,  17  could vertically moved independently of the other such that each magazine  15 ,  17  can intake and discharge articles independently. To facilitate this, each magazine  15 ,  17  can be independently adjusted vertically by independent servo motors  31  and each conveyor can have its own linear bearing assembly  29 . It should also be apparent that one set of motors could operate four conveyor drive mechanisms. To accomplish this, one motor  22  can use a common shaft or a universal joint connected to a common shaft used by two drive mechanisms. 
     It should also be apparent that one drive mechanism could be used for each magazine  15 ,  17  by having one of the gears  52 ,  53  of each opposing belt mechanisms  50  share a common shaft. Finally, it is also apparent that each conveyor  23  can only include one belt mechanism  50  wherein the endless belt  51  covers the inside width of its respective magazine. Where only one belt mechanism  50  is used, however, the width of the conveyors  23  may not be adjustable. 
     It should be understood that the foregoing is illustrative and not limiting and that obvious modifications may be made by those skilled in the art without departing from the spirit of the invention. Accordingly, reference should be made primarily to the accompanying claims, rather than the foregoing specification, to determine the scope of the invention.