Abstract:
A flexible drive shaft for a turn portion of a transfer device, such as a conveyor. The flexible drive shaft can be made from wound steel, wound plastic, wound cable or other wound material. In one embodiment, multiple rollers are rotatably mounted to a support structure of the conveyor and traverse the turn portion of a conveyor. The flexible drive shaft can be mounted to the support structure, and can follow the turn portion. A connector can join the rollers and flexible drive shaft, so that force can be transferred from the flexible drive shaft to the rollers, causing them to rotate.

Description:
This application claims benefit of U.S. Provisional application 60/541,400, filed Feb. 3, 2004, which is hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to line shaft roller conveyor systems, and more specifically to drive shafts for such systems. 
     Roller conveyor systems are often used in production, transport and/or distribution settings to load, unload or otherwise move objects to a desired location. Roller conveyor systems are often used to move cardboard boxes, however, roller conveyor systems may be used to transport, load, unload or otherwise move virtually any type of object. 
     Many traditional roller conveyor systems utilize a belt to drive various rollers on the roller conveyor system. In belt-driven roller conveyor systems, a belt is typically attached to a power source at one end and connected to either a roller itself, or to a coupling device, which is attached to a roller. When under power, the end of the belt is turned by the power source, which ultimately turns multiple rollers, thus providing power to various rollers propels boxes and like objects along a designated pathway. 
     While many traditional roller conveyor systems utilize belts to drive various rollers, belt-driver roller conveyor systems (as opposed to shaft-driven systems) offer several disadvantages. The belt utilized in these belt-driven roller conveyor systems are typically made of high-density rubber, or other relatively flexible material, such that over time the belts crack, wear thin and/or break. In order to replace a cracked, worn thin and/or broken belt, the belt-driven roller conveyor system generally must be shut down for extended periods of time, while skilled laborers replace the belt. This may result in an interruption in business, which can cause delayed distribution and/or reduced sales. 
     Additionally, broken belts are problematic. To replace a broken belt, the belt-driven roller conveyor system usually must be shut down. Furthermore, when a belt breaks, it presents a potentially serious injury to any worker near the breaking belt. Also, over the course of time belts may stretch, causing them to slip. When a belt slips in a traditional roller conveyor system, it does not provide a steady, consistent and reliable connection to the power source. This can cause transportation inconsistencies on traditional belt-driven roller conveyor systems and ultimately may require shutting down the conveyor system and replacement of the belt that is slipping. 
     Roller conveyor systems may also be shaft-driven. Typical shaft-driven roller conveyor systems may have straight sections and/or corners, or corner sections, which allow the movement of objects not only in straight lines but around corners and bends. Conventional shaft-driven roller conveyor systems have multiple shafts connected by couplings and universal joints, hereinafter U-joints. In traditional shaft-driven roller conveyor systems, the multiple shafts are all straight, non-flexible shafts, which when connected to a U-joint may create an angle. When many straight non-flexible shafts are connected via U-joints, a corner or bend may essentially be formed by angling the shafts around a corner, thereby allowing the corner sections of roller conveyor systems to be shaft-driven. 
     However, there are many disadvantages associated with these types of shaft-driven roller conveyor systems. The U-joints which connect the straight, non-flexible shafts must be maintained. These joints require a proper fit, proper alignment, and proper lubrication. To align these straight, non-flexible shafts with U-joints, skilled laborers typically utilize large amounts of time to ensure proper alignment. Only then will these straight, non-flexible shaft-driven roller conveyor systems be functional. If a straight, non-flexible shaft becomes misaligned with a U-joint, the roller conveyor system must be shut down, a skilled laborer with the knowledge and know-how of aligning these types of systems must realign and/or replace either a straight, non-flexible shaft and possibly a U-joint. This shutdown of a straight, non-flexible roller conveyor system results in decreased and untimely distribution or transportation of objects. 
     Therefore, there is a need for a drive shaft for use in line shaft roller conveyor systems that has an increased reliability, decreased maintenance and decreased labor time due to the ease of installation of the drive shaft into a roller conveyor system. 
     SUMMARY OF THE INVENTION 
     The aforementioned problems are overcome in the present invention. One embodiment of the present invention includes a flexible drive shaft for a turn portion of a conveyor. The drive shaft can be made from wound steel. 
     These and other objects, advantages and features of the invention will be more readily understood and appreciated by reference to the detailed description of the invention and the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an installed flexible drive shaft of the present invention; 
         FIG. 2  is a second perspective view of an installed flexible drive shaft from an underside of a transfer drive; 
         FIG. 3  is a side perspective view of the installed flexible drive shaft; and 
         FIG. 4  is a top plan view of the flexible drive shaft. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     For purposes of description herein, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the exemplary drive shaft  10  as oriented in  FIG. 3 . However, it is to be understood that the drive shaft may assume various alternative 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. 
     One embodiment includes a flexible drive shaft for a turn portion of a transfer device, for example, a conveyor. The drive shaft is typically made from wound steel and a number of fittings are attached to the shaft. Referring to  FIGS. 1–3 , the drive shaft  10  can be installed in and be part of a conveyor of the type that typically conveys objects including, but not limited to, cardboard boxes; objects for transportation and/or distribution; and objects to load or unload, or any other type of object, including food stuffs. The flexible drive shaft as shown in  FIGS. 1–3  is installed in the turn portion  12  of a conveyor. 
     Referring to  FIG. 4 , drive shaft  10  includes a main shaft  14  which may be made of any material, including, but not limited to, wound cable, wound steel, or wound plastics, or any combination or derivation of any of the above. As used herein, “steel” can include any type of steel product, including stainless steel. As an example, the wound steel material can include a plurality of steel wires aligned generally in parallel, and individually or collectively wound in a helical or semi-helical fashion. The wound steel wires need not be in a helical configuration; other structures may be used as described. 
     The flexible drive shaft  10  may be any length. Typically, the flexible drive shaft  10  may range in length anywhere from about 1 inch to about 20 feet. Additionally, the flexible drive shaft  10  may vary in diameter. The diameter of the flexible drive shaft  10  may range from about ⅛ of an inch in diameter to about 6 inches in diameter. The preferred wound steel may be wound by any industrial acceptable means that provides flexibility to the shaft. The wound steel shaft should be at least flexible enough to form a curve or to be capable of the curvature typically required by corners, or the corner sections, of roller conveyor systems. For example, the wound steel shaft can be flexible enough to curve around turns or corners being angled at about 30°, about 45°, about 60°, about 90°, about 120°, or any other angle as desired. 
     Main shaft  14  of drive shaft  10  may include any number of fittings  16 ,  18 ,  20  and  22 . These fittings are generally adapted to receive drive spool  24  and connector  25  (see  FIG. 3 ). The drive spool  24  may be disposed between any of the fittings  16 ,  18 ,  20  and  22  and the connector  25 . The connector  25  extends between any of the fittings  16 ,  18 ,  20 ,  22  and the conveyor, or a coupling connected to the conveyor. A connector  25  connects the fitting  16 ,  18 ,  20  and  22  and drive spool  24  to the conveyor such that when main shaft  14  of flexible drive shaft  10  is turned, the connector attached to fittings  16 ,  18 ,  20  and  22  turns the conveyor roller  55  to which the connector  25  is attached. Typically, connector  25  is tensioned between drive spool  24  and the roller conveyor. If an object to be moved on the conveyor weighs too much for conveyor (i.e., if an object is placed on the conveyor that has a weight that is too great for the conveyor to move), drive spool  24  will slip and/or spin on the respective fitting(s) so that this weight resistance (i.e., increased torque and weight load) is not transferred to the power source. 
     The fittings  16 ,  18 ,  20  and  22  may be composed of any material, including, but not limited to, metal, plastic, wood, or any combination or derivation of any of the above. Additionally, the fittings  16 ,  18 ,  20  and  22  may be any shape as long as they are able to be attached to the main shaft  14  of the drive shaft  10  and are shaped to accept a line shaft conveyor drive spool  24 , with retaining ring grooves to maintain the drive spool position. The fittings  16 ,  18 ,  20  and  22  may be connected to the main shaft  14  of drive shaft  10  by any type of connection, including, but not limited to, soldered, welded, adhered, bonded, screwed, or any combination or derivation of any of the above. Typically, the number of fittings positioned on the main shaft  14  of drive shaft  10  ranges from about 1 fitting to about 15 fittings per main shaft section. The fittings  16 ,  18 ,  20  and  22  may be spaced apart from one another on main shaft  14  as necessary to accommodate the roller conveyor system in which the flexible shaft is installed. 
     The fittings can also be adapted for securement to a conveyor support structure  50 . In such a construction, the fittings can be captured by a bracket  52  which is further mounted to the support structure. The bracket can be configured to enable the fitting to rotate therein. Bearings or other components can be disposed around the fittings to improve rotation within the bracket  52 . The brackets can be spaced along the support structure to provide a desired amount of curvature in the drive shaft  10  around a turn portion of the conveyor. 
     Alternatively, main shaft  14  of drive shaft  10  may not include any fittings. Instead, the flexible drive shaft of the present invention may be used as a connector shaft to connect two separate flexible or non-flexible (i.e., traditional drive shafts) drive shafts. The flexible drive shaft of this embodiment may include a short shaft at each end of the flexible shaft. The short shafts are connected to the remaining drive shaft(s) and/or a power source. The short shafts are typically connected to other shafts and/or a power source by utilizing couplings. 
     The flexible drive shaft  10  can also include a layer, coating, or tubing  13  to protect the shaft from corrosion, abrasion and/or excess wear. In one embodiment, a plastic tube is positioned over the entire drive shaft  10 , or certain components as desired. The plastic tube can be shrunk, for example by heating, to be closely secured to the shaft. The tube can be cut in certain sections to expose the underlying fittings as desired. 
     Flexible drive shaft  10  eliminates the need for traditional straight non-flexible roller conveyor systems shafts of the past and U-joints. The flexible drive shaft  10  of the present invention enables a roller conveyor system to be utilized, which does not require a great deal of maintenance, prolonged shutdown time when a shaft needs to be replaced, or harbor the potential for injury as is the case with belt driven roller conveyor systems of the past. Rather the flexible drive shaft  10  of the present invention, when installed in a roller conveyor system, offers increased reliability and decreases the number of moving parts as compared to a straight non-flexible shaft-driven roller conveyor system of the past. Additionally, the flexible drive shaft  10  of the present invention is easy to install and offers decreased labor and decreased shutdown time if in fact a flexible drive shaft does need to be replaced. 
     The above descriptions are those of the preferred embodiments of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. Any references to claim elements in the singular, for example, using the articles “a,” “an,” “the,” or “said,” is not to be construed as limiting the element to the singular.