Abstract:
A conveyor assembly includes a mounting assembly for moving a material to be conveyed. The mounting assembly is movable in a first direction and in a second direction opposite the first direction. At least one resiliently deformable spring member is provided for storing energy therein responsive to a motion of the mounting assembly in the second direction. Energy stored in the spring member is usable to urge the mounting assembly and the associated material in the first direction.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of provisional application Ser. No. 61/125,491 filed on Apr. 25, 2008. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The embodiments of the present invention described herein relate to beltless conveyor systems for moving materials from one location to another. 
       SUMMARY OF THE INVENTION 
       [0003]    In one aspect, embodiments of the present invention include a conveyor assembly having a mounting assembly for moving a material to be conveyed. The mounting assembly is movable in a first direction and in a second direction opposite the first direction. At least one resiliently deformable spring member is provided for storing energy therein responsive to a motion of the mounting assembly in the second direction. Energy stored in the spring member is usable to urge the mounting assembly and the associated material in the first direction. 
         [0004]    In another aspect of the embodiments of the present invention, a method is provided for operating a conveyor so as to move a material in a first direction. The method includes the steps of providing a mounting assembly movable in the first direction and in a second direction opposite the first direction for positioning the material thereon; providing at least one spring member resiliently deformable for storing energy therein responsive to a motion of the mounting assembly in the second direction; urging the mounting assembly in the second direction to a first position to resiliently deform the spring member; and releasing the mounting assembly to enable movement of the mounting assembly in the first direction by a force exerted on the mounting assembly by the deformed spring member as the spring member returns to an undeformed state, thereby moving a material positioned on the mounting assembly in the first direction. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is a schematic view of a beltless conveyor system in accordance with one embodiment of the present invention. 
           [0006]      FIG. 2  is a perspective view of a conveyor assembly in accordance with one embodiment of the present invention. 
           [0007]      FIG. 3  is a plan view of the embodiment shown in  FIG. 1 . 
           [0008]      FIG. 4  is a side view of the embodiment shown in  FIG. 1 . 
           [0009]      FIG. 5  is an end view of the embodiment shown in  FIG. 1 . 
           [0010]      FIG. 6  is a perspective view of a mounting assembly in accordance with one embodiment of the present invention. 
           [0011]      FIG. 7  is a cross-sectional side view of an air cylinder incorporated into the embodiment shown in  FIG. 2 . 
           [0012]      FIG. 8  is a schematic view of a solenoid valve assembly incorporated into the embodiment shown in  FIG. 1 . 
           [0013]      FIG. 9  is a perspective view of a tray system mounted on the embodiment shown in  FIG. 1 . 
           [0014]      FIG. 10  is an isometric view showing the interior of a conveyor assembly in accordance with an embodiment of the present invention. 
           [0015]      FIGS. 11A-11D  show operation of a conveyor system in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Referring to  FIGS. 1-9 , a beltless conveyor system  10  in accordance with one embodiment of the present invention includes a control system  12  and a conveyor assembly  14  coupled to the control system for moving material positioned thereon responsive to commands from a user and/or the control system. 
         [0017]    Control system  12  includes a commercially-available, double solenoid-operated four-way valve  16  for regulating airflow to the conveyor assembly, and a controller  18  operatively coupled to the valve  16  for controlling valve actuation. Actuation of the valve  16  responsive to commands from controller  18  and/or a user controls operation of a mechanism (for example, an air cylinder  22  as shown in  FIG. 6 ) for moving a portion of the conveyor system including a table or tray  20  (see  FIG. 9 ) on which a material  100  is placed for movement. In the embodiments shown herein, tray  20  is operatively coupled to a shaft of the air cylinder so as to move in conjunction therewith. The inlets of valve  16  are operatively coupled to a source of pressurized air, and the outlets of valve  16  are operatively coupled to the air cylinder. 
         [0018]    Controller  18  controls actuation of solenoid valve  16 . Controller  18  may be any device capable of performing the control functions required for operation of the conveyor assembly as described herein. Controller  18  may be programmable directly by a user and/or may be capable of receiving control commands from an external or remote source (for example, a remotely located user, a computer, or another device or system). In one embodiment, controller is a programmable logic controller (PLC) having a screen display and a user interface such as a visual screen display and keypad to enable system programming or the input of system commands by a user. In another example, the control functions are performed by a programmable relay available from any of a variety of vendors, such as Rockwell Automation or Allen-Bradley. In a particular embodiment (not shown), diodes are operatively positioned between the relay and the solenoids to aid in protecting the relay from spikes in current. 
         [0019]    In a particular embodiment of the conveyor system described herein, elements of the conveyor system are modular, and the conveyor assembly  14  may be physically detached from the control system  12 . This enables a malfunctioning conveyor assembly  14  to be disassembled for repair or replaced in the conveyor system by another conveyor assembly  14 , which can be easily connected to the control system. The valve  16  is also physically separable from the controller  18  and conveyor assembly  14 . This modularity aids in minimizing the replacement costs of any element of the system, because there is no need to replace an entire integrated unit or assembly. 
         [0020]    Controller  18  may be programmed or receive commands through a manual interface  13 . Controller  18  may also receive commands from one or more external sources  11 . These external sources may include, for example, a device, a group of devices, or another system coupled to the conveyor system. The signals received from external sources  11  may include, for example, sensor data for use by controller  18  in generating an appropriate conveyor system instruction, or commands generated from outside the conveyor system. 
         [0021]    Referring to  FIGS. 1 and 7 , the stroke length of the air cylinder shaft  24  is controlled by controller  18  responsive to a timing signal from a first timer  26  incorporated into or operatively coupled to the controller. Similarly, the dwell time of the shaft  24  in any given position is controlled by controller  18  responsive to a timing signal from a second timer  28  incorporated into or operatively coupled to the controller. The controller  18  provides actuation signals to the solenoid valve  16  responsive to the timer signals. Alternatively, switching of the solenoid valve  16  may be responsive to a signal received directly from either or both of timers  26  and  28 . A known air filter and regulator package (not shown) may be coupled to the compressed air supply for the cylinder. 
         [0022]    Each of timers  26  and  28  comprises a circuit or device suitable for generating timing signals usable for actuating the air cylinder in accordance with set-up commands received from controller  18 , from a user, and/or from another source according to design and operational requirements. The timers  26  and  28  may be incorporated into the controller or the timers may be separate from the controller. 
         [0023]    The overall speed with which the material is conveyed will depend on such factors as the dwell time, the speed of movement of the cylinder shaft  24  (to which the tray  20  is connected), and the total distance which the tray  20  is to be moved by shaft  24  during the forward and reverse strokes of the shaft. The dwell time is controlled by timer  28 , and the total distance which the tray  20  is to be moved during the forward and reverse strokes of the shaft is controlled by temporal start and stop points determined by the settings of timer  26 . In a particular embodiment, the overall material travel speed is set by adjustment of the settings of timers  26  and  28  responsive to an output voltage (or control voltage) of a potentiometer (not shown) operatively coupled to the timers. The controller  18  is configured to adjust the settings of timers  26  and  28  corresponding to the potentiometer output voltage, so that a predetermined output voltage of the potentiometer corresponds to an associated material travel speed. In this manner, any of a continuous range of travel speeds may be provided. In addition, the material travel speed can be adjusted manually by turning a knob on a control panel. Alternatively, the control voltage may be generated by another element of the conveyor system or by an element external to the conveyor system, according to the requirements of a particular application. If desired, the system may be configured to limit the control voltage to within a predetermined range, so that the settings of timers  26  and  28  are correspondingly limited to within predetermined ranges. Increasing the time setting on the dwell timer  28  will increase the time between strokes, resulting in fewer strokes per unit time and less air usage. The distance the material moves per stroke is essentially unchanged. 
         [0024]    In a particular embodiment, the first timer  26  is pre-programmed by the conveyor system vendor, and is not re-programmable in the field. 
         [0025]    In a particular embodiment, the second timer  28  is operatively connected to a user-accessible potentiometer (not shown), thereby enabling the dwell time of the cylinder shaft  24  to be altered by turning a knob on a control panel. 
         [0026]    In a particular embodiment, the direction of travel of material  100  placed on the conveyor system is controlled by selective actuation of the solenoid responsive to a signal received from the controller  18 . A switch, such as a “forward/reverse” selector switch may be incorporated into a control panel, enabling selection of the material travel direction by a user. Alternatively, the signal controlling travel direction may be automatically generated based on an input or inputs to the controller, according to the requirements of a particular application. 
         [0027]    Referring now to  FIGS. 2-5 , the conveyor assembly  14  includes a base plate  30 , air cylinder  22  secured to the base plate, a pair of opposed endplates  32   a  and  32   b,  a pair of opposed side plates  34   a,    34   b  coupled to the endplates, and a top plate  36  coupled to the end plates and/or side plates to form an enclosure, generally designated  33 . A pair of guide rods  44  is mounted between end plates  32   a,    32   b.    
         [0028]    Referring now to  FIG. 6 , conveyor assembly  14  also includes a tray mounting assembly  38  is formed from a mounting plate  46 , a pair of ball bushing or bearing assemblies  40   a,    40   b  attached to the mounting plate, and a mounting bracket  42  attached to the mounting plate. In conveyor assembly  14 , bushing assemblies  40   a,    40   b  slide along respective ones of guide rods  44 . Mounting bracket  42  connects to the shaft  24  of the air cylinder  22 . Thus, motion of shaft  24  produces a corresponding motion of mounting assembly  38 . Ball bushings  40   a,    40   b  and guide rods  44  support the material being moved and the trays and framework that carry the material. Bushings  40   a,    40   b  and guide rods  44  also aid in isolating the cylinder from loads resulting from movement of the material positioned on the tray, and from movement of the trays and framework that carry the material. Referring to  FIG. 9 , a table or tray assembly  20  is secured to mounting plate  46  to serve as a material transport medium. 
         [0029]    Referring to  FIG. 4 , spring members C and D are secured within the enclosure between bushing assemblies  40   a,    40   b  and respective ones of end plates  32   a  and  32   b . Spring members C and D are compressed, stretched, or otherwise deformed so as to store energy which is used to impart a pre-load to the conveyor system for use in initiating motion of the mounting assembly. During operation of the conveyor system, the mounting assembly  38  is urged against either spring members C or spring members D at the end of each motion cycle to compress the spring members prior to reversing the direction of motion of the mounting assembly. In the embodiment shown in FIGS.  4  and  11 A- 11 D, spring members C and D are any compression spring members suitable for the purposes described herein. Some examples of suitable spring members are coil springs and spring members formed from a rubber, foam, or other resiliently compressible material. For purposes of illustration, the embodiments disclosed herein are shown using resilient cushions as spring members. The embodiments shown herein also incorporate two spring members. Alternatively, a single spring member may be used or more than two spring members may be used, depending on the configuration of the particular system and the requirements of a particular application. 
         [0030]    Operation of a conveyor system in accordance with an embodiment of the present invention will now be discussed with reference to  FIGS. 11A-11D . The embodiments of the present invention described herein implement a timed motion and shift cycle using the controller  18 , air cylinder  22 , and other elements previously described. 
         [0031]    Referring to  FIG. 11A , motion (in the direction indicated by arrow “A”) of an object or a quantity of material  100  positioned on the conveyor is generated by selection of a desired tray speed. The tray speed may be selected manually or automatically based on a predetermined set of criteria, according to the requirements of a particular application. 
         [0032]    When it is desired to move the tray material in direction “A”, the tray  20  may be loaded when spring members C are already compressed. Compression of spring members C will be described as a prelude to motion of tray material  100  in direction “A”. However, it is understood that spring members D could be pre-compressed in the same manner as described if it is desired to move the tray material  100  in direction “B”. 
         [0033]    Referring to  FIG. 11A , to compress spring members C prior to movement of the material  100  in direction “A”, the desired tray speed is selected, either manually or automatically. Selection of a desired tray speed results in actuation by controller  18  of solenoid  6  in solenoid valve  16  ( FIG. 8 ). This permits compressed air to flow through valve port  1  to cylinder port  2  ( FIG. 7 ). Valve port  4  is opened to exhaust air from the interior of the cylinder between piston  25  and an end wall  22   a  of the cylinder housing through which the shaft protrudes. The cylinder piston  25  moves in the direction indicated by arrow “B”, driving the mounting assembly  38  coupled to cylinder shaft  24  into spring members C and compressing the spring members to pre-load the spring members. The cylinder shaft comes to a stop with spring members C resiliently compressed by mounting assembly  38  until expiration of the dwell time period.  FIG. 11A  shows mounting assembly  38  at t 1 , the beginning of a direction “A” motion cycle, with spring members C pre-compressed. 
         [0034]    After the dwell timer period expires, a signal indicating expiration of the timing period is sent to solenoid  7 , activating the solenoid. This opens cylinder port  2  to exhaust gas from the cylinder interior between piston  25  and cylinder end wall  22   b,  and also opens cylinder port  4  to permit pressurization of the cylinder interior between the cylinder end wall  22   a  and piston  25 . 
         [0035]    Generally, there is a delay between reversal of airflow direction by the controller and initiation of mounting assembly motion while the internal cylinder pressure between the end wall  22   b  and piston  25  is relieved, and the pressure between endwall  22   a  and piston  25  builds up. However, because spring members C are present and are pre-compressed by the mounting assembly, as air is exhausted from the cylinder interior, the force compressing spring member C is released, permitting spring members C to decompress or expand. Decompression or expansion of spring members C imparts a slow starting acceleration to piston  25  and to the attached cylinder shaft  24  and mounting assembly  38  as the internal cylinder pressure between the end wall  22   b  and piston  25  is relieved, allowing the cylinder shaft  24  to move in the direction indicated by arrow “A”. In the manner described above, pre-compression of the spring members C by the mounting assembly  38  prior to reversal of the airflow direction enables motion of the mounting assembly to be initiated as soon as the cylinder internal pressure on the opposite side of the piston  25  has fallen enough to enable the piston to move in direction A. This reduces or obviates the above-mentioned delay in initiation of mounting assembly motion. 
         [0036]    Referring to  FIG. 11B , the mounting assembly  38  and tray  20  coupled to shaft  24  now accelerate in direction “A”. Since the decompressing spring member C initiates the motion of the mounting assembly  38  and tray  20  at a relatively slow rate, the static frictional connection between the material and the tray is not broken and the material moves with the tray instead of sliding along the tray. The cylinder shaft  24  continues to move in the direction indicated by arrow “A” until expiration of a predefined stroke time period (as determined by first timer  26 ).  FIG. 11B  shows the position of mounting assembly  38  at t 2 , the end of the stroke timer period. 
         [0037]    Referring to  FIG. 11C , at the end of the predetermined stroke time period, controller  18  again actuates solenoid  6  in solenoid valve  16  ( FIG. 8 ). This permits compressed air to flow through valve port  1  to cylinder port  2  ( FIG. 7 ). Valve port  4  is opened to exhaust air from the interior of the cylinder between piston  25  and an end wall  22   a  of the cylinder housing through which the shaft protrudes, and to permit the cylinder interior between piston  25  and end wall  22   b  to be pressurized. The cylinder piston  25  again moves in the direction indicated by arrow “B”, driving the mounting assembly  38  coupled to cylinder shaft  24  into spring members C and compressing the spring members to pre-load the spring members. 
         [0038]    The reversal of shaft direction occurs before the cylinder shaft  24  reaches the end of its stroke (i.e., prior to the point at which maximum travel of the shaft in direction “A” has occurred) and before the mounting assembly  38  reaches spring members D. Due to the suddenness with which the shaft stops and the dynamic inertia of the material  100  in direction “A”, the static frictional connection between the material  100  and the tray  20  is overcome. Thus, the material  100  continues to move in direction “A” (see  FIG. 11C ) after the shaft  24  stops and as the tray  20  moves out from under the material  100  in direction “B”.  FIG. 11C  shows the position of mounting assembly  38  at t 3 , after material  100  has moved along tray  20  in direction “A” and just prior to the reversal of direction of mounting assembly  38 . 
         [0039]    Referring to  FIG. 11D , the piston  25  and tray  20  continue traveling in direction “B” until the shaft  24  reaches the end of its stroke, compressing spring member C again to pre-load the spring member. The piston  25  then dwells in this position until expiration of the dwell timing period causes the piston to begin another motion cycle in direction “A”, as previously described.  FIG. 11D  shows mounting assembly  38  at t 4 , the end of the previously described stroke and prior to the beginning of a new stroke cycle, with spring members C pre-compressed again. 
         [0040]    The above sequence is repeated until the material is conveyed off of the tray in direction “A”. 
         [0041]    Reversing the direction of travel of the material  100  may be accomplished by a manual or automatically generated signal to controller  18 . The controller then generates a signal actuating the solenoid to control the compressed air flow to cycle the mounting assembly position so as to provide the desired material motion. Operation of the system to move the material in direction “B” is essentially opposite of that described above, with the mounting assembly piston initially being driven into spring members D to compress the spring member, and the mounting assembly being retained in this position until the dwell timing period expires. Also, in this operational mode, the piston and shaft reverse direction before the mounting assembly contacts spring members C. 
         [0042]    The compressed air pressure setting controls the energy imparted to the system for moving the connected load and the conveyed load. The connected load is defined as the load imposed by the elements of the conveyor system (such as the mounting assembly, any support bearings (not shown), and any trays mounted thereon) which are moved by the air cylinder during operation of the system. In order to move the material, sufficient air pressure must be provided to overcome the static inertia of the connected and conveyed loads. It is also desirable that the pressure setting not be so high that braking of the system elements comprising the connected load becomes prohibitive due to excessive dynamic inertia generated during the movement portion of the cycle. The compressed air pressure and speed control settings may be independently adjusted to achieve the most efficient operational mode for a given system loading. The precise settings for a particular system loading may be iteratively determined based on such factors as the desired conveyor speed and the magnitudes of the connected and conveyed loads. 
         [0043]    In a particular embodiment, any desired conveyor speed within a predetermined range can be achieved using a compressed air supply pressure setting between 20 and 60 PSIG. 
         [0044]    In another particular embodiment, the on/off function of the system is controlled by a selector switch that can be coupled to another controller or device (for example, a controller for a stamping press) to receive an actuation signal therefrom, if desired. 
         [0045]    In another particular embodiment, there are three predetermined conveyor speeds to choose from. The controller automatically sets the stroke length and dwell timers to provide an optimum cycle time for each predetermined conveyor speed. 
         [0046]    In another particular embodiment (not shown), the conveyor control system has an option that allows it to control two separate conveyor assemblies to enable, for example, two different directions of material travel simultaneously. 
         [0047]    The controller  18  in the system embodiments described herein allows the conveyor system to be electronically connected to other electronic machine controls so that it can be turned on or off in conjunction with other equipment, if desired. Also, because the system controls are electronic, an additional valve can coupled to the controller to permit two cylinders (and therefore two conveyor assemblies) to be operated from the same controller. This enables synchronization of the motions of the cylinders to optimize conveying capacity. The two conveyor assemblies can be installed to convey material in parallel, in opposite directions, or even in oblique directions with respect to each other. 
         [0048]    As stated previously, for purposes of illustration, the embodiments disclosed herein are shown using resilient cushions as spring members. However, any other suitable type of spring member may be used, according to the requirements of a particular application. For example, in an alternative embodiment (not shown), a pusher plate is positioned within enclosure  33  and is movably coupled to base plate  30  by one or more tension spring members (for example, coil springs). At the beginning of a mounting assembly motion cycle, the mounting assembly  38  is forced against the pusher plate so as to stretch or extend the tension spring members, thereby imparting a pre-load which bears against the mounting assembly as previously described. When the motion cycle is initiated by the controller, pressure exerted on the pusher plate by the mounting assembly is relieved, and the energy stored in the spring member(s) is expended to provide initial motion of the mounting assembly in the same manner as previously described. 
         [0049]    In a particular embodiment, a hard stop (not shown) is provided against which the mounting assembly  38  may abut to limit motion of the mounting assembly  38  in direction “B”, thereby effectively limiting the compression (or tension) in the spring member(s). The position of the hard stop may be adjustable (for example, using a threaded mounting) to enable the deflection of the spring member(s) (and the energy stored in the spring members) to be tailored to the requirements of a particular application. By this method, the amount of spring force acting on the mounting assembly  38  can be adjusted and controlled with some consistency. 
         [0050]    In addition, the system elements described herein are scalable, and additional load bearing capacity or conveyor length may be provided by sizing the components and adding components accordingly. 
         [0051]    It will be appreciated that the various constituents described above are formed in known manners. For example, the various components may be molded. stamped or otherwise metal formed from carbon steel, aluminum, metallic alloys, or any of a variety of polymers. 
         [0052]    It will be understood that the foregoing description of embodiments of the present invention is for illustrative purposes only, and that the various structural and operational features herein disclosed are susceptible to a number of modifications, none of which departs from the spirit and scope of the present invention. The preceding description, therefore, is not meant to limit the scope of the invention. Rather, the scope of the invention is to be determined only by the appended claims and their equivalents.