Abstract:
An interlocking transfer system includes a workstation having four or more sides, each of which is positioned at 90° angles from the next adjacent side. A cam lift assembly is provided on each of the sides and a means for moving the pallets horizontally. The cam lift assembly is actuated by a reciprocating cylinder which operates to lift and lower the pallets. While pallets are lifted, they are also advanced horizontally using either an external reciprocating cylinder, a motor or by hand. The interlocking transfer system of the present invention provides high efficiency and low transfer rate. It also eliminates the need for lift and locate devices, transfer space due to traffic control, and end-to-end cross transfers. The interlocking transfer system of the present invention also provides for interchangeable fixtures.

Description:
FIELD OF THE INVENTION  
         [0001]    The device of the present invention relates generally to transfer systems and the like. More specifically, it relates to automated workstations for use in production facilities.  
         BACKGROUND OF THE INVENTION  
         [0002]    Many present day industries use a conveyor type transfer system, whether it is belt drive or chain drive, to transfer pallets from one point to another. Conveyor systems must either run continuously or must be stopped at each workstation. Stopping at each workstation leads to excessive wear and tear on the drivetrain of the conveyor. If the conveyor does not stop at each workstation, then there must be a device that provides for a positive stop so that work may be performed on the product. A second stop, or cue stop, is also required so that the parts that are advancing toward the workstation do not collide with the part being worked on.  
           [0003]    The disadvantages to this type of system are obvious. First, there is the problem of belt wear. If the belt is moving and the pallet is stationary, the movement of the belt will cause wear on both the pallet and the belt. The alternate solution, stopping the conveyor at each workstation, merely switches the wear problem from the belt to the drivetrain of the conveyor.  
           [0004]    Another problem with prior devices of this type is excessive transfer time. Conveyors generally require a three to four second cycle time for a pallet that is being worked on to move on to the next workstation and the next pallet to move into the first pallet&#39;s workstation. The device of the present invention reduces the transfer time to about one second because all of the pallets move simultaneously, thus eliminating the need for pallets to be cued up behind each workstation and thereby increasing productivity.  
           [0005]    Prior devices also take up more space. Manufacturing space is prime real estate. Thus, bulky prior transfer devices have high overhead requirements. For example, a standard conveyor device requires a pallet at each workstation and space for a pallet in cue. The device of the present invention allows a workstation over each pallet. Thus, the device of the present invention requires only one-half the space of prior transfer systems. The device of the present invention also eliminates the need for complicated systems for transferring pallets from conveyor to conveyor, thus conserving even more space.  
           [0006]    An additional problem is that prior devices require several drive motors to accomplish the same thing that the device of the present invention can accomplish with just a single motor. For example, a conveyor system that must turn a complete square will need at least four power sources, one for each side of the square. This inventor is also aware of several conveyor systems which require an additional operation to transfer around corners. The device of the present invention can be powered by a single cylinder, a single servo motor, or even by hand.  
           [0007]    Prior devices are also handicapped by their requirements for multiple mechanically actuated stops around the conveyor belt for workstations and for cues before the workstation. All of the stops require some form of automation, including complicated sensors for detecting the location of pallets and complex software to keep track of all the operations occurring throughout the conveyor system. The device of the present invention virtually eliminates the requirements for sensors and software because the device is “intertwined” in such a way that each pallet moves in lockstep with every other pallet.  
           [0008]    A further limitation of prior devices is that they require a “pick and place” operation for precision manufacturing. The device of the present invention reduces the time necessary for precision machining by providing bushings within each fixture. Thus, each workstation operation can be completed on the fixture itself, reducing the amount of time necessary for procedures and eliminating the need for pick and place machining operations. This inventor is not aware of any prior devices that accommodate this requirement with the simplicity of the device of the present invention.  
           [0009]    The device of the present invention also offers extraordinary versatility. For example, the device may be adapted to use different size square pallets or even rectangular pallets. The device may also be assembled in virtually any configuration having 90-degree angles. For example, a manufacturer may need a very simple series of operations and employ a simple square transfer system. A manufacturer could build any design required for the particular article of manufacturing or necessitated by the floorplan of the building. The device of the present invention may also be adapted for use in clean room environments.  
           [0010]    Lastly, prior devices require extensive maintenance. The conveyor belts and multiple drives associated with conveyor operations are difficult to maintain. In contrast, the device of the present invention allows easy access to workstations.  
         SUMMARY OF THE INVENTION  
         [0011]    It is therefore a principal object of the interlocking transfer system of the present invention to provide a new, useful and uncomplicated assembly that transports fixtures or pallets to a workstation. It is also an object of the present invention to improve upon the speed and efficiency of prior conveyor devices. It is yet a further object to provide a transfer system that is capable of either manual or automated procedures. It is still another object or the present invention to eliminate the need for transfer space due to traffic control and end to end cross transfer. It is also an object of the present invention to provide an efficient way to transfer pallets around 90 degree corners. It is a further object of the present invention to provide a system that allows for pallet swapping ability and offers multiple configurations to fit floor space. It is another object of the present invention to provide a device that can be purchased for significantly less than comparable systems and that occupies less than half the space of comparable systems. It is yet another object of the present invention to provide a low-maintenance device that is suitable for use in a clean room.  
           [0012]    The device of the present invention obtains these objects. It can be configured in any number of setups depending on both production necessities and floor space. The device of the present invention consists generally of a workstation with four or more sides positioned at 90-degree angles from one another, a cam lift assembly on each of the sides and means for moving the pallets horizontally. The cam lift assembly is actuated by a reciprocating cylinder which operates to lift and lower the pallets. While the pallets are lifted, they are also advanced horizontally using either an external reciprocating cylinder, a motor, or by hand. The device of the present invention provides a combination of high efficiency and low transfer rate. The present invention eliminates the need for lift and locate devices, transfer space due to traffic control and end-to-end cross transfers. The device of the present invention also provides for interchangeable fixtures. Further, the device of the present invention may be advanced by either manual or automatic means. Lastly, the purchase price is less than comparable conveyor systems. The foregoing and other features of the device of the present invention will be further apparent from the detailed description that follows.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 is a front perspective view of one embodiment of the interlocking transfer system of the present invention.  
         [0014]    [0014]FIG. 2 is a top schematic view of several basic and alternative configurations of the interlocking transfer system.  
         [0015]    [0015]FIG. 3 is a front perspective view showing the internal workings of the system shown in FIG. 1.  
         [0016]    [0016]FIG. 4 is an enlarged elevational view of the lift beam and carriage subassemblies of the system shown in FIG. 1.  
         [0017]    [0017]FIG. 5 is a sectional view of the subassemblies shown in FIG. 3.  
         [0018]    [0018]FIG. 6 is a sectional view of the backside of the subassemblies shown in FIG. 3. 
     
    
     DETAILED DESCRIPTION  
       [0019]    Referring now to the drawings in detail, wherein like numbered numerals refer to like elements throughout, FIG. 1 shows the interlocking transfer system, generally identified  1 , constructed in accordance with the present invention. Distilled to its essence, the device of the present invention consists generally of four or more sides with each adjacent side positioned generally perpendicularly to one another, a cam lift assembly on each of the sides and a means for moving the fixtures horizontally. Each fixture on the interlocking transfer system supports one pallet. The device of the present invention advances pallets from workstation to workstation by raising the fixtures  100  off the transfer rails  500  of the interlocking transfer system  1  with the cam lift assembly, advancing them horizontally using some means for reciprocating horizontal motion, and lowering them using the cam lift assembly. Lastly, the horizontal motion returns to its home position.  
         [0020]    The device of the present invention can be constructed with a steel base plate and an extruded aluminum frame. The frame can also be welded steel if the tooling requires it. Tooling can be mounted on the interlocking transfer device  1  if required. The materials discussed are not meant to limit the invention in any way. They are merely present to provide examples of construction materials. Accordingly, it is to be understood that the device of the present invention could be constructed of nearly any kind of metal or hardened plastic.  
         [0021]    As shown in FIG. 1 a preferred embodiment of the invention is shown in its simplest configuration, a square. The configuration shown is used to provide illumination and is not meant to serve as a limitation to the device of the present invention. In fact, as depicted in FIG. 2, the device of the present invention can be configured  30 ,  40 ,  50 ,  60 ,  70 ,  80  in multiple ways to take advantage of available floorspace or to provide customized subassembly stations.  
         [0022]    In its most simple configuration, the finished product resembles a square table. Easily visible in FIG. 1 are the cover  510 , the transfer rails  500 , the rough locating pads  520  and the fixtures  100 . The cover  510  protects the assembly from the elements and prevents the possibility of operator injury from the moving parts of the undercarriage. The transfer rails  500  provide a resting place for the fixtures  100  when they are stationary at workstations. The rough locating pads  520  consist of narrow strips attached to the transfer rails  500  to provide an approximate workstation location within the interlocking transfer system  1 .  
         [0023]    In a preferred embodiment, the device of the present invention has several fixtures  100 . The fixtures  100  are used to hold pallets. (not shown) The fixtures  100  are generally square, although other shapes may be employed, and have a top side  102  and a bottom side  104 . The bottom side  104  of the fixture  100  features several machined holes, or keyholes  108 . The keyholes  108  fit onto points, or keys on the lift beam  200  and are especially important when a fixture  100  has reached the end of one side and is going around a corner of the assembly. The keys  108  provide each fixture  100  with an exact location on the lift beam  200  as the lift beam  200  elevates each of said fixtures  100 . When the fixtures  100  reach the end  12  of one side  10  of the interlocking transfer system  1 , a second lift beam  25  of the new side  20  will pick up the fixture  100  using either the same set of keys  110  or a similar set of keys positioned  90  degrees from the first set of keys  110 . In this manner, the assembly of the present invention provides that each fixture  100  remains exactly and precisely located on the interlocking transfer system  1 .  
         [0024]    Each interlock transfer assembly  1  has at least four sides. Each side  10  functions mechanically identically. However, this is not to imply that each side  10  need be identical. To the contrary, the inventor envisions that some sides could be longer or shorter than other sides, depending on production requirements of manufacturers and the space constraints of their buildings so long as each side is generally perpendicular to its adjacent side. Some basic configurations envisioned by the inventor are depicted in FIG. 2. Despite this variability, and in the interests of simplicity and clarity, the inventor has chosen to describe the mechanism of only one side  10  of any interlocking transfer system  1  constructed in accordance with the present invention. See, for example FIG. 4, FIG. 5 and FIG. 6, depict in more detail a side of the system depicted in FIG. 3.  
         [0025]    As shown in FIG. 5, the fixture  100  rides on top  202  of the lift beam  200 . In section view, the lift beam  200  has a top portion  202  and a bottom portion  204  perpendicular to each other, generally in the shape of an inverted L. The top  202  of the lift beam  200  features a pair of locating keys  206  that fit into the keyholes  108  of the fixture  100 . The lift beam  200  also features several support flanges  205  that extend outwardly from the bottom  204  of the lift beam  200  to support the top  202  of the lift beam  200 . Generally, the lift beam  200  runs the length of a side  10  of the interlocking transfer system  1  and lifts several fixtures  100  at once, advances them and then sets them down. The subassembly for lifting and advancing the fixtures will be discussed in more detail later in this detailed description.  
         [0026]    A pair of vertical bearing rails  220  are attached to the other side  208  of the lift beam  240 . These bearing rails  220  fit into the linear bearings  610 , which are attached to the lift beam support plate  600 , and allow nearly frictionless vertical motion of the lift beam  200  relative to the lift beam support plate  600 . In the preferred embodiment, the linear bearings  610  are generally T-shaped with the top of the “T” furthest away from the lift beam support plate  600 . The top of the “T” then fits within the bearing rails  220  on the back  208  of the lift beam  200 . This illustration of the shape of the bearing  610  and bearing rail  220  is for purely illustrative purposes and is not meant to be a limitation. It is to be understood that any type of bearing  610  and bearing rail  220  that allows nearly frictionless movement such as is similar to the arrangement described above would work.  
         [0027]    The vertical motion of the lift beam  200  is supplied by a cylinder and camshaft subassembly. In general, the subassembly is comprised of a cylinder  400 , a clevis  410 , a tie rod  420 , a pivot  460 , a pair of lift blocks  240  and a pair of cam levers  430 . The first end  402  of the cylinder  400  is attached to the lift beam support plate  600 . The second end  404  of the cylinder  400  is a clevis  410 . The clevis  410  is attached to the tie rod  420  near the center  426  of the tie rod. The tie rod  420  is attached to a cam lever  430  at both of its ends  422 ,  424 . The cam levers  430  are attached at their lower ends to the tie rod  420  and at their upper ends to the pivot  460 . The pivot  460  is attached at its top to the lift beam support plate  600 . The cam lever  430  is attached to a cam follower  440 . The cam follower  440  is positioned between two liftbars  240 . In this fashion, the horizontal motion caused by the cylinder  400  extending is transferred first to the tie rod  420  and then to the cam lever  430 . The cam lever  430  engages the cam follower  440 , which raises the liftbar  240 , which in turn lifts the lift beam  200 .  
         [0028]    The interlocking transfer assembly  1  of the present invention also provides for adjustable vertical motion of the fixtures. In other words, one side of the device may lift a fixture  100  two inches, while the adjacent side lifts the fixture  100  only one inch. This would allow a manufacturer to use pallets that are larger than standard without causing interference between the lift beam assemblies of adjacent sides.  
         [0029]    The movement of the cylinder  400  is contained within a pair of shocks  450 . The shocks  450  act to reduce the impact caused when the cylinder  400  cycling back and forth to lift and lower the fixtures  100  and can be of various strengths depending on the load on the fixture  100  and the speed with which the interlocking transfer device  1  is used. A shock or a group of shocks  250  may also be positioned underneath the lift beam  200  to absorb the impact of descending fixtures  100 .  
         [0030]    The movement of the cylinder  400  is regulated by a sensor (not pictured). This sensor can be electronic or mechanical. The sensor detects the amount of air entering or escaping the cylinder  400 . It then uses this information to determine and regulate the amount of stroke the cylinder  400  uses. In the preferred embodiment, this stroke information can be relayed to a central processor (not pictured) that coordinates the entire device  1  so that the cylinder  400  on each side of the assembly  1  operates in a coordinated fashion with the other cylinders.  
         [0031]    The horizontal motion of the interlocking transfer system can be supplied in one of several ways. However, the hardware that the device of the present invention employs remains generally the same. The device of the present invention employs a horizontal transfer rail  300 . This transfer rail  300  runs the length of the maximum possible stroke to be used in the device. The stroke will be discussed in more detail later in this detailed description. In one preferred embodiment, the transfer rail  300  has three distinct parts. In section view, the slide rail has a first thick end  302 , which abruptly tapers to a flat midsection  306  and a second thick end  304 . The transfer rail  300  generally functions to allow the carriage  310  to slide back and forth horizontally in a nearly frictionless fashion.  
         [0032]    The carriage  310 , by means of components to be later described, supports the lift beam support plate on the transfer rail  300 . Because the majority of the weight on the lift beam  200  is not directly over the carriage  310 , the unique shape of the transfer rail  300  allows the bearings within the carriage  310  to be placed at an angle to the vertical. This eliminates side-loading conditions, which could lead to increased friction between the carriage  310  and the transfer rail  300 , or even binding. The carriage  310  contains several bearings (not shown) that enable the carriage  310  to slide nearly without friction along the transfer rail  300 .  
         [0033]    The carriage  310  is attached to an adapter plate  320 . The adapter plate  320  provides a mechanism for centering the lift beam  200  so that it does not interfere with the motion of the other lift beams. In one embodiment, this adjustment mechanism features a spring-loaded adjustment block  330  that can be moved along a threaded rod  340  by variously loosening and tightening the hex jam nuts  350  at either end of the adjustment block  330 . Moving the adjustment block  330  moves the lift beam  200  horizontally with respect to the carriage  310 . The adjustment feature allows an operator to quickly and easily move the lift beam  200  so that it is centered. Unless the lift beam  200  is centered, it may grind into the frame of the assembly or interfere with other lift beams.  
         [0034]    As shown in FIG. 3, one embodiment of the interlocking transfer system requires only a single external cylinder  700  to operate the horizontal component of motion on all four sides of the device. This particular embodiment of the device of the present invention provides for a threaded rod and belt design to transfer the horizontal reciprocating motion provided by the external cylinder  700 . The threaded bolt  360  runs through the carriage and comes out each end of the carriage  310 . Each end of the threaded bolt  360  is attached to an adjustable clamp  380 . The adjustable clamp  380  is used to hold a belt  370 . The clamp  380  must be adjustable so that the tension on the belts  370  can be equalized throughout the interlock transfer system  1 . The belt  370  is actually a studded belt so that the adjustable clamps  380  and the carriage  310  have a positive grip on the belt  370 . The belt  370  is used to transfer the horizontal motion of the external cylinder  700  around 90° corners to each particular carriage  310  located on the interlocking transfer assembly  1 .  
         [0035]    The interlocking transfer system is truly horizontally interlocked. The device of the present invention calls for the belt  370  to transfer around corners using pulleys  390  so that one power source can handle all of the horizontal motion requirements for the system.  
         [0036]    The above embodiment featuring the belt is again meant as an illustration and not a limitation of the device of the present invention. The inventor has already envisioned the use of a chain drive, a belt drive and a steel band drive for use with the interlocking transfer system instead of the above-described timing belt.  
         [0037]    The interlocking transfer system generally employs the following cycle, when the lift beam  200  is in the up position, the external cylinder  700  extends, providing horizontal motion for the fixtures  100 . When the fixtures  100  are over their new stations, the lift beam  200  descends and places the fixtures  100  onto the transfer rails  500 . The external cylinder  700  then contracts to the original, or home position.  
         [0038]    Changing the timing of the vertical motion cylinders  400  with respect to the external cylinder  700  reverses the direction of the pallets. Thus, the device of the present invention can be operated in both a clockwise and a counterclockwise motion without any changes in tooling.  
         [0039]    In another embodiment, the device of the present invention may be manually activated. In still another embodiment, a servomotor powers the device of the present invention. A servo motor offers several unique advantages, including the ability to stop and start within each stroke of horizontal motion. To illustrate, if the required stroke is ten inches, a servomotor could stop at each inch interval if a manufacturer so desired. A standard motor could also provide the horizontal motion of the carriage.  
         [0040]    While the invention has been described in connection with what is presently considered the most practical embodiment and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.