Circle-crane material handling system

For the movement of work-in-process materials on a storage or manufacturing floor, a grid of computer-controlled, unmanned jib cranes is established. The cranes' operational areas overlap. A crane can place an individual part or a magazine of parts on an elevated, revolving pedestal which then automatically rotates 180 degrees so that the next crane in line can pick up these materials and move them into its own area. The hand of the crane is moved so that it can place its load directly into the position in the machine tool where it undergoes its next process. The arm of the jib crane is fully retractable and computer-controlled, using a laser integrated into the computer's system to aid in detecting the crane's hand location at each delivery position that the crane visits. The jib cranes can lift parts up to a level that places them near the ceiling of the manufacturing floor area. The crane arm then begins to swing and extend (or retract, as necessary) to transport the part or parts to the next operational position required in the manufacturing or storage process.

FIELD OF THE INVENTION 
The present invention pertains to a manufacturing material handling system 
and, more particularly, to overhead cranes for use in moving material in a 
manufacturing area. 
BACKGROUND OF THE INVENTION 
Moving work-in-process materials inside a manufacturing area has commonly 
been with wheeled vehicles, conveyance devices (such as overhead cranes 
controlled in real time by a human operator) and powered or gravity-feed 
conveying systems (utilizing belts, rollers, etc.). With wheeled vehicles, 
much floor space has to be given up to open areas in order to permit the 
vehicles room in which to maneuver. There have also been several control 
problems inherent to wheeled vehicles, creating traffic jams and lapses in 
proper computer control, all of which results in severe inefficiencies. In 
the case of overhead crane systems, few of them can run without the crane 
operator's constant attention; indeed, a second person must usually act to 
hook the crane to the load, guide the crane operator's actions with hand 
signals and, finally, unhook the load at its destination. Gravity and 
belt- or roller-powered conveyors also require much floor space for their 
installation. In addition, the finished conveyor system is usually quite 
product-specific, exhibiting little tolerance for new products to be 
integrated onto the manufacturing floor. 
For transporting items substantially horizontally, conveyor belts and other 
mechanisms typically require, for support, structure on both ends of the 
conveying means. Unfortunately, the support scheme often requires 
additional floor space and/or complexity of apparatus. Moreover, due to 
the nature of such supported conveying means, the overall length is 
generally fixed. The foregoing constraints limit the flexibility of such 
conveying systems. 
While the use of chains provides flexibility, there has been a long sought 
need to develop a chain that need not be supported on both ends. A 
flexible chain and rigid bar combination was disclosed in U.S. Pat. No. 
4,885,907 (issued to Sofia Pappanikolaou). This so-called chainbar 
requires separate locking mechanisms and a plurality of moving parts, 
which are susceptible to failure under load. 
U.S. Pat. No. 1,004,575 (issued to J. M. Jones) also addresses the support 
problem by providing hook prominences. Unfortunately, such prominences 
tend to catch on fabric and other extraneous objects. Moreover, no 
provision is made to accommodate the drive sprocket teeth which are 
normally expected to drive the chain when in use by engaging slots in the 
chain placed in line at regular intervals. 
U.S. Pat. No. 553,650 (issued to P. S. Kingsland) discloses a lock chain 
which is rigid only when first laid straight and then compressed 
end-to-end. Such a procedure is not conducive to modern material handling 
operations. 
It would be advantageous to eliminate the use of wheeled vehicles for 
moving work-in-process, saving floor space in a manufacturing area. 
It would also be advantageous to replace the overhead crane operators with 
full-time computer control, removing the potential for human error and 
reducing the number of people needed to operate in a given manufacturing 
floor area. 
It would be further advantageous to reduce the transportation time of 
parts, minimizing the amount of work- in-process inventory needed in a 
manufacturing area. 
It would be yet advantageous to keep all movement of work-in-process (WIP) 
off the floor level and place it overhead. This would minimize the danger 
of accident by eliminating the mixing of WIP transportation with human 
activities at floor level, effectively eliminating floor conveyor systems 
in manufacturing plants which make individual pieces of a product. This 
thereby saves much floor space and provides a system that can be much more 
receptive to the introduction of new products on the manufacturing floor. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, there is provided a material 
handling system for moving and placing items within a manufacturing area 
or material distribution center. A number of isolated cranes are rotatably 
mounted on respective columns. Each of the cranes has a maneuverable, 
retractable arm; along the length thereof is a mechanism for picking a 
load and moving it vertically. The elevated crane then rotates to move the 
load horizontally. A lazy-susan type of turntable is provided so that 
elevated items placed on it by one crane can be rotated horizontally to 
another position, where yet another crane can pick the load from the 
lazy-susan and continue the load on its traverse of the floor area. Other 
mechanisms for moving items horizontally from one point to another can 
also be used. Finally, a computer controller is connected to each of the 
cranes. Thus, an item placed by one of the cranes can be moved from a 
first position to a second position in preparation for being picked up by 
another crane for further handling. 
It is an object of the present invention to produce a completely automatic, 
computer-controlled WIP material handling system without the need for 
human intervention. Said material handling system has the ability to 
remove a manufactured part from a machine tool where it has just completed 
one processing step and place it into the next machine tool for the next 
manufacturing process step. 
It is a further object of the invention to provide a means of eliminating 
WIP from the conventional storage site on the manufacturing floor, moving 
any storage site needed into currently unused areas of space immediately 
below the plant's ceiling. 
It is a more detailed object of the present invention to reduce the amount 
of human effort needed to manufacture a product by making the material 
handling activities involved in that manufacture completely automatic. 
It is still a further object of the invention to provide a system that is 
versatile enough to readily adopt new products into its glossary of 
control programs and integrate that controlled movement with that of all 
other existing products made on that manufacturing floor. 
It is yet a further object of the invention to provide a conveying 
mechanism, such as a chain, which is self-supporting and locking in all 
but one direction, so that it may be wound when not in use.

DESCRIPTION OF PREFERRED EMBODIMENTS 
Shown in FIG. 1 is a control computer 19, such as an IBM.RTM. personal 
computer or other suitable processor, disposed at a remote location. 
Control computer 19 is adapted to control (via lines 19a) each of eight 
circle cranes 20 placed in a four-by-two matrix. The cranes 20 are 
disposed relative to one another so that they can span the entire 
manufacturing floor 18 as shown, servicing pieces of manufacturing 
equipment 22 in all of their equipment positions on that manufacturing 
floor 18. Work-in-process parts, not shown, are moved from one piece of 
manufacturing equipment 22 to another 22 by use of these circle cranes 20. 
If one piece of manufacturing equipment 22 is out of reach of one crane 
20, then that crane 20 will deposit the part or magazine of in-process 
parts onto the revolving pedestal 23 positioned on the most direct route 
to the next operational site of processing. After the deposit of the part 
onto the revolving pedestal 23, the crane 20 is free to obtain information 
on its next move from control computer 19. 
The same remote system control computer 19 will schedule the adjacent, 
neighboring circle crane 20 to swing to pick up the part left on top of 
the revolving lazy-susan pedestal 23 by the previous circle crane 20. The 
revolving lazy-susan pedestal 23 revolves 180 degrees, enabling the 
receiving crane 20 to pick up the part or parts magazine in the same 
orientation in which the previous crane 20 had held it. If temporary 
storage is necessary for the in-process parts, the circle crane 20 places 
them into the revolving lazy-susan shelves 21. An aisleway 24, shown 
bordered by dotted lines, defines the reduced space necessary for aisle 
traffic when all of the parts are moved overhead. 
The circle cranes 20 may be fitted with robotic hands and wrists 29 (FIG. 
2), so that they can place a part directly into the grip of the 
manufacturing equipment without the help of an operator, or they can be 
programmed with a simple gripping device 29 to deliver the part or parts 
to a lay-down space, where an operator will later come to retrieve the 
part for processing. 
Now referring to FIG. 2, the plan view of the circle crane 20 shows 
stepping motors 26 which are computer-controlled and used to reel cables 
28 in and out so as to flex the crane arm 33 into proper position. This 
flexing is accomplished when one or the other of these two cables 28 is 
tightened or loosened by the action of rotating cable drums 25, to which 
these cables 28 are attached. This rotating drum 25 is computer-controlled 
and is in response to feedback from laser-beam targets 31 and 32 reacting 
to a laser beam 48 (FIG. 5) projected by laser 27. 
As the crane arm 33 is moved in three-dimensional space, the crane hand 29 
is positioned so that a part, a magazine of parts, a container of liquids 
or a container of finely divided solids, etc., which is being transported 
can be placed accurately enough to feed said material into the gripping 
jaws or chuck jaws of a machine tool. This action is accomplished when the 
computer 19 instructs the crane 20 to be swung by its stepping motors 26, 
which drive it so that it is on the proper radian to be the exact one for 
the desired delivery location. The arm 33 is then extended or retracted 
along that radian by other stepping motors 26 under computer control, 
until it has reached the exact distance for the delivery of the materials. 
The computer 19 then reads the signals it receives from the laser targets 
31 and 32 and determines how much adjustment is needed for the final 
positioning of the arm load for proper delivery. The cables 28 are then 
pulled, flexing the hand 29 at the end of the arm 33 until the targets 31 
and 32 report that the laser beam 48 was projected through the center hole 
in target 32, thus proving that the hand end 29 of the crane 20 is now in 
perfect position to deliver or retrieve a load. 
Depending upon where the laser beam 48 first hits the target 31 or 32, the 
computer 19 can adjust the hand end 29 of the crane arm 33 up or down or 
left or right (or any combination thereof) in order to seek and find the 
proper alignment stored in computer memory for that delivery site. Any 
amount of distance that is off-center is detected by the light receptor 
cells 46 (FIG. 6) in target 32. Adjustments are made as described until 
the laser beam 48 projects through the center hole 47 in target 32, 
striking the photocell on target 31 and thereby signalling the computer 19 
to stop the cable tensioning adjustments, as proper positioning has been 
achieved. Target 31 then reads the length of the distance that the arm 33 
is extended by using the laser beam's capabilities, thereby achieving 
highly accurate distance measurements. Any error in the extension of the 
arm 33 is then corrected by an adjustment, using the stepping motor 26 and 
associated worm-drive mechanism, not shown, built into the hand receptacle 
30 for that purpose. 
Now referring to FIG. 4, the mechanical strength of the crane arm 33 (FIG. 
3) is due to the one-way chain 83 which unreels from reel 35 and is guided 
by ramp 34. FIG. 4 shows how the pivot links 42 and the main links 43 of 
chain 83 form a rigid, linear structure in one direction, yet allow the 
chain 83 to bend to any extent and roll into a coil onto its take-up reel 
35 in the opposite direction. This rigidity provides for a crane's 
required load-bearing strength, in order to support its load in the 
desired fashion. Turning the reel 35 to force the attached chain 83 out 
onto chain guide ramp 34 forces the chain 83 to extend out as far as the 
turning of the reel 35 pushes it. Once properly extended, the chain 83 may 
be restrained by the sides of the guide ramp 34 to firmly hold it in that 
desired position. 
Now referring again to FIG. 3, the side view of the crane 20 displays the 
hand receptacle 30 which contains such stepping motors, gears, worm drives 
and pneumatics as provide for all necessary motions of the hand 29 at the 
end of the crane's arm 33. All necessary electric power hydraulics, 
pneumatics and control signals needed to operate the hand 29 are carried 
through cables 28. 
Hand receptacle 30 also supports the laser targets 31 and 32. Stepping 
motor 40 drives ring gear 36 to rotate the crane assembly to swing to any 
of its computer-addressed radians through 360 degrees. A steel support 
pipe 39 is anchored to a block of concrete foundation, not shown, placed 
into the shop floor 18; this acts as an inertial block in keeping the 
entire crane assembly upright. Hydraulic cylinder 38 is 
computer-controlled in order to tilt the crane 20 on pivot pin 37, so that 
it can reach loads and delivery points close to its base. 
The view of the chain's link configurations in FIG. 4 displays the abutment 
surfaces 45 cast into both ends of the right main link 43 and the left 
main link 43. These surfaces 45 are held in place by pivot links 41 and 
42, which are, in turn, anchored in place by pivot pins in holes such as 
hole 44. This assemblage causes the main chain links 43 to butt up against 
one another, so they can go no farther, pivoting into a straight, rigid 
structure when forced by the weight of a load, not shown, to move against 
a neighboring link's abutment surfaces 45. When pivoted away from these 
abutment surfaces 45, the chain 83 bends easily in the opposite direction 
to conform to any radius demanded of it. 
Now referring to FIGS. 5 and 6, illustrated is the laser target's detailed 
matrix of photocells 46 which are mounted on the hand receptacle 30, 
allowing the computer 19 to detect the existence of any misalignment of 
the crane's hand 29 from a nominal position in three-dimensional space, 
which is stored in the computer's memory. Laser beam 48, as generated by 
laser 27, is shown projecting through the center hole 47 in target 32 to 
strike the "on target and distance measuring" photocell or mirror, not 
shown, housed in target element 31, thus communicating to the computer 19 
that proper crane hand alignment has been achieved. Should there be any 
misalignment, so that the hand end 29 of the crane arm 33 is skewed from 
the projection of the laser beam 48 along the center line of the crane arm 
33, the computer 19 will cause the cables 28 to pull the hand end 29 of 
the crane arm 33 into perfect alignment with the laser beam 48. 
The computer 19 then utilizes the laser 27 to determine the distance to the 
hand 29 from the center line of the crane support 39 (FIG. 3); if that 
information matches that which is stored in the computer 19, then the 
crane hand 29 can make its final movement to insert the part or deliver 
the load into the open grip of whatever receptacle awaits. The computer's 
stored information for each final delivery or pick-up movement of the 
crane's hand 29 may be different for each delivery position and product. 
The computer 19 will track, with the aid of its memory, all jobs on the 
manufacturing floor and know what type of part it is expected to pick up 
or deliver at each piece of equipment. If desired for additional control 
of the identity of parts, a self-adhesive tag with bar-code information 
(identifying the part or container of parts) can be adhered. This will 
also enable another laser beam, not shown, to read and thereby confirm the 
identity of the part type it is currently handling. An ink-jet printer, 
not shown, can be incorporated into the design of the crane's hand 29 and 
used to mark current information onto the adhesive tag each time that the 
crane 20 handles a part. That part's progress through the manufacturing 
system can thereby be identified by computer reading, using a laser to 
scan the updated bar-code on each part handled as it is encountered. 
Now referring to FIG. 7, a view of a second, more rugged chain-link 
configuration displays abutment surfaces 65 and 68, which are cast and 
machined flat into both ends of the right main link 64 and the left main 
link 62. These surfaces 65 and 68, held in place by the pivot pins 61 to 
the pivot links 60 and 63, cause the main chain links 62 and 64 to butt up 
against each other's abutment surfaces 65 and 68, as well as against the 
pivot links'abutment surfaces machined on the underside of the center 
connecting member 69 of pivot links 60 and 63. These blocking abutment 
surfaces 65, 68 and 69 in concert stop the links 60, 62, 63 and 64 in the 
chain, so that they can go no farther; they all pivot, therefore, into a 
straight, rigid structure when forced by the weight of a load to move 
against their adjacent, neighboring link's abutment surfaces. When pivoted 
in the opposite direction of these abutment surfaces, the chain 83 bends 
easily in the opposite direction to conform to any radius demanded of it. 
Additional abutment surfaces for extra strength are shown being formed by 
the underside surfaces of the metal forming the midsection 69 of pivot 
links 60 and 63 and by the ears cast and machined flat on their bottom 
surfaces, located at the midsection of the main links 62 and 64. Therefore 
abutment surfaces 68 mate with surfaces 69, surfaces 65 with one another, 
surfaces 70 with one another, and surfaces 67 with surfaces 62. To 
complete the design of the chain 83, sprocket holes 66 are cast and 
machined into the center of each main link 62 in the chain 83. This allows 
a drive sprocket, not shown, to manipulate the chain assembly onto and off 
its holding reel 35 (FIG. 3) and to extend and retract the arm 33. 
Now referring to FIG. 8, the rotating lazy-susan pedestal 23 (as depicted 
in FIG. 1) is shown. Its computer-controlled stepping motor 49 is shown 
engaging ring gear 50, which acts through a large bearing allowing the 
parts platform 51 to be rotated through all 360 degrees of possible 
movement. The entire assembly is supported off the shop floor 18 to a 
height comparable to that of the height of the crane's head assembly 
(shown in FIGS. 2 and 3) by steel pipe 39, which, in turn, is anchored to 
concrete foundation block 53. 
Now referring to FIG. 9, an almost identical structure 21 to the rotating 
lazy-susan pedestal 23 (FIG. 8) is shown. This rotating lazy-susan shelf 
21 is positioned by computer-controlled stepping motor 54, which turns the 
upper part of the structure 21 through a pivot-bearing supported by steel 
pipe 56. These two similar structures 21 and 23 allow the crane 20 to 
release loads onto their respective platforms 55 and 51 for later 
retrieval by the same or a neighboring crane 20. The lazy-susan shelf 21 
is a parts accumulator, using shelves 55 which provide temporary storage 
for work in process. The rotating lazy-susan pedestal 23, on the other 
hand, receives a load only from one crane 20, rotates it 180 degrees and 
presents it to the next crane 20 for further transportation, thus acting 
only as a way-station for a single crane's load in the circle-crane parts 
transportation network system. 
In some configurations of this system, it could be necessary to mount the 
cranes 20, lazy-susan shelf 21 and revolving lazy-susan pedestal 23 on 
floor tracks, not shown, or other mechanical means that would permit their 
movement across space, rather than having them cemented in a fixed 
position as hereinabove described. 
It is also evident that this system of material handling could be installed 
in many more applications and situations than a manufacturing floor 
scenario; however, the manufacturing floor scenario is the one chosen to 
explain this invention. 
Other designs for the hardware devices in this system (such as the one-way 
chain retracting crane arm, laser targets, cable drums, stepping motors 
and other integral components of this system) are obvious, once the 
overall concept taught by this invention is understood; however, the 
inventor has chosen the designs presented herein to explain the circle 
crane concept of material handling and to represent one possible working 
configuration of the system. 
Since other modifications and changes varied to fit particular operating 
requirements and environments will be apparent to those skilled in the 
art, the invention is not considered limited to the example chosen for 
purposes of disclosure, and covers all changes and modifications which do 
not constitute departures from the true spirit and scope of this 
invention. 
Having thus described the invention, what is desired to be protected by 
Letters Patent is presented in the subsequently appended claims.