US3082855A

US3082855A - Material handling system

Info

Publication number: US3082855A
Application number: US734385A
Authority: US
Inventors: Habicht Ernst; Meinas Georg
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-05-08
Filing date: 1958-05-08
Publication date: 1963-03-26
Anticipated expiration: 1980-03-26

Description

March 26, 1963 E. HABICHT ETAL MATERIAL'HANDLING SYSTEM F iled May 8. 1958 16 Sheets-Sheetl INVENTORS AL /a/W March 26, 1963 E. HABICHT ETAL MATERIAL HANDLING SYSTEM 16 Sheets-Sheet 2 Filed May 8. 1958 INVENTORS BY ERNST HABICHT GEORG MEINAS ATTORNEY. 4.24M s. S'h-r/ar March 26, 1963 E. HABICHT ETAL MATERIAL HANDLING SYSTEM 16 Sheets-Sheet 3 Filed May 8. 1958 Q Q N INVENTOR5 .BY.,%" M

March 26, 1963 E. HABICHT ETAL MATERIAL HANDLING SYSTEM 16 Sheets-Sheet 4 Filed May 8, 1958 lNV ENTORS BY ERNST HABICHT GEORG MEINAS ATTORNEY mu! army March 26, 1963 E. HABICHT ETAL 3,082,355

MATERIAL HANDLING SYSTEM Filed May 8, 1958 16 Sheets-Sheet 5 2.3,4 9 5, IV R Fig. 8

INVENTORS. BY ERNST HABICHT GEORG MEINAS March 26, 1963 E. HABICHT ETAL MATERIAL HANDLING SYSTEM 16 Shee ts-Sheet 6 Filed May 8, 1958 .WADNH mum m H Nfim w m A w 7m 65 @w/ #IHG m m I M A B 0mm l: m w a w m A 2 u 5 R 2 m m 6 RU f $9M 1 In I III m. I

- ATTORNEY. 7 1411-4121 S. (hiker March 26, 1963 E. HABlCHT ETAL 3,

MATERIAL HANDLING SYSTEM Filed May 8, 1958 16 Sheets-Sheet 7 I INVENTQRS.

BY ERNST HA'BlCHT GEORG MEINAS March 26, 1963 E. HABICHT ETAL 3,082,855

MATERIAL HANDLING SYSTEM Filed May 8, 1958 16 S heets-Sheet 8 4 V R g: R had/341% 0 LL T /4/ M2 M3 132 M- a- I Fig. 15

' INVENTORS. BY ERNST HABICHT GEORG MEINAS ATTORNEY. I), g 5. S'fri Qr March 26, 1963 E. HABlCHT ETAL 3,082,855

MATERIAL HANDLING SYSTEM Filed May 8, 1958 16 Sheets-Sheet 9 Fig. 16

A BY ERNST HABICHT GEORG MEINAS ATTORNEY.

fr/kg! March 26, 1963 E. HABICHT ETAL 3,082,855

MATERIAL HANDLING SYSTEM Filed May 8, 1958 16 Sheets-Sheet l0 20a r VE INVENTORSV-Y, BY ERNST HABYICHT GEORG Many/As March 26, 1963 I E. HABICHT ETAL 3,082,855

- MATERIAL HANDLING SYSTEM Filed May 8, 1958 16 Sheets-Sheet 11 9 Magoo,

INVENTORS- BY ERNST HABICHT GEORG MEiNAS ATTORNEY. 49 9.95 17b! March 26, 1963 E. HABlCHT ETAL MATERIAL HANDLING SYSTEM 16 Sheets-Sheet 12 Filed May 8, 1958 i INVENTORJ a M1 6124* 620,-? A7 e inn;-

E. HABICHT ETAL MATERIAL HANDLING SYSTEM March 26, 1963 Filed May 8, i958 16 Sheets-Sheet 13 fig. 25

INVENTORS- BY ERNST HABICHT GEORG MEINAS March 26, 1963 E. HABICHT ETAL 3,082,855

'MATERIAL HANDLING SYSTEM Filed May 8, 1958 16 Sheets-Sheet 14 INVEN I'OB BY ERNST H s gm GEORG MEINAS ATTOR NEY, m 4: Imu- March 26, 1963 E. HABICHT ETAL MATERIAL HANDLING SYSTEM 16 Sheets-Sheet 16 Filed May 8, 1958 ;i it.

3,082,855 MATEREAL HANDLING SYSTEM Ernst Hahicnt, Bielefeld, Germany (lngolstadter Land- The present invention relates to material handling systerns.

More particularly, the present invention relates to that type of material handling system wherein a conveyor distributes material to a plurality of work stations and receives material from the work stations to deliver the material to other work stations or to remove the material from the system.

Material handling systems of this type at the present time have several disadvantages. Thus, the known systems are extremely complex and they require a large amount of material to be in continuous movement, which results in a considerable waste of energy and time. Moreover, known material handling systems are subject to unavoidable bottlenecks.

One of the objects of the present invention is to provide a material handling system which is relatively simple and which at the same time is capable of efiiciently delivering material to a relatively large number of work stations as well as receiving the material from a relatively large number of work stations.

Another object of the present invention is to provide a material handling system capable of maintaining only a limited amount of material in movement at any given time so that the energy required to move the material is maintained at a minimum and so that a minimum amount of time and work is required to keep the material in movement.

A further object of the present invention is to provide a material handling system capable of automatically eliminating bottlenecks.

An additional object of the present invention is to provide a material handling system which automatically prevents material from being transported to a location which is already occupied with material.

Still another object of the present invention is to provide a material handling system of the above type which can easily be supervised in its entirety from a single station.

A still further object of the present invention is to provide a material handling system which occupies a relatively small space and at the same time is capacle of serving a relatively large number of work stations in relation to the relatively small space which is occupied by the entire system.

It is also an object of the present invention to provide a material handling system in which the material which is worked on is transported in containers or receptacles which need never be raised or moved by the operators at the several work stations. t is also an object of the present invention to provide a material handling system in which all components are capable of operating in precise synchronism with each other and in which long fluid conduits are unnecessary so that faulty timing resulting from such long fluid conduits can be avoided.

With the above objects in view the present invention includes a material handling system wherein a plurality of work stations are located along a predetermined path. In accordance with the present invention a conveyor means extend along the path along which work stations are located, and this conveyor means includes a first series of carriers for the several work stations, respectively, which move along the above path and a second the appended claims.

3 ,082,855 Patented Mar. 26, 1953 series of carriers for the several work stations, respectively, the second series of carriers being located after the first series of carriers and also moving along the above path. Thus, the conveyor means includes only two carriers for each work station, and the two carriers of each work station are separated from each other by the carriers of the other work stations so that no two carriers for a single work station are next to each other. The material handling system of the present invention also includes a receiving area located at each work station for receiving a container from a carrier which belongs to the particular work station, and at each work station there is a discharge area from which a container is delivered to a carrier of another work station, these carriers of the conveyor means being adapted to carry the containers. The conveyor means includes a plurality of carriers in addition to those which belong to the several work stations, and there is located at a part of the path of movement of the conveyor means an additional receiving station which cooperates with the additional carriers to receive therefrom excess containers which were not delivered to any of the receiving areas at the several work stations. Each of the operators at the several work stations is capable of selecting a carrier which corresponds to another work station to have the container with the work pieces which have already been operated on by a particular operator picked-up by the carrier of another station and delivered to this other station, and in the event that the two carriers which correspond to the next station are already occupied there is provided an automatic control for delivering the container to one of the additional carriers which delivers the container to the additional receiving area.

The novel features which are considered as characteristic for the invention are set forth in particular in The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which: 7

FIG. 1 is a fragmentary schematic plan view of the material handling system of the present invention showing the relationship between the carriers of the conveyor means and the several work stations;

FIG. 2 shows the system of FIG. 1 with containers located at certain parts of the system;

FIG. 3 fragmentarily illustrates on an enlarged scale part of the structure shown in FIG. 2, FIG. 3 showing how several containers cooperate with the station 4;

FIG. 4 is a schematic plan view of the entire material handling system of the present invention showing several containers having various positions with respect to the work-stations and with respect to the conveyor means;

FIG. 5 is a fragmentary partly sectional transverse elevational view taken transversely to the direction of movement of the conveyor means and showing details of the conveyor means as well as of the structure which cooperates with the conveyor means for causing a container to be delivered therefrom to a receiving area at a given work station;

FIG. 6 is a front elevational view of the conveyor means of the invention showing fragmentarily a unit of the conveyor means, FIG. 6 showing the structure as seen in the direction of arrow X4 of FIG. 3;

FIG. 7 shows the structure of FIG. 5 in a different position wherein the conveyor means has been actuated to deliver a container to a receiving area;

FIG. 8 is a fragmentary transverse elevational view of the conveyer means of the invention, FIG. 8 additionally showing part of the structure for moving a con- 3 tainer from a receiving area at each Work station to a discharge area thereof;

FIG. 9 fragmentarily illustrates the structure of FIG. 8 as seen in the direction of arrow X2 of FIG. 8;

FIG. is a plan view of the structure of FIG. 9, FIG. 10 being taken in the direction of arrow X3 of FIG. '11 is a transverse fragmentary sectional view taken in the direction of arrow X1 of FIG. 3 and showirig the details of the structure for moving a container from a receiving area to a discharge area at each work s o FIG 12 is a fragmentary elevational view of the structure as seen in the direction of arrow X2 of FIG. 8 and showing additional details of the structure for moving a container from a receiving area to a discharge area at each Work t t o FIG. 13 is a fragmentary plan view of the structure of FIGS. 11 and 12, as seen int-he directionof arrow X3 of FIG. 8, and in FIG. 13 the, platform on which the containers are located when they are not on the conveyer means is shown in a horizontal plane for the'sa-ke of clarity;

FIG. 14 is a fragmentary transverse sectional view showing the structure which is actuated by a container at a discharge area of each work station for preventing a second container from being delivered to the discharge area when there already is a container at. the discharge area;

FIG. 15 is a plan view of the structure of FIG. 14 and shows the structure as seen in the direction of arrow X3 of FIG. 8;

FIG. 16 is a fragmentary elevational view of the structure of FIGS. 14 and 15 for moving a container from a receiving area to a discharge area at each work station;

FIG. 17 is a plan view of the structure of FIGS. 14-16;

FIG. 18 is a fragmentary elevational view taken transversely with respect to the direction of movement of the conveyer means and showing the structure for moving a container from a discharge area at each work station to the conveyer means{ I FIG. 19 is a view on an enlarged scale of the structure of FIG. 18 for moving a container from a discharge area to the conveyor means; 7

FIG. 20 is a schematic illustration'of part of the wiring for a central control station which has lamps which indicate the presence or absence of contm'ners at the several work stations;

FIG. 21 fragmentarily and diagrammatically illustrates part of the wiring which controls the movement of the containers to and from the conveyer means;

FIG. 22 also is a fragmentary schematic illustration of the wiring which controls the movement of a containe from the conveyor means to a work station; I

FIG. 23 is a wiring diagram of the electrical structure which controls the operation of the components ofthe material handling system of the present invention;

FIG. 24 is a transverse elevational View taken transversely to the direction of movement of the conveyor means and showing another embodiment of a structure for moving a container from a discharge area at each work station to the conveyor means;

FIG. 25 is a fragmentary plan view of part of the conveyer means and part of awork station of the present invention, FIG. 25 showing the dimensional relationship between various components of the system of the invention;

FIG. 26 is a schematic transverse elevational view of the structure of FIG. 25, FIG. 26 also showing the dimensional relationship of the components of the structure which move a container from a discharge area to the conveyor means; a

FIG. 27 is a broken away plan view of part of the material handling system of the present invention showing the structure of FIG. 24 for moving a container from a work station to the conveyer means;

FIG. 28 is a side elevational view of the moving structure which actuates the movement of a container shown in FIG. 24;

FIG. 29 shows the structure of FIG. 28 as seen from the left'side of FIG. 28;

FIG. 30. is a sectional plan view taken along the line BB of FIG. 29 in the direction of the arrows;

FIG. 31 is a top plan of the structure of FIG. 28;

FIG. 32 is a sectional plan view of the structure of PEG. 29 taken along the line CC of FIG. 29 in the direction of the arrows; and

FIG. 33 is a sectional plan view of the structure of FIG. 29 taken along lineA-A of HG. 29 in the direction of the arrows.

The material handling system of the present invention is capable of handling all types of materials such as textiles, leather, plastics, metals, liquids, and the like. The system of the present invention includes a convcyer means which moves continuously and which does not-have any cyclical movement which is in any way related to the operations which are carried on at the several work stations. According to the present invention only a limited amount of material is maintained. in movement by the system at any given time. 7

General Description The layout of the material handling system of the present invention and the manner in which it operates is illus trated in FIGS. 14. As may be seen from FIG. 1, the material handling systentof the present invention in cludes a plurality of work stations which in the illustrated example are numbered 1-30. These Work stations start at the upper left of FIG. 1 and advance to the right up to station No. 15, and then they continue at the lower right of FIG. 1 and continue to the left up to station No. 39. These work stations are located along an endless path, and a conveyer means moves along this path to deliver the material to the Work stations and to receive material from the work stations. The-conveyer means includes an elongated endless sprocket chain or'the like 13 which is driven by a pair of sprocket wheels located at the turning points W and W shown in FIG. 1, a suitable electrical driving motor, which is not illustrated, being located beneath one of the turning points W and W and cooperating through a suitable gear transmission with one of the sprocket wheels for turning the same so as to continuously advance the endless chain B with the upper run thereof, as viewed in RIG. 1, moving to the right as indicated by the upper arrows A and with the lower run of FIG. 1 moving to the left, as viewed in FIG. 1, as indi cated by the lower arrows A. The conveyer means further includes a plurality of carriers C which are connected with the chain B for movement therewith along the endless path which is surrounded by the several work stations. In accordance with the present invention only two carriers C are provided for each work station. Thus, the carriers :1 and 1 cooperate with the work station 1, the

carriers

2 and 2 cooperate with the work station 2, etc. Thus, there are provided in the conveyer means of the present invention a first series of carriers for the several work stations, respectively, and a second series of carriers for the several work stations, this second series following the first series, so that only two carriers are provided for each work station, and these two carriers of each Work station are separated from each other by all of the carriers for the other work stations. The several carriers and the several Work stations may be provided with any suitable indicia such as the numbers shown in FIG. 1 for identifying the carriages and the work stations. Furthermore, it will be noted that while the numbers of the work stations progress from the left to the right at the upper part of FIG. 1 and from the right to the'left at the lower part of FIG. 1, the numbers of the carriers progress in the opposite direction from the right to the left at the upper part of FIG. 1 and from the left to the right at the lower part of FIG. 1.

The numbers of the carriages are visible to the operators at the several work stations as the carriages move by the work stations, and the conveyer means operates at a steady fixed predetermined speed in a continuous uninterrupted manner so that each carriage in a given time moves once through the entire endless path along which the conveyer means is located.

An elongated continuous platform which is described in greater detail below surrounds the conveyer means and is located between the latter and the several work stations. At each work ation this platform provides a receiving area H which receives containers delivered from a carriage to each work station and a discharge area I from which a container is discharged from each work station to the conveyor means. Thus, FIG. '1 shows at the work station 14 the receiving area H and the discharge area I of the work station 14-, and all of the work stations are provided with similar receiving and discharge areas. It will be noted that the total length of the receiving and discharge areas H and I at each work station equals the length of each work station along the path of movement of the conveyor means, and furthermore each pair of succeeding carriers C have a length equal to the length of the areas H and 1.

One of the important features of the present invention is the limitation of the amount of material which is in movement at any given time. P16. 2 illustrates the limitation of the am not of material for the work station 4'. Thus, as may be seen from FIG. 2, there is a container D and a container E at the receiving and discharge areas of the work station 4, and at the same time there is a container F on the carrier 4 of the conveyer means and another container G on the carrier 4 of the conveyer means. Therefore, at this time both of the

carriers

4 and 4 are occupied by containers for the work station 4 and simultaneously both the receiving and discharge areas of the work station 4 are occupied. Therefore, the containers F and G cannot be delivered to the receiving area. of the work station 4, and with the structure as shown in FIG. 2 the system is provided with the maximum amount of material which it can handle for the work station 4. Thus, assuming that there are a given number of work pieces or a given amount of material in one of the containers DG, then the maximum amount of material which can be handled by the system of the invention for any given work station is four times the amount of material or number of work pieces in one of the containers which holds the material or work pieces which are operated upon at a particular work station.

The manner in which the material moves is shown for the work station 4 on an enlarged scaie in FIG. 3, the container P which is on the carrier 4 being omitted from FIG. 3. Thus, as can be seen from FIG. 3 the containers which are delivered to the several stations such as the stations 3 and 5 of PEG. 3 are moved from the receiving areas H at these stations to the discharge areas i, and this movement takes place at each work station as soon as the discharge area of each station is unoccupied, as will be apparent from the description below. The container at each discharge station 1 of the several work stations moves as shown by the arrows in FIG. 3 toward the conveyer means to be discharged from the work station to the conveyer means in a manner described in greater detail below.

The operators at the several work stations do not remove the containers from the system. Each operator only takes material or a work piece from a container, performs the particular operation on the material or work piece, and then returns the material or work piece to a container. Although the operator may work on the material or work pieces while a container which holds these work pieces is at the position H or the position I, in alan electrical construction and includes a plurality of switches capable of being selectively actuated by each operator. Thus, when the operator at the work station 4 of FIG. 2 completes the operations on the materialor work pieces in the container E, he will close a selected switch of his selector device VE, this switch bearing a number which is the same as the number of thework station to whichthe work pieces or material are to be delivered from the work station 4'. When the operator at the work station t closes this particular switch which corresponds to one of the other Work stations, then the container E will in a manner described below be discharged from the work station 4 to one of the two carriages C for the next Work station which receives the material from the work station 4 and then in a manner described below the container D will automatically be shifted over to the discharge area I previously occupied by the container E, and one of the containers F and G will be automatically delivered to the receiving area of the work station The continuous platform surrounding the conveyor means and providing the receiving and discharge areas for the several work stations is inclined downwardly from the conveyor means and at its lower limit the platform carries a mountingplate on which the selector device VB for each work station is mounted.

The manner in which the entire system operates is illustrated in FIG. 4. As may be seen from FIG. 4 a pair of containers arelocated at the receiving and discharge areas, respectively, of the work station 6. Assuming that the workpieces or material operated on at the work station 6 are then to be delivered to the work stations 17 and that the operator at the work station 6 has closed the switch 17 of the selector device VE, then when the carrier 17 is located at the discharge area of work station 6, as shown in FIG. 4, the container at this discharge area will automatically move onto the carrier1'7 to be carried thereby to the work station 17 and to be automatically delivered from the conveyor to the receiving area of the work station 17. In the event that the carrier 17 is already occupied, then the movement of the container at the discharge area of work station 6 to the carrier 17 is automatically prevented in a manner described below, and when the carriage 17 becomes located at the discharge area of the work station 6 the container at the latter discharge area will be automatically moved onto the carrier 17 to be conveyed by the latter to the work station 17. Thus, the selector devices VE eliminate a considerable amount of waiting time on the part of the operators. The operators need only press the switch corresponding to the next work station, and the work is automatically carried to this next work station. While waiting for work to be carried away from the discharge area at any work station the operator may continue to work on workpieces in a container located at the receiving area of theparticular work station. As soon as a container is delivered to the conveyer from the discharge area of a work station, the container at the receiving area of the work station moves automatically to the discharge are-a thereof. Thus, referring to FIG. 4, the container at the discharge area of work station 6 will move onto the carrier 17 and immediately thereafter the container at the receiving area of the work station 6 will move to the discharge area of the work station 6, so that if the

carriers

6 or 6 are occupied by containers for the work station 6, one of these 7 containers will be automatically delivered to the receiving. area of the work station' which is now vacant. The illustrated example of FIG. 4 shows that the carrier is empty while the carrier 6 is occupied, and the container on this carrier 6 will be automatically delivered to the receiving area ofthe work station 6 as soon as the container at this receiving area of the work stations in the position of the parts shown in FIG. 4 is shifted to the. right to the discharge area of the work station 6,

Assuming, for example, that in the above example both of the carriages 17 and 17 are occupied so that the container at the discharge area of the work station 6 cannot move onto the carriers 17 or 17 the structure of the invention operates to eliminate a bottleneck which might otherwise occur. The

stations

1 and 3% are not work stations in the sense that operations are performed on the material or the workpieces at the stations 1 and 30; These stations 1 and 3t} are located at the left end of the system, as viewed in FIG. 4, and serve to provide this system with fresh material or workpieces to be processed at the several work stations as well as to eliminate fi'om the system excess containers which cannot be delivered to the next work station for the time bein When the operator at the work station 6 closes the switch 17 of his selector device VB and assuming that the carriages or carriers 17 and 17 are occupied, then the. electrical system in a manner described below automatically causes the container at the discharge area of the work station 6 to be received by one of the carriers 30 or 30 to be delivered to the collection area I which is the receiving area for the station 3d. The

carriers

11 and 1 serve the same purpose so that for the left end of the system there are more than two carriers provided for removing excess containers from the system, these excess containers being temporarily prevented from moving to the next work station, and also the additional areas at the end of the system serve to receive fresh material which moves onto the carriers for a particular work station where the operations are started. Therefore, with the case where the carriers 17 and 17 are occupied so that the container at the discharge area of work station cannot move to one of these carriers, either the carriers 3th or 355 or the carriers 1 or '1 will automatically receive the container at the discharge area of the work station 6 and deliver this excess container to the area I, and this way a bottleneck is avoided.

The continuous platform which surrounds the conveyer mean and is located between the latter and the several work stations is uninterrupted except for the elongated slotsY which form part of the structure for shifting a container from a receiving area at each work station to the discharge area thereof and the slots Z which form part of the structure for moving the containers from the discharge areas at the several work stations to the conveyor means, as is described in greater detail below.

PEG. 4 shows several difierent operations taking place in the material handling system of the present invention. At the work station in FIG. 4 a container with ma terial or. workpieces. therein is being delivered from the carrier 1% of the conveyor means to the receiving area H of the work station .10, and FIG. 4 shows atthe discharge area 1 of the work station 10 a container which has just been moved to this discharge area I from the receiving area H. Furthermore, FIG. 4 shows another container on the carrier 16 of the conveyer means which moves with the conveyer means and remains in reserve for the work station 10 to be delivered automatically to the receiving area'thereof as soon as this receiving area is unoccupied and the carrier 16;; reaches the unoccupied receiving area. When the operator at work station it) completes his work on the workpieces or material in the container at the discharge area I of the work station 19 the operator will select at the selector device VE the next work station to receive the container from the work 8. station 10 and the carrier of the next work station will automatically receive the container from the work station 10 and deliver to the next work station. Thus, whichever of the two carriers belonging to the next work station are unoccupied and reach the work station 10 after the operator at the work station iii actuates the selector device VE will receive the container from the discharge area I of the work station It At the work station 2-5 in FIG. 4 a container is being moved from the receiving area H to the discharge area I, and it will he noted that the carriers 26 and 26 are both occupied with containers for the work station 26. Thus, inasmuch as the carrier 25 will be the first to reach the receiving area H of the work station 26 after this receiving area H has become unoccupied, it will be the container from the carrier 26 which will be delivered to the receiving area H of the work station 26, and container on the carrier 26 will remain in reserve for the work station 26. In the illustrated example, after the operations has been performed upon the workpieces or material at the work station 26 the containers with the workpieces or material are to be delivered to the work station 6, and it will be noted that a container which was previously at the discharge area I of the work station as has just been moved onto the carrier 6 and is on its way to the work station 6. Assuming that the workpieces or material are to be delivered to the work station 17 after being worked upon at the work station 6 and that before the carrier 6 reaches the work station 6 the container at the discharge area thereof has been moved onto the carrier 1% and the container at the receiving area H thereof has been shifted to the discharge area I thereof, then when the carrier 6 reaches the receiving rea H of the work station 6, the container-on the carrier 6 will be automatically moved from the conveyor means to the receiving area H of the work station 6. It will be noted that the carrier 6 is empty, a container having just been delivered from this carrier 6 to the receiving area H of the work station 6. The operator at the work station 26 selects the work station 6 on his selector device VB, and if by the time carrier 6 reaches the work station 26 the operator at the latter work station has completed the operations on the material or workpieces in the container at the discharge area I ofthe work station 26 and has again selected the work station 6 on his selector device, then this container will be moved from the discharge area I of the station 26 onto the empty carrier 6 to he delivered therefrom to the receiving area of the work station 6 as soon as this receiving area becomes unoccupied.

At the work station 18 in the example illustrated in FIG. 4 there are containers at the receiving and discharge areas, respectively, and moreover it will be noted that the carrier 18 has just passed the work station 18 and is occupied by a container which could not be delivered to the work station 18 because'the receiving area thereof is occupied. Moreover, there is another container on the carrier 18;, so that in the illustrated example both of the carriers for the Work station 18 are occupied and both the receiving and the discharge areas of the work station 18 are occupied. Therefore, under these conditions work cannot be moved from any other work station to the work station 13, and the system carries the maximum amount of material which it can carry for the work station 18. The carriers 18 and 18 will be occupied by the containers thereon until the receiving area at the work station 18 becomes unoccupied. Assuming that the work station 18 receives the workpieces or material from the Work station 21 and that the operator at the work station 21 has completed his operation on the workpieces or material which are then to be moved to the work station 18, it'is evident that under these circumstances the container will not be picked-up from the discharge area of the work station 21 by either of the carriages 18 or 18

Claims

1. A MATERIAL HANDLING SYSTEM COMPRISING, IN COMBINATION, A PLURALITY OF WORK STATIONS LOCATED ALONG A PREDETERMINED PATH; CONVEYER MEANS EXTENDING ALONG SAID PATH AND INCLUDING A PLURALITY OF CARRIERS WHICH MOVE ALONG SAID PATH WHICH ARE ADAPTED TO CARRY CONTAINERS, RESPECTIVELY, WHICH HOLD MATERIAL TO BE WORKED ON AT SAID STATIONS, SAID CONVEYER MEANS INCLUDING FOR EACH WORK STATION AT LEAST TWO CARRIERS SEPARATED FROM EACH OTHER BY CARRIERS FOR OTHER WORK STATIONS SO THAT THE CARRIERS FOR ANY ONE STATION ARE NOT LOCATED NEXT TO EACH OTHER AND SAID CONVEYOR MEANS INCLUDING AT LEAST ONE ADDITIONAL CARRIER; A RECEIVING AREA LOCATED AT EACH WORK STATION FOR RECEIVING A CONTAINER FROM ONE OF THE CARRIERS AND AT EACH WORK STATION A DISCHARGE AREA FROM WHICH A CONTAINER IS DELIVERED TO A CARRIER OF SAID CONVEYER MEANS; AN ADDITIONAL RECEIVING AREA LOCATED AT A PART OF SAID PATH FOR RECEIVING FROM SAID CONVEYER MEANS EXCESS CONTAINERS WHEN ALL OF SAID RECEIVING AREAS AT SAID WORK STATIONS ARE OCCUPIED; AND MEANS COOPERATING WITH SAID DISCHARGE AREAS AND SAID CONVEYER MEANS FOR MOVING FROM THE DISCHARGE AREA OF ONE WORK STATION A CONTAINER TO A CARRIER FOR ANOTHER WORK STATION WHICH IS TO FURTHER OPERATE ON THE MATERIAL WORKED ON SAID ONE WORK STATION, WHEN THE CARRIERS OF SAID OTHER WORK STATIONS ARE UNOCCUPIED, FOR MOVING THE CONTAINER FROM SAID ONE DISCHARGE AREA TO SAID ADDITIONAL CARRIER WHEN THE CARRIERS FOR THE NEXT WORK STATIONS ARE OCCUPIED, AND FOR SUBSEQUENTLY DISCHARGING THE CONTAINER MOVED ONTO SAID ADDITIONAL CARRIER ONTO SAID ADDITIONAL RECEIVING AREA.