Title of Invention

"AN AUTOMATIC DEVICE FOR STORAGE AND RETRIEVAL OF THE MATERIAL"

Abstract

An automatic device for storage and retrieval of the material for use in a highrise storage rack/structure comprising a computer based control means, a stacker crane with programmable logic control (PLC) means to operate a single column stacker crane, an interface for inter connecting said PLC and computer control means, warning means comprising a Bar Code Scanner for reading the bar code fixed on the bin disposed in said storage racks is directly interfaced with said computer means for reading and verifying the bins.

Full Text

This invention relates to an automatic device for storage and retrieval of the material for use in a highrise, storage rack/structure. Until a few years back storing of materials used to be stacked either on the floor or in low height racks, and high rise fork lifts used in handling the materials in such racks. Due to the limitations of manually operated systems, the height of the racks were restricted, thus limiting the storage volume in a given floor space involving high expenditure. Operation of forklifts beyond a height of 5.5 meters is net practical as it involves stress on the operator in positioning and aligning at every cycle of operation, and is critical from the safety point of view. Thus high desity, high rise storage was not feasible. The manually operated fork lift also need a person to be continuously exposed in a less ilium inated, polluted and noisy environment. The safety in the operation of manually operated fork lifts left much scope for improvement. Over and above, every transaction in a manually operated stores need updation of the records, which is laborious, erroneous and time consuming. Chances of misplacement of items, pilferage and damage due to manual handling were prevalent. Non availability of correct and upto date records, misplacement and human error in operations add upto poor efficienty of operation and higher cost. In the last few years,the stores have been modernised by the use of high rise racks going upto 12 Meters in height and doing the handling operations by a manually operated high rise stack er crane. This has helped the industries in storing more materials on the same floor area by effective utilisation of vertical space. However, other problems associated with a manually operated system remained the same. With the introduction of high rise stacker cranes safety needs of the human operator became more critical. Manual record keeping becomes a bottleneck in high frequency operation. An object of the present invention is to propose an improved construction of an automated storage and retrieval system wherein a large quantity of variety of material can be easily stored and retrieved. Another object of the present invention is to propose an automated storage and retrieval system having inventory management and cont rol. 4 Yet another object of the present i nvent ion is to propose an automated storage and retrieval system which provides a reliable and immediate delivery. Still another object of the present invention is to propose an automated storage and retrieval system wherein there is a better floor space utilization. Further object of the present invention is to propose an automated storage and retrieval system v/herein there is design flexibility to accommodate wide range of loads. Still further object of the present invention is to propose an automated storage and retrieval system, which has the ability to operate in adverse conditions Yet a further object of the present invention is to propose an automated storage and retrieval system wherein there is an accurate inventory and load location. Further objects and advantages of this invention will be more apparent from the ensuing description. At the outset of the description which follows, it is to be understood that the ensuing description only illustrates a particular form of this invention However, such a particular form is only an exemplary embodiment, and without intending to imply any limitation on the scope of this invention. Accordingly, the description is to be understood as an exemplary embodiment and teaching of the invention and not intended to be taken restrictively According to this invention there is provided an automatic device for storage and retrieval of the material for use in a highrise storage rack/structure comprising a computer based control means, a slacker crane with programmable control logic means to operate a single column stacker crane, an interface for inter connecting said PLC and computer control means, warning means comprising a Bar Code Scanner for reading the bar code fixed on the bin disposed in said storage racks is directly interfaced with said computer means for reading and verifying the bins The nature of the present invention, its objectives and advantages will be farther apparent from the following disclosure made with reference to the accompanying figures wherein Fig. 1 shows a schematic of a high - rise rack (1) and stacker crane.(2); Fig. 2 shows the detail of the stacker crane. Such as motors (8) for movement/ load (7)/ carriage (3) mast (6)/ top guiderail (5) and Bottom guiderail (9). Fig. 3 shows different views of a rack in an AS/RS Fig. 4 shows elements involved in a retrieval operation with PC ( 11) and scanner (10). Fig. 5 - shows elements involved in a storing operation PLC ( 12),control switch (13). Automatated storage and retrieval systems (AS/RS) use the concepts of high rise' high density storage (1) of items with a computer (11) controlled stacker crane (2) handling the items. The computer (11) is also capable of real time inventory management. The material is stored in standard size Bins (14),crates or Pallets/ which are stacked into the high rise racks (1)/with multiple levels. The length of the racks (1) can be as high as 100 - 150 Meters and the height can be anywhere in the range of 8 to 15 Meters depending upon the availability of space/ the types of materials to be handled and the number of Bins etc. to be stored. AS/RS have aisles that divide the storage racks. In each aisle is a stacker crane (2) which picks up the load from the pick up station and stores it at a computer assigned location / and delivers any Bin (14) at the delivery station under the commands of the system controller. The computer (11) keeps track of the materials being handled and can be programmed to give a warning for stock replenishment when the quantity of any item falls below a predefined level. Due to computerisation of the crane operation and on-line real time handling of information it is possible to have a better inventory management system. The system offers preparati on of stock reports, queries regarding availability of any item, prior warning for stock replenishment etc. By simple interat ion at the system controller all necessary information can be obtained very quickly. As the crane (2) is controlled from the system controller (11,4) directly without any human intervention, it is ensured to deliver; the right item at the delivery counter without any delay. In cases of non - availability of any item,'the system gives an immediate message indicating the status. By this means a lot of waiting and search time associated with any manually operated stores, is saved. There is a better space utilisation, as the vertical space is utilised most effectively in an AS/RS. Large volume and variety of material can be stored over a significantly small floor area. As the entire stocking area is cordoned off and only automated crane operation is allowed in the racks, the chances of pilferage as well as misplacement of items are m inimised. As any item stored in the system can be easily traced from the memory of the computer (11), it is highly unlikely to permanently misplace any item. The tracks (9,5) are modular in nature, allowing easy to be handled. Usually the width and depth of the .racks are to be prefixed before erection/ as these are to be grouted on the floor. However/ the height of each pocket can still be altered by re-positioning the platform bases along the columns. By this way/ a mix of different heights of Bins (14) can also be handled in different segments of the rack system. An AS/RS can be divided into four major elements, stacker crane (2) , storage structures (1,conveying devices (14) and system controller (4/ 11). Stacker Crane (2): It is the basic element of the system. It is made to function accurately and safely at higher speeds/ reachina heights beyond 20 feet and operating in aisles only inches wider than the load it carries. Since it has to be automated/ it can also be operated by remote control. The modern stacker crane runs on a floor mounted rail (9) and is guided at the top (5). It com es in a wide variety of sizes and configura- (7) tions because its design is a function of the load/it carries and the task it performs. Speed is generally determined by the system's throughput requirements (i.e. how many loads need to be stored and retrieved in an hour). Travelling speeds vary from 2-75 meters/min while hoisting speeds vary from 2-7 meters/min. For travelling and hoisting three phase AC motors (8) are used. For travelling at high speeds, motors (8) in the range of 1.5 - 2.5 HP are used and for travelling at low speeds motors of 0.5 - 1 Hp are used. For hoisting purposes two speed motors (8) of 7.5 - 10 HP are used. The payload of the m achine is to be decided as per the requirement of the user. It may be in the range of 5 00 - 2000 Kgs. Figure 2 illustrates a typical dual masted heavy duty storage / retrieval machine. It travels along a floor -mounted guide rail (9) by means of power driven wheels/ and is also supported by top guide rails (5). The table (7) on the carriage (3) is capable of loading and unloading parts or pallets in both directions and accessing any stack in the warehouse. It has a positioning system anc powered drive system in the following three axes: horizontal movement of the shuttle table (4)/ vertical movement of the carriage and movement of the stacker crane along the guide rai1 (9,5). Storage Devices (1): anes In AS/RS material is stored in racks (1) which differ from conventional racking. These storage racks are normally much higher and interface directly with the stacker cr (2). AS/RS racking system must provide for the integration of stacker crane guide rails and fire protection systems. The most common storage structures (1) are free standing and are installed inside a building. Figure 3 i1lustrates a set of racks showing three v iews• Specifications differ depending on type of load to be stored and system configuration. Presently an increasing number of systems are rack supported, that is, the rack storage structure supports the building itself. This type of system can be upto 30 meters tall and is popular because it saves construction time and cost of more than 20%. The materials are kept in bins{14) which must be of a standard size for an AS/RS. The Bins (14) are kept on the platforms supported by the columns of the system. The columns of racks' are made of cold rolled steel. The columns are louvred to give additional strength to the racks. Also due to louvring the platform of the bins Conveying Devices: These are devices which transport loads beyond the limits of the stacker cranes. Some systems need a few conveyors, while others require elaborate conveying devices; connecting the S/R system wi th other plant operat ions . Among the conveying devices , there are fork lifts, roller or chain conveyors, guided vechicles, robots, overhead power and free conveyers, in floor tow lines or shuttle t rolleys. T he AGV (automated guide vehicle) is also used in some part of the work. The AGV transports goods, that is tool s can be shifted to any desirable height of the rack. or assembly parts,from one part to another and is guided by mini computers- When the AGV is instructed; to bring a certaa in object from the AS/RS, it would go and wait near the delivery counter of the AS/RS till the object is loaded on it. After that it brings the required object to the required place as guided by the computers. By integration of the AGV Route controller with the AS/RS controller, one can achieve a cO-ordinated material handling and movement in the entire shop - floor automatically. This is one of the applications of the AGV in a manufacturing unit. Controllers ( 11,4): The AS/RS controllers bring everything (equipment and information) together to enable proper system function. An i ncreasing number of S/R systems are computer controlled. Each S/R machine has its own on-board microprocessor / PLC which provides the automation for the individual machine. The conveyors are controlled by a sim ilar processor. All these processors communicate with an equipment controller ( (also a small computer ) which runs the over all system by remote control. SYSTEM SPECIFICATION : The prototype AS/RS developed as one of the embodiment and installed at the Technology Development Laboratory of Corporate R&D has the following specifications: Number of Racks : 2 rows Number of Stacker Cranes : 1 Height of the Racks : 7.2 Meters Number of levels in vertical: 6 d irection Number of Bins(locations) : 72 Size of each Bin : 800 x 800 x 800 mm Payload of the crane : 1000 Kgs. Total Tonnage capacity : 72 Tons Floor space occuppied : 400 sq. Ft. (40 sq.Mt) Stacker crane type : Single column Travel speed of stacker crane Horizontal : 60 Mtrs ./Min (high) 3.5 Mtrs/Min (low) Vertical : 7 Mtrs./Min (high) r 2 Mtrs./Min (low) Form movement 6 Mtrs./Min Operational Modes : From PC (fully automatic) or From Pendant (semi-auto) or Manual with operator in the cabin of crane Inventory Control : Automatic with PC resident software SOFTWARE: PLC Software: The PLC controls the movements of the crane and the fork for any storage and retrieval operation. It interacts with various sensors mounted on the crane for registering the position of the crane/ the vertical carriage/ and the fork. It is interfaced with the System controller for taking the inputs regarding the destination/ the type of operation (store/retrieve) to be carried out and the side of the rack (left/right) to be approached. The PLC software is written in SIMATIC-S5 language suitable for SIEMENS PLCs. The program is written by using different Program Block (PBs) for faster execution. It also allows calling of d ifferent PBs for different cycles of operation. There is a separate PB for the main travel/ and one each for the retrieve and the store cycles. All the outputs required to define the destination column number/ row number/ store/retrieve command/ and the side of rack (right/left) must be i ssued from the PC based system controller in a proper sequence. The crane will be moved only after receiving all of these inputs at 24 VDC level and followed by a GO AHEAD pulse also at 24 VDC level. A remote hardware emergency switch is provided near the system controller for stopping the crane in case of € any malfunction. A separate PB is written for initialisation and re-definit ion of the crane posit ion/ which may be used in case of intermediate manual operation of the crane. This c can be activated from a remote pendant by a combination of Input switches. Retentive flags are used for memorising the destination and other essential commands in the battery supported RAM area in cases of power failure. The operation of the crane for the same function as it was. doing before power failure can be easily resumed by resetting the PLC Controller. System control software: The system control software is resident on the PC/AT/ which is configured as the system controller. It is written in QBASIC language using modular concept. The program is interactive in nature and the operator can store or retrieve any Bin by only keying in the Bin number from the keyboard. The operator faces a screen with different options indicated for storing/retrieving/displaying the status of racks etc. A separate option is offered for defining the initial locations of the Bins. This is useful for initial definition as well as indicating the positions of Bins after any intermediate manual operation of the crane. The display rack status option shows the locations of all the Bins in the racks in a graphical matrix form. The software autom atically updates the contents of the location table after every successful store or retrieve operation. OPERATION OF THE SYSTEM: The AS/RS commissioned at Corp., R & D is designed for operation in three different modes - Fully automatic mode from the system controller Semi automatic mode from a Pendant Manual mode with operator in the cabin Automatic tracking of material and inventory control is possible only in mode 1. The other two modes are provided for operation during m aintenance and in case of a system failure from the PC side. In mode 1/ the system control software guides the operator through an interactive menu appearing on the screen of the pc based system controller. The first screen has r five options as printed on the next page. By selecting the appropriate option/ one can do the following functions : Option 1: One can define the initial locations of various Bins, once for all during commissioning or in case of any intermediate manual operation of the crane. Option 2; One can retrieve any Bin/Pallet available in the system. Option 3; One can store any Bin/Pallet in the system. Option 4: One can see the status of the racks i n graphical presentation. Option 5: Used for closing all files and coming out of the control software. For retrieving a Bin/Pallet/ one has to select option 2 for the first menu and then enter the Bin number against the next prompting from the system controller. The controller searches through its database and locates the position of the Bin in the racks. It then instructs the PLC to drive the crane to the correct pocket and withdraw the B in. If the Bin is not available in the racks, an warning is given to the operator on the screen as well as with an audio signal. After withdrawing the Bin/ a Bar code fixed on the Bin is read by a Bar code (14) scanner (10) mounted on the crane. If the Bar code matches the Bin is delivered at the load/unload counter. If the Bar code does not match/ the system prompts the operator to give his choice of either keeping the Bin back at the same location/ with the proper Bin number read from the Bar code or delivering it at the counter. In case the Bar code is not readable or not present/ the system asks for decision regarding next operation from the operator. Once the Bin is delivered, the system automatically updates its data base regarding the locations of all the Bins. For storing a Bin in the system/ one has to only select the storing option. The system checks for the availability of the Bin at the loading/ unloading counter. If the Bin is present, it is loaded on the crane and the Bar code sticker is scanned to obtain the Bin number and the destination for the Bin. If the data is valid and the destination is empty, the crane is driven by the PLC to deposit the Bin there. The data base is automatically updated thereafter. In case of an invalid bar code or the destination being occupied, the Bin is unloaded after giving an warning message and a hooter signal. WE CLAIM: An automatic device for storage and retrieval of the material for use in a highrise storage rack/structure comprising a computer based control means, a stacker crane with programmable logic control (PLC) means to operate a single column stacker crane, an interface for inter connecting said PLC and computer control means, warning means comprising a Bar Code Scanner for reading the bar code fixed on the bin disposed in said storage racks is directly interfaced with said computer means for reading, and verifying the bins. A device as claimed in claim 1 wherein said computer based control is provided with a resident software so as to store or retrieve any Bin by keying the BEST number from the key board. A device as claimed in claims 1 and 2 wherein said interface has a 24VDC-5VDC and 5VDC-24VDC level converter cards for matching and transmission of signal commands. A device as claimed in claims 1 to 3 wherein said stacker crane control means has a programmable logic controller (PLC) to receives control commands from said computer-based control means so as to control the safe operation of the crane. A device as claimed in claims 1 to 4 wherein said single column stacker crane has a split fork for handling variety of Bins and Pallets and is provided with simplified gear boxes and two speed hoist alongwith fail safe brakes. An automatic device for storage and retrieval of the material for use in a highrise, storage rack/structure substantially as herein described and illustrated in the accompanying drawings.

Documents:

271-del-1995-abstract.pdf

271-del-1995-claims.pdf

271-del-1995-correspondence-others.pdf

271-del-1995-correspondence-po.pdf

271-del-1995-description (complete).pdf

271-del-1995-drawings.pdf

271-del-1995-form-1.pdf

271-del-1995-form-2.pdf

271-del-1995-form-3.pdf

271-del-1995-form-4.pdf

271-del-1995-form-5.pdf

271-del-1995-form-6.pdf

271-del-1995-form-9.pdf

271-del-1995-gpa.pdf

abstract.jpg