Abstract:
A laser cutting system wherein a conveyor system indexes sheet material through various processing stations, the processing stations operating simultaneously during the time period when the conveyor is stopped and wherein the conveyor system is in the form of an endless belt.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of application Ser. No. 13/987,002, filed Jun. 24, 2013. 
       BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
       [0002]    The present invention provides an improved conveyor adapted for use in a system that loads, processes (cuts), sorts and stacks a variety of sheet metal parts, the cutting process being performed by a high speed laser. 
       2. Description of the Prior Art 
       [0003]    Sheet metal products are typically formed in a piece of sheet metal and connected to the sheet metal through one or more micro-joints. In order to separate these pans, it is conventional that subsequent mechanical or manual hammering or vibrating is carried out with respect to the sheet metal 
         [0004]    The use of a moving table to transport sheet metal is a highly effective system when the laser unit operates at a slower pace. However, for faster laser units which require processing complete sheets in less than two minutes, the conventional moving table systems have been found to he inefficient. When the total load, cut, unload and sort process for a metal sheet is to be completed in two minutes or less, a high speed conveying system is required. 
         [0005]    U.S. Pat. No. 8,253,064 to Beck et al discloses a laser blanking device for high speed cutting of material that uses synchronized laser cutting operations along multiple axes and on a continuously moving coil strip. 
         [0006]    The coil strip is moved through the device at a velocity substantially equal to the velocity of the moving pin conveyor. 
         [0007]    The system is designed to increase production rates by minimizing stationary periods; this is accomplished by increasing the speed of the cutting operation of rapidly fed coil stock (a “coil” of material weights between 5,000 and 40,000 pounds; changing between material types will take between 20-40 minutes). The problem with this is the inability to change material type and thickness quickly enough to keep up with a “high mix low volume” environment. 
         [0008]    A fiber laser cutting system (designated the FOL-AJ) for cutting material has been developed by Amada America, Buena Park, Calif. and is designed to take full advantage of the unique cutting capabilities of fiber laser processing. The advanced motion system and an innovative beam delivery system keeps pace with the cutting speeds and capabilities of the fiber resonator. The result is an extremely productive fiber laser system that delivers speed, accuracy, and edge quality, even in thick sheets. 
         [0009]    Although moving tables have been successfully utilized in the cutting operation noted hereinabove, there are inherent limitations in their use with high speed laser systems, such as the FOL-AJ. Specifically, Amada is currently marketing a FOL-AJ based system using a plurality of moving tables to convey material to the laser cutter. In this system, the movable table is loaded with material, the table traveling into/out of the laser device for each cycle. The empty moving table is loaded with the new material while the laser is processing the previously loaded material. After a moving table delivers the loaded material to the laser, and the material exits the laser, a different moving table is loaded with new material (a robot first unloads the cut parts before new material can be loaded onto a moving table). In addition, scraps must be unloaded before new material is loaded onto a moving table. Although this system performs extremely well, the use of moving tables in the process limits the processing speeds and, as a result, the processing times are less than desired for certain applications 
         [0010]    The system disclosed in the &#39;064 patent as noted hereinabove is also limited because of its inability to change sheet material type and thickness rapidly as is required in current system applications (as noted hereinabove, the &#39;064 system takes between 20 and 40 minutes to change material; the FOL-AJ system takes approximately 2 minutes to change material). In addition, part separations by gravity used in the &#39;064 system is limited to simple part geometries (i.e. round, rectangular and square) because more complex geometries will hang up in the skeleton and not drop correctly. 
         [0011]    Standard endless belt conveyors move material, parts, etc. from one location to another at normal conditions. However, prior art endless conveyor belt or chain are not capable of passing through the inside of the laser cutting machine without damage from the laser beam, dust and slugs generated during the laser cutting process (the term “slug” refers to the buildup of material from metal cutting/melting). 
         [0012]    Patent application Ser. No. 13/987,002, filed on Jun. 24, 2013 and assigned to the assignee of the present invention, discloses a laser cutting system wherein a conveyor system indexes sheet material through various processing stations. The conveyor is configured as a chain type member that moves in an endless loop. Although the system described therein performs well, an improved conveyor system would be desireable. 
         [0013]    What is thus desired is to provide an improved material conveyor system adapted for use in laser processing systems which overcome the disadvantages of using the prior art systems as noted hereinabove and improves upon the basic conveyor system disclosed in the &#39;002 application. 
       SUMMARY OF THE INVENTION 
       [0014]    The present invention provides an automated system for handling material and parts and scrap cut therefrom and in particular, an improved conveyor system that enables high speed laser material cutting. 
         [0015]    The system uses a conveyor for the material, the conveyor moving sheet material into the laser for cutting purposes. The empty conveyor space is loaded with new material as the laser is processing the previously loaded sheet of material. The conveyor is indexed one position such that new sheet material is loaded into the laser as processed material is moved from the laser to the part unloading station, both processes occurring at the same time. 
         [0016]    A robot then unloads the parts from the processed sheet material while new sheet material is being loaded on the side of the conveyor opposite where the laser is positioned. The conveyor is further indexed and scrap is automatically unloaded, all the processes occurring simultaneously. 
         [0017]    The conveyor features noted hereinabove significantly decreases the system processing time compared to systems using moving (shuttle) tables and is particularly adaptable for use with high speed lasers, such as the FOL-AJ system noted hereinabove. 
         [0018]    The sheet metal material is precut to specific lengths, allowing many types and thicknesses of material to be loaded and processed on a sheet by sheet basis. Parts are picked up by a robot and stacked in preparation for the next process (bending, welding, etc.). Scrap is destructed during the last process and is automatically dumped into a scrap box as the conveyor indexes. A material storage tower with a sheet by sheet loading process is also provided. 
         [0019]    An important feature of the present invention is the provision of multiple chain rows to support the material and create clearance for slug drop-down. Since the chain is passing through the laser, structure is provided to support the chain on the top and bottom and to protect the chain from damage that normally would be generated during the laser cutting operation. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0020]    For a better understanding of the present invention as well as other objects and further features thereof, reference is made to the following description which is to be read in conjunction with the accompanying drawing wherein: 
           [0021]      FIGS. 1 and 2  are views of a prior art conveyor system; 
           [0022]      FIG. 3  is a perspective view of the conveyor system of the present invention used in a laser material cutting system; 
           [0023]      FIG. 4  is a plan view of the system shown in  FIG. 1  illustrating the movement of the material through the system stations; 
           [0024]      FIG. 5  illustrates the positioning of the conveyor during system operation; 
           [0025]      FIGS. 6-13  are computer flow charts for the operation of the conveyor system of the present invention; and 
           [0026]      FIGS. 14-16  illustrate components of the unloading portion of the conveyor system. 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0027]      FIGS. 1 and 2  illustrate a prior art system  10  for handling material and parts cut therefrom utilizing movable tables, such as shuttles described in co-pending Ser. No. 13/987,002 filed Jun. 24, 2013. System  10  comprises laser cutting device  11 , shuttle table  12 , upper shuttle cart  14 , lower shuttle cart  16 , cart wheels  18  and  20 , tracks  22  and  24 , and cylinders  26  and  36 . Cylinders  26  and  36  operate to raise and lower shuttle carts  14  and  16  respectively, in a predetermined sequence such that the carts can he aligned with the tracks associated with laser cutting device  11 . In essence, the shuttle carts  14  and  16  are used to both transport sheet material to the laser cutting device  11  and to remove the sheet material after parts are cut therein (the skeleton). 
         [0028]      FIG. 3  illustrates the apparatus utilized to cut parts from sheet material by the cutting system  40  using, the conveyor  46  of the present invention. 
         [0029]    (a) The system operator sets up raw material storage in tower  42 . The material size, thickness, type, sheet quantity, and shelf location are recorded in a microprocessor as will be described hereinafter. 
         [0030]    (b) The system operator then sets up a processing schedule for processor  44  ( FIG. 4 ) utilized to control the system  40 . The program number, material name, and run quantity are entered in sequence. The software runs on a conventional Windows OS computer (a flow chart illustrating the program steps is illustrated in  FIGS. 5-12 ). 
         [0031]    (c) The system operator initiates system operation by turning on processor  44 . 
         [0032]    (d) A raw material sheet is loaded from storage tower  42  according to the schedule requirement stored in processor  44 . 
         [0033]    (e) Conveyor  46  moves a sheet of raw material from an initial position (Position # 1 ) to the second position (Position # 2 ) in preparation for laser cutting by laser device  48 . The storage tower  42  readies the next sheet in sequence for loading. 
         [0034]    (f) When the material sheet is confirmed in position by a sensor (not shown) for laser cutting, the laser cutting system  48  executes the laser program portion of the software (the software determines the dimensions of the part to be cut) and storage tower  42  loads the next sheet of raw material to the first conveyor position. 
         [0035]    (g) When storage tower  42  finishes sheet loading at the first conveyor position and laser cutting system  48  finishes cutting at the second position, the conveyor system control  50  ( FIG. 4 ) advances the cut sheet to a third position (Position # 3 ) for unloading and the raw sheet material loaded at Position # 1  advances to the Position # 2  at the same time. 
         [0036]    (h) Storage tower  42  then loads new raw material to conveyor Position # 1  as required by the software, laser cutting system  48  continues laser cutting at Position # 2 , and a parts sorting robot  52  starts the unloading sequence at Position # 3 . 
         [0037]    (i) Robot  52  stacks cut parts according to the software program. When stacking, laser cutting and raw material sheet loading is complete at conveyor Position # 3 ,  2 , and  1  (respectively), conveyor  46  advances—repeating the processes as set forth hereinabove in accordance with the schedule established by the software. 
         [0038]    (j) As conveyor  46  advances, the skeleton sections remaining after the programmed parts are cut are forwarded from conveyor Position # 3  and drops onto the skeleton conveyor  60  which moves skeleton, parts forward so they drop into the skeleton collection bin  62 . The skeleton conveyor  60  advances simultaneously with the conveyor  46 . 
         [0039]    Robot  52  stacks cut parts at the scheduled quantity at a designated location (the system operator ensures that the stack height is limited to one that is stable) and includes sensors (not shown) to detect hanging, tipped-up, and missed pick-up of parts and will stop system operation as these conditions occur. 
         [0040]    Robot  52  fault recovery is at the operator&#39;s option, the flowchart therefor being shown in  FIG. 13 . Robot  52  may retry, skip current part pick-up, or abort parts pick-up from the output cut sheet. Parts not unloaded from the conveyor system by robot  52  may be retrieved at the outer end of the skeleton conveyor by hand (the operator may manually “Jog” the skeleton conveyor forward to access parts) the operator preventing the parts from dropping into the skeleton collection bin  62 . 
         [0041]    The operator stops the robot operation in order to enter the unloading area where unload carts are positioned. The operation resumes once the operator exits the area. 
         [0042]    As noted hereinabove, flowchart for the software used to control the system of the present invention is shown in  FIGS. 6-12 . The software runs on a conventional Windows OS computer and sends job data to the laser process machine automation system. The job data includes the location, size and thickness of the raw material and the numerical control (“NC”) program to be executed in the laser process machine and parts sorting data to be executed by the parts sorting robot. 
         [0043]    The aforementioned data are sent at different but synchronized timing as the system control requires. 
         [0044]    The software schedules a plurality of job data so that the laser cutting system can be operated unattended for a period of time. The schedule is entered into the software by a human operator (or automatically loaded using a predetermined interface method). 
         [0045]    The software is able to detect alarms which occur on the laser cutting system and then send notification messages to those involved in the system operation; in addition, the computer outputs production result information for the system operator. 
         [0046]    The use of an endless chain conveyor system instead of conventional movable tables for handling sheet material enables the four processes (load, cutting, unload, and scrap removal) to be done simultaneously and continually at very rapid speeds (a single sheet of material can be processed in approximately thirty seconds). A will be described hereinafter, the chain conveyor system is configured to resist damage as it travels through the laser cutter. 
         [0047]    Referring to  FIGS. 6-12 , the operational flow chart for system  40  is illustrated. 
         [0048]      FIG. 6  shows a process start block ( 200 ) which, when activated by an operator causes system  10  to be initialized and the laser cutting operation to proceed. All safety interlocks are placed in the ready state (block  202 ) which, in turn, causes the computer to start the software process (block  204 ) causing the conveyor controller  50  to receive a sheet load command (block  206 ). If the required sheet is determined to be present (blocks  208  and  210 ), the sheet is loaded to the conveyor first position (block  212 ). A sensor then determines if the material is loaded successfully (block  214 ). The next process sequence is initiated via a signal on lead  215 ; if the required sheet is not in the material storage tower (block  216 ), an alarm is sounded (block  218 ). 
         [0049]    Referring to  FIG. 7 , if the conveyor sensor confirms the sheet position (blocks  300  and  302 ), a control block confirms everything is ready (block  304 ) after a short delay and a conveyor move command is issued (block  306 ). The system then determines whether the conveyor is in the proper position (block  308 ). If so, the conveyor sensor confirms the position of the sheets (blocks  300 ,  302 ). If the conveyor position ready is not confirmed (block  314 ), an alarm (block  316 ) is issued. Referring to  FIG. 8 , once the conveyor sensor confirms the position of the sheets, the laser cutting unit receives a start command (block  400 ) which is the beginning of process B and begins the cutting process (block  402 ) (this corresponds to the second position of the sheet being cut). If the loading of the follow-up sheet is scheduled, process A is repeated (block  404 ). A signal is issued when the cutting cycle is completed (block  406 ), thus ending process B. 
         [0050]    The portion of the operation flow chart shown in  FIG. 9  confirms that processes A and B have been completed (block  500 ). If not completed, an alarm is initiated (block  502 ,  504 ). If process A and B are confirmed to be completed (block  506 ), and the control block is confirmed to be ready (block  508 ), a conveyor move command is issued (block  510 ). The system then determines if the conveyor position is correct (block  512 ); if not, an alarm indication is issued (block  514 ,  516 ). Referring to  FIG. 10 , if the conveyor sensor confirms that the position of the next sheet is correct, processes A and B are repeated if scheduled (block  600 ). At the same time, the parts sorting robot (PSR) receives a start command (block  602 ) which is the start of process C. The PSR unloading cycle starts at the third position (block  604 ) and a signal indicating that the PSR unloading has been completed (block  606 ) and process C then ends. 
         [0051]    It should be noted that the machine operator could initiate a PSR fault recover (block  608 ), the flow chart portion therefor being set forth in  FIG. 12 . 
         [0052]    Referring to  FIGS. 11 and 12 , the system determines whether processes A, B and C have been completed (block  700 ). If not, an alarm is initiated (block  702 ,  704 ). If it is confirmed that processes A, B and C are completed, the control microprocessor is confirmed to be ready after a short (i.e. 3 second) delay (block  706 ,  708 ). A conveyor move command signal is issued (block  710 ) and the system then determines if the conveyor position is ready (block  712 ). If not, an alarm is generated (block  714 ,  716 ). If the conveyor position is ready, a conveyor sensor confirms whether the sheets are in the correct positions (block  720 ); if not, an alarm is sounded (block  722 ,  724 ). If the conveyor sensor confirms that the sheets are in the correct position, process A (sheet load), process B (laser cutting) and process C (PSR unload) in accordance with the program schedule (box  722 ,  724 ), has been completed and the system is deactivated (block  726 ). 
         [0053]    The parts sorting recovery flow-chart sequence is shown in  FIG. 13 . If the system sensors detect part pickup failure, tip-up, or the skeleton portion of the sheet is still attached (block  800 ), the system operator can skip the unloading of that sheet (block  802 ). The PSR skips the pickup and is directed to the next part (block  804 ) and the PSR resumes normal operation (block  806 ). If the PSR does not skip pickup, the system then returns to the sensors detect part pickup process (block  800 ). Note that the operator has the option of aborting the part unloading the current sheet as the conveyor advances (block  808 ,  810 ) and the PSR then resumes normal operation (block  806 ). Note that the operator also has the option of attempting to unload the part again (block  812 ,  814 ). If successful, the PSR resumes normal operation (block  806 ). If the pickup is unsuccessful, the system returns to the sequence wherein the sensors operate whether part pickup has failed (block  800 ). 
         [0054]    As noted hereinabove, a key feature of the present invention is the “endless” conveyor system which enables material to be cut at speeds that exceed those currently available. Details of the conveyor construction which supports this feature is shown in  FIGS. 14-16 . 
         [0055]      FIG. 14  is a cut away view along the length of the conveyor and comprises the following components:
       (1) Bolt  900  which holds the cover chain  914  and the skids  916  at both ends to the chain block;   (2) Drive shaft  902 ;   (3) Outer plate  904 ;   (4) Lower support rails  906 ;   (5) Conveyor frame  908 ;   (6) Idler shaft  910 ;   (7) Outer roller chain  912 ;   (8) Chain cover  914 ;   (9) Skids  916 ; and   (10) Upper support rails  918 .       
 
         [0066]    A servo motor (not shown) drives the conveyor forward by propelling the drive shaft  902  where chain sprockets are mounted for both inner chain  906  ( FIG. 18 ) and outer roller chain  912 . Chain movement is synchronized by utilizing a single drive shaft  902 . The servo motor precisely controls conveyor position while sensors confirm material placement during loading and conveying operations. Skids  916  are arranged into 5 (five) sections at intervals which allow proper spacing for utilizing loading, cutting, and unloading areas simultaneously. 
         [0067]    The conveyor skids  916  provide ma drum open area for air circulation during the cutting process and enables a laser system dust collector ( 45 ,  FIG. 4 ) to remove contaminants suspended in the air of the machine cavity during the laser cutting operation. Conveyor skids  916  also allow small shapes cut from the sheet material to pass through the conveyor and into a collector system in place at the base of the laser cutting machine. 
         [0068]      FIG. 15  is a cut away view across the conveyor illustrating the inner single chain component parts as follows:
       (1) Upper support rail  950 ;   (2) Skids  916 ;   (3) Chain cover  952 ;   (4) Inner roller chain  956 ;   (5) Bottom chain tab  958 ;   (6) Plate  960  for mounting chain cover  914 ;   (7) Lower support rails  962 ; and   (8) Conveyor frame  908 .       
 
         [0077]    The inner singer roller chain is driven by the conveyor drive shaft  902  ( FIG. 14 ), the chain being driven by sprockets mounted thereon. Upper support rails  950  support and guide the chain at the rollers. The lower support rails  962  eliminate chain sag by carrying the chain and skid weight using chain tabs  958  integrated into alternating chain side plates. 
         [0078]    The outside plate  980  ( FIG. 16 ) of the inner section of the single roller chain is extended to provide a mounting surface for the chain covers  982 . These provide center support for the skids  916  and protect the chain and drive mechanisms from the laser cutting residue (molten metal particles) that is expelled during the laser cutting process. 
         [0079]    Note that the skids and chain covers (which are exposed to the laser cutting residue) can easily be replaced when residue builds up and/or when exposure to the laser cutting beam reduces the integrity or functionality of these components. 
         [0080]      FIG. 16  is a cut away view across the conveyor illustrating the outer double chain component parts as follows:
       (1) Skids  916  which are bolted at both ends to chain block  900 ;   (2) Chain block  984  which is bolted to chain outer plate  980 ;   (3) Chain cover  904  which is bolted to chain block  984 ;   (4) Top chain lock  986 ;   (5) Outer double roller chain  988 ;   (6) Support rails  990 ;   (7) Low chain lock  992 ;   (8) Low chain support  994 ;   (9) Conveyor frame  996 ;   (10) Outer plate  998  which carries chain, block  984 ; and   (11) Outer double roller chain  999 .       
 
         [0092]    The outer double roller chain  988  is driven by the conveyor drive shaft  902  and the outer most chain section is driven by sprockets mounted on the drive shaft. The inner section of the double chain has a common roller pin with the outer chain and is also driven by sprockets mounted on the same drive shaft. Chain locks and support rails support and guide the chain en its rollers and eliminates sag. 
         [0093]    The outer plate of the inside section of the double roller chain  988  is extended to provide a mounting surface for the chain block  984 . This provides the connection between the miler chain  984  and skids  916 , allowing the chain to carry them around the conveyor as the conveyor indexes forward. The skids  916  provide the resting surface for the sheet material being loaded onto the conveyor and allows cutting by the laser machine  48  while supporting cut part shapes until unloaded at the end. 
         [0094]    The chain covers  914  are bolted on by their mounting tab which is inserted between the chain blocks and skids. These protect the chain and drive mechanisms from the laser cutting residue (molten metal particles) that is expelled during the laser cutting process. 
         [0095]    While the invention has been described with reference to its preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the true spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its essential teachings.