Patent Publication Number: US-2021187533-A1

Title: Fluid dispensing and curing system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application relates to commonly-owned, U.S. Provisional Patent Application, Ser. No. 62/952,254 entitled “PNEUMATIC ROBOTIC FLUID SPRAYING SYSTEM” filed on Dec. 21, 2019. The contents of such application are included herein in their entirety. 
    
    
     PRIORITY CLAIM 
     This application claims the benefit of, and priority to, commonly-owned, U.S. Provisional Patent Application, Ser. No. 62/952,254 entitled “PNEUMATIC ROBOTIC FLUID SPRAYING SYSTEM” filed on Dec. 21, 2019. The contents of such application are included herein in their entirety. 
     COPYRIGHT NOTICE 
     Portions of this document may contain material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction of the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all rights relating to the reproduction, distribution, copying and display of this copyrighted work. 
     TECHNICAL FIELD 
     The present invention relates to a fluid deposition and curing system for spraying/curing fluid on a work-piece, and more particularly, a new, useful and cost effective fluid spraying and curing system for depositing a volatile fluid on a work-piece to mitigate hazards due to the flammability of such volatile fluids. 
     BACKGROUND 
     Spray systems used in the automobile, boating or aircraft industries typically employ a spray booth having one or more articulating heads which traverse the surface of the work-piece, e.g., fender, bumper, hull, bulkhead, or tailcone etc., as paint is deposited on the surface. Generally, the spray environment is highly controlled and properly ventilated to prevent volatiles gassing off the spayed paint from reaching a combustible level. Inasmuch as an Original Equipment Manufacturer (OEM) can readily control the work environment, i.e., the volatiles therein, robotic systems employing electronically-controlled motors can be implemented in a manner which essentially eliminates the potential for producing a flammable work environment. On the other hand, business operators which repair or repaint vehicles, or discrete parts thereof, generally do not have the necessary controls to obviate the creation of a flammable or hazardous work environment. As such, these operators generally employ hand held spray deposition systems, the efficacy thereof being highly dependent upon operator skill and touch to deposit the fluid, i.e., paint, acrylic, resin, or clear coat, evenly and with the proper thickness. That is, robotic systems have not been employed in business operations which do not have repeatable requirements, i.e., always having different work-pieces with different surface contour, and do not have the ability to monitor the environment to the level necessary to avoid a hazardous condition. 
     The foregoing describes some, but not necessarily all, of the problems, disadvantages and shortcomings related to prior art spray deposition systems. A need, therefore, exists for a fluid deposition system which provides a highly controlled, evenly deposited, fluid coating or spray on a surface of a work-piece without incurring environmental hazards due to the flammability of a volatile fluid. An need also exists for providing such robotic system so as to minimize the time and cost associated with curing and/or drying the sprayed fluid. 
     SUMMARY 
     In one embodiment of the disclosure, a robotic system for applying and curing a volatile fluid to a work-piece is provided, comprising a support structure configured to mount at least one spray nozzle while facilitating motion of the nozzle in multiple degrees of freedom. An encoder senses a position of the spray nozzle issues a position signal indicative thereof. A pneumatically-driven motor effects displacement of the spray nozzle on the support structure along each degree of freedom. A controller disposed outside the boundaries defined by the structural support, is responsive to the position signals for controlling the pneumatically-driven motor to displace the spray nozzle while dispensing the volatile fluid. The pneumatically driven motor and confined or isolated spatial position of the controller prohibits a source of ignition for the volatile fluid sprayed by the nozzle. 
     In another embodiment, the robotic system may be equipped with machine vision to completely scan and plot the required data points to apply and cure the fluid. In yet another embodiment, the robotic system may employ more economical full-spectrum sensors to identify the color spectrum as to where and when to apply and cure the sprayed fluid. 
     In yet other embodiments, its common practice to utilize displacement sensors to maintain a requisite distance from the work-piece to the spray nozzle and/or the curing unit. All of the foregoing may be performed at the set-up or mapping stage, where the system utilizes a combination of techniques and methods to teach the pathways prior to performing a spray operation. As such, the risks and hazards associated with running electronics together with active spray nozzles are mitigated. 
     Additional features and advantages of the present disclosure are discussed in, and will be apparent from, the following Brief Description of the Drawings and Detailed Description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a first embodiment of a robotic fluid dispensing and curing system including a cuboid-shaped structural support having stationary support frame and a movable carriage assembly for mounting for three spray nozzles for dispensing a fluid onto a work-piece. 
         FIG. 2  is a schematic illustration of a sequenced displacement of the three spray nozzles of the fluid deposition system. 
         FIG. 3  is a schematic illustration of a first sequenced displacement pattern of the three spray nozzles of the fluid deposition system which depict the spray head movement necessary to avoid conflict of multiple heads spraying a particular area at a specific time. 
         FIG. 4  is a schematic illustration of a second sequenced displacement pattern of the three spray nozzles of the fluid deposition system which depict the spray head movement necessary to avoid conflict of multiple heads spraying a particular area at a specific time. 
         FIG. 5  is a perspective view of a second embodiment of the robotic fluid dispensing system including a movable carriage assembly having a single spray nozzle for dispensing the fluid onto the work-piece. 
         FIG. 6  is an enlarged isolated profile view of an inverted U-shaped frame member employed in combination with the movable carriage assembly. 
         FIG. 7  is a perspective view of a third embodiment of the robotic fluid dispensing system including a movable carriage assembly having: (i) a UV, or other, heat source for curing an adhesive paint dispensed by the at least one spray nozzle, (ii) a plurality of full spectrum sensors operative to stop and start the flow of fluid dispensed by the spray nozzle depending upon the color or wavelength or light detected by the sensor, and (iii) a plurality of displacement sensors to control the rate of displacement of the pneumatically controlled motors. 
         FIG. 8  is a perspective view of a wiper station or cleaning head operative to remove excess paint or sprayed fluid. 
         FIG. 9  is a perspective view of a mapping/teaching assembly comprising machine vision optics and a displacement sensor disposed within a protective casing. 
         FIG. 10  is a perspective view of a mapping/teaching assembly comprising a full spectrum sensor and displacement sensor disposed within a protective casing. 
         FIG. 11  is a perspective view of an absolute position sensor disposed within a protective casing and disposed along the drive axis of a pneumatically driven motor. 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure is directed to a robotic fluid dispensing system for spraying a volatile fluid, such as a resin based paint or coating on the surface of a work-piece. While the disclosure illustrates a robotic fluid dispensing system for an automobile, it will be appreciated that the fluid dispensing system is applicable to discrete components of the automobile or to other vehicles such as boats, fixed wing aircraft, rotary wing aircraft, and parts thereof. Additionally, it should also be appreciated that the robotic fluid dispensing system may be applicable to any work-piece, e.g., panels, doors, sheathing, etc., wherein an investment in robotic automation is warranted and, of course, profitable. 
     In  FIG. 1 , an exemplary embodiment of a robotic fluid dispensing system  100  includes a cuboid-shaped support structure  110  comprising a stationary support structure  112  and a movable carriage assembly  114 . The support structure  110  is configured to mount at least one nozzle  116  for spraying a fluid on a surface of the work-piece (not shown), which support structure  110  facilitates displacement of the spray nozzle in multiple degrees of freedom. In the embodiment depicted in  FIG. 1 , a plurality of spray nozzles  116  are mounted to the movable carriage  114 , though it should be appreciated that a single spray nozzle may be employed depending upon the degrees of freedom provided by the movable carriage  114 . This will understood when describing other embodiments, such as that disclosed in  FIG. 5  of the present application. 
     At least one position sensor  120 , operatively coupled to a controller  130 , is configured to sense a position of each spray nozzle  116  and provides position signals indicative thereof to the controller  130 . Additionally, at least one pneumatically driven drive device  140  effects displacement of the respective spray nozzle  116  along each degree of freedom provided by the support structure  110 . The controller  130  is responsive to the position signals and is additionally operatively coupled to the pneumatic drive device  140  and spray nozzle  116 , to control the displacement, and flow of fluid being dispensed from the spray nozzle  116 . That is, in the described embodiment, an encoder provides the location of the at least one spray nozzle  116  while a pneumatically driven motor  140  receives control signals issued by the controller  130  to control the position and rate of displacement of the spray nozzle  116 . A closed loop error feedback system may be employed to provide precise and immediate error position control of the movable carriage  114 , the spray nozzles  116  and pneumatically-driven drive devices  140 . At the same time, a predefined algorithm controls the fluid flow rate and/or volume of fluid flow dispensed by the spray nozzle  116  onto the surface of work-piece. One skilled in the art of control laws will readily develop the requisite control law algorithms and source code to efficiently and effectively program the controller  130  to control the amount of fluid dispensed from the spray nozzles, the relative position each spray nozzle  116  from the work-piece, the relative position of one spray nozzle  116  relative to another spray nozzle  116  and the rate of displacement of each spray nozzle  116  over the surface of the work-piece. The preferred control algorithms and method for controlling fluid dispensation will be discussed in greater detail hereinafter when describing the embodiments of  FIGS. 2 through 4 . 
     In the described embodiment, the stationary support structure  110  of the cuboid-shaped support structure defines at least two (2) pairs of parallel horizontal tracks  152   a ,  152   b ,  154   a ,  154   b  which are separated and supported by at least four (4) vertical support members  156   a ,  156   b ,  158   a ,  158   b , disposed at each corner of the cuboid-shaped support structure  110 . Consequently, two (2) corner vertical support members and their respective pair of horizontal tracks  156   a ,  156   b ,  152   a ,  152   b  define a right side plane P 1  while another of the two (2) corner vertical support members and their respective pair of horizontal tracks  158   a ,  158   b ,  154   a ,  154   b  define a left side plane P 2 . For added structural stability, intermediate vertical support members  153   a ,  153   b  may be disposed between each pair of corner vertical support members  152   a ,  152   b ,  154   a ,  154   b  and mounted outboard of each of the right and left side planes P 1 , P 2 . 
     The movable carriage assembly  120  of the cuboid-shaped support structure includes at least one pair of vertical track members  160   a ,  160   b  and a horizontal cross-member  170 , wherein each of the vertical track members  160   a ,  160   b  are configured for displacement mounting to each pair of horizontal tracks  158   a ,  158   b ,  154   a ,  154   b , and wherein the horizontal cross-member  170  is configured for displacement mounting to each of the track members  160   a ,  160   b . Each displacement mount includes a pneumatically motor driven device operatively coupled to the controller  140  to affect displacement of: (i) each vertical track member  160   a ,  160   b  relative to each pair of stationary horizontal tracks  158   a ,  158   b ,  154   a ,  154   b , and, (ii) the cross-member  170  relative to each vertical track number  160   a ,  160   b.    
     In a first embodiment of the disclosure, a spray nozzle  116  is articulately mounted to each member of the movable carriage assembly  120  such that each spray nozzle  116  may be displaced along three dimensional planes (X, Y, Z) and along at least one axis of rotation XA. While the support structure  110  and movable carriage provides displacement along three dimensional planes and one rotational axis, it will be appreciated that additional degrees of freedom, i.e., rotational displacement along two or more axes XA, YA, ZA, are desirable and may be obtained by articulately mounting the spray nozzles  116  onto each member of the movable carriage  114 . For example, a first and second spray nozzle  116  may be mounted to the vertical rails  160   a ,  160   b  while a third spray nozzle  116  may be mounted to cross-member  170 . In the described embodiment, the third spray nozzle  116  may rotate about a pitch axis XA disposed along the cross member  170 . 
     In  FIGS. 2 through 4 , two spray patterns are disclosed which describe methods for providing full coverage, uniform thickness, spray coating of a surface. For complete coverage, the starting position of the left-side spray nozzle  116  is along the left side bottom surface of a vehicle  200 . The starting position of the right-side spray nozzle  116  is along the right-side upper surface of the vehicle  200  while the starting position of the top-side spray nozzle  116  is at the left-side top surface  200 . The starting position of the movable carriage assembly  114  is at the left side front of the support structure  110 , i.e., along the left-side front of the perspective shown in  FIG. 1 . 
     In  FIG. 3 , the first pattern is characterized by the carriage assembly  114  moving incrementally, e.g., seven (7) increments, from a start position R 1 , L 1 , T 1  to an end position R 7 , L 7 , T 7 , and continuing along a reverse path from the end position to the start position. At each incremental position of the carriage assembly  114 , the left and right spray nozzles  116  move vertically in a continuous motion while the top spray nozzle  116  moves continuously from start-to-end, and end-to-start positions before the movable carriage assembly  114  shifts to its next incremental position. 
     The second pattern is characterized by the left, right and top-side spray nozzles  116  moving incrementally from a start-to-end position after moving carriage assembly  114  completes a full cycle of movement. At each incremental position of three spray nozzles  116 , the moving carriage assembly  114  travels continuously front-to-back and back-to-front before the spray nozzles  116  shift from their respective incremental position. 
     An examination of each of the two patterns reveals that the spray nozzles  116  are controlled such that they will not dispense fluid concurrently and/or coincidentally. As such, fluid can be dispensed completely and uniformly without too much fluid covering any one zone or area of the work-piece. It will, therefore, be appreciated that these patterns are configured to precisely control thickness and prevent running of the dispensed fluid. 
     In another embodiment of the disclosure depicted in  FIGS. 5 and 8 , the robotic system  100  may include wiper stations  180  mounted to the stationary support frame structure  110  for cleaning each of the spray nozzles  116  of excess or residual fluid. That is, to ensure proper atomization of the fluid, it will be periodically necessary to clean the nozzle of residue. In the described embodiment. A wiper station  180  is placed or positioned along the path of each spray nozzle  116  such that the nozzle may be cleaned upon engaging the wiper station  180 . In the described embodiment, the controller  130  may pulse the spray nozzle  116 , i.e., induce a pulse of pressurized air, to force excess fluid out of the nozzle  116  and into the wiper station  180 . Additionally, the stationary support frame  112  or the movable carriage assembly  114  may each include heat lamps (not shown) to facilitate curing of an adhesive paint. Of course, the wattage or power requirements of a heat lamp will be dependent upon the specifications of the adhesive paint being dispensed. 
     Another embodiment of a robotic fluid dispensing system  300  is depicted in  FIGS. 5 and 6 , wherein the same or similar components to those described in connection with  FIG. 1 , are identified with the same reference numerals. In this embodiment, a single articulating spray nozzle  116  mounts to a carriage assembly  114  having an inverted U-shaped frame member  350  pivotally mounting to the pair of vertical tracks  160   a ,  160   b  about a horizontal pitch axis XA. Therein, the articulating spray nozzle  116  includes rolling elements  310 ,  312  ( FIG. 6 ) which mount within and engage a continuous track which traverses the two corner elbows of the inverted U-shaped frame member  350 . More specifically, a pivoting V-shaped mount  360  is configured to engage the rolling elements  310 ,  312  to mount the spray nozzle  116  to the inverted U-shaped frame member  350 . As such, the pneumatically driven motors  140  may drive the spray nozzle  116  ( i ) across the base or cross-member portion  370  of the inverted U-shaped frame member  350 , (ii) around each elbow, and (iii) up or down each of the parallel legs  360   a ,  360   b  of the inverted U-shaped frame member  350 . It will also be appreciated that the combined vertical and pivot motion of the inverted U-shaped frame member  350 , i.e., about the horizontal pitch axis XA, allows the spray nozzle  116  to cover the top, left and right sides of the work-piece or vehicle. 
     In yet another embodiment depicted in  FIGS. 5 and 9 , a machine vision system  380  may be employed to map the region or paintable area of the work-piece prior to fluid spraying operations. This may include the entire work-piece, a door panel, a bumper, or some portion thereof. The machine vision system  380  is operably coupled to the controller  130  to define and record a scan of the work-piece  200 . Full spectrum sensors  500  may be used to prevent deposition of fluid in unintended areas, i.e., masked and unmasked regions defining those areas which may be subject to being sprayed with the fluid. The scanned work-piece  200  in combination with displacement sensors (not shown) may be employed for maintaining the requisite distance between the work-piece  200  and the respective spray nozzle  120  and/or a curing unit light or source of heat (not shown). 
     Yet another embodiment of a robotic fluid dispensing system  400  shown in  FIGS. 7, 10 and 11  includes: (i) a plurality of displacement sensors  420  to monitor the rate of displacement, or velocity, of the moveable carriage assembly  114 , (ii) a plurality of UV or radiant heat sources  430  operative to cure the adhesive or curable coating dispensed on the work-piece, and (iii) a plurality of full spectrum sensors  440  operative to start and stop the flow of fluid depending upon the wavelength of light energy sensed by the full spectrum sensors  440 . It will be appreciated that displacement, temperature and wavelength signals will be issued by each of the displacement, temperature and full spectrum sensors,  420 ,  430 ,  440 , respectively, and received by the controller  130  to determine the velocity, energy requirements and start/stop sequence of the fluid dispensed by the spray nozzles  116 . 
     With respect to item (i) above, it will be appreciated that the rate of displacement of each spray nozzle  120  determines the thickness of coating or layer dispensed by the spray nozzle  120 . As such, displacement sensors  420  may be employed to accurately determine thickness of fluid being dispensed onto the surface of the work-piece  200 . Alternately, a displacement signal may be derived from the position signals issued by the position sensors  120 . 
     With respect to item (ii) above, a plurality of UV or radiant heat sources  430  may be disposed in combination with each spray nozzle  116  (see  FIG. 1 ) to rapidly cure the adhesive coating or paint dispensed on the work-piece  200 . In the described embodiment, each of the vertical track members  160   a ,  160   b  and cross-member  170  may include an array of curing heat lamps or light emitting diodes  430  to curing the adhesive immediately following the dispensation of fluid. 
     With respect to item (iii) above, a plurality of full spectrum sensors  440  are operative to start and stop the flow of fluid depending upon the wavelength of light energy sensed by the respective full spectrum sensor  440 . For example, an area of the work-piece may be masked by tape of a particular color, e.g., red taped, such that upon sensing a wavelength of greater than about 660 nanometers, the controller may be programmed to “stop” dispensing fluid until such time that the wavelength change to another color indicative of a “start” dispensing signal. In this embodiment, an alternative placement of each wiper station  180  is shown. That is, rather than being located toward or at an end of the support structure, the wiper stations  180  may be located at the front portion of the cuboid-shaped support structure  110 . 
     In summary, the robotic systems  100 ,  300  of the present disclosure each comprise support structures  110  producing a cuboid-shaped frame having a stationary frame structure  112  for mounting a movable carriage assembly  114 ,  314  wherein the controller  130  is disposed outside the confines of the cuboid shaped frame and wherein the location of the controller  130  and the at least one pneumatically driven motor  140  prohibits a source of ignition for volatiles out-gassed from the sprayed fluid by one spray nozzle  120 . 
     Various systems may be combined or excluded to enhance or simplify the capabilities of the robotic fluid dispensing system. For example,  FIG. 7  depicts an alternate embodiment wherein the wiper cleaning station  180  is disposed at the entrance of the cuboid shaped support structure  110 . the spray nozzles  116  may be equipped with fixed or articulating mounts. The wiper station  180  for cleaning the spray nozzles  116  may be located at the front or aft end of the cuboid shaped support structure  110 . Motion sensors, displacement/position sensors and full spectrum optical sensors may be employed to enhance the accuracy of the fluid being dispensed. A curing assembly may be used to augment or accelerate the rate that the fluid dries. The number of spray nozzles  116  may vary from at least one nozzle  116  to three or more nozzles  116  depending upon the articulation and movement of the carriage assembly  114 . The surface of the work piece  200  may be scanned and mapped to determine the distance that a spray nozzle  116  must maintain for accurate and/or uniform spray thickness and quality. The curing system may employ an array of UV lights or a conventional radiant heat lamp. 
     Additional embodiments include any one of the embodiments described above, where one or more of its components, functionalities or structures is interchanged with, replaced by or augmented by one or more of the components, functionalities or structures of a different embodiment described above. 
     It should be understood that various changes and modifications to the embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present disclosure and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims. 
     Although several embodiments of the disclosure have been disclosed in the foregoing specification, it is understood by those skilled in the art that many modifications and other embodiments of the disclosure will come to mind to which the disclosure pertains, having the benefit of the teaching presented in the foregoing description and associated drawings. It is thus understood that the disclosure is not limited to the specific embodiments disclosed herein above, and that many modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although specific terms are employed herein, as well as in the claims which follow, they are used only in a generic and descriptive sense, and not for the purposes of limiting the present disclosure, nor the claims which follow.