Abstract:
A system element for the transporting and positioning of a tool on a surface of a workpiece, includes at least one suction device that generates a suction stream, and a transport device that is arranged around the suction device, and includes: at least two rollers that are rotatably supported on the suction device, connection elements that interconnect respective end regions of various rollers, and the rollers and the connection elements are elastically deformable, and when there is a suction stream, the system element substantially conforms with the surface of the workpiece.

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of the filing date of German Patent Application No. 10 2006 005 524.1 filed Feb. 7, 2006 and of U.S. Provisional Patent Application No. 60/771,196 filed Feb. 7, 2006, the disclosures of which applications are hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The field relates to a system element for the transporting and positioning of a tool on a surface of a workpiece. 
     BACKGROUND OF THE INVENTION 
     In order to use robots for machining large workpieces, it may be economical to rigidly position the workpiece and to let the robot move to the position where machining is to occur. If the dimension of the robot is to be kept small, the robot may be moved to a suitable position. If the workpiece is sufficiently stable, there may be no need to use external devices for leading the robot into position, for example, for scaffolds, provided the technical task of moving over the workpiece is solved. This may involve the sub-task of locomotion and, if the surface is inclined, of adhesion. 
     In order to achieve adhesion to the surface, the solution of providing the transport and positioning device with one or several suction cups suggests itself. This approach may be associated with some problems of implementing locomotion. For example, a window cleaning robot adheres to the window panes by means of suction cups. In the case of a window cleaning robot, a sliding suction function may be achieved. In order to combine good sealing characteristics with good sliding characteristics, in this arrangement, a liquid is injected between the suction cup and the window pane surface. 
     The known window cleaning robot may be designed for operating on substantially non-curved glass panes since, depending on the radius of curvature of the surface, significant limits apply to the size of the suction cups and thus to the contact pressure. Furthermore, it may be undesirable in use to put up with regular feed-in and the release of liquid. 
     SUMMARY OF THE INVENTION 
     Among other things, it may be an object to create an option for safely transporting and positioning a tool, in particular, on an inclined or curved surface of a workpiece. 
     In one example, a system element for the transporting and positioning of a tool on a surface of a workpiece, comprises at least one suction device that generates a suction stream, and a transport device that is arranged around the suction device, wherein the transport device comprises: at least two rollers that are rotatably supported on the suction device, and connection elements that interconnect respective end regions of various rollers, the rollers and the connection elements being elastically deformable, and when there is a suction stream, the system element substantially conforms with the surface of the workpiece. 
     According to one embodiment of the system element, the rollers and the connection elements contact lateral walls of the suction device, as a result of which between a suction side of the suction device, the rollers, and the connection elements, strong negative pressure may be generated as a result of the suction stream, and the system element may be safely held to the surface of the workpiece. 
     According to one embodiment of the system element, advance of the system element may be taken place by a torque applied to at least one of the rollers, as a result of which the system element and correspondingly, a tool coupled to the system element may be transported and positioned on the surface of the workpiece in an easy manner without the surface being damaged. 
     According to one embodiment of the system element, at least one connection element is formed as a running belt that interconnects two rollers by their end regions, wherein, at least on one of the end regions of the rollers, pulleys are arranged, which are rigidly connected to the rollers, with the running belt being placed around the pulleys, for the purpose of transmitting the torque to the rollers. As an alternative, the rollers may idle, with forward movement of the system element taking place solely by way of the running belts. 
     As an alternative, the connection element may be designed as a roller, which is, capable of been driven such by a motor that the mobility of the system element is enhanced. 
     According to one embodiment of the system element, a surface of the suction device that is defined by the lateral walls of the suction device and that faces away from the suction side of the suction device is designed so as to be quadrangular, and in each case, one roller is arranged on two opposite lateral walls, wherein the end regions of the rollers are connected to each other by way of a running belt. As an alternative, any desired forms of the suction device include various forms such as triangular, trapezoidal, etc., wherein any number of rollers and corresponding connection elements are provided on the respective lateral walls. 
     Several system elements may be combined to form a transport system, wherein the system elements are connected to each other so that large tools may be transported that may be coupled to the transport system. 
     The system element for transporting and positioning a tool on a curved surface of a workpiece operates with one or several suction devices which hereinafter are also referred to as “suction chambers,” which roll over the surface instead of gliding over it, so that friction may be drastically reduced. 
     In forward and reverse direction, a suction chamber rolls, for example, on flexible rollers that conform to the surface curvature of the workpiece under the effect of the air pressure and of a suction stream generated by the suction chamber, until the suction stream ceases and further movement may be possible while rolling and without loss of negative pressure. 
     The lateral surfaces of the suction chamber finish off with flexible running belts, which as a result of air pressure and suction stream conform both to the curved surface and to the suction chamber. 
     In this way, sliding friction may be shifted from contact with the workpiece to contact with the suction chamber so that by way of a suitable selection of the suction-chamber wall material, or by way of movable parts on the suction-chamber wall, sliding friction may be significantly reduced. 
     The advance of the suction chamber may, for example, be handled by the rollers or by the running belts. 
     For the rollers, depending on requirements of torque transmission, a single flexible material may be sufficient; a material combination made of a flexible envelope and a flexible but torsionally relatively stiff core may be advisable, or a core made from a chain of universal joints with longitudinal compensation might be the right solution. 
     For the running belts various profiles and designs may be considered, depending on whether the drive belts at the same time also assume the function of drive belts (torque transmission from a motor to the rollers), or on whether the drive belts are to be integrated in the running belts, whether they are externally coupled to the drive belts or whether they run along independently of the drive belts, for sealing purposes only. 
     In addition to the above-mentioned elements, near the contact positions between sealing parts and the suction chamber, airstream-reducing parts (e.g. pads made of fabric or sponge material) may be installed, which do not result in any significant friction but which in case of a leak clearly may reduce the speed of negative-pressure loss, and in this way may allow for a vacuum pump that communicates with the suction chamber to maintain adequate negative pressure. 
     Due to the flexibility of the rollers and the running belts, good adaptation to curved surfaces and at the same time good sealing may be made possible. Under the effect of the air pressure and the air stream, the system may automatically conform with the surface of a workpiece, wherein such conforming may not have to be ensured by separate control units. 
     Furthermore, if the curvature of the surface of the workpiece is not extreme, the base surface of a suction chamber (suction device) that may be provided may be large, the large surface may be an advantage, particularly in applications in aircraft construction, because in this industry sector, large parts have to be transported and positioned. 
     Furthermore, no wetting of the workpiece using sealing fluids or sliding fluids may be required. By shifting the principal friction to targeted contact surfaces with the suction device, friction may be minimised by optimising materials and the nature of the surface. The contact surfaces are, for example, strip-shaped. Furthermore, as a result of the rolling movement, the surface of the workpiece may be exposed to minimal stress. 
     According to one embodiment, for the purpose of locomotion of the system element, contact with the workpiece surface may not need cease; in other words, there may no need to cease negative pressure and then to build it up anew. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Below, with reference to the enclosed drawings, preferred embodiments are described. In the drawings: 
         FIG. 1  shows a diagrammatic perspective view of a system element according to the preferred embodiment; 
         FIG. 2  shows a diagrammatic lateral view of the system element according to  FIG. 1 ; 
         FIG. 3  shows a diagrammatic front view of the system element according to  FIG. 1 ; and 
         FIG. 4  shows a diagrammatic partial lateral view of a detail of the system element according to  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     The examples described and drawings rendered are illustrative and are not to be read as limiting the scope of the invention as it is defined by the appended claims. 
     Below, the same reference characters are used for identical components in the different views of the figures. The illustrations in the figures are diagrammatic and not to scale. 
     In  FIG. 1 , the system element  1  comprises a suction chamber  2  which is used for generating a suction stream and which is a generally known component, known by a person of ordinary skill in the art. The system element  1  further comprises a transport device  3  that encloses lateral walls of the suction chamber  2 . 
     As shown in  FIG. 1 , the transport device  3  comprises a first roller  4  and a second roller  5 , where the rollers are arranged at opposite lateral surfaces of the suction chamber  2  and contact the respective lateral surface. 
     According to the embodiment, pulleys  6  for driving the rollers  4 ,  5  and thus for driving the system element  1  are arranged on the respective end regions  4   a, b  and  5   a, b  of the first and second rollers  4 ,  5 . The pulley  6  and the rollers  4 ,  5  are firmly connected to an axle  12 , as shown in  FIG. 4 , so that the running belt  7  is not subjected to unnecessary deformation as a result of torque transmission, but may instead carry out its sealing function without hindrance. As an alternative, a drive belt (not shown), may be used and is driven by a motor (not shown) and is connected to the pulley  6 , to drive the running belt  7 , such that a torque acts on the rollers  4 ,  5 , and so that the system element may be moved. 
     According to the embodiment, the suction chamber  2  is supported by the rollers  4 ,  5  such that rotation of the rollers  4 ,  5  may be possible and the suction chamber  2  may be safely held to the rollers  4 ,  5 . 
     According to the embodiment, the running belt  7  is made from a flexible material so that the running belt  7  may carry out its sealing function. As shown in  FIG. 1 , the embodiment comprises two running belts  7   a ,  7   b  that may establish contact with opposite lateral surfaces of the suction chamber  2 , where the lateral surfaces are not the same as the lateral surfaces that are contacted by the rollers  4 ,  5 . 
     As shown in  FIG. 1 , the end regions  4   a ,  5   a  of the rollers  4 ,  5  are connected by way of the running belt  7   a , and the end regions  4   b ,  5   b  of the rollers  4 ,  5  are connected to each other by a separate running belt  7   b . Both belts are examples of a connection element. 
     With reference to  FIGS. 2 and 3 , the function of the system element  1  according to  FIG. 1  is described. 
       FIG. 2  shows a diagrammatic lateral view of the system element, according to  FIG. 1 , in a state in which the suction chamber  2  generates a suction stream, wherein the system element  1  is sucked to a surface  8  of a workpiece  9 . As shown in  FIG. 2 , in this suction state, the flexible running belt  7   b  (and the running belt  7   a  that is not visible in this view) conforms to the curved surface  8  of the workpiece  9 .  FIG. 2  shows guide discs  11  around where the running belt  7   b  has been placed. 
       FIG. 3  shows a front view of the sucked in system element, according to  FIG. 2 . The diagram shows that in the sucked in state, the running belts  7   a, b  may conform with the surface  8  of the workpiece  9 , and that the rollers  4 ,  5  may be made from a correspondingly elastic flexible material. 
       FIG. 4  shows a diagrammatic partial lateral view of a detail of the system element  1  according to  FIG. 1 . 
     As shown in  FIG. 4 , the running belt  7  is placed around a guide disc  11 . The guide disc  11  is connected to an axle  12  which extends from the roller  5  towards the outside. By way of a sliding bearing or ball bearing  13 , a connection  14  is supported by the axle  12 . The connection  14  is preferably rigid and bears or supports the suction chamber (not shown). 
     According to the preferred embodiment, the rigid connection  14  comprises a first part  15 , that extends so as to be substantially parallel in relation to the axle  12  and the roller  5 , and a second part  16  and a third part  17  which extend substantially perpendicularly from the first part  15  in the direction of the axle  12 . The free ends of the first and second parts  16 ,  17  are supported by the axle  12  via the sliding bearings or ball bearings  13 . 
     The first and second parts  16 ,  17  of the connection  14  are spaced apart from each other, and the pulley  6  is arranged between the first part  16  and the second part  17 , as shown in  FIG. 4 . 
     During the transport of the suction chamber  2  over the workpiece  9 , the suction device  2  is supported by the rollers  4 ,  5 . To this effect, the axle bearing  12  of the rollers  4 ,  5  is rigidly connected to the suction chamber  2  as described above. Expediently, attachment of the axle bearing  12  is further to the outside than the position of the running belts  7  such that the axle bearing arrangement may not be in the way of automatic sealing between the running belts  7  and the rollers  4 ,  5 . The rigid connection  14  of the axle bearings  12  and the suction chamber  2  comprises an opening  18 , through which the upper part of the running belts  7  may move. 
     In an inoperative position, e.g. while a transported tool is in operation, attachment of the suction device may also be possible by way of additional suction cups or by way of full contact of the suction device in that the rigid connection to the rollers is undone. 
     Thus, the running belts  7   a ,  7   b , which may serve as connection elements, and the rollers  4 ,  5 , which may serve to generate forward movement of the system element  1 , may conform to the curved surface  8  of the workpiece  9  when the suction chamber  2  generates a suction stream, so that a good negative pressure is generated between the suction chamber  2  and the surface  8  of the workpiece  9 , where negative pressure makes possible reliable adhesion of the system element  1  to the surface  8  of the workpiece  9 . In this way a tool (not shown) that is coupled in any desired manner to the system element may reliably be conveyed to a desired position on the surface of the workpiece  9 , where the tool may be positioned. 
     Although not shown in the figures, a transport system according to the invention may comprise a plurality of system elements  1 . 
     For example, the shape of the suction chamber  2  is not limited to a square or rectangular shape but instead may comprise any form with any number of lateral surfaces, but it may be ensured that each lateral surface is contacted either by a roller or by a running belt so as to ensure that adequate negative pressure is generated for adhesion of the system element  1 . 
     Furthermore, the running belt  7  may also be designed as some other connection element that interconnects the end regions of the rollers and contacts a lateral surface of the suction chamber  2 . In this case, the drive of the system element  1  takes place by applying a torque to any one of the rollers  4 ,  5  (or to both) without the need for pulleys  6 . 
     As an alternative, the running belts  7  may be made from a suitable material and may have a suitable shape so that forward movement of the system element may by said running belts  7  alone, wherein the rollers  4 ,  5  are idle rollers. 
     The system element may be used in many sectors, for example, in aircraft construction, shipbuilding or in any other sectors where a tool has to be reliably transported over a curved surface of a workpiece and has to be positioned thereon, wherein the term “tool” also refers to a component, robot or a workpiece to be transported. 
     Furthermore, the system element may of course also be used on horizontal or flat surfaces. 
     It should also be mentioned that “comprising” does not exclude any other elements or steps, and that “a” or “an” does not exclude a plurality. It should furthermore be noted that characteristics or steps described with reference to one of the above embodiments may also be used in combination with other characteristics or steps of other above-described embodiments. The reference symbols in the claims should not be understood in a restrictive sense. 
     Alternative combinations and variations of the examples provided will become apparent based on this disclosure. It is not possible to provide specific examples for all of the many possible combinations and variations of the embodiments described, but such combinations and variations may be claims that eventually issue. 
     LIST OF REFERENCE CHARACTERS 
     
       
         
               
               
             
           
               
                   
               
             
             
               
                 1 
                 System element 
               
               
                 2 
                 Suction chamber 
               
               
                 3 
                 Transport device 
               
               
                 4 
                 First roller 
               
               
                 5 
                 Second roller 
               
               
                 4a, b 
                 End regions of the roller 4 
               
               
                 5a, b 
                 End regions of the roller 5 
               
               
                 6 
                 Pulley 
               
               
                 7 
                 Running belt 
               
               
                 8 
                 Surface of the workpiece 
               
               
                 9 
                 Workpiece 
               
               
                 10 
                 Surface of the suction chamber 
               
               
                 11 
                 Guide disc 
               
               
                 12 
                 Axle 
               
               
                 13 
                 Sliding bearing/ball bearing 
               
               
                 14 
                 Rigid connection 
               
               
                 15 
                 First part 
               
               
                 16, 17 
                 Second and third part 
               
               
                 18 
                 Opening