Abstract:
To prepare a surface with a surface preparation device, an apparatus including a mount, a platform, and a suspension system is utilized. The mount supports and positions the surface preparation device. The platform moves the apparatus. The suspension system is disposed between the mount and the platform and controls an amount of force pressing the mount towards the surface. The suspension system and mount are operable to position the surface preparation device in contact with the surface.

Description:
FIELD OF THE INVENTION 
   The present invention generally relates to a surface preparation device and method. More particularly, the present invention pertains to a device and method for preparing a surface by contact with the surface. 
   BACKGROUND OF THE INVENTION 
   In various manufacturing and construction industries, items are produced that require surface preparation by contact with the surface. These surface preparations may include grinding, sanding, polishing, and the like. Often, these surface preparations are performed by hand, that is, by a user or human using a surface preparation device. If this surface preparation is performed by hand, it may be advantageous to position the item relatively below the shoulders of the user and with the item&#39;s surface facing preferably upwardly. In this manner, the user may maintain a relatively comfortable position and at least to some extent enjoy the assistance of gravity forcing the tool downward against the surface. Unfortunately, some items are too large, awkward, fragile and/or otherwise impractical to manipulate into a position with the surface facing upwardly. For example, in the case of a large relatively flat object having two sides, such as an airplane wing, it may be different to rotate the wing so that the normally downward-facing bottom becomes upward facing. 
   In such situations, the user may be required to work overhead with the surface preparation device from below the item, and the user may need to assume a potentially uncomfortable position in order to accomplish the surface preparation task. Also, it may be difficult to apply the correct amount of pressure against the surface being treated since gravity is urging the device away from the surface. Similarly, even when preparing a surface generally perpendicular to the user or angled towards the user, such as for example: a wall; an underside of a plane or boat; and the like, the weight of the preparation device may tend to fatigue the user. 
   Accordingly, it is desirable to provide a method and apparatus capable of overcoming the disadvantages described herein at least to some extent. 
   SUMMARY OF THE INVENTION 
   The foregoing needs are met, to a great extent, by the present invention, wherein in one respect a surfacing device and method of preparing a surface is provided. 
   An embodiment of the present invention pertains to an apparatus for preparing a surface with a surface preparation device. This apparatus includes a mount that supports the surface preparation device, a platform, and a suspension system. The suspension system applies a force pressing the mount towards the surface. The suspension system is disposed between the mount and the platform and is operable to position the surface preparation device in contact with the surface. 
   Another embodiment of the present invention relates to an apparatus for preparing a surface above a floor with a surfacing device. This apparatus includes a means for modulating a height of the surfacing device in response to a change in a height of the surface relative to the floor. In addition, the apparatus includes a means for following a contour of the surface with the surfacing device and a means for controlling an amount of force exerted by the surfacing device upon the surface. 
   Yet another embodiment of the present invention pertains to a method of preparing a surface above a floor with a surfacing device. In this method, a height of the surfacing device is modulated in response to a change in a height of the surface relative to the floor, a contour of the surface is followed with the surfacing device, and an amount of force exerted by the surfacing device upon the surface is controlled. 
   Yet another embodiment of the present invention pertains to a method of preparing a surface above a floor with a surfacing device. In this method, a height of the surfacing device is modulated with a suspension system in response to a change in a height of the surface relative to the floor. In addition, a contour of the surface is followed with the surfacing device and an amount of force exerted by the surfacing device upon the surface is controlled with the suspension system. 
   There has thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto. 
   In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting. 
   As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side view of a surface preparation device according to an embodiment of the invention. 
       FIG. 2  is a perspective view of the surface preparation device of  FIG. 1 . 
       FIG. 3  is an exploded view of a surfacing head suitable for use in the device of  FIG. 1 . 
       FIG. 4  is a flow diagram illustrating steps that are followed in accordance with an embodiment of the invention. 
   

   DETAILED DESCRIPTION 
   The present invention provides a surface preparation device and method. In one example of a preferred embodiment, the surface to be prepared is the underside of an airplane wing. Such a surface presents a number of difficulties with regard to surfacing. Primary among these difficulties is the overhead nature of the surface. To overcome this and other difficulties, in some embodiments, the surface preparation device includes a surfacing head mechanically secured to a platform, preferably a mobile platform. The surfacing head includes a surfacing device such as, for example, a sander, a grinder, or the like. This surfacing device is pivotally secured on the surfacing head via a gimbaled and counterpoised arrangement. In this manner, the contour of the surface being prepared is followed by the surfacing device. The surface preparation device also includes a suspension system that urges the surfacing head against the undersurface of the wing. By virtue of these features, an operator is freed from having to manually apply the supporting and positioning forces for work overhead. 
   The suspension system is further operable for maintaining a substantially constant force of the surfacing head against the surface being prepared. This substantially constant force is maintained by an actuator operable to modulate the distance between the mobile platform and the surfacing head. In a specific example, the actuator includes a pneumatic cylinder operable to modulate the distance between the mobile platform and the surfacing head by telescoping a member of the suspension system relative to another member of the suspension system. To minimize the possibility of adverse consequences of working in explosive environments, compressed air is utilized to power the various components of the surface preparation device in at least one embodiment of the invention. Examples of other suitable power supplies include at least, electric, hydraulic, and the like. 
   Another embodiment in accordance with the present invention provides a method of preparing a surface. In this method, the surfacing head is selected based upon the surfacing procedure to be performed. For example, a sanding head is selected to perform a sanding or abrading procedure, a grinding head is selected to perform a grinding procedure, a cutting head is selected to perform a cutting or milling procedure, and the like. The surfacing head is evaluated and/or prepared to perform the surfacing procedure. For example, sandpaper attached to the sanding head is evaluated and replaced if found to be excessively worn. The surfacing head is attached to the mobile platform. The surfacing head is introduced to the surface to be prepared. The surface preparation device is activated and the surface is prepared. 
   Preferred embodiments of the invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. As shown in  FIG. 1 , a surface preparation device, or surfacer  10 , is configured to prepare a surface  12  and move across a floor  14 . The surfacer  10  includes a surfacing head  16 , a suspension system  18 , and a mobile platform  20 . The suspension system  18  includes a pneumatic cylinder  22  to vary the length of the suspension system  18  while exerting an amount of force upon the surfacing head  16 . The force may be adjustable by adjusting the pneumatic pressure. Once, adjusted, it is preferably held substantially constant. In this manner, the surfacing head  16  exerts a substantially constant amount of force upon the surface  12 . Pressurized air or gas to operate the pneumatic cylinder  22  is supplied via an air line  24 . This air line  24  is connected to a pressure supply such as, for example, a compressor, pressurized air tank, or the like. 
   To control the air pressure delivered to the pneumatic cylinder  22  and thus the force applied by the pneumatic cylinder  22 , the surfacer  10  includes a regulator  26 . The regulator  26  is configured to modulate fluid pressure supplied by the air line  24 . The regulator  26  may be manually adjustable and/or electronically controlled. Suitable examples of regulators include at least, piston-type regulators, diaphragm-type regulators, proportional air valves, and the like. However, the regulator  26  is optional and, for example, when a pressure supply configured to suitably regulate fluid pressure is utilized, the regulator  26  may be omitted. To facilitate maintaining a set pressure within the pneumatic cylinder  22 , a vent  28  is configured to allow air to escape. This vent  28  includes any suitable hole or pressure regulated valve operable to relieve pressure from the pneumatic cylinder  22 . 
   The suspension system  18  further includes a first support member  30  and a second support member  32 . These support members  30  and  32  are slidably attached to one another. For example, the second support member  32  may have an outer surface which is slightly smaller than an inside surface of the first support member  30 . In this manner, the support members  30  and  32  form a telescoping extension or armature, the length of which is modulated by the operation of the pneumatic cylinder  22 . In another example, the capabilities of the pneumatic cylinder  22  are subsumed within the support members  30  and  32 . For example, in an embodiment of the invention, the support members  30  and  32  include a linear thruster or other such device. Suitable examples of linear thrusters are manufactured by Bimba of Monee, Ill. USA. In addition, the first support member  30  is pivotally attached to the mobile platform  20  and the second support member  32  is attached to the surfacing head  16 . With regard to the attachment to the mobile platform  20 , the first support member  30  is mounted to a base plate  34 . This base plate  34  is secured to the mobile platform  20  via a bolt  36 , or other such structure, to form an axis A about which the base plate  34  rotates. In this manner, the suspension system  18  and the surfacing head  16  are configured to rotate in relation to the mobile platform  20 . The amount of rotation is preferably limited to plus and minus 60° from a central axis of the mobile platform  20 . The first support member  30  is secured to the base plate  34  via a bolt  38 , or other such structure, to form an axis B upon which the suspension system  18  pivots. In this manner, the suspension system  18  and the surfacing head  16  are configured to pivot relative to the base plate  34 . The degree of pivot is controlled via a stop. For example, the amount of pivot may preferably be limited to approximately plus and minus 20° of center. 
   The mobile platform  20  preferably utilizes a suitable number of wheels, treads, and/or the like. In the example shown in  FIG. 1 , the mobile platform  20  includes four wheels  40   a – 40   d . At least one wheel  40   a – 40   d  is attached to and driven by a motor  42  via a power transmission  44 . This motor  42  is preferably powered pneumatically. The mobile platform  20  further includes a steering mechanism  46  for modulating the rotational plane of at least one of the wheels  40   a – 40   d . For example, the steering mechanism  46  includes a pneumatic cylinder  48  attached to the wheels  40   a  and  40   b  via a linkage for turning the rotational plane of the wheels  40   a  and  40   b.    
     FIG. 2  is a perspective illustration of the surfacer  10 . As shown in  FIG. 2 , the surfacer  10  further includes a handle bar  52  mounted to the first support member  30  via a strut  54 . This handle bar  52  includes a pair of handles  56   a  and  56   b . The handle bar  52  further includes a control panel  58 . The control panel  58  includes a variety of controls such as, for example, the regulator  26 , a forward/reverse toggle  60 , a steering knob  62 , and the like. 
   The handles  56   a  and  56   b  and the control panel  58  allow an operator to guide the surfacer  10 . For example, the operator may walk beside the surfacer  10  and guide the surfacer  10  as the surface  12  is prepared. In addition, the operator may adjust the angle and orientation at which the surfacing head  16  addresses the surface  12  by applying force to the handles  56   a  and  56   b . Any force applied by the operator is magnified via the leverage provided by the strut  54  and the handle bar  52  configuration. 
     FIG. 3  is an exploded view of the surfacing head  16  suitable for use with the surfacer  10  as illustrated in  FIG. 1 . As shown in  FIG. 3 , the surfacing head  16  includes a surfacing device  64  supported within a gimbal mechanism  66 . Suitable types of surfacing devices include, for example, sanders, grinders, polishers, brushers, buffers, milling machines, boring devices, and the like. In a particular example, the surfacing device  64  is a pneumatically driven sander having a sanding pad  68  driven in an oscillating motion by a motor  70  and powered via an air line  72 . The surfacing device  64  is secured within the gimbal mechanism via the clamping action of a gimbal ring  74 . This gimbal ring  74  includes a pair of gimbal ring members  76   a  and  76   b . The gimbal ring  74  is fastened together and securely clamped to the motor  70  by a pair of machine bolts  78   a  and  78   b  and a mating pair of nuts  80   a  and  80   b.    
   The gimbal ring  74  includes a pair of trunnions  82   a  and  82   b . These trunnions  82   a  and  82   b  are configured to mate with a pair of trunnion seats  84   a  and  84   b . In this manner, the surfacing device  64  is pivotable about an axis C. The trunnion seats  84   a  and  84   b  are respectively located within a front member  86  and a rear member  88  of a gimbal frame  90 . This gimbal frame  90  further includes a pair of side members  92   a  and  92   b . The gimbal frame  90  is fastened together via a plurality of machine bolts configured to mate with a plurality of threaded bores machined into the front and rear members  86  and  88 . The gimbal frame  90  is attached to the suspension system  18  via a gimbal support  94 . This gimbal support  94  is attached to the gimbal frame by a pair of machine bolts  96   a  and  96   b  that form an axis D about which the gimbal frame  90  and surfacing device  64  rotate. 
     FIG. 4  is a flow diagram of a method  100  according to an embodiment of the invention. In the method  100 , the surfacer  10  is made ready to prepare a particular surface  12 , such as an underside of an airplane wing having a series of protruding rivet heads. To machine these protruding rivet heads more flush with the surface  12 , a sander may be utilized as the surfacing device  64 . At step  102 , the surfacing head is evaluated. For example, if it is determined that the surfacing device  64  is not the proper device for the particular task, the correct surfacing device may be installed at step  104 . In addition, if at step  102  it is determined that the sanding pad  68  has incorrect and/or worn sanding medium, the sanding pad  68  may be replaced at step  104 . Following the step  102  or  104 , the tool height is evaluated at step  106 . 
   At step  106 , the tool height is evaluated. For example, if at step  106  it is determined that the height of the surface  12  is outside of telescoping range of the suspension system  18 , at step  108 , the height is adjusted, and if needed, an extension maybe added and/or a suspension system  18  having a different telescoping range may be installed. In this manner, the surfacer  10  is operable to accommodate relatively large deviations in the height of the surface  12  above the floor  14 . Following the step  106  or  108 , the surfacer  10  is optionally turned on. 
   At step  110 , the surfacer  10  is optionally turned on. For example, if the surfacer  10  is pneumatically powered, the air line  24  may be attached to the control panel  58 . However, if the surfacer  10  is already powered, the step  110  is omitted. 
   At step  112 , the surface  12  is prepared. For example, the surfacer  10  is positioned at or near one end of the series of protruding rivet heads, the surfacing device  64  is engaged and introduced to the surface  12 , and the surfacer  10  is controlled to travel along the series of protruding rivet heads. To introduce the surfacing device  64  to the surface  12 , the pneumatic cylinder  22  is pressurized by the regulated air supply. The suspension system  18  modulates the height of the surfacing device  64  to automatically adjust for changes in the height of the surface  12  above the floor  14 . In addition, the force exerted by the surfacing device  64  upon the surface  12  is automatically maintained at a relatively constant amount by maintaining a relatively constant air pressure within the pneumatic cylinder  22 . 
   To control the speed and/or direction of travel, the operator manipulates the forward/reverse toggle  60 . The travel direction is further modulated by manipulation of the steering knob  62 . Once the speed and direction are set, the surfacer  10  is operable to automatically maintain this set speed and direction. 
   In general, it is advantageous that the plane of the surface  12  and the floor  14  are parallel. However, it is an advantage of various embodiments of the invention that the surfacer  10  is operable to accommodate for relatively large deviations from parallel by rotating the suspension system  18  and surfacing head  16  about the axis A and/or the axis B, as appropriate. In this manner, the suspension system is operable to dispose the surfacing device  64  at a nominal angle to the surface  12 . In addition, the gimbal mechanism  66  is operable to automatically adjust for relatively minor deviations of the surface  12 . 
   In another embodiment of the invention, one or more of the axis A to D are modulated by one or more respective actuators. For example, a controller determines a contour path to follow and controls the surfacing head  16  to follow this contour path via the action of the actuators. More particularly the actuators are modulated via one or more respective proportional air valves that are controlled by the controller. To determine the contour path, the controller may utilize a computer readable representation of the surface to be prepared. For example, a computer aided design (CAD) drawing is accessed by the controller and the contour path is determined based on this CAD drawing. In addition or alternatively, a sensor such as a feeler gauge, for example, may sense the contour of the surface and relay measurements to the controller. In response to these measurements, the controller determines the contour path. Following the completion of the surfacing task at step  112 , it is determined, at step  114 , whether another surfacing task is to be performed. 
   At step  114  it is determined whether another surfacing task is to be performed. If it is determined that an additional surfacing procedure is to be performed, the surfacing device  64  is evaluated at step  102 . If it is determined that no additional surfacing procedures currently exist, the surfacer  10  may placed idle or be shut down. 
   The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.