Patent Publication Number: US-10779698-B2

Title: Gas-assisted scraping tool

Description:
TECHNICAL FIELD 
     This disclosure relates to tools that utilize a compressed gas, and more particularly, to scraping tools that use a compressed gas to disperse material removed by the scraping tool blade. 
     BACKGROUND 
     Scraping tools come in many forms. A common component of most scraping tools is a blade having a sharp scraping edge. The blade may be attached to a handle that may be gripped by one or both hands of a user. The scraping tool blade edge is forced against the surface of a workpiece at an acute angle and reciprocated across the surface. The sharp edge of the blade thus scrapes away unwanted material, which may comprise old paint or varnish, residue, surface oxidation, or surface imperfections in the workpiece material itself. Such unwanted material accumulates as the action of the scraping tool blade continues to generate flakes or particles of the unwanted material being removed. If such accumulated scrapings of material are not removed from the work area, they may foul the area of the workpiece being scraped and reduce the effectiveness of the scraping tool blade in removing additional material. 
     Scraping tools have been developed to address the problem of accumulation of scraped material. Such scraping tools include a connection to a source of gas under pressure, such as pressurized air, that is directed over the surface of the workpiece to blow away the material removed from the workpiece by the scraping tool blade. Some gas-assisted scraping tools are complex in construction, requiring many parts that increase the overall cost of the scraping tool and are prone to corrosion and fouling. Other gas-assisted scraping tools are of a simple design, but do not direct a stream of the pressurized gas over a wide swath of cleared area that matches the area contacted by the full width of the scraping tool blade. 
     Accordingly, there is a need for a gas-assisted scraping tool that is low cost, of simple construction, is rugged, and provides a wide swath of cleared area adjacent the scraping blade edge. 
     SUMMARY 
     The disclosure describes a gas-assisted scraping tool that utilizes a pressurized fluid, which may take the form of a liquid or a compressed gas, such as compressed air, to blow away chips and/or material removed from the surface of the workpiece by the scraping tool. The disclosed scraping tool is of a relatively simple and low cost design, and may be disassembled for cleaning and/or replacement of its constituent parts with a minimum of effort. Further, the disclosed gas-assisted scraping tool includes a diffuser that distributes a stream of compressed gas across the entire width of the scraping tool blade, thus providing an efficient material removal function. 
     In an embodiment, a gas-assisted scraping tool includes a housing having a blade support with a cavity that is connectable to a source of a pressurized gas; a blade attached to and extending forwardly of the blade support; and a diffuser attached to the blade support and spacing the blade from the cavity, the diffuser shaped to direct a stream of the pressurized gas from within the cavity lengthwise along the blade and distribute the pressurized gas transversely across a width of the blade, whereby material loosened by the blade is blown away from an end of the blade by the stream of the pressurized gas. 
     In another embodiment, a gas-assisted scraping tool includes a housing having a blade support, the blade support having a rear wall, a pair of opposing side walls, a top wall, and a front lip, all defining a portion of a cavity that is connectable to a source of a pressurized gas, and together forming a continuous, flat mounting surface; a blade attached to and extending forwardly of the blade support; a flat, plate-shaped diffuser abutting the continuous, flat mounting surface of the blade support; and wherein the diffuser is shaped to direct a stream of the pressurized gas outwardly from the cavity between the blade and the front lip in a lengthwise direction along an adjacent surface of the blade and distribute the compressed gas transversely across a width of the adjacent surface of the blade, whereby material loosened by the blade is blown away from an end of the blade by the compressed gas. 
     In yet another embodiment, a method of making a gas-assisted scraping tool includes forming a housing having a blade support, and forming a cavity in the blade support that is connectable to a source of a compressed gas such that the cavity can be filled with the compressed gas; attaching a blade to the blade support such that the blade extends forwardly of the blade support; and attaching a diffuser to the blade support such that the diffuser or the blade covers the cavity, wherein the diffuser is shaped to direct a stream of the pressurized gas from the cavity lengthwise along the blade and distribute the pressurized gas transversely across a width of the blade, whereby material loosened by the blade is blown away from an end of the blade by the stream of the pressurized gas. 
     Other objects and advantages of the disclosed gas-assisted scraping tool will be apparent from the following description, the accompanying drawings, and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the underside of an embodiment of the disclosed gas-assisted scraping tool; 
         FIG. 2  is a side elevation, in section, of the gas-assisted scraping tool of  FIG. 1 , taken along line  2 - 2  of  FIG. 2 , and showing the retainer plate in section; 
         FIG. 3  is a top plan view of the housing of the gas-assisted scraping tool shown in  FIG. 1 , with the retainer plate and fasteners removed; 
         FIG. 4  is an exploded view showing the components of the gas-assisted scraping tool shown in  FIG. 1 ; 
         FIG. 5  is a top view in perspective of the gas-assisted scraping tool of  FIG. 1 ; 
         FIG. 6  is a perspective view of the underside of another embodiment of the disclosed gas-assisted scraping tool; 
         FIG. 7  is an exploded, perspective view of the embodiment of  FIG. 6 ; 
         FIG. 8  is a side elevation, in section, of the embodiment of  FIG. 6 ; and 
         FIG. 9  is a perspective view of yet another embodiment of the disclosed gas-assisted scraping tool. 
     
    
    
     DETAILED DESCRIPTION 
     As shown in  FIGS. 1, 2, 3, and 4 , in an exemplary embodiment, the gas-assisted scraping tool, generally designated  10 , may include a housing  12  having a blade support  14 . The blade support may have a cavity  16  that is connectable to a source  18  of a pressurized fluid, which may take the form of a gas or a liquid. The source  18  may take the form of a tank of gas or liquid under pressure, an accumulator, and/or a compressor. The gas may include atmospheric air, and/or an inert gas, such as nitrogen. The liquid may be water, water mixed with a soap or cleaning solution, or a solvent. In an exemplary embodiment, the source  18  is pressurized gas at a pressure above atmospheric, and the pressure may be selected or adjusted by a throttle or valve (not shown) by a user of the tool  10  to suit the application. 
     The gas-assisted scraping tool  10  also may include a blade  20  that is attached to and extends forwardly of the blade support  14 . The scraping tool  10  also may include a diffuser  22  that is attached to the blade support  14  and that covers the cavity  16 . The blade  20  and diffuser  22  may be flat and plate shaped, and the diffuser  22  may be shaped to seat upon and cover the cavity  16  and lie flat against the base of the blade, as shown best in  FIG. 2 . 
     As shown in  FIG. 3 , in an embodiment, the cavity  16  may include a rear wall  23 , a pair of opposing side walls  24 ,  26 , a top wall  28 , and a front lip  30 , all of which are formed in the blade support  14 . The opposing side walls  24 ,  26  may diverge outwardly in a downstream direction (i.e., in the direction of arrows A in  FIG. 2 ) on the blade support  14  of the housing  12 . The front lip  30  may extend transversely across the width of the front of the blade support between the opposing side walls  24 ,  26 , and may be integral or unitary with the side walls. In an embodiment, the blade support  14  includes a baffle that reduces airflow out from the cavity  16  across the front lip  30 . The baffle may take the form of a rectilinear raised rib  32  attached to and extending downwardly from the top wall  28  into the cavity  16 . The raised rib  32  may extend between the opposing side walls  24 ,  26 , and may be substantially parallel to the front lip  30  of the blade support  14 . 
     The rear wall  23 , opposing sidewalls  24 ,  26  and the front lip  30  each may include a flat or substantially flat mounting surface segment  34 ,  36 ,  38 , and  40 , respectively. The mounting surface segments  34 - 40  combine to form a continuous, flat mounting surface  42  that engages the diffuser  22 , which in exemplary embodiments is flat and plate-shaped. Thus, the engagement between the diffuser  22  and the continuous, flat mounting surface  42  forms a wall of, and encloses the cavity  16 , such that the cavity forms and acts as a plenum. 
     As shown in  FIG. 4 , the diffuser  22  may form a bottom wall  44  of the cavity  16  when the diffuser  22  is placed against the continuous mounting surface  42  of the blade support  14 . As shown in  FIG. 4 , the diffuser  22  may include a plurality of spaced teeth  46  extending across a forward edge  48  thereof, such that the teeth form gaps  50  therebetween. As shown in  FIG. 2 , the plurality of spaced teeth  46  are positioned between the blade  20  and the front lip  30  such that the gaps  50  ( FIGS. 4 and 5 ) are bounded above and below by the front lip and the blade  20 , respectively, and form a plurality of channels  52  to the ambient from the cavity  16  spaced across the width of the blade that direct streams, which collectively form a continuous stream, of the compressed gas from the cavity lengthwise along the upper surface of the blade, in the direction of arrows A in  FIGS. 2 and 5 . 
     As shown in  FIG. 5 , the channels  52  are spaced transversely across the width of the scraping tool blade  20 . Thus, the channels  52  of the diffuser  22  distribute the streams of the pressurized gas evenly transversely across a width of the blade  20 , whereby material loosened by the blade is blown away from the end of the blade by the stream of the pressurized gas across the entire width of the scraping tool blade. In the embodiment, the baffle  32  may be shaped to form a restriction with the bottom wall  44  of the cavity  16 , which is a surface of the diffuser  22  and is obverse to the surface shown in  FIG. 4 , to reduce airflow from the cavity through the plurality of openings  50  and channels  52  to provide a predetermined amount of air flow across the width of the blade  20 . In an embodiment, the teeth  46  are shaped to terminate rearwardly or inwardly of the forward face of the front lip  30 . 
     As shown in  FIGS. 1, 2, 4, and 5 , the scraping tool  10  may include a retaining plate  56  that releasably clamps the scraping tool blade  20  against the diffuser  22 , and the diffuser to the blade support  14  of the housing  12 . The retaining plate  56  may have a trapezoidal, or generally trapezoidal, shape in plan view that corresponds to the shape of the mounting surface segments  34 ,  36 ,  38 , and  40  of the continuous mounting surface  42 . The shape of the retaining plate  56  is defined by a transverse, squared front wall  95 , diverging side walls  96 ,  97 , and a transverse rear wall  98  that may abut the forward wall  99  of the handle  86 . The top wall  100  of the retaining plate  56  may taper in thickness from the upper surface  102  of the handle  86 . 
     As shown in  FIG. 4 , the blade  20  may be a flat, plate-shaped blade having a straight rear edge  58 , a pair of opposing and diverging side edges  60 ,  62 , and a squared front edge  64 . The rear edge  58  is shaped to abut the straight wall  66  of the housing  12 . The front edge  64 , in other exemplary embodiments, may be curvilinear, such as concave or convex, saw toothed, pointed or chisel shaped, or have an irregular shape. The edge of the front edge  64  may be squared, or may be beveled or sharpened to a knife or chisel edge. In an exemplary embodiment, the opposing side walls  24 ,  26  of the blade support  14  may be shaped to diverge in a forward direction that substantially, or in embodiments exactly, follows the portion of the outer profile of the scraping tool blade  20  that overlies the blade support. Similarly, the outer contour or profile of the retaining plate  56  may be shaped to follow, or substantially follow, the outer profile of the blade support  14 . 
     As shown in  FIGS. 2, 3, and 4 , the top wall  28  of the blade support  14  may include at least one and optionally two cylindrical bosses  66 ,  68  extending into the cavity  16 . The scraping tool  10  also may include at least one and optionally two fasteners  70 ,  72  that attach to the bosses  66 ,  68  to clamp the scraping tool blade  20  and diffuser  22  between the retaining plate  56  and the blade support  14 . The fasteners  70 ,  72  may take the form of screws that are threaded into complementary threaded holes  74 ,  76  formed in the bosses  66 ,  68 , respectively. 
     The screws  70 ,  72  pass through holes  78 ,  79  that are formed in the scraping tool blade  20  and diffuser  22 . The screws  70 ,  72  may be retained within countersunk holes  82 ,  84  formed in the retainer plate  56 . Thus, the blade  20  and diffuser  22  are retained against the blade holder  14  of the housing  12  by the clamping force of the retainer plate  56  against the mounting surface  42  of the blade holder, and by the positive mechanical connection of the screws  70 ,  72  passing through the holes  78 ,  79  of the blade and holes  81 ,  82  of the diffuser  22 . 
     In an exemplary embodiment, the housing  12  may include a handle  86 . The handle  86  may be shaped to be grasped by the hand of a user, and is positioned rearwardly of the blade support  14 . The handle  86  may include a fitting  88 , formed in a rearmost face, that connects to the source  18  of pressurized gas, for example by way of a hose  90 , which in embodiments may include a regulator or valve to control gas pressure delivered to the scraper body  12 . The hose  90  and fitting  88  may take the form of a quick-disconnect engagement, or a threaded bore for a simple male-female threaded connection. The handle  86  may include a channel  92  that connects the fitting  88  to the cavity  16  to convey pressurized gas from the fitting to an opening  94  in the rear wall  23  of the cavity. The handle  86  may be defined by a top surface  102 , bottom surface  103 , rear surface  104  and forward wall  99 . The top surface  102  and bottom surface  103  may be joined by opposing side surfaces  105 ,  106  that may taper in width rearwardly toward rear surface  104 . 
     In an exemplary embodiment, the source of pressurized gas  18  may provide atmospheric air under pressure through hose  90  to the fitting  88  to pressurize the cavity  16  so that gas exits the cavity through the channels  52  formed by the gaps  50  between the teeth  46  of the diffuser  22  and formed by the adjacent and abutting surface of the blade  20  and the front lip  30  of the blade support  14 . In other embodiments, the compressed gas may include an inert gas such as nitrogen or carbon dioxide, or may be in the form of a fluid, such as water, a solvent, such as a petroleum solvent, or a detergent mixture. In still other embodiments, the source of pressurized gas may take the form of steam, so that the gas leaving the cavity  16  in the direction of arrows A in  FIG. 2  may be in the form of steam that may heat and moisten the material being scraped by the blade  20 . 
     A method for making the gas-assisted scraping tool  10  shown in  FIGS. 1-5  may include forming a housing  12  having a blade support  14 , and forming a cavity  16  in the blade support that is connectable to a source of pressurized gas  18 , such that the cavity fills with pressurized gas. The housing  12  may be cast and/or machined from a single billet of material, which may be selected from a metal, such as steel, aluminum, or brass; a polymer, such as nylon; or a composite, such as carbon fiber reinforced plastic (CFRP). A scraping tool blade  20  is attached to the blade support  14  such that the scraping tool blade extends forwardly of the blade support. And finally, a diffuser  22  is attached to the blade support  14  such that the diffuser covers the cavity  16 , wherein the diffuser is shaped to direct a stream of the pressurized gas from the cavity lengthwise along the blade  20  and distribute the pressurized gas transversely across a width of the blade, whereby material loosened by the blade is blown away from an end of the blade by the stream of pressurized gas. 
     The diffuser  22 , which is placed against the continuous mounting surface  42  of the blade support  14 , may be clamped between that supporting surface and the scraping tool blade  20  by the retaining plate  56  which is placed on the scraping tool blade. These components are held clamped together by the fasteners  70 ,  72  which are threaded into the threaded holes  74 ,  76  of the bosses  66 ,  68  extending upwardly from the top wall  28  of the blade support  14 . The gas-assisted scraping tool  10  may be disassembled by removing the fasteners  70 ,  72  from the bosses  66 ,  68 , at which point the retaining plate  56  may be removed and the scraping tool blade  20  and diffuser  22  separated from the blade support  14  of the housing  12 . This ease of disassembly facilitates the replacement of a worn or broken blade  20 , as well as substituting a blade  20  having a different front edge configuration, such as a saw tooth shape, an arcuate shape, a knife edge, and the like. 
     The channels  52  formed by gaps  50  between the teeth  46  of the diffuser  22  direct the pressurized gas from the cavity  16  across the width of the blade  20  evenly, in a lengthwise direction along an adjacent surface of the blade and distribute the compressed gas transversely across a width of the adjacent surface of the blade, whereby material loosened by the blade is blown away from an end of the blade by the compressed gas. The stream of pressurized gas flows in a direction that is substantially parallel to and against an adjacent surface of the blade  20  to disburse material removed from the surface of a workpiece by the blade that otherwise might collect on or adjacent the forward edge  64  of the scraping tool blade. The scraping motion of the disclosed scraping tool  10  may be effected by a user grasping the handle  86  of the housing  12  with their hand or hands and performing the scraping action manually. In other embodiments, the handle  86  may be attached to or integrated with an extended handle (not shown), or may be attached to or integrated with an articulated arm of a robotic device (not shown), where it would function as an end effector. 
     In an exemplary embodiment, the scraping tool  10  is positioned relative to a workpiece such that the channels  52  are on top of the blade  20 , so that the stream of pressurized gas passes along the top of the tool against the upper surface of the blade (i.e., as shown in  FIG. 5 ). However, there may be applications in which it is beneficial to position the tool  10  relative to a work surface such that the channels  52  convey the stream of pressurized gas from the cavity  16  along and under the adjacent surface of the blade  20  (i.e., the tool  10  is inverted, as shown in  FIG. 1 ). 
     Another embodiment of the gas-assisted scraping tool, generally designated  110 , is shown in  FIGS. 6, 7, and 8 . The tool  110  may include a housing  112  having a blade support  114 . The blade support  114  may be cast and/or machined from a solid billet of material and include a cavity  116 , which may be cast or machined into the blade support, that communicates with the source  18  of pressurized gas or liquid  18 . The tool  110  also may include a blade  120  that is attached to and extends forwardly of the blade support  114 . The blade  120  may be flat and plate shaped, having a straight rear edge  158 , a pair of opposing and diverging side edges  160 ,  162 , and a straight front edge  64 . 
     The tool  110  may include a diffuser  122  that is attached to the blade support  114  and that covers the cavity  116 . The diffuser  122  is positioned between the blade  120  and the blade support  114 . The housing  112  may include a retaining plate  156  that clamps the blade  120  against the diffuser  122 , and the diffuser against the blade support  114 . The retaining plate  156  corresponds in width and length dimensions to the blade holder  114 , having a top surface  200 , a beveled front edge  195 , a rear face  198 , opposing sides  199 ,  201  and an interior cavity  197 , which in embodiments may form part of the cavity  116  that receives compressed gas from channel  192 . These components may be held together by retaining screws  170 ,  172 ,  173 , which extend through retaining holes  182 ,  184 ,  185  in the retaining plate  156 , aligned holes  178 ,  179 ,  180  in the blade  120 , aligned holes  181 ,  182 ,  183  in the diffuser  122 , and are threaded into holes  174 ,  176 ,  177  in the blade support  114 . 
     In an embodiment, the cavity  116  may include a rear wall  123 , a pair of opposing side walls  124 ,  126 , a top wall  128 , interior walls  129 ,  131 , and a front lip  130 . The interior walls  129 ,  131  interrupt rear wall  123  at a midpoint of the width of the blade support  114  and define a raised land for the screw hole  176 . The cavity  116  may include a transverse channel  132  that extends parallel to the front lip  130 . The transverse channel  132  may be shallower in depth (i.e., as measured in  FIG. 8 ) than the portion of the cavity  116  defined by the side walls  124 ,  126 , rear wall  123 , and top wall  128 , and thus may provide a restriction or baffle function. The blade support  114  may include a flat, or substantially flat, mounting surface  142  that surrounds the cavity  116 , and in embodiments extends across the entire top surface of the blade support, including the raised land defined by walls  129 ,  131 . 
     In an exemplary embodiment, the diffuser  122  is flat, or substantially flat, and plate shaped, and may form a bottom wall  144  of the cavity  116  when the diffuser is clamped against the continuous mounting surface  142  of the blade support  114  by the blade  120  and retaining plate  156 . The diffuser  122  may include a plurality of spaced teeth  146  extending transversely across a forward edge of the diffuser, such that the teeth form gaps  150  therebetween that extend transversely across the width of the diffuser. In an embodiment, the gaps  150  are evenly shaped and spaced across the width of the diffuser. The diffuser  122  is shaped such that the gaps  150  form a plurality of channels  152  to the ambient from the cavity  116 , so that streams of compressed gas from the cavity travel lengthwise along the blade  120 . 
     The blade support  114  may include a fitting  188 , formed in a side wall  189 , as shown in  FIGS. 6 and 7 , and/or in a bottom wall  191  as shown in  FIG. 8 , of the blade holder, that may be connected to a source  18  of pressurized gas, for example, by way of a hose  190 . The blade holder  114  may include a channel  192  that connects the fitting  188  to the cavity  116  to convey pressurized gas from the fitting to an opening  194  in the rear wall of the cavity. 
       FIG. 9  shows yet another embodiment of the disclosed gas-assisted scraping tool, generally designated  210 . Gas-assisted scraping tool  210  includes a blade support  114 , blade  120 , and retaining plate  156 , which in embodiments are the same described for tool  110  of  FIGS. 6-8 . Diffuser  222  is shaped to cover continuous mounting surface  142 , but includes cutouts  224 ,  226  that are shaped to conform to the rear walls  123 , side walls  124 ,  126 , and interior walls  129 ,  131 . The diffuser  222  also includes a recess  228  bounded by side edge projections  230 ,  232  whose outer edges are aligned with the corresponding end walls  189 ,  196  of the blade support  114 . 
     In an alternate embodiment, blade  120  may be provided with an opening (not shown) that provides communication between interior cavity  197  and cavity  116 , and diffuser  122  may be provided with an opening (not shown) aligned with the blade opening that allows pressurized gas or fluid entering the cavity  116  to flow into and pressurized the interior cavity  197 . Diffuser  122  and blade  120  may be reversed in orientation relative to the blade support  114  from that shown in  FIG. 8  so that gas exits from the interior cavity  197  between the retaining plate  156  and the blade  120 . In such an embodiment, the cavity  116  may be considered to communicate with and include interior cavity  197 . 
     The diffuser  222  is placed beneath the scraper blade  120 , and the diffuser and scraper blade are clamped against the blade holder  114  by the retaining plate  156  and retaining screws  170 ,  172 ,  173 . The screws  170 ,  172 ,  173  pass through holes  182 ,  184 ,  185  in the retaining plate  156 , holes  178 ,  179 ,  180  in scraper blade  120 , holes  181 ,  182 ,  183  in diffuser  222 , and are threaded into holes  174 ,  176 ,  178  of the blade holder  11 . The diffuser  222  spaces the scraper blade  120  from the mounting surface  142  to form a continuous transverse gap  234 , which may be coextensive with the transverse channel  132 , between the portion of the mounting surface formed by the lip  130  and the immediately adjacent portion of the underside  244  of the scraper blade  120 . Unlike the embodiments  10 ,  110  of  FIGS. 1-8 , the rear portion  244  of the blade  120  of scraper  210  itself forms a wall of the cavity  116  of the housing  112 , and is spaced from the mounting surface  142  by the diffuser  222  to form the gap  234 . 
     Compressed air or other gas entering the cavity  116  from the source  18  exits the cavity in a continuous, transverse sheet of air or gas along the scraper blade  120  toward the front edge  64 . The absence of spaced teeth in the diffuser, such as spaced teeth  46 ,  146  of the embodiments of  FIGS. 1-8 , may provide a wider stream of air or gas along the blade  120 . The gas-assisted scraping tools  110 ,  210  may be attached to a wand, pole, or other component to facilitate use by hand, or may be attached to a robotic arm as an end effector. The scraping tools  110 ,  210  function in a manner similar to the gas-assisted scraping tool  10  of  FIGS. 1-5 , namely, compressed gas is conveyed from a source of compressed gas  18  to the cavity  116  formed in the blade support  114 , where it exits through channels  152  or transverse gap  234  formed by the diffuser  122 ,  222 , respectively, and travels along the underside  244  of the length of the blade  120  (in the orientation shown in  FIG. 9 ) toward the front edge  164 , where it acts to blow away chips and other debris that may be loosened by the scraper blade  120 . 
     While the forms of apparatus and methods disclosed and described herein constitute preferred embodiments of the gas-assisted scraping tool, it is to be understood that the invention is not limited to these precise structures and methods, and that changes may be made therein without departing from the scope of the invention.