Abstract:
A head for an orbital abrading machine comprising a housing, a shroud including inner and outer portions, defining a chamber between the inner and outer portions, a drive means for driving an abrading pad, the drive means at least partially enclosed by the housing and the shroud, wherein the drive means produces an exhaust which is directly vented into the chamber without leaving the head, and wherein the chamber includes at least one opening for directing the exhaust toward the abrading pad for cooling the pad with the exhaust.

Description:
FIELD OF THE INVENTION 
     The invention broadly relates to abrading devices, more specifically to pneumatically-powered random orbital devices, and even more particularly to a pneumatically-powered random orbital buffer having a front exhaust. 
     BACKGROUND OF THE INVENTION 
     Random orbital buffing devices are well known in the art. They are used to polish and finish various surfaces without the drawbacks inherent to rotary-type buffing devices. For example, a random orbital buffer may be used to polish a coat of paint on a new automobile. Random orbital buffing devices are commonly pneumatically-powered. After being used to power the device, the compressed air or gas must be exhausted from the device. One problem common to pneumatic devices is that the exhausting air may produce a large amount of noise, which is undesirable for the user of the device. 
     For example, abrading tool  10  is shown in  FIGS. 1A and 1B . Tool  10  includes head  12 , which houses a drive means for driving abrasive pad  14 . The drive means may be, for example, a drive means according to U.S. Pat. No. 6,206,771 (Lehman) or U.S. Pat. No. 4,854,085 (Huber et al.), which patents are incorporated herein by reference. Head  12  is affixed to handle portion  16 , which includes trigger mechanism  18  for controlling the operation of tool  10 . Port  20  is located at the back of the handle portion for coupling the tool to a pneumatic power source, such as a pressurized air tank. Shroud  22  is included to at least partially contain the drive means. Hang ring  24  may be included to provide a convenient means for storing the device when not in use, such as from a hook. 
     Many devices incorporate mufflers to reduce the noise produced by the exhausting air. Traditionally, these mufflers increase the overall size of the device. To reduce the negative effects that this extra size has on the device&#39;s usability, these mufflers are commonly placed in or attached to the device&#39;s handle, since there is no room to accommodate a muffler in the head portion of the tool proximate the drive means. The channel from the coupling port (port  20 ) for the input air is frequently in the handle for the same reason, leading to a common design where the input and exhaust air lines are coaxial or parallel to each other in the handle of the device. That is, separate input and exhaust channels are both included in the handle. 
     For example, muffler  26  is included at the rear of tool  10  to muffle the exhaust of the device. This embodiment results in the exhaust air being vented from the rear of the device, near the connector for the input air. This embodiment adds complexity to the device in the form of a second air line that runs the length of the device between the muffler and the outlet of the drive means. Additionally, a constant current of air is exhausted near the user while the device is in use. 
     An alternative to this embodiment is included in some grinding devices, which involves venting the exhaust air from the front of the device, onto the abrading pad. Directly exhausting the drive means onto the abrading pad advantageously provides cooling of the pad. Additionally, two separate lines or channels are not required in the handle portion, reducing the complexity of the handle. Also, this eliminates the need to include a muffler, which, in addition to the lack of two channels in the handle, enables more design choices in handle shape and size. 
     However, internal space is very limited in the head of these tools, resulting in front-exhaust tools which do not include mufflers. For grinding operations, muffling the exhaust is not a necessity, due to the inherent loudness of grinding. However, muffling is vital for buffing tools to reduce the noise of the tool. Thus, front-exhausting tools tend to be much louder than rear-exhausting tools. Some embodiments attempt to combine the benefits of the front-exhausting and rear-exhausting embodiments by piping the exhaust air from the muffler at the rear of the handle of the device with an exterior line to carry the exhaust back to the front of the device, where it is exhausted onto the pad. This embodiment adds the extra complexity and size for the exterior exhaust line. 
     A final problem common to pneumatically-powered buffing devices, and buffing devices generally, is that heat created by the buffing action can damage the surface that is being polished. To prevent the build-up of excess heat, buffing devices are usually limited in speed, or users must operate the devices carefully to ensure particular portions of the surface are not overworked. These limitations reduce the effectiveness of the device, increasing the time needed to polish the surface. 
     As can be derived from the variety of devices and methods directed at effectively exhausting pneumatically-powered buffing devices, many means have been contemplated to accomplish the desired end, i.e., preventing the exhausting air from interfering with the buffing action of the device. Heretofore, tradeoffs between noise, device design, preservation of the surface to be polished, and user comfort were required. Thus, there is a long-felt need for a pneumatically-powered buffing device that minimizes exhaust noise and accidental damage to the surface to be polished, while preventing the device&#39;s exhaust structures from interfering with the timely and efficient operation of the device. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention broadly comprises a head for an orbital abrading machine including a housing, a shroud including inner and outer portions, defining a chamber between the inner and outer portions, a drive means for driving an abrading pad, the drive means at least partially enclosed by the housing and the shroud, wherein the drive means produces an exhaust which is directly vented into the chamber without leaving the head, and wherein the chamber includes at least one opening for directing the exhaust toward the abrading pad for cooling the pad with the exhaust. 
     In one embodiment, the drive means comprises a pneumatically-powered rotor. In one embodiment, the head further includes an exhaust cavity for receiving the exhaust from the drive means, the exhaust cavity in pneumatic communication with the chamber for enabling the exhaust to flow from the exhaust cavity and into the chamber. In one embodiment, the inner and outer shroud portions are engaged against the housing about an orifice with a first seal and a second seal, respectively, wherein the orifice provides the pneumatic communication between the exhaust cavity and the chamber, for preventing leakage of the exhaust as the exhaust flows from the exhaust cavity through the orifice into the chamber. In one embodiment, the drive means receives a pneumatic input, the pneumatic input sealed from the exhaust except for a path through the drive means. In one embodiment, muffling material is contained within the chamber for muffling the exhaust. In one embodiment, the drive means is secured at least partially within the housing with a lock ring, wherein a spacer is provided with the lock ring for creating a gap, the gap enabling pneumatic communication between the exhaust cavity and the chamber. 
     The current invention also broadly comprises an abrading tool including a head according to the above; a handle secured to the head, the handle including a port for coupling the abrading tool to a source for powering the drive means. In one embodiment, the abrading tool is pneumatically-powered. In one embodiment, the abrading tool is a random orbital buffer. In one embodiment, the chamber includes muffling material for enabling the shroud to muffle the exhaust. 
     These and other objects and advantages of the present invention will be readily appreciable from the following description of preferred embodiments of the invention and from the accompanying drawings and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The nature and mode of operation of the present invention will now be more fully described in the following detailed description of the invention taken with the accompanying drawing figures, in which: 
         FIG. 1A  is a side view of a prior art abrading tool; 
         FIG. 1B  is a top view of the prior art abrading tool shown in  FIG. 1 ; 
         FIG. 2  is a cross-sectional view of a head for an abrading tool according to the current invention; 
         FIG. 3  is an exploded view of the head shown in  FIG. 2 ; 
         FIG. 4  is a cross-sectional view of a drive assembly shown in  FIG. 3 ; 
         FIG. 5  is an exploded view of the drive assembly shown in  FIG. 4 ; 
         FIG. 6  is a perspective view of a front bearing plate of the drive assembly of  FIGS. 4 and 5 ; and, 
         FIGS. 7 and 8  are perspective views of a cylinder of the drive assembly of  FIGS. 4 and 5 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements of the invention. While the present invention is described with respect to what is presently considered to be the preferred aspects, it is to be understood that the invention as claimed is not limited to the disclosed aspects. 
     Furthermore, it is understood that this invention is not limited to the particular methodology, materials and modifications described and as such may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to limit the scope of the present invention, which is limited only by the appended claims. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs. It should be appreciated that the term “device” is synonymous with terms such as “tool”, “machine”, etc., and such terms may be used interchangeably as appearing in the specification and claims. Additionally, the term “buffer,” “buffing device,” and the like may be used interchangeably. Furthermore, “abrasive pad” or “abrading pad” may be used to refer to any polishing, buffing, abrading, or other pad suitable for such orbital tools. Although any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the invention, the preferred methods, devices, and materials are now described. 
     Referring now to the figures,  FIGS. 2 and 3  show buffer head  100 . Head  100  is generally formed by housing  102 , which contains drive assembly  104 . Head  100  is arranged to directly vent the exhaust from drive assembly  104  onto abrasive or buffing pad  105 . Since head  100  is arranged to be held by a user during an abrading operation, grip cover  103  may be included to provide a more comfortable gripping surface for the user. Head  100  may also include hang ring  107 , similar to hang ring  24 , discussed above. 
     In the shown embodiment, drive assembly  104  is arranged to enable head  100  to be used for random orbital abrading. For example, drive assembly  104  could generally refer to any suitable drive means for an abrading device, such as taught in the aforementioned &#39;771 or &#39;085 patents, which describe random orbital abrading devices. In the preferred embodiment, drive assembly  104  is regulated by a valve mechanism in a handle portion of a tool. For example, head  100  could affix to any suitable handle known in the art. As a specific example, head  100  could replace head  12  as shown in  FIGS. 1A and 1B , affixing to handle  16 , and powered by a pneumatic source coupled to the buffer via inlet  20  and regulated via trigger mechanism  18  which controls the pneumatic input to the drive means. Advantageously, head  100  would not require rear muffler  26 , as discussed below. 
     One embodiment of drive assembly  104  is shown in  FIGS. 4 and 5 . In the shown embodiment, the drive assembly comprises rotor  106  having vanes  108 . The rotor and vanes are housed within cylinder  110  between front and rear bearing plates  112  and  114 , respectively. Pin  116  locks the front and rear bearing plates to cylinder  110 . The rotor is rotatable about shaft  118 , with shaft  118  engaged with bearings  120  and  122 , which bearings sit in front and rear bearing plates  112  and  114 , respectively. On one end of shaft  118  is counterbalance  124  for enabling random orbital movement, as described. Bearing  126  is sealed adjacent counterbalance  124  near the end of shaft  118  via v-ring  128  and snap ring  130 . Shaft  132  engages in bearing  126 , and is operatively arranged to connect to a buffer pad, such as buffer pad  105 . Lock ring  134  is provided to secure the drive assembly in housing  102 . Spacer  136  is included to create gap  138  between lock ring  134  and front bearing plate  112 . 
     As shown generally in  FIGS. 2 and 3 , drive assembly  104  is locked into housing  102  via lock ring  134 . In the shown embodiment, lock ring  134  threadingly engages with interior threading on housing  102  for locking drive assembly  104  in housing  102 . A shroud is formed by inner and outer shroud portions  140  and  142 , engaged with housing  102 . The inner and outer shroud portions form a shroud chamber  141 . The shroud generally surrounds counterbalance  124  and second shaft  132  near the end of shaft  118 . Outer shroud portion  140  engages with o-ring  144  against lip  146  of housing  102 , and inner shroud portion  142  engages with o-ring  148  against lip  150  of housing  102 . It should be appreciated that the o-rings could be replaced by any other suitable sealing means known in the art for preventing leakage of the exhaust as it travels through head  100 . A least one aperture  152  is included between lips  146  and  150 . In the shown embodiment, aperture  152  is included in groove  154 , between the lips. Groove  154  enables o-ring  144  to expand as the o-ring is moved into engagement with lip  146 , without risk of damaging the o-ring. That is, if groove  154  were not formed between the lips, then a portion of o-ring  144  would likely expand into aperture  152  as the o-ring passes over the aperture, and this portion would like be clipped or sheared off as the o-ring is forced into final engagement with the housing. Since the o-rings prevent leakage of air as it is exhausted out the front of the buffer, it is important that the o-rings are not damaged during assembly. 
     Muffling material  156  is included between the inner and outer shroud portions. In one embodiment, the muffling material is a strip of felt. By including muffling material  156  in the gap formed between the inner and outer shroud portions, the shroud effectively acts as a muffler for the buffer. Previously, as discussed above, muffler were included at the far opposite end of the handle from the buffer head, and the handle accordingly required two sealed channels so that the handle could both receive the pneumatic input and expel the exhaust. Thus, if head  100  is utilized, a muffler is not required at the opposite end of the buffing tool. For example, muffler  26  would not be required in tool  10  if head  12  were replaced with head  100 . Additionally, since only one chamber is required in the handle, the arrangement of the handle can be greatly simplified. 
     Front bearing plate  112  is shown in more detail in  FIG. 6 . Plate  112  includes annular projection  158 , in which bearing  120  is to be seated. Shaft  118  is insertable through bore  160  for rotatable engagement with bearing  120 . Plate  112  also includes cut  162  in flange  163 . Cylinder  110 , shown in more detail in  FIGS. 7 and 8 , includes cut  164  which corresponds to cut  162  in front edge or rim  166 . Conversely, the opposite rim, rear rim  168  provides a constant diameter about the cylinder and does not include a cut. During operation of a tool including head  100 , a pneumatic input (e.g., pressurized air) is fed into drive assembly  104 , which is housed within cylinder  110 , via inlet  170 . The air is exhausted through outlets  172 . Dividing area  174  is at a common diameter with rear rim  168  and the uncut portion of front rim  166  for separating the inlet from the outlet (a similar dividing area is included on the opposite side of the Figures, hidden from view). That is, the housing preferably has an inner diameter which corresponds to the outer diameter of the cylinder for sealing the pneumatic input between rims  166  and  168  in recessed area  176  proximate inlet  170 . The exhaust is expelled from outlets  172  into recessed area  178 , which is bounded on one side by rim  168 . Recessed area  178  generally defines an exhaust cavity between housing  102 , the body of cylinder  110 , and rim  168 . The exhaust is free to exit the housing via cut  164  in front rim  166 . Pin  116  is insertable through bore  180  for engagement with a corresponding bore in rear bearing plate  114 , and partial bore in plate  112  (hidden from view in  FIG. 4 ). 
     The assembly of head  100  can be best appreciated by referring again to  FIGS. 2 and 3 . Grip cover  103  engages over housing  102 . Hang ring  107  clips onto the housing and is held in place due to lip  146 . O-ring  144  seals outer portion  140  of the shroud against lip  146  of the housing. Muffling material  156  is engaged between outer portion  140  and inner portion  142  of the shroud. O-ring  148  seals inner portion  142  of the shroud against lip  150  of the housing, containing muffling material  156  in chamber  141  formed between the outer and inner portions of the shroud. Orifice  152  is included to provide pneumatic communication between cavity  178  and chamber  141  for enabling the exhaust to flow from the cavity to the chamber. Screws  182  secure inner shroud portion  142  to housing  102  via bores  184 . In addition to friction between outer shroud portion  140  and housing  102 , the outer shroud portion is also supported by projections  143  of inner shroud portion  142 . Lock ring  134  is included to lock the top portion of drive assembly  104  within housing  102 , with the bottom portion of the drive assembly surrounded by the shroud. Abrasive pad  105  secures to shaft  132 , which is freely rotatable about a second axis, assisted by bearing  126 . 
     Thus, it can be seen that a path can be traced throughout head  100  which enables the exhaust to be expelled directly on the abrasive pad. Specifically, air or some other operating fluid is supplied to head  100  via a port in a handle, such as port  20  in handle  16 . The operating fluid then powers the rotor to rotate drive assembly  104  about shaft  118 . The operating fluid is exhausted via outlets  172  into exhaust cavity  178  between cylinder  110  and the interior of housing  102 . Cuts  162  and  164  enable the exhaust to flow out of exhaust cavity  178  and into shroud chamber  141 . Specifically, in the shown embodiment, spacer  136  between lock ring  134  and plate  112  creates gap  138 , which aligns with holes  152  in housing  102 . Holes  152  align with outer and inner shroud portions  140  and  142  so that the exhaust enters shroud cavity  141 . That is, the exhaust flows through the channel created by cuts  162  and  164  into gap  138 , and from gap  138  through holes  152  into chamber  141 . O-rings  144  and  148  seal above and below holes  152  to prevent leakage of the exhaust. The exhaust then exits shroud chamber  141  via holes  186  in the inner shroud portion or through slots  145  formed between projections  143  and the outer shroud portion. 
     Accordingly, the exhaust is directly vented onto the abrasive pad for improved cooling of the pad during operation. By directly, it is meant that the exhaust is contained in the head and must only travel through the head, and not back through the handle. Advantageously, this enables increased buffing speed and buffer pad lifespan, decreased buffing time and a reduced occurrence of imperfections caused on the buffing surface due to overheating of the pad. The shown arrangement also reduces the required complexity of a handle for a tool using head  100 , since the exhaust no longer needs to travel back through the handle, eliminating the need for a rear muffler (e.g. muffler  26 ). Thus, the above described embodiment enables the shroud to not only protect and contain the rotating components of the drive assembly (counterbalance  124  particularly), but to also muffle the exhaust as it passes through the head to cool the buffing pad. 
     Thus, it is seen that the objects of the present invention are efficiently obtained, although modifications and changes to the invention should be readily apparent to those having ordinary skill in the art, which modifications are intended to be within the spirit and scope of the invention as claimed. It also is understood that the foregoing description is illustrative of the present invention and should not be considered as limiting. Therefore, other embodiments of the present invention are possible without departing from the spirit and scope of the present invention.