Abrasive finishing tool having a rotary pneumatic motor

Abstract

A pneumatic abrading or polishing tool is provided that includes a motor having a rotor, a motor housing, a carrier part having a shaft and a key extending from the shaft, and an abrading or polishing head attached to the carrier part. The motor housing contains a progressive exhaust passage including a preliminary portion that relieves at least some of the air pressure inside the motor before the exhaust passage fully opens.

1 . An abrasive finishing tool having a rotary pneumatic motor comprising:
 a motor having a rotor and a housing containing the rotor;   a carrier part engaging the rotor; and   an abrading head attached to the carrier part,   wherein the housing comprises an inlet passage configured to introduce air into the motor and a progressive exhaust passage having a preliminary portion configured to release air from the motor prior to the release of air through a secondary portion greater in cross section than the preliminary portion.   
   
   
       2 . The abrasive finishing tool of  claim 1 , wherein the preliminary portion of the progressive exhaust passage comprises a preliminary slot and the secondary portion of the progressive exhaust passage comprises a secondary slot offset from the preliminary slot. 
   
   
       3 . The abrasive finishing tool of  claim 2  wherein the preliminary slot overlaps the secondary slot. 
   
   
       4 . The abrasive finishing tool of  claim 2  wherein the preliminary slot opens before the secondary slot opens and closes after the secondary slot opens. 
   
   
       5 . The abrasive finishing tool of  claim 1 , wherein the housing further comprises a recess formed in an outer surface of the housing and encompassing at least a portion of the progressive exhaust passage. 
   
   
       6 . The abrasive finishing tool of  claim 1 , wherein the rotor comprises a keyway that mates with a key on the carrier part to engage the rotor with the carrier part. 
   
   
       7 . The abrasive finishing tool of  claim 1 , wherein the housing is made of steel. 
   
   
       8 . The abrasive finishing tool of  claim 1 , wherein the tool is a pneumatic orbital abrading or polishing tool. 
   
   
       9 . The abrasive finishing tool of  claim 1 , wherein the rotor comprises an outer body and a central core. 
   
   
       10 . The abrasive finishing tool of  claim 9 , wherein the outer body and central core comprise mating protrusions that lock the outer body to the central core to prevent relative rotation therebetween. 
   
   
       11 . The abrasive finishing tool of  claim 9 , wherein the central core comprises steel. 
   
   
       12 . The abrasive finishing tool of  claim 1 , wherein the preliminary portion comprises a first portion of a first slot and the secondary portion comprises a second slot and a second portion of the first slot, such that the preliminary portion has a cross-sectional area that is less than the cross-sectional area of the secondary portion. 
   
   
       13 . An abrasive finishing tool having a rotary pneumatic motor comprising:
 an abrading or polishing surface;   a carrier part connected to the abrading or polishing surface;   a stator having an inner surface defining a motor cavity; and   a rotor contained within the motor cavity and engaging the carrier part in a driving relationship,   the stator comprising an inlet opening for introducing an expandable fluid into the motor cavity, and further comprising a progressive exhaust channel having a preliminary portion that releases at least some of the fluid inside the motor cavity before the progressive exhaust channel fully opens.   
   
   
       14 . The abrasive finishing tool of  claim 13 , wherein the progressive exhaust channel has a secondary portion configured to fully open the progressive exhaust channel, and wherein the preliminary portion has a cross-sectional area that is less than a cross-sectional area of the secondary portion. 
   
   
       15 . The abrasive finishing tool of  claim 13 , wherein the progressive exhaust channel comprises a plurality of offset slots. 
   
   
       16 . The abrasive finishing tool of  claim 13 , wherein the stator further comprises a recess formed in an outer surface of the stator and overlapping with at least a portion of the progressive exhaust channel. 
   
   
       17 . The abrasive finishing tool of  claim 13 , wherein the preliminary portion comprises a preliminary slot and the progressive exhaust channel comprises a secondary slot offset from the preliminary slot. 
   
   
       18 . The abrasive finishing tool of  claim 13 , wherein the rotor comprises an outer body surrounding a central core having a keyway that engages a key on the carrier part. 
   
   
       19 . An abrasive finishing tool having a rotary pneumatic motor comprising:
 a motor comprising a rotor configured to rotate inside a motor housing;   a carrier part engaged with the rotor;   an abrasive surface attached to the carrier part;   the motor housing comprising an inlet and a progressive exhaust, and the progressive exhaust comprising a preliminary portion and a secondary portion, the preliminary portion being configured to release air from the motor before the secondary portion opens.   
   
   
       20 . The abrasive finishing tool of  claim 19  wherein the preliminary portion is smaller in cross section than the secondary portion.