Abstract:
A reciprocating abrading, polisher or buffing tool is disclosed in which a counterweight for a shoe adapted for the mounting of an abrading, polishing or buffing member is driven by the shoe for oppositely directed reciprocating movement. Pairs of guides for supporting the shoe and counterweight for reciprocating movement are mounted on a shroud having halves fixed to each other and to depend from a rim of a body of the sander or polisher, so as to permit selective rotational displacements of the shoe and counterweight relative to the body. In one form of the invention employing suction to withdraw dust from adjacent the shoe, the shroud is employed to positionally locate an L-shaped connecting duct relative to a dust discharge opening in the shoe and a dust collecting duct leading to an aspirator.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to improvements in portable abrading, polishing and buffing tools of the type having a counterweight and a sanding, polishing or buffing material supporting shoe supported for oppositely directed reciprocating movements in order to minimize vibrations felt by an operator of the tool. 
     Prior tools of the type described have employed both rotary motors and reciprocating piston type motors, and a suitable transmission permitting both the counterweight and the shoe to be directly coupled to the motor and driven thereby for reciprocating movement. Patents believed representative of prior tools include U.S. Pat. Nos. 2,743,557; 2,830,411; 3,793,781; 4,228,620 and 5,085,012. 
     SUMMARY OF THE INVENTION 
     The present invention relates to portable, reciprocating abrading, polishing or buffing tools employing a counterweight drivingly coupled to a shoe adapted for mounting abrading, polishing or buffing material, such that the counterweight is driven by the shoe for reciprocating movement in a direction opposite to that of the shoe. 
     The shoe and counterweight are supported for reciprocating movement by pairs of guides carried by a shroud fixed to depend from an annular rim defined by the housing of the tool. In a preferred construction, the shroud is defined by shroud halves removably clamped against each other and the annular rim, and the rim and shroud halves are provided with slidably engaging annular ribs and grooves cooperating to support the shroud halves for rotary movement relative to the housing when clamping pressure is removed from the shroud halves. By this arrangement, the direction of reciprocating movement of the shoe and counterweight may be selectively adjusted relative to the housing. 
     In one form of the invention intended for use in the removal of dust created adjacent a workpiece, the shoe is formed with a through dust discharge opening arranged outwardly of the shroud and the shroud is formed with an outer surface arranged to positionally locate a connecting duct relative to the discharge opening and a dust collecting duct leading to an aspirator driven by air exhausted from the tool. 
    
    
     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 taken with the accompanying drawings wherein: 
     FIG. 1 is a side elevational view of an abrading tool in the form of a reciprocating sander incorporating the present invention; 
     FIG. 2 is a front end elevational view thereof; 
     FIG. 3 is a sectional view taken generally along the line 3--3 in FIG. 2; 
     FIG. 4 is a sectional view taken generally along the line 4--4 in FIG. 3; 
     FIG. 5 is a sectional view taken generally along the line 5--5 in FIG. 3; 
     FIG. 6 is a sectional view taken generally along the line 6--6 in FIG. 3; 
     FIG. 7 is a sectional view taken generally along the line 7--7 in FIG. 3; and 
     FIG. 8 is a view similar to FIG. 1, but showing another form of the sander incorporating the present invention. 
    
    
     DETAILED DESCRIPTION 
     The present invention shall for purposes of illustration be described as being incorporated in a pneumatically operated, hand held abrading tool in the form of a reciprocating sander generally designated as 10 and shown in FIGS. 1-3 as including a hollow cast or molded housing or body 12, which defines a chamber 14 having a lower open end bounded by a rim 16, an air inlet or supply conduit 18 and an air outlet or discharge conduit 20. Chamber 14 mounts a pneumatically operated rotary motor 22, which is arranged in communication with the air inlet and discharge conduits and has a rotor 24 supported by bearings 26. Flow of air to motor 22 is controlled by a flow control valve 28 manually operable by a housing mounted lever 30, and air discharge from motor 22 via discharge conduit 20 may be passed through air aspirator mechanism 32. 
     As thus far described, sander 10 is of known construction and reference may be had to U.S. Pat. No. 5,319,888 for a more detailed description of such construction and mode of operation. 
     In accordance with the present invention, rotor 24 is connected to a rotary drive member 34 by a planetary gearing mechanism 36 with such drive member being supported by further bearings 38 for rotation about a first axis 40 shown in FIGS. 5 and 7, and preferably disposed essentially concentrically of rim 16. 
     Unlike the sander described in U.S. Pat. No. 5,319,888, the sander of the present invention is intended to impart reciprocating movements to a sanding device 42, such as may be defined by a flexible pad 44 to which sandpaper, not shown, is suitably affixed. To this end, pad 44 is removably fixed to a shoe 46, which is in turn supported for reciprocating movement by a shroud 48 fixed to rim 16 under the control of drive member 34 drivingly coupled to the shoe by a first coupling means in the form of a pin and slot device 50. Preferably, rim 16 is an annular rim and shroud 48 is formed as a pair of halves 48a and 48b removably and clampingly secured to each other and thus to the rim by clamping fastener screws 48c. Also, it is preferable to provide rim 16 and shroud halves 48a and 48b with a slidably engaging annular rib and groove arrangement 52, which serves to positively position shroud 48 relative to housing 12 in a direction extending lengthwise of axis 40, while permitting rotary adjustment of the shroud and thus shoe 46 relative to the housing as will be described with reference to FIG. 8. 
     Shoe 46 is formed with oppositely facing surfaces 54a and 54b essentially corresponding in size and configuration to pad 44, oppositely facing and parallel side edge surfaces 56a and 56b, and oppositely facing end edge surfaces 58a and 58b. Pad 44 is intended to be removably, clampingly secured to shoe surface 54b by suitable means, such as screws 60, and shoe surface 54a is intended to be disposed in facing relationship to housing 12 and removably supported for reciprocating movement relative thereto by arranging side edge surfaces 56a and 56b in sliding engagement with a first pair of guide means 62a and 62b, which are in the form of a pair of facing grooves defined by a pair of guide plates 64a and 64b suitably fixed to inner surfaces of shroud halves 48a and 48b, respectively. 
     Pin and slot device 50 is shown in FIGS. 3-5 and 7 as including a drive pin 68, which is carried by drive member 34 and disposed eccentrically of and parallel to first axis 40, and a slot 70, which is formed to open through shoe surface 54a and extend transversely of the direction of reciprocating movement of shoe 46. Preferably, pin 68 is fitted with a bearing sleeve 72 serving to reduce friction as the pin moves back and forth within slot 70 to effect reciprocation of shoe 46 as an incident to rotation of drive member 34. 
     In accordance with the present invention, vibrations caused by reciprocating movements of shoe 46 and pad 44 relative to housing 12 is substantially reduced by providing a counterweight 74 driven directly by shoe 46 for reciprocating movements in a direction opposite thereto. Counterweight 74 is formed with oppositely facing surfaces 76a and 76b between which extends a centrally located opening 78 sized to loosely receive drive member 34. A pair of slide plates 80a and 80b, which are suitably fixed to counterweight lower surface 76b, serve to define oppositely facing parallel edge surfaces of counterweight 74 arranged for removable sliding engagement with a second pair of guide means 82a and 82b in the form of a pair of facing grooves or slots defined by guide plates 64a and 64b. 
     A second coupling means is employed to connect shoe 46 to counterweight 74 for effecting reciprocating movement of the counterweight relative to housing 12 in response to reciprocating movement of the shoe. This coupling means is shown in FIGS. 3-6 as including first rack means including a pair of first racks 86,86 carried by counterweight lower surface 76b on opposite sides of through opening 78 in alignment with the direction of reciprocation of counterweight 74; a second rack means including a pair of second racks 88,88 carried by shoe upper surface 54a for alignment with the first racks; and a pair of gear pins 90,90, which have their opposite ends removably, rotatably supported by guide plates 64a and 64b, and are arranged to engage with the first and second racks. 
     As desired, housing 12 may be fitted with differing sizes of counterweights depending on the weights of the shoe, pad and abrasive material intended to be employed. Alternatively, a single size counterweight may be provided and material removed from its upper surface 76a, such as by grinding, as required to match its weight to that of the shoe, pad and abrasive material to be employed. 
     In the form of the invention where air exhausted from motor 22 is passed through aspirator 32 for dust collecting purposes, the aspirator is provided with a dust collecting duct 94 having an upper end 94a exposed to the reduced pressure or vacuum condition created by discharged air passing through the aspirator and a lower end 94b; shoe 46 defines a dust collection passageway 96 arranged to extend from adjacent a point at which dust to be collected is generated to a discharge opening 98 disposed to face towards the aspirator and be arranged outwardly of shroud 48, as best shown in FIG. 3; and an L-shaped connecting duct 102 is provided to connect discharge opening 98 to dust collecting duct 94. Connecting duct 102 is best shown in FIG. 3 as having an upper end or one of its ends 102a sized to be removably, slidably supported by dust collecting duct lower end 94b, a lower or other end 102b arranged for alignment with discharge opening 98 and a follower surface 102c. Engagement of follower surface 102c with shroud guide surface 100 serves to position connecting duct upper end 102a in flow communication with dust collecting duct lower end 94b and to position connecting duct lower end 102b in flow alignment with discharge opening 98 and in a slightly spaced or non-contacting relationship with shoe upper surface 54a peripherally of the discharge opening. As will be apparent from viewing FIG. 3, connecting duct lower end 102b is sized such as to ensure that discharge opening 98 is continuously disposed in flow alignment therewith throughout the range of reciprocating movements of shoe 46. The maintenance of a slight spacing between shoe upper surface 54a and duct lower end 102b allows for the ingress of ambient air directly into the duct lower end and prevents reduced pressure induced clamping of such duct lower end against shoe 46. 
     For the vacuum or dust collecting form of sander 10 illustrated in FIGS. 1-7, it is necessary to maintain the illustrated positional relationship of dust collecting duct 94, connecting duct 102, discharge opening 98 and shroud guide surface 100, and thus the orientation of shoe 46, i.e. the direction of its reciprocating movement, relative to housing 12 cannot be adjusted. 
     As is conventional, pad 44 and the abrasive material carried thereby would typically be provided with passageways, not shown, for placing the interior of shoe 46 in direct flow communication with the surface of a workpiece being sanded. 
     Again referring to FIG. 3, it will be understood that it is preferable to form opposite ends of shroud 48 with transversely extending slots 106a and 106b, which are sized to receive flexible sealing strips 108a and 108b whose free ends are disposed for sliding engagement with shoe upper surface 54a. The seal created by sealing strips 108a and 108b rubbing against shoe surface 54a, and the seal created by sliding engagement of guide plates 64a and 64b with shoe edge surfaces 56a and 56b results in an effective barrier against the passage of dust inwardly of shroud 48. 
     Reference is now made to FIG. 8, wherein a non-vacuum or non-dust collecting type sander is illustrated in which elements thereof similar to those of sander 10 are identified by like primed numerals. In this construction, the absence of previously described dust collecting duct 94, connecting duct 102 and discharge outlet 98 allows the orientation of shoe 46, i.e. the direction of its reciprocating movement relative to housing 12, to be selectively adjusted. This adjustment is effected by the simple operation of loosening screws 48c&#39; sufficiently to permit shroud 48&#39; to be rotated relative to annular rim 16&#39; until a desired orientation of shoe 46&#39; relative to housing 12&#39; is achieved and finally tightening such screws sufficiently to frictionally clamp the shroud to the rim. 
     While the invention has been specifically described for use with a pneumatic motor operated abrading tool in the form of a reciprocating sander, it will be understood that it has utility with sanders employing other suitable types of drive motors, and in similarly constructed buffing or polishing tools, where vibrations are desired to be reduced and/or the orientation of a shoe of the tool is desired to be adjusted relative to its housing.