Abrading tool suction system

A portable abrading tool having a shoe which is driven relative to a carrying body by a contained air motor to perform an abrading operation, and in which a flow of air discharged from the motor passes through a conduit structure projecting from an end wall of the tool body, with the body having a flange projecting therefrom beneath the conduit structure and carrying at its underside a seal part slidably engaging the shoe structure to deliver air and abraded particles from a passage in the shoe through the seal part and upwardly through a connected secondary conduit for delivery into the primary stream from the motor, in an aspirator relation inducing the secondary flow by the energy of the primary stream.

BACKGROUND OF THE INVENTION 
This invention relates to improved portable power driven abrading tools, 
such as sanders, of a type including an abrading shoe power driven 
relative to a carrying body to cause a sheet of sandpaper or other 
abrading material to perform an abrading operation on a workpiece. 
In U.S. Pat. No. 3,785,092, there has been shown an abrading tool in which 
an aspirator is energized by a primary flow of air discharged from an air 
motor of a tool to induce a secondary flow of air and abraded particles 
from the vicinity of a workpiece through passages in the abrading shoe and 
into a conduit leading to a dust collection bag. A later U.S. Pat., No. 
3,932,963, shows a similar dust collection system in a sander of a type in 
which the abrading shoe reciprocates in a straight line relative to the 
carrying body. 
SUMMARY OF THE INVENTION 
The present invention relates to an improved arrangement for conducting the 
primary and secondary flows of air, in a tool of the above discussed 
general type, into contact with one another at an aspirator location, in a 
manner attaining optimum confinement and control of the two streams, and 
avoiding development of leaks in either system even after very extended 
use of the tool. Certain features of the invention relate particularly to 
the manner in which the secondary flow of air and particles is conducted 
to the body of the tool from the relatively movable abrading shoe, in 
tightly sealed relation, and in a manner occupying a minimum of space. 
In an arrangement embodying the invention, the body of the tool has an end 
surface from which there projects a conduit structure through which the 
primary flow of air discharged from the air motor of the device passes. 
Beneath the location of this conduit structure, the body of the tool has a 
flange which projects in generally the same direction as the conduit 
structure and is received above the abrading shoe. A seal part carried at 
the underside of the flange slidably engages the shoe in a relation 
conducting air from a passage or passages in the shoe through the seal 
part to a tube which extends upwardly to the first mentioned conduit 
structure, with an aspirator being provided at the juncture of this tube 
and the conduit structure for inducing the secondary flow of air and 
particles from the shoe in response to movement of the primary flow of 
air. The tube extending upwardly from the seal part is longitudinally 
extensible, desirably being a short length of corrugated flexible hose, 
and may extend upwardly through an opening in the flange and be connected 
at its lower end in fluid tight relation to the seal part and at its upper 
end in fluid tight relation to the conduit structure. The seal part at the 
underside of the flange is free for upward and downward movement relative 
to the flange to form an effective sliding contact seal with the shoe, and 
is preferably yieldingly urged downwardly against the shoe by spring means 
interposed vertically between the flange and seal part.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The portable sanding tool illustrated at 10 in FIG. 1 includes a body 11 
adapted to be held by two handles 12 and 13, and to the underside of which 
there is mounted a shoe structure 14 which is power driven to reciprocate 
in a straight line relative to body 11 and along the front to rear axis of 
the device represented at 15. The motor 16 for reciprocating the shoe is 
contained within body 11, and typically includes a double ended piston 
illustrated somewhat diagrammatically at 17 to which compressed air is 
delivered from a source 18, under the control of a trigger actuated valve 
19 and an automatic reversing valve 119 operated by the piston and acting 
to alternately admit compressed air to the two cylinder chambers 20 and 21 
at opposite ends of the double ended piston. A reciprocating mechanism of 
this type is disclosed in the above mentioned prior U.S. Pat. No. 
3,932,963, and will not be described in further detail in the present 
application. 
The abrading shoe assembly 14 carries a sheet of sandpaper 22 at its 
underside, which is retained at its opposite ends by two spring clips 23. 
The shoe assembly may include a rigid essentially flat metal part 24 
extending along the underside of body 11 and appropriately guided for only 
the desired straight line reciprocating movement by two retaining plates 
25 extending along opposite sides of the body and having vertical portions 
26 secured by screws 27 to the body, with inturned lower horizontal 
portions 28 of plates 25 extending beneath and slidably contacting the 
under surface of plate 24 to confine it slidably at the underside of the 
body. The shoe assembly 14 also includes a removable pad strucure 29 which 
may consist of an upper rigid metal plate 30 and a cushion 31 adhered to 
the underside thereof, with this two piece pad structure being secured by 
screws 32 to the underside of plate 24. Passages are formed in pad 31 to 
conduct air and abraded particles from the workpiece 34 through the 
interior of the rubber pad 31 to the locations of two vertically aligned 
openings 35 and 36 formed in plates 30 and 24 respectively near the rear 
end of the tool. More particularly, these passages within pad 31 may form 
a number of openings 138 in the bottom surface of the pad communicating 
with registering openings 137 in the sandpaper sheet 22, at a number of 
locations spaced across the horizontal extent of the cushion and sandpaper 
sheet, with these various openings 138 extending upwardly to a location 
near the plate 30 and there leading into or merging with a passage 33 
which extends along the underside of plate 30 to the location of apertures 
35 and 36. The two plates 24 and 30 are in direct contact with one another 
entirely about the locations of these apertures, to form a seal between 
the parts and prevent loss of vacuum at that location. 
The cylinder bore 21 at the rear end of piston 17 (right end as viewed in 
FIG. 1) is closed by an end part 37 of the body. More particularly, this 
end part has a vertical upstanding portion 38, which is disposed 
transversely of the main front to rear axis 15 of the tool, and axis 39 of 
the piston, and which has a planar rear end surface 40 also disposed 
transversely of those axes. At the lower end of this portion 38, the part 
37 has a flange 41 which extends horizontally and projects in a rearward 
direction beyond the plane of surface 40. The compressed air which is 
discharged from motor 16 within the body, after driving piston 17, flows 
to the rear end of the body through a passage 42 in the body which 
communicates with an aperture 43 in plate 38 for conducting the air, still 
under substantial super-atmospheric pressure, to the plane of the rear 
face 40. From this aperture, the pressurized air flows into a conduit or 
tube 43, whose forward end 44 is rigidly secured to and carried by a 
mounting plate 45 secured by screws 46 to end wall portion 38 of part 37. 
Mounting plate 45 may be flat except at the location of a rearwardly 
bulged or deformed region 47, which is shaped to communicate with both the 
aperture 43 and opening 48 in plate 45 leading into the forward end of 
tube 43. Plate 45 is in tight sealed engagement with rear surface 40 of 
end wall 38 of the body continuously about the location of bulge 47 and 
the communicating apertures 43 and 48, to form a seal between the parts at 
that location, and if desired may have an appropriate gasket between these 
elements for enhancing the seal. 
The tube 43 may be angled slightly upwardly as seen in FIG. 3, and may be 
formed of simple straight cylindrical metal tubing having its forward end 
flattened to the essentially rectangular configuration illustrated in FIG. 
8. A short metal tube 49 projects downwardly from the lower wall 50 of the 
rectangular portion of tube 43, near plate 45, to pass air and abraded 
particles from the shoe upwardly through a circular opening 51 in wall 50 
into to the interior of tube 43. To attain an aspirator or ejector action, 
the primary flow of air from the motor is initially confined above a 
deflecting wall or plate 52, which extends across the width of the 
rectangular portion of tube 43 and is brazed to the opposite sides 
thereof, and which is inclined upwardly as seen in FIG. 3 to require that 
all of the air from the motor move along the upper side of plate 52 to a 
location 53 at which the air discharges rapidly rearwardly past a rear 
transverse edge 54 of plate 52 at a location above and slightly beyond the 
mild point of opening 51. As will be understood, this primary flow of air 
discharging rapidly rearwardly at 53 induces a secondary flow of air 
abraded particles upwardly through tube 49, by aspirator action, so that 
these two streams of air then intermix and flow rearwardly together 
through tube 43 and ultimately through a flexible hose 55 into a porous 
dust collection bag 56 or other dust collection chamber. 
At its underside, flange 41 contains a rectangular recess 57, having an 
upper horizontal wall 58, a transverse vertical end wall 59, and two 
opposite parallel side walls 60. Confined within this recess, there is 
provided a seal element 61, which is externally of a rectangular 
configuration to fit closely within recess 57, while being free for very 
limited and slight upward and downward movement relative to the flange 41. 
At opposite sides of recess 57 and part 61, two elongated parallel bearing 
strips or elements 62 are interposed vertically between flange 41 and the 
upper planar surface 63 of shoe plate 24, with these bearing elements 
typically being formed of an appropriate resinous plastic material and 
being located in fixed position relative to part 37 and the remainder of 
the tool body 11 by projections 64 formed integrally with bearing elements 
62 and extending upwardly into mating recesses 65 formed in flange 41 and 
the main portion of the body. An additional pair of bearing strips similar 
to elements 62 may be provided at the forward end of the tool for 
assisting in slidably guiding the shoe for its reciprocating movement at 
that location. The seal plate 61 is yieldingly urged downwardly against 
upper surface 63 of plate 24 by a pair of light coil springs 66 whose 
lower portions are received and confined within recesses 67 formed in the 
upper surface of part 61, and whose upper ends bear upwardly against top 
wall 58 of recess 57 in flange 41. Two of the screws 27 which secure the 
two shoe retaining plates 25 on the opposite sides of the body may extend 
through side portions of the end part 37 and at their ends 68 project into 
notches 69 formed in the opposite sides of part 61 in an interfitting 
relation preventing movement of part 61 relative to flange 41 in a 
direction parallel to the front to rear axis 15 of the tool. 
As seen in FIG. 5, the seal part 61 has at its underside a recess 70, which 
may be elongated in a front to rear direction to always communicate with 
aperture 36 in the engaged plate 24, and thereby receive air and abraded 
particles through that aperture from the shoe. In all positions of the 
shoe, the horizontal planar undersurface 71 of part 61 contacts the upper 
surface of part 24 entirely about aperture 36, to form an effective 
airtight seal between the relatively movable parts at that location. 
The upper wall 72 of part 61 contains a circular aperture 73 defined by an 
annular inwardly projecting rib or edge 74. A flexible tube or hose 75 
connects into this opening 73, and has at its lower end an external 
annular groove 76 receiving edge 74 in a closely interfitting relation 
forming a fluid tight seal between the parts at that location. The tube 75 
is desirably formed of an appropriate flexible elastomeric material, such 
as neopreme rubber, and above the location of the part 61 this tube 
projects upwardly through a circular opening 77 formed in the top part of 
flange 41. At its upper end, tube 75 is received tightly about the rigid 
short tube 49 projecting downwardly from conduit 43. To form an effective 
fluidtight seal at that location, the upper portion of the elastomeric 
tube 75 has an internal annular rib 78, which is of a normal diameter 
slightly less than the external diameter of tube 49 to fit tightly 
thereon. Vertically between its upper and lower portions, the hose or tube 
75 has an intermediate portion with annular corrugations or ribs 79 giving 
the tube a capacity for very substantial axial or vertical extensibility 
or contractability, so that the lower end of this tube and the connected 
part 61 may move slightly upwardly and downwardly relative to flange 41 
and the upper conduit structure 43 to always assure maintenance of a close 
sliding engagement between seal part 61 and the upper surface of shoe 
plate 24. The seal part 61 is desirably rigid, and may be formed of 
appropriate resinous plastic material capable of withstanding wear and 
maintaining the seal after long use. 
During use of the tool, compressed air is fed continuously from source 18 
to motor 16, causing piston 17, acting through an appropriate gear 
mechanism, to reciprocate shoe 14 in opposite directions along axis 15. 
The still pressurized air discharged from the motor flows through aperture 
43 in the rear end wall 38 of the body, and then flows along the upper 
side of deflector 52 to discharge rearwardly at 53 and induce a secondary 
flow of air through passages 33, 137, 138 and 33 in the sandpaper sheet 
and shoe assembly 14 and through apertures 35 and 36 in plates 30 and 24 
into the recess 70 formed in the underside of seal part 61. From this 
recess, the secondary flow of air and abraded particles carried thereby 
flow upwardly through tube 75 and the connected short tube 49 into conduit 
43 for intermixture with the primary flow of air and delivery therewith to 
bag 56, through whose pores the air flows to atmosphere while the dust is 
trapped therein. 
While a certain specific embodiment of the present invention has been 
disclosed as typical, the invention is of course not limited to this 
particular form, but rather is applicable broadly to all such variations 
as fall within the scope of the appended claims.