CA1161647A - Portable electrically energized surface finishing tool - Google Patents

Abstract

IMPROVED PORTABLE ELECTRICALLY ENERGIZED
SURFACE FINISHING TOOL

ABSTRACT OF THE DISCLOSURE

An improved, portable, electrically energized surface finishing tool for use with peripherally acting finishing devices and for use with planar finishing devices is dis-closed.

Description

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This is a divisional of Canadian Patent Application Serial No. 343~820, filed January 16th, 1980.
BACKGROUND OF THE INVENTION

Field of the Invention This invention ~'elates to surface finis'hing tools. The invention relates more particularly to an im;proved, portable hand held electrically energized surfac finishing tool.

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Description of the Prior Art Among the ~arious surface finishing operations, those typically performed by tradesmen, craftsmen and homeowner~
include rotary finishing with peripherally acting finishing de-vices, such as wire wheel brushes, flexible ~lap sanding wheels, flexible drum sander~, and cotton buffing wheels. Surface finishing is also practiced utilizing,for example.sanding ~iscs and polishing bonnets. In the la~ter case, a relakively larger rotary surface performs the finishing.
These finishing devices have in the past been mounted on an output spindle of a stationery drive, or alternat.ively, they have been rendered portable as accessory devices for mounting in a portab~e, electric, power drill chuck or in a portable finishin~ tool. The drill mounted accessories have exhibited various deficiencies including poor handling performance since the use of the accessory i5 auxiliary to the principal design for axial drilling with a mounted drill bit chuck. Overall handling of the tool is relatively poor because of a relatively large overhang of the accessory device with respect to the axls of the ~rill chuck. The resultan Eorces acting on the user have a ~ency to ~atigue ~he u~. From a performance viewpoint, the ~inishing characteri6tic~ are relatively poor since ~he speed-tor~ue ~har~ctaristic of thedevio3 is not p3r~cularl~ selected to 6~7 satisfactorily power a variety of surface finishing devices.
Moreover, the use of these auxiliary devices with elec~ric drills is done in the absence of safety guards. Some portable power tools have been designed to provide or sanding or for polishing but such tools, which are dedicated to finishing in a plane, provide a direct drive which increases the weight and cost of the finishing tool. Some of these deficiencies can be corrected by mounting the device on a stationary motor but the application is then limited to those jobs which can be hand held.

SUMMARY OF T~E INVENTION

Accordingly, it is an object of this invention to provide an improved drive arrangement for a portable, hand held electrically powered, surface finishing tool.
Another ~bj~ct of the invention is to provide an improved drive arrangement for a surface finishing tool which is adapted for finishing with peripheral type finishing devices.
The above noted parent application describes and claims portable, electrically energized surface finishing tool which is adapted to be hand held by a user and comprises an elongated tool body having a length and distal first and second opposite ends. A tool support handle is positioned adjacent a first end of the tool and a support spindle which is adapted to - receive a peripherally acting surface inishing tool is positioned adjacent the second opposite end of the tool. The support handle and the spindle are mutually orientated for providing that the spindle extends horizontally and trans-versely to the tool body length when the support handle i~
positioned vertically. A guard means is positioned between the spindle and the support handle and is configured to inhibit , ::_ '"~ .
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~63~6~7 the projection of particles from the second relatively forward end of the tool body to the first relatively rearward end at which position a user is located. Ease of use and balance is imparted to the tool by positioning an electric drive motox armatuxe shaft at a location intermediate the first and second ends and extending from a side of the tool opposite to the side from which the spindle extends. The armature shaft extends transversely with respect to the length of the tool.
The tool body comprises an elongated frame member and first I0 and second housing members which enclose a portion of the frame member. A means is provided for rotatably mounting the spindle to the frame member at the second end thereof and for mounting the electric motor to the frame member at a position intermediate the first and second ends. The housing members are intercoupled and mounted to the frame member and form a saw grip support handle at the first end of the tool.
A second hand gripping means is also provided and is positioned near the first end of the tool and extends in a transverse direction with respect to the length of the tool at a loca tion opposite the spindle. A means including a belt drive is provided for coupling rotary motion from the armature shaft - to the spindle. An adjusta~le spindle bearing block is also provided for adjusting the tension of the drive belt.
The present invention is particularly related to the drive coupling systems for the tool. Accordingly, the invention of the present divisional provides an improved arrangement for coupling-rotary motion between an armature shaft of an electric motor and a body to be rotated comprising:
(a) an electric motor having an armature including electrical windings formed thereon, said windings having end segments thereof; ~b) said armature having an electrically conductive, rotary shaft including teeth formed along a length thereof;

(c) a sleeve of electrical insulating material positioned about said shaft between said winding end segments and said shaft and insulating said ~inaings from said shaft; (d) said sleeve including an inner surface having teeth formed therein for engaging said shaft teeth and causing sai.d sleeve to rotate with said shaft; (e) said sleeve having an edge surface thereof extending in a transverse direction to a length of said shaft; (f) an elongated, toothed drive belt having an edge thereof; and (g) said drive belt positioned in engage-ment with said shaft teeth and having said belt edge injuxtaposed relationship with said sleeve edge surface.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and features of the invention will become apparent with reference to the following specifica-. tion and to the drawings wherein:
Figure 1 is a left hand perspective view of the surface finishing tool of this invention;
Figure 2 is a right hand perspective of the finishing tool of Figure l;
Figure 3 is an exploded perspective view of the finishing tool of Figure l;
Figure 4 is a side eilevation view of the finishing tool of Figure l;
Figure 5 is a sectional view taken along line 5-5 of - Figure 4;
Figure 6 is an enlarged ~iew of an eccentrically mounted spindle taken along the line of 6-6 of Figure 5;
Figure 7 is a view taken along the line 7-~ of Figure 5;
30Figure 8 is an enlarged view of a motor cooling fan and armature shaft taken along the line 8-8 of Figure 5;
Figure 9 is a view taken along lines 9-9 of Figure 5;
Figure 10 i5 a ~ectional view taken along line 10-10 of Figure 5;

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Figure 11 is an enlarged fragmentary, partly broken away, partly in section, view of the drive belt and armature shaft of Figure 5;
Figure 12 is a fragmentary sido view of the surface finishing device of Figure 1 illustrating alterna~ive use of a surface finishing device; and, Figure 13 is a f~agmentary view taken a.Long line 13-13.

DETAILE3 bEscRIpTIoN

Referring now to the drawings and particularly to Figures 1, 2 and 3, the hand/held portable, electrically ener~ized surface finishing tool body 20 is shown. ~he tool body is elongated having a handle gripping segrnent 36 at a first end 37 thereof and a spindle 30 at a second,relatively forward end 31 thereof. The tool includes an elongated frame member 22 (Fig. 3), a housing 24 formed by housing members 26 and 28, the tool spindle 30 which is ro~ably mounted to the fra~e member 22, an electric drive motor 29 having an armature 32 and a coupling means referenced generally as 34 for impar~ing ro~ary motion from the motor armature 32 to the spindle 30. ~he finishin~ tool ~0 is conveniently gripped with one hand at the saw gripped shaped handle segment 36 and at a tubular shaped relatively forward positioned gripping member 38 with the other hand. Electrical energy i5 applied to the finishing tool via a line cord 40 which is coupled to the base 42 of the saw qrip section 36. Electrical energy i~ applied to the motor by a finger activated trigger control 6witch 44`. Electrical power is continuously applied and the ~witch 44 retained in a retracted pOsitiDn by a lock button A rotary peripherally actin~3devioe 48 is mounted to the drive spindle 30 and iB ~ecured thereto by a retaining nut 50. The toDl 20 is . _ 5 _ . . .. . . .. ~ .. . . . .

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particularly useful with fini~hing devices which provide a finishing operation at an edge or near a periphery of the accessor ;
such as the sanding flap whePl ~8 illustrated in the drawings as wela ~s by wire brush wheels, buffing wheel, ~sanding drums, etc.
A particular form of ~a~ding flap wheel i~ described in greater detail in Canadian Patent Application NoO 434,818 filed Janua~y 16, 1980, and which is~assigned to the ~ssignee of this invention. ~s illustra~ed in the drawings, the flap wheel includes A genêrally cylindrically shaped hous~ng from which a plurality of radially extending flexible abrasive strips backed by a resilient support means is provided. A guard means 62 is provided positioned between the s~indle 30 and handle 36 for inhibiting projection of particl~ and protecting the rearwardly positioned user from materials which may be deflected as a result of the finishing operation. The particular arrangement of the rotary accessQry, the drive motor, the hand grip means and the guard provide for a convenient and easily handled and balanced tool which provides edge finishing or alternatively, surface finishing as described hereinafter with respect to the Figures 12 and 13.
The frame support member 22 is an elongated body extending in a direction 52 (Fig. 3) and is adapted to support at first and second spaced apart locations, the transversely extending t~ol spindle 30 and the transversely extending motor armature 32 .
~rame support me~ber 22 inc~udes a generally planar shaped spindle support ~egment 54 having an ~perture 55 formed therein and throug h which the ~pindle 30 extends and is su~orted ~y a hus~ing as des~ribed he~einafter. A motor bearing su~port segment 56 of the membcr 22 i~ pro~ided having a generally spider sha~ed segment 58 for re~eiving an~ ~upporting a bearing for the armature ~;haft of the ~ture 32. The motor bearing support segment of the frame mem~er 22 and tool support ~egment 54 are intercoupled by a longitudinally extending ribbed coupling segment 60. A guard member or shroud 62 comprises an arcuate segmen~ which extends transversely to the leng~h of the rame member ~2 and extends for an arcuate distance about the spindle 30 for shielding the user from particles and material which are projected by the finishing device ~8 which rot~tes in the clcckwise direction 64 as illustrated in Figure 3.
Disc sh~ mDunting p~ 63 and 65 tFig. 4) are fon~ in~ally with the frame 22 and provide for ~tationary mounting of the tool 20. The pads 63 and 65 abut generally rectangular shaped bosses 67 and 69 which receive nuts 71 and 73, re~pectively.
Apertures 75 and.77 formed respectively in the pads 63 and 65 align with the nuts 71 and 73. The housing member 28 along with the bosses 67 and 69 and the pads 63 and 65 captivate the nuts 71 and 73. These nuts receive and engage mounting screws 79 and 81 which engage and mount the tool to a mounting means, not illustratedO A mounting means which comprises bracket for example supports the tool 20 and mounts it to a work bench, a vice grip jaw, or other desired support. The ~eight of the finishing tool 20 is kept low and its use facilitated by fabricating the frame member 22 of a durable lightweight rigid material. In a particular embodiment, the frame member 22 i formed of aluminum and the spindle support segment 54, the m~tor bearing support segment 56, the guard segment 62 and the longi~udinally ext2nding ribbed coupling ~egment 60 ~re integrally formed.
Mounting and support of the tool spindle 30 is illustrated in Figures 5, 6 and 7. As shown in Figure 5, the spindle ~upport _ 7 - .
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segment 54 i~ludes a raised hub 66 having a bore 68 f~rmed therein. A bearing block 70 having a bore 72 formed therein is positioned in the apexture 6B. The block supports ~ bearing such as a bushing 74 formed of bronze, for example, which is seated in the bore 72; The bushing 74 receives a segment of the tool spindle 30. A lip 76 ~f the bushing engages a flange shoulder 78 formed on the spindle thereby limiting axial movement of the spindle and provides a thrust bearing for planar type devices~ The bearing block 70 includes shoulders 80 and 82 (Figure 6~ each having arcuate formed slots 84 and 86 respec-tively formed therein. The bearing block i~ secured to the spindle support segment 54 by screws 88 and 90 which extend through the slots 84 and 86 respectively and engage internally ~hreaded bores 92 and 94 formed in the hub 66. As illustrated in Figure 6, an axis 96 of ~he spindle 30 and its ~ushing 74 and bore 72 are eccentrically located with respect to a central axis 98 of the bearing block 70. This eccentricity is establis~
by forming the bore 72 in the bearing block having an axis ooLnciding with the axis of the bushing and the spindle 30 and eccentric with the central axis 98 of the bearing block 70.
As indicated hereinafter, the bearing block is adjusted to provide belt tensiening of a drive means. Adjustm~nt i5 affected by l~osening the screws B8 and 90 and rotating the bearing block until desired tension is establish~d.
; A drive means for coupling rotary energy from the armature 32 ~f the electric m~tor includes a drive pulley 110 formed of a p~lymer plastic for ex~mple, a toothed drive timing belt 112, and drive teeth 114 formed in the armature driv~ shaft 116 ~Figuxe 11). The pulley 110 includes (Figure 7) a t~othed outer periphery 118 whi~h engages drive teeth 120 on the timing belt 112. A hub 122 i~ po6itioned in a centrally located cavity 124 on the pulley 110. The hub 122 which is press fitted ~o a ~egment 126 o the spindle 30 includes a plurality of radially .. . ..

extendi.ng, peripheral arc shaped segments 128 which extend ir.to the body of the pull~y and transmi~ torque. rrhe hub is formed of metal and is integrally for~,ed with the pulley.
The motor 29 includes the rotatable armature 32 and a stationary field assembly including a magnetic core 130 and field windings 133. ~he core 130 is cen~rally located within a generally cylindrically shaped field case 132 by radially extending shoulders 134 and is secured in position by elongated rivets 136 and 138 which extend through the field core 130.
The armature shaft 116 issupported at one end by a bushing 140 which is captivated at one end of the field case 132. An opposite end of the armature shaft 116 is supported by a ball bearing assembly 142. The ball bearing assembly 142 is positioned and seated in an electrically insulating bearing support 144, which is seated in the centrally located spider shaped segment 58 of the motor bearing support segment 56 of frame assembly 22. A cup shaped body 146 formed of rubber, for example, is positioned between the ball bearing assembly 142 and the ball bearing support 144 for vibration dampening and to take up manufacturing tolerances.
The armature 32 requires a predetermined length of insulation extending from the armature core to accommodate end turn segments of the armature winding at the end of the armature core. In addition, the armature shaft 116 is cut to provide teeth 114 which engage the belt 112. The cutting o~ such teeth generally requires additional, non-useful shaft length in order to provide for runout of the teeth cutting tool.
Further, to~thed belts 112 require an adjacent, rotating, beveled ~urface. These various requirements are met and the ~haf~ length i8 advantageously minimized by the use of a molded _g_ .' ,, ~ 116~

plastic insulating sleeve 113 having a shoulder 115 (Figure 11) with a beveled surface 117. ~n inner bore of the sleevP 113 at the shoulder 115 extends over the runout and the shoulder collar is toothed to engage the armature shaft teeth 114 for causing rotation of the sleeve 113 therewith~ The fan 148 described hereinafter also includes a similarly beveled surface 147 (Fig. 3). Ihe elec~ric motor asse~bly 29 which is positioned in the field case 132 is mounted to the frame member 22 with a longitudinal axis of the a~nature 32 extending in a direction tran~verse to the length of the frame member 22. The f ield case,which as indicated, is generally cylindrically shaped in~ludes a ring 149 having radially extending ears 150, 152 and 171, best seen in Figure 9, and having apertures formed there~
in. Mountiny screws 156, 158 and 160 respectively, extend through these apertures and engage ~hreaded bores formed in ~he frame member 22 thereby securely mounting the field case and the motor assembly positioned therein to the frame member 22.
Flectrical energy is applied to the armature 32 from ~e line cord 40 which engages a plug 161 mounted in the handle o~ the housing. Electrical leads, not illustratedl extend from this plug to the trigger control switch 44 and from the trigger switch 44 to the field case 132. Electrical leads 162 in the ~ield case are coupled to spring biased brushes 165 for applying electrical energy to a Commutator 166 of the armature upon actuation of the trigger switch 44.
A means for cooling the motor 29 includes the fan 148 ~hich i~ mo~nted to the armature ~haft 116 for rotation therewith. A~ best seen in Figures 5 and 8, fan 148 includes a ~entral hub 8egment 151 having internally formed teeth 153.

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The hub segment is positioned on a too~hed segment of the armature shaft 116 and the ~eeth 153 are positioned in engagement therewith for causing rotation of the fan upon ro~ation of ~he shaft. Cooling of the motor is effected by rotation of the fan 148 which establishes an air stream fl~wing through slotted apert~res 155 (Figure 5) formed in a cap 157 which is mounted to the field case 132 by screws 159, over the motor field core and winding 130 and 133, over the armature 32 and through apertures 154 în the housing member 28. ~ means is pr`ovided for increasing the flow over the outer ~urface of the armatuxe 32 in order to enhance the cooling of the armature.
This means comprises a cylindrically shaped baffle 163 which extends into the field case 132 from a location adjacent the field frame 22~ The ba~fle includes a plurality of radially extending segments 164 which increase the resistance of air flow over the outer portions o the winding and increase the flow of cooling air between the armature and the core 130 thus enhancing cooling D~ the armature.
The housing member 26 ~Figure 3) includes a gripping aperture 170 formed therein, a motor aperture 172, a post segment 174 and a transversely extending flange 183 extending about the periphery o~ this housing member. The gripping aperture 170 includes a transversely extending integrally ~ormed flange segment lB5. A transversely extending, cylindrically ~haped motor flange segment 187 extends about the motor aperture 1~2. ~he ~witch 44 and the electrical power plug 161 are ~upported by ribs not illustrated in detail.
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11~;1ti17 The hand gripping post segment 174 includes a shoulder segment 176 and a segment 178 ~f reduced diameter in which an aperture 180 is formed. The tubular gripping handle 38 includes a segment 181 which engages the segment 178. A bolt 182 extends through the aperture in the handle 38 and through the aperture 180. It is engaged a~d secured by a lock nut 186.
Ribs 188 are integrally formed with the tubular handle 38.
These ribs guide placement of the bolt 182 during fabrication and operate to cause rotation of the bolt up3n mounting the handle 38 to the ool 20.
The housing member 28 similarly includes a hand gripping aperture 190 formed therein and is configured to abut against the frame member 22, to conform wi~h the shape of the g~,ard 62, and to space itself fxom the surface ~f fra~e member 22 for receiving the bearing support segment 58 of the frame member 22.
The housing member 28 includes a plurality of recessed bores 198 (Figure 5) having apertures formed therein and which are axially aliqned with segments formed in the housing member 26.
A plurality of screws 200 extend through the apertures of the bores 198, through aligned bores in the frame member 22 and engage the bores 202 ~f the h~using member 26 to securely main-~ain the `nousing members 26 and 28 in assembly with the frame member 22. A plurality of screws 210 (Figure 4) extend through the frame member 22 and engage the llousing member 26 while ~crews 212 (Figure 4~ extend through the housing member 28 and engag~ the h~using member 26 at the gripping handle area.

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I' In addition to employing the surface finishing tool 20 with peri.pheral acting finishing devices, the tool can also be usefully employed with a planar type of finishing device such as a sanding disc, a polishing bonnet, etc. Figures 12~
and 13 illustrate a sanding disc assembly mounted ~o the to~l.
The sandlng disc assembly includes a circular disc backing plate having an extended hub ~32 with a centrally formed bore 233 having an internally threaded insert 234 molded therein for engaging the distal threaded segment 236 of ~he spindle 30. A
pressure ~ensitive adhesive abrasive disc 238 is mounted against a lower surface of a foam body 240 which is secured by an adhesive to the backing plate 230.
Mounting and demounting of a finishing device is facilitated by initially restraining rotation of the spindle 30. A pin 251 (Figure 4) is inserted insequence ~hrough an aperture 253 in ~he housing member 26 (Figure 1), through one of the apertures 255 in the pulley 110 and in~o a pocket 257 which is integrally formed in the member 22. Extension of the pin through these members inhibits rotation of the pulley and of the spindle which is coupled thereto.
As indicated hereinbefore, the relati.ve positioning of the spindle and supported finishing device, the motor and the hand gxips provide a balanced tool which exhibits enhanced ease of handling with differen~ finishing vperations. In a preferred embodiment the housing members, field case, and handle grip are formed of a poI~mer plastic while the frame i~ formed ~f a light weight metal. Other materials may be utilized in fabr~c~ting these mbmers to satisfy the desired weight~ cost and operational characteristics.
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Thus, an improved, hand heldl electrically operated, portable, surface finishing tool adapted for a multiplici~y of finishing operations has been described. The tool is particularl advantageous in that its configuratioll provides for ease in handling and use. The~speed-torque characteri.s~ics of the tool are selected to be advantageou.s with both peripheral and planar actin~ devices thus providding a means for driving a variety of different devices having desired finishi.ng charac~eristics.
In an exemplary arrangement, the surface finishing tool provides a no load speed of 2700 or 3400 RPM. Since it is formed of relatively light weight materials, it reduces the fatigue accompanying the use of heavier portable hand held tools. ~he noise level is relatively quiet because of the provision of a belt drive and a relatively uniform finishing operation is ~ccomplished because of the relatively higher speed with which the tool can be operated in comparison with the use of finishing devices with portable electric drills. The tool handling ease and its facility for use further enhance the characteristics of the finished ~urface.
While a particular embodiment of tbe invention bas been described, it will be apparent to those skilled in the art that variations may be made there~o without departing from the spirit of the invention and the scope ~f the appended claims.

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Claims (4)

CLAIMS:

1. An improved arrangement for coupling rotary motion between an armature shaft of an electric motor and a body to be rotated comprising:
a. an electric motor having an armature including electrical windings formed thereon, said windings having end segments thereof:
b. said armature having an electrically conductive, rotary shaft including teeth formed along a length thereof, c. a sleeve of electrical insulating material positioned about said shaft between said winding end segments and said shaft and insulating said windings from said shaft;
d. said sleeve including an inner surface having teeth formed therein for engaging said shaft teeth and causing said sleeve to rotate with said shaft;
e. said sleeve having an edge surface thereof extending in a transverse direction to a length of said shaft, and, f. an elongated, toothed drive belt having an edge thereof;
g. said drive belt positioned in engagement with said shaft teeth and having said belt edge in juxtaposed relationship with said sleeve edge surface.

2. The arrangement of claim 1 wherein saidteeth formed on said shaft includes a tool runout segment and said sleeve extends about said runout segment.

3 . The arrangement of claim 1 wherein said sleeve edge surface includes a segment extending in a direction anti-parallel relative to the edge of said drive belt.

4. The arrangement of claim 1 wherein said sleeve includes a transversely extending shoulder segment and said sleeve edge segment is formed thereon.