US2929175A - Buffer wheel mounting - Google Patents

Description

March 22, 1960 MURRAY BUFFER WHEEL MOUNTING 4 Sheets-Sheet 1 Filed July 31, 1958 INVENTOR. [277632 J. )Yzz r74? Jamm 7 March -22, 1960 E. E. MURRAY 2,929,175

BUFFER WHEEL MOUNTING Filed July 31, 1958 4 Sheets-Sheet 2 q :Z Q INVENTOR. E -7. Jrrresz" Z2 )fzzrraz /7 Fur/ E. E. MURRAY BUFFER WHEEL MOUNTING March 22, 1960 Filed July 31, 1958 4 Sheets-Sheet 3 March 22, 1960 E. E. MURRAY BUFFERWHEEL MOUNTING 4 Sheets-Sheet 4 Filed July 31, 1958 INVENTOR. 1. 77766"; .5, yarrrdy i BY w 'LcvL United tates Paten 2,922,175 BUFFER WH EL MOUNTING Ernest Murray, Birmingham, lVIich. Application July 31, 1958, Serial No. 752,363 10 Claims. (Cl. 51-165) This invention relates generally to bufiing or polishing machines and more particularly to apparatus for automatically adjusting the position of the huffing memher in such a machine to compensate for wearing of the member.

An object of this invention is to provide an improved apparatus for automatically'adjusting the position of the oufling member in a bufling machine to compensate for .wear of the bufling member.

A further object of this invention is to provide apparatus for accomplishing the above adjustment quickly as well'as completely automatically, without any hunting which is an objectionable featureinherent in'many prior devices for this purpose. Another object of this invention is to provide apparatus or" the above type which senses from the part being buffed and operates through the medium of the float distance of the buffing member to accomplish the desired adjustment.

A further object of this invention is to provide apparatus of the above type which provides for an automatic signal when the bufiing member has been worn to a size requiring replacement.

' Still a further object of this invention is to provide apparatus of the above type which is simple in construction, economical to manufacture, and efficient in operation in automatically and continuously adjusting the position of the buffing member to compensate for wear thereof.

Further objects, features and advantages of this invention will become apparent from the following description and the appended claims, when taken in connection with the accompanying drawings in which:

Figure lis a fragmentary side elevational view of a bufiing machine shown in assembly relation with one form of the adjusting apparatus of this invention;

Fig. 2 is a fragmentary sectional view looking substantially along the line 2-2 in Fig. l; h

Fig. 3 is a fragmentary plan view looking generally in th r c o of h row 3 in i 1;

Fig. 4 is a fragmentary rear view looking substantially in the direction of the arrow 4 in Fig. 1;

Fig. 5 is a wiring diagram for the apparatus of this invention; V I

Fig. 6 is a diagrammatic view illustrating the relative positions of a workpiece conveyor, the bufiing member, and a control switch in the adjusting apparatus of this invention;

Fig. 7 is a diagrammatic view of the form of the adjus'ting apparatus of this invention shown in Fig. 1;

Fig. 8 is a fragmentary side elevational view of a buffing machine shown in assembly relation with a modified form of the adjusting apparatus of this invention; and

Figs. 9 and '10 are transverse sectional views looking along the lines 9-? and 1010 in Fig. 8.

Withreference to the drawings, the-apparatus of this invention; indicated generally at 10, is illustrated in Pig. [in assembly'relation w-itha bufiing machine indicated 2,929,175 Patented Mar. 2 2, 1950 generally by the numeral 12. The machine 12 includes the usual bufiing'wheel 14 carried on which for convenience of description will be hereinafter referred to as the front end of a supporting body structure 16 which is in turn pivotally supported for up and down movement about a horizontal shaft 18. The wheel 14 is usually formed of a plurality of tightly packed discs of soft materials such as cotton and the like. The shaft 18 is carried by a'supporting structure, only a fragmentary portion of which is illustrated at 20, which may be suspended from an overhead frame or the like.

A pair of transversely spaced arms 24 (Figs. 1 and 3) extend upwardly from the body structure 16 and carry a block 26 mounted for sliding movement in a slot 28 in an elongated support bar 30 arranged above the body structure 16. .The support bar 30 is inclined upwardly and rearwardly and carries a threaded stud 32 which is firmly secured at its lower end to the upper end of the bar 30. A bearing sleeve 34 (Figs. 1 and 2) rotatably supports an elongated nut 36 for the stud 32 and in turn carries a pair of pivot pins 38. A shoulder 37 and a retainer ring 39 at opposite ends of the nut 36 prevent movement of the nut36 longitudinally of the bearing 34. The pins 38 are' pivotally supported on the upper ends of a pair of upwardly inclined arms 40 on a stationary supporting member 42 associated with the supporting structure 20."

A ratchet wheel 44 having teeth 46 is positioned about and secured to the nut 36. A ratchet pin 48, carried in a housing 50 mounted on a ring 51 rotatably supported on the nut 36 adjacent the ratchet wheel 44, has a tooth shape'end 52. a The pin end 52' and the teeth 46 are shaped such that on swinging movement of the pin 48 in a counterclockwise direction as viewed in Fig. 4, the ratchet wheel 44 is rotated bythe pin 48. On swinging movement of the pin 48 in an opposite direction, the pin moves rearwardly against the action of a spring 54 in the housing 50 so as to ride over the teeth 46 without effecting any rotation of the ratchet wheel 44. A laterally extended handle 56 on the pin'48 is located outwardly of the housing 50 andis manually operable to retract the pin 48 "relative to the teeth 46'when the nut 36 is being reset. The end 58 of the nut 36 is preferably of a square or hexagonal shape to facilitate the assembly of a wrench with the nut to rotate the nut for resetting purposes.

A pneumatic cylinder assembly 60 (Figs. -1 and 4) supported on a frame 62a secured to the sleeve 34 has an extendible and retractable piston rod 62 connected to the housing 50.' Accordingly, When the assembly 60 is operated to extend the piston rod 62, the housing Ed and the pin'48 are'rotated in a counterclockwise direction as viewed in'Fig. 4, to in turn also rotate the nut 36. On retraction of the piston rod 62, the housing and pin are rotated in an opposite direction with the pin 48 riding over the teeth-46 so as to be in a position for the next nut turning operation.

On each turn of the nut 36, the stud 32 is moved downwardly along with the bar 30. 'As a result, an adjustable threaded stop member 66 at the lower end of the bar 30 is also moved downwardly. The stop member 66 engages the slide block 26 to limit downward movement of the bufflng wheel 14. Consequently, when the stop 66 is moved downwardly, additional movement of the buffer wheel 14 in a downward direction is permitted. As a result, by coordinating the adjustment of the stud 32 with wear of the wheel14, a predetermined location of the peripheral surface of the wheel 14 relative' to a workpiece located-blow'the wheel 14 is readily m d 1 7 I" ..L 1; g. 1 I A'cont'rol circuit 10 for coordinating the adjustment of the'stud' 32 with wear of the trated in Fig. 5. The circuit 70 operates to control the position of a solenoid valve, indicated diagrammatically at 72 (Figs. 5 and 7), associated with the pneumatic cylinder assembly 60 for selectively admitting air under pressure to the assembly 60 to extend or retract the piston rod 62. The circuit 70 provides for an automatic operation of the cylinder assembly 60 in response to wear of the buffer wheel 14.

A normally closed switch LS1 in the circuit 70 is mounted on the upper end of the bar 30 (Fig. 1). An actuating arm 74 adjustably clamped in an upright sup port 76a carried by. the slide bar 26 engages and closes the switch LS1 on upward movement of the slide bar 26 to a predetermined position. A normally open switch LS2, connected in series with the switch LS1, is mounted on a supporting frame 76 for the usual conveyor, a portion of which is shown at 75 in Fig. 6, for moving workpieces past the machine 12 so that the wheel 14 can buff and polish the workpieces. The conveyor has workpiece supporting platens 78 which move along the frame 76 adjacent the machine 12.

By way of example, an automobile bumper 80 is illust'rated in Fig. 6 mounted on the platen 78 for travel into engagement with the buffer member 14. An actuating arm 82 mounted on the frame 76 is operated by a fixture (not shown) on the platen 78 to close the normally open switch LS2 in positions of the platen 78 in which the highest portions of the workpiece 80 are engaged by the butter member 14.

A switch LS3 mounted on the bearing sleeve 34 (Figs. 1 and 3) has a first pair of normally closed contacts LS3a and a second pair of normally open contacts LS3b. As shown in Fig. 5, the switches LS1 and LS2 and the contacts LS3a are connected in series with the solenoid valve 72 across a pair of lead lines 79. The contacts LS3b are connected in series with a warning light 86 also across the lines 79 so as to be in parallel with the switches LS1 and LS2 and the contacts LS3a. The contacts LS3a and LS3b are connected in the usual manner for concurrent operation so that when the contacts LS3a are closed, the contacts LS3b are open and vice versa.

. An actuating knob 88 (Fig. 3) on a supporting arm 90 which is adjustably mounted on the bar 30 is engageable with an operating member 92 on the switch LS3 to open the normally closed contacts LS3a and close the normally open contacts LS3b. The arm 90 is initially set such that when a full wheel wear has taken place, the knob 88 actuates the switch LS3 to open the contacts LS3a and prevent further energization of the solenoid valve 72. Accordingly, further adjustment of the stop member 66 is prevented and the warning light 86 is energized by closing of the contacts LS3b to indicate the need for replacement of the bufiing wheel 14. It is apparent that a buzzer or other alarm could be satisfactorily substituted for the light 86. Also, a switch for controlling the operation of the conveyor could be substituted for the light 86 so that the switch is opened to stop the conveyor 75 when the contacts LS3b are closed.

In the use of the apparatus 10 with the machine 12 and the conveyor 75, the nut 36 is initially manually adjusted so that the bar 30 is close to the nut 36. This initial setting provides for a maximum downward movement of the bar 30 during operation of the apparatus 10 to compensate for wear of the Wheel 14. The stop 66 is set to provide for a location of the buffer wheel 14 in engagement with the lowest portion of the bumper 80 in a position of the slide block 26 against the stop 66 or spaced slightly from the stop 66. As a bumper 80 moves past the wheel 14, the wheel 14 moves between upper and lower limit positions in which the wheel is on the highest portion of the bumper 80 and the slide block 26 engages the stop 66, respectively. The arm 74 is initially set so that when the bufling wheel 14 moves to its uppermost position indicated at A in Figs. 6 and 7, the arm 74 opens LS1. In its lowermost position indicated at B in Figs. 6 and 7, the wheel 14 is in a position to be picked up and supported on the next bumper 80 and the slide bar 26 engages the stop 66. A counterweight (not shown) or a spring device, like the device illustrated in connec tion with the apparatus shown in Figs. 8, 9 and 10, provides for a desired pressure engagement of the wheel 14 with the bumpers 80. Thetfioat distance of the wheel 14, namely, the distance traveled by the wheel between its A and B positions, is indicated at a in Fig. 7.

It is apparent that when the wheel 14 wears so that the diameter thereof is reduced, the float distance a is decreased. As a result, when the slide bar 26 moves upwardly in slot 28, it does not move far enough to provide for opening of the switch LS1. As soon as the platen 78 moves to a position closing the switch LS2, which position occurs immediately after the wheel 14 moves to position A, the solenoid valve 72 is energized to admit air to the cylinder assembly 60 so that the piston rod 62 is extended. This movement of the piston rod rotates the pin 48 in a counterclockwise direction as viewed in Fig. 4 to in turn rotate the ratchet wheel 44 and the nut 36 and lower the stop 66 to maintain the float distance a constant.

Stated otherwise, when the wheel wears the radius is decreased so that in position A of the wheel, the arm 74 does not reach the switch LS1. Accordingly, the cylinder assembly 60 is operated each time the switch LS2 is closed, to successively lower the switch LS1 until it reaches a position in which it is engaged by the arm 74.

As a result, the next time the wheel 14 moves upwardly to move the slide block 26 upwardly in the slot 28, the. arm 74 opens the switch LS1 prior to closing of the switch LS2 to thus prevent energizing of the solenoid valve 72. Each time the wheel 14 is worn to an extent corresponding to the adjustment increment for each extension of the piston rod 62, the cylinder assembly 60 operates to adjust the position of the position of the wheel 14. vThis procedure continues until the wheel 14 is worn to an extent such that the bar 30 has been moved downwardly to a position in which the knob 88 engages the plunger 92 to actuate the switch LS3. As pointed out previously, actuation of the switch LS3 discontinues further adjustment of the stop 66 and provides for lighting of the warning light 86.

It is thus apparent that the adjusting apparatus of this invention operates through the medium of the wheel float distance a to provide for continuous adjustment of the wheel 14. Accordingly, a continuous and complete but!- ing operation on a plurality of conveyor mounted workpieces can be performed and a worm wheel 14 is signaled without requiring any manual attention to the machine 12. In addition, the wheel 14 is in a position for engaging the next bumper in line following each bufling operation.

It is to be understood that while the apparatus 10 has been described in detail with respect to a wheel movable in and out in substantially horizontal directions and biased in one'direction by a spring or the like.

A modified form of the adjusting apparatus of this invention, indicated generally at 10a, is illustratedin Fig. 8 in assembly relation with a bufiing machine 12a. The switches LS1 and LS3, previously described in connection with the apparatus 10, are illustrated in Fig. 8 mounted on the machine 12a and are circuit connected with the switch LS2, as illustrated in Fig. 5.

The machine 12a is mounted on a supporting structure, a fragmentary portion of which is indicatedat which may be suspended from an overhead frame or the like and which carries a pair of mutually perpendicular shafts 102 and 103 (Fig. 8). The usual buffing wheel 14a for the machine 12a is carried on the front end of a body structure 106 which is pivotallysupported intermediate its ends on shaft 102 so that the wheel 14a is movable up anddown about the shaft 102. The

sesame wheel 14a and the shaft 102 are movable about the shaft 103 in the event tilting or inclining of the wheel 14a is desired.

An upwardly and rearwardly inclined portion 108 of the body structure 106 carries a stop screw 110 adjacent its terminal end 112. Also supported on the body portion 108 adjacent the end 112 is a pivot block 114 swingable about a pivot 116. A rod 118 clamped to the block 114 is connected to one end of a spring 120, the opposite end of which is connected to an operating lever 122 for the switch LS1. In response to a downward swinging movement of the body portion 108 to a predetermined position, corresponding to a predetermined upwardly moved position of the buffer wheel 14a, the spring 120 pulls the normally closed switch LS1 to an open position.

An elongated stud member 126 has a threaded end portion 127 threadably supported in a projection 128 on the supporting structure 100. A projection 130 on a supporting casting 132 carried on the shaft 103 rotatably supports a portion of the stud member 126 spaced from the threaded portion 127. The end 134 of the stud 126 engages the stop screw 110 and functions as a stop for limiting swinging movement of the buffer wheel 14a in a downward direction.

A wrench or the like may be applied to the opposite squared end 138 of the stud 126 for manually adjusting the stud to a desired position relative to the stop screw 110 in initially setting up the apparatus a.

The switches LS1 and LS3 are carried on opposite sides of an upright supporting plate 140 which is in turn carried on a rod 142 slidably supported in a boss 144 formed on the supporting structure 100 at a position above the stud 126. At its lower end, the plate 140 is positioned between a pair of collars 146 clamped to the stud 126 so that the plate 140 is movable with the stud 126.

A pair of upright arms 150, rotatably supported at their lower ends on the stud 126, are connected by a cross brace 152 and carry a pivot pin 154 extended between the upper ends thereof. A pneumatically operated piston and cylinder assembly 156 has a cylinder member 158 connected by a pivot 160 on a frame 162 carried by the casting 132. The assembly 156 also includes a piston rod 164 connected to the pivot pin 154 so that on extension of the piston rod, the arms 150 are rotated in a counterclockwise direction, as viewed in Fig. 9.

A transverse extension 166 of the arms 150 is provided with a housing 168 for slidably supporting a pawl 170. A coil spring 172, extended about the pawl 170, and arranged in compression between one end of the housing 168 and a stop collar 174 on the pawl 170 urges the pawl 170 toward a position in engagement with a ratchet wheel 176 secured to the stud 126 by a key 178. The wheel 176 is positioned between the arms 150 and is relatively loosely mounted on the key 178 so that the ratchet wheel 176 is movable longitudinally of the stud 126 for a purpose to appear presently.

In operation, the apparatus 10a is initially installed as illustrated in Fig. 8, which shows the relative positions of the parts for a full size buffing wheel 14a, namely, before any wear of the wheel 14a. The rod 118 is adjusted in the block 114 so that for a maximum float movement of the buffing wheel 140, the pull on the spring 120 exerts sufficient pulling force on the lever 122 to open the switch LS1.

The desired work pressure of the wheel 14a upon the workpieces is obtained by adjusting a spring assembly 180 on the shaft 102. The assembly 180 includes a torsion spring 182 secured at one end to the shaft 102 and at the opposite end to a housing 184 adjustably mounted on the body structure 106. In those cases in which the buifing wheel 14a is mounted for up and down movement, the spring 182 is positioned so that it acts against the force of gravity on the buffing wheel 14a so that the wheel exerts the desired work pressure on the workpieces.

In those cases in which the wheel 14a moves back and forth about an upright axis, the housing 184 isrevr'eid on the shaft 102 so that the spring 182 acts to urgthe buffing wheel 14a toward the workpiece so that the wheel exerts the desired work pressure. v

When the wheel 14a has been worn to an extent such that in its extreme upperposition the force of the spring on the lever 122 is insufficient to open the switch LS1, the solenoid valve 72 is energized, on closing of the switch LS2 when the workpiece carrying platen reaches a predetermined position. On energizing of the solenoid valve 72, the pneumatic cylinder and piston assembly 156 is operated to rotate the pawl in a counterclockwise direction, as viewed in Fig. 9, to in turn rotate the ratchet wheel 176 and the shaft 126.

On rotation of the threaded portion 127 of the stud 126 in the projection 128, the stud is retracted relative to the stop screw 110. As a result, the location of the buffing wheel 14a relative to the workpiece is adjusted sufficiently to compensate for the Wear of the buffing wheel. This adjustment continues during wheel wear until the stud 126 reaches a limit position. This posi; tion is determined by the engagement of an actuating lever 188 for the switch LS3 and a pin 19 0 and some; sponds to a fully worn condition of the wheel 14a. The pin 190 is adjustably attached to a block 192 secured to the outer end of a plate 194 attached to the projection 130 on the casting 132. On engagement of the lever 18$ with the pin 190, the contacts LS3a are opened to prevent further energizing of the solenoid valve 72 and the conltacts LS3b are closed to provide for operation of signal light 86.

Although the invention has been described with respect to a preferred embodiment thereof, it .is to be under,- stood that it is not to be so limited, since changes can be made therein which are within the scope of the invert,- tion as defined by the appended claims.

What is claimed is: e

1. In a buffing machine, a work engageable, wearable buffer member mounted on a supporting frame for pivotal back and forth movement a distance necessary for continuous engagement of the buffer member with irregularly shaped workpieces, stop means operatively associated with said buffer member for limiting movement of the buffer member in one direction to a stop position for the bufier member, a control member actuated in response to movement of the buffer member said distance in the opposite direction from the stop position therefor, and means associated with said control member for moving said stop means to provide for increased movement of said buffer member in said one direction in response to movement of said buffer member in said opposite direction a distance insufiicient to provide for actuation of said control member. 7

2. In a buffing machine, a work ,engageable, wearable buffer member mounted for back and forth floating move} ment in opposite directions for continuous engagement with irregularly shaped workpieces movable along a line past said machine, said buffer member being movable through a float distance corresponding to the distance between the portions of said workpieces closest to and farthest away from said buffer member in the direction of floating movement, stop means for limiting movement of said buffer member in one direction toward the farthest portion of said workpieces, and means responsive in operation to a decreased movement of said member in the opposite direction as a result of wearing of said merriber for moving said stop means in a direction to provide for an increased movement of the member in said one direction a distance necessary to maintain said float distance constant.

3. In a bufiing machine, a work engageable, wearable machine, said buffer member being-movable through a float distance corresponding to the distance between the farthest spaced portions of said workpieces in a direction corresponding to the direction-of said back and forth movement, adjustable stop means for limiting the movement of said buffer member in one direction, screw means associated with said stopmeans for selectively moving said stop means in a direction to provide for increased movement of the buffer member in said one direction a .distance necessary to maintain said float distance constant during wearing of said buffer member, and means responsive in operation to a decreased movement of said buffer member for advancing said screw means.

4. In a bufling machine, a work engageable, wearable buffer member mounted on a supporting frame for back and forth movement in opposite directions in continuous engagement with irregularly shaped workpieces movable on a conveyor past said machine, said buffer member being movable through a float distance corresponding to the distance between spaced portions of said workpieces in a direction corresponding to the direction of said back and forth movement, a stop member movably mounted on said frame for limiting movement of said buffer member in a direction toward one of said spaced portions to a position engaging said one portion, screw means for moving said stop member in a direction to provide for an increased movement of the buffer member in said one direction a distance necessary to maintain said float distance constant during wearing of said buffer member, ratchet means operatively associated with said screw means for advancing the screw means, fluid-operated cylinder and piston means for operating said ratchet means to advance said screw means, and circuit means operatively associated with said cylinder and piston means and responsive in operation to a decreased movement of said buffer member in the opposite direction for actuating said cylinder and piston means.

5. In a buffing machine, a work engageable, wearable buffer member mounted on a supporting frame for movement back and forth in opposite directions, stop means on said frame for limiting movement of the buffer member in one direction, a switch mounted on said frame in a predetermined spaced relation with said stop means, control means movable back and forth into engagement alternately with said stop means and said switch in response to movement of said buffer member, and circuit means responsive in operation to a decreased movement of the control means in the direction of said switch to a position short of engagement with said switch for moving said stop'means in a direction providing for increased movement of said buffer member in said one direction.

6. In a buffing machine, a work engageable, wearable buffer member mounted for movement back and forth in opposite directions, a support bar positioned adjacent said bufier member, an arm attached to said machine and slidably supported on said bar, stop means on said support bar engageable with said arm for limiting movement of the buffer member in one direction, a switch adjustably mounted on said support bar in a predetermined spaced relation with said stop means, said arm being movable back and forth into engagement with said stop means and said switch in response to back and forth movement of said buffer member, means for moving said support bar, circuit means responsive in operation to a decreased movement of the arm in the direction of said switch to a position short of engagement with said switch when said buffer member has been worn to a reduced size, and means including power means operated by said circuit means for moving said support bar to position said stop means so as to compensate for wear of said bulfer member.

7. For use with buffing apparatus and a workpiece conveyor wherein the apparatus includes a resilient bufiing member mounted adjacent said conveyor for floating movement toward and away from the conveyor for continuous engagement with irregularly shaped workpieces thereon, said bufiing'member being biased in a direction toward the conveyor and being movable through a float distance corresponding to the difference inthe distances between the closest and farthest portions of said work of the conveyor to a position corresponding to the position of the bufiing member in engagement with said closest portion, means responsive in operation to closing of said first switch means for moving said stop means in a direction providing for further movement of the buffing member toward said farther portion, second switch means operative to render closing of said first switch means ineffective, said second switch means operating in response to movement of the bufling member through a full float distance and positioning of the buffing member at said closest portion, third switch means for rendering closing of the first switch means ineffective on movement of the stop means to a predetermined position corresponding to the size of the bufiing member after a predetermined amount of wearing thereof when the buffing member is in engagement with said closest portion, and signal means responsive in operation to actuation of said third switch means.

8. In a bufling machine, a work engageable, wearable buffer member mounted on a supporting frame for movement back and forth in opposite directions, stop means on said frame operatively associated with said buffer member for limiting movement of the buffer member in one direction, a switch mounted on said frame in a predetermined spaced relation with said stop means, control means movable back and forth into engagement with said stop means and said switch in response to movement of said buffer member, circuit means responsive in operation to a decreased movement of the control means in the direction of said switch to a position short of engagement with said switch for moving said stop means to compensate for size reductions of said buffer member, and signal means operatively associated with said circuit means for indicating a predetermined reduced size of said buffer member.

9. For use with buffing apparatus and a workpiece conveyor wherein the apparatus includes a bufling member mounted adjacent said conveyor for floating movement toward and away from the conveyor for continuous engagement with irregularly shaped workpieces thereon, said buffing member being biased in a direction toward the conveyor and being movable through a float distance corresponding to the difference in the distances between the closest and farthest portions of said workpieces from said buffing member in a position of the bufiing member toone side of the conveyor, apparatus for maintaining predetermined limit positions of the working surface of said buffer member during wearing of the buffing member to a reduced size thereof, said apparatus comprising stop means operatively associated with said buffer memher for limiting movement thereof toward said farther portion for engagement therewith, first switch means associated with said conveyor and movable to a closed position in response to movement of the conveyor to a position corresponding to the position of the buffing member in engagement with said closest portion, means responsive in operation, to closing of said first switch means for moving said stop means in a direction providing for further movement of the bufling member toward said farther portion, second switch means operative to render closing of said first switch means inefiective in response to movement of the bufiing member through a full float distance and positioning of the buffing member at said closest portion, and third switch means for rendering closing of the first switch means ineffective on movement of the stop means to a predetermined position corresponding to the size of the bufiing member after a predetermined amount of wearing thereof when the bufiing member is in engagement with said closest portion.

10. In a bufiing machine, a Work engageable, wearable bufiing wheel rotatably mounted on one end of a body structure which is in turn rotatably mounted intermediate the ends thereof on a supporting frame so that said bufiing wheel is movable back and forth in opposite directions and is biased in one direction, a stud member threadably supported intermediate the ends thereof on said frame and having one end engageable with said body structure adjacent the opposite end thereof for limiting movement of said bufiing wheel in said one direction, power means mounted on said frame and engaged with said stud for rotating the stud to adjust the position thereof and to increase the distance said wheel is movable in said one direction, said wheel being movable in an opposite direction to positions dependent on the size thereof and on the shape and position of the workpieces on which said wheel is bufiing, and means for actuating said power means in response to a decreased movement of said wheel in said opposite direction as a result of Wearing of said wheel.

References Cited in the file of this patent UNITED STATES PATENTS 1,516,103 Keller Nov. 18, 1924 1,549,600 Mueller Aug. 11, 1925 2,490,848 Vossler Dec. 13, 1949 UNITED STATES PATENT OFFICE I CERTIFICATE OF CORRECTION Patent No. 2,929,175 March 22, 1960 Ernest E, Murray It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 37 strike out of the position"; line "50 for "worm" read Worn Signed and sealed this 20th day of September 1960..

SEAL) Attest:

KARL H AXLINE ROBERT C. WATSON Attesting Officer Commissioner of Patents

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