US2932926A

US2932926A - Method and apparatus for polishing articles

Info

Publication number: US2932926A
Application number: US670729A
Authority: US
Inventors: Peter M Dreiling
Original assignee: HI LITE POLISHING MACHINE CO I
Current assignee: HI LITE POLISHING MACHINE CO I; HI-LITE POLISHING MACHINE Co Inc
Priority date: 1957-07-09
Filing date: 1957-07-09
Publication date: 1960-04-19
Anticipated expiration: 1977-04-19

Description

April 19, 1960 P. M. DREILING METHOD AND APPARATUS FOR POLISHING ARTICLES Filed-July 9, 1957 6 Sheets-Sheet l INVENTOR.

PETER M. DREILING m1 Mflfili Attorneys April 19, 1960 P. M. DREILING METHOD AND APPARATUS FOR POLISHING ARTICLES Filed July 9, 1957 6 Sheets-Sheet 2 FIG. 4.

63 INVENTOR. PETER M. DREILING Attorneys April 19, 1960 P. M. DREILING METHOD AND APPARATUS FOR POLISHING ARTICLES Filed July 9, 1957 6 Sheets-Sheet 3 fi I INVENTOR. PETER M. DREILING Attorneys 6 Sheets-Sheet 4 P. M. DREILING FIG. 7.

METHOD AND APPARATUS FOR POLISHING ARTICLES April 19, 1960 Filed July 9, 1957 O Q h I I R G W O N w. V m W k% N w I E M A a R rm E 4 "H W F. P 1 F m v u M 4 4 m a/, /|mv- .E w 5 8 m J A f// 8 V m 9 2 9 w 4 M 2 v 4 w 2 q 4 m 5 L 1. T J HH A .2; k. b k m 9 Attorneys April 19, 1960 P. M. DREILING METHOD AND APPARATUS FOR POLISHING ARTICLES Filed July 9, 1957 6 Sheets-Sheet 5 FIG. IO.

INVENTOR. PETER M. DREILING 4 M 4 Attorneys April 19, 1960 P. M. DREILING 2,932,926

METHOD AND APPARATUS FOR POLISHING ARTICLES Filed July 9, 1957 e Sheets-Sheet 6 uwmron. PETER M. DREILING "k xwrzm nited States ice METHOD AND APPARATUS FOR POLISHING AR CLES Peter M. Dreiling, hehoygan, Wis, assig'nor to Hi-Lite Polishing Machine .Co. inc, Shehoygan, Win, a corporation of Wisconsin Application July 9, 19 57, SeriaiNo. 670,729

32 Claims. {CL 51: 1.42)

corners, such as a stainless steel sink, has been finished or polished 'by a manual operation. In the manual procedure, the sink is either held by the operator and moved over a fixed grinding or polishing member, or

the-sink is fixed-and :a flexible shaft polishingmember is employed byhtheioperator .to finish the inside surface of the 1 sink.

The presentinvention is directed :to a machine for automatically oinishi-ng the "bottom surface and inside cornersof-agenerally rectangular container, such as a stainless steeLsink/orthe like. he workpleceisfinished by a. polishing or abrading member which moves across the surface eithe -workpiece as the'same is moved in a direction generally normal to-the. gdirection ofmovement of the abrading member. More.-specifically,=the workpieceissupported by .a chuck which is initially tilted upward so that the abrading member is disposed in verc'tical alignment with one .of t the inside corners Lto be 1 polished. .As the -.abrading member .reciprocates ,across the surface of the=workpiece, =the.-chuck is tilted downwardly .to 'a generally. horizontal 1 position and moves. in a directiongenerailyrnormaltothedirection of reciprocation of the abrading member. 'z-During this action, the

bottom .surface,-of the workpiece is finished.

When the.-abra;dingjrn ember=;is disposed in vertical alignment #withthe opposite inside. corner of the. workpiece, thewchuck again tilted upwardly i so that the abrading memberawill polish that inside corner.

The reciprocation ofsthe abrading memberi serves to polish thetinside-tcornersmf'the-workpiece which exitendqgenerallyparallehto-the direction of travel ofthe chuck, and by tilting -;the chuck upwardly-at the be- -ginningyand endyofgqtheoperation, the inside corners which extend-generally perpendicular to the direction of travel of the chuck are also polished;

"Ehe present apparatus;automatically polishes the botitom surfaee and all; four inside corners .of agenerally rectangularcontainer in.a single operation and provides an excellent finish for the inside of the container which passes dairyinspections. gThe. apparatus..;will effectively polish the-bottom surface tof the container regardless of any irregularities in the contour of the surface, as in the case of a; sink in :which' thebottom; surface is sloped to .aldrai ep nin in additiom the apparatps can be used to polishvarious sized containers;or workpieces. In order to change from one container size to another, a new chuck,.corr esponding to t esi e frthe onta n o .b .-p shed,;;is. m y ser n wth app atu en in when tera io t ppa t ss s requ e O h wbi san adta t s l ar e rr ntt au of, the following; description.

, system of. the. apparatus;

The drawings illustrate the best mode presently contemplated for carrying out the invention.

i In the drawings:

Figure l is aside elevation of the apparatus invention with parts broken away in section;

Fig. 2 is a top plan .view of the apparatus shown in Figure 1 with parts broken away;

Fig. 3 is an end view of the apparatus with parts broken away in section;

Fig. 4' is an enlarged side elevation of the crank sprocket and timing plate;

Fig. 5 is an enlarged fragmentary front elevation with parts broken away in section of the carriage plate and contact wheel structure;

Fig. .6 is an endview with parts broken away showing of the .the structure .of :Fig. 5

.tilted' position;

Fig. 10 is a schematic drawing of the chuck drive mechanism showing the chuck in the tilted position at .the .start of the polishing operation;

Fig. 11 is a view similar to Fig. 10 and showing the chuck in the horizontal position;

Fig. 12 is a view similar to Fig. 10 and showing the chuck roller in engagement withthe slide plate lug; .Fig. 13 is aview similartoFig. l0 and showing the .chuckpivoted upwardly at the end ;of the polishing operation;

Fig. 14 is a wiring diagram of the electrical control Fig. 1L5 is aside elevation showing he position of the ,limit switches for actuating the head and chuck drives; and

Fig. 16. is a view taken along line.1;6 16 of Fig. 15. Tnedrawings illustrate an apparatus for polishing or otherwise finishingthe bottom surface and inside corners .Of a generally rectangular container, such as a sink or similanarticle.

@TheaPparatus comprises, in general, a base 1 which carriesa work chuck 2 adapted to support and move the workpiece-,3 during thepolishing operation. An abrading head 4 is mounted on a column 5 attached to base 1. and is adapted to engage, and polish the workpiece as the same is moved in its path of travel with chuck 2.

.T he" base 1 may have anysuitable'construction and is shown as a rectangular box-like housing having four side walls ,6 reinforced by stifieners 7 which extend the length of the opposite side walls.

The chuck 2 is movably supported on. the base 1 by means .of a plurality of rollers 8 which are secured to thechuck and ride on rails 9 associated with the base 1.

Each of the rollersS is secured to a shaft 10 which is journaled in an opening in the side Wall of the chuck 2 andeach pair of shafts 10 associated with a given side of the chuck are connected by and journaled in a bearing arm 11.

The guide rails 9 on which the rollers 8 ride are secured to the inner surface of an extension plate 12, which is attachedby suitable bolts to the upper edge portion of opposite side wall 6 of base 1.

To provide the chuck 2' with movement with relation to the abrading head 4, a sprocket 13 is secured to each of the shafts 10 and is spaced from the respective chuck .wall bya plate 14. Each pair of sprockets associated .with a given side of the chuck are. driven by an endless chain 15 and the chains 15 are driven by motor 16. Motor 16 is mouuted on a plate 17 which issupported on cross bars 18 resting on stifleners 7 of base 1. The motor 16 is connected to a speed reducing unit 19, and a sprocket 29 is secured to the output shaft 21 of the speed reducer. The sprocket 20 is connected by a chain 22 to a sprocket 23 carried on shaft 24 which is rotatably secured to one of the side walls 6. A drive sprocket 25 is secured to the shaft 24an'd engages one of the endless chains 15 to drive the same. The chains 15 travel over

idler sprockets

26, 27 and 28, each of which is rotatably secured to a suitable bracket attached to the base 1. To impart the movement of the drive chain to the second chain, the sprockets 28 are secured to a common shaft 29. Rotation of the sprocket 28 associated with the drive chain is transmitted through a shaft 29 to the sprocket 28 associated with the driven chain to drive the same.

The tension on the chain 15 is adjusted by means of a sprocket 30 which is adjustably attached to a bracket 31 extending outwardly from the base 1. By proper adjustment of the location of sprocket 30 on bracket 31, the

tension on the drive chain 15 can be varied, as desired.

To support the chains 15, a chain support bar 32 extends upwardly from a plate 33 which is secured to the inner surface of the opposite side walls 6. The bars 32 support the respective chains 15 in the span between the

sprockets

27 and 28 and serve to keep the chains in engagement with the respective sprockets 14 associated with the chuck 2.

With this construction, the operation of motor 16 drives the endless chains to move the chuck 2 with respect to the abrading head 4 and during the chuck movement, the rollers 8 ride on the guide rails 9 which are secured to the base 1.

The speed of the chuck travel is designed so that the workpiece will be moved slowly across the plane within which the abrading head 4 is reciprocating so that the head will polish or otherwise finish the entire bottom surface of the workpiece 3.

In order to polish the inside corners of the workpiece 3 which extend generally normal to the direction of chuck travel, the chuck is originally tilted upwardly, as shown in Figs. 9 and 10. -In the tilted position, the center line of the radius of curvature of the inside corner of the workpiece is in vertical alignment with the abrading head 4. The chuck 2 and workpiece 3 are then pivoted downwardly to a generally horizontal position resulting in a polishing of the entire radius of curvature of the inside corner. The chuck is then moved in a horizontal plane to polish the bottom surface of the workpiece, as shown in Fig. 11, until the opposite inside corner is in a position in vertical alignment with the abrading head 4. With the workpiece in this position, the chuck is then pivoted upwardly, as shown in Fig. 13, so that the abrading head will effectively polish the entire radius of curvature of this inside corner.

To tilt the chuck upwardly at the beginning and end of its stroke of travel, a plate 34 is slidably connected to each extension plate 12 and is free to move a limited distance in the direction of chuck travel. As best shown in Fig. 8, the plate 34 is slidably connected to plate 12 by means of bolts 35 which extend through aligned openings in plate 12 and in spacer plate 36, then through slots 37 in plate 34 and are threaded into an inner plate 38. With this connection, the plates 34 are free to move in the direction of chuck travel with respect to the extension plates 12.

As shown in Figs. 9-l3, each of the slidable plates 34 is provided with a central depending lug 39 which is located in the path of travel of the chuck rollers 8 and are adapted to be contacted by the rollers during movement of the chuck.

To limit the movement of the chuck 2, each plate 34 is provided with an upstanding ear 40 which is adapted to engage an adjustable stop 41. The adjustable stop 41 takes the form of a bolt which is threadedly engaged within an opening in a stop block 42. The stop block 42, in turn, is secured to extension plate 12.

As best shown in Fig. 10, the polishing operation is begun with the chuck in the tilted position. In this tilted position, the center of the roller 8 is in axial alignment with the center of the'radius of curvature of the corresponding inside corner of the workpiece and is also in vertical alignment with the abrading head 4.

As the chain 15 is driven, the chuck and workpiece are initially pivoted downwardly to a horizontal position and then the chuck is moved horizontally in the direction of chain travel, as shown in Fig. 11. The chuck is moved horizontally until the rollers 8 associated with the trailing end of the chuck engage the lugs 39 of the respective plates 34, shown in Fig. 12, and the rollers will then move the plates 34 forwardly in the direction of chain travel until the upstanding ears 40 of the plates engage the adjustable stops 41. When this occurs, the plates 34 and chuck 2 are no longer able to move with the chain and the continued movement of the chain 15 will thereby pivot the chuck upwardly to a tilted position, as shown in Fig. 13. The chuck begins to tilt upwardly when the center of the rollers 8 reaches a position in vertical alignment with the abrading head 4. As the chuck is pivoted upwardly to the tilted position, the abrading head polishes the entire radius of curvature of the corresponding inside corner of the workpiece.

If the center of the rollers 8 and the center of the radius of curvature of the workpiece 3 are not in vertical alignment with the abrading head 4 when pivoting action begins, a striped finish is obtained throughout the radius of curvature of the workpiece caused by polishing with the edge portion of thebelt rather than with the center portion of the belt. By proper adjustment of the stops 41, the position of the chuck at the start of the pivotal motion can be varied so that the center of the radius of curvature of the workpiece will always be in vertical alignment with the abrading head 4 during the pivotal motion regardless of the particular size of the workpiece or curvature of the corner.

The slidable plates 34 have a limited amount of movement which is determined by the position of the adjustable stops 41. Under normal operations, the depending lugs 39 of plates 34 move a distance equal to the radius of one roller 8 plus the radius of the second roller plus the thickness of the lug 39.

The workpiece 3 is centered longitudinally within the chuck 2 by'a plurality of generally curved blocks 43 which are secured to the bottom and opposite side surfaces of the chuck. Each of the blocks 43 is provided with the approximate curvature of the corner of the workpiece to complement the same.

The workpiece 3 is centered laterally within the chuck by a pair of

adjustable plates

44 and 45. The plates 44 carry studs 46 which extend-outwardly through openings in the side walls of the chuck and receive nuts 47. By suitable adjustment of the nuts 47, the position of plate 44 can be varied.

The plate 45 is urged inwardly toward the center of the chuck to bias the workpiece against the plate 44. In this regard, the plate 45 is provided with a pair of rods 48 which extend outwardly through tubes 49 secured within openings in the side wall of the chuck. Each of the rods 48 carries a stop 50 which is slidable within the respective tube 49, and a spring 51 bears between the outer end of the tube and the stop 50 to urge the' plate 45 inwardly. With this construction, the chuck 2 firmly holds the workpiece and can accommodate workpieces of vari ous'width depending on the particular. polishing operation involved.

The generally spare column 5 which carries the polishing head 4 is supported by base 1 by means of a generally box-shape extension 52 which is welded to one of the side walls 6 of base 1. Thelower end of the column 5 carries a generally rectangular plate 53 which is secured anemone -5 :fiatwise to the outerzsurfacezof box 524m :firmly secure the column to the base :1.

The abrading head 4 is adapted 'to be raised (and lowered with respect to the workpiece 3 and :chuck 2 to bring ithe abrading member into contact with the work- "piece. To guide the .head .in vertical movement with respect to the chuck 2, a pair of guides '54 are secured to the upper edges of the column 5 and are slidably "received within :guide blocksecured .to the ahead '4.

'The head 4 is raised and ilowered with respect to tthe .chuck 2 and base 1 by means of .a cylinder 56 which is :supported by a plate .57 secured toithe column 5. The piston rod 58 of. cylinder 56 :extends upwardly from the cylinder and bears against the underside of a bracket .59 attached to guide block :55. Hydraulic fiuid'is adapted to be admitted to the lower end of cylinder.5f6 'through a :conduit '60 .to :extend :the rod 58 :and eraise :the head 4 'with 'respect to the chuck 2.

The'head 4 isilowered toward the chuckrhyagravitynnd 'the downward movement of the.headaisllimited'byxengage- 'ment .of'the guide'hlockSS with an cadjustablestud #61 which is threadedly engaged within an opening in a bracket 62 "secured to columns. By threaded adjustment :ofcstud .61 within the bracket .62, tthe lowermost position of the head can be varied.

The head '4 includes a :ihorizontally :disposed trail 63 reinforced by a generally rectangular beam 64 which is coextensive with the rail. The guide block :55 ..is

:securedby welding to :the :face 10f .the :rail :63.

A carriage :plate .65 is "adapted toride :on therail :63 and reciprocates in a direction generally normal ato the direction of movement of "the .chuck 22. The marriage lpla'te 65 supports an endless :polishing belt :66 which passes .over a .contact wheel #67 adapted :to uengage :the workpiece 3 and polisht'the same.

"To support the carriage ;plate 65 :on ;the rail .63, .apair of generally horizontal arms 68 .are secured to the .rear face-of the carriage plate. A series of rollers :69 are rotatably secured'to the arms 68 andride on the forward face of the guide rail :63, while a pluralityof rollers 70 "are rotatably secured to the outer beveled edges .71 of "arms 68 and are adapted'to ride Ion the .upper and lower beveled edges of the rail 63.

The endless polishing or'abrasivebe'lt 6'6is driven by a drive wheel 72 and passes over-a-Wheel73, adjusta'bly secured to rail 63,-and over idler'wheels'i74, 75, 76 -and 77 which arerotatablysecured to the carriageplate:65. In addition, the belt 66 passes over:contact wheel'67 rand wheel'78 which are 'rotatablymounted on a contact'plate 79slidably secured to carriage plate "65.

The wheel 78 is rotatably supported between contact plate 79 and a parallel arm 80 which is secured to plate 79.

The lower end of plate 79 terminates in a-generally circular shaft 81 which is slidably disposed within an opening in a T-block 82 secured to carriage plate .65.

The upper end' of a connecting rod-'84'isthreadedly engaged within an opening in the lower end of shaft 81, while the lower end of rod 84 is threadedly engaged in a bar 85. The lower end ofbar 85 is bifurcated as indicated by 86, and rotatably'supports'the contact wheel 67.

To bias the contact wheel 67 downwardly into engagement with the workpiece 3, a pair of plates 87 are secured edgewise, as by welding, to the forward face of the carriage plate 65. A stop 88 is secure'dbetween the spaced plates 87 and is provided with 'anopening which receives the connecting rod '84. The contact wheel is'urgeddownwardly by a spring 89 which is interposed between 'the stop 88 and the upper endo'f .the bar-85.

As best shown in Fig. 5, the contact"wheel67 is provided with a radius substantially equal tether adios of curvature'of the corners of 'the workpiece 3 to enable the 'contactwheelto move into 'the corners and polish the same.- In addition, the periphery of the contact Wheel 4 67 I is curved in the "direction of the ax-is of the lcorners of the workpiece.

6 wheel, .as best shownin Pig. .6, with the radius of curvartureaapproxirnating that of the radius of curvature of the This latter curvature of the contact wheel permits the wheel to polish the inside corners of .the workpiece that extend generally parallel to the direction of reciprocation of the contact wheel. Thus, the-contact wheel is able to finish all four :inside .corners of the-workpiece with the corners extending per- ;pendicularto the direction of 'the'contact wheel reciproca: than being finished'due to the radius of the contact wheel, and .the corners extending parallel to the direction of (reciprocation of the contact wheel .being finished due to the curved :nature of the periphery of the wheel.

As lit is desirable .in some applications ,for the couttact-wheel-67 -to;polish only intone direction of its stroke of travel, the contact wheel maybe raised-out of contact with t-the workpiece on either .the forward or return stroke, :as :desired. This raising of the contact wheel is separate and independent from the mechanism which -is adapted=to raise and lower the head for the insertion and'rernovalof'the workpiece from the chuck.

To .raise theqcontact wheel167 out of contact with the .workpieceon one of=its strokes of travel, ta cylinder 90 .is secured to a bracket .91 attached to the upper end of ;plate 79, the contact wheel 67 and theuppcr Wheel 78, which are associatedvwith the plate 79, are moved up wardly .against the force of springfifi to remove the contact wheel from engagement with the workpiece. The'drive wheel 72 and

theidler wheels

73, 74, 75, '76

:and 77 are fixed with respect to vertical movement and, do

not move upwardly with the

wheels

67 and 78 when the :ram 9-3 of the cylinder 90 is extended. Under normal .practice the contact Wheel 67 is engaged with the .workpiece on only one of its strokes of reciprocating motion, and generally the contact is made-on the return stroke that is, the stroke in the direction toward column 5.

To adjust the tension on-the belt 66, the'wheel 73 is .securedto a bracket 96and the upper end of the bracket carries. a hub 97 :which is pivotally connected by.a ,pin

fiiittoa plate The plate 99 is attached to the rail -63 by means of clarnps 1% which. engage the beveled edges of the rail..63 and are secured to the plate 99by suitable bolts.

The :bracket 96 and wheel 73 are adapted to .be pivoted about the pin 98 to adjust the tension onthe belt 66. This is accomplished by a spring 101 which -is wound aroundthe hub 97 and is secured-to a pin 102 located on the hub. The free .end 103 of spring lillextends outwardly and is secured between a plurality of spaced pegs 1% attached to plate :99. By changingthe position of the free end 103 of spring-101 with respect to the pegs 104, the bracket 96 which carries wheel73 can be pivoted toobtain the desired amount of tension on the abrasive belt-65.

The endless abrasive belt 66 is driven by a;motor .105 which is connected through a drive system tothe drive wheel 72. The motor 105 is, suspended from the bottom plate 106 of a frame 107 whichis'attached to rail 63. ,The drive shaft 108 vof motor. 105 carries. a pulley EH59 which is connected by belt 110 to-a pulley 111 secured to a shaft 112. The shaft 1l2-is journaled within a bracket secured to rail 63, and the drive wheel 72 whichcarries the belt 66 is secured to the shaft. Ihus, the'rotation oflmotordrive shaft 108 is transmittedto shaftfllz andwheel n to drive the belt 66.

"The drive toreciprocate the carriage 65 and move the I 7 contact wheel 67 across the workpiece 3, is also taken from motor 105. In this regard, a second pulley 113 is securedto the 'drive shaft 108 of motor 105 and carries 'a belt114 which drives pulley 115 secured to hub 116. The hub 116 is journaled on a shaft 117 by a bearing 118 and the shaft is supported by a bracket -119 which is adjustably secured to vertical plate 120 of frame 107.

In order to adjust the tension on the belt 114, the connection between

bracket

119 and 120 is adjustable. Thus, plate 120 is provided with a pair of slots 121 and the bracket 119 is formed with a pair of aligned slots 122 which extend generally normal to the slots 121 in plate 120. Bolts 123 extend through the aligned slots, and by virtue of this slotted arrangement the position of bracket 119 can be varied with respect to the plate 120 to adjust the tension on belt 114.

The hub 116 also carries a sprocket 124 which drives a sprocket 125 through chain 126. The slotted adjustment between

bracket

119 and 120 also is employed to adjust the tension on chain 126. The sprocket 125 is secured to shaft 127 which is supported by the vertical plate 120. The sprocket 125 serves as a crank plate, and one end of a connecting rod 128 is secured to the sprocket 125 by means of a bearing assembly 129. The other end of rod 128 is secured within an opening in a block 130 supported by a tube 131 which extends outwardly from the rear surface of carriage plate 65. With this structure, the rotation of the sprocket 125 is transmitted through the rod 128 to the carriage plate 65 to cause the carriage plate to reciprocate along the rail 63 in accordance with rotation of the sprocket 125.

As previously described, the contact wheel and carriage'plate reciprocate in a direction generally normal to the direction of travel of chuck 2 so that the contact wheel will move across the surface of the workpiece and into the inside corners extending generally parallel to the direction of chuck movement. At the beginning and end of the chuck stroke when the chuck is tilted upwardly the contact wheel also reciprocates with the same motion to polish or otherwise finish the entire radius of curvature of the inside corners of the workpiece extending generally normal to the direction of chuck travel.

The raising and lowering of the head 4, the reciprocation of the head and the chuck movement are controlled through an electrical system, as shown in Fig. 14.

In the electrical control diagram, the main power lines are indicated by 132 and horizontal branch lines connected across the power lines are designated by an L series of numbers, such as L1, L2, etc. The contacts actuated by a given relay are designated by the reference number of the relay and a hyphenated number.

Automatic operation of the apparatus normally begins with the polishing head 4 in raised position. Depressing start cycle push button 133 in L1 energizes relay 134 to close normally open contacts 134-1 in L2, 134-2 in L5, 134-3 in L and 134-4 in power line 132. De-

pressing the start cycle push button 133 also closes the button 133A in L15 which is mechanically connected to button 133 and is actuated simultaneously. Closing the contacts of button 133A in L15 energizes relay 135 to close the normally open contacts 135-1 in L16, 135-3 in L7 and 135-4 in L10 and open normally closed contacts 135-2 in L6. The closing of contact 135-1 in L16 serves to hold the relay 135 in the circuit, while closing contacts 135-3 in L7 actuates solenoid 136 to release the fluid pressure in thecylinder 56 and lower the head 4 toward the workpiece 3.

The initial downward movement of the head 4 releases the normally closed limit switch 137 in L2 to close the same and hold in the relay 134. As best shown'in Figs. 15 and 16, the limit switch 137 is secured to a plate 138 attached to the top of column 5. The roller arm 139 of limit switch 137 is adapted to be engaged by a bar 140 which is adjustably secured to a bracket 141 attached to head 4. The bracket is provided with a series of slots 142 and a suitable bolt extends through one of the slots and is employed to position the bar with respect to the bracket. At thestart of operation,'the limit switch 137 is held open due to the engagement of the roller arm 139 with bar 140. However, as the head is lowered, the roller arm rides off the bar 140 and the limit switch 137 is then closed.

As the head is lowered, normally open limit switch 143 is closed to energize motor relay 144 in L3. Motor relay 144 operates the head drive motor 105 to start the reciprocating movement of the head and the belt drive. The limit switch 143 is secured to plate 138 and has a roller arm 145 which is adapted to be engaged by an adjustable bar 146 on bracket 141. As the head is lowered, the roller arm 145 rides on bar 146 to close the limit switch 143.

Just before the head 4 reaches its lowermost position of travel, limit switch 147 in L8 is closed to energize relay 148 in L11 through the closed contact 134-3 and 135-4 in L10. The limit switch 147 is provided with roller arm 149 which is adapted to be engaged by an adjustable bar 150 on bracket 141 as the head is lowered.

Energizing relay 148 operates the chuck motor 16 to move the chuck in its path of travel which is a right to left direction, as shown in Figs. 10-13. As previously described, the chuck initially pivots downwardly to a horizontal position and .then moves in the horizontal plane.

Energizing relay 148 serves to open the normally closed contact 148-1 in L5 and close the normally open contact 148-2inL12.

Contact wheel pressure against workpiece 3 is released during one of the strokes of reciprocation of the head by the cylinder 90 which is controlled by solenoid 151 and limit switch 152. The limit switch 152 is supported by -a bracket 153 which extends upwardly from rail 63. The roller arm 154 of limit switch 152 rides on the edge of a timing plate 155 attached to the shaft'127. When the roller arm is in contact with the edge of the plate 155, the limit switch 152 is closed to energize the solenoid 151 in L4. Energizing solenoid 151 operates cylinder 90 to raise the contact wheel 67 out of engagement with the workpiece.

To vary the timing of the contact wheel pressure, a pair of extension segments 156 are adjustably secured to the surface of plate 155 and serve to selectively change the amount of peripheral cam surface of the plate so that the periodof time in which the contact wheel is in engagement with the workpiece can be varied, as desired.

As the chuck travels to its extreme left position, as

,shown in Figs. 12 and 13, and pivots upwardly, limit switch 157 in L8 is closed to latch relay 158 in L9. The normally closed limit switch 157A in L11, which is tied in with limit switch 157, is simultaneously opened, thereby de-energizing the chuck motor relay 148 in L11. The impulse torelay 158 momentarily energizes relay 159 in L13 through the closed contacts 148-2 in L12. The contacts 148-2 in L12 open as the relay 158 latches, but as the impulse to relay 158 through its contacts 158-1 in L8 and the impulse to relay 159 occur at the same instant, the relay 159 is momentarily energized to open its normally closed contacts 159-1 in L16. The opening of contacts 159-1 in L16 serves to de-energize relay 135 in L15, thereby opening contacts 135-3 in L7 to de-energize solenoid 136. De-energizing relay 135 also closes normally closed contacts 135-2 in L6 to energize solenoid 160. The energizing of solenoid 160 serves to admit fluid pressure to cylinder 56 and raise the head upwardly.

The limit switch 157, which is closed as the chuck pivots upwardly at the end of its stroke of travel, is secured to base 1 and is provided with an upstanding arm 161. The arm 161 is adapted-to be engaged by a lever 162 which is fulcrumed at 163. As the chuck 2 pivots upwardly, the lower end of the bearing arm 11 contacts the lever 162 to pivot the lower end of the lever into con- "to trip relay 15%. Simultaneously,

tact with the 161nflimitswitch157 to actuate the same.

As the head .moves upwardly due to the energizing of solenoid 160,

limit switches

143 and 1 37 are releasedand, as the head approaches its uppermost position, limit switch 137 .is actuated to drop out the relay .134.

Tojrepeat the procedure and move the chuck from right toleft position, the start cycle push button 133 is again closed'to lower the head by action of

relays

134 and 135. The head and belt drive motor 1G5 is restarted by actuation of the limit switch 143 as the head is moved downwardly.

As previously described, the relay 158 was latched when the chuck reached its extreme upward tilted position. This had closedthe contacts 158-3 in L10. When limit switch 147 is closed as head 4 is lowered, chuck motor relay 164 in L is energized as contacts 1 34-3 and 135-4 in L10 are closed on energization of relays i134 and 1&5. Energizing relay 1'64 operates :the chuck motor in the opposite direction so that the chuck will 1 travel fnomleft to right.

Latching of relay 158, opened contacts 158-1 in L8 and 158-4 in L11 and closed contacts 158-2 in L9.

As the chuck reaches its extreme right position and is tilted upwardly, the limit switch 167 in L9 is closed with the closing of switch 167, switch 167A in L10 is opened to de-energize chuck motor relay 164. This momentarily opens contacts 164-2 in L14 to .de-energize relay 159. This drops {out relay 135 in L15 to again raise the head, as previously described.

The normally closed interlocks :148-1 and 164-1 in L5, which are in multiple with limit switch 152, keep the contact 'wheelsolenoid ;151 tie-energized in the event the chuck should :stall by the fact that one of the normally closed contacts 148-1 01' 164-1 are :open as the chuck is moving. If the chuck stalls, both contacts 148-1 and 164-1 will be closed, thereby energizing solenoid 151 through closed contacts 134-2 to raise the contact wheel. This will release the contact wheel pressure so that the Wheel will not run in one place to gouge or :remove excessive metal from the workpiece.

The switch 167 is disposed adjacent switch 157 on base 1 and .is provided with an upstanding arm 168 which is contacted by the lever 162 as the chuck is tilted upwardly to actuate the switch.

Manual stop 1.70 is provided in L1 to stop the operation of the machine in case of an emergency.

The present apparatus is directed to a device for:automatically ,finishing the bottom surface and inside corners of a generally rectangular container in a single operation. in the automatic operation, the workpiece and the chuck are moved in a given direction of travel and the abrading head is moved across the workpiece in a separate and distinct pattern of travel to finish thelentire bottom surface and inside cornersof the workpiece.

The apparatus can readily be adapted to polish various sized workpieces by merely interchanging chucks. Each chuck is designed to support a particular size of workpiece, and if it is desired to polish a workpiece of greater or lesser length, the original chuck 'is removed from engagement with rails 9 and asecond chuck, corresponding in size to that of the workpiece to be polished, is inserted on the rails. As the width of a stainless steel sink is generally standard for all models and only the l rigth is changed for largeror smaller sizes, the reciprocating stroke of the abrading head :4 is not adapted to be varied to .any great extent, except for minor adjustments through bearing .129 or the connection of rod 128 with block 13.0.

Due to the resilient connection between "the carriage plate 65 and contact plate 79, the contact wheel :67 floats with respect to the carriage plate and :CfinzfOllGW irregularities in the surface of the workpiece. The wheel flisplacethe belt 66 vertically in accordance with vertical movement of the contact wheel as the same follows the surface contour of the workpiece, and thereby keeps the belt under a given degree of tautness.

The drive and support system :for the endless belt :66 provides the contact wheel 67 with a pick-up action which enables the wheel to freely ride over irregularities in contour of the workpiece without binding. If, for instance, the wheel 67 :contacts an irregularity sufiicient to cause the belt to bind, the driving force on the belt tends .to pull the wheel upwardly and enables the wheel to walk over the irregularity to release the belt.

.As .thecontact wheel '67 is located at the end of the long rod 84, the apparatus is particularly adaptable 'for polishing or otherwise .finishing the inner surfaces :of a deep container. Furthermore, as the belt 66 is confined by the

rollers

76 and 77 .and extends substantially 'ver- :tically to the contact wheel 67, an excellent view of the grinding :area is provided during the polishing operation.

While the above description is directed to the polishing of a workpiece, such as a stainless steel sink, it is contemplated that the apparatus can be employed to grind, abrade, bufi, polish or otherwise finish a workpiece formed of any desired material, such as metal, wood, ceramics, glass, etc.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming .the subject matter which is regarded as the invention.

1 claim:

.1. An apparatus for polishing or otherwise finishing the bottom surface and the curved inner corners of a generally rectangular container, comprising a frame, a chuck supported by the frame and adapted to carry the container to be polished, ahead supported by the "frame, a work member carried by the head and adapted to engage the container to polish the same, means for lowering the head to bring the work member into contact with the container at the start of the polishing opera tion and for raising the head to withdraw the work member from contact with the container at the comple tion of the polishing operation, drive means to move the chuck relative to the frame in a given linear direction normal to the :axis of said chuck, and second drive means acting in synchronization with said first drive rneans for reciprocating the head in a direction generally normal to the direction of movement of said chuck to move the work member across the surface of the container as the container moves with the chuck to polish said container.

'2. An apparatus for polishing or otherwise finishing the bottom surface and the curved inner corners of a generally rectangular container, comprising a frame, a chuck supported by the frame and adapted to carry the container to be polished, a head supported by the frame, an abrasive work member carried by the head and adapted to engage the container to polish the same, drive means to :move the chuck relative to the frame in .a given linear stroke of travel normal to the axis of said chuck, second drive means acting in synchronization with said first drive means for reciprocating the head in a direction generally normal to the stroke of travel of said chuck to move the work member across the surface of the container as the container moves with the chuck to polish said container, and means for pivoting the chuck with respect to the frame at the end of the stroke of travel about an axis disposed parallel to the direction of reciprocation of the head to enable the work member to polish the radius of curvature of said corner.

3. An apparatus for polishing or otherwise finishing the bottom surface and the curved inner corners of a generally rectangular container, comprising .a frame, a chuck supported by the frame and adapted rtotcarry the container to be polished, a head supported by the flame,

a work member carried by the head and adapted to engage the container to polish the same, drive means to move the chuck in a given linear direction normal to the axis of the chuck, second drive means acting in synchronization with said first drive means for reciprocating the head in a direction generally normal to the di rection of movement of said chuck to move the work member across the surface of the container as the container moves with the chuck to polish said container, and means responsive to the operation of said second drive means for raising the work member out of contact with the container on every alternate stroke of reciprocation of said head.

4. An apparatus for polishing the inner surfaces of a generally rectangular workpiece having a bottom surface and a plurality of side wall surfaces with the inner corners of said container joining said bottom surface and said side wall surfaces having a given radius of curvature, comprising a frame, a chuck supported by the frame and adapted to carry the workpiece to be polished, a head supported by the frame, an abrasive contact wheel supported by the head and adapted. to engage the inner surfaces of the workpiece to polish the same, said contact wheel having a radius substantially equal to the radius of curvature of the corners of the workpiece and the periphery of said contact wheel being curved in the direction of the axis of the wheel with said periphery having a radius of curvature substantially equal to the radius of said contact wheel, drive means to move the .chuck in a given linear stroke of travel normal to the axis of the chuck, second drive means to rotate said contact wheel, third drive means acting in synchronization with said first drive means for reciprocating said head in a direction generally normal to the stroke of travel of the chuck to thereby move the contact wheel across the surface of the workpiece and into the opposite corners thereof extending generally parallel to the direction of chuck movement to polish the same, and means .for pivoting the chuck relative to the frame at the end of the stroke of travel about an axis disposed generallyparallel to the direction of reciprocation of the head when said corner is disposed in substantial vertical alignment with the contact Wheel to thereby polish the entire radius of curvature of said corner.

5. An apparatus for polishing the inner surfaces of a generally rectangular container having a bottom surface and four side walls and having a pair of first curved inner corners joining a pair of opposite side walls to the bottom surface and having a pair of second curved inner corners joining the other pair of opposite side walls to said bottom surface, comprising a frame, a chuck support member, a chuck supported by the chuck support member and adapted to carry the container to be polished, a head supported by the frame, an abrasive contact wheel supported by the head andadapted to engage the inner surfaces of the container to polish the same, said contact wheel having a radius adapted to be substantially equal to the radius of curvature of the corners of the workpiece, drive means to move the chuck relative to the chuck support member in a given direction, second drive means to rotate said contact wheel, third drive means acting in synchronization with said first drive means for reciprocating said head in a direction generally normal to the direction of chuck movement to thereby move the contact wheel across the surface of the container and into the first named corners thereof to polish the same, and means for pivoting the chuck upwardly relative to said chuck support member about the center of curvature of a second corner when said second corner is disposed in substantial vertical alignment with the contact wheel to thereby polish the entire radius of curvature of said second corner.

6. A polishing apparatus for polishing the bottom surface and the curved inner corners of a generally rec- ,tangular container, comprising a frame, a chuck supported by the frame and adapted to carry the container to be polished, a head supported byv the frame, a work member carried by the head and adapted to engage the container to polish the same, drive means to move the chuck relative to the frame in a given linear direction disposed generally normal to the axis of the chuck, second drive means acting simultaneously with said first drive means for reciprocating the head in a direction generally normal to the direction of movement of said chuck to move the work member across the surface of the container as the container moves with the chuck to polish said container, a pivotal support member connected to the chuck and adapted to be disposed in axial alignment with the center of radius of curvature of a corner of the container extending generally normal to the direction of chuck movement, stop means for preventing movement of the chuck in said given direction when said pivotal support member is disposed in vertical alignment with said work member, and means for pivoting the chuck about said pivotal support member to enable the work member to polish the radius of curvature of said corner of the container.

7. A polishing apparatus for polishing the bottom surface and the curved inner corners of a generally rectangular container, comprising a frame, a chuck supported by the frame and adapted to carry the container to be polished, a head supported by the frame, a work member carried by the head and adapted to engage the container to polish the same, drive means to move the chuck in a given direction, second drive means acting simultaneously with said first drive means for reciprocating the head in a direction generally normal to the direction of movement of said chuck to move the work member across the surface of the container as the container moves with the chuck to polish said container, a

rail connected to the frame, a plurality of rollers connected to the chuck and disposed to ride on the rail as said chuck is moved with at least one of said rollers adapted to be disposed in axial alignment with the center of radius of curvature of a corner of the container extending generally normal to the direction of chuck movement, stop means disposed to be engaged by the chuck for preventing movement of the chuck in said given direction when said roller is disposed in vertical alignment with said WOI'k' member, and means for pivoting the chuck about the axis of said roller when said roller is in vertical alignment with the work member to enable the work member to polish the radius of curvature of said corner of the container.

8. An apparatus for polishing the bottom surface and the curved inner corners of a generally rectangular container, comprising a frame, a chuck supported by the frame and adapted to carry the container to be polished, a head supported the frame, a work member carried by the head and adapted to engage the container to polish the same, drive means to move the chuck in a given direction, second drive means acting simultaneously with said first drive means for reciprocating the head in a direction generally normal to the direction of movement of said chuck to move the work member across the surface of the container as the container moves with the chuck to polish said container, a pair of rails connected to the frame, a pair of forward rollers rotatably secured in axial alignment to one end of said chuck and a pair of rear rollers rotatably secured in axial alignment to the opposite end of said chuck, said forward and rear rollers disposed to ride on said rails to guide the chuck in movement, said forward rollers adapted to be disposed in axial alignment with the center of radius of curvature of a corner of the container extending generally normal to the direction of chuck travel and said rear rollers adapted to be disposed in axial alignment with the center of radius of curvature of the opposite corner, stop means disposed to be engaged by the chuck for preventing continued movement of the chuck in a forward direction when the axis of said forward rollers is disposed in vertical alignment with the work member, second stop means disposed to be engaged by the chuck for preventing continued movement of the chuck'in a rear direction when said rear rollers are disposed in vertical alignment with the work member, and means responsive to the engagement of the stop means by the chuck for pivoting the chuck upwardly about the axis of the pair of rollers disposed in vertical alignment with said work member to polish the entire radius of curvature of the corresponding corner of the container.

9. An apparatus for polishing or otherwise finishing the bottom surface and the curved inner corners "of a generally rectangular container, comprising a frame, a head supported by the frame and having a Work member adapted to engage the container to polish the same, drive means for reciprocating the head in a given direction, a chuck adapted tosupport the container to be polished, a roller rotatably connected to the chuck and disposed to ride on the frame, said roller adapted to be disposed in axial alignment with the center of radius of curvature of a corner of the container extending generally parallel to the direction of reciprocation of the head, an endless drive chain, sprocket means connected to the chuck and disposed in axial alignment with said roller for engaging the chain and driving the chuck in a given path of travel generally normal to the direction of reciprocation of the head to move the container across the path of movement of the work member to thereby polish the surface of said container, a stop member associated with the frame, a plate slidably connected to the chuck and having a portion disposed to be engaged by said roller to permit said plate to be moved with the chuck and having a second portion disposed to engage said stop member and thereby stop the movement of the chuck in said path of travel, and means responsive to the engagement of said stop member by said second portion for pivoting the chuck about the axis of said roller to enable the work member to polish the radius of curvature of said corner of the container.

10. A polishing apparatus for polishing the bottom surface and the curved inner corners of a generally rectangular container, comprising a frame, a head supported by the frame and having a work member adapted to engage the container to polish the same, drive means for reciprocating the head in a given direction, a chuck adapted to support the container to be polished, a pair of rails connected to the frame, a'pair of forward rollers rotatably secured in axial alignment to one end of said chuck and a pair of rear rollers rotatably secured in axial alignment to the opposite end of said chuck, said forward and rear rollers disposed to ride on said rails to guide the chuck in movement, said forward rollers adapted to be disposed in axial alignment with the center of radius of curvature of .a corner of the container extending generally normal to the direction of chuck travel and said rear rollers adapted to be disposed in axial alignment with the center of radius of curvature of the opposite corner, drive means for moving the chuck in a path of travel extending generally normal to the direction of reciprocation of said head, a stop member connected to the frame, a plate associated with the chuck and slidably disposed thereto, said plate having a projection adapted to engage said stop member and thereby stop movement of the chuck in said path of travel, said projection being located with respect to the stop member such that said projection engages ,said stop member when the axis of the corresponding pair of rollers is centered beneath the work member, and means for pivoting the chuck upwardly about the axis of the pair of rollers centered beneath the work member to polish the entire radius of curvature of the corresponding corner of the container.

11. A polishing apparatus for polishing the bottom surface and the curved inner corners of a generally rectangular container, comprising a frame, a chuck supt4 ported by the frame and adapted to carry the container to be polished, -a head supported by the frame, an at rasive contact wheel carried by the head and adapted to engage the inner surfaces of the container to polish the same, said contact wheel having a radius substantially equal to the radius of curvature of the corners of the container and the periphery of said contact wheel be- .ing curved in the direction of the axis of the wheel with said periphery having a radius of curvature substantially equal to the radius of said contact wheel, drive means to move the chuck in a direction generally parallel to the axis of the contact wheel, second drive means acting simultaneously with said first drive means for reciprocating the head in a direction normal to the direction of movement of said chuck to move the contact wheel across the surface of the container and into the corners of the container extending generally parallel to the direction of chuck travel, a pivotal support member connected to the chuck and adapted to be disposed in axial alignment with the center of radius of curvature of a corner of the container extending generally normal to the direction of chuck movement, stop means for preventing movement of the chuck in said given direction when said pivotal support member is disposed in vertical alignment with said contact wheel, and means for pivoting the chuck about said pivotal support member to enable the contact wheel to polish the radius of curvature of said last named corner of the container.

12. A polishing apparatus for polishing a workpiece,

comprising a base, a chuck supported 'by the base and adapted to carry the workpiece, drive means for moving :the chuck in a given *path of travel,'a post secured to the base and extending upwardly therefrom, a guide rail connected to the post and extending outwardly from the post in a direction generally normally to the direction of chuck travel, a carriage movably :mounted on the guide rail, an abrasive member supported by the carriage and adapted to engage the workpiece to polish the same, and second drive means for reciprocating the carriage on the guide rail simultaneously with movement of the chuck with said abrasive member moving across the surface of the workpiece to polish the same.

13. A polishing apparatus for polishing a workpiece, comprising a base, a chuck supported by the base and adapted to carry the workpiece, drive means for moving the chuck in a given path of travel, a'post secured to the base and extending upwardly therefrom, a guide rail connected to the post and extending outwardly from the post in a direction generally normal to the direction of chuck travel, a carriage movably mounted on the guide rail, an abrasive contact wheel supported by the carriage, means for biasing the contact wheel into engagement with the workpiece and maintaining engagement of the contact wheel and the workpiece regardless of irregularities in the contour of said workpiece, "second drive means for reciprocating the carriage on the guide rail simultaneously with movement of the chuck to thereby move the contact wheel across the surface of the workpiece to polish the same, and means for raising and lowering the guide rail and carriage with respect to the chuck to permit insertion and removal of the workpiece from the chuck. I

14. A polishing apparatus for polishing a workpiece, comprising a base, a chuck supported by the base and adapted to carry the workpiece, drive means for moving the chuck in a given path of travel, a post secured to the base and extending upwardly'therefrom, a guide railiconnected to the post and extending outwardly from the post in a direction generally normal to the direction of chuck with said abrasive member moving across the surface of the workpiece to polish the same, means for raising and for lowering the guide rail and carriage with respect to the chuck to permit insertion and removal of the workpiece from the chuck, and means separate from said last named means for moving the abrasive member out of contact with the workpiece on every alternate stroke of reciprocation of the carriage.

15. An apparatus for polishing or otherwise finishing a workpiece, comprising a guide member, a carriage movably mounted on said guide member, an endless abrasive belt, belt support means associated with the carriage for supporting the belt in endless travel, contact support means connected to the carriage for supporting the belt and adapted to urge the belt against the workpiece to polish the same, second belt support means associated with the guide member for supporting the belt in endless travel and disposed on opposite sides of the carriage, drive means for moving the belt in endless travel, and second drive means for reciprocating the carriage on said guide member simultaneously with travel of said belt to polish the surface of the workpiece.

16. An apparatus for polishing a workpiece, comprising a guide member, a carriage movably mounted on said guide member, an endless abrasive belt, belt support means associated with the carriage for supporting the belt in endless travel, a contact wheel connected to the carriage and disposed to support the belt and adapted to urge the belt against the workpiece to polish the same, a pair of belt'support rollers associated with the guide member with one of the support rollers disposed on each side of the carriage, drive means acting through one of said support rollers for moving the belt in endless travel, and second drive means for reciprocating the carriage on said guide member simultaneously with travel of said belt to polish the surface of the workpiece.

17. An apparatus for polishing a workpiece, comprising a guide member, a carriage mounted for reciprocation on said guide member, a contact support member connected to the carriage and disposed for limited vertical movement with respect to said carriage, an endless abrasive belt, belt support means associated with the carriage for supporting the belt in endless travel, a contact member connected to the contact support member and disposed to support the belt and adapted to urge the belt into contact with the workpiece to polish the same, second belt support means associated with the guide member for supporting the belt in endless travel, drive means for moving the belt in end-less travel, second drive means for reciprocating the carriage on said guide member simultaneously with travel of said belt to polish the surface of the workpiece, and means for moving the contact support member upwardly with respect to the carriage on each alternate stroke of reciprocation of the carriage to lift the contact member and belt out of engagement with the workpiece.

18. An apparatus for polishing a workpiece, comprising a base, a chuck supported by the base and. adapted to carry the workpiece, drive means for moving the chuck in a given path of travel, a post secured to the base and extending upwardly therefrom, a guide rail connected to the post and extending outwardly from the post in a direction generally normal to the direction of chuck travel, a carriage mounted for reciprocation on said guide rail, a contact support member connected to the carriage and disposed for limited vertical movement with respect to said carriage, an endless abrasive belt, belt support means associated with the carriage for supporting the belt in endless travel, a contact wheel connected to the contact support member and disposed to support the belt and adapted to urge the belt into contact with the workpiece to polish the same, a belt support roller connected to the contact support plate and disposed above said contact wheel, a pair of belt support members connected to the guide nail with one of said belt support members disposed on each side of the carriage plate, said belt support mem- .bers supporting the 'belt for endless travel and being fixed with relation to the guide rail, second drive means for moving the belt in endless travel, third drive means for reciprocating the carriage on said guide rail simultaneously with movement of said chuck and with travel of said belt to polish the surface of the workpiece, and hydraulic fluid means for raising the contact support member and said contact wheel and belt support roller upwardly with respect to the carriage on each alternate stroke of reciprocation of the carriage to thereby withdraw the belt fromcontact with the workpiece on said alternate stroke.

19. A polishing apparatus for polishing the inner surfaces of a generally rectangular container, comprising a base, a chuck supported by the base and adapted to carry the container to be polished, a head connected to the base and disposed generally above said chuck, an abrasive belt supported for endless travel by said head and adapted to engage the container to polish the same, chuck drive means for moving the chuck in a given path of travel, head drive means for reciprocating the head in a direction generally normal to the direction of chuck travel, belt drive means for driving the belt in endless travel, means for lowering the head toward the chuck to engage the abrasive belt with the containenmeans responsive to a given amount of downward movement of the head to actuate the chuck drive means and start the chuck travel, means responsive to a second given amount of downward movement of the head to actuate the head drive means and the belt drive means and begin reciprocation of the head and travel of the belt, means responsive to the chuck reaching an end point and its path of travel for stopping said chuck drive means and raising the head upwardly away from the chuck, and means responsive to a predetermined amount of upward movement of the head for stopping the head drive means and the belt drive means to thereby stop the reciprocation of the head and the travel of the belt.

20. A polishing apparatus for polishing the inner surface of a generally rectangular container, comprising a base, a chuck supported on the base and adapted to carry the container to be polished, a head connected to the base and disposed generally above the chuck, an abrasive belt supported for endless travel by the head and adapted to contact the container to polish the inner surfaces thereof, chuck drive means for driving the chuck in a given path of travel with the chuck being pivoted upwardly about a corner of the container at the end of its path of travel, head drive means for reciprocating the head in a direction generally normal to the direction of chuck travel,

belt drive means for driving the belt in endless travel, switch means, means responsive to closing said switch means for lowering the head toward the chuck to eflect engagement of the endless belt with the container, stop means for limiting the downward movement of the head with respect to the chuck, means responsive to a given amount of downward movement of the head to actuate said chuck drive means and start the chuck travel, means responsive to a predetermined amount of downward movement of the head to actuate said head drive means and belt drive means to begin reciprocation of the head and travel of the belt, means for raising the abrasive belt out of contact with the container on every alternate stroke of reciprocation of the head, means responsive to the 'chuck pivoting upwardly at the end of its stroke of travel for stopping said chuck drive means and for raising the head upwardly from the chuck, means responsive to a predetermined amount of upward movement of the head for stopping said head drive means and belt drive means to thereby stop the reciprocation of the head and the belt travel. i p i 21. A polishing apparatus for polishing the inner surfaces of a generally rectangular container, comprising a base, a chuck supported by the base and adapted to carry the container to be polished, a head connected to the base and disposed generally above said chhclcan abrasive belt supported for endless travel by; said head and adapted to engage the container to polish the same, chuck drive means for moving the chuck in a given path of travel, head drive means for reciprocating the head in a direction generally normal to the direction of chuck travel, belt drive means for driving the belt in endless travel, means for lowering the head toward the chuck to engage the abrasive belt with the container, means responsive to a given amount of downward movement of the head to actuate the chuck drive means and start the chuck travel, means responsive to a second given amount of downward movement of the head to actuate the head drive means and the belt drive means and begin reciprocation or the head and travel of the belt, means responsive to stopping of said chuck drive means for raising the endless abrasive belt out of contact with the container and reventin gouging of the container in event the chuck drive means Sta-11S, means res onsive to the chuck reaching an end point in its path of travel for stopping said chuck drive means and raising the head upwardly away from the chuck,- and means responsive to apredetermined amount of upward movement of the head for stop ing the head drive means and the belt drive means to thereby stop the reciprocation or the head and the travel of the belt.

22. An apparatus for polishing a workpiece, comprising a frame, an endless abrasive belt, belt support means connected to the frame for supporting the belt in endless travel, a contact member connected to the frame and disposed to support the belt and force said belt against the workpiece to polish the same, means for resiliently mounting the contact member with respect to the frame" to permit the contact memberto oscillate relative to the frame and follow irregularities in the" contour ofthe workpiece, and means operably connected to the contact member and disposed in engagement withsaid belt for displacing the belt in the direction or movement of said Contact member to maintain the belt under a given degree of tautness during the oscillatory movement of the contact member.

23. An apparatus for polishing a workpiece, comprising, a support member to support the workpiece to be polished, a frame, an endless abrasive belt, belt support means connected to the frame for supporting the belt in endless" travel, a' second frame slidably' connected to the first frame and having an elongated end portion, a contact member connected to the elongated end portion and disposed to support the belt in endless travel, second belt support means connected to the second frame and disposed on the opposite side of said first belt support means from the contact member for supporting the belt in endless travel, and resilient means for urging the elongated end portion axially outward with respect to the first frame to bias the contact member toward the workpiece, said resilient means permitting the contact member and said second belt support means to move relative to the first frame and thereby enable the contact member to follow irregularities in the contour of the'workpiece and maintain the belt under a given degree of tightness during movement of the contact member.

24. A method of polishing a generally rectangular workpiece having a bottom surface and a plurality of sidewall surfaces with the inner corners of said container joining said bottom surface and said side walls having a given radius of curvature, comprising, tilting the workpiece to an angle to the horizontal and posi-' tioning the center of the radius of curvature of a first inner corner of the workpiece in substantial vertical alignment with an abrading member, reciprocating the abrading member in a direction generally parallel to said first inner corner to polish the same, pivoting the workpiece to a generally horizontal plane while continuing the reciprocation of the abrading member, moving the workpiece in said horizontal plane and in a direction generally normal to the direction of reciprocation of the abrading inner corner Of member to polish the bottom surface or the workpiece, and hiring the war-piece upwardly about the center of the radius of curvature of .the inner corner disposed opposite to. said first inner corner when said center is positioned in vertical alignment with said abrading mem her to polish the opposite inner corner of said workpiece.

25. A method of polishing a generally rectangular workpiece having a bottom surface and a plurality of side wall surfaces with the inner corners of said container joining saidbottom surface and said side walls having a given radius of curvature, comprising, tilting the workpiece to an angle to the horizontal and positioning the center of the radius of curvature of a first the workpiece in substantial vertical ali nment with an abrading" member, reciprocating the abrading member in a direction generally arallel to said first inner corner, engagin the abrading member with the workpiece on every alternate sti'oke of reciprocation of the head to polis'hthe workpiece, pivoting the workpiece to a generally horizontal plane while continuing the reciprocation or the abrading member, moving the workpiece in said horizontal plane and in a direction generally normal to the direction of reciprocation of the abrading member to polish the bottom surface of the workpiece, and tilting the workpiece upwardly about the center of the radius of curvature of the inner corner disposed opposite to said first inner corner when said center is positioned in vertical alignment with said abrading member to polish the opposite inner corner of said workpiece.

26. A method of polishing a generally rectangular workpiece having a bottom surface anda plurality of side wall surfaces with the inner corners of said co tainer joining said bottom surface and said side walls having a given radius of curvature, comprising-tilting the workpiece to an angle to the horizontal and posi tioning the center of the radius of curvature of a first inner corner of the workpiece in substantial vertical alignment with an abrading member, resiliently biasing the abrading member into reciprocating the abrading member in a direction generally parallel to said first inner corner to polish the same, pivoting the workpiece to a generally horizontal plane while continuing the reciprocation of the abrading member, moving the workpiece in said horizontal plane and in a direction generally normal to the direction of reciprocation of the abrading member to polish the bottom surface of the workpiece, and tilting piece upwardly about the center of the radius of curvature of the inner corner disposed opposite to said first inner corner when said center is positioned in vertical alignment with said abrading member to polish the 0pposite inner corner of said workpiece.

27. A method of polishing a workpiece having a bottom surface and at least one side wall with the inner corner of the container joining the bottom surface of the side wall having a given radius of curvature, comprising reciprocating an abrasive member in a given plane, disposing the bottom surface of the container in a second plane generally normal to said given plane, engaging the abrasive member with the bottom surface to polish the same, moving the workpiece in said second plane and in a direction at an angle to the direction of reciprocation of the abrasive member to thereby polish the bottom surface of the container, and tilting the workpiece about the center of the radius of curvature of the corner when said center is positioned in alignment with the abrasive member to polish said inner corner of the workpiece.

28. A method of polishing a workpiece having a bottom surface and a pair of opposite side walls with the inner corners of the container joining the bottom surface and the side walls having a given radius of curva- 'turc, comprising reciprocating an abrasive member in a given plane, tilting the workpiece to an angle to said contact with the workpiece, I

the workgiven plane and engaging one of said inner corners with fvthe abrasive member to polish said corner, pivoting the ;workpiece.to a plane generally normal to said given plane, moving the workpiece in said last named plane and in a direction generally normal to the direction of reciprocation of the abrasive member to polish the bottom I surface of the workpiece, and tilting the workpiece about the center of the radius .of curvature of the corner disposed opposite to the first'named corner when the center 1 of the second named corner is positioned in alignment "with the abrasive member to polish said second named corner of the workpiece. I

29. An apparatus for polishing a workpiece compris- -ing, a supporting frame including a guide member, a

carriage slidably connected to the guide member and adapted to move thereon, an endless abrasive member, first support means associated with the frame and disposed on either side of the carriage and adapted to sup port the endless member in endless travel, drive means mounted on the frame and connected to one of said first support means to drive the endless member, second sup- .port means disposed on said carriage and disposed to support the endless member in endless travel, a contact member disposed to support the endless member, a sliding member slidably mounted on the carriage and supporting the contact member, resilient means for urging the sliding member outwardly with respect to the carriage to bias the contact member toward the workpiece, I displacement support means attached to said sliding member and cooperating with said second belt support members on said carriage for taking up the slack in the endless member as the contact member follows irregularities in the contour of the workpiece, and means to move the carriage on said guide member to thereby move the contact member across the surface of the workpiece to polish the same.

30. An apparatus for polishing a workpiece, comprising a supporting frame including a guide member, a carriage slidably connected to the guide member and I adapted to move thereon, an endless abrasive belt, a pair of rollers associated with the frame and located on either side of the carriage and disposed to support the belt in endless travel, a motor mounted on the frame and connected to one of said rollers to drive the endless belt in endless travel, belt-tensioning means associated with the other'of said rollers for maintaining the belt under a given degree of tautness, a plurality of belt supporting rollers disposed on the carriage and adapted to support the belt in endless travel, a sliding member slidably mounted on the carriage, a contact member secured to the end of said sliding member and adapted to support the belt in its travel, resilient means for urging the sliding member outwardly of the carriage to thereby bias the contact member toward the workpiece, said sliding member mounted to slide in a direction generally normal to the direction of movement of said carriage on said guide member, a displacement rollersecured to said sliding member and located on the opposite side of said support rollers from said contact member, said displacement roller adapted to move in accordance with said sliding member and immediately take up the slack in said belt as the contact member engages irregularities in the surface of the workpiece, and means for moving the carriage on said guide member to move the contact member across the workpiece to polish the same.

31. The structure of claim 29, in which the second belt support means includes four support rollers disposed in generally rectangular arrangement on said carriage and said sliding member is disposed centrally of said rectangular arrangement and the displacement means comprises a roller located on the opposite end of the sliding member from said contact member and being positioned out of the periphery of the rectangular arrangement of said rollers.

32 A method of polishing a workpiece, comprising reciprocating an abrasivemember in a given plane, dis- References Cited in the file of this patent UNITED STATES PATENTS UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Noe. 2 932 926 April 19 1960 Peter- Mo Dreiling I'b-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 71 for "spare" read square i Signed and sealed this let day of November 1960 (SEAL) Attest:

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