US2267521A - Grinding and polishing apparatus - Google Patents

Description

C. M. GRIFFIN GRINDING AND POLISHING APPARATUS Dec. 23, 1941.

Filed March 15, 1940 6 Sheets-Sheet 1 4 Dc. 23,1941. c. ,M'. GRIFFIN GRINDING AND POLISHING APPARATU S Filed March '15, 1940 6 sheets sheet 2 INVENTOR Dec. 23, 1941. I c. M. GRIFFIN GRINDING AND POLISHING APPARATUS Filed March 13, 1940 s sheets-sheet 3 I 5 i -64 I I 1 I L INVENTOR o k I -JO v w I V I 43 7m E 4 I; I

Dec. 23, 1941. c. M. GRIFFIN 2,267,521

GRINDING AND POLISHING APPARATUS Filed March 13, 1940 6 Sheet-Sheet 4 Dec. v23,1941.

c. M. GRIFFIN GRINDING AND POLISHING APPARATUS 6 Sheets-Sheet 5 7 Filed March 13, 194p Patented Dec. 23, 1941 UNITED STATE GRINDING AND POLISHIING APPARATUS Clyde M. Griffin, Mount Lebanon, Pa., assignor to Minnesota Mining & Manufacturing Company, St. Paul, Minn., a corporation of'Delaware Application March 13, 1940, Serial No. 323,747

12 Claims.

My invention relates to the art of grinding, scouring, polishing and cleaning the surfaces of metal strips, or sheets, fiat wire, the dressing of rolls etc., and is hereinafter described .as employed in the surfacing of long strips of metal such as those produced on continuous rolling mills, and the surfacing and cleaning of rolls. It will be; understood, however, that various features of the invention can advantageously be, employed in the surfacing of other articles, such as a succession of flat sheets.

By the use of my invention, the steel strip or other work piece is subjected to identical abrading or surfacing action at all points throughout the areathereof, thus not only giving absolutely uniform surface appearance or finish to the work, but insuring that all parts of the work will be abraded to the same degree or depth. This latter feature is particularly important in the surfacing of light gauge materials, and where uniformity and evenness of finish is desirable, regardless of the strip steel gauge, and where it is desired to remove tough or tightly adhering corrosive film, oxides or other foreign matter,

which will be cut through and removed by the abrasive, from the surface area which sometimes has shallow pits or similar defects.

Another object of my invention is to provide a method and apparatus of generally simplified and improved form, for the surface treatment of metal.

Broadly stated, my invention comprises means for constantly feeding or supplying an abrasive strip to the work to be surfaced, and at the same time imparting thereto smooth uninterrupted movement of the abrasive strip at an accuratelycontrolled speed, whereby fresh abrasive is constantly supplied to the work piece at a predetermined rate and smoothness of movement, so that the surfacing operation will be absolutely uniform on all surface areas of the work piece.

The arrangement, in one form, consists of a rubber-covered steel'roll for holding or pressing the abrasive strip against the work piece and is usually termed a contact or presser roll. This roll is driven at a relatively slow. peripheral speed, the range of which is usually from 1 to 12" per minute, whereas in the case of abrading of steel sheet or strip, the'speed of the steel would ordinarily vary from approximately 150 feet to 750 feet per minute. The frictional drag of the steel strip or other work piece tends to revolve the contact roll in the direction in which the steel is moving, the roll being retarded in this ply roll, between the presser roll and the work piece, it being also passed between the presser roll and a snubbing roll that is so positioned as to hold the abrasive strip in tight contact with a large portion of the circumference of the presser roll. This large area of contact between the abrasive strip and the presser roll serves to prevent slippage of the sanding strip on the presser roll and to therefore insure smooth or uniform rate of travel of the abrasive strip.

Figure 1 is a face view of one form of appa ratus used in the practice of my invention; Fig. 2 is an end view thereof; Fig. 3 is an end view showing a modification of the apparatus of Figs. 1 and 2; Fig. 4 is a view showing another manner in which the abrasive strip may be supplied to the work and movement thereof retarded to a desired speed; Fig. 5 shows still another manner of imparting frictional resistance or drag to the abrasive strip; Fig. 6 is a vertical sectional view showing a form of apparatus suitable for use in the polishing of rolling mill rolls, taken on the line VIVI of Fig. 7 Fig. 7 is a plan view thereof; Fig. 8 shows a manner of moving the abrasive strip oppositely to movement of the work, and

Filgl. 9 is a sectional view ,of a soft-faced presser ro Referring first to Figs. 1 and 2, the apparatus is shown as employed in the grinding and polishing of continuous strip steel that is continuously advanced past the abrading elements by the use of suitable feed rolls indicated diagrammatically by the numerals H and I2, the strip being drawn from a reel or direct from a rolling mill. It will be understood that the feed rolls are indicated only diagrammatically and that means such as additional feed rolls or takeup (winding) reels will be provided for exerting pulling force on the steel strip to move it against the frictional resistance of the abrasive elements.

It will also be understood that a plurality of sets of abrasive units may be mounted in position to successively operate upon the steel strip, as for example, in'rough grinding, intermediate grinding and final surfacing, in continuous sequence. Sheets'or other articles, instead of conmovement by means of a high ratio gear reduccorner post for supporting the apparatus. The

lower ends of the uprights I3 are rigidly connected together by a channel I4 that extends crosswise of the framework, and the upper ends thereof are similarly connected by a channel I5.

At each end of the channel I4, a pillar I6 is mounted in the framework and serves as a'support for certain shaft bearings and other portions of the apparatus. Apillow block I! is mounted on each of the pillars I and carries bearings for a shaft I5 that carries a presser roll I9 and a shaft which carries a snubbing 'roll 2I, which exerts some light pressure against the roll I9, but

can be positioned in spaced relation thereto.

A reel 22 is idly joumalled in a pair of brackets 23 that are secured to the framework of the machine and has a strip 24 of sandpaper, emery cloth or other suitable surfacing material wound thereon, the strip 24 passing in a counterclockwise direction past the roll 2|, thence between the rolls 2| and I9 and finally across the top of the roll I9 and beneath the steel strip I0.

The snubbing roll 2| is preferably positioned so that the abrasive strip will have contact with the presser roll I9 through at least 180 of its circumference, to provide frictional area sufficient to prevent slippage, whereby the strip will move at the same speed as the periphery of the roll I9. It has been found in practice that a relatively light pressure of the snubber roll against the presser roll is usually sufficient when the included wrapped angle of contact of the strip with the roll is 180 or more, although a lesser angle of wrap will be satisfactory if the pressure of the snubber roll against the presser roll is increased. The element 2| may suitably be in th form of a stationary snubbing device instead of an idlingly-mou'nted roll.

The roll I9 is driven froma variable-speed motor 26 that is secured to one of the pillars I6; through a speed reducing unit 21, a pair of bevel gear wheels 28, one of which is mounted on a worm shaft 29 and a worm gear 35. The motor speed and gear reduction is such that the roll I9 will turn quite slowly relative to the rate at which the work piece I 0 travels. For example, 7"

the steel strip may travel at anywhere from 50 feet per' minute to 500 feet per minute, while the peripheral speed of the roll I9 and consequentlythe rate of travel of the abrasive strip 24 may b at a rate of only six inchesper minute to 18 inches per minute, the relative rates of speed being adjusted in accordance with the character of abrasive which is employed and the rapidity with which the abrasive becomes worn through contact with the work, and also in. accordance with the degre of pressure exerted upon the abrasive strip. The presser roll I 9 may be faced with semi-hard rubber, cork or other suitable material, to a thickness of about inch, or may be entirely of metal. For light grinding and finishing of a steel strip, the facing on the presser rolls can suitably have a durometer gauge hardness of from 20 to 90. For rough grinding, the hardnesscan be greater.

It will be seen that as the strip I0 moves forwardly, it will exert a "drag upon the abrasive surface of the strip 24, tending to move said' abrasive strip along with the steel strip, but since the presser roll I9 is restrained by the motor to a relatively low rate of speed, the high speed I of the steel strip as compared to the abrasive element will result in abrasion of the under surface of the strip I0.

By means which will be hereinafter described,

- the pressure. at the contacting surfaces of the abrasive strip 24 andthe steel strip It can be regulated to a desired degree. For example, the pressure and differential in'speed will usually be such that the abrasive will be completely consumed upon one pass thereof in contact with the work piece. At any rate, the abrasive strip is paid out at a predetermined rate of speed relative to the speed at which the steel strip I 0 travels, with the result that there is absolute uniformity in the rate at which fresh or unused abrasive surface is supplied to the steel strip, and with consequent absolute uniformity in degree of abrasion.

A pair of bearing brackets 32 are slidably supported upon the uprights L3 and carry bearing blocks 33 suspended therefrom. In these bearing blocks 33 is journaled a shaft 34 that carries an upper presser roll 35 which corresponds to the lower presser roll I9. A shaft 36 is journaled in the bearing members 33 and carries a snubbing roll 31. I

A motor 40 is secured to one of the bracket members 32 and operates through a gear reducing unit 4| to drive a pair of bevel gear wheels 42, a worm 43 and a worm gear 44, the worm gear 44 being secured to the shaft 34.

A shaft 46 is loosely journaled in a pair of brackets 41 that are secured to the members 32 and has a supply of an abrasive strip 48 coiled thereon. The strip 48 passesover the snubber roll 31; between the roll 31 and the presser roll 35, and beneath the roller 35-with its abrasive surface in contact with the steel strip I0. The motor 40 will control the rate at which the abrasive strip is drawn from the supply on the shaft 46, through the drag exerted by the steel strip. While the rollers 2I and 31 are idly journaled in the framework, they produce a snubbing effect since they hold the abrasive strips in contact with a large part of the circumferential surfaces of the presser rolls, to thus prevent slipping of the abrasive strips on such rolls.

A base plate 50 is mounted upon the framework and at each end thereof supports a cylinder 5I that is held in place by a top plate 52 and tie bolts 53. Pipes 54 and 55 serve as a means for supplying pressure (either air or liquid) to the upper and lower sides of a piston 56 contained within the cylinder 5|. Piston rods 51 are connected with the bracket members 32, so that as the pistons move up and down, the presser roll 35 and the other parts that are carried by the brackets 32 will also be moved up and down. This arrangement not only serves as a convenient means for separating the presser rolls so that access can be had thereto for replacement etc., but the fluid pressure admitted to the upper side of the piston 56 can be so regulated that a desired degree of pressure will be produced as between the abrasive strips and the steel strip I0.

Each of the bearing brackets 32 is supported one. pair of springs 51a that are interposed between extensions 53 carried by the bearing brackets and spring seats 59 on the uprights I3. These springs are of suflicient resistance to support the weight of the members 32 and the parts carried thereby, and will, of course, be compressed when fluid pressure is admitted to the upper side of the piston 56, so that very light pressure as well as very heavy pressure can be exerted at the presser rolls I9 and 35 upon the abrasive strips and the work piece.

The abrasive pressure which it is desired to exert can readily be regulated to substantially any desired degree. For example, in the surfacing of what is termed "dead soft carbon steel either unplated, or plated with copper, nickel,

'chrome, etc., a very few pounds of abrasive pressure will be used, as ordinarily it will be desired not to cut through the plated surface or' to abrade too harshly the soft carbon steel surface. In the case of hard steel or steel having a hard surface, abrasive pressures up to several thou-- an emery-faced abrasive strip is employed, a

greater area of contact can be had for a given amount of pressure than where a coarser abrasive is employed. There are commercially available sources of sandpaper and the like which will not tear under pressures as great as 1250 lbs. per square inch abrasive pressure, so that very great pressure can be employed and the abrasive entirely consumed upon one pass.

The travel of the abrasive strip to the work piece is constantly retarded to a desired rate of speed, and this retarding resistance to move-. ment of the paper under frictional drag of the work piece can be maintained at approximately the maximum tensile and tear strength of the abrasiv strip. Even though the drag exerted on the abrasive strip is suflicient to tear or shear it frequently, the abrading action is nevertheless uninterrupted because a fresh supply of new abrasive is-accurately and continuously fed into the abrading zone.

The reason for this appears to be that the tearing or shearing of th abrasive strip generally occurs just in or slightly past the abrasive zone where the presser roll bears upon the steel strip or other work piece, and since the presser rolls l9 and 35 are positively driven, new abrasive is continuously fed into the abrasive zone. Again, the abrasive strip will preferably .be of one-fourth inch to one inch wider than the steel strip or other work piece so that even though the abrasive strip is torn in the zone of abrasion, there is an untorn portion at each edge thereof which serves to assist in advancing the unused portion of the abrasive strip.

Furthermorethe instant that the abrasive strip breaks, the motor, through the presser, roll, exerts a feeding force on the abrasive strip instead of retarding it, the motor thus being at all times constantly effective to cause proper rate of strip feed.

In Fig. 3 I show apparatus wherein the framework and th mountings for the various rolls are substantially the same as in Figs. 1 and 2, but

wherein there is a different arrangement of rolls past which the sandpaper is fed. In this structure, presser rolls 8!! and BI serve to hold the abrasive strips 24 and 48 against the upper and lower faces respectively of the steel strip Ill, but instead of being positively driven as are the presser rols l9 and 35 of Fig.1, are idly mounted and turn through the drag exerted by the strip 1,0 and the paper strips 24 and 48. l

The abrasive strip 24 passes below and around a snubber roll 62 and backwardly and across a feed roll 63and thence between the roller and the steel strip l0, all of said rolls being journaled in theframework of the :machine. The roller 63 is driven from 'a motor 54 through suitable reduction gearing and a chain 65, the peripheral speed of such roller being much les than the rate of travel of the steel strip ID, the feed roller 63 and the snubber roller 62 serving to prevent too rapid advancingmovement of the abrasive strip under th drag of the steel strip l0.

. As indicated in the drawing, the bearings 62a of the roll 62 are slidable in the openings in the end members l6a in which the bearings are supported, and the 'feed roll 63 is preferably of a I diameter not less than three inches, though here shown as much larger, the purpos of a sufficientlylarge diameter being to avoid too sharp bend-- ing and possible cracking of abrasive strips that that rests directly upon the roll of abrasive strip and is maintained in place thereon by a pair of lugs 23a that project upwardly from the brackets 23 at the ends of the'machine. This resistance to unreeling of the abrasive strip will, when an additional pulling stress is imposed on the strip to such extent that it slips on the roll 63, cause th roll 62 and its bearings to be slid toward the roll 63, thus causing the roll 62 to hold the strip more firmly against the roll 63, and thus stop slippage of the strip thereon.' Thereby accidental slipping of the strip through unusual frictional drag of. the steel strip is automatically caused to cease.

By producing the snubbing' or retarding force on the steel strip by the use of the rolls 62 and 63, instead of utilizing the roll 62 and the presser roll (ill as in Figs. 1 and 2, I am enabled to employ presser rolls of various diameters, since the snubbing action will not be dependent upon an area of frictional contact between the abrasive strip and the presser roll. For example, when a small width of contact at the zone of. abrasion is required, a sufficiently smal1 presser roll can engagement, thus permitting of greater unit pressure area and sharper cutting action, because the individual grains of abrasive will stand out more prominently at the zone of abrasion, and there will be less loading of the abrasive strip at. said zone. For example, the presser roll may be made less than three inches in diameter.

In this Fig. 3, the abrasive strip 48 is paid out or fed to the upper surface of the work ill in the same manner as the strip 24, it passing around .a snubbing roll 66 and back around the feed roll 61 and from thence beneath the roller 6| where its abrasive surface will be pressed into contact with the upper face of the steel strip Ill. The roll 61 is driven from a motor 68 through suitable reduction gearing and a chain 69 at a slow rate of speed relative to the travel of the strip Ill. While the rolls 62 and 66 have been designated as snubber rolls and the rolls 63 and 61 as feed rolls, it will b seen that both the rolls 63 and 6'! serve as snubbing rolls to prevent too rapid withdrawal of the abrasive strips and to insure withdrawal thereof at a-desired speed, depending upon the rate at which the motors 64 and 68 turn, it being desirable to have these motors of the variable speed type. In this structure, as in the structure of Figs. 1 and 2,

vertically through the use of cylinders and pistons, so as to eifect a desired degree of abrasive pressure and also a desired abrasive area at the zones of contact between the rolls and the strips, where yieldably-faced presser rollers are employed.

It will be seen that the abrasive residue which is worn from the strip through the drag of the work piece, and the particles'of abraded metal, are carried away from the point of contact and harmlessly discharged, with minimum danger of loading the unused abrasive at the area of contact with the work. The worn ends of the paper can be torn off and discarded after it passes from beneath the presser rolls, or can be wound up on take-up reels. The abrasive residue that remains on the strip I after it passes through the presser rolls will be wiped or blown therefrom. V

Referring now to Fig. 4, I show another means for snubbing or frictionally-retarding the movement of the abrasive strips 24 and to presser rolls 1| and I2 and the work piece I0. In this arrangement, as in the case of Fig. 3, the presser rolls are idly mounted so that they will freely rotate under the frictional drag of the steel strip I0. The movement of the abrasive strips under the frictional drag of the steel strip I8 is retarded by pinch rolls I3 that are journaled on the frame work of the machine and whose shafts carry worm gears I4 with which the worms on a shaft I5 have driving engagement. The shaft I5 is in turn driven through a worm gear unit I6 and bevel gears I1 from a motor I8. The motor speed and the gear reduction are such that the abrasive strips will be drawn along' slowly relative to the rate at which the steel strip travels, since the pinch rolls engage the strip tightly enough to prevent slippage thereof in such rolls.

In Fig. 5 I show an arrangement wherein only the upper surface of the steel strip I8 is surfaced, the strip being supported from beneath by a billy roll 88 which will be mounted in suitable bearings and which may be either hard or soft faced. In this case, the presser roll '8I may be driven in a manner similar to that in which the presser roll 35 is driven. The snubber roll 82, however, is adjustable so of snugness or tightness with which the abrasive strip 48 is held in contact with the presser roll.

as to vary the degree To this end, the roller 82 is supported at each end by a bracket arm 83 that is pivoted at 84 to the framework of the machine. A pressure-adjusting screw 85 has threaded .engagement with a block or bushing 86 that is secured to the machine. The screw 85 extends through and is rotatable in the bracket arm 83 and has a head at its lower end, so that as the screw is rotated, the snubber roll will be moved toward or away fromthe presser roll 8I. This arrangement has the further advantage that if the snubber roll 82 at one end bears more lightly or heavily against the presser roll than at its other end, a proper adjustment of the screws can be made to correct the misalignment. The roll of abrasive strip 48 0f.Fig. 5 can be retarded by use of a weighted roll 22a as in Fig. 3, particularly when roll 82 is set in spaced relation to the roll 8|.

I have found it desirable, particularly in the finer grinding and finishing operations, to apply a coat of oil to the surface of the strip. The oil may be applied either by the use of brushes, dipping of the sheet, or by spraying. The use of 2,287,631 .the roll-supporting member 32 is adjustable the oil is desirable where there is tendency for scale and other loose material to accumulate between the abrasive strip and the steel strip at.

the front side of the pass. The oil, of course, adheres to the 'steel strip and it serves as a carrier to cause movement of the loose particles through the roll pass. Where the abrasive strip is of such nature as not to be seriously affected by water, water can be employed instead of oil.

Referring to the apparatus shown in Figs. 6 and 7, for the polishing and cleaning of rolling mill rolls, a conventional form of roll stand is shown, which comprises a pair of housings 9| in which are journaled a pair of rolls 82 and 83 for the hot or cold rolling of a metal strip 84. The polishing apparatus can be detachably connected to the housings 9|, or can be brought into position for polishing the rolls whenever desired. In the case of continuous strip roll ng. I may desire to have the polishing apparatus remain in position during rolling operations, the abrasive strip being occasionally put into use, as may be required.

It will be understood that not only can an abrasive strip be used of a character which will clean scale and grease from the roll, but grit of such nature may be employed that the usual abraded pattern will be ground or cut on the roll surface.

' The polishing apparatus comprises a base plate 95 that is secured to the rolling mill foundation by bolts 96 that extend through slots in the base plate. The base plate has upstanding portions 91 and 98 at the ends thereof, the upper portions of which are connected by a tie plate or brace bar 99. These uprights serve to support the bearings sup plying and feeding the abrasive strips to the rolls 92 and 93.

Inthe lower portion of the uprights 91 and 98, a shaft I00 is mounted for carrying a roll of sandpaper IOI, which is drawn around beneath a snubber roll I82 that is journaled in the uprights and then passes over a roll I03 and between such roll and the 'roll 92. The roll I83 is driven by an electric motor I04 that is mounted on a bracket I05 which is secured to the upright 98 through a gear reduction unit I 86, bevel gearing I81, a worm I08 and a worm gear I08 that is figured to the shaft IIO, which carries the roller The rollers I82 and I03 serve as snubbing devices to retard the movement of the abrasive strip I8I under the drag of the roll 92, the roll 92 having a much higher peripheral speed than the rate at which the abrasive strip is drawn or fed. The motor I04 is preferably of the variable speed type, so that it can be driven to produce a desired differential rate of speed as between the roller I83 and the roll 92. t

A similar arrangement of apparatus for feeding' an abrasive strip II2 to the top roll 93 is mounted in the upper portion of the uprights 81 and 98, and comprises a motor II3 secured to the upright 88 and operating through bevel gear wheels H4 and worm gearing II5 to drive a roll II8 which corresponds to the roll I03 and serves to control the rate at which the strip II2 will be drawn from the supply roll II 1 past a snubber roll II8.

Adjustment of the base plate 95 and the parts carried thereby toward and from the rolls 82-83 of screws I20, each of which is threaded in opposite directions at its ends and has threaded engagement with upstanding for the shafts that carry the rolls for 4 or out of operative position.

lugs I2I and I22 on the support for the roll stand andthe edge ,of the base plate 95, respectively, so that when the screws are turned. the base plate and the parts carried thereby will be slid toward or away from the rolls 92 and 93, to effect desired degrees of abrasive pressure, or to move the abrasive strip-supplying apparatus into It will be seen that when the abrasive strips are paid out or fed at a uniformly slower rate of speed than the rate of rotation of the rolls 92 and 93, there will be absolute uniformity in abrading action and truly cylindrical contour ofthe mill rolls maintained.

While I have herein shown presser rolls for holding the abrasive strips in contact with the work piece, it will be understood that I can use other presser devices such as shoes which would offer but little frictional resistance to the smooth side of the abrasive strips as compared to the frictional drag of the work piece.

Referring now to' Fig. 8, I disclose apparatus whereby the abrasive strip 48 may be moved in a direction counter or opposite to that in which the steel strip III is advanced. the directions of travel of these two elements being indicated bythe arrows.

While the abrasive strip feeding apparatus is shown as placed. to operate on only the upper surface of the work piece III, it will be understood that the apparatus can .be duplicated at the underside of the work piece. However, for simplicity of description, I have shown a billy roll I24 which will be journaled on a suitable base and may be idling y mounted, the billy roll being either hard or soft faced and serving to support the strip against the pressure of a presser roll I25. The abrasive strip 48 is drawn from a supply reel I26 mounted in suitable bearings (not shown). The presser roll is driven in a manner similar to the pres'ser rolls of Figs. 1 and 6, from a motor I21 through bevel gearing I28 and worm gearing I29, preferably at a slower rate of speed than that at which the work piece III travels.

The abrasive strip 48 is held wrapped partially about the presser roll I25, by a snubber roll I35, so as to have greater frictional contact with the presser roll than the frictional drag exerted by the work piece Ill upon the abrasive grains. A

take-up reel I30 that comprises a shaft I3I mounted in suitable bearings (not' shown) is so positioned as to hold the abrasive strip in partially wrapped engagement with the presser roll I25. .A pulley I32 is secured to the shaft HI and is driven by a belt I33 from a pulley I34 that has connection with the motor shaft. The belt I33 is of suiiicient looseness to permit easy slippage of the pulley I34. The driving force exerted through the belt I33 need be sufficient only to wind up the worn abrasive strip on the shaft I3I and to maintain such strip in a taut condition between the take-up reel and the presser roll.

In this arrangement, as in the various other structures heretofore described, the presser roll may have a-facing of soft material, as indicated in Fig. 9, wherein the roll shaft is indicated by the numeral I36, its metal body portion by the numeral I31 and its rubber sleeve bythe numeral I38.

' I claim as my invention:

1. Surfacing apparatus comprising a presser roll for holding an abrasive strip in contact with a work piece, means for moving the work piece,

means for driving said roll at a slower rate of peripheral speed than the rate at which the work piece moves, and a snubber roll located between the source of abrasive strip supply and the presser roll, positioned to maintain the abrasive strip in snug engagement with such circumferential area of the presser roll that the strip will have a greater degree of frictional engagement therewith than the frictional drag exerted by the work piece upon the strip, the adjacent surfaces of the work piece and the presser roll moving in the same general direction.

2. Surfacing apparatus comprising a presser roll for maintaining an abrasive strip in contact with a work piece,'means for moving the work piece, a supply roll from which the abrasive strip i drawn' through frictional contact with the work piece, retarding rolls interposed between the supply roll and the presser roll, the retardingrolls engaging opposite faces, of the strip with such force as to prevent slippage of the strip on the rolls, and means for so controlling the rotation of the retarding rolls that the peripheral speeds thereof will be slower than the rate at which the work piece moves.

3. Surfacing apparatus comprising a presser roll for maintaining an abrasive strip in contact with a work piece, means for moving the work piece, a supply roll from which the abrasive strip is drawn through frictional contact with the work piece, pinch rolls engaging the strip at a point intermediate the presser roll and the supply roll with sufficient force toprevent slippage of the strip, and means for driving the pinch strip in snug engagement with such circumferential area of the presser roll that the strip will have a greater degree of frictional engagement therewith than the frictional force exerted by the work piece upon the strip, the adjacent surfaces of the work piece and the presser roll moving in the same general direction, and means for adjusting the presser roll to vary the degree of 7 pressure exerted thereby upon the abrasive strip and the work.

5. Surfacing apparatus comprising, a presser roll for maintaining an abrasive strip in contact with a moving workpiece, means for supporting a quantity of abrasive strip as a source of supply, a snubber roll located between the source of abrasive strip supply and the presser roll, for deflecting the strip and maintaining it under a greater degree of frictional engagement with said .rolls than the frictional force exerted by the work piece upon the strip, the adjacent surfaces of the work piece and the presser roll moving in approximately parallel paths, and means for moving one of said rolls at a slower peripheral speed than the rate atwhich the work piece travels.

6. Apparatus for surfacing steel mill rolls and the like when they are revolving, comprising a roll containing a supply of abrasive strip, a presser roll for holding the abrasive strip in contact with a mill roll, a snubbing device intermediate the supply roll and the presser roll, positioned to produce a greater frictional drag on the strip than the frictional force exerted by the mill roll, and means for driving th presser roll at a slower peripheral speed than the peripheral speed of the mill roll.

7. Apparatus for surfacing steel mill rolis and the like when they are revolving, comprising a roll containing a supply of abrasive strip, a presser roll for holding the abrasive strip in contact with a mill roll, a snubbing roll intermediate the supply roll and the presser roll, positioned to produce a greater frictional drag on the strip than the frictional force exerted by'the mill roll, and means for driving one of the two second named rolls at a peripheral speed slower than the peripheral speed of the mill roll.

8. Apparatus for surfacing steel mill rolls and the like when they are revolving, comprising a roll containing a supply of abrasive strip, a presser roll for holding the abrasive strip in contact with a mill roll, a snubbing device intermediate the supply roll and the presser roll, positioned to produce a greater frictional drag on the strip than the frictional force exerted by the mill roll, means for driving the presser roll at a slower peripheral speed than" the peripheral speed of the mill roll, and-means for adjustably supporting the supply roll and the presser roll in a rolling mill stand.

9. Surfacing apparatus comprising a presser roll for maintaining an abrasive strip in contact with a moving work piece, a snubber roll for engaging the strip located between the source of abrasive strip supply'and the presser roll, and positioned to maintain it under a greater degree of frictional engagement with one of said rolls than the frictional force exerted by the work piece, the adjacent surfaces of the work piece and the presser roll moving in approximately parallel paths, and means for constantly rotating the said frictionally-engaged roll at a slower peripheral speed than that at which the work piece moves. I

10. Surfacing apparatus comprising means for imparting travelling movement to strip material past a given zone, a presser roll for maintaining an abrasive strip in contact with the said material, a snubber roll located between the source of abrasive strip supply and the presser roll, for engaging the abrasive strip and positioned to maintain it under a greater degree of frictional engagement with one of said rolls than the frictional force exerted by the said material. the adjacent surfaces of the material and the presser roll moving in approximately parallel paths, and means for constantly rotating the said frictionally-engaged roll at a slower" peripheral speed than that at which the strip material travels 11. Surfacing apparatus comprising means for supporting a work piece, an abrasive element, a presser roll for holding the abrasive element against the work piece, bearing brackets for the presser roll, means yieldably supporting the brackets and the presser roll above the work piece, and means for applying a fluid pressure force to the presser roll, for urging it toward the work piece in opposition to the said yieldable support.

12. Surfacing apparatus comprising means for supporting a work piece, an abrasive element, a presser roll for holding the abrasive element against the work piece, bearing brackets for the presser roll, means yieldably urging the brackets and the presser roll in a direction from the work piece, and means for applying a fluid pressure force to the presser roll, for urging it toward the work piece in opposition to the said yieldable means.

CLYDE M. GRIFFIN.

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