US2666282A

US2666282A - Method of conditioning metal sheets, strips, rods, and the like

Info

Publication number: US2666282A
Application number: US221906A
Authority: US
Inventors: Ruben O Peterson
Original assignee: Osborn Manufacturing Corp
Current assignee: Osborn Manufacturing Corp
Priority date: 1951-04-19
Filing date: 1951-04-19
Publication date: 1954-01-19
Anticipated expiration: 1971-01-19

Description

Jan. 19. 1954 R. O. PETERSON METHOD OF 2,666,282 CONDITIONING METAL SHEETS, STRIPS, RODS, AND

THE LIKE Filed April 19'. 1951 5 Sheets-Sheet l O O O O O O O INVENTOR.

J MYIMD4 ATTORNEYS Jan. 19, 1954 Filed April 19, 1951' R. O. PETERSON METHOD OF CONDITIONING METAL SHEETS, STRIPS, RODS, 'AND THE LIKE 3 Sheets-Sheet 2 I INVENTOR. RUBEN OJPETERSO/V OLM M 6'7 7 OQNEYS.

ONDITIONING METAL SHEETS, STRIPS, RODS, AND

THE LIKE 3 Sheets-Sheet 5 Filed April 19, 1951 .2 v: 000000000 Q Q A, N: .w: 8 .E

Q m: o 1/ 8. 8. .l .mm

0 O 0 m: m9 .,o O mo. g 0 J R l 00000090 8. 8 KW r, 0 og mm 9 o 09 mm o wQ INVENTOR. RUBEN O.PETERSON Jaw ATTORNEYS Patented Jan. 19, 1954 METHOD OF CONDITIONING METAL SHEETS, STRIPS, RODS, AND THE LIKE Ruben 0. Peterson, University Heights, Ohio, as-

' signor to The Osborn Manufacturing Company,

Cleveland, Ohio, a corporation of Ohio Application April 19, 1951, Serial No. 221,906

' 7 Claims. 1 The present invention relating as indicated to the conditioning of metal sheets, strip, rod and the like has more particularregard to means and methods for attaining such beneficiating effects as the removal of scale and other closely adherent coatings and small slivers, and the rounding of the sharp edges of small pits and scratches, and reducing differences in hardness and associated physical qualities of small adjacent surface areas and small adjacent subsurface component formations, and cleaning and polishing the surface, and reducing surface tension on such articles by brushing action and by the conjoint action, on the surface being treated, of a brush and of auxiliary materials such as abrasive, peening pellets, cleaning and coating materials.

' The addition of an abrasive to a brushing operation in order to clean the surface of a metal sheet or like article by an ordinary scouring operation is, of course, well known. Thus, floors have been long cleaned and polished in this manner. It has also been proposed to clean sheet metal plates (see Patent No. 451,263 to Buckman) by similarly supplying an abrasive, e. g. sand, to the surface of the sheet in advance of the application thereto of a rotary brush. However, such simple scouring treatment has not proved effective for the removal of closely adherent oxide coatings, such as heat formed scale, from sheet or strip steel or rod, in order to prepare such metal for further reduction as by rolling or drawing or to prepare the surface of such metal for plating with another metal, such as tin or zinc, or to receive and retain a paint, lacquer, or enamel coating, without employing more costly, objectionable and less beneficial pickling processes.

An aspect of the continuing roblem presented, of scale removal by a brushing operation, is evidenced by Patents Nos. 1,440,619 to Noyes et a1. and 2,335,196 to Pecsok, which respectively disclose different methods of applying a brush to the surface of a sheet in an endeavor to secure complete scale removal. But other aspects include the removal of small slivers and the sharp edges of pits and scratches which are not removed by prior methods and which when not removed become, upon subsequent rolling, drawing, or the like, the sources of miniature seams and the starting points of fractures when an articlemade from the metal sheet, strip or rod is subjected to stresses of manufacture and use. Also a phase of the problem involves the minimizing of differences in hardness and associated physical qualities of small adjacent surface areas and small adjacent subsurface component formations, which differences, when permitted to become exaggerated, reduce the facility with which the metal may be worked and reduce someof the desirable qualities of the articles made therefrom. Some commonly used methods and means, suchas for example scale-breaking and subsequent pickling to remove the scale, exaggerate such differences and therefore have serious detrimental effects while achieving the main objective.

As indicated above, one object of the present invention is to combine brushing action with application of an abrasive material in such a manner as will effectually accomplish the removal of scale, small slivers, and other objectionable surface irregularities from metal sheets, strip, rod and similar articles. I have discovered that if such abrasive material be forcibly discharged onto the surface of a sheet simultaneously with the application of a brush thereto or immediately in advance of such application, not only is the cleaning action greatly improved but the power required for brushing greatly reduced. I have further discovered that where, as will be desirable, a rotary brush is employed, such brush itself may be utilized thus forcibly to discharge, by centrifugal action, the abrasive material onto the surface of the sheet without detracting from, but on the contrary greatly increasing, the chiciency of the brushing action proper.

While in the case of metal sheets and strip,

they will at times desirably be arcuately flexed to present a convex surface to the brush, as taught by the above-cited Pecsok patent, the present improved method of conditioning sheets, etc., is not limited to such procedure but may be utilized in connection with fiat sheets, strips or'like articles or with sheets or strips arcuately flexed to present a concave surface to the brush. Furthermore, in such method I may utilize abrasive material either in dry granular form having variousdegrees of fineness or such abrasive may be carried by a suitable liquid vehicle. The invention further comprehends improved means for conducting the abrasive in either such form to the brush in such manner as to utilize the centrifugal action of the latter to forcibly discharge the abrasive onto the sheet.

To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully described and particular- 7 1y pointed out in the claims, the annexed drawings and the following description setting forth in detail certain means and one mode of carrying out the invention, such disclosed means and modes illustrating, however, but one of various ways in which the principle of the invention may be used.

In said annexed drawings: v

Fig. 1 is a diagrammatic side elevational view of one form of apparatus constructed in ac- 3 cordance with the present invention and showing a metal strip in process of being acted upon thereby;

Fig. 2 is a central longitudinal section of one of the brushes, shown as being utilized in such apparatus, wherein the centrifugal action of the brush is utilized to discharge granular abrasive material onto the sheet being treated;

Fig. 2a shows a detail of Fig. 2 on larger scale;

Fig. 3 is a transverse section of such brush, the plane of the section being indicated by the line 3-3, Fig. 2; a

Fig. 4 is a diagrammatic side elevational view of one form of apparatus constructed in ac cordance with my invention and showing a metal strip in process of being acted upon thereby.

Referring to the construction of apparatus illustrated in Fig. 1, such apparatus will be seen to comprise two rolls l and 2, about which the metal strip S is passed in such manner that each side of the strip will be respectively subjected to the action of rotating cylindrical brushes 3 and 4 which are disposed with their axes respectively parallel to the corresponding rolls (which may be disposed at desired angles to the longitudinal axis of the strip) and so spaced in relation thereto that the brushes will contact with the arcuately flexed portions of the sheet as it passes over and is supported by said rolls respectively. The rolls I and 2 of course are rotated in the same direction as that in which the sheet S moves in passing thereover and the brushes 3 and 4 will be rotated in a direction opposite to that of the rolls, i. e. in the same direction as that in which the strip moves while in contact with the latter, or in a reverse direction, or alternately first in one direction and then in another for short periods of time. Certain brush materials work best when they are continually sharpened by alternately operating the brush first in one direction and then in the other. Also, the direction of operation of a brush determines which sides of pits or scratches and corresponding sharp edges of which will be most effectively rounded by a given brush. It is, therefore, desirable to em ploy several brushes and to have their respective directions of operation so adjusted and periodically alternated as to have their effective operational directions adjusted to several different related angles. be power driven, either by direct motor drive or otherwise as found desirable or convenient, the brushes preferably being rotated rapidly, for example at approximately 3000 R. P. M. in the case of a 12 in. diameter brush, which will be approximately equal to an average of 9000 F. P. M. during the useful life of the brush, while the strip of course moves at a much lower speed, relative to the speed at which the contacting brush surfaces travel. Brushes larger than 12 inches in diameter will often be preferred.

For the purpose of feeding the sheet to the rolls I and 2, as it is received from roller conveyor 5 it passesbetween relatively adjustable bending rolls 6, I and 8 which serve to arcuately bend the strip to a curve of somewhat greater diameter than that of roll I. .The strip then passes between guide rollers 9 and 10, which direct it into substantially tangential relationship to the surface of the roll directly opposite brush 3. Beyond the roll I the strip passes between rollers II and 12, which are disposed in a relationship to said roll complementary to that of rollers 9 and I0.

As a result of the disposition of the two pairs The rolls and brushes will 1 of guide rollers the area of contact of the sheet S on its concave side with the roll I is limited substantially to that of the area of contact of its convex side with the opposed rotating brush 3. The brush will be set no more tightly against the sheet or strip S than necessary to obtain the desired efiect, since the coefficient of friction be tween the brush and the strip increases more rapidly than the square of the pressure, and the power consumption is of course a factor of importance. Over-brushing of the metal surface furthermore may have detrimental effects in forming characteristic irregularities and removing and displacing too much metal.

Directly below the point of tangency of roll 5 and brush 3 is an exhaust collector l3 adapted to receive the particles of scale removed from the sheet by the action of brush 3 as well as additional granular abrasive material which, as will presently be described, will be supplied to the brush for use as in the treatment of the sheet. A suction fan 14, connected with collector I3, serves to convey the abrasive including of such scale along a duct I5 in which is interposed a screen [6 whereby the larger particles are caught and collected in a trap ll. The remaining, finer particles of scale are delivered by duct 15 to a hopper 18 located conveniently adjacent brush 3 from which such abrasive particles may be supplied to the brush in the manner presently to be described.

Returning to the progress of the sheet S, after leaving guide rollers II and 12 it then continues between

bending rolls

20, 21 and 22, whereby it is arcuately bent in the opposite direction from that given it by the first-mentioned set of bending rolls and caused to tangentially engage roll 2 where its other side, now convex, is subjected to the action of brush 4. Disposed on opposite sides of roll 2 are complementary pairs of

guide rollers

23, 24 and 25, 26 which, like the previously mentioned pairs of guide rollers, serve to limit the area of contact which the strip or sheet S has with roll 2. Finally, the sheet is received between straightening

rolls

21, 28 and 29 which straighten the strip and enable it to continue in its original direction along the roller conveyor 30. Associated with brush 4 is a collector 3| and suction fan 32, which'are connected with a suitable hopper associated with brush 4 through a duct (not shown), in the same manner asin the case of the collector and hopper associated with brush 3. If brushes 3 and i are adapted to be periodically reversed in operation, as preferred, then of course similar collectors should also be provided at the other side of the brush.

As indicated, the rotary brushes 3 and 3 which are disposed to operate on the convexly flexed surface of the sheet as it moves through the apparatus will in effect be duplicates of each other, being designed to perform the same operation on opposite sides of such sheet; furthermore, each such brush is so constructed as to adapt the same to forcefully project abrasive material onto such convexly flexed surface of the sheet. A preferred construction of brush designed to operate in the manner just referred to is shown in Figs. 2, 3 and 2a, which will now be described. As there shown, the body of the brush comprises two oppositely

disposed hub members

35 and 36 respectively provided with bearing sleeves 35a and 36a whereby said members may be rotatably supported. in suitable journals. Fitted to said hub members is a cylindrical shell 31 that is provided with a suitable number of properly spaced perforations 38 "manner.

through the portion thereof lying between the hub members to permit the discharge outwardly through such shell of abrasive material supplied to the interior thereof. Mounted in turn on shell '31 is "a body 39 of radially extending stranded brush material. This material may constist of crimped wire of varyingdegrees of fineness, or

any of the other materials usually employed in brushing operations of the character involved, and may be secured to the shell in any approved As illustrated, such brush material is disposed in the form of doubled layers held by a retaining Wire or ring 40 in a channel form base 4| which may be either in the form of an annulus or wound helically about the shell. Retaining rings 42, 42 held in place by means of lock rings 43 'threaded on the respective ends of the shell press against the corresponding sides of the 'assembled body of brush material and serve both to'secure the latter to the shell and compact the same to the desired degree.

Where the brush material is held in a channel form base 4|, the sides of the latter, as shown in Fig. 2a, are formed with alternate depressed areas and intermediate lands so that radial passages will be left between adjacent bases (or sections of the base Where helically wound on the shell) and the number and disposition of the perforations 38 in the shell 3'! will be such that a'substantial portion, if not all, of the passages thus provided will coincide in location with such perforations so that abrasive supplied in the manner previously referred to may pass through the latter and such passages and thence outwardly in between the stranded brush material. relatively free flow of abrasive is further facilitated by rounding the lower corners of the channel form bases so that circumferential passages are provided between adjacent bases which will further insure connections between the per- 'forations in the shell and such radial passages.

The specific construction just described, whereby provision is made for the flow of abrasive from within the shell 31 into the body of stranded brush material, forms the subject matter of my Patent No. 2,409,309, dated October 15, 1946, and it will be understood that where different methods of attaching the stranded brushmaterial to the brush body are employed, other means for providing for such flow may require to be used. In

other words, the illustrated construction is to be considered merely as constituting one form of brush body wherein provision is made for such flow of abrasive from the interior thereof radially outwardly into the stranded brush material.

Further referring to Figs. 2 and 3, it will be seen that a tubular shaft 45 extends axially through the body of the brush, the ends of such shaft projecting beyond the

respective hubs

35 and 36. The intermediate portion of the shaft, i. e. that lying between such hubs within shell 31, is provided with a longitudinally aligned series of apertures 46 through which abrasive or other flowable material may be introduced into the hollow interior of the brush body. Such material may be supplied from any suitable source to the tube through either end thereof, the right-hand end being shown as selected for the purpose in Fig. 2. A'solid rod 41 inserted in the other end of the tubular shaft serves to close off such end and being reciprocable said rod may be utilized for the further purpose of cleaning out the in- Such terior of the shaft should it, or the openings 46 7 therein, become clogged.

Tubev 45 is not directly in contact with the openings in the hubs and 35, but the portion thereof lying within hub 35 is surrounded by a second tubular shaft, or rather sleeve, 48 which serves as a close fitting bushing within which such shaft may be angularly adjusted, i. e. rotated about its axis so as correspondingly to vary the angular position of the series of perforations in relation to the axis of the shaft. The portion of the shaft 45 which lies within hub 36 is similarly surrounded by a closel fitting tubular shaft 49 and said shaft 49 is in turn surrounded by a second tubular shaft or sleeve 5d, the function of which is the same as that of sleeve 48 except that, as indicated, said shaft s9 is interposed therebetween and the innermost tubular shaft 45. Said shaft 49 projects into the hollow interior of the brush body and desirably includes an axially spaced extension in the form of a separate ring 5| that lies adjacent the inner face of hub 35, and fixedly attached to these portions of said shaft 49 is a radially projecting wiper 52. While the latter may take on various forms, it will desirably consist, as best shown in Fig. 3, of a straight channelform base 53, similar to the base employed to hold the brush material comprised in brush body 39, and a doubled layer of stranded brush material which is secured in such base just as the previously mentioned brush material is secured in the channel bases 4!. The wiper thus constructed extends substantially across the space within shell 31 lying between the two

hubs

35 and 36 and is of such radial extent that its outer edge, which, where the blade is formed of stranded brush material, will consist of the ends of such strands, will frictionally engage with the inner face of said shell.

Shaft 49 is normally held against rotation by suitable means and as a result rotation of the inner face of the shell 31 about such wiper serves to clear the perforations 3B in such shell should they become cloggediyvhile the brush is in use. However, when desired, tubular shaft 49 which carries the wiper 52 may be rotated, or rather adjusted angularly, about the axis of said shaft so as to correspondingly vary the angular position of the wiper within said shell. Any suitable means may be provided for thus rotatably adjusting said shaft 45 and for retaining the same against rotation as desired, e. g. a worm gear 45a attached to the projecting outer end of the shaft and a worm 49b engaging said gear.

In order to facilitate insertion and removal of shaft 45 with the Wiper thus carried thereby, a radial slot 55 is cut in hub 35, such slot being of proper width to permit the ready passage therethrough of the blade, however constructed. When the blade is in its operative position, as shown in Figs. 2 and 3, such passage will be closed by a plug 55 that is held in place by meansof a flange on the bushing 35a.

While the wiper assembly must be inserted before the brush is placed in its bearings, thereafter the angular adjustment of the wiper can be made without disturbing the brush mounting. Likewise, the feeder tube 45 can be inserted and removed, as can also the reciprocable clean-out shaft or plug 41, all without disturbing the brush set-up.

The manner in which a brush constructed as just described isutilized in a brushing operation such as that illustrated in Fig. 1 will now be set forth. Assuming the open end of feed tube 45 f to be connected with a suitable supply of granular abrasive, or other material such as more fully set forth later herein, which may be carried by a stream of air or other suitable vehicle moving at proper velocity, such abrasive or the like will be carried into the hollow interior of the brush body and there be subjected to the centrifugal force occasioned by the high rate of rotation of such body when the brush is in operation. The effect will be to cause the abrasive to flow through the perforations 33 in shell 3'! and thence to discharge the same at an accelerated rate of movement through the stranded body of brush material. effectively controlled by rotating the feed tube so as to vary the angular direction of the openings therein, through which such abrasive is supplied to the hollow interior of the brush. Thus, for example, as such material is discharged from the stranded brush body, it can be directed onto the surface of the sheet being brushed along the line of contact of the brush therewith, or in ad- Vance of such line, as desired. Such direction of discharge may be further controlled by utilizing the wiper 52 as a deflector, to which purpose it is equally well adapted. In other words, by proper angular adjustment of the feed tube and of such wiper thus serving as a deflector, the angle at which the major portion of the abrasive will be discharged from the brush can be fairly closel controlled.

It is not necessary of course that all of the particles of abrasive should fall within a defined area on the sheet, but merely that the major portion thereof should do so. In order to catch such particles as may be thrown beyond the desired area, any suitable form of enclosure or guard may be employed. It will be further understood that while reference has been made in the foregoing description of the operation of my improved brush to the use of a granular abrasive conveyed b a stream of air, other media, including a suitable liquid, may be employed, such liquid carrying the abrasive being discharged in the same manner. Moreover, for certain purposes the material supplied to the brush for the purpose of thus being centrifugally discharged therefrom may consist wholly of a liquid medium capable of having a beneficiating effect on the surface of the sheet as it is being brushed.

While my improved method and. apparatus for surface beneficiating metal sheets and the like has been described with special reference to the removal of scale and like closely adherent coatings, no limitation to such particular use is to be implied. Thus, by employing other forms of discrete hard particles instead of granular abrasive, e. g. peening pellets of properly selected size, such method and apparatus may be equally well employed in the peening treatment of sheets and like metal particles.

In peening practice as at present carried out, while the impact of the pellets or shot has the desired effect of relieving surface tensions and otherwise beneficiating the surface of the article being treated, there is at the same time produced a disadvantageous effect arising from the presence of the crushed cementite and other constituents of steel. Where the broken fragments of such materials, which are relatively hard, remain on the surface, not only is the peening action interfered with but the surface itself may be permanently marred. However, by combining with the impact action of peening pellets a brushing action such as I am able to obtain, these objectionable products are immediately removed and a much more perfect surface condition obtained.

The direction of such discharge can be' Where peening pellets are employed, they will of course be fed onto the work-piece by means of the brush so as to be projected therefrom by centrifugal action of the latter in the same manner as the granular abrasive material previously referred to. Furthermore, as has hereinbefore been pointed out, my improved construction of brush and the method involved in its use may be found quite advantageous where instead of thus feeding discrete hard particles through the brush, other kinds of beneficiating materials, e. g. in liquid form, are thus applied to the surface of the article being treated, without carrying any granular abrasive or other additional material.

While the means and method hereinbefore described for centrifugally discharging abrasive or other beneficiating material onto the surface being treated, viz. by feeding the same into the interior of a brush rotating at high speed, thence to pass radially outwardly through the stranded brush material, are considered preferable, I have found a like effect may be obtained by supplying such material at the proper point or points on the surface of such a brush as more fully set forth in my co-pending application Serial No. 126,408, filed Novemer 9, 1949.

The term surface beneficiation as employed herein is to be understood as comprehending any of the several forms of treatment mentioned, e. g. cleaning, polishing, scale removal and relieving surface tension.

Referring now more particularly to Fig. 4, the apparatus in the form therein disclosed comprises two

rolls

92 and 93 about which the metal strip 94 is adapted to pass in such manner that each side of the strip will be respectively subjected to the action of

brushes

95 and 96. These brushes will generally be rotating at speeds in the vicinity of 9000 F. P. M. and their directions of rotation will desirably be periodically reversed, the rate of travel of the strip ordinarily being sufficiently slow that no consideration need be given thereto in this connection. The strip of course is moving at a much lower relative speed.

The end. of the strip approaches the machine sliding along conveyor 91 until it strikes large roll 92 whereupon the end of the strip is deflected and received between the surface of such roll and a small auxiliary roll 93 carried by a spring-backed mount 99 provided with an adjustable stop !00 operative to limit maximum movement of roll 98. Rotation of roll 92, which is driven from any suitable power source, then operates to pull the strip into the nip of the two rolls and the strip is driven forward against roll IOI which is mounted ina manner similar to roll 98 and very close to the latter (detailed mounting means not shown for purposes of clarity). The sheet is then driven onward between rolls 9.2 and .IOI and becomes arcuately bent through the interaction of

rolls

92, 98 and IOI to a radius substantially conforming to the surface of roll 92. The sheet next passes under a spring loaded shoe I02 carrying one or more rollers I03 similarly operable to bear upon the sheet. The smooth curved surface of shoe I02 adjacent roll 92 is sufficiently removed from roll 92 to afford ample clearance for passage of the strip but serves to deflect such strip should the latter fail closely to conform to the surface of roll 92. Spring I04 is effective to cause rollers I03 to bear on the strip with considerable pressure in order to maintain the latter in tight engagement with roll 92 as it passes beneath brush 95. A second spring loaded shoe I05 provided with similar rollers I06 cooperates in maintaining the strip in close engagement with roll 92.

The strip then passes over pulley roller I 01 and follows conveyor I09 to roll 93 where it passes between roll 93 and rolls 98, 10!, I03, and [09, these rolls corresponding in mounting and function to the similar rolls above described. Deflector I I starts the strip from roll 93 whereupon it passes between rolls Ill, H2, and H3 which have a straightening effect upon the strip which now resumes its course in its original direction along conveyor H4. driven similarly to roll 92, either through a train of gears or alternatively by means of a separate electric motor, for example, which may be caused to turn roll 93 at a slightly greater speed than roll 92 to aid in keeping the strip tight.

Directly below the point of tangency of roll 92 and brush 95 is an exhaust collector H5 adapted to receive the particles such as scale discharged by the action of the brush. An appropriate blower H6 forces the scale along duct Ill to screen H8 where the larger particles are caught and collected in trap H9. The finer particles of scale are carried to hopper I20 from the bottom of which they are fed or preferably forced to the outer periphery of the rapidly rotating brush 95. In other words, the material in question may thus be supplied to the work either by a controlled gravity feed of any usual type or by an air blast of familiar construction, and the material maybe thus discharged against the surface of the strip being treated with only a portion being delivered to the periphery of the brush prior to engagement with such strip. A similar system, the parts of which are identified by like numerals, is provided for brush 96. Since the details of the system form no part of the present invention, it has been considered unnecessary to illustrate other than in diagrammatic fashion the specific construction of feeding means, whether gravity or air blast, thus associated with hoppers I20.

This application is a continuation-in-part of I my co-pending application Serial No. 668,391

filed May 9, 1946, in turn a continuation-in-part of Serial No. 632,831 filed December 5, 1945, and Serial No. 437,648 filed April 4, 1942; and also of my co-pending application Serial No. 126,408 filed November 9, 1949. Such applications Serial Nos. 437,648; 632,831; and 668,391 have been abandoned without prejudice in favor of this present application.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such be employed.

I therefore particularly point out and distinctly claim as my invention:

1. In a method of removing scale from a metal sheet, the steps which comprise flexing the sheet, brushing the convex face of the latter, and simultaneously supplying to the face thus being brushed an abrasive consisting substantially entirely of previously removed scale particles.

2. In a method of removing scale from a metal sheet, the steps which comprise flexing the sheet, brushing the convex face of the latter, collecting the particles of scale removed from such sheet by such brushing operation, and supplying such particles to the face of the sheet while subjected to such brushing step.

Roll 93 may be to such brush in such relation as to be projected thereby onto such convexly flexed surface.

5. The method of removing scale from a metal sheet which comprises progressively flexing such sheet convexly to raise the edges of the scale particles, and forcefully projecting abrasive material in a general tangential direction onto such convexly flexed portion of the sheet.

6. The method of removing scale from a metal sheet which comprises progressively flexing such sheet convexly to raise the edges of the scale particles, brushing such convexly flexed portion of the sheet normal to the line of flexing throughout such line, and simultaneously forcefully projecting abrasive material in a general tangential direction onto such convexly flexed portion of the sheet.

7. The method of removing scale from a metal sheet which comprises progressively flexing such sheet convexly to raise the edges of the scale particles, brushing such convexly flexed portion of the sheet normal to the line of flexing throughout such line, and simultaneously supplying abrasive material to such brush in such relation as to be projected thereby onto such convexly flexed portion of the sheet.

RUBEN O'. PETERSON.

References Cited in the file of this patent UNITED STATES PATENTS Name Date Wooster Oct. 6, 1868 Hall et a1 Feb. 5, 1884 Buckman Apr. 28, 1891 Lindsey Dec. 29, 1891 Nelson Feb. 21, 1893 Muller Nov. 10, 1903 Broderick Oct. 29, 1907 Miller Oct. 23, 1923 Miller Nov. 20, 1923 McCrery Oct. 25, 1932 MacGregor Oct. 30, 1934 Berger Aug. 11, 1936 Quinn May 23, 1939 Lynch May 23, 1939 Minich Aug. 29, 1939 Jesser Sept. 19, 1939 Coddington May 14, 1940 Hershey et al Nov. 12, 1940 Wallace July 15, 1941 Quigley et al Apr. 7, 1942 Wood Apr. 14, 1942 Stanier et al May 4, 1943 Pecsok Nov. 23, 1943 Yoder Dec. 25, 1945 Barnes Oct. 28, 1947 Stone Dec. 16, 1947 Anderson Apr. 18, 1950 Number FOREIGN PATENTS Number