US2853245A

US2853245A - Mill roll scraper

Info

Publication number: US2853245A
Application number: US504210A
Authority: US
Inventors: Jacobson Abner
Original assignee: Individual
Current assignee: Individual
Priority date: 1955-04-27
Filing date: 1955-04-27
Publication date: 1958-09-23
Anticipated expiration: 1975-09-23

Description

Sept. 23, 1958 A. JACOBSON MILL ROLL SCRAPER 2 Sheets-Sheet 1 FIG. 2.

led April 27, 1955 INVENTOR. 145N497? l/AC0550/V BY Sept. 23, 1958 A. JACOBSON MILL ROLL SCRAPER 2 Sheets-Sheet 2 Filed April 27, 1955 5 v, 4 mm ME 7 T 0 a N m5 mp VB m m Mr A W F 1 5 m N 4 w a United States Patent"- MILL ROLL SCRAPER Abner; Iacnbsong. Shaker. Heights, Ohio Application Aprili27,1955,,SerialjN0. 504,210 liClalmst (61;;241-467) The present invention, relates to i'mproved'millroll apparatus. and more. particularly. to floating scraper apparatus adapted to redistribute the milled material onv handle'is'particularly well exemplified by a mixture of fine graphite particles. in. a sticky hydrocarbon matrix in which-the graphite particles are being milled down to a substantially uniform. colloidal size. Such types of sticky viscous materialsclog up the spaces between the ends of the rollers and the. frame of the mill. Bearings become clogged; proper lubrication is prevented and rapid wear and overheating occur. Large quantities of the milled.

material are lost and contaminated with lubricating oil. Frequent shutdowns are caused.

It has become common practice to use wiping glands at opposite ends of the. rolls inan effort to plow the milled material away from their ends and turn it back in toward their medial portions. A .pair of these wiping glands is used with each roller. These glands have generally saddle shaped faces which are pressed firmly into contact with the surface of each roll' near opposite ends. In many cases the saddle face of the gland extends around a. substantial party of the circumference. of the roll. Nevertheless, where the material .is extremely sticky and viscous it adheres firmly to the surface of the roll. As the roll turns the material soon begins to be pulled in under the front edge of thesaddle. The material acts like a thin wedge as it works back under the wiping gland and lifts.

it away from the surface of the roll. In a short while a substantial clearance exists between, the roll surface and the saddle over the full circumferential length of the saddle. This lifting effect occurs regardless of the application'of extremely great forces to hold the gland down, and in many cases the forces must be reduced to prevent overheating and damage to the mill or spoilage of the material.

Then, when the gland'is lifted, the material creeps on out over the end of the roll almost as fast as if the.

wiping gland were not used. Once the gland is pried up by the material from the roll surface it, is practically impossible to force it back down with the mill in operation.

This problem of the creep out of the milled material is'even more difficult to deal with in the types of mills ice where, at least one of, the rollers is slightly crowned and its bearings are purposely provided with lateral play The. crownedroller thus is. allqwedto wobble slightly as, the mill turnscausing amorerapid redistribution of the milled materialover the millroll, surfaces. andproducing a more complete, undunifbrm, milling operation. The wiping landsthenmust. float? in operatien t fnllowthe. wobblingofthemillrollli As aresult the. milled mate.- ria1.c.an..cre p.under. the. Wiping gland more easily than when the. rolls. are fixed...

It, is an object, of the. present; inventionto provide,- flfoating scraper apparatus which. is h ghly. successful, in oyercomingthis problem, of the creeping of milled. mate.- rialidutonto he. end ofthe. roll rs and, tQ'enable mills. of the, rolljtype .to handle, sticky viscous materials more, efii'ciently and withless; wear, andshutdowns,

In. accor ance .with. the descri ed embodiment f the present invention ,the floating scraper apparatus, is ar-' ranged to scIaPQthe milled material away from the surface. o amillmll he dof'the w n ng gland. The. milled material iscontinuquslyturned back in toward'the center of: the. rol1S.-..

Amongthe. many. advantages of the. illustrative :embodirv men ofjthe. presentinv nti n ar those-res lting from he factthat the. scraper apparatus .isfioating in its operation, thins. ciuitrudu lv. ac ommod ing i self. to. movem nts. of the mill; rollandwiping gland. Substantially complete removalof'the milledmaterial. away from the roll surface ahead" of the wi'ping glandisv obtained. The materialis; also effectively prevented, from. creeping off of the. end of the roll. Thus, the wiping glandcanbe operated at reduced pressures, resulting in, less wear, and heat, and

invention, but it is to be understoodthat it is not intended.

to be exhaustivenor limiting ofthe inventiombut on the contrary is given for purposes of illustration inZorder that others skilled. in the art may. fully understand the invention and the manner of applying it in practical use so that they may modify and adapt it in various forms, each as may be bestsuited to the conditions of a particular use.

The various objects, aspects, and advantages of the pres-, ent invention will be more fully understood from a consideration of the following specification in conjunction with the'accompanying drawings, in which:

Figure-.1 ista partial perspective viewof a mill roll with associated floating rolli scraper apparatus. embodying the presentinventiong-- F gure; i553, top view of, apair of mill rolls including;

scraper, apparatus; asshown; in Figure l andwiththeassociated hydraulic control systenrforthe, scraper apparatus schematicallyillustrated; Figure3 isaperspectiveview, on enlarged scale, of, the

scraper shown, in Figure 1, the view being taken in the. general direction of the arrows. 3--3, that is, looking upwardly in Figure 1 from a position below and to the left of the scraper;

Figure 4 is another perspective view of the scraper as seen looking up and to the right in Figure 3 from the line 44 as indicated;

Figure 5 is a top view, partially in section and on enlarged scale, taken generally along the line 5-5 in Figure 1 looking downwardly; and

Figure 6 is an elevational and partial sectional view as seen looking to the right in Figure 5 in the direction of the surface of the roll, the section being indicated by the line 66.

In operation the viscous material to be milled is fed to the surfaces of the front and rear mill rolls 10 and 12, respectively, in Figure 2 approximately midway between their ends. The front roll 10 is rotated in a counter-clockwise direction as shown by the arrow 14 in Figures 1 and 6 and the rear roll 12 is rotated in the opposite direction so that the material is drawn down into the crotch 16 between the rolls and crushed. The material adheres to the surfaces of the rolls and is continuously carried underneath them and up around them again and again for repeated crushing. In order to improve the milling effect, the front roller 10 maybe of slightly smaller diameter than the rear roller, for example, it may be 22 inches in diameter compared with 24 inches for the rear roller. Also, it may be rotated at a slightly slower speed than the rear roller, for example, such as 40 R. P. M. compared with 45 R. P. M., respectively. Also, the surface of the front roller may be crowned slightly and its bearings may be provided with lateral play at their mounting points in the left and right side frames 18 and 20, respectively. This play enables slight wobbling of roll 10 relative to the roll 12, which has its bearings rigidly secured in place in these frames, thus producing a better action in distributing the material along the surfaces of both mill rolls.

Soon after the mill rolls begin to turn, the material becomes substantially uniformly spread over the surfaces of the rolls and creeps out toward their ends. Pairs of wiping

glands

22 and 24, and 26 and 28 are located at opposite ends of the

rolls

10 and 12, respectively, and have saddle surfaces sitting down astride the tops of these rolls. As shown in Figures 1 and 2, the adjacent edges of these glands are rabbeted and interfitted along vertical joints 30 and 32, effectively to wall up the left and right sides of the crotch region 16, respectively, so as to retain any excess material therein. The front inside corners of these wiping glands are rounded off. For example, as shown in Figure 5, the front inside face of the gland 24' is defined by a convex cylindrical surface 34 tangential with the inside face 36 of the gland 24.

In order to prevent the material from wedging under the gland 24 and to prevent it from creeping out to the end of the roll -(see Figures 5 and 6), a floating scraper 38 is pressed down firmly against the roll surface ahead of the wiping gland. This scraper is generally L-shaped as seen from on top. It has a rearwardly extending side portion 40 extending back adjacent the convex surface 36 of the wiping gland and a front portion 42 extending across in front of the wiping gland and overlapping the adjacent end 43 of the roll 10. The outside face 44 of the side portion 40 resting against the convex surface 34 of the gland 24 is also rounded to provide a slightly convex bearing surface. By tilting and rocking the scraper on these convex bearing surfaces, the adjustment of the scraper into optimum operating position is obtained, as explained below. In effect, these bearing surfaces permit limited universal motion between the scraper and the gland.

To secure the scraper 38 in position while allowing adjustment and floating action thereof so as to accommodate any slight wobbling of the roll 10, a bolt 46 is passed through a hole 48 near the effective center of the side portion 40. The bolt extends in a direction parallel to the axis of the roll 10 and serves as an axis about which a limited degree of universal adjustment of the scraper 38 is made. The diameter of the hole 48 is considerably larger than the shank of the bolt with a sleeve 50 fitting loosely therein around the bolt shank and preventing the

surfaces

34 and 44 from being tightly clamped together. The end of the sleeve 50 thrusting against the surface 34 is cut off at an angle equal to the angle of the surface 34 around the bolt shank, and the other end bears against the underside of the bolt head. Freedom for adjustment of the scraper 38 is provided by the clearance within the hole 48 and by the sleeve 50 which prevents the bolt from being drawn up too tightly. As shown in Figure 5, a nut 52 and an associated lockwasher and a washer within a recess 54 in the outside of the gland 24 hold the bolt in place. It is desirable to have the bolt head of a screw type and countersunk below the inside face of the side portion 40, thus allowing the milled material to slide back alongside of the scraper 38 without interference.

Extending across the bottom of the scrapper 38 is a scraping edge 56 pressed firmly into contact with the surface of the roll. This edge is formed by the junction of a concave trailing face 58 of the scraper 38 (see also Figures 3 and 4) which is cylindrical and has its axis extending parallel with the axis of the hole 48 with a plow face 60 extending generally diagonally up and across the front of the scraper 38 and facing the oncoming surface of the roll. The junction of these two surfaces along the edge 56 is seen most clearly in Figure 4. As shown most clearly in Figures 1 and 3, this plow face starts at the most advanced portion of the scraper at a tip 62 and slopes upwardly at an angle C (Figure 3) of about 50 with respect to the substantially vertical corner 65. planar, and the scraping edge 56 is curved in a generally helical shape to conform to the surface of the roll 10.

To illustrate the way in which the scraping edge 56 begins at a point overhanging the end 43 of the roll 10 and slants inwardly to force the milled material back in toward the center of the roll 10, reference is also made to the dotted line 56 in Figure 5 showing the relative position of the edge 56 extending across the under side of the scraper 38 as seen from a top view. It is to be noted that the effective point of support of the convex bearing surfaces 34 and 44 is always close to the position where the bolt 46 enters the wiping gland. Thus, this bearing point is approximately directly behind the mid-point of the scraping edge 56 in an axial direction. Also, as seen in Figure 6, this hearing point lies on a line 63 tangent to the roll at a point near the middle of the scraping edge 56. Line 63 is tangent to the surface of the roll 10 at a point approximately in the center of the scraping edge 56,

' that is, halfway along the dashed line 56 in Figure 5.

In order to plow the material inwardly of the roll while at the same time folding the material over on top of itself with an advantageous kneading action, the plow face 60 (see Figure 6) overhangs the oncoming surface of the roll. As shown in this illustrative embodiment of the invention, the plow surface 60 forms an approach angle A as measured between the surface 60 and the adjacent surface of the roll in a plane perpendicular to the roll axis of about 35 with respect to the surface of the roll 10 thereunder immediately adjacent to scraping edge 56. The dashed line 64 represents the direction of the radius of the roll passing through a point on the edge 56 adjacent the inner side of the scraper 38, and the plow face is directed forward of the extension of this radius by the complementary angle B of 55 at this point, that is, is directed toward the oncoming roll surface.

As mentioned above, the lower trailing face 58 of the scraper is substantially cylindrical. In order to cant the scraper and adjust its angular position so that this trailing face is in contact with the roll only along the edge 56,

In this embodiment the plow face 60 is an adjustable abutment means is provided by a set screw 70 threaded through a hole 72' in'the upper'corner of the front portion 42 of scraper 3C- spaced' a considerable distance above its tip 62. This set screw thrusts against the front ofthe'wiping gland 24 so as to tilt slightlythe body of the scraper and rock it in an axial direction of the roll about the point of contact between the rounded bearing surfaces 34 and 44.

In order to prevent the milled material from collecting behind the scraper, I have found it advantageous to taper back the side portion 40 of the scraper. This may conveniently be done by cutting it off at anangle of about 45 forming a taper 73.

Forcing the edge 56firmly against the roll is a pressing member 74 having a rounded end engaging in a rounded pocket 76 in the trapezoidal shaped front face 77 of the scraper 38; This member presses radially of the roll 10 as indicated by the dashed line 78, and as shown it is inclined at an; angle of about 45 with respect to a vertical plane including the axis of the-roll. Also, it thrusts axially outwardly toward the roll end 44 at an angle of about with respect to a plane perpendicular to the roll-axis.

Advantageously, the direction of action of the thrust of member 74 intersects the scraping edge 56 near its mid point. Thus, the pressure is substantially uniform along the edge 56. Also, because the member 74 acts radially of the roll, it has no tendency to push the scraper 38 out of its adjusted position. With the roll 10 turning, the set screw 70 is tightened against the front edge of the wiping gland until the trailing face 58. is lifted up a very slight amount away from the roll, leaving only the edge 56 firmly in contact with the roll.

To supply'the desired amount of force to the member '74; a hydraulic cylinder 80 is supported at an angle. of

about 45 from the end of a bracket 82 suitably secured,

as by bolts 84, to inside face 36 of the gland 24 a considerable distance above the surface of the millroll; A

base plate 86 is welded to the end, of the bracket -82.at.

the desired angle and the cylinder 80 isv thenbolted to this plate.

As-shown in Figure 2, a scraper 37 is associated with.

the wiping gland 22 and

scrapers

39 and 41 are associated with the wiping glands 26' and 28 of the rear roll. Operating each of these other three scrapers are hydraulic cylinders corresponding with the cylinder 80. The supporting brackets for these cylinders are not illustrated in Figure '2 for purposes of simplification. Hydraulic fluid is supplied from a reservoir 90'through a positive displacement type pump 92 and through'a' high pressure line 94 to a control valve 96 which returns a controlled portion of the fluid back through a line 98 to the reservoir. The fluid at the desired pressure is fed throughra front branch line 100 to the cylinders for the front roll scrap-. ers and is fed througha rear branch line 102' to the others. Return lines are indicated at 104 and 106'leading back to the pump intake.

Among the many advantages of this scraping apparatus is that the scraper is entirely supported from its associated wiping gland. Thus, as the front. roll wobbles in operation the scrapers automatically move with their wiping glands. Moreover, the scrapers are floating" free for a limited amount of motion with respect to the, gland.

and with respect to the. mill frame. The pressure is applied substantially uniformly along the scraping edge and is precisely controllable by the valve 96.

Where the milled material is a mixture of graphite and.

with pressures of the order of about 100 to 500 poundsper square inch along the edge 56 and are found to run cool and to keep the rolls clean at both ends. As a result 6 the wiping glands run smoother and much cooler, and a mill' can-be run continuously for an' entire day or longer at full output without any of thedifiiculties discussed above.

From the foregoing it will be-understood that theembodiment of the present invention described above is well suited to provide the many advantages set forth, and since different embodiments: may be made of this invention' and as the apparatus herein described may be varied in various parts, all' without departing from the scopeof the invention, it is to be understood that all matterhere inbefore set forth or shown in the accompanying'drawings is to be interpreted as illustrative and not in a limiting sense and that in certain instances, some of the features of the inventio'nmaybe used'without a correspondinguse of other features, or without departing from the scope of the invention.

What is claimed is:

1. In a rolling mill having a plurality of rolls for milling material, scrap'er' apparatus deflecting the material in a direction generally axially of a roll, said apparatus including a scraper having a scraping edge at an inclination with respect to the roll axisand engaging the surface of said roll, said scraper having a plow face and a trailing face meeting along said edge, said plow face overhanging the surface of the roll immediately ahead of said scraping edge at an acute angle as measured in a plane perpendicular to the axis. of the roll, said trailing face closely overhanging the surface of the roll immediately behind said scraping edge at all pointsalong the length of said edge and being substantially tangent to the surface of. the roll'behind said edge, and;

defining clearance space between said trailing face and the surface of the roll behind. said edge, and a pressing, member forcing said edge downfirmly against the surface of the roll, the direction of actionof saidpressing. member being radialy inward of the roll toward its. axis and passing. generally through said edge.

2. In a rolling mill having a plurality of rolls for milling material, scraper apparatus deflecting the material in a direction generally axially of a roll, said appara-. tus including a scraper. having a. scraping edge at an. inclination with respect to'the roll axis and engaging the roll surface, said scraper having a plow face overhanging the roll surface immediately ahead ,of: said scraping ment means generally above the leading end of said" scraping edge and positioning said scraper with said trailing face lifted slightly, from the roll surface and defining a clearance'space between said trailing face and said roll surface behind the. scraping edge, and pressingmeans acting radially inwardly of, said roll along aline.

of action passing near said scraping edge.

3. Rolling mill scraper apparatus asclaimed in claim 2 and wherein said plow face is. substantially planar.

4. Rolling mill scraper apparatus as claimed in claim 3 and wherein said plow face is inclined. at an angle C of about 50 with respect to a plane perpendicular to the; roll axis: and. said scraping edge is: generally helical in shape.

5. In a rollingmill having a plurality of rolls for milling material, scraper apparatus deflecting the material in a direction generally axially of a roll, said apparatus including a scraper having av scrapingedge at. an inclinaa tion with. respect to the roll axis and engaging the surface of said roll, said scraper having a plow face and a trailing face meeting along said edge, said plow face overv said scraping edge at an acute angle as measured in a plane perpendicular to the axis of the roll, said trailing face closely overhanging the surface of the roll immediately behind said scraping edge at all points along the length of said edge, bearing means supporting said scraper at a point, said point being behind said scraping edge and at a position which is generally on a line tangent to the roll surface near the middle of said scraping edge, adjustable abutment means generally above the leading end of said scraping edge and positioning said scraper with said trailing face lifted slightly from the roll surface and defining a clearance space thereunder behind said edge, and pressing means acting radially inwardly of said roll along a line of action passing near said scraping edge.

6. Rolling mill scraper apparatus comprising a mill roll, a scraper having a generally helically shaped scraping edge at an inclination with respect to the roll axis and engaging the surface of said roll, said scraper having a plow face and a trailing face meeting along said edge, said plow face overhanging the roll surface immediately ahead of said scraping edge, said trailing face being substantially tangent to the surface of the roll behind said edge, a pressing member forcing said edge down firmly against the surface of the roll, the direction of action of said pressing member passing generally through the center of said edge and generally radially inwardly of the roll toward its axis, and a wiping gland engaging said roll, said scraper being pivotally secured to said wiping gland at a point behind said scraping edge.

7. In a rolling mill having a plurality of rolls for milling material, apparatus for controlling the distribution of the milled material during milling comprising a mill roll, a wiping gland having a saddle engaging said roll near one end, said gland having a front corner, a gen erally L-shaped scraper adjacent said corner and having a rearwardly extending side portion extending back beside said gland on the side of said gland facing away from the nearer end of the roll and having a front portion extending across in front of said gland, said front portion including a scraping edge engaging the roll surface and inclined axially inwardly of the roll, and force generating means acting on said scraper and pressing said edge against said roll and also forcing said scraper toward said corner.

8. Apparatus as claimed in claim 7 and wherein said side portion of the scraper tapers rearwardly toward the adjacent side of said gland.

9. In a rolling mill having a plurality of rolls for milling material, apparatus for plowing the milled material axially inwardly away from the end of a mill roll comprising a wiping gland having a saddle engaging said roll near the end of the roll, said gland having a front corner, a generally L-shaped scraper straddling said corner and having a rearwardly extending side portion extending back beside said gland on the side of said gland facing away from said roll end and having a front portion extending across in front of said gland and overhanging said roll end, said front portion including a scraping edge engaging the roll surface along a line beginning at said roll end and inclined axially inwardly of the roll to a position generally inside of said corner, and force applying means engaging said scraper and forcing it toward said straddling position and also pressing said edge firmly down onto the roll surface.

10. In a rolling mill having a plurality of mill rolls, apparatus for confining the milled material on the roll surfaces comprising: a plurality of wiping glands near the ends of a pair of adjacent rolls, a plurality of L- shaped scrapers, each scraper straddling the forward inside corner of one of said wiping glands, each scraper having a scraping edge extending inwardly along the surface of the respective associated mill roll ahead of the respective gland which it straddles and inclined rearwardly, and force applying means mounted on each gland and pressing said edge firmly against the surface of the respective associated mill roll.

11. In a rolling mill having a plurality of mill rolls, apparatus for confining the milled material on the roll surfaces comprising: a plurality of wiping glands, one being near each of the ends of a pair of adjacent rolls, a scraper movably secured to each gland and having a scraping edge extending axially inwardly along the surface of the mill roll ahead of the respective gland which it straddles and inclined rearwardly in the direction of rotation of the mill roll which is near the respective gland which it straddles, a force-generating cylinder associated with each gland, bracket means securing each cylinder to its associated gland, each cylinder acting to press the scraping edge of the scraper straddling said associated gland firmly against the mill roll surface, a fluid supply system connected to said cylinders, and means to control the pressure supplied to said cylinders by said system.

12. In a rolling mill having a plurality of rolls for milling material, scraper apparatus for pushing the milled material axially inwardly away from the end of a mill roll comprising a wiping gland having a saddle engaging said roll near one end, said gland having a front corner, a generally L-shaped scraper straddling said corner and having a rearwardly extending side portion extending back beside said gland on the side of said gland facing away from said roll end and having a front portion extending across in front of said gland, said front portion including a scraping edge engaging the roll surface ahead of said wiping gland and inclined axially inwardly of the roll to a position generally inside of said gland, a pivot bearing for said scraper pivotally coupling said side portion to said gland at a point behind said edge, a force generating mechanism, bracket means supporting said mechanism from said gland and in a position above said scraper, and a pressing member actuated by said force generating means and exerting force on said scraper along a line of action passing through said scraping edge and directed radially inward of the roll.

13. In a rolling mill having a plurality of rolls for milling material, scraper apparatus for plowing the milled material axially away from the end of a mill roll and for folding the material over onto itself during said plowing comprising a wiping gland having a saddle engaging said roll near the end of said roll, said gland having a front corner facing generally axially away from said end, a generally L-shaped scraper straddling said corner and having a rearwardly extending side portion extending back beside said gland and having a front portion extending across in front of said gland, said front portion including a scraping edge engaging the roll surface ahead of said wiping gland and inclined axially inwardly of the roll to a position generally inside of said corner, said scraper having a plow face extending up from said edge and overhanging the surface of the roll immediately ahead of said edge, and force applying means engaging said scraper and forcing it toward said straddling position and also pressing said edge firmly down onto the roll surface.

14. Rolling mill scraper apparatus as claimed in claim 13 and wherein said force-applying means is a force-generating cylinder supported from said gland and including a pressing member engaging said scraper and acting along a line directed radially of the roll and passing through said scraping edge.

15. In a rolling mill having a plurality of rolls for milling material, scraper apparatus for deflecting the milled material along the surface of a roll away from one end comprising: a wiping gland having a saddle engaging said roll near one end, said gland having an inner front corner which is rounded, a scraper having a rearwardly extending side portion positioned beside said gland and having a front portion positioned ahead of said gland, said scraper straddling said corner, said side portion being connected to said gland for universal motion of the scraper with respect to said gland, said front portion of the scraper having a plow face commencing at a point near said one'end of the roll and slanting rearwardly and away from said one end and terminating at a point positioned axially inside of said corner, adjustable abutment means interengaging said front portion and gland, bracket means extending ahead of said gland, and a force exerting mechanism associated with said bracket means and including a pressing member applying force to the front portion of said Scrapper and forcing the lower edge of said plow face firmly against the roll, the line of action of said pressing member being directed generally radially inward of said roll and forming an 10 angle of about 45 with respect to said front portion of the scraper, said line of action also being canted toward said one end at a small angle with respect to a plane perpendicular with the roll axis, whereby said pressing member presses said side member against the gland.

References Cited in the file of this patent UNITED STATES PATENTS Behringer May 30,