US2216784A - Method of forming liner plates - Google Patents

Description

Ott 8, Y|= M. PAYNE 2,216,784

METHOD OF FORMING LINER PLATES Filed lApril 28, 1958" ooloojorcoooooo Ao @le 0,80

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i Pea/"50N` M af Ffa 7 Af for/7g Patented Oct. 8, 1940 l UNITED STATES PATENT OFFICE N, i A 2,216,784 i i v Y v METHOD oF FORMING UNER PLATES Pearson M. Payne, Denver, Colo. n

Application April Z8, 1938, Serial No. 204,714

4 Claims.

This invention relates to grinding and comminuting mills, and more particularly to the abrasive resisting inner surfaces of such mills, and hasas an object to provide improved liner means adapted for removable and replaceable association with the inner surfaces of such mills.

A further object of the invention is to provide an improved construction for mill liner sections or plates.

1'0" A further object of the invention is to provide an improved .combination of a highly abrasiveresisting, hard, and consequently brittle grinding section with a relatively softer and more elastic supporting member in a manner constituting a 115', mill liner section or plate.

A further object of the invention is` to provid improvedmeans for interconnecting a hard and brittle wearing section with a relatively softer and less brittle backing element to form a mill liner section or plate.

Afurther object of the invention is to provide as units `of manufacture and replacement, mill liner sections or plates in the form of a unitary combination of a grinding section with a relative- 1y softer and. less brittle backing element.

,A further object of the invention is to provide an improved method for the manufacture and production of mill liner sections or plates.

' A further object of the invention is to provide an improved method for the manufacture and production of unitary combinations of a wearing section with a relatively softer and less brittle backing Aelement for use with high eiciency and enhanced advantage as mill liner sections or` plates.

A further object of the invention is to provide an improved composite mill liner section or plate which is free from many of the disadvantages of functionally similar conventional constructions,

0. which permits of the practical and -eflicient use of very hard, highly abrasive-resisting material as a Wearing base and section, which is susceptible of simple and convenient construction through the use of conventional apparatus in sizes and 45? shapes adapted for operative association with conventional mills, and which presents advantages of greater operative durability and longer efficient life in comparison with conventional like units. 502 My invention consists in the construction, ar-

rangement, and combination of elements, and in the method employed in electing a unitary 55sl bythe accompanying drawing, in which- Figure l is an elevation of the outer or con` t-acting side of a mill liner section embodying the principles of my invention'.` Figure 2 is a .longitudinal Vsection taken' on the indicated line 2---2 of Figure 1. Figure 3 is a transverse section 5,. taken on the indicated line 3-3 of Figure 1 andillustrating the assembly of said latter ligure in'A operative association with a-portion of ya mill shell and with the immediately adjacent, complementary liner sections. 'Figure 4 iS a fragment`10- tary, detail section illustrating .alternative meansemployable in giving effect 'to my yinvention;` Fig-l ures 5, 6,and 7 are Views similar to Figure 4, illustrating various alternative means employable inv the practical development and use of the inven- 15 tion.

Conventional construction of ball and rod mills employed-in the grinding and comminution of ores and similar materials includesa substan-r tially cylindrical, hollow shell, mounted for rotation about its axis and lined with removablefandv replaceable sections or plates of wear resisting. material rigidly clamped to said shell for rotation therewith, the interior ofthe drum thusrformed being supplied with a quantity ofloosely 5 posed balls or rods which cascade androll about within the mill for impact and grinding effect on material fed into said drum. The liner sectionsA or plates must resist the abrasive action-of the material to be ground and must withstand, as 30,

well, impact effect of the grinding balls and rods. Low-cost metals in cast form, particularly white iron, are characterized by relatively extreme hardness and high resistance to4 abrasion, and

hence are,'from the stand-point of economy and '5,

brittlawhich is a notable disadvantage in that, .0,

liner sections or plates of such material are frequently broken in handling, tr-ansit, and installa-4 tion. l y

The brittle character of they hard liner sections and plates is of further disadvantage in that it 425.

permits fraoturing and ultimate destructive disintegration of such plates under impact in use,

particularly when the plate has been worn down in thickness, so that the initial rrelatively lower cost of the liner installation may be oiset by the. T

necessity for frequent renewal of the liner plates.: Relatively. more elastic and less brittle liner units may be formed from more expensive materials and alloys, but the gain in strength and durability of. units so manufactured .is at least partialbores I2 extending entirely through said portion ly offset by loss of hardness and consequent wearing efficiency, hence a liner construction wherein the wear resistance and long life of white iron or other hard material may be combined in a unit having the strength and operative durability of the less brittle materials presents practical advantage of both initial and operative economy and constitutes a long-sought contribution to the art of comminuting and grinding.

The instant invention is concerned with the provision of a liner` plate or section ywherein a relatively thicker Wearing portion of white iron or equivalent metal is rigidly and permanently attached to a backing plate having a relatively high coefficient of elasticity, to--form a liner section or plate adapted for removable .and replaceable association with a mill shell and for marginally adjacent cooperation with other such units to cover the inner cylindrical surfaces of such shell. As shown in the drawing, the numeral I designates the inside body portion of the improved unit, which portion is formed by casting or molding of highly abrasive-resisting hard material such as Whit iron, toa length and width corresponding to the conventional sizes used in theV grinding chamber of a mill wherewith the unit is to be associated, with substantially arcuate, concentric inner and outer vsurfaces adapted to cooperate with the curvature of the mill. drum, and with long side margins defined by converging planes corresponding with radii of the mill, all of which is in itself conventional and well-known practice. The inner or Wearing face of the portion IU may be formed witha longitudinal Vrib I.I, or such other protuberance, depressions, or deformations as may be deemed best suited to comminution of a given material in. a specific mill, and said portion I0, including in this instance the rib. II, is intersected` by suitable, spaced, radially-traversing for registration with corresponding holes in a mill shell to provide means for securely bolting the liner unit to said shell. The bores I2 may vary in specific form and arrangement as may be deemed most expedient'for a given installation, the arrangement shown in the drawing contemplating an'elongated oval recess with its greater axis directed longitudinally of the unit and opening through the grinding face of the latter to receive the ovalhead portion of a bolt I3, an outwardly-converging bore portion Vcontinuing said oval recess and adapted to seat against and receive pressurefrom a tapered neck portion of the bolt I3, and an extension of said tapered portion opening through the outer wall of the casting I0 to receive the shank of said bolt I3, so that when a nut I4 is tightened on the bolt I3 against the outer surface of a mill shell I5-, the tapered neck of said bolt acts against the tapered portion of vthe bore I2 to closely and firmly clamp the liner I0 against the mill shell. The clamping means shown and described is typical of such means commonly employed and is in itself prothe bolts I3 when the latter are tightened againstl the shell I5. l

In giving effect to the instant invention, the

. liner portion I0 is associated with andrmly and.

permanently secured to a relatively thin backing plate I6 of a material relatively softer and less brittle than the white iron of the casting IIL' the backing plate I6 being conveniently formed of sheet steel, or equivalent material, which has the characteristics noted. The backing plate I6 is formed to a length corresponding with that of the casting I0, to a curvature concentric with and adapted to t closely between the outer surface of the Vcasting I0 and the inner surface of the mill shell I 5, and has a widthjdened by the same radial planes as limit and denne the long margins of the casting. To secure the plate I6 to and in the desired relation with the casting I0, said plate is formed with a plurality of identical holes or openings I'I disposed throughout its surface area in relatively closely spaced arrangement and in conformity with a definite, predetermined pattern, other holes I8 being formed through the plate I6 in position to register with and continue adjacent portions ofthe bores I2 for accommodation of the shank of the boltl I3. The holes I'I conform in pattern with an arrangement of studs, inserts, pins, or rivets I9 imbedded in the outer surface of the casting IIJ at the time the latter is cast, and projecting from said outer surface of the casting a .distance somewhat less than the thickness of the b-acking plate I6. It is, in a practical sense, immaterial whether the elements I9 have headed portions imbedded in the metal of the casting I9, as shown, or Whether said elements are simply straight studs orpins, since the casting of the metal I0 about said elements will provide a bond sufficient to hold the elements I9 `firmly to vsaid casting. against any pressures which may act to effect a separation therebetween. The elements I9 are of a metal susceptible to Welding, riveting, and like treatment, and are preferably of soft steel or equivalent material. With the elements I9 disposed in the casting I0 to conform with the pattern of the holes I'I and arranged to project from their casting a distance less than the thickness of the backing plate I6, it is desirable that the holes Il have a'diameter somewhat in excess of the diameter of the elements I9 to be received therein, which variation of diameter has a two-fold function in that it permits accommodation of slight variations and inaccuracies in the registration of the elements I9 with the holes I1, and leaves a space or clearance about. each element I9 within its respective hole I'I which may be filled by welding to securely fasten the projecting portion of each element I9 within and to its corresponding hole I'I. As is clearly shown in the first three figures ofthe drawing, the backing plate I6 is positioned closely against the outer surface of the casting I0 with the projecting portions of the elements I9 received in corresponding holes I'I, whereafter each of said elements is securely brazed or welded `to adjacent margins of its hole I 1, the relative short projection of the elements I9 and the clearance between each element I9 and its corresponding hole I1 permitting the formation of a strong welded bond therebetween Without the necessity of marring or deforming in any Way the outer surface of the backing plate I 6 which is adapted to seat against the inner curvature of the shell I5.

While it is believed that considerations of economy and practicality are best served by fixing the backing plate to the casting I0 in the manner just above described, alternative means for the same purpose are available as indicated in Figures 4 to 7, inclusive. In Figure 4 is illustrated an arrangement wherein the holes I'I are tapered inwardly toward the wearing face of the casting I0, as indicated at I 1', and the elements I 9 are kreplaced by elements I9 having a projecting length greater than the thickness of the backing plate I6, in which arrangement the projecting portions of the elements I9 are designed to be upset or riveted into an expanded relation closely lling the frusto-conical holes I1', thus uniting the casting I and back plate I Ii in a unitary assembly.

The showing of Figure 6 is closely analogous to that of Figure 4, the elements I9 being replaced by a short stud 20, of soft metal, which terminates flush with the surface of the casting Ill, a frusto-conical cap member 2| being seated in the tapered holes II in registration with the exposed end of the stud 25 to which said capv 2| is butt-welded to establish the desired connection between the casting I@ and backing plate II.

In the modicaticn according to Figure 5, the backing plate I6 is provided with tapered holes I l adapted to register with openings in the casting Il! which communicate with the threaded holes or nuts 22 embedded in said casting, so that conical-head screws 23 may threadedly engage the nuts 222 with their heads seated and bearing against the holes I1 to firmly clamp the backing plate to the casting.

In Figure 7 an arrangement is shown wherein threaded bolts 24 are positioned with their heads embedded in the casting I0 and their threaded stern portions projecting beyond the outer surface of said casting a distance less than the thickness of the backing plate I5, for threaded engagement with nuts 25 adapted to be received in counter bores 2E formed in the outer surface of the plate I6 in concentric relation with the hole formed in said backing plate for reception of the bolt stem.

The improved liner plate constructed as shown and described provides a wearing portion of low cost material which is very hard and highly efficient, in combination with a supporting or backing plate so associated with the abrasive-resisting liner portion as to position and hold the lat` ter against destructive disintegration even after the wearing portion has been extensively fractured as a result of mounting strains and impact eiects. The clamping action of the bolts I3 in the construction shown is had against shoulders formed in the casting II), rather than against the .backing plate I6, so there is no tendency for said plate Iii to be pulled away from the casting I0, said plate I6 serving rather as a bridge to connect and hold the portions of the casting II) in the desired operative relation for continued wearing action until such portions have been worn so thin as to preclude further effective gripping thereof by the elements interconnecting between the casting and the backing plate. As is the case with conventional liner installations, a loose condition of a liner mounting which necessitates tightening of the clamp bolts is indicated by leakage oi nes loutwardly of thev mill shell about those bolts I3 which are loose, and a condition of wear of the improved liner plate construction which necessitates replacement of the liner assembly is indicated by the presence of chips or relatively small pieces of material from the casting lil in the discharge from the mill, such indications evidencing wear of the'liner plates to a thickness` less than will permit the interconnecting elements to continue to long hold the casting portions to their backing plate.

Since many changes, variations, and modifications in the specific form, construction, and arrangement of the elements shown and described may be had without departing from the spirit of my invention, I Wish to be understood as being limited solely by the scope of the appended claims, ratherthan by any details of the illustrative showing and foregoing description.

I claim as my invention- 1. The method of forming mill liner plates n which consists of casting a wearing section from hard, highly abrasive-resisting material, providing said wearing section with rigidly-held attaching lugs of more ductile material embedded therein at the time of molding to project from its outer surface, and rigidly connecting a coextensive backing plate of non-brittle material formed With holes disposed to receive said lugs to said lugs in closely-overlying relation with said wearing section outer surface.

2. The method of forming mill liner plates kwhich consists of casting a wearing section of hard, highly abrasive-resisting material, coincidentally embedding lugs of more ductile material in said casting in spaced relation on and projecting from the outer surface of said casting, forming a coeXtensiVe backing plate of nonbrittle material with holes to receive said lugs and' closely overlie said casting outer surface, and rigidly interconnecting said lugs with adjacent portions of `said backing plate.

3. The method of forming mill liner plates which consists of casting a white iron wearing section, coincidentally embedding relatively more ductile lugs in said casting in spaced relation on and projecting from said casting outer surface, forming a coextensive steel plate to closely overlie said casting outer surface and with holes adapted to receive said lugs, and welding said lugs to adjacent portions of said backing plate.

4. The method of forming mill liner plates which consists of rigidly interconnecting a backing plate of non-brittle material closely against and in ooextensive covering relation With the outer surface of a highly abrasive-resisting casting by embedding ductile lugs at the time of molding in said casting to project from said casting outer surface, forming holes in said plate disposed to receive said lugs, and rigidly interco-nnecting said lugs and plate.

PEARSON M. PAYNE.

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