US2982062A

US2982062A - Method for grinding gyratory crusher wearing parts

Info

Publication number: US2982062A
Application number: US650134A
Authority: US
Inventors: Willard C Jackson; Walter E Ruehmer
Original assignee: Nordberg Manufacturing Co
Current assignee: Nordberg Manufacturing Co
Priority date: 1957-04-02
Filing date: 1957-04-02
Publication date: 1961-05-02
Anticipated expiration: 1978-05-02

Description

y 1961 w. c. JACKSON ETAL 2,982,062

METHOD FOR GRINDING GYRATORY CRUSHER WEARING PARTS Filed April 2, 1957 6 Sheets-Sheet 1 In Wen Z075 5y farl'er 5 Caz fer .fltfbri zeys May 2, 1961 w. c. JACKSON ETAL 2,982,062

METHOD FOR GRINDING GYRATORY CRUSHER WEARING PARTS Filed April 2, 1957 6 Sheets-Sheet 2 Waller)? fiuekfieer 5y J ar/rer a? Caiier viz'zorneys May 2, 1961 w. c. JACKSON ET AL METHOD FOR GRINDING GYRATORY CRUSHER WEARING PARTS Filed April 2. 1957 6 Sheets-Sheet 3 Waite 712. fiaze/e/Wer 5y Pa 74w?" darzer Jzzorneys y 1961 w. c. JACKSON ETAL 2,982,062

METHOD FOR GRINDING GYRATORY CRUSHER WEARING PARTS Filed April 2, 1957 a 6 Sheets-Sheet 4 J 71 00 via 75 Milford aha/{4307? Zflaiier Z fizze m .Za 74%;" a? arzer J/farweys May 2, 1961 w; c. JACKSON ET AL 2,982,062

METHOD FOR GRINDING GYRATORY CRUSHER WEARING PARTS Filed April 2, 1957 6 Sheets-Sheet 5 :9 Inz/ewfors Willard (1751025011 Zflaizerflfiu efimer May 2, 1961 w. c. JACKSON ET AL 2,982,062.

METHOD FOR GRINDING GYRATORY CRUSHER WEARING PARTS 6 Sheets-Sheet 6 Filed April 2, 1957 w haw J7? z/en zors Millard Che/3:50

i. crossrai1320" or"t he like. The crossrai moved upland downfthe'posts andis n V stays-generally horizontal. 'i'The superstructur'e or bridge" U ni sd .j msPatsgfl 1.

METHOD FOR GRINDING GYRATORY CRUSHER WEARING PARTS Willard C. Jackson, Milwaukee, and Walter E. Ruehmer,

South Milwaukee, Wis., assignors to Nordberg Manufacturing Company, Milwaukee, Wis., a corporation of such as mantles and liners, for use on or with gyratory crushers andthe like, although many of the characteristics, features and aspects of the invention are not nec essarily restricted thereto. In any event, the invention is concerned with a method and apparatus for grinding a rough casting of manganese steel or the like to produce 'a finished frusto-conic wearing a gyrato'ry crusher. v

A primary object of our invention is a methodof grinding'gencrally frusto-conic manganese steel castings. Another object is a method of grinding castings of the above type to insure faces.

Another object is a'method of grinding a mantle to insure aproper nut seatat the smallend. 1

Another object is a machine for grinding. liners or mantles, or both, to insure concentricity o'n thefinish'edproduct.

Another object is a method of preliminarily assembling or prechucking the frusto-conic manganese steel castings to reduce down time in a grinding machine.

1 Another'object is a machine for grinding the fit and wear surfaces of both mantles and liners simultaneously.

Another object is an improvedmanganese steel frustoconic wearing part for use on gyratory crushers and the like: a W 1 Another object is a frusto-conic manganese'steel man i tle constructed to insure a smooth concentric nut seat.

"Another object-Isa method ;for automatically and -s i-' multaneously grinding thewear-and fit surfaces on a mantle or liner -to' insure concentricity in the finishedarticlw I r a Other objects will appear from time to timein the ensuingspecification and drawings in which:

Figure 1 is"a perspective of a grinding :machinewitl a mantle in position being ground;

Figure 2 is an enlarged perspective of the right hand i grinding spindlein- Figure 1 showing the controlmech- Figure 3is an'axial section through theg'rinding zone with a bowl liner being ground and showing, diagrammat'ically, the grindingheadsin operation; 1 Figu re 4 is aIview similar to Figure 3 but of;

.Figure Slis a; top plan view of aprechucking' structureusablewith the machine of Figure 1; and;

Figure 6is aside viewofiEigure. 5.

In Figure 1;' thebasicv machine ,isLshown. ltrnaylin clude asuitablebase,'indicated generally at 10, rotatably supporting a j'generallyf' upright I'table. 12 017 the' like; defininga gi inding' zone, indicated. generally at 14. On

: each "side of the table; and grinding zone ar e' uprights or jpost's *16f1'and '18 which support'afgenerally" horizontal,

' 'l-isad'aptedt'o b- 70 concentricit'y of the fit and wear sur a modi-r A n 2,982,062 Patented M y 1 and serves as a support for suitable power mechanisms,

hydraulic circuits, electric drives, control circuits, and

the like, none of which is important to this invention.

The table may be rotated by, any suitable conventional driving mechanism, not shown, which may provide for a.

full range of speeds. Through a suitable power mechanism, not shown in detail, the crossrail may be raised and lowered. For example, a gear box 24 or the like at the foot of upright 16 is connected by suitable lead screws 28 and the like to the mechanism of the crossrail. A similar gear box 30 and lead screws 32 are pro'-' vided adjacent the other upright 18. The details ofthis mechanism, in and of themselves, may be conventional."

We provide two

saddles

34 and 36 on the crossrail, one on each side of the grinding zone and table. The crossrail may carry a suitable power mechanism and a drive so that the saddles, either together or independently;

may be moved back and forth along the crossrall. For example, note the lead screw 38. In, any event, the important point is that the saddles move along suitable ways on the crossrail to provide for a desired adjustment. Each element for use on zone.

saddle carries a spindle mechanism, for example, at 40 and 42., Each such spindle has a grinding head at its lower end, for example, at 44 and 46. The spindles project toward the grinding zone and the grinding heads might be characterized as residing at or in the grinding Each spindle is mounted on a somewhat large gear, as at 48 and 50, each of which is pivoted to its saddle, as at 52 and 54. Note that each spindle is eccentric to the pivot for the gear that carries it.

Rotation of the gears 48 and 50 about their respectivepivots will cause the spindles-to be' rotated bodily about the pivots 52 and 54, thereby providing an adjustment for the direction at which each of the grinding heads approach or project into the grinding zone. The gears may be suitably rotated by a worm-drive, as at 56 and 58, which may be driven by any suitable power mechan-' ism, not shown in detail because, as such, it is not important in detail to this invention. The front of the crossrailrnay be provided with suitable covers 60, if desired. Between the uprights or posts we may provide an arcuate shield 62, if desired, behind the grinding zone,

flow ofi'of the rotary table 12, through the screens to'a':

suitable sump or collecting zone for recirculation;

In a conventional manner, the upper surfaces of the table may be provided with a plurality of radiallydisposed T-slots 64 adapted to'receive bolts or other suitable connecting elements to fasten clamps, jaws, or other suitable supporting mechanism, indicated broadly at 66; to thetable. The-workpiece 68, shown in Figure 1, generally represents" a manganese steel. frusto-conic mantle ,for'use on the head of a gyratory crusher. For

*- example see U.S. Patent No. 2,684,208. As shown, the

mantle :ismounted onjaws on the rotary table with its large end up. i

lfi 'flgllle 4 which shows a variant form of, machine w and method, we have the same or asimilar, type of n mantle, in section.

conic fit surface 70 adjacent or at the large end anda Such a mantle has an inner frusto-..

frusto-conic'wear surface 72 on the 'outer surface which. coactS'Withthe materialbeing fed into the crushing cavity of .a gyratory crusher'between the gyrating headia'nd the v 74, but itmightbe-o'th'e'rwiset "We'h ave indicated thesamelfitsurfaceandWearsur 22*: across the top offtheguprightstor.fposts is stationary-' face and-7 2 'on themanfl 'mfi urei ,As shown; the .1.

. on the table.

exact; a

l 3 t mantle is supported by the fixtures or jaws, 66, which engage its outer surface generally adjacent the small end and a suitable centrally disposed pulldown mechanism may project up through-the open small end of the mantle and clamp against the inner surface in any suitable manner, not shown. As for the clamping and supporting mechanism to hold the mantle rigid during a' grinding operation, suflice it to say that any suitable fixtures or jaws or clamps may be used, either supported or attached directly to the upper surface of the table, as shown in Figure l, or in accordance with the variant form of Figure 5 to be explained hereinbelow.

A bowl liner is shown in Figure 3, generally at 76. Such a liner is similar to a mantle in that it has agenerally frusto-conic body portion whichis disposed big end up But its wear surface is on the inner surface of the frusto-conic body, as at 78, and its fit surface is on the outer surface, as at 80. This is the reverse of the mantle. But they are similar in that each has a fit and a wear surface. In each case, one such surface'is on the inside of the casting, adjacent the large end, and the other is on the outside, also adjacent the large end. The bowl liner in Figure 3 is suitably supported by jaws or clamps and suitable hooks 82 or the like connected to the table by bolts 84 or the like may be used to pull down the mounting hooks'86 which are normally found on bowl liners and are used to mount the bowl liner on the bowl of a gyratory crusher.

In general, the mantle andliner, explained somewhat in detail hereinabove, are representativeof the type ofwearing parts'used in gyratory crushers with which we are concerned in this invention. While the broad aspect of the invention may be applied to either, there are certain specific aspects, set forth in detail hereinbelow, which may be considered restricted to one or the other.

In general, the wearing part or element, whether a mantle or liner, is a frusto-conically shaped manganese steel rough casting. Such castings are notoriously out of round, and before they can be applied and used on gyratory crushers, the fit and wear surfaces must be trued. This has previously been done by either machining or grinding. Machining is too expensive and too slow, and, more important, manganese steel has very: poor machining properties. In fact, for many uses it is widely accepted as a nonmachinable material. While grinding has been used, it too has proved expensive and, more important, inaccurate. For example, in the finished product, there must be a matched concentricity between the wear and fit surfaces. Prior grinding processes have failed to obtain this. Also, grinding processes have been generally time consuming and, therefore, additionally expensive. Further, such grinding processes are quite slow, require the use of a number of machines to perform differentsteps. tie up an excessive amount of capital equipment and floor space for the small amount of finished wearing elements produced. x

One of the important aspects .of our invention is that we simultaneously grind both the wear and the'fit sur: faces. The table supporting the casting to be ground 'is rotated at a generally uniform rate of speed. The grinding heads-are automatically and uniformly moved back and forth in the grinding zone across the surfaces and grinding is done'simultaneously to insure conceiitricity of these two surfaces on the finished piece. 'For examplefin Figure-31hr: grinding head .44 is'indicatedfto're of the plunger mechanisms may be caused to move back and forth within their cylindrical housings. For example, a rack may be secured on the plunger or piston driven by a suitable pinion which in turn could be driven by any suitable power mechanism, hydraulic, electric, or otherwise, contained in or mounted on the cylinder housing. For example, note the rack 96 on the plunger or piston 94. Or a piston and cylinder may be secured to the quill. The important point is that each of the plungers or pistons is caused to reciprocate back and forth within its housing or mounting so that the grinding head carried at the end may be caused to move back and forth across the surface on the casting to be ground.

The distance moved by the grinding head during this reciprocation shall be referred to as the grinding stroke or stroke.

To regulate and effectively control the length of this stroke, we provide a control mechanism. For example,

' same structure may be applied to the left-hand unit. In

safety cams ;so that in the eventthe normal'reversingdetail in Figure 2, the cylinder or support 90 may carry a suitable bracket 106 which in detail is unimportant. This bracket or support carries two sets of microswitches or the like, one set being designated 108 opposite the rod 102 and the other set being designated generally 110 opposite the rod 104. Each microswitchof the set may include a lever 112 with a roller on the end or otherwise and the rods carry suitable cam elements, adjustably;

mounted. For example, the rod 102 has lower and

upper cam elements

114 and 116 while the rod 104 carries suitable lower and upper cam'elcments 118 and120. Either rod may'be considered the primary or controlling rod while the other functions as a safety. For example,

the rod 102 may perform the actual reciprocal control with the rod 104; being the safety. In this case, the

stops

114 and 116 are adapted to engage the levers on .the microswitches of the set 108 in response to movement of the plunger or piston. The cams kick'the switches backand forth. The switches may be suitably 'connected,'as by the leads shown in Figure 2, to a suitable conventional reversing mechanismjso thatthe powertothe piston may be reversed whenever either one of the cams trip the switches; The cams onthe safety rod 104 are merely mechanism is faulty and either of the

normal controlling cams

114 and 116 pass through the switches 108 without effect; the cams '118 and 120 on the safety 'rod will hit their'auxiliary' switches 110 to reverse the plunger andprevent the grinding head from moving too far in either directionan'dcause damage. i For example, the

safety cams

118 and 120 might be set to prevent the grinding head 46 in FigureSJfrom reaching'the hooks" 86 on :the

- bowl liner in the event 'that'the normal cams malfunction.

The important point isthat the

cams

114 and 116 are i st to define the stroke o'f l'the grinding headffThis is oiproc'ate back and forth across the wear surface 78. At

the same time, the grinding head is indicated as reground simultaneously 'andftheir concentri'city'wilfbe peripheralsp'eed of. the surface being' ground onthe cast ing, so that .a predetermined thickness of material. at. the surface of the castingwillbe rough ground andremovedfv Thestops orcams ,will norrnally be set so that the grind ing head'just-clears the, surface undergoing grindingat As for the details, in Figure'l, each: spindle mayiiirl-fl 'clude a cylinder or housing, as."at 88"and 90; which: car-1' two of both heads. power mechanism,moves the grinding head at a predetermined linear velocity,jrelati've tothe speed of rotation of the table ,12jand also the each-end when-rjeversingtakesplace, but not necessarily.

The I details :of- ,the ;power mechanism, the reversing same 3:; our invention,and accordingly we have not shown em. ..t i l r The casting undergoing grinding is positioned on the rotary table in the grindingfor working zone with its axis generally upright and concentric with the rotary axis of the table; For example, suchaxis is indicated generally at X in Figure 3. The casting is rotatedabout this axis. The grinding heads, are brought in from opposite sides, on one side the. grinding head moves into the casting, such as the head .44 in Figure 3, and grindsthe inner surface, in this casethe wear surface of a bowl liner. The other head moves somewhat below the ca sting and across the outer surface, in'the'case of Figure 3, the fit surface ofv the liner. In each case the grinding head is reciprocated through a. predetermined grinding stroke. The stroke of eachhead is determined automatically by a mechanism, such as in Figure 2. The stroke of the two heads may be different, depending upon the width of the ground surfaces desired. ln any event, one head, for example the head44, reciprocates back and forth along its axis Ylwhile the other head reciprocatesback and forthalong its axisZ, these axes being understood to be the-centerlines, or generally $0,; of the spindle units. These axes intersect the'Xfaxis', of the workpiece, but not at thesame point, which is' 'clearly shown in Figure 3.

In otherwords, the di'rectionof movement, of either head during its reciprocation would, extended, intersect the rotary axis of'the piece and table. Further, the three axes, X, 'Y and Z," are coplanar and their plane would be upright, perpendicular to the base and woul d generally pass laterally across the front: of the machine through the middle of the grinding zone,',such1as'in Figure 1 h In additionfto having a certainreciprocating stroke, eachv head also has a" feed, andthis feed is acquired by an automatic imovernel'ltlof thelsaddle, horizontally along the rail. For examplegat'a predetermined time, the saddle 34 inFigureiirnoves a predetermined amount to the left. "The sameljis true oftlsaddle 36, namely, to the left. In each case the grindingfhead carried on the spindle of thatsaddle will be fed into the work. The amount of feed is a combination of the desired amount of. material to be remb vedfromjthe casting, as well as a compensation for wheel wear and may be varied to suit conditions. Whatever the feed .is,"the' saddle might be moved this amount jonce" during each'reciprocation cycle of the plunger of {piston and grinding headr We prefer that a certain amount of-fe'e'd be applied to. the saddle or eachheadatieach end of its reciprocation, and thisirnay be 'easily attained. For example, consider the s'etofmicroswitchesi108. One switch of the set could be used as the .re'versegswitch to. reciprocate the plunger and grinding headlb k;.and'forth whilethe other switch could be used to automatically feed the "saddle a predetermined amount. ln this marinenlwhen theg rindi'ng head was at ,either'the top or the bottomi'of its stroke, it would be fed a'certain distance toward the worl The. stops or canis114 and-116areiset rtothe limits of the stroke, which determines the point of lateralfeed, and themicroswitches, are electrically, connected to'the feed mechanism so that the feed may be applied at the-top or bottom of the stroke orat both or at either. A;,.manual control the axis of rotation X which,., is, the general axis of-the castingj i In use, we provide a generally upright pivoted post ,126 mounted on and projecting above the top 22 of the machine or otherwise, which has a boom 128 and suitable depending cables or leads 130 to a control board or panel 132, which is at waist or chest level or otherwise for use by the operator. The panel has a pluralityof control buttons and the operator in starting, stopping, and otherwise handling the machine, may pivot the control panel from one side tothe other of the rotary table and grinding zone so that he can, at all times, si multaneously'observe and control the operations of any of the moving parts. For example, we prefer that the controls on the-panel be such that the operator may manually feed the saddles in or out, independently or together, raise or lower the crossrail, start and stop the grinding heads, and pivot the spindles about their pivot points on the saddles. Also, the operator should be able to start and stop the table, as well as other things.

In starting a grinding operation, the operator moves the grinding heads in toward the grinding zone by bringing the saddles inwardly. Previously, the casting, be it a mantle or a liner, would have been positioned properly on the table. The angle of the spindles should then be adjusted so thatvtheheads, during their reciprocation, will move generally'parallel to the surfaces to be ground. The operator should then raise the head 44 above the casting by retracting it and bring it over the casting byfeedingthe saddle 34' inwardly. The head should then belowered untilit projects down into the casting slightly and the stops should be setroughly to determine the extent of. reciprocation during the working stroke. With this l roughlyeset; the operator would then move the saddle tothe left bringing the head 44 toward the inner surface, in Figure 3 this being the working surface.

As'soon as the grinding head made contact, manual latbutton is included on thecontrolpanel," described later, 7

l to permit, the reed, mechanis nto be actuated at any desired point between thetop-and bottom-ofthe stroke.

Also, the coolant is important and we have, shown coolant connections gl22 andl124 in Figure :1, but the details arei otherwise unimportant and; may be conven tion'al. The grinding heads need not reciprocate together I or in unison but they do reciprocate-at the same time;

operate simultaneously so that the inner and outer" ground surfac'e's'l will be" accurate inconcentricity; By grinding simultaneouslyfeacliground surface is concentric about eral, feed ofthe saddleshould be stopped and the other grinding head 46 should be set in a similar manner. But

in the case of the outside grinding head, as compared to the inside head, it would not have to be lowered into the casting from above. Rather,.it could come straight into the sideuntil it contacted the surface to be ground. With each of the. heads "taking a bite out of its respective surface, 'the stops would then be accurately positioned, the, amount of feed would be determined and sent into meant, and the machine wouldibe thrown into automaticl Each head would take up its reciprocation and its automatic feed, each feeding to the left, as in Figure'3, the feed being elfected at the, top and bottom -,of each StrokeL' The operator would then be through 'until'grindingwas completed. 7

It might happen that. one grinding head would finish its surface before the other, in which case the operator could easily throw' ithat head back on to manual and move it out of contact with the casting, allowing the other head to'cornplete grinding on fautomaticf. If the castings are allof the same general size and dimensions, the machine could be set up with 'a fixed stroke, feed and speed and the operator would merely have to mam ually bring each'head into contact with the Work and then put the machine on automatic. from oneunit to another.

One of the importan t points of thefFigure '1 arrangement is that each-spindle ison the same side ofits pivot. For example,'no te that thespindle 40 is on the righthand But this would vary side and generally"'above its pivot 52. The spindle'42 is i spindle 40'works down and in the .casting, whilethe head 46' works under and-up to the casting, more or less; If

the spindles were symmetrically arranged, relative to their pivot, either b'oth'inside or, both outside, the railwould have to be impossibly long because one'of the spindles would npt be ableto reach workipoint conveniently.

For example, if the spindle 42 was above its pivot 54, to reach the working surface 72 with the head 46, the saddle 36 would have to be moved farther to the right in Figure l and the spindle and rail would have to be extended so that the head could reach the casting. The 'machine would be cumbersome, unnecessarily expensive and require additional floor space and heavier parts. By the arrangement shown, the rail may remain short and the spindles do not have to be excessively long.

In Figure 4, we have shown a variation in which the rail is indicated generally at 20', the saddles at 34 and 36, and the left and right spindles at 40 and 42. The mechanism may be generally the same as in Figure 1. As set forth hereinbefore, the workpiece is a mantle. In this case, we provide an auxiliary or third or inside spindle which includes a saddle 134 mounted on the rail to be moved back and forth and a generally vertical or upright spindle 136. The spindle 136 may carry a suitable grinding head 138 which is adapted to oppose the large end of the mantle. The saddle 134 may be otherwise free and tied to either one of the two outside saddles so as to move with it. For example, we show an interconnection 140 between the saddles 36' and 134 and it may take any suitable form. Accordingly, the auxiliary saddle will move with the saddle 36 but it might be tied to the other saddle 34'. The point is that during feed of either one of the saddles, the center saddle will be moved. The axis A ofjthe center orauxiliary grinding head may be considered to be generallyvertical and parallel to the rotary axis of the workpiece. This axis Adoes not necessarily lie in the same plane with the three axes X, Y and Z in Figure 3, and the axis A, while vertical, may be offset, preferably forward (relative to the machine in Figure 1), but it might be set back. In any event, the important point is that the auxiliary grinding head is fed witheither one of the saddles and it opposes the large edge of, the mantle.

, During the operation of grinding the mantle casting,

as set forth hereinabove, the fit and wearsurfaces may be ground over a period of several hours. Toward the end of that time, we prefer to feed the spindle 136 down so that the grinding head 138 grinds off the upper large edge of the mantle to provide allat control surface. This surface will be at right angles or perpendicular to the axis X which maybe assumed to be the axis of the now accurately ground fit and wear surfaces.

The importance of this control surfaceon the finished mantle is as follows. The mantle fits on the gyratory head of a crusher and is held down on the somewhat conic that this nut seat 144 be finished, preferably by grinding, before the mantle is mounted on a head and the nut turned down.

By providing the control surface at the large end of the mantle, the nut seat maybe accurately ground after the mantle is removed from the grindingsetup of Figure 4 because the control seat will provide a plane, fiat surface perpendicular to the trued axis of concentricity of the liner because the other end of aliner, the small end,

fit and wear surfaces. "The control surface may -be placed down on any smooth, fiat surface, for-example, a

rotary table, and while the piece is rotated the nut seat can be accurately ground, and will be'exact in concenend of one operationand the start of the next may take.

as much as forty-five minutes to an hour. Thisinvolves removing the finished piece and mounting the'next rough casting. To reduce this down time to a minimum, we provide a preassembling arrangementor method.v For example, as shown in Figures '6 and 5, the normal table is indicated generally at 12. To cover this table, we provide a flat plate 146 which conforms generally to the table, may be round, and is clamped or secured to the table in any suitable manner. In this setup. the plate 146 is what might be considered a cover plate for the normal table and it is clamped thereto and left in position. A second plate 148 is clamped on top of the cover plate 146. This second plate is removable, and suitable guides, bosses or other types of centering or piloting means are used so that the plate 148 always fits in the same position on the cover plate 146. As shown in Figure 5, the second plate has right angle, T-shaped

notches

150 and 152 which divide the plate generally into quadrants and it may be provided with a suitable number of. locating holes 154. These holes may be positioned in relation to the size of the standard castings to be ground. The arrangement shown could be varied and the particular locations are not important. The point is that a pattern of holes may be established, either in the notches to serve as stops for the jaws or clamps or outside of the notches or channels in different locations such as at 156. The holes or stops may be suitably marked so that the operator will instantly know which clamps to use in which holes for a particular casting. I I I The important point is thatthe top plate 148 may be set off to the side. For each machine, we might provide two, three, or four such plates. While one casting is being ground, the operator can be setting up another casting with its jaws, clamps, etc. on a second plate. When the grinding operation is completed on thefirst casting, it could be removed and the entire assembly of the casting clamped on a plate could be swung, by a suitable overhead crane .orotherwise, onto the rotary table on top of the cover plate 146. We have found that we can reduce the downtime as much as twenty-five percent by this pre-setup arrangement.

For the larger mantles and liners, we find that it is preferable to always individually mount the piece on the table and jaw and chuck it up, but for the smaller ones, they may be present, such as in Figures 5 and 6.

While we have stated that'the axis of the third or center spindle is offset, either backward or forward, from hey plane of the axes X, Y, and Z, it might be otherwise, and the invention should be understood to include a third spindle which is coplaner with the axes X, Y and Z. The particular size, design and style of adapter plate 146 and carrier plate 148, in Figures '5 and 6,is unimportant, and we have not gone into detail. The ground fit side and wear side on the workpiece, be it a mantle or liner, could be parallel or they could be otherwise. During an automatic operation, the operators judgment is used to determine when sufiicient material has been removed and a smooth ground surface of sufficient axial length has been provided. In Figure 4 we have shown the use of a third or center spindle to provide a control surface on the large end of a mantle generally perpendicular to the mantle'axis or the axis of rotation, and this arrangement would not be used on a does not have'a nut seat. a

This general type of grinding is only considered roughcut work and it is not, in any sense, fine grinding. This grinding is only rough from the standpoint of surface finish. However, .it must be accurate to produce straight concentric surfaces ,and true angles;

- The use, operation and function of our invention are as followsi ,i I

The invention is concerned with a method of grinding 'wearing elements for use with gyratory crushers or the like. Such elements are termed mantles and liners and I l 9 are well-known and quite old. They are normally made of manganese stel which is very difiicult if not impossible to machine. The rough cast workpiece, be it a -mantle or. liner, must be trued before it can be used in t i a crusher.

grinding is done simultaneously, both on the inner and outer surfaces, so that even if the casting is decidedly out of round, the ground surfaces will be accurate in concentricity.

The machine used has decided advantages because it is quite small, on a relative basis, and compact. The crossrail does not have to be unnecessarily long and the spindles are not too largeand cumbersome. The mechanism shown has the distinct advantage that it will handle either mantles or liners without requiring excessive floor space. This is done by pivoting both of the spindles on the same side of their respective pivots, as shown in Figure 1, both on the right side rather than both being either inside or outside.

' The preassembling setup shown and described may be used to reduce the down time of a machine as much as twenty-five percent.

The control panel, swingably mounted around the front of the machine, is of. a particular advantage beand several modifications of our invention, it should be understood that suitable additional modifications, changes, substitutions and alterations may be made without departing from the inventions fundamental theme. In many places, we have only indicated the machine broad- 1y without going into'details because those details are of no importance to this invention, and it should be understood that any suitable mechanism may be used to carry out the functions, steps and operations described. With these and other modifications in mind, we wish that the invention be unrestricted except as by the appended claim.

We claim:

A method of grinding frusto-conic manganese steel mantles to be used on the head of gyratory crushers and the like, including the steps of providing a generally frusto-conic truncated mantle casting, larger at one end than the other, and fully open through its central axis, positioning the mantle casting generally upright, large end up, in a grinding zone, rotating the casting at a generally uniform speed about its axis, simultaneously grinding concentric inner and outer frusto-conic surfaces adjacent the large end of the casting and also a flat control surface at the large end disposed generally at right angles to the axis of rotation, inverting the casting so that it rests on the fiat control surface, and using the control surface as a reference while grinding an inwardly disposed somewhat conical throat surface at the small end of the casting to be engaged by the locking mechanism of the head of the crusher when fully seating the finished mantle in the crusher.

cause it allows the operator to run a piece in without losing sight of or being unable to see or move to where he can see the roughing in, operation of any other' spindle.

While we have shown and described the preferred form References Cited in the file of this patent UNITED STATES PATENTS Flygare Jan. 22, 1957