GB2188253A - Gyratory crusher - Google Patents

Abstract

A gyratory crusher has a conical crushing head 7 that gyrates in an annular lower frame member 3. An upper frame member 8 that seats on the lower frame member 3 in a normal operative position comprises a bowl 9 that cooperates with the head to define a crushing gap 10. Upright, circumferentially spaced double- acting hydraulic jacks 25 are connected between the lower frame member 3 and a tie ring 26 surrounding it; and upright, circumferentially spaced tie rods 27 connect the tie ring 26 with the upper frame member 8. The piston rods of the jacks 25 project downwards. The upper hydraulic chambers of the jacks 25 are normally in communication with a fluid pressure system that maintains fluid in them at a predetermined pressure and comprises an accumulator charged by a hydraulic pump that is controlled by a pressure responsive switch. A relief valve near each jack vents fluid from its upper chamber to its lower one when pressure in the upper chamber exceeds the predetermined value by a predetermined amount, for example when tramp iron, that is uncrushable material, lifts the bowl 9. The lower chambers are normally in communication with a source of unpressurised fluid. A selector valve reverses the connections to the jack chambers to lift the bowl for maintenance purposes. <IMAGE>

Description

SPECIFICATION Gyratory crusher This invention relates to crushers ofthe type wherein a gyratory substantially conical crushing head and a relatively fixed bowl, which is also sometimes called a concave, cooperate to define a crushing gap. The invention is in particular concerned with automatic means in such a crusherwherebythe bowl is biased down to a normal operate position relative to the head, from which position the bowl can rise as necessary to permit substantially uncrushable material to pass through the crushing gap without harm to the crushing surfaces, and whereby the bowl is immediately returned to its operative position after being so elevated.

In a crusher of the type to which this invention relates, a generally conical crushing head is mounted on an upright eccentric shaft to be gyrated by rotation of the shaft. On a relatively stationary frame of the crusher there is an annular crushing bowl which more or less overlies and surrounds the crushing head and cooperates with ittodefineagapthatformsan annular crushing chamber. Material to be crushed is fed downward through the crushing chamberto be crushed between the bowl andthe head asthe head gyrates.

One ofthe problems that has received much attention in the gyratory crusher art is that which arises upon the entry of so-called tramp ironsubstantially uncrushable material- into the annular crushing chamber. If the bowl is confined against rising in relationtothe head when tramp iron is caught inthecrushing gap,thereisa high probability of damagetothecrushingsurfaceofthebowl orthe head, or both, that will put the crusher out of service fora substantial timewhilethe damaged surface is replaced.To prevent such damage, it has been usual to arrange the bowl of a gyratory crusher on an upper frame memberthat normally rests concentrically upon a fixed lowerframe member but can be forced upoffofthelowerframe memberbytrampironinthe crushing chamber. Since the weight ofthe upper frame member is not great enough to hold it down againstthe upward forces exerted upon the bowl during normal crushing, its been more or less conventional to bias the upperframe mem ber downwardly by means of heavy springs whereby the upper frame memberwas maintained firmly seated on the lower one during normal crushing but was permitted to rise underthe greaterforce developed when tramp iron was present.The springs had to be under a substantial preload by which the bowl was held down, and when the bowl was lifted bytramp i ron, this already-high force on the springs was further substan- tially increased. Usually such a spring arrangement prevented serious damage to the crushing surfaces, but it nevertheless required a fairly prolonged shutdown ofthecrusherfor removal oftramp iron because the spring force had to be relieved and the upper frame member had to be lifted enough to permitthe tramp iron to fall through the crushing gap.Relief of spring tension usually entailed the removal of nuts on numeroustierodsthatextendedthroughthesprings and transmitted spring forcestothe upperframe member; and during such disassembly the high energy stored in the springs endangered those doing the work.

The serious and troublesome nature of the tramp iron problem is attested by the relatively large number of patents that have issued on expedients intended to solve it.

One ofthe earliest ofthese was U.S. Patent No.

2,679,984 to Gruender, issued in 1954, wherein the generally conventional springs were replaced by pneumatic pressure cylinderjacks that normally maintained a yielding predetermined downward biasing force upon the upperframe member. The upper frame member could rise underthe force exerted by tramp iron in the crushing chamber, increasing the pressure in the pneumatic system, which thus functioned analogously to springs exceptthat pneumatic pressure was not allowed to exceed a predetermined maximum value that was established by a reliefvalve.

Forfreeing thetramp iron, pressure in the cylinders could be relieved by opening a manually operable valve, and the upperframe memberthen had to be lifted. Although offering advantages over a spring biased upperframe member, the arrangementcould not provide for powered lifting ofthe bowl when elevation of the bowl became necessary, and it had the further important disadvantage that it needed a large supply of air at high pressure and therefore was not energy efficient.

The employment of single-acting fluid pressure jacks to exert normal downward bias upon an upper frame memberwas also disclosed in two U.S. patents to Johnson, No.3,118,623 (reissued as Re 29,970) and No.3,281,083, and in U.S. Patent No.3,038,670 to Becker. In the apparatus ofthese patents the cylinder jacks functioned in substantially the same manner as the springs thatthey replaced, except that there was provision for manual relief of the biasing force that the jacks exerted.

In another approach to the problem, disclosed in U.S. Patent No. 3,140,635to Balmeretal, springswere employed to bias the upperframe member downwardly in a more or less conventional manner, and manually controlled single-acting fluid pressure jacks were arranged to liftthe upperframe member against the biasing force ofthe springs when tramp iron was caught in the crushing gap. U.S. Patents No.3,009,660 to Symons et al and No.3,162,387 to Symons disclose other arrangements employing the same general principles.

U.S. Patent No.2,597,548 to Traylor, Jr., disclosed an arrangement wherein fluid piston devices equipped with one-way bleed valves permitted tramp iron in the crushing gap to liftthe bowl against spring bias but whereby downward spring biased return motion ofthe bowl was retarded to allow time for the tramp iron to pass out ofthe crushing chamber. In practice this arrangementwas not likely to be consistently operative, because the biasing force of the springs increased asthe bowl rose, andthetramp iron could not liftthe bowl above a level at which it was clear of thetrampiron; hence spring force on the bowl could continue to hold the tramp iron captive in the crushing chamber.

In the crusher of U.S. Patent No.3,396,916 to Kemnitz et al, the bowl or concave was surrounded by a cylindrical wall on the fixed lowerframe member that cooperated with a cylindrical outer surface on the bowl to define an annular hydraulic cylinder, and the bowl had a circumferential flange which was received in that cylinderto serve as its piston. Pressure fluid in the annular cylinder, above and below the circumferential flange, controlled the heightwise position of the bowl and could be used to raise the bowl for release oftramp iron. The bowl was hydraulically locked atthe selected height and therefore could not yield upwardly to any significant extent until a valve in the hydraulic system was manually shifted for raising it.

In the crusher of U.S. Patent No.2,791,383 to Kjeigaard, a number of double-acting hydraulic jacks were connected between the lower frame and an upperframe mem ber that comprised the bowl . Fluid under a predetermined pressure was maintained in the lowerchambers of the jacks, and fluid that was in effecttrapped intheirupperchambersheldthebowl at a desired height. For adjusting the bowl downward there was a hand pump by which fluid could be forced into the upper chambers of the jacks, and for adjustingly raising the bowl there was a manually operable valve through which the upper chambers could be controlledly drained.Also connected with the upperjack chambers was a pressure reliefvalve which opened for quickly draining those chambers if pressure in them exceeded a predetermined value as when tramp iron in the crushing gap exerted an upward force on the bowl-thus automatically raising the bowl fortramp iron release. After each such tramp iron release the bowl had to be brought back down to its operative position by operation ofthe hand pump. The apparatus had thefurtherdisadvan tagethat any leakage offluid outoftheupper jack chambers allowed the bowl to rise, increasing the width of the crushing gap; and the bowl then had to be readjusted backto a position thatwas indeterminate in the first place.

U.S. Patent No.3,754,71 6to Webster disclosed a generallysimilararrangementwhereinthe hand pump of Kjelgaard was replaced by an electrically driven pump and wherein the adjusted position ofthe bowl was sensed electrically. When the bowl was raisedforreleaseoftramp iron, itwas maintained in its lifted position for a predetermined period of time and thereafter was brought back down automatically to the electrically sensed position that it had occupied just before being raised. The electrical and hydraulic control system had to be rather complicated because the bowl had no mechanically defined position, and every jack had to be individually controlled in order to preventthe bowl from being established in a tipped position.

U.S. Patent No.2,680,571 to Bjarme disclosed a structurewhereindouble-acting pneumatic jacks were arranged to maintain a normal downward biasing force upon an upperframe memberthat comprised a concave. There was no provision for automatic relief of the downward bias when tramp iron was present in the crushing gap, but a manually operable valve could be repositioned to so reconnect thejacksthattheyliftedtheupperframe memberfor release of tramp iron. In common with the arrangments disclosed in certain of the other patents discussed above, the pneumatic jacks in the crusher of the Bjarme patent were located at the top ofthe crusher, and in fact they projected a substantially distance abovethe top of the upperframe member.

Such an arrangement is undesirable because it adds to the height ofth-ecrusherso that the machine is not adaptable to all installations. Furthermore, material to be crushed is fed into a gyratory crusherfrom above and it must therefore beliftedto a level from which it can fall into the cruslTèr; hence, energy required for feeding material into a-crusher is directly related to the height ofthe crusher. Overthelong life of a crusher, and considering that the feed m-aterial is usually heavy, every additional inch of crusher height can entail a very significant cumulative energy expenditure.

The above discussed prior patents, and others like them, disclose thatthere has been a long standing need and desire to provide gyratory crushers with effective meansforsensing the presence oftramp iron or other uncrushable material in the crushing gap and for promptly and automatically relieving downward force on the bowl in responseto sensing of such material. A basic problem with respect to the provision of such automatically responsive apparatus is that of detecting the presence oftramp iron in the first place. Heretofore, in non-automatic systems, deceleration or stalling of the crusher drive motor has often been relied upon to signal the presence oftramp iron; but bythetime rotor deceleration becomes perceptible, a substantial amount of damage can already have occurred.When the upper frame member that carries the bowl is not hydraulically locked against rising, as it was in the above-discussed Kjelgaard patent, an early and significant manifestation of the presence of tramp iron is a tilting rise ofthe upperframe member. Since such lifting can occur anywhere around the periphery ofthe crusher, an operator at a fixed control station is not in a good position to observe it immediately and react promptly to it. Any automatic device that provides for a yielding downward force upon the bowl, so that it can be lifted in response to the presence oftramp iron, must:l;ikewise take accountof the tilting that the bowl tends to undergo when tramp iron is caught in the crushing gap.

It is not imperative tbatthe bowl be positively lifted upon the detection oftramp iron in the crushing gap, to be held high enoughforthetramp iron to fall freely through the gap, but an automatic tramp iron release should at least beso arranged that there is no substantial increase in the downward force upon the bowl as it rises, so that the bowl can be lifted by the upward force that tramp iron exerts upon it. On the other hand, during normal operation the bowl should be confined in a defined operative position buy a downward force upon it that yields to the lifting action of tramp iron. The normal position ofthe bowl should be defined in such a manner-preferably by solid abutment means-that the bowl can be brought directly back to it after being so lifted.

It will be apparent atthis pointthat providing forthe presence oftramp iron in a gyratory crusher is not a simple problem but instead presents numerous requirements, some of which are in apparent conflict with others. Heretofore no arrangement has been proposed that solves the basic problem and satisfies or resolves all the requirements and desiderata.

The present invention is concerned with a crusher of the type comprising a cone or crushing head that gyrates in a stationary lowerframe member and cooperates with a bowl or concave to define a crushing gap, and the general object of the invention is to provide energy-efficient means whereby a predetermined downward force is normally imposed upon the bowl, to maintain it seated upon the lower frame member in an operative position, and whereby such downward force is prevented from increasing to any substantial extent when lifting of the bowl occurs, as from the presence of tramp iron in the crushing gap.

Thus, according to one aspect ofthis invention, a gyratory crusher comprises a cone that gyrates in an annular relatively stationary lowerframe member, an annular upper frame member which is normally supported and engaged against the lower frame membersothatitoccupiesadefinedoperating position, a bowl which cooperates with the cone to define a crushing gap, and bowl control meansfor normally imposing upon the upperframe member a predetermined downward force that tends to maintain the upperframe member in its operating position, the bowl control means being characterised by:: A. a plurality of double-acting hydraulicjacks disposed at circumferentially spaced intervals around the upper and lower frame members, each jack comprising a piston which is slidable in a cylinder having a pair of pressure chambers at opposite sides of the piston; B. means so connecting each of the jacks between the upper and the lower frame members that hyd raulicfluid pressure in one of the chambers of the jack cylinder is translated into a downward force upon the upperframe member; C. hydraulic pressure means normally in communication with the one of the chambers of every jack cylinder, the hydraulic pressure means providing a source of hydraulic fluid ata substantially predetermined pressure and comprising: (1) an accumulator; (2) a pumpforchargingtheaccumulatorwith hydraulicfluid; and, (3) pressure responsive control means operatively associated with the pump and the accumulatorfor directing hydraulicfluid from the pump to the accumulatorwhenthefluid atthe accumulator is at less than the predetermined pressure and for prevent ingchargingoftheaccumulatorwhenthefluidthereat is at su bstantia l ly the predetermined pressure;; D. normally closed relief valve means connected between the one ofthe chambers of every jack cylinder and the other chamberthereof, the relief valve means being arranged to open for transferring fluid from the one ofthe chambersto theother chamberwhen the fluid in the one ofthe chambers is at a pressure which exceeds the predetermined pressure buy a predetermined amount; and E. means venting the other chamber of every jack cylinderto a source of unpressurised fluid at all times that the crusher is in crushing operation.

A crusher constructed in this way can be madeto respondtothepresenceofuncrushablematerial in the crushing gap by allowing the bowl to liftto an extent that allows such material to pass through the crushing gap, and to do so without substantial increase in the reaction forces impose upon the opposing surfaces of the bowl and the crusher head by the material between them, so that those surfaces suffer no greater damagefrom tramp iron in the crushing gap than from the crushable material they are intended to act upon.

In this way a very long useful lifeforthecrushing surfaces of the gyratory crusher can be provided.

The crusher permits tramp iron and the like to work through the crushing gap without stalling the crusher and without endangering the crushing gap surfaces, the crusher can be madeto do this in a fully automatic manner in the sense that it requires no attention on the part of an operator, neither for effecting relief of downward force upon the bowl when tramp iron is present in the crushing gap norforrestoration of such downward force when the tramp iron has passed throughthecrusing gap.

The crusher may also preferably be arranged to produce a signal for alerting an operator to the presence oftramp iron in the crushing gap and to the consequent need for removing the tramp iron from the output of the crusher.

The crusher in accordance with the invention has no need for the powerful springs heretofore employed for biasing the bowl downward to its operative position,thus eliminating the dangers that such springs presented to personnel working around the crusher, especially at times when the blow had to be raised for service or repair.

It is possible for a crusherwhich is designed for the heretofore conventional bowl hold-down springs, to be modified to make it in accordance with the invention without requiring extensive or costly modification ofthecrusher structure to adapt it.

The crusher may have a simple manually operable control valve that can be placed in one position for hydraulically lifting the bowl to a substantial elevation, for service or maintenance, and can be placed in another position for normal crushing operation with automatictramp iron accommodation as above described.

In most gyratory crushers the bowl has a screwthreaded connection with the upperframe member, so that the crushing gap can be adjusted by rotation of the bowl in the upperframe member, to vary the heightwise position of the bowl relative to the cone; and normally a locking ring or similar expedient is provided for preventing undesired rotation ofthe bowl. The crusher in accordance with the invention may be constructed in such a way that it in no wise conflicts or interferes with conventional arrange mentsforadjustingtheheightwiseposition ofthe bowl and for locking it in any selected position of heightwise adjustment.

The present invention also consists, according to another of its aspects, in a gyratory crusher comprising a cone that gyrates in an annular relatively stationary lowerframe member and an annular upper frame member comprising a bowl that cooperates with the cone to define a crushing gap, the crusher being characterised by: A. cooperating abutment means on the upper and lower frame members, the abutment means being engageable for support ofthe upperframe member upon the lowerframe member in a predetermined operative position from which the upperframe member can be raised; B. a plurality of double-acting hydraulic jacks arranged at circumferentially spaced intervals around the lowerframe member and having:: (1) a cylinder with a substantially upright axis, (2) a piston slidable in the cylinder and having a downwardly projecting rod, and (3) upperand lower pressure chambers in the cylinder, at opposite sides ofthe piston, and wherein (4) the lower chamber of every cylinder is vented to a zone of unpressurised fluid at all timesthatthe crusher is in crushing operation; C. means providing a swivel connection between the upper end of each jack cylinder and the lowerframe member, nearthetop ofthe lowerframe member; D. a tie ring which surrounds the lowerframe member and to which the piston rod of each jack has a swivel connection;; E. a plurality of elongated uprighttie rods which are arranged at circumferentially spaced intervals around the frame members and through which upward and downward forces that the jacks impose upon the tie ring aretransferred to the upperframe member, each ofthetie rods (1) having at its lower end a connection with the tie ring and (2) having at its upper end a connection with the upperframe member;; F. hydraulic pressure means normally in communication with the upper chamber of every jack cylinder and providing a source offluid at a substantially predetermined pressure, the hydraulic pressure means comprising (1) an accumulator, (2) a pump for charging the accumulator with hydraulic fluid, and (3) pressure responsive control means operatively associated with said pump and said accumulatorfor directingfluidfrom said pump to said accumulator when fluid atthe accumulator is at less than the predetermined pressure and for preventing charging of the accumulator when fluid thereat is at the predetermined pressure; and G. reliefvalve means adjacent to said cylinder of each jack, arranged to open when hydraulicfluid in the upper chamber ofthe jack has a pressure which exceeds the predetermined pressure bya predeter minedamounttoallowtheflowoffluidfromtheupper chambertothe lower chamber of the jack.

According to yet another of its aspects, the invention consists in a gyratory crusher comprising a cone that gyrates in an annular relatively stationary lower frame member and an annularupperframe member comprising a bowl that cooperates with the cone to define a crushing gap, the crusher being characterised by:: A. cooperating abutment means on the upper and lowerframe members,the abutment means being engageabletosupportthe upperframememberupon the lower frame member in predetermined operative position from which the upperframe member can be raised; B. a plurality of double-acting hydraulic jacks at circumferentially spaced intervals around the lower frame member, each jack having (1) a cylinder with a substantially upright axis, (2) a piston slideable in said cylinder, and, (3) a pair of pressure chambers in the cylirfder, at opposite sides ofthe piston; C. means connecting each ofthe jacks to act between the upper and lowerframe members where; by hydraulicfluid under pressure one of the chambers ofthe jack imposes a downward force upon the upperframe memberthat tends to maintain it in its operative position; D. a selector valve having connections with both of the chambers of every jack and having alternatively selectable normal and bowl-raising conditions; E. a sourse of substantially unpressurised fluid which is connected with the selectorvalve for communication therethrough with the other chamber of everyjackwhen the selector valve is in its normal position and for communication with the one chamber of every jack when the selectorvalve is in its bowl-raising position;; F. hydraulic pressure means connected with the selectorvalve for communication therethrough with one chamber of every jack when the selector valve is in its normal position and for communication with said other chamber of everyjackwhen the selector valve is in its bowl-raising position, the hydraulic pressure means comprising (1) an accumulator, (2) a pumpfordrawing fluid from the source and charging the accumulator, and (3) pressure responsive control means operatively associated with the pump and the accumulatorfor directing fluid from the pump to the accumulator when thefluid atthe accumulator is at lessthan a predetermined pressure and for preventing charging ofthe accumulatorwhen fluid thereat is at substantiallythe predetermined pressure; and G. pressure relief valve means adiacentto each of the hydraulic jacks, the reliefvalvemeans being arranged to open when pressureoffluid in the one chamber of an adjacent jack exceeds the predetermined pressure by a predeterinined amount and which, when open, places the one chamber of the jack in communication with its other chamber.

An example of a gyratory crusher in accordance with the invention will now be described with reference to the accompanying drawings in which: Figure lisa view in vertical section through the gyratory crusher; Figure 2 is a circuit diagram ofthe meansfor controlling an upperframe member in the gyratory crusher shown in Figure 1; and Figure 3 is an enlarged fragmentary view in section, taken on the plane ofthe line 3-3 in Figure 1.

Referring now to the accompanying drawings, the numeral 3 designates generally a relativelyfixed lowerframe member of a gyratorycrusherwhich embodies the principles of this invention. The lower frame member3 has an uprightannularwall4that defines the loweroroutlet portion 5 of a crushing chamberwithin the crusher. Mounted on an eccentric shaft6inthe lowerfrarne member3 isa coneor crushing head 7 that is given a gyratory motion by rotation ofthe shaft 6. Concentrically seated on top of the annularwall 4 ofthe lowerframe member is an upperframemember8thatcomprises an annular frusto-concial concave or bowl 9 which converges upwardly and thus faces downwardly and inwardly.

The bowl or concave 9, which is in upwardly surrounding relation to the crushing head 7, cooperates with the crushing head to define a more or less annular crushing gap 10 that comprises the crushing chamber proper.

The eccentric shaft 6 and the crushing head 7 that it drives are mounted in sturdy bearing 12 in the lower frame member 3. Rotation is imparted to the eccentric shaft6 by means of a horizontally extending drive shaft 1 4that is also journaled in the lower frame member.

The rim portion ofthe annularwall 4 of the lower frame membertapers upwardly, being formed with one concentric conical surface 1 6 that faces obliquely upwardly and radially inwardly and another concen tricconicalsurface 17 that faces obliquely upwardly and radially outwardIyArnund the bottom of the annularupperframemember8thereisadownwardly opening circumferential groove 18 that has downwardly divergent surfaces which mate with the conciai surfaces 16 and 17 on the lowerframe member, so that when the upperframe member is seated on the lower one it is maintained concentric to the lower one by the cooperation ofthose mating surfaces.

The bowl or concave 9 comprises an annular bowl support 20 which has a screw-threaded connection 21 with the upperframe member 8. A bowl liner 22 that serves as the stationary crushing surface of the machine is secured to the bowl support 20 in such a mannerasto be readily detachable therefrom for replacement The threaded connection 21 between the upperframe member 8 and the bowl support 20 enables the bowl support to be adjusted up and down in relation to the upperframe member, and hence in relation to the cone or crushing head 7, to provide for adjustment ofthe width ofthe crushing gap 10. Since crushing action imposes a tangential force upon the bowl, a locking ring 23 is threaded into the upper frame member 8to releasably confine the bowl support 20 against rotation.The particular bowl and locking ring arrangement here illustrated is described and claimed in the copending Polzin et al application, Serial No. 21,721,filed March19, 1979, which has a common assignee with this application. As the description ofthe present invention proceeds, it will become apparent that the particular form of connec- tion between the upper frame member 8 and the bowl support 20 is in no wise material to the present invention because the invention is adaptable to crushers with practically all known arrangements for bowl support and bowl locking.

Material to be crushed isfed intothe annular crushing gap 10 by way of a funnel-like hopper 24 on the bowl support, and such material passes through the downwardly tapering crushing gap lotto be crushed between the bowl liner 22 and the crushing head 7 as the latter gyrates.

Itwill be apparent that crushing action imposes upon the bowl 9 a substantial upward force thattends to liftthe upperframe member8 outof its seated engagement upon the lower one. With the arrangement ofthe present invention, such upward forces are yieldingly resisted by hold-down means comprising a plurality of double-acting cylinderjacks 25, a tie ring 26 and a plurality of tie rods 27. The double-acting cylinder jacks 25 are connected between the fixed lowerframe member3 and the tie ring 26, while thetie rods 27 connectthetie ring 26 with the upperframe member 8.

The double-acting cylinderjacks 25 are arranged at regular circumferential intervals in a circle around the fixed frame member 3, with their axes parallel to the crusher axis and equidistant therefrom. The cylinder 35 of each jack 25 thus has an upper or blind end chamber59 above its piston 36and a lowerorrod end chamber 60 below its piston. The connection of each jack 25 to the fixed lower frame member 3 comprises a sturdy radially outwardly projecting flange 28 on the lowerframe member, near its top, to which the upper end ofthe jackcylinder35 has a swiveling connection 29. As best seen in Fig. 3, the flange 28 has a pair of fixed downwardly projecting lugs 30 for each swiveling connection 29.A horizontal pin 31 that extends transverselyto the lugs 30 and is fixed in them carries a coaxial spherical element 32, and the jack cylinder has a spherical socket 33 at its upper end in which the spherical element 32 is engaged. The jack is thus free for iimited swinging in all directions about its connection with the flange 28.

The piston rod 36' of each jack has a swiveling connection 38 to thetie ring 26 that is generally like the upper swivel connection 29. Because each jack has its cylinder 35 uppermost and its piston rod 36' projecting downwardly,the piston rod isto some extent protected from dust and dirt bythe cylinder above it. In addition, the piston rod 36' is surrounded by a protective axially expansible and contractable boot 37 of rubber or the likethat extends between the cylinder 35 and thetie ring 26.

The tie ring 26, which surrounds the lower frame member 3 nearthe bottom thereof, is moved down by extension ofthe jacks 25 and moved up by their retraction. The tie ring 26 is substantially confined to such up and down motion, and is restrained against substantial rotational and radial motion, by cooperating guide means on it and on the lowerframe member 3comprising (as best seen in Fig. 3) a pairoftubular guide elements 40 that project down from the tie ring at diametrically opposite locations on it, and a pair of upright stud-like guide elements 41 that are fixed to flange-like supports 42 nearthe bottom ofthe lower frame member, at opposite sides thereof, and project up into the respective tubular guide elements 40 with a loose sliding fit.

The lifting and lowering forces that are imposed upon the tie ring 26 by the jacks 25 are in turn transferred to the upperframe member8 bythe uprighttie rods 27, which are spaced at uniform circumferential distances from the jacks and alternate with the jacks around the lowerframe member 3. Each tie rod 27 is connected at its lower end to the tie ring 26 and is connected at its upper end to a circumferential radially outwardly projecting force-receiving flange 44 on the upperframe member 8.The flange 44 is near the bottom ofthe upperframe member8 but is spaced above the jack supporting flange 28 onthe lower frame member Each tie rod27 passes th rough the jack supporting flange 28 on the lowerframe member at a hole therein that affords substantial clearance for the tie rod.

Both end portions of each tie rod 27 arethreadedto receive nuts 46-49 that provide abutments by which vertical forces are transferred to and from the tie rod.

Thus the lower end portion of each tie rod 27 extends through a hole in thetie ring 26, and nuts 46 and 46 above and below the tie ring substantially constrain thetie ring andthetie rod to move up and down in unison, although preferably with a little lost motion between them, and nuts 48 and 49 atthetop ofthe tie rod similarly connect it with the flange 44 on the upper frame member. The tie rod holes in thetie ring 26 and the upper flange 44fitthe tie rods 27 somewhat loosely, and together with the slightly loose connections provided by the nuts 46-49 they allow the tie rods to swing or swivel to some extent relative to the tie ring 26 and theflange44,thus accommodating tilting ofthe upperframe member8 and the tie ring 26 relative to the tie rods.

Itwill be evidentthatthe adjustability of the nuts 47 and 48 allows downward biasing forcesthat originate from the jacks 25 to be imposed upon the upper frame member8 uniformly all around it. It will also be noted that neitherthejacks 25 nor the tie rods 27 increase the height ofthe crusher since they are located wholly belowthe level ofthetop ofthe upperframe member 8 and are, moreover, compactly arranged close to the sidesurfaces ofthe crusher body. Furthermore, since the upperframe member 8 is lifted out of engagement with the lowerframe member3 by retraction of the jacks 25, the inherently greater force exerted for extension ofthe jacks is employed to hold down the upperframe memberagainstcrushing forces which tend to lift it.

However, by reason of the hydraulic circuitthat is diagrammatically illustrated in Fig. 2, the downward force thatthe jacks 25 impose upon the upper frame member 8 is maintained at a predetermined value and isayielding one that permitsthe upperframe member to be lifted bytrampiron orthe like inthe crushing gap 10. The hydraulic circuit also ensures that there will be no substantial increase in that downward force when any lifting oftheupperframe member occurs.

In general the hydraulic circuit apparatus comprises an accumulator53for maintaining fluid in the system under pressure, a pump 50 for charging the accumulatorwith fluid drawn from a reservoir 52, and pressure control means (described hereinafter) cooperating withthepumpandtheaccumulatorto maintain fluid pressure atthe accumulator at substantially a predetermined value The pump 50 is preferably driven by an electric motor 51, and the pressure control means can therefore comprise a pressure responsive switch 55 bywhichthe motor51 isturned on and offas necessary to maintain pressure atthe accumulator at said predeterminedvalue.The pressure control means can also comprise a relief valve 56 that opens in the event fluid pressure at the accumulatorsubstan- tially exceeds said predetermined value, discharging the excees fluid to the reservoir 52. A check valve 54, connected downstream from the pump 50 but up stream from the accumulator 53 and the relief valve 56, prevents the accumulatorfrom discharging through the pump when the pump is not operating.

At the pressurefluid port of the accumulator 53 there is a needle valve 72 that can be manually closed to cut off the accumulatorfrom the restofthe hydraulic system for service and maintenance. Nor mally,the needle valve 72 is open, and it has some throttling effect upon flow offluids into and out ofthe accumulator, although it does not present enough restriction to fluid flow to have any material effect upon charging ofthe accumulator by the pump 50.

The hydraulic pressure system just described is connectable with the several hydraulicjacks 25 through a manually operated selector valve 57. In a normal position ofthe selector valve 57, in which it is shown in Figure 2, it communicates the fluid port of the accumulator53 with a headerormanifold 58thatis in turn communicated with the upper (blind end) fluid chamber 59 of every jack cylinder 35. The lower (rod end) chamber 60 of each cylinder 35 is communicated with another manifold 61. When the selector valve 57 is in its normal position, itcommunicatesthe manifold 61 with the reservoir 52.The reservoir 52 is so located thatfluid in it has a normal level somewhatabovethat ofthe manifold 61, sothatfluid at substantially zero pressure normallyfillsthe manifold61 and the lower chambers 60 ofthe jacks. The two manifolds 58 and 61 are preferably circular, in surrounding relationtothe crusher, for convenient connection to the respective cylinder chambers 59 and 60 of all of the jacks 25.

Itwill now be apparentthatwhen the selectorvalve 57 is in its normal position, which it always occupies when the crusher is operating, there is fluid in the upper (blind end) chambers 59 of the jack cylinders at the predetermined pressure maintained by the accu mulator 53, and such pressure fluid imposes upon the upperframe member8 a strong but yielding downward bias that tends to maintain the upperframe member in its operative position, seated upon the lower frame member 3. Since there is zero pressure in the lower cylinder chambers 60, the magnitude of the downward biasing force exerted by the jacks 25 is determined by the pressure maintained atthe accumulator 53.

If there is any leakage in the hydraulic system (e.g., across pistons 36), the pump50operatesautomatical- ly, under control of the pressureswitch 55, as and when the accumulator needs recharging,formaintenance of the predetermined fluid pressure. Thus the motor 51 which is the only energy-consuming device in the bowl control apparatus-operates only infrequently and then only for short periods.

Connected between the upper chamber header 58 and the lower chamber manifold 61 are a plurality of reliefvalves 67, each of which is adjusted to open and passfluidfromtheheader58intothemanifold61 when pressure in the header 58 exceeds the above mentioned fluid pressure value by a predetermined amount. Preferably there are enough ofthe relief valves 67 so that there is one for each pair of jacks 25, and each reliefvalve 67 is so located asto be near the connections of its pair of jack cylinders with the header 58 and the manifold 61.

When tramp iron or other uncrushable material entersthecrushing gap 10 and exerts upon the upper frame member8 a high enough upward force to raise it from its operative position, such lifting will usually occur at only one side ofthe crusher, and consequently only one or a fewjacks 25 at that side of the crusher will have their pistons 36 raised by the lifting of the bowl. When the piston rises in an affected jack, there is of course a more or less abrupt increase in the pressure offluid in its upper chamber 59.Owing to the throttling effect ofthe needle valve 72 and the greater distance ofthe accumulator 53 from the affected jack, the increased pressure is imposed upon the adjacent reliefvalve 67, ratherthan being applied to substantial charging ofthe accumulator,andthat reliefvalve 67 opens promptly, thus relieving pressure in the upper chamber59 and transferring fluid into the lower chamber 60 ofthe same cylinderto prevent cavitation in it. The amount offluid discharged from an upper blind end chamber 59 is somewhatgreaterthan is needed to fill the void in the lower rod end chamber 60, and the excess fluid drains to the reservoir 52 through the manifold 61 and the selectorvalve 57.To ensure prompt opening ofthe reliefvalve 67 and fast transfer offluidfrom an upperchamber59to a lower chamber 60, it is considered desirable to enlarge the ports of commercially available double acting cylinders employed as the jacks 25.

A reliefvalve 67 will of course reclose before pressure in the adjacent chamber 59 is fully relieved; but itwill be apparentthatthe apparatusfunctions in such a mannerthat even when the upperframe member rises to accommodate tramp iron in the crushing gap 10, the downward bias exerted upon the bowl (and imposed by it upon material in the crushing chamber) will not substantially exceed the normal downward bias maintained upon the bowl during crushing. This meansthattramp iron in the crushing gap 10 will not exert upon the opposing surfaces of the bowl 9 and cone 7 any substantial greaterforcethan those surfaces are required to sustain during normal crushing, and consequently those surfaces are unlikelyto be damaged bythetramp iron.Furthermore, because ofthe continuance of near normal forces on the crushing surfaces, the cone 7 will continue to gyrate in the normal manner instead of being stalled, andthetramp iron will beworkedthroughthe crushing gap 10 while the bowl rises as necessaryto accommodate it. Oncethetramp iron has passed through the crushing gap, the upperframe member 8 will promptly reseat itself underthe continuing downward bias upon it. The pump 50 may operate brieflyforrechargingtheaccumulator,to makeupfor the small loss offluid from the pressure system that occurs during passage oftramp iron.

Because ofthe uneventful manner in which tramp iron is dealt with bythe crusher, it is desirable to alert an operator to the passage oftramp iron through it, for removal of such material from the crusher output. To that end a pressure responsive switch 62 is so connected in the hydraulic system as to be closed by pressure high enough to open one of the relief valves 67, and a signalling device 66 is electrically connected with that switch to be energized by its closure.

The apparatus ofthis invention provides in a very simple and efficient mannerforfull elevation ofthe upperframe member8 and the bowl 9to a raised position in which the bowl structure is accessible for repairand maintenance. For such powered bowl lifting the selector valve 57 is manually actuated to a position in which it communicates the accumulator 53 with the lower chamber manifold 61 and communicatesthe upper chamber manifold 58 with the reservoir 52. The lower chambers 60 of the jack cylinder are then supplied with fluid at the pressure maintained attheaccumulatorwhilethe upper chambers 59 are vented to the reservoir 52.For safety, a pressure relief valve 74 is preferably connected to the manifold 61 with aventoutlettothe reservoir 52, for preventing pressure in the manifold 61 from exceeding the above-mentioned predetermined value by more than a predetermined amount.

Preferably the selector valve 57 is a three-position valve which can also be placed in a cut-off position at which the jack cylinders 35 and their manifolds 58,61 are disconnected from the pressure system that comprises the accumulator 53, to facilitate repair and maintenance work on the apparatus.

By way of example, in atypical apparatus embodying this invention, the predetermined fluid pressure at the accumulator53was a nominal 1549 psi, that is, the pump 50 started whenever pressure dropped to 1400 psi and stopped when it reached 1540 psi; and each of the several relief valves 56,67 and 74 was adjusted to open at 1600 psi. The difference between the 1540 psi predetermined pressure and the 1600 psi relief valve pressure was great enough to prevent undesired opening ofthe reliefvalves but small enough so that forces upon the crushing surfaces never materially exceeded those imposed upon them normal crushing operation.

From the foregoing description taken with the accompanying drawings it will be apparent that this invention provides simple and effective means for preventing tramp iron damageto a gyratorcrusher and for enabling tramp iron to passthrough the crusherwithoutinterruption of normal crushing operation.

Claims (10)

1. Agyratorcrushercomprisingaconethat gyrates in an annular relatively stationary lowerframe member, an annular upperframe memberwhich is normally supported and engaged against the lower frame member so that it occupies a defined operating position, a bowl which cooperates with the cone to define a crushing gap, and bowl control means for normally imposing upon the upperframe member a predetermined downward force that tends to maintain the upper frame member in its operating position, the bowl control means being characterised by:: A. a plurality of double-acting hydraulicjacks disposed atcircumferentiallyspaced intervals around the upper and lower frame members, each jackcomprising a piston which is slidable in a cylinder having a pair of pressure chambers at opposite sides ofthe piston; B. means so connecting each of the jacks between the upper and the lowerframe members that hyd raulicfluid pressure in one ofthe chambers ofthe jack cylinder is translated into a downward force upon the upperframe member; C. hydraulic pressure means normally in com munication with the one ofthe chambers of every jack cylinder, the hydraulic pressure means providing a source of hydraulic fluid at a substantially predeter mined pressureandcomprising:: (1) an accumulator; (2) a pumpforchargingtheaccumulatorwith hydraulicfluid; and, (3) pressure responsive control means operatively associated with the pump and the accumulatorfor directing hydraulicfluidfromthe pump to the accumulatorwhen the fluid at the accumulator is at less than the predetermined pressure and for preventing charging ofthe accumulatorwhen the fluid thereat is at substantially the predetermined pressure;; D. normally closed reliefvalve means connected between the one ofthe chambers of every jack cylinder and the other chamberthereof, the relief valve means being arranged to open for transferring fluid from the one ofthe chambers to the other chamberwhen the fluid in the one ofthe chambers is art a pressure which exceeds the predetermined pressure by a predetermined amount; and, E. means venting the otherchamberofeveryjack cylinder to a source of unpressurised fluid at all times thatthe crusher is in crushing operation.

2. Acrusheraccordingto Claim 1,furthercharacte- rised by: F. selector valve means connected with the chambers ofthe jack cylinders with the hydraulic pressure means and with the source of unpressurised fluid, said selector valve means (1) having a normal position in which it places (a) the one of the chambers of every cylinder in communication with the hydraulic pressure means and places (b) the other chamber of every cylinder in communication with the source of unpressurised fluid, and (2) having an alternatively selectable bowl-raising position in which it places (a) the other chamber of every cylinder in com munication with the hydraulic pressure means and places (b) the one of the chambers of every cylinder in communication with the source of unpressurized fluid.

3. Acrusheraccordingto Claim 1 or Claim 2, wherein the means connecting each ofthe jacks between the upper and the lowerframe members comprises: (1) afirst radially outwardly projecting circumferen- tial flange on the lowerframe member nearthetop thereof, the cylinder of every jack being connected to thefirstflange; (2) a tie ring movablysurrounding the lower frame member in downwardly spaced relation to the first flange, the piston of every jack being connected to the tie ring; (3) a second radially outwardly projecting circum ferential flange on the upper frame member, spaced above the first flange; and (4) a plurality of elongated tie rods arranged at circumferentially spaced intervals around theframe members, each tie rod having at a lower end thereof a connection with thetie ring and at an upper end thereof connection with the second flange.

4. A gyratory crusher comprising a cone that gyrates nan annular relatively stationary lowerframe memberandanannularupperframemembercom- prising a bowl that cooperates with the cone to define a crushing gap, the crusher being characterised by: A. cooperating abutment means on the upper and lower frame members,th;e abutment means being engageable for support ofthe upper frame member upon the lower frame member in a predetermined operative position from which the upperframe member can be raised; B. a plurality of double-acting hydraulicjacks arranged at circumferentially spaced intervals around the lowerframe memberandhaving::- (1) a cylinderwith a substantially upright axis, (2) a piston slidable in the cylinder and having a downwardly projecting rod, and (3) upperand lower pressure chamberin the cylinder, at opposite sides ofthe piston,and wherein (4) the lower chamber of every cylinder is vented to a zone of unpressurised fluid at all times that the crusher is in crushing operation; C. means providing a swivel connection between the upper end of each jack cylinder and the lower frame member, nearthetop ofthe lower frame member; D. a tie ring which surrounds the lowerframe member and to which the piston rod of each jack has a swivel connection;; E. a plurality of elongated upright tie rods which are arranged at circumferentially spaced intervals around theframemembersandthroughwhich upward and downward forces that the jacks impose upon the tie ring are transferred to the upperframe member, each of the tie rods (1) having at its lower end a connection with the tie ring and (2) having at its upper end a connection with the upper frame member;; F. hydraulic pressure rrleans normaily in communication with the upper chamber of every jack cylinder and prnvidig asource offluid at a substan- tial ly predetermined pressure, they hydraulic pressure means comprising (1) an accumulator, (2) a pump for charging the accumulator with hydraulic fluid, and (3) pressure responsive control means operatively associated'with said pump and said accumulatorfor directing fluid from said pump to said accumulator when fluid at the accumulator is at less than the predetermined pressure and for preventing charging ofthe accumulator when fluid thereat is at the predetermined pressure; and G. reliefvalve means adjacent to said cylinder of each jack, arranged to open when hydraulic fluid in the upper chamber of the jack has a pressure which exceeds the predetermined pressurebyapredeter- mined amountto allowtheflowoffluidfrom the upper chambertothe lowerchamberofthe jack.

5. A crusher according to Claim 4, further characte- risedby: H. aselectorvalvethroughwhich,whenthevalveis in a normal position, the upper chamber of each jack is incommunicationwiththe hydraulic pressure means and the lower chamber of each jack is in communicationwith a source of substantially unpressurised fluid, the selector valve having an alternatively selectable bowl lifting position in which the lower chamber of each jack is in communication with the hydraulic pressure means and the upper chamber of each jack is in communicationwith the source of substantially unpressurised fluid.

6. A gyratory crusher comprising a cone that gyrates in-an annular relatively stationary lower frame member and an annular upperframe member comprising a bowl that cooperates with the cone to define a crushing gap, the crusher being characterised by: A. cooperating abutment means on the upper and lowerframe members, the abutment means being engageableto supportthe upperframe member upon the lower frame member in a predetermined operative position from which the upperframe member can be raised; B. a plurality of double-acting hydraulic jacks at circumferentially spaced intervals around the lower frame member, each jack having (1) a cylinder with a substantially upright axis, (2) a piston slidable in said cylinder, and (3) a pair of pressure chambers in the cylinder, at opposite sides ofthe piston;; C. means connecting each of the jacks to act between the upper and lower frame members whereby hydraulic fluid under pressure in one ofthe chambers of the jack imposes a downward force upon the upper frame memberthattends to maintain it in its operative position; D. a selector valve having connections with both of the chambers of every jack and having alternatively selectable normal and bowl-raising conditions; E. a source of substantially unpressurised fluid which is connected with the selector valve for communication therethrough with the other chamber of every jack when the selector valve is in its normal position and foj communication with the one chamber of every jackwhen the selectorvalve is in its bowl-raising position;; F. hydraulic pressure means connected with the selectorvalve-forcommunication therethrough with one chamber-ofevery jack when the selector valve is in its.normal position and for communication with said other chamber of every jackwhen the selector valve is in itsbowl-raising position, the hydraulic pressure means comprising (1) an accumulator, (2) a pumpfordrawingfluidfromthesource and charginatheaccumulator, and (3) pressure responsive control means operatively associated with the pump and the accumulatorfor directing fluid from the pumpto the accumulator whenthefluid atthe accumulatoris at lessthan a predetermined pressure and for preventing charging of the accumulatorwhen fluid thereat is at substantiallythe predetermined pressure; and G. pressure reliefvalve means adjacent to each of the hydraulicjacks, the reliefvalve means being arrangedto open when pressureoffluidintheone chamber of an adjacent jack exceeds the predetermined pressure by a predetermined amount and which, when open, places the one chamber of the jack in communication with its other chamber.

7. A crusher according to Claim 6, wherein the piston of each jack has a downwardly projecting rod and whereinthe one chamber of each jackcylinder is the upper chamberthereof and further characterised by: (1) afirst substantially circular manifold surrounding said lowerframe member, to which the upper chambers ofthe jacks have respective circumferentially spaced connections, thefirst manifold being connected with the selector valve for normal communication therethrough with the hydraulic pressure means;; (2) asecondsubstantiallycircularmanifoldsur- roundingthelowerframemember,towhich manifold the lower chambers ofthe jacks have respective circumferentiallyspaced connections, the second manifold being connected with the selector valve for normal communication therethrough with the source of substantially unpressurised fluid; and (3) the pressure reliefvalve means comprising a plurality of relief valves, one for each two hydraulic jacks, each reliefvalve being connected with both of the manifolds nearthe connections thereto ofthe chambers of its two hydraulic jacks.

8. Acrusher according to Claim 6 or Claim 7, wherein the piston of each jack has a downwardly projecting rod and wherein the other chamber of each jack cylinder isthe lower chamberthereof and further characterised by: the source of substantially unpressurised fluid being substantially at the level of the lower chambers of the jack cylinders to provide for normal maintenance of substantially unpressurised fluid in those chambers.

9. Acrusheraccordingto anyoneofClaims6to8, furthercharacterised by: throttle means between the accumulator and the selectorvalve.

10. A gyratory crusher substantially as described with reference to the accompanying drawings.