US2630210A - Vibratory conveyer with deformable drive coupling - Google Patents

Description

March 3, 1953 R. M. CARIER, JR., ETAL '2,530,210

VIBRATQRY coNvEYER WITH DEFORMABLE muws couPLING Filed Feb. 28. 194e s sheets-sheet 1 March 3, 1953 R. M. CARRIER, JR., ErAx. 2,630,210

VIBRATORY coNvEyER wrm DEFORMABLE DRIVE: 'couPLING Filed Feb. 28. 1948 3 Sheets-Sheet 2 Il. IMIIHII I||| HHM ...hill Il.. fn 7mm March 3, 1953 R. M. CARRIER, JR., I'AL VIBATORY CONVEYER WITH DEFORMABLE DRIVE COUPLING Filed Feb. 28. 1948 3 Sheets-Sheet 3 Vlll Ilfig# 5 Patented Mar. 3, 1953 UNITED STATES PATENT OFFICE VIBRATORY CONVEYER WITH DEFORM- ABLE DRIVE COUPLING noteren/i. carrier, Jr., Auma, 1511., and Maurice G.' Whitley, Louisville, Ky.; ass'ignors, by mesne' assignments, to Carrier Conveyor Corporation, Louisville, Ky., a corporation of Kentucky Appii'ticn Fetay' 28, 1948, Serin N. 11,998

7 Claims'. 1

This invention relatesv to improved conveyor apparatus and to drive4 meansland morey par-V ticularly has to do with spring-'mounted conveyors, the drive mechanism of4 which is auto# matically synchronized with the' natural fre'-v quency of the spring mounting` to obtain motivation of the conveyor with minimum power con. sumption. The resonant' drive mechanism rof this invention is particularly advantageously ap# plied to a conveyor which moves material alongk the conveying surfacev duev to arecipiocating' andv oscillating movement, or asimilar movement, of the conveyor itself'l Heretofore, low' frequency' spring4v mountings have been provided forconveyor's to resiliently support the conveyors and to absorb vibrations during operation. However, dueto the'lfact that the natural frequencies ofthe springs' in these mountings were low compared' t'o the' `fr'ecuency of operation of theY conveyor, the conveyor drive means in efiect acted against the'vibrating action of the spring at Various times during the opera` tion.

This phenomenon can best be explained by" visualizing a large coil spring suspended ironi an overhead upright on a," support.rv If a piece' of material, for example, a100 pound blocklof steel, were secured on thev lower( endof the' coil, a per'm son could cause the 100'v poundblock to move: up and down over a limited rangey merelyby'p'us'hing down periodically' on the block' secured to' the spring. if thev pushes arenot sync'irronized"vvitlfiA the coiling and uncoiling of the spring, much power will be wasted when applied against the action of the spring. However, if' the pushesYA are synchronized with the natural vibrating frequency of the spring, pushes having only' a frac-V tion of the power of the unsynchronized pushes. will be suncient to keepv the *16,0v pound block" moving up and down with the coils;` t

ccording to the principles of our invention, a conveyor, such as a spring mounted spiral'o trough conveyor, moving 'material along the coi veying surface by"the"direotional'throwprin ple,j

is provided with a drive' mechanism tlatfoperates theconveyor at a` frequency *substallntially in resonance with the natu Y spring-mounting. It has'be nffoundthat by s'y'nf-f chronizing the operation ofthe'conveyor w hf the natural frequency 'off-the? spring" niofunti can be thereby.Y attained'.

quency of the spring mounting A further object; ofi this't inventionfistof pr'j4 vide a springe mountingeforf a*- spiiiat'conveyoif" which not f only. nesiliently siipports the conveyor' f reougenpyk or the c 2 butals'of acts to center it about an imaginary center axis.

Still another object of this invention is to provide a meth-0d of causing material to convey up a spiral or yon a trough using the principle of natural frequency.'

VA' particular feature of this invention resides in' the provision of a constant speed motor selected to' operate the' conveyor at the natural fre'- quency of thefspring mounting.

A further feature of this invention isthe provision of la spring mounting comprising spring arms' made of spring' stock .which are positively xed Atoi the periphery of the conveyor and to a baseY member for performing' the three-fold func.L` tion of acting as the centralbearing member for thev conveyor, supporting theV conveyor, and oscillating the conveyor about an imaginary verti; calaxis. n

Another and still further feature of this inventionistheprovision of a uid drive means which permitsthe conveyor to automatically adiust the length of thedrive arm so that the weight of the conveyor will rest on the spring mounting regardless of the loadl onv the conveyor.

y The novel features whichwejbelieve to be characterstic'uoi our invention areset forth in the appended claims.- OurY invention, however, bothV refererice*tov the following description, taken in connectionwith; tlieac'companying drawings, in

which: Y

Fgurel' 1 is a" fragmentary; front elevational viewof a spiral conveyor constructed according to the teachings' oiV kour invention;

Figure 2 isfaffragrnentary side elevational View, partly insectio'n, of the" spiral conveyor of Figure l;

Figure* 3i' is a horizbritai" sectional View taken substantially on line HIL-III of Figure 2; y

Figure- 4 is? a fragmentary vertical sectional View takenwon line IV--IV of Figure 2;

Fjigure is a fragmentary elevational view of afI To'lodied"v drive" kniec'h'an'i'sn applicable to theV conveyor of" FigureA 1i Figure 6K'is` ajirafgrnentary Velevational View of a modified' means for oscillating the conveyor ofv Figurev 1- 7 isah'fjrag'rn'entary' elevational view of af'inodie'd drive-means for the'conveyor oflFlgurevl;v

Figure V3" is a;V fragmentary' elevational View of* a nofel spring mounting for' the'conveyor of IFigure- ;V

Figure 9` isI awfragmentary vertical sectional vievvftakenfsubstanuauy on' liireiIX-'IX of Figureli Figure is a side elevational View of a trough 'conveyor constructed according to the principles of this invention;

Figure 11 is a horizontal sectional view taken on line XII-XII of Figure 6;

Figure 12 is a more or less diagrammatic showing of a modied drive mechanism applicable to the conveyor of Figure 8; and

Figure 13 is a view similar to Figure 12 showing a modified drive mechanism applicable to the conveyor of Figure 8.

As shown on the drawings:

The embodiment of the present invention disclosed in Figures 1 and 2 comprises a frame support structure IU in which a Ihelical conveying night II is supported for oscillation about a substantially vertical shaft I2 and for reciprocation in a vertical direction relative to the frame struc-v ture.

The conveyor is arranged to move material up the flight by using the directional throw principle of conveying. This method of conveying, when applied to a helical conveyor, requires that the helical ight be oscillated about its center laxis at the same time that it is being reciprocated in a vertical direction. Thus, each point on the conveyor night is first given a twisting, upwardly movement at a fixed angle to the angle of climb of the flight. If, for example, the angle of climb of the conveying flight is 10 with the horizontal, the flight may be twisted upwardly at an angle of, for example, 45 to the horizontal. Then, when the movement of the ight is reversed and it is twisted downwardly, the material on the flight will be thrown forwardly off the night at an angle approximately 35 thereto and will come to rest on an advanced part of the conveyor due to the fact that it has been thrown forwardly and also due to the fact that the flight has been moved backwardly while the material is out of contact with the surface of the flight.

The frame structure I0 comprises a base I5 supported in spaced relation to the door by foot members I6 disposed at each corner of the base. A pair of vertical angle members I and I8 are secured, as by welding, at each side of the base I5. These angle members are spaced from each other and carry between them a curved guide plate having a slanted guide slot 2|, the purpose of which will be explained hereinafter.

At their upper ends the angle members Il' and I8 are secured to a top plate 22 which includes a platform portion 23 extending outwardly from the frame structure. This 'platform 23 is braced by angle members 24 which are secured as by Welding near their opposite ends to the frame structure and by a diagonal brace 25 disposed between the frame and the platform 23. This platform serves to support a motor 26 that drives the conveyor through a belt 21.

Spaced downwardly from the top of plate 22 and secured to the four angle members of the frame structure is a second platform member 28 from the center of which depends a bearing member 29 in which the shaft I2 is journaled.

As best seen in Figure 2, the conveying ight comprises a series of separate units 30 secured together on the shaft I2 by means of a nut 32 disposed on an upper threaded portion 33 of the shaft I2. Each unit includes a portion of an upwardly winding trough 34 integrally formed on a length of tubing 35 equal to the pitch of the night.

The nut 32 bears downwardly on a circular closure plate 36 which is seated on a recessed ledge 38 on the upper end or the tube S5. Th lower end of each section of tubing has a downwardly projecting rim 39 which is adapted to seat on the recessed ledge at the upper end of the section of tubing therebelow. The unit at the bottom of the conveyor' differs from the other units in that, instead of a downwardly extending rim 39 at its lower end, this section has a recessed shoulder 40 against which a bottom closure plate liI abuts.

The shaft I2 has an enlarged lower end 43 providing la shoulder 44 which is drawn up against the bottom closure plate d! when the nut 32 is threaded downwardly on the shaft against the upper closure plate 36. Thus, the several units are rigidly held together for movement as a unit with the shaft I- It will be noted that a loading chute 45 is suitably secured, as by welding, to the bottom unit of the conveyor while a discharge chute 46 is similarly secured to the top unit of the conveyor.

The shaft I2 which is journaled at its lower end in a bearing Il] is resiliently mounted on a coil spring 48 and is free to oscillate relative to this night through the action of an anti-friction bearing 'assembly 49, which is freely disposed about the shaft I2 between the springr 68 and the bottom closure plate 4I As previously mentioned, the helical conveying ight I I must be given, simultaneously, a vertical reciprocating movement and an oscillating movement about its center axis. In this invention, the reciprocating movement is provided by a drive shaft 5I journaled in a pair of bearing blocks 52 on the top plate 22 and rotated through a pulley drive from the motor 26. Disposed on the drive shaft 5I directly above the vertical axis of the conveyor flight, is an eccentric 53 which has a connecting rod 54 disposed around the cam of the eccentric and associated at its lower end through a ball joint 55 with the upper end of the conveyor shaft I2. As the drive shaft 5I is rotated by the motor 26, the connecting rod will raise and lower the conveyor flight due to eccentricity of the mechanism.

It will of course, be understood that any other type of mechanism which provides a universal pivoting movement may be used in place of the ball joint 55.

The conveyor fiight is oscillated about its central axis by means of a pair of rollers 58 disposed on opposite sides of the conveyor. Each roller 1s rotatably secured on an axle 59 which is rigidly fixed to the wall of the trough 34. The roller 58 1s disposed in the slanted guide slot 2l of one of the curved plate 25 which are held between the structural angle members I l and IS on either side of the conveyor.

It will be readily seen therefore that, as the eccentric mechanism reciprocates the conveyorflight in a vertical direction, the slanted guide slot 2| will, through the rollers 58, cause the iiight to oscillate about its center axis. The angu-v larity of the slot determines the degree of oscillation since the conveyor night is displaced a constant distance vertically for each rotation of the eccentric.

The angularity of the slot will also control the angle in which the material leaves the surface of the conveyor flight. Referring to Figure 1 it 1s clearly seen that the path of travel of lthe roller 58 in the slot 2I is, in this illustration, at approximately 45 to the horizontal, while the angle of climb of the conveyor flight is approximately 8. Thus, the material will leave the suraecaeio 5. face of the flight at an angle of approximately 37 to the surface of the flight.

As many rollers B and guide slots 2| may be used as is dictated by the height of the conveyor assembly.

In cases where a heavy material is being conveyed in the conveyor of Figure 1 and considerable amounts of power is being exerted by the eccentric drive means, vibrations will be set up in the support structure. In such a case it may be, desirable to provide for counterbalancing the vertical movement of they spiral flight in order that the vibrations will not become excessive. In Figure 5, one means of counterbalancing this installation is shown.

In this modification a. weight 62 is adjustably mounted on a shaft 65,3 which is driven from an. eccentric 99 keyed to the drive shaft 5|. The bearing block 52 may be extended upwardly to provide astandard for pivotally supporting a lever 65 attached pivotally to the rod on which the weight t2 is mounted. The pair of eccentrics on the drive shaft are oppositely disposed so that when, the conveyor is moved downwardly the weight 52 is moved upwardly. Thus vibrations` and shocks are counteracted and not transmitted to the frame structure. It is to be understood that the weight E52y must equal the weight of the conveyor or the throw of the eccentric 64 must be made several times as great as that of the eccentric. 5,3.

It will, of course, be obvious that the spring 4S may beA eliminated from the conveyor of Figure 1. In this case the weightl of the entire conveyor flight will rest on the thrust bearing 4l. The principle of operation will, however, remain the same.`

Rotation of the conveyor flight about its center axis may be obtained by means other than the roller 58 and slot 2| previously mentioned. iny Figure 6 a second mechanism for rotating the conveyor flight is illustrated.

The spiral flight 68. of this modification may be constructed of several individual' units as in the spiral of Figure 1. Theflight may conveniently be held between a platform 69 and the topclosure plate by means of the nut 32 threaded on the shaft l2, which in this case has a. lower shoulder 'l0 disposed under the platform 59. By clamping the several units of the spiral e flight between the nut 32 and' the shoulder 15, the spiral will be suitably held against the bottom platform 69 to assure oscillation of the flight with the platform 59.

To impart a vertical reciprocating movement to the conveyor, there is provided a drive shaft 12 journaled in bearings '|3 and 11| secured in an upright position on a circular platform 15.

This platform 'f5 is connected to the platform 69' in substantially parallel spaced relation by four angle members Ti which maybe welded atY either end to the platforms.

A stub shaft 'i9 isV welded at its. upper end; in an opening in the platform l5 directly below and in alignment with the shaft l2 and projects downwardly into a bearing assembly 8| secured to a suitable base member 82 by the bolts 33. A plate 85' having a central opening through which the shaft 19 passes is held spaced above the base 82 by a plurality of bolts 86 and spacer sleeves 81.

A coil spring S8 is disposed about the shaft 'i9 with its lower end resting freely on the plate S5 and its upper end abutting a disk 99. This disk is separated from the platform 15 by an anti*- friction bearing assembly 9|'. With this arrange--v ment the platform 'l5 is free to oscillateabout the shaft '|9 with-out causing rotation of the spring 88.

Near the center of the shaft. '|2, a pulley 93 is keyed thereto, the pulley being connected through a belt 94 to a suitable source 0I" power, such as the motor 26, Figure 1. A weight is secured near either end of the shaft 'l2 at points equidistant from the pulley 93. As the pulley is rotated by the external drive means, the weights 95 will cause reaction forces to be set up in the structure tending to move the structure sidewise and up and down in a vertical direction. Since the shafts |2 and 19 are journaled in upper and lower bearings, the conveyorl will be unable to move sidewise and only a vertical reciprocating movement of the spiral flight will result.

To impart. oscillating movement to the embodiment of this invention disclosed in Figure 6, there is provided a pair of arms 9'! and 9S which are pivotally mounted at their lower ends in bearing blocks 99 secured to the base 82. At the upper end, the arms 91 and 98 are pivotally connected to ears |09 depending in diametrically opposed positions from the lower surface of theplatform 15. It will immediately be recognized that, as the spiral flight 68 is reciprocated in a Vertical direction by the action of the weights 95, the up and downward swinging movement of the arms 97 and 9Bv will cause the platform 'f5 and consequently the spiral flight 63 to oscillate about the shafts I2 and 19.

The angle at which the material carried on the surface of the spiral flight is thrown upwardly will depend upon the position and length of the arms 91 and 98, since the material will be thrown in a direction substantiallyv tangential to the arc described by the outer end of the arms.

As the platform 69 oscillates, the upper ends of the arms 9'| and 98, which are fastened thereto, will of course tend to oscillate with the point of the platform tol which they are attached. Since the arms 91 and 93 are rigid, means must be provided to allow them to pivot in their mountings. To accomplish this we have provided a rubber mounting for the upper and lower end of these arms. As. seen in Figure 1l, a rubber sleeve |02 is molded between an inner sleeve |93 and an outer sleeve |04'. The inner sleeve |93 is held rigid betweenv the bearing blocks 99 by a bolt, |05. which passes therethrough. The outer sleeve |94` is pressed into the hub of the arm 9T. Thus, since the sleeves |93 and |94 are held in fixed position, pivoting of the arm in the mounting will be accomplished by flexing of the rubber sleeve |02'.

For the purpose of varying the frequency of the spring mounting, a plurality of coil springs |95 may be secured, as by eyelets Hita between the platform l5 and the base plate 85. Since these springs are secured, spaced from the axis of the conveyor they will also have a stabilizing effect.

The upper end of the arm also; hasl a rubber sleeve held between inner and outer sleeve to permit pivoting of the arm at this point.

As shown in Figure 6, the arms 91 and' 9i? extend upwardly through an opening |9| provided at one side of' the plate 85.

There is thus illustratedV in Figure 6 a spiral conveyor mounted on coil springs and arranged to be simultaneously' reciprocated in a. vertical direction and oscillated aboutits center axis.

If the coil springs are eliminated from this assembly the weight: of'. the. conveyor will' rest 7 solely on the bearing 8|. However, the conveyor will be operated in the same manner as above described.

In order that the slow frequency spring 48 of Figure 1 be used to support as much of the weight of the conveyor as possible it may be desirable to incorporate in the conveyor drive mechanism means for allowing the conveyor to sink or assume a floating position on the spring mounting in accordance with variations in the Weight of the loaded or unloaded conveyor.

In Figure '7 such a mechanism is illustrated. It comprises a cylinder H mounted on a shaft H2 around which the conveyor flight is assembled. A piston H3 is secured to the lower end of the drive shaft I2, which is disposed for reciprocating in a fluid tight seal H4 in the cylinder H0. The cylinder H0 is filled with a fluid, preferably a liquid such as oil, on both sides of the piston H3. A bypass port I|5 in the piston H3 affords communication between both sides of the piston.

Since the cylinder H0 is connected directly to the spring-mounted flight 68, the flight will be allowed to sink on the spring mounting until substantially the entire static load of the conveyor is carried thereby. When the shaft I2 is reciprocated by the drive means the fluid drive mechanism will act as a rigid link for reciprocating the conveyor. Thus, the spring mounting will automatically adjust its position for changes in the total weight of the conveyor due to loading or unloading.

In the arrangement shown in Figure rI, a modied spring mounting and centering member is illustrated. This member comprises a leaf spring Il which is welded as at |08, to the frame member 'I and has a bearing |09 secured to one end for receiving the shaft H2 which passes freely therethrough. Collars I are keyed to the shaft I|2 above and below the bearing. Thus, the shaft is free to rotate relative to the shaft but must vibrate vertically with the bearing and the leaf spring.

The fluid cylinder H0 is adapted for use with the conveyor of Figure 1, with either the roller and slot rotating mechanism or with the swinging arms of Figure 6.

Figures 8 and 9 illustrate a third form of means for causing rotative movement of the conveyor. This mechanism comprises a plurality of individual spiral units clamped between an upper disk 36, Figure 2, and a platform H6 by the nut 32 threaded on the upper end of the rod I2. This rod passes through a central aperture in the disk 36 and, at its lower end, through a central aperture in the closed end Hl of a sleeve H8, Figure 9. A nut H3 threaded on the lower end of the rod I2 coacts with the nut 32 to clamp the units together. The sleeve H8, at its lower end, is secured as by welding to the platform IIE and has an opening near its upper end through which the nut I I9 may be adjusted.

Thus, the tighter the nut H9 is drawn on the rod |2, the tighter the sleeve will be pressed against the platform HB.

Vertical reciprocation of this structure is obtained through a lever |23 which is pivoted in a fulcrum |24 and arranged, at one end, to be moved up and down by an eccentric mechanism driven from a drive means |25, such as the electric motor 2E of Figure 1. At its other end the lever |23 is pivotally connected to a push rod |26 which extends upwardly inside the sleeve I |8 for connection at its upper end to a piston |21 slidably mounted in a cylinder |28. Fluid tight packing is disposed around the rod |26 where it enters the cylinder |28. The cylinder |28 is sup-V ported by a rod |30 and a ball joint |3| from a disk |32 which is welded across the inside of the sleeve H8. The up and down movement of the outer end of the lever |23 is transmitted to the sleeve H8 and therefore to the spiral flight through the fluid cylinder |28.

In Figure 9 it will be seen that a restricted passage |33 is drilled through the piston |2`| establishing communication between the iluid on either side of the piston. Thus, the fluid cylinder |28 will act in the same manner as the cylinder I l0 of Figure 7 to permit the conveyor to float on the spring mounting.

In this form there is provided a plurality 01 arms |34 which may suitably be made from rods of spring steel. These rods may have various cross-sections but are preferably of round crosssection. In all forms the mass of the rod is uniformly distributed on all sides of a central axis so that the rod has the characteristic of being able to flex universally and uniformly in any direction from the axis. Each arm |34 is adjustably held at its lower end in a block |35 by means of a set screw |35. The block |35 is secured by bolts |38 and |39 to a suitable base |40, the bolt |39 being disposed in a horizontal arcuate slot (not shown) in the base flange portion of the block for permitting the block to be adjusted by pivoting about the bolt |38 as center. Near its upper end, each rod passes through a segmental circular cutout portion |44, Figure 8, in the platform H5. A block |45 is adjustably secured to each arm by set screws |46 and has a slanted brace |41 pvota-lly secured by a capscrew |48, Figure 8, to the platform |6.

Thus, each rod is mounted so that its effective length can be increased or decreased to regulate the frequency of the spring arms |34. The pivotal mounting of the block |35 and I 45 permits this adjustment without deformation of the spring arms |34.

As the spiral flight is reciprocated in a vertical direction, the spring arms |34 will oscillate the flight in the same manner as the arms 91 and 98 of Figure 6 or the slot 2| of Figure 1.

Sets of spring arms |34 can of course be connected to the conveyor flight at various elevations by mounting them on a support platform built around the conveyor at an appropriate height. The platform on which the blocks |45 are mounted could be readily secured to a cylindrical sleeve fastened to the periphery of the flight.

It is evident that as many sets of spring arms may be used on a spiral conveyor as is necessary to keep the conveyor centered at all times.

From the above description it will be readily seen that the several spring arms act to center the spiral flight about an imaginary central axis. Thus, no center bearings are needed with this construction.

.It is within the scope of this invention to provide a conveyor having a set of spring arms |34 as the lower center bearing and having a typical center bearing, such as bearing 29 of Figure 1, as the upper center bearing. Or, the spring arms may. replace both the upper and lower center bearings, using one or more sets of spring arms depending upon the height of the conveyor.

Although in the illustrations of this application we have shown five spring arms mounted equi-distantly about the conveyor, it is within the scope of this invention to use any number oi spring arms for the purpose of centering the con- -9 veyor, resliently mounting the conveyor and imparting oscillating movement thereto.

The spring mountings and drive means of this invention are also applicable to a trough conveyor. In Figure lo a trough |59 is mounted substantially horizontally on spring rods which are adiustably secured in blocks |52 and |53 on both sides of the trough. A motor |54 operates an eccentric 55 to reciprocate the trough in a substantially horizontal direction through a piston |55 slidably mounted in a fluid cylinder 51. A passage |59 establishes communication between both sides of the piston. The cylinder is secured through a balljoint |58- to the conveyor. Horizontal reciprocation of the conveyor will result in the movement of the conveyor at an angle upwardly to the left as seen in Figure l0 for discharge through a chute |69 secured in an opening in the bottom of the conveyor.

The trough conveyor illustrated in Figure 10 is adapted to move material along its surface from right to left accordingto the directional throw method of conveying. The angle at which the material leaves the surface of the conveyor will depend upon' the location of the arms and their iength.

It will be understood that the uid cylinder 25"! permits the trough conveyor t0 float on the spring rods |5| in the manner described in connection with the cylinder lill of Figure 7. This type of floating drive may of course be replaced hy a single, rigid drive shaft, in cases Where it is not desired to take full advantage of the spring mounting.

Further, the spring arms 5| may be advantageously replaced by one or more leaf springs secured between the supporting base and the 'central section of the bottom panel of the trough.

Reciprocation of the trough may of course be effected by means of rotating weights secured to the trough and operating in substantially the same manner as the weights 95 of Figure 6. In this case, the Weights would be arranged to augment each other in a horizontal direction to cause reeiprocation of the trough but to counterbalance each other in a vertical direction. Thus", the Weights would have to be rotated in opposite direction by any of the well known mechanical arrangements, such as bygears.

Heretofore this disclosure has been concerned with conveyors mounted on slow frequency springs. As previously stated an important fea-- ture of this invention is the provision of means for operating' the conveyor Within the natural frequency range of the spring mounting.

The natural frequency of a spring mounting load mounted directlyf on the springs without externaily connected dampening mem- '.bers be computed from the equation Af: d

uals the frequency in R. P. M. and d deflection under the load in a vertical nection with Figures 1', 6', 8 and 10 maybe adapted for operation for conveying at the natural frequency of the spring. However, in all cases the conveyor must be permitted to settle to its normal floating position even While load is increased or decreased. Thus, a fluid cylinder such as cylinder llo of Figure 7 must be incorporated in the drive mechanism. Or the loaded conveyor must be permitted to settle on the springs before a suitably adjusted drive arm is connected thereto.

While the natural frequency of a spring mounting may be calculated from the abovementioned formula, it must be remembered that the rela-tion of the drive mechanism and the conveyor is such that they will operate in resonance in a range which extends approximately 5% above and below the calculated Value. Thus, if the calculated or mean value of the natural frequency is 285 vibrations per minute, the range of resonance will extend approximately from 27() to 300 vibrations per minute.

Therefore, it is to be understood that hereinafter when the natural frequency range of a spring mounting is referred to, it means the range in which the drive means and the conveyor are Rate of conveying material in the conveyor depends upon the speed and the amplitude of the conveyor vibrations. If a liquid, such as oil, is used in the drive cylinder lill, the speed of natural frequency of the spring mounting must be predetermined to be within the range of speed that Will give the desired conveying rate. The

amplitude of the vibration will, of course, depend upon the throw of the eccentric. Thus, for each installation using liquid in the cylinder I 0, a denite speed and amplitude is predetermined to give the necessary discharge.

The rate of conveying may be varied in any frequency range by manually -adjusting the amplitude of the conveying stroke. In Figure 12 a hydraulic driveV mechanism is illustrated connected between the eccentric drive means |25 and the push rod |25.

This hydraulic drive comprises a pair of fluid cylinders i1@ and l1! mounted on a support |12. The cylinder I lil has a piston |13 mounted for reciproca-tion therein and connected to a drive arm H5 leading from the eccentric |25. The cylinder 11| has a piston |11 connected to the rod i2@ leading to the fluid cylinder |28. The space above the piston in cylinder |16 is connected through a flexible tube |19 to the space above the piston in cylinder i'l. Likewise, the spa-ces below the piston areinterconnected by a iiexible tube |83. This fluid system is designed to run full andconsequently reciprocating movement of the piston |13 causes reciprocating movement of the piston |11 and therefore movement of the conveyor. A bypass line |82, having a hand operated valve M33, is connected between the tubes |19 and |86. The amount of the valve |83 is opened will of course determine the length of stroke of the rod |26.

Thus, the conveyingrate may be varied with the drive means operating at constant speed. ln Figure 13 a modification of the drive means of Figure l2 is disclosed. In this modification, the piston |11 is secured to a rod |85 fastened to a support member |86. The cylinder |1| is secured to the base H6 of the conveyor. Thus, the piston l1? is held stationary while the cylinder il! and the conveyor is moved.

This modification permits the conveyor to be mounted close to the ground.

A control bypass valve, such as valve |83, may. of course be installed in the apparatus of Figure 13.

A second method of obtaining a variation in the speed of conveying is by use of a drive cylinder, such as the cylinder H0, using air as the driving fluid. Referring to Figures 8 and 9, with a predetermined length of stroke of the rod |26 and using air in the cylinder |28, the rate of conveying of material can be varied by varying the speed at which the rod |26 is reciprocated, which variation may be made by any manually operated speed changer connected to the drive shaft of the motor. As the reciprocated speed of the rod is increased, the effective stroke of the conveyor will be raised so that the stroke of the conveyor will be greater than the stroke of the rod |26. This increase of stroke results in an increase in amplitude and consequently an increase in conveying speed.

If the speed is decreased, the stroke of the conveyor will be de-creased to a point where it is less than the stro"e of the rod |26. This vari-ation of the effective length of the conveyor stroke in spite of the fixed stroke of the rod |26 is a result of the inherent characteristics of the air cylinder .and results in controlling the conveying speed with a. fixed stroke by varying the reciprocations.

Thus, by the use of an air cylinder the rate of conveying may be varied from a trickle of materia-l to a rapid rate.

In summation, there is disclosed in this invention, a spiral conveyor and a trough conveyor and various means for operating each conveyor without spring support, with slow frequency spring mounting and with a natural frequency spring mounting.

There is further disclosed means for permitting the conveyor to settle or float on the spring mounting with changes in load conditions.

The conveyor apparatus herein disclosed, and especially the natural frequency conveyors, have many advantages both as to economical construction and efficient operation heretofore unknown in the conveyor field.

We have heretofore described various modifications of our invention, but it will be understood that numerous other variations may be made in the character, construction and arrangement of the component parts and in the general assembly,

without departing from the principles and scope of the invention. It is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

We claim as our invention:

1. In a mechanism of the character described, the combination of a vibratory material handling structure, resilient means supporting said structure and which permit said structure to settle under load, means extending between said structure and a base with respect to which said structure vibrates, said last named means comprising a vibrator and a coupling, through which the vibrations from said vibrator are transmitted to said structure, which coupling is deformable to compensate for changes in the distance between said structure and said base, as the former settles under load, said coupling being thus deformable at a rate of movement which is substantially less than the rate of movement imparted to said structure by said vibrator at the normally used frequency and amplitude thereof.

2. The mechanism according to claim 1 characterized further in that said coupling, when deformed, retains no strain as a result of being thus deformed.

3. The mechanism according to claim 1 characterized further in that said coupling comprises relatively movable members forming a chamber containing substantially incompressible liquid. and bleed means permitting discharge of liquid from such chamber for enabling settling of said structure, but at a reduced rate as aforesaid so that substantially positive driving of said structure is effected through said members and the liquid-containing chamber dened thereby.

4. The mechanism according to claim l characterized further in that said coupling comprises a double-acting piston-cylinder assembly defining a pair of chambers containing substantially incompressible liquid and having restricted communication with each other at a rate such that substantially positive driving of said structure by said vibrator is effected through said couplingr while such restricted communication between said chambers enables a settling of said structure under load at the reduced rate aforesaid.

5. The mechanism according to claim 1 characterized further in that said coupling comprises a piston-cylinder type hydraulic shock absorber in which bleed means between bodies of substantially incompressible liquid therein permits settling of said structure but prevents perceptible relative piston-cylinder movement at the frequency of vibration of said structure by said vibrator.

6. The mechanism according to claim 1 characterized further in that said vibrator is fixedly mounted, and that said coupling is connected between said vibrator and said structure.

7. The mechanism according to claim 1 characterized further in that said coupling comprises a double-acting piston-cylinder assembly deiining a pair of chambers containing substantially incompressible liquid and having restricted communication with each other at a rate such that substantially positive driving of said structure by said vibrator is effected through said coupling while such restricted communication; between said chambers enables settling of said structure under load at the reduced rate aforesaid, and a bypass valve between such chambers whereby, upon opening of said valve, said members, and thus said vibrator and structure, may vibrate independently of one another as during starting and stopping thereof.

ROBERT M, CARRIER, JR. MAURICE G. WHITLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 786,337 Zimmer Apr. 4, 1985 1,146,947 Norton July 20, 1915 1,160,427 Marcus Nov. 16, 1915 1,204,522 Wall Nov. 14, 1916 2,374,664 Carrier May 1, 1945 2,464,216 Devol Mar. 15, 1949 FOREIGN PATENTS Number Country Date 580,558 Germany Mar. 31, 1931

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