US2094237A - Apparatus for aggregate coating - Google Patents

Description

Sept. 28, 1937. w. M. HENDRICK ETAL 2,094,237

APPARATUS FOR AGGREGATE COATING Filed July 27, 1955 3. Sheets-sheet 1" i r) .M Ml- Mew /m NCa T uw WG Sept 28, 1937. w. M. HENDRICK ET AL 2,094,237

` APPARATUS FR AGGREGATE COATINGl Filed July 2'?, 1955 5 Sheets-Sheet 2 www Y, Twf M NHeo. E./ 0 www 4. wamv sept'. 2s, 1937.

w. M. HENDRICK 5T APPARATUS FOR AGGREGATE COATING Filed July 27, 1935 3 Sheets-Sheet 3 HAF ANGULAE. POSITION Patented Sept. 28, 1937 UNi'i'ED STATES attain PATEN'i1 itiil'lrl Wallace M. Hendrick, Great Neck, and Gustave Loefller, Jr., Flushing, N. Y.

Application July 27, 1935, Serial No. 33,474

20 Claims.

This invention relates to the coating of aggregate with other material, and more particularly to an improved machine therefor. Without intending any limitation thereby we may mention,

as typical aggregates to be coated, crushed stone, gravel, slag, or the like; and, as typical material for coating the same, bitumen-for example in emulsion or cut-back form. It will be obvious, however, that our invention may be found useful in a wide sphere of coating and/or mixing operations, and the above examples are not to be construed in a limitative sense.

An object of our invention is to provide an improved methcd and apparatus for coating aggregate with other material.

One form of machine to which we have very advantageously applied c-ur invention is an upwardly inclined screw conveyor, in the lower portion of which is maintained a bath of aggregate coating material, the aggregate being immersed in this bath and moved thereout by the screw for -drainage of excess coating material in the upper portion of its travel within the conveyor. These machines, when the drainage therein is reasonably unimpeded, form a highly satisfactory means for imparting a uniform coating to aggregate. In such machines, for various purposes including the facilitation of the draining action, the prevention of jamming of large aggregate pieces, etc-. it is customary to provide some space between the bottom of the trough and the rotary path of the screw periphery. We have found, however, that the mere provision of this space does not necessarily result in proper drainage, as there is a strong tendency for aggregate iines i. e., smaller pieces of aggregate to seggregate and collect rapidly in this space and thereupon to form a substantially inert mass which in turn blocks the free drainage of the moving aggregate.

An important object of our invention is to maintain the aggregate drainage unimpecle-d. An allied object is the provision of a machine of the character described wherein the aggregate drainage remains unimpeded.

In machines of the character described the bath of coating material or the like may be maintined at a predetermined depth by introducing the material in a iiow at least suflicient to balance the consumption, and carrying off for reintroduction such material as rises above the predeternined depth. Unless special precautions are observed, the carried-off material may be contaminated by incidental dirt, liquids, or the like which may be present on the surface of the aggregate as it is introduced into the bath. It is an object of our invention to provide a machine in which the excess coating material or the like may be maintained in a substantially uncontaminated condition. v

The prevention of collection of inert aggregate between trough and blade periphery is not limited in its application to inclined screw conveyors. Accordingly it is a general object of our invention to provide a coating machine with a rotatable blade or blades wherein collection of inert aggregate between the trough and the path of the blade periphery is-prevented. It is an allied object to prevent this collection without danger of jamming of larger aggregate pieces between the blade periphery and the trough.

VAnother general object is the provision of a self-cleaning coating machine. An allied object is the provision of a` machine in which various portions of the trough are periodically and alternately cleaned.

Other and allied objects will more fully appear from the following description and the appended claims.

In the description reference is had to the accompanying drawings, of which:

Figure 1 is a view, principally in side elevation but partially in vertical section, of a coating machine according to our invention;

Figure 2 is a plan View of the same machine, looking from the left-hand side of the vertical sheet on which Figure l is illustrated;

Figures 3, 4, and 5 are cross-sectional views respectively taken along the lines 3 3, 4 4, and 5 5 of Figure 2; excepting that while Figures l and 4 illustrate the trough in its downmost position, Figures 3 and 5 each illustrate the trough very near its toprnost position;

Figure 6 is a detail illustration of the baffle 3l of earlier figures; and

Figure '7` is a curve illustrating the synchronization of the relative trough-blade movement, hereinafter described, with screw rotation.

Reference is rst invited to Figures 1 and 2 for a general description of our machine. Herein I represents a main casing, open at the top, of U- shaped cross-section, and having the U-shaped end- members 2 and 2". These end-members are respectively provided with the angled brackets 3 and 3, which are secured to the extremities of a rectangular frame composed of side channel-pieces 5 and end cross-members li and 4". This frame, which is parallel with the casing l, may be permitted at the one end (i. e., that associated with the casing end-member 2) to rest upon the ground or other level object; the opposite end of the frame is raised above that level as by means of the bracketed leg system 6, to result in an inclined position for the casing I. A shaft system 'l is supported longitudinally within the casing I. The upper shaft portion l of this system extends outwardly through the upper end-member 2', being journalled therein in a bearing 8 which is arranged to resist thrust in the direction of end-member 2". The shaft system 'I further includes, solidly fastened together with the upper shaft portion l', the shaft 1 of the screw I0, hereinafter described, and the lower shaft portion 1". The latter is journalled in a bearing 9, which is hung by means of a hanger 9 from a cross-member 9 secured between the sides of the casing at their tops. The shaft system 'I is driven, as through bevelled gear system 5l) (Figure 2), from any suitable source of power (not shown).

On the screw shaft 1', and extending for its full length, is formed the screw l0, for example having the continuous single helicoid blade IB; no limitation to any particular form of blade or blades is, however, intended. The peripheral diameter of the blade is made slightly less than the width of the trough I I, next described. As illustrated in Figure l, the spacing between the bottom of the trough and the blade periphery is appreciable; this, however, will be later referred to.

It will be understood that for convenience, in view of the inclined conveyor position, the terms upper and lower are in general used herein to denote respectively right and left-hand dispositions of components as they appear in Figure 1, while the terms top and bottom are used to denote respectively upward and downward dispositions of components as they appear in that gure.

The trough II of the conveyor is of U-shaped cross-section, open at the top, and is provided with U-shaped end-members I2 and I2. The trough is of smaller dimensions than the main casing, and is suspended, in manner hereinafter described, within that casing; its longitudinal position within the casing is such that the lower trough end-member l2 is disposed slightly below the lower shaft extremity and bearing 9, while the upper trough end-member I2 is disposed slightly above the upper extremity of the screw l0. Accordingly the upper shaft portion 'l' passes through the upper trough end-member i2', which latter is therefore provided with a central slot lZa extending downwardly from the top of the end-member to below the shaft. The trough is further provided, slightly below the lower extremity of the screw lll, with a transverse partition I3 similar to the trough end-members. Accordingly the lower shaft portion I passes through the partition I3, which latter is therefore provided with a central slot Ita similar to the slot E20! in the end-member I2. The central slots lZa and I3a in end-member I2' and partition I3 are extended toward the trough bottom sufficiently to permit the ris-e of the trough to a higher position than illustrated in Figure 1, and (in the case of slot Ia) to assure good communication for liquid between the trough section Il above the partition i3 and the trough section I I below the partition I3 (screw and reservoir sections, respectively).

Into the reservoir section ll, as by a pipe I4, is introduced the coating material, After this has risen to the level of the bottom of slot i3d it will flow over into the screw section I I', forming a bath of the material. The level to which the bath will rise may be adjusted by connecting a exible overflow hose or like device i5 selectively to the appropriate one of a plurality of holes I6 in the lower trough end member I2, the unused holes i6 being closed by respective plugs IE. A typical level has been indicated in Figure l by the dash-dot line il. The aggregate is introduced, as by the chute 58, into the lower extremity of the screw section il of the trough, and hence into the bath, its surface thus becoming thoroughly coated, or super-saturated, with the coating material. By the screw EE] the aggregate is moved out of the bath and upwardly within the trough, draining its excess coating meanwhile, and finally discharging through the outlet I9. This outlet is secured to the trough I l and passes through an oversize aperture l in main casing I.

We have thus far referred to the trough as simply suspended in position. Attention may now be directed to the manner in which this suspension is effected, reference conveniently being had to Figure 4 as well as to Figures l and 2. From side to side at the top of the main casing I are provided a plurality of cross-members 2G, each carrying a central standard 2l. In these standards is journalled a cam-shaft 22, parallel with the main shaft system TI. On the cam-shaft 22, at a plurality of points above the trough Ii, are provided a like plurality of similar flat cams 26, disposed transversely of the shaft. Passing over the upper peripheries of each of these cams is a chain 2'?, both extremities of which are secured to studs 2l in a respective cross-member 28, which is in turn secured from side to side at the top of trough l l in the plane of the respective cam. (In Figure 2 one of the chains 2l has been omitted for the better illustration of the associated cam 25.) The chains retain the trough as to downward movement transverse of the shaft; the trough is retained as to downward longitudinal movement by a plurality of brackets 29 secured to the inside of the casing l near its lower extremity, each carrying a button 2t against which the trough end-member l2 bears.

Before describing in detail the cams or the manner of their movement we call attention to the fact that the suspension of the trough il thus far described holds the trough loosely or yieldably rather than rigidly with respect to the screw IG. That is to say, the trough is capable of small transverse or side-to-side movements, and of small longitudinal movements away from the retaining brackets 2Q. This feature in itself we have found helpful in minimizing tendencies toward aggregate jamming and the like.

As illustrated in Figure l the spacing of the bottom of the trough from the blade periphery is intended to be approximately the maximum which might be desired in normal operation of a conventional conveyor; thus for a representative range of aggregate sizes it might be of the order of two inches. In the preferred carrying out of our invention we continuously vary this spacing in an oscillatory manneri. e., from such a maximum to a minimum (which may for example be of the order of one-half inch), back to the maximum, and so on. While this may of course be done in any way which oscillatorily varies the spacing between the trough bottom and the main shaft, we have found it most desirable to raise and lower the trough oscillatorily. Accordingly we shape the cams 26 as eccentrics, align them lOl with each other, and drive the cam-shafty 22'from the main shaft system 1. Such a drive has been illustrated as carried'out` by the chain v23 passing over sprockets 24 and 25 oncam-shaft 22` and main shaft portion 1', respectively. One of the cams-26 is bestseen in ligurefl,` which clearly illustrates its eccentric formation. Thus the peripheral point A, which Aas illustrated is upwardly disposed andhencein the approximate center of the peripheral portion against which the chain rests, has the` minimum radial separation from the center of the cam-shaft 22; accordingly with the cam-shaft 22 and cams in the angular position illustrated in Figure 4 the trough I I is in its downmost (or Figure 1), position, and the blade-trough separation a maximum. In Figure Ilithe direction of rotation of the cam is indicated bythe arrow, and the peripheral point of maximum radialseparation from the cam shaft center as B. Obviously when the cam is vrotated so that the lpoint B is upmost, the trough Il will be in `its upmost position (near which it has Abeen illustrated in Figure 5) and the blade-trough separation is a minimum; It will be understood, of

: course, that-by virtue ofthe illustrated and described trough suspension the trough raising and lowering occurs in a direction at right angles to the `main shaft system 'I and cam-shaft 22.

We may employ for cams 2S any'eccentric shaping within wide limits. We have found, however, that it is very advantageous sof-to arrange the oscillatory trough movement that the trough rise (or'reduction of blade-trough separation) is relatively slow,l and the trough drop i (or increase of separation) is relatively rapid.

The slow reduction of separation minimizes danger of` jamming oflarger aggregate pieces be; tween blade and trough, the rapid-increase of separation facilities quick and free-drainage, and the combined action-has proven otherwisev helpful and desirable. This actionI is very'conveniently provided by properly shaping the camsv 26 as we have illustrated in-Figure-fl; Herein the peripheral cam portion' between points A' and B which is active inftrough raising is indicated as X, while the peripheralvportionbetween points B and A which is active in trough lowering isiindicated as Y. As illustrated the peripheralportion Xfsubtends about the center-ofthe camshaft an angle of about 210 degrees, and the peripheral portion Y therefore an angle of only, approximately 150 degrees. The relative trough raising and trough lowering times are respectively proportional to these subtended angles, the rotational speed of the cam-shaft being constant, and for the particular cam illustratedare therefore approximately in a 3:2 ratio one to the other. Obviously other and higher ratio-s may be established by suitable variation of the cam shape.

The trough is of course suspended from the momentarily top peripheral portions ofthe cams, which portions upon cam-shaft rotationrise and fall periodically with respect" to thescrew. Obviously We may employ for suspension of the trough any devices characterized by the periodic rise and fall; we have preferred the cams, however,.because of the ease with whichrelative rise` and fall rates may be diiferentiated'as just described;

The oscillatory spacing variation is arranged as a recurrent function responsive, and hence having a predetermined relationship, to the rotation of the main shaft and screw il); this relationship of course results from the driving of the camshaft" 22y from the mainshaft system l. By this screw rotationa g., to drive the cam-shaft 22' atia fraction of the speed of the main shaft system lThis gives sufcientftime for significant drainage while the spacing remains high,l and insures that the cleaning action occurring each time the spacing becomes small will extend in substantially full effect for an appreciable timefor example long enough for the screw to advance in an axial direction for at least a major fraction of its pitch (or separation between successive portions` similarly disposed angularly about the shaft). Another of these characteristics is the establishment of this multiple as a non-integral one-for example as half of an oddnumbered integral relationship. This hasithe ei'- fect of staggering the longitudinal sections of the trough bottom best cleaned by the screw blades on successive approaches of the trough to the blade.

While we intend no limitation thereto, we have successfully employed, as a speed ratio between the cam-shaft and the main shaft system, a ratio of 1:31/2-1. e., We have driven the cam-shaft 22 at 2/7 of the speed of the main shaft system, choosing the gears 24 and 25 to that end. This results in a relationship of spacing variation period to screw rotation period which has been graphically illustrated in Figure 7. The abscissae of this curve represent degrees in a cycle of rotation of the main shaft system, while the ordinates represent the level of the trough (a high ordinate showing a small blade-trough spacing, and viceversa); the origin atf point |02) represents a condition of lowest trough position. From the point |80 may be traced the actually continuous curve made up of the seven successive half'cycle portions lilla, Illlb, IUZa, |025, I03ct, |03b, |0441. The termination of the curve Ila, at point`200, is seen to represent a recurrence of lowest trough level. From this as a new point of origin the curve starts to repeat itself; but this repetition, of which the first portion appears as the dotted curve 2mal, is displaced 18() degrees in phase from the corresponding portion (Illia) of the first curve. For the sake of clarity portions of the repetition curve have been omitted;v

but the portions 2ll2bfand 203:1, (corresponding to |6211 and |0341'I of the rst' curve) have been included to show the 180 `degree displacement of the high point (22B) of the repetition curve from the high point (|20) of the first curve. A rerepetition curve will of course coincide with the first curve, and so on in'a continuous alternation. The half cycle regions for 90 degrees in each direction from each of' the high points I 2U and 22@ of the curves are obviously regions throughout which substantially minimum blade-trough spacing persists and excellent cleaning action occurs. These regions being at complementary positions in their respective screw rotation cycles, the staggering of best cleaned areas above discussed will be apparent.

t has been mentioned that the liquid coating medium in the screw section II of the trough is in communication withthat in the reservoir section II `around the shaft portion l" through the slot I3a'in partition I3; a substantial area relationshipanvessentially uniform effect on the drainage of allthe'aggregate pieces is insured.v

of liquid communication' may exist in this slot. To prevent unnecessary circulation between these sections, with attendant contamination of the coating medium in the reservoir section by foreign matter from the aggregate surface, we provide the baiile 3| about the shaft portion I just above the partition I3. The baffle may be of flat circular form somewhat less in diameter for example than the screw periphery, may have a central hole substantially fitting the shaft portion, and may be retained in slight spaced relation to the partition I3 by a plurality of buttons 33 secured to the face of the bale. This slight spacing affords ample opportunity for flow of coating medium from the reservoir section into the screw section as consumption occurs from the latter, but prevents any appreciable circulation between the two sections, as well as aggregate passage into the reservoir section. For convenience in inserting the baiile it may be formed in two halves Sla and SIb (see Figure 6) which may be assembled about the shaft and secured together by the welding to both of a plurality of flat straps 32. It is of course immaterial whether or not the baiiie tends to rotate with the main shaft system; and the shoulder formed by the lower extremity of screw shaft 1"', as well as gravity, maintains it always in its proper position longitudinally of the main shaft.

For draining the reservoir section upon any termination of use we may provide the drain pipe 35, normally closed b-y the cap 35'; the pipe 35 may pass through an oversize hole I in the bottom of the main casing I. For draining the screw section into the reservoir pipe we may provide the removable plug 34 at the bottom of the partition I3.

The operation of the illustrated machine has been developed in connection with the description of structural features. In review of the more fundamental actions, however, it may be pointed out that the oscillatory trough-blade spacing reduction occurs with sufficient frequency to preclude appreciable segregation of the aggregate, so that the drainage of excess coating from all the aggregate can and does occur unimpededly during the intervals of full and near-full spacing; this results in a very uniform coating on all pieces of the aggregate as discharged from the machine. 'I'he slow decrease and rapid increase of the separation provides a very efficient apportionment between segregation-preventing and draining actions. The desirable eifect of cleaning of the bottom of the trough is inherently obtained, and is particularly uniform over the whole trough length when the non-integral relationships above-mentioned are observed. The yieldable suspension of the trough, convenient in carrying out the spacing variation, is itself of value in minimizing danger of aggregate jamming. Other benecial eifects and advantages have also been mentioned above.

While we have with particularity illustrated and described our invention in terms of a typical embodiment thereof, we do not intend to limit the scope of our invention by the details of that embodiment, but rather intend to express the same in the appended claims, as broadly as the state of the art will permit.

1.An aggregate coating machine having, in combination,an inclined trough adapted to receive aggregate in its lower portion; means for maintaining a bath of coating material in said lower portion; blade means Within said trough, having edge portions adjacent the bottom of said trough but with a spacing therefrom, operative to move aggregate upwardly of said trough for drainage; and means for maintaining said drainage substantially unimpeded, comprising means for effecting periodic substantial reductions and restorations of said spacing.

2. The combination according to claim l, wherein said last mentioned means are so arranged that each reduction of said spacing is relatively slow and each restoration thereof relatively rapid.

3. An aggregate coating machine having, in combination, a non-vertical trough, a rotary blade within said trough arranged for rotation to move its periphery adjacent the bottom of said trough but with a spacing'therefrom, and means operative during said blade rotation for oscillatorily and substantially varying said spacing.

4. The combination according to claim 3, wherein said varying means are so arranged that in each cycle of said spacing variation the reduction of said spacing is relatively slow and the increase of said spacing relatively rapid.

5. An aggregate coating machine having, in combination, a non-vertical trough, a rotary blade within said trough arranged for rotation to move its periphery adjacent the bottom of said trough, and means for oscillatorily and substantially raising and lowering said trough to vary the spacing of said trough bottom from said blade.

6. An aggregate coating machine having, in combination, a non-vertical trough adapted to receive aggregate; an aggregate-advancing screw within said trough arranged for rotation with its periphery in spaced relation to the bottom of said trough; and automatic means, comprising said screw and devices relatively positioning said screw and said trough, for periodically and alternately cleaning sections of the bottom of said trough.

'7. A machine for progressing aggregate having, in combination, an inclined trough arranged to receive aggregate at one end and to discharge it at the other, an aggregate-advancing screw rotatable within said trough, and means for supporting said screw, said trough being suspended yieldably with respect to said screw supporting means.

8. An aggregate coating machine having, in combination, a non-vertical trough; a shaft arranged for rotation within said trough and a blade secured on said shaft; and devices disposed above said shaft and arranged for periodic rise and fall upon said rotation thereof, said trough being suspended from said devices.

9. An aggregate coating machine having, in combination, a trough; a shaft arranged for rotation within said trough and a blade secured on said shaft; a second shaft above said rst shaft and arranged for rotation in predetermined speed relationship thereto; and devices carried by said second shaft and arranged for periodic rise and fall upon rotation thereof, said trough being suspended from said devices.

10. An aggregate coating machine having, in combination, a trough; a shaft arranged for rotation within said trough and a blade secured on said shaft; a second shaft above said first shaft and arranged for rotation therewith; a plurality of cams secured on said second shaft; and chains passing over said cams and suspending said trough therefrom.

11. An aggregate coating machine having, in

Combination, an inclined trough; an inclined screw arranged for rotation within said trough; devices disposed above said screw and arranged for periodic movement toward and away from the axis of said screw upon rotation thereof; means suspending said trough from said devices; and means for retaining said trough against lowering movement axial of said screw.

12. An aggregate coating machine having, in combination, an inclined trough having a main compartment and a screw longitudinally disposed in said compartment; and means for maintaining a bath of coating material at a predetermined level in said compartment, comprising a reservoir compartment adjacent the lower extremity of said main compartment and communicating therewith through a narrow aperture only, and means for maintaining a supply of coating material at said predetermined level in said reservoir compartment.

13. An aggregate coating machine having, in combination, an inclined main casing; an inclined trough within said casing and a transverse partition dividing said trough into upper and lower compartments; a bearing hung from said casing into said lower compartment and a bearing at the upper extremity of said casing; a shaft journalled in said bearings, said partition and upper extremity of said trough being slotted to pass said shaft; and a blade secured on said shaft within said main trough compartment.

14. The combination according to claim 13, further including a baffle plate surrounding said shaft within said main compartment and slightly spaced from said partition.

15. The combination accor-ding to claim 13, further including means for raising and lowering said trough in a direction transverse thereof.

16. The combination according to claim 13, further including a second shaft supported to said main casing for rotation above said trough, and devices on said shaft arranged for rise and fall upon said rotation, said trough being suspended from sai-d devices.

17. An aggregate coating machine having, in combination, an inclined trough adapted to receive aggregate in its lower portion; means for maintaining a bath of coating material in said lower portion; a rotary blade within said trough, having a periphery adjacent the bottom of said trough but with a spacing therefrom, arranged for rotation to move aggregate upwardly of said trough for drainage; and means for maintaining said drainage substantially unimpeded, comprising means for reducing and restoring said spacing once each in successive periods which are longer than the blade rotation period.

18. The combination according to claim 17, wherein said last mentioned means are so arranged that each of said successive periods is a non-integral multiple of blade rotation period.

19. An aggregate coating machine having, in combination, a non-Vertical trough; a rotary lade within said trough arranged for rotation to move its periphery adjacent the bottom of said trough but with a spacing therefrom; and means` for oscillatory varying said spacing, said means having a variation period longer than the period of rotation of said blade.

20. The combination according to' claim 19,

wherein the variation period of said means is a non-integral multiple of the blade rotation period.

WALLACE M. HENDRICK. GUSTAVE LOEFFLER, J R.

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