US2340216A - Cutter for dredges - Google Patents

Description

Jan. 25, 1944. F. A. GILL 2,340,216

CUTTER FOR DREDGES Filed May 27, 1941 s Sheets-Sheet i $12 35 lNVENTOR 3 M a. BY

@MQMM ATTO R N EY Jan. 25, 1944. F. A. GILL 2,340,216

CUTTER-FOR DREDGES Filed May 27, 1941 5 Sheets-Sheet 2 INVENTOR 1 14 a. W m Mir;

ATTORNEY Jan. 25,1944. F A G" 2,340,216

CUTTER FOR DREDGES Filed May 27, 1941 3 Sheets-Sheet. 3

ay/3 gay/4 INVENTOR ATTORNEY Patented Jan. 25, 1944 CUTTER FOR DREDGES Fred A. Gill, Lebanon, Pa., assignor of one-half to Guy W. Sackett, Christiansburg, Va.

Application May 27, 1941, No. 395,337

3 Claims. (01.37-67) The invention relates to cutters for suction dredges and more particularly to cutters of the type disclosed in Sackett Patent No. 1,226,386, dated May 15, 1917.

The present invention constitutes an improvement over the cutter disclosed in the above-mentioned Sackett patent, although its principles are not necessarily limited to cutters of the Sackett type. The Sackett cutter comprises a cutter head generally in the shape of a crown comprising a rim or base at one end and a nose or hub at the other end united by curved helical-like blades, the edges of which constitute cutting edges. Se-= cured to these blades are sockets in whichare located cutting teeth for enhancing the cutting effect of the blades, particularly when working, on harder materials, such as hard pan, coral,,soft rock, etc. While the Sackett cutter has gone into extensive commercial use, its cutting teeth are subject to considerable wear, necessitating frequent sharpening and replacement.

The present invention providesa cutter which not only increases the speedof cutting but. also greatly increases the life 'of the cutter head and cutter teeth, increasing the length of. the periods between sharpenings and greatly increasing the overall life of the cutter teeth. According" to the present invention, the 'teeth are madetmore slender, increasing the length of their cutting edges and providing a positive relief or clearance along the depth or width of the tooth which provides more of a cutting or splitting action and reduces friction and wear on the teeth.

The teeth, as shown in the Sackett patent and as heretofore used, are in the nature of picks and are made comparatively thick and heavy and provide points which do most of the cutting ac-' tion. These teeth are subject to considerable wear because they shatter and break the rock rather than split or cleave it.

The invention also provides for the bending of nd .shift, some or all of the teeth being bent,;

in the cutter in use. 7 1

The present invention also locates the, teethon.

if necessary, in accordance with the results noted that the teeth on successive blades do not trail each other. w The invention also consists in certain'ne'wan'd original features of construction and combinations of parts hereinafter set forth and claimed.' Although the novel features which are believed to be characteristic of this invention will be par; ticularly pointed out in the claims appended hereto, the invention itself, as to its objects and advantages, and the manner in which itmay be carried out, may be better understood by refer ring to the following description taken in connece tion with the accompanying drawings formin g a part thereof, in which 7 V Fig. 1 illustrates a common form of dredg'eof which the invention is applied. Fig. 2 is an end view of the cutter head looking; axially thereof, teeth being shown in some of the sockets and omitted in others for purposes of illustration. t

Fig. 3 is a side elevation with parts broken away of the new cutter head, some of the teeth being omitted.

theseveralcutter blades in staggered relation so 66;

. Fig. 4 is a side elevation of a new tooth acc ording to the invention. 7 t

Fig. 5 is a top plan View of the tooth inFig. 4. Fig. 6 is an end elevation of the tooth looking, from nose toward the shank of the tooth. I, Fig. 7 is a section on the line 7-1 of Fig, 4 throughthe blade of the tooth. Fig. 8 is a section on the line 88 of Fig.4- through the shank of the tooth. Figs. 9 and 10 are side elevations of the tooth, corresponding to Fig. 4, showing the blade bent upwardly and downwardly respectively with re-,- spect to the shank. f Figs. 11 and 12 are top plan views of the tooth. corresponding to Fig. 5, but showing the blade-of the tooth bent to the right and to the left respectively with respect to its shank looking from shank to nose. a 1, Figs. 13 and 14 are semi-diagrammatic views, looking axially of the cutter and illustrating the, bending of the tooth blades downwardly and upwardly respectively, and 4 Figs. 15 and 16 are semi-diagrammatic side; elevations of a cutter illustrating the blades of,- the tooth bent to the right and leftrespectively, as viewed in these figures. j, g In the following description and in theclaims, various details will be identified by specific names; for convenience, but they are intended to beas; generic in their application as the art will permit; Like reference charactersdenote like partsin the several figures of the drawings,

In the drawings accompanying and forming part of this specification, certain specific disclosure of the invention is made for purposes of explanation, but it will be understood that the details may be modified in various respects without departure from the broad aspect of the invention.

Referring now to the drawings and more particularly to Fig. 1, my invention is shown applied to one form of suction dredge, this figure showing the parts somewhat diagrammatically. The water or stream is denoted by H and the bed or deposit it is desired to remove is indicated by l2. The barge or float upon which the dredging apparatus is mounted is denoted by H). The cutter denoted by 13 is driven by drive shaft. I4 which in turn is driven by a suitable prime mover H in such manner that the shaft 14 may have universal movement with respect to the dredge Ill. The suction pipe l5 extends from a point within the cutter l3 and has suitable universal connection with suitable pumping apparatus located on the dredge lil. The drive shaft M and suction pipe l5 are assembled together and provided with a suitable means for permitting a workman to climb out to the cutter 13 when it is raised out of the water. This assembly indicated by I6 is commonly known as a ladder and this ladder together with the cutter l3 is movable both vertical-1y and horizontally by a suitable derrick including tackle l9 and beams l8 as will be understood by those skilled in the art.

Referring now to Figs. 2 and 3 the cutter 13 comprises a head or spider connected to drive shaft M which is suitablyjournaled in a cutter head bearing 22 suspended from a link 2i con-- nected to the tackle or ladder fall [9. The bearing 22 has a bearing surface 23 for supporting the rim or back ring 24 of the spider 28. The spider 20 has a hub 25 to which shaft M is suitably secured. Hub 25 and rim 24 are connected by Warped blades 26 which are connected or braced by circular rods or braces 21 to limit the si-zeo'f the openings between the exterior and interior of the head 29. The bearing 22 alsosupports the lower end of suction pipe l5 which'has an opening 3| communicating with the interior of the head 20.

The blades 26 have sharp cutting edges 28 on the sides facing in the direction of rotation, i. e their leading edges are sharp, and are provided with sockets 29 to receive the teeth 30 which are suitably keyed thereto.

The blades 26 extend generally helically from the central hub 25,in a direction opposite to the direction of rotation of the head indicated by Ain Fig. 2, to the rim or base 24 of the crownshape'd cutter head 26. Every other blade 26 hassixteeth while the intermediate bladeshave five teeth, the teeth on alternate blades being staggered axially of the cutter so thattheteeth onth'e irr'in'iediately following blades do notfollow directlyi'n the paths cut by the teeth immediately preceding. -As in the Sackett patent, the blades 26 are shaped to provide a nose M projectingaaxially of the hub 25 and to insure there being always some part of some blade in cutting action.

Referring now to Figs. '4 to 8, the teeth 30. are made up of a tapered shank 32 having topsurface 33, bottom surface 34 and sidesurfaces 35 and 36, this shank-engaging a similarly shaped interior surface of the several'sockets 29. Integral with the shank 32 is a blade 311 having a top-surface 38 and converging side surfaces 33 and 40 forming .relief'angles c (Fig. "7) The intersection of top surface 38 and side surfaces 39 and 40 form cutting edges 42 for which the relief angles 0 are provided. The side faces 39 and 40 meet in a comparatively narrow bottom edge 01' surface indicated by as which partakes or" a gentle curve from the nose 4! merging into the bottom surface 34 of shank 32. The blade 31 and shank 32 are joined by a portion indicated by 46 which will be termed the neck, at which the blade may be bent with respect to the shank 32 for certain purposes as will hereinafter be described more in detail.

The approximately median line through the shank and blades of a straight tooth will be called the axis for convenience and is indicated by -45. When the teeth are mounted in their sockets this line or axis is located in a plane substantially perpendicular to the axis of rotation for teeth near the rim 24, while the sockets for those teeth nearer the nose M locate the axes of the teeth at increasingly greater angles with rwpect to planes perpendicular to the axis of revolution as indicated particularly in Fig. 3. In all cases the tooth axes are located at positions between radii from the axis of rotation passing through the teeth and tangents to said radii, which indicate the direction of tooth move ment at any particular instant. Thus. the top surface 38 and cutting edges d2 of the tooth blades 31 are leading surfaces and edges while the bottom edges G3 are trailing.

Before explaining the useof the invention some idea of size will be given. It will be understood that we are dealing with heavy machinery. For example, the cutter head may weigh about 15,000 lbs. and each individual tooth may weigh between and lbs. In the particular installation illustrated, there are 33 teeth so the teeth alone will weigh consider-ably over a ton. The cutter head may be five or six feet in diameter at its rim or open end and may be five or six feet in length, that is, axially. The cutter .teeth may run over two feet in length and may be 4 inches wide at the top and 4 inches in depth (from top 38 to bottom 43). The cutter head may rotate at a speed of 20 revolutions per minute. It will be understood that the above figures are illustrative only and the various sizes, weights and other values will vary with the particular installation.

To use the above invention, new and sharp straight teeth 30 having substantially the shape indicated will. be mounted in the cutter head sockets 29: and keyed or locked in. The cutter head l3 will of course have been detached from drive shaftv 14, the work of mounting the teeth 30 being done on the deck of barge I-ll as will be understood by those skilled in the art. Thehead or spider 20 will then be mounted in position on the end of the-driveshaft M, the ladder 16.0fcourse, being in raised position to permit this operation. Theladder will then be lowered into the water and we, are ready for dredging.

The dredging procedure will .depend upon the technique of the particular operator and also upon conditions or the nature of the bed to. be, removed. The dredge Willbe moved to plac the cutter head I3up'against the bed it. is desiredft'o. cut illustrated-by- I2 in'Fig. 1,'the cutter'headwill be started rotating-in the di-rection indicated by the arrow -A'in Fig. 2 and the ladder f6 will be moved in a long horizontal sweep, cutting in the direction indicated by the arrow B. At theend of each horizontal sweep, the ladder i6 willbe returned no cutting being done'on thereturn trip.

'Upon the'next cuttin'gitrip in the direction'oi the arrow B, a further line or path will'be cut'in the rock l2. edges 28 wi1l cut the softer materials such as clay, etc. The teeth 30 will cleave the rock into comparatively small pieces which must pass through the openings in the cutter head whence they are sucked by the suction pipe l5 and discharged in accordance with well-known suction dredge practice. I

After a given cutting period, which again will depend upon cutting conditions but which may be three or four hours, the ladder I6 is raised, the cutter stopped and a man crawls out on the ladder to look at the teeth. If the teeth are not too dull, the cutting may be resumed until it is decided that the teeth are too dull for further work.

...While the cutting operation is going on, a spare cutting head will be conditioned to replace the cutting head in use when it must be removed after becoming dull. The cutting teeth will be mounted in the spare head 20in a manner sim-' ilar to mounting them on the first head, but some or all of the new teeth, or resharpened teeth, as the case may be, instead of all being straight, will be bent to overcome the wear as indicated by. an

inspection of the teeth on the first head. Thus,"

when the first head must be removed for further sharpening of its teeth, the spare head will be ready to be put in place. The length of a-cutting period will vary with conditions, running for 6X? ample from 18 to 20 hours. For hard rock,-.the period may be as short as '12'hours before the head must come off for the resharpening ofthe teeth. For soft rock, the period may be as long as 48 hours before it is necessary to remove the head for resharpening. v

For bending the teeth a special bending press may be provided. The bodies of the teeth will be bent at their necks 46 with respect to their shanks 32, either up as in Fig. 9; down as in Fig. 10; right as in Fig. 11; or left as in Fig. 12, considering the surfaces 33 and 38 as the top of the tooth andlooking from shank 32 to nose 4|. Generally speaking, the side bending will be in the direction of wear. For example, if a tooth in use shows more wear on the right side (surface 39) the cor responding tooth of the spare job will be bent toward the right side to the shape shown in Fig. 11. If the wear is on the left side (surface 40) the. corresponding tooth will be bent toward the left side to the shape shown in Fig. 12. The up and down-bending will be dependent upon the amount of wear on the lower edge 43 of the teeth. If the wear on lower edge 43 is too great, indicated by the depth or width (distance from upper surface 38 to lower edge 43) being too small, generally speaking, the tooth will be bent downwardly as indicated in Fig. 10; if the wear on lower edge 43 is too little, the tooth will be bent upwardly as shown in Fig. 9.

The relationship of the teeth with respect to the axis of rotation indicated by 41 and the effect of bending will be better understood by referring to Figs. 13-16. Here the sockets are omitted to better illustrate the tooth angles. In Fig. 13 the tooth blade 31 is bent with respect to its original axis 45 downwardly, or oppositely to the direction of rotation A, through the angle d, thus corresponding to Fig. 10. In Fig. 14 the tooth blade 31 is bent upwardly, or into the direction of rotation A, through the angle e, corresponding to Fig. 9. In Fig. 15 the tooth blade is bent laterally toward the rim 24 through angle 1, corresponding to Fig. 12. In Fig. 16 the tooth blade The cutting blades 26 having cutting,

is bent laterally. toward the nose 44 through angleg, corresponding to Fig. 11. V

The uneven distribution of wear on the several teeth is caused bya number of factors, among whichare the kind and condition of the deposit, the direction of .stratification, etc. In any event, whatever. the causeofuneven wear on the several teeth, the teeth .are bent either sideways or up and downto'lessen this wear so that, when the spare cutter head is placed in cutting position, it will cut more efficiently and its teeth will last longeni When the first cutting head is removed from its drive shaft, itsteeth are removed and they are sharpened .by;. heating and. pounding undera steam hammerto-replace the cutting edges 42 and to provide the relief 0 as indicated in Fig. 7; The sharpening .orhamme'ring action draws the teeth, using'the stock .in the body to form the cutting edges and the relief angle similarto the original teeth, but as the tooth. is repeatedly sharpened, thev blade 31 becomes thinner, although its cuttingedgesand relief angles will be kept constant;- As the teeth become thinner, they naturallybe'com more'efiicient in their cutting or, splitting action. As an example, an average tooth may-take four or five sharpenings before it must be discarded, .but the use of the invention will double the tooth life between sharpenings.

The tooth according to the invention is highly efficient in that. it provides more efficient cutting or splitting action and less pulverizing or ham! mering, action The comparatively thin blade 31 provides splitting efiiciency and the depth or width of the, blade provides sufficient strength" to permitthe blade to be narrow and the relief angle 0 ,orzclearance reduces friction and resist-' ance of the teeth as they pass through the rock. The repeated scraping of the rock on the teeth: acts as abrasive which gradually Wears the teethaway, but the narrower teeth acting as blades, become more'emcient in use due to the increased splittingaction. The tapering of the upper sur-: face 38 of the tooth blade and the more uniform thicknesspof thelower edge43 provides a variable relief angle c; increasing from nose 4| to shank- 32 It will be found that thebending of the teeth not only increasesthe life of the teeth but also increases the life ofthe sockets 29. It 'is cus tomary tov replace the metal scraped from the sockets by the abrasion of the rock, by adding metal by welding. Th bending of the teeth protects these sockets and reduces the. amount of the material it is necessary to add to the sockets.

Thus, a cutting tooth for suction dredges is provided which has higher cutting efliciency and longer life. The relief angle reduces the friction of the teeth as they pass through the rock. The narrowness of the teeth makes it more bladelike and its depth gives it strength. The bending of the teeth reduces uneven wear by causing the teeth to bite into the rock rather than to merely scrape it. A scraping tooth does no cutting and yet adds friction and wears out prematurely.

While certain novel features of the invention have been disclosed herein, and are pointed out in the annexed claims, it will be understood that tier sockets of generai-lyrectangular ternal cross section, teeth in said sockets, each tooth having a relatively heavy tapered shank of generally rectangular cross section seated in its socket and a cutting and "wedging blade comparatively deep .or wide in the direction or cutting movement and comparatively thin in the direction transverse tov said cutting movement, said tooth blade having a com-nanatime-ly flat leading surface merging into the top surztace of said shank, said leading surtace eonveming in width outwardly to a blunt nose of restricted dimension, said tooth blade having side surfaces converging to a relatively small blunt trailing edge, the intersection of said leading surface and said side surfaces fanning edges, said converging side surfaces providing relief for said cutting edges, said trailing edge merging the bottom surface of said shank, said trailing edge extending from shank to nose andior'ming :a relatively small angle with said leading surface near said shank and for .a substantial part of length of the blade, and partaking or anrdtuberant outline toward the outer end vof the blade and f-orming a relatively large acute angle with said leading surface at said nose, the general tapering nature of said tooth blade from shank to hose providing wedging action as the tooth enters the rock, the comparatively thin and deep or wide blade and its relieved cutting edges iproviding cutting action as the tooth :cuts .a swath through the rock.

.2. In hydraulic suction dredging, a rotary cutter having sockets of generally rectangular in: ternal cross section, teeth in said .sochets, each tooth having a relatively heavy tapered shank of generally rectangular cross section seated in its socket and a cutting and wedging blade comparatively deep or wide in the direction of cutting movement and comparatively thin in "the direction. transverse to said cutting movement, said vidin-g relief for said cutting edges, said relief becoming increasingly larger from said-nose toward said shank, said trailing edge 'being substantially coextensive with the adjacent bottomsin-race of said shank, said trailing edge extermiing from to nose and donning a relativel small angle with said leading surface near shank andror-a substantial part or length of the blade; and partaking of a protuberant outline toward the outer end of the blade and form'- ing a relatively large acute angle with said leadingsurface at said nose, the general tapering nature of said tooth blade fromshan-k to nose providingwedging action as the tooth enters the rock, the comparatively thin and deep or wide blade and its relieved cutting gesprovidms cutting action as the tooth cuts a swath through therock. l

'3, In hydraulicgsuction dredging, a rotary cut.- ter. comprising. a crown-shaped head having a hub and a :back ring, a plurality of helicoidal blades connecting said hub and {back ring, .sockets of generally rectangular internal ,crcssesece tion on said blades, teeth in said sockets, each tooth having a relatively heavy tapered shank of generally rectangu ar cross section seated in its sockets and a cutting and wedgi-ng blade comparatively deep or wide in the direction of cutting movement and comparatively thin in the direction transverse "to said cut-ting movement said tooth blade having a comparatively flat leading surface substantially coextensive with the adjacent top surf-ace of said shank, said leading surface converging in width outwardly to a blunt nosenose of substantial but restricted dimension, said :toolih blade ihaving side surfaces converging to a relatively small hlunt trailing edge, the inters'ection of said lea-ding surface and said side smifaces forming cutting edges, said converging side surfaces providing relief for said cutting edges, said relief becoming increasingly lar er from .said nose toward said shank, rsazld'trailing edge being substantially coextensive the adiacent bottom surface of said shank, said .trailing edge extending from shan'kto nose and describing .a relatively small angle with said leading surface near said shank and for a substantial of length or the blade, and describing a gentle curvle toward the outer end of the blade ending in :a relatively large :acute angle with said leading surface atisaidnose, the general tapering nature of said tooth blade from shank to mose providing wedging action as the tooth enters the rock, the 'wmpamtively and deep .01 wide blade and its relieved cutting edges providing cutting action as the tooth cuts a swath through therock;

FRED A. GILL.

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