US2535692A - Rotary knife tobacco cutting machine - Google Patents

Description

Dec. 26, 1950 D. w. MOLINS ETAL ROTARY KNIFE TOBACCO CUTTING MACHINE Filed Jan. 29, 1946 4 Sheets-Sheet l fivenl'for 25.1.0. Wag- M :b'. a

Dec. 26, 1950 D. w. MOLINS ETAL ROTARY KNIFE TOBACCO CUTTING MACHINE Filed Jan. 29, 1946 4 Sheets-Sheet 3 Dec. 26, 1950 D. w. MOLINS ETAL ROTARY KNIFE TOBACCO CUTTING MACHINE 4 Sheets-Sheet 4 Filed Jan. 29, 1946 a? ray/j! Patented Dec. 26, 1950 UNITED STATE ROTARY KNIFE TOBACCO CUTTING MACHINE Desmond Walter Molins, Felix Frederic Ruau, and George Dearsley, London, England, assignors to Molins Machine Company Limited, London,

England Application January 29, 1946, Serial No. 644,133 In Great Britain January 31, 1945 3 Claims.

This invention concerns improvements in or relating to rotary tobacco cutting machines.

When leaf tobacco is to be cut into shreds, for instance to prepare cigarette tobacco, the leaves are first compressed into a solid mass frequently referred to as a cheese. As the leaves are of a substantial area relatively to their thickness it will be seen that if the mass of leaves is compressed from two opposite sides only, then the mass of leaves will naturally form a cheese having strata Whose planes are substantially normal to the direction in which the compression is applied. This is so whatever the original orientation of the individual leaves in the mass, for it will be seen that during compression, the leaves which are not already lying in planes sub stantially normal to the direction in which compression is applied will, due to the compression, have portions turned or folded so that they finally close up in such planes, and their contact ing surfaces form the lines of cleavage of the cheese.

If tobacco is cut by hand the cutter cuts across the end of the cheese with a broad knife whose edge moves parallel to itself in the same direction as the above mentioned direction of compression, although the edge of the knife is usually at an angle to the strata of thecheese to secure; a shearing cut. The earlier forms of cutting machine imitated this motion, being, in effect, guillotines of various designs.

With the introduction of rotary cutters to obtain the large outputs necessary nowadays it was not easily possible to follow this practice, as for practical reasons it is simplest to feed and comsides, as distinct from the mathematical directions of the actual forces set up.

In order to obtain a large output with such an arrangement it will be appreciated that it is necessary to have a cheese of a suitably large cross-sectional area. Where the tobacco is compressed between top and bottom conveyors it is important that the depth of the cheese shall be kept as small as possible, and in practice this latter is between 2 and 2% inches. The reason is that it is important that the amount of stationary surfaces at the sides of the stream which would tend to hold up the tobacco being fed, should be kept as small as possible, consistent, however, with keeping the stream as large as possible to obtain the maximum output. In practice, therefore, the depth of 2 to 2% inches at the mouthpiece was found adequate as compared with a width of 16 inches, which width was found to be sufficient to enable the machine to be supplied by hand, and was approximately the acceptedsize in the trade for tobacco-cutting mouthpieces. Such an arrangement with such proportions for the cheese enables the use of relatively large compressing and driving surfaces to engage the tobacco stream, whilst only relatively small stationary surfaces tend to hold up the feeding of the tobacco. With such an arrangement it is only possible, in a construction in which the knife edges rotate in a flat or conical plane, to arrange for the blades on the cutter to out through the cheese in the direction of compression by arranging the center of rotation of press the tobacco so that the strata are substantially parallel to the conveyor on which the leaves are fed and compressed. This is because the conveyor for feeding the stream of tobacco which is compressed into cheese form is most easily arranged to move beneath so as to support the tobacco. Above this conveyor another conveyor was provided, the two conveyors being arranged to converge so that the tobacco stream was compressed into cheese form by these top and bottom conveyors.

Since, as mentioned above, the strata of the cheese are normal to the direction of compression, in such a construction the intersections 'is applied and the direction of compression are intended to mean the general line along which athe tobacco itself is condensed from opposite the knives at one side of the cheese. However, such an arrangement requires a considerable amount of floor space, and also requires thatihe radial extent of the cutter arms and knives should be very long so that the full 16 inches width of the cheese is covered; thus a veryconsiderable leverage is applied. Obviously such an arrangement would not be desirable in the case of machines designed primarily for large output. The leverage on the cutter arms can of course be reduced by reducing the width of the cheese, but reducing the width of the cheese merely reduces, the output unless the width of the side walls is increased. However, increasoing the width of the side walls upsets the feeding of the of the strata with the cutting face of the cheese.

cheese, and consequently one is left with. the same difliculty as originally.

Machines having rotating cutter-heads have been extensively used in practice, such machines having converging top and bottom conveyor bands, and a knife-head rotatable about an axis which is located above the mouthpiece and extends in the same general direction as the tobacco stream. In such machines a large output is maintained by keeping the proportions of, the cheese substantially the same as mentioned above by placing the center of rotation ofthe 3 5 51 W? he *cheese, thus cutting across 3 the widtirof the cheese andesubstantiallyralong the strata. With such an arrangement, of course, the radial extent of the cutter arms and knives can be made shorter than would be required if the axis of rotation were at the side however, the blades can be arranged to shear across the "fchee'se1nore or less'in'the direction of compressiomit is thought the leaveswillbend away naturally in "strips and 'as they are *rela- .tively'flexible in this direction, some breakage will beiavoided and shreds ofsatisfactoryllength and :texture will be =obtain'ed.

:According "to the present invention there "is 1 .provided ta itobacco cuttin'g "machine comprising fin "combination a bottom conveyor-system arranged to'support and convey: leaf tobacco to be Tied iforwardly thereon as a stream, conveyor- :systems "arran'gediat each side-.o'f the bottomcon- 'veyor-fsystem and adapted .to ffeed 'and subject such .moving stream to lateral compression "to condense the tobaccmthereby. 'r'e'ducingthe width or the stream supported-by the bottom'conveyor- -'system, a mouthpie'ce through which the con- -"densed stream isfe'd, and a rotatable knife-head havingia cuttingfblade arranged to-move across the path of 'the stream in the general direction of the widthof the stream as the'stre'am'emerges from th'e mouthpiece.

Thiscombination which feeds the tobacco between two side f conveyor systems which compact "the stream laterally, and carries the stream on a 'bottom conveyor system, makes it possible to feed "*a-compressed stream of relatively large cross- '--'sectional area, since at leastthree sides of the stream are engaged and'transported by conveyor systemsjbut the limitations previously essential inthe dimensions of the compressed cheese in tobacco cutters, due to the presence of two sta- "tionary walls, are removed, so that the present arrangementof conveyors gives much wider latitude-in 'thechoice of the cross-sectional dimensions' of the cheese on the part of the designer of the'machine. He obtains the benefitof cut- *ting across the planes of the strata in the cheese, together with the benefit of doing this "without unduly'increasing'the' floor space of the machine, 'and'by suitably choosing thedimensions of thef'cheese"he"can keep the radial dis tance of fthe extremities. of the knife edges and the-actual lengthsof the .knifeedges within reasonable llimits thereby obtaining the practical "advantages of such an arrangement.

Further, according'to the gpresentinven-tion,

there is provided a tobacco-cutting ,machine comprising the I combination ofia cutting .mouth or mouthpiece with means.toffeedandcompress leaves to form a "cheese; said meansLincludin a relatively widebottom conveyor-system adapt ed to receive andsupport. the leave andon which "the leaves arefed' forwardly as a stream, to comjpress the" leaves duringsuch forward movement laterally so as to reducethewidth. of..the.-stream i 'and thereby to form the-latter J into .a compact cheese *cwhose :strata eare "substantially normal to the'supporting surface of the bottom-conveyor- :system, and a rotatable knife-head having at vleastonecutting blade, the axis of rotation of the head being so arranged that the edge of the blade in cutting across the cheese moves in a direction "substantially normal to the strata in ith'e' tcheese.

Thebladeedgezmay be substantially radial to the axis of rotation of the knife-head and the axis-.dfthe knife 'head is located on a line above and substantially along the midwidth of the stream.

Four conveyor systems may be provided to feed 2 and compress the tobacco-stream, said f our conveyor systems comprising two clateral conveyor syste1ns for the sides of the tobacco stream 'and which applycompression to condense the to- 'bacco and-1a top1and a bottom =system, .so' that thetobacco stream is engaged above andibelow and-onits sides by moving surfaces.

The top and a bottom systems may'be substantially parallel so-that no compression isproduced therebyzrexcept insofar as theyfformxeacting surfaces.

ln' orderto 'ensure thata-as far as possibl'ethe :to'bacco mass is-supported only by 'moving-surf ac es the bottom" conveyor system may "comprise three conveyors arranged side by'side, the middle one-being longer than the side onesso as tovapproachnearerlto the:mouthpiece The bottom zconveyor=system*ma-y be tiltedaso as tohave the tobacco outlet higher than-the tobacco inlet.

Automatic feedingmeans may be provided to deliver leaves at the rear end of the machine, comprisinga substantiallyyertica-l chute whereby .the vleaves are partly compressed bygravity and therear wall ofthechute i oscillated-towardsand awayfrom the mass of tobacco in .the chute to facilitate .theidownward movement of the tobacco and to ,providea compressing .-0r compactingforce .as the chute wall movesinwards andpresses tobacco. against. the, rea end of the tobacco stream.

One way of carrying the -.invention into effect will now be described .by wayotexample, with reference to the accompanyin draw'ingsin which:

Figurel is a side elevationof the machine.

Figure 2 is a plan ofpart of Figure lilooking inthe direction oftthe arrow A and shows the general arrangement of the bottom and side conveyors.

Figure 3 is an elevationof part of Figure 1 looking in the direction of the arrow'B and shows the knife-head and neighbouring parts.

Figure 4 is asi'de'elevation showing the'cons'tructicn of the conveyor "chains and sprockets.

:Figure'fi is a plan of part of the chain shown in Figure 4.

Figure *6 shows a method of supporting the "lower run of-the topconveyor chain.

Referring to the drawings, the cutterhead- I *consists of a spider on which are"'m0unted"at equally spaced angles a six blades T2 whose ed'ses sweep acrcss "'a'j-Cllltbing"mO1llih or mouthpiece 3 .(asshown in'Figure 1). 'Thegeneralmethod 10f mounting, i-grind'ing and "feeding-the fblades forwards --is :substantially" as shown in British .i-Patent SpecificationyNo. ;365,997,-:except that :in the present ,ca'sez-the" cutting edges :of .thekblades are-radial .or-substantially. radial; to the "axis of rotationr see Figure .13. -'l;he number :of arms .-;to,the spider and the number ;of .,bl.adeszarefnfi y ated in the figure for clearness. Preferably the edge of the blade just touches the front face of the mouthpiece.

Top and bottom conveyor systems which are described below are located behind the mouthpiece and extend away therefrom in directions normal to the plane thereof. Lateral conveyor systems are similarly arranged except that they diverge as they extend away from the mouthpiece.

A conveyor consists of a number of links 5 of the kind shown in Figure 4, pivoted together to form an endless chain which is mounted on sprockets, 6, Figure 4, which support and drive the chain. The tobacco engaging surface of the links are so constructed that they provide a substantially continuous plane surface for this purpose. In Figures 1, 2 and 3 the chains are shown by single lines and the sprockets by cylinders,

owing to the small scale of said figures.

The top and lateral conveyor systems each consist of a single conveyor 1, 8 and 9 respectively. the spindles of the rear sprockets being journalled in brackets 26, which also support a chute l 4 described later.

The bottom system consists of three side by side conveyors Ill, H and I2 respectively, their rear ends being supported on sprockets carried by a single spindle represented in Figure 2 by its axis l3, so that a broad conveying surface is provided nearly as wide as the greatestdistance between the lateral conveyors, that is at their rear end. The rest of the rear end of the tobacco supportin surface is formed by fixed plates. The triangular gaps between the bottom and side conveyors at the mouthpiece end are also filled by fixed plates. The lateral conveyors 8 and 9 converge towards the mouthpiece to a distance which is rather less than the width of the middle conveyor Ill of the bottom system and the said middle conveyor is, as shown in Figure 2, of such length as to reach up to the mouthpiece while the two conveyors II and I2 at its sides are reduced in length in order to allow space for brackets and other parts which carry the spindles and sprockets which support the lateral conveyors at the forward ends and also because at this position they no longer engage the tobacco owing to the reduced distances between the lateral conveyors.

It is not easy nor entirely necessary to arrange the top conveyor I in the same way as the bottom one and therefore a single conveyor is used similar to the middle conveyor Ill of the bottom system and the remainder of the width of the converging passage is filled in by cover plates 23, Figure 6. These overlap recessed parts The conveyors are all driven by gearing coupled to the spindle of the knife head, which is represented in Figure 1 by its axis 4 and the whole machine is driven by a motor 21. The

speeds of the conveyors are proportioned according to the disposition of the various conveyors and for the purpose in view. The gearing is omitted from the drawings for clearness but. by way of example, a six-blade knife-head for an average machine is driven at 150 R. P. M., that is it makes 900 cuts per minute. Sixty cuts per inch of cheese produces satisfactory cut .tobacco for cigarette making and therefore the conveyors are geared to the head so as to feed 15" per minute. Thus, as the machine is driven the cheese will be fed through the mouthpiece and slices cut therefromin the (desired manner. l

In order to assist in the preliminary of the leaves which are to form the .cheese and to avoid having a machine of inordinate length the leaves are fed, e. g. from a conveyor beltor the trunking of a conveyor system, or as shown in Figure 1, from a feed box 25 into a substantially vertical chute M of a cross section similar to that of the conveyor passage at its rear end. This arrangement is similar to that shown in Figures 1 and 2 of prior British Patent Specification No. 516,805. The chute is sufiiiciently high to cause the leaves to be packed a little under their own weight and the lower end is a curved at 15 to lead into the passage. The rear wall l5 of the chute is pivoted at its upperend at I! and oscillated by an eccentric l8 through the linkage I9, 20 and 2| the eccentric being driven from a suitable part of the machine gearing. This helps the tobacco to move down the chute and also causes the leaves at the bottom of the chute to be fed into the conveyor passage as they are needed.

It is to be understood that the preliminary massing of the leaves by means of the rear wall l5 of the chute is eifected only to pack the leaves to an extent such that the leaves are loosely compact and so that the mass has a substantially constant weight per unit volume to enable the leaves to be fed on to the bottom conveyor of the tobacco-cutting machine at a substantially constant rate. This preliminary massing is obtained by only a relatively light pressure compared with a compression such as is necessary for forming the cheese or even with a significant proportionof such compression. and is really no more than a packing of the leaves, and its purpose is to collect or gather the leaves into a relatively loosely compact form with substantially uniform distribution of the leaves throughout the mass and to pack these gathered leaves against the rear end of the mass of leaves which is being fed and compressed by the tobacco-cutting machine conveyors, into a cheese. i

In order to keep the back of the machine low so as to accommodate a long chute and also to keep the front high to allow for a conveyor to carry away the cut tobacco the front of the frame 22 of the machine is tilted backwards ,a suitable amount, as shown in Figure 1, so that the axis 4 which is normal. to the front of the machine is inclined as previously described and the remainder of the frame is suitably shaped so as. to preserve the proper relationship of knife path to conveyor. V l I I It will be seen that in the construction described the tobacco is received on, a relatively wide supporting surface, at the rear end of the cutteiyfrom the chute l4. Thewidth of the supporting surface at this point is about 36".

Tobacco is fed forwardlytowards the mouthpiece and in so moving it is compressed laterally so as to reduce the width of the stream to form "-t-het'ob'acco stream *remains constant atabout -6". "Ii-his construction has the t'advantage of *not'only ensuring that-the strata-in the"cheese are planes substantially normal to the-bottom 'tobacco' supporting surface which is con- -stituted by the "various supporting plates and theconveyors "I 0, II and 'l2'so that the edge of the blade in 'cutting across the edges is ub- -s'tantially 'parallel 'to the strata and 'thereby' *gives' the "improved cut, but also 'due to the extreme Width and small depth of the tobacco "'strea'm atthe"rear 'end "of the machine at'the bottom of the chute l4,the'tobacco can be more easily*turnedthrough thevery shalp'angle in "*improved "by'the arrangementaccording to the 1 invention; and further "owing to the lateral compression over a very wide widthof small depth. One'of the main advantages obtained by'the "present inventiomprovided the designer takes advantage'ofthe generalsystem of conveying,

"compressing "and cutting accordin to "the pres- '-entinvention, by choosin suitable dimensions for his"cheese,fis that the knife-edges can be 'relatively short.

Further, the shorter the knife-edges, the easier 'it-isto provide for automatic sharpening and "feeding to "compensatefor wear. For instance, a 'knife edge "of about 6" long can be automati- "='cal1y sharpened during the operation of the inachine by a single grindstone so that no traversing mechanism for stone or knifeis necessary. Also,"a knifehavin ashortknife-edge "canbe'fed forwardly in the direction of. its edge "vmore'easily than a Wide knife having a longer -e'dge,-since "the narrower the knife, the easier *itis 'to'gui'deit in a straight path by a single -=central screw 'feed.

-At-theback the automatic feeding from the "'vertical'chute l4 and'the oscillating'rear wall ""l6'isimproved' relatively to the use of the same 1 construction in amachine having top andbot- 'tom compression such as described and shown "'in British Patent Specification No. 516,805. In *cuttingacross' the"ohe'ese, the edge of the blade *lxis parallel to the strata at the centre of the mouthpiece in the case "where the "blade'is'radial, though of course there is slight divergence from -this-position at the beginning and end of the cut, but in all cases it will be appreciated that the edge-of theblade is substantially parand "tothe strata during cutting. In an alternative construction, instead of having conveyors as described, one or moreof the convey- *ors could be'formedbyaseriesof driven rollers.

- What we claim as our invention and desire to secure by-Le'ttersPatent is:

" 1. A t'o'bacco-cuttin machine, comprising, in combination, a conveyor system to feed'a'ma'ss of tobacco-leaves forwardly as a stream while ncondensing the mass by lateral compression to form-acornpact cheese, 2, mouthpiece'toward avhich the said stream is fedand through which the stream'passes'as'a cheese'fiand a rotat- 'able "knife-head having a "cutting blade arto-inovebodily across the mouthpiece in s the igen'erahdirection of the"horizor1tal= \vidtl1fof the stream-so as to cut the "cheese', saidrkriife- "head :being supported "for rotation 'on "an axis generally parallel to the "direction in "which the stream is fed -andspaced vertically fromsai'd mouthpiece, "said conveyor system comprising a bottom endless-band conveyor to supportthe stream and .movable toward the mouthpiece, 'meansproviding an upper surface substantially parallel with the said bottom "conveyor, 's'alid bottom conveyor extending beyond "said upper surface "atthe inlet end,':whereby the "depth ,of

I the streamris kept substantially constant, andja pair of opposed lateral :endless-band conveyors movable toward the mouthpiece and converging in their direction of movement, "said endless band conveyors forming with said upper surface. a. converging compression chamberh'aving an inlet end of a width,"measured horizontally, at least several times greater 'than"the depth thereof, and-a discharge end dimensioned to .conform substantially to 'the .ldimensions t'o'f said mouthpiece, J'an'dof a width not "substanman difierent'from the. depth thereof,.'the construction thus being such "that practically the whole of the compression of the'tobacco leaves into the cheese is ieffectedby the convergence of the, lateral conveyor baridssothatthe resulting cheese formed thereby is vertically stratified.

2. A tobaccoe'cuttin machine as claimed "in claim 1, in which said upperparallel urface is also comprised by an endless b'an'd conveyor, whereby the tobacco stream is engaged'and'supported substantially wholly by the moving 'sur faces of the conveyors, said bottom'conveyor' being composedo'f a plurality ,of endless conveyor bands arranged side by side.

'3. A tobacco-cutting machine, ,as claimed'in claim 1, and comprising automatic'feeding means .todeliver tobacco leaves'to the said bottom conveyor at the inlet end of thecompression-ch'amher, said automatic 'feedingfm'eans, comprising =:a substantially vertical chute wherebythe leaves arepar'tl packed by gravity, arear wall tosaid .chute, and means to-oscillate .said rear walltoward and .awayfrom .the tobacco-.inthe chute to facilitate the downward" movement of .thetobacco andtoprovide a,.preliminary massingof .theleaves.

'DESMOND' WALTER MOLIN S. FELIX FREDERIORUAU. GEORGE 'DEARSLEY.

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

'UNITED STATES 'PA'I'E'NTS

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