US2350686A - Knife cleaner for rotary tobaccoleaf cutting machines - Google Patents

Description

June 6, 1944. H. w. LANGRISH 2,350,685

KNIFE CLEANER FOR ROTARY TOBACCO-LEAF.CUTTING MACHINES Filed Oct. 2 1941 2 Sheets-Sheet 1 Jung 6, 1944. H. w. LANGRISH 2,350,686

KNIFE CLEANER FOR ROTARY TOBACCO-LEAF CUTTING MACHINES Filed Oct. 2. 1941 2 Sheets-Sheet 2 angle is'chosen by experiment to find the best 7 for cutting a cheese of the cross-section determined ,1 by. the? particular rnouthpiece. The edge ofeach knife lies in a plane normal to the axis of rotation of theknife carrier. The edge of each knife may thus be said to be a line on the rotatable head. V w

the method hereinafter described with respect to with that of the knife carrier shaft 2'. Secured to the shaft I for arcuate-movement therewith (e. g. rotation) is a remover element which' com' I prises a scraper l. The scraper is fixed toa block H which is pivoted at 8 to a lever 9 fixed on the shaft, i0 .whichforms the axis of rotation of the. remover element. of slight movementabout the pin 8again'st the tension of; the spring I 2. The lever-9 may be ro- :tated. in any .convenientmanner but for simplicity it is, shownas being driven :by, a chain from the shaftlof the knife: carrier. Tothis shaft. there is fixed a sprocket wheell3on which *achain l4 runs; the chain also'passesover a small sprocket J5 fixed to the spindle l0 about,

vthe axis. of which the element revolves. The operative portion of the scraper is, in one form, of substantially inverted V shapeand at the apex of the- V' thescraper is arranged to engage the knife edge whilegon one side ofthe V it engages the=backof the: knife and on the other side=of they engages the chamfer on the frontof the knife, all inthe manner to be described here- :after withreference to Figures 3 and 4;

The orbital-path of the knife edge is intersected by the, path. of the apex of the V. and the relative speeds ofthe knife and thescraper and the distance of each from the axis about which it moves are so chosen .that the trace of the ex- 171'611'18 point of the apex of the V coincides with accordance with the invention is shown-in Fig- The block Ii is capable the'flinifeedgeflles atan angle of" 32; with respect to the radius RI so'that the upper position of the knife edge is easily drawn in by placing it at an angle of 32 with respect to the radius R2 A line X--Y drawn through the intersec- At some suitable position to be determined by 1 ctions a, n, 0.1 r, m so obtained is an arc of a circle, the radius Z of which can be readily ascer- Figure 2, a second shaft II] is mounted ,forrota-j "taine d by'construction and measurement, thus tion, the axis of this second shaft beingl parallel determining the position for the axis I'll of rotation of the scraper. This are 9, n, o, p, r, m,

is. therefore a trace in space formed by a point 1 fprogressing outwardly along the line a, g at sucsecond revolution of the knife carrier.

of the edge, that the ,whole 11.40.

cessivemoments during movement of the rotatable 'knife carrier. This are having beenobtained,- the relative angular speeds of the knife .and scraper can be readily calculated once the angular speedof the knifexis known, since the linear speed of the scraper must equal the speed at which the trace is formed. I

, In the machine being described the scraper -rnakes five revolutions to two of the knife carrierso that each knife is scraped during each As above described the arrangement is adapt- I ed' to scrape the entire straight edge of a knife. 'Since, however, the knife is continually ground during the operation of the machine by the grinding wheel shown in Figure 1 the edge of the knife is usually notquite straight but is concave. The extent to which theedgeis not straight is about .005" to. .01! between the oppositecorners In some cases it is not. important of; the.edge shall be engaged by the scraper, andjn these. cases moving the scraper over the edge -and, in close...proximity ,thereto will ensurelthat no undue accumulation of resinous substanceswillloceurbn the knife. .Whenrhowever, it is desired to. scrape the entire edge in such cases, the scraper is resiliently mounted on the lever secured to the scraper shaft as described with reference to Figure 1. The

scraper could of course be articulated and arranged to move out .by centrifugal force against theknife edge to follow. the latter .where it deviates from a straight line.

ure 2. ,The distanCe through. which it is de-" sired that the knife. shall be, moved during the scraping operation is first selected and as shown on'the diagram, this distance corresponds to the distance between the ends a and m of the radial .lines RI, and R2. The orbital path of the knife is, of course, known and asshown the corners of theknife travel along arcs struck about the axis of; rotation from the points A and G. The -angular speed at. which'the knife is'moved is -also known and is constant. A number of equispaced points g to a, respectively representing selected positions of a point progressing outwardly along the edge are next selected along the knife edge and through these points are drawn arcuate linesA to G struck about the axis of rotation-G ofthe knifecarrier. ,:These lines pass throughthat part of the orbital path within'which scraping is to be effected. A number of vfines, d n, i, 7, 7c,.l, m, equal to the number of.

' It should also be j Similarly if it is not convenientto position the Qaxisof rotation of the scraper in its exact posi- ,tion so as to ensure that it moves along the tracelg, n, 0, 2 L1, m, then thescrapermay be resiliently mounted or arranged to move out'as above-mentioned by centrifugal force.

a'ppreciatedjthat when it is not necessary that the scrapershall engage the positions the axis ofrotation of the ensure that the scraper follows the said trace. Insuch a case, however, it will be understood that the direction of movement of the scraper would, nevertheless, require to be substantially straight in order toobtain the requisite scraping effect. I

By frequently engaging the edge of the knife with the scraper in the manner above described, any burrs which tend to form are quickly removed.

Referring to Figures 3-11' which show various forms of scrapers and the manner in which they operate to remove materialfrom the rotatable .element, the scrapershown in Figures 3 and I4 is of substantially inverted V shape, the apex it of the V being arranged to engage the knife edge as shown in Figure 9 while the side I! of the V engages the back of the knife and part of the clamp while the other side l3 of the V engages a chamfer on the front of the knife. In Figures 5 and 6 the scraper is only provided with one scraping edge 19 which engages the clamp on the back of the knife as shown in Figure 10. The scraper shown in Figures 7 and 8 is adapted to remove material from the ground face of the knife and the neighbouring face of the front portion of the knife, i. e. the face nearer to the cheese of tobacco and part of the front clamp. This scraper operates in the manner shown in Figur 11. If desired other shapes of scrapers may be designed to scrape, for example the whole of the knife and parts of the front and back clamps. This is shown in Fig. 12 where two scrapers are mounted on the block l I, one behind the other, each scraper dealing with a part of the surface on which the resinous material accumulates, the leading scraper la being that shown in Figures 3, 4, and 9, and the following scraper lb being that shown in Figures '7, 8, and 11.

Although in the examples given, the edge of the knife has been considered as straight or substantially straight and the edge has been assumed to be regular, the invention could also be applied to constructions in which the edge whether irregular or regular has parts which de viate from a straight or substantially straight line to a small extent. For instance, if in a particular application it sufiiced for the remover element to be at a certain maximum distance, it would clearly be possible to construct an edge in which there was either irregularity or curvature to that extent and the words substantially in the direction of a line and substantially along a trace when used herein and in the claims mean that the remover element (whether yieldably mounted on a carrier or not) passes along the line or trace at all times within the minimum distance necessary for performing the intended function. Where, however, the remover element is to act as a grinder or hone, it is clear that the edge of the knife must be a very close approximation to a straight line unless the remover element is yieldably mounted to allow it to compensate for any departure of the knife edge from a straight line. It is to be appreciated, however,

that any such departure from the straight line will be limited by consideration of expediency.

What I claim as my invention and desire to secure by Letters Patent is:

1. In a tobacco cutting machine, a rotatable knife having a substantially straight cutting edge inclined to the radial in a direction outwardly and rearwardly with respect to the direction of rotation and in a plane normal to the axis of rotation, and a scraper blade driven in timed relationship with the knife and shaped to engage the cutting edge and areas in proximity to the cutting edge of the knife to remove material therefrom, during movement of the knife, and means supporting said blade for movement in a curved path about an axis parallel to and spaced from the knife axis in the same angular direction as the knife and outwardly across the path of the knife in a zone laterally removed from a line connecting the axes of the knife and blade, means driving said knife and blade in such timed relation that during the movement of the blade along the knife, the blade is caused to sweep lengthwise of the whole of said cutting edge with a point on said blade progressively engaged with successive points on said cutting edge, said sup porting means retaining said blade against axial displacement during such outward movement.

2. In a tobacco cutting machine, a rotatable knife having a substantially straight cutting edge inclined to the radial in a direction outwardly and rearwardly with respect to the direction of rotation and in a plane normal to the axis of rotation, and a scraper blade driven in timed relationship with the knife and shaped to engage the cutting edge and areas in proximity to the cutting edge of the knife to remove material therefrom, during movement of the knife, and means supporting said knife and blade for rotation on spaced parallel axes and in the same direction, whereby the remover element may move outwardly across the path of the knife in a zone laterally removed from a line connecting the axes of the knife and blade, means yieldingly supporting said blade on said last named means, means driving said knife and blade in such timed relation that during the movement of the blade along the knife, the blade is caused to sweep lengthwise of the whole of said cutting edge with a point on said blade progressively engaged with successive points on said cutting edge.

HENRY WILLIAM LANGRISH.

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