US3328923A - Grinder for the cutting knife of a cigarette machine cut-off - Google Patents

Description

y 4, 1967 J. A. MASON ET AL GRINDER FOR THE CUTTING KNIFE OF A CIGARETTE MACHINE CUT-OFF Filed No). 17. 1964 4 Sheets-Sheet 1 N w \\\Q //V l/E N 7 025 JAMES A MA 501V 52/6 En THOMAS July 4, 1967 J MASON ET AL 3,328,923

GRINDER FOR THE CUTTING KNIFE OF A CIGARETTE MACHINE CUT-OFF Filed Nov. 17, 1964 4 Sheets-Sheet 2 lnveu'tovs Jami! G. Mum 6/14 11. Tfimu.

July 4, 1967 MASON ET AL 3,328,923

GRINDER FOR THE CUTTING KNIFE OF A CIGARETTE MACHINE CUT-OFF Filed Nov. 17. 1964 4 Sheets-Sheet S luumvlors Tunas t) M Maw 6y. umm6ei QMM; wane.

Qmnweys July 4,1967 MASON ET AL GRINDER FOR THE CUTTING KNIFE OF A CIGARETTE MACHINE CUT-OFF Filed Nov. 17, 1964 4 Sheets-Sheet 4 j as 9 6M m 07% 0.16am,

United States Patent 3,328,923 GRINDER FOR THE CUTTING KNIFE OF A CIGARETTE MACHINE CUT-OFF James Arthur Mason and Eric Raymond Thomas, London, England, assignors to The Molins Organisation Limited, London, England, a British company Filed Nov. 17, 1964, Ser. No. 411,870 Claims priority, application Great Britain, Nov. 20, 1963, 45,816/ 63 4 Claims. (Cl. 51247) ABSTRACT OF THE DISCLOSURE This invention concerns a cut-off mechanism for a continuous rod cigarette-making machine. The cut-ofi has a flat sickle knife which is given a traverse movement in the direction of the cigarette rod travel during cutting, and a similar return motion, by means of a Hookes joint form of linkage. A grinding roller is situated 180 from the midpoint of the cutting-off action to grind a bevel edge on the knife, and is angularly adjustable to maintain the correct grinding action as the amount of traverse motion is altered to cut off differing cigarette lengths.

This invention concerns an improved grinder for the cut-off of a continuous rod cigarette-making machine, the cut-off being of the kind using a flat knife which has a cutting edge eccentric to the axis of revolution of the knife, and commonly called a sickle knife, and in which the traversing movement for the knife, such that it moves sideways at substantially the speed of the cigarette rod while it is passing through the rod, is produced by mechanism, such as a Hookes joint which causes the knife to be substantially at right angles to the rod during the cut and also at a position 180 therefrom. Such a cut-off will be referred to as a cigarette-machine cut-off of the type described.

This traversing movement has to be altered to obtain different lengths of cigarette since, in machines of the type described, the rod speed is kept constant and the revolutions per minute of the cut-off are increased to cut shorter cigarettes and are reduced to cut longer cigarettes, and so the transit time of the knife through the rod differs with changes in cigarette length.

Efiicient grinding of these knives has always been very difficult because it is necessary, so far as is possible, to keep the sickle edge to a true arc, and avoid a ragged edge, and to attempt to keep the bevel or chamfer caused by grinding to a reasonably sharp angle, irrespective of the length of traverse which changes the range of angles of contact between knife and grinder. It is also very desirable to preserve the arc of the sickle at a constant radius and eccentricity, in spite of changes in the traverse of the knife. The invention aims at meeting these various requirements.

According to the present invention there is provided a grinding device for the knife of a cigarette machine cutoff of the type described, comprising means for altering the rotational speed of the knife and the amount of its traverse to cut off different cigarette lengths, a grinding wheel having a surface formed by the revolution of a substantially straight line about an axis coplanar therewith, the grinding wheel being situated to be in contact with the mid-point of the sickle edge of the knife when that point is at 180 from the axis of the cigarette rod and with its axis in a plane containing said point of contact and the axis of the cigarette rod, means mounting said grinding wheel for rotation about its axis and for adjustment of its axis in said plane about the point of contact of the midpoint of the sickle edge and the grinding wheel through a range of angles relative to the plane of the knife during 3,328,923 Patented July 4, 196 7 the grinding operation such as to grind a chamfer along the whole length of the sickle edge for different cigarette lengths.

The grinding wheel may be cylindrical or frusto-conical. If the wheel is cylindrical then its axis will be inclined to the plane of the knife during the grinding operation for all positions of adjustment in said range of angles. If the grinding wheel is frusto-conical and is arranged to taper inwards towards the rotational axis of the knife then, by choice of a suitable vertex angle for the grinding wheel, it will have its axis parallel with the knife during grinding for one position of adjustment in the range of angles.

The angle of the chamfer on the knife edge will, of course, be different for each angular position of the grinding wheel, and thus for each cigarette length, but this variation is quite small and acceptable. The range of angular adjustment of the grinding wheel may conveniently be arranged to cater for cigarette lengths ranging from 66 mm. to 84 mm.

One embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, of which:

FIGURE 1 shows in front elevation a continuous rod cigarette-making machine having a cut-off of the type described.

FIGURE 2 is a plan view of part of the cut-off with the knife turned through 270 with respect to its position in FIGURE 1, and showing a cylindrical grinding wheel.

FIGURE 3 is a view on the line 33 in FIGURE 2 with the grinding wheel in the position shown in chaindot lines in FIGURE 2, for convenience of illustration.

FIGURE 4 is a diagrammatic illustration of the angular adjustment of the grinding wheel relative to the knife as viewed in FIGURE 2.

FIGURE 5 is a diagrammatic view in the direction of the arrow A in FIGURE 2 along the edge of the knife at various successive positions relative to the grinding wheel during the grinding operation.

FIGURE 6 is a diagrammatic view in the direction of the arrow B in FIGURE 2 showing the different positions of the knife corresponding to those shown in FIGURE 5.

FIGURE 7 is a diagrammatic view corresponding to FIGURE 4 but showing a frusto-conical grinding wheel with its taper towards the axis of revolution of the cut-off.

FIGURE 8 is similar to FIGURE 7 but with the grinding wheel inverted, and

FIGURES 9 and 10 are modifications of FIGURES 4 and 7 respectively.

The machine 1 shown in FIGURE 1 forms a continuous tobacco filler on the underside of an air-pervious conveyor band 2 to which the filler is held by suction. The suction is applied to the band by means of a suction chamber 3 which also produces an air flow up a duct 4 which impels the tobacco particles to the band to build up thereon to form the filler. A continuous paper wrapper 5 is fed into the machine and wrapped around the filler by a folding device 6. The edges of the wrapper are gurnmed by a pasting device 7, and the adhesive is dried by a heater 8. These devices are all of normal construction. A continuous cigarette rod CR thus issues from the heater 8. The continuous rod is cut into equal length cigarettes by a cut-off mechanism 9, and the separate cigarettes are each received in a flute of a drum 10 and carried away from the machine on a catcher band 11.

The cut-off mechanism 9 is of generally well known form and comprises a sickle knife 12, i.e. a fiat knife which has a cutting edge substantially in the form of a circular arc eccentric to the axis about which the knife is rotated. The rotation of the knife 12 is produced by a shaft 13 which is the output shaft of a gearbox 14 driven from the mainshaft of the machine in the normal manner. The traversing movement of the knife 12 during its rotation i.e. the motion of the knife in the direction of travel of, and at substantially the same speed as, the cigarette rod, during the cutting of the rod, and also the corresponding and identically similar return motion, is produced 'by the inclination to the horizontal of a shaft which is mounted for rotation in a member 16. The member 16 can be moved up or down in the plane of the figure to alter the angle between the shafts 13 and 15, the member 16 being slidable in a bearing block 17 having a part circular surface 18. The shaft 13 is connected by a pivot pin with two members 19 (only one of which is shown in FIGURE 1) which are arranged on either side of a member 20 which is secured to the shaft 15. The knife 12 is carried by the members 19 which can pivot about an axis at right angles to the pivotal connection between the shaft 13 and the members 19. This construction will later be made clear by reference to FIGURES 2 and 3. The effect of this manner of mounting the knife 12 is that the knife is carried by the intermediate member connecting two mutually inclined shafts in a Hookes joint.

In FIGURES 2 and 3 the member 16 and the bearing block 17 are omitted. In FIGURES 2 and 3 the cut-off is shown, for convenience of illustration, with the two shafts 13 and 15 coaxial. To correspond with the position shown in FIGURE 1, the end of the shaft 15 would be inclined downwards into the plane of FIGURE 2, and be inclined to the downwards in FIGURE 3. Thus, when the knife 12 has rotated with the shaft 15 through 180 from the position shown in these figures, and is cutting through the cigarette rod CR, it will be travelling bodily in the direction of movement of the cigarette rod. To make clear the direction of movement of the cigarette rod CR an arrow has been added to the rod in FIG- URE 2.

The cigarette rod is supported for the cutting operation by a ledger 21 comprising three tubular members 21a, 21b and 210. The members 21a and 21b are separated by a small gap through which the knife 12 passes during the cutting operation. The ledger 21 is reciprocated in the direction of the cigarette rod CR by a crank mechanism shown generally at 22, and of normal construction, which is driven from the gearbox 14, the arrangement being such that the ledger 21 moves in the direction of travel of the cigarette rod CR and at substantially the same speed during the cutting operation.

The shaft 13 terminates in an eye 13A in which pivots a pin 23. The pin 23 is retained in the members 19 by means shown generally at 19A and 19B in FIGURE 3. The means 19A has been omitted in FIGURE 2. The axis of the pivot pin 23 is indicated at 23A in FIG- URE 3.

The knife 12 is clamped between clamp members 24 and 25 which in turn are carried by means permitting the knife 12 to be fed outwards in a gradual manner to compensate for wear. This knife feeding means is no part of the present invention and is described in more detail in US. patent application Serial No. 266,997 filed March 21, 1963, now Patent No. 3,169,431, issued February 16-, 1965. The rod which is reciprocated to operate the knife-feeding mechanism is shown at 39 within the shaft 15. The knife feeding means is carried by a structure 26 which is held between the two members 19 by means of setscrews 27. Thus, for present purposes, it can be considered that the knife 12 is carried by the members 19.

The member 20 has four lugs 28, 29, 30 and 31, which are shown dotted in FIGURE 2 and which are situated between the two members 19. Blocks 32 and 33 are held between the two members 19, and a pivot pin 34 passes through the lugs 28, the block 34 and the lug 29, and a similar pivot pin 35 passes through the lug 30, the block 32 and the lug 31, the two pivot pins 34 and 35 having a common axis 36 which passes through the axis 23A and, as can be seen in FIGURE 3, is at 4 right angles to it. It can thus be seen that the two members 19, and the blocks 32 and 33 together with the lugs 28, 29, 30 and 31, the single member 20 and the pivot pins 23, 34 and 35 constitute a Hookes joint.

The result of this construction is that during rotation the knife 12 rocks about the axis 23A to produce traversin motion for the cutting operation, and a similar return motion, and also that the knife 12 turns about the axis 36, so that during the cutting operation, and also at the position shown in FIGURE 2, which is from the cutting position, the knife 12 is at right angles to the plane of FIGURE 2..

To preserve a sharp sickle edge to the knife 12 it is necessary for it to be ground in operation. A cylindrical grinding wheel 37 is mounted for rotation about its axis 38, a pulley 39 being provided for the grinding wheel to be driven. The axis 38 passes through the axis of the shaft 13 and is in the plane of FIGURE 2 and thus lies in a plane containing the midpoint b of the sickle edge the axis of the shaft 13 and the axis of the cigarette rod CR. After passing through the cigarette rod the knife edge is deburred by a deburring wheel 40.

FIGURES 4 and 5 will now also be referred to. It will be seen that the grinding wheel 37 grinds a bevel on the sickle edge due to the inclination of its axis 38 to the plane of the knife. The whole of the sickle edge is ground, even though the knife is traversing during the grinding operation by swinging about the axes 23A because the leading edge of the sickle meets the wheel lower down than do successive points along the knife edge which meet the grinding wheel at progressively higher positions. This can be seen from FIGURES 4, 5 and 6. Three knife positions A, B and C are shown in dot and dash full, and dashed lines respectively in FIG- URES 5 and 6 and also the contact points a, b and c. The angle of the bevel changes only slightly along the knife edge because the knife swings about the axis 23A only to a very small extent during grinding. The angle the grinding wheel 38 makes relative to the plane of the knife can be adjusted about the axis XY which contains the point of contact b between the mid-point of the sickle edge and the grinding wheel 37. Such an angular adjustment is necessary when the amount of traverse of the knife is changed (by changing the angle between the shafts 13 and 15) so that different length cigarettes are cut off, because the angle through which the knife swings about the axis of 23A during the grinding operation also changes. In FIGURE 4 the grinding wheel is shown in full lines in its mean position suitable when cigarettes of 70 mm. are being cut off. When cigarettes of shorter length, such as 66 mm., are being cut off the grinding wheel 38 is tilted to the position shown in dashed lines. When lengths of 84 mm. are to be cut ofif the grinding wheel 38 is tilted to the position shown in chain dotted lines.

The grinding wheel 38 is mounted for rotation in a housing 41 which has a part circular portion 41A which has two slots 41B. Attached to the gearbox 14 is a bracket 42 which has a protruding portion 42A. The portion 42A has a slot 42B and opposite sides of the slot have each a part circular bearing surface 42C. The part circular portion 41A and the surfaces 42C have their common centre on the axis XY at the contact point b. Adjustment of the angle of the grinding wheel is made by slackening two setscrews 42D and sliding the housing 41 around to the desired position and then tightening the clamping setscrews 42D. To facilitate adjustment of the grinding wheel 37 to the correct angle a graduated disc 43 is carried by the housing 41. This disc has a spiral edge with a series of notches 43A, each one of which corresponds to the correct angle for a particular cigarette length, and is marked with that length. The correct angle is obtained when the disc 43 is turned and the appropriate notch can receive a pin 44 which is carried in plates 45 carried by the projection 42A.

In FIGURE 7 a frusto-conical wheel 50 with its axis 51 is used and its angle will be adjustable in the same manner. In the position of adjustment shown in full lines the axis 51 is parallel with the knife 12 and the vertex angle U is also the angle of the bevel ground on the knife 12. The dotted and dashed illustrations shown the wheel and the corresponding bevel angles with the wheel at different inclinations to the knife 12.

A coned grinding wheel does imply a certain amount of difference in the relative surface speed of grinding for different radii of the sickle edge and if this is thought to be detrimental by any user, the cylindrical wheel 37 is used. Alternatively the frusto-conical wheel can be inverted as shown in FIGURE 8 where it is marked 60. In this case, with a slope on its sides of 1 in 11, the surface grinding speed will be substantially constant for different points on the sickle edge, as the smaller radius part of the sickle meets a large diameter of wheel and a large radius part meets a small diameter. The wheel axis is canted, as shown, but the pivoting point is still the contact point between wheel and knife when the latter is touching the wheel on its mid-point b.

If it should happen that it is required to cut lengths of less than 66 mm. or more than 84 mm. the frusto-conical wheel may be changed for one having, respectively, a more acute vertex angle or a more obtuse angle, in order to avoid the grinding making the bevel on the knife too acute or too obtuse, as the case may be, with a consequent change in the sickle arc.

If it is desired to have a hollow ground edge, that is, one where a section of the knife displays a slight concavity at the ground part, a wheel of parabaloidal shape as shown at 70 in FIGURE may be substituted for the frusto-conical wheel, or a barrel shape as shown at 80 in FIGURE 9 may be substituted for the cylindrical wheel. This will result in a slightly different sickle are being formed but the difference is not material.

While the invention has been described with reference to the cutting of a continuous cigarette rod into separate cigarettes it will be obvious to those skilled in the art that similar considerations apply to the manufacture of filter plugs for cigarettes as the rod forming and cutting processes are similar. The invention thus relates broadly to the cutting of rod-like articles, namely cigarettes or pieces of filter plug material.

What we claim as our invention and desire to secure by Letters Patent is:

1. A grinding device for the knife of a cigarette-machine cut-off of the type described, comprising means for altering the amount of traverse of the rotatably mounted knife to cut off different cigarette lengths from a continuous rod moving in an axial direction, a grinding wheel having a surface formed by the revolution of a substantially straight line about an axis coplanar therewith, the grinding wheel being situated to be in contact with the mid-point of the sickle edge of the knife when that point is from the axis of the cigarette rod and with its axis in a plane containing said point of contact and the axis of the cigarette rod, means mounting said grinding wheel for rotation about its axis and for adjustment of its axis in said plane about the point of contact of the mid-point of the sickle edge and the grinding wheel through a range of angles relative to the plane of the knife during the grinding operation such as to grind a chamfer along the whole length of the sickle edge irrespective of the different lengths of cigarettes to be cut.

2. A grinding device as claimed in claim 1 wherein the grinding wheel is cylindrical, and at all positions of adjustment in said range of angles the axis of the grinding wheel is inclined to the plane of the knife during the grinding operation.

3. A grinding device as claimed in claim 1 wherein the grinding wheel is frusto-conical, and tapers towards the rotational axis of the knife, and the range of adjustment includes the position where the axis of the grinding wheel is parallel with the plane of the knife during the grinding operation.

4. A grinding device as claimed in claim 1 wherein the grinding wheel is frustro-conical, and tapers outwards away from the rotational axis of the knife, and at all positions of adjustment in said range of angles the axis of the grinding wheel is inclined to the planes of the knife during the grinding operation.

References Cited UNITED STATES PATENTS 512,740 1/1894 Ogle 51247 2,022,569 11/1935 Molins 51-247 2,541,615 2/1951 Ruau 51-247 2,752,741 7/ 1956 Molins 51247 HAROLD D. WHITEHEAD, Primary Examiner.

Claims (1)

1. A GRINDING DEVICE FOR THE KNIFE OF A CIGARETTE-MACHINE CUT-OFF OF THE TYPE DESCRIBED, COMPRISING MEANS FOR ALTERING THE AMOUNT OF TRAVERSE OF THE ROTATABLY MOUNTED KNIFE TO CUT OFF DIFFERENT CIGARETTE LENGTHS FROM A CONTINUOUS ROD MOVING IN AN AXIAL DIRECTION, A GRINDING WHEEL HAVING A SURFACE FORMED BY THE REVOLUTION OF A SUBSTANTIALLY STRAIGHT LINE ABOUT AN AXIS COPLANAR THEREWITH, THE GRINDING WHEEL BEING SITUATED TO BE IN CONTACT WITH THE MID-POINT OF THE SICKLE EDGE OF THE KNIFE WHEN THAT POINT IS 180* FROM THE AXIS OF THE CIGARETTE ROD AND WITH ITS AXIS IN A PLANE CONTAINING SAID POINT OF CONTACT AND THE AXIS OF THE CIGARETTE ROD, MEANS MOUNTING SAID GRINDING WHEEL FOR ROTATION ABOUT ITS AXIS AND FOR ADJUSTMENT OF ITS AXIS IN SAID PLANE ABOUT THE POINT OF CONTACT OF THE MID-POINT OF THE SICKLE EDGE AND THE GRINDING WHEEL THROUGH A RANGE OF ANGLES RELATIVE TO THE PLANE OF THE KNIFE DURING THE GRINDING OPERATION SUCH AS TO GRIND A CHAMFER ALONG THE WHOLE LENGTH OF THE SICKLE EDGE IRRESPECTIVE OF THE DIFFERENT LENGTHS OF CIGARETTES TO BE CUT.

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