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| United States Patent |
3,552,251 |
|
Neff
, et al.
|
January 5, 1971
|
ROTARY SLIT CUTTER
Abstract
The slit cutter comprises a rotary cylinder carrying knives, and a
stationary fixed knife the cutting edge of which is ground away or
relieved except at those parts along its length where the web is to be
slit. All of the rotary knives cooperate with the resulting intermittent
edge of the single fixed knife. The knives are preferably helically
mounted on the cylinder, and the cylinder and fixed knife are skewed at an
angle such that the resulting slits are perpendicular to the long axis of
the web. There is a metering roll ahead of the knives, and a pull roll
following the knives, both driven accurately at web speed, and serving to
maintain control of the web independently of the knives, which are
preferably but not necessarily driven at web speed. Means is provided to
properly register the slits with the printing on the web.
| Inventors: |
Neff; Herbert E. (Short Hills, NJ), Chestnut; William R. (West Caldwell, NJ) |
| Assignee: |
Bobst Champlain, Inc.
(Roseland,
NJ)
|
| Appl. No.:
|
04/780,862 |
| Filed:
|
December 3, 1968 |
| Current U.S. Class: |
83/299 ; 83/336; 83/339; 83/342; 83/349 |
| Current International Class: |
B26F 1/00 (20060101); B26D 5/32 (20060101); B26F 1/20 (20060101); B26D 5/20 (20060101); B23d 025/02 () |
| Field of Search: |
83/336,339,342,349,299
|
References Cited [Referenced By]
U.S. Patent Documents
Primary Examiner: Lawson; William S.
Claims
We claim:
1. A rotary slit cutter for operating on a continuously moving web to produce a line of short slits extending transversely of the web, said cutter comprising a rotary knife cylinder
having a plurality of knives substantially helically mounted thereon, each of said knives having a continuous cutting edge, a stationary or fixed knife having an intermittent cutting edge disposed in the path of the cutting edges of said rotary knives,
said cylinder and fixed knife being mounted relative to the transverse axis of said web at an angle skewed an amount such that the resulting slits are perpendicular to the long axis of the web.
2. A rotary slit cutter for operating on a continuously moving, previously printed web to produce a line of short slits extending transversely of the web, said cutter comprising a rotary knife cylinder carrying a rotary knife having a cutting
edge, a stationary or fixed knife having its edge disposed at the path of the said rotary cutting edge, the edge of one of said knives being cut away or relieved except at those parts along its length where the web is to be slit, means for sensing said
print on said web and means operatively connected to said sensing means for momentarily varying the speed of said web relative to said rotary knife edges so as to afford registration of said slits with the printing on said web.
3. A rotary slit cutter as defined in claim 2, wherein the means for momentarily varying the speed of said web relative to said rotary knife edges comprises running register means operatively connected to said drive means for momentarily varying
the rotational speed of said rotary knife cylinder.
4. A rotary slit cutter as defined in claim 2, in which said means for varying the speed of said web relative to said rotary knife edges comprises an adjustable compensator roll ahead of said knives adapted to momentarily vary the rate of feed
of said web past said knives.
5. A rotary slit cutter as defined in claim 1 in which the skew angle of the knife cylinder and fixed knife is adjustable, and in which there are means for effectuating a gradual controlled adjustment of the skew angle, and additional means for
locking the said knife cylinder and fixed knife against movement from the desired angular position.
6. A rotary slit cutter as defined in claim 1, in which the rotary knife cylinder has a shaft one end of which is driven by appropriate drive means, and in which there is a swivel joint between the driven end of the shaft and the said gearing in
order to accommodate the skew angle of the knife cylinder.
7. A rotary slit cutter as defined in claim 6, in which there is a metering roll and a nip roll cooperating therewith for feeding the web to the knives at a desired web speed, and in which there is a pull roll and a nip roll cooperating
therewith for pulling the web from the knives at the same desired web speed, said metering and pull rolls being geared to said rotary knife cylinder for operation in unison.
8. A rotary slit cutter as defined in claim 7 for operating on a previously printed web, in which a running register means is provided in the drive means of the rotary knife cylinder in order to afford registration of the slits with the printing
on the web.
9. A rotary slit cutter as defined in claim 7 for operating on a previously printed web, in which there is a compensator roll ahead of the knives to provide registration adjustment for correction of the registration of the slits with the
printing on the web.
10. A rotary slit cutter as defined in claim 1, in which the rotary knife is approximately helically mounted on the knife cylinder to produce a shear cut, and in which the cylinder and fixed knife are mounted at an angle skewed an amount such
that the resulting slits are perpendicular to the long axis of the web.
11. A rotary slit cutter as defined in claim 10, in which the skew angle of the knife cylinder axis and the fixed knife is adjustable, and in which there are means for effectuating a gradual controlled adjustment of the skew angle, and
additional means for locking the said knife cylinder and fixed knife against movement from the desired angular position.
12. A rotary slit cutter as defined in claim 10, in which the rotary knife cylinder has a shaft one end of which is driven by appropriate drive means and in which there is a swivel joint between the driven end of the shaft and the said gearing
in order to accommodate the skew angle of the knife cylinder.
Description
Cigarette manufacturers employ cigarette pack filling machines with a continuous printed web feed into the machine for the
wrappers or so-called "labels" for a "soft pack". The web has been notched to facilitate feeding and handling in the pack filling machine, the notches being cut in proper register with the printing on the web. The triangular notches have been made with
a reciprocating punch utilizing male and female type dies, requiring dwell of the web, or on a swinging type punch which moves with the web during the punch cycle. Each of the approaches have definite speed limitations.
More recently short slits have been used instead of notches. These again have been made by use of a reciprocating type punch with dwell of the web, or a swinging punch. Here again, speed and accuracy are limited because of the inertia of the
reciprocating members. Similar remark applies to a looper punch such as that shown in U.S. patent to Fischer and Neff, No. 3,085,457 , issued Apr. 16, 1963 and entitled "High Speed Web Stopping Mechanism".
A rotary type cutter will work at higher speeds, and has been used for cutting a sheet all the way across. Such a cutter may be a double rotary cutter using two knife cylinders with overlapping blades. A rotary cutter also has been used
cooperating with a single stationary blade, the blades passing one another so closely as to cut a web across its width even when the rotary knife matches web speed. For a shearing cut, the rotary blades are made helical, and the rotary and fixed blades
then are disposed at an angle that is skewed in proper relation to the web travel to obtain a cut which is square across the web. Double rotary cutters provide high operating speed, but have not been thought feasible for short slits. In a practical
case there may be say nine knives around a knife cylinder, and perfect meshing of the knifes is needed for all nine blades. This is very difficult even with continuous blades, and multiple short blades easily get out of mesh thereby impairing their
life.
To overcome the foregoing difficulties and to fulfill the foregoing objectives, we provide a rotary slit cutter comprising a rotary cylinder carrying a knife, and a fixed knife with its edge disposed at the line of coincidence of the paths of the
rotary cutting edge and the web. The cutting edge of one of the knives is cut away or relieved except at those parts along its length where the web is to be slit. In preferred form, the rotary cylinder has a plurality of like knives spaced around the
cylinder, and these knives all have continuous cutting edges. There is a single fixed knife the edge of which is relieved to provide an intermittent cutting edge, and all of the rotary knives cooperate with the relieved or intermittent edge of the
single fixed knife. The rotary knives are preferably slightly helically mounted on the cylinder, and the fixed knife and the cylinder are skewed at an angle such that the resulting slits are perpendicular to the long axis of the web.
The knife cylinder and the fixed knife have a skew angle which is adjustable, and means are provided for effectuating a gradual controlled adjustment which is equal for both the cylinder and the fixed knife. The skew angle is adjusted whenever
the length of the cut sheet is changed. The rotary knife cylinder is driven through appropriate gear means, and there is a swivel joint between the shaft and the gearing in order to accommodate the desired adjustment of the skew angle.
We preferably provide a metering roll ahead of the knives, and a pull roll following the knives, these being driven accurately at desired web speed, and maintaining control of the web independently of and without reliance on the knives, the
latter, however, also preferably but not necessarily being driven at web speed.
It is important to properly register the slits with the printing on the web, and for this purpose either a running register or a compensator roll may be used, in conjunction with electric eye scanning means to maintain the desired register. If
the web has been preprinted and is being fed from a roll, a so-called "feathering drive" preferably is employed.
The foregoing and additional features are described in the following specification, which is accompanied by drawings in which:
FIG. 1 shows a piece of printed web provided with lines of short slits;
FIG. 2 is a simplified plan view of a rotary slit cutter embodying features of our invention;
FIG. 3 is a simplified elevational view of the rotary slit cutter;
FIG. 4 is a fragmentary section showing the rotary and fixed knives;
FIG. 5 shows how the cutting edge of the fixed knife is relieved or cut away to make short slits;
FIG. 6 is a schematic diagram showing the application of electric eye scanning means for register control; and
FIG. 7 is a schematic view showing the use of a compensator roll instead of a running register.
Referring to the drawing and more particularly to FIG. 1, sheet 12 is assumed to have been printed to act as the wrapper or so-called label of
soft cigarette packs. In the particular case shown each wrapper is 7 inches wide, and sheet or web 12 has a width of 44 inches, making up six wrappers across, with a one-inch margin at each edge for scrap. Each line of slits has seven slits as shown,
across the web.
The "repeat length" for the printing is here shown to be 36 inches, corresponding to nine wrappers each 4 inches along the web, and the lines of slits are therefore spaced four inches apart. This dimension will vary with the cigarette length.
The invention, of course, is applicable to a slit web used for any other purpose.
Referring now to FIGS. 2 and 3 of the drawing, the rotary slit cutter comprises a rotary knife cylinder 14 carrying a plurality of rotary knives 16, and there is a single fixed or stationary knife 18 disposed beneath the web, the latter being
shown in FIG. 3 by the broken line 20. The cylinder 14 (FIG. 2) and fixed knife 18 are longer than the width of the web, indicated in FIG. 2 by broken lines 20.
Both the rotary and fixed knives are located at the web line, and are brought so close together as to contact and thereby have a cutting action on the web even though the rotary knives are turned at web speed. In the particular case shown the
cylinder 14 has nine knives 16, equally spaced about the cylinder, the angular separation being 40.degree., and the linear separation at the web being four inches. The edges of the knives are disposed on a circle having a circumference of 36 inches, or
a diameter of 36 /.pi. inches. If the printing web is coming directly from a print line, such as a multicolor gravure press line, the gravure cylinders would conveniently have the same diameter, so that the parts may be turned in one to one ratio by a
common line shaft or main drive shaft 24 (FIGS. 2 and 6) running lengthwise of the press line.
For a shear cut, the knives 16 are preferably disposed at an angle or helically on the knife cylinder 14. The angle is small, say one degree, and is exaggerated in the drawing. The cylinder is disposed with its shaft at an angle or skewed, as
will be seen from inspection of the shaft 22. The fixed knife 18 is skewed at the same angle, say one degree, as the cylinder axis. The angle is opposite the helix angle. They seem alike in FIG. 2 because in FIG. 2 the rotary knife is shown a at the
top rather than at the bottom of the cylinder where it cuts. With the web moving in the direction of the arrow, the resulting cut may be made perpendicular to the long axis of the web.
The rotary knife cylinder is driven by main drive shaft 24 through gearing located at 26. This is preferably connected to shaft 22 through a swivel joint or coupling 28. This may be a universal joint, in which case two such joints may be used
in series, so as to maintain a uniform velocity. However, other connections are preferably used such as the Sier-Bath flexible gear couplings made by Sier-Bath Gear Company, Inc. of North Bergen, New Jersey, U.S.A.
The skew angle is conveniently adjusted by appropriate means. In FIG. 3 it will be seen that the bearing block 30 for cylinder 14 also carries the fixed knife 18. Referring to FIGS. 2 and 3 the adjustment may be controlled and made gradually by
means of a threaded link 32 connected to bearing block 30 at an ear 34. The link may be moved and subsequently locked by nuts 36 and 38 on each side of an ear 40 fixed on the frame of the machine. For this adjustment, the bolts 42 and 43 holding the
common base 44 of bearing supports 30 are preliminarily loosened, and again tightened after the adjustment has been made. Base 44 has a slot 45 to permit the skew angle. Bolt 43 is located in a hole beneath flexible joint 28 and acts as a pivot. In
practice there would be multiple bolts at each end, and the pivot would be an accurate pilot rather than a bolt received in a bolt hole.
Referring now to FIG. 4, each rotary knife 16 is secured to a holder 50 by screws 52. Holder 50 in turn is secured to cylinder 14 by means of appropriate screws 54. The screws 54 in practice include screws which force the blade outward, as well
as others which force the blade inward, thereby affording very accurate adjustment of the critical cutting radius of the blades.
The fixed knife 18 is secured by screws 56, and referring to FIG. 5, it will be seen that screws 56 pass through slots 58 which permit vertical adjustment of the fixed knife 18. This adjustment may be controlled and made gradual, as by means of
adjusting screws 60 (FIG. 4). FIG. 5 also shows how the cutting edge of the fixed knife 18 is relieved or cut away as shown at 62, for most of its length, leaving only the seven short cutting edges 64. In the present case these are 1/2inch long,
corresponding to the desired slit length of 1/2inch.
The machine preferably includes a metering roll 70 (FIG. 3) with a cooperating nip roll 72 ahead of the knives, and a pull roll 74 with a cooperating nip roll 76 following the knives. These rolls 70 and 74 both are driven at the desired web
speed, and they are geared to and driven by the main drive shaft 24, as shown in FIG. 2 by the gear boxes 78 and 80. In FIG. 2 the nip rolls have been omitted to better show the metering roll 70 and pull roll 74. These provide accurate control of the
web independently of the knives, although the latter also preferably move at web speed.
The slits must be located in proper registration with the printing on the web, and for this purpose the gearing in box 26 (FIG. 2) differs from the gearing at 78 and 80 in including running register means symbolized at 27. This may be of the
worm and gear type with the worm slidable axially for a change of say 45.degree. at shaft 22, or it may be of the planetary or differential gear 360.degree. type. In either case a rotative correction may be fed to the knife shaft 22.
Referring to FIG. 6, line shaft 24 drives metering roll 70 through gearing at 78, and drives pull roll 74 through gearing at 80. The rotary knife cylinder 14 is driven through gearing at 26 which includes a running register symbolized at 27.
Some corrective motion may be fed into shaft 22 by means of a correction motor M. This may be controlled by conventional means, including an electric eye scanner 82 which scans the web 20 at a point near the knife cylinder 14. A pulse signal from
scanner 82 is compared with a pulse signal from a so-called "phase micrometer" 84 which is secured to and turns with the shaft 22 of knife cylinder 14. The signals are compared in suitable circuitry often referred to as a "computer" shown at 86, and a
correction signal is sent on cable 88 to the correction motor M.
The scanner, phase micrometer and circuitry in the computer may be of the type sold by the Registron Division of Bobst-Champlain, Inc. located at Roseland, New Jersey, as their Model R500 "Registron".
If desired the registration of slit to print may be maintained by means of a compensator roll instead of a running register, and such an arrangement is schematically shown in FIG. 7, which is generally the same as FIG. 3 except that the web 12 is
fed downward and then upward around a compensator roll 90. This may be moved up or down by means of vertically slidable bearings 92 at both ends operated by vertical screws 94 at both ends turns turned through gearing at 96 by a correction motor M'. The
control circuitry may be exactly like that shown in FIG. 6, except that the running register 27 in FIG. 6 is eliminated, and the correction motor M' is then used to raise or lower the compensator roll 90 as shown in FIG. 7, in which the motor M'
corresponds to the motor M in FIG. 6.
When the web is accurately controlled by metering and pull rolls on each side of the rotary knife as here shown, there is some leeway in the knife travel relative to the web travel. With a 36" repeat length as here shown, the effective knife
cylinder circumference should be 36" but may be somewhat more or somewhat less without spoiling the operation. This is so because the rotary knife can slide on the web somewhat without cutting the web except at the instant when the knife and web are at
the fixed knife. This possibility is a convenience in that some change in repeat length may be accommodated without necessarily requiring a new knife cylinder. In the case of cigarette packs, the many different cigarette lengths require correspondingly
different repeat lengths for the pack. This may be accommodated by using different knife cylinders, but considerable change, say 10 percent, may be accommodated even when using a single knife cylinder.
As so far described the printed web is assumed to be coming from a printer, such as a multicolor gravure printing line. However, the web may be preprinted and rolled, the roll subsequently being fed directly to the present slit cutter. In such
ea case the rate of feed of the metering and pull rolls should preferably be variable to accommodate a change in repeat length of the preprinted web. This change may be slight but it is cumulative. In working with a preprinted web a so-called
"feathering drive" may be used for the metering rolls, such as the drive disclosed in U.S. Pat. to Haskin et al. 2,812,938 issued Nov. 12, 1957 and entitled "Registering Drive for a Web". This adjustment employs an electric eye scanner and phase
micrometer, all as is fully described in the patent, and the frequency and direction of the adjustment of the rotary knife cylinder is monitered and used to adjust the speed of the metering roll.
Thus when using a preprinted web, the same electric eye scanner and phase micrometer that are used to obtain proper slit to print registration also serve to activate the circuitry of the Haskin feathering drive. For this a "Registron" type C370
would be used.
It will be understood that although it is greatly preferable to relieve the edge of the fixed knife, it is also possible to retain a full length cutting edge on the fixed knife, and to instead relieve the rotary knives to cut only the desired
short slits.
this knives are helically mounted in the knife cylinder to cause the cuts to be produced over a small interval of time rather than instantaneously - in other words to make a shearing cut. This, however, necessitates skewing the entire cylinder
and fixed knife in order to obtain a cut perpendicular to the axis of the web despite the helical mounting of the rotary knives, but the angle involved is very small, say one degree. The skewing angle is dependent upon the feed up and helix angle of the
knife.
The use of metering and pull rolls not only controls the web but minimizes wrinkling and tearing of the paper during cutting.
The slitter may be used following a last gravure color print station, and if located very close to that station the metering roll 70 may be eliminated.
It is believed that the construction and operation, as well as the advantages of our improved rotary slit cutter, will be apparent from the foregoing detailed description. The device may be run at high speed and is substantially as simple as
though being used for full cutoff of the web. Instead, slits are obtained by relieving or cutting away the edge of only a single knife blade, this being a fixed blade. A change in slit length, or slit spacing across the web, requires changing only the
single fixed blade. Adjustment for proper cutting action may be made at each of the rotary blades. The apparatus will work at high speed, say 800 ft. per minute.
It will be understood that while we have shown and described the invention in a preferred form, changes may be made without departing from the scope of the invention.
* * * * *
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