Apparatus for cutting

Abstract: Apparatus for cutting web material (20) in which blade (11) and anvil cylinder (12) cooperate, the blade cylinder (11) having a slot (15) in which a blade (14) equipped bar (16) is mounted with support for the bar from the bottom of the slot (15) offset a distance circumferentially from the blade (14) such that the cutting force (c) exerted on blade (14) and the offset bar (16) supporting force result in a torque (T) on the bar (16) clamping the blade (14) securely while actual cutting is taking place, the height of the cutting blade (14) being adjustable through the use of cooperating tapered surfaces on two components of the blade supporting bar (22,23) and in which friction means are operably associated with the blade to inhibit axial assembly of the blade.

Description: This invention relates to apparatus for cutting and more particularly the mounting of cutting blades in a rotating cylinder for cutting or perforating continuous webs of paper, plastic, fabric, etc. More specifically, the invention applies to the manner in which the cutting blade is adjusted, supported, clamped, and changed. In the manufacture of many articles of paper, plastic, fabric and the like, there is a need to cut or perforate across the width of a moving web. A widely used method of doing this is to use steel rule cutting blades clamped in a slot of a rotating cylinder or roll. The blades cut against a hardened steel impression cylinder or roll. A plurality of cutting rules are mounted around the circumference of the cylinder. The blades are first clamped lightly, the cylinder rotated one revolution to seat each blade in contact with the impression cylinder, then the blades are securely clamped before cutting any paper, plastic, fabric, etc. This method works quite well and has been in common use for many years. It does have some objections, however. First, as the speed of machinery has increased, a problem developed due to the heat generated in the bearings of the blade and impression cylinders. This heating causes the frames of the machine supporting the cylinders to expand -- thus separating the centers of the cylinders and causing poor cutting for lack of sufficient contact between the cutting blade and the impression cylinder. This problem has been solved at some expense by providing heaters for the frames to maintain them at a uniform elevated temperature. A second problem is the long time it takes to install new blades. The blades are typically held by a series of clamping screws each one of which must be set to a proper torque for the first revolution of the cylinder, and then tightened for the final clamping. If the torque for the first setting is too low, the blades will not cut. If it is too high, the blades will hit too hard giving short blade life and severe wear and tear on the bearings, drive gears, etc. If the blades are extended too far out of the blade cylinder slot for the first revolution, they can be permanently bent, and thus ruined -- as a bent blade will not cut cleanly. The difficulty of setting cutting blades by this method results in many blades being set improperly requiring resetting, short blade life or poor quality cuts. Currently, the cutters/perforators suited for fast blade change are either of the type of U.S. Patents 4,848,202 or 4,920,843. The 4,848,202 patent provides for shimming under the clamping bar to adjust for inaccuracies in machining or tolerances while Patent 4,920,843 which is considered the closest prior art reference provides for operator adjustment screws for each blade to compensate for these differences in blade height. To fix the knife blade in the slot of the knife retaining cylinder, the knife blade has to be put on a support portion of a retaining ruler. The retaining ruler comprises a downwardly inclined wedge surface which cooperates with a corresponding downwardly inclined wedge surface on a tightening ruler disposed beside the retaining ruler in a slot. The disadvantage of this arrangement is that in preparation for the cutting action an additional adjustment step has to be performed by which the knife retaining cylinder is rotated relative to the counter pressure cylinder, which presses the blade downwards into the slot. A further disadvantage of this arrangement is that, for removing the blade, tools have to be used by the operator to release the wedged rulers and the blade between the retaining ruler and one side wall of the slot. Further, US-A-3,769,868 discloses a transverse cutting machine which has stationary and rotatable blade supports and blades, with the stationary blade projecting into the path of rotation of the rotating blade a distance of around 0,1 mm. One of the blades is fixed in its support and the other blade is fixed on its support against movement in the direction of the cutting force. This other blade is formed with a curved surface at one end leading into its cutting edge so that on contact with the fixed blade, it displaces or deflects in a direction normal to the direction of the cutting force against a pressurized fluid bias provided by an expansible, pressurized tube. The disadvantage of this cutting machine is that this arrangement of blades is relatively complicated, because controllable means for biasing the blade have to be provided. SUMMARY OF THE INVENTION : It is an objective of this invention to provide a cutting rule mounting that is not affected by normal blade height tolerances. Another objective is to provide a mounting that is not adversely affected by changes in cylinder center distances due to heating. Another objective is to provide a mounting that can accept non-uniform blade contact due to runout in the blade or impression cylinders. Another objective is to provide a mounting that does not require a first clamping and then a final lock up clamping operation. Another objective is to provide a mounting that permits fast changing of blades without the use of many clamping screws. Still another objective is to provide a blade mounting that does not require the high clamping forces necessary in present systems. Another objective is to provide a blade mounting that is quick and easy for the operator to make very accurately. Another objective is to provide a blade mounting that permits the operator to change blades using nominal force without special tools, withdrawal devices, etc. Another object is to provide for accurate adjustment of the blade height that is easily and quickly made by the machine operator. Still another object is to provide a restraint to prevent the blade from "walking", i.e., moving across the width of the cylinder during the course of many cutting operations. These objects and advantages are provided in the instant invention through a blade cylinder operating in conjunction with an impression cylinder, the blade roll having an axially extending slot receiving a bar means supported from the slot bottom, the bar means being equipped with generally circumferentially extending ledge means at the bottom thereof, a blade mounted on the ledge means and supporting means for the bar offset from the center of the blade resulting in both radial and circumferential forces on the blade during the actual cutting operation. In specific aspects, the blade position is maintained by spring means bearing against the bar to exert a circumferential force against the bar means during that portion of a revolution of the blade cylinder when the blade is not actually cutting. When cutting action begins, the radial downward cutting force on the bar that is counteracted by an upward radial force on the bar that is offset some distance circumferentially from the force on the blade, these offset forces resulting in a torque on the bar causing the bar to clamp the blade more securely; axial movement of the blade is inhibited by friction means operably associated with the blade; and height adjustment is achieved by providing the bar means in two parts having tapered surfaces. BRIEF DESCRIPTION OF THE DRAWINGS : FIG. 1 is an end elevational view of apparatus for practicing the invention; FIG. 2 is an enlarged fragmentary sectional view such as would be seen along the sight line 2-2 applied to FIG. 1; FIG. 3 is a perspective view of the two bars employed for height adjustment; FIG. 4 is a fragmentary longitudinal sectional view of the assembled bars of FIG. 3 such as would be seen along the sight line 4-4 applied to FIG. 3; FIG. 5 is a fragmentary top perspective view showing the assembly of elements employed for height adjustment and also featuring a register; FIG. 6 is a view similar to FIG. 5 and featuring a rack and pinion tool for advantageously adjusting the height; and FIG. 7 is a fragmentary sectional view FIG. 6. DETAILED DESCRIPTION : In FIG. 1, the numeral 10 designates generally the frame of the apparatus which rotatably supports a blade cylinder 11 and an impression cylinder 12. These are rotated by a gear train 13. The numeral 14 designates the blade carried by the blade cylinder 11. One clamping arrangement for the blade 14 in the cylinder 11 is seen in FIG. 2. A slot 15 is cut across the axial length of a rotating blade-holding or blade-carrying cylinder 11. Blade 14 is mounted between the bar 16 and one side wall 17 at ledge 18. The blade edge 19 is supported at some chosen distance above the blade cylinder 11 surface so that it just contacts impression cylinder 12 if cutting is to be through all plies or at some precise chosen distance short of impression cylinder 12 if the cutting is to be through only some of the plies. For instance, it may be desired to perforate or to cut completely through two plies 20 and 20a but not to perforate or to cut a third ply 21 immediately in contact with impression cylinder 12. Because paper, plastic, fabric plies, or the like are commonly 0,025 mm to 0,127 mm (.001 to .005 inch) in thickness, it can be seen that the height adjustment of blade 14 must be precise. The amount of movement and the firmness of the resilient pad 30 are selected to give sufficient cutting force C for the materials being cut. For paper plies of 0,051 mm to 0,127 mm (.002 to .005) inch thickness a cutting force of about 150 lbs. per inch of length of blade 14 is used. The bar 16 is pressed against the blade 14 by springs 28 clamping the blade between slot wall 17 and part 22. This clamping force is relatively small and is used to hold the blade when cutting is not actually taking place. During actual cutting, the cutting force C on the blade causes a torque T on part 22 clamping blade 14 much more securely. More particularly, the cutting force C results in a radially inward force on the ledge 18 tending to pivot part 22 around the point 29 (see FIG. 2). This causes the base 30 to move to the right in FIG. 2 to take up the clearance 31 -- thus resulting in torque T. In practice a small clearance 31 is desirable in order to easily pivot part 22 without binding when changing blades 14. The invention finds application both with a resilient base 30 or a rigid base 30. When die cutting (as illustrated in FIG. 2) the base 30 is advantageously rigid so as to maintain the tip 19 of the blade 14 in predetermined position. This also applies to cutting where the tip of the blade 14 comes just into "kissing" contact with the surface of the impression or anvil roll 21. On the other hand, where there is interference between the blade and the impression cylinder, the interference is taken up by virtue of having a resilient base 30. When it is desired to cut completely through only ply 20 or through two plies 20 and 20a but not through ply 21 which is immediately in contact with impression cylinder 12, the blade height is adjusted upwards until only the one or two plies are cut as desired. A rigid pad 30 is used, so there is negligible downward movement of blade 14 at the time of cutting but the cutting force C is essentially of the same magnitude and creates the blade clamping torque T through there is negligible actual movement of bar 16. To achieve precise adjustment, the bar 16 of this invention is made of two parts 22 and 23 which have tapered surfaces 24 and 25 in engagement. The U-shaped part 22 which supports the blade 14 ordinarily is restrained from movement across the length (i.e., the axial dimension) of the slot 15 by bearers, viz., discs affixed to the ends of roll 11 or other means well known in the art. The part 23 has means to be moved along the length of slot 15 thus raising and lowering the height of blade 14 by means of the inclined surfaces 24 and 25. The means for indicating the amount of adjustment of blade 14 upwards or downwards can be very simple and accurate because a large movement of part 23 in relation to part 22 results in a small adjustment of blade height. For example, a reference graduation 27 is positioned on a part 22 (see FIG. 5). Cooperating graduation marks 26 are provided on part 23 to indicate a convenient change in blade height, advantageously 0,025 mm (0.001 inch) when part 23 is moved the distance of one graduation. The graduations are spaced much further apart than the adjustment made due to the ratio of change in blade height to movement of part 22 resulting from the angle of incline used on surfaced 24 and 25. It may be advantageous in certain instances to interchange the graduations on the parts 22 and 23 still providing the same result and indication. FIG. 6 shows an arrangement using a rack and pinion that is especially advantageous for the machine operator. A form of a T-handled key is used. The key has pinion gear portion 33 and a cylindrical end portion 35 shown in FIG. 7. In use the key is inserted through hole 34 in part 22 with the cylindrical end portion 35 in hole 36 in part 23 and pinion gear portion 33 engaged in rack 32. By rotation of the pinion 33 in one direction or the other part 23 is caused to move in relation to part 22 thus causing the blade height to be raised or lowered accordingly. Height adjustment is advantageous in normal cutting and perforating operations where the cutting is through all plies and which thereby enhances blade life and smooth, quiet running. This adjustment becomes especially advantageous when the cutting is to be through some but not all of multiple plies passing through the cutting station or roll nip simultaneously. For most operations, I prefer to employ a base 30 that is resilient and, in fact, may be a spring. The base 30 supports the bar such that the cutting edge 19 of the blade 14 is a few thousandths of an inch above the radius of cutting so that the blade and bar will be pressed downward into slot during the actual cutting operation. The downward movement of the bar 14 compresses base 30 developing a force C sufficient to cut the material being processed. The cutting force also creates a torque T that securely clamps the blade 14 against slot wall 17 during the actual cutting operation. During the portion of the revolution of the blade cylinder 11 when cutting is not actually taking place, there is no torque T to clamp the blade against slot wall so springs 28 are provided for this purpose sufficient to prevent the blade from falling out. It is desirable that the clamping force provided by springs 28 be modest so the operator finds it easy to move the bar to release the blade when installing or removing the blade. Excessive spring forces can result in deformation or damage to the bar when applying sufficient force to release the blade. In prior art practice, the bar clamps the blade by friction between the adjacent slot side wall and the clamping bar. This clamping force must be substantially higher than the radial cutting force. Thus, when using steel for the blade, slot wall and clamp bar and a radial cutting force of 26,3 N/mm (150 lbs. per inch) of blade length, the clamping force is of at least 35 N/mm (200 lbs. per inch) and in actual practice much more than that in order to insure adequate clamping. The circumferential force on the blade due to the thickness of the material to be cut and the projection of the blade over cutting radius is about 1,75 N/mm (10 lbs. per inch) of width. Thus, when only the circumferential force must be met rather than the forces required for rigid clamping, it becomes possible for the machine operator to easily manipulate the bar in order to change the blade. One method to remove and install blades can consist of providing the bar 16 with holes in the top of the bar to accept a pin punch or the like for the operator to use as a lever to open the gap and release the blade. Therefore, the blades can be changed much more quickly than when using the series of clamping screws as are now commonly used. In order to restrain the blade 14 from moving across the width of the slot 15 during repeated cutting actions, I provide an inhibiting member which may take a variety of forms for frictional engagement with the blade. For example, a friction surface on the bar can engage one side of the blade 14. The high friction surface has particles that contact only a relatively small area and are sharp enough to actually bite into the blade under the action of torque. The cutting blades are usually made of steel hardened to 40 Rockwell B to about 55 Rockwell C to ensure long life. The friction surface can be an abrasive material such as aluminum oxide, silicon carbide, or the like, typically ranging from 36 to 240 in grit size. Also employed to advantage are other high friction materials such as plasma coated tungsten carbide. A friction surface can be located on the slot wall 17 with equal effectiveness. In actual practice, the invention will be used with cylinders in the field which are difficult to apply the friction surface to. Although the friction surface can be applied to the bar with less difficulty, it is sometimes advantageous to have the friction surface on an easily replaceable, inexpensive member. In such a case, the friction surface can be located on a member intermediate the blade 14 and the bar 16 or a member intermediate the blade 14 and the cylinder wall 17. A particularly advantageous intermediate member is an element constructed of approximately 0,25 mm (0.010") thick spring steel coated with the friction surface as mentioned above and having opposed generally planar surfaces. The friction coating can be on both surfaces of the intermediate member in which case no additional axial inhibiting means is required for the intermediate member. Also, it is advantageous to adhere the intermediate member to the adjacent cylinder or bar wall. The coating may be only on one surface of the intermediate member and the member itself restrained against axial movement by the usual means at the ends of the slot such as bearers or bar retainers well known in the art which so limit the bar or other holder means for the blade. It will be appreciated that the blades are typically shorter than the slot, hence the need for inhibiting axial movement. As mentioned previously, the pad 30 may not only be resilient but can also take the form of a spring. For instance, the pad 30 made of polyurethane would function effectively as a spring on bar 16. The spring force required is in the range of 17,5 N/mm to 88 N/mm (100 lbs. to 500 lbs. per inch) of length of the cutting blade. A force F of 26,3 N/mm (150 lbs. per inch) is typical when cutting bond papers papers of 0,051 mm to 0,127 mm (.002 to .005 inch) thickness. The blade 14 is supported so that the cutting edge 19 will be moved downward against the force of springs when it contacts the anvil cylinder 12. It is desirable that the amount of downward movement be minimal but sufficient to absorb the errors due to manufacturing tolerances in the height of the cutting rules, changes in center distance due to heating of the frames, run out of the cylinders, etc. A convenient amount for this dimension is about 0,254 mm (.010 inch) when cutting paper and plastic materials of 0,051 mm to 0,127 mm (.002 to .005 inch) thickness. This amount can be chosen to meet the specific demands of the installation.

Claims: Apparatus for cutting web material comprising a frame (10), a blade roll (11) rotatably mounted on said frame (10), an impression roll (12) rotatably mounted on said frame (10) adjacent said blade roll (11), said blade roll (11) being equipped with an axially-extending slot (15) having a radially inward generally circumferentially-extending bottom wall and spaced generally radially-extending side walls (17), blade-supporting bar means (16) mounted in said slot (15) and having a bottom wall adjacent said slot bottom wall, said bar means (16) being equipped with generally circumferentially-extending integral ledge means (18) adjacent said bar bottom wall, and a blade (14) mounted on said ledge means (18) and interposed between said bar means (16) and one sidewall of said slot, characterized by an adjustable support (23) for supporting said bar means (16) through co-acting surfaces (24,25) and for adjusting the height of the blade (14) relative to the impression roll (12), cutting action developing a radially inward force on said blade (14) and said ledge means (18) which tends to pivot said bar means (16) about a point (29) adjacent the bottom of said support (23), the circumferential spacing of said ledge means (18) from said point (29) causing a torque to be generated on said bar means resulting in a clamping force on said blade (14). The apparatus of claim 1 in which said bar means includes axially extending generally chordally disposed ramp means (22,23) for adjusting the blade (14) height relative to the impression roll (12). The apparatus of claim 2 in which said bar means includes two component parts having engaged tapered surface providing said ramp means. The apparatus of claim 1 in which spring means are operatively associated with said blade roll (11) bearing against said bar means for exerting a generally circumferential force against said bar means to clamp said blade (14). The apparatus of claim 4 in which a rigid base (30) is provided in said slot (15) to maintain the tip of said blade (14) at a predetermined height. The apparatus of claim 4 in which a resilient base (30) is provided in said slot (15) to permit exertion of a radial force against said bar means. The apparatus of claim 1 in which spring means (28,30) are operatively associated with said blade roll bearing against said bar (16) for exerting both generally radial and circumferential forces against said bar (16) to clamp said blade (14) while providing a radially resilient mounting for said blade (14). The apparatus of claim 1 in which friction means are operably associated with said blade (14) for inhibiting axial movement of said blade (14).

Inventors: STEIDINGER DONALD J, STEIDINGER, DONALD J.
Applicants: STEIDINGER DONALD J, STEIDINGER, DONALD J.
Application year: 1992
Main classification: B26D7
IPC codes: B26D7