Knife assembly for rotary cutting system

Abstract: A knife holder assembly (4) for a rotary cutting machine includes a holder (12) with a top portion (40) and side member (16-19) with a body portion and an extender. The extender is adapted to extend through the side portion opening and has a backing portion at its end. The body portion has an indention (51-54) with a tapered sidewall for allowing a fastener to be inserted through the top portion opening and contact the tapered sidewall thereby moving the adjusting member in a direction away from the side portion to clamp an inserted knife between the backing portion and the side portion.

Description: The invention relates generally to rotary cutters for cutting web or sheet material, and more particularly to a knife holder apparatus which may be attached to a knife cylinder and employed with an associated anvil cylinder to transversely cut or score a moving web or sheet. It is conventional practice to use a rotary cutter to transversely cut web material received from a printing press. In general, rotary cutters have an anvil cylinder and a knife cylinder which are rotatable in timed relation. One or more knife holders, which hold the cutting knives are attached to the knife cylinder. The knife and anvil cylinders normally rotate at the same speed and the moving paper or web material is transversely cut or scored as the cutting knife moves into and out of engagement with the anvil surface. The cutting knives may be spaced apart to create the desired cut. In the conventional rotary cutter, knife replacement is a time-consuming operation. Reducing this replacement operation has become even more important with the increased use of recycled paper and its negative effect on the life of the cutting knife. To reduce down time due to blade replacement, unitary epoxy knife holder and blade assemblies 112, for example, as shown in FIG. 14 have been employed. Replacement of a worn cutting knife, however, requires that the entire assembly be removed from the knife cylinder, which requires stripping away the cushioning and rubber material which is placed over the knife cylinder and portions of the holder. The installer must then realign and remount the replacement holder on the knife cylinder. This problem is partially avoided by use of a knife holder assembly as shown in FIG. 15. This knife holder assembly includes a metal holder 116 and a backing member 110, which locks a cutting rule 114 to the holder 116 with holding screws 118. Although this knife holder assembly does not require the complete removal of the holder 116 from the knife cylinder, it does require some of the cushioning material to be stripped back because the release screws 118 are located on the side of the holder. This requires the person changing the cutting rule 114 to loosen the holding screws 118 from the side of the holder, which is both awkward and time consuming. It would be desirable to have a knife holder assembly that would allow the user to quickly and efficiently remove the worn cutting knife and replace it without removing the holder from the knife cylinder. It would further be desirable to provide a knife holder assembly that would aid in relieving some of the wear on the knife blade. With regard to apparatus claims 1 and 16: US 4,020,724 A represents the closest state of the art and discloses a knife holder apparatus for a rotary cutter comprising: a holder including a top portion and a side portion, the top portion including at least one opening formed therethrough; the side portion including at least one opening formed therethrough; at least one adjusting member including at least one body portion (nut 39), a backing portion (strip portion 40) and an extender (screw-type fastener 34), said extender adapted to extend through said at least one side portion opening, said extender having the backing portion (strip portion 40) at its outer end; whereby the backing portion can be moved away from the side portion to release the knife. With regard to method claim 23: US 4,020,724 A represents the closest state of the art and discloses a method of operating a knife holder in a rotary cutter comprising: inserting a knife between a side portion of a holder and a backing portion of an adjusting member; and clamping the knife between the side portion and the backing portion. The invention provides a knife holder apparatus as set out in claims 1 and 16, and method of operating a knife holder in a rotary cutter as set out in claim 23. This design allows the operator to replace the knife by simply loosening or removing the fastener or fasteners from the top portion of the holder. This eliminates the need to pull back or remove the cushioning material to get at side mounted fasteners or screws and thereby reduces downtime. These and other features and advantages of the present invention will become apparent to those skilled in the art upon review of the following detailed description of the presently preferred embodiments of the invention taken in conjunction with the accompanying drawings. FIG. 1 is a schematic view of a rotary cutter with knife holders mounted on the knife cylinder. FIG. 2 is a perspective view of a rotary cutter showing embodiments of the knife holders mounted on the knife cylinder. FIG. 3 is a sectional view of embodiments of the knife holders mounted on the knife cylinder. FIG. 4 is an exploded perspective view of a single knife embodiment of the invention. FIG. 5 is a perspective view of the embodiment of FIG. 4 in the closed position. FIG. 6 is a sectional view of the knife holder assembly taken through line 6-6 of FIG. 5. FIG. 7 is a side view of a first side portion of the holder embodiment. FIG. 8 is a bottom view of the holder embodiment. FIG. 9 is a side view of a second side portion of the holder embodiment. FIG. 10 is an exploded perspective view of a double knife embodiment of the invention. FIG. 11 is a perspective view of the embodiment of FIG. 10 in the closed position. FIG. 12 is a sectional view of the knife holder assembly taken through line 12-12 of FIG. 11. FIG. 13 is a perspective view of an urethane strip for placing on the sides of the knife. FIG. 14 is a perspective view of an existing epoxy knife holder assembly. FIG. 15 is a perspective area of an exiting knife holder assembly with side mounted screws. Referring to FIG. 1, there is shown a schematic diagram of a rotary cutter having a knife cylinder 1, and anvil cylinder 2. The web material 3 is shown passing between the nip formed between the two cylinders. A single knife embodiment 140 of the knife holder assembly 4 and a double knife embodiment 150 are shown attached to the knife cylinder 1. FIG. 2, further shows a single knife embodiment 140 mounted on the knife cylinder 1. The knife holder assembly 4 is preferably sized for use on a discrete section of the knife cylinder. Alternatively, the knife holder may be sized to cover greater portions of the knife cylinder 1, and numerous individual knife holders may be mounted on the knife cylinder. The rubber cushioning 6 is also shown which facilitates the driving of the web through the cylinders and acts to keep the web taut while it is cut. The knife cylinder has a plurality of receiving holes 8, which are preferably threaded holes, positioned in a uniform matrix or array about its outer surface. FIG. 3 shows a single-knife embodiment 140 and double-knife embodiment 150 of the knife holder mounted on the knife cylinder 1. A long screw 7 (shown partially in phantom) is screwed into one of the threaded holes 8 to secure the holder to the knife cylinder 1. Referring to FIGS. 4 and 5, an exploded perspective view, and a closed view of the single-knife embodiment 140, respectively, is shown. The knife holder assembly includes a holder 12, adjusting members (including body portions or adjusting bars 121-124, extenders or peg members 22-25 and backing portion or bar 14), fasteners or locking screws 18-21, and cutting rule or knife 26. The holder 12 is preferably made of a 11.1mm x 44.5mm (7/16 x 1¾ inch) steel channel member having a 141.5mm (5.570 inch) length. The holder has a first set 27-30 and a second set 31-34 of four openings bored through its top portion 40. These openings are preferably 7.9mm (5/16 inch) diameter threaded screw holes to receive the locking screws 18-21, which are preferably 5/16-24 x ⅜ LG. set screws. The screws 18-21 are designed to be interchangeable in any of the openings in the first or second set of openings. The top portion 40 of the holder 12 also has attachment slots 35-39 for allowing the holder 12 to be positioned upon or fastened to a knife cylinder 1, as shown in FIG. 3. Referring to FIG. 8, a bottom view of the top portion 40 of the holder 12 is shown. The slots 35-39 preferably have an inner opening with a 4.7mm (0.187 inch) width and an outer opening with a 11.1mm (0.436 inch) width. The slot-shaped indentions 51-54 which are aligned with the first and second set of openings are preferably 4.8mm (3/16 inch) diameter and 1.0mm (0.040 inches) deep and allow the shaft portion 74 of the peg members 22-25 to slide more easily. Referring to FIG. 7 is a side view of the first side portion 70 is shown. The first side portion 70 has a length of preferably the same as the length of the holder 12 of 141.5mm (5.570 inches) and a width of 11.1mm (0.437 inches). The first side portion openings 65-68 are centred at 7.3mm (0.287 inches) from the top edge of the first side portion 70 and are spaced 28.3mm (1.1147 inches) from their centres. Referring to FIGS. 4 and 6, the first side portion 70 has an outer face 60 which is preferably angled 7° degrees from the vertical to position the knife 26 for optimum cutting on knife cylinders with diameters ranging between 588 and 1225mm (24 and 50 inches). The backing bar 14, shown in FIG. 4, preferably has a length of 141.5mm (5.570 inches), a width of 9.5mm (0.375 inches) and a depth of 3.2mm (0.125 inch). Backing bar openings 61-64 are aligned with the first side portion openings 65-68. As shown in FIG. 6, the backing bar openings 61-64 have recessed area 85 surrounding the openings, and both the opening and recessed area are angled at 7° degrees to allow the backing bar 14 to uniformly hold the knife 26 to the angled face 60 of the first side portion 70. The peg member 25 has a cap portion 72, a shaft portion 74 and screw portion 76. The cap portion 72 fits in the recessed area 85 around the backing bar openings 61-64. The shaft portion 74 fits through these openings 61-64. The knife 26 has notches 41-44 which maintain the 7° alignment of the knife with the outer face 60 of the first side portion 70. Referring to FIG. 9, the second side portion 80 of the holder 12 preferably has a length of 141.5mm (5.570 inches), a width of 11.1mm (0.437 inches) and has slots 81-84 bored through its 6.4mm (0.25 inch) thickness. The slots 81-84 are positioned to allow the adjusting bars 121-124 to slide through. As shown in FIG. 4, the adjusting bars 121-124 preferably have a length of 38.1mm (1½ inches), a width of 12.7mm (0.50 inch) and a thickness of 4.7mm (0.187 inch). Preferably, the adjusting bars 121-124 extend at least partially through the second side portion openings 81-84. These second side portion openings are positioned to maintain perpendicular alignment with the inner sidewall 71 of the first side portion 70. The top of a first set of indentations or adjusting bar openings 91-94 preferably have 7.9mm (5/16 inch) diameters and generally align with a first set of top portion openings 27-30 when the knife holder assembly is in the closed position as shown in FIG. 5. Similarly, a second set of indentations or adjusting bar openings 95-98 align with a second set of top portion openings 31-34. As shown in the sectional view of FIG. 6, both the first set 91-94 and second set 95-98 of adjusting bar openings are bored at an angle of 21° degrees from the vertical. This angle is designed to receive the tapered end portions 45 of the set screws 18-21 which are also angled at 21° degrees from the vertical. The adjusting bars 121-124 also have screw holes 100-103 that are designed to receive the screw portion 76 of the peg members 22-25. Referring to FIGS. 10-12, a double knife preferred embodiment is shown. A spacer 48 is inserted between the first knife 26 and a second knife 49. The spacer 48 preferably has a length of 141.6mm (5.573 inch), a width of 11.1mm (0.437 inch) and a thickness that may be varied to achieve a desired distance between the knives. The notched openings 104-107 are angled at 7° degrees to the horizontal to allow the spaced knives 26,49 to be uniformly clamped between the backing bar 14 and the first side portion 70. In this embodiment, the set screws 18-21 are screwed into the second set of top portion openings 31-34 as shown in FIGS. 11 and 12. When the rotary cutting machine is shut down for maintenance, the operator would preferably use a hex wrench to loosen or remove the set screws 18-21 from, for example, the first set of openings 27-30, as shown in FIGS. 4-6. This, in turn, causes the tapered portion 45 of the set screw to come out of contact with the tapered sidewall 125 of the first set of adjusting bar openings 91-94, thus allowing the adjusting bars 121-124 with attached peg screws 22-25 to translate or move toward the first side portion 70 which loosens the clamped knife 26. The operator may then replace the worn knife 26 with a new knife by aligning the notches 41-44 of the knife with the shaft portion 74 of the pegs 22-25 and setting the knife onto the shaft portion 74 of each of the pegs. The operator may then easily and rapidly tighten the set screws 18-21 using the hex wrench which drives the tapered portion 45 against the tapered sidewall 125 of the first set of adjusting bar openings 27-30. This moves the adjusting bars 121-124 and attached pegs 22-25 toward the second side portion 80. The cap portion 72 of the pegs 22-25 retains the backing bar against the knife and clamps it to the outer face 60 of the first side portion 70. The rotary cutting operation can then be resumed. Alternatively, as shown in the embodiment of FIGS. 10-12, the operator may place a spacer 48 and a second knife 49 onto the shaft portion 74 of the pegs 22-25. The set screws 18-21 would then be screwed into the second set of top portion openings 31-34. The tapered end 45 of the set screws 18-21 contacts with the tapered sidewall 126 of the second set of adjusting bar openings 95-98, thus moving the adjusting bars 121-124 and attached pegs 22-25 toward the second side portion 80. The adjusting bars 121-124 extend partially through the second side portion openings 81-84. The spacer 48 may have a desired thickness to achieve the desired cut. In addition, the angle of outer face 60 the first side portion 70 may be altered for different diameter knife cylinders. The embodiments described herein may be used for a 610mm-1270mm (24-50 inch) diameter knife cylinder. Alternatively, urethane strips 120 with 4.8mm (3/16 inch) thickness as shown in FIG. 13 may be inserted on either side of the knives 26,49 to decrease the wear on the knife blade. The urethane strips preferably have openings formed therein to fit onto the shaft of the peg members 22-25, and are placed on both sides of the knife or knives. It should be appreciated that the present invention may be preformed or configured as appropriate for the intended application. The embodiments described above are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is indicated by the following claims rather than by the foregoing description. All changes which come within the mean and range of equivalency of the claims are to be embraced within their scope.

Claims: A knife holder apparatus for a rotary cutter comprising: a holder (12) including a top portion (40) and a side portion (70), the top portion (40) including an opening (27)formed therethrough; the side portion (70) including an opening (65) formed therethrough; an adjusting member including a body portion (121), a backing portion (14) and an extender (22), said extender (22) adapted to extend through said side portion opening (65), said extender (22) having the backing portion (14) at its outer end, said body portion (121) including an indention (91) formed therein having a tapered sidewall (125); and a fastener (18) inserted through the top portion opening (27) to contact the tapered sidewall (125) thereby moving the backing portion (14) toward the side portion (70) to clamp an inserted knife (26) between the backing portion (14) and an outer side (60) of the side portion (70), whereby retraction of the fastener (18) allows the backing portion (74) to be moved away from the side portion (70) to release the knife(26). The apparatus of claim 1 wherein the top portion (40) includes a slot (35) formed therethrough for allowing the holder (12) to be fastened to a knife cylinder (1). The apparatus of claim 1 wherein the extender (22) comprises a separate peg member attached to one end to the body portion (121), and at its other end to the backing portion (14). The apparatus of claim 3 wherein the peg member is screwably attached to the body portion (121). The apparatus of claim 1 further comprising a knife (26) for inserting between the backing member (14) and the side portion (70). The apparatus of claim 1 wherein the fastener (18) comprises a set screw and the top portion opening (27) has threaded sidewalls for receiving the set screw. The apparatus of claim 1 wherein the backing portion (14) is a separate member movably attached to the extender (22). The apparatus of claim 7 wherein the backing member (14) has an opening (41) formed therethrough for allowing the extender (22) to slidably fit through said backing member opening (41), said extender (22) having a cap portion (72) for retaining the backing member (14) on the extender (22). The apparatus of claim 1 wherein the body portion indention (91) is an opening having a tapered sidewall (125), said body portion opening in communication with said top portion opening (27). The apparatus of claim 1 wherein the top portion (40) has a second opening (31) formed therethrough positioned further than the first top portion opening (27) from said side portion (70), said second indention (95) with tapered sidewall (126) formed on the body portion (121) for allowing two knives (26,49) and a spacer (48) to be inserted between the side portion (70) and the backing portion (14) and clamped therebetween when a fastener (18) is inserted through said second opening (31). The apparatus of claim 10 wherein the top portion (40) has formed therethrough a first series of openings (27-30) communicating with a series of adjusting members (121-124) aligned so that each indention (91-94) aligns with one of said first series of openings (27-30), said top portion (40) has formed therethrough a second series of openings (31-34) which are positioned further than said first series from the side portion (70), each of the second series openings (31-34) aligned with the second indention (95-98) of one of the adjusting members. The apparatus of claim 11 wherein the first series of top portion openings (27-30) comprise four spaced openings, each of the four first openings aligned with the first indention (91-94) of one of four adjusting members, said second series of top portion openings (31-34) comprise four spaced openings, each of said second openings (31-34) aligned with the second indention (95-98) of one of the four adjusting members. The apparatus of claim 12 wherein each of said indentions (91-98) comprise an opening formed in the body portion (121-124) of said adjusting member, said body portion openings (91-98) having tapered sidewalls (125, 126) for allowing contact with a fastener (18-21) inserted through the top portion openings (27-34). The apparatus of claim 1 further comprising a second side portion (80) including an opening (81) formed therethrough for allowing the adjusting member to slidably extend therethrough. The apparatus of claim 1 further comprising a urethane strip (120) adapted to be positioned adjacent a knife (26,49) and clamped between the backing member (14) and side portion (70) of the holder (12). Apparatus for supporting a cutting knife (26) disposed on a rotary die cutting machine comprising: a holder (12) including a top portion (40) and first and second side portions (70,80), said holder (12) having a first plurality of openings (27-30) formed through said top portion (40), said first side portion (70) having a plurality of openings (65-68) formed therethrough, said second side portion (80) having a plurality of openings (81-84) formed therethrough; a plurality of adjusting members including body portions (121-124), extenders (22-25) and backing portion (14); the body portions (121-124) each slidably fitting through one of said second side portion openings (81-84) and positioned within a cavity formed within said top portion (40) and side portions (70,80) of said holder (12), each of said body portions (121-124) aligned with one of the holder openings (65-68), said body portions (121-124) each having an indentation or opening (91-94) formed therein, each of said body portion openings (91-94) having a tapered sidewall (125); the backing portion (14) having a front and back side, said backing portion (14) being aligned with said first side portion (70) of said holder (12), said backing portion (14) including a plurality of openings (61-64) formed therethrough, each of said backing portion openings (61-64) aligned with one of the body portions (121-124) adjacent said first side portion (70) of said holder (12); the extenders being a plurality of peg members (22-25) each having a shaft portion (74) and a cap portion (72), each of said shaft portions (74) slidably fitting one of the backing portion openings (61-64) and one of the first side portion openings (65-68), each of said shaft portions (74) connected at one end to one of said body portions (121-124), each of said cap portions (72) located adjacent said back side of said backing portion (14); and a plurality of fasteners (18-21) movably fitted in said top portion openings (27-30) for inserting through said top portion openings (27-30) and contacting with said tapered sidewall (125) to move the body portion (121-124) toward the second side portion (80) of the holder (12) thereby locking a knife (26) between the front side of the backing portion (14) and the first side portion (70) of the holder (12). The apparatus of claim 16 further comprising a plurality of slots (35-39) formed through the top portion (40) of said holder (12) for allowing the holder (12) to be positioned on and fastened to a knife cylinder (1). The apparatus of claim 16 further comprising a second plurality of openings (31-34) formed in said top surface (40) of said holder (12) and aligned with said first plurality of adjusting member openings (95-98), said second plurality of holder openings (31-34) positioned closer than the second plurality of holder openings (27-30) to the second side (80) of the holder (12). The apparatus of claim 18 further comprising a second plurality of said body portion openings (95-98) formed in said body portion (121-124), said second plurality of body portion openings (95-98) positioned further than said first plurality of body portion openings (91-94) from said first side portion (70) of said holder (12). The apparatus of claim 19 further comprising a space bar (48) having a plurality of notches formed therein to fit over the shaft portions (74) of the peg members (22-25) for spacing a pair of knives (26,49) positioned between the backing portion (14) and first side portion (70) of the holder (12) and allowing the knives (26,49) to be clamped between the backing portion (14) and holder (12) when the fasteners (18-21) are inserted into said second plurality of top portion openings (31-34) and contact said tapered sidewalls (126) of said second plurality of adjusting member openings (95-98). The apparatus of claim 16 further comprising at least one urethane strip (120) for positioning against a side of the knife (26) and clamped between the first side portion (70) and the backing portion (14). The apparatus of claim 16 wherein the fasteners (18-21) comprise set screws each having an end portion with a taper angled the same as the tapered sidewalls (125, 126) for allowing the tapered end portions of the screws to contact with the tapered sidewalls (125, 126). A method of operating a knife holder (12) in a rotary cutter comprising: inserting a knife (26) between a side portion (70) of a holder (12) and a backing portion (14) of an adjusting member; inserting a fastener (18-21) through an opening formed in a top portion (40) of the holder (12) to contact with a tapered sidewall (125) formed in the adjusting member thereby moving the adjusting member in a direction away from the side portion (70); and clamping the knife (26) between the side portion (70) and the backing portion (14). The method of claim 23 further comprising inserting a urethane strip (120) on both sides of said knife (26). The method of claim 23 further comprising inserting a spacer (48) and a second knife (49) adjacent said first knife (26). The method of claim 25 further comprising inserting a urethane strip (120) on both sides of each knife (26,49).

Inventors: BRIDGES CHARLES H, KAPOLNEK PAUL G, BRIDGES, CHARLES H., KAPOLNEK, PAUL G.
Applicants: WESTERN PRINTING MACH CO, WESTERN PRINTING MACHINERY COMPANY
Application year: 1997
Main classification: B26D1
IPC codes: B26D7