US3822625A

US3822625A - Rotary cutter with quick change knife

Info

Publication number: US3822625A
Application number: US00330965A
Authority: US
Inventors: D Obenshain
Original assignee: Westvaco Corp
Current assignee: Westvaco Corp
Priority date: 1973-02-09
Filing date: 1973-02-09
Publication date: 1974-07-09
Anticipated expiration: 1991-07-09

Abstract

A quick change knife blade support structure for a rotary cutter is disclosed wherein a fly knife support holder and a bed knife support holder are rigidly mounted respectively in a rotary cutter drum and bed plate, which holders include clamping portions for fixedly securing and retaining therein the fly knife and bed knife, with additional provisions included for adjusting the position of the fly knife with respect to the cutter drum.

Description

[111 3,822,625 July 9,1974

[ ROTARY CUTTER WITH QUICK CHANGE KNIFE [75] Inventor:

l/l973 Trogan et a1. 83/672 David Noel Obenshain, Swanton, Md.

[73] Assignee: Westvaeo Corporation, New York, Primary ExammepaDonald Schran 22 Filed:

ABSTRACT Feb. 9, 1973 tter drum and bed plate, which holders include clam fixedly securing and retainin Appl. No.: 330,965

A quick change knife blade support structure for a rotary cutter is disclosed wherein a fly knife support [52] US. 83/342, 83/349, 83/672, holder and a bed k if support holder are rigidly 83/699 mounted respectively in a rotary cu B26d 1/38 ping portions for 51 Int.

g therein the fly knife and [58] Field of Search 83/341, 342, 672, 349, 83/698 699 bed knife, with additional provisions included for adjusting the position of the fly knife with respect to the cutter drum.

[5 6] References Cited UNITED STATES PATENTS 2,829,695 4/1958 7 83/342 X 14 Claims, 2 Drawing Figures 1 ROTARY, CUTTER WITH QUICK CHANGE KNIFE BACKGROUND OF INVENTION The present invention relates generally to a device for cutting a web of material into sheets, and particu- SUMMARY OF INVENTION I In the rotary knife paper cutter devices disclosed both in applicants prior patents and in other prior art, the knife bladcslhave been conventionally held in place by bolts passing through holes in the blade itself. This conventional means for securing the rotary knife to the cutter drum, and the bed knife blade to the bed knife support structure, has proven satisfactory in operation, except that replacement and adjustment costs and down time on the machine for replacement and adjustment has become prohibitive. Accordingly, working on the principle of using a quick change, inexpensive and disposable knife blade as a substitute for the expensive,

hard tochange and adjust prior knife blades, applicant has developed the novel ers disclosed herein.

In addition, the'novel quick change knife blade holdquick change knife blade hold em disclosed hereinalso solve other and different problems which are inherent in the use of conventional bolted-implace knife bladesFor instance, the relatively high initial cost of the prior art knife blades require that they be resharpened for reuse after becoming dull and the resharpening costs, including shipping and handling have been escalating unreasonably in recent years. On the other hand, the initial cost of the quick change knife blades disclosed herein for use with applicants novel knife blade holders, have proven to be low enough to allow the blades to be discarded after becoming dull thereby eliminating theneed for resharpening with its attendant problems.

Moreover, even though the conventional throughbolted knife, blades of the prior art are adapted to be adjusted, a uniform adjustment can only be achievedthrough atedious and time consuming process. The

problems inherent in the adjustment process are caused by the necessity of passing the attachment bolts through the blade, which produces localized forces on the blade that are unequal along the blade. Now however, with the quick change, disposable knife blade holder disclosed herein, adjustment has been made much simpler with a reduction in localized stresses since the blade nests completely in a continuous bracket that extendsthroughout the length of the blade.

Finally, operational loads on the through-bolted knife blades. of the prior art structures also produce alignment problems simply because the shocks to the blade during the cutting operation changethe localized forces on the blade at the points of attachment. Of course, with the novel quick change knife blade holders disclosed herein, such alignment problems have been overcome because of the continuous support provided for the blades. Also, the knives used in the quick change knife blade holders disclosed herein require much less of the expensive tool steel than that required for the prior art knives. Thus the knives used in the quick change knife blade holders can be initially ground to extremely close tolerances so that no installation adjustment is required for the. bed knife, and only a slight installation adjustment is: required for the fly knife.

Accordingly, the object of the present invention is to provide for the operator of a rotary cutter a quick change blade holder which allows the operator toinstall and adjust cutter knives more quickly than was possible with the prior art rotary cutters. Further, because the knives used in the present invention use such a small amount of the expensive tool steel required for knives of thetype disclosed, the total cost for simply disposing of used or dull cutter knives, as proposed herein, is only a little more than having conventional cutter knives resharpened. This feature in turn eliminates the problems associated with the use of reground cutter knives and the necessity of resetting and adjusting reground cutter kniveseach time they are replaced. With the prior art structures, the changing and adjusting of old style knives requires the services of two men from 6-8. hours. Using the new quick change knives proposed herein and the novel quick change blade holders disclosed, the dull cutter knives can be replaced and aligned in less than two hours. Since the knives used in theapresent invention can be obtained with a height tolerance not exceeding 0.0002 inch, only minor adjustment is required when knives are changed. Thus itmay be seen that it is far more economical with the device of the present invention to discard the knives when they become dull rather than have them resharpened.

Another object of the present invention is to provide a. novel quick change blade holderthat is adapted to be fixedly attached to existing cutter drum and bed plate installations. g

Still another object of the present invention is to provide a novel means for retaining the cutter knife. in the quick change blade. holder including a new and improved means for adjusting the knife blade on the cutter drum. I

DESCRIPTION OF THE DRAWING showing a conventional knife blade installation (la-.

beled PRIOR ART); and,

FIG. 4 is a view similar to FIG. 3, but showingin detall the novel quick change knife blade holders of the present invention.

DETAILED DESCRIPTION According to thepresent invention, a rotary cutter device is disclosed wherein the fly knife and bed knife are mounted in a pair of quick change blade holders which are fitted to the rotary cutter drum and bed knife supporting structures. In each case, the quick change blade holders are rigidly and precisely attached to the cutter drum and bed plate respectively, however, the fly knife blade holder includes a means as an integral part of its design which permits the blade holder and its blade to be adjusted with respect to the cutter drum. The fly knife blade holder includes a slot machined in a portion thereof into which the fly knife is inserted, and a plurality of clamping screws are spaced along the length of the fly knife blade holder for fixedly retaining the fly knife in its slot. Additional retaining means are provided near each end of the fly knife blade holder in the form of set screws, which seat against the fly knife and prevent the fly knife from becoming dislodged from the fly knife blade holder either because of the clamping screws working loose or because of the centrifugal forces generated in use. Clearance adjustment for the fly knife is provided by adjusting screws in yet another portion of the fly knife blade holder, and finally, a plurality of release screws are also provided in the fly knife blade holder for releasing the fly knife from its slot when replacement is required.

The bed knife blade holder issimilar'in concept to the fly knife blade holder except'it has no provision for adjustment. Thus the bed knife blade holder has a slot machined in a portion thereof into which the bed knife is inserted, and a plurality of clamping screws are provided throughout the length thereof which fixedly retain the bed knife in the bed knife blade holder. In addition, a plurality of release screws are also provided in the bed knife blade holder for the purpose of releasing the bed knife from the bed knife blade holder when replacement is required. However, the invention will be best understood by reference to the following detailed description and drawing in which, with specific reference to FIG. 1, there is shown a rotary cutter drum supported by journals l2 and which has installed therein the novel fly knife blade holder 8 of the present invention. The cutter drum l0 is driven by any suitable means through the cutter drive pulley 6 which is connected to a drive motor (not shown). The journals. 12 are in turn supported in bearings 14 located in the cutter drum pedestals l6, l7. Pedestals I6, 17 are mounted on the bed knife support frame 18 by means of screws 20, and the bed knife support frame 18 is suitably mounted to the machine frame 19. The bed knife support frame 18 also includes the novel bed knife blade holder 9 which is shown in FIG. 2, and in more detail in FIG. 4. A fly knife 26 is clamped in the fly knife blade holder 8 and a bedknife 28 is clamped in the bed knife blade support 9 as shown in FIG. 2, and as will be more fully explained in connection with the description of FIG. 4. However, as will be observed, the rotary cutting apparatus shown in FIG. 1 is of more or less conventional construction, except for the novel fly knife and bed knife blade holders 8, 9 indicated. In addition, for the purposes of the present invention, it is desirable although not necessary that the

pedestals

16, 17 include the patented

pedestal heater devices

34, 35 as described in applicants prior US. Pat. No. 3,186,275.

FIG. 2 shows in cross section an end view of the cutter drum l0 and the fly knife blade holder 8 with the fly knife 26, and the bed plate support structure 18 with the bed knife blade holder 9 and bed knife 28. Thus particular attention to FIG. 2 shows that only slight modifications in details are required to permit the novel quick change blade holders to be installed in existing rotary cutting equipment.

FIG; 3 shows in detail a typical fly knife and bed knife installation as used in the prior art rotary cutting devices. In FIG. 3, the cutter drum 10 is formed from end to end (as shown in FIG. 1) with a generally rectangular notch that is preferably cut on a true helix angle, having a radial wall 40 and a second wall 42 at right angles to the wall 40. At the juncture of these walls 40 and 42, there is generally formed a recess 44 which receives the end of the fly knife 26 and a plurality of fly knife adjusting screws 27 (only one shown). Clamping screws 48 (only one shown) are passed through the clamping washer or block 46 and the fly knife blade 26, and are threaded into the cutter drum 10 for securing the fly knife blade fimily in place. Finally, a cover plate 50 is removably secured in the vacant notched area of the cutter drum 10 by screws 52. Obviously in the typical prior art arrangement shown, the cover plate 50, which extends from end to end on the cutter drum 10, must be removed to permit access to the fly knife blade 26 for adjustment via screws 27 or removal/installation via clamping screws 48.

In the case of a conventional prior art bed knife installation, the bed knife 28 as shown in FIG. 3 is rigidly mounted on the bed knife support structure 18 by means of the clamping screws 47 (only one shown) which are passed through the clamping washer or block 45 and the bed knife 28 and finally threaded into the bed knife support structure 18. In addition, the typical prior art bed knife installation also includes a plurality of bed knife adjusting screws 25 (only one shown) for adjusting the position of the bed knife above the bridge plate 23. Thus it may be seen that with the prior art rotary cutting devices the fly knife and bed knife are each mounted directly to the cutter drum and the bed knife support frame making removal, replacement and adjustment difficult, time consuming and expensive.

However, as shown in FIG. 4, the novel quick change cutter knife blade holders of the present invention are illustrated to their best advantage. Referring more particularly to FIG. 4, there is shown a cutter drum 10 with the novel fly knife blade holder 8 rigidly attached thereto. The fly knife blade holder is shimed into position adjacent the cutter drum face 42, and attached to the cutter drum 10 via the mounting screws 24 (only one shown) and shims 23. Initially, the shims 23 are inserted under the fly knife blade holder 8 in the region 43 provided therefor so that when the mounting screws 24 are securely tightened, the fly knife 26 clears the bed knife 28 a uniform amount throughout its length. For this purpose, a clearance of 0.010 inch has been found to be satisfactory. The mounting screws 24 may be positioned as desired, however it has been found that good results can be obtained by positioning the screws 24 on three inch centers along the length of the fly knife blade holder 8 to thereby securely fix the fly knife blade holder in position on the cutter drum.

For the purpose of releasibly retaining the fly knife 26 in the fly knife blade holder 8, a slot 29 is machined in an outwardly projecting portion of the blade holder for accepting the fly knife 26. After the fly knife 26 is inserted in slot 29, it is clamped in position by a series. of clamping screws 22 (only one shown) that are also spaced at three inch centers along the length of the fly knife holder 8. In the preferred embodiment each of the clamping screws 22 are located at substantially a right angle to a second slot 49 in the body of the fly knife blade holder 8. Slot 49 is formed in the fly knife holder 8 near the bottom of the blade slot 29 and extends substantially perpendicular thereto. The clamping screws 22 are individually tightened after the fly knife 26 is inserted in the slot 29, and as the screws 22 are tightened they extend across the second slot 49 and abut against an inside face thereof. This action tends to spring the jaws of slot 29 to close and grip the fly knife by flexing at point x shown in FIG. 4.

In addition, to provide yet another securing means for the fly knife 26, a cone pointed set screw 21 is provided near each end of the fly knife blade holder 8 which cooperates with a conically shaped hole in the fly knife 26. The main purpose of the set screws 21 is to prevent the fly knife 26 from becoming disengaged from the slot 29 due to centrifugal forces in operation when the clamping screws 22 are not properly tightened. In addition, the set screws 21 tend to force the screws 33 and 63 (only one of each shown) spaced along the length of the bed knife blade holder. For the purpose of releasibly retaining the bedknife 28 in the bed knife blade holder 9, a slot 34 is machined in a pro- 5 jecting portion thereof into which the bed knife 28 is end of the fly knife to the bottom of the slot 29. Of

course since the fly knife blade holder 8 is mounted on the cutter drum along a helix angle, the flyknife 26 will have a slight bow and the set screws 21 insure that the ends of the knife seat properly. t 1 Moreover, as noted hereinbefore, in addition to the knife blade clamping screws 22, a plurality (three or more) of clamp release screws 22a are also'provided in i the. fly knife blade holder 8 at substantially uniformly spaced intervals along the length thereof, for springing open the slot 29 when it is desired to remove the knife blade 26' for replacement. In operation, the clamping screws 22 are retracted before the release screws 22a are tightened for removal of the blade 26, and after a new blade is replaced, the release screws 22a are retracted before the clamping screws 22 are retightened.

For the purpose of adjustment, the fly knife blade holder 8 also includes a series of adjusting screws 30 (only one shown) which extend through the blade holder 8 and abut against the face 42 of thecutter drum notch 41. To provide a point of flexure for the fly knife blade holder 8, the holder has a third slot formed therein as shown at 59 on the drawing, and when the adjustingscrews 30 are manipulated to give the fly knife proper clearance, the fly knife holder 8 flexes at the point y. As pointed out hereinbefore, with the shims 23 in place, the mounting screws 24 securely tightened, and the adjusting screws 30 not touching the face 42, the fly knife should clear the bed knife by a uniform amount of about 0.010 inch. Subsequently, when the adjusting screws'30 are progressively tightened, the fly knife holder 8 flexes at the point y" until the desired cutting clearance is attained between the knives. The desired clearance is on the order of 0.0001

I inch as determined by actually cutting thin paper as the clearance is being adjusted.

The bed knife blade holder 9 is quite similar in action and structure to the fly knife blade holder 8 except that no adjustments are provided therefor other than the shims 31 used with the initial installation. In this regard, the bed knife support structure18 includes a trough or notch 32 machined therein for accepting the bed knife blade holder 9. The bed knife blade holder 9 is placed in the notch 32 and shimed into proper position with the shim elements 31. Subsequently, the bed knife blade holder 9 is rigidly mounted in the notch 32 of the bed knife support structure with a plurality of mounting closely fitted. After the bed knife 28 is inserted in slot 34, it is clamped in position by a series of clamping screws 37, preferably of the socket head type (only one shown), which are spaced on approximately three inch centers along the length of the bed knife holder 9. In the preferred embodiment, each of the clamping screws 37 are provided with clearance through the bed knife support structure 18 and are located at substantially a right angle to an internal slotted area 36 located coextensive with but separated from the bed knife slot 34. The clamping screws 37 are individually tightened after the bed knife 28 is inserted in the slot 34, and as the screws 37 are tightened they extend across the slot 36 and abut against an inside face thereof. This action tends to spring the jaws of slot 36 to cause the blade gripping jaws of slot 34 to close and grip the bed knife by flexing at the point 2 shown in FIG. 4.

Three or more release screws 35 are also provided in the bed knife holder 8 to spring open the jaws of the bed knife clamping slot 34 when installing, removing and replacing the bed knife. Screws 35 are spaced at substantially uniform intervals along the bed knife holder 9 at points midway between the clampingscrews 37. The release screws 35 are preferably similar to the clamping screws 37 except are made somewhat longer to enable them to be threaded into the bed knife holder on the opposite side of the slot 36. Of course, the release screws 35 also are provided with clearance through the bed plate support structure 18, and when tightened, they become threaded into the opposite side of slot 36 and bear against the vertical wall of notch 32. This action tends to close the slot 36 and produce a flexure at the point 2" which spreads the jaws of the bed knife slot 34 thereby permitting release of the bed knife 28. Obviously, clamping screws 37 must be loosened before the release screws 35 are tightened, and conversely, the release screws 35 must be retracted before tightening the clamping screws 37.

The top edge of the bed knife should be straight to within 0.0001 inch for best results and the shims 31 are used for this purpose and also for the purpose of correcting for possible deficiencies in machining the bed knife support structure notch 32, or warping that might have occurred in the assembly of the apparatus. Safety set screws are not needed in the bed knife holder 9 as are provided in the fly knife holder 8 since there are no centrifugal forces at the bed knife holder which would tend to dislodge the bed knife 28.

Finally, it should also be noted that each of FIGS. 3 and 4 show channeled bars 61, 62 under the bridge plate 23 located on each side of the cutting zone. The channeled bars 61, 62 are shown in the preferred embodiment since they have been found desirable although not necessary and the function of the channeled bars 61, 62 is fully disclosed in applicants prior US. Pat. No. 3,143,016.

It should be noted however, that only a preferred embodiment has been shown and described and obviously 1. In a rotary cutting machine including a stationary bed knife blade mounted on a bed plate, a rotary cutter drum, and a rotary fly knife blade mounted on said cutter drum, said stationary bed knife and rotary fly knife cooperating with one another to form a cutting zone, the improvement comprising:

a. an elongated bed knife blade holder fixedly mounted on said bed plate including means for releasibly retaining the bed knife blade therein, said means comprising a slotted area machined in a portion of said bed knife holder to form blade gripping jaws for receiving the bed knife blade, said bed knife blade holder further including a plurality of clamping means provided along the length thereof for clamping the bed knife blade in the blade gripping jaws, and a plurality of release means provided along the length thereof for releasing the bed knife blade from the blade gripping jaws; and,

b. an elongated fly knife blade holder including means for releasibly retaining the fly knife blade therin fixedly mounted for adjustment on said rotary cutter drum.

2. The apparatus of claim 1 wherein the clamping means further compriseclamping screws which pass through a first portion of said bed knife holder, across a first slotted flexure area machined in said bed knife holder and abut against an inside face of said first slotted flexure area thereby flexing the bed knife holder to cause the blade gripping jaws to close and clamp the bed knife in position.

3. The apparatus of claim 2 wherein the first slotted flexure area is coextensive with but separated from the bed knife slotted area in said bed knife holder.

4. The apparatus of claim 3 wherein the release means further comprises releasing screws which pass through a first position of said bed knife holder, across the first slotted flexure area, and become threaded into a second portion of said bed knife holder thereby flexing the bed knife holder to cause the blade gripping jaws to open and release the bed knife blade.

5. The apparatus of claim 4 wherein the means for releasibly retaining the fly knife blade in the rotary cutter drum comprises a slotted area machined therein which forms blade gripping jaws for receiving the fly knife blade.

6. The apparatus of claim 5 wherein the fly knife blade holder further includes a plurality of clamping means provided at the ends and along the length thereof for clamping the fly knife blade in the blade gripping jaws.

7. The apparatus of claim 6 wherein the fly knife blade holder also includes a plurality of release means provided along the length thereof for releasing the fly knife blade from the blade gripping jaws.

8. The apparatus of claim 7 wherein the fly knife blade holder further includes a plurality of fly knife adjusting means located along the length thereof.

9. The apparatus of claim 8 wherein the clamping means located along the length of said fly knife blade holder further comprise clamping screws which are threaded into the blade clamping portion of said fly knife blade holder and pass across a second slotted flexure area machined in said fly knife holder and abut against an inside face of said second slotted flexure area thereby flexing the fly knife holder to cause the fly knife blade gripping jaws to close and clamp the fly knife in position.

10. The apparatus of claim 9 wherein the second slotted flexure area is substantially perpendicular to and coterminous with the slotted area which receives said fly knife blade.

ll. The apparatus of claim 10 wherein the clamping means located at the ends of said fly knife holder further comprise a pair of cone pointed set screws which are threaded into the fly knife holder and become seated in openings provided therefor in the ends of said fly knife blade.

12. The apparatus of claim 11 wherein the release means for said fly knife blade further comprises releasing screws which pass through the blade clamping portion of said fly knife holder, across the second slotted flexure area, and. become threaded into an opposite portion of said fly knife holder thereby flexing the fly knife holder to cause the fly knife blade gripping jaws to open and release the fly knife blade.

H3. The apparatus of claim 12 wherein the fly knife adjusting means further comprise adjusting screws which are threaded into another portion of said fly knife blade holder and abut against the rotary cutter drum in combination with a third slotted flexure area located in said fly knife holder and arranged substantially parallel to the slotted area for gripping said fly knife blade whereby tightening of said adjusting screws causes the fly knife holder to flex and adjust the position of said fly knife blade and holder with respect to said rotary cutter drum.

14. The apparatus of claim 13 wherein the third slotted flexure area is further located adjacent to the means for mounting said fly knife blade holder on said rotary cutter drum.

Claims

1. In a rotary cutting machine including a stationary bed knife blade mounted on a bed plate, a rotary cutter drum, and a rotary fly knife blade mounted on said cutter drum, said stationary bed knife and rotary fly knife cooperating with one another to form a cutting zone, the improvement comprising: a. an elongated bed knife blade holder fixedly mounted on said bed plate including means for releasibly retaining the bed knife blade therein, said means comprising a slotted area machined in a portion of said bed knife holder to form blade gripping jaws for receiving the bed knife blade, said bed knife blade holder further including a plurality of clamping means provided along the length thereof for clamping the bed knife blade in the blade gripping jaws, and a plurality of release means provided along the length thereof for releasing the bed knife blade from the blade gripping jaws; and, b. an elongated fly knife blade holder including means for releasibly retaining the fly knife blade therin fixedly mounted for adjustment on said rotary cutter drum.

2. The apparatus of claim 1 wherein the clamping means further comprise clamping screws which pass through a first portion of said bed knife holder, across a first slotted flexure area machined in said bed knife holder and abut against an inside face of said first slotted flexure area thereby flexing the bed knife holder to cause the blade gripping jaws to close and clamp the bed knife in position.

11. The apparatus of claim 10 wherein the clamping means located at the ends of said fly knife holder further comprise a pair of cone pointed set screws which are threaded into the fly knife holder and become seated in openings provided therefor in the ends of said fly knife blade.

12. The apparatus of claim 11 wherein the release means for said fly knife blade further comprises releasing screws which pass through the blade clamping portion of said fly knife holder, across the second slotted flexure area, and become threaded into an opposite portion of said fly knife holder thereby flexing the fly knife holder to cause the fly knife blade gripping jaws to open and release the fly knife blade.

13. The apparatus of claim 12 wherein the fly knife adjusting means further comprise adjusting screws which are threaded into another portion of said fly knife blade holder and abut against the rotary cutter drum in combination with a third slotted flexure area located in said fly knife holder and arranged substantially parallel to the slotted area for gripping said fly knife blade whereby tightening of said adjusting screws causes the fly knife holder to flex and adjust the position of said fly knife blade and holder with respect to said rotary cutter drum.