US3747449A

US3747449A - Slitting device and method

Info

Publication number: US3747449A
Application number: US00240940A
Authority: US
Inventors: G Gould
Original assignee: Dow Chemical Co
Current assignee: Dow Chemical Co
Priority date: 1972-04-04
Filing date: 1972-04-04
Publication date: 1973-07-24
Anticipated expiration: 1990-07-24

Abstract

The disclosure concerns method and apparatus having utility in the art of slitting continuous lengths of film, sheet, and the like flexible web materials, and particularly for trimming waste edge(s) therefrom. The apparatus in the specific structure illustrated, embodies: a hollow trim cylinder 12 rotatably driven such as by belt means 58, and which receives an advancing web 78, a groove 50 continuous on the surface of revolution of such cylinder and in communication with the interior thereof, a stationary slitting blade 52 which rides in such groove, and passage means 34 for introducing air or like fluid internally to the cylinder, for flow of the same outwardly of groove 50 against the underside of the web. In practicing the method, the trim cylinder is driven at a rate generally corresponding to or in excess of that of web 78.

Description

United States Patent 1 Gould July 24, 1973 SLITTING DEVICE AND METHOD Primary Examiner.l. M. Meiste r Attorney-William M. Yates. Burke M. Halldorson [75] Inventor: Gordon E. Gould, Breckenridge, ct

Mich.

[57] ABSTRACT [73] Asslgnee: 33: f l fi Company The disclosure concerns method and apparatus having 1 an utility in the art of slitting continuous lengths of film, sheet. and like fleiiible web inaterials, and particu- [22] Filed 1972 larly for trimming waste edge(s) therefrom. The apparatus in the'specitic structure illustrated, embodies: a [21] Appl 240340 hollow trim cylinder 12 rotatably driven such as by belt means 58, and which receives an advancing web 78, a [52] U S Cl 83/22 83/56 83/98 groove 50 continuous on the surface of revolution of 83/169 83/402 [431 such cylinder and in communication with the interior 51 Int. Cl 325d 19/04 themfi a summary slitting blade 52 which rides in [58] Field oi gearch 83/22 24 56 98 Such and Passage means immdudng air 100 169 6 or like fluid internally to the cylinder, for flow of the same outwardly of groove 50 against the underside of the web. In practicing the method, the trim cylinder is References and driven at a rate generally corresponding to or in excess UNITED STATES PATENTS of that of web 78.

1,939,925 12/1933 Schwartz 83/100 10 C a s, 2 a g Figures Lur/can/ in SLITTING DEVICE AND METHOD BACKGROUND OF THE INVENTION In slitting mill roll stock into finished film of desired width(s), it is usually necessary to trim one and sometimes both edges of the mill roll. The ultimate yield of the mill roll can be benefited depending on the finesse with which this can be performed.

Saran film presents a difficult problem because it has a tendency to cold flow. For example, when wound on a mill roll, saran can exhibit cold flow to an extent that the layers nearest the core will become irregular in width with respect to the layers thereof near or at the surface of the mill roll. Also particularly with saran, and like delicate films, there has historically been a problem in holding and maintaining a narrow or fine edge trim.

Moreover, in instances where the film may come up short of the edge trimmer, that is, where trimming is intermittent, certain devices in use before this invention would not readily pick up the film to again resume trimming. Rather, what can be referred to as a bird nest might form, which is essentially a bunching up of the film adjacent the front edge of the trimming blade. As still a further disadvantage associated with a lack of capability to trim intermittently, certain start-up problems are usually generated and require particular attention, such as with each mill roll change.

In view of the many shortcomings of the prior art, as exemplified at least partially above, it would be particularly advantageous and beneficial if there were available an apparatus and method for automatically trimming the waste edge of the moving flexible web material, wherein the device operated in such a manner to maximize the yield of the film through efficiently controlling and minimizing the amount of waste edge or edges trimmed from the film.

It would be further advantageous if such an apparatus and method were not limited to a continuous trimming step, but could operate intermittently, and further, if such a device were of a construction and mode of operation that made it substantially insensitive to bird nesting or piling up of the film in front of the cutting blade.

It would be of still further advantage if the aforesaid device and method required essentially little or no special procedure in the initial startup of the trimming operation, such as with each mill roll change.

BRIEF SUMMARY OF THE INVENTION These features and other advantages in accordance with the teachings of the present invention are achieved in a method and apparatus employing in combination, an anvil means defining a groove, a blade means associated with such groove and adapted to trim or slit an advancing web as it is passed over such groove, and means for influencing air or like fluid flow outwardly of the groove. against the underside of such advancing web. The preferred structure of such apparatus comprises a rotatable trim cylinder or roll (i.e., anvil means) defining such groove circumferentially thereon, an air feed source for influencing air flow outwardly from the groove, and a blade or cutting instrument disposed within the groove and extending therefrom, and preferably with it edge normal or substantially normal to the surface of the trim roll. In practicing the method of the invention, the trim roll is driven at a rate generally corresponding to or in excess of that of the moving web.

Further features and advantages in accordance with the present invention will become more apparent from the following specification taken in conjunction with the drawings wherein:

FIG. 1 is a front elevational view of an edge trimming and/or slitting device constructed according to the general teachings and principles hereof, and shows certain parts thereof broken away to illustrate detail; and

FIG. 2 is a side elevational view schematically illustrating the device of FIG. 1 in employment in an edge trimming fabrication, and shows additionally, certain apparatus desirably companion to such employment.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT In the FIG. 1, Reference Numeral l0 denotes an edge trimming and/or slitting device having utility with regard to flexible web materials, particularly continuous plastic film or sheeting. Device 10 is comprised of a hollow or centrally bored trim cylinder or roll or anvil 12, which is journably carried at its ends 14 and 16, about stationary spindles l8 and 20, respectively. The spindles, in turn, are rigidly affixed to suitable framing, as denoted generally at 22 and 24.

The end 14 of the device is shown in detail, and is the mirror image of end 16. Spindle 18, associated with end 14, is press fitted or otherwise affixed to the inner racer of a bearing 26; and the outer racer of the bearing is press fitted into the central bore of cylinder 12, for free rotation of the trim cylinder about the stationary spindles. A seal 28 is affixed inwardly of bearing 26 by press fit with the inner surface of the trim cylinder. A lubricant passage 30 is defined in spindle 18, and is extended axially outwardly thereof such as by means of an external fitting or line 32. Passage 30 and line 32 provide a path of communication for entry of lubricant into the space between the bearing and seal.

A second or air passage 34 extends axially through the extent of spindle 18 to provide for introduction of air into the hollow central part of the trim cylinder, and is operated such as through an air feed line 36.

A first collar piece 38 is affixed circumferentially about the trim cylinder adjacent end 14. Collar piece 38 includes a recessed threaded end 40 which threadably receives a second collar piece 42. Such pieces are flush with and form a part of the surface of revolution 44 of the trim cylinder.

A plurality of apertures 46 are drilled or otherwise formed through the wall of the trim cylinder at regions underlying the first collar piece, and communicate with a circumferentially continuous channel 48. Channel 48 is defined between the underside of the first collar piece, and the adjacent surface of the trim cylinder.

A circumferentially continuous groove 50 is defined on surface of revolution 44 by collar pieces 38 and 42. Groove 50 communicates with channel 48, through a plurality of port means or apertures 54 defined in threaded end 40, and ultimately with the interior of the trim cylinder through apertures 46. Turning the second collar piece on threaded end 40 varies and sets the width of groove 50. The groove can extend parallel to the direction of revolution of trim cylinder 12.

A stationary cutting blade 52 is affixed to a rigid support 70, and extends downwardly therefrom and enters groove 50 at an angle approximately normal to surface of revolution 44. A pulley 56 is attached to end 14 of the trim cylinder, and is operated such as by a drive belt 58, to provide a positive rotational drive source.

Referring now to FIG. 2, companion apparatus desirably associated with device may include a hood element 60 which sets over the device, substantially overlying the entire extent thereof. Hood element 60 includes a rectangular enclosure 62 which is hollow as denoted by dotted lines, and opens downwardly toward device 10. The back wall 64 of the hood element is extended or offset downwardly, and apertured at 66, and the aperture fitted with a vacuum pick-up tube 68. The hood element may be used as or comprise the support 70 for the cutting blade.

A pair of interdigitatable forks or finger elements 72 and 74, also shown schematically, are positioned forwardly of device 10, and preferably separated therefrom by an idler roll 76. The forks are positioned on opposite sides of the web, and are operable between an open or rest position as shown in full lines, and an interdigitated position as is shown in dotted lines, and in which such engage the web from opposite sides.

Operation In the operating procedure of FIG. 2, a web 78 is drawn off from a preferably compact supply source such as a mill roll 80, by appropriate film drive means, (not shown), the latter comprising, for example, suitable drive rolls. Device 10 can be positioned at some area intermediate the above. The web after it leaves the mill roll can be directed about suitable roll means, or the like, including idler roll 76, to tension the web, and preferrably, partially wrap the same about trim cylinder 12. Simultaneously as the web is passed about the trim cylinder, air or its equivalent is being introduced through air passage 34, thereby creating a positive pressure within the central bore of the trim cylinder. The pressure is ultimately relieved by the passage of air generally radially outwardly of groove 50, whereupon the same impinges against the underside of the advancing web.

Cooperatively with the passage or flow of air through groove 50, blade 52 trims a desired or determined amount of edge waste from the web. It is understood that the opposite edge of the web can be simultaneously thinned in a like manner, by utilizing a blade and groove arrangement at end 16, like that shown for end 14.

The waste trim is automatically removed through vacuum pick-up tube 68. The suction of the vacuum is at least in part concentrated at the underside of the trimmed waste strip as denoted by air flow arrows 82, due to the enclosure effect of hood 60. Overall such assists to prevent the waste trim from wrapping and accumulating on the trim cylinder, as is also assisted by the air flow outwardly of groove 50.

The trim cylinder is preferably driven at all times, at a rate in excess of, or at least generally about that of the advancing web, to avoid placing drag thereon. This can be accomplished as shown, or alternately, as a further example, the advancing web can drive the trim cylinder, such as by means of a roll (not shown) that firmly engages the web against the surface of the trim cylinder, preferably at a region remote from blade 52.

By way of further illustration of the invention, a trim cylinder 12 is constructed having a diameter at its surface of revolution of about 3 A inches. The cylinder is constructed of mild steel having a flash chromium plate finish for corrosion resistance. Saran film of 0.0005 inch thickness is passed over the trim cylinder, utilizing a wrap of about 180. That is, the film engages the trim cylinder about forwardly of blade 52, and is taken off at about 90 rearwardly of the blade. The cylinder is at all times set to drive at a rate of about 5 to 40 percent, and preferably about 20 to 30 percent, faster than the film, placing the section of the film between the trim cylinder and idler roll 76 in tension. Some slippage of belt 58 on the pulley, however, reduces the actual rotational speed of the trim cylinder.

The blade is set approximately normal to the advancing film but can be set off normal, either forwardly or backwardly, and still function properly. However, it is noted that if the cutting edge of the blade is placed generally in the horizontal position, the trim cylinder does not function nearly as well as with the blade in the vertical or near vertical position.

The groove width setting is approximately 0.015 inch, and blade 52 is of a width of approximately 0.012 inch. The positive pressure within the trim cylinder is maintained at approximately 4 to 5 psig, through air introduced through air passage 34.

Under such operating conditions the trim cylinder operates with remarkable efficiency. It is able, for example, to operate intermittently, that is, lose the edge and then pick it up again without bunching or piling up the material in front of the slitting blade. Moreover, upon mill roll changes, the trim cylinder proves especially easy in initial startup because of its ability to operate intermittently. It is also found that the blade can take a fine sliver of edge waste where necessary, and thus can operate with maximum control and finesse in edge trimming the web.

Because of the delicate nature of saran, it is found desirable to employ the aforenoted interdigitable forks 72 and 74 on the infeed side of the cylinder, and which are operated responsive to stoppage of the trimming operation. Otherwise the film may be notched by the blade and tear propagate. The forks, however, which are engaged or interdigitated slightly before film stoppage, wrinkle the film, causing the same to pull back slightly from the blade and negate tear propogation.

As may well be appreciated, the attached drawing shows a preferred form of the invention. Obviously structural changes may be made therein without departing from the spirit and scope of the invention. Accordingly it is intended that the invention only be limited by the breadth of the appended claims.

What is claimed is:

l. A slitting device comprising an anvil means defining a groove on a surface portion thereof, a slitting means partially disposed in such groove and traversing such surface portion, and passage means communicating with such groove for introducing a gaseous fluid thereto for flow of the same generally outwardly from such groove.

2. The device of claim 1 wherein such anvil means comprises a rotatable cylinder means, such groove being circumferentially continuous on the surface of revolution of such cylinder means.

3. The device of claim 2 wherein such groove extends in a direction normal to the axis of such cylinder means.

4. The device of claim 3 wherein such slitting means comprises a stationary blade.

5. The device of claim 4 wherein the cutting edge of such blade extends generally normal to the surface of revolution of such cylinder means.

6. The device of claim 4 including means to rotationally drive such cylinder means.

7. The device of claim 6 wherein such cylinder means is hollow, such groove being in communication with the interior of such cylinder means, and wherein such passage means communicates between a gaseous fluid supply source and the interior of such cylinder means.

8. In a method of slitting advancing web material, the steps of:

a. directing such advancing web over a surface defining a groove opening toward such web and extending generally in the direction of movement thereof,

ping the web at least partially about such surface.

PC4050 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,747,449 Dated July 24, 1973 Inventofls) Gordon E. Gould It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Colnmn 3, line 15, the word "interdigitatabl'e" should be deleted so that the sentence reads "A pair of forks.

Column 3, line 46, the word "thinned" should I be -trimmed--.

Signed and sealed this 1st day of January 19714..

(SEAL) Attest:

EDWARD M.FLETCHER,JR. REN v1). TEGTMEYER Attesting Officer Acting Commissioner of Patents

Claims

1. A slitting device comprising an anvil means defining a groove on a surface portion thereof, a slitting means partially disposed in such groove and traversing such surface portion, and passage means communicating with such groove for introducing a gaseous fluid thereto for flow of the same generally outwardly from such groove.

8. In a method of slitting advancing web material, the steps of: a. directing such advancing web over a surface defining a groove opening toward such web and extending generally in the direction of movement thereof, b. causing a gaseous fluid to flow outwardly of such groove against such web, c. and slitting such web employing a slitting means partially disposed in such groove and traversing such surface.

9. The method of claim 8 wherein such surface comprises a cylindrical surface having such groove circumferentially continuous thereOn, such method including the additional step of rotating such surface at a speed approximately equal to or in excess of the rate of the moving web.

10. The method of claim 9 including the step of wrapping the web at least partially about such surface.