US3745863A

US3745863A - Severing mechanism

Info

Publication number: US3745863A
Application number: US00215819A
Authority: US
Inventors: R Murre; H Schulz
Original assignee: Bell and Howell Co
Current assignee: Bell and Howell Co
Priority date: 1972-01-06
Filing date: 1972-01-06
Publication date: 1973-07-17
Anticipated expiration: 1990-07-17

Abstract

A severing mechanism for cutting sheets or strips of paper or other sheet material from a length thereof, including a rotatably mounted knife spring biased in one direction of rotation for cutting purposes. An arcuate ratchet is mounted at one end of the knife. A cocking pawl is oscillatably mounted for incrementally rotating the knife to a cocked condition by engaging the ratchet teeth seriatim, and a keeper pawl is engageable with the ratchet teeth to prevent rotation of the knife on the back strokes of the oscillating cocking pawl. A cam type trip member engages the pawls to lift the pawls off of the ratchet, thereby releasing the knife for cutting. In one form of the invention, a lost motion connection is provided between the cocking and keeper pawls to permit the cocking pawl to oscillate relative to the keeper pawl for cocking the knife but to cause both of the pawls to be moved off of the ratchet when one of the pawls is tripped. In another form, the cocking pawl is moved off of the ratchet prior to the keeper pawl so that the oscillatory movement of the cocking pawl does not interfere with sharp release of the knife.

Description

United States Patent 1 Murre et al.

[451 July 17, 1973 SEVERING MECHANISM [75] Inventors: Robert W. Murre, Chicago; Herman C. Schulz, Skokie, both of III.

[73] Assignee: Bell & Howell Company, Chicago,

Ill.

[22] Filed: Jan. 6, 1972 [21] Appl. No.: 215,819

[52] U.S. Cl. 83/224, '83/587 [51] Int. Cl 826d 5/08, B26d 5/22 [58] Field of Search 83/224, 223, 587,

[56] References Cited UNITED STATES PATENTS 3,185,008 5/l965 Balaz et al. 83/224 Primary Examiner-J. M. Meister Attorney-J. R. Stapleton [57] ABSTRACT A severing mechanism for cutting sheets or strips of paper or other sheet material from a length thereof, including a rotatably mounted knife spring biased in one direction of rotation for cutting purposes. An arcuate ratchet is mounted at one end of the knife. A cocking pawl is oscillatably mounted for incrementally rotating the knife to a cocked condition by engaging the ratchet teeth seriatim, and a keeper pawl is engageable with the ratchet teeth to prevent rotation of the knife on the back strokes of the oscillating cocking pawl. A cam type trip member engages the pawls to lift the pawls off of the ratchet, thereby releasing the knife for cutting. In one form of the invention, a lost motion connection is provided between the cocking and keeper pawls to permit the cocking pawl to oscillate relative to the keeper paw] for cocking the knife but to cause both of the pawls to be moved off of the ratchet when one of the pawls is tripped. In another form, the cocking pawl is moved off of the ratchet prior to the keeper pawl so that the oscillatory movement of the cocking pawl does not interfere with sharp release of the knife.

15 Claims, 6 Drawing Figures SEVERING MECHANISM BACKGROUND AND SUMMARY OF THE INVENTION This invention relates to a severing mechanism and particularly to a severing mechanism for cutting sheets or strips of paper or other sheet material from a roll or length thereof.

In various apparatus such as photographic apparatus, duplicating apparatus, and the like, it is necessary to have means for severing film, paper, and the like, from a roll or supply thereof. For instance, in some duplicating machines, rolled prlnting or duplicating paper is used. The rolled duplicating paper is cut in accordance with the length of an original which is run through the duplicator for copying. The cut sheet of paper may then be passed through a charging device, moved forward in juxtaposition with the original, and moved past an exposure device which reproduces the original image onto the cut sheet of paper.

The principal object of this invention is to provide a new, improved and more efficient and satisfactory mechanism for severing sheets or strips of sheet material from a supply or length thereof.

Another object of this invention is to provide a severing mechanism adaptable for use in duplicating apparatus, photographic apparatus, and the like.

In the exemplary embodiment of the invention, an elongated severing mechanism in the form of a knife, having a length at east the width of the sheet material to be severed, is rotatably mounted and spring biased in one direction of rotation for cutting purposes. An arcuate ratchet is mounted on one end of the knife and pawl means is engageable with the ratchet to rotate the knife opposite said one direction and hold the knife in cocked position. Trip means is provided to disengage the pawl means from the ratchet to release the knife and permit the spring to rotate the knife in said one dirction for cutting purposes.

In the preferred embodiment, the pawl means includes a cocking pawl oscillatably mounted for incrementally rotating the knife to its cocked condition by engaging the ratchet teeth seriatim, and a keeper pawl engages the ratchet teeth to prevent rotation of the knife on the back strokes of the oscillating cocking pawl.

In one form of the invention, a lost motion connection, in the form of a pin and slot, is provided between the cocking and keeper pawls to permit the cocking pawl to oscillate relative to the keeper pawl when cocking the rotary knife, but to cause one of the pawls to lift off of the ratchet when the other pawl is moved off of the ratchet in a direction transverse to the direction of oscillatory movement of the cocking pawl. The trip means includes a cam portion on one of the pawls engageable by an appropriate complementary cam means to disengage the pawls from the ratchet. The severing means is shown herein as part of a duplicating apparatus having a drive system which includes the trip means. The drive system may include an endless drive chain having a pin protruding from the side thereof at a point therealong. The pin comprises said complementary cam means for engaging the cam portion on one of the pawls in response to movement of the drive chain to provide means to trip the rotary knife in a timed relationship with the drive system or cycle of the duplicating apparatus.

In another form of the invention, the cocking and keeper pawls are independently mounted with no connection therebetween and the drive system includes a rotating gear having a pair of pins protruding from one side thereof for rotation therewith. The pins are slightly angularly separated with respect to the axis of rotation of the rotating gear so that one of the pins lIfts the cocking pawl off of the ratchet before the other pin lifts the keeper pawl off of the ratchet so that the oscillatory movmement of the cocking pawl does not interfere with sharp release of the rotary knife.

As another feature of the invention, particularly with the latter form of. the invention, is the provision of means to initially adjust the point in time when the pin member or members will engage the pawls to trip the rotary knife. In the exarnplary form of the invention, the rotating gear is mounted for axial movement to selectively move the gear out of mesh with its driving gear, thereby permitting relative adjustment between the gears. In addition, means is provided to limit the amount of adjustment between a given or desired range of cut sheet lengths. Such means includes an annular slot in the rotating gear and a fixed pin member aligned with the slot and mounted on a frame portion of the apparatus. The pin member extends into the slot when the rotating gear is moved axially out of engagement with its driving gear, and the pin is removed from the slot when the rotating gear and driving gear are in mesh.

Other objects, features and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of severing mechanism in accordance with the present invention, with both the cocking pawl and keeper pawl in engagement with the ratchet means;

FIG. 2 is a partial side elevational view similar to that of FIG. 1, on an enlarged scale, showing both the cocking pawl and keeper pawl lifted off of the ratchet means to trip the rotary knife for severing the sheet material;

FIG. 3 is a side elevational view of a modified form of the invention;

FIG. 4 is a partial vertical sectional view, on an enlarged scale, of the rotating tripping gear, and related mechanism, of the form of the invention shown in FIG. 3.

FIG. 5 is a further modified form of the invention shown in FIG. 3 wherein the cam pins are disposed on a member independent of the gear 72, with the gear in driving meshed condition; and

FIG. 5a is a partial view smilar to FIG. 5 with the gear 72 out of driving meshed condition.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings in greater detail, and first to FIGS. 1 and 2, the severing mechanism of this invention is shown as incorporated in a duplicating machine, or the like, which includes a supply roll 10 of sheet material 11, such as duplicating paper, or the like. The paper is passed through a pair of

feed rollers

12a and 12b to a severing knife mechanism, generally designated l4 and described in greater detail hereinafter, where it is severed as seen in FIG. 2. The cut sheet of paper S then may be fed from the severing mechanism, in the direction of arrow A, to charging, exposing or other stations of the duplicating apparatus. Obviously, the

feed rollers

12a and 12b rotate in the direction of arrows B pulling the sheet material off of the supply roll 10, rotating the supply roll in the direction of arrow C. The duplicating apparatus has a drive system which includes an endless drive chain 16 wrapped around

sprockets

18a and 18b, nhe drive chain moving in the direction of arrows D. The drive chain may be used for moving a platen, or the like, to carry an orignal past an exposure station.

The severing mechanism of this invention includes an elongated rotatably mounted knive 20 which is biased by a spring 22 in a direction of rotation indicated by the arrow E (FIG. 2) for cutting purposes. The elongated knife is at least as long as the width of the sheet material and has an elongate cutting edge 20a (FIG. 2) which cooperates with a stationary knife blade 24 (FIG. 2) to sever sheets or strips of paper or other sheet material from the length thereof being pulled by

feed rollers

12a, 12b from the supply roll 10. An annular ratchet 26, having ratchet teeth 26a, is mounted on one end of the rotary knife 20 and is fixed thereto for rotation therewith.

A cocking pawl member 28 is mounted eccentrically by a pin 30 to the feed roller 12b so that the cocking pawl 28 oscillates generally in the direction of doubleended arrow F as the feed roller 12b rotates. The cocking pawl 28 has a pawl tooth 280 which, under the influence of a spring 32, is biased into engagement with the ratchet teeth 26a. Thus, as the cocking pawl 28 oscillates in the direction of arrow F it effectively cocks the rotary knife 20 and ratchet 26 in the direction of arrow G (FIG. 1).

A keeper pawl member 34 is pivotally mounted to the apparatus frame by a pivot pin 36 and has a pawl tooth 34a engageable with the ratchet teeth 26a to prevent rotation of the rotary knife and ratchet in the direction of arrow E (FIG. 2) on the back strokes of the oscillating cocking pawl 28.

A lost motion connection, defined by a slot 38 in the cocking pawl 28 and a pin 40 on the keeper pawl 34, is provided between the cocking and keeper pawls, the pin 40 protruding into the slot 38. It is apparent that with the slot 38 being elongated generally in the direction of the oscillatory movement of cocking pawl 28, the cocking pawl may oscillate relative to the keeper pawl when cocking the rotary knife 20, in the direction of arrow G. However, abutment of the pin 40 against the upper side of the slot 38 will cause both of the pawls to lift off of the ratchet in the direction of arrow H (FIG. 2) generally transverse to the direction of oscillatory movement of the cocking pawl 28.

In the embodiment of the invention shown in FIGS. 1 and 2, a cam member 42 is mounted on the keeper pawl 34 by means of a clamping bolt member 44 extending through a slot 46 in the keeper pawl. The cam member 42 also has a locating tab 48 extending into the slot 46. The cam member 42 has a rearwardly protruding camming flange 50 which is engageable by a camming pin 52 which protrudes forwardly from the drive chain 16. By loosening the clamping bolt member 44 the cam member 42 may be adjusted in the direction of arrow X to vary the point in time when the camming pin 52 strikes the camming flange 50 and thereby adjust the cut paper length.

.Thus, it is apparent that for each revolution of the drive chain 16, the camming pin 52 will come into abutment with the camming flange 50 of the cam member 42 and lift the cocking pawl 28 and keeper pawl 34 off of the ratchet 26, in the direction of arrow H (FIG. 2), to permit the spring 22 to bias the rotary gear 20 in the direction of arrow E to sever a sheet S or section of the paper or sheet material from the length thereof coming off of supply roll 10.

It should be pointed out that the drive chain 16 is operated in a timed cycle with the feed rolls 12a, 12b and the other apparatus of the duplicating machine. It also should be pointed out that the ratchet 26, in essence, is a ratchet whereby the teeth terminate in a smooth override portion 26b at the end of the series of teeth 26a. Thus, engagement of the cocking pawl tooth 280 with the smooth override ratchet portion 26b will not further rotate the ratchet in the direction of arrow G (FIG. 1). In other words, the override portion 26b provides a lost motion means between the ratchet 26 and the cocking pawl 28 at the end of the series of ratchet teeth 26a to permit the cocking pawl to continue to oscillate after the rotary knife 20 has been cocked.

Turning now to the form of the invention shown in FIG. 3, the sprocket 18b, the

feed rollers

12a and 12b, the rotary knife 20 and the ratchet 26 (with ratchet teeth 26a and override portion 26b) are shown with like numerals. However, in this form of the invention, a cocking pawl member 60, having a pawl tooth 60a, and a keeper pawl 62, having a pawl tooth 62a, are independently mounted with no connection therebetween such as the pin 40 and slot 38 of the form of the invention shown in FIGS. 1 and 2. The cocking pawl 60 is mounted by an eccentric member 64 fixed to the feed roller 12b and has a cam arm 66. The eccentric member 64 is rotatably received in an aperture 65 in the cocking pawl 60. The keeper pawl 62 is pivotally mounted by a pin or shaft 68 and has a rearwardly extending camming flange 70.

It has been found that in certain instances it is desirable, in tripping the rotary knife 20, to lift the cocking pawl 60 off of the ratchet 26 prior to lifting the keeper pawl 62 to trip the knife. For instance, this insures that the oscillatory movement of the cocking pawl does not interfere with a sharp or precise release of the knife. To effect this sequential lifting of the cocking and keeper pawls, a rotating gear 72 is provided, with a pair of

camming pins

72a and 72b protruding forwardly and into the path of the cocking pawl cam arm 62 and the keeper pawl camming flange 70, respectively. As seen in FIG. 3, the pins are slightly angularly separated so that the pin 72a engages the cocking pawl cam arm 66 prior to the pin 72b engaging the keeper pawl camming flange 70, as seen in FIG. 3. The rotating gear 72 is driven in the direction of arrow l by a driving gear 74 which is part of a gear train, generally designated 76. The gear train includes an idler gear 78 and a driving gear 80, the latter of which is mounted alongside the sprocket 18b for rotation therewith. The gear train 76 establishes a driving connection from the sprocket 18b to the rotating gear 72 which trips the cocking and keeper pawls. In actual practice, there is an 1 l to I reduction in the gear train.

A Further feature of the invention is the provision of means for initially adjusting the point in time when the pin members 720 and 72b on the rotating gear 72 will engage the cam arm 66 and camming flange on the cocking and keeper pawls, respectively. More particularly, the rotating gear 72 is mounted on a shaft 88 for axial movement in the direction of arrow J (FIG. 4) out of its meshed engagement with driving gear 74 to permit relative rotation between the two gears and thereby adjust the point in time of tripping the rotary knife. In addition, means is provided to limit the amount of adjustment between the

gears

72 and 74 between a given or desired range of cut sheet length. This means includes an annular slot 82 formed in the rotating gear 72 and a pin member 84 radially aligned with the slot and fixed to a frame member 86 of the apparatus. The slot 82 and pin 84 limit the relative rotation between the

gears

72 and 74. More particularly, when the rotating gear 72 is moved in the direction of arrow J, out of mesh with the gear 74, the pin 84 will protrude into the slot 82 and limit the relative adjustment of the gears, as determined by the ends of the slot 82 against which the pin 84 will abut. In actual practice, the slot 82 is so positioned and is of a length which will permit cutting sheets of paper ranging between 5% and 14 inches in length. A spring 90 may be employed to bias the gear 72 toward its meshed position with gear 74. The shaft 88 may protrude through a front housing wall 92 (FIG. 4) for connection to a control knob 94 for manual manipulation by operators of the device.

FIGS. 5 and 50 show a further modification of the structure shown in FIGS. 3 and 4. Like numerals will be applied where applicable. In this form of the invention, a control knob 94' is disposed on the front end of the shaft 88. The rotating gear 72 is disposed behind the cam arm 66 and the camming flange 70. Thus, a plate 94 has pins 94a and 94b for engaging the cam arm 66 and the camming flange 70, respectively, to provide the aforesaid sequential release of the cocking pawl 60 and the keeper pawl 62. To unmesh and adjust the rotating gear 72, the knob 94' is pushed in the direction of arrow M and rotated to adjust the relative positions of the

gears

72 and 74, for the purpose described in full above.

The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations should be understood therefrom as some modifications will be obvious to those skilled in the art.

We claim 1. A severing mechanism, comprising:

a rotatably mounted knife;

means biasing said knife in one direction of rotation for cutting purposes;

ratchet means operatively associated with said rotary knife;

pawl means engageable with said ratchet means to rotate said knife opposite said one dire(tion and hold the knife in a cocked condition; and

trip means to disengage said pawl means from said ratchet means to release said knife and permit said biasing means to rotate the knife in said one direction for cutting purposes.

2. The severing mechanism of claim 11 wherein said ratchet means includes a series of ratchet teeth, and said pawl means includes a cocking pawl oscillatably mounted for incrementally rotating said knife to its cocked condition by engaging said teeth seriatim and a keeper pawl engageable with said teeth to prevent rotation of said knife on the back strokes of said oscillating cocking pawl.

3. The severing mechanism of claim 2 including a lost motion connection means between said cocking and ill:

keeper pawls to permit said cocking pawl to oscillate relative to said keeper pawl when cocking said knife but to cause one of said pawls to lift off of said ratchet means when the other pawl is moved off of the ratchet in a direction transverse to the direction of oscillatory movement of said cocking pawl.

4. The severing mechanism of claim 3 including means biasing one of said pawls in said transverse direction against said ratchet means.

5. The severing mechanism of claim 3 wherein said trip means includes cam means on one of said pawls engageable by an appropriate complementary cam means to disengage said pawls from said ratchet means.

6. In combination with the severing mechanism of claim 5, a drive system which includes said trip means, said drive system including said complementary cam means.

7. The combination of claim 6 wherein said drive system includes an endless drive chain member having at least one protruding pin member fixed thereto at a point therealong, said pin member comprising said complementary cam means for engaging the cam means on said one pawl in response to movement of the drive chain member to trip the rotary knife in a timed relationship with said drive system.

8. The combination of claim 6 wherein said drive system includes a rotating member having at least one protruding pin member fixed thereto for rotation therewith, said pin member comprising said complementary cam means for engaging the cam means on said one pawl in response to rotation of said rotating member to trip the rotary knife in a timed relationship with said drive system.

9. The combination of claim 8 wherein said rotating member comprises a rotating gear in meshed engagement with a driving gear in said drive system, and including means to selectively disengage said gears to permit relative rotation therebetween and thereby adjust the point in time when said pin member will engage said cam means to trip the rotary knife.

10. The combination of claim 9 wherein said rotating gear is mounted for selective axial movement to provide for disengagement from said driving gear, and including means operatively associated with said rotating gear when disengaged from said driving gear to limit the relative rotation of the gears.

11. The combination of claim 10 wherein said last named means includes an annular slot in said rotating gear and a fixed pin member which extends into the slot when the rotating gear is disengaged from said driving gear, the fixed pin member being removed from the slot when the gears are in mesh.

ll2. The combination of claim 2 wherein said ratchet means has an override portion at the end of said series of teeth providing a lost motion means between the ratchet means and said cocking pawl to permit the cocking pawl to continue to oscillate after said knife has been cocked.

13. The combination of claim 2 wherein said trip means includes a first portion operatively associated with one of said pawls and a second portion operatively associated with the other of said pawls and means to actuate said first portion prior to actuating said second portion to lift one pawl off of the ratchet means prior to the other pawl.

14. The combination of claim 13 wherein said trip means includes a rotating member having a pair of pins said cocking pawl to lift the cocking pawl off of the ratchet means before the keeper pawl so that the oscillatory movement of the cocking pawl does not interfere with sharp release of said knife.

Claims

1. A severing mechanism, comprising: a rotatably mounted knife; means biasing said knife in one direction of rotation for cutting purposes; ratchet means operatively associated with said rotary knife; pawl means engageable with said ratchet means to rotate said knife opposite said one dire(tion and hold the knife in a cocked condition; and trip means to disengage said pawl means from said ratchet means to release said knife and permit said biasing means to rotate the knife in said one direction for cutting purposes.

2. The severing mechanism of claim 1 wherein said ratchet means includes a series of ratchet teeth, and said pawl means includes a cocking pawl oscillatably mounted for incrementally rotating said knife to its cocked condition by engaging said teeth seriatim and a keeper pawl engageable with said teeth to prevent rotation of said knife on the back strokes of said oscillating cocking pawl.

3. The severing mechanism of claim 2 including a lost motion connection means between said cocking and keeper pawls to permit said cocking pawl to oscillate relative to said keeper pawl when cocking said knife but to cause one of said pawls to lift off of said ratchet means when the other pawl is moved off of the ratchet in a direction transverse to the direction of oscillatory movement of said cocking pawl.

12. The combination of claim 2 wherein said ratchet means has an override portion at the end of said series of teeth providing a lost motion means between the ratchet means and said cocking pawl to permit the cocking pawl to continue to oscillate after said knife has been cocked.

14. The combination of claim 13 wherein said trip means includes a rotating member having a pair of pins protruding from one side threof and comprising said first and second portions, said pins being slightly angularly separated.

15. The combination of claim 13 wherein said second portion of the trip means is operatively associated with said cocking pawl to lift the cocking pawl off of the ratchet means before the keeper pawl so that the oscillatory movement of the cocking pawl does not interfere with sharp release of said knife.