US2345072A

US2345072A - Cutoff machine tripping mechanism

Info

Publication number: US2345072A
Application number: US409214A
Authority: US
Inventors: John R Rosenleaf; Emmett D Benham
Original assignee: JB Ehrsam and Sons Manufacturing Co
Current assignee: JB Ehrsam and Sons Manufacturing Co
Priority date: 1941-09-02
Filing date: 1941-09-02
Publication date: 1944-03-28
Anticipated expiration: 1961-03-28

Description

w March 28, 1944. J. R. ROSENLEA ET AL 2,345,072

CUTOFF MACHINE TRIPPING MECHANISM Filed Sept. 2, 1941 3 Sheets-Sheet 1 INVENTOR. n/OHN R. ROJE/YLE/iF' 4m;

March 28, 1944. ROSENLEAF ET AL 2,345,072

CUTOFF MACHINE TRIPPING MECHANISM Filed Sept. 2,

1941 3 Sheets-Sheet 2 BY Q March 28, 1944.

.1. R. ROSENLEAF ET AL CUTOFF MACHINE TRIPPING MECHANISM Filed Sept. 2, 1941 s Shets-Sheet s I N\ TNTORS. Jim/v A. Pasi/vziifarzd Patented Mar. 28, 1944 CUTOFF MACHINE TRIPPING MECHANISM John R. Rosenleaf and Emmett D. Benham, Enterprise, Karla, assignors to The J. B.

Ehrsam & Sons Manufacturing Company,

Enterprise, Kans., a corporation of Kansas Application September 2, 1941, Serial No. 409,214

21 Claims.

It is the primary object of the present invention to simplify the construction and control of cut-01f machines particularly of the type primarily intended for use upon plaster board and the like and in which it is oftendesirable to cause the machine to sever the work upon one revolution and to perforate the work upon another revolution. The machine of the present invention is likewise capable of cutting or perforating the work at intervals which are not even multiples of the circumference of the knife orbits. A further object of the invention is to provide, in a machine of the character here under consideration and having a plurality of knives mounted on a continuously operating rotor, means for automatically preventing damage to the work by contact with those knives during non-active periods of the machine, while insuring against bending of the work under the influence of the knives at the time of coaction of the knives to cut or perforate the work.

Further objects of the invention will appear as the description proceeds.

To the accomplishment of the above and related objects, my invention may be embodied in the form illustrated in the accompanying drawings, attention being called to the fact, however, that the drawings are illustrative only, and that change may be made in the specific construction illustrated and described, so long as the scope of the appended claims is not violated.

Fig. 1 is an elevation of the machine of the present invention;

Fig. 2 is an elevation taken from the left-hand end of Fig. 1;

Fig. 3 is a section taken substantially on the,

line 3-3 of Fig. 1 and looking-in the direction of the arrows;

Fig. 4 is a fragmental section taken substantially on the line 44 of Fig. 1 and looking in the direction of the arrows; and

Fig. 5 is an elevation, upon an enlarged scale, of the left-hand end of Fig. 1.

Referring more particularly to the drawings, it will be seen that we have illustrated a machine very similar in many respects to the machine disclosed in our Patent 2,288,921 issued July 7, 1942; but that, in the present disclosure, the transaxially-shiftable rotor carries only one knife, the fixed-axis rotor is continuously driven, the trip mechanism for connecting the firstmentioned rotorto be driven is quite different, and the driving train and ,control for the rotorshifting cam is difieren. Too, in the present disclosure. we have provided a work-supporting cradle, shiftable in accordance with the operation of the upper rotor, and finding no counterpart in our said patent.

In Figs. 1 and 5 there will be seen the machine bed H) mounted on feet It and supporting end frames 12 and I3 in which the ends l4 and I5 of lower rotor 16 are solidly journalled. The rotor 16 carries four knives l1, l8, I9, and 20, spaced apart on its periphery.

One or more brackets 21 provide support for a countershaft 22 to which is keyed sprocket 23 driven by chain 24 from sprocket 25 on, for instance, the spindle 26 of a motor 21. Said countershaft 22 carries a pinion 28 meshing with a gear 29 carried on a continuation 30 of the end 14 of rotor I6, to provide a solid continuous drive for the rotor I6.

A continuation 3| of the end l5 of the rotor 16 is journalled in a supplemental end frame 32 mounted on the bed l0, and carries a gear 33 continuously meshing with a gear 34 of equal pitch diameter mounted on a stub shaft 35 journalled in the frame member 32. To one face of the gear 34 is secured one member 36 of an "Oldham coupling of well-understood construction, while the mating element 31 of said coupling has secured to its outer face a jaw clutch element 38. The

elements

31 and 38 are loosely mounted on a projection 39 of one end 40 of an upper rotor 4|, the end 40 and 42 of said rotor being journalled in suitable bearings in bearing carriages slidably mounted respectively in the

end frames

12 and 13 in the manner illustrated in Fig. 3.

As is clearly shown in Figs. 1, 3, and 5, the end 40 of rotor 4| is journalled in a slide plate 43 guided for vertical movement in a guideway 44 formed in the end frame l3, said plate being supported by a spring 45. The opposite end 42 of said rotor is similarly mounted, so that said rotor is transaxially shiftable toward and away from the rotor l6.

Integral with, or fixedly secured to, the plate 43 is a platform 46, formed to provide two

hinge lugs

41, 41, in which is received a pintle 48 to which are fixed a pair of

yoke arms

49, 49 provided with shoes 50, 50. diametrically oppositely received in an annular groove 5| formed in a clutch element "52 fixed on extension .39 and adapted to mate with clutch element 38. At least one of said arms is provided with. an extension 53 with which is associated a coiled spring 54 urging said yoke arms to swing in a counterclockwise direction; as viewed in Figs. 1 and 5, to move said clutch element 52 into cooperative relation with the element 38; but said element 52 is normally restrained against such movement and held in the position illustrated in Figs. 1 and 5 by the engagement of a trip dog 55 with the thickened portion 56 of an annular cam collar 51 integral with or fixed to said element 52.

As is clearly shown in Figs. 1, 3, and 5, the dog 55 is reciprocably mounted in a lug 58 carried on said platform 46, and is held in position by a finger 59 on a rockshaft 66 journalled in bearings 6|, 6| depending from the platform 46, and carrying a lever 62 with which is associated a coiled spring 63 tending to rotate said lever in a clockwise direction as viewed in Figs. 1 and 5, and thereby holding the dog 55 in its illustrated position.

It will be obvious that the driving train thus far described will produce continuous rotation of the rotor i5, and will effect rotation of the rotor 4| only when the clutch element 52 is engaged with the clutch element 33; and that the provision of the Oldham coupling permits the transmission of movement from the stub shaft 35 to the rotor 4| whether or not those members are in axial alignment. A single knife 64 is carried by the rotor 4 I.

In the illustrated positions of the parts, the dog 55 cooperates with the thickened portion 56 of the cam collar 51 to hold the clutch element 52 out of engagement with the element 38. counterclockwise movement of the lever 62, however, in opposition to the spring 63, will withdraw the dog 55 to permit the spring 54 to move the element 52 into cooperative relation with the constantly rotating element 38 to drive the element 52 and the rotor 4|. If the lever 62 is now promptly released, the spring 63 Will urge the dog 55 into engagement with the peripheral surface of the collar 51 of the rotating element 52; and as said element rotates, the thin portion of the collar will come into registry with the dog 55 to permit said dog to move upwardly into contact with the left-hand, cammed face of said collar. Thus, as the rotor 4| approaches completion of a revolution, the dog 55, acting on the cammed face 56 of the collar 51, will shift the element 52 to the right to disengage said element from the element 33. Preferably, a springpressed brake 55 is associated with a projecting portion of the end 42 of the rotor 4| to stop said rotor promptly upon disengagement of said clutch elements, the brake 65 being mounted to partake of the transaxial movement of the rotor4l.

Beyond the supplemental end frame 32, the extension 3| carries a bevelled gear 66 meshing with a gear 61 fixed on a shaft 68 journalled in

suitable brackets

69 and 16. The shaft 68 carries a sprocket 1! connected, by a chain 12 to drive a

double sprocket

13, 14 suitably journalled on the machine frame. The chain 12 engages the portion 13 of the last-named sprocket; and a control chain 15 hangs loosely on the sprocket portion 14, said chain 15 carrying one or more suitably positioned trip elements 16. It will be clear from the above that the chain 15 is driven with the continuously rotating rotor 6, and, at predetermined points in the cycle of the rotor l6, a trip element 16 will be caused to engage the lever 62 to swing the same in a counterclockwise direction to withdraw the dog 55 to permit engagement of the clutch element 52 with the element 38, and that thereupon the rotor 4| will be turned through one revolution, upon the completion of which the now-released dog 55 will cause disengagement of the element 52 from the element 38, and the brake 65 will stop the rotor 4|.

Of course, the chain 15 will be so associated with the sprocket 14 as to trip the clutch mechanism at a time such as to bring the knife 64 into vertically downwardly directed position at a time to cooperate with one of the knives on the rotor l6. It will be obvious that the chain 15 can be so designed and proportioned as to cause the knife 64 to cooperate with any one of the knives 0n the rotor |6 upon each revolution of the rotor l6, or to cooperate with successive knives on the rotor l6. Thus, depending upon the selection of a chain 15 of suitable length or with suitably spaced trip elements 16, the rotor 4| can be caused to make one revolution for each revolution of the rotor I6, or one revolution for each one and one-fourth revolutions of the rotor IE, or one revolution for each one and one-half revolutions of the rotor l6, or one revolution for each one and three-fourths revolutions of the rotor H5, or one revolution for any other number of revolutions of the rotor I6 in the same arithmetical progression. Thereby, the machine can be caused to cut material traveling therethrough to any desired length greater than the periphery of the orbit of the knives on the rotor |6 by any desired multiple of one-fourth that length.

It is often desirable, particularly in working upon plaster board, to cause a cut-off machine to perforate the board at stated intervals between severing operations. It is for that reason that the rotor 4| is mounted for transaxial movement relative to the rotor l6, and we have provided means for automatically shifting the rotor 4| between that position in which the knife 64 will cooperate with one of the knives 0n the rotor I6 to sever the board and that position in which the knife 64 will cooperate with one of the knives on the rotor l5 merely to perforate the board without severing it. Referring, again, to Fig. 3, it will be seen that the slide plate 43 mounts a roller 11 adjacent its upper end, and that a cam 18 engages said roller to hold the slide plate 43 down against the tendency of the spring 45. It will be obvious of course that the other end 42 of the rotor 4| is journalled in a similar slide plate provided with a similar roller with which cooperates a similar cam which is carried on the same cam shaft 19 with the cam 18.

On the countershaft 22 is fixed a sprocket which drives, through a chain 8|, a sprocket 82 fixed on a tubular shaft 83 suitably journalled in the end frames l3 and 32. Fixed to the shaft 83 is a clutch member 84 very similar to the member 52, and similarly provided with a cam collar 85 having a thickened portion 86, and with an annular groove 81.

Yoke arms

88, 88 are mounted upon a suitable rock shaft 89 journalled upon a bracket 96 carried by the end frame 32, and said arms are received in the groove 81. At least one of said arms is formed with an extension 9! with which cooperates a coiled spring 92- urging the yoke arms to swing in a counterclockwise direction. Reciprocably mounted in the bracket 98 is a trip dog 93 cooperating with the collar 85 normally to hold the clutch element 84 in the illustrated position. Likewise journalled in the bracket 95, and in an additional bearing 94-, is a rock shaft 95 to which is fixed a lever 96 engaging the dog 93, said shaft being resiliently held, by means of a spring 91, in the illustrated position. A lever 98 fixed, to the shaft 95, is disposed in the, path of trip elements 99 carried by a chain I supported on a double sprocket-NI,

I02 driven, by a chain. |03 from a sprocket I04- on the shaft 68. 1

A clutch element I05 is mounted upon a shaft I06 concentric with the shaft 83. When the lever 96 is tripped, the dog 93 will be withdrawn to permit the clutch element 84 to engage the clutch element I05 to drive the shaft I06 through a single revolution, upon the completion of which, the dog 93, cooperating with the thickened portion 86 of the cam collar 85, will disengage the element 84 from the element I05. A sprocket I01 on the shaft I06 is connected by'achain I08 to drive sprocket I09 on the cam shaft I9.

; It is here to be noted that the gear ratio between the pinion 28 and gear 29 is one to two, so that two revolutions of the countershaft :22 will produce one revolution of the rotor I6; the gear ratio between the. sprocket 80 and the sprocket 82 is one to two, so that two revolutions of the countershaft 22 will produce one'revolution of' the tubular shaft 83; and the gear ratio betweenthe sprocket I01 and I09 is one .to two, sothattwo revolutions of the countershaft 22 will produce one-half revolution .of the cam shaft 19'. Thus, each time the lever 98 is tripped, the cam shaft I9 will be turned through. one-halfrevolution. Thus, if the trip elements 99 are so arrangedas to trip the lever 98 each time the lever 62 is tripped, the machine will sever the work upon odd revolutions of the rotor 4|, and will perforate the work upon even revolutions of the rotor 4|. Alternatively, of course, the stops 99 maybe so set on the chain I60 as to cause the machine to perforate anydesired number of times between severing operations, or to sever any desired number of times between perforating operations.

Because the rotor I6 with its. four knives is continuously rotating, it is desirable to elevate the work normally into a plane outside the orbit of the knives on the rotor I5, so that said knives shall not mutilate or scar the work between the points at which the machine severs or--perforates the work. On the other hand, it is undesirable to hold the work outside the orbit of the knives on the rotor I6 during severing or perforating operations, because if the work were so supported, the effect of the knife 64 would be to .bend'th'e work downwardly, between the points of support, and into the orbit of the knives on the rotor I6. Therefore, we have provided a cradle for the work comprising idle rollers H0 and III supported in a frame work II2, and positioned on opposite sides of the vertical plane including the axesof the rotor I6 and 4|. Theframe H2, in turn, is supported upona frame comprising uprights H3 and I I4, an upper cross bar I I5, and alower cross bar II6. A two-part slide II'I is reciprocably mounted between the frame elements H3 and H4, being held in adjusted position therein between bolts II8 and H9, said bolts being oper-. ,able to adjust the position of the frame I I2 with respect to the end 42 of the rotor 4|, Suitably fixed to the rotor end 42, and rotatable within the slide 1, is an eccentric ring I20. It will be seen that rotation of the rotor-end 42 and the ring I20 will cause reciprocation of the cradle with its rollers. I I0 and III, with respect to the axis of the rotor 4|. The opposite end of the cradle is similarly supported by a frame work- I2I associated with the end 40 of the rotor 4|; and legs I22 are secured to element 2 and slidably engage the uprights of the frame mem-- ber|2.

When the rotor 4| is in the position illustrated,-

trated in Fig. 4, in which the rollers I I0 and III will be at their minimum distance below the axis of the rotor 4|, and in which position, work supported upon the rollers H0 and III will be disposed outside the orbit of the knives on the rotor I6. .As the rotor 4| is rotated, the cam ring I20 will be, rotated therewith; so that, asthe knife 64 approaches a vertically downward position, the frame -I I2 will be moved downwardlywith respect to the rotor 4|, whereby theupper surfaces of the rollers H0 and III will fall below th horizontal plane tangent with the orbit of the knives on the rotor I6, so that it will be unnecessary for the knife .64 to bend the work downwardly intov engagement with the cooperating knife on the rotor l6; As the knife 64 moves beyond its vertically downward position, the eccentric ring I20 will begin to elevate the framel I2, and the work will be movedout of the orbit of the knives on the rotor I|6 before the next adjacentknife onsaid rotor comes into a vertically .upwardiposition.

- It will be obvious that the minimum length of material which can be cut with the present machine is determined by the periphery of the orbit of the cutting edge of the knife 64. In prac-, tice, this length is usually 48 inches. Since the rotor I6 is provided with four knives, equally spaced, it will be obvious that the machine is capable of cutting lengths greater than48 inches by any desired multiple of 12 inches.

Because the

clutches

38, 52,"and 84, I05 are four-jaw clutches, it is possible to trip the machine at' any time within one quarter of a-revo lution of the desired cutting position, and still get an accurately positioned cut, because the rotor 4| or the cam shaft 19 will not start to move until the completion of the quarter revolutio I during which the machine is tripped It is our present belief that the trip mechanism including the chain I5 and the lever arm 62 will operate satisfactorily and with sufficient accuracy, even though the sprocket I4 is mounted upon a fixed axis, while the lever 62 moves somewhat in, a vertical direction. Of course it will be obviously possible, without invention, to support the double sprocket'I3, I4 from the platform 46, providing any suitable means, such; for instance, as a resiliently biased idler sprocket, to compensate, in the chain I2, for variations in the center distance between the shaft 68 and the sprocket I4 resulting upon such modification.

We claim as our invention:

1. A cut-off machine comprising a pair of knife-carrying rotors, aplurality of knives carried by one of said rotors, a single knife carried .by the other of said rotors, and means for driving said rotors, including means for selectively disconnecting said last-named rotor from said driving means and reconnecting the same in timed relation to cause said single'blade to cooperate with any one of said plurality of blades.

2. A cut-off machine comprising a pair 0 knife-carrying rotors, a plurality of knives carried by one of said rotors, a single knife carried by the other of said rotors, means for transaxially shifting one of said rotors,'and means for driving said rotors, including means for selectively disthe eccentric ring 1 I 20 will be in the position illus by the other of said rotors, means for transaxially shifting one of said rotors, and means for driving said rotors, including means for selectively disconnecting said last-named rotor from said driving means and reconnecting the same in timed relation to cause said single blade to cooperate with any one of said plurality of blades, and means for varying the cycle of said shifting means.

4. In a cut-oil machine, a lower rotor, at least one knife on said rotor, means for continuously driving said rotor, an upper rotor, at least one knife on said upper rotor, means for driving said upper rotor, means for varying the center distance between said rotors, a work support arranged between said rotors and adapted normally to support work out of cooperative relation with said knives, and means dominated by said center distance varying means for shifting said work support toward one of said rotors upon reduction in such center distance.

5. In a cut-off machine, a lower rotor, at least one knife on said rotor, means for continuously driving said rotor, an upper rotor, at least one knife on said upper rotor, means for shifting one of said rotors toward and away from the other of said rotors, a work support arranged between said rotors and adapted normally to support work out of cooperative relation with said knives, and eccentric means on said upper rotor supporting said work support for transaxial movement with respect to both of said rotors.

6. In a cut-off machine, a lower rotor, at least one knife on said rotor, means for continuously driving said rotor, an upper rotor, at least one knife on said upper rotor, means for shifting one of said rotors toward and away from the other of said rotors, a cradle formed to provide a rest over which work may move between said rotors, eccentric means associated with said upper rotor and supporting said cradle, said eccentric means being transaxially shiftable with said upper rotor to shift said cradle transaxially with respect to said lower rotor, and rotatable with said upper rotor to shift said cradle transaxially with respect tosaid upper rotor.

7'. In: a cut-off machine, a first" knife-carrying rotor, means for continuously driving said rotor, a. second knife-carrying rotor, means for inter-- mittently driving said second rotor, a work sup port arranged between said rotors and adapted normally to support work out of contact with the knives of both rotors, and automatic means for shifting, said work support, when said second r0.- tor is driven, to bring work supported thereonwithin. the paths of the knives of both rotors.

8; In a. cut-off machine, a fixed-axis rotor, at least one knife carried by said rotor, means for continuously driving said rotor, asecond rotor, at least oneknife carried by said second rotor, means- 1" or intermittently driving. saidsecond rotor, means for transaxia'lly shifting saidisecond rotor, a work support arranged between said rotors and adapted normally to support work outside the path of any knife carried on said lower rotor, and automatic means for shiftingv said work support. when said. second rotor isdriven, intoa position in which work supported thereon is. disposed within, the pathsof the knives. of both. rotors.

9. In a cut-off machine, a. first rotor, a plurality of knives carried thereon, means for driving said first rotor;. at second rotor, a, single knife; carried on said second rotor, a drive train for said. second rotor including a, single-revolutionclutch, and meansdrivenwith said first-rotor fori tripping said clutch at a predetermined point in the; cycle of said first rotor.

10. In a cut-off machine, a first rotor, a plu-- rality of knives carried thereon, means for driving said first rotor, at second rotor, a single knife carried on said second rotor, a drive train for said second rotor including a single-revolution clutch, and means driven with said first rotor and operable to trip said clutch at any of a plurality of predetermined'points in the cycle of said first rotor.

11. In a cut-off machine; a fixed-axis rotor, at least one knife carried by said rotor, means for continuously driving said rotor, a second rotor, at least one knife carried by said second rotor, means for intermittently driving said second rotor, means for transaxially shifting said second rotor, a Work support arranged between said rotors and adapted normally to support work outside the path of any knife carried on said lower rotor, and automatic means for shifting said work support, when said second rotor is driven, into a position in which work supported thereon is disposed within the paths of the knives of both rotors, said last-named means being alternatively operable to cause said one blade on said second rotor to coact with any one of said plurality of blades on said first rotor.

' 12. In a cut-off machine, a first rotor, a plurality of knives carried thereon, means for driving said first rotor, a second rotor, a single knife carried on said second rotor, a drive train for saidsecond rotor including a single-revolution clutch, means driven with said first rotor for tripping said clutch periodically, means for mechanically varying the center distance between said rotors, including a. rotary element, a drive train for said rotary element includinga second single-revolution clutch, and means driven with said first rotor for tripping said second clutch.

13. In a. cut-off machine, a first rotor, a plurality of knives carried thereon, means for driving said first rotor, a second rotor, a single knife carried on said second'rotor, a drive train for said second rotor including a single-revolution clutch, means driven with said first rotor for tripping said clutch periodically, means for me-- chanically varying the center distance between said rotors, including a rotary element, a drive train for said rotary element including speed reducing mechanism andfurther including a second single-revolution clutch, and means driven with. said first rotor for tripping said second clutch.

14. In a cut-off machine, a first rotor, a plu- 1 I rality of knives carriedthereon, means for driving said first rotor, a second rotor, a single knife carri'ed' on said second rotor, a drive train for said second rotor including a single-revolution clutch,

means driven with said first rotor for tripping said clutch periodically, means for mechanicallyvarying the center distance between said rotors including a rotary cam cooperating with one of said rotors and having one position in which the orbits of the knives on the two rotors intersect and a diametrically-opposite position in which the adjacent points" in such orbits are separated but by' a distance less than the thickness of the work being operated upon by the machine, a drive. train for said cam including speed reducing mechanism designed to produce one-half revolution of said cam during one revolution of said first rotor and further including asecond single-revo-- lution clutch, and means driven with saidv first rotor for tripping. said second clutcln 15. In a out-01f machine, a first rotor, a plurality of knives carried thereon, means for driving said first rotor, a second rotor, a single knife carried on said second rotor, a drive train for said second rotor including a single-revolution clutch, means driven with said first rotor for tripping said clutch periodically, means for mechanically varying the center distance between said rotors, including a rotary cam cooperating with one of said rotors and having one position in which the orbits of the knives on the two rotors intersect and a diametrically-opposite position in which the adjacent points in such orbits are separated but by a distance less than the thickness of the work being operated upon by the machine, a drive train for said cam including speed reducing mechanism designed to produce one-half revolution of said cam during one revolution of said first rotor and further including a second single-revolution clutch, and means driven with said first rotor and operable to trip said second clutch at any of a plurality of predetermined points in the cycle of said first rotor.

16. In a cut-off machine, a first rotor, a plurality of knives carried thereon, means for driving said first rotor, a second rotor, a single knife carried on said second rotor, a drive train for said second rotor including a single-revolution clutch, means driven with said first rotor and operable to trip said clutch at any of a plurality of predetermined points in the cycle of said first rotor to cause said one blade on said second rotor to coact with any one of said plurality of blades on said first rotor, means for mechanically varying the center distance between said rotors, including a rotary cam cooperating with one of said rotors and having one position in which the orbits of the knives on the two rotors intersect and a diametrically opposite position in which the adjacent points in such orbits are separated but by a distance less than the thickness of the work being operated upon by the machine, a drive train for said cam including speed reducing mechanism designed to produce one-half revolution of said cam during one revolution of said first rotor and further including a second single-revolution clutch, and means driven with said first rotor and operable to trip said second clutch at any of a plurality of predetermined points in the cycle of said first rotor.

17. In a cut-off machine, a fixed-axis rotor, a plurality of knives carried on said rotor, means for continuously driving said rotor, a second rotor, a single knife carried on said second rotor, a drive train for said second rotor including a single-revolution clutch, means driven with said first rotor and operable to trip said clutch at any of a. plurality of predetermined points in the cycle of said first rotor, means for transaxially shifting said second rotor, including a rotary cam cooperating with said second rotor and having one position in which the orbits of the knives on the two rotors intersect and a diametrically opposite position in which the adjacent points in such orbits are separated but by a distance less than the thickness of the work being operated upon by the machine, a drive train for said cam including a second single-revolution clutch, and means driven with said first rotor and operable to trip said second clutch at any of a plurality of predetermined points in the cycle of said first rotor, a work support arranged between said rotors and adapted normally to support work outside the orbit of the knives on said lower rotor, and automatic means for shifting said work support, when said first clutch is tripped, into a position in which Work supported thereon is disposed within the orbits of the knives on both rotors.

18. A cut-01f machine comprising a pair of knife-carrying rotors, a plurality of knives carried by one of said rotors, a single knife carried by the other of said rotors, means for cyclically transaxially shifting one of said rotors in a predetermined relation to the cycle of operation of said other rotor, and means for varying said relation to bring said one knife selectively into coaction with any one of said plurality of knives.

19. In a cut-off machine, a first knife-carrying rotor, means for continuously driving said rotor, a second knife -carrying rotor arranged in cooperative relation with said first rotor, and means for intermittently driving said second rotor to cause rotation thereof in any desired one of a plurality of phase relations to said second rotor.

20. In a cut-off machine, a first rotor, a plurality of knives carried thereon, means for continuously driving said first-rotor, a second rotor, a single knife carried on said second rotor, a driving train for said second rotor only, including a single-revolution clutch, and means driven in synchronism with said first rotor for tripping said clutch at a predetermined point in the cycle of said first rotor.

21. In a cut-off machine, a first rotor, a plurality of knives carried thereon, means for driving said first rotor, a second rotor, a single knife carried on said second rotor, a drive train for said second rotor including a single-revolution clutch, and means operable to trip said clutch at any of a plurality of predetermined points in the cycle of said first rotor.

JOHN R. ROSENLE AF. EMME'IT D. BENI-IAM.