US3675761A

US3675761A - Automatic cigarette feed machine having a vacuum belt conveyor

Info

Publication number: US3675761A
Application number: US61347A
Authority: US
Inventors: Floyd V Hall
Original assignee: Liggett and Myers Inc
Current assignee: Liggett Group LLC
Priority date: 1970-08-05
Filing date: 1970-08-05
Publication date: 1972-07-11
Anticipated expiration: 1989-07-11

Abstract

The first conveyor which moves the single file of cigarettes upwardly uses an endless belt made of a flexible material with apertures spaced along the path thereof and an evacuation chamber over which the belt slides. The belt serves to cover over the evacuation chamber while the suction force created within the chamber draws air through the apertures in the belt to hold a cigarette thereon. Each cigarette which is positively held on the belt under suction serves to hold a number of cigarettes in front on the conveyor belt.

Description

United States Patent Hall [54] AUTOMATIC CIGARETTE FEED MACHINE HAVING A VACUUM BELT CONVEYOR [72] Inventor: Floyd V. Hall, Durham, N.C.

[73] Assignee: Llggett & Myers Incorporated, New York,

22 Filed: Aug. 5, 1970 21 Appl.No.: 61,347

[52] US. Cl ..l98ll84 51 Int. ("I 365 15/00 [58] FieldofSear-ch ..l98/l84, 193

[56] References Cited UNITED STATES PATENTS 3,282,586 11/1966 Schwebel ..l98/l93 X [451 July 11, 1972 Schmitt 198/ 1 84 ..l98/184 ..l98/l84X 2,639,025 5/1953 3,277,558 1 H1969 Fleischauer.... 2,362,168 11/1944 Stokes Primary Examiner-Joseph Wegbreit Assistant Examiner-H. S. Lane Attorney-Kenyon & Kenyon, Reilly, Carr & Chapin ABSTRACT The fu'st conveyor which moves the single file of cigarettes upwardly uses an endless belt made of a flexible material with apertures spaced along the path thereof and an evacuation chamber over which the belt slides. The belt serves to cover over the evacuation chamber while the suction force created within the chamber draws air through the apertures in the belt to hold a cigarette thereon. Each cigarette which is positively held on the belt under suction serves to hold a number of cigarettes in front on the conveyor belt.

13Clalms,4l)rawingfigures PKTENTEDJUL 1 1 1972 SHEET 2 OF 2 INVENTOR. F oyo 1 4L AUTOMATIC CIGARETTE FEED MACHINE HAVING A VACUUM BELT CONVEYOR This invention relates to a cigarette transfer apparatus. More particularly, this invention relates to a conveyor for a cigarette transfer apparatus. Still more particularly, this invention relates to an inclined conveyor for conveying a series of cigarettes in an inclined path in an automatic cigarette transfer machine.

Various techniques and systems have been known for conveying a cigarette from a cigarette making machine to a cigarette packaging machine. For example, systems have been known in which the made cigarettes have been deposited into trays and the trays have thereafter been placed, usually manually, onto conveyors for transport to a packaging machine. However, these systems have required considerable time and eflort in order to convey large numbers of cigarettes from a cigarette making machine to a cigarette packaging machine and as a result such has been relatively expensive and has added to the cost of the cigarettes which are to be sold. As a result, other systems have been devised which rely on mechanized techniques to move the cigarettes from the making machines to the packaging machines. However, these systems have usually been limited in the rate of output so that more than one conveyor system has been required in order to convey the output of two or more cigarette making machines to a single cigarette packaging machine.

In order to overcome the disadvantages of these above systems, various types of conveyors have been proposed for feeding cigarettes directly from a cigarette making machine to a cigarette packaging machine. For example, in some instances it has been known to discharge the output of a single cigarette making machine onto a plurality of runs which are operated to stack the cigarettes into three rows for passage into a packaging machine so as to provide a conventional cigarette package. In another case, cigarettes have been moved in bulk along a conveyor system either longitudinally or vertically into a hopper of a packaging machine. However, such systems have generally been limited to a slow rate, for example, 1200 packaged cigarettes per minute. Further, in the case where the cigarettes have been conveyed in bulk, a substantial percentage of the cigarettes have been damaged due to crushing and the like during transportation. In other cases, it has been known to utilize a chain conveyor to convey cigarettes from the making machine to a packaging machine. However, in these machines, the feed rate has been confined to relatively low rates since an increase in speed has frequently caused the cigarettes being conveyed to fall from the conveyor due to vibration. Also, the vibration has caused skewing of the cigarettes on the conveyor which can lead to jamming of the conveyor and damaging of the cigarettes.

Accordingly, it is an object of this invention to convey a single file of cigarettes on an inclined plane.

It is another object of this invention to provide an apparatus for conveying a single file of cigarettes upwardly .on an inclined plane from a cigarette making machine towards a cigarette packaging machine.

It is another object of the invention to convey a single row of cigarettes on an upwardly directed plane without crushing of the cigarettes.

It is another object of the invention to convey a series of cigarettes at high speed.

Briefly, the invention provides a cigarette transfer apparatus which delivers the output of a high speed cigarette making machine directly to a high speed cigarette packaging machine in a one-to-one relationship. The apparatus includes a pair of conveyors which are connected in series to convey the cigarettes from the making machine first in an upwardly directed plane and then into a horizontal plane for depositing into a hopper of the cigarette packaging machine. The inclined conveyor is constructed so that the cigarettes are conveyed in a free manner so as to avoid crushing of the cigarettes during conveyance while the horizontally disposed conveyor conveys the cigarettes in a loosely bulked manner.

The transfer apparatus is constructed so that the entire output of the cigarette making machine can be directed in a steady stream into the hopper of the cigarette packaging machine without interruption.

The inclined conveyor is constructed to move a row of cigarettes on an inclined plane in an upward direction under a suction force which retains the cigarettes on the conveyor belt. To this end, the conveyor belt can be fonned of any suitable flexible material and can be provided with a series of apertures which communicate with an evacuation chamber positioned between the rollers of the conveyor between the upper and lower reaches of the conveyor belt. The evacuation chamber is exposed at the upper side to the conveyor belt and serves to draw air through the apertures in the belt into the evacuation chamber. By thus drawing air through the belt, a cigarette can be drawn under suction against the aperture in the belt and retained over the aperture. The spacing between the apertures and the belt are such that a number of cigarettes in front of the retained cigarettes will be held on the belt by the positively retained cigarette acting as a stop. The evacuation chamber is further constructed so as to be in open communication with the upper reach of the conveyor belt throughout the length of the reach as well as throughout an upper section of the belt which is curved about the conveyor rollers. In this way, the point from which the cigarettes are deposited onto the horizontal conveyor can be controlled.

The evacuation chamber of the inclined conveyor is evacuated through any suitable means through an outlet a pipe which extends from a side wall of the chamber. This pipe can be disposed at any particular position so as not to interfere with the movement of the conveyor belt. In addition, the evacuation chamber is provided with a pair of guides which serve to slidably mount the upper reach of the conveyor belt thereon and which are made of suitable material so as to reduce wear therebetween.

Since the cigarettes are conveyed only by a single conveyor belt and are otherwise exposed to view, any defective cigarette can be readily seen and removed if desired. Further, should any cigarette become skewed during conveyance, jamming will not occur in the inclined conveyor.

After the cigarettes have been deposited into the hopper of the cigarette making machine, a suitable packaging operation is carried out.

These and other objects and advantages of the invention will become more apparent when taken in conjunction with the following detailed description and appended drawings in which: a

FIG. 1 illustrates a side view of an automatic feed machine according to the invention located between a cigarette making machine and a cigarette packaging machine;

FIG. 2 illustrates an enlarged fragmentary view of the inclined conveyor of FIG. 1;

FIG. 3 illustrates a cross-sectional view of the inclined conveyor of FIG. 2; and

FIG. 4 illustrates a fragmentary plan view of the conveyor of FIG. 2.

Referring to FIG. 1, the cigarette feed machine 10 is disposed between a cigarette making machine 11 and a cigarette packaging machine 12. Both the cigarette making machine 11 and the cigarette packaging machine 12 are of conventional structure and therefore are not further shown or described. The cigarette feed or transfer machine 10 includes a first conveyor 13 which is inclined so as to convey the cigarettes 14 from the making machine 12 to an elevated position and a second conveyor 15 which transfers the elevated cigarettes 14 into a hopper 16 of the cigarette packaging machine 12.

Referring to FIGS. 1 and 2, the inclined conveyor 13 is constructed of a pair of conveyor rollers 16, 17 a conveyor belt 18 which is disposed in endless fashion over the conveyor rollers 16, 17, and an evacuation chamber 19 which is disposed under the upper reach of the conveyor belt 18. The upper conveyor roller 16 serves as a driving roller to drive the belt 18 while the lower conveyor roller 17 is formed as a flanged outer race ring of an anti-friction bearing (not shown) to be freely mounted on the shaft 20 carrying a pair of grooved dispensing rollers 21, as are known, of the cigarette making machine 11. The endless belt 18 is provided with a series of apertures 22 disposed along the length of the belt 18 in spaced relation. For example, the apertures 22 are spaced apart a distance of approximately three to four times the diameter of the cigarettes being conveyed. The evacuation chamber 19 is disposed so that the belt 18 slides on the upper surface of the chamber 19.

Referring to FIGS. 2 and 3, the evacuation chamber 19 is of a substantially channel shaped cross-section with an open top. A pair of guide plates 23 are secured adjacent the upper ends of the side walls 24 of the chamber 19 and are secured thereto in any suitable manner such as by welding. These guide plates 23 serve to guide the conveyor belt 18 thereon and are of any suitable material to reduce wear therebetween. For example, the belt 18 can be made of a material such as spring steel or nylon while the guide plates 23 are made of brass. In the event that the belt is made of a material such as a porous nylon weave or a nylon film, the guides can be made of Teflon or other suitable plastic material. In addition, the plates 23 are spaced apart a distance substantially equal to the width of the apertures 22.

In order to evacuate the interior of the evacuation chamber 19, a suitable outlet pipe 25 (FIG. 1) is secured in a side wall 24 of the chamber 19 and communicates, for example, over a flexible line 26 to a vacuum pump 27 which is driven by a suitable motor 28. The outlet pipe 25 is disposed near the lower end of the chamber 19 to communicate with the vacuum pump 27 while the vacuum pump 27 and motor 28 are mounted on any suitable support structure adjacent to the lower end of the conveyor 13.

Referring to FIGS. 1 and 2, the evacuation chamber 19 further has a curl 29 at the upper end which is sized so as to curl around the conveyor roller 16 without interferring with the drive of the conveyor belt 18 by the conveyor roller 16. For example, as shown in FIG. 2, the angular extent of the curl 29 from a point located in a plane 30 perpendicular to the axis of the conveyor roller 16 and perpendicular to the longitudinal axis 31 of the conveyor 13 subtends an angle A of approximately 75 to 80 maximum. The dimensions of the curled end of the evacuation chamber 19 and the conveyor roller 16 are such that the conveyor belt 18 is unsupported for only a slight distance in passing from the guide plates 23 of the evacuation chamber 19 onto the surface of the conveyor roller 16.

Referring to FIG. 2, the inclined conveyor 13 is provided with a suitable frame 32 which serves to support the conveyor roller 16 and evacuation chamber 19 in fixed relation to each other. The frame 32 is sized to be positioned in close proximity to the dispensing rollers 21 of the making machine 12 so that the conveyor belt 18 can be looped about the lower conveyor roller 17 and so that the evacuation chamber 19 can be brought between the dispensing rollers 21 close to the point where the cigarettes are discharged from the dispensing rollers 21. If necessary, the lower end of the evacuation chamber 19 can be arcuately extended in a manner similar to the upper end in order to initiate the influence of the chamber 19 on the cigarettes.

In addition, a suitable tension arrangement 33 is mounted in the frame 32 of the conveyor 13 so as to place the conveyor belt 18 under tension. For example, the tension arrangement 33 includes a pair of

rollers

34, 35 one of which is fixedly mounted in the frame 32 of the conveyor 13 and the other of which is movably mounted in a guided manner in the frame 32 under the force of a spring 36 secured to the frame 32. This tension arrangement 33 can be similar to that described in copending application Ser. No. 28,640 filed Apr. 15, I970. The tension imparted to the belt 18 is of sufficient to maintain the belt 18 in sliding contact with the guide plates 23 of the evacuation chamber 19 so as to prevent any leakage of air between the plates 23 and belt 18. This will prevent loss of the vacuum force required to retain the cigarettes on the belt 18.

Referring to FIG. 1, the horizontal conveyor 15 is disposed so as to receive the cigarettes 14 delivered from the inclined conveyor 13 and to transfer the cigarettes in stacked fashion to the hopper 16 of the packaging machine 12. This horizontal conveyor 15 is constructed, for example, of a pair of endless belts 40 of interconnected chain pushers (not shown) which are disposed about pairs of

toothed sprockets

41, 42. One pair of sprockets 41 is driven while the other pair of sprockets 42 is coupled to the upper drive roller 16 of the inclined conveyor 13 to drive the same. In addition, the conveyor 15 includes a platform (not shown) located between the endless belts 40 which can be made of any suitable material to support the cigarettes being conveyed along the conveyor 15.

The conveyor 15 is further provided with a pair of upstanding walls 43 to either side so as to provide a channel for the transportation of the cigarettes in stacked fashion. Each of these walls 43 can be formed of a transparent material for visual viewing and at least one can be sectioned so as to be removed or pivoted away to permit access to the cigarettes. The conveyor 15 is of a construction which is similar to that described in copending application Ser. No. 28,640 filed Apr. 15, 1970 and reference is made thereto for further details.

Referring to FIG. 2, in order to aid in the guiding of the cigarettes 14 from the inclined conveyor 13 to the horizontal conveyor 15, a guide means 44 in the form of a plate is mounted on the second conveyor 15 adjacent to the end of the inclined conveyor 13. This guide plate 44 allows the cigarettes being delivered from the conveyor 13 to slide down onto the belts 40 of the horizontal conveyor 15 without falling into the space between the conveyors. In addition, a hold down flap 45 such as a piece of canvas which may be supported on a pin 46 mounted on a wall 43 of the horizontal conveyor 15 can be used to further facilitate delivery of the cigarettes onto the conveyor 15 in an orderly manner. The flap 45 is loosely supported so as to be pushed aside under the force of the flow of cigarettes from the inclined conveyor 13 to the horizontal conveyor 15. In this way, the cigarettes upon passing from one conveyor to the other are substantially prevented from jumping off the end of the inclined conveyor 13. Also, a further flap 45 can be used to hold down the stacked cigarettes conveyed along the conveyor 15 and stacked within the hopper 16.

Referring to FIG. 1, the delivery end of the horizontal conveyor 15 is provided with a suitable guide .means 48 for facilitating passage of the stacked cigarettes into the hopper 16, for example, as, described in the above mentioned copending application. In addition, an agitating means 49 having a reciprocating bar 50 with extending pins 51 located within the hopper 16 is provided and is connected to the guide means 48 in order to oscillate the same. A segregating means 52 is also provided in the hopper 16 to segregate the cigarettes as well as a photosensing system 53 for detecting different levels of cigarettes in the hopper 16 for control of the packaging machine speed as is known.

In order to actuate various conveyors of the transfer machine, a drive transmission is connected so as to drive the horizontal conveyor 15 which in turn drives the inclined conveyor 13. This drive is similar to that described in the above mentioned copending application and further descriptive details are not believed to be necessary. However, it is noted that the lower conveyor roller 17 is able to move independently of the operation of the dispensing rollers 21.

In operation, with the cigarette making machine 11 and transfer apparatus 10 in operation, a row of cigarettes is discharged onto the upper reach of the conveyor belt 18 via the dispensing rollers 21 as is known. The belt 18 of the inclined conveyor 13 then conveys the stream of cigarettes 14 upwardly from the making machine 11 under the suction force which is generated within the evacuation chamber 19. That is, as air is drawn through the apertures 22 in the conveyor belt 18, some of the cigarettes 14, e.g. every third or fourth cigarette, positioned on the upper reach of the conveyor belt 18 are drawn by the air stream over respective apertures 22 so as to seal of! the apertures. Each cigarette so drawn is thereafter retained in place over an aperture 22 under the force of the vacuum. The cigarettes 14' which are positioned between each pair of retained cigarettes 14 then roll down the conveyor 13 a small distance until abutting a retained cigarette 14 and are thereafter carried along with the retained cigarettes 14. To this end, the apertures 22 are spaced apart on a centerline-to-centerline basis by about three to four cigarettes diameters. However, any suitable spacing can be used to effect transport of the cigarettes. Alternatively, the belt 18 can be made of a woven or mesh-like material so that air is drawn substantially uniformly therethrough to positively retain all of the cigarettes under suction.

In order to retain the cigarettes 14 over the apertures 22 a pressure of between two inches to three inches of vacuum is used for a conveyor 13 inclined on an angle of about 45. Should the angle of the conveyor 13 be made steeper, more vacuum would be required. In addition, the movement of the belt 18 in relation to the speed of the making machine 11 is such that the dispensing rollers 21 which serve to individually discharge the made cigarettes out of the cigarette making machine 11 are positioned with respect to the conveyor belt 18 so that every third or fourth cigarette comes into substantially immediate contact with an aperture 22 in the conveyor belt 18. This permits the cigarettes to be positively retained on the conveyor belt 18 substantially immediately upon leaving the influence of the dispensing rollers 21. From this point forward, each retained cigarette 14 is conveyed positively along the upper reach of the conveyor while holding two or three cigarettes 14 in the front against backward movement under gravity. Upon reaching the upper end of the conveyor 13, the row of cigarettes are directed about the conveyor 13 over the curl 29 of the evacuation chamber due to the vacuum effect of the evacuation chamber 19 at this end. Upon reaching a point where gravity would overcome the retaining force on the cigarettes 14, the cigarettes roll off the conveyor belt 18 onto the guide plate and thence onto the horizontal conveyor 15.

The continued operation of the transfer machine is substantially identical to the operation of the machine as described in the above mentioned copending application and further description is not believed to be necessary.

The invention thus provides a cigarette transfer apparatus which utilizes an inclined conveyor which can move a row of cigarettes upwardly in single row fashion at substantially high speeds. For example, the cigarettes can be moved at a rate of over 3600 cigarettes per minute. In addition, the cigarettes being conveyed can be readily inspected since they are exposed to view so that should any cigarettes become damaged during conveyance such can be readily removed. In addition, because the cigarettes are being conveyed only from below, jamming of the cigarettes on the conveyor and crushing of the cigarettes during conveyance are eliminated.

The invention further provides a transfer apparatus which does not subject the conveyed cigarettes to any mechanical forces other than suction. The freely moving cigarettes therefore can maintain the roundness and desired compaction in being moved between a cigarette making machine and a cigarette packaging machine.

What is claimed is:

1. In an automatic cigarette feed machine for conveying cigarettes from a cigarette making machine to a cigarette packaging machine;

a first conveyor inclined with respect to a horizontal plane having a smooth endless belt for conveying a single row of cigarettes thereon from the cigarette making machine to an elevated position in a sequential series, said belt having a plurality of spaced apart elongated apertures therein transversely of said belt, each aperture being sized to position a conveyed cigarette thereover, and

means for drawing air through said apertures to retain at least some of the conveyed cigarettes thereon under a suction force.

2. In an automatic cigarette feed machine as set forth in claim 1 wherein said apertures are spaced apart a distance of from three to four diameters of the conveyed cigarettes.

3. In an automatic cigarette feed machine as set forth in claim 1 wherein said belt is made of spring steel.

4. In an automatic cigarette feed machine as set forth in claim 1 wherein said belt is made of nylon.

5. In an automatic cigarette feed machine as set forth in claim 1 wherein said conveyor includes an evacuation chamber positioned below the upper run of said belt for evacuating air through said belt to retain at least some of the conveyed cigarettes thereon under a suction force, said evacuation chamber having a guide means thereon slidabl receiving said upper run of said belt means thereon.

6. A conveyor for conveying cigarettes in an upwardly inclined plane comprising an evacuation chamber having an open side;

means connected to said evacuation chamber for creating a suction force within said evacuation chamber, and

an endless belt having an upper run thereof slidably mounted over said open side of said evacuation chamber to close said open side, said belt having a plurality of spaced apart elongated apertures extending transversely of said belt for passage of air therethrough into said evacuation chamber whereby a cigarette positioned on said upper run is retained under a suction force on said upper run.

7. A conveyor as set forth in claim 6, wherein said evacuation chamber is of channel shaped cross-section and is dislposed longitudinally and parallel to said upper run of said be t.

8. A conveyor as set forth in claim 6, wherein said evacuation chamber includes guide means thereon projecting from said open side to slidably mount said belt thereon with said apertures extending therebetween.

9. A conveyor as set forth in claim 6, wherein said apertures are spaced apart a distance equal to from three to four diameters of the conveyed cigarettes.

10. A conveyor as set forth in claim 6, which further includes a roller at one end of the conveyor for driving said belt in an endless path, said evacuation chamber having an end curled about said roller between said belt and said roller.

11. A conveyor as set forth in claim 10, wherein said curled end subtends an angle of approximately 75 to from a point in a plane perpendicular to the rotational axis of said roller and perpendicular to the longitudinal axis of the conveyor.

12. A conveyor for conveying cigarettes in an upwardly inclined plane comprising an evacuation chamber having an open side;

means connected to said evacuation chamber for creating a suction force within said evacuation chamber;

an endless belt having an upper run thereof slidably mounted over said open side of said evacuation chamber to close said open side, said belt having means therein for passage of air therethrough into said evacuation chamber whereby a cigarette positioned on said upper run is retained under a suction force on said upper run, and a roller at one end of the conveyor for driving said belt in an endless path, said evacuation chamber having an end curled about said roller between said belt and said roller.

13. A conveyor as set forth in claim 12, wherein said curled end subtends an angle of approximately 75 to 80 from a point in a plane perpendicular to the rotational axis of said roller and perpendicular to the longitudinal axis of the conveyor.

* I! I? t It UNITED STATES PATENT OFFHIE @ETWEQATE CQEQTEQN 3,675,761 5 Dated July 11, 1 2

Patent No.

Invento'r(s) l yd V. Hall It is certified that error appears in the above-identified patent and that said Letters- Patent are hereby corrected as shown below:

On the cover sheet [563 under the References Cited,

patent number" "3,277,558" should read 3,477,558

Signed and sealed this 19th day of December 1972.

(SEAL) Attest;

EDWARD M. FLETCHER,JR, 5 ROBERT GSCHALK Attesting Officer Commissioner of Patents USCOMM'DC 60376-P69 U.S. GOVERNMENT PRINTING OFFICE: 1565 O356-334.

FORM PO-IOSO (10-69)

Claims

1. In an automatic cigarette feed machine for conveying cigarettes from a cigarette making machine to a cigarette packaging machine; a first conveyor inclined with respect to a horizontal plane having a smooth endless belt for conveying a single row of cigarettes thereon from the cigarette making machine to an elevated position in a sequential series, said belt having a plurality of spaced apart elongated apertures therein transversely of said belt, each aperture being sized to position a conveyed cigarette thereover, and means for drawing air through said apertures to retain at least some of the conveyed cigarettes thereon under a suction force.

5. In an automatic cigarette feed machine as set forth in claim 1 wherein said conveyor includes an evacuation chamber positioned below the upper run of said belt for evacuating air through said belt to retain at least some of the conveyed cigarettes thereon under a suction force, said evacuation chamber having a guide means thereon slidably receiving said upper run of said belt means thereon.

6. A conveyor for conveying cigarettes in an upwardly inclined plane comprising an evacuation chamber having an open side; means connected to said evacuation chamber for creating a suction force within said evacuation chamber, and an endless belt having an upper run thereof slidably mounted over said open side of said evacuation chamber to close said open side, said belt having a plurality of spaced apart elongated apertures extending transversely of said belt for passage of air therethrough into said evacuation chamber whereby a cigarette positioned on said upper run is retained under a suction force on said upper run.

7. A conveyor as set forth in claim 6, wherein said evacuation chamber is of channel shaped cross-section and is disposed longitudinally and parallel to said upper run of said belt.

11. A conveyor as set forth in claim 10, wherein said curled end subtends an angle of approximately 75* to 80* from a point in a plane perpendicular to the rotational axis of said roller and perpendicular to the longitudinal axis of the conveyor.

12. A conveyor for conveying cigarettes in an upwardly inclined plane comprising an evacuation chamber having an open side; means connected to said evacuation chamber for creating a suction force within said evacuation chamber; an endless belt having an upper run thereof slidably mounted over said open side of said evacuation chamber to close said open side, said belt having means therein for passage of air therethrough into said evacuation chamber whereby a cigarette positioned on said upper run is retained under a suction force on said upper run, and a roller at one end of the conveyor for driving said belt in an endless path, said evacuation chamber having an end curled about said roller between said belt and said roller.

13. A conveyor as set forth in claim 12, wherein said curled end subtends an angle of approximately 75* to 80* from a point in a plane perpendicular to the rotational axis of said roller and perpendicular to the longitudinal axis of the conveyor.