US3417541A

US3417541A - Apparatus for automating packaging machines and packaging production lines

Info

Publication number: US3417541A
Application number: US531572A
Authority: US
Inventors: Gerald F Wedl; Darwin D Draisey
Original assignee: GRAIN BELT BREWERIES Inc
Current assignee: GRAIN BELT BREWERIES Inc
Priority date: 1966-03-03
Filing date: 1966-03-03
Publication date: 1968-12-24
Anticipated expiration: 1985-12-24

Description

Dec. 24, 1968 G. F, WEDL ETAL 3,417,541

APPARATUS FCR AUTCMATING PACKAGING MACHINES AND PACKAGING PRODUCTION LINES Filed MarCh 5, 1966 5 Sheets-Sheet l .diro/P41515' .mw IO M u H@ C A Ill.

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G. F. WEDL ETAL APPARATUS FOR AUTOMATING PACKAGING MACHINES Dec. 24, 1968 AND PACKAGING PRODUCTION LINES 5 Sheets-Sheet 2 Filed March 5. 1966 eg'ff' I N VEN TORS L, p f W F w m fa De- 24, 1968 G. F. wenn. ETAL APPARATUS FOR AUTOMATING PACKAGING MACHINES AND PACKAGING PRODUCTION LINES 3 Sheets-Sheet 5 Filed March 5, 1966 IIIllu-hn.

S. R m@ WW. 1F M a Fig 7 United States Patent O 3,417,541 APPARATUS FOR AUTOMATING PACKAGING MACHINES AND PACKAGING PRODUCTION LINES Gerald F. Wedl, Coon Rapids, and Darwin D. Draisey, Minneapolis, Minn., assignors to Grain Belt Breweries, Inc., a corporation of Minnesota Filed Mar. 3, 1966, Ser. No. 531,572 7 Claims. (Cl. 53-55) ABSTRACT OF THE DISCLOSURE A beer can packaging apparatus sensing a shortage of beer cans to stop the flow of cartons, and sensing a shortage of cartons to stop the ilow of beer cans.

Of the available packaging machines presently on the market, particularly those machines designed to package groups of six cans into a wrap around carton, none have provided for completely automating the machine by coordinating the packaging machine with the packaging production line in such a way that the machine responds to shortages in the packaging line and the packaging line responds to shortages of carton blanks in the packaging machine. Further, presently available packaging machines do not consider the packaged product after it leaves the packaging machine but while it is still in the over-all packaging production line, for example enroute to a master packer station.

An example of such a packaging machine may be found in U.S. Patent No. 2,986,857, issued June 6, 1961 to Henry Ganz and assigned to the Continental Can Co. Inc., New York, N Y. The Ganz packaging machine wraps a carton blank around a predetermined number of cans, typically six cans arranged in two, side by side rows of 3 cans each. No provision is made for providing a machine responsive to the production line nor is the production line responsive to the packaging machine. Further, the packaging machine should dispense carton blanks with the discharge of groups of six cans from the production line in such a way that the carton blank is properly positioned over the cans at the point of wrapping. Oftentimes, the lack of synchronization between the carton blanks and the production line, which typically follows the dispensing of a faulty carton blank or no blank at all, results in a blank being disposed over two or four cans for Wrapping. When this occurs the operator must shut the machine down and manually insert or exclude the proper number of cans and manually synchronize the carton with the cans and the can discharge. This procedure results in a high percentage of downtime and, consequently, results in high packaging cost per packaged unit.

With these comments in mind it is to the elimination of these and other disadvantages to which the present invention is directed along with the inclusion therein of other novel and desirable features.

An object of our invention is to provide a new and improved method and apparatus for automating packaging production lines of simple and inexpensive construction and operation.

Another object of our invention is the provision of a packaging machine which responds to the packaging production line and includes means to control the production line in response to the machine.

Another object of our invention is the provision of a packaging production line which responds to the packaging machine and includes means to control the packaging machine in response to the production line.

Still another object of our invention is the provision rice l of a method and apparatus for controlling the ow of units to be packaged in response to the packaging medium and simultaneously controlling the flow of the packaging medium in response to the units to be packaged.

Another object of our invention is the provision of apparatus for dispensing the packaging medium at a predetermined time as Well as interrupting the flow of packaging medium at a predetermined time in response to the units to be packaged.

Another object of our invention is the provision of apparatus to index the units to be packed into groups of predetermined numbers as well as to control the ow of a predetermined number of units in response to the packaging medium.

A still further object of our invention is the provision of an automated packaging machine and package production line eliminating the need for a highly skilled operator and requiring only an operator of minimum skill or manual dexterity.

These and other objects and advantages of our invention will more fully appear from the following description made in connection with the accompanying drawings wherein like reference characters refer to the same or similar parts throughout the several views, and in which:

FIG. l is a side elevation showing a packaging machine with incoming cans from the production line and the outgoing packaged product; the production lines and machine shown complete with the apparatus of my invention for automating the packaging of the product.

FIG. 2 is an enlarged partial perspective view showing the carton blank dispensing mechanism and synchronization assembly.

FIG. 3 is an enlarged partial plan view showing the can indexing and spacing assembly.

FIG. 4 is an enlarged partial perspective view showing the carton blank sensing limit switches and a carton blank.

FIG. 5 is an enlarged partial plan view showing the production line pressure gate and can sensing assembly.

FIG. 6 is an enlarged partial cross-sectional View taken along the line 6 6 of FIG. 2 and showing the carton dispensing assembly.

FIG. 7 is an enlarged partial side elevation showing the pressure gate assembly and the auxiliary sensing assembly in the production line.

One form of the present invention is shown in the drawings and is described herein. The packaging machine is shown in FIG. l, indicated in general by numeral 10. The machine includes suitable supporting structure 10a. A start-stop switch is indicated at 10b and a carton blank dispensing override switch at 10c. The override is utilized to clean-out the machine at the end 0f the day. The machine and production line are each connected to a suitable power source (not shown). The incoming production line and supporting structure is indicated at 11, and the outgoing production line of packaged products is indicated at 12. Cans 13 are shown on the incoming production line and packaged cans 14 are shown on the outgoing production line 12. Direction of flow of the cans is from the right to the left in FIG. l as indicated by the arrow. As cans 13 proceed from the production line 11 into the wrapping station of machine 1G, carton blanks are dispensed by the carton dispensing assembly, indicated in general by numeral 15. Individual carton blanks are dispensed for oW through the machine 10 to the wrapping station at intervals synchronized with the ow of groups of cans through the machine so that a blank and corresponding cans arrive at the wrapping station at the same time. The cans are indexed in groups of six and are Wrapped by machine 10 in any of several conventional ways. One manner of wrapping cans is clearly disclosed in the above mentioned 3 Ganz patent. Further explanation of the wrapping apparatus and process is deemed unnecessary except as it relates to our invention.

FIG. 1 shows the carton dispensing assembly 15 which includes a hopper 16 for containing the carton blanks and a bottom opening 17 for dispensing the carton blanks 18. A series of suction cups 19 are disposed transversely of the direction of travel of the cans and underneath opening 17 of hopper 16. Suction cups 19 are energized by pneumatic valve 20. The hopper 16 is attached to machine 1t) with bracket 21 and valve 2t) is attached to the machine supporting structure, and connected to suction cups 19 through hose 21a. Suction `cups 19 are actuated upwardly to engage the lowermost carton blank in hopper 16 and, with the suction at each of the cups, draw off the bottom carton blank, and feed it into rollers which are shown in FIG. 6. The mechanical apparatus for alternately raising and lowering suction cups 19 is not shown, but may be done in any of several conventional ways. Suction cups 19 are synchronized with cans 12 in such a way that a carton is dispensed each time .a group of six cans enters the machine. Further, if cans are not in the incoming production line the carton blank is not released. The carton blank is fed onto conveying chains 22 which in turn feed the carton blank onto conveying chains 23. The carton blank 18 rests on these chains and is carried thereon to the cans to be packed. Limit switches 24 have sensors 24a attached thereto which maintain contact with the dispensed carton and, in the instance of interrupted ow of carton blanks, provide electrical signal means for interrupting the flow of cans until such time as the next carton is dispensed. Frequently the iiow of cartons is interrupted when the suction cups 19 fail to draw off a carton blank due to, for example, blanks adhering together from moist conditions, faulty ink or other malfunctions.

The can indexing assembly is indicated at numeral 25, in FIG. 1, and is shown in plan view in FIG. 3. The cans are indexed into groups of six, three in each of two rows. Referring to FIG. 3, the can conveyor is indicated at 26 and is of conventional construction. The conveyor moves as indicated by the arrow in FIG. 3, conveying the cans toward can indexing assembly 25. A divider 27 separates the cans into two rows. The machine housing is indicated at 28 and supporting frame 29 is also shown. A pair of commercially available solenoid operated air cylinders 30 are attached to the frame 29 and are disposed alongside each of the conveyors 26. Each cylinder includes a plunger 31 guided by bracket 32 to engage the upper indexing portion 33 which is aflixed to the star wheel 34. The solenoid operated air cylinders 30 are responsive to limit switches 24 and sensors 24a. They are linked by conventional electric circuitry which is not shown here. Star wheel 34, with the indexing portion 33 securely attached thereon, is rotatably mounted on upright shaft 35 and rotates freely. The star wheel and indexing members are contsructed from steel and are cut to fit the unit being packaged. When sensors 24a do not contact a carton, plungers 31 are actuated and indexing members 23 stop the star wheels from turning, preventing cans from entering the machine. It should be noted that the can indexing assembly provides for stopping in groups of six cans, thereby obviating the need for the operator to manually remove the corresponding cans each time a missing carton occurs. When a carton is next contacted by sensors 24a the solenoid operated plungers 31 are withdrawn and properly indexed cans proceed in timed relation with the carton blanks.

A chain and

sprocket assembly

36 and 37, respectively, is secured to the frame and, as the cans proceed from the can indexing assembly, the cans are engaged by can engaging elements 38 which project outwardly from the chain 37. Can engaging elements 38 are spaced a predetermined distance apart to carry cans to the wrapping station timed to coincide with the arrival of a corresponding carton blank at the wrapping Station, Conventional drive means are provided for sprockets 37 and the detail is not shown here.

FIG. 4 shows carton blank 18 flowing through the machine in the direction of the arrow and engaging sensors 24a which are attached to limit switches 24. Limit switches 24 are securely mounted on the frame of the machine and may be adjusted to properly time the release of cans at the can indexing assembly with the arrival of carton 18 at the wrapping station of the machine. Structural framework of the machine is indicated in FIG. 4, by numeral 39. Limit switches 24 are commercially available and wired in parallel. The sensors 24a are simply rigid wires attached to the limit switches in switch actuating relation. The sensors are spaced so that at least one touches a carton blank at all times that the blanks are being properly discharged. When a blank fails to discharge both the sensors must fail to contact a carton blank before the plungers 31 are actuated, preventing the flow of cans until the next carton blank is sensed.

FIG. 6 shows the manner in which a carton blank is dispensed. Suction cups 19 are advanced to the position shown in the dotted lines to grip a carton blank 18. Suction is applied and the suction cups are then retracted to the position shown in the solid lines, gripping carton 18 and placing the carton lblank leading edge adjacent the knurled roll 40. The suction is then released. This allows the knurled roll, which mates with conveyor 22, to grip the blank. Conveyor 22 is driven by sprocket 41 which rotates about shaft 42. Shaft 42 provides the pivot point of the reciprocating knurled roll 40 which advances the carton to the position shown in the dotted lines and indicated at 40a. The blank is then carried by conveyor 22 to conveyor 23 which includes pushers -23a spaced at a predetermined distance to carry carton blanks to the wrapping station coinciding with the arrival of a predetermined number of cans to be wrapped. The drive means for the reciprocating suction cups 19, as well as the means controlling the suction cycle and providing the reciprocating action to roller 40 may be done in the manner disclosed by the above mentioned patent and is not shown here.

Referring to FIG. 2, the mechanism which provides for coordinating the knurled roll and suction cups at start-up or shutdown is shown in detail. Shaft 42 is show-n with a cam 43 mounted thereon above the shaft 42. The cam 43 is elevated by rigid support 44 which gives cam 43 a reciprocating motion substantially the same as the reciprocating motion of the knurled roll 40 shown in FIG. 6. Cam follower 45 rests on cam 43 and actuates limit switch 46 in response to the motion of the cam 43. When cam 43 is forward, as indicated by the solid lines, limit switch 46 is open and energizes pneumatic valve 20. In the position shown in the dotted lines, limit switch 46 is closed thereby shutting off the vacuum to suction cups 19. The limit switch is mounted on the hopper 16 by bracket 47 and is connected to pneumatic valve 20 with conventional electric circuitry, controlling the pneumatic valve in response to the can supply in the pro duction line without the need for shutting down any part of the machine in a can shortage, but rather simply control the vacuum responsive to the can supply. Further, the cam 43 actuates the pneumatic valve 20 at the same point each time start-up or shutdown occurs, providing automatic synchronization 'between the pneumatic valve which supplies the suction to the suction cups and the knurled roll 40 which takes the cartons 18 away and places them on conveyor 22.

The cam and cam follower are constantly in motion as the machine is running. Limit switch 46 is connected to a sensing means in the production line with a time delay relay and locking circuit interposed in the circuitry. The relay (not shown) is locked into the circuit in the on position and is maintained in the circuit until such time as a can shortage is sensed. At this point limit switch 46 is closed when cam 43 is rearwardly and acted upon cam follower 45. This shuts oif the pneumatic valve and suction to suciton cups 19 is no longer provided. However, the suction cups maintain their reciprocating motion but -do not draw cartons for conveying to the wrapping station. When the production line sensing means senses cans the time delay relay is energized and, upon timing out opens limit switch 46 when the cam 43 is forward and locking it in the circuit thereby opening valve 20 and supplying suction to the reciprocating suction cups 19 at the predetermined point in their reciprocating movement. This cycle of operation occurs each time cans are not sensed in the Production line and provides automation with respect to dispensing the cartons in response to the can production line.

FIG. 7 shows the production line can sensing means which includes a can pressure gate assembly 48 and auxiliary can sensing assembly 49 which together7 through conventional electric circuit-ry, control limit switch 46 which in turn is controlled by cam and

cam follower

43 and 45 respectively. The time delay relay and locking circuit is interposed between the production line can sensing means and the limit switch 46. The direction of can flow is in the direction indicated by the arrow in FIG. 7.

FIG. 5 shows a plan view of the pressure gate assembly 48 and the can sensing assembly 49 with can flow as indicated. The pressure gate assembly 48 comprises a spring loaded, hinged gate portion 50 in the guide rail 51 of the production line, which production line cornprises a pair of

guide rails

51 and 51a. The gate is hinged by hinge 52 and is spring loaded, utilizing spring 53 which is mounted on post 53a which projects outwardly from the stationary rail 51. Bracket 54 is attached to the gate portion 50 and includes an aperture (not shown) allowing post 53a to be inserted in the aperture. Spring 53 maintains gate portion 56 in a normally continuous relation with stationary guide rail 51. This position is indicated by the dotted lines and is maintained when there is not can ow through the gate. Guide rail 51a is widened opposite gate portion 50 to supply added pressure to the gate portion. The widened portion is indicated at 51b. A limit switch 55 is mounted on bracket 55a which in turn is mounted on the supporting framework of the production line. Limit switch 55 is actuated in response to a cam SSb which r-olls on gate portion 50 as the gate p0rtion is moved to the open position thereby actuating the limit switch 55, as can ow continues a locking circuit maintains limit switch 55 in the circuit.

The auxiliary can sensing assembly 49 includes a limit switch 56 and sensor 57 attached in actuating relation to the limit switch 56. Limit switch 56 is placed in conventional series circuit with switch 55, sensing can ow. When can flow is no longer sensed by sensor 57, limlL switch 56 is closed, dropping out the locking circuitry, which in turn actuates limit switch 55. At this point, since cans are no longer sensed by the gate assembly and auxiliary sensing assembly, the time delay interposed between the production line and the dispensing assembly is energized and subsequently provides for interruption in the flow of cartons without stopping the machine, until such time as the can supply is replenished.

The time delay relay interposed between the production line and the carton blank dispensing mechanism is commerically available and is not shown here. The time delay is timed dependant upon the length of the production line, particularly the length between the production line can sensing mechanism and the overall length of the production line. Other factors may be considered in determining the time delay necessary.

A emergency sensing mechanism may be provided on the discharge end of the packaging machine. Sensing means may be interposed in the outgoing production line of packaged goods to prevent the packaged goods from backing up into the machine at such times as a master packing operation may not be able to keep up with the production of the packaging machine. This may be done in any of several ways, none of which are shown here. A common method comprises installing a limit switch with a sensing lever attached thereto in actuating relation, interposed in the outgoing production line. At such times as the sensing lever senses interruption in the flow of packaged goods, the machine is automatically shutdown until such time as ow is resumed. All stations of the machine should be shutdown in this instance to prevent damage to the various working parts of the machine.

Operation \Operation of the machine is begun by actuating the start-stop button 10b. The operator pushes the start button and cylinders 30 are actuated through conventional solenoids forcing plungers 31 outwardly to contact indexing portion 33 thereby retarding the flow of cans to the machine 10. Since the cans are prevented from flowing into the machine, they build up along the conveyor production line 11 to auxiliary ca n sensing assembly 49 and then to pressure gate assembly 48. This actuates

limit switches

55 and 56, which are in series, and which are linked through conventional electric circuitry to limit switch 46. Limit switches 55 and 56 provide against short periods of sufficient flow of cans through gate assembly 48 and sensor 49 from starting the flow of cartons at the carton dispensing assembly 15 in that both switches must be affected. A commercially available time delay relay is interposed in the circuit between limit switches 55/56 and 46. The time delay is timed dependant upon such variables as the length of the production line or the distance from the gate to the end of the can conveyor. When the time delay times out, after build-up past the gate has occurred, the relay is energized allowing cam and

cam follower

43 and 45 respectively to open limit switch 46. Cam 43 causes the limit switch 46 to be opened when suction cups 19 are at a predetermined position. When the limit switch 46 is opened pneumatic valve 20 is actuated supplying suction to suction cups 19. At this point a conventional locking circuit is actuated maintaining limit switch 46 in the circuit. This allows the suction cycle to continue normally even though the cam and follower continue their reciprocating movement. The suction to the cups is alternated to withdraw and subsequently release carton blanks as disclosed in the above mentioned Ganz patent.

When a shortage of cans is sensed and limit switch 56 is not satisfied, cam and

cam follower

43 and 45, respectively close limit switch 46 at the predetermined position. The circuit may also be set so that switches 55 and 56 must be satisfied before switch 46 is closed. This will prevent short can flow interruptions from stopping the cartons. This shuts off the vacuum without shutting olf any of the other parts of the machine. Since the vacuum is off, cartons are no longer dispensed until such time as sufficient can supply is again built up. This satisfies switches 55 and 56 and can ow resumes as described above. This cycle is repeated each time a shortage and subsequent replenishment occurs, the continuous operation of the machine being maintained at all times.

In the instance of a carton blank shortage or skipped carton due to excess moisture or similar malfunctions, the sensors 24a do not contact a carton blank and subsequently actuate the solenoid operated air cylinders 30. Plur'gers 31 engage the indexing portion 33 interrupting the ilow of cans into the machine. After predetermined groups of six cans have proceeded into the machine sui cient to meet the last carton which was sensed by sensors 24a, lflow of cans ceases until carton ow begins. While the ow of carton blanks is interrupted the balance of the machine continues operation and the drive motor need not be shut-off. When the carton blank shortage is corrected, the cartons ow as above and are sensed by sensors 24a. The solenoid is actuated and plungers 31 retract allowing cans to proceed in groups of six. The sensors 24a may be spaced apart to prevent short interruptions in carton ow from stopping can ow. Each time a carton shortage occurs the above operation automatically repeats without the need of any assistance of an operator and without aiecting any other of the working parts of the machine.

After initial start-up the machine continues running without the need for any supervision except with respect to machine jams. If there are no cans, no cartons are dispensed; if there are no cartons, no cans are dispensed. When shutting down the machine at the end of the day, carton override 10c is actuated which holds limit switch 46 in the circuit allowing cartons to be dispensed even though

limit switches

55 and 56 in the production line have been actuated since no cans are present.

A sensing assembly may be included at the discharge end of the packaging machine to sense iiow of packaged units. If flow ceases and units are sensed, the machine should be shut down to prevent the packaged goods from backing up into the machine. The machine should start automatically when discharge ilow resumes.

It will, of course, be understood that various changes may be made in the form, details, arrangement and proportions of the various parts without departing from the scope of our invention.

What is claimed is:

1. A packing machine adapted to wrap cans and the like into packages of a predetermined number of cans, said packaging machine comprising,

a wrapping station,

a carton blank dispensing mechanism adapted to continuously dispense a plurality of carton blanks in single tile order,

a carton blank conveying system adapted to continuously convey carton blanks to said wrapping station whereby the carton blanks arrive at said wrapping station corresponding to the arrival of cans,

a can conveying system adapted to continuously move a plurality of cans to said wrapping station in groups of a predetermined number whereby each group arrives at said wrapping station simultaneously with the arrival of a corresponding carton blank,

can sensing means interposed in said can conveying system, said can sensing means including a sensor adapted to project into the stream of continuously moving cans on said can conveying system,

a sensor limit switch connected to said sensor in actuating relation, whereby said limit switch is actuated in response to flow of cans in contact with said sensor,

said can sensing means also including a pressure gate interposed in said can conveying system, said pressure gate adapted to respond to the flow of a continuously moving stream of cans,

a pressure gate limit switch connected to said pressure gate in actuating relation, whereby said limit switch is actuated in response to ilow of cans through said pressure gate,

circuit means connecting said pressure gate limit switch to said sensor limit switch whereby only the flow of cans for greater than a predetermined duration actuates said pressure gate limit switch and said sensor limit switch, and

circuit means connecting said pressure gate limit switch and said sensor limit switch to said carton blank dispensing mechanism, said carton blank dispensing mechanism responsive to said sensor limi-t switch and said pressure gate limit switch whereby a can shortage interrupts said carton blank dispensing mechanism interrupting carton blank flow corresponding to the period of can shortage.

2. The packaging machine of claim 1 including carton blank sensing means comprising,

at least one sensor adapted to project into the stream of continuously moving carton blanks on said carton bla-nk conveying system,

at least one sensor limit switch connected to said sensor in actuating relation whereby said limit switch is actuated in response to the ow of carton blanks in contact with said sensor, and

circuit means connecting said limit switch to said can conveying system, said conveying system responsive to said sensor whereby a carton blank shortage interrupts said can conveying system interrupting can flow corresponding to the period of carton blank shortage.

3. A packaging machine adapted to wrap cans and the like into packages of a predetermined number ot' cans, said packaging machine comprising,

a wrapping station,

a carton blank dispensing mechanism adapted to continuously dispense a plurality of carton blanks in single le order,

carton blank sensing means interposed in said carton blank conveying system and including a pair of sensors adapted to project into the stream of continuously moving carton blanks on said carton blank conveying system, said pair of sensors spaced apart to permit one of said sensors to contact the leading edge of a carton blank and the other of said sensors to contact the trailing edge of a carton blank,

a pair of sensor limit switches connected to said sensors in actuating relation, whereby said limit switches are actuated in response to the iiow of carton blanks in contact with said sensors,

circuit means connecting said sensor limit switches to said can conveying system, said can conveying system responsive to said sensors whereby a carton blank shortage interrupts said can conveying system interrupting can flow corresponding to the period of carton blank shortage, and

circuit means connecting said pair of sensor limit switches whereby only interruptions in the flow of carton blanks greater than a predetermined duration actuate said can conveying system.

4. The packaging machine of claim 3 including can sensing means which comprises,

a pressure gate interposed in said can conveying system, said pressure gate adapted to respond to the flow of a continuously moving stream of cans,

a pressure gate limit switch connected to said pressure gate in actuating relation, whereby said limit switch is actuated in response to how of cans through said pressure gate,

circuit means connecting said pressure gate limit switch to said sensor limit switch whereby only the flow of cans for greater than a predetermined duration actuates said pressure gate limit switch and said sensor switch, and

circuit means connecting said pressure gate limit switch and said sensor limit switch to said carton blank dispensing mechanism, said carton blank dispensing mechanism responsive to said sensor limit switch and said pressure gate limit switch whereby a can shortage interrupts said carton blank dispensing mechanism interrupting carton blank flow corresponding to the period of can shortage.

5. An attachment adapted to substantially automate a packaging machine having a wrapping station, a can conveying system, a carton blank dispensing mechanism responsive to the can conveying system and a carton blank conveying system, said attachment comprising,

can sensing means adapted to be interposed in the can conveying system, the carton blank dispensing mechanism being responsive to said can sensing means, said can sensing means including,

a pressure gate adapted to be interposed in the can conveying system, said pressure gate responsive to the flow of a continuously moving stream of cans,

a pressure gate limit switch connected to said pressure gate in actuating relation, whereby said limit switch is actuated in response to ow of cans through said pressure gate,

a sensor adapted to project into the stream of continuously moving cans on the can conveying system,

a sensor limit switch connected to said sensor in actuating relation, whereby said sensor limit switch is actuated in response to flow of cans in contact with said sensor,

circuit means connecting said pressure gate limit switch to said sensor limit switch whereby only interruptions in the flow of cans greater than a predetermined duration actuate said pressure gate limit switch and said sensor limit switch, and

circuit means connecting said pressure gate limit switch and said sensor limit switch to the carton blank dispensing mechanism, the carton blank dispensing mechanism responsive to said sensor limit switch and said pressure gate limit switch whereby a can shortage interrupts said carton blank dispensing mechanism interrupting carton blank ow corresponding to the duration of can shortage.

6, An attachment adapted to substantially automate a packaging machine having a wrapping station, a carton blank dispensing mechanism, a carton blank conveying system and a can conveying system responsive to the carton blank conveying system, said attachment comprising,

carton blank sensing means adapted to be interposed in the carton blank conveying system, the can conveying system being responsive to said carton blank sensing means, said carton blank sensing means including,

a pair of sensors adapted to project into the stream of continuously moving carton blanks on the carton blank conveying system, said pair of sensors adapted to be spaced apart to permit one of said sensors to Contact the leading edge of a carton blank and the other of said sensors to contact the trailing edge of a carton blank,

a pair of sensor limit switches connected to said sensors in actuating relation, whereby said limit switches are actuated in response to the flow of carton blanks in contact with said sensors,

circuit means connecting said sensor limit switches t0 the can conveying system, the can conveying system responsive to said sensors whereby a carton =blank shortage interrupts said can conveying system interrupting can ow correspond-ing to the period of carton blank shortage, and

circuit means connecting said sensor limit switches whereby only interruptions in the ow of carton blanks greater than a predetermined duration actuate said can conveying system.

7. The attachment of claim 5, said attachment further including,

a pair of sensor limit switches connected to said sensors in actuating relation, whereby said limit switches are actuated in response to the ow of carton blanks in contact with said sensors,

circuit means connecting said sensor limit switches to the can conveying system, the can conveying system responsive to said sensors whereby a carton blank shortage interrupts said can conveying system interrupting can ow corresponding to the period of carton blank shortage, and

circuit means connecting said sensor limit switches whereby only interruptions in the flow of carton blanks greater than a predetermined duration actuate said can conveying system.

References Cited UNITED STATES PATENTS 2,751,730 6/1956 Gentry 53-55 X 2,860,461 11/1958 Arneson 53-63 X 2,919,526 1/1960 Arenson 53-59 3,253,385 5/1966 Beermann et al. 53-55 3,262,242 7/ 1966 Godschalx 53-55 45 TRAVIS S. MCGEHEE, Primary Examiner.

R. L. SPRUILL, Assistant Examiner.

U.S. Cl. X.R.