US2697901A

US2697901A - Turret-type stretch wrapping

Info

Publication number: US2697901A
Application number: US203050A
Authority: US
Inventors: Gerald C Hosack
Original assignee: Individual
Current assignee: Individual
Priority date: 1950-12-28
Filing date: 1950-12-28
Publication date: 1954-12-28
Anticipated expiration: 1971-12-28

Description

Dec. 28, 1954 Filed Dec. 28, 1950 G. C. HOSACK TURRET-TYPE STRETCH WRAPPING Unull nu Mnl QILCT- 5 Sheets-Sheet L Dec. 28, 1954 G. c. HosAcK 2,697,901

TURRET-TYPE STRETCH WRAPPING med Dec. 2a, 195o 5 snetsheet 2 Dec, 28, 1954 G. c. HosAcK 2,697,901

TURRET-TYPE STRETCH WRAPPING Filed Dec. 28, 1950 5, She e ts-She,et 3

Dec. 28, 1954 G. c.- HosAcK 2,697,901

TuRRET-TYPE STRETCH WRAPPING Filed Deo. 28, 195o 5 sheets-sheet 4 IN VEN TOR.

Dec. 28, 1954 G. c. HosAcK 2,697,901

TuRRET-TYPE STRETCH WRAPPING 4 Filed Dec. 28, 1950 5 Sheets-Sheet 5 United States Patent O 2,697,901 TRRET-TY'P lSTRETCH WRAPG 'Gerald o. Hosek, Sanford, En., assigner' to william s. Cloud, wilmette, nl.

Application December 2s, 1950, seriall Nm` 203,050 is claims. (ol.- sii-8925)v In the wrapping of various articles in stretchable hlm, a novelmethod has been worked out according to` which the ilrn moves continuously, passing about a turret or drum-like structure having a' plurality' of wrapping units which move with tlielin, successive portions of which are drawn down by suction into successive units to forni a pocket, and the pocket is'stretched deeper by moving the bottom portion of the pocket. After the article to be packaged is dropped vwithin this doubly stretched lm pocket, the neck of Vthe pocket' is 'constrict'ed above the article and sealed closed.

According to theY present invention, a method and apparatus have been` worked out for stretch-wra`ppihg articles with exceptional eiciency and dependability. According to this invention, the plastic hlm moves continuously, passing about aturret or drum-like structure having a plurality 'of wrapping, unit's which move with 'the hlm. As the units rotate about the drum, the lm is drawn toward the' axis of thedru'n to form a pocket and, after the article is placed therein, thev pocket is closed by a pair of closure devices which; bring 'the sidesof the poeket together with a minimum ofl gathering, so as Vtofpro'dllce a smooth l'seal along 'one side yofthe pocket,` thus closing the wrapper about the pocket. With thisv arrangement, the pocket maybe y"of elongated shape, if desired. Economy in the use of the' ilniv is ac'corr'iplished by this construction, especially when, according to the preferred form of the invention, the pocket, after being firstlfonnen, is deepened by holding the cent-"ral porvtion of the pocket and v'drawing` itl further toward the to increasingly( stretch the' l"neck 4portion Vof the poe et.

4The various features 'of this application have 'been cornbjine'd according to the present invent-ion in a 'manner which produces exceptionally satisfactory results, both in the quality of the 'wrapper and in the 'economy in 'he costof wrapping, Furthermore, 'considerable simplification 'i'sl accomplished. 'For example, the closing `:and sealing means may be used Vadditionally for lsupporting the lm during the 'stretching thereof by movement of the pocket. Additional objects and advantages' will be appare ent 'from the" following description vand from vthe drawings.`

Figure' 1 is a somewhat diagrammatic view :looking down o'n the invention chosenv for illustration.

Figure 2 is a` somewhat diagrammatic -side view 'of the machine, Aas seen from the 'side "which is shown 4a't the bottom of Fig. 1. Y

Figure 3 is 'a similar view of the lother 'side 'of the machine.

Figure 4 is a fragmentary, approximately vertical transverse sectional view taken approximately along the' -l1ne "of Fig. 2.

Figure '5 is `air-*enti yiewof themaehine fas. seen trom the-"end shown'fa't the `left in Fig. f1.

Fig're '6 i's a lfragmentary sectional view illustrating the positjion 'of parts' on the 'drum when 'the venp `is 4in its outermost :position l `Figure 7 :is 1a @similar viewioh a llargerscale, illustrating the positionof 'the parte when 4the cup is irrite 1retr'cted position' and showing a "cross section of fthe cup.

'Figure l` is Ia?liz-'ross`se`ctior1al 'view lon an enlarged scale through the olosureirms. y

lfIn various-figures, Lprtsfhavebeenmitted -ifor the sake of'elarity.

ICC

General description The film` or web 11 of wrappingV material, as best. shown invFig. 2, is drawn from a roll 12, passed around a heatingA drum 13 and then around a main or packaging drum or turret 14. As it passes around the heating drum 13 and the packaging drum 14, it is gripped along its edges by a belt 16 which may press it into shallow grooves for better gripping.

A s it passes around the packaging drum, portions of the film 11 are drawn by suction successively into each of a series of cups 17 to form pockets in the film. As seen in Fig. 1, the c ups 17 may be elongated to take elongated articles such as a head of celery. After the film has been drawn into one of the cups 17 and is firmly held therein by the suction, the cup 17 Vis lowered by a cam track 18. In this manner the neck portion of the film pocket is further stretched. The article to be packaged will be dropped into the pocket just before or during this further stretching of the pocket. During the further stretching of the pocket the lm will have been supported between the cups by the bars 19 and as each cup approaches its retracted position, the adjacent bars 19 are swung over the cup to close the neck of the pocket, thus sealing the wrapper about the article. A resistance wire 21 is now connected to a source of current to be heated so that it severs the wrapped article from the film. At an appropriate time the cooperating closure bars 19 are drawn apart to release the wrapped article which may fall onto a conveyor.

Although the law requires a full and exact description of at least one form of the invention, such as that which follows, it is, of course, the purpose of a patent to cover each new inventive concept therein, no matter how it may later be disguised by variations inV form. or additions of further improvements; and the appended claims are intended to accomplish this purpose by particularly pointing out the parts, improvements or combinations in which the inventive vconcepts are found.

Drum construction As seen best in Fig. 4,` the drum 14 is carried by a shaft 23 whichin` turn 4rotates in 'frame members 24. A sprocket 26 drives the shaft which .in turn ldrives the drum 14.

A drum 14 includes an inner cylinder 27 having end plates or hubs 28 'engaging the shaft 23. Extending outwardly from cylinder 27 and carried vthereby are spokes or spoke plates 29, each pair of which .isv connected near its outer end by a plate 31, thus 'forming a U-shaped composite spoke. Rims 32 are carried by spokes 29 and are formed with annular grooves to receive belt 16, the hlm 11 being gripped between the grooved .rims 32 and the belt 16. Between successive pairs of spokes .29, guide plates 33 are secured. The various parts of the drum Vso far mentioned may be welded together.

Guide rods 34 carrying cups 17 'slide through aper tures in the guide plates 33 and apertures aligned therewith in cylinder 27. The cups 17 are moved radially inwardly and outwardly by cam track 18 at opposite ends o'f ydrum 14, cams 18 engaging cam follower rollers 37 carried by studs 38 extending outwardly 4from the ends of cups 17. The studs 38 are preferably separable from Vthe cups 17 (being threaded to them) `to facilitate assembly and removal of the cups. The cams or cam 19acks '18 ymay be secured to frame 24 by 'brace members A pair of spaced bearing vblocks 41 'is Isecured to each .guide vplate 33. -Pairs of shafts 42 pass through the bearing blocks v41. On these shafts are mounted the closure bars 19. As best seenlm lFig. 4, each closure Ir'od 19 comprises a U-shaped member. As best seen in Fig. 6, each closure bar 19 .is operated by a crank arm 43 at each end thereof. At the end of each crank arm 43 isa roller 44. There may be a yieldable connection to `guard against Vbreakage. if movement of bars `19 Lis obstructed. Ascup 17 approaches theretracted position, [a plate 46 carried at the bottom 'thereof engages the four associated rollers 44, Vone for each ofthe crank arms `43, shownfinfFi'g. 4, thus swinging-the arms 43 downwardly or toward the center ofthe drum. This swings @the 4closure bars 19 toward one another, as best illustrated in Fig. 7, .thus closing the wrapper about the article.

Each cup 17 is provided with a groove 48, extending i all around the inside wall thereof, as best seen in Fig. 7. The upper part of this groove is connected by a tube 49 (Fig. 4) with a source of suction to be described. -As each cup 17 passes into contact with the film approaching the drum 14, suction will be applied through groove 4S to evacuate the air from the cup 17, at least partially. This will draw the lm into the cup and sufficiently into groove 48 to securely hold the film within the cup. Thus as the pocket is restricted by cam tracks 18, the film 11 will be stretched in that portion thereof between closure rods 19 and the cups 17 or, more specifically, the groove 48.

` The-neck portion of the pocket thus stretched will be under considerable tension. However, snapping apart of the sides ofthe package upon severance of the web by heated wire 21 is prevented by a rubber gripping strip 51 (Fig. 8) carried by one bar 19 which presses the portions of film 11 against insulating facing 52 carried by the other bar 19. A second resistance wire 53 is heated to a lower temperature than wire 21, the temperature of wire 53 being appropriate for sealing the two layers of film 11 together, thus completely sealing the wrapper so that when released the wrapped article will have the desired sealed-in characteristics. Proper contact of the film with wires 21 and 53 is ensured by rib 51 and a flange 54 which cooperate to wrap the films partially around the wires 21 and 53.

The wires Z1 and 53 may be secured to insulating facing 52 carried by one of the bars 19 in any manner, as by being laced through holes therein.

The articles will be dropped into the cups 17 approximately at the top of the drum. They may be dropped manually but ordinarily a feed device will be desired to drop them in timed relationship to the movement of the cups; As the cups are rotated around the drum, smaller articles may fall or slide from the cups prematurely. To prevent this, a retaining plate 56 is pivotally carried by the-bar 19 which will be lowermost at this stage of the cycle. When the closure bars 19 open, the plate 56 swings out ofthe way, as seen in Fig. 6.

The closure bars 19 are spread apart by coil springs 57 which, as seen in Fig. 4, are positioned at opposite ends ofeach cup. As seenin Figs. 2 and 7, each coil spring 57 has arms 58 extending upwardly therefrom to engage the closure bars 19.

Vacuum connections port associated with that cup moves into facing alignment with a manifold groove 62 in stationary manifold disk 63 of a different metal, such as brass. The manifold groove 62 is connected by a pipe or hose 64 (traced best in Fig. 2),to a vacuum pump 66. As seen in Fig. 5, vacuum pump 66 may driven by a motor 67. The manifold disk 63 may be restrained from turning by engagement with any portion of frame 24. It is maintained in a snug sliding engagement with valve disk 61 by a collar 63 provided with a set screw 69. This collar applies its thrust to manifold plate 63 through a rolling type of bearing 71. The adjustment of collar 68 is such as to pass valve plate 61 against manifold plate 63. Friction and leakage may be minimized by oil grooves 70. The extent of groove 62 is such as to apply suction to the cup shortly after the film is applied over the cup and to discontinue the suction just before the closure rods 19 complete their closure. This timing of the release of the suction minimizes the entrapment of air within the package. The release of the suction is made effective by a port 72 (Fig. 2) through manifold plate 63, which allows air to rush into the cup 17 at the appropriate time.

T ming of cut- 6 The timing of the supply of current to the wires 21 and 53 may be controlled in any suitable manner. For example, each of these wires for a given cup may be connected to a brush 74 (Fig. 3) approximately aligned with that cup. The circuit will be completed while the brushes 74 are in engagement witha fixed contact plate 76 secured to the machine frame but insulated therefrom. The con- 4 tact plate 76 may be energized by a suitable transformer which may be variable or connected through a variable resistance to control the temperature to which the wires are heated. Sealing wire 53 may have a higher resistance than cut-ofi` wire 21, so that it will carry less current and maintain a lower temperature.

Gripping belts The gripper belts 16 grip the edges of the film within the groove in rims 32 throughout the period that the film is being stretched by suction into the cups and by movement of the cups. Preferably the belts also grip the film in a similar manner as it passes around heating drum 13. Adjacent the main drum 14 and heating cylinder 13 the belts pass around idler pulleys 78. The return runs of the belts may take any course but preferably extend over pulleys 79 which are laterally offset outwardly from the main drum so that the return runs of belts 16 will cause no interference at the filling position. The offset position of pulleys 79 is best seen in Figs. l and 5. The tension of the belts may be adjusted in any suitable manner as by tensioning pulleys 81 on brackets 82 which (as best seen in Fig. 5) are slidably positioned on the frame, being secured by bolts in any desired position.

Path of film As the film 11 is drawn from roll 12, it may be tensioned by a suitable brake 83, best shown in Fig. 2. A brake acting on the periphery of roll 12 may be used, if preferred, for more uniform tension. The film passes under guide rollers 84 over heating cylinder 13 around a roller co-axially mounted with intermediate pulley 78 and over main drum 14. As the belt 16 releases the residue of the film from which the packages have been cut, this waste film is rolled on a waste film roll S6. The latter is driven by a belt 87 which may be a coil spring belt to permit the roll 86 to accommodate itself to the speed of the waste film supplied to it.

The drum 14 may be driven by sprocket 26 on shaft 23. The sprocket 26 is driven by a chain 89 driven by a sprocket on shaft 91. The shaft 91 may also be used for driving the feeder and may be driven by a motor 92 through gear reduction unit 93 (Fig. l). The heating cylinder 13 may be driven by the belt 16.

Heating cylinder Although the heating cylinder 13 may take various forms, the illustrated form is preferred, inasmuch as it facilitates quick, accurately controlled, temperature changes and has other advantages. In this form, as best shown in Fig. 2, the metallic (aluminum) outer shell of the cylinder is heated by a liquid, such as oil, therewithin. To avoid using a large volume of liquid, the liquid is confined within a peripheral chamber formed by the outer shell and an inner shell spaced a little inwardly therefrom. This annular jacket thus formed is kept filled by a liquid reservoir 96, to and from which the liquid may fiow through a hollow bearing shaft of cylinder 13, fitted with a packing gland, as the liquid expands and contracts with changes in temperature. A plurality of heater rods extend into the jacket or into tube-like wells therein `at circumferentially spaced points. When the desired temperature is reached, an adjustable thermostat interrupts the circuit for alternate heaters, leaving the remaining heaters connected in a separate circuit to minimize temperature fluctuations. Temperature fluctuations can be further minimized by connecting the heaters to a variable transformer 98. A separate thermostat may disconnect the remaining heaters in the unlikely event that the temperature continues to rise due to excessive line voltage, or for any other reason.

I claim:

l. Apparatus for wrapping articles in film, including means for heating the film, a rotatable drum about which a web of the film passes, means for engaging the edges of the web as it passes about the drum, a series of cups arranged in sequence about the drum as at least part of the periphery of the drum, means for rotating the drum to move successive cups into position to contact successive portions of the film, means for applying suction within the cups during a portion of their rotation to form pockets in the film bydrawing said contacted portions of it into the cups, the inner walls of the cups being provided With suction grooves for L grippingl thepockets when they are drawn into the cups by suction, means f ormov-- ing the cups toward the axisrof the drum while the pockets are held therein and shiftable means for supporting lthe film between the cups as the cups are thus moved, means operated by the movement of the cups for shifting the means supporting the film between the cups to close the sides of `the film against one another and spring means urging said supporting means apart.

2. Apparatus for wrapping articles in filmJvincluding a rotatable drum about which a web of the film passes, means `for engaging the edges of the web as it passes about the drum,- a series of cups arranged in sequence about the drum as at least part of the periphery of the drum, means for rotating the drum to move successive cups into position to contactsuccessive portions of the film, means for applying suction within the cups during a portion oftheir rotation to form pockets in the lm by drawing said contacted portions of it into the cups, the inner walls ofthe cups beingprovided with suction grooves for gripping the pockets when theyl are drawninto the cups by suction, means for moving the cups toward the axis of the drum while the pockets are held therein and shiftable means for supporting the film between the cups as the cups are thus moved, means operated by the movement; of the cups for shifting the means supporting the film between the cups to close the sides of the film against one another and spring means urging said supporting means apart.

3; Apparatus for Wrapping articlesin film,` including a rotatable drum about which a web of the film passes, means for engaging the edges of the web as it passes about the drum, a series of cups arranged in sequence about the drum as at least part of the periphery of the drum, means for rotating the drum to move successive cups into position to contact successive portions of the film, means for applying suction within the cups during a portion of their rotation to form pockets in the film by drawing said contacted portion of it into the cups, means for moving the cups toward the axis of the drum While the pockets are held therein and shiftable means for supporting the film between the cups as the cups are thus moved, means operated by the movement of the cups for shifting the means supporting the film between the cups to close the sides of the film against one another and spring means urging said supporting means apart.

4. Apparatus for wrapping articles in film, including a rotatable drum about which a web of the film passes, means for engaging the edges of the web as it passes about the drum, a series of cups arranged in sequence about the drum as at least part of the periphery of the drum, means for rotating the drum to move successive cups into position to contact successive portions of the film, means for applying suction within the cups during a portion of their rotation to form pockets in the film by drawing said contacted portions of it into the cups, means for moving the cups toward the axis of the drum while the pockets are held therein and shiftable means for supporting the film between the cups as the cups are thus moved, means for shifting the means supporting the film between the cups to close the sides of the film against one another.

5. Apparatus for Wrapping articles in film, including a rotatable drum about which a web of the film passes, means for engaging the edges of the web as it passes about the drum, a series of cups arranged in sequence about the drum as at least part of the periphery of the drum, means for rotating the drum to move successive cups into position to contact successive portions of the film, means for applying suction within the cups during a portion of their rotation to form pockets in the film by drawing said contacted portions of it into the cups, means for moving the cups toward the axis of the drum while the pockets are held therein and shiftable means for supporting the film between the cups as the cups are thus moved and for closing the pockets formed in the film by said cups by pressing together the sides of the pockets stretched by movement of the cups.

6. Apparatus for wrapping articles in film, including a rotatable drum about which a web of the film passes, means for engaging the edges of the web as it passes about the drum, a series of cups arranged in sequence about the drum as at least part of the periphery of the drum, means for rotating the drum to move successive cups into position to contact successive portions of the film, means for applying suction within the cups during a portion of their rotation to form pockets in the film by drawing said contacted portions of it into the c'ups, means for moving the cups toward the axis of the drum while the pockets are held therein and shiftable means for supporting the film between the cu'ps as the cups are thus moved and for closing the pockets formed in the film by said cups by pressing together the sides of the pockets stretched by movement of the cups, and aA cut-off resistance wire carried by said closure means; and; energizing means for heating the resistance wire to sever the Wrapped article from the web.

7. Apparatus for wrapping articles in film, including a rotatable drum about which a web of the film passes, means for engaging the edges of the web as it passes about the drum, a series of cups arranged in sequence about the drum as at least part of the periphery of the drum, means for rotating the drum to move successive cups into position to contact successive portions of the film, means for applying suction Within the cups ,during a portion of their rotation to form pockets in the film by drawing said contacted portions of it into theicups, means for moving the cups toward the axis of the drum while the pockets are held therein and shiftable means for supporting the film between the cups as the` cups are thus moved and for closing the pockets formed in the film by said cups by pressing together the sides of the pockets stretched by movement of the cups, a cut-off resistance wire carried by said closure means, energizing means for heating the resistance wire to sever the wrapped` article from the web, and a second resistance wire located toward the cups from the cut-ofi wire and adapted to be heated to a lower temperature for sealing the contacting portions of the film.

8. Apparatus for wrapping articles in film, including a rotatable drum about which a web of the film passes,\ means for engaging the edges of the web as it passes about the drum, a series of cups arranged in sequence about the drum as at least part of the periphery of the drum, means for rotating the drum to move successive cups into position to contact successive portions of the film, means for applying suction within the cups during a portion of their rotation to form pockets in the film by drawing said contacted portions of it into the cups, means for moving the cups toward the axis of the drum while the pockets are held therein and shiftable means for supporting the film between the cups as the cups are thus moved and for closing the pockets formed in the film by said cups by pressing together the sides of the pockets stretched by movement of the cups, a cut-off resistance wire carried by said closure means, and energizing means for heating the resistance wire to sever the wrapped article from the web, a second resistance wire located toward the cups from the cut-off wire and adapted to be heated to a lower temperature for sealing the contacting portions of the film, and gripping means adjacent the second resistance wire and adapted to grip a portion of the film and press it against said sealing wire.

9. Apparatus for wrapping articles in film, including a rotatable drum about which a web of the lm passes, means for engaging the edges of the web as it passes about the drum, a series of cups arranged in sequence about the drum as at least part of the periphery of the drum, means for rotating the drum to move successive cups into position to contact successive portions of the film, means for applying suction within the cups during a portion of their rotation to form pockets in the film by drawing said contacted portions of it into the cups, means for moving the cups toward the axis of the drum while the pockets are held therein and shiftable means for supporting the film between the cups as the cups are thus moved and for closing the pockets formed in the film by said cups by pressing together the sides of the pockets stretched by movement of the cups, means carried by the closure means to retain the wrapped articles in the drum until the closure means opens.

l0. Apparatus for sealing fills in film wrappers including a rotating drum having a series of cups rotatable with the drum and movable radially between a position outermost of the drum to contact successive portions of a web of film passing about the drum to an inner position, means for applying suction to the cups in their outermost position to pocket the film into the cups, means for moving each cup inwardly while the pocket is held therein and while restraining adjacent parts of the lrn to stretch the neck of the pocket, and closure means for closing opposite sides of the stretched neck upon each other.

11. Apparatus for wrapping articles in film, including a cup, means for advancing a film across the cup, means for applying suction within the cup to draw the iilm into the cup in the form of a pocket, means for moving the cup in a direction to deepen the pocket, and c1amp-type closure members for restraining surrounding portions of the film and for pressing together opposite sides of the deepened pocket.

12. Apparatus for wrapping articles in lm, including a cup, means for advancing a film across the cup, means for applying suction within the cup to draw the lm into the cup in the form of a pocket, means for moving the cup in a direction to deepen the pocket, and clamp-type closure members for restraining surrounding portions of the film and for pressing together opposite sides of the deepened pocket, said cup being of an elongate shape in a direction parallel to the length of the clamp-type members.

13. Apparatus for wrapping articles in thermoplastic film, including a heating roll and a turret roll, means for passing a web of film successively around the heating roll and turret roll, said turret roll including means for drawing a pocket into the web, means for gripping the central portion of the pocket to stretch the neck portion of the pocket, and means for closing the pocket to seal an article within the pocket.

14. Apparatus for wrapping articles in film, including a rotatable drum about which a web of the film passes, means for engaging the edges of the web as it passes about the drum, a series of cups arranged in sequence about the drum as at least part of the periphery of the drum, means for rotating the drum, to move successive cups into position to contact successive portions of the film, means for applying suction within the cups during a portion of their rotation to form pockets in the film by drawing said contacted portion of it into the cups, means for moving the cups toward the axis of the drum while the pockets are held therein and shiftable means for supporting the film between the cups as the cups are thus moved.

15. Apparatus for sealing fills in film wrappers including a rotating drum having a series of cups rotatable with the drum and movable radially between a position outermost of the drum to contact successive portions of a web of film passing about the drum to an inner position, means for applying suction to the cups in their outermost position to pocket the film into the cups, means for moving each cup inwardly while the pocket is held therein and while restraining adjacent parts of the film to stretch the neck of the pocket.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,642,361 Crowell Sept. 13, 1927 1,672,036 Ollman June 5, 1928 1,802,968 Everett et al. Apr. 28, 1931 1,958,137 Fowler May 8, 1934 2,122,254 Kranich et al. June 28, 1938 2,425,581 Vincent Aug. 12, 1947 2,486,761 Pfeiffer Nov. 1, 1949 2,490,781 Cloud Dec. 13, 1949 2,549,123 Osterhof Apr. 17, 1951