US3523492A

US3523492A - Apparatus and method for attaching a flexible bag to a container body

Info

Publication number: US3523492A
Application number: US736400A
Authority: US
Inventors: John K Bruce; Roger K Bruce
Original assignee: Sterigard Corp
Current assignee: Sterigard Corp; STERIGARD CO
Priority date: 1968-06-12
Filing date: 1968-06-12
Publication date: 1970-08-11
Anticipated expiration: 1987-08-11

Description

United States Patent [72] Inventors John 1(- Bru 2,364,012 11/1944 Walton 53/175X Santa California; 2,403,998 7/1946 Pottle 93/59(CE)UX Rog r R Br Costa Mesa, California 2,546,137 3/1951 Schmidt 93/3601 [21] A pp 736,400 2,601,547 6/1952 Minock 29/235X Filed June12,l968 2,914,845 12/1959 Crites 29/450 [45] Patented: Aug ll, 1970 3,126,797 3/1964 Carpenter 93/3601 1 1 Assignee Slmgard ig x 3,266,390 8/1966 Carpenter 93/3601 Santa Callfflmla 3,272,094 9/1966 Carpenter 93/77(C a California Limited Partnership 3,281,927 11/1966 Buslaff 29/450x Primary Examiner-Wayne A. Morse, Jr. [54] APPARATUS AND METHOD FOR ATTACHING A A! f Omeys Christie, Parker and Halfi FLEXIBLE BAG TO A CONTAINER BODY 24 Claims, 10 Drawing Figs.

[52] U.S. Cl 93/361", ABSTRACT; A l lit f a a t ated fingers are disposed 93/8. 93/3 53/175, 29/235, in a radial array to expand the mouth ofa bag prior to the at- 29/450 tachment of the bag over the top of an open container body. Int. Cl The fingers are a tuated a cam plate having a plurality of I 33113 1/52, 1331b 1/90 cam slots configured such that alternate fingers move radially [50] Field of Search 93/8(WA), inward ahead f their neighbors w a contracted i i i 36-01, ll i 84(FF)? the fingers expanded position, the bag's mouth is expanded slightly to receive a container body. With the fingers in their expanded position, the container is raised by a ram to a posi- [56] References C'ted tion where the container's top flange extends slightly above UNITED STATES PATENTS the fingers to engage the bag. The fingers are relaxed slightly 1,879,410 9/1932 Morris 93/36.01X against the side of the container and the ram continues up- 1,965,876 7/1934 Bettis 29/450 ward through the fingers to remove the bag from the fingers 1,993,751 3/1935 Reid 93/84(FF)UX and allow the bag to collapse tightly against the outer surfaee 2,152,941 4/1939 Wilcox 93/3601 of the container body.

60 if 60 .Ww b M y I; l /J a! /4 1 a //i e ,1 7 Z, I

,y 1 .42" w" d t m 1' 1 1;; 44.. 11 i i6 /fl4 .92 :4 W I M l M f 56 M 42 M g g .1 rg fl g 2Z. gZ a) Q? a/Q Patented Aug. 11, 1970 Sheet l of 6 Patented Aug. 11, 1970 3,523,492

@066? K Eel/6'5 Patented Aug. 11, 1970 3,523,492

Sheet 3' of 6 Pater ated Aug. 11, 1970 Sheet Patented Aug. 11, 1970 Sheet APPARATUS AND METHOD FOR ATTACHING A FLEXIBLE BAG TO A CONTAINER BODY BACKGROUND OF THE INVENTION The present invention relates in general to the art of fabricating containers and, more particularly, to an apparatus and method for attaching a flexible bag to a container.

Pressurized containers for dispensing various products are becoming increasingly popular. One of the most effective pressurized containers is described in US. Patent Application, Serial No. 548,963, filed on May 10, 1966 how Patent No. 3,393,842, issued July 23, 1968, and assigned to the same assignee as this application. The pressurized container utilizes a flexible bag or tube disposed within a container body. A propellant urges against one side of the bag to force the product on the other side of the bag through an actuated valve. The flexible bag is mounted on the container body by stretching it over the top of the container with a portion of the bag extending down the outside wall of the body. The container cap is then seamed onto the container to hold the bag firmly in place.

In fabricating a bag-in-can type container, it is necessary to expand the mouth of the bag for its placement over the top of the container body prior to the cap-seaming operation. Slight expansion of the mouth ,of the bag is required to produce direct tensioned contact of the bag with the outside surface of the container body. Because of the limited flexibility of presently suitable materials available for the bags, the amount of stretching cannot be too great if tearing or distortion of the bag material is to be avoided.

The requirement for expanding the mouth of the bag for its attachment to the body of a container leads to problems in placing the container body for receipt of the bag. The container body must have enough room to enter the expanded portion of the bag without interfering with the means for holding the bag in its expanded position.

These requirements must be met in a manner allowing rapid and economical fabrication of containers having a bag. The bag must be rapidly expanded to receive the container body. Provision must also be made to allow the bag to contract and stretch over the outside of the body of the container. Moreover, the bag itself must be placed within the container after the mouth of the bag is expanded over the container body. Preferably, the container must, as well, be able to pass through the means for expanding the bag after the bag has been attached.

SUMMARY OF THE INVENTION The present invention provides an apparatus and method for expanding the mouth of a flexible bag and attaching it to an end of a container body.

Briefly, the invention contemplates a base, a plurality of radially actuable bag engaging fingers and means for moving the fingers radially inward to a contracted position to selectively accept and release the bag and moving the fingers radially outward to an expanded position to engage and expand the inner surface of the bag proximate its mouth.

Preferably, the base has a passage sized for the passage of the container body. The fingers are slidably disposed on the base for radial movement towards and away from the center of the passage between the expanded and contracted finger positions. Each of the fingers has an outer radial bag engaging surface for engaging the inner surface of the bag around the bags mouth.

In preferred form, the bag engaging surface of the fingers takes a blade-like configuration and the fingers are actuated by a cam plate.The cam plate has a plurality of cam slots corresponding in number to the number of fingers. Each of the blade-like elements is attached to a body or cam follower which is slidably received in radial slots in the base. Means are provided such as inner and outer radial ,stop positionsin the cam slots-to determine the limit of radial travel of the fingers.

The fingers are operably engaged to the cam plate through the cam slots such that upon rotation of the cam plate the cam followers move in unison between the inner and outer radial stop positions to respectively contract and expand the fingers.

It is preferred to have a substantially continuous bag engaging surface defined by the sum of the individual bag engaging surfaces of the fingers in their expanded position. In order to effect this substantially continuous engaging surface between the fingers and the bag and yet provide for bag placement on the fingers, it is also preferred to have alternate fingers move radially inward ahead of their neighbors to the contracted finger position. This allows a greater bag engaging surface for a given engagement circumference while at the same time providing clearance and the ability of inward movement of the fingers to the contracted position. The facility of having alternate fingers move radially inward ahead of their neighbors may be accomplished by configuring the cam slots such that the alternate fingers move faster inwardly than their neighbors to the contracted position. Thus, the preferred cam slot configuration has a radial rate of change for the path of the slower fingers less than the corresponding radial rate of change of the path of the fast fingers. It is also preferred that the fast fingers occupy a finger contracted position radially inward of the slower fingers. A neck is provided between the blade-like elements and the cam followers of the fast fingers such-that in the contracted position the slower fingers nest in the necks.

The container body to which the bag is applied is preferably positioned by means such as a ram that moves the container body through the base 5 passage inwardly of the expanded fin gers with the flange of the container body just over the top of the fingers blade-like elements. The bag is attached to the container body by collapsing the blade-like elements against the container body below the flange and continued movement of the ram to strip the mouth of the bag from the blade elements into tensioned contact against the outer surface of the container body. A vacuum may be applied through the ram to draw the bag inside the container body. The lower flange of the container is passed through the fingers by once again expanding the fingers outwardly. In order to guide the container in its upward travel through the base, a guide throat is provided which has two diametrically opposed springs positioned to aid in axially aligning the container as it advances through the passage. The springs also act to hold the container below the fingers in the event that station-to-station container fabrication is used.

By the present invention, flexible bags may be rapidly and expeditiously attached to container bodies. The fingers expand the bag at its mouth radially outward while allowing the placement of the container body inwardly of the expanded fingers in position to receive the bag. The cam plate and the alternate cam slot configuration allow the fingers to present'a substantially continuous bag. engaging surface while allowing for finger contraction to release the bag to be removed by the container body and subsequently accept a new bag. This is a particularly salient feature inasmuch as the amount of bag expansion cannot be great and yet the expansion must be uniform for accepting the container body. The blade-like finger engaging elements also provide for relatively little expansion with sufficient room for the container body and its flange to pass interiorly of these elements. The container body itself may be readily positioned by a ram or the like and the bag drawn into the body by, for example, a vacuum applie through the ram. 1

These and other features, aspects and advantages of the present invention will become more apparent from the following description, appended claims and drawings.

BRIEF DESCRIPTION OF THE FIGURES FIGURE lis an elevational view in half section, partly broken away, taken along line 1-1 of FIGURE 2, showing a preferred embodimentjof the bag applicator of the present invention; 7

FIGURE 2is a plan view taken along line 2 2 of FIGURE 1;

FIGURES 3 and 4 are perspective views of the cam actuated fingers employed in the embodiment of the invention illustrated in FIGURES I and 2;

FIGURE 5 is a plan view, partly broken away, of the em- ;bodiment ofthe invention shown in the first two FIGURES;

FIGURE 6 is a partial view illustrating the movement ofa container into the applicator with an expanded bag ready to be received by the container;

FIGURE 7 is another partial view illustrating the attachment of the bag to the container;

FIGURE 8 is a partial view illustrating the container with the bag fixed and in condition to be removed from the applicator;

FIGURE 9 is a schematic wiring diagram illustrating the electrical circuitry ofthe present invention; and

FIGURE I is a schematic diagram illustrating the pneumatic circuitry of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGURES l, 2 and illustrate the applicator of the present invention. The applicator is shown in general by reference numeral 10. The applicator includes a base 12, a cam plate 14 and a plurality of radially actuable fingers 16.

As seen to best effect in FIGURE 1, base 12 includes a retainer plate 18, a guide throat 20, a pair of support bars 22, 24, and a body 26. A container passage 28 is provided through base 12.

Retainer plate 18 is generally square in configuration and has a plurality of holes 30 for fasteners. The retainer plate has a cylindrical hole 32 for the mounting of guide throat 20. A pair of rectangular support bars 22 and 24 extend across retainer plate 18 and are spaced apart from each other. These support bars are fastened to retainer plate 18 by a plurality of flush head screws 34 disposed in holes 30 and received in female threads in the support bars Support bars 22 and 24 may be adapted with mounting slots or apertures 36 to receive pins 38 which extend inwardly from a pair of endless chains 40 and 42. The endless chains provide a means for moving applicator from various stations in an automated assembly.

Body 26 is fastened to support

bars

22 and 24 through a plurality of threaded fasteners 44 received in mating female threads in the support bars. The body is thus made integral with retainer plate 18. An annular bore 46 in body 26 receives the upper portion of guide throat 20.

Body 26 is integrally formed into two sections. The first section is generally square with a perimeter matching that of retaining plate 18. This section is indicated by reference numeral 48. The second section of body 26 is generally circular and is indicated by reference numeral 50. Section 50 has an inner bore 52 which defines a part of container passage 28. A plurality of regularly spaced and radially disposed slots 54 are provided in body section 50 for guiding fingers 16. In the embodiment illustrated, there are twelve of these radially disposed slots. The radial array of slots 54 is most clearly depicted in FIGURE 2.

Guide throat is illustrated in FIGURE 1. The guide throat includes an annular, radially outward extending mount ing flange 56 disposed between the lower horizontal surface of body 26 and the upper surface of retainer plate 18. Throat 20 has an upwardly converging, frusto-conical belled mouth 58 for centering a container passing upwardly into passage 28. The throat further includes an annular cylindrical wall 60 which merges into mouth 58 at the latters upper end and terminates at the plane between

sections

48 and 50 of body 26.

A pair of diametrically opposed

leaf springs

62 and 64 extend upwardly towards each other through spring slots 66 in throat 20. The springs are mounted to the guide throat by a pair of screws 68. These springs serve to center a container as it passes through passage 28. The springs are operable to deflect over the upper flange of the container body as illustrated in FIGURE 6 and to retain the container body in this position in the event that station-to-station fabrication is used. For example, it may be required to advance applicator I0 to a location removed from that at which it received the container body for the placement ofa bag over fingers I6.

Fingers 16 are constructed to define a substantially continuous circle when expanded (FIGURE 2) and for an overlapping relationship when contracted (FIGURE 5). For this purpose, there are two types of fingers indicated by reference numerals and 82. Fingers 80 are spaced between two of the fingers 82. Each type of finger is illustrated in detail in FIGURES 3 and 4.

Each of the fingers 82 includes a generally rectangular cam following portion 84 which is slidably disposed in one of the slots 54. A blade-like element 86 is integrally connected to the cam following portion at the latters inner terminus. Blade element 86 extends above the cam following portion. A radial, outwardly extending flange or step 88 extends above cam following portion 86 to the rear of blade element 86 and terminates below the upper end of the blade element. The upper surface of this step provides a lower positioning stop for bags placed over the finger. The inner surface of blade element 86 has a slight concave curvature indicated by reference numeral 90. This concave curvature is to conform to the outer surface of the container to which a bag is applied by the applicator. Concave surface 90 meets a tapered face 92 at the inner end of cam following portion 84. The tapered face extends to approximately the lower end of flange 88. Tapered faces 92 guide the container as it passes inwardly of blade elements 86. A bag engaging surface 94 is defined by the outer radial surface of blade 86 above flange 88. This bag engaging surface is curved convexly to define, with the similar surfaces of fingers 80, a substantially continuous circular bag engaging surface when the fingers are expanded.

Fingers 80 are of a slightly different configuration than fingers 82. These fingers are disposed in alternate of the slots 54 between fingers 82. Fingers 80 include a cam following portion 96 similar in configuration to cam following portions 84 of fingers 82. The cam following portion meets a blade element 98 through a flange 100. Flange 100 extends above the upper surface of cam following portion 96 and terminates at the same point as do steps 88 of fingers 80 to cooperate with these steps in providing a lower terminus for bags placed over the fingers. An inner concave surface 102 ofblade element 98 extends vertically from the top of blade element 98 to a tapered face 104 which is at the inner end of flange 100 and cam following portion 96. The curvature of surface 102 is the same as that of surface 90 offinger 82. A convexly curved bag engaging surface 105, having the same curvature as its associated surface 94 of fingers 82, extends from the top of blade element 98 to flange 100. As is seen in FIGURE l, tapered faces 104 cooperate with tapered faces 92 of fingers 82 to guide the container from guide throat 20 as it ascends through applicator l0. Flange 100 is necked towards cam following portion 96. Cam following portion 96 is also necked at 101 to its juncture with flange 100. The vertical flanks of finger 80 defined by this necking provide a recess for blade element 86 of fingers 82 when the finers are in the contracted condition illustrated in FIGURE 5.

Fingers

80 and 82, then, are disposed in a radial array in slots 54 with their blade elements facing the center of passage 28. The fingers are operable to expand into the FIGURE 2 configuration which defines, by the outer radial surfaces 94 and 105 of the blade elements, a generally cylindrical and continuous bag engaging surface. The fingers are operable to extend inwardly towards the center of passage 28 and overlap one another in the FIGURE 5 configuration. This collapsed or contracted configuration is possible because of the necking of cam following portions 96 and flanges 100 of fingers 80. To produce this overlapping relation, fingers 80 must travel from their expanded position to their contracted position faster than fingers 82. This is provided by the unique configuration of cam plate 14.

Cam plate 14 is rotatably mounted on upper section 50 of body 26. The cam has an annular opening 108 for the passage of the upwardly extending blade elements of

fingers

80 and 82. A circular register ring 110 maintains cam plate 14 in its proper axial position. The register ring is attached through a plurality of screws 112 to upper section 50 of body 26.

As is seen in FIGURE 2, a plurality of first and second sets of cam slots 114and 116 are present in the cam for the actuation of the fingers.

Cam slots 114 are operably engaged by fingers 82 through rollers 118. Pins 120 secured in cam following portions 84 of fingers 82 rotatably mount rollers 118 in cam slots 114. In the outer radial position shown in FIGURE 2, rollers 118 are confined against further outward radial travel by the outer radial limits of cam slots 114. The inner limit of finger travel, shown in FIGURE 5, is determined by the inner radial end of cam slots 114. Fingers 82 will experience radial-travel towards and away from the axis of passage 28 corresponding to the radial center-to-center distance of pin 120 in cam slot 114. This cam slot has walls which are curved to effect a slower rate of inward travel of fingers 82 than the corresponding rate of travel of fingers 80. This difference may be viewed as a relatively low rate of change of radius with angular displacement of pin 120 as it begins its traverse from the FIGURE 2 to the FIGURE 5 position.

Cam slots 116 are responsible for radial movement of fingers 80. A plurality of pins 122 secure a plurality of rollers 124 to cam following portions 96 of fingers 80. The inner limit of radial travel for fingers 80 is determined by the inner end of cam slots 116. The outer radial position of these fingers, shown in FIGURE 2, is determined by the outer radial limit of slots 116. Because of rollers 124, the amount of radial travel for fingers 80 is again determined by the center-to-center radial distance of pins 122 between their expanded and contracted positions. The innermost radial position of pins 122 is slightly closer to the axis of passage 28 than the innermost radial position of pins 120. Accordingly, fingers 80 will extend slightly closer to the axis of passage 28 than fingers 82.

Cam plate 14 is attached to a positioning plate 126 by a plurality of screws 128. Thus, cam plate 14 is carried by positioning plate 126. As is most clearly shown in FIGURE 5, positioning plate 128 has a pair of camming lugs 130. These lugs may be used to contact cams to effect the rotation of the positioning plate in its carried cam 14 as applicator moves with endless chains 40 and 42.

FIGURES 6 through 10 depict a typical application ofa bag onto a container by applicator 10. FIGURES 6, 7, 8 and 10 illustrate a bag 132. FIGURE 8 illustrates bag 132 attached to a container body 134. The container body is fabricated from rigid metallic tubing and has seaming

flanges

136 and 138 at its top and bottom. The bag is fabricated from plastic tubing and is closed at its bottom 140 as by a heat seal. The top of bag 132 is open for its expansion and insertion around seaming flange 136 and the contiguous upper external portions of container 134. A ram 142, actuated through a double acting pneumatic piston and cylinder 144, carries container body 134 through container passage 28 in applicator l0.

Cam plate 14'is actuated through positioning plate 126 to contract and expand fingers 16. Positioning plate 126 has an arm 146, shown in FIGURE 10, for this rotational movement. Arm 146 replaces camming lugs 130. The arm is attached at one end to the top of the positioning plate and pivotally connected at its other end to the shaft of a spring-biased piston and cylinder 148. The spring-biased cylinder maintains fingers 16 in the normally contracted position illustrated in FIGURE 5.

A detailed description of the pneumatic and electrical circuitry required for the type of operation illustrated in FIGURES 6 through 8 will be presented as this description proceeds. Before this description, it is helpful to understand the operation of the applicator itself. Ram 142 elevates container 134 into-passage 28 with fingers 16 in their expanded FIGURE 2 position. Flange 136 will eventually be positioned slightly above the upper ends of the blade elements of

fingers

80 and 82. In this position, the flange begins to engage the bag proximate its mouth. Fingers 16 are expanded sufficiently to allow flange 136 to clear the fingers and engage the bag. FIGURE 6 illustrates this.

As illustrated in FIGURE 6, when container 134 begins its ascent into passage 28, it will be centered by bell-shaped mouth 58 of guide throat 20. Leaf springs 62 and 64 deflect over flange 136 against the smooth cylindrical portion of container body 134 and thereafter aid in maintaining the body in its centered position. As we previously mentioned, springs 62 and 64 may be used to hold container body 134 by flange 136 if applicator 10 is moved to a different location than its container receiving location. During the ascent, fingers 16 are fully expanded, as indicated by fingers 82 in FIGURE 6. Flange 136 will, therefore, pass through the expanded fingers to a point slightly above the fingers blade elements.

Before the ascent of container body 134, bag 132 was placed over the contracted fingers, shown in FIGURE 5. The

fingers were then expanded to expand the mouth of the bag v radially outward. This is shown in FIGURE 6. As was previously described, fingers 16 are expanded and contracted by rotational movement of cam plate 14. As the cam plate is rotated counterclockwise, as viewed in FIGURE 2,

cam slots

114 and 116 act through

rollers

118 and 124 to move fingers and 82 inward. Because of the difference in the radial rate of change between

slots

114 and 116 and the difference in their inner termini of travel, fingers 80 will move ahead of fingers 82 into the contracted position shown in FIGURE 5. Upon clockwise rotation of cam plate 14, the fingers will expand into their FIGURE 2 position.

At the point when flange 136 passes over the top of the fingers blade elements, fingers 16 are relaxed as shown in FIGURE 7. The fingers relax against the walls of container 134 proximate top flange 136. The relaxed fingers allow the bag wall proximate its mouth to contract inwardly around flange 136. At this point, bag 132 is effectively carried by container 134. After the bag is released from the fingers, the fingers are expanded to allow the free passage of container body 134, including its lower seaming flange 138, through the applicator. Ram 142 continues its vertical travel until container body 134 is completely free from the applicator as shown in FIGURE 8.

FIGURE 8 also illustrates the bag attached to container body 134. The bag material proximate its mouth is shown by reference numeral 150. This material is tightly stretched around the cylindrical wall of container 134 and extends over flange 136. The balance of bag 132 extends inwardly of the container and down towards its bottom. The bag reaches its FIGURE 8 orientation from the position shown in FIGURES 7 and 10 by vacuum applied through vacuum passage 152 in ram 142 during the rams vertical ascent.

FIGURES 9 and 10 illustrate an electrical and pneumatic circuit operable to obtain the results just described. A source of power is connected in series with an on-and-off switch 162. Switch 162 is in turn connected in series with stop-start switch 164. A delay timer 166 is serially connected to switch 164 and to ground. This timer has a set of normally closed contacts 168 which are electrically coupled in series with solenoid 170 and ground. Contacts 168 are also coupled in series through on-off switch 162 to power source 160. A normally closed limit switch 172 is connected in series with a solenoid 174 to ground. The limit switch is also wired to start-stop switch 164. Spring-biased air cylinder 148 is coupled to a source of air through a normally closed solenoid operated valve 176. The solenoid which operates this valve is solenoid 174. A solenoid operated valve is also coupled to the source of air to control double acting piston and cylinder 144.

Solenoid 170 controls valve 180. Valve 180 norrnally communicates the upper chamber of cylinder 144 with the source of air to maintain ram 142 in its lowered position.

When switch 162 is closed and switch l64'i's in position to energize delay timer 166, contacts 168 are opened. With contacts 168 open, solenoid 178 is out of circuit and therefore air valve 180 maintains the piston of airlift cylinder 144 in its down position. The actuation of switch 164 to couple solenoid 174 to power source 160 begins a time-out cycle forde'lay timer 166. During this time-out cycle, solenoid 1 74 is energized through limit switch 172 and actuating cylinder 148 acts through arm 146 to open fingers 16 to receive container 134 and expand the mouth of bag 132. At the completion of the time-out cycle, contacts 168 will close to energize solenoid 170. With the energization of solenoid 170, air valve 180 admits air to the lower part of cylinder 144 and ram 142 with its carried container 134 begins to rise for accepting bag 132. When flange 136 of container 134 just clears the top of fingers 16, as shown in FIGURE 4, limit switch 172 is actuated to open the circuit to solenoid 174. Valve 176 then closes and fingers 16 relax against the wall of container 134 below flange 136. This position is shown in FIGURE 7. The vacuum source is always energized and through line 152 draws bag 132 inside of container 134 as shown again in FIGURE 7. Ram 142 continues upward to clear limit switch 172. When the ram clears limit switch 172, solenoid 174 is energized. Valve 176 then communicates cylinder 148 to the air source. The fingers will then expand to free container body 134 and allow its lower flange 138 to rise above expanded fingers 16. This orientation is shown in FIGURE 8.

The present invention has been described with reference to certain preferred embodiments. The spirit and scope of the appended claims should not, however, necessarily be limited to the foregoing description.

We claim:

1. An apparatus for attaching a flexible bag to a container body comprising:

(a) a base;

(b) a plurality of fingers disposed on the base for radial movement towards and away from a center between an expanded and a contracted position, each of the fingers having an outer radial surface for engaging the inner surface ofthe bag proximate its mouth;

(c) means for moving the fingers radially inward to the contracted position to selectively accept and release the bag, and for moving the fingers radially outward to the expanded position to engage the inner surface of the bag proximate its mouth with the finger's engaging surfaces and to expand the engaged portion of the bag for the bags attachment to the container body; and

(d) means for moving one end of the container body inside the expanded fingers to accept a bag expanded by the fingers.

2. The apparatus claimed in Claim 1 wherein the finger moving means includes:

a cam plate rotatably mounted on the base and operably engaging each of the fingers such that rotation of the cam plate in a first direction moves the fingers radially inward to the contracted position and rotation in an opposite second direction moves the fingers radially outward to the expanded position.

3. The apparatus claimed in Claim 2 wherein:

(a) the engaging surfaces of the fingers in the expanded position define a substantially continuous cylindrical bag engaging surface; and

(b) the cam plate includes means to move alternate fingers inwardly ahead of the remaining fingers from the expanded position.

4. The apparatus claimed in Claim 3 wherein the cam plate means for moving alternate fingers inwardly ahead of the remaining fingers includes:

(a) a first set of cam slots corresponding in number to one half the number of fingers, each first set cam slot having an inner and an outer radial stop position angularly displaced from one another, the first set of cam slots operatively engaging a first set ofthe fingers for movement between the stop positions;

(b) a second set of cam slots equal in number to the first set of cam slots, each second set cam slot having an inner and an outer radial stop position angularly displaced from one another in the same angularsense as the stop positions of the first cam slot set, the second set ofcam slots operatively engaging a second set of the fingers for movement between the stop positions, the radial rate of change of each of the second set cam slots being lower than each of the first set cam slots for at least a portion of their length to effect a contracted finger position with the first set of fingers disposed radially inward of the second set of fingers; and

(c) The first and second cam slot inner and outer stop positions corresponding respectively to the contracted and expanded finger positions.

5. The apparatus claimed in Claim 4 wherein each of the fingers includes:

(a) a cam following portion, the fingers corresponding cam slot engaging the cam following portion; and

(b) a blade-like element integral with and extending above the cam following portion, the outer radial surface of the blade-like element defining the fingers bag engaging surface.

6. The apparatus claimed in Claim 5 wherein:

(a) each offirst set of fingers is necked between its bladelike element and cam following portion such that adjacent second set fingers in the contracted position nest in the recess defined by the neck; and

(b) the inner stop position of the first set of cam slots is radially inward ofthe inner stop position for the second set of slots to obtain the nesting of second set fingers in the neck recesses of the first set fingers.

7. The apparatus claimed in Claim 2 wherein:

(a) the base has a passage sized for the container body,

the means for moving one end of the container body inside the expanded fingers being operable to move the container body through the passage; and

(b) the fingers are disposed for movement towards the axis of the passage at a first end thereof.

8. The apparatus claimed in Claim 7 wherein:

the passage has a guide throat at its second end to center a container body as the container body enters the passage.

9. The apparatus claimed in Claim 8 wherein:

guide means are provided to center the container body between the guide throat and the first end.

10. The apparatus claimed in Claim 9 wherein the cam plate includes:

(a) a first set ofcam slots corresponding in number to one half the number of fingers, each first set cam slot having an inner and an outer radial stop position angularly displaced from one another, the first set of cam slots operatively engaging a first set of the fingers for movement between the stop positions;

(b) a second set of cam slots equal in number to the first set of cam slots, each second set cam slot having an inner and an outer radial stop position angularly displaced from one another in the same angular sense as the stop positionsof the first cam slot set, the second set of cam slots operatively engaging a second set of the fingers for movement between stop positions, the radial rate of change of the second cam slots being lower than the first set for at least a portion oftheir length to effect a contracted finger position with the first set of fingers disposed radially inward of the second set of fingers; and

11. An apparatus for attaching a flexible bag to a container body comprising:

(a) a base having a passage for the passage of the contamer;

(b) a plurality of fingers slidably disposed on the base'for radial movement towards and away from the axis of the passage between an inner contracted position and an outer expanded position;

(0) an upwardly extending bag engaging blade element on the inner radial end of each of the fingers, each blade element having a bag engaging surface on its outer radial side; (d) a cam plate rotatably mounted on the base and having a plurality of cam slots corresponding in number to the number of fingers, each of the fingers being operatively engaged with one of the cam slots and the cam slots being sized and disposed such that upon rotational movement of the cam plate the cam followers move in unison between the inner contracted position and outer expanded position; and

(e) means to rotate the cam plate to move the fingers between the contracted and expanded positions.

12. The apparatus claimed in Claim 11 wherein:

(a) the cam slots are divided into alternately disposed first and second sets of cam slots for corresponding first and second sets of fingers;

(b) the second cam slots have a radial rate of change with respect to a radial rate of change of the first cam slots to effect an inner contracted finger position with the blade elements of the first set of fingers disposed radially inward of the blade elements of the second set of fingers; and

(c) the first and second sets of cam slots are sized and disposed to effect an expanded finger position with the bag engaging surfaces of the fingers falling in a circle whose center is at the axis of the passage.

13. The apparatus claimed in Claim 12 including:

(a) means for moving a container body having an externally flanged open end through the passage;

(b) means coupled to the moving means to actuate the cam plate rotation means and move the fingers to the expanded finger position and expand the mouth of a flexible bag over the open end of the container body when the open end of the container body is inside the expanded fingers;

(c) means to actuate the cam plate rotation means to move the fingers inwardly against the outer wall of the container body below its flange when the open end of the container body is inside the expanded fingers; and

(d) means to actuate the cam plate rotation means to move the fingers to the expanded finger position after the moving means has moved the open end of the container body sufficiently to strip the bag off the fingers and onto the outside of the body proximate its flange.

14. The apparatus claimed in Claim 12 wherein each of the cam slots has an inner and an outer radial stop operative to engage its associated finger to arrest radial movement, the inner radial stops of the first set cam slots being radially inward of the inner radial stops of the second set cam slots to effect the contracted finger position wherein the blade elements of the first set of fingers are disposed radially inward of the blade elements of the second set of fingers.

15. The apparatus claimed in Claim 14 wherein:

(a) the inner radial stops of the first set of cam slots lie in a first inner common circle;

(b) the inner radial stops of the second set of cam slots lie in a second inner common circle having a radius from the axis of the passage larger than the corresponding radius of the first inner common circle; and

(c) the outer radial stops for the first and second sets of cam slots lie in a common circle having a radius from the axis of the passage larger than the radii of the first and second inner circles.

16. The apparatus claimed in Claim 15 including:

(a) means for moving a container body through the passage, the fingers being disposed for radial movement towards the axis of the passage at the exit thereof;

(b) a guide throat at the entrance to the passage to center a container body as the container body enters the passage on the moving means; and

(c) guide means between the guide throat and the exit of the passage to center the container asit passes through the'passage.

17. The apparatus claimed in Claim 16 including:

(a) means coupled to the moving means to actuate the cam plate rotation means and move the fingers to the expanded finger position and expand the mouth of a flexible bag over the open end of the container body when the open end of the container body is inside the expanded fingers;

(b) means to actuate the cam plate rotation means to move the fingers inwardly against the outer wall of the container body below its flange when the open end of the container body is inside the expanded fingers; and

(0) means to actuate the cam plate rotation means to move the fingers to the expanded finger position after the moving means has moved the open end of the container body sufficiently to strip the bag off the fingers and onto the outside of the body proximate its flange.

18. A method of attaching a flexible bag to a container body comprising:

(a) engaging the inner surface of the bag proximate its mouth with a plurality of fingers;

(b) expanding the mouth of the bag by outward radial movement of the fingers such that the engaged portion of the bag is slightly stretched;

(c) placing the top of the container body radially inward of the fingers in position to receive the bag; and then (d) disengaging the fingers from the bag such that the bag contracts around the outer surface adjacent the top of the container body with a tight fit.

19. The method claimed in Claim 18 including the step of contracting the fingers against the container body after the placing step.

20. The method claimed in Claim 19 including the additional step of inserting the bag into the container body after the top of the container body is placed inwardly of the fingers.

21. A method of attaching a flexible bag to a container body having an external flange at one end and a hollow interior comprising the steps of:

(b) expanding the fingers radially outward to slightly expand the mouth ofthe bag;

(c) passing the container body inwardly of the expanded fingers to a position where the flange slightly clears the fingers and the outer surface of the container body proximate the flange is disposed radially inward of the fingers;

(d) contracting the fingers against the outer surface of the container body proximate the flange to engage the bag with the flange; and

(e) disengaging the mouth of the bag from the fingers by movement of the container body relative to the fingers, the bag contracting against the outer surface of the container body upon such disengagement into direct tensioned contact therewith.

22. The method claimed in Claim 21 including the additional step of expanding the fingers radially outward after the disengaging step.

23. The method claimed in Claim 22 including the additional step of inserting the bag into the hollow interior of the container body after the top of the container body is placed inwardly of the fingers.

24. The method claimed in Claim 23 wherein the insertion step comprises applying a vacuum to the interior of the container body to draw the bag inside such interior.