US3913463A

US3913463A - Apparatus for opening tubes of flexible material

Info

Publication number: US3913463A
Application number: US485700A
Authority: US
Inventors: Clinton R Hollis
Original assignee: International Paper Co
Current assignee: International Paper Co
Priority date: 1972-06-29
Filing date: 1974-07-05
Publication date: 1975-10-21
Anticipated expiration: 1992-10-21

Abstract

A method and apparatus for spreading open the ends of bag tube blanks in a bag forming machine wherein a pair of opposing suction cups, one on each side of the path of movement of the blanks are moved in a circular path with respect to the machine frame. At the same time the suction cups are counter rotated at the same angular speed but in directions opposite to their movement in the circular path whereby the suction cup faces maintain constant their angular relationship with respect to the machine frame. The paths of movement of the cups are selected to provide concurrent tangential passage of the cups with the two walls of the bag blank and a suction pressure is applied to the cups when they are in contact with the blank. The blank is opened by action of the suction pressure as the cups move away from each other.

Description

United States Patent [191 [111 3,913,463 Hollis [451 Oct. 21, 1975 APPARATUS FOR OPENING TUBES OF Primary Examiner-1oseph H. McGlynn FLEXIBLE MATERIAL [75] Inventor: Clinton R. Hollis, Camden, Ark.

[73] Assignee: lnternationalPaper Company, New

York, NY,

[22] Filed: July 5, 1974 [21} Appl. No.: 485,700

Related US. Application Data [62] Division of Ser. No. 267,361, June 29, 1972, Pat.

[52] US. Cl 93/28; 53/386; 93/84 FF [5]] Int. Cl. B31B 1/80 [58] Field of Search 93/14, l5, 16, 22, 23, 93/24, 25, 28, 29, 30, 84 FF; 53/386; 226/47 [56] References Cited UNITED STATES PATENTS 3,446,121 5/1969 Achelpohl 93/28 3,545,346 12/1970 Achelpohl 93/28 3,547,010 12/1970 Gennerich et al. 93/28 X Assistant Examiner-James F. Coan Attorney, Agent, or Firm-R. S. Sanborn; W. T. Zielinski; W. A. Aguele [5 7] ABSTRACT A method and apparatus for spreading open the ends of bag tube blanks in a bag forming machine wherein a pair of opposing suction cups, one on each side of the path of movement of the blanks are moved in a circular path with respect to the machine frame. At the same time the suction cups are counter rotated at the same angular speed but in directions opposite to their movement in the circular path whereby the suction cup faces maintain constant their angular relationship with respect to the machine frame. The paths of movement of the cups are selected to provide concurrent tangential passage of the cups with the two walls of the bag blank and a suction pressure is applied to the cups when they are in contact with the blank. The blank is opened by action of the suction pressure as the cups move away from each other.

5 Claims, 4 Drawing Figures I VACUUM SOURCE US. Patent Oct. 21, 1975 Sheet 1 of 2 3,913,463

VACUU M 7 SOURCE VACUU SOURCE CAM OPERATED PNEUMATIC VALV E CAM PNEUMATIC.

VALVE OPERATED US. Patent Oct. 21, 1975 Sheet20f2 3,913,463.

This is a divisional of Ser. No. 267,361 filed June 29, 1972, now US. Pat. No. 3,834,287.

BACKGROUND OF THE INVENTION This invention pertains to a method and apparatus for spreading open the walls of an essentially flat tube of flexible material and more particularly relates to a method and apparatus for spreading open the walls of paper tube blanks in a bag forming machine.

There'are various known embodiments of bag forming machines for forming bags from tube stock of flexible material such as kraft paper. Usually, the bag blanks are separately made by a tubing machine which provides a continuous tube having a longitudinal seam prepared from sheet stock and cuts the tube to a series of blanks of predetermined length suitable forthe bag to be formed. These blanks are then processed through a bag forming machine for forming at least one sealed end.

The machine is adapted to process a large volume of bag blanks. Thus, the blanks are continuously fed irito the machine which includes means for transporting the bag blanks in series manner through several stations where the various operations for formingthe bag bottom are automatically performed. The blank is first scored lightly to provide the fold lines necessary for forming the bottom while the tube is in an essentially flat condition in one plane. The bottom end of the tube is then partially folded along a line transverse to the tube while the two walls of the ends still remain adjacent each other. These walls are then spread openand folded into the plane of the blank to provide exposed inner surfaces of the end portion. A suitable cement is then roller applied to the exposed surfaces and additional folding is performed to provide the necessary overlying layers of the tube end to form the bottom of 'the bag.

A typical prior art bag forming machineis described in greater detail in US. Pat. No. 2,707,421 to M. Rawe. As illustrated in FIG. of that patent the tube end is first partially opened by suction devices 3; the spreader finger 4 enters between the partially opened walls and opens them further; Then, the bow shaped forming members 5 enterthe partially opened tube end to fold the tube walls into the plane of the tubeblank.

{This type of tube end spreading mechanism is quite common in prior art bag forming machines. In some machines the spreader finger is omitted.

- 'A serious problem associated with such prior art spreading mechanisms is that the suction devices occasionally do not pre-open the tube ends sufficiently. In such instances, the spreader finger or the bow shaped forming members crush the end of the bag blank whereby a malformed bag is produce. Since the suction devices move around a circular path their faces are jointly parallel with the walls of the bag tube at only one point in their paths of motion. This is at their point of contact with the tube walls. Thus, as the suction devices approach the tube walls they form a distinct angle which decreases until contact is made and then they as sume a departing angular relationship as'they rotatev Also ,.,these dynamics operate as aconstraint on the usefulness of themachine since when bag sizes are made which depart from the optimum or nominal design size upon1 which the geometry of the spreading mechanism is predicated, the rejection rate if further increased. 1

Several attempts have been made to solve this problem among which is increasing the radius of the arc of movement of the suction devices so that they contact the tube end walls with a distinct interference or force against each other, to enhance the likelihood ofa'firm vacuum grasp. This results in premature wear of the forward corner of the vacuum cups having the adverse effect of increasing the down-time of the machine. Other attempts include reducing the size of the vacuum cup in an effort to alleviate the corner wear problem while increasing the vacuum pressure. It was found that this did not sufficiently increase the effectiveness of the vacuum devices to substantially reduce the objectionable rejection rate.

The invention as herein described solves the aforementioned problems by providing a far superior dynamic operation of the spreading mechanism wherein the suction cups approach each other while maintaining theirfaces in essentially contant angular relationship, perform their spreading function, and move away from each other with their faces in essentially .unchanged angular relationship. The invention has been found so effective that when making certain select sizes of bags from relatively heavy stock it is possible to omit one of the rotating suction devices and replace. it merely by a wall against which the bag tube end may rest while it. is partially opened by the remaining suction device.

SUMMARY One aspect of the present invention resides in a method of spreading open the walls of a tube of flexible material, including first and. second walls essentially facing each other wherein the tube is in motion in a predetermined direction, including the steps of; contacting the first wall of the tube with the suction face of a suction cup wherein the face-is essentially parallel to the walls of the tube, and moving the suction cup at least in part during the contacting stepin a direction having at least a vector component parallel to said predetermined direction of movement of the tube. The method includes the further steps of; applying a suction pressure to the suction cup at least inv part during the contacting step, and moving the suction cup in a direction away from the first wall while applying the suction pressure and while maintaining the suction cup face essentially parallel to the walls of the tube, thereby moving the first wall in a direction away from the second wall by action of the suction pressure.

In a preferred version of the method of the invention a pair of opposing suction cups are employed with the steps including; contacting thewalls of the tubewith the respective suction faces of the cups, one on each side of the tube, wherein the facesof the cups are essentiallyparallel, and moving the suction cups at least in part during'the contacting step in a direction of movement of the tube. This version of the methodincludes thefurther steps of; applying a suction pressure other while applying the suction pressure and while Yet another aspect of the invention resides in an apparatus-combination contemplated foruse in connectionwith a bag forming machine wherein the' machine includes a frame, means in the frame for folding the ends of the bag'tube blankto provide a plurality of overlying layers thereof while the" end of the tubeis in motion, means in the machine frame for moving the end of the tube into'the folding means in a determined direction to perform the folding, and mean's'operatively coupled with thefolding means for securing the overlying' layers to form the bag bottom. The preferred apparatus combination in accordance with the present invention is operatively coupled with the folding'means and is for openingthe end of the tubewhile the end is in motion in the aforementioned direction prior to completion of the folding thereof. This app'artus combinationincludes; a pair of suction cups, a first support member, means for rotating one of the suction cups at a' predetermined angular velocity about a first axis which is positioned inthe'first support member, and means for rotating'the support member at an angular velocity substantially equal to but opposite in direction to the predetermined angular velocity about an axis second which is positioned in the machine frame essentially parallel to the first axis and positioned to provide an essentially tangential passage of the suction face of the first cup with a first wall of thetube end in substantially the same direction as the predetermined direction of movement of the tube end.

The apparatus further includes; a second support member, means for rotating the second suction cup about an axis third which is positioned in the second support member, means for rotating the second support member in synchronism' with the first support member at an angular velocity substantially equal to 'but opposite indirection to the rotation of the second suction cup about the axis third, the rotation of the second support member being about an axis fourth which is positioned in the machine frame essentially parallel to the axis third and positioned to provide an essentially tangential passage of the suction face of the second cup with a second wall of the tube end in the vicinity of,

substantia'lly'in the same directionand concurrent with,

- themselves or with the tube end wallsthroughout their respective paths ofmotion. Thus, the suction cups can be initially se'tin parallel relationship ,with thetubewall path and they will maintain this relationship throughout their respective motions. This resultsvin greatly improved vacuum'contact with the tube walls. 4,

Furthermore, there is little .or no. transverse- -movement of the suction cups with respect-to .the tube walls while they are in contact therewith resulting insubstantially less wear of the cup faces.

v 'Kfurther advantage of the invent-ion resides in doing away with the necessity of employing the conventional rotating vacuum couplings associated with the prior art tube end spreading devices for providing a vacuum through the drive shafts of the vacuum cups.'Since the vacuum cups of .the .present invention do'not rotate with respect to the machine frame, a suction source can be directly coupled to the cups. This further increases the reliability ofthe machine. Another advantage of the invention is that bag tubes having minor inside sticking problems associated with the. longitudinal glued joint can beeffectively opened. Also, it can be understood that the invention results in a much wider pre-opening ofthe. bag tube than heretofore obtained.

In view of the foregoing it isan object of the present ,invention to'provideimproved methods and apparatus for spreading open thewalls of a tube of flexible material.

' It is another object of the invention to provide a method and apparatus of improved effectiveness for spreading open the walls of a tube of paper-like material in connection with bag making machines.

It is another object of "the invention to provide method and apparatus improvements which reduce the rejection rate of bags made by a bag making machine.

It is another object of the invention to provide an improved method and apparatus for the vacuum opening of the walls of a bag tube'blank enabling the use of vacuum cups of enlarged face area. I It'is yetanother object of the present invention to provide an improved method and apparatus for the vacuum opening of the walls of a bag tube blank in a bag making machine for reducing the wear of the vacuum cups and reducing the downtime of the machine. It is another object of the invention to providev iniproved apparatus for the vacuum opening of a bag tube enabling the use of a more simplified vacuum coupling system. v

It is yet a further object of the invention to provide an improved apparatus for the vacuum opening of a bag tube blank for use in a bag making machine extending the flexibility of usefulness of the machine.

These and other objects, advantagesand features of the invention, will be more fully understood by referring to the following descriptions and claims, taken in conjunction with the accompanying-drawings.

BRIEF DESCRIPTION or THE DRAWINGS FIG. 1 is a fragmentary, perspective view, partly in section, of a portion of the inlet end of a bag making I machine illustrating the prior art apparatus for opening the end of a bag tube.

FIG. 2 is a cross-sectional view taken in the direction 2 2 of FIG. 1 wherein the apparatus for opening the bag tube ends is replaced by improved apparatus illustrating features of the present invention.

FIG. 3 is an endview, partly in section, of FIG. 2 in the direction 3 3, illustratingin'greater detail the FIG.,,3 illustrating in still further detail the drive mecha- -nism for the tube suction cups.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, which partly illustrates the inlet protion of a bag making machine, essentially flat bag tube blanks 12 are sequentially introduced into the machine by conventional feeding apparatus not shown. It will be understood that as used herein the term essentially flat is intended to describe the relaxed shape assumed by a bag tube of generally flexible material such as kraft paper. Thus, the walls of the tube will tend to rest adjacent each other under the influence of gravity while the ends of the tube do not necessarily have a distinct longitudinal fold line. I

The tube blanks are transported through the bag making machine by suitable conveyor means such as endless belts 13, 14 which incorporate suitable grasping means for holding the tube blanks.

A stationary machine frame 15 is illustrated which includes a suitable bed upon which the endless belts l3, 14 move. A stationary g'uide bar 16 is provided positioned essentially transverse to the machine direction beneath which the end of the bag tubes are transported. Adjacent the bar 16 is a cam plate 17 having a gradually inclining curved surface which rises to a perpendicular relationship with the plane of travel of the bag tubes. Thus, as the bag tubes pass over the cam plate 17 the tube end is folded along a line transverse to the tube and essentially perpendicular to the plane of the tube. Therefore, an upstanding end 19, of the tube, is formed.

For brevity, the conventional scoring drums have been omitted from FIG. 1. These provide the several score lines required to define the various fold lines. for forming the overlying layers of the tube end to serve as the bag bottom. The scoring drums are generally positioned in the machine ahead of the cam plate 17 so that the scoring is performed prior. to folding the upstanding end 19.

The fold formed by the cam 17 is not exceptionally sharp so thata small radius is left at the fold line. Thus, the upstanding end 19 is of somewhat relaxed condition depending upon the weight of paper stock used and defines a plane of somewhat variable width parallel to the machine direction. The plane is somewhat thicker at the end of the tube than it is in the central region where the walls tend to rest adjacent each other.

Several further operations, not illustrated, are required to form the bag. The upstanding end is first spread open then flattened back into the plane of the tube leaving exposed the inner surfaces of the tube end. Then, adhesive is applied to the exposed inner surfaces and they are again folded to provide secured overlying layers. Appropriate apparatus for performing these functions is illustrated in the aforementioned patent US. Pat. No. 2,707,421.

As illustrated in FIG. 1, the prior art method of preopening the bag tube end employs a pair of suction cups rigidly rotated by a pair of driven shafts 21, 22 which are quidistantly disposed on either side of the path of passage of the upstanding tube end 19 and parallel therewith. For supporting the shafts 21, 22 the machine frame includes an overhead frame member 23 having downwardly depending

bearing bosses

24, 25. The

bosses include suitable bearings in which the shafts 21,

22 rotate. Also, the

bosses

24, 25 respectively include stationary arms 26, 27 which depend from the lower ends thereof. Mounted for rotation about horizontal axes in the arms 26, 27 are a pair of shafts which respectively include

bevel gears

28, 29. These respectively engage

bevel gears

30, 31 keyed to the shafts 21, 5 22. The shafts of the bevel gears 28, 29 have fixed to their respective ends bow-shaped forming

members

32, 33 for concurrent rotation thereof in essentially vertical planes. Non-rotatably connected to the lower ends of the shafts 21, 22 are a pair of opposing suction cups.

The shafts 21, 22 are driven in synchronism at equal angular speed and in equal opposite directions such that the scution cups associated therewith are opposite each other when a bag blank is present between the shafts 21, 22. Thus, the suction cups make a tangential 5 passage along the upstanding end 19 while both cups are moving in essentially the same direction as the tube end. The tangential passage can be arranged so that there is some interference i.e., the cups will concurrently apply some force on each other as the tube end is trapped between them. Or, the tangential passage can be adjusted to have some clearance so that suction cups are not subjected to any mechanical pressure as they jointly contact the bag tube.

A cam operated pneumatic valve 40 is schematically illustrated mechanically coupled with the drive means for driving the shafts 21, 22. A vacuum source 41 is connected with the valve 40. The shafts 21, 22 are hollow thereby providing a passageway communicating with the rotating suction cups. The upper ends of the shafts 21, 22 include appropriate rotating vacuum couplings, not shown, and a pneumatic tube connection, not shown, connected with the pneumatic valve 40 for receiving a vacuum pressure. The cam operated pneumatic valve is arranged to apply a vacuum to the shafts 21, 22 the moment the suction cups approach the tube end walls. The vacuum pressure is kept on for a short period of time as the suction cups pull away from each other partially opening the tube end. The vacuum is then immediately shut off to prevent tearing of the tube walls. This is required since the circular path of motion of the suction cup faces provides a velocity thereof which is in agreement with the velocity of the tube end only at the point of contact.

The bow-shaped forming

members

32, 33 are axially offset slightly so that the ends thereof are one behind the other in the machine direction. These ends immediately enter the partially opened tube end spreading it further to a fully opened condition into the plane of the tube exposing the inner surfaces thereof.

A major disadvantage of this prior art method and apparatus for opening the tube end arises from the fact that the faces of the suction cups are constantly changing their angular relationship whereby they are parallel with each other at only one point in their paths of motion, namely, the point of contact with the tube end. As a result, it has been necessary to adjust their respective radius arms of rotation such that their tangential passage is one involving interference, or mechanical pressure with each other and the tube end, in order to minimize the number of improperly formed bags. As indicated above this measure has not proved entirely satisfactory.

Referring now to FIG. 2 which is a cross-sectional view along the lines 2-2 of FIG. 1 wherein the tube end opening device is modified to include features of the present invention, the depending stationary boss 25 is lengthened in a downward direction and includes an opening 45 to accompany the bevel gear 29. A solid shaft 52 is used in place of the hollow shaft 22 and has suitably keyed to its upper end a driven gear-53. A suction cup 54 is shown in which is fitted a vacuum line 55.

Referring now jointly to FIG. 3 and 4, several axes of rotation are identified. A first axisof rotation is occupied by a shaft 56 to which is fixed the suction cup 54. The second axis of rotation is occupied by the shaft 52.

v The third axis of rotation is occupied by a shaft 57 the lower end of which is fixedto a suction cup 58. The

' fourth axis of rotation is occupied by a shaft 59 which mechanism. The same common drive is used to operate the cam, not shown, associated with the cam operated pneumatic valve 40.

The shaft 52 is rotateably mounted in the overhead frame 23 with

bearings

63, 64. The lower bearing 64 is directly fitted into a counterboard portion of the boss 25. The upper bearing 63, is fitted in a bearing retaining ring 65 which is, in turn, fitted into a mating counter bore in the overhead frame member.

A second counter bore is provided in the lower surface of the boss into which is snugly fitted the hub end of a gear 68. The counter bore is arranged concentric with the axis of the shaft .52 so that the pitch diameterof the gear 68 is generally concentric with the shaft 52. A set screw 69 is employed to secure the gear 68 in non-rotatable relationship with the boss 25. a support member 70 is clamped to the lower end of the shaft 52 with a clamping screw 71. A slot is provided in the wall of the support member 70 to obtain the de-' sired clamping action. An idler gear 73 is provided which is rotateably mounted to the support member for engagement with the stationary gear.68 .-The idler, in turn, is engaged with a gear 74 which is rotateably mounted in the support member 70. More specifically,

- the gear 74 is clamped to the shaft 56 with a gear clamp and screw 75. An extended hub portion of the gear 74 is provided over the end portion of which the gear clamp 75 is fitted. Also, this hub is fitted "in bearings 76,

v 77 which are, in turn, fitted in the support member 70 to'permit rotation of the shaft 56 with respect to the support member. The suction cup 54 is fixed to the lower end of the shaft'56.

- As the gear 53 is driven by the machine common drive mechanism it rotates the shaft 52 which carries with it the support member 70so that the first axis of rotation. occupied by the shaft .56-is caused to rotate about the shaft 52 in acircular path. As shown in FIG.

j 4, the direction of rotationof the-gear 53 and the suppoi-t member 70 illustrated clockwise. The idler gear 73 is caused to rotate by the stationary gear 68 as its pivotal axis is carried around the gear 68 by the support member 70. The idler 73, in tum, drives the gear 74 in I a counter clockwise direction, resulting in a counter clockwise movement of the shaft 56 with respect to its axis. The

gears

68 and 74 have the same number of ;teeth so that for each clockwise revolution of the support member 70 the shaft 56 makes counter clockwise revolution. Thus, the angular velocity of the shaft 56 about the axis of the shaft 52 is equal to but opposite in direction of the angular velocity of the suction cup 54'with respect to the shaft 56.

It is seen that the suction cup 54 moves in a circular path while maintaining constant the angular relationship of the plane of its face with respect to the machine frame.

The Suction cup 58 is driven by an identical but mirror image mechanism of that used for driving the-cup 54. The

gears

53, 60 and the center distances between the

shafts

52, 56 and 57, 59 are selected to provide a peripheral speed of the faces of the

cups

54, 58 approximately equal to the speed of movement of the tube end at the point of tangent intersection with the tube end. It can be understood that due to the improved performance of the suction cups wide tolerances of this speed are found acceptable.

Also, the

cups

54 and 58 are initially set up parallel with each other and with the path of movement of the tube ends by adjustments of the clamp and screw 75.

Likewise, reasonably wide tolerances of this angular relationship are acceptable since, once established, the angular relationship are acceptable since, once established, the angular relationships of the cups remain unchanged as they are moved through .their respective paths. I have found that an angular tolerance from parv allel of 10 to be quite acceptable.

The cam operated pneumatic valve 40 is preferably arranged to simultaneously apply a vacuum pressure to the suction cups approximately 5 of theirrespective rotation about the

shafts

52, 59 prior to being v opposite I It is preferred that the

shafts

52, 56, 57, and 59 be arranged generally perpendicular to the bed of the machine. so that the

cups

54, 58. move 'generally in the same direction as the tube ends at the point of their tangential passage. However, I have found that the present invention makes possible very wide variations from this preferred design. Indeed, acceptable performance is obtained if the movement of the suction cups merely has a vector component in the same direction as the tube end direction of movement when making the tangential passage. Also, wide tolerances of the nature of this tangential passage can be absorbed. It can be a passage of the cups in which only brushing contact is made with the tube walls or one which involves a substantial pressure between the two cups with the tube walls therebetween. Thus, as used herein; the term tangential passage is intended to embrace a family of arcs of movement of the cups which. come near the tube end walls or which intersect with them.

In a specific example the

gears

68 and 74 were selected having a pitch diameter of 2% inches. A pitch diameter of 1% inches was chosen for the idler gear 73 and it was positionedto provide a center distance, R between the

shafts

52 and 56 of 2% inches. The radius of movement of the face of the cup with respect to the shaft 56, R waschosen-as 2% inches. The cups were placed to provide approximately aline-to-line condition thereof without a'bag' tube present at'the nearest point of their tangential passage.

It can be seen by those skilled'in the art that the path of movement of the suction cup 54 with respect to the machine frame is a circle of radius R with'its axis displaced toward the bag tube end by a distance R from the axis of the shaft 52. Thus, the preferredangular speed of the gear 53 can be easily calculated to'provide a peripheral speed at a radius R approximately equal to the speed of the bag tube end. I

By employing the tube end opening device hereinabove described it became possible to substantially increase the speed of the bag forming machine while lowering to substantially zero the rate of malformed bags attributable to improper end opening.

While the invention has been described with a certain degree of particularity it can, nevertheless be seen, by the examples hereinabove set forth, that .many variations and modifications of the invention can be. made without departing from the true. spirit 'and scope thereof.

1 claim: 1 I

1. In combination with apparatus for forming a closed bottom of a bag from an'essentially flat'tube of flexible material including a machine frame, means in said frame for folding the endof said tube to provide a plurality of overlying layers thereof while said end is in motion, means in said frame for moving said end of said tube into said folding means in-apredetermined direction for said folding, and means operatively coupled with said folding means for securing said overlying layers to form said bag bottom, apparatus operatively coupled with said folding means for opening said end of said tube while said end is in motion in said direction prior to completion of said folding thereof, comprising:

a. a first suction cup; r

b. a support member;

0. means for rotating said suction cup at a predetermined angular velocity about a first axis which is positioned in said support member, said means including a single pivotal connection means on said suction cup for rotatable connection thereof with said support member and for defining said first axis;

d. means for rotating said support member at an angular velocity substantially equal to but opposite in direction to said angular velocity provided by said means (c) about a second axis, said second axis being positioned to provide a first essentially tangential passage of the suction face of cup with a first wall of said tube end in substantially the same direction as said predetermined direction of movement of said tube end; and

e. means for applying a suction pressure to said suction cup at least in part during said tangential passage of said suction cup face with said first wall.

2. The appartus of claim 1 further comprising:

f. a second suction cup;

g. a second support member;

h. means for rotating said second suction cup at a predetermined angular velocity about a third axis, said third axis being positioned in said second support member, said means (h) including a single pivotal connection means on said second suction cup for rotatable connection thereof to said second support member and for defining said third axis;

synchronism with said means (d) at an angular velocity substantially equal to but opposite in direction to said angular velocity provided by said and concurrent with said first tangential passage of I said first cup; and j. means for applying a suction pressure tos aid second suction cup at least in part during said second tangential passage of said second cup face with said 'second wall.

31in combination with apparatus for' forming a closed bottom of a bag from an essentially flat tube of flexible material including a machine frame, means in said frame for folding the endof said tube to provide a plurality of overlying layers thereof while said tube end is in motion, means in said frame for moving said. tube end into said folding means with a predetermined 1 velocity for said folding, and means operatively coupled with said folding means for securing-said overlying layers to form said bag bottom, apparatus operatively coupled with said folding means for opening said tube end while it isin motion at said velocity prior to completion of said, folding thereof, comprising:

a. a first support member; 1 b. a second support member; p V g c. first and second opposing suction cups, one on each side of the path of movement of said end of said tube in said frame, said first suction cup having a single pivotalconnection means thereon defining a first axis of rotation for rotatable mounting of said first suction cup to said-first support member; (1. means for rotating said first suction cup about said first axis in a first angular direction at a first angular speed;

e. mounting means for rotatably mounting said first support member to said frame for rotation thereof 1 about a second axis essentially parallel to said first axis, wherein said mounting means is positioned in said frame to provide a first tangential passage of the face of said first suction cup with a first wall of said tube end in a' direction substantially aligned with the direction of movement of said tube end; f. means for rotating said first support member about said second axis at an angular speed essentially equal to said first angular speed and in an angular direction essentially opposite to said first angular Y direction; r i g. a single pivotal connection means on said second suction cup for rotatable connection thereof to said second support member, said single pivotal connection means defining a thirdaxis of rotation;

h. means for rotating said second suction cup about said third axis at an angular speed substantially equal to said first angular speed and in an angular direction essentially opposite to said first angular diection;

i. mounting means for rotatably mounting said second support member to said frame for rotation thereof about a fourth axis essentially parallel to said third axis wherein said mounting means (i) is positioned in said frame to provide an essentially means for rotating said second support member in Y tangential passage of the face of said second cup with the wallof said tube end oppositesaid first wall but in the vicinity of said first tangential passage and in a direction substantially aligned with the direction of movement of said tube end; and

- j. means for rotating, in synchronism with the rotation of said first support member, said second support member about said fourth axis at an angular speed essentially'equal to said first angular speed and in an angular directionessentially the same as said first angular direction.

4. In combination with apparatus for forming a closed bottom of a bag froman essentially flat tube of flexible material including a machine frame, means in said frame for folding the end of said tube to provide a plurality of overlying layers thereof while said end is in motion, means in said frame for moving said end of said tube into said folding means in a predetermined direction for said folding, and means operatively coupled with said folding means for securing said overlying layers to form said bag bottom, apparatus operatively coupled with said folding means for opening said end of said tube while said end is in motion in said direction prior to completion of said folding therof, comprising:

a. a suction cup;

b. a support member;

c. a toothed driven member fixed to said suction cup and rotatably mounted to said support member for defining a first axis of rotation of said suction cup with respect to said support member;

(1. means for rotating said support member about a second axis, saidsecond axis being positioned in said machine frame substantially parallel to said first axis and positioned in said machine frame to provide a first essentially tangential passage of the suction face of said cup with a first wall of said tube end in substantially the same direction as said predetermined direction of movement of said tube end;

e. a toothed driving member fixed to said machine frame in a position circumscribing said second axis;

f. engagement means for engaging said driven member (c) with said driving member (e) to rotate said suction cup about said first axis in a direction opposite to the direction of rotation of said support member; and

g. means for applying a suction pressure to said suc tion cup at least in part during said tangential passage of said suction cup face with said first wall.

'5. The apparatus of claim 4 further comprising:

h. a secondv suction cup;

i. a second support member;

j. a second toothed driven member fixed to said second suction cup and rotatably mounted to said second support member for defining a third axis of rotation;

k. means for rotating said second support member about a fourth axis, said fourth axis being positioned in said machine frame essentially parallel to said third axis and positioned in said machine frame to provide an essentially tangential passage vof the suction face of said second cup with a second wall of said tube end in the vicinity of, substantially in the same direction and concurrent with said first tangential passage of said first cup;

. a second toothed driving member fixed to said machine frame in a position circumscribing said fourth axis;

m. engagement means for engaging said driven member (j) with. said driving member (1.) to rotate said second suction cup about said third axis in a direction opposite to the direction of rotation of said second wall.

Claims

1. In combination with apparatus for forming a closed bottom of a bag from an essentially flat tube of flexible material including a machine frame, means in said frame for folding the end of said tube to provide a plurality of overlying layers thereof while said end is in motion, means in said frame for moving said end of said tube into said folding means in a predetermined direction for said folding, and means operatively coupled with said folding means for securing said overlying layers to form said bag bottom, apparatus operatively coupled with said folding means for opening said end of said tube while said end is in motion in said direction prior to completion of said folding thereof, comprising: a. a first suction cup; b. a support member; c. means for rotating said suction cup at a predetermined angular velocity about a first axis which is positioned in said support member, said means including a single pivotal connection means on said suction cup for rotatable connection thereof with said support member and for defining said first axis; d. means for rotating said support member at an angular velocity substantially equal to but opposite in direction to said angular velocity provided by said means (c) about a second axis, said second axis being positioned to provide a first essentially tangential passage of the suction face of cup with a first wall of said tube end in substantially the same direction as said predetermined direction of movement of said tube end; and e. means for applying a suction pressure to said suction cup at least in part during said tangential passage of said suction cup face with said first wall.

2. The appartus of claim 1 further comprising: f. a second suction cup; g. a second support member; h. means for rotating said second suction cup at a predetermined angular velocity about a third axis, said third axis being positioned in said second support member, said means (h) including a single pivotal connection means on said second suctiOn cup for rotatable connection thereof to said second support member and for defining said third axis; i. means for rotating said second support member in synchronism with said means (d) at an angular velocity substantially equal to but opposite in direction to said angular velocity provided by said means (h), about a fourth axis, said fourth axis being positioned in said frame essentially parallel to said third axis and positioned to provide an essentially tangential passage of the suction face of said second cup with a second wall of said tube end in the vicinity of, substantially in the same direction and concurrent with said first tangential passage of said first cup; and j. means for applying a suction pressure to said second suction cup at least in part during said second tangential passage of said second cup face with said second wall.

3. In combination with apparatus for forming a closed bottom of a bag from an essentially flat tube of flexible material including a machine frame, means in said frame for folding the end of said tube to provide a plurality of overlying layers thereof while said tube end is in motion, means in said frame for moving said tube end into said folding means with a predetermined velocity for said folding, and means operatively coupled with said folding means for securing said overlying layers to form said bag bottom, apparatus operatively coupled with said folding means for opening said tube end while it is in motion at said velocity prior to completion of said folding thereof, comprising: a. a first support member; b. a second support member; c. first and second opposing suction cups, one on each side of the path of movement of said end of said tube in said frame, said first suction cup having a single pivotal connection means thereon defining a first axis of rotation for rotatable mounting of said first suction cup to said first support member; d. means for rotating said first suction cup about said first axis in a first angular direction at a first angular speed; e. mounting means for rotatably mounting said first support member to said frame for rotation thereof about a second axis essentially parallel to said first axis, wherein said mounting means is positioned in said frame to provide a first tangential passage of the face of said first suction cup with a first wall of said tube end in a direction substantially aligned with the direction of movement of said tube end; f. means for rotating said first support member about said second axis at an angular speed essentially equal to said first angular speed and in an angular direction essentially opposite to said first angular direction; g. a single pivotal connection means on said second suction cup for rotatable connection thereof to said second support member, said single pivotal connection means defining a third axis of rotation; h. means for rotating said second suction cup about said third axis at an angular speed substantially equal to said first angular speed and in an angular direction essentially opposite to said first angular diection; i. mounting means for rotatably mounting said second support member to said frame for rotation thereof about a fourth axis essentially parallel to said third axis wherein said mounting means (i) is positioned in said frame to provide an essentially tangential passage of the face of said second cup with the wall of said tube end opposite said first wall but in the vicinity of said first tangential passage and in a direction substantially aligned with the direction of movement of said tube end; and j. means for rotating, in synchronism with the rotation of said first support member, said second support member about said fourth axis at an angular speed essentially equal to said first angular speed and in an angular direction essentially the same as said first angular direction.

4. In combination with apparatus for forming a closed bottom of a bag from an essentially flat tube of flexiblE material including a machine frame, means in said frame for folding the end of said tube to provide a plurality of overlying layers thereof while said end is in motion, means in said frame for moving said end of said tube into said folding means in a predetermined direction for said folding, and means operatively coupled with said folding means for securing said overlying layers to form said bag bottom, apparatus operatively coupled with said folding means for opening said end of said tube while said end is in motion in said direction prior to completion of said folding therof, comprising: a. a suction cup; b. a support member; c. a toothed driven member fixed to said suction cup and rotatably mounted to said support member for defining a first axis of rotation of said suction cup with respect to said support member; d. means for rotating said support member about a second axis, said second axis being positioned in said machine frame substantially parallel to said first axis and positioned in said machine frame to provide a first essentially tangential passage of the suction face of said cup with a first wall of said tube end in substantially the same direction as said predetermined direction of movement of said tube end; e. a toothed driving member fixed to said machine frame in a position circumscribing said second axis; f. engagement means for engaging said driven member (c) with said driving member (e) to rotate said suction cup about said first axis in a direction opposite to the direction of rotation of said support member; and g. means for applying a suction pressure to said suction cup at least in part during said tangential passage of said suction cup face with said first wall.

5. The apparatus of claim 4 further comprising: h. a second suction cup; i. a second support member; j. a second toothed driven member fixed to said second suction cup and rotatably mounted to said second support member for defining a third axis of rotation; k. means for rotating said second support member about a fourth axis, said fourth axis being positioned in said machine frame essentially parallel to said third axis and positioned in said machine frame to provide an essentially tangential passage of the suction face of said second cup with a second wall of said tube end in the vicinity of, substantially in the same direction and concurrent with said first tangential passage of said first cup; l. a second toothed driving member fixed to said machine frame in a position circumscribing said fourth axis; m. engagement means for engaging said driven member (j) with said driving member (l) to rotate said second suction cup about said third axis in a direction opposite to the direction of rotation of said second support member; and n. means for applying a suction pressure to said second suction cup at least in part during said second tangential passage of said second cup face with said second wall.