US3150477A

US3150477A - Bag closing machine

Info

Publication number: US3150477A
Application number: US105059A
Authority: US
Inventors: William A Keene
Original assignee: Phillips Petroleum Co
Current assignee: Phillips Petroleum Co
Priority date: 1961-04-24
Filing date: 1961-04-24
Publication date: 1964-09-29
Anticipated expiration: 1981-09-29

Description

P 1964 w. A. KEENE 3,150,477

BAG CLOSING MACHINE Filed April 24. 1961 5 Sheets-Sheet 1 FIG.

INVENTOR. W. A. KEENE A T TORNEVS p 1964 w. A. KEENE 3,150,477

BAG CLOSING MACHINE Filed April 24, 1951 5 Sheets- Sheet 3 Inn 62 IIIIII 63 1 mmmnmnmmnal D FIG. 30

STATION l INVENTOR.

W. A. KEENE A TTORNEVS p 1954 w. A. KEENE 3,150,477

BAG CLOSING MACHINE Filed April 24. 1961 5 Sheets-Sheet 4 STATION 3 g6 22 STATION 1 O 0 B O Q 0 O O O 0 O O O 0 D O INVENTOR. W. A. KEENE A T TORNE Y5 P 1964 w. A. KEENE 3,150,477

BAG CLOSING MACHINE Filed April 24, 1961 5 Sheets-Sheet 5 HOV I00 Am 7 r 2 I07 (I06 98 l 108 I03 98 f TIMER E 5, y I05 TIMERv 80 lOl IOI' 93 yo TIMER 94 FIG.

57 FIG. .9

INVENTOR.

W. A KEENE FIG. /0 /W w yak A T TORNEYS United States Patent 3,150,477 BAG CLOSING MAIJIIDJE William A. Keene, Eartlesville, Okla, assignor to Phillips Petroleum Company, a corporation of Delaware Filed Apr. 24, 1961, Ser. No. 105,059 13 Claims. (Cl. 53--370) This invention relates to a bag closing machine and method. In one aspect this invention relates to a machine for closing open mouth bags. In another aspect this invention relates to a method for closing open mouth bags.

Many products such as carbon black, fertilizer, cement, lime, grain feeds, and other granular or powdery materials are packaged in paper bags for delivery to the ultimate consumer. Generally speaking, three types of bags are in use, the valve bag, the pasted open mouth bag, and the sewn open mouth bag. For many products a pasted closure for the open mouth bag is not practical. The valve bag is more costly. So far as is presently known, no automatic bag filling machines are available for filling valve type bags. Furthermore, the machines presently available for filling valve type bags do not weigh as accurately as do machines or apparatus for filling open mouth bags. For these reasons the open mouth bag is most widely used and recently several companies have developed automatic bagging equipment for open mouth bags which includes automatic sewing equipment to close the open mouth of the bag by sewing. However, in many instances the automatic sewing equipment has proved troublesome and impractical resulting in excessive maintenance costs. Furthermore, a sewed bag has a tapered end which has a poor appearance and poor warehousing qualities.

An object of this invention is to provide an improved bag closing machine for closing open mouth bags. Another objeot of this invention is to provide an improved method for closing open mouth bags. Another object of this invention is to provide a method and a machine for closing open mouth bags, which method eliminates closing said bag by sewing. Another object of this invention is to provide a method and machine for closing open mouth bags which eliminates closing said bag by pasting. Still another object of this invention is to provide a bag closing method and machine for closing open mouth bags which may be entirely automatic in operation, if desired, so that a filled bag can be delivered to the machine from a bag filling machine and all of the operations for completing the closing of the bag will be entirely automatic. Still another object of this invention is to provide a method and machine for closing open mouth bags as heretofore characterized which can be operated at high speed, so that closing of the bag can be effected as rapidly as the filling of the bag, with the result that a single machine for closing bags may handle all of the filled bags delivered by an automatic bag filling machine. Still another object of this invention is to provide, when starting with an open mouth bag, a closed, filled bag which is relatively flat on both the bottom and top and thus possesses a boxlike shape which is more desirable, both for appearance and for handling and stacking purposes. Other aspects, objects, and advantages of the invention will be apparent to those skilled in the art in view of this disclosure.

In the practice of the invention, there is provided a bag closing machine which, in a presently preferred embodiment, broadly comprises a rotary turntable unit provided with four bag receiving pockets on four different sides thereof. Said rotary turntable unit is rotated through four consecutive stations at which various operations of the method of the invention are carried out. Thus, a filled bag is moved in vertical position to a pocket of said machine occupying a first station. As said bag is moved into said pocket, the lips of the bag are introduced between a pair of open fingers extending horizontally above said pocket. The bag upon entry into said pocket actuates the machine and simultaneously, the pocket containing said bag is moved from said first station to a second station, said fingers are closed to engage the lips of said bag and rotated so as to roll said lips around said fingers downwardly onto the body of the filled bag, and said filled bag is elevated an amount sufficient to compensate for said downward rolling of said lips. All of said operations occur simultaneously with the movement of the pocket containing said bag from said first station to said second station. While at said second station, at least one piece of pressure sensitive adhesive tape is applied across the rolled down lips of the bag. The pocket containing said bag is then moved to a third station at which the bag is removed from said fingers and the machine onto a conveyor for transport to storage or other handling.

FIGURE 1 is a perspective view of a bag closing machine in accordance with the invention and illustrating filled bags in three pockets of the machine stationed at stations I, 2, and 3. Said FIGURE 1 also illustrates the relation between the bag closing machine and other bag filling and handling apparatus.

FIGURE 2 is a plan view of the bag closing machine of FIGURE 1 without the filled bags in the pockets at the various stations.

FIGURE 3 is a view in elevation of the lower portion of the bag closing machine of FIGURE 1 when looking at station I of said machine.

FIGURE 3:: is a view in elevation of the top portion of the bag closing machine of FIGURE 1 when looking at station I thereof and is fragmentary or diagrammatic in that the drawing has been simplified by omitting the finger mechanism which normally would be shown as extending over the pockets at

stations

2 and 4 as shown in FIGURES 1 and 2. Otherwise, the view in FIGURE 3a corresponds to the upper portion of the machine as viewed in FIG- URE 3.

FIGURE 4 is a sectional view taken substantially along the line 44 of FIGURE 2.

FIGURE 4a is a view in elevation of the top portion of the machine of FIGURE 1 when looking at station 2 and is fragmentary or diagrammatic in that the drawing has been simplified by omitting the finger mechanism which would normally be shown as extending over the pockets at

stations

2 and 3 as shown in FIGURES l and 2. Otherwise, the view in FIGURE 4a corresponds to the upper portion of the machine as viewed in FIGURE 4.

FIGURE 5 is a detail view, partly in section, taken along the line 5-5 of FIGURE 4 and illustrates a portion of the mechanism for rotating the frame of the machine.

FIGURE 6 is a detail view, partly in section, illustrating details of the means for rotating and closing and opening the fingers which engage the open lips of the filled bag as illustrated in FIGURE 1.

FIGURE 7 is a detail view, partly in section, taken along the line 77 of FIGURE 2 and illustrates other details of the means for rotating the fingers which engage the lips of the open bag as illustrated in FIGURE 1.

FIGURE 8 is a detail view taken along the line 8-8 of FIGURE 2 and illustrates still other details of the means for rotating and closing and opening the fingers which engage the lips of the open bag as illustrated in FIGURE 1.

FIGURE 9 and 10 are detail plan views illustrating still other details of the means for rotating and closing and opening the fingers which engage the lips of the open bag as illustrated in FIGURE 1.

FIGURE 11 illustrates one suitable wiring diagram which can be employed in controlling the operation of the bag closing machine of the invention.

Referring now to the drawings, wherein like reference numerals are employed to denote like elements in the various drawings, the invention will be more fully explained. In the embodiment illustrated in said drawings the bag closing machine of the invention comprises a base which can be fabricated from any suitable type of structural materials such as the channel beams illustrated. A vertical support column 11 is centrally disposed with respect to and is attached at its lower end to said base. A first hub 12 is rotatably mounted around the upper portion of said column. A second hub 13 is rotatably mounted around the lower portion of said column.

A frame surrounds said column 11 and is comprised of a first ring-like member 14 in the shape of an octagon surrounding said column 11 at the level of and attached to said first hub 12 by means of a plurality of supporting spokes 16. A second ring-like member 17 in the shape of an octagon surrounds said column 11 at the level of and is attached to said second hub 13 by means of a second plurality of supporting spokes 18. Although not essential, said ring-

like members

14 and 17 are substantially the same diameter. A first, a second, a third, and a fourth pair of spaced apart wall members 19-19, 2121', 22-22, and 23-23, respectively, extend horizontally from four diiferent sides of said second ring-like member 17 to form respectively a first, a second, a third, and a fourth bag receiving pocket. In the machine here illustrated said pockets are spaced equidistantly, i.e., 90, from each other with respect to the center lines thereof. As explained further hereinafter, each of said pockets consecutively occupies a first, a second, a third, and a fourth station during rotation of said frame. Separate connecting

members

24, 26, 27, and 28, respectively, connect adjacent sides of said first and second pockets, adjacent sides of said second and third pockets, adjacent sides of said third and fourth pockets, and adjacent sides of said fourth and first pockets.

Separate brace members

29, 31, 32, and 33 extend between and connect said first ring-like member 14 to said connecting

members

24, 26, 27, and 28, respectively.

A bag conveyor assembly is mounted in and forms the bottom of each of said bag receiving pockets. Each of said bag conveyor assemblies comprises a plurality of conveyor rolls 34 rotatably mounted between a pair of mounting brackets 36. Each of said mounting brackets is provided with a tongue 37 extending from the wall of a recess formed at about the midpoint of the bracket. Said tongue 37 co-operates with a grooved boss 38 formed on the inner wall of each of said wall members, for example 19 and 19. Each of said bag conveyor assemblies is thus slidably mounted for limited vertical movement between the wall members of one of said pockets. A circular track 35 is mounted on said base 10 by means of the adjustable bolts shown. It will be noted that said track has a lower elevation at said first station than at said second, third, and fourth stations. A wheel 40, or other suitable supporting means such as a slide, is mounted in a bracket 45 attached to the bottom of said mounting brackets 36 on each of said bag conveyor assemblies and supports each of said bag conveyor assemblies on said track 35.

The bag closing machine illustrated in the drawings is provided with four bag engaging and closing means, one each of which is positioned above and extends horizontally over each of said bag receiving pockets. Each of said bag engaging and closing means comprises a main shaft 38 rotatably mounted in bearings 39 on said frame (support members 16) above said first hub 12 with the inboard end of said main shaft adjacent said support column 11. A collar 41 is fixed to said inboard end of said main shaft 38. Said collar 41 is provided with a first flat cam surface 42 and a second fiat cam surface 43 (see FIGURE 8) on adjacent sides thereof. A sprocket wheel 44 is fixed on said main shaft 38 adjacent the outboard end thereof. First and second spaced apart parallel finger shafts 46 and 47 (see FIGURES 6, 7, and 8) are rotatably mounted Within said main shaft and extend beyond both the inboard and outboard ends thereof. First and second spaced apart parallel polished fingers 48 and 49 (see FIGURE 2) are attached respectively to the outboard ends of said first and

second finger shafts

46 and 47. A pair of said

fingers

48 and 49 extends above each one of said pockets and is adapted, as explained further hereinafter, to receive the lips of a filled open mouth bag when said bag is moved into the one of said bag receiving pockets which is occupying station 1.

Referring now to FIGURES 6 and 8, a first spur gear 51 is mounted on said first finger shaft 46 at the inboard end thereof. A second spur gear 52 is mounted on said second finger shaft 47 at the inboard end thereof and is adapted to engage said first spur gear. A cam lug 53 is fixed to the inboard side of said first spur gear 51. A torsion spring 54 is mounted around said second finger shaft 47, fixed to said spur gear 52 and said collar 41, and is normally biased to cause said spur gears to rotate said

finger shafts

46 and 47 in a direction to cause said

fingers

48 and 49 to be in the closed engaging position as shown in FIGURE 1.

A first slide plate 56 (see FIGURES 2, 4, and 10) is fixed around the periphery of said column 11 above said first hub 12. Said slide plate 56 is provided with a first extension 57 thereon which extends outwardly between station 4 and station 1 and is positioned adjacent said station 1 so as to engage said first cam surface 42 on said collar 41 just prior to arrival of main shaft 38 in a position above station 1 when said frame is being rotated and thus prevent rotation of said main shaft 38 prior to and while it is at said station 1. Said slide plate 56 is also provided with a second extension 58 thereon which extends substantially between station 2 and station 4 and is adapted to engage said second fiat cam surface 43 on collar 41 during rotation of the frame around said column 11 and prevent rotation of said main shaft 38 while it is traveling between station 2 and station 4. A second slide plate 59 (see FIGURES 4a and 9) is fixed around the periphery of said column 11 between said first slide plate 56 and said first hub 12. Said second slide plate 59 is provided with an actuating lug 61 which extends therefrom between station 4 and station 1 and is positioned so as to engage said cam lug 53 which is fixed to said spur gear 51, cause said spur gears 51 and 52 to rotate, and open said

fingers

48 and 49 just prior to their arrival in a position above said station 1.

A circular drive plate 62 is fixed on said column 11 above said first slide plate 56. A first segment of rack gears 63 (see FIGURES 2, 3a and 4a) is mounted on the under side of said drive plate 62 adjacent the periphery thereof between said first and second stations for coacting with said sprocket wheel 44 to rotate said main shaft 38 and said

fingers

48 and 49 and thus roll the lips of said bag around said fingers as said frame is rotated from said firststation to said second station as described further heremafter. A second segment of rack gears 64 is mounted on the under side of said drive plate 62 adjacent the periphery thereof between said fourth and said first stations, and is spaced apart from said first segment of rack gears, for coacting with said sprocket wheel to rotate said main shaft 38 and said finger shafts 46 and 4'7 sufficient to place said

fingers

48 and 49 in an open receiving position just prior to their arrival at station I. Said rack gears 63 and 64 can be any type of gear suitable for engaging the teeth of sprocket 44. One convenient type of gear arrangement is a series of individual links of bicycle type" chain welded to drive plate 62. The size and spacing between the links will depend upon the size of sprocket 44.

Referring now to FIGURES 4 and 5, an indexing ring 66 is secured to and surrounds the lower portion of said second hub 13. In the embodiment of the invention here shown, said indexing ring 66 is provided with four indexing recesses 67 spaced equally apart around the outer circumference thereof. A shoulder 68 extends from one side of a slip ring 65 surrounding but not fixed to said second hub 13 below said indexing ring 66. A pawl 69, biased by means of spring 71 to normally engage one side only of said recesses so as to move said ring 66 in one direction only, is pivotally mounted on said shoulder 68. A first cylinder 72 is mounted on said base below said frame and adjacent said shoulder 68. A double acting fluid operated piston 73 is disposed within said cylinder 72. A piston rod 74 is connected at one end within said cylinder to said piston 73 and at its other end to said shoulder 68 on said indexing ring 66.

Fluid conduit

76 and 77, connected to air manifold 78 through solenoid actuated four-way valve 79, are provided for delivering actuating air to and from cylinder 72 for actuating said piston 73 so as to rotate said frame by the action of pawl 69 on one side of recesses 67. A double acting brake member 81 is provided for engaging both sides of recesses 67 in indexing ring 66 so as to prevent rotation of the frame in either direction except when desired. Said brake member is actuated by a double acting piston (not shown) in cylinder 82 suitably mounted on said base 10. Said cylinder 82 is supplied with actuating air from manifold 78 via solenoid actuated valve 83 and conduit 84 simultaneously with the supplying of air to said first cylinder 72. Thus, when air is supplied to said cylinder 72, air is also supplied to cylinder 82 so as to move brake member 81 out of engagement with recesses 67 and permit rotation of ring 66. Said air manifold 78 is connected to a source of compressed air, not shown. Solenoid actuated

valves

79, 83 and 94 have been shown schematically in FIGURE 4 in order to simplify the drawings. In actual construction said valves are mounted at suitable positions on base 10. The relationship between said valves and their actuating solenoids and the electrical system of the machine is shown in FIGURE 11.

A second cylinder 86 is mounted on said column 11 above said first hub 13 by means of rings 88 attached to said column and mounting plate 87 attached to said rings. A double acting fluid operating piston (not shown) is disposed within said cylinder 86. A piston rod 89 is connected at one end within said cylinder 86 to said piston and at its other end to a vertically disposed push-01f plate 91. Actuating fluid is conducted to and from said cylinder 86 by means of

conduits

92 and 93 which are connected to fluid manifold 78 via solenoid actuated fourway valve 94. The actuating fluid used in

cylinders

72 and 86 is preferably air as indicated in FIGURE 4 or can be a hydraulic fluid by making suitable modifications to the fluid supply system.

An actuating lever 96 comprising an upper and a lower horizontal bar connected by means of a vertical rod is pivotally mounted in one of the wall members of each of the bag receiving pockets. In the embodiment of the invention illustrated, the vertical rod portion of said actuating lever is mounted in the right-hand wall member, for example,

wall members

19, 21, 22, and 23. Said actuating lever 96 is mounted so that the upper horizontal bar thereof normally extends over the top of the bag receiving pocket and the lower horizontal bar extends below said bag receiving pocket and said frame. Said actuating lever 96 is normally biased in the position described by means of spring 97 attached to said lower horizontal bar and mounted as shown.

Switches

98, 99, and 101 are mounted on said base 10 at

stations

1, 2, and 3, respectively, in a position such that the lower horizontal bar of actuating lever 96 will strike the actuating bar of said switches as the frame is rotated.

Referring now to FIGURE 11, there is illustrated one suitable wiring and switch arrangement which can be employed to control the operation of the bag closing machine of the invention. When said machine is in operation, main switch is closed. When a filled bag enters the bag receiving pocket occupying station 1, the bag strikes the upper horizontal bar of actuating lever 96 which causes the lower horizontal bar of said actuating lever 96 to strike the actuating bar of switch 98. Said switch 98 is a commercially available switch of a type commonly referred to as micro switches and normally makes contact only momentarily. Said momentary closing of switch 98 completes a circuit from main lead wire 102 through said switch 98, lead wire 103, lead wire 104, and lead wire 105 into timer 106.

Said timer 106 is a commercially available mechanism comprising a relay, an electric motor, and a cam. One side of the winding of said motor is connected into main lead wire 102 by lead wire 107. Said lead wire 105 is connected to the relay in timer 106. Said relay is connected to the other main lead wire 109 by means of lead wire 108. Upon actuation of said relay by the closing of switch 98 the motor in timer 106 is started and the cam, being connected to said motor, is rotated. Said relay keeps the circuit through lead wire 108 closed during revolution of the cam. At the end of one revolution of said cam a notch on the surface of the cam causes the relay to break the circuit through the lead wire 108 and the motor stops. During the time the motor is running a circuit is also completed from main lead wire 102 through lead wire 110, lead wire 111, said relay, lead wire 112, sholenoid 79', and lead wire 113 to the other main lead Wire 109 Said last-mentioned circuit actuates said solenoid 79' which switches four-way valve 79 to admit air from air header 78 and conduit 78' to conduit 76 which is connected to cylinder 72 (see FIGURE 4) of the rotating mechanism. At this time conduit 77, also connected to said cylinder 72, is connected to exhaust through said four-way valve 79. The admission of air through conduit 76 to cylinder 72 causes piston 73 to move in a direction to eifect one stage of rotation, i.e., 90, of the frame of the bag closing machine. When the motor in timer 106 stops, the circuit through solenoid 79' is broken and de-energization of said solenoid causes four-way valve 79 to switch to a position to admit air to cylinder 72 via conduit 77. Upon said switching of valve 79, conduit 76 is, of course, placed in exhaust position. This reverses the action of piston 73 and places the rotating mechanism in position for the next stage of rotation.

Said timer 106 can be any commercially available mechanism suitable for use in the practice of the invention. The type described generally above is a series RA-O timer fitted with a gear rack A-l8, available from the Industrial Timer Corporation, Newark, New Jersey. Four-way valve 79 is a conventional valve. As will be understood by those skilled in the art, conduit '78 is connected to the body of the valve and when the valve is switched said conduit 78 is placed in communication with first one and then the other of the lower ports shown so as to admit air to one or the other of conduits 76 or conduit 77. The one of said lower ports which said conduit 78' is not in communication with serves as an exhaust port for the one of said

conduits

76 and 77 which is not being employed to pass air to cylinder 72. When solenoid 79' is not energized, valve 79 is normally biased to place condiut 76 in exhaust position.

Simultaneous with the completion of the circuit through timer 106 as described above, another circuit is completed through solenoid 83 by means of

lead wires

114 and 115. Thus, the closing of switch 98 will actuate said solenoid 83' and switch four-way valve 83 to admit air from air header 78 through said valve 83 to conduit 84 which is connected to cylinder 82. This will actuate the piston in said cylinder 82 causing it to effect the withdrawal of brake member 81 (see FIGURES 4 and 5) from contact with recesses 67 in indexing ring 66. Although the actuation of solenoid 83' is of short duration, it is of sufficient time to withdraw brake member 81 from ring 66 because it is only necessary that said brake member be withdrawn long enough to initiate rotation of indexing ring 66. When once withdrawn, and ring 66 is moved, said brake member will ride on the surface between said recesses 67 until it again indexes with one of said recesses to again be effective as a brake. When solenoid S3 is not energized, the valve 83 connected thereto is normally biased to switch conduit 84 to an exhaust position through the port of said valve which is not in communication with air header 78. At the same time, conduit 85 is placed in communication with air header 78 and the piston in cylinder 82 is actuated in a direction to move brake member 81 toward indexing ring 66. Valve 83 is a conventional four-way valve.

During rotation of the frame of the bag closing machine, as each bag receiving pocket containing a filled bag arrives at station 2 the lower horizontal bar of actuating lever 96 will strike the actuating bar of switch 9%. If it is desired to apply the pressure sensitive tape to the top of the closed bag automatically, said switch 99 can be employed to effect actuation of an automatic tape applying machine, not shown. Thus said switch 5 9, together with its associated timer and associated circuits, can be employed to complete a circuit through solenoid 80 which will switch four-way valve 30 to admit air from air header 78 to the taping machine. Said circuit which is completed through switch Q9 and its associated timer and associated circuits is completed in exactly the same manner as described above in connection with switch 98 and timer 106. Any other suitable mechanism and/ or circuitry can be employed to actuate the automatic taping machine. If an automatic taping machine is not employed, the tape is applied manually as described elsewhere herein.

At the next stage of rotation, the filled and taped bag arrives at station 3 where the lower horizontal bar of actuating lever 96 strikes the actuating bar of switch 101, a circuit is completed through the associated timer and its associated circuits, solenoid 94, and four-way valve 94 is switched to admit air to one of

conduits

92 and 93 connected to cylinder 36. This will actuate the piston in said cylinder 86 and cause kick-off plate 91 to move the bag from the bag pocket at station 3. The operation of solenoid 94- and switch 94, responsive to closing of switch 101, is exactly the same as that described above for solenoid '79 and valve 79.

Switches 98, 99', and 1431 are hand operated switches provided for manual operation of the machine.

In view of the above description it is believed clear that the timers, such as timer 106, can be selected to give any desired timing cycle within reasonably broad limits. For example, in one bag closing machine which was fabricated in accordance with this invention, the machine was designed to handle fifteen bags per minute. Thus, a filled, unclosed bag enters station 1 every four seconds. The timers 1% are set accordingly. Approximately one second is required to complete each stage of rotation. Thus each bag receiving pocket is stationary at each of the

stations

1, 2, 3, and 4 for approximately three seconds.

The wiring diagram in FIGURE 11 has been shown schematically in order to simplify the drawings. In actual construction the switches, timers, solenoids, valves, and associated lead wires are mounted on base 11) in suitable positions.

In the operation and practice of the invention a filled bag is delivered from a bag filling machine (not shown) by means of conveyor 116 into pocket 19-19 located at station 1 of the bag closing machine as illustrated in FIGURE 1. The lips of said bag are guided by means of rotating V-

belts

117 and 118 which operate from a power source not shown and rotate over

pulleys

119 and 121, respectively. Said pulleys can be suspended in the position illustrated by any suitable means. Prior to the entry of the filled bag into the bag receiving pocket 19-19 as station 1,

fingers

48 and 49 are in the open receiving position as shown in FIGURE 2. Said V-

belts

117 and 118 guide the lips of the filled bag between said fingers 4-8 and 49. The bag upon entering the bag receiving pocket strikes the upper horizontal bar of actuating lever 96 which causes the lower horizontal bar of said lever 96 to strike the actuating bar of switch 98 which completes the circuit as illustrated and described above in connection with FIGURE 11 causing air to be delivered to cylinder 72. Piston '73 is thereupon actuated, the entire frame assembly is rotated by means of the rotating means illustrated in FIGURE 5, and pocket 1- 19 is moved from station 1 to station 2. The operation of the invention will be further described in terms of the movement of said pocket 19-19.

FIGURE 1 illustrates the position of the apparatus just after the rotation has been initiated. Prior to the entry of the filled bag into the bag receiving pocket 19-19,

fingers

43 and 49 are held in open position by cam lug 53 being in contact with extension 61 of slide plate 56. At this time main shaft 38 is prevented from rotating due to fiat cam surface 42 on collar 41 bearing against the under side of small extension 57 on slide plate 56. As rotation of the frame is initiated said flat cam surface 42. clears said extension 57 on slide plate 56 and cam lug 53 clears said extension 61 on slide plate 59 whereupon spring 54 causes spur

gears

51 and 52 to rotate

finger shafts

46 and 47 and cause

polished fingers

48 and 49 to close and engage the lips of the bag as shown in FIGURE 1. At the same time sprocket wheel 44 engages rack gears 63 on drive plate 62 (which is fixed to column 11 and remains stationary) and main shaft 38 is revolved l 4 revolutions with said

polished fingers

48 and 49 in closed position to roll the lips of the bag around said fingers and downwardly onto the body of the filled bag. Due to the arrangement of the indexing ring 66 and the rotating mechanism illustrated in FIGURE 5, the frame will be rotated through a 90 increment or stage with the pocket 1&1), formerly at station 1, moving to and stopping at station 2. It should be noted that the rolling down of the top of the bag occurs as said pocket 19-19 is being moved from station 1 to station 2. It should also be noted that during the movement of said pocket 19-19 from station 1 to station 2 the bottom of the pocket is raised in elevation, due to the change in elevation of track 35, an amount sufiicient to compensate for the amount which the lips of the bag are rolled downwardly onto the body of the filled bag.

While said pocket 19-19 containing the filled bag with the rolled down top is at station 2, one or more, usually two, pieces of pressure adhesive tape are applied vertically across the rolled down portion of the bag as shown in FIGURE I. Said pressure adhesive tape can be applied manually or it can be applied by means of any suitable automatic tape applying machine. Said tape applying machine can be actuated by means of switch 99 provided at station 2 expressly for this purpose. It is within the scope of the invention to thus actuate any suitable type of auto matic tape applying machine which is employed in combination with the bag closing machine of the invention.

At station 2 flat cam surface 43 on collar 41 is in position to engage extension 58 on slide plate 56. The entry of another filled bag into the empty bag pocket 23-23 now at station 1 again activates the rotating mechanism as previously described and the pocket 19-19 is moved from station 2 to station 3. Upon initiation of said second stage or increment of movement, cam surface 4-3 on collar 41 engages extension 53 on slide plate 56 and prevents rotation of main shaft 38 during movement of said pocket 19-19 from station 2 to station 3. The

polished fingers

43 and 49 thus remain in the rolled down portion of the bag lips.

Upon arrival of the filled and taped bag at station 3, the lower horizontal bar of actuating lever 96 strikes the actuating bar of switch 101 whereupon a circuit is completed as illustrated in FIGURE 11 to actuate the solenoid operated valve 94 and admit air to cylinder 86. The piston in said cylinder 86 then moves push-off plate 91 and pushes the filled bag off the

polished fingers

48 and 49 and onto conveyor 122 (see FIGURE 1). At this point, the filled bag can, if desired, be pushed over by means of any suitable pushing apparatus, such as ram 123, onto conveyor 124 and transported to storage or other further handling.

The entry of another filled bag into the empty pocket 22-22 now at station 1 will activate rotation of the frame as previously described and the now empty pocket 19-19 at station 3 will be rotated to station 4. During movement of the empty pocket 19-19 from station 3 to station 4 cam surface 43 on collar 41 remains in contact with extension 58 on slide plate 56 to prevent rotation of main shaft 38 and

fingers

48 and 49 remain in their closed position. At station 4 said flat cam surface 43 on collar 41 disengages extension 58 on slide plate 56.

Upon the entry of another filled bag into the empty pocket 21-21 now occupying station 1, the rotating mech anism will be again activated as previously described and the empty pocket 19-19 at station 4 will be moved to station 1. Upon initiation of said last-mentioned stage of rotation sprocket 44 engages rack gears 64 on drive plate 62 and rotates the main shaft 38 A of one revolution. When sprocket 44 clears the end of the segment of rack gears 64, rotation of the main shaft 38, of course, stops. At this time cam lug 53 attached to gear 51 comes in contact with extension 61 on slide plate 59, the biasing action of spring 54 is overcome, and

finger shafts

46 and 47 are rotated through 90 to place the

polished fingers

48 and 49 in open receiving position as shown in FIGURE 2 upon arrival at station 1. At the same time fiat cam surface 42 on collar 41 engages the small extension 57 on slide plate 56 and prevents rotation of main shaft 38. The sprocket 19-19 which was originally at station 1 has now completed the circuit and is again in position to receive another filled bag and start another revolution of the machine as described.

Referring to FIGURES 1 and 2 it will be clear that each of the other bag receiving pockets 21-21, 22-22,

and 23-23 is provided with a bag engaging and closing v means comprising a main shaft 38 and a pair of

fingers

48 and 49. During the rotation of the frame each of said pockets goes through the four stages of movement, consecutively occupies each of the

stations

1, 2, 3, and 4, and the same operations are carried out at each station as described above for pocket 19-19.

The invention is applicable to the closing of any type of flexible bag made of any flexible material such as paper, cloth, plastic, etc. The invention is particularly applicable to the closing of multi-wall open mouth paper bags. However, all types of bags, either single wall or multi-wall, can be closed according to the invention.

The actual dimensions of a bag closing machine fabricated in accordance with the invention will depend, to some extent, on the size of the filled and closed bag to be handled. For example, a machine fabricated in accordance with the invention for handling filled bags having a length of about 27 inches, a width of about 16 inches, and a thickness of about 4 inches when closed, had a width as measured through stations 2 and 4 (see FIGURE 2) of approximately 5 feet 6 inches and an overall height of approximately 5 feet (see FIGURES 1 and 3). The

fingers

48 and 49 were mounted approximately 2 feet 8 inches above the bottom of the bag receiving pocket positioned at station 1 and Were about 2 feet above the bottom of the bag receiving pocket at

stations

2, 3 and 4. This difference in the elevation of said fingers above the bottom of the bag receiving pocket is, of course, due to the difference between the elevation of track 35 at station 1 and

stations

2, 3, and 4. Refernce to FIGURE 3 clearly shows this difference in elevation of said track 35 which causes the bottom of the bag 18 receiving pocket to be elevated. The bag receiving pockets were each about 1 foot 4 inches in length and about 8 inches in width. Drive plate 62 was approximately 1 foot 9 inches in diameter. The remainder of the elements of the machine were proportionately sized.

The feature of the invention whereby the elevation of track 35 at station 1 is less than the elevation of said track at the other three

stations

2, 3, and 4 affords one of the outstanding advantages of the invention. Not only does said difference in elevation make it possible to compensate for the amount of the bag top which is rolled down as the bag is moved from station 1 to station 2, but said difference in elevation also makes it possible to adjust the bag closing machine to handle different sizes of bags. This is made possible due to the fact that said track 35 is adjustably mounted on base 10, as shown in FIGURE 3 for example.

Other advantages of the machine are that it can be operated at any desired speed within reasonable limits so as to accommodate the bag filling equipment and different rates of production. This adjustment in rate of operation of the machine can be effected by varying the time cycle of the timers 106 shown in FIGURE 11. The bag closing operation can be made entirely automatic, if desired, by employing an automatic taping machine in combination with the bag closing machine; or, the tape can be applied manually if desired. Still another advantage is that the troublesome sewing equipment formerly widely used for closing open mouth bags is eliminated. The tape employed according to the method of the invention is less expensive than the thread and tape employed in sewing.

The bag closing method of the invention provides a simple, neat, but yet very effective closure. The closed bag is substantially square on both ends. The closed bag is thus box-like and is much more adapted for stacking in storage and other handling. Rolling down the top of the bag reduces the volume of the finished container to substantially the volume of its contents. This firmer, more compact pack presents a more desirable appearance for sales appeal and can be handled and stored more efliciently.

Also, while the specific embodiment of the invention illustrated and described above is provided with four bag receiving pockets spaced equidistantly apart on four different sides of the frame of the machine, it is within the scope of the invention to provide a machine which is comprised of less than four or more than four equidistantly spaced apart bag receiving pockets constructed in accordance with the invention, for example, a machine having three pockets. In such a machine the empty pocket from station 3 would move into station 1 for receiving a filled, unclosed bag. As another example, a machine provided with six bag receiving pockets could also be constructed in accordance with the invention. In such a machine the empty pocket now illustrated at station 4 would become station 1 of a second sequence of

stations

1, 2, and 3. Such a machine provided with six bag receiving pockets could receive filled, unclosed bags from two different bag filling machines.

While certain embodiments of the invention have been described for illustrative purposes, the invention obviously is not limited thereto. Various other modifications will be apparent to those skilled in the art in view of this disclosure. Such modifications are within the spirit and scope of the invention.

I claim:

1. A bag closing machine comprising: a rotatable frame, means for rotating said frame in stages through a plurality of consecutive stations comprising a first, a second, and a third station; a bag receiving pocket formed in said frame on one side thereof, said pocket consecutively occupying said stations during said rotation of said frame; means, actuated by an open bag moving into said pocket while it is occupying said first station, for actuating said rotating means; means for closing said open bag as said frame is rotated and said pocket containing said bag is moved from said first station to said second station; means mounted within said frame for pushing said closed bag from said pocket when said pocket reaches said third station; and means at said third station for actuating said bag pushing means when said pocket arrives at said third station.

2. A bag closing machine comprising: a rotatable frame; means for rotating said frame in stages through a plurality of consecutive stations comprising a first, a second, and a third station; a plurality of bag receiving pockets formed in said frame, each of said pockets being formed in a different side of said frame and spaced apart equidistantly from each other, and each of said pockets consecutively occupying said stations during said rotation of said frame; bag engaging means extending above each of said pockets and adapted to receive the lips of the open mouth of a bag when it is moved into the one of said pockets occupying said first station; means, actuated by said open bag moving into the said pocket at said first station, for actuating said rotating means; means for actuating and causing said engaging means to engage said lips of said bag and roll said lips around said engaging means as said pocket containing said bag is rotated from said first station to said second station, and thereby closing said bag; means mounted within said frame for pushing said closed bag from said pocket when said pocket reaches said third station; and means at said third station for actuating said bag pushing means when said pocket arrives at said third station.

3. A bag closing machine comprising: a rotatable frame; means for rotating said frame in stages through consecutive first, second, third, and fourth stations; a bag receiving ocket formed in said frame on one side thereof, said pocket consecutively occupying said stations during said rotation of said frame; means, actuated by an open bag moving into said pocket while it is occupying said first station, for actuating said rotating means; means for closing said open bag as said frame is rotated and said pocket containing said bag is moved from said first station to said second station; means mounted within said frame for pushing said closed bag from said pocket when said pocket reaches said third station; and means at said third station for actuating said bag pushing means when said pocket arrives at said third station.

4. A bag closing machine comprising: a rotatable frame; means for rotating said frame in 90 degree increments through consecutive first, second, third and fourth stations; four bag receiving pockets formed in said frame on different sides thereof and spaced apart equidistantly from each other, each of said pockets consecutively occupying said stations during said rotation of said frame; means, actuated by an open bag moving into the pocket occupying said first station, for actuating said rotating means; means for closing said open bag as said frame is rotated and said pocket containing said bag is moved from said first station to said second station; means mounted within said frame for pushing said closed bag from said pocket when said pocket reaches said third station; and means at said third station for actuating said bag pushing means when said pocket arrives at said third station.

5. A bag closing machine comprising: a rotatable frame; means for rotating said frame in 90 degree increments consecutively through a first, a second, a third, and a fourth station; four bag receiving pockets formed in said frame on four different sides thereof and spaced apart equidistantly from each other, each of said pockets consecutively occupying said stations during said rotation of said frame; four bag engaging means each extending above one of said pockets and adapted to receive the lips of the open mouth of a bag when it is moved into the one of said pockets occupying said first station; means, actuated by said open bag moving into the said pocket occupying said first station, for actuating said rotating means, means for actuating said bag engaging means to engage said lips of said bag and roll said lips around said engaging means and down as said pocket containing said bag is rotated from said first station to said second station, thereby closing said bag; means for raising the bottom of said pocket containing said bag as said bag is moved from said first station to said second station so as to compensate for the amount said lips of said bag are rolled down; means mounted within said frame for pushing said closed bag from said pocket containing same when said pocket reaches said third station; and means at said third station, actuated by the arrival of said bag containing pocket at said third station, for actuating said bag pushing means.

6. A bag closing machine comprising: a rotatable frame mounted on a base; means for rotating said frame in degree increments consecutively through a first, a second, a third, and a fourth station; four bag receiving pockets formed in said frame on four different sides thereof and spaced apart equidistantly from each other, each of said pockets consecutively occupying said stations durng said rotation of said frame; a bag conveyor assembly slidably mounted for limited vertical movement in each of said bag receiving pockets, a circular track mounted below said frame on said base, said track having a lower elevation at said first station than at said second, third and fourth stations; separate means attached to each of said bag conveyor assemblies for movably supporting each said assembly individually on said track during said rotation of said frame; four bag engaging means each extending above one of said pockets and adapted to receive the lips of the open mouth of a bag when it is moved into the one of said pockets occupying said first station; means, mounted on a wall member of each of said pockets and actuated by said open bag moving into the said pocket occupying said first station for actuating said rotating means; means for actuating said bag engaging means to engage said lips of said bag and roll same down as said pocket containing said bag is rotated from said first station to said second station, thereby closing said bag; means mounted within said frame for pushing said closed bag from said pocket containing same when said pocket reaches said third station; and means, mounted on said base and actuated by the arrival of said bag containing pocket at said third station, for actuating said bag pushing means.

7. A bag closing machine comprising: a base; a vertical support column centrally disposed with respect to and attached to said base; a first hub rotatably mounted around the lower portion of said column; a second hub rotatably mounted around the upper portion of said column; a frame surrounding said column, said frame being attached at its lower portion to said first hub and attached at its upper portion to said second hub; means for rotating said hubs and said frame around said column in 90 degree increments consecutively through a first, a second, a third, and a fourth station; four bag receiving pockets formed in said frame on four different sides thereof and spaced apart equidistantly from each other, each of said pockets occupying said first, second, third, and fourth stations consecutively as said frame is rotated; a bag conveyor assembly slidably mounted for limited vertical movement in each of said bag receiving pockets; a circular track mounted on said base and surrounding said support column, said track having a lower elevation at said first station than at said second, third, and fourth stations; separate means attached to each of said bag conveyor assemblies for movably supporting each said assembly individually on said track during said rotation of said frame; four bag engaging means, each operatively connected to said column above said second hub and extending above one of said pockets, and adapted to receive the lips of the open mouth of a bag when it is moved into one of said pockets occupying said first station; means, mounted on a wall member of each of said pockets and actuated by said open bag moving into the said pocket at said first station for actuating said rotating means; means for actuating said bag engaging means to engage said lips of said bag and roll same down as said pocket containing said bag is rotated from said first station to said second station, thereby closing said bag; means mounted within said frame for pushing said closed bag from said pocket containing same when said pocket reaches said third station; and means, mounted on said base and actuated by the arrival of said bag containing pocket at said third station, for actuating said bag pushing means.

8. A bag closing machine comprising, in combination: a base; a vertical support column centrally disposed with respect to and attached to said base; a first hub rotatably mounted around the lower portion of said column; a second hub rotatably mounted around the upper portion of said column; a frame surrounding said column, said frame being attached at its lower portion to said first hub and attached at its upper portion to said second hub; means for rotating said hubs and said frame around said column in 90 degree increments consecutively through a first, a second, a third, and a fourth station; a first, a second, a third, and a fourth bag receiving pocket formed in said frame on four different sides thereof and spaced apart equidistantly from each other, each of said pockets occupying said first, second, third, and fourth stations consecutively as said frame is rotated; a bag conveyor as sembly slidably mounted for limited vertical movement in each of said bag receiving pockets; a circular track mounted on said base and surrounding said support column, said track having a lower elevation at said first station than at said second, third, and fourth stations; separate means attached to each of said bag conveyor assemblies for movably supporting each said assembly individually on said track during said rotation of said frame; four bag engaging means, each operatively connected to said column above said second hub and extending above one of said pockets, and adapted to receive the lips of the open mouth of a bag when it is moved into the one of said pockets occupying said first station; means, mounted on a wall member of each of said pockets and actuated by said open bag moving into said pocket at said first station for actuating said rotating means; means for actuating said bag engaging means to engage said lips of said bag and roll same down as said pocket is rotated from said first station to said second station, thereby closing said bag; means at said second station for actuating a tape applying machine for applying tape across the rolled down top of said bag; means mounted on said column within said frame for pushing said bag from said pocket when said pocket reaches said third station; and means, mounted on said base and actuated by the arrival of said bag containing pocket at said third station, for actuating said bag pushing means.

9. A bag closing machine, adapted for operation inde pendent of preceding bag filling and succeeding bag handling means, said machine comprising: a rotatable frame mounted on a base; four bag receiving pockets formed in said frame on four different sides thereof; means for rotating said frame in 90 degree increments, each of said pockets consecutively occupying a first, a second, a third, and a fourth station during said rotation; means, actuated by an open bag moving into the one of said pockets occupying said first station, for actuating said frame rotating means to move said bag containing pocket from said first station to said second station; means, operable simultaneously with the movement of said pocket from said first station to said second station, for closing said open bag; means mounted within said frame for pushing said closed bag from said pocket containing same when said pocket reaches said third station; and means, mounted on said base and actuated by ii the arrival of said bag containing pocket at said third station, for actuating said bag pushing means.

10. A bag closing machine, adapted for operation independent of preceding bag filling and succeeding bag handling means, said machine comprising: a rotatable frame; four bag receiving pockets formed in said frame on four different sides thereof and spaced apart equidis tantly from each other; means for rotating said frame in degree increments, each of said pocket consecutively occupying a first, a second, a third, and a fourth station during said rotation; four bag engaging means each extending above one of said pockets and adapted to receive the lips of the open mouth of a bag when it is moved into the one of said pockets occupying said first station; means, actuated by an open bag moving into the said pocket occupying said first station, for actuating said rotating means to (a) rotate said frame and move said pocket containing said bag from said first station to said second station and (b) cause said engaging means to engage the lips of said bag and roll said lips around said engaging means simultaneously with the movement of said bag containing pocket from said first station to said second station, and thereby close said bag; means mounted within said frame for pushing said closed bag from said pocket containing same when said pocket reaches said third station; and means at said third station, actuated by the arrival of said bag containing pocket at said third station, for actuating said bag pushing means.

11. A bag closing machine, adapted for operation independent of preceding bag filling and succeeding bag handling means, said machine comprising: a rotatable frame mounted on a base; first, second, third, and fourth bag receiving pockets formed in said frame on four different sides thereof and spaced apart equidistantly from each other, each of said pockets consecutively occupying a first, a second, a third, and a fourth station during rotation of said frame; means for rotating said frame in 90 degree increments; means, actuated by a filled open bag moving into one of said pockets While it is at said first station for actuating said rotating means to cause said frame to rotate and move said bag containing pocket from said first station to said second station, move the one of said pockets formerly occupying said second station to said third station, move the one of said pockets formerly occupying said third station to said fourth station, and move the one of said pockets formerly occupying said fourth station to said first station; means, operable simultaneously with the rotation of said bag containing pocket from said first station to said second station, for closing said open bag; a bag pushing means, mounted within said frame, for pushing a closed filled bag from the one of said pockets occupying said third station; and means at said third station for actuating said bag pushing means when one of said pockets containing a closed filled bag arrives from said second station and occupies said third station.

12. A bag closing machine, adapted for operation independent of preceding bag filling and succeeding bag handling means, said machine comprising: a rotatable frame mounted on a base; first, second, third, and fourth bag receiving pockets formed in said frame on four different sides thereof and spaced apart equidistantly from each other, each of said pockets consecutively occupying a first, a second, a third, and a fourth station during said rotation of said frame; main actuating means mounted on said base at said first station for actuating said rotating means; first actuating means carried by a wall member of each of said pockets and actuated by a filled open bag moving into one of said pockets while it is at said first station for actuating said main actuating means to cause said frame to rotate and move said bag containing pocket from said first station to said second station, move the one of said pockets formerly occupying said second station to said third station, move the one of said pockets formerly occupying said third station to said fourth station, and move the one of said pockets formerly occupying said fourth station to said first station; means, operable simultaneously with the rotation of said bag containing pocket from said first station to said second station, for closing said open bag; means mounted on said base at said second station and actuated by said first actuating means for actuating a tape applying machine for applying tape across the top of said closed bag; bag pushing means, mounted within said frame, for pushing a closed filled bag from the one of said pockets occupying said third station; and means mounted on said base at said third station and actuated by said first actuating means for actuating said bag pushing means when one of said pockets containing a closed filled bag arrives from said second station and occupies said third station.

13. A bag closing machine comprising, in combination: a base; a vertical support column centrally disposed with respect to and attached to said base; a first hub rotatably mounted around the lower portion of said column; a second hub rotatably mounted around the upper portion of said column; a frame surrounding said column, said frame being attached at its lower portion to said first hub and attached at its upper portion to said second hub; means for rotating said hubs and said frame around said column in 90 degree increments consecutively through a first, a second, a third, and a fourth station; a first, a second, a third, and a fourth bag receiving pocket formed in said frame on four different sides thereof and spaced apart equidistantly from each other, each of said pockets occupying said first, second, third, and fourth stations consecutively as said frame is rotated; a bag conveyor assembly slidably mounted for limited vertical movement in each of said bag receiving pockets; a circular track mounted on said base and surrounding said support column, said track having a lower elevation at said first station than at said second, third, and fourth stations; separate means attached to each of said bag conveyor assemblies for movably supporting each said assembly individually on said track during said rotation of said frame; four bag engaging means, each operatively connected to said column above said second hub and extending above one of said pockets, and adapted to receive the lips of the open mouth of a bag when it is moved into the one of said pockets occupying said first station; means for actuating said rotating means when said open bag is moved into said pocket at said first station, means for actuating said bag engaging means to engage said lips of said bag and roll same down as said pocket is rotated from said first station to said second station, and thereby closing said bag; means at said second station for actuating a tape applying machine for applying tape across the rolled down top of said bag; means mounted on said column within said frame for pushing said bag from said pocket when said pocket reaches said third station; and means, mounted on said base and actuated by the arrival of said bag containing pocket at said third station, for actuating said bag pushing means; each of said bag engaging means and said means for actuating said bag engaging means comprising: a main shaft rotatably mounted on said frame above said second hub with its inboard end adjacent said column;

a collar fixed to said inboard end of said main shaft, said collar being provided with first and second flat cam surfaces on adjacent sides thereof; a sprocket wheel fixed on said main shaft adjacent the outboard end thereof; first and second spaced apart parallel finger shafts rotatably mounted within said main shaft; first and second spaced apart parallel fingers attached respectively to the outboard ends of said first and second finger shafts, said fingers extending above one of said pockets and adapted to receive the lips of said open bag when it is moved into the one of said pockets occupying said first station; a first spur gear mounted on the inboard end of said first finger shaft; a second spur gear mounted on said second finger shaft at the inboard end thereof and adapted to engage said first spur gear; a cam lug mounted on the inboard side of said second spur gear; a torsion spring mounted around said first finger shaft and normally biased to cause said spur gears to rotate said fingers to open receiving position; a first annular plate fixed around the periphery of said column above said second hub, said plate being rovided with a first extension thereon between said station four and said station one and positioned adjacent said station one so as to engage said first cam surface on said collar on said main shaft just prior to the arrival of said main shaft at said station one during the rotation of said frame and prevent rotation of said main shaft prior to and while it is above said station one, said plate also being provided with a second extension thereon between said station two and said station four and adapted to engage said second cam surface on said collar on said main shaft while said frame is being rotated around said column between said station two and said station four and prevent rotation of said main shaft; a second annular plate fixed around the periphery of said column between said first plate and said second hub, said second plate being provided with an actuating lug extending therefrom between said station four and said station one and positioned so as to engage said cam lug on said second finger shaft, cause said spur gears to rotate said finger shafts and open said fingers just prior to their arrival in a position above said station one; a circular drive plate fixed on said column above said first plate; a first segment of rack gears mounted on the underside of said drive plate adjacent the periphery thereof between said first and second stations for coacting with said sprocket wheel to rotate said main shaft and said fingers and roll the lips of said bag around said fingers during rotation of said frame and said pocket from said first station to said second station; and a second segment of rack gears mounted on the underside of said drive plate adjacent the periphery thereof between said fourth and first stations, and spaced apart from said first segment of rack gears, for coacting with said sprocket wheel to rotate said main shaft and said fingers suflicient to place said fingers in opening and receiving position.

References Cited in the file of this patent UNITED STATES PATENTS