US3501893A

US3501893A - Bag opening machine

Info

Publication number: US3501893A
Application number: US700667A
Authority: US
Inventors: Axel F Peterson
Original assignee: AXEL F PETERSON
Current assignee: AXEL F PETERSON
Priority date: 1968-01-08
Filing date: 1968-01-08
Publication date: 1970-03-24
Anticipated expiration: 1987-03-24

Description

March 24, 1970 A. F. PETERSON 3,501,893

BAG OPENING MACHINE Filed Jan. 8, 1968 v 6 Sheets-Sheet 1 INV ENT OR 50 AXE! f. Ptrewswv March 24, 1970 A. F. PETERSON BAGDPENING MACHINE 6 Sheets-Sheet 2 Filed Jan. 8, 1968 7 u v y a 4- 1 J 2W0. 4 3\ Lil. I 4 5 a 54. w M u w 9 7 a M 10 6 N 4 aw 1/ 5 f 4 M fi a 5 Fm z a w w a 3 171 3 MM, A M

Axn 1"." PETERSON (2 BY Q.

ATTORNEY March 24, 1970 A. F. PETERSON BAG OPENING MACHINE 6 SheetsSheet 4 Filed Jan. 8, 1968 INVENTOR AXE; F P'l'E/PSON BY gwvhannmq ATTORNEY March 24, 1970 A. F. PETERSON 3,

BAG OPENING MACHINE Filed Jan. 8, 1968 v 6 Sheets-Sheet 6 INVENTOR AXEL F. Fifi-RSON BY QMW ATTORNEY United States Patent US. Cl. 53-190 Claims ABSTRACT OF THE DISCLOSURE The invention discloses a bag opening apparatus for use with fiat folded bags having pleated walls. The device includes a bag filling guide, and a pair of arms pivoted on parallel planes on opposite sides of said guide. The arms are provided with extensible and retractable end portions provided with bag engaging suction cups connectable to a source of partial vacuum. The arms are swingable from a substantially vertical position through somewhat more than ninety degrees to a position adjacent to the filling guide and on opposite sides thereof. When in vertical position the suction cups of one arm engage the uppermost bag of a series of superimposed bags. The extensible end of said one arm retracts, and the arms swing in unison until the bag is engaged by the suction cups of the other arm. The extensible end of the other arm retracts to open the big. When carried to position adjacent the filling guide the sides of the bag are clamped for filling.

This invention relates to an improvement in bag opening machine and deals particularly with an apparatus capable of picking up a bag from a supply stack, swinging it into upright position, opening the upper end of the bag, and holding the bag in opened position for a predetermined time period before releasing it.

Some years ago the filling of bags with flowable material of one type or the other was a manual operation. The operator picked up a bag from a supply pile, opened it up and placed it beneath a filling mechanism, operated the filling mechanism to fill the bag, and carried or otherwise moved the filled bag to a bag closing mechanism such as a sewing machine, a stapler, or the like. With the increase in cost of labor, such a manual operation became somewhat impractical, and as a result, machines of one type or the other were developed to accomplish the desired result. The present invention lies in the provision of an apparatus for packing up a bag made of paper or other suitable material from a vertical stack or pile of horizontal bags, swinging the bag into vertical position and simultaneously opening the bag by drawing the opposite walls of the bag apart, and holding the bag in an elevated position during the filling operation. As soon as the bag is released, the bag is moved out of filling position and the cycle of operation repeats.

A feature of the present invention resides in the provision of a device including suction arms swingable from a generally upright position in which suction cups on one of the arms engage the uppermost bag of a stack of bags through an angle of somewhat more than 90 degrees to a position adjoining a filling spout. As one suction arm carries the bag from one position to another, a second suction arm engages the opposite side of the bag, the two suction arms drawing the bag into open position as it moves into filling position. Means are provided for pivoting the arms on opposite sides of the bag in unision during the bag opening operation.

A feature of the present invention resides in a device of the type described including a pair of clamping members which enter the open upper end of the bag as it reaches filling position. As the upward movement of the bag stops, means are actuated to move the clamping 3,501,893 Patented Mar. 24, 1970 ice means against the bag to hold the bag securely during the filling operation. After a predetermined time period, the clamping means is released allowing the bag to drop unto a suitable conveyor and permitting the suction arms to return to starting position.

A further feature of the present invention resides in the provision of a suction arm including two tubular telescoping members one of which is provided at its end with one or more parallel suction cups. The other tubular member is connected to a source of partial vacuum. As the suction arms swing down toward vertical position, the portion of the suction arm bearing the suction cup slides partially out of the tubular member connected to the vacuum source to elongate the arm. As soon as the suction cups engage the surface of a bag, the suction acts to retract the slidable tubular member into the pivoted tubular member, raising the bag from the stack into position to be opened.

A further feature of the present invention resides in the provision of a particular type of suction cup which has been found particularly useful in the combination. The suction cup includes a relatively inflexible tube to which is secured a highly flexible skirt which is preferably corrugated so as to readily contract in length. The flexible skirt is brought into contact with the surface of the bag, and immediately conforms to the shape of the bag. When the skirt is engaged to the bag, the suction acts to contract the skirt until the surface of the bag is drawn against the end of the relatively inflexible inner tube. With this arrangement, the bags are readily picked up while at the same time the movement of the bag is controlled by engagement of the wall of the bag against the rigid inner tube once the bag has been picked up.

These and other objects and novel features of the present invention will be more clearly and fully set forth in the following specification and claims.

In the drawings forming a part of the specification:

FIGURE 1 is a front elevational view of the bag opening apparatus showing the general arrangement of parts therein.

FIGURE 2 is a perspective detail of the bag lifting arm showing the latch arrangement used to hold the arm in inoperable position when the device is not in use.

FIGURE 3 is a perspective detail of one arrangement of suction cups which may be used on the bag lifting arm.

FIGURE 4 is a vertical sectional view through one of the suction cups illustrated in FIGURE 3 of the drawlllgS.

FIGURE 5 is a diagrammatic top plan view of the bag opening mechanism, showing the general arrangement of parts therein.

FIGURE 6 is a perspective view showing one of the bag lifting arms.

FIGURE 7 is a sectional view through a portion of the bag lifting arm.

FIGURE 8 is a fragmentary detail showing the manner in which the two bag engaging arms are moved in unison.

FIGURE 9 is a fragmentary view showing the cylinder employed for rotating the arms in unison.

FIGURE 10 is a fragmentary detail showing the means for operating the bag clamping means to hold the bag in open position during filling.

FIGURE 11 is a vertical sectional view through the means for clamping the bag in open position during the filling operation.

FIGURE 12 is a fragmentary detail illustrating the mounting of the bag opening arm.

FIGURE 13 is a diagrammatic view showing the general position of the bag lifting and opening arms at the beginning of a cycle of operation.

FIGURE 14 is a diagrammatic view of the position of the arms as the bag is lifted into position to be engaged by both of the opposed arms.

FIGURE 15 is a diagrammatic view showing the position of the arms when the bag is in fully elevated position.

FIGURE 16 is a side elevational view of the bag opening arm in operable position.

FIGURE 17 illustrates diagrammatically a portion of the pneumatic system.

FIGURE 18 is a diagrammatic view showing the air pressure and air suction lines and the valves used to operate the same.

FIGURE 19 is an enlarged detail of the end of the bag lifting arms showing the suction cups in elevated position.

FIGURE 20 is a view similar to FIGURE 19 but showing the suction cups after they have engaged the surface of a bag.

FIGURE 21 is an enlarged sectional detail showing the manner in which the bag may flex relative to the suction cup arrangement.

The bag opening apparatus is best shown in general in FIGURES 1 and 5 of the drawings. The device is indicated in general by the letter A, and includes a pair of front posts or standards and 11, and a pair of similarly spaced rear posts or standards 12 and 13. The upper end of the

standards

10 and 11 are connected by a horizontal connecting member 14, and the upper ends of the posts 12 and 13 are connected by a parallel horizontal connecting member 15. The connecting members 14 and 15 are connected by cross-members 16 and 17. The

standards

10 and 11 may also be connected by other supporting frame members, as may also be the standards 12 and 13.

A horizontal connecting member 19 may connect the columns 12 and 13, and

vertical angle members

20 and 21 may extend upwardly from the lower frame member 19 to the upper frame member 15. A generally rectangular frame 22 extends laterally to one side of the

columns

11 and 13 as is best illustrated in FIGURE 5. The rectangular frame member 22 includes a front frame member 23, a rear frame member 24, and a side connecting frame member 25. As indicated in FIGURE 1 of the drawings the frame 22 is supported by suitable supporting legs 26.

The front and

rear columns

11 and 13 are provided with bearings 29 which support a horizontal shaft 30 (see FIGURE 2). The shaft 30 pivotally supports the bag lifting arms 31 and function to swing the arm mechanism 31 through somewhat more than 90 degrees. A similar pair of bearings .32 (see FIGURE 1) are mounted upon the vertical standards or columns 10 and 12 to support a shaft 33 in opposed relation to the shaft 30. The shaft 33 supports the arm mechanism which is indicated in general by the numeral 34 and which functions to open up the bag B which is lifted by the suction arm 31.

A platform or table 36 is supported within the frame 22. Vertical rods 37 are connected to the platform 36 near the corners thereof, and the rods 37 are slidable in sleeves 39 supported by vertical brackets 40 mounted upon the frame 22. The platform 36 is supported by a pair of cables 41 which are secured to opposite sides of the plaform 3'6 and are secured in their opposite ends, as indicated at 42, to the frame 22. A pair of vertical cylin- :lers 43 are mounted upon the frame members 23 and 24 on opposite sides of the platform 36 near the center thereof, and each cylinder contains a piston identified in FIGURE 18 by the numeral 44 and to which a piston rod 45 is attached. The pulley 46 ismounted in a clevis 47 at the upper end of each piston rod 45. The cable 41 extends from the platform 36, over the pulley 46 and is anchored to the frame at 42. Accordingly, as the piston 44 is forced upwardly in each of the cylinders 43, the elevations of the pulley 46 increases, and the platform 36 is raised. The purpose of this arrangement is to maintain the uppermost bag B on the platform 36 at a substantially equal level.

As indicated in FIGURE 2 of the drawings, a clamping bracket 49 is secured to the pivot rod 30. A radially extending arm 50 is secured to the bracket 49 and supports a right angularly extending bracket 51. A tubular member 52 forming the upper pivotal end of the bag lifting arm is clamped in the bracket 51. A second clamping bracket 53 is secured to the tubular member 52 below the position of the bracket 51 when the bag lifting arm is in generally vertical position. The bracket 53 is provided with a laterally extending arm 54 supporting a rod 55 which extends through the arm 50. The rod 55 is provided with adjustable stop means 56 for a purpose which will be later described.

A second tubular member 57 is slidably supported within the tubular member 52, and supports a yoke 59 designed to support suction cups of a type which will be later described. The clamping bracket 53 supports a laterally extending bracket 60 which pivotally supports a locking arm 61. The locking arm 61 is provided with an angularly turned lower end 62 which is engageable beneath the yoke 59 of the lower tubular member 57. The arm 61 is provided with an enlarged upper end 63 which may be pivotally engaged by a locking lever 64 mounted upon a bracket 65 adjustably secured to the upright 11.

The arrangement is such that when the latch member 64 is in one position shown in dotted outline in FIG- URE 2, the hook end 62 of the arm 61 is out of the path of movement of the yoke 59 of the tubular member 57, allowing the yoke to drop into contact with the surface of the bags B. When the latch 64 is in its outer extreme position, the arm 61 moves into the position shown in dotted outline in FIGURE 2 of the drawings, engaging the yoke 59 and preventing the tubular member from dropping. As indicated in FIGURE 2, the spring 66 normally draws the hook end '63 toward one extreme position. A lug 67 on the latch 64 holds the latch in either extreme position, the latch being manually operable.

The means for operating the bag lifting arm 31 is best illustrated in FIGURES 1 and 9 of the drawings. A crossmember 69 connects the rear column 13 with the upright 21. A pneumatic cylinder 70 is pivotally connected at 68 to the cross-member 69. A piston 71 (see FIGURES 9 and 18) is connected to a connecting rod 72 leading to a crank arm 73 mounted upon the shaft 30. When the piston 71 is moved upwardly in the cylinder 70, the crank arm 73 is rotated in clockwise direction rotation of the arm 30. The cylinder 70 and its piston 71 are so proportioned that the bag lifting arm 31 is pivotal from a generally vertical position in which the suction cups engage the uppermost bag B, to the position illustrated in full lines in FIGURE 1 of the drawings. In other words, in the arrangement illustrated the shaft 30 is rotated through an angular distance of somewhat more than 90 degrees by the piston 71 and the cylinder 70.

With reference to the FIGURES 1 and 8 of the drawings, means are provided for rotating the

shafts

30 and 33 in unison. As indicated in FIGURE 1, a sprocket 74 is mounted upon the shaft 30. A cooperable sprocket 75 is mounted upon a shaft 76. The shaft 76 is supported by a bracket 77 in fixed relation to the frame. The

sprockets

74 and 75 are connected by a chain 79, the tension of which is adjusted by means of an idler sprocket 80. A parallel shaft 81 supported by a bracket 78 supports a sprocket 82 connected to the shaft 33 by means of a chain 83, the tension of which is adjusted by an idler sprocket 84. As indicated in FIGURE 5 of the drawings the shafts 76 and 81 support intermeshing gears 86 and 87 which cause the shafts 76 and 81 to move in unison in opposite directions. As a result, the clockwise movement of the shaft 30 controlling the position of the bag pickup arm unit 31 causes a counter-clockwise pivotal movement of the shaft 33 supporting the bag opening arm unit 34.

As is indicated in FIGURES 6 and 7 of the drawings, a bracket 90 is mounted upon the shaft 33 and includes a radially extending arm 91 supporting a clamping bracket 92 which is in right angular relation to the clamping bracket 90. The bracket 92 includes a tubular arm member 93 which is clamped in fixed relation to the shaft 33. A second tubular member 94 is slidable in the tubular member 93 for movement longitudinally thereof. As indicated in FIGURE 7 of the drawings, a seal 95 is interposed between the end of the tubular member 93 and the tubular member 94. A second seal 96 is interposed between the upper end of the tubular member 94 and the pivotal tubular member 93. Thus when the interior of the tubular member 93 is subjected to partial vacuum, the interior of the tubular member 94 is similarly subjected to partial vacuum.

A yoke 97 is secured to the lower end of the tubular member 94. The yoke 97 is hollow and tubular, and the actual construction of this portion of the apparatus is best illustrated in FIGURES 19 and 21 of the drawings. It should be understood that the yoke 97 is identical to the yoke 59 mounted upon the tubular member 57 of the bag pickup unit 31.

As indicated, the yoke 97 is substantially inverted U-shaped in form terminating in end portions 99 which are on a substantially common plane. Flexible resilient corrugated sleeves 100 are provided with a relatively large diameter open end 101, and a relatively small diameter cylindrical attaching sleeve 102 which encircles the yoke 97. The arrangement is such that when the corrugated suction cups 100 are in their normal relaxed position as indicated in FIGURE 19 of the drawings, the open ends 101 of the cups extend substantially beyond the ends 99 of the yoke 97. The corrugated flexible nature of the cups or sleeves 100 permit the open end to readily adapt themselves to the surface of the bag B being engaged. On the other hand, when the open ends 101 of the collapsible sleeves 100 are subjected to partial vacuum and are closed by a surface of the bag B, the sleeves 100 will collapse until the end 99 of the yoke 97 are in contact with the surface of the bag B. As indicated in FIGURE 2l of the drawings, once the bag B has been engaged and drawn against the end 89 of the yoke 97, the surface of the bag may bend to permit the bag B to assume a considerable angularity relative to the collapsible sleeve portion 100 of the suction cups.

The

tubular members

52 and 57 operate in a manner similar to the

telescoping tubes

93 and 94. As long as the suction cups on the yoke 59 and the yoks 97 are open to atmosphere, and when the tubular members are in generally vertical position as indicated in dotted outline in FIGURE 1 of the drawings, the suction cup supporting yokes drop by gravity into extended position. The degree of extension of the

tubular members

52, 57 is limited by the rod 55 and the adjustable nut 56. The degree of extension of the

tubular members

93, 94 is limited by the rod 103 which extends through a lug 104 on the tubular member 94, and through aligned apertures in

lugs

105 and 106 on the tubular members 93, the limit of movement of the rod 103 being adjusted by an adjustment nut or collar 107. As is indicated in FIGURE 1 and FIGURE 6 of the drawings, flexible suction hoses 109 and 110 are connected to the

tubular members

52 and 93 respectively to withdraw air therefrom. Thus when the bag pickup arm unit 31 pivots into substantially vertical position, and the yoke 59 drops until the suction cups 111 mounted upon the yoke 59 engages the uppermost bag B, the tubular member 57 is automatically retracted into the tubular member 52 raising the uppermost bag as will be described.

As is indicated in FIGURE 5 of the drawings, a pair of forwardly and rearwardly extending

supports

112 and 113 extend between the top frame members 14 and 15 and support the

brackets

77 and 78 and a pair of

parallel brackets

114 and 115.

Brackets

116 and 117 extend downwardly from the

brackets

114 and 115. The

brackets

116 and 117, as indicated in FIGURE 10 of the drawings, support opposed inwardly extending

arms

119 and 120 which support fixed clamping

members

121 and 122. The fixed

clamping members

121 and 122 provide abutment against which the opposite outer sides of the bag B are clamped during the filling operation.

The bag clamping apparatus is perhaps best illustrated in FIGURES l0 and 11 of the drawings. As'indicated in FIGURE ll, a filling hopper 123 is supported above the bag B when the bag is in elevated position. A pair of clamping

plates

124 and 125 are pivotally supported upon

shaft

126 and 127 on opposite sides of the hopper 123, the clamping plates being attached to the

shafts

126 and 127 in order to move in conjunction therewith. FIGURE 11 of the drawings indicate the bag B in partially raised position, the bags being moved in the direction of the arrow 129. When the bag is in fully elevated position, it engages between the friction surfaces 130 and 131 of the

member

119 and 120 and is held in this position by the outward swing of the clamping

plates

124 and 125. In order to accomplish the desired result, the mechanism indicated in FIGURE 10 of the drawings is provided, the

clamping blades

124 and 125 being indicated in dotted outline in this figure. A pair of crank arms 132 and 133 are mounted upon the

parallel shafts

127 and 126 and rotate in unison therewith. A hydraulic piston cylinder unit 134 is mounted between the arms 132 and 133. The piston-cylinder unit 134 includes a cylinder 135 having a fixed arm 136 on one end thereof pivotally connected at 137 to the arm 132. A piston 139 in the cylinder 135 is connected to a piston rod 140 which is pivotally connected at 141 to the arm 133. As is obvious, movement of the piston 139 to the right in the cylinder 135 will rotate the shaft 126 in a counter-clockwise direction, and rotate the shaft 127 in a clockwise position, acting to clamp the walls 142 and 143 of the bag B against the fixed

abutments

121 and 122.

In order to insure uniform movement of the arms 132 and 133, a pair of

gears

144 and 145 are mounted upon

parallel pivots

146 and 147. Crank

arms

150 and 151 are mounted upon the

pivots

146 and 147 to rotate in unison therewith.

Links

152 and 153 are pivotally connected at 154 and 155 respectively to the ends of the

crank arms

150 and 151, and are pivotally connected at their other ends as indicated in 156 and 157 to the crank arms 132 and 133. The crank arm 132 is parallel to the crank arm 150, and the crank arm 133 is parallel to the crank 151. As a result, upon actuation of the piston 139 in the cylinder 135, the clamping

plates

124 and 125 are pivoted uniformly against the

abutments

130 and 131 in order to clamp the bag in an open position.

The pneumatic system for operating the apparatus is best illustrated in FIGURE 18 of the drawings. The letter F designates a pressure conduit leading from a source of air under pressure. The letter V indicates connections to a source of partial vacuum.

The pressure conduit P is connected to a limit switch 160 which is normally open. Air under pressure may flow through the conduit 161, the check valve 162 and conduit 163 to the lower end of the cylinder 43 to raise the piston 44. The limit switch 160 is provided with a plunger or feeler 164 which rests upon the surface of the uppermost bag B on the platform 36. When the bags B are at the desired elevation, the plunger or feeler 164 is raised, closing the conduit to the cylinder 43 and preventing further raising of the platform 36 until the level of the bags B lowers to the point wherefurther elevation is required.

An exhaust valve 165 is provided in an exhaust line 166 connected to the lower end of the cylinder 43. When it is desired to lower the platform 3-6 in order to place additional bags on the platform, the manually operable plunger 167 may be lowered to connect the conduit 166 to atmosphere, thereby allowing the piston 44 and its piston rod 45 to drop to the lowermost position.

The pressure line P also extends to an air switch 170 which is normally closed but which may be held by suitable means not illustrated in the drawings in an open position. From the air switch 170, the air may flow through conduits 171 and 172 to

valves

173 and 174 controlling the flow of vacuum through the bag pickup arm unit 31 and to the bag opening unit which may be indicated in general by the numeral 175. When the manually operable valve 170 is in closed position, the bag pickup arm 31 and the bag opening arm unit 175 are inoperative. However, when the air switch 170 is open, the valve elements 176 and 177 are moved into position to subject the interiors of the

cylinders

52 and 93 respectively to partial vacuum from the vacuum line V. The letter M indicates conduits or openings which extend to atmosphere.

The pressure conduit P is also connected by a conduit 181 to an air switch 182 controlled by a member 183 which is operated by the relative movement of the

telescoping members

52 and 57. When the

members

52 and 57 have elongated sufliciently to engage the uppermost bag B on the platform 36, the member 183 opens the valve 182 to direct the flow of air through the conduit 184 to a valve 185. The valve 185 normally directs air through a conduit 186 to the upper end of the cylinder 70, holding this cylinder in a retracted position. However, when air is introduced into the valve 185 through the conduit 184, the piston 187 is moved to the left as viewed in FIGURE 18, connecting the air conduit P with the conduit 189 leading to the lower end of the cylinder 70, and acting to raise the piston 170. This action acts to rotate the

arms

31 and 175 through a pre-determined angular distance.

Most of the elements of the apparatus are controlled by rotation of the shafts from one extreme position to another. The conduit 184 is connected by a conduit 190 to a valve 191 which is normally closed. However, when the arm 31 is swung into the position shown in full lines in FIGURE 1 of the drawings, a cam means 192 act upon the valve plunger 193 opening the conduit 190 to atmosphere, and allowing the valve 185 to return to its original position due to the presence of the operating spring 194.

A valve 195 of the normally closed type is connected by a conduit 196 to the pressure line P. The valve 195 includes a piston 197 having a piston rod 199 controlled by a cam 200 on one of the operating shafts such as the shaft 30. Thus when the

arms

31 and 34 are moved into their extreme upper positions, the cam 200 opens the valve 195 to perform a function which will be described.

The pressure line P is also connected to a valve 201 which normally directs air through a conduit 202 to the end of the cylinder 134 tending to retract the piston 139 in the cylinder. The conduit 203 is normally connected to atmosphere from the opposite end of the cylinder.

When the air switch or valve 195 is actuated to open the valve, a flow of fluid is provided from the conduit 196 through the conduit 205 to the end of the cylinder valve 201 forcing the valve element 206 to the left as viewed in FIGURE 18. When in this position, the air from the conduit P flows through the conduit 203 to the cylinder 135 forcing the piston 139 in the direction to extend the distance between the

pivots

137 and 141. This action causes the clamping

member

124 and 125 to clamp the bag B against the friction surfaces 130 and 131 of the

abutments

121 and 122.

The conduit 205 which leads from the valve 195 to the air controlled valve 201 includes a time delay device 207 which retains the cylinder unit 134 in extended position for a predetermined period of time before releasing the air and permitting the

clamping devices

124 and 125 to release the bag.

As is obvious from FIGURE 5 of the drawings, a conveyor 210 extends beneath the bag supported by the clamping

arms

124 and 125, and the conveyor may act to convey the bag from beneath the clamps after the clamps have been released. The conveyor 210 is of the endless type and is operated by the drive motor 211.

FIGURES 12 through 17 of the drawings show a structure similar to that described in the previous description with the exception of the bag opening arm structure. The arrangement shown in these figures serves the same purpose as the structure previously described. However, this structure permits the apparatus to return to its original or starting position somewhat more quickly than the previous structure, and is illustrated for this purpose.

FIGURE 12 of the drawings discloses a bracket 180 secured to the shaft 33 and supporting an arm 181 secured to the bracket for rotation in connection therewith. The arm 181 supports a pair of spaced brackets 182 and 183, between which is supported a double acting pneumatic cylinder 184. The purpose of this arrangement will be described.

The cylinder 184 includes a piston which operates a piston rod 185. A right angular bracket 186 includes one arm 187 which is slidably supported by the bracket 180, and includes a right angular arm 189 supporting a bracket 190. These

arms

193 and 194 are encircled by vacuum cups 100 of the type which is previously described.

FIGURES 13 through 16 of the drawings are designed to diagrammatically illustrate various positions of the cylinder 184 and the bag pickup mechanism 31 during the operating cycle. FIGURE 13 of the drawings shows the tubular member 57 of the bag pickup unit 31 in extended position and with the suction cups thereupon engaging the uppermost bag of a series of bags B. From the position illustrated in FIGURE 13, the suction within the tubular member 52 will retract the tubular member 57 into the cylinder 52, raising the uppermost bag from the stack.

FIGURE 14 of the drawings shows the bag pickup cylinder 31 swung through an angle of somewhat less than degrees and the piston 185 of the cylinder 184 projected from the cylinder so that the suction cups thereupon are in engagement with the side of the bag B opposite that engaged by the suction cups 100 of the pickup arm 31. When in approximately the position shown in FIGURE 14, the piston within the cylinder 184 is actuated to retract the piston arm 185 into the cylinder 184, thus spreading the sides of the bag B apart to open the bag.

FIGURE 15 of the drawings shows the bag pickup unit 31 and the cylinder 184 in their opposite extreme positions from those shown in FIGURE 13. In this position, the bag B has been spread open and positioned inwardly of the fixed clamping

members

121 and 122. This view also illustrates movable clamping plates 124 and clamping the bag in position.

FIGURE 17 shows a simple hydraulic circuit for operating the piston 195 on the piston rod within the cylinder 184. The pressure line P is connected by a conduit 196 to a normally closed air switch 197 controlling the flow of air through the conduit 199 to pneumatic valve 200. The pressure line P is also connected by a conduit 201 to the valve, and the air under pressure normally flows through a conduit 202 to the cylinder 184 in the direction to retract the piston and the piston arm 185. The opposite end of the cylinder 184 is connected by a conduit 203 to the valve 200 and the upper end of the cylinder is normally subjected to atmosphere. The air switch 197 is actuated by cam means 204 which first opens the air switch to the conduit 199 to move the position of the valve 200 and to direct air under pressure to the upper end of the cylinder 184 as viewed in FIGURE 17, and to connect the lower end of the cylinder to atmospheric pressure. Further movement of the air switch 197 by the cam 204 connects the pressure line 196 to atmosphere, reversing the position of the 9 valve 200 and quickly retracting the piston 195 and piston rod 185 in the cylinder 184.

In accordance with the patent statutes, I have described the principles of construction and operation of my improvement in bag opening machines, and while I have endeavored to set forth the best embodiment thereof I desire to have it understood that changes may be made within the scope of the following claims without departing from the spirit of my invention.

I claim:

1. A bag opening device including:

a filling guide,

a pair of arms pivotally supported on parallel pivots on opposite sides of said filling guide,

means pivoting said arms in unison from a generally vertical position through a generally horizontal position,

means supporting a supply of bags in substantially horizontal position beneath one of said arms when in said vertical position, each of said arms includes an extensible and retractable end portion including suction cups engageable with said bag,

the suction cups of said one arm being engageable with the uppermost bag of said supply when in said substantially vertical position, whereby pivotal movement of said arms will swing the bag engaged into the path of movement of the suction cups on the other of said arms,

means retracting the retractable end portion of said other arm to draw the opposite sides of said bag apart,

said arms moving said bag into position to receive material passing said filling guide.

2. The structure of claim 1 and including means for retracting said retractable end of said one arm upon engagement of said suction cups on said rectractable end with the uppermost bag of said supply.

3. The structure of claim 1 and including means actuated by pivotal movement of said arms into material receiving position for clamping said bag walls in open position.

4. The structure of claim 1 and including fixed clamping members on opposite sides of said bag between which said bag is moved by said arms,

movable clamping means inwardly of said fixed clamping members and extending into said bag when in material receiving position, and

means actuated by movement of said arms into position to move said bag into material receiving position to move said movable clamping means toward said fixed clamping members.

5. The structure described in claim 1 and in which said arms are tubular, and including a source of partial vacuum connected to the interior of said arms and through said .arms to said suction cups.

. 6. The structure of claim 5 and in which said source of partial vacuum causes retraction of the retractable arm ends when said suction cups thereupon are closed by engagement with the bag.

7. The structure of claim 1 and in which said arms are tubular, and includes a source of partial vacuum connected thereto communicating with said suction cups thereon, and in which suction from said partial vacuum source retracts said retractable end of said one arm upon engagement with said uppermost bag.

8. The structure of claim 7 and including a pneumatic cylinder connecting the other said arm to its extensible end, and means for operating said pneumatic cylinder to extend and retract said extensible end.

9. The structure of claim 1 and in which said arms are tubular and including a source of partial vacuum connected to said arms and communicating with said suction cups and including means actuated by movement of said arms into material receiving position to disconnect said source of partial vacuum from said arms.

10. The structure of claim 9 and including clamping means engageable with opposite sides of said open bag in material receiving position, and means operable by movement of said arms to actuate said clamping means to clamp the bag.

References Cited UNITED STATES PATENTS 3,208,194 9/1965 Johnson et a1. 53-190 2,814,488 11/1957 Kipers 53-386 X 3,430,409 3/1969 Manfredonia et al. 53-190 X 3,169,354 2/1965 Bliss et al. 5361 TRAVIS S. MCGEHEE, Primary Examiner H. M. CULVER, Assistant Examiner US. Cl. X.R, 533 86