Method And Machine For Forming Flat Bottom Bags Having Side Gussets

Abstract

The machine first makes a strip of side gusset bags having two inwardly tucked panels forming each of the side gussets, the bags being interconnected with each other by cross-seals. A transfer splitter receives each leading bag at a pick off station prior to and during severing of the bag from the strip. The transfer splitter is operable to swing the severed bag into an upright position while keeping the gusset panels separated from each other. Grippers carried by a conveyor receive the bag from the transfer splitter and clamp the bag for step-by-step movement with the conveyor while keeping the panels separated from each other so as to permit subsequent expansion of the gussets to open the bag as it remains clamped to the conveyor. The lower end portion of the bag is folded upwardly and sealed to the one side of the bag to complete formation of the bag prior to the bag being opened and filled with a charge of product.

Description

BACKGROUND OF THE INVENTION

This invention relates to a method and a machine for forming bags from a continuous web of flexible material and for filling each of the bags with a product. More particularly, the invention relates to the manner in which the bags are transported as they are formed, opened, filled and closed. Herein, the web is formed into a continuous flat tube or strip having horizontal sides and inwardly tucked opposite edge portions, each of the edge portions including two facing panels which define an expandable gusset. Longitudinally spaced cross-seals are formed across the tube so the tube defines a strip of interconnected bags. The bags are severed from the leading end portion of the strip by a cutter which slices through the strip adjacent the trailing edge of each cross-seal so one end of the newly formed bag is unsealed.

Thereafter, the bags are turned into upright positions with the unsealed ends facing upwardly and then the bags are advanced in spaced relation through a filling station to receive a measured charge of product. Before being filled, the body of each bag is expanded so as to unfold the side gussets and open the bag to receive the product charge. After being filled, the bags are sealed closed along their upper margins.

A machine of this general character is shown in our prior U.S. Pat. No. 3,545,166 entitled Method and Machine for Forming and Filling Bags.

SUMMARY OF THE INVENTION

The primary object of the present invention is to provide a new and improved machine of the above general type which is adapted to operate in a novel manner to form flat bottom side gusset bags of the type in which a lower margin of each bag is folded upwardly and sealed to one side thereof before the bag is opened to be filled. A more detailed object is to adapt the foregoing machine in a manner such that the bags are partially formed in a bag making section of the machine while moving along a predetermined path and thereafter are transferred to a conveyor for movement along a continuation of the path through a filling station, the formation of the bottoms of the bags being completed while being advanced by the conveyor and before the bags are opened to receive the measured charge of product.

A further object is to construct the machine so the two panels forming each of the side gussets are kept separated from each other as the bags are transferred from the bag making section of the machine to the conveyor.

A still further object is to hold the bags in their upright positions on the conveyor so that, without releasing the bags from the conveyor, the formation of the bottoms of the bags may be completed and thereafter the side gussets may be expanded to open the bags for filling.

Another detailed object of the present invention resides in the provision of a second conveyor adapted to receive the filled bags from the first conveyor and to transport the filled bags through successive stations where the upper margins of the bags are folded together and sealed closed to complete the packaging operation.

The invention also resides in the provision of a unique transfer splitter operable to move back and forth between a pick off station adjacent the downstream side of the cutter and one end of the first conveyor to swing the bags from their horizontal positions into their upright positions while keeping the adjacent gusset panels separated from each other. The invention is further characterized by the provision of unique grippers which are carried by the first conveyor and are operable to grasp the bags for movement therewith without holding the gusset side panels together so the gussets may be expanded to open the bags without releasing the grippers.

These and other objects and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a is a schematic perspective view of the bag forming portion of a machine embodying the novel features of the present invention.

FIG. 1b is a continuation of FIG. 1a and is a schematic view of the bag-filling and bag-closing portion of the machine.

FIG. 2 is a perspective view of a bag after being formed, filled and closed by the machine.

FIG. 3 is an enlarged cross-sectional view taken substantially along line 3--3 of FIG. 1a.

FIG. 4 is an enlarged cross-sectional view taken substantially along line 4--4 of FIG. 1a.

FIG. 5 is a fragmentary perspective view of a partially formed bag made by the machine.

FIG. 6 is an enlarged fragmentary perspective view of a transfer splitter for transporting partially formed bags from horizontal to upright positions.

FIG. 7 is a fragmentary perspective view similar to FIG. 6, but showing parts of the machine in moved positions.

FIG. 8 is an enlarged cross-sectional view taken substantially along 8--8 of FIG. 7.

FIG. 9 is an enlarged fragmentary perspective view showing parts of a flying splitter for guiding the partially formed bags onto the transfer splitter.

FIG. 10 is an enlarged fragmentary perspective view schematically showing parts of the machine for completing the formation of the bottoms of the bags prior to the bags being completely opened.

FIG. 11 is an enlarged fragmentary cross-sectional view taken substantially along line 11--11 of FIG. 10.

FIG. 12 is an enlarged schematic perspective view showing the bag-opening, the bag-filling and the bag-closing stations of the machine.

FIG. 13 is an enlarged fragmentary cross-sectional view taken substantially along line 13--13 of FIG. 12.

FIG. 14 is a view similar to FIG. 13, but showing parts in moved positions.

FIG. 15 is an enlarged schematic view showing the bag-closing and bag-sealing stations of the machine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in the drawings for purposes of illustration, the present invention is embodied in a machine 20 particularly adapted for forming, filling and closing side gusset bags 21 having flat bottoms 22. As shown in FIGS. 2 and 3, each bag comprises two opposing face-to-face sides 26 and 27 joined together along their two side margins by gussets 33 and along their bottom margins by a lower seal 51. The upper margins 163 of the sides are sealed together to close the bag. In each completed, filled and closed bag, the gussets are expanded and triangular portions 170 (FIG. 15) of the top margins of each gusset and similar portions (not shown) of the bottom margins of each gusset are disposed inwardly to shape the bag as a block. More particularly, the lower seal 51 extends across the bottom 22 of the bag between the gussets and each gusset is defined by two adjacent side panels 42 joined together along a fold line 28.

Basically, the machine 20 comprises a bag-making section 32 (FIG. 1a) with which the bags 21 are formed from a flexible web 24 of heat sealable material such as foil, plastic or paper as the web is advanced in a horizontal direction along a predetermined path. Downstream from and disposed end-to-end with the bag making section is a bag-fill section 38 (FIG. 1b) to which the newly formed bags are transferred for filling and closing during advancement along an extension of the path.

In the bag-making section 32, the web 24 which is heat sealable along one side thereof is formed into a continuous strip 23 of interconnected bags. To form the strip of bags, the web is advanced intermittently past and is folded around a tube former 25 to bring the opposite edge portions of the web into overlapping relation to form the opposing sides 26 and 27, the latter side being interrupted by a longitudinal seam 29 defined by the overlapped edge portions of the web. As shown in FIG. 1a, the tube former includes a forming wheel 30 under which the web feeds so opposite edge portions of the web are dished upwardly. Upon leaving the wheel, the web passes beneath and alongside a forming plate 31, the dished edge portions being folded gradually around the plate and into an overlapping relation to form the web into a flat tube with the seam 29 facing upwardly.

To form the tube with the side gussets 33, the opposite edge portions of the tube are tucked inwardly in a V-shape as shown in FIG. 3. For this latter purpose, the forming plate 31 comprises a narrow center section 34 sandwiched between upper and lower sections 35 which are sider than the center section so as to define elongated grooves 36 extending alog opposite side edges of the plate. The upstream end of the plate is supported by a leg 37 (FIG. 1a) secured to the upper section 35 while the downstream end of the plate is supported by two rollers 39 which are disposed on opposite sides of the plate and extend laterally of the tube. As the web 24 is advanced beneath the forming plate, its longitudinal edge portions are tucked into the grooves by elongated stationary splitters 40 projecting inwardly into the grooves between the upper and lower plate sections, each of the side gussets 33 thus being formed with the panels 42 facing each other. Above the splitters are four forming disks 41 which exert frictional forces on the web tending to wrap the same gradually around the top of the plate. Pressing fingers 43 are disposed between the pairs of disks and overlie and hold the web as it passes between the disks.

Downstream of the disks 41, an electrically heated sealing bar 44 (see FIGS. 1a and 3) is brought downwardly into engagement with the upper side 27 of the web or tube 24 along the seam 29 to seal together the overlapping edge portions. After the seam has been heat-sealed and the tube has been advanced through one step, the newly formed seal is hardened by a cooling bar 45 which is maintained at a low temperature. Herein, both the sealing bar and the cooling bar are moved up and down to engage and release the tube by pneumatic actuators 46 and 47 which are controlled in timed relation with the advance of the tube.

In a similar manner, a heated cross-sealing bar 49 and a lateral cooling bar 50 located downstream of the plate 31 are actuated to pinch the opposite sides 26 and 27 of the tube 24 together to form spaced cross-seals 51 (see FIGS. 1 and 5). In this way, the tube is formed into the strip 23 of interconnected bags 21 which are subsequently severed from each other. At the same time the cross-seal is formed in each bag, the cross-sealing bar also forms a slanted seal 52 between the lower margin of each panel 42 and the adjacent side 26 or 27 of the bag, each slanted seal extending upwardly and outwardly from the lower end of the fold line 28 to the edge between the panel and the side of the bag. The space between the two slanted seals on each gusset 33 defines the triangular portion which is to be disposed inwardly on the bottom margin of the gusset. In addition to cooling the hot cross-seal and slanted seals in each bag, the cooling bar 50 also forms a crease 53 (FIG. 5) in the tube along the upstream edge of the cross-seal when advanced against the bag so as to later facilitate folding of the bottom margin upwardly along the side 27 of the bag.

Downstream of the cooling bar 50, mechanism in the form of two horizontal drive rollers 54 (FIG. 1a) frictionally engages the opposite sides 26 and 27 of the bags to advance the strip 23. The rollers are rotated intermittently through precisely controlled angular distances to feed the strip through steps exactly equal in length to the length of the bags. Herein, the rollers are connected to a motor 55 by a power train 56 operable to drive the rollers intermittently in response to measured movement of the strip of bags as detected by a photoelectric scanner 57 supported above the bags.

A cutter 63 (FIG. 1a) in the cutting station 60 severs the leading bag 21 in the strip 23 from the other bags by cutting the strip alongside and just behind the trailing edge of each cross-seal 51 so one end of the bag is sealed by the cross-seal and the other end of the bag is unsealed. Each bag, after being cut from the strip, is turned into an upright position so the sealed end of the bag forms a lower margin 64 (see FIG. 7) and the unsealed end of the bag faces upwardly. Thereafter, a conveyor 65 advances the upright bag in an edgewise direction step-by-step through a filling station 66 (see FIG. 1b). In this instance, the conveyor includes an endless chain 67 traveling in a horizontal plane and trained around sprockets 69 and 70, the sprocket 69 being positioned adjacent and below the pick off station 61 such that one of the curved end runs of the chain is spaced downstream of and beneath the horizontally disposed bags cut from the strip 23 at the cutting station 60. A Geneva mechanism 71 coupled to the sprocket 70 is driven by a cycle shaft 72 and is timed to advance the chain intermittently at approximately the same time the drive rollers 54 are advancing the strip so both the chain and the drive rollers dwell during the same intervals.

In accordance with the primary aspect of the present invention, the machine 20 is adapted to operate in a novel manner so as to complete formation of each of the bags 21 by folding the lower margin 64 of the bag upwardly and sealing the margin to the side 27 of the bag as the latter is advanced along the fill section 38 of the machine but before the bag is opened to be filled. For this purpose, a unique transfer splitter 73 (FIG. 1b) swings each of the partially formed bags from the pick off station 61 of the bag making section 32 into an upright position of the conveyor 65 for grippers 74 to clamp the bags for movement with the conveyor. Advantageously, the transfer splitter keeps the two facing panels 42 in each gusset 33 separated from each other as the bag is swung from the pick off station to the conveyor so the grippers can clamp the bag along its edges to permit the lower margin of the bag to be folded upwardly and sealed to the side of the bag while still keeping the two panels in each gusset separated from each other. This permits subsequent expansion of the gussets to open the bag for receiving the product charge as the bag remains clamped to the conveyor. Thus, with this arrangement, the machine 20 is adapted for use in forming flat-bottom bags by completing formation of the bottom 22 of the bag after the latter is transferred from the bag making section of the machine.

In the present instance, the transfer splitter 73 is swung from the pick off station 61 to carry each bag 21 to the conveyor 65 during the dwell period and includes spaced parallel blades 75 (see FIGS. 6 and 7) supported on pivot arms 76 by links 77. The blades fit between the gusset panels 42 along opposite edges of the bag, and suction cups 79 help hold the bag on the blades as the splitter swings toward the conveyor. Herein, a flying splitter 80 guides the end bag of the strip 23 from the downstream ends of the stationary splitters 40, through the cutting station 60 and into the pick off station. Upon reaching the pick off station, the flying splitter abuts the transfer splitter 73 (see FIG. 9) so that, as the strip advances further into the pick off station, the panels 42 slide telescopically onto the blades so the latter keep the panels separated from each other.

Prior to severing the end bag 21 from the strip 23, the flying splitter 80 is retracted relative to the strip, back upstream of the cutter 63 and into position to guide the next bag into the pick off station 61 during the next advance of the strip. Herein, the flying splitter is reciprocated by a fluid-actuated cylinder 81 with each advance step of the strip and includes a split upstream end portion 83 (see FIG. 9) sandwiched over a portion 84 of the stationary splitter 40 to guide the flying splitter as it moves back and forth through the cutting station 60.

To swing the bag 21 into its upright position, the arms 76 of the transfer splitter 73 are supported on a horizontal rock shaft 85 (FIG. 6). The latter is connected through linkage 86 to a follower 87 (FIG. 1b) which engages a cam 89 on the cycle shaft 72. Accordingly, during the dwell period, the shaft 85 is pivoted first in a counterclockwise direction (FIG. 6) to swing the blades 75 and the bag into vertical positions at the end of the conveyor 65 and then, after the bag is clamped for movement with the conveyor, the blades are swung clockwise (FIG. 7) back to the pick off station to receive the next bag.

As the bag 21 reaches its vertical position, the grippers 74 (see FIGS. 7 and 8) grasp the bag along the opposite edges thereof to hold the bag for movement with the conveyor 65. Herein, the grippers are pivotally supported on a yoke 90 (FIG. 7) attached to one of the links 91 of the conveyor chain 67 and normally are biased closed by springs 93. As shown in FIG. 8, each gripper includes a generally V-shaped bellcrank 94, one end of which forms a jaw 95 which coacts with the yoke to grip the bag. Herein, the jaws extend through notches 96 in the blades 75 so that only one panel 42 is clamped between the jaw and the yoke along each edge of the bag. To open the jaws to receive the bag, a follower 97 on the other end of the bellcrank 94 is engaged by a cam 99 which, when advanced toward the follower by an actuating linkage 100 (FIG. 1b), overcomes the springs to pivot the jaws open to receive the bag. In the exemplary embodiment, the actuating linkage is moved back and forth by a face cam 101 mounted on the cycle shaft 72.

After the grippers 74 grasp the bag 21 for movement with the conveyor 65, the splitter 73 is swung back to the pick off station 61. Thereafter, the conveyor is advanced to cause the lower margin 64 of the bag to ride over a folding bar 103 (FIG. 10) and to be folded upwardly along the crease 53 and into a substantially horizontal position as the bag is advanced into a gluing station 104. At the gluing station, applicator nozzles 105 spray hot-melt adhesive in a strip 106 across the bag and above the crease so the lower margin can be glued to the side 27 of the bag. As the bag is moved out of the gluing station, the bar 103 folds the lower margin upwardly so as to parallel the side of the bag preparatory to entering a sealing station 107. In the sealing station, jaws 109 and 110 of a pressing mechanism 111 are closed by an actuator 113 (see FIG. 11) and squeeze folded margin against the side of the bag so the adhesive seals the margin to the side of the bag so as to complete the formation of the bottom of the bag prior to opening the latter.

Once the bottom of the bag 21 has been formed, the conveyor 65 advances the bag into an opening station 114 where, during the dwell period, an opener 115 (FIGS. 12 and 13) is telescoped downwardly into the bag and is actuated to expand the gussets 33 to open the bag. Herein, the bag opener includes two plates 116 pivotally mounted on opposite sides of a support 117. Intermediate their ends, the plates are bent toward each other (see FIG. 13) to permit easy entry of the plates into the bag as the support is advanced downwardly from a retracted position above the bag by a fluid-operated cylinder 119. The support is carried slidably on the end of a rod 120 projecting downwardly from the cylinder and is located between upper and lower stops 121 and 123 secured to the lower end portion of the rod. A spring 124 acting between the upper stop 121 and the support urges the latter downwardly into engagement with the lower stop 123. Also connected to the lower end of the rod are two sets of curved arms 125 (see FIG. 12) whose lower ends are pivotally fastened to the plates, one set of the arms being fastened to one of the plates adjacent the bend in that plate and the other set of arms being fastened in a like manner to the other plate. Slots 126 (FIG. 13) in the upper ends of the arms receive a pin 127 which secures the arms to the lower end of the rod so that, as the rod slides downwardly relative to the support, the pin slides in the slots and causes the lower ends of the arms to spread the plates away from each other to expand the side gussets of the bag (see FIG. 14). The distance which the arms can pivot away from each other is limited by the support 117 as it compresses the spring 124 against the upper stop 121.

To limit downward movement of the support 117 so the downwardly moving rod 120 may overcome the spring 124 and slide downwardly relative to the support to spread the arms 125, two vertical guide bars 129 (FIG. 12) on opposite sides of the rod 120 are fixed at their lower ends to the support 117 and are bushed slidably by a fixed bracket 130 which also supports the cylinder 119. Threaded on the upper ends of the bars are stop nuts 131 which, when the support is pushed downwardly by the rod, engage the upper surface of the bracket to prevent further downward movement of the support. At this point, the rod overtravels to spread the arms and plates 116 (see FIG. 14) and thereby to open the bag 21. As the gussets 33 are expanded in this manner, a horizontal kicker plate 134 (FIGS. 1b and 14) strikes the bottom of the bag to help square the bag before the latter is advanced out of the bag opening station 114. The plate 134 is carried on the end of a rod 135 adapted to be reciprocated upwardly and downwardly by a cam 136 on the cycle shaft 72.

As the open bag 21 is advanced out of the bag opening station 114 by the conveyor 65, a U-shaped holder 137 (FIG. 12) carried on a chain 139 of another conveyor 140 swings upwardly along each of the gussets 33 to advance the bag along its predetermined path to be filled and subsequently closed. The second conveyor is advanced step-by-step in timed relation with the first conveyor through suitable mechanism (not shown) and includes one end sprocket 141 (see FIG. 1b) spaced between the sprockets 69 and 70 of the first conveyor and an opposite end sprocket (not shown). The chain 139 is trained around the two sprockets of the second conveyor and carries a bracket 143 (FIG. 12) to which the holder is secured for pivotal movement between a downwardly opening vertical position and a horizontally opening position disposed around the bag. The holder is urged into its normal horizontal position by a spring 144 (FIG. 13) acting between the bracket and the holder but, in the bag opening station 114, the holder is held downwardly in its vertical position by a retaining bar 145 (FIG. 12). The latter is positioned such that, in the bag opening station, the holder is tilted slightly upwardly along the gussets 33 and, as the bag leaves the opening station, the holder passes by the end of the bar to swing upwardly along the bag under the urging of the spring. At this point, the grippers 74 are still clamping the bag 21 on the first conveyor 65 and thus retain the bag within the holder 137 as the two conveyors 65 and 140 advance the bag into the filling station 66. Upon being advanced out of the bag opening station 114, the bag is slid onto two driven belts 146 which are separated from each other and which keep the bag from falling downwardly out of the holder during subsequent advance of the bag. The belts are trained around a pulley 147 and advanced in timed relation with the second conveyor to avoid relative sliding between the belts and the bottom 22 of the bag.

In the filling station 66 (FIG. 12), the bag 21 is gripped by a suction device 149 which pulls outwardly on the front side 27 of the bag as the grippers 74 captivate the bag in the holder 137. Then, a charge of product is fed into the bag from a dispenser 150. To help the product settle within the bag, a kicker platform 151 is mounted beneath the two belts 146 and is jogged upwardly against the belts by a cam 153 (FIG. 1b) mounted on the cycle shaft 72.

As the bag 21 is advanced from the filling station 66 by the two conveyors 65 and 140, the followers 97 on the grippers 74 of the first conveyor 65 engage a stationary cam 154 (FIG. 12) mounted above the end sprocket 70 and are opened so the grippers release the bag. The latter is then carried solely by the second conveyor 140 and the belts 146 and is advanced step-by-step through closing, sealing and flattening stations 155, 156 and 157 (FIGS. 16, 12 and 15). In the closing station 155, pivoted L-shaped gusset tuckers 159 (FIG. 12) engage the two side gussets 33 between each of the two panels 42 adjacent the top of the bag and tuck the gussets toward each other to assure that the bag will close properly. After the gussets have been tucked inwardly, closing bars 160 are advanced by a cam 161 (FIG. 1b) to engage the opposite sides 26 and 27 of the bag along the upper margins 163 thereof and crimp the bag closed. As this is done, a second kicker platform 164 is jogged upwardly from beneath the two belts 146 by a cam 165 and helps to settle the product within the bag.

The bag 21 then is advanced from the closing station 155 with the upper margin 163 being sandwiched between two parallel guide bars 166 (FIGS. 12 and 15) to keep the upper end of the bag from expanding open as the bag is carried into the sealing station 156 by the second conveyor 140. In the sealing station, two sealing bars 167 are advanced to seal the top margins of the two side panels 26 and 27 together to close the bag. As the bars are sealing the sides together, squaring arms 169 (FIG. 15) adjacent each end of the top seal being formed are swung toward each other to expand the upper portion of each gusset 33 while also tucking the triangular portion 170 at the upper end of each gusset inwardly beneath the margins to help square the top of the bag. As the arms reach the ends of their inward swinging, a jogging platform 171 beneath the sealing station is lifted into engagement with the belts 146 to push the bag upwardly so the top portion of the bag is pressed against the sealing bars and the arms to square the top of the bag. Thereafter, the arms, the jogging platform and the sealing bars are retracted away from the bag and the latter is advanced to the flattening station 157 to fold the upper margins, now forming a top seal 163, downwardly onto the top of the bag as is shown in FIG. 15. The bag subsequently is removed from the machine for placement into shipping cartons.

From the foregoing, it will be apparent that the machine 20 of the present invention is adapted to operate in a novel manner so as to utilize the bag making section 32 in the formation of the flat-bottom side gusset bags 21. To this end, the bottoms 22 of the bags are completed by folding the lower margins 64 of the bags upwardly along the sides 27 of the bags as the latter are advanced along the fill section 38 of the machine but before the bags are opened to be filled. By utilizing the novel transfer splitter 73 to keep the gusset panels 42 separated from each other as the bags are carried from the pick off station 61 to the conveyor 65, the grippers 74 may be actuated to clamp the bags for movement with the conveyor without clamping the gussets closed. Advantageously, this enables the bottoms of the bags to be completed along the fill section of the machine while still permitting the bags to be opened subsequently for filling without need of unclamping the bags from the conveyor.

Claims

We claim as our invention:

1. A method of forming flat bottom, side gusset bags from a strip of interconnected bags, said strip having cross-seals connecting said bags together and having side gussets along opposite margins and each defined by two inwardly tucked panels which face one another, said method comprising the steps of, advancing said strip along a predetermined path, guiding the leading bag in said strip into a pick off station, separating the two panels of each of the gussets from each other as the bag is moved into said station, severing the leading bag from said strip adjacent said station along the edge of one of said cross-seals to leave the severed bag with one end closed by one of said cross-seals and with the other end unsealed, swinging said severed bag from said pick off station onto a conveyor, keeping each of the two panels separated from each other as said bag is swung from said pick off station onto said conveyor, clamping said bag on said conveyor, maintaining each of said two panels separated from each other as said bag is clamped to said conveyor so as to permit subsequent expansion of said gussets to open said bag as the latter remains clamped to the conveyor, advancing said conveyor to carry said bag along a continuation of said path, folding a portion of the sealed end of the bag along one side of the bag while the bag is clamped to said conveyor, and sealing said portion against the side of the bag to complete formation of the sealed end of the bag prior to opening and filling of the bag.

2. A method of forming side gusset bags from a strip of interconnected bags, said strip having cross-seals connecting said bags together and having side gussets along opposite margins and each defined by two inwardly tucked panels which face one another, said method comprising the steps of, advancing said strip step-by-step along a horizontal path with the bags disposed in horizontal positions, guiding the leading bag in said strip into a pick off station, separating the two panels of each of the gussets from each other as the bag is moved into said station, severing the leading bag from said strip adjacent said pick off station along the edge of one of said cross-seals to leave the severed bag with one end closed by one of said cross-seals and with the other end unsealed, swinging said severed bag from said pick off station into an upright position on a conveyor while keeping each of the two panels separated from each other, gripping only one of the panels in each gusset to clamp the bag on the conveyor while still keeping the two panels in each gusset separated from each other to permit subsequent expansion of said gussets to open said bag as the latter remains clamped to the conveyor, advancing said conveyor step-by-step to carry said bag along a horizontal path with the bag in an upright position, applying adhesive across the bag adjacent the sealed end thereof, folding a portion of the sealed end of the bag upwardly along one side of the bag, and pressing said folded portion against the side of the bag to cause the adhesive to seal the folded portion to the side of the bag to complete formation of the bag prior to opening and filling of the bag.

3. A method of forming side gusset bags as defined by claim 2 further including the steps of opening each bag after completing the formation of the bottom of the bag, squaring the bottom of the bag as the latter is opened, and filling the bag with a product.

4. A method of forming side gusset bags as defined by claim 3 further including the steps of transferring the bag onto a second conveyor, holding the bag for movement with said second conveyor, unclamping said bag from said first conveyor after filling the bag, advancing said second conveyor in timed relation with said first conveyor, tucking the gussets toward each other adjacent the top of said bag, and sealing together the upper end portion of the opposite sides of said bag to close the bag.

5. A machine for forming side gusset bags from a strip of interconnected bags, said strip having cross-seals connecting said bags together and having side gussets along opposite margins and each defined by two inwardly tucked panels which face one another, said machine including means for advancing said strip step-by-step along a predetermined path into a pick off station, a splitter sandwiched between the two facing panels of each gusset and operable to keep the panels separated as the leading bag is advanced into the pick off station, a cutter adjacent said pick off station and operable to sever the leading bag from said strip along one edge of one of said cross-seals to leave the severed bag with one end closed by one of said cross-seals and with the other end unsealed, a transfer splitter receiving said leading bag at said pick off station prior to cutting of the bag, said transfer splitter being sandwiched between the two facing panels of each gusset and being movable from said pick off station to swing the severed bag into an upright position while keeping each of the two panels separated from each other, a conveyor having one end located adjacent said pick off station and operable to move said bag step-by-step along a continuation of said path in timed relation with the advancement of said strip, grippers carried by said conveyor and operable to clamp said bag in its upright position for movement with said conveyor, said grippers keeping each of said two panels separated from each other so as to permit subsequent expansion of said gussets to open said bag as the latter remains clamped to said conveyor, means for folding a portion of the sealed end of said bag upwardly against one side of the bag, and means for sealing said folded portion to the side of the bag to complete formation of the bag prior to opening and filling of the bag.

6. A machine as defined by claim 5 further including means for applying adhesive across said bag adjacent the sealed end thereof prior to folding said portion of the sealed end against the side of the bag.

7. A machine as defined by claim 6 wherein said conveyor advances said bag through an opening station and a filling station, a bag opener located at said opening station, adapted to open said bag and to square the bottom of the bag, a dispenser located at said filling station and operable to deposit a charge of product into said bag, and a second conveyor operable in timed relation with said first conveyor for receiving said bag from said first conveyor and holding said bag for advancement along a further continuation of said path to be sealed closed.