MXPA99008901A - Continuous roll of plastic bags - Google Patents

Abstract

A continuous web of bags formed of a plurality of layers to be separated along a line of perforations that extends through all of the layers transverse of the web, in which at least one of the outermost layers is detached from the web at the separation line. Apparatus accomplishes this detachment in a moving web by engaging the outermost layer outer surface and exerting a force in a manner to produce the detachment from the separation line. Both the outermost upper and lower web layers can be detached at the separation line.

Description

CONTINUOUS ROLL OF PLASTIC BAGS FIELD OF THE INVENTION The present invention is concerned with plastic bags or plastic bags and more particularly with a roll of plastic bags where the bags are partially opened as they are stocked.

BACKGROUND OF THE INVENTION In a supermarket or food market, fresh agricultural products are often displayed in bulk, often in piles or loose items. Consumers should take a bag from a nearby source and then select and pack their own fruits and vegetables.

Normally, the bag source consists of a cylindrical roll positioned vertically or horizontally of plastic bags of multiple flat folds provided in continuous strips. One type of bag used in a roll is the bag PULL-N-PAK®. This comprises a flat tube of plastic material in which the bags are fully reinforced on each side and folded longitudinally to form a configuration of eight folds sealed in star. The bags have a seam for the bottom of the bag and there is a line of separation of corporations adjacent to the seam or union of each bag. The separation line REF .: 31366 comprises multiple perforations that extend through all eight layers of the bag. A slot or slit is placed in the center of the separation line and extends through all the layers. The roll of bags is placed in a dispenser, for example of the type shown in US Pat. No. 5,558,262. The user pulls the first bag into a tab of the dispenser that contacts the slot in the separation line. The front of the next bag is trapped in the space between the tongue and a handle behind the tongue and is retained in space. The continuous or prolonged traction of the first bag produces a force separating the first bag from the next remaining bag in the roll in the separation line. A problem with the bags provided in a continuous strip is that frequently the user finds it difficult to open the bag once it has been removed from the strip. The user may still find it difficult to determine which end of the removed bag is the end that opens. The smooth finish of the walls of the thin film of the bag, the static adhesion of the thin plastic films and the puncture forces applied to the films in order to provide the separation lines can cause the folds in the opening The bag will resist separation, in which case a user may need both hands to open the bag. This can be annoying when the consumer has already selected their products and holds them to be placed in the bag. An object of the present invention is to provide plastic bags which, when dispensed in continuous strips, can be opened more easily than prior bags. A further object is to provide a bag for agricultural products that is provided to the user in a partially open state. A further object of the invention is to provide a continuous strip of bags for agricultural products in a roll such that when removing a front bag from the roll the opening end of an adjacent successive bag in the roll is easily identified. A further object of the invention is to provide a method and apparatus for processing a multi-pleated mobile bag belt to separate a layer from each bag along a separation line to provide a roll of plastic bags that are easily opened afterwards. of his separation from the roll.

BRIEF DESCRIPTION OF THE INVENTION In accordance with the invention, a roll of plastic bags having multiple layers includes at least one outer layer separated in the separation line from the adjacent bags. In a preferred embodiment of the invention, the bags are provided in the form of a belt that is folded in such a way that a longitudinal edge is a fold line. The adjacent bags are separated by a seam line and a separation line. An outer layer of each bag is separated in the line of separation of the adjacent bags. Through the action of pulling a bag, after the slot in the separation line in the remaining layers engages the tongue of a jet, the pulling force is transferred from the bonded layers of the first bag to the joined layer (s) remaining (s) of the next bag in the roll. The upper layer does not transfer any force to the next bag because it is completely separated from the belt in the separation line; likewise, the upper layer of the next bag does not receive any force from the first bag because it is completely separated in the separation line. As a result, after separation of the first bag from the roll, the front part of the next bag is partially opened in the automatic way. It is also possible to separate only the inner layer or the upper layer and the lower layer. In a star-sealed bag (eight layers), when the upper (first) and lower (octave) layers are separated, only six layers are joined. This makes it easier to separate a bag from the roll since only six layers have to be torn and separated along the line of separation. The invention also includes a method and apparatus for separating one or both of the outer layers as a series of bags is fed from one site to another site. To accomplish this, a friction element engages with the outer layer of the belt to be separated downstream from the seam or union between two belt bags as long as the friction element moves at a greater speed than the travel speed of the tape. This separates the layer coupled along the line of separation of the tape. In a belt where the separation line is upstream of the seam or joint, the friction element engages with the outer layer and exerts a pulling force or is moved in a direction opposite to that of the travel of the belt. .

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects of advantages of this invention will become apparent to those skilled in the art upon reading the detailed description of a preferred embodiment, in conjunction with a review of the accompanying drawings in which: Figure 1 is a top view of a portion of a continuous strip of bags showing in detail the lines of separation between the bags. Figure 2 is a cross-sectional view taken along the sectional line 2-2 in Figure 1 showing the multiple folds of a folded bag. Figure 3 is a perspective view of a roll of bags in a continuous strip held in a spout. Figure 4 is a schematic illustration of an apparatus and process for cutting an upper layer of the multilayer bag; Figure 5 is a schematic view showing second embodiments of an apparatus and process for cutting the layer; Figure 6 is a schematic view of a third embodiment and Figure 7 is a schematic view of a fourth embodiment. Figure 8 is a side sectional view of a preferred apparatus used in accordance with the invention taken along line 8-8 of Figure 9. Figure 9 is a front sectional view along the line 9-9. of Figure 8. Figure 10 is a top sectional view along the line 10-10 of Figure 8 and Figure 11 is a side view partially in section of a modified spout to incorporate a friction element to separate the top layer of a multi-pleated ribbon as each individual bag is stocked.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 shows a continuous strip of plastic bags 10 according to a preferred embodiment of the invention. The bags are provided in what is known as a "star-sealed" configuration that is a standard configuration for plastic bags. It is formed by extrusion of a tubular shape, the shape is fully reinforced and then the fully reinforced tubular form is folded to form the eight-fold configuration shown in Figure 2, one of the longitudinal edges 11 comprises the fold. The individual bags are separated by a seam 12 and a separation line 14 which extends through all eight layers of the star-sealed configuration. The seam 12 defines the bottom of a bag and the line of separation 14 the upper part of the adjacent bag. As described in U.S. Patent No. 5,558,262, each of the separation lines 14 includes a central slit or slot 14A that engages the tongue of a dispensing mechanism to allow the user to separate the individual bags. Figure 3 shows in perspective the dispensing mechanism of U.S. Patent No. 5,558,262. The plastic bags are provided in a roll 16 that includes a central axis (not shown in Figure 3) that rests on tracks within the spout 18. The separation tab of the spout mechanism that engages with the slots within the line of separation is shown at 20. U.S. Patent No. 5,558,262 provides a detailed discussion of the construction and operation of the dispensing mechanism in combination with the bag roll and is hereby incorporated by reference. The plastic bag dispensing system described above provides bags in a manner convenient to the consumer. After a first bag has been separated from the roll, the next adjacent bag is in its place where it can be easily held by the user. In addition, the action of stocking and separating a given bag tends to open the bag, but if a user has only one free hand or is physically disabled, it can be difficult to open the bag. When bags made according to the invention are used, the bags are partially opened automatically as they are stocked, which means the goal of fully opening the bag to receive agricultural products or other objects. This is carried out by the simple fact of completely separating one or both of the outer layers, that is the upper or lower layer. In this way, the upper layer (for example) is completely separated from the upper layer of adjacent bags. As a result, as each individual bag is stocked, the adjacent bag remaining in the roll is automatically opened. It is possible to separate the selected layer when the tape is stopped for the sealing and / or perforating steps but it is preferred to separate the selected layer after the sealing and perforation have been presented and while the tape moves continuously. Figure 4 shows a first way to separate an outer layer of each bag from the adjacent bags as the belt travels from one place to another. In Figure 4, the reference number 30 indicates the machine, of conventional construction in which the bag belt is made. The bags exit the machine 30 in a continuous belt 40 in the configuration shown in Figure 1. The seam or union lines 12 are spaced along the length of the belt to define the individual bags. The separation lines 14 extend through all the layers of the belt adjacent to a corresponding seam line or junction 12. A winding or unwinding machine 60 is shown for winding the bag belt of the machine 30 on a roll about an axis 62. The belt moves in the direction of the arrow, from the bag machine 30 to the winding machine 60. As shown, the separation lines 14 are downstream, seen from the exit of the machine 30. of the welding lines 12. Obviously, Figures 4-7 are schematic views showing the belt 40 rotated 90 degrees as it moves beyond the separation mechanism. A detector 68, such as a photoelectric tape, is located above the tape 40. As the tape moves, the detector 68 sequentially detects the individual bags by a separation line 14 or a seam line 12. A carriage or mobile support 70 is located above the tape downstream of the detector. The car or mobile support 70 has a separator in the form of a protrusion 72 with an end 74 of a high friction surface, for example, of rubber (or rubber). The carriage 70 is located above a plate 75 on which the belt 40 passes. A mechanism 77, acts as a lever operated by piston, cam or other similar arrangement, first moves the carriage 70 in such a way that the end 74 of the protrusion can be brought into contact with the upper layer of the tape material and then moves it for a short distance in the direction of movement of the tape but at a speed higher than that of the tape. The carriage 70 is put into operation under the control of the detector 68. In operation, the detector 68 detects the presence of the separation line 14 or the presence of the union or seam 12, between two bags of the moving tape that leaves the machine 30. the carriage 70 is located at a predetermined distance downstream of the detector 68 sufficient to allow the operation of the carriage 70 through a complete cycle. That is, after detection of the separation line 14 or the seam line 12 through the detector 68, the mechanism 77 causes the carriage 70 to move downward to bring the outer protrusion end 74 into contact with the upper layer. of the ribbon at a short distance, for example approximately 1.27 cm (one half inch) apart from the separation line 14 in the downstream direction. Then the carriage 70 and the protrusion 72 are moved in the same direction as the belt travels, but at a higher speed. Due to the friction and the higher speed of the protrusion 72, the upper layer of tape slides from the other layers and is separated or torn along the separation line 14 of the upper layer of the adjacent bag. After making the protrusions 72 move a few centimeters, the carriage mechanism 77 returns the carriage 70 in the upward direction and returns it to its original position to be ready for the next bag to separate from the upper layer. The carriage 70 also has a nozzle 80 that moves with it. The nozzle 80 feeds air that is blown into the enclosure formed by separating the upper layer from the separation line. Part of the air in the nozzle 80 will be trapped between the upper layer and the other layers. A thin layer of air reduces the friction between the top layer and the other layers. This makes opening the bag easier after it is torn off the tape. The bag with the outermost layer that is open away from the tape, as shown at 49, is then wound onto the roll, preferably in such a way that the open layer will be the top layer when the bags are stocked. Figure 5 shows another embodiment of the invention. The same reference numbers are used for similar components. A separator in this case comprises a rubber wheel 90 located above the belt 40 and on the plate 75. The wheel 90 rotates in the same direction as the travel of the belt 40. In response to a signal from the detector 68, a mechanism 92 at the appropriate time causes wheel 90 to come into contact with the upper layer of the belt. The periphery of the wheel 90 moves at a faster speed than the speed of the belt. When the wheel 90 rotates at a peripheral speed greater than that of the speed that the tape separates the outer layer of the tape coupled along the line of separation 14. After the outer layer is separated along the line of separation, the wheel 90 is separated from the tape to wait for the next signal from the detector 68. In an alternative form, the wheel 90 can be put in contact with the tape all the time and roll freely, in such a way that it does not exert any enough frictional force to separate the coupled layer from the separation line. When it is appropriate to separate the upper layer coupled by the wheel from the belt, the wheel can be activated to apply a greater coupling force to the outer layer and rotate at a higher speed. This can be accomplished by an appropriate clutch mechanism. In one form of the Pull-N-Pak® bags, when the roll is rolled, the perforation 14 is behind or upstream of the seam or union opposite to what is shown in Figures 4 and 5. As a result, custom-made that the roll is unrolled in the spout, the portion of the bag that is trapped in the space between the handle and the tongue is the split or open end of the bag. Figure 6 shows a tape 40a of this type and an arrangement for separating the top layer along the perforation line 14. Here, the roll 90 engages with the upper layer of the bag upstream of the welding line 12 The roller 90 is rotated in a direction opposite to the movement of the belt 40 at a slower speed than the movement of the belt. This will produce a pulling force that will tear the top layer of the perforation line 14. Alternatively, there may be a series of hands along a bar that is lowered to engage with the outer layer of the tape and held stationary for exert a drag force to separate the outer layer of the belt along the separation line. The mechanism of Figure 4 can also be used to separate the upper layer of a belt 40a of the type illustrated in Figure 6. The prominent end 74 would mate with the upper layer of the belt upstream of the separation line 14 and would move towards the bag machine 30 to tear the top layer in the separation line 14. When changing the position of the carriage mechanism 70 of the wheel 90 from the top of the belt to the bottom of the belt, the lower layer of the tape can be separated from the separation line. Also, by providing two separation stations, one for the upper layer and one for the lower layer, the upper and lower layer can be separated from the separation line of the belt. In this case one station may be separated from the other, such as by the length of a bag with each other. Figure 7 shows still a further embodiment of the invention. The same reference numbers are used to identify elements that are the same as the elements described in Figures 4, 5 and 6. In Figure 7 a friction wheel 100 is located above the belt 40. An adjustable pressure roller 102 is positioned below the belt 40. The wheel 100 and the pressure roller 102 come into contact with the belt 40 and rotate in the travel direction of the belt. The pressure roller 102 is adjustable in such a way that the friction between the wheel 100 and the roller 102 can be adjusted. The peripheral speed of the pressure roller 102 is equal to the speed of the belt 40. Also, under normal conditions, the peripheral speed of the wheel 100 is the same as the speed of the belt 40. In response to a signal from the detector 68 , an activation mechanism 92 causes the wheel 100 to rotate at a peripheral speed greater than the speed of the belt. When this happens, the outer coupled layer of the tape 40 is separated along the separation tape 14. The mechanism 92 activates the wheel 100 at a precise point in time such that the speed of the wheel 100 will be increased at a point in time at which it is easier to separate the separation line 14. Also, the activation period will be the shortest possible time to allow complete separation of the contacted layer. As soon as the outer layer has been separated, the peripheral speed of the wheel 100 is returned to the speed of the belt 40. Figures 8-10 show an apparatus that can be used to separate either the upper or lower fold the tape as it moves between the bag machine 30 and the winding roller 62. The tape is supplied in the configuration shown in Figures 1 and 2, this is a fully reinforced folded (star-sealed) film forming eight layers or contiguous folds. A longitudinal edge of the tape is formed by a fold and seams or junctions 12 and lines of separation 14 are provided between adjacent bags. Since the tape is wound by conventional elements (not shown) it will be under tension. The apparatus shown in Figures 8-10 is added to the conventional production line. The apparatus includes a box comprising a rear wall 110, natural panels 112 and 114 and a removable center cover 116. The various inactive and pressure wheels described above are mounted on the side panels 112 and 114.

As shown in the film 9, in the preferred embodiment two lines or tapes 40a or 40B pass through the separation mechanism. The operation of both sides of the line is identical. The apparatus includes inactive input rollers 120, 122 and 124, upper pressure rollers 126A, 126B and friction wheels 128A, 128B. The drive of the friction wheels 128A, 128B opens the separation lines 14 in an outer fold of each belt as previously described. The inactive exit rollers 130, 132, 134, the oscillating roller 136 and the inactive roller 137 direct the belts to the winding machine or rewinders (not shown). Either the upper layer or the lower layer of a belt 40A, 40B can be opened by the apparatus shown in Figures 8-10. When the tapes pass between the nip rollers 126A, 126B and the friction wheels 128A, 128B, the lower layers of the tapes are opened. As shown in dashed lines, the tapes can be alternately directed from the idle roller 122 to the friction rollers 138A, 138B, and back to the line beyond the inactive roller 132. In that case, the acceleration of the wheels of friction 128A, 128B (in this case, in a counterclockwise direction) will open the top layer of the bags. It is desirable that the upper layer of the tape be the separate layer when the bags are supplied to the customer; therefore, in most cases, the apparatus of Figs. 8-10 will be used to open the top layer and the rolls will be rolled in the clockwise direction. However, in some cases it may be preferable to roll the rolls in a counter-clockwise direction, in which case the lower layer of the tape would be opened (when using the pressure rollers 126A, 126B and the friction wheels 128A, 128B ) in such a way that the tape is rolled in the counterclockwise direction, with the top layer on top. The structure and operation of the pressure rollers 138A, 138B is the same as that of the rollers 126A, 126B which are described hereinafter. Each of the pressure rollers is mounted on a shaft 140 with bearings 142 (only one is shown) at each end of the respective roller which allows the roller to rotate to accommodate or compensate the speed of the moving belt. Each roller comprises a steel drum 144 having a rubber coating 146 on its outer periphery. The shaft 140 on which the drum 144 rotates is mounted on the free ends of the arms 148 and 150. A pair of sleeves 152A and 152B, which are biased against each other, are rotatably mounted on a shaft or shaft 153 that it is secured in the side panels 112 and 114. The sleeve 152A is moved by arms 148 and 150 to the pressure roller 126A; the sleeve 152B is moved similarly to the pressure roller 126B. This allows the pressure in each of the production lines to be controlled independently. The sleeves 152A, 152B can be rotated to control the friction applied to each belt 40A, 40B, as it passes between the pressure rollers 126A, 126B and the friction wheels 128A, 128B. For this purpose, a pneumatic pressure control system is provided at each end of the shaft 153. The systems comprise air cylinders 158 and pistons 156 attached at their upper ends to a link 154 which is attached to the sleeve 152A or 152B (see figure). 8). The pistons 156 can be driven by air in a conventional manner and serve to control the pressure between the friction rollers 126A, 12B and the friction wheels 128A, 128B respectively. The friction wheels 128A and 128B are secured to a shaft 160. One end of the shaft 160 is appropriately driven into the side panel 112 of the case with the other end driven into a mounting cylinder 162 attached to the side panel 114. The shaft 160 is rotated by servomotor 164 by means of a band 166 and pulleys 168 and 170, all of which can be conventional. As explained above with respect to Figure 7, the servomotor 164 rapidly accelerates the axis 160, which causes the friction wheels 128A and 128B to open the separation line 14 of the individual fold of the belt that comes into contact with the wheel. of friction. The wheels 128A, 128B are preferably manufactured from silicone rubber with a hardness of approximately 40 durometer. It has been found that this material is effective to separate a single layer from a multilayer tape. A mechanism can be provided to limit the movement of the friction rollers of the friction wheels 128A, 128B. In Figure 9, four retention mechanisms are shown, each of which may be the same. A block-like block 171 is rotatably attached to the arm 154. A pin 172 extends through the block 171 and receives a nut 174 at its end. The bolt includes a non-threaded portion that passes through a cylindrical ring 176 that is rotatably attached to the panel 112 of the frame or frame. The position of the nut can be adjusted in a threaded manner to limit the upward (or downward) movement of the associated pressure rollers 126A, 126B (and 138A, 138B). By way of example only, a typical line speed may be in the range of 140 to 146 meters per minute (460- 480 feet per minute). The servomotor 164 can accelerate the pressure wheels 128A, 128B to approximately 150% of the line speed five times every second, which means that for each line, the top folds of five bags can be opened in every second. In the preferred embodiment, one of the external folds is completely separated along the separation line 14. It is also possible that the same principle can be applied during actual use of the dispenser, whereby one of the external folds is separated before the user separates the bag from the roll. A structure that can be used for this purpose is shown in Figure 11. The timing or synchronization signals fed to the servomotor are generated by a controller that allows manual fine tuning of the acceleration speed of the desired wheel and an encoder module (not shown) for interpreting the signals of the piercing detector 68 (Figure 7) to effect appropriate timing or synchronization. In a preferred embodiment, a modified Unidrive model controller manufactured by Control Techniques, Inc. is used. The dispenser shown in Figure 11 is the same as the dispenser shown in the North American patent application Serial No. of the Applicant, filed 09 March 1998, proxy file number 2669 / 0D316 and entitled Plástic Bag Dispenser and Support Mechanism Therefore. That application is incorporated herein by reference. The roll of bags is the same as the roll of bags described in this specification and is shown with the number 200 wound on an axis 201. The axis 201 slides on a pair of tracks 202 and the film is pulled beyond a hand 204 and a separation tab 206 that engages the slot 14A in the center of the perforation line to separate the bag that is stocked from the roll. Ordinarily none of the folds would be separated from the roll until the user actually pulls the bag to cause the tongue to separate the bag from the roll. According to this embodiment of the invention, a friction wheel 208 is mounted on the side walls of the spout ctly opposite the handle 204 with its bottom surface slightly below the top surface of the knob 204. The friction wheel 208 does not rotates but is positioned to apply sufficient pressure to the film, such that as the consumer pulls a bag, the friction applied by the wheel 208 causes the top layer of the film to separate along the line of the film. piercing before the bag is actually separated from the bag roll. Because this case the upper layer is completely separated before separation, the effect is the same as if the bags had been provided with the pre-separated top layer; that is, when the bag is removed, the bag will be partially open. While the invention has been described with reference to an eight layer plastic bag belt, there may be a smaller or greater number of layers. Also, the layers may be plastic or other material such as paper or a combination of plastic and paper. Furthermore, it is not necessary that the entire separation line be opened to obtain the desired results while the separation line in an outer layer is separated beyond the slot 14A, some benefit will be obtained although it is preferred that substantially the entire line of separation be open. While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail can be made without departing from the spirit and scope of the invention. It is noted that in relation to this date, the best method known by the applicant to bring the practice to the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates.

Claims (7)

1. Claims Having described the invention as above, claim as property contained in the following claims: 1. A roll of plastic bags in a continuous tape, the bags in the tape have upper and / or lower layers, each bag is separated from an adjacent bag by a seam line or seam and a separation line having a central groove or slot for coupling with a separating element, at least one of the tape layers of each bag is at least partially separated from the adjacent pouches along the separation line, the region in which the layer of tape is separated is longer than the central slot or slit.
2. 2. A roll of plastic bags according to claim 1, characterized in that the bags are folded in such a way that one edge of the continuous tape is a fold.
3. 3. A roll of plastic bags according to claim 2, characterized in that the bags comprise a tube fully reinforced on each side and folded to form an eight-fold star-sealed configuration.
4. 4. A roll of plastic bags according to claim 3, characterized by a layer of tape is the top layer. A roll of plastic bags according to claim 4, characterized in that one or both of the outer tape layers of each bag are at least partially separated from the adjacent bags along the separation lines. 6. An apparatus for processing a moving belt of plastic bags, the belt comprises a plurality of layers of plastic film, the individual bags that are separated by seam or union lines and separation lines, characterized in that it comprises: a frame or frame; a pressure roller mounted for rotation in the frame or frame, a pressure roller mounted for rotation in the frame or frame. a friction wheel mounted for rotation in the frame or frame, each of the pressure roller and the friction wheel are brought into contact with each other and are vibratory as the ink is pulled between them; and control means for intermittently varying the rotation speed of the friction wheel so as to cause the separation line of the layer of plastic material contacting the friction wheel to be divided. 7. An apparatus for processing a moving belt of plastic bags according to claim 6, characterized in that it includes sensitive means either to the separation or joining line between each pair of bags to drive the control means.