Abstract:
A method and apparatus for the fixed combination of side-fold bags to form stacks. The side-fold bags to be combined, arriving from a machine which produces side-fold bags, are previously separated into stacks of a controlled quantity. During combining, each stack is oriented in relation to a perforating station, pressed together and punched with at least two through-holes. Each stack is interlockingly bundled by at least one intermediate fixation element, which is force-lockingly closed to form a loop, for the purpose of being further used in an automatic goods packing machine, where each stack is fixedly held in a packaging station by a fixing element in the shape of a hoop, which penetrates through the holes, wherein the intermediate fixation element is removed.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a method and an apparatus for a fixed combination of side-fold bags to form stacks, wherein the side-fold bags to be combined, which are coming from a machine which produces side-fold bags, have previously been separated into stacks of controllable quantity, and wherein during combining each stack is oriented in relation to a perforating station and is pressed together. 
     2. Description of Prior Art 
     In order to be able to automatically package goods, for example bread, it is necessary that the packaging is accurately oriented and is easy to handle. The automatic packaging of goods in paper or plastic bags in particular makes high demands. Generally, bags which have a side fold are used for this purpose, having one side at the open end of the bag which is not folded and forms a protruding tongue. Such bags are called side-fold bags. To allow automatic packaging, several side-fold bags are combined to form a stack by guiding a metal hoop through two holes punched into protruding tongues lying on top of each other. During packaging, a stack of side-fold bags is held in the packaging device in such a way that the side-fold bags lie flat on a packaging table with their sides having tongues down, and the open ends of the metal hoop project downward. The topmost side-fold bag is opened by blowing in air and the goods are inserted. Thereafter the side-fold bag with the goods is pulled away from the metal hoop in the longitudinal direction and the holes are ripped open in the process. Now the bag next below is inflated and goods packed in it. 
     The metal hoop assures that the respectively topmost bag can be inflated, while the lower, punched lateral surface is kept on the packaging table. The hoop additionally maintains the bags in a fixed position and allows the tearing off of the uppermost bag in a well-defined direction. 
     The stacks have the metal hoops during their manufacture and packing. To this end bags produced by the machine producing side-fold bags are counted in a counting device, counted stacks are pressed together, the protruding tongues are provided with two punched holes and a metal hoop is manually guided through the holes. For fixing the stack in place, a rubber band is manually wound around the open ends of the metal hoop. Thereafter the bundled stacks are packed and delivered to the packager. 
     The packaging method using metal hoops has proven itself but is disadvantageous because the metal hoops are awkward and therefore make the packing of the stacks more difficult. The fact that some steps must be manually performed further increases the packing costs. In addition, the metal hoop increases the total weight, which in turn increases transportation costs. It is furthermore necessary that the metal hoops be returned from the packager to the bag manufacturer to be reused. 
     SUMMARY OF THE INVENTION 
     It is one object of this invention to provide a method for fixing stacks of such side-fold bags in place which corrects the above mentioned disadvantages. 
     It is a further object of this invention to produce a device for bundling side-fold bags wherein the method of this invention is employed. 
     In accordance with the method of this invention, the side-fold bags coming from the production machine and made available in stacks in controllable quantities have an intermediate fixation which, in the form of a loop, interlockingly bundles the stack. The intermediate fixation preferably comprises two tapes which are guided through the through-holes of the stack and whose sections which come to rest on top of each other are connected with each other, so that each tape forms a closed loop. Thus the sections are preferably welded together. By means of the tapes the bags are fixed to form a bundle without being able to displace each other. 
     Now the bundling and packing of the side-fold bags can be performed completely automatically. In addition, the bundles are easier to pack because they can be welded in foils, for example. 
     So that the bundles can be used for automatic packaging of goods, the known metal hoops are pushed through the holes in the bundle by the goods packager and the tapes are preferably cut. Therefore the automatic packaging method for goods remains unchanged. 
     An exemplary embodiment of the device in accordance with this invention is represented in the attached drawings, by means of which the method in accordance with this invention will be described. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1a is a schematic side view of a device in accordance with the invention; 
     FIG. 1b is a schematic top view of the invention shown in FIG. 1a; 
     FIGS. 2a to 2h each show a schematic top view of individual method steps in the perforation and tape station; and 
     FIGS. 3a to 3f each show a schematic side view of the individual method steps in the perforation and tape station. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     A device in accordance with this invention for side-fold bags, also called a bag bundling machine, is schematically represented in FIGS. 1a and 1b. Side-fold bags 6&#39;, shown in FIG. 3a, coming from a bag-producing machine are conveyed through a reception station 1 to the bag bundling machine. The reception station 1 is known from the prior art and in general comprises a conveyor drum 10 with a counting unit 11 for counting the bags 6&#39;, a pivot station 12 for taking the bags 6&#39; off the conveyor drum 10 and for transferring the bags 6&#39; in stacks to an input station 13, where the formed stack 6 is turned into the desired position and is handed over transversely to its longitudinal direction, defined by the opening in the bags 6&#39;, to the bag bundling machine, or more specifically to a conveyor unit 2. The counted and stacked side-fold bags 6&#39; are aligned in the conveyor unit 2 and are transferred to a pressing station 3, where the bags 6&#39; are pressed together and are conveyed on by the conveyor unit 2 to a perforating station 4. From there, the stacked bags 6&#39; come to a tape station 5, where the individual stacks 6 are fixed in place as bundles. 
     The individual method steps for bundling the stacked side-fold bags 6&#39; are represent ed in FIGS. 2a to 2h, starting from the conveyor unit 2 up to the tape station 5. A stack 6, which rests on a conveying element of the conveyor unit 2, is shown in FIG. 2a. On its side which is not folded, each side-fold bag 6&#39; has a protruding tongue 60. This side i s downward oriented. 
     The stack 6 is aligned in the conveyor unit 2 by means of lateral and rear bag guide elements 20, 21 and is conveyed in the longitudinal direction to the pressing station 3. In a next step, the stack 6 is pressed together in the pressing station 3 by means of first bag pressing elements 30, 30&#39;, for example by two clamping bars which are height-adjustable and arranged at a distance from each other, wherein preferably the lateral and rear bag guide elements 20, 21 continue to adjust the stack 6 during the pressing process. This is shown in FIG. 2b. 
     Subsequently the stack 6, pressed together by the first bag pressing elements 30, 30&#39;, is moved transversely to its longitudinal direction to the perforating station 4, where a continuous hole 61 is punched through the protruding tongues of the bags 6&#39; by means of a known punch element, as represented in FIG. 2c. The production of the hole does not necessarily have to be done by punching, other ways, for example drilling, are also possible. Subsequently the stack 6 is conveyed by a defined distance transversely to its longitudinal direction by the conveyor unit 2, so that a second hole 62 is punched through the protruding tongues 60 at a distance which corresponds to the width of a metal hoop employed in the automatic packaging of goods, as shown in FIG. 2d. It is also possible to produce both holes 61, 62 simultaneously. However, the embodiment described here has the advantage that it is possible to operate at a lesser punching pressure. 
     Now, as shown in FIG. 2e, the transfer of the pressed stack 6 from the first bag pressing elements 30, 30&#39; to second bag pressing elements 31, 31&#39; takes place. This transfer is not necessary, the stack 6 can also be conveyed on by means of the first bag pressing elements 30, 30&#39;. However, this transfer increases the frequency with which the individual stacks 6 can be inserted into the bag bundling machine. These second bag pressing elements 31, 31&#39; are preferably embodied the same way as the first ones, for example they again are two spaced-apart clamping bars but are arranged offset with respect to the first ones. 
     The next step is shown in FIG. 2f. In the pressed state, the stack 6 is again moved transversely with respect to its longitudinal direction to the tape station 5, wherein respective tapes 50, 50&#39; from respective rolls of tape, not shown, are introduced into the two spaced-apart holes 61, 62. Thereafter, as shown in FIG. 2g, the stack 6 is moved together, or by means of the second bag pressing elements 31, 31&#39; in the longitudinal direction, therefore transversely in relation to its conveying direction up to now, toward the rear, for example away from the tape station 5. In this position the tapes 50, 50&#39; are separately welded into loops and cut off the tape roll. Finally, as shown in FIG. 2h, the second bag pressing elements 31, 31&#39; are moved back to the transfer station and the bundled stack 6 is conducted to a further packing station, not shown. In FIG. 2h, tapes 50, 50&#39; have been removed from stack 6 and a fixing element penetrates through holes 61, 62 to fixedly hold the stack. 
     The method steps by which the stack 6 is tied together by tapes 50, 50&#39; are shown from a different perspective in FIGS. 3a to 3f. The side-fold bags 6&#39; are represented at a distance from each other for greater clarity, although they are pressed on each other during these method steps. 
     The method step shown in FIG. 3a corresponds to the situation represented in FIG. 2f, but only the first hole 61 and the first tape 50 are visible. However, the second hole 62 preferably has a second tape 50&#39; at the same time. The tape 50 is introduced into the hole 61 of the stack 6 by means of a tape guide element 51, which can be displaced in height. Suitable as a tape guide element 51 is, for example, a stiff sleeve, through which the tape 50 can be displaceably moved, and which tapers toward the end facing the stack, wherein a short end of the tape 50 protrudes from the sleeve. The tape guide element 51 is introduced into the hole 61 until the protruding end of the tape 50 projects on the underside of the stack 6 into a tape fixing element 52, which for example is formed by two clamping jaws arranged under the stack 6. The clamping jaws are moved toward each other and fix the tape 50 in its position, as shown in FIG. 3b. Thereafter, as shown in FIG. 3c, the tape guide element 51 is moved upward and the stack 6 in the pressed state is moved toward the rear, as already shown in FIG. 2g, away from the tape station. Because of this the tape 50 is unwound from a tape roll, not shown, until sufficiently long sections of the tape 50 protrude on both sides of the hole 61 past the front edge 63 of the stack 6. A welding tongue 54 is moved closely in front of the front edge 63 of the stack 6. Other welding tongues, not shown, are provided for the further tapes. Subsequently, as shown in FIG. 3d, tape pressing elements 53, for example again oppositely located clampingjaws, are moved together on both sides of the stack 6 from above and below, and the tape sections protruding past the front edge 63 are brought to the heated welding tongue 54. The welding tongue 54 is retracted after a predefined length of time and the heated tape sections are pressed on each other by means of the tape pressing elements 53. In FIG. 3e the tape section connected with the tape roll is cut off by means of a separating element 55, for example a cutter, wherein the separation occurs at a place shortly back of the welded connection and sufficiently far removed from the lower end of the tape guide element 51, so that the end of the tape 50 required for the next bundling again protrudes from the tape guide element 51. 
     The stack 6, now bundled by means of an intermediate fixation, is again pushed forward in accordance with FIG. 3f and from there the bundled stack 6 is conveyed to a packing station, not shown, where the several bundles are packed together in boxes or foil. 
     The method in accordance with this invention leads to the desired end in this general form. However, tests have shown that it is advantageous to make the holes non-circular, but in such a way that a predefined breaking point is formed on the bag, so that, when the bags 6&#39; are inserted into a goods packaging machine, every bag is torn out of its fastening exactly in the longitudinal direction. It is thus advantageous to provide the holes with a notch oriented toward the front edge, for example, or to make the holes cornered, wherein one corner is oriented toward the front edge. It has also been found to be advantageous to use as tape those tapes used for baling, since they can be welded in a simple manner without shrinking. They furthermore are sufficiently stiff to prevent the displacement of the individual bags in relation to each other. Welding by means of the welding tongue can be performed very closely in front of the front edge of the stack 6 without the individual bags being affected by the heat or perhaps even welded together. The weld bead can be kept comparatively short, so that the tape welded into a loop projects only a little in front of the stack 6 and therefore does not interfere with packing. Furthermore, shorter lengths are sufficient for tying the bags together. 
     In another preferred embodiment of the method, the side-fold bags already have holes, so that this method step is omitted from the device in accordance with this invention. This is advantageous, for example, when the bundles are too thick to be easily punched. In this case an alignment station is advantageously provided in place of the punching station, which has pins that are conducted through the holes of the side-fold bags and thereby align the bags.