DE202015002947U1 - Device for producing sacks or bags and sacks or bags - Google Patents

Abstract

Apparatus for making sacks or bags with vents, comprising a coated web of stretched polyolefinic material, having at least one perforating tool for introducing a number of vents less than 0.8 mm in diameter into a flat or tubular web or sections thereof • With a device for molding at least one bottom of sections of the flat or tubular web for the production of sacks or bags, characterized in that the perforation tool is adapted to provide areas of at least one folded edge with vents of reduced diameter.

Description

The invention relates to a device for producing sacks or bags according to the preamble of patent claim 1 and a bag or bag according to the preamble of claim 16.

With bags or bags comprising a coated fabric of polyolefinic materials, there is the difficulty that, due to the coating formed by the application of liquid polyolefinic material, when filling the sacks or bags, the air introduced with the contents will escape poorly can. This occurs especially when the filling material, such as building materials, is filled as a product-air mixture.

Therefore, such bags or pouches, the flat or tubular web or portions thereof from which the bags or pouches are later made, are provided with a number of vent openings by means of a perforating tool.

Vents are characterized by the fact that the air from the bag interior can penetrate to the outside. At the same time the vents are small enough so that no moisture can enter from outside into the bag. This is usually the case when the vents are smaller than 0.8 mm in diameter. The vents are usually introduced as a surface perforation the flat or tubular web or sections thereof.

Microperforations, for example with a density of 13 vents per square centimeter (cm ³ ), and nanoperforations, for example with a density of 64 vents per square centimeter (cm ³ ), can often be distinguished from each other. For example, the perforations may be formed with substantially conical needles or with substantially cylindrical needles.

A bag or a bag comprises as essential components a front wall, a rear wall, and one or two molded bottoms, wherein in the case of two molded bottoms of a bottom of the bag usually comprises a valve to fill the bag over it can.

The problem, however, is that when mechanical loads on the bag bottom, such as when filling or when thrown, they can burst. It has been observed that the sacks tear particularly at the folding edges of the soil.

It is therefore an object of the present invention to provide a device for producing a bag and a bag, in which the risk of bursting of the bag is reduced.

According to the invention this object is achieved by all features of claims 1 and 16. In the dependent claims, in the figures and in the description of possible embodiments of the invention are given. In this case, where appropriate, the features of the device according to the invention can be regarded as embodiments of a sack according to the invention and vice versa.

According to the present invention, it is provided that with the at least one perforation tool, regions of at least one folded edge, in particular regions of the later, that is to be molded, floors, can be provided with vents of reduced diameter. "Reduced" is to be understood here in comparison to the diameters of the vent holes in the bag front wall and / or the rear wall of the bag. The diameter of the vent openings in the bag front wall and / or in the sack rear wall is less than 800 microns (microns), in particular less than 100 microns (microns), preferably less than 50 microns (microns). As an alternative or in addition to the areas of the later floors, the regions of the front and / or rear walls adjoining the floor can also be provided with vents of reduced diameter. In particular, the transition region from a floor to the adjoining front and / or rear wall can be provided with vents of reduced diameter. This transition is usually defined by the existing folded edge. Also, the areas of the folding edges that connect the bag front wall and the bag rear wall with each other can be provided with vents with reduced diameter.

The invention is based on the finding that the tissue is significantly weakened by the introduction of the vent holes, so that the nominal tear strength of the fabric is reduced. This weakening is further reinforced at the folded edges, in particular at the folded edges of the bottom. Such fold edges are often unavoidable. In particular, when forming cross or block bottom bags such fold edges are generated. The laying flat of a hose leads to folded edges, which represent weak points.

The strength of the bags can be significantly increased by the above-described inventive measure.

It is advantageous if the areas of the at least one folded edge, in particular those of the subsequent floors, are completely free of ventilation openings through the perforation tool being held. A corresponding embodiment of the perforation tool will be discussed below. As a result, the strength can also be further increased in the region of the folded edges. Now only the weakening by the actual folding plays a role. By the expression according to which "areas of the at least one folded edge, in particular those of the subsequent floors are kept free", it is meant that the diameter of the ventilation openings in these areas is reduced to 0, ie no ventilation holes are introduced.

In a particularly preferred embodiment of the invention, provision is made for the device according to the invention to be provided in a machine in which the production of at least one base takes place by means of at least one hot-air sealing station.

During bottoming, at least one end of a length of tubing is pulled open to form an open bottom rectangle with simultaneous formation of side triangular pockets. Under the formation of further folding edges parts of the resulting tabs are repulsed. Subsequently, a so-called bottom cover sheet is sealed by the latter being deposited successively on the tabs. In this case, between the tabs on the one hand and the bottom cover sheet on the other side thermal energy, such as hot air, so that the coatings of the elements involved are melted. Immediately thereafter, before the coating solidifies again, the elements are pressed. It creates a solid connection. The energy input is to be made so that, although the coating is melted, but the stretched fabric is heated as little as possible. If too much warming of the fabric loses its strength, which was added to it by stretching.

When using a device according to the invention for producing sacks with at least one bottom produced by thermal sealing, the strength of the sack, in particular in the region of the folded edges, can be increased particularly strongly. The disadvantage of the conventional manufacturing method is that the vents facilitate a penetration of the thermal energy to the tissue, so that it loses its strength in particular. This is especially true when using an air flow as an energy source, since this is additionally injected into the vents.

In an advantageous embodiment of the invention, it is provided that, viewed in the transport direction (x) of the flat or tubular web, at least 0.3 cm, in particular at least 0.5 cm, before and after later to be formed fold edges of the subsequent trays with vents with reduced diameter are providable. In this case, the later bag receives as many vents as possible, so that a high venting performance is achieved, which is particularly advantageous when filling with a product-air mixture. However, an adaptation to the bag length and / or the floor size is required.

As an alternative to this, in the transport direction (x) of the flat or tubular web, the section in which vents of reduced diameter can be introduced can be kept constant independently of the sack length and / or the bottom size. As a result, the handling of the associated device is simplified.

In a further, advantageous embodiment of the invention it is provided that the distance of the perforation tool to the flat or tubular web in the areas in which the flat or tubular web is provided with vents with a reduced diameter, can be increased. This is a simple and constructive approach with little effort.

It is also advantageous if the ventilation openings can be produced with a needle roller. This can roll on the flat or tubular web or sections thereof. In areas where the flat or tubular web or sections thereof are provided with reduced diameter vents, the needle roller can be removed from the flat or tubular web. A rolling needle roller is a very low-wear way to create vents. It is equally effective if, instead of moving the needle roller, the flat or tubular web is moved toward or away from the needle roller. It depends on a relative movement of the needle roller and the flat or tubular web.

Instead of removing the needle roller when reduced diameter vents are provided, the needle roller for the regions may also be provided with smaller needles or recesses in the needle stock. It is advantageous that a mechanism can be saved. This variant is advantageous if a rare or no change in the bag size (bag length) occurs. If a change in the bag size is desired, the needle roller is usually also replaced.

In a further advantageous embodiment of the invention is a synchronization of the introduction of vents with reduced diameter and the printed image, which is often on the flat or tubular web before Sack production is applied, provided. For this purpose, at least one sensor element is provided, which scans the printed image or parts thereof or other elements characterizing the position of the printed image on the tubular web. The signal is fed to a control device, which controls the perforation tool in such a way that the vents of reduced diameter assume a fixed position relative to the printed image. This position is often determined by the fact that the subsequent soil occupies a defined position relative to the printed image.

Instead of generating ventilation openings by means of mechanical means, it is also possible to provide contact-free means, such as electromagnetic radiation, as can be generated, for example, by means of a laser device.

Further advantages, features and details of the invention will become apparent from the following description in which, with reference to the figures, various embodiments are explained in detail. The features mentioned in the claims and in the description may each be essential to the invention individually or for any combination of mentioned features. The individual figures show:

1 Schematic diagram of a device for generating vents.

2 Variant of the device according to the 1 ,

3 Sack with vents according to the invention

4 Sequence for the production of sacks according to the invention

5 Device for producing sacks

1 shows a device 100 for providing a tubular web 101 with vents, which in the view of 1 are not visible. The device 100 is integrated, for example, in a device for producing sacks from a roll with a tubular web. The installation location of the device is preferably between the unwinding device and the device for separating the tubular web into pieces of hose. In this area, the transport direction is the direction in which the longitudinal axis of the hose is directed.

The tube web 101 is about one in the machine frame 102 rotatably mounted transport roller 103 guided, which is preferably covered with an elastic material. A needle roller 104 is on its outer peripheral surface with a large number of needles 105 provided so that the tube web 101 , can be provided with vents almost in their full width. The areas near the folding edges are preferably recessed in order not to weaken these weaknesses additionally by the needling.

In order to be able to also produce areas with ventilation openings with a variable diameter in the transport direction x, the needle roller is 104 in at least one sled 106 rotatably mounted, which along the frame-fixed rails 107 relative to the tube web 101 is displaceable. For this purpose, the carriage is the first end 109 a connecting rod 108 rotatably mounted, the second end 110 rotatable with a handrail 111 connected is. The latter is in turn rotatable with a frame-fixed counter bearing 112 connected.

On the hinge axis between the connecting rod 108 and the handrail 111 is a role 115 rotatably mounted, which with a pneumatic or hydraulic cylinder 113 that hinges with the machine frame 102 is connected, against the cam roller 114 is pressed.

The cam roller 114 is set in rotation by a rotary drive, not shown. If now the cam 116 the cam roller 114 on the role 115 it hits against the force of the cylinder 113 pushed back. Due to the kinematics is now the slide 106 and thus the needle roller 104 removed from the tube. Depending on the height of the cam, the needles can 105 completely from the tube web 101 be removed so that no vent holes now arise.

Depending on the desired size of the area of the vent holes, the cam in the circumferential direction of the cam roller 114 be designed shorter or longer. Alternatively, the cam roller can also be driven non-uniformly. The largest distance of the cam to the pivot point of the Nockelrolle 114 determines if and how deep the needles 105 still in the tube 101 and thus to what extent the diameter of the vent holes is reduced compared to the original diameter.

As can be further seen, the cam roller 114 eccentric in a disc 120 mounted, which in turn is rotatable relative to the machine frame. By a rotation of the disc 120 can be on the already described operative connection of the cam roller with the needle roller, the basic position of the needle roller to the tube web and so that the basic diameter of the vents set.

Overall, with the illustrated and described device, the diameter of the vent openings in the tubular web can be varied such that the areas of the later folded edges are damaged as little as possible, so that the durability of the bags produced later from the sections of the tubular web is improved.

The 2 now shows a variant of the device according to the 1 , Here is the needle roller 104 not stored in a slidable on rails carriage, but in a swivel arm 130 rotatably mounted. This swivel arm is over a bearing 131 pivotally connected to the machine frame. All the rest in the 2 shown device components correspond to those of 1 ,

Another variant, not shown, is based on the device according to FIG 2 , It is envisaged that the swivel arm 130 is moved directly from a drive without the interposition of kinematics. A position-controlled drive can provide a sufficiently large force to create vents.

In further, not shown alternative embodiments, instead of or in addition to the movement of the needle roller, the transport roller 103 to be moved. For this purpose, then advantageously the same device components are used in the same functional context, as in connection with the 1 and 2 with respect to the needle roller.

The 3 shows a bag according to the invention 300 , This comprises a web of polyolefinic threads or narrow strips which was stretched before weaving. Such a fabric is characterized by a high tensile strength in all load directions. Preferred polyolefin for this application is polypropylene. The fabric is additionally provided with a coating which serves different purposes. The role of the coating for the production of a bag, is determined by the 4 described. The coating, which is produced by applying a liquefied plastic on a flat or tubular web of tissue, serves in addition to the better printability of the web and the subsequent moisture protection of the medium. The coating usually comprises polypropylene or polyethylene.

For venting the bag interior are in the bag front wall 301 and / or in the invisible sack rear wall vent holes 302 introduced, which are shown exaggerated for clarity. In practice, these are much smaller openings, which are present in large numbers.

The bag 300 includes a bottom at each end 303 . 304 one of which is equipped with a filling valve, which is not shown. Each bottom is preferably of the cross-bottom type and has a cover sheet 305 busy. It can be seen that the floors are not in the same or in a parallel plane of the sack front wall 301 is, but for example perpendicular to it. The transition is formed by a folded edge over which, however, the ventilation openings can extend. In a filled bag, these folded edges are no longer pronounced, but represent a weak point during the filling process.

A strong influence on the stability of the bag 300 have the folded edges 306 , Which mark the transition from the bag front wall or bag back wall to the ground in the finished bag. Between the two folded edges 306 a bottom cover sheet is arranged, which has preferably been fixed by hot air sealing. On the basis of the two floors it can be seen that in front of and behind the folded edges 306 the areas A and B are kept free of vents. The areas A and B advantageously have a width (seen in the tube longitudinal direction) of at least 0.3 cm and preferably at least 0.5 cm. In this way, the folded edges are as little as possible loaded, so that their stability is as large as possible. Based on the soil 303 you can also see that below the ground cover sheet 305 can be arranged again vents without the stability of the bags would be reduced.

The 4 illustrates in its parts a to d the process for producing a bag. It can be seen which areas of the later bag are provided with vent holes with a reduced diameter.

The part 4a ) shows a hose section 400 whose front wall 401 can be seen and already with ventilation holes 402 is provided. The dotted lines 403 make the later folding edges 430 of the soil and are accordingly not provided with ventilation holes. In the part 4b ) can now be seen that parts of the front wall 401 was beaten back at their ends, with ground rectangles 410 and triangle pockets 411 have arisen. In addition, now are parts of the back wall 412 to recognize. In the part 4c ) are now the tabs 421 the front wall and 422 the back wall, each located between the folding edges 403 and the end of the piece of tubing, were folded back to close the bottom. Finally, in the part 4d ) each a ground cover sheet 431 attached by hot air seal on the closed floors. In hot air sealing would be the folding edges 430 particularly damaged if due to the vents, the hot air could penetrate into the tissue and at this, for example, by the filling and transport of the filled sack, heavily stressed site could damage the tissue. This is accomplished by providing reduced diameter vents over the vents in the front and / or back wall 401 . 412 avoided.

The 5 now shows schematically an overall machine 501 for the manufacture of sacks comprising a coated web of stretched polyolefinic material. First, the tube web 502 the whole machine 501 fed. This is advantageously done by unwinding a winding 503 forming fabric tube in a processing device 504 , Then the hose can 502 the so-called opening in the opening station 205 Experienced. In this case, the fabric tube is guided around an inner tool, which separates the two layers from each other, so that the layers, if they were glued together in one of the manufacturing steps of the hose, separate. Only with separate layers can it be ensured that the following production steps can be carried out properly. Afterwards, the separate material layers of the hose are put back on top of each other.

The fabric tube will now be the cross cutter 506 supplied, which singles the fabric tube into individual pieces of hose. The web cutting station is preceded by a web storage, not shown, which allows to withdraw the tubular web from the unwinding device at a uniform speed, but advance or-pull in the cross-cutting station intermittently. Such track storage are known in the form of dancers.

Subsequently, a change of the original transport direction z, in which the tube or pieces of tubing were transported in the direction of their longitudinal axes, in the new transport direction x, so that the hose pieces now no longer in the direction of z hose longitudinal axis (hereinafter also extension direction of the hose pieces called ), but are transported transversely thereto, so that the ends of the hose pieces are laterally accessible for the purpose of molding the floors. This takes place in the transfer station 507 ,

In the next station, the floor opening station 508 , both ends of each piece of tubing are opened and the so-called ground rectangles are laid. In the following valve station 509 a valve is placed on one of the two open ends and fastened. The open floors will now be in the bottom closing station 510 closed, with two tabs are placed on each other and are connected to each other permanently by hot air sealing. The conclusion of the actual Sackherstellprozesses forms the application of a ground cover sheet on the floors in the cover sheet station 511 , For this purpose, the cover sheets can also be welded. The finished sacks are then placed on the sack stack 512 stored and transported away from there on unspecified manner.

A device 520 to provide the tube web with vents is advantageously behind the unwinding device 504 and in front of the cross cutter 506 into the whole machine 201 integrated. Advantageously, the device 520 be provided as an optional unit, which can work independently of the overall machine and must not be connected to this. There must be only a sufficiently large amount of space available.

However, a device for providing pieces of tubing with vents may also be in or after the transfer station 507 respectively. In this case, for example, a needle roller may be provided which extends in the axial direction between the folded edges 403 extends and whose axis of rotation is parallel to the tube longitudinal axes. This is a particularly simple variant of a device according to the invention, since here the distance of the needle roller to the tube pieces does not have to be changed.

Claims (16)

Apparatus for making sacks or bags with vents, comprising a coated web of stretched polyolefinic material, having at least one perforating tool for introducing a number of vents less than 0.8 mm in diameter into a flat or tubular web or sections thereof With a device for molding at least one bottom of sections of the flat or tubular web for the production of sacks or bags, characterized in that the perforation tool is adapted to provide areas of at least one folded edge with vents of reduced diameter. Apparatus according to claim 1, characterized in that with the perforation tool Areas of the at least one folding edges of vents are kept free. Device according to one of the preceding claims, characterized in that with the perforation tool areas of at least a part of the folding edges, which define the floors, with vents with reduced diameter are providable. Device according to one of the preceding claims, characterized in that at least one hot air sealing station is provided, with which the at least one bottom can be produced by thermal sealing, in particular by hot air sealing. Device according to one of the preceding claims, characterized in that seen with the perforation tool in the transport direction (x) of the flat or tubular web at least 0.3 cm before and behind later to be formed folding edges of the subsequent floors with vents with reduced diameter are providable. Device according to one of the preceding claims, characterized in that the perforation tool comprises at least one needle roller. Device according to one of the preceding claims, characterized in that the perforation tool is in the region of at least one folded edge out of interaction with the flat or tubular web or sections thereof. Device according to one of the preceding claims, characterized in that an on-and off device is provided, with which the relative distance between the perforation tool and the flat or tubular web or sections thereof is variable. Device according to one of the preceding claims, characterized in that the perforation tool is mounted on at least one carriage or in a lever which is movable by means of a displacement device at least perpendicular to the flat or tubular web. Device according to one of the preceding claims, characterized in that the displacement device comprises a rod, preferably a connecting rod, which is connected at its first end rotatably connected to the carriage or lever and / or with the perforating tool. Device according to the preceding claim, characterized in that the second end of the rod is connected via a hinge to the first end of a support rod, whose second end is rotatably but immovably mounted in the machine frame. Device according to one of the two preceding claims, characterized in that the rod and / or the support rod and / or the joint between the two rods comprises a stop element, which can be pressed with a force providing device against a Wegbegrenzungselement. Device according to the preceding claim, characterized in that the Wegbegrenzungselement is a rotatably driven cam. Device according to one of the two preceding claims, characterized in that the travel limiting element via a displacement device, in particular via an eccentric, relative to the machine frame is displaceable. Device according to one of the two preceding claims, characterized in that the Wegbegrenzungselement is a rotatably driven with a uniform rotational speed cam. A sack or bag having vents, comprising a coated web of stretched polyolefinic material, having a bottom comprising elements joined by a thermal sealing process, the vents having a diameter of less than 0.8 mm. characterized in that areas of at least one folded edge, in particular areas around folding edges of at least one floor, have vents of reduced diameter.

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