Bottom-forming station and method for forming a fold-over bottom on a fabric tube piece

Abstract

The invention relates to a bottom-forming station (16) for forming a fold-over bottom, comprising: a conveying device (20) for conveying the fabric tube piece in the conveying direction (21); a fold-over device (22) for folding over an end region of the fabric tube piece (11) onto a fabric tube wall of the fabric tube piece; a hot gas nozzle (12) for ejecting hot gas, preferably hot air; and a pressing device (25) for pressing the end region and the fabric tube wall of the fabric tube piece (11) together in order to form the fold-over bottom, the hot gas nozzle (23) having at least one first outlet opening (26) for ejecting hot gas in the direction of the outer face of the fabric tube wall and at least one second outlet opening (27) for ejecting hot gas in the direction of the inner face of the end region of the fabric tube piece (11).

Description

[0001] SOIL FORMATION STATION AND METHOD FOR THE FORMATION OF A FOLDING SOIL ON A PIECE OF FABRIC HOSE

[0002] The invention relates to a bottom-forming station, preferably a pinch bottom-forming station, for forming a folded bottom, preferably a pinch bottom, on a fabric tube section with a tape fabric made of plastic tapes, preferably substantially made of semi-crystalline thermoplastic, preferably of polyolefin, for example polypropylene (PP) or polyethylene (PE), or of polyester, for example polyethylene terephthalate (PET) or polylactic acid (PLA), comprising: a conveying device for conveying the fabric tube section in a conveying direction, a folding device for folding an end region of the fabric tube section onto a fabric tube wall of the fabric tube section, a hot gas nozzle for ejecting hot gas, preferably hot air, between the outside of the fabric tube wall of the fabric tube section and the inside of the end region of the fabric tube section.

[0003] Furthermore, the invention relates to a method for forming a fold-over bottom, preferably a pinch bottom, on a fabric tube piece with a tape fabric made of plastic tape, preferably essentially made of semi-crystalline thermoplastic, preferably made of polyolefin, for example polypropylene (PP) or polyethylene (PE), or of polyester, for example polyethylene enterephthalate (PET) or polylactide (PLA).

[0004] Finally, the invention relates to a device and a method for manufacturing woven bags, preferably fold-bottom woven bags, preferably pinch-bottom woven bags.

[0005] As described in EP 2 599 617 Bl, woven pinch bags are known in which a printed film is applied to stretched polyolefin fabric. These woven pinch bags offer the necessary stability for the consumer sector, in addition to an attractive appearance, for packaging pet food, for example. To create the pinch bottom, one end of the tubular section is folded over by 180° and fixed to the bag wall. Due to the restoring forces of the resilient woven material, the formation of the folded bottom presents particular challenges. In the prior art of EP 2 599 617 Bl, the folding is guided by a guide element. To produce the folded bottom in a heat-induced joining process, hot air is blown into the interior of the guide element using a hot air nozzle, thus heating the plastic material to be joined.The hose section is then pressed between press rollers, whereby the folded bottom is formed by welding the molten plastic material.

[0006] The method of forming the folded bottom on the woven bag by hot air welding is still not ideal. Increasingly stringent demands are being placed on the quality and strength of the folded bottom, and in the consumer sector, also on its appearance, demands which the established method cannot always meet. With current technology, a balance must always be struck between the quality of the weld and the preservation of the fabric material. The higher the heat input from the hot air nozzle, the better the welding result; however, damage to the fabric material begins to occur, which can negatively affect the strength of the woven bag.

[0007] In contrast, the object of the present invention is to create a bottom formation station, a method and a device for the production of woven bags with which the folded bottom can be fixed by means of a high-quality hot gas welding connection, but the woven material is affected as little as possible.

[0008] This problem is solved by a soil formation station according to claim 1, a method for forming a folded soil according to claim 17, and a device for manufacturing woven bags according to claim 20. Preferred embodiments are included in the dependent claims.

[0009] In the soil formation station according to the invention, the hot gas nozzle has at least a first outlet opening for ejecting hot gas towards the outside of the fabric tube wall, which is preferably formed by a film applied to the woven tape, and at least a second outlet opening for ejecting hot gas towards the inside of the end region of the fabric tube section, which is preferably formed at least partially by the woven tape. Depending on the embodiment, the film preferably comprises polypropylene (PP), particularly preferably oriented polypropylene, in particular biaxially oriented polypropylene (BOPP), or polyethylene, particularly preferably oriented polyethylene, in particular biaxially oriented polyethylene (BOPE), or polyethylene terephthalate (PET), particularly preferably oriented polyethylene terephthalate, in particular biaxially oriented polyethylene terephthalate (BO-PET).As an alternative to the film, the woven tape can have a coating applied to it. The coating can be formed by extrusion. Preferably, the coating comprises or consists essentially of polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polylactic acid (PLA), and / or mixtures thereof. In preferred embodiments, both the film and the coating are formed from a thermoplastic, sealable, i.e., weldable, polymer.

[0010] The inventive method for forming a fold-over bottom, preferably a pinch bottom, on a fabric tube section with a tape fabric made of plastic tape, preferably made of polyolefin, for example polypropylene, comprises at least the following steps:

[0011] Conveying the fabric hose section in a conveying direction, preferably essentially horizontal,

[0012] Folding over an end area of ​​the fabric hose piece onto a fabric hose wall of the fabric hose piece,

[0013] The process involves the emission of hot gas, preferably hot air, between the outer surface of the fabric hose wall and the inner surface of the end region of the fabric hose section, wherein a first hot gas stream is directed towards the outer surface of the fabric hose wall and a second hot gas stream is directed towards the inner surface of the end region of the fabric hose section. In a preferred embodiment, the method further comprises the following step:

[0014] Pressing the folded end section together with the fabric hose wall of the fabric hose piece, so that the folded bottom is formed.

[0015] Thus, at least one first outlet opening of the hot gas nozzle is oriented towards the outside of the fabric hose wall, whereas at least one second outlet opening is oriented towards the inside of the end region of the fabric hose section. The outside of the fabric hose wall and the inside of the end region form the connecting surfaces, the material of which is melted or heated by the hot gas nozzle to such an extent that a thermal weld is created between the end region and the fabric hose wall by pressing in a pressing device. The at least one first outlet opening is designed separately from the at least one second outlet opening; that is, the first outlet opening does not transition directly into the second outlet opening.Since at least one first outlet opening and at least one second outlet opening are oriented in different directions, the outer surface of the fabric hose wall and the inner surface of the end section of the fabric hose can each be selectively supplied with a first or second hot gas stream, respectively. This design offers the advantage that the first and second hot gas streams can be adapted to the design and material of the outer surface of the fabric hose wall and the inner surface of the end section, respectively. This advantageously allows for a significant improvement in the hot gas welding of the flat fabric hose wall to the folded end section of the fabric hose.

[0016] For the purposes of this disclosure, the location and direction references, such as "above", "below", "horizontal", "vertical", refer to an intended state of use of the soil formation station or of a device containing this soil formation station for the production of woven bags.

[0017] The woven tube section features the woven tape onto which the film, e.g., made of BOPP, can be applied, preferably laminated. This film forms the outer surface of the woven bag to be manufactured, preferably the pinch bag. The film can have a printed motif, e.g., as a reverse print. If a coating is used as an alternative to a film, the coating forms the outer surface of the woven tube wall.

[0018] In a preferred embodiment, a pinch bottom is provided as the folding end. To prevent the escape of filling material through the pinch bottom, the pinch bottom forms a sealing closure. For this purpose, at least one of the two opposing fabric tube walls of the folded end section has a recess, preferably stepped. As is known in the prior art, the recess can be produced in a previous manufacturing step by tearing off the fabric tube section along a stepped tear line from a fabric tube sheet. By folding over the end section with the, preferably stepped, recess on at least one of the fabric tube walls, the sealing closure of the resulting bag is formed, which prevents the escape of filling material from the finished pinch bag.

[0019] In this design, the first hot gas stream can strike the film or coating that forms the outer surface of the fabric hose wall opposite the end section. The second hot gas stream, however, can pass through the opening in one fabric hose wall and strike the inner surface of the other fabric hose wall, where the woven tape is exposed, i.e., where no film or coating is present. Thus, the hot gas streams emitted from the first and second outlets can be specifically tailored to the materials being joined. This was not possible with the prior art, as only a uniform hot gas stream could be delivered between the fabric hose wall and the folded-over end of the fabric hose section. This, however, resulted in less than optimal welding results.On the one hand, the adhesive bond could fail under heavy loads, and on the other hand, the woven fabric could be damaged by the hot gas injection. With the application of two hot gas streams in opposite directions according to the invention, the hot gas welding connection between the fabric hose wall and the unfolded end section of the fabric hose can be significantly improved without having to adjust any of the many other influencing factors for the weld connection, which would entail other disadvantages, such as a longer production time. Advantageously, a better, full-surface connection can be achieved right up to the leading edge of the folded end section. Furthermore, a particularly good weld appearance is achieved.

[0020] In another preferred embodiment, the folded bottom is straight, meaning that the leading edges of the fabric tube walls extending into the end section are straight and identical. Fabric bags manufactured with such a folded bottom are also known as padded bags. This embodiment also advantageously allows for a better, full-surface connection right up to the leading edge of the folded end section. Furthermore, a particularly good weld pattern is achieved.

[0021] In a preferred embodiment, a normal to the first outlet opening of the hot gas nozzle is at an angle of 50° to 140°, preferably 60° to 130°, preferably 70° to 100°, to the normal to the second outlet opening.

[0022] In a preferred embodiment, the hot gas nozzle is configured to expel hot gas with a larger volume flow and / or a higher temperature towards the outside of the fabric hose wall of the fabric hose section via at least one first outlet opening than towards the inside of the end region of the fabric hose section via at least one second outlet opening. In this embodiment, a greater heat output is delivered towards the outside of the fabric hose wall via the first outlet opening than towards the inside of the folded end region of the fabric hose section via the second outlet opening. This embodiment is particularly advantageous when the outside of the fabric hose wall is formed by the (BOPP) film, while the inside of the fabric hose section is at least partially formed by exposed woven tape.In a pinch weld design, the second hot gas stream therefore strikes at least the exposed woven tape in sections. The (BOPP) film can be melted by the first hot gas stream, while the woven tape is only warmed by the second. By taking into account the different materials on the surfaces to be joined, the quality of the hot gas weld can be significantly improved without damaging the more delicate woven tape.

[0023] Depending on the design, the temperature of the hot gas from the first or second outlet opening can be at least 150°C in each case.

[0024] In a preferred embodiment, the at least one first outlet opening is configured differently from the at least one second outlet opening. It is particularly preferred if the at least one first outlet opening has a larger geometric dimension than the at least one second outlet opening, such that a first volume flow of the hot gas through the at least one first outlet opening is greater than a second volume flow through the at least one second outlet opening. In this embodiment, the hot gas can be guided to the at least one first and second outlet opening via a uniform hot gas channel, so that only minor modifications to known hot gas nozzles are required.Since at least one first outlet opening offers less flow resistance for the exiting hot gas than at least one second outlet opening, a larger hot gas flow can be released towards the outside of the fabric hose wall via at least one first hot gas opening than towards the inside of the folded end area via at least one second hot gas opening.

[0025] To provide the appropriate heat output for welding preparation across the width of the folded end section, the hot gas nozzle, in a preferred embodiment, has an arrangement of first outlet openings for expelling hot gas towards the inside of the end section of the fabric hose piece and an arrangement of second outlet openings for expelling hot gas towards the outside of the fabric hose wall of the fabric hose piece. In one variant, the first and second outlet openings are circular. In another variant, the first and second outlet openings are elongated, preferably in the longitudinal direction of the flat nozzle element described below. For example, the first and second outlet openings can be oval.This allows the hot air flow to be distributed more evenly and prevents localized overheating, which could cause the respective plastic material to contract. The first and second outlet openings are preferably spaced at regular intervals along the width of the end region.

[0026] In a preferred embodiment, the hot gas nozzle has a flat nozzle element which, in a lying position (preferably substantially horizontal during operation), can be arranged between the outer surface of the fabric hose wall and the inner surface of the end region. The first outlet openings are preferably arranged along one of the two opposite longitudinal sides of the flat nozzle element of the hot air nozzle, which preferably extend in the width direction of the end region (or substantially in the length direction of the fabric hose section).

[0027] The fabric hose section is preferably conveyed in a transverse transport position along the hot gas nozzle. In the transverse transport position, the longitudinal axis of the fabric hose section extends essentially perpendicular to the conveying direction, which preferably runs essentially linearly in a conveying plane, preferably a horizontal one.

[0028] In this embodiment, it is advantageous if the normals to the first outlet openings of the hot gas nozzle are each at an angle of 50° to 140°, preferably 60° to 130°, preferably 70° to 100°, to the normals to the second outlet openings.

[0029] To be able to precisely direct the hot gas flows onto the opposing connection surfaces, i.e., the outside of the fabric hose wall and the inside of the folded end section, it is advantageous for the hot gas nozzle to have a first flow channel leading to at least one first outlet opening for a first hot gas flow and a second flow channel leading to at least one second outlet opening for a second hot gas flow, wherein the first flow channel for the first hot gas flow is separate from the second flow channel for the second hot gas flow. Thus, the hot gas is guided separately through the first and second flow channels to the at least one first and second outlet opening, respectively, so that the first and second hot gas flows can be adjusted independently of each other.In this design, at least one first outlet opening can be identical to at least one second outlet opening.

[0030] In a preferred embodiment, the hot gas nozzle has first and second acceleration channel sections leading directly into the first and second outlet openings, respectively. These acceleration channel sections have smaller cross-sectional areas, particularly smaller diameters, than the first and second main channel sections of the first and second flow channel, respectively, leading into the first and second acceleration channel sections. This allows the hot gas to be accelerated before exiting.

[0031] In a preferred embodiment, a guide is provided for guiding the fabric hose section along the hot gas nozzle in the folded-over state of its end region. During operation, the fabric hose section is guided past the hot gas nozzle in the conveying direction. By means of the guide, the inner side of the end region is spaced apart from the outer side of the fabric hose wall such that a gap is formed into which the hot gas nozzle can be inserted. As the fabric hose section passes the nozzle, hot air is discharged into the gap. This exposes the gusset of the fabric hose section formed between the fabric hose wall and the end region to the hot gas.

[0032] In a preferred embodiment, the flat nozzle element, which has the first and second outlet openings, is arranged vertically offset from an adjacent intermediate section of the hot gas nozzle via a vertical offset section, for example, in the form of a kink. A clearance is formed in the area of ​​the vertical offset section. This clearance can be used to freely control the movement of the hot gas nozzle from an operating position for forming the base of the fabric bag piece to an inactive position, for example, to clear a material blockage in the base formation station, and vice versa. The vertical offset section therefore assists demolding during the transition from the operating to the inactive position, for example, when the pressure element described below is present.

[0033] In a preferred embodiment, a heat protection device is provided to protect the fabric hose section from heat exposure caused by the hot gas nozzle wall, which heats up during operation. The heating of the fabric hose section at the connection surfaces is preferably achieved essentially entirely via the hot gas flows from the outlet openings. The heat protection device reduces, and preferably essentially prevents, the heating of the fabric hose section before it reaches the outlet openings. This improves the connection and prevents damage.

[0034] In a preferred embodiment, the heat protection device has insulation, preferably an insulating plate. Preferably, the insulation is provided on the top of a holder, for example, with a retaining plate. For example, the insulation can be bonded to the holder. The holder can be attached to the guide device. During operation, the insulation can rest against the underside of the flat nozzle element. The first fabric hose wall is guided under the insulation, so that the first fabric hose wall is protected from the heat of the hot gas nozzle. The insulation preferably extends from a longitudinal side of the flat nozzle element facing the incoming fabric hose section to a longitudinal section of the flat nozzle element adjacent to the first outlet openings.Advantageously, this design avoids melt marks that could occur without insulation if the fabric hose section rubs against the hot gas nozzle. In this design, the insulation is separate from the hot gas nozzle.

[0035] Depending on the design, the insulation can comprise a high-temperature-resistant insulating material, preferably with mineral fibers or mineral wool, and particularly with a filler. Preferably, the temperature resistance of the high-temperature-resistant insulating material is at least 600°C (Celsius), meaning that the high-temperature-resistant insulating material remains functional at temperatures up to at least 600°C. Particularly preferably, the temperature resistance is selected from a range of 650°C to 1200°C, and especially from 700°C to 900°C. Furthermore, the thermal conductivity of the high-temperature-resistant insulating material is preferably a maximum of 0.5 W / (m*K), and particularly preferably a maximum of 0.15 W / (m*K).

[0036] In another preferred embodiment, the hot gas nozzle is provided at least partially with a heat-resistant coating, preferably a ceramic coating, in particular comprising zirconium. In this embodiment, the heat-resistant coating is integrally formed with the hot gas nozzle, which is made of a different material than the heat-resistant coating. The heat-resistant coating is preferably provided at least on the underside, and preferably also on the top side, of the flat nozzle element. Furthermore, the heat-resistant coating can also cover other sections of the hot gas nozzle.

[0037] In a preferred embodiment, the heat protection device includes a pressure element that holds the first fabric hose wall away from the hot gas nozzle. Preferably, the pressure element prevents the longitudinal or lateral fold from rising as the fabric hose section is conveyed along the hot gas nozzle. This prevents undesirable thermal damage, even in a rear area of ​​the hot gas nozzle where, for example, no insulation or heat-resistant coating is provided.

[0038] The pressure element can be spring-loaded. For example, a spring-loaded plate can be used as the pressure element, which pushes the first fabric hose wall away from the hot gas nozzle. The spring-loaded plate can be arranged at an angle to the horizontal in the operating position.

[0039] Preferably, the pressure element is attached to the guide device.

[0040] Preferably, the guiding device comprises an upper assembly with which the folded end of the fabric hose section is guided from above. The upper assembly may have a guide ramp. Preferably, the guiding device comprises a middle assembly to which the pressure element may be attached. Finally, the guiding device may comprise a lower assembly with which underside guidance can be achieved.

[0041] The hot gas nozzle is preferably made of a temperature-resistant steel alloy, preferably a high-alloy steel that is resistant to high temperatures, corrosion, and strength. The high-alloy steel is preferably nickel-based and also preferably contains chromium. The steel alloy preferably has a temperature resistance selected from the range of 650°C to 1200°C, particularly preferably from the range of 700°C to 900°C.

[0042] In a preferred embodiment, a control and / or regulating device is provided for controlling and / or regulating the first hot gas flow in the first flow channel and / or the second hot gas flow in the second flow channel of the hot gas nozzle.

[0043] To precisely adjust the heat output delivered to the bonding surfaces, the control and / or regulating device, in a preferred embodiment, is designed to control and / or regulate the temperature and / or volume flow of the first and / or second hot gas stream. It is particularly preferred if the control and / or regulating device can control the temperature and volume flow, preferably of the first and second hot gas streams respectively. This embodiment makes it possible to adjust the heat output with high accuracy to the delicate optimum between the quality of the weld joint and the protection of the tape fabric.

[0044] In a preferred embodiment, the control device is designed to control and / or regulate the volume flow of the first hot gas flow by means of a first valve, preferably a first proportional valve, and / or to control and / or regulate the volume flow of the second hot gas flow by means of a second valve, preferably a second proportional valve. The volume flow rates of the first and second hot gas flows can be adjusted, preferably essentially steplessly, by means of the first and second valves, respectively.

[0045] In a preferred embodiment, the control and / or regulating device is configured to control or regulate the first hot gas flow independently of the second hot gas flow and / or the second hot gas flow independently of the first hot gas flow. Thus, for example, the volume flow and / or temperature of the first hot gas flow can be increased without changing the volume flow and / or temperature of the second hot gas flow (or vice versa).

[0046] In a preferred embodiment, a first gas heating unit, preferably a first gas heater cartridge, is provided for forming the first hot gas flow, and a second gas heating unit, preferably a second gas heater cartridge, is provided for forming the second hot gas flow.

[0047] In a preferred embodiment, the hot gas nozzle has a first hot gas supply, preferably a first hot gas supply pipe, which is connected to the first flow channel, preferably via a first intermediate piece. Preferably, the hot gas nozzle has a second hot gas supply, preferably a second hot gas supply pipe, which is connected to the second flow channel, preferably via a second intermediate piece.

[0048] In a preferred embodiment, the hot gas nozzle has a flat nozzle element which has at least one first and at least one second outlet opening on a longitudinal side, wherein the flat nozzle element preferably has at least one first row of first outlet openings, preferably also a second row of first outlet openings, and at least one row of second outlet openings, preferably also a second row of second outlet openings.

[0049] In a preferred embodiment, the first outlet openings of the first row of outlet openings are arranged offset along the longitudinal direction of the flat nozzle element from the first outlet openings of the second row of outlet openings. Thus, the first outlet openings of the first row of outlet openings are not located at the same longitudinal positions as the first outlet openings of the second row of outlet openings. Preferably, the offset is substantially half the longitudinal extent (i.e., the maximum extent along the longitudinal direction of the flat nozzle element) of each first outlet opening.

[0050] It is further preferred that the second outlet openings of the first row of second outlet openings are arranged offset in the longitudinal direction of the flat nozzle element from the second outlet openings of the second row of second outlet openings. Thus, the second outlet openings of the first row of second outlet openings are not arranged at the same longitudinal positions as the second outlet openings of the second row of second outlet openings. Preferably, the offset is substantially half the longitudinal extent (i.e., maximum extent in the longitudinal direction of the flat nozzle element) of the second outlet openings.

[0051] These design methods achieve a better surface distribution of the respective hot gas flow.

[0052] The first row of first exit openings is located closer to the first row of second exit openings than the second row of first exit openings is located to the second row of second exit openings. Thus, the first rows form the inner rows and the second rows form the outer rows.

[0053] In a preferred embodiment, the normals to the first outlet openings of the first row of outlet openings are arranged at an angle of 50° to 140°, preferably 60° to 130°, more preferably 80° to 110°, for example substantially 100°, to the normals to the second outlet openings of the first row of outlet openings. In a preferred embodiment, the normals to the first outlet openings of the second row of outlet openings are arranged at an angle of 50° to 140°, preferably 60° to 130°, more preferably 65° to 80°, for example substantially 70°, to the normals to the second outlet openings of the second row of outlet openings. Preferably, the angle between the first rows is greater than the angle between the second rows. This results in particularly favorable heating.

[0054] In a preferred embodiment, the flat nozzle element has at least one third outlet opening, preferably at least two third outlet openings, for expelling hot gas and / or at least one fourth outlet opening, preferably at least two fourth outlet openings, for expelling hot gas on the end face facing away from the first or second hot gas supply. The normal to the third outlet opening is arranged at an angle, preferably at an angle of 30° to 120°, for example, substantially at a right angle, to the normal to the first outlet opening. The normal to the fourth outlet opening is arranged at an angle, preferably at an angle of 30° to 120°, for example, substantially at a right angle, to the normal to the second outlet opening. Hot gas can be discharged into the area of ​​the bottom fold edge of the fabric hose section via the third or fourth outlet opening.This can further improve soil formation.

[0055] To separate the first from the second hot gas flow, the flat nozzle element, in a preferred embodiment, has a central wall for separating the first and second flow channels, wherein the central wall is preferably arranged substantially centrally between the upper and lower surfaces of the flat nozzle element. During operation, the flat nozzle element can be arranged substantially parallel to the fabric hose wall, onto which the end section of the fabric hose is folded. Preferably, the end section is folded onto the upper fabric hose wall, so that the lower fabric hose wall is free of the folded end section.

[0056] The centers of the outermost first and / or second outlet openings, relative to the longitudinal direction of the flat nozzle element, are each at least 3 centimeters (cm) to 8 cm apart. The maximum width of the folded end section, i.e., its maximum extent in the direction of the longitudinal axis of the fabric hose section, is preferably from 3 centimeters (cm) to 8 cm, preferably from 4 cm to 6 cm.

[0057] In a preferred embodiment, a device is provided for equalizing the outflow of the hot gas from the first and second outlet openings. Preferably, this device comprises at least one first gas guiding element in the first flow channel and / or at least one second gas guiding element in the second flow channel.

[0058] In a preferred embodiment, the first gas guiding element is configured to direct a partial flow of the hot gas to a front end region of the flat nozzle element facing away from a first hot gas supply. Similarly, the second gas guiding element is preferably configured to direct a partial flow of the hot gas to a front end region of the flat nozzle element facing away from a second hot gas supply. For this purpose, the first and second gas guiding elements can be designed as first and second gas guide ribs, respectively, which subdivide the first and second flow channels. This design allows for a better distribution of the hot gas outflow over the length of the flat nozzle element.

[0059] In a preferred embodiment, a pressing device is provided for crimping the end section to the fabric hose wall of the fabric hose section to form the folded bottom. The pressing device is preferably located downstream of the bottom-forming station, viewed in the conveying direction of the fabric hose section. The pressing device crimps the previously hot gas-treated connecting surfaces. By means of the pressing device, the inner side of the folded end section is intimately bonded to the outer side of the fabric hose wall, thus completing the folded bottom.

[0060] In a preferred embodiment, the pressing device for pressing the folded end section to the fabric hose wall has two opposing pressing rollers, between which the fabric hose section can be pressed. The pressing device preferably has at least one pressing drive for driving at least one of the opposing pressing rollers.

[0061] To prepare or interrupt hot gas welding, a movement device is preferably provided for moving the hot air nozzle from an inactive position to an active position, preferably in at least two axes, for example in two mutually perpendicular axes, in particular in a horizontal and a vertical axis.

[0062] In a preferred embodiment, an exhaust air guide element is provided, which redirects the exhaust air from the hot gas nozzle. The exhaust air guide element is particularly useful for directing the exhaust air away from sensitive components, such as seals. Furthermore, the exhaust air can be recycled for reuse as the first and / or second hot gas stream.

[0063] In carrying out the method according to the invention, a first hot gas stream is directed towards the outside of the fabric tube wall of the fabric tube section and a second hot gas stream towards the inside of the end region of the fabric tube section. The associated technical effects and advantages will become apparent from the above description of the soil formation station.

[0064] In a preferred embodiment, the woven hose section comprises a tape fabric made of, preferably stretched, plastic tapes, preferably of semi-crystalline thermoplastic, preferably of polyolefin, for example polypropylene (PP) or polyethylene (PE), or of polyethylene terephthalate (PET). A film, i.e., a homogeneous sheet structure, is preferably applied to the tape fabric. The film can comprise or consist of: polypropylene (PP) or polyethylene

[0065] (PE), preferably extended PP or extended PE, in particular biaxially oriented polypropylene (BOPP) or biaxially oriented polyethylene (BOPE), or polyethylene terephthalate (PET), preferably oriented polyethylene terephthalate, in particular biaxially oriented polyethylene terephthalate (BOPET). The film can be unprinted or printed, e.g., with a motif, wherein, in the case of using a transparent film with a printed motif, preferably the side of the film facing the woven tape is printed (counter-printed). Alternatively to the film, the woven tube section can have a coating applied to the woven tape. The coating can be formed by an extrusion coating that essentially comprises or consists of polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polylactic acid (PLA), and / or mixtures thereof. In this case, the coating is a homogeneous layer on the woven tape.Both the film and the coating are preferably formed from a thermoplastic, sealable, i.e. weldable, polymer.

[0066] In a preferred embodiment, the fabric tube section has a side pleat on each of its opposite longitudinal sides. This allows for the production of side-pleated fabric bags.

[0067] In a preferred embodiment, the fabric tube section is processed by folding the end region of the fabric tube section over itself, i.e., over the adjacent fabric tube wall, at least once, preferably exactly once, and joining the folded end region to the adjacent outer surface of the fabric tube wall to form a folded bottom, preferably a pinch bottom. The invention can be used to produce, on the one hand, a pinch-bottom fabric bag in which at least one of the fabric tube walls has a stepped front edge, a so-called step line, in the end region. On the other hand, the invention can also be used to produce a folded-bottom fabric bag in which the front edges of the fabric tube walls are straight in the end region. This fabric bag is also referred to as a padded bag.

[0068] In a preferred embodiment, the fabric hose section is provided by tearing it off a fabric hose sheet along a tear line (which later forms the leading edges of the folded-over end region). The fabric hose sheet is preferably formed from a flat fabric sheet, which is folded over to form the hose, with longitudinally overlapping sections of the flat fabric sheet being joined together in the overlap area by a longitudinal seam, in particular an adhesive or weld seam.

[0069] To form the tear line, the fabric tubing preferably has perforations, i.e., openings that completely penetrate one of the opposing fabric tubing walls, or weakenings, i.e., indentations that only partially, but not completely, penetrate one of the opposing fabric tubing walls, or a combination of perforations and weakenings, cf. EP 2 117 821 bl.

[0070] The first and / or second hot gas stream melts a portion of the material on the connection surfaces, i.e., the outer surface of the fabric hose wall or the inner surface of the end section. This allows the formation of the weld joint to be prepared, preferably by means of a pressure device described below. In a preferred embodiment, the material on the outer surface of the fabric hose wall, in particular the (BOPP) film, is partially melted by the first hot gas stream, whereas the material on the inner surface of the end section, in particular the woven fabric of the tape, is merely heated by the second hot gas stream but not melted.

[0071] In a preferred embodiment of the method, a film, which in particular comprises or consists of BOPP, BOPE or BOPET, is applied to the outside of the fabric tube wall of the fabric tube section, wherein the inside of the end region of the fabric tube section is formed at least partially, preferably largely, i.e. to more than 50%, by the tape fabric, so that the first hot gas stream is directed onto the film and the second hot gas stream onto the tape fabric.

[0072] In order to enable high-quality hot gas welding without damaging the tape fabric, in a preferred embodiment, the first hot gas stream transfers more heat towards the outside of the fabric hose wall than the second hot gas stream transfers heat towards the inside of the folded end area of ​​the fabric hose piece.

[0073] The device according to the invention for the production of woven bags, preferably fold-bottom woven bags, preferably pinch-bottom woven bags, has a bottom-forming station in one of the above described embodiments.

[0074] In a preferred embodiment, the device includes an unwinding station with which a flat fabric web is unwound as the starting material for the fabric bags. Alternatively, the fabric tube web can already be in tube form.

[0075] In a preferred embodiment, the device further comprises a station for forming tear lines at regular intervals along the fabric sheet or fabric tube. The tear lines are preferably formed by perforations and / or weakenings, as described above. The station preferably includes at least one laser unit for weakening or perforating the fabric sheet or fabric tube along the tear lines. Alternatively, the station for forming the perforations can have a roller equipped with perforating blades that interact with a counter-roller. The tear lines preferably have a stepped shape, which forms a sealing closure, i.e., a gasket, in the final pinch-bottom fabric bag to prevent the escape of filling material. The details of the stepped line are explained, for example, in EP 2 117 821 Bl.

[0076] In a preferred embodiment, the device includes a tube forming station with which the fabric web is folded over and processed into a fabric tube web with a longitudinal seam. The tube forming station can also be configured to form longitudinal folds on the long sides of the fabric web.

[0077] The hot gas nozzle in one of the above-described versions can also be used to form this longitudinal seam. The tube forming station can also be combined with a different bottom forming station than described above, in particular with a different connecting device for joining the end section to the fabric tube wall to form the folded bottom.Thus, the present disclosure also relates to a tube forming station comprising: a device for folding a fabric web and for processing the folded fabric web with a longitudinal seam at overlapping sections of the folded fabric web to form a fabric tube web, and a hot gas nozzle for ejecting hot gas, preferably hot air, between overlapping sections of the folded fabric web, wherein the hot gas nozzle has at least a first outlet opening for ejecting hot gas in the direction of one of the overlapping sections of the folded fabric web and at least a second outlet opening for ejecting hot gas in the direction of another of the overlapping sections of the folded fabric web. The hot gas nozzle can be configured in one of the embodiments described above.

[0078] Furthermore, the present disclosure relates to a device for manufacturing woven bags, preferably folded-bottom woven bags, preferably pinch-bottom woven bags, with such a tube-forming station. This device can also include a bottom-forming station with a connecting device for joining a folded end section of a woven tube piece to a woven tube wall of the woven tube piece.

[0079] In a preferred embodiment, the device has a rotary station downstream of the tear-off station in the transport direction for rotating the fabric hose sections by substantially 90° from a longitudinal transport position to a transverse transport position. Upstream of the rotary station, the longitudinal axes of the fabric hose sections are arranged substantially in the transport direction, and downstream of the rotary station, they are arranged substantially perpendicular to the transport direction.

[0080] In a preferred embodiment, the device has a delay station in the transport direction after the rotary station to delay the fabric hose pieces for further processing.

[0081] In a preferred embodiment, the device has, in the transport direction after the tear-off station, preferably in the transport direction after the delay station, the bottom formation station for forming fold-over bottoms, preferably pinch bottoms, on the fabric tube pieces, so that fold-over bottom fabric bags, preferably pinch bottom fabric bags, are obtained.

[0082] In a preferred embodiment, the device has a depositing station for depositing the folding bottom fabric bags, preferably the pinch bottom fabric bags, in the transport direction after the bottom formation station.

[0083] According to the invention, a method for manufacturing a woven bag, preferably a fold-over bottom woven bag, preferably a pinch-bottom woven bag, can also be carried out, in which the bottom formation is carried out according to one of the embodiment variants described above.

[0084] The method for manufacturing the fabric bag can further comprise at least one of the following steps, preferably all of the following steps, preferably sequentially: i. Unwinding a fabric sheet as starting material; ii. Forming tear lines at regular intervals in the fabric sheet, preferably by perforations and / or weakening, preferably by laser cutting, of the fabric sheet; iii. Folding over the fabric sheet and joining an overlap area of ​​the folded fabric sheet with a longitudinal seam, so that a fabric tube sheet is formed; iv. Tearing off the fabric tube piece from the fabric tube sheet; v.Rotating the fabric tube section by substantially 90° from a longitudinal transport position in which the longitudinal axis of the fabric tube section (from open end to open end) is arranged substantially in one transport direction, to a transverse transport position in which the longitudinal axis of the fabric tube section is arranged substantially perpendicular to the transport direction, vi. Forming a folding bottom, preferably a pinch bottom, on the fabric tube section, so that a folding bottom fabric bag, preferably a pinch bottom fabric bag, is obtained.

[0085] In a preferred embodiment, longitudinal folds are formed on the longitudinal sides of the fabric tube sheet, preferably during tube formation.

[0086] In a preferred embodiment, the conveying speed of the fabric hose section is reduced after rotation (step v.) and before forming the folded bottom (step vi.).

[0087] The invention is further explained below with reference to an embodiment illustrated in the drawings.

[0088] Fig. 1 shows a schematic representation of a pinch sack production plant in which a soil formation station according to the invention is used.

[0089] Fig. 2 shows in detail the soil formation station of Fig. 1.

[0090] Fig. 3, Fig. 6 and Fig. 7 show details of a hot gas nozzle of the soil formation station of Fig. 2.

[0091] Fig. 4 shows a section of a fabric tube wall. Fig. 5 shows the end of a fabric tube section for forming a pinch bottom with the bottom-forming station of Fig. 1 and Fig. 2, respectively.

[0092] Fig. 8 shows another embodiment of the hot gas nozzle.

[0093] Fig. 9 and Fig. 10 show another embodiment of the soil formation station with the hot gas nozzle according to Fig. 8.

[0094] Fig. 11A and Fig. 11B show another embodiment of the hot gas nozzle.

[0095] As can be seen in Fig. 1, the device 1 has a winding station 2 with which a flat fabric web 3 is unwound. The flat fabric web 3 has a tape fabric made of stretched plastic tapes, for example predominantly polypropylene. A film, preferably predominantly made of BOPP, is preferably applied to one side of the tape fabric.

[0096] As can be seen in Fig. 1, the device 1 further comprises a station 4 for forming tear lines 5 at regular intervals along the fabric sheet 3. The tear lines 5 are formed by weakening or perforations in the material. The station 4 preferably comprises at least one perforation unit 6, here a laser unit, for weakening or perforating the fabric sheet 3 along the tear lines 5. Alternatively, the station 4 can have a roller equipped with perforating blades for forming the perforations, which interact with a counter roller (not shown). The tear lines 5 preferably have a stepped shape, which forms a sealing closure of the final pinch-bottom fabric bag.

[0097] As can be seen from Fig. 1, the device 1 further comprises a tube forming station 7, with which the fabric sheet 3 is folded over along its longitudinal axis, an overlap area is formed, and this overlap area is provided with a longitudinal seam 8 to form a fabric tube sheet 9. Longitudinal folds 9A can also be provided (see Fig. 5).

[0098] As can be seen from Fig. 1, the device 1 further has a tear-off station 10, with which the fabric tube sheet 9 is divided into individual fabric tube pieces 11 which are open at their end regions.

[0099] As can be seen from Fig. 1, the device 1 further comprises an intermediate transport and discharge station 12 for the intermediate transport of the fabric hose pieces 11 and the discharge of ejected material, i.e. defective or damaged fabric hose pieces.

[0100] As can be seen from Fig. 1, the device 1 further comprises a rotary station 13 for rotating the fabric tube sections 11 by 90° from a longitudinal transport position, in which the longitudinal axes of the fabric tube sections 11 are arranged in the transport direction 14A, to a transverse transport position, in which the longitudinal axes of the fabric tube sections are arranged in the transverse direction 14B perpendicular to the transport direction 14A, and still in the transport plane. Thus, the open ends of the fabric tube sections 11 are located at the front and rear ends before the rotary station, and at the sides of the fabric tube sections 11 after the rotary station.

[0101] As can be seen from Fig. 1, the device 1 further has a delay station 15 for delaying the fabric hose pieces 11 for further processing.

[0102] As can be seen from Fig. 1, the device 1 further has a bottom formation station 16 for forming fold-over bottoms, preferably pinch bottoms 17, on the fabric tube pieces 11, so that fold-over bottom fabric bags 18, preferably pinch bottom fabric bags, are obtained.

[0103] As can be seen in Fig. 1, the device 1 further comprises a depositing station 19 for depositing the fabric bags 18. As shown in Fig. 2, the bottom-forming station 16 has a conveying device 20 for conveying the fabric tube section 11 in a conveying direction 21 corresponding to the transport direction 14A. The fabric tube section 11 has a first 11A and a second fabric tube wall 11B, which are fed to the bottom-forming station 16 in a flat, overlapping state. A folding device 22 folds over one of the open end regions of the fabric tube section 11. Preferably, the short side of the fabric tube section, which forms the bottom end on the fabric bag, is folded over. In this process, one of the open end regions of the fabric tube section, which is formed from the end sections of the first 11A and the second fabric tube wall 11B, is folded over to a connecting section 11C of the first fabric tube wall 11A (see .Figures 2 and 5 .

[0104] Furthermore, a hot gas nozzle 23 is provided, with which hot gas, preferably hot air, is expelled between the outside of the connecting section 11C of the first fabric hose wall 11A and the inside of the end region of the fabric hose piece 11 facing the connecting section (see Fig. 2 and Fig. 3).

[0105] As can be seen in Figures 2 and 3, a guide device 24 moves the end section of the fabric hose section 11 past the hot gas nozzle 23 in its folded state, i.e., folded over by essentially 180° (see Figures 1, 2, and 3). The guide device 24 spaced the inside of the end section from the outside of the adjacent first fabric hose wall 11A, creating a gap HD. The hot gas nozzle 23 was inserted into this gap HD. When the fabric hose section 11 was conveyed in the conveying direction 21, the hot gas was discharged into the gap HD by the hot gas nozzle 23 (see Figures 2 and 3). The hot gas partially melted the surface of the material being conveyed.

[0106] A pressing device 25 presses the end region against the first fabric hose wall HA of the fabric hose section 11, thus forming the thermal weld connection between the folded end region and the connecting section HC. As shown in Fig. 2, the pressing device 25 has a first, here a lower, pressing roller 25A and a second, here an upper, pressing roller 25B. Following the pressing device 25 is the fabric bag 18 with the folded bottom, which, when using a stepped tear-off line 5 as a pinch bottom (see Fig. 1).

[0107] According to the invention, as shown in Fig. 3, the hot gas nozzle 23 has at least a first (lower) outlet opening 26, with which a first hot gas stream 23A is expelled towards the outside of the connecting section 11C of the first fabric hose wall 11A, and at least a second (upper) outlet opening.

[0108] 27, with which a second hot gas stream 23B is expelled towards the inside of the folded end area of ​​the fabric hose piece 11.

[0109] The woven tube section 11 has a woven tape 28 which is provided on the outside, i.e., on the visible side of the finished bag, with a film 29, here made of biaxially oriented polypropylene (BOPP) (see Fig. 4). The end region of the woven tube section 11 has, preferably at least on the first, inner wall 11A of the woven tube, a recess 30 which results from the stepped tear line 5 and is formed by the steps (shape) 5A (cf. Fig. 1 and 5). In the area of ​​the recess 30, the woven tape 28 is therefore exposed on the inside of the second (outer, with respect to the folded-over state of the end region) wall 11B of the woven tube.

[0110] Thus, as can be seen in conjunction with Figures 3 and 5, a first hot gas stream is expelled by the hot gas nozzle 23 through at least one first outlet opening 26 onto the outside of the connecting section 11C of the first fabric hose wall 11A, which has the recess 30 in the folded end region (see Figure 5). A second hot gas stream passes through the recess 30 via at least one second outlet opening 27 to the inside of the second, here outer, fabric hose wall 11B, which is the lower fabric hose wall in the remaining fabric hose section 11 (excluding the end region) (see Figures 2 and 3). The fabric strands of the tapered fabric lie on the inside of the end section of the second fabric hose wall 11B.

[0111] 28 free in front (see Fig. 3 and Fig. 4). To improve the welded joint of the folded bottom without affecting the woven fabric 28, the hot gas nozzle 23 is designed to expel hot gas with a larger volume flow and / or a higher temperature towards the outside of the woven tube wall of the woven tube section 11 via at least one first outlet opening 26 than via at least one second outlet opening 27 towards the inside of the end region of the woven tube section 11 (see Fig. 3). This results in less heat being applied to the woven fabric 28 than to the comparatively less sensitive film 29 (see Fig. 4).

[0112] As schematically shown further in Fig. 2, Fig. 3, and partly also in Fig. 6, the hot gas nozzle 23 has a first flow channel 31 leading to at least one first outlet opening 26 for a first hot gas flow and a second flow channel 32 leading to at least one second outlet opening 27 for a second hot gas flow. The first flow channel 31 for the first hot gas flow is completely separated from the second flow channel 32 for the second hot gas flow.

[0113] In the example shown, a control and / or regulating device 33 is provided (see Fig. 2) for controlling and / or regulating the first hot gas flow in the first flow channel 31 and / or the second hot gas flow in the second flow channel 32 of the hot gas nozzle 23. The control and / or regulating device 33 is designed to control and / or regulate the temperature and / or the volume flow of the first and / or the second hot gas flow, preferably independently of each other.

[0114] As can be seen from Fig. 2, the control and / or regulating device 33 is connected to a first valve 34, preferably a first proportional valve, and / or to a second valve 35, preferably a second proportional valve. By adjusting the first valve 34 or the second valve 35 with the control and / or regulating device 33, the volume flows of the first and second hot gas flows, respectively, can be adjusted, preferably essentially steplessly. As further shown schematically in Fig. 2, the control and / or regulating device 33 is also provided with a first gas heating unit 36, preferably with a first gas heater cartridge, for generating the first hot gas flow, and with a second gas heating unit 37, preferably with a second gas heater cartridge, for generating the second hot gas flow. By adjusting the first valve 36 or the second valve 35, the volume flows of the first and second hot gas flows can be adjusted.The temperature of the first or second hot gas flow can be set using the second gas heating unit 37 with the control and / or regulating device 33.

[0115] In the example shown, the hot gas nozzle 23 has a flat nozzle element 38, which has at least one first outlet opening 26 and at least one second outlet opening 27 on one longitudinal side (see Figures 3, 6 and 7). As shown in detail in Figure 7, the flat nozzle element 38 has at least one first row 39 of first outlet openings 26, and here also a second row 40 of first outlet openings 26, and at least one first row 41 of second outlet openings 27, and here also a second row 42 of second outlet openings 27. The first 26 and second outlet openings 27 are separate from each other. The angle between the first row 39 of first outlet openings 26 and the first row 41 of second outlet openings 27 is larger in the example shown than the angle between the second row 40 of first outlet openings 26 and the second row 42 of second outlet openings 27 (see Fig. 3 and Fig. 7).

[0116] As can be seen from Figures 3 and 6, the flat nozzle element 38 has a central wall 43 which separates the first flow channel 31 from the second flow channel 32. In the example shown, the central wall 43 extends essentially centrally between the upper and lower surfaces of the flat nozzle element 38.

[0117] Fig. 6 shows the hot gas nozzle 23 in detail, using the underside of the flat nozzle element 38 as an example, in relation to the first flow channel 31 and the first hot gas flow 23A. The top of the flat nozzle element 38 and the routing of the second hot gas flow 23B to the second outlet openings 27 can be designed analogously. A first gas guiding element 44 is arranged in the first flow channel 31, which is configured to guide a partial flow 23C, i.e., a portion but not the entire first hot gas flow 23A, of the hot gas to a front end region of the flat nozzle element 38, which is located furthest away from a first hot gas supply 45. The second gas guiding element is designed to direct a partial flow, i.e., a part but not the entire second hot gas flow, of the hot gas to a front end region of the flat nozzle element 38, which faces away from a second hot gas supply, i.e.furthest away is (not shown).

[0118] In the example shown, first gas guide vanes 46 are arranged in the first flow channel 31 (see Fig. 6) and corresponding second gas guide vanes are arranged in the second flow channel 32, which contribute to the homogenization of the volume flow as well as the temperature of the first and second hot gas flows over the length of the flat nozzle element 38.

[0119] As shown in Figure 7, the flat nozzle element 38 in a preferred embodiment has at least a third outlet opening 47 and preferably at least a fourth outlet opening 48 on the end face facing away from the first or second hot gas supply, for ejecting hot gas into the area of ​​the folded edge 49 of the fabric hose wall 11A, 11B (see Fig. 5).

[0120] Fig. 8 shows another embodiment of the hot gas nozzle 23. In this embodiment, the flat nozzle element 38, which has the first 26 and second outlet openings 27, is offset from an adjacent intermediate section 51 of the hot gas nozzle 23 by a vertical offset section 50, here in the form of a kink. Due to the vertical offset section 50, a clearance 52 is formed below the intermediate section 51 opposite the underside of the flat nozzle element 38. This clearance 52 can be used to release the movement of the hot gas nozzle 23 from the operating position shown to an inactive position, in which the hot gas nozzle 23 is removed from the guide assembly 24, which comprises a lower assembly 24A, an upper assembly 24B, and a middle assembly 24C (see Fig. 9 and Fig. 10). Due to the free space 52, the movement of the hot gas nozzle 23 from the operating position shown to the rest position away from the guide device 24 is controlled.Inactivation facilitates or enables it.

[0121] In the example shown, the middle assembly 24C of the guide device 24 (see Fig. 10) serves to create an intermediate space in order to fold the floor to be produced by 180° shortly before the press rollers 25, cf. Fig. 2, so that the hot gas nozzle 23 can heat the upper and lower layers of the fabric floor or melt the BOPP coating and the floor can then be pressed.

[0122] Furthermore, the upper assembly 24B and the middle assembly 24C of the guide device 24 can be designed to be movable for demolding when the device 1 is at a standstill.

[0123] Fig. 9 shows the hot gas nozzle 23 in the configuration according to Fig. 8 in the installed state in the soil formation station 16.

[0124] As can be seen in Fig. 9, in the illustrated example, preferably below the flat nozzle element 38, an insulation 55, preferably an insulating plate, is provided which reduces, and in particular essentially completely prevents, the heating of the fabric passing by the hot gas nozzle 23 before it reaches the first outlet openings 26 of the hot gas nozzle 23. In the illustrated example, the insulation 55 is arranged on its upper side on a support 56, here a retaining plate, which in the illustrated example is attached to the central assembly 24C of the guide device 24. In this embodiment, the insulation 55 is not rigidly connected to the hot gas nozzle 23, but preferably rests against the underside of the flat nozzle element 38. Thus, the insulation 55 forms a separate heat shield from the hot gas nozzle 23.In the example shown, the insulation 55 extends from a longitudinal side of the flat nozzle element 38 facing the incoming fabric hose section 11 to a longitudinal section of the flat nozzle element 38 adjacent to the first outlet openings 26. Thus, the fabric hose section 11 is protected by the insulation 55 from the heat exerted by the wall of the hot gas nozzle 23, which heats up during operation, until the fabric hose section 11 reaches the first outlet openings 26, through which hot gas is expelled towards the outside of the first fabric hose wall 11A. This prevents melt marks that could occur without the insulation 55 if the fabric hose section 11 came into contact with the hot gas nozzle 23.This problem can occur particularly in the area of ​​the longitudinal fold 9A (so-called "gusset") and is reliably solved by the insulation 55 even at a preferred hot gas temperature of more than 500°C, preferably more than 600°C, for example more than 650°C and preferably less than 800°C, preferably less than 760°C, and particularly preferably less than 710°C, for example less than 685°C. Depending on the embodiment, the insulation 55 can comprise a high-temperature-resistant insulating material, preferably mineral fibers or mineral wool.

[0125] Fig. 10 shows a pressure element 53, for example a spring plate, for pressing the first fabric hose wall 11A against a lower guide surface 54 of the lower assembly 24A of the guide device 24. Thus, the pressure element 53 presses the fabric hose section 11 downwards. The pressure element 53, located in the area of ​​the intermediate section 51 of the hot gas nozzle 23 and preferably not insulated, serves to hold the fabric down to prevent the longitudinal or lateral fold 9A from rising when the fabric edge passes through. This also prevents undesirable thermal damage in the rear area of ​​the hot gas nozzle 23, which is not protected by the insulation 55.

[0126] Figures 11A and 11B show a further embodiment in which the hot gas nozzle 23 is provided section by section with a heat-resistant coating 57, preferably with a ceramic coating, in particular comprising zirconium. The heat-resistant coating preferably extends at least on the underside, and preferably also on the top side, of the flat nozzle element 38. In addition, the heat-resistant coating can be provided on the top and / or underside of the intermediate section 51. Reference list:

[0127] 1 Device

[0128] 2 processing stations

[0129] 3 Fabric flat sheet

[0130] 4 Station

[0131] 5 tear-off lines

[0132] 5A Step Form

[0133] 6 perforation unit

[0134] 7 Hose formation station

[0135] 8 Longitudinal seam

[0136] 9 Fabric hose conveyor

[0137] 9A Fold lengthwise

[0138] 10 Tear-off stations

[0139] 11 piece of fabric hose

[0140] 11A first fabric hose wall

[0141] 11B second fabric hose wall

[0142] 11C Connection section of the first fabric tube wall

[0143] HD gap

[0144] 12 Discharge Station

[0145] 13 Rotating Station

[0146] 14A Transport direction

[0147] 14B Transverse direction

[0148] 15 delay stations

[0149] 16 Soil formation station

[0150] 17 Pinch bottoms

[0151] 18 Umf old soil fabric bags

[0152] 19 Departure Station

[0153] 20 funding institution

[0154] 21 Direction of conveyance

[0155] 22 Folding device

[0156] 23 Hot gas nozzle

[0157] 23A first hot gas flow

[0158] 23B second hot gas stream

[0159] 23C Partial flow of the first hot gas flow

[0160] 24 Guide system

[0161] 24A Lower assembly of the guide device

[0162] 24B Upper assembly of the guide device

[0163] 24C Middle assembly of the guide device

[0164] 25 Pressure device A First pressure roller B Second pressure roller First outlet opening Second outlet opening Woven fabric Film Recess First flow channel Second flow channel Control device First proportional valve Second proportional valve First gas heating unit Second gas heating unit Flat nozzle element First row of first outlet openings Second row of first outlet openings First row of second outlet openings Second row of second outlet openings Center wall First gas guide element First hot gas supply First gas guide ribs Third outlet opening Fourth outlet opening Folding edge Height offset section Intermediate section Clearance Pressure element Guide surface I Insulation Bracket Heat protection coating

Claims

Claims:

1. Bottom formation station (16) for forming a folded bottom, preferably a pinch bottom (17), on a fabric tube section (11) with a tape fabric (28) made of plastic tape, preferably substantially of semi-crystalline thermoplastic, preferably of polyolefin, for example polypropylene (PP) or polyethylene (PE), or of polyester, for example polyethylene enterephthalate (PET) or polylactic acid (PLA), comprising: a conveying device (20) for conveying the fabric tube section in the conveying direction (21), a folding device (22) for folding an end region of the fabric tube section (11) onto a first fabric tube wall (11A) of the fabric tube section, a hot gas nozzle (12) for ejecting hot gas, preferably hot air, between the outside of the first fabric tube wall (11A) of the fabric tube section (11) and the inside of the end region of the fabric tube section (11), characterized in thatthat the hot gas nozzle (23) has at least one first outlet opening (26) for expelling hot gas towards the outside of the first fabric tube wall (11A), wherein the outside of the first fabric tube wall (11A) is preferably formed by a film (29) applied to the tape fabric, preferably comprising polypropylene (PP), particularly preferably comprising oriented polypropylene, in particular comprising biaxially oriented polypropylene (BOPP), or polyethylene (PE), particularly preferably comprising oriented polyethylene, in particular comprising biaxially oriented polyethylene (BOPE), or polyethylene terephthalate (PET), particularly preferably comprising oriented polyethylene terephthalate, in particular comprising biaxially oriented PET (BOPET), and at least one second outlet opening (27) for expelling hot gas towards the inside of the end region of the fabric tube section (11), wherein the inside of the end region preferably comprises at least, is formed section by section by the ligamentous tissue (28), exhibits .

2. Soil formation station (16) according to claim 1, characterized in that the hot gas nozzle (23) is designed to expel hot gas with a larger volume flow and / or a higher temperature via the at least one first outlet opening (26) towards the outside of the first fabric tube wall (11A) of the fabric tube section (11) than via the at least one second outlet opening (27) towards the inside of the end region of the fabric tube section (11).

3. Soil formation station (16) according to claim 1 or 2, characterized in that the at least one first outlet opening (26) is designed differently from the at least one second outlet opening (27).

4. Soil formation station (16) according to claim 1 or 2, characterized in that the hot gas nozzle (23) has a first flow channel leading to at least one first outlet opening (26). (31) for a first hot gas flow and a second flow channel leading to at least a second outlet opening (32) for a second hot gas flow, wherein the first flow channel (31) for the first hot gas flow is separated from the second flow channel (32) for the second hot gas flow.

5. Soil formation station (16) according to claim 4, characterized in that a control and / or regulating device (33) is provided for controlling and / or regulating the first hot gas flow in the first flow channel (31) and / or the second hot gas flow in the second flow channel (32) of the hot gas nozzle (23).

6. Soil formation station (16) according to claim 5, characterized in that the control and / or regulating device (33) is designed to control and / or regulate the temperature and / or volume flow of the first and / or the second hot gas flow.

7. Soil formation station (16) according to claim 5 or 6, characterized in that the control and / or regulating device (33) is configured to control or regulate the first hot gas flow independently of the second hot gas flow and / or the second hot gas flow independently of the first hot gas flow.

8. Soil formation station (16) according to one of claims 1 to 7, characterized in that the hot gas nozzle (23) has a flat nozzle element (38) which has on a longitudinal side at least one first (26) and at least one second outlet opening (27), wherein the flat nozzle element (38) preferably has at least one first row (39) of first outlet openings (26), preferably also a second row (40) of first outlet openings (26), and at least one first row (41) of second outlet openings (27), preferably also a second row (42) of second outlet openings (27).

9. Soil formation station (16) according to claim 8, characterized in that the flat nozzle element (38) has a central wall (43) for separating the first (31) and the second flow channel (32), wherein the central wall (43) is preferably arranged substantially centrally between the upper and lower sides of the flat nozzle element (38).

10. Soil formation station (16) according to claim 8 or 9, characterized in that at least a first gas guiding element (44) is arranged in the first flow channel (31) and / or at least a second gas guiding element is arranged in the second flow channel (32).

11. Soil formation station (16) according to claim 10, characterized in that the first (44) and / or the second gas guiding element is configured to guide a partial flow of the hot gas to a front end region of the flat nozzle element (38) facing away from a first hot gas supply (45) or from a second hot gas supply.

12. Soil formation station (16) according to one of claims 8 to 11, characterized in that the flat nozzle element (38) is arranged vertically offset from an adjacent intermediate section (51) of the hot gas nozzle (23) via a height offset section (50), for example in the form of a kink.

13. Soil formation station (16) according to one of claims 1 to 12, characterized in that a heat protection device is provided to protect the fabric hose section (11) from heat exposure caused by the wall of the hot gas nozzle (23) which heats up during operation.

14. Soil formation station (16) according to claim 13, characterized in that the heat protection device has insulation (55), preferably an insulating plate.

15. Soil formation station (16) according to one of claims 1 to 14, characterized in that the hot gas nozzle (13) is provided at least partially with a heat protection coating (57), preferably with a ceramic coating, in particular comprising zirconium.

16. Soil formation station (16) according to one of claims 13 to 15, characterized in that the heat protection device has a pressure element (53) which keeps the first fabric hose wall (11A) away from the hot gas nozzle (23).

17. Method for forming a folded bottom on a fabric tube section (11) with a tape fabric (28) made of plastic tape, preferably of semi-crystalline thermoplastic, preferably of polyolefin, for example polypropylene, preferably with the bottom formation station according to one of claims 1 to 16, comprising the steps: Conveying the fabric hose section (11) in the conveying direction (21) , Folding over an end area of ​​the fabric tube piece (11) onto one of two opposite fabric tube walls (11A, 11B) of the fabric tube piece (11) , Ejections of hot gas, preferably hot air, between the outer surface of the fabric hose wall (11A) of the fabric hose section (11) and the inside of the end region of the fabric hose piece (11) , characterized in that a first hot gas stream is directed to the outside of the fabric hose wall (11A) of the fabric hose piece (11) and a second hot gas stream is directed to the inside of the end region of the fabric hose piece (11).

18. Method according to claim 17, characterized in that a film (29), in particular a BOPP film, is applied to the outside of the fabric tube wall (11A) of the fabric tube section (11), wherein the inside of the end region of the fabric tube section (11) is formed at least partially by the woven tape (28), so that the first hot gas stream is directed onto the film (29) and the second hot gas stream onto the woven tape (28).

19. Method according to claim 17 or 18, characterized in that the first hot gas stream transfers a greater heat output to the outside of the fabric hose wall than the second hot gas stream transfers to the inside of the folded end region of the fabric hose piece (11).

20. Device (1) for the production of woven bags, preferably fold-bottom woven bags (18), preferably pinch-bottom woven bags, comprising: a bottom-forming station (16) according to one of claims 1 to 16.

Images