Tear-off station, and method for tearing off a section of a woven tubular web

Abstract

The invention relates to a tear-off station (10) for tearing off a section (11) of a woven tubular web (9) along a tear-off line (5), the tear-off station comprising: a draw-in unit (20) for drawing in the woven tubular web (9) at a draw-in speed; a tear-off unit (21) by means of which the woven tubular web section (11) is torn off from the woven tubular web (9) along the tear-off line (5); and an advancing unit (22) which is designed to advance a front region of the woven tubular web (9), in a clamped state, at an advancing speed while the woven tubular web section (11) is being torn off along the tear-off line (5) behind the front region of the woven tubular web (9).

Description

[0001] Tear-off station and method for tearing off a section of fabric hose

[0002] The invention relates to a tear-off station for tearing off a piece of fabric hose from a fabric hose web along a tear-off line, comprising: a feed unit for feeding in the fabric hose web at a feed rate, a tear-off unit with which the piece of fabric hose is torn off the fabric hose web along the tear-off line.

[0003] Furthermore, the invention relates to a method for tearing off a piece of fabric tubing from a fabric tubing web along a tear line, comprising the steps:

[0004] Pulling in the fabric tubing at a pull-in speed ,

[0005] Tearing off the fabric hose section along the tear line from the fabric hose sheet.

[0006] Finally, the invention relates to a device for the manufacture of woven bags, preferably fold-bottom woven bags, preferably pinch-bottom woven bags.

[0007] EP 2 599 617 Bl describes the production of pinch-bottom woven bags, which, in addition to an attractive appearance, offer the necessary stability for packaging products such as pet food in the consumer sector. The production process begins with the unwinding of a web of material from a reel at a winding station. The web material is a woven fabric made of stretched polyolefin, onto which a printable film is applied. After unwinding, the web passes through a pre-feed station before entering a perforation station, where lasers create perforations along a perforation line. The perforated web then enters a tube-forming station, where the tube cross-section is formed. The tube is created from the flat web by guiding it over a series of plates and rollers, folding over the sides of the web.In the area where the edges of the web now overlap, an area of ​​overlapping material is created. During tube formation, side gussets can also be formed in the tube, resulting in the production of gusseted bags. During further transport, longitudinal gluing is carried out in the overlapping material area at a longitudinal gluing station. Finally, the tube web enters a tear-off station where it is subjected to longitudinal forces, separating the web into tube sections. In this state of the art, double belt conveyors are proposed for tearing off the tube sections. The tube sections are then conveyed along their longitudinal axes to a rotating and deflecting station, where they are rotated on a rotary table. Subsequently, the longitudinal axes of the tube sections are aligned perpendicular to their transport direction.In a station for forming pinch bottoms, one end of the hose section is heated with a hot air nozzle and folded over the hose wall. The resulting bottom is then clamped between press rollers. The finished bags are stacked in a storage station.

[0008] However, with the current state of the art, the problem can arise that the hose sections are no longer in the desired orientation parallel to the transport direction after tearing. Due to the stretching processes during tearing, the hose sections can become misaligned. This problem has been observed particularly with fabric hoses, which are formed by folding over a flat material and creating a longitudinal seam. Furthermore, the current state of the art cannot always adequately ensure that the hose sections are pulled off the tear-off station at the desired intervals. Such deviations in orientation and spacing are, however, detrimental to the further processing of the hose sections.Precise removal of the hose segments from the break-off station is particularly critical when these segments are subsequently fed into a soil formation station, where a visually appealing and dense soil is to be formed. This requires high accuracy regarding the alignment and position of the hose segments. If a rotary station is positioned before the soil formation station to rotate the hose segments by 90°, this rotation can introduce an additional inaccuracy that may be superimposed on the deviation from the break-off unit. This can further complicate soil formation.

[0009] German patent DE 1 436 785 describes a different type of machine for producing flat bags from a web formed into a tube. However, this machine does not produce pinch-bottom woven bags, for which higher tearing forces would be required. In this prior art, the material web is periodically held in place by a pair of rollers, which interact with a special pair of rollers for tearing. A second pair of tear-off rollers follows.

[0010] From GB 2, 324, 998 A, a device for separating hose segments from a hose sheet provided with transverse perforation lines is known. The device has a holding unit with endless conveyor belts running over upper and lower deflection rollers. The hose sheet then enters a tear-off unit, which also has conveyor belts running around deflection rollers. These conveyor belts run at least temporarily at a higher speed than the holding unit, so that tearing occurs along the transverse perforation lines between the holding and tear-off units. A device is also provided between the holding and tear-off units with which an initial tear can be formed at the perforation line.

[0011] In contrast, the object of the present invention is to alleviate or eliminate at least some disadvantages of the prior art. The invention preferably aims to create a tear-off station and a method for tearing off a piece of fabric tubing, with which the torn pieces of fabric tubing can be precisely peeled off in the desired orientations and intervals for further processing, in particular in a soil formation station.

[0012] This problem is solved by a tear-off station according to claim 1, a method according to claim 12, and a device according to claim 15. Preferred embodiments are specified in the dependent claims. The tear-off station according to the invention has a pre-traction unit configured to advance a front portion of the fabric tube in a clamped state at a predetermined pre-traction speed, while the fabric tube section is torn off along the tear-off line behind the front portion of the fabric tube.

[0013] With the preferential unit according to the invention, the front portion of the fabric tube web, viewed in the transport direction, is advanced in a clamped state and at a predetermined feed rate, so that the position and orientation of the front portion of the fabric tube web in the transport direction within a transport plane, in the direction perpendicular to the transport direction within the transport plane (i.e., in the transverse direction), and in the direction perpendicular to the transport plane are essentially precisely determined, while the fabric tube section is torn off along the tear line, which forms the rear end of the fabric tube section. This design has the advantage that the position and orientation of the front portion of the fabric tube web are not affected by the tearing process. The tearing unit causes the fabric tube web to stretch in the area of ​​the tear line during the tearing process.The feed unit holds the leading edge of the fabric tube web, which becomes the leading edge of the fabric tube section upon tearing, in the desired position and advances the leading edge at the desired feed rate, so that the fabric tube section, in its torn state, can be precisely transferred to the next station, preferably a rotary station described below. In contrast, in the prior art, the leading edge of the fabric tube web was free, meaning that the tearing process could change the position and orientation of the fabric tube section in an undefined manner. This had the significant disadvantage that the position and orientation of the fabric tube section had to be readjusted for the next processing step, or processing at the next station was impaired.This problem is largely solved by the preferential unit according to the invention, since any stretching of the fabric tube during tearing can no longer affect the front area of ​​the fabric tube, which is precisely guided by the preferential unit. The invention is particularly advantageous if the fabric tube section has a longitudinal seam extending in the transport direction. Such a longitudinal seam can join folded-over, longitudinally overlapping sections of a fabric flat sheet together in the overlap area during tube formation. This longitudinal seam causes an asymmetry of the fabric tube section, which is particularly susceptible to changes in the orientation of the fabric tube section during tearing. Without the preferential unit according to the invention, the forces during tearing can be distributed differently to the sides of the fabric tube with and without the front.Without a longitudinal seam, tearing could cause the fabric tube section to tilt, which hampered further transport and processing. The preferred unit according to the invention prevents such tilting by pulling the front section of the fabric tube web forward in the desired orientation in a clamped position. Preferably, the front transverse edge of the fabric tube section is held by the preferred unit in the transverse direction, i.e., in a direction essentially perpendicular to the transport direction in the transport plane, so that the longitudinal axis of the fabric tube section, which runs from open end to open end, extends after the tear-off unit essentially in the transport direction.

[0014] Due to the higher accuracy of the tear-off station according to the invention, an alignment station in the transport direction after the tear-off station, in particular after a rotary station, can be relieved of some load, or an alignment station can be dispensed with altogether.

[0015] In a preferred embodiment, the feed unit has a first feed roller. Preferably, the feed unit has a second feed roller to form a feed roller pair, wherein the front portion of the fabric hose web is advanced in the transport direction between the first and second feed rollers in the clamped state. The feed unit preferably has a feed drive with which the first and / or the second feed roller is driven. The first feed roller can have several feed roller segments, which are mounted on an axis that preferably extends substantially in the transverse direction. In a preferred embodiment, the first feed roller, which preferably has the feed roller segments, is height-adjustable in the direction perpendicular to the transport plane, preferably by a height-adjustment drive.The second preferred roller is preferably designed as a roller which extends in particular over the entire width of the fabric tube section.

[0016] In order to convey the front area of ​​the fabric tube web in a defined position, while the rear area of ​​the fabric tube piece to be produced can be compressed by tearing, the feed unit and the feed unit are set in a preferred embodiment such that the feed speed of the front area of ​​the fabric tube web during tearing of the fabric tube piece is essentially equal to the feed speed of the fabric tube web.

[0017] In order to transfer the fabric hose web drawn into the tear-off unit by the feed unit to the feed unit, the feed unit and the feed unit are, in a preferred embodiment, set such that the feed speed of the front area of ​​the fabric hose web from the takeover by the feed unit until the tear-off of the fabric hose piece essentially corresponds to the feed speed of the fabric hose web.

[0018] To transport successive sections of fabric tubing in the transport direction at predetermined intervals, the feed unit and the feed unit, in a preferred embodiment, are set such that the feed speed of the fabric tubing section is increased after tearing to a take-off speed that is greater than the take-off speed of the remaining fabric tubing web, i.e., the web reduced by the fabric tubing section. Thus, the take-off speed is only reached after tearing. The take-off speed then carries the fabric tubing section away from the remaining fabric tubing web.

[0019] Preferably, the feed unit is set such that the feed rate is essentially constant during the feed-in of the fabric tube web, the tearing off of the fabric tube section, and the peeling off of the fabric tube section, relative to the peeling speed. Preferably, the feed rate is essentially constant over the time it takes to tear off several fabric tube sections.

[0020] Preferably, the preferred unit is set such that the pull-off speed is reached at the end of an acceleration process, which is preferably triggered with or after the tearing off of the fabric hose piece.

[0021] To prepare for the tearing off of the next fabric tube section, the preferred unit is preferably configured to decelerate, after the fabric tube section has been pulled off and before the remaining fabric tube web is taken over, to a takeover speed essentially corresponding to the retraction speed of the remaining fabric tube web, so that the leading edge of the remaining fabric tube web is taken over at a takeover speed essentially corresponding to the retraction speed of the fabric tube web. The next fabric tube section can then be torn off and pulled off as described above.

[0022] In a preferred embodiment, the tear-off unit is designed to create a compression, i.e., a section-by-section upward movement from the transport plane, of the rear portion of the fabric tube to be torn off or the torn-off section in front of the preferred unit. Preferably, the tear-off unit is configured to overstretch the fabric tube sheet along the tear line, so that the fabric tube section is torn off along the tear line. This overstretching can cause a compression of the fabric tube sheet, which can also propagate into the torn-off fabric tube section. However, this compression is not transferred to the front portion of the fabric tube section, which is transported further by the preferred unit in its clamped and thus defined state.

[0023] In a preferred embodiment, a smoothing unit is provided between the tear-off unit and the feed unit. This smoothing unit is designed to smooth the compression of the rear section of the fabric hose segment to be torn off before it reaches the feed unit, i.e., to realign the compressed rear section parallel to the transport plane. Advantageously, the compression of the rear section caused by the tear-off process can therefore be at least partially, and preferably substantially completely, compensated for by the smoothing unit before the rear section passes the feed unit.After leaving the preference unit, the entire fabric hose section is flat and essentially free of compression in the transport plane, which is preferably essentially horizontal with respect to the operating state, wherein the front end of the fabric hose section is in the defined position and orientation due to the preference unit, which is optimized for transfer to the next processing station.

[0024] To actively smooth the compression, the smoothing unit, in a preferred embodiment, includes a transport device with which the rear portion of the fabric hose to be torn off is transported to the feed unit at a certain speed. For this purpose, the transport device has at least one transport drive. In a preferred embodiment, the transport drive is formed by a feed drive of the feed unit. In this embodiment, the transport device does not have its own drive.

[0025] In an alternative design, the smoothing unit can have a stationary smoothing element, for example, a smoothing bar. The smoothing element can passively smooth out the compression backwards as the fabric hose web or fabric hose section is guided past it.

[0026] In a preferred embodiment, the transport device and the feed unit are adjusted such that the transport speed specified by the transport drive during tearing essentially corresponds to the feed speed. If the front section is pulled away faster at the pull-off speed, the compression is compensated for particularly evenly and continuously.

[0027] In a preferred embodiment, the transport device comprises at least one belt conveyor, and preferably also a further belt conveyor, in particular an upper and a lower belt conveyor. The belt conveyor can engage the upper side and the further belt conveyor the underside of the fabric tube web. The belt conveyor preferably comprises at least one circulating belt element, preferably an upper circulating belt element, and / or the further belt conveyor comprises a further circulating belt element, preferably a lower circulating belt element, each of which is set in motion by a belt drive, preferably by the feed drive.

[0028] In a preferred embodiment, the belt conveyor and / or the subsequent belt conveyor each have a freewheel, so that the transport speed of the circulating belt element can increase passively, i.e., solely through contact with the fabric tube section, via the feed-in speed when the fabric tube section is pulled off at the feed speed after tearing. Preferably, the freewheel is configured on a (further) deflection roller for the (further) circulating belt element. It is particularly preferred if the upper and lower belt conveyors each have a freewheel. The freewheel has the advantage that the friction between the fabric tube section accelerated by the feed unit and the (further) circulating belt element can be reduced.

[0029] In a preferred embodiment, the circulating belt element, preferably the upper circulating belt element, has an entry area spaced apart from the transport plane. Along the entry area, the circulating belt element is raised from the transport plane, allowing the material compression of the fabric tube section to form. Preferably, the entry area has a length of at least 60 millimeters (mm), preferably at least 80 mm, for example, from 100 mm to 180 mm. In a preferred embodiment, the further circulating belt element of the further belt conveyor, preferably the lower circulating belt element, extends along the transport plane in the entry area of ​​the upper circulating belt element, so that a gap, preferably a wedge-shaped gap converging in the transport direction, is formed between the circulating belt element and the further circulating belt element in the entry area.

[0030] In a preferred embodiment, the circumferential belt element, preferably the upper circumferential belt element, has a run-out area spaced away from the transport plane.

[0031] Along the discharge area, the circulating belt element is lifted from the transport plane. This allows the circulating belt element to be decelerated, preferably passively, to the transfer speed at which the next fabric hose section is transferred as the fabric hose section is pulled away with the feed unit. Preferably, the discharge area has a length of at least 50 mm, preferably at least 80 mm, for example from 100 mm to 180 mm.

[0032] In a preferred embodiment, the further circumferential belt element, preferably the lower circumferential belt element, extends along the transport plane in the run-out area of ​​the upper circumferential belt element, so that in the run-out area a further gap, preferably a wedge-shaped gap diverging in the transport direction, is formed between the circumferential belt element and the further circumferential belt element.

[0033] In a preferred embodiment, the belt conveyor, preferably the upper belt conveyor, has a pressure roller for pressing the fabric hose section against the transport surface. Preferably, the inlet area, viewed in the transport direction, is located upstream of the pressure roller, and the outlet area, also viewed in the transport direction, is located downstream of the pressure roller. Preferably, the rear and / or the front end of the belt conveyor, preferably the upper belt conveyor, is each formed by a deflection roller raised from the transport surface, around which the circulating belt element, preferably the upper circulating belt element, rotates. The rear and / or the front end of the further belt conveyor, preferably the lower belt conveyor, is preferably each formed by a deflection roller adjacent to the transport surface, around which the further circulating belt element rotates.

[0034] The transport device described above can also be used independently of the tear-off station. Therefore, this disclosure also applies to a transport device comprising a belt conveyor as described above, preferably also with a further belt conveyor as described above.

[0035] For the purposes of this disclosure, the location and direction references, such as "above", "below", "horizontal", "vertical", refer to the intended operating state of the tear-off station or the device for the manufacture of pinch-bottom fabric bags.

[0036] In a preferred embodiment, the upper belt conveyor has an arrangement of upper belt elements and / or the lower belt conveyor has an arrangement of lower belt elements. Preferably, the upper and lower belt elements are spaced apart from each other in the transverse direction, i.e., in the direction perpendicular to the transport direction in the transport plane.

[0037] In a preferred embodiment, the feed unit has a feed drive and the feed unit has a feed drive, wherein the feed speed and the feed speed can be set independently of each other using the feed drive. For example, the feed speed can be increased from the take-up speed during the take-up of the fabric web to the take-off speed using the feed drive, without changing the feed speed. Preferably, the feed drive is separate from the feed drive.

[0038] In a preferred embodiment, the transport device has a transport drive, wherein the transport speed and the pre-loading speed can be set independently of each other using the transport drive. For example, the pre-loading speed can be increased from the take-up to the take-off speed using the pre-loading drive without changing the transport speed. Preferably, the transport drive is formed by the infeed drive.

[0039] In a preferred embodiment, the tear-off unit has a first holding roller and a first tearing roller, so that the fabric hose piece is torn off the fabric hose web along the tear-off line by different circumferential speeds of the first holding roller and the first tearing roller.

[0040] Preferably, the tear-off unit has a second holding roller to form a pair of retaining rollers and / or a second tearing roller to form a pair of tearing rollers.

[0041] In a preferred embodiment, the first holding roller and / or the second holding roller, preferably the pair of holding rollers, is connected to a holding roller drive, and the first and / or the second tearing roller, preferably the pair of tearing rollers, is connected to a tearing roller drive. Different circumferential speeds of the (first or second) tearing roller relative to the (first or second) holding roller can be set using the holding roller and tearing roller drives, so that a tensile force is applied to the fabric tube web that the fabric tube section is completely torn off.

[0042] In a preferred embodiment, the retaining roller drive is independent of the tearing roller drive, so that the first retaining roller, preferably the retaining roller pair, can be driven independently of the first tearing roller, preferably the tearing roller pair. Thus, the fabric tube web can be stretched by driving the first retaining roller, preferably the retaining roller pair, with the retaining roller drive and the second tearing roller, preferably the tearing roller pair, with the tearing roller drive, such that the fabric tube section is torn along the tear line.

[0043] In a preferred embodiment, the first holding roller has a holding roller clamping strip configured to clamp the fabric tubing against the second holding roller exactly once every plurality of revolutions, preferably exactly once every three revolutions. This embodiment offers the advantage that the first holding roller, or first tearing roller, can be rotated continuously, thus avoiding or reducing detrimental acceleration and deceleration. Every nth revolution, for example, every third revolution, the first holding roller comes into contact with the second holding roller, so that the fabric tubing is temporarily clamped between the first and second holding rollers in order to tear off the fabric tubing section in conjunction with the pair of tearing rollers.

[0044] In a preferred embodiment, it is advantageous for the first tearing roller to have a tearing roller clamping strip configured to clamp the fabric tube against the second tearing roller once every multiple revolutions, preferably exactly once every three revolutions. The first and second tearing rollers can be designed corresponding to the first and second holding rollers, respectively. When the fabric tube is clamped between the holding roller clamping strip of the first holding roller and the mating surface of the second holding roller, the fabric tube section can be torn off by stretching along the tear line by clamping the fabric tube between the tearing roller clamping strip of the first tearing roller and the mating surface of the second tearing roller.

[0045] In order to bring the retaining roller clamping strip into contact with the opposite surface of the second retaining roller exactly once per plurality of revolutions, for example exactly once every three revolutions, the retaining roller drive is preferably designed to drive the first retaining roller at a different speed than the second retaining roller.

[0046] To improve guidance and / or tensioning of the fabric tube and / or the fabric tube section, a preferred embodiment includes at least one pair of intermediate rollers, arranged between the tearing roller pair and the holding roller pair. Preferably, after the fabric tube section is torn off, the fabric tube web is picked up by the intermediate roller pair, i.e., between a first and a second intermediate roller. Preferably, the intermediate roller pair is driven by an intermediate roller drive or, alternatively, designed as a passive roller pair. Preferably, the intermediate roller drive is independent of the holding roller drive and the tearing roller drive. Preferably, the intermediate roller pair runs ahead of the holding roller pair.

[0047] The ripper roller drive is preferably designed to drive the first ripper roller at a different speed than the second ripper roller. This ensures that the ripper roller clamping strip comes into contact with the mating surface of the second ripper roller exactly once per plurality of revolutions, for example, exactly once every three revolutions.

[0048] To synchronize the tear-off unit with the transport of the fabric tube web, a sensor unit is preferably provided. In a preferred embodiment, this sensor unit is designed to determine the target position of the tear-off line relative to the tear-off unit by detecting the beginning or the (leading) edge of the fabric tube web and / or the tear-off line or a printed mark, for example, a color transition or a perforation in the fabric tube web. If the tear-off line is at the desired target or tear-off position, the fabric tube section is torn off by the tear-off unit. Preferably, the fabric tube section is also torn off by the tear-off unit if the tear-off line is within a tolerance range around the desired target or tear-off position, or if a printed mark is within a tolerance range around the desired target position.

[0049] Preferably, the sensor unit comprises a contrast sensor for determining the position of printed motifs, in particular print marks, on the fabric tube web. Preferably, several print marks are applied to the fabric tube web at a predefined distance from one another, the distance between two adjacent print marks preferably corresponding substantially to the repeat length, i.e., the repetition length of a printed motif, of the fabric tube web. Preferably, each print mark marks an end region of a fabric tube section. The print mark can be formed, in particular, by a specially applied identifying mark or by a predefined area of ​​the repeating printed motif.

[0050] In a preferred embodiment, a control unit is provided which is configured to control or regulate at least one of the drives described above, preferably the preferred drive, the ripper roller drive and the retaining roller drive, in particular all of the drives described above, preferably depending on the sensor unit.

[0051] In the inventive method for tearing off a piece of fabric hose from a fabric hose web along a tear line, at least the following steps are carried out:

[0052] Pulling in the fabric tubing at a pull-in speed ,

[0053] Tearing off the fabric hose section along the tear line from the fabric hose sheet,

[0054] Pre-pulling of a front portion of the fabric tubing ahead of the tear line during the tearing of the fabric tubing section along the tear line in a clamped state at a pre-pulling speed.

[0055] The advantages and technical effects of this process were explained above in connection with the detachment station, which is preferably used to carry out the process.

[0056] In a preferred embodiment, the woven tubing has a tape fabric made of, preferably stretched, plastic tapes, preferably of semi-crystalline thermoplastic, preferably of polyolefin, for example polypropylene. A film, preferably of biaxially oriented polypropylene (BOPP), is preferably applied to the tape fabric.

[0057] In a preferred embodiment, the fabric tube is formed from a flat fabric sheet, which is folded over to form a tube. Intersecting sections of the flat fabric sheet are joined together in the overlap area by a longitudinal seam, in particular an adhesive or weld seam. In a preferred embodiment, the fabric tube has a side fold on each of its opposite longitudinal sides. This allows the production of side-fold fabric bags.

[0058] To form the tear line, the fabric tubing preferably has perforations, i.e., openings that completely penetrate one of the opposing fabric tubing walls of the tubing, or weakenings, i.e., depressions that only partially, but not completely, penetrate one of the opposing fabric tubing walls, or a combination of perforations and weakenings (see EP 2 117 821 Bl).

[0059] Preferably the demolition line is a stepped line (see also EP 2 117 821 Bl ).

[0060] In a preferred embodiment, the torn-off piece of fabric tubing is processed by folding the end region of the fabric tubing, bounded by the tear line, at least once, preferably exactly once, over onto the adjacent fabric tubing wall, i.e., onto itself, and joining the folded end region with the adjacent outer surface of the fabric tubing wall to form a folded bottom, preferably a pinch bottom. The invention can be used to produce both pinch-bottom fabric bags, i.e., fabric bags with a stepped tear line, and other folded-bottom fabric bags, particularly those with a straight tear line.

[0061] In a preferred embodiment of the method, the preferred speed of the front region corresponds to the fabric tube web.

[0062] - from the takeover by the preferred unit until the tearing off of the fabric hose section, essentially the retraction speed of the fabric hose web and / or

[0063] - during the tearing off of the fabric hose section, essentially the retraction speed of the fabric hose web .

[0064] Preferably, the initial velocity of the fabric tube section is increased after tearing to a pull-off velocity that is greater than the retraction velocity of the remaining fabric tube web. Preferably, the pull-off velocity is reached at the end of an acceleration process, which is preferably triggered at or after the tearing of the fabric tube section.

[0065] To prepare for the separation of the next fabric hose section, the leading edge of the remaining fabric hose web (i.e., reduced by the previously separated section) is picked up and advanced after the previously separated section has been pulled off, at a feed rate essentially corresponding to the feed rate of the fabric hose web. Further fabric hose sections can be torn off and advanced as described above.

[0066] When the fabric hose section is torn off, a compression of the rear area of ​​the fabric hose section to be torn off or torn off is preferably formed, which is at least partially, preferably substantially completely, compensated before reaching the preferred unit.

[0067] To at least partially reduce this compression, in a preferred embodiment the rear area of ​​the torn-off or torn-off fabric hose section is transported to the preferred unit at a transport speed.

[0068] The device according to the invention for the production of woven bags, preferably fold-bottom woven bags, preferably pinch-bottom woven bags, has a tear-off station in one of the above described embodiments.

[0069] 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.

[0070] In a preferred embodiment, the device further comprises a station for forming tear lines at regular intervals along the fabric sheet or the fabric tube sheet. The tear lines are preferably formed by perforations and / or weakenings, as described above. The station preferably comprises at least one perforation unit, preferably a laser unit, for weakening or perforating the fabric sheet or the fabric tube sheet 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 tight seal 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.

[0071] In a preferred embodiment, the station is designed to form tear lines, forming the tear line at a position corresponding to the recurring pressure motif of the fabric tube web.

[0072] To reduce the influence of web deviations and material tolerances, the device, in a preferred embodiment, is designed to determine a correction dimension, i.e., an offset between the target position of the tear-off line and the repeating print motif, or between two, preferably consecutive, print marks on the fabric tube web. Preferably, the target position of the tear-off line is determined based on the leading tear-off line (i.e., the line preceding the line in the conveying direction) and the repeat dimension. Preferably, a target print mark is then identified whose position most closely corresponds to the target position of the tear-off line (i.e., for example, whose position is closest to the target position of the tear-off line). Preferably, the correction dimension of the fabric tube section is determined from the positions of the target print mark and the target position. Preferably, the correction dimension serves as a control variable for the control or...Control unit of the device. It is advantageous if the distance over which the fabric tube web is conveyed before the fabric tube section is torn off is corrected by the correction dimension. It is advantageous if this correction enables a consistent positioning of the tear line in the tearing unit, i.e., for example, centrally between the tearing and holding rollers. In a preferred embodiment, the device has a tube forming station with which the fabric flat web is folded over and processed into a fabric tube web with a longitudinal seam.

[0073] In a preferred embodiment, the device has a rotary station downstream of the tear-off station in the transport direction for rotating the fabric tube 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 tube sections are arranged substantially in the transport direction, and downstream of the rotary station, they are arranged substantially perpendicular to the transport direction.

[0074] In a preferred embodiment, the device has a delay and / or alignment station in the transport direction after the rotary station for delaying the fabric hose pieces for further processing.

[0075] In a preferred embodiment, the device has an intermediate transport and discharge station, preferably arranged downstream of the tear-off station in the transport direction. Preferably, the intermediate transport and discharge station is located upstream of the rotary station, i.e., arranged upstream of the rotary station in the transport direction. Preferably, the intermediate transport and discharge station is designed to take the fabric hose section from the tear-off station and / or to transfer the fabric hose section to the rotary station. Preferably, the intermediate transport and discharge station is designed to discharge fabric hose sections, for example, during a start-up phase of the device. It is advantageous if the fabric hose section is already aligned before being transferred to the rotary station.

[0076] In a preferred embodiment, the device has a bottom-forming station for forming fold-over bottoms, preferably pinch-over bottoms, on the fabric tube sections in the transport direction after the tear-off station, preferably in the transport direction after the delay station, so that fold-over bottom fabric bags, preferably pinch-over bottom fabric bags, are obtained. In a preferred embodiment, the device has a depositing station for depositing the fold-over bottom fabric bags, preferably the pinch-over bottom fabric bags, in the transport direction after the bottom-forming station.

[0077] The invention is further explained below with reference to an exemplary embodiment shown in the drawings.

[0078] Fig. 1 schematically shows a device for the production of pinch-bottom fabric bags, in which a tear-off station according to the invention is used for tearing off pieces of fabric tubing from a fabric tubing web.

[0079] Figs. 2 to 10 show the tear-off station according to the invention in various phases of drawing in a fabric tube web, tearing off a piece of fabric tube and pulling forward the torn-off piece of fabric tube.

[0080] Fig. 1 shows a device 1 for manufacturing a pinch-bottom woven bag.

[0081] The individual stations of the device 1 are explained below only as comprehensively as is necessary for understanding the context of the invention.

[0082] As can be seen in Fig. 1, the device 1 has an unwinding station 2 with which a fabric web 3 is unwound. The fabric web 3 has a tape weave made of stretched plastic tapes, for example polypropylene. A film, preferably made of biaxially oriented polypropylene (BOPP), is preferably applied to the tape weave.

[0083] As can be seen from 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, in the example shown 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 tight seal of the final pinch-bottom fabric bag.

[0084] As can be seen in Fig. 1, the device 1 further comprises a tube forming station 7, with which the fabric sheet 3 is folded over, an overlap area is formed, and this overlap area is provided with a longitudinal seam 8 (schematically shown in Fig. 1) to form a fabric tube sheet 9. Longitudinal folds can also be provided.

[0085] As can be seen from Fig. 1, the device 1 further has a tear-off station 10, which is described in detail below, with which the fabric hose web 9 is divided into individual fabric hose pieces 11.

[0086] As can be seen from Fig. 1, the device 1 further has an intermediate transport and discharge station 12 for the intermediate transport of the fabric hose pieces 11 and the discharge of starting material.

[0087] 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 after the rotary station.

[0088] As can be seen from Fig. 1, the device 1 further includes a delay and / or alignment station 15 for delaying the fabric hose pieces 11 for further processing.

[0089] 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.

[0090] As can be seen from Fig. 1, the device 1 further has a depositing station 19 for depositing the fabric bags 18.

[0091] As can be seen from Fig. 2, the tear-off station 10, viewed in the transport direction 14A, has successively a feed unit 20 for feeding in the fabric tube web 9, a tear-off unit 21 for completely tearing off the fabric tube pieces 11 along the tear-off lines, and a feed unit 22 for drawing the fabric tube web 9 forward from the point where the leading edge of the fabric tube web 9 contacts the feed unit 22, through the tearing off of the respective fabric tube piece 11 along the tear-off line 5, until the fabric tube piece 11 is pulled off after the fabric tube piece 11 has been torn off (see Fig. 3).

[0092] In the example shown, the feed unit 20 has a first, here an upper, feed roller unit 23 with several, here four, upper feed roller elements 23A. Depending on the design, the feed roller elements may be fixed in height or adjustable individually, in pairs, or together in the vertical direction, i.e., perpendicular to the transport plane. The feed unit 20 also has a second, here a lower, feed roller 24, which extends across the entire width of the fabric tube web 9. The fabric tube web 9 is drawn between the feed roller elements 23A of the feed roller unit 23 and the second feed roller 24. In the example shown, the second feed roller 24 is connected to a feed drive 24A, so that the second feed roller 24 is actively driven. The feed roller elements 23A of the first feed roller unit 23 are passively dragged along when the fabric hose web 9 is conveyed.The contact pressure on the fabric tube sheet 9 can be varied in the transverse direction by adjusting the height of the feed roller elements 23A individually, in pairs, or together. This allows, in particular, the contact pressure to be adjusted to the opposite side folds of the fabric tube sheet 9. This adjustment is especially advantageous during feeding because high feeding forces must be applied to the fabric tube sheet 9. For adjusting the height of the feed roller elements 23A, actuating units 23B, preferably pneumatic actuating units, are preferably provided (see Figures 2 to 10).

[0093] The tear-off unit 21, as shown in the example, comprises a pair of retaining rollers with a first (here, an upper) retaining roller 25 and a second (here, a lower) retaining roller 26, as well as a pair of tearing rollers with a first (here, an upper) tearing roller 27 and a second (here, a lower) tearing roller 28. The retaining roller pair is connected to a retaining roller drive 29, and the tearing roller pair to a tearing roller drive 30. The retaining roller drive 29 is separate from the tearing roller drive 30, so that the retaining roller pair can be driven independently of the tearing roller pair. By varying the circumferential speeds of the retaining roller pair and the tearing roller pair, the fabric hose sections 11 can be torn off along the tear lines 5 (Fig. 2, Fig. 3).

[0094] In the example shown, the first retaining roller 25 has a retaining roller clamping strip 31. With each revolution of the retaining roller 25, the retaining roller clamping strip 31 comes into contact with a counter surface 32 of the second retaining roller 26, so that the fabric hose web 9 is momentarily clamped between the retaining roller clamping strip 31 of the first retaining roller 25 and the counter surface 32 of the second retaining roller 26 (see Figs. 2 to 6).

[0095] In the example shown, the first tearing roller 27 has a tearing roller clamping strip 34 which comes into contact with a counter surface 35 of the second tearing roller 28 exactly once per plurality of revolutions, approximately once every three revolutions, so that the fabric tube web 9 is momentarily clamped between the tearing roller clamping strip 34 of the first tearing roller 27 and the counter surface 35 of the second tearing roller 28. During the remaining revolutions, the tearing roller clamping strip 34 passes over clearances, here flattened sections 36, of the second tearing roller 28, so that no clamping of the fabric tube web 9 takes place (see Figs. 2 to 6). To enable the clamping of the fabric tube web 9, the first holding roller 25 is driven by means of the holding roller drive 29 at a different speed than the second holding roller 26 and the first tearing roller 27 is driven by means of the tearing roller drive 30 at a different speed than the second tearing roller 28.The different diameters of the first 25 and second retaining roller 26 result in equal circumferential speeds.

[0096] The tear-off station 10 has a control unit 33 (see Fig. 2, Fig. 3) which is connected to a sensor unit 38. The sensor unit 38 detects the position of the tear-off line relative to the tear-off unit 21 via the beginning of the fabric tube 9 and / or the tear-off line and / or (as shown) a print mark 38A on the fabric tube 9 and transmits this information to the control unit, which controls the tear-off unit 21 depending on the detected position of the tear-off line 5.

[0097] In the example shown, the feed unit 22 has a first, here an upper, feed roller 39 and a second, here a lower, feed roller 40, which together form a feed roller pair for drawing forward a front section of the fabric tube web 9. The first 39 and the second feed roller 40 are in contact with each other such that the fabric tube web 9 is constantly clamped between the first 39 and the second feed roller 40. The feed unit 22 has a feed drive 41, which drives the first 39 and / or the second feed roller 40. However, it is preferred if the first 39 and the second feed roller 40 are driven by the feed drive 41. Since the front part of the hose track has to be drawn between the two feed rollers 39, 40 again during each tearing process, it is not practical to only passively drag one of the feed rollers 39, 40.In this case, the hose track would have to transfer the movement to the passively trailed feed roller. However, this could cause the hose track to kink.

[0098] In the example shown, the first preferred roller 39 has several, here four, preferred roller segments 39A, which sit on a common axis 39B and, in a preferred embodiment, can be adjusted together in height.

[0099] A smoothing unit 42 is provided between the tear-off unit 21 and the feed unit 22. In the example shown, the smoothing unit 42 is formed by a transport device 43, which transports the tubular fabric web 9 between the tear-off unit 21 and the feed unit 22 at a transport speed in transport direction 14A. The transport device 43 has a belt conveyor 44, here an upper belt conveyor, and another belt conveyor 45, here a lower belt conveyor (Figs. 2 to 10).

[0100] The belt conveyor 44 has several circulating belt elements 46 and the further belt conveyor 45 has several further belt elements 47, each of which is set in rotation by a belt drive, in the example shown by the feed drive 24A (see Fig. 2, Fig. 3).

[0101] In the example shown, the circulating belt elements 46 each have an entry area 46A spaced apart from the transport plane. Along the entry areas 46A, the circulating belt elements 46 are raised from the transport plane. The other circulating belt elements 47 of the further belt conveyor 45, on the other hand, run parallel to and adjacent to the transport plane, so that along the entry areas 46A a gap, here a wedge-shaped gap converging in the transport direction, is formed between the circulating belt elements 46 and the other circulating belt elements 47 (Fig. 2, Fig. 3).

[0102] In the example shown, the circulating belt elements 46 each have a run-out area 46B spaced away from the transport plane. Along the run-out areas 46B, the circulating belt elements 46 are raised from the transport plane. The other circulating belt elements 47 of the further belt conveyor 45, on the other hand, run parallel to and adjacent to the transport plane, so that along the run-out areas 46B a gap, here a wedge-shaped gap widening in the transport direction, is formed between the circulating belt elements 46 and the other circulating belt elements 47 (see Fig. 2 and Fig. 3).

[0103] In the example shown (see Figs. 3 to 8), the belt conveyor 44 has a pressure roller 48, which presses the fabric hose section 11 against the further circulating belt element 47. The inlet area 46A extends in front of the pressure roller 48 when viewed in the direction of transport. The outlet area 46B extends, also when viewed in the direction of transport, after the pressure roller 48. To form the inlet area 46A and the outlet area 46B, the rear and front ends of the belt conveyor 44 are each formed by a deflection roller 49 raised from the transport plane. The circulating belt element 46 runs around the deflection rollers 49 and the pressure roller 48 such that the inlet area 46A is formed in front of the pressure roller 48 and the outlet area 46B is formed after the pressure roller 48. For the circulation of the circulating belt element 46, the belt conveyor 44 has further deflection rollers 50.The rear and front ends of the further belt conveyor 45 are formed by deflection rollers 51 adjacent to the transport plane, around which the further circulating belt element 47 rotates. For the rotation of the further belt element 46, the further belt conveyor 45 has additional deflection rollers 52 (see Fig. 3).

[0104] In the example shown, the belt conveyor 44 and the further belt conveyor 45 each have a freewheel, so that the transport speed of the circulating belt element 46 and the further circulating belt element 47 can increase above the feed speed due to the frictional contact with the fabric hose section 11 when the fabric hose section 11 is pulled off at the feed speed after being torn off. A freewheel is provided on the driven deflection pulley 49 for the circulating belt element 46 and on the driven deflection pulley 51 for the further circulating belt element 47.

[0105] Figures 2 to 10 show the tearing process in detail.

[0106] As shown in Fig. 2, the fabric tube web 9 is drawn in by the feed unit 20. The front end of the fabric tube web 9, where the future pinch bottom of the fabric bag can be seen, is located just between the holder roller pair and the tearing roller pair.

[0107] As shown in Fig. 3, the front section of the fabric tube web 9 is advanced by the feed unit 22 in a clamped position. The feed drive 41 sets the feed speed to the constant feed speed. The feed unit 22 advances the front section of the fabric tube web 9 in the transport direction 14A at the same speed as the fabric tube web 9 is fed in further back by the feed unit 20. The tear-off unit 21 is still in the inactive state.

[0108] According to Fig. 3, the sensor unit 38 detected that the tear line 5 had reached the target position between the holding and tearing roller pair. The tearing unit 21 is controlled by the control unit so that the section of the fabric tube web 9 is stretched between the holding and tearing roller pair, as shown in Fig. 4.

[0109] As shown in Fig. 5, the fabric hose section 11 is torn off the fabric hose web 9. Since the feed speed during tearing is limited to the feed or web speed, a material compression 53 builds up due to the tearing stress adjacent to the tear roller clamping strip 34, which can bulge upwards in the inlet area of ​​the transport device 43.

[0110] As shown in Fig. 6, when the fabric tube section 11 is torn off, the feed roller(s) of the feed unit 22 are accelerated, so that the feed speed is increased from the feed speed to a pull-out speed. The transport device 43 is driven by the feed drive 24A (see Fig. 2 and Fig. 3). Due to the freewheel, the transport speed of the transport device 43 increases above the feed speed of the feed unit 20.

[0111] As shown in Fig. 7, the distance between the fabric hose section 11 and the remaining fabric hose web increases. The rear end of the fabric hose section 11 has almost reached the inlet area 46A. The material compression 53 is further (continuously) reduced.

[0112] As shown in Fig. 8, the material compression 53 at the rear end of the fabric tube section 11 is relieved by the pressure roller 48 of the belt conveyor 44, which presses against the further belt elements 47 of the further belt conveyor 45. Thus, the material (see material compression 53) can be smoothed out to the rear before the rear area of ​​the fabric tube section 11 is drawn through the first feed roller 39 and the second feed roller 40 of the feed unit 22.

[0113] As shown in Fig. 9, the rear end of the fabric tube section 11 has passed the pressure roller 48. The material compression 53 has been compensated. The discharge area 46B of the belt conveyor 44 is out of contact with the rear end of the fabric tube section 11, so the transport speed is reduced back to the feed speed. The fabric tube section 11 is now only in the area of ​​its rear end in the feed unit 22. At this position, the fabric tube section 11 is essentially flattened.

[0114] As shown in Fig. 10, the rear end of the fabric tube section 11 is pulled off the feed unit 22. At this point, the fabric tube section 11 can be transferred to the next station. The acceleration to the pull-off speed establishes the desired distance to the remaining fabric tube web 54, i.e., the fabric tube web 9 without the fabric tube section 11. The feed unit 22 is then decelerated to a take-up speed, which again corresponds to the feed-in speed. Thus, the remaining fabric tube web can be taken over at the feed-in speed, which was previously reduced to the feed-in speed. From this point on, the steps described above are repeated to separate the next fabric tube sections from the remaining fabric tube web 54.

[0115] Reference list: Device Unwinding station Fabric flat web Station for forming tear-off lines Tear-off lines Perforation unit Tube forming station Longitudinal seam Fabric tube web Tear-off station Fabric tube pieces Ejection station Rotary station A Transport direction B Transverse direction Deceleration station Bottom forming station Pinch bottoms Folded bottom fabric bags Discharge station Infeed unit Tear-off unit Preferred unit First infeed roller A Upper infeed roller elements B Actuating units Second infeed roller A Infeed drive First holding roller Second holding roller First tearer roller Second tearer roller Holding roller drive Tearer roller drive Holding roller clamping strip Counter surface Control and regulating unit Tearer roller clamping strip Counter surface Flattening Sensor unit A Print mark First prefer roller A Preferred roller segments B Common axis Second prefer roller Preferred drive Smoothing unit Transport device Belt conveyor Further belt conveyor Circulating belt elements A Infeed area BDischarge area, further circumferential belt elements, pressure roller, deflection rollers lifted from the transport level, further deflection rollers, deflection rollers adjacent to the transport level, additional deflection rollers, material compression, remaining fabric hose web

Claims

Claims:

1. Tear-off station (10) for tearing off a piece of fabric tubing (11) of a fabric hose web (9) along a tear-off line (5) , comprising: a feed unit (20) for feed the fabric hose web (9) at a feed rate, a tear-off unit (21) with which the fabric hose piece (11) is torn off the fabric hose web (9) along the tear-off line (5), characterized by a feed unit (22) which is configured to feed a front area of ​​the fabric hose web (9) forward in a clamped state at a feed rate, while the fabric hose piece (11) is torn off along the tear-off line (5) behind the front area of ​​the fabric hose web (9).

2. Tear-off station (10) according to claim 1, characterized in that the feed unit (22) and the feed unit (20) are configured such that the feed speed of the front area of ​​the fabric tube web (9) during the tear-off of the fabric tube piece (11) corresponds essentially to the feed speed of the fabric tube web.

3. Tear-off station (10) according to claim 1 or 2, characterized in that the feed unit (22) and the feed unit (20) are configured to increase the feed speed of the fabric tube section (11) after tearing to a pull-off speed which is greater than the feed-in speed of the remaining fabric tube web (54).

4. Tear-off station (10) according to one of claims 1 to 3, characterized in that the preference unit (22) is configured to decelerate, after the peeling off of the fabric tube section (11) and before the take-up of the remaining fabric tube web (54), substantially to a take-up speed corresponding to the draw-in speed of the remaining fabric tube web (54), so that the front area of ​​the remaining fabric tube web (54) is brought into contact with the substantially The retraction speed of the fabric tubular web (54) is taken over by the corresponding transfer speed.

5. Tear-off station (10) according to one of claims 1 to 4, characterized in that the tear-off unit (21) is designed to form a material compression (53) of the rear area of ​​the fabric hose piece (11) to be torn off or torn off in front of the preferred unit (22) during tearing.

6. Tear-off station (10) according to claim 5, characterized in that a smoothing unit (42) is provided between the tear-off unit (21) and the preferred unit (22), which is designed to smooth the material compression (53) of the rear area of ​​the fabric tube piece (11) to be torn off or torn off in front of the preferred unit.

7. Tear-off station (10) according to claim 6, characterized in that the smoothing unit (42) has at least one transport device (43) with which the rear area of ​​the fabric hose piece (11) to be torn off or torn off is transported to the preferred unit (42) at a transport speed.

8. Tear-off station (10) according to claim 7, characterized in that the transport device (43) and the feed unit (20) are arranged so that the transport speed essentially corresponds to the feed speed.

9. Tear-off station (10) according to one of claims 1 to 8, characterized in that the tear-off unit (20) has a first holding roller (25) and a first tearing roller (27), such that the fabric tube piece (11) is torn off from the fabric tube web (9) by different circumferential speeds of the first holding roller (25) and the first tearing roller (27) along the tear-off line (5).

10. Tear-off station (10) according to claim 9, characterized in that the tear-off unit (21) has a second holding roller (26) to form a retaining roller pair and / or a second tearing roller (28) to form a tearing roller pair.

11. Tear-off station (10) according to claim 10, characterized in that the first tearing roller (27) has a tearing roller clamping strip (34) which is configured to clamp the fabric tube web (9) against the second tearing roller (28) once per plurality of revolutions, preferably exactly once per three revolutions.

12. Method for tearing off a piece of fabric tubing (11) from a fabric tubing web along a tear-off line, preferably with a tear-off station according to one of claims 1 to 11, comprising the steps: Pulling in the fabric tube sheet (9) at a pulling speed, Tearing off the fabric tube piece (11) along the tear line (5) from the fabric tube sheet (9) , characterized by Pre-pulling a front portion of the fabric tube sheet (9) in a clamped state at a pre-pulling velocity during the tearing of the fabric tube piece (11) along the tear line (5) behind the front portion of the fabric tube sheet (9).

13. Method according to claim 12, characterized in that the feed rate of the front region of the fabric tube web (9) during the tearing off of the fabric tube piece (11) essentially corresponds to the retraction rate of the fabric tube web (9) and / or that the feed rate of the front region of the fabric tube web (9) from the takeover by the feed unit (22) until the tearing off of the fabric tube piece (11) essentially corresponds to the retraction rate of the fabric tube web (9) and / or that the feed rate (22) of the fabric tube piece (11) after tearing off is increased to a take-off rate which is greater than the retraction rate of the remaining fabric tube web (9).

14. Method according to claim 12 or 13, characterized in that when the fabric tube piece (11) is torn off, a material compression (53) of the rear area of ​​the to be torn off or a torn piece of fabric hose (11) is created, which is at least partially, preferably substantially completely, compensated before reaching the preferred unit (22).

15. Device (1) for manufacturing woven bags, preferably fold-bottom woven bags, preferably pinch-bottom woven bags, comprising: a tear-off station (10) according to one of claims 1 to 11, preferably a rotary station (13) for rotating the woven tube section (11) by substantially 90° from a longitudinal transport position to a transverse transport position.

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