Partial opening device for pre-opening of gripping device

Abstract

To provide a partial opening device for pre-opening a gripping device, in particular a gripping device of a stretching device.SOLUTION: A partial opening device includes at least one partial opening disk and a drive device for driving at least one partial opening device. The partially opening disc has a circumferential surface that forms a rolling contact surface contacting with a tongue piece of the gripping device to pre-open the gripping device when the gripping device is guided past the partially opening disc.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The invention relates to a partial opening device for preopening a gripping device, in particular a gripping device of a stretching device, an opening device for opening the gripping device, a method for opening the gripping device as well as a stretching device provided with an opening device. [Background technology]

[0002] Stretching devices are used in particular for the production of plastic films and stretched fabrics and fibers. The strip of material to be stretched, usually a plastic film, is gripped by a gripping device and moves with the movement of the gripping device. The gripping devices are movably arranged on recirculating guide rails and are driven centrally or independently.

[0003] In particular, the strip material to be stretched is gripped in an entrance region by gripping devices that movably grip both side edges of the strip material stretched on an annular guide rail. The gripping devices are moved in sequence from the entrance region through the stretching region to the exit region and back to the entrance region again, while the thin film is subjected, for example, to a predetermined internal stress relaxation treatment and / or post-heat treatment and then transported to the exit.

[0004] In the inlet area, the gripping device is moved from an open state to a closed state (gripping state) in which it grips the web-like material. The gripping device usually has at least two gripping surfaces arranged opposite each other and gripping the web-like material. By actuation of the operating rod (also called a tongue), the gripping surfaces move closer to each other and are in the gripping state in which they grip the web-like material. The operating rod also moves the gripping surfaces to a separation position to release the stretched web-like material from the gripping device. In particular, the web-like material has to be released again after the stretching process is completed. Usually, the web-like material is usually released from the gripping device after the stretched thin film has passed through a subsequent heating or cooling zone. The gripping device grips the web-like material again (at a different place) after it has been returned to the inlet area on the annular guide rail and moves again through the stretching zone of the stretching device. The gripping device is opened to grip the web-like material again. Summary of the Invention [Problem to be solved by the invention]

[0005] The opening action of the gripping devices of existing stretching devices, in particular thin-film stretching devices, is unreliable and the gripping devices do not always operate reliably in the open state. In this case, the gripping devices either remain partially open or close again. The gripping devices thus do not grip the web material reliably, and there is a risk that the stretching device and / or the thin film to be stretched may be damaged. To overcome this defect, mechanical forced opening devices are used. When the gripping devices are guided past the forced opening devices, known forced opening devices, such as opening rings or opening strips, abut against the gripping devices so that the gripping devices are not fully opened or are closed. The gripping devices are forced open by a stop device.

[0006] However, the stop and quick release contacts create very high mechanical stresses that can significantly reduce the operational life of the gripping devices. If an impact force or stress causes a part of the gripping device, such as a tongue or other part of the gripping mechanism, to break, other parts of the thin film stretching device can be damaged and / or cause lost time and production.

[0007] Said forced opening should be avoided in particular in the case of high-speed stretching devices (e.g., where the corresponding movement speed of the gripping device is more than 500 m / min), such as stretching devices or super-fast stretching (BO) devices, which produce plastic thin films such as polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polyamide (PA) in the transverse and longitudinal directions. However, the opening speed of known magnetic opening devices and non-impact opening devices drops as the movement speed of the gripping device increases. Also, the opening speed of known non-impact opening devices results in insufficient operation when opening by the gripping device is difficult. Insufficient operation occurs, among other things, in the case of large film thickness, when the tongues are caught, and in the case of high film transverse tension. [Means for solving the problem]

[0008] The present invention aims to provide an apparatus and a method for reliably opening a gripping device even when the gripping device is moving at high speeds and / or when opening the gripping device is difficult.

[0009] The object of the invention is solved in particular by a partial opening device for preliminary or complete opening according to claim 1, by an opening device for complete opening of a gripping device according to claim 9, by a stretching device according to claim 13 and by a method for opening a gripping device according to claim 15. Further details of the invention are also given in the dependent claims and in the detailed description of the invention below.

[0010] In particular, the object of the present invention is solved by a partial opening device for pre-opening the gripping devices of a stretching apparatus, in particular a thin-film stretching apparatus, although the invention is not limited to thin-film stretching apparatuses, but can also be used, for example, in the stretching of fabrics, textiles or other materials, and further applications in other fields are also possible.

[0011] The partial opening device of the present invention does not completely open the gripping devices, which means that the gripping devices are not moved from the closed position to the open position by the partial opening device, in particular the partial opening device is configured to only perform a preliminary opening of the gripping devices that require a preliminary opening, to completely open or to partially open all the gripping devices that are guided past.

[0012] When partially opening the gripping device, the gripping device is only partially opened by the partial opening device, which for example moves the gripping device from the closed position without opening it completely. The subsequent additional opening process is controlled by an opening device, such as a suitable non-contact opening device (for example a magnetic opening device). In this case, the partial opening device is arranged upstream of the opening device or in the front area of ​​the opening device, so that the opening device can take over from the previously opened gripping device.

[0013] In a first application example, only a part of the gripping device is pre-opened, in particular the part of the gripping device guided through the partial opening disc has a predefined degree of opening. In this case, the partial opening device is arranged in the (front) area of ​​the opening device. In this case, the preferred degree of opening of the gripping device corresponds to the degree of opening to which the opening device has moved the gripping device due to correct functioning of the opening device.

[0014] The gripping devices that do not reach the desired degree of opening are subsequently opened by a partial opening device that is guided past the gripping device. The gripping devices do not reach the desired degree of opening, for example, if the gripping device (or its tongues) is stiff and / or adheres too strongly to the side edges of the film to be stretched. The gripping devices that are pre-opened by the partial opening device are completely opened by the actual opening device (for example a magnetic opening device).

[0015] In a second application, the entire gripping device is pre-opened. For this purpose, a partial opening device is arranged in front of the actual opening device. The gripping device which is guided past the actual opening device is then opened and pre-opened by the partial opening device and in the pre-opened state is sent to a suitable real magnetic opening device.

[0016] In a third application example, a partial opening device is provided which completely opens the gripping device. In this case, the partial opening device is arranged downstream of the opening device or in the region of the opening device. In this case, the partial opening device takes over the already partially opened gripping device from the opening device and then further initiates the subsequent process of the already partially opened gripping device. When the gripping device is fully opened, the partial opening device guides it beyond the tip to a completely open position. The tip means the event beyond which the gripping device or the tongue is completely and definitely opened.

[0017] The partial opening device also prevents: (i) the opening device does not fully open the gripping device (especially due to pre-opening); and / or (ii) A gripping device that has already been (partially) opened (in particular by full opening) while still in a partially open or re-closed state.

[0018] The partial opening device comprises at least one partial opening disk and a drive for driving the at least one partial opening disk. The partial opening disk is in particular rotated by the drive.

[0019] The partially opening disc has a circumferential surface with a rolling contact surface, which when the gripping device is guided past the partially rotating disc comes into contact with a tongue of the gripping device and when guided beyond the partially opening disc, the gripping device has an opening degree below a predetermined opening degree, so that the gripping device is pre-opened or selectively fully opened.

[0020] In a first application example, when only a part of the gripping device is pre-opened, a partial opening device (which is connected in parallel to the opening device) is arranged in the region of the opening device, preferably in the front region of the opening device. In this case of guiding the gripping device through the partial opening device, the preferred degree of opening of the gripping device corresponds to the degree of opening with which the opening device actuated the gripping device with the correct functioning of the opening device. The gripping device which is insufficiently opened and guided by the opening device is pre-opened by the partial opening device. After passing the partial opening device, the whole gripping device is partially opened (when the opening device or the partial opening device has functioned correctly) so that the opening device can take over the gripping device and perform the remaining opening. The pre-opened gripping device is further opened by the opening device after being guided through the partial opening device.

[0021] In case all gripping devices are pre-opened (second application), the partial opening device is arranged upstream of the opening device and the degree of opening of the gripping devices is determined to a position that approximately corresponds to the closed position of the gripping devices. In this way, all gripping devices that are guided past are pre-opened in the partial opening device and the partially opened gripping devices are conveyed further to the opening device and fully opened.

[0022] If, being guided through the partial opening device, the gripping device is partially opened to a less than predetermined degree of opening, a partial opening device (connected in parallel to the opening device) is arranged in the region of a further opening device or downstream of the opening device. In this case, when leaving the opening device (if the further opening device functions correctly), the desired degree of opening corresponds to the normal degree of opening of the gripping device. Thus, the gripping device guided by the opening device with insufficient opening is fully opened by the partial opening device. The gripping device that is insufficiently opened by the opening device is ultimately fully opened by the partial opening device.

[0023] The predetermined pre-opening degree is, for example, at least 1%, at least 5%, at least 10% or at least 15%, and the predetermined full opening degree is, for example, at least 85%, at least 90% or at least 95%. In particular, the predetermined opening degree can be set by the position of the partially opening disc.

[0024] The pre-opening time of the gripping device is extended in comparison with conventional opening devices, so that the gripping device is subjected to less mechanical stress during the opening operation, which ensures a complete opening and also extends the operating life of the gripping device.

[0025] The tongues of the gripping devices in the pre-opening state mechanically contact the relevant contact surfaces of the partially-opened disk. At any one time, a single gripping device contacts the contact surface of the rotating partially-opened disk at a selected position and / or diameter of the partially-opened disk. Also, several (at least two) gripping devices simultaneously contact the contact surface of the rotating partially-opened disk at selected positions and / or diameters. However, with pre-opening of gripping devices which only partially open, compared to the operation of a forced opening device, the mechanical stresses are significantly reduced and the relative speed between the gripping devices or tongues and the driven partially-opened disk is reduced or even set to zero.

[0026] In an embodiment of the invention, the partial opening device pre-opens the gripping device with an opening degree in the range of more than 0% to at least 5%, preferably at least 10%, particularly preferably at least 15%. In another embodiment of the invention, the (or another) partial opening device pre-opens the gripping device with an opening degree of at least 95%, preferably at least 90%, particularly preferably at least 85%. The percentage is related to the travel distance over which the gripping surface of the gripping device moves from the closed state to the open state.

[0027] The partial opening of the gripping device allows the gripping device to be opened particularly reliably in the following cases: Jamming of the gripping device (or the tongues and / or at least one gripping surface), if at least one gripping surface adheres to and / or catches the web of material being conveyed, Residual material and / or deposits prevent the gripping device from opening, and / or Due to the high moving speed of the gripping device, the inertia of the moving parts of the gripping device makes it more difficult to open the gripping device.

[0028] In particular, the opening operation of the gripping device can be driven in synchronization with the moving speed of the gripping device. A synchronous drive with respect to the moving speed of the gripping device is performed by setting a substantially non-slip state or a desired slip between the partially opening gripping device and the partially opening disk. For example, the contact surface of the partially opening disk with respect to the partially opening gripping device can be driven in synchronization with a slip occurring within the range of -10% to +10%, preferably -5% to +5%, and suitably 0% to +3%. In this way, the preliminary opening operation (or the full opening operation) can be guided by the partially opening disk, reducing the mechanical stress on the contact surface acting on the gripping device. In this way, the operating life of the gripping device and the partially opening disk can be extended.

[0029] The drive of the gripping device is a direct drive or an articulated drive, for example a belt drive, a chain drive and / or an electric motor, for example a synchronous motor, is used for the drive.

[0030] Also, the position of the partially opening disc can be adjusted in the transverse (TD) and / or longitudinal (MD) directions. In this way, the degree of opening of the gripping device can be predefined. To adjust the position of the partially opening disc, the partially opening device has at least one positioning device, the adjustment can also be performed manually. The at least one positioning device has, for example, at least one linear motor and / or one linear guide. Likewise, the positioning device comprises, for example, a transmission, such as a trapezoidal screw shaft, which converts a rotary drive movement into a linear movement.

[0031] The term "MD" refers to the "machine (longitudinal) direction," while the term "TD" refers to the "transverse direction." The MD is the longitudinal direction in which the stretching device conveys the thin film material (especially the resin thin film), and is the main conveying direction along the length of the thin film material. In contrast, the TD is the direction perpendicular to the MD (the plane of the thin film material).

[0032] The position of the partially open disc can also be adjusted vertically. The vertical direction is perpendicular to the horizontal plane of the thin film material. In this way, the partially open disc can be placed in positions that vary in three dimensions (vertical, horizontal and vertical). The vertical direction can be manually adjusted. In particular, the vertical position can be specified once (e.g. by a slot during assembly) or the vertical position can be adjusted manually. A positioning device can be provided for this purpose.

[0033] It is preferred that the position of each of the partially open discs can be adjusted independently in the longitudinal, lateral and / or vertical directions. For this purpose, individually driveable / adjustable motor shafts or positioning devices can be provided.

[0034] In particular, the partial opening device comprises a control device for varying the speed of the partial opening disc, for which purpose the control device can control the drive device to set the partial opening disc to a desired slip level.

[0035] The optimum position of the partially open disk depends on the film side edge thickness of the thin film material being transported. The film side edge thickness of the thin film material gripped by the gripping device is the thickness of the thin film material (particularly a synthetic resin thin film) that is sandwiched between the two gripping surfaces of the gripping device in the gripped state. The position of the tongue changes depending on the film side edge thickness, so the position of the contact point where the tongue first comes into contact with the rotating contact surface of the partially open disk also changes. Through positioning of the partially open disk in the longitudinal, lateral and / or vertical directions, the desired contact point (and the preset degree of opening for preliminary opening or full opening) is set according to the film side edge thickness, so that the mechanical load is reduced as much as possible during preliminary opening and / or full opening, and the gripping device can be opened reliably.

[0036] For example, the non-contact opening device (e.g., magnetic opening device) is given the option of opening the pre-opened gripping device completely and reliably after the partially opening disk arranged thereon. After the pre-opening, the non-contact opening device takes over the pre-opened gripping device and continues the opening process. It is preferable to move the gripping device and continue the opening process before the pre-opened gripping device starts to close again. Similarly, for the ideal complete opening, for example, a parallel or forward non-contact opening device (e.g., magnetic opening device) moves the already widely opened gripping device or the gripping device that is not opened correctly to the positioned partially opening device and completely opens it. As mentioned above, the partial opening device can only perform the pre-opening of the gripping device that needs the pre-opening and completely open it by the opening device (first application example) or pre-open all the guided gripping devices by the partial opening device (second application example).

[0037] For example, the thin film side edge thickness can be input into a user interface of a computing device for purposes of positioning the partially open disk, after which the ideal position of the partially open disk can be calculated and the partially open disk can be manually positioned.

[0038] In particular, the contact surface of the partially open disc has a profile cross-section. The profile cross-section of the contact surface of the partially open disc can be adjusted to the contact area of ​​the tongue of the partially open gripping device, preferably independently of the longitudinal contact point location from the film side edge thickness of the film material (e.g. plastic film) held by the opening gripping device. The profile cross-section of the partially open disc can achieve an ideal pre-opening or full opening and guarantee a small function of the film side edge thickness without modifying or repositioning the partially open disc.

[0039] The partially open disc can be made of synthetic resin or metal. For example, the partially open disc can be made of a high-temperature resistant resin such as polyetheretherketone (PEEK). When the partially open disc is made of metal, the peripheral surface of the partially open disc can be selectively coated at least partially. For example, the coating material comprises a synthetic resin coating, in particular polyetheretherketone. In this way, the tongue and the partially open disc can be provided with resistance to abrasion, scratches and mechanical stresses.

[0040] The object of the invention is also achieved by an opening device for opening a gripping device, in particular a gripping device of a stretching device, comprising at least one partial opening device as described above and a magnetic opening device, which opens the gripping device using a magnetic force when the gripping device is guided past the magnetic opening device, the magnetic force being generated using at least one permanent magnet and / or at least one electromagnet.

[0041] Furthermore, at least one partial opening device can be arranged vertically to perform a pre-opening of the gripping device.

[0042] For example, a partial opening device can be arranged in front of or in part of at least the effective area of ​​the magnetic opening device, and a partial opening device can be arranged in that area or upstream of that area for pre-opening. When the effective areas of the magnetic opening device and the partial opening device overlap, the gripping devices to be pre-opened can simply be moved to the magnetic opening device, or only these gripping devices can be pre-opened to an opening degree below a predetermined opening degree. Here, the magnetic opening device can be used and the predetermined opening degree can be suitably selected to correspond to the opening degree of the gripping devices to achieve a normal opening degree. In this case, all gripping devices passing the partial opening device can be set to a specific opening degree (pre-opening degree) by the partial opening device.

[0043] A partial opening device can be further arranged in the longitudinal direction to fully open the gripping device. For example, a partial opening device is arranged after the effective area of ​​the magnetic opening device and / or at least in at least a part of the effective area for full opening. If the effective areas of the magnetic opening device and the partial opening device overlap, the gripping device that is not fully opened but is already partially opened is simply transferred to the partial opening device. In this case, a predetermined preferred degree of opening is selected which corresponds to the degree of opening that the gripping device would normally achieve after leaving the magnetic opening device. With full opening, the partial opening device ensures that the entire gripping device is opened after passing the partial opening device.

[0044] The effective area of ​​the magnetic opening device is the area where a magnetic force acts on the tongue of the gripping device sufficient to actuate the tongue.

[0045] A partial opening disk is arranged in the longitudinal direction of the front area of ​​the magnetic opening device, particularly in the front third area (relative to the effective area length L of the magnetic opening device), and at least one partial opening device is arranged relative to the magnetic opening device.

[0046] At least one partial opening device is arranged relative to the magnetic opening device, and the contact point of the partial opening disk is arranged at a distance d from the point where the maximum magnetic force acts on the opening gripping device. In particular, when the effective area length of the magnetic opening device is represented by L, the distance d is within a range of L to L / 2 mm, preferably L to L / 3 mm, and particularly preferably L to L / 5 mm.

[0047] The distance at which the partial opening disc engages the area just before / just after the maximum magnetic force is preferably selected so that the gripping device does not open after the maximum magnetic force is exceeded, and the partial opening device takes over the partially opened gripping device and further opens it before the gripping device starts to close again, i.e. before the gripping device closes again.

[0048] The opening device also includes a mechanical pressure opening device disposed in the direction of movement of the gripping device after the magnetic opening device and the partial opening device. The mechanical pressure opening device ensures that the gripping device is always opened before the gripping device grips the thin film material again. In normal operation, the opening device is set so that the partial opening device and the magnetic opening device are fully opened. For example, the mechanical pressure opening device is used only as a backup means that can be used in the event of a failure of the partial opening device.

[0049] The web of material to be released from the gripping device is fixed to the gripping device before release. The unreleased or only partially released gripping device grips, conveys and guides the web of material to be released, the tongues rub against the web of material to be released and the gripping device is actuated to force a complete opening. Similarly, the opening wheel completely opens the gripping device. When guiding the gripping device past the stationary opening wheel, the stationary opening wheel actuates the tongues to completely open the gripping device.

[0050] The object of the present invention is also achieved by a stretching apparatus, in particular a transverse orienter, a longitudinal orienter and / or a simultaneous stretching apparatus, which comprises a number of gripping devices for gripping a strip-shaped material (e.g., a thin film) to be stretched. The stretching apparatus also comprises an opening device of the above-mentioned type. The strip-shaped material to be stretched while supported between a pair of rails is usually guided by the gripping devices along the two rails, and the gripping devices are guided in a circular manner. An opening device is assigned to each of the pair of rails.

[0051] In a machine direction orienter, the strip of material is stretched in the machine direction (MD). In a transverse direction orienter, the strip of material is stretched in the transverse direction (TD). Machine direction and transverse direction orienters may be combined to stretch first in the machine direction and then in the transverse direction (or vice versa). In a simultaneous stretcher, the machine direction and transverse direction stretching occur simultaneously.

[0052] A thin film stretching device is used to stretch a thin film made of resin such as polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polyamide (PA), etc. The side edge thickness of the thin film is in the range of 2 to 200 μm, preferably 2 to 100 μm, and particularly preferably 2 to 50 μm. The moving speed of the gripping device is, for example, more than 400 m / min, preferably more than 500 m / min, and particularly preferably more than 600 m / min.

[0053] The object of the invention is also achieved by a method for opening a gripping device, in particular a gripping device of a stretching device, which comprises the following steps: a partial opening step of partially opening the gripping device by at least one partial opening device as described above; a magnetic release step of releasing the gripping device using a magnetic release device; A forced opening process in which the gripping device is selectively and forcibly opened using a mechanical forced opening device without being completely opened after the gripping device has passed through the partial opening device and the magnetic opening device.

[0054] In addition to the preliminary opening, the gripping device can be fully opened, which is a reliable and wear-resistant opening of the gripping device and allows for a long operational life. [Brief description of the drawings]

[0055] Other features and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: [Figure 1] Plan view of the stretching device [Diagram 2] FIG. 11 is a plan view showing another embodiment of a stretching device. [Diagram 3] A perspective view of the gripping device [Figure 4] Side view of the gripping device [Diagram 5] Schematic block diagram of the opening device [Figure 6] A side view of the partial opening disc of the partial opening device [Figure 7] A perspective view of a partial opening device [Figure 8] Flowchart of a method for releasing a gripping device DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0056] Each of Figures 1 and 2 illustrates a drawing apparatus 10. The drawing apparatus 10 includes a furnace 14 and two drives 16. The pair of drives 16 are arranged mirror-symmetrically with respect to the axial plane S of the drawing apparatus 10 and at least partially within the furnace 14. The drawing apparatus 10 includes an inlet region 18 for feeding a thin film material into the drawing apparatus 10 and an outlet region 20 for discharging the thin film material from the drawing apparatus 10, and the drives 16 are provided to protrude outside the furnace 14 at the inlet region 18 and the outlet region 20. It will be understood that the drives 16 are provided completely through the furnace 14.

[0057] In addition to the entrance region 18 and the exit region 20, the stretching apparatus 10 has at least three other regions 22, 24, and 26. The regions 22, 24, and 26 are disposed adjacent to one another and along the film transport direction, i.e., normal draw direction R, of the stretching apparatus 10, with the entrance region 18 adjacent to a first region 22, which is adjacent to a second region 24, which is adjacent to a third region 26, which is finally adjacent to the exit region 20.

[0058] In a first region 22 constituting a preheating region of the stretching apparatus 10 adjacent to the entrance region 18, the pair of drivers 16 are spaced apart from each other by a first gap E. A plurality of regions 22-26 are successively adjacent to the heat treatment region 26. Other regions may be similarly provided between the regions 22, 24 and 26. For example, a cooling region for further cooling the stretched and heat-treated thin film may be provided after the heat treatment region 26.

[0059] The gap between the two drivers 16 in the stretching region 24 constituting the second region gradually increases from the start of the stretching region 24 to a second gap A which is the start of a third region 26 constituting the heat treatment region.

[0060] Each drive device 16 includes a rail 17 that guides a number of gripping devices 28. The gripping devices 28 are moved along the rail 17 by the drive of each drive device 16. The gripping devices 28 can also be driven directly. In this case, the rail 17 is configured as, for example, a linear motor.

[0061] Although two gripping devices 28 are shown diagrammatically for each drive device 16 shown in FIGS. 1 and 2, an actual stretching apparatus 10 will include multiple gripping devices 28 positioned along the rails 17.

[0062] The rails 17 of each drive unit 16 form a closed loop from the entry area 18 to the exit area 20 and back to the entry area 18 from which they started. The return section of the rails 17 which form the outward path is oriented in the direction required for the movement of the gripping device 28 between the entry area 18 and the exit area 20 within the furnace 14.

[0063] The positive operating return section of rail 17, which provides a return path from exit region 20 to entrance region 18, is located within furnace 14 in the illustrated embodiment (FIG. 1), whereas in the embodiment of FIG. 2, the return path from exit region 20 to entrance region 18 is located outside furnace 14.

[0064] During operation of the stretching apparatus 10, the film material 12 to be stretched is fed into the entrance region 18 of the stretching apparatus 10 in a pulling direction R. To this end, both side edges of the film 12 moving in the pulling direction are gripped by opposite drives 16.

[0065] Both side edges of the thin film material (e.g., the side edges of the thin film) are specifically gripped in place by clamping devices 30 (FIG. 3) of gripping device 28 and moved in the pulling direction (longitudinal, or machine direction) along rails 17 of drive device 16 as gripping device 28 moves.

[0066] The thin film material 12 in the entrance region 18 has a width E perpendicular to the pulling direction R that corresponds to a first spacing E between the pair of actuators 16 .

[0067] The web material 12 is then heated in a first region 22 where it is fed. In a subsequent second region, or heating region 24, the web material 12 is stretched as the spacing between the pair of drivers 16 increases continuously in the transverse direction and optionally in the longitudinal or machine direction. At the end of the second region 24, the web material 12 is formed to a second width A.

[0068] Upon completion of the stretching process in the second region 24, the thin film material 12 proceeds to a third region 26 where it is heat treated to relax or relieve internal stresses, after which it is cooled and released from the gripping device 28 at the exit region 20 and the thin film material 12, now formed to a second width A, exits the stretching device 10.

[0069] For example, the stretching device 10 may be an orienter that stretches the thin film material 12 in the transverse direction, and may also be a machine direction orienter that stretches the thin film material 12 in the length (tensile R) direction.

[0070] In some cases, a simultaneous stretching device is used in the second or stretching zone 24 to simultaneously stretch in the tensile direction R as well as in the transverse direction perpendicular to the tensile direction.

[0071] During processing of the thin film material 12, large tensile forces in the machine or transverse direction act on the gripping device 28, particularly in the second region, the stretching region 24. The tensile force direction is dominated by the main direction P (FIG. 3) of the gripping device 28, and has a small transverse force component relative to the main direction.

[0072] The gripping device 28 must be able to withstand high tensile forces, particularly in the main direction P of the tensile force, which is a lateral direction parallel to the side edges of the thin film material 12 that the gripping device 28 grips.

[0073] A gripping device 28 for gripping the thin film material 12 must be provided close to the input region 18, and the tensile force of the gripping device 28 must be reliably absorbed by a fastening device 30. At the exit region 20, the gripping device 28 must again be released to release the stretched thin film material 12 from the gripping device 28. A release device 100 (FIG. 5) is provided for releasing the gripping device 28 and returning the gripping device 28, having released its grip on the thin film material 12, to the entrance region 18.

[0074] A perspective view of the gripping device 28 or clamping device 30 is illustrated in Figure 3. Figure 4 is a side view of the gripping device 28. The gripping device 28 comprises a main complement 32 and two guides 34 attached to the main complement 32. The main complement 32 comprises a base 36 and the actual clamping device 30 that is attached to the base 36 and grips the thin film material 12.

[0075] The base 36 of the main complement 32, which carries the clamping device 30, constitutes the gripping side of the thin film material 12. The opposite side of the base 36, which does not have the clamping device 30, constitutes the guide side on which the guide 34 is mounted. The guide 34 runs along the rail 17 of the drive 16. The main complement 32 thus has a gripping side of the thin film material 12 and a guide side on which the guide 34 is mounted.

[0076] The clamping device 30 of the illustrated embodiment is provided with a base 36 as a base, a lower gripping surface 37 integrally molded on the base 36, and a tongue (operating rod) 38 constituting an upper gripping surface 38. A fixing portion 40 or a fixing opening through which the side edge of the thin film material 12 to be gripped is inserted into the gripping device 28 is formed by the upper gripping surface 38 of the clamping device 30.

[0077] The main direction P of the pulling force applied to the gripping device 28 is perpendicular to the edge of the web material 12 that is fixed in place by the gripping device 28. For example, the main direction P of the pulling force is substantially to the left in Figure 3. The web material 12, whose side edges are fixed to the gripping device 28, exerts a pulling force on the gripping device 28 primarily in the second region (stretching region) 24 in the pulling direction, i.e. the main direction P.

[0078] Each of the pair of guiding devices 34 includes a support arm 42 and at least one guide piece 44 attached to the support arm 42. The guiding device 34 of the gripping device 28 illustrated in Fig. 3 includes, for example, a drive element 46 that constitutes a chain or a part of a chain of the drive device 16. An engagement protrusion that constitutes a part of a belt or a linear motor of the drive device 16 can be used for the drive element 46.

[0079] The guide pieces 44 in the illustrated embodiment are formed as rollers. In other embodiments, sliding and / or magnetic bodies, such as permanent magnets or ferromagnetic bodies, can be used for the guide pieces 44.

[0080] The guide device 34 defines a mounting gap 48 for mounting the rail (also called a "guide rail") 17. In particular, a mounting gap 48 for fitting the rail 17 is provided in each support arm 42 of the guide device 34.

[0081] The mounting gap 48 is therefore located on the front or guide side of the main complement 32. The guide pieces 44, which in particular constitute the rollers and possibly the sliders, protrude or are located in the mounting gap 48 and serve as supports and guides for the rails 17.

[0082] The clamping device 30 of the gripping device 28 / guide device 34 is shown in Figure 4. The lower gripping surface 37, which is formed of a rigid material, is part of the base 36. The upper gripping surface 38 moves between a closed position and an open position. The tongue 39 is actuated to cause the upper gripping surface 38 to move in a rotational manner. Figure 4 shows the upper gripping surface 38 and tongue 39 in the closed position and the upper gripping surface 38' and tongue 39' in a closed condition.

[0083] 5 shows a schematic diagram of an opening device 100 for opening the gripping device 28 of the stretching device 10. The opening device 100 includes a partial opening device 150 and a magnetic opening device 120. When the gripping device 28 on the rail 17 is guided past the magnetic opening device 120, the magnetic opening device 120 is actuated to open the gripping device 28 using a magnetic force.

[0084] The partial opening device 150 is disposed in the machine direction of a front region of the magnetic opening device 120, particularly the third front region (with respect to the effective area length L of the magnetic opening device 120).

[0085] The effective area of ​​the magnetic opening device 120 overlaps vertically with the partial opening device 150 as shown, so that the gripping devices to be pre-opened are simply transferred from the partial opening device 150 to the magnetic opening device 120. Depending on the application, the partial opening device 150 can be configured to pre-open gripping devices that require pre-opening in order to be fully opened by the partial opening device 150 (first application) or to pre-open all gripping devices 28 that have been previously guided (second application).

[0086] In the illustrated embodiment, at the exit area, an opening device 100 releases the thin film material 12 from the gripping device 28 and separates the thin film material 12 from the gripping device 28, while at the entrance area 18, a deflector 19 on the rail 17 returns the gripping device 28 from the open state to a gripping state so that the thin film material 12 can be gripped again by the gripping device 28.

[0087] For example, when the thin film material 12 cannot be successfully released from the gripping device 28 due to malfunction of the partial opening device 150 and / or the magnetic opening device 120, a forced opening device 190 can be provided to forcibly open the gripping device 28 and separate the thin film material 12 from the gripping device 28 before it reaches the entrance area 18 again.

[0088] For example, a side view of the partial opening disk 160 of the partial opening device 150 shown in Fig. 7 is shown in Fig. 6. The partial opening disk 160 is driven to rotate around a rotation axis 161.

[0089] The partially-opening disc 160 comprises a circumferential surface 162 having a rotating contact surface 164. As the gripping device 28 is guided past the partially-opening disc 160, the tongues 39 of the gripping device 28 engage the rotating contact surface 164 and the gripping device 28 is pre-opened or fully opened. In the illustrated embodiment, the tongues 39 of the gripping device 28 are actuated by the partially-opening disc 160 to move the upper gripping surface 38 of the gripping device 28 from the closed position to the partially-open position. The gripping device 28 is thus pre-opened and then moves to the magnetic opening device 120 for further opening.

[0090] Similarly, the tongue 39 of the gripping device 28 can be actuated by the partial opening disk 160 to move to the partially open position, and further the upper gripping surface 38 of the gripping device 28 can be moved from the partially open position to the fully open position. In this manner, the gripping device 28 can be moved once by the magnetic opening device 120 to completely release the thin film material 12.

[0091] The partially open disc 160 shown in FIG. 6 is arranged in the longitudinal machine direction (MD) and transverse direction (TD) and is moved or actuated by a distance X from the first contact point of the tongue 39, which starts to contact the partially open disc 160 at a contact point 165 between the rotating contact surface 164 and the tongue 39 of the gripping device 28, until the tongue 39 is removed from the partially open disc 160. The distance X or the position of the partially open disc 160 is set so that the gripping device 28 is pre-opened in an opening angle range of 0% to at least 5%, preferably at least 10%, particularly preferably at least 15% greater. Similarly, the distance X or the position of the partially open disc 160 can be set so that the gripping device 28 is opened at an opening angle of at least 95%, preferably at least 90%, particularly preferably at least 85%. The percentage corresponds to the distance that the upper gripping surface 38 of the gripping device 28 moves from the closed position to the open position.

[0092] 7 is a schematic diagram of a partial opening device 150 used for preliminary or complete opening. The partial opening device 150 can in principle replace an existing opening device or form part of the opening device 100 according to the invention.

[0093] 6, and a direct or indirect drive unit 170 that rotates the partial opening disc 160. For example, the drive unit 170 includes a belt or chain drive unit 172 and a synchronous motor. The contact surface 164 of the partial opening disc 160 has a sliding range of -10% to +10%, preferably -5% to +5%, and particularly preferably 0% to +3%, relative to the gripping device 28 where the tongue 39 is partially opened.

[0094] The partial opening device 150 shown in Fig. 7 comprises position adjustment devices 166, 167 for adjusting the position of the partial opening disc 160 in the transverse (TD) direction and / or the longitudinal, machine (MD) direction R, for example via screw drives 168, 169. The position of the partial opening disc 160 can also be adjusted in the vertical direction Z. For this purpose, separate position adjustment devices (not shown) can be provided.

[0095] In particular, the partial opening device 150 may be provided with a control device 200 (FIG. 7) that varies the speed of the partial opening disc 160 .

[0096] FIG. 8 shows a flow chart of an opening method 1000 for opening the gripping device 28 of the stretching device 10, which includes the following steps: As described above, a pre-opening process 1100 of pre-opening the gripping device using at least one partial opening device 150; a magnetic release process 1200 for releasing the gripping device using the magnetic release device 120; and a forced opening process 1300 for selectively forcibly opening the gripping device 28 using a mechanical force opening device after guiding the gripping device 28 through the partial opening device 150 and the magnetic opening device 120 when the gripping device does not open smoothly.

[0097] It will be understood that the preliminary opening process 1100 and the magnetic opening process 1200 are performed in a special order for the gripping device to be pre-opened. It is possible to perform the preliminary opening first, then the opening, and finally the full opening. However, in case of implementation or emergency, only the forced opening is performed after the preliminary opening process 1100 and the magnetic opening process 1200. When the gripping device for which the preliminary opening is required is pre-opened by the partial opening device and then fully opened (first application example), only the gripping device can be opened by the magnetic opening device 120. For the gripping device guided through the partial opening device, at least a predefined preliminary opening is achieved, and then the full opening is applied to the gripping device that is fully opened by the opening device. Therefore, the present invention can of course be implemented in other ways than those currently implemented without diminishing the important features of the present invention. The embodiments of the present invention are merely illustrative, and the present invention should not be interpreted as being limited to the embodiments, and all changes and modifications of the embodiments are intended to be included in the scope of the claims under the doctrine of equivalents. [Explanation of symbols]

[0098] 10 ·· stretching device, 12 ·· thin film material, 14 ·· heating furnace, 16 ·· drive device, 17 ·· rail, 18 ·· inlet region, 19 ·· deflection device, 20 ·· outlet region, 22 ·· first region (preheating region), 24 ·· second region (stretching region), 26 ·· third region (heat treatment region), 28 ·· gripping device, 30 ·· clamping device, 32 ·· main supplementary part, 34 ·· guide part, 36 ·· base part, 37 ·· lower gripping surface, 38 ·· upper gripping surface, 39 ·· tongue, 40 ·· fixing part, 42 ·· support arm, 44 ·· guide piece, 46 ·· drive element, 48 ·· mounting gap, 100 ·· release device, 120 ·· magnetic release device, 150...partial opening device, 160...partial opening disk, 161...rotating shaft, 162...circumferential surface, 164...rotating contact surface, 166...position adjusting device, 167...position adjusting device, 168...screw drive device, 169...screw drive device, 170...drive device, 172...belt or chain drive device, 190...forced opening device, 200...control device, 1000...method, 1100...partial opening (pre-opening or full opening), 1200...opening, 1300...forced opening, A...second width, E...first width, P...main direction, R...machine direction, S...target surface, TD...transverse direction, X...gap, Z...vertical direction, L...effective area length,

Claims

1. A partial opening device (150) for pre-opening a gripping device (28), particularly a gripping device of a stretching device (10), comprising at least one partial opening disk (160) and a drive device (170) for driving the at least one partial opening disk (160), At least one partially open disk (160) has a circumferential surface (162) having a rolling contact surface (164); As the gripping device (28) is guided through the partially open disc (160), the tongues (39) of the gripping device (28) engage the rolling contact surfaces (164) of the partially open disc (160); A partial opening device (150) characterized in that the tongue (39) guided through the partial opening disc (160) has a predetermined degree of opening at which the gripping device (28) is pre-opened.

2. The partial opening device (150) according to claim 1, wherein the drive device (170) generates a slip within a range of -10% to +10%, preferably -5% to +5%, and more preferably 0% to +3% with respect to the moving speed of the partially opening gripping device (28) to synchronize the rotating contact surface (164) of the partially opening disc (160).

3. 3. The partial opening device (150) according to claim 1 or 2, wherein the drive (170) is a direct drive or an articulated drive driven by a belt or chain.

4. The position of the partial opening device (150) is adjusted in the pull direction and / or the machine direction; The partial opening device (150) according to any one of claims 1 to 3, preferably comprising at least one positioning device (166, 167) for adjusting the position of the partial opening disc (160) in the tensile direction and / or in the machine direction.

5. The partial opening device (150) according to any one of claims 1 to 4, characterized in that the position of the partial opening disc (160) is vertically adjustable.

6. The partial opening device (150) according to claim 4 or 5, characterized in that the partial opening device (150) comprises a control device (200) for varying the position of the partial opening disc (160).

7. The rolling contact surface (164) of the partially open disc (160) has a contoured cross-section; A partially opening device (150) according to any one of claims 1 to 6, wherein the profile cross-section of the rolling contact surface (164) is adapted to the contact position of the contact point in the machine direction between the tongue (39) of the partially opening gripping device (28) and the rolling contact surface (164) of the partially opening disc (160), preferably independently of the film side edge thickness of the film material (12) gripped by the partially opening gripping device (28).

8. The partially open disk (160) is made of a polymer or metal. The partial opening device (150) of any one of claims 1 to 7, wherein the circumferential surface (162) is selectively at least partially coated with a polymeric coating.

9. In the opening device (100) of the gripping device (28), in particular the gripping device (28) for the stretching device, The device comprises at least one partial opening device (150) according to any one of claims 1 to 8 and a magnetic opening device (120), As the gripping device (28) is guided past the magnetic opening device (120), the magnetic opening device (120) uses magnetic force to release the gripping device (28); An opening device (100) characterized in that at least one partial opening device (150) is arranged in the machine direction (R) for pre-opening the gripping device (28).

10. The opening device (100) according to claim 9, wherein the partial opening device (150) is positioned relative to the magnetic opening device (120) by positioning the contact point of the partial opening disc (160) in the machine direction of the front area, particularly at front number 3 of the magnetic opening device (120).

11. The opening device (100) of claim 9 or 10, wherein the contact point (165) of the partial opening disc (160) is spaced forward or rearward of the point at which the maximum magnetic force acts on the gripping device (28) to be opened, and the partial opening device (150) is positioned relative to the magnetic opening device (120).

12. 11. The opening device (100) according to claim 9 or 10, further comprising a mechanical forced opening device (190) arranged in the direction of movement of the gripping device, behind the magnetic opening device (120) and the partial opening device (150).

13. A number of gripping devices (28) for gripping a strip of material, particularly a thin film, to be stretched; A stretching device (10), in particular a transverse direction orienter, a machine direction orienter and / or a continuous stretching device, characterized in that it comprises an opening device (100) according to any one of claims 9 to 12.

14. 14. A stretching apparatus (10), in particular a thin film stretching apparatus, according to claim 13, wherein the stretching apparatus (10) has a movement speed of the gripping device of more than 400 m / min, preferably more than 500 m / min and particularly preferably more than 600 m / min.

15. In a method (1000) for opening a gripping device, in particular a gripping device (28) of a stretching device (10), a pre-opening step (1100) of pre-opening the gripping device (28) guided through the partial opening disc (160) by at least one partial opening device (150) according to any one of claims 1 to 8 to a degree of opening below a predetermined degree of opening; a magnetic release process (1200) for releasing the gripping device (28) using a magnetic release device (120); and a forced opening process in which, if the gripping device (28) is not successfully opened and the gripping device (28) is guided through the partial opening device (150) and the magnetic opening device (120), the gripping device is selectively and forcibly opened using a forced opening device (190) which mechanically forcibly opens the gripping device.

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