Stretching device and method for reducing non-uniform air temperature and asymmetric air flow in thin film stretching device
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-05-26
- Publication Date
- 2026-03-12
AI Technical Summary
Existing thin film stretching devices face issues with non-uniform transverse temperature and asymmetric air flow, leading to film property defects and non-uniform film properties.
A stretching apparatus and method that includes a heating furnace with a conditioning device featuring air blowers and ventilation holes arranged symmetrically to counteract imbalanced air flow, using a regulating device to equalize air flow and temperature within the furnace.
The solution effectively reduces non-uniform temperatures and asymmetric air flow, preventing film defects and enhancing the quality of manufactured thin films.
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Abstract
Description
[Technical Field]
[0001] The present invention relates to a thin film stretching apparatus and method that reduces non-uniform air temperatures and asymmetric air flows within the apparatus for stretching a thin film. [Background technology]
[0002] Various stretching devices are particularly suitable for the production of thin plastic films. A thin film is transported by a conveying device through the heating furnace of the stretching device and is usually stretched in the drawing direction within the stretching device. Before the stretching process, the thin film to be stretched is heated in the heating furnace, and the thin film is maintained at a predetermined temperature during and between the stretching processes. The stretched thin film is subsequently cooled in the heating furnace.
[0003] It is essential to maintain a uniform film temperature in the transverse direction (perpendicular to the drawing direction) throughout the entire process. If the film temperature is not maintained uniformly, the film will be stretched in the transverse direction at different times, i.e., not simultaneously, which can result in multiple film property defects and multiple non-uniform film properties. Non-uniform temperature control in the transverse direction, for example, improper air flow in the drawing direction, can cause uneven cold air flow into the heating furnace, resulting in film property defects. Summary of the Invention [Problem to be solved by the invention]
[0004] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a stretching apparatus and method for reducing non-uniform transverse temperatures in thin films. [Means for solving the problem]
[0005] The object of the present invention is achieved by a thin film stretching apparatus, particularly a transverse stretching apparatus, a longitudinal stretching apparatus, and / or a simultaneous stretching apparatus, including a heating furnace and an adjusting device. The heating furnace has a height direction, a transverse direction, and a drawing direction. The adjusting device has a blower, a first vent (first adjusting vent), and a second vent (second adjusting vent), the first vent and the second vent opening into the heating furnace opposite each other in the height direction and the drawing direction of an imaginary central plane of the heating furnace. The blower is disposed between the first vent and the second vent so as to be fluidly connected. The adjusting device draws or removes air from the heating furnace through one of the first vent and the second vent, and supplies the drawn or removed air into the heating furnace through the other of the first vent and the second vent.
[0006] The air flow can be reduced or stopped by generating a cross or lateral air flow from the adjusting device on the opposite side of the film. The air drawn in from one side of the imaginary central plane is simultaneously supplied to the furnace on the other side of the imaginary central plane at a flow rate equal to the drawn air flow rate, so that the air temperature or air flow rate in the furnace is not unbalanced.
[0007] The conditioning device does not need to be provided with a temperature regulator for the air being conveyed.
[0008] However, it may be useful to provide a temperature control device, such as a heat exchanger, within the conditioning device to eliminate specific air temperature differences within the furnace and / or to compensate for heat losses occurring in the conditioning device.
[0009] Temperature control devices that eliminate specific air temperature differences are particularly closed systems.
[0010] The vents of the regulator are, for example, not located beyond the imaginary center plane of the furnace.
[0011] The first and second vents may be formed in the same configuration to improve uniformity of air flow, but this is not a requirement of the present invention.
[0012] In an embodiment of the present invention, when the first vent hole and the second vent hole are arranged at substantially the same or symmetrical positions in the withdrawal direction of the imaginary central plane of the heating furnace, there is no need to generate longitudinal air flow in the adjustment device itself.
[0013] In other embodiments of the present invention, the first and second vents are located at the film entrance area into the furnace or at the film exit area from the furnace, thereby preventing excessively cold or hot air from entering the drawing apparatus from outside.
[0014] For example, the first and second vents can be located in the neutral zone of the furnace, the upstream zone and / or the downstream zone of the neutral zone. The neutral zone can be located between two zones of the furnace with significantly different air temperatures, such as the annealing zone and the cooling zone, thereby preventing air flow between different zones along a significant temperature gradient and allowing the stretching apparatus to operate efficiently.
[0015] In an embodiment of the present invention, the first and second vent holes are arranged laterally outside the thin film running track provided in the heating furnace and / or at the same height as the thin film running track, and the thin film is not adversely affected by the air blown out from the adjustment device.
[0016] Two flow openings are provided as the first ventilation hole and the second ventilation hole, one of which is arranged above the thin film running track and the other below the thin film running track to prevent air from being blown directly onto the thin film.
[0017] The flow area is particularly arranged vertically from below to above the thin film running track or laterally above or below the thin film running track, while, for example, each of the first and second vents has multiple flow openings arranged in at least one flow area. When the first and second vents have multiple flow openings, air is not only sucked from or supplied to the heating furnace in a point-like manner from each flow opening, but also sucked or supplied over a wide area, thereby preventing inappropriate air flow interaction with the thin film.
[0018] Also, a plurality of flow spaces may be provided.
[0019] Placing the blower outside the processing chamber helps to avoid contamination of the processing chamber.
[0020] Additionally, filters may be provided in the conditioning unit, particularly in the conditioning unit's conduits, to purify the air within the furnace and improve the quality of the thin film produced.
[0021] The use of a centrifugal blower effectively provides a conditioning device.
[0022] For example, a first vent may be fluidly connected to a blower via a first conduit and a second vent may be fluidly connected to the blower via a second conduit to form a predetermined flow path.
[0023] In particular, thermal insulation of the conduits reduces heat losses caused by the conditioning device and reduces air temperature differences within the furnace.
[0024] An embodiment of the present invention can be provided in which the conditioning device includes a first distribution box fluidly connected to the discharge side of the blower and a second distribution box fluidly connected to the suction side of the blower, and the first conduit and the second conduit each branch into two branches, one branch fluidly connected to the first distribution box and the other branch fluidly connected to the second distribution box, to control the air flow.
[0025] The distribution box (foldable box) is, for example, a two-way distributor.
[0026] For example, when the distribution box is in a first state, the first conduit is fluidly connected to the suction side of the blower and the second conduit is fluidly connected to the discharge side of the blower, and when the distribution box is in a second state, the first conduit is fluidly connected to the discharge side of the blower and the second conduit is fluidly connected to the suction side of the blower, so that by switching the distribution box between the first and second states, the air flow within the adjustment device can be switched between forward flow and reverse flow.
[0027] The stretching device may be provided with one or more sensors for determining the air flow direction and / or one or more pressure sensors to automatically control the adjustment device.
[0028] There is also provided an embodiment of the invention in which the drawing apparatus is provided with a conveying device for conveying the film through the furnace in the drawing direction, particularly along the film run track, thereby achieving a high level of process reliability.
[0029] A conveying device of this kind is known, for example, from patent document WO 2014 / 094803 A1.
[0030] Vents are provided laterally outside the conveyor and / or in the furnace next to it.
[0031] a step of measuring the flow rate and / or pressure of the air flow in the drawing direction on one side of the imaginary center plane of the heating furnace of the drawing device; The object of the present invention is achieved by a method for reducing uneven temperatures and asymmetric air flow in a drawing device, the method including the steps of: operating an adjusting device in response to measurement results from the measuring step to draw air from the heating furnace through a first vent hole on one side of an imaginary central plane of the heating furnace, and supplying air from the other side of the imaginary central plane to the heating furnace through a second vent hole.
[0032] The process of measuring the air flow rate can be automated using multiple detectors, or can be performed manually using, for example, a manual flow meter.
[0033] The features and advantages described above with respect to the drawing apparatus are equally applicable to the method of the present invention, and vice versa.
[0034] Other features and advantages of the present invention will become apparent from the following detailed description of the invention which proceeds with reference to the accompanying drawings, in which: [Brief explanation of the drawings]
[0035] [Figure 1] 1 is a schematic plan view of a stretching device according to the present invention; [Figure 2]Cross-sectional view taken along line II-II in Figure 1 [Figure 3] FIG. 2 is a perspective view showing a part of an adjustment device of the stretching device of FIG. 1; [Figure 4] A shortened cross-sectional view of the stretching device of FIG. [Figure 5] 1 is a shortened cross-sectional view of a second embodiment of a stretching device according to the present invention; [Figure 6] 10 is a shortened cross-sectional view of a third embodiment of the stretching device of the present invention; [Figure 7] 4 is a shortened cross-sectional view of a fourth embodiment of the stretching device of the present invention; [Figure 8] 10 is a shortened cross-sectional view of a fifth embodiment of the stretching device of the present invention; [Figure 9] Enlarged cross-sectional view taken along line AA in FIG. 8. DETAILED DESCRIPTION OF THE INVENTION
[0036] FIG. 1 shows a schematic plan view of a stretching apparatus 10 of the present invention.
[0037] The illustrated stretching apparatus according to the first embodiment of the present invention is a transverse stretching apparatus, also called a transverse direction orienting machine (TDO). Instead of a transverse stretching apparatus, the present invention may also be implemented in a longitudinal stretching apparatus or a simultaneous stretching apparatus.
[0038] The stretching device 10 includes a heating furnace 12 , a conveying device 14 , and an adjusting device 16 .
[0039] A drawing direction R for moving the thin film to be drawn is given to the heating furnace 12. A horizontal lateral direction Q perpendicular to the drawing direction R and a vertical height direction H are also given to the heating furnace 12.
[0040] The furnace 12 is provided with a plurality of processing zones, such as different heating, stretching and annealing zones, for processing the thin film being stretched along the drawing direction R.
[0041] In the first preheating zone 22, the film is heated. Following the first zone 22, in the second stretching zone 24, the film is stretched in the transverse direction Q, so that the width of the film at the end of the second zone 24 is greater than at the start of stretching.
[0042] When passing through the third zone 26 of the heat treatment zone, the additional heating zone and / or the annealing (slow cooling) zone, the internal stress of the stretched thin film is relieved or relaxed at different elevated temperatures.
[0043] The thin film then passes sequentially through a fourth region 28 of the neutral zone and a fifth region 30 of the cooling zone, which cools the thin film.
[0044] For example, a fourth region 28, which is a neutral region that is simply a passage space without ventilation function, physically separates the third region 26 and the fifth region 30.
[0045] At least a part of the conveying device 14 , which is provided mirror-symmetrically with respect to the imaginary central plane M of the stretching device 10 or the heating furnace 12 , includes two conveying rails 32 laid inside the heating furnace 12 .
[0046] A plurality of conveying rails 32 are positioned outside the furnace 12 at an entrance region 34 where the film to be stretched enters the stretching apparatus 10 and at an exit region 36 where the film exits the stretching apparatus 10 .
[0047] The thin film is gripped in a known manner by a plurality of gripping devices (not shown) of the conveying device 14 guided along the conveying rail 32 and conveyed through the heating furnace 12 in the drawing direction R. The thin film is guided along a thin film running track F (FIG. 2) provided within the heating furnace 12 and conveyed by the conveying device 14. The thin film running track F is provided on both sides of an imaginary central plane M.
[0048] FIG. 2 is a cross-sectional view of the stretching apparatus 10 taken along line II-II of FIG.
[0049] In FIG. 2, the thin film running track F between the plurality of transport rails 32 provided in the heating furnace 12 is indicated by a chain line, and the thin film is indicated by a broken line.
[0050] 2, multiple jets of heated air indicated by arrows are ejected in the direction of the thin film trajectory F. The thin film is heated or maintained at a predetermined temperature by contact with the heated air.
[0051] At least two detectors 40 are optionally provided, one on each side of the imaginary central plane M of the membrane runway F or transport rail 32 area. The detectors 40 measure the air flow direction and / or the air pressure prevailing at the detectors 40. Instead of the detectors 40, the air flow direction can be determined manually, for example by means of a manual flow meter placed at the measurement point.
[0052] The conditioning device (equalizer) 16 includes a blower 42, a first distribution box 44, a second distribution box 46, a first conduit 48, a second conduit 50, a first vent 52, and a second vent 54.
[0053] The blower 42 , the first distribution box 44 , the second distribution box 46 , the first conduit 48 and a portion of the second conduit 50 are located outside the furnace 12 , including, for example, on the housing of the furnace 12 .
[0054] The first conduit 48 and the second conduit 50 are disposed within the furnace 12, and the first vent 52 and the second vent 54 are disposed only within the furnace 12.
[0055] The first vent hole 52 and the second vent hole 54 are arranged on opposite sides of an imaginary central plane M within the heating furnace 12. In particular, the first vent hole 52 and the second vent hole 54 are provided outside the thin film running track F in the lateral direction Q and outside the conveying device 14, for example, beside the conveying device 14.
[0056] The first ventilation hole 52 and the second ventilation hole 54 are arranged at substantially the same position in the drawing-out direction R. For example, the offset between the first ventilation hole 52 and the second ventilation hole 54 in the drawing-out direction R is less than 2 m, particularly less than 1 m.
[0057] For example, the first vent hole 52 and the second vent hole 54 are disposed within the same region or between multiple regions among the first region 22, the second region 24, the third region 26, the fourth region 28, and the fifth region 30.
[0058] In the illustrated embodiment, the first vent 52 and the second vent 54 are located in a region within the furnace 12 that is directly adjacent to the membrane inlet inlet region 34. In the example of FIG. 1, the first vent 52 and the second vent 54 are located within the first region 22.
[0059] The first vent hole 52 and the second vent hole 54 may be provided in the heating furnace adjacent to the outlet region 36 of the thin film outlet. The first vent hole 52 and the second vent hole 54 may also be arranged in the fourth region 28, which is the neutral region. Furthermore, the first vent hole 52 and the second vent hole 54 may also be arranged in the third region 26 of the heat treatment region or the fifth region 30 of the cooling region. Depending on the arrangement positions of the first vent hole 52 and the second vent hole 54, the necessary detector 40 can be displaced in the extraction direction R and arranged.
[0060] Also, multiple adjustment devices 16 may be provided in different areas.
[0061] The first vent 52 shown in FIG. 2 is fluidly connected to the blower 42 via the first conduit 48, and similarly, the second vent 54 is fluidly connected to the blower 42 via the second conduit 50, thereby allowing fluid communication between the first vent 52 and the second vent 54 by directing air from the blower 42 from one to the other.
[0062] In the closed system adjustment device 16, air inside the heating furnace 12 that is sucked in from one of the first air vent 52 and the second air vent 54 can be supplied into the heating furnace 12 from the other of the first air vent 52 and the second air vent 54.
[0063] In the illustrated embodiment, the adjustment device 16 is configured without using a temperature control device such as a heater or cooler, but can thermally insulate the first conduit 48 and the second conduit 50 outside the furnace 12 to prevent temperature fluctuations between the first vent 52 and the second vent 54.
[0064] For example, in an alternative embodiment, one or both of the first conduit 48 and the second conduit 50 may be provided with a temperature control device 55, such as a heat exchanger.
[0065] Additionally, one or both of the first conduit 48 and the second conduit 50 may include one or more filters 57 for filtering the air flowing through the conditioning device 16 .
[0066] FIG. 3 is a partial perspective view of the adjustment device 16 showing the connection state of the blower 42.
[0067] The blower 42 in the illustrated embodiment is a centrifugal blower having a suction side and a discharge side.
[0068] The first distribution box 44 is directly connected and fluidly coupled to the discharge side of the blower 42. The second distribution box 46 is directly connected and fluidly coupled to the suction side of the blower 42.
[0069] The first distribution box 44 and the second distribution box 46 together form a two-way distributor that fluidly connects, for example, a first conduit 48 and a second conduit 50 .
[0070] The first conduit 48 and the second conduit 50 are each branched into two branches, a first branch 56 and a second branch 58, with the first branch 56 of the first conduit 48 and the first branch 56 of the second conduit 50 being fluidly connected to the first distribution box 44, and the second branch 58 of the second conduit 50 and the second branch 58 of the first conduit 48 being fluidly connected to the second distribution box 46.
[0071] The first distribution box 44 and the second distribution box 46 are switched between a first state and a second state, respectively, and the first distribution box 44 in the first state fluidly connects the second conduit 50 to the discharge side of the blower 42, and the second distribution box 46 fluidly connects the first conduit 48 to the suction side of the blower 42.
[0072] When the first distribution box 44 and the second distribution box 46 are in the first state, air from the heating furnace 12 is sucked in through the first air vent 52 and then supplied back to the heating furnace 12 through the second air vent 54, so that the first air vent 52 serves as an air outlet (suction port) from the heating furnace 12 and the second air vent 54 serves as an air inlet (exhaust port) to the heating furnace 12.
[0073] When the first distribution box 44 and the second distribution box 46 are switched from the first state to the second state, the first distribution box 44 fluidly connects the first conduit 48 to the discharge side of the blower 42, and the second distribution box 46 fluidly connects the second conduit 50 to the suction side of the blower 42, so that the second vent 54 in the second state forms an air outlet (suction port) from the furnace 12 and the first vent 52 forms an air inlet (exhaust port) for the furnace 12. Therefore, the air flow direction in the second state of the first distribution box 44 and the second distribution box 46 is reversed compared to the first state.
[0074] FIG. 4 is a cross-sectional view that schematically shows the positions of the first vent hole 52 and the second vent hole 54 relative to the thin film running track F indicated by the dashed line.
[0075] 4, the first ventilation holes 52 and the second ventilation holes 54 are arranged laterally beside the transport device 14 and the thin film running track F. In the height direction H, the first ventilation holes 52 and the second ventilation holes 54 are arranged at the same height as the thin film running track F.
[0076] In particular, the first vent hole 52 and the second vent hole 54 are not disposed beyond the imaginary central plane M.
[0077] The first ventilation hole 52 and the second ventilation hole 54 are formed in the same shape.
[0078] During normal operation of the stretching device 10, an inappropriate air flow is generated on the opposite side of the imaginary central plane M in the drawing direction R indicated by the arrow L in FIG. 1 and in the opposite direction. In the present invention, however, the inappropriate air flow L is reduced by implementing the following method.
[0079] First, the air flow rate of the air flow L in the drawing direction R is measured by the detector 40. Instead of the detector 40, for example, the direction and rate of the air flow can be determined manually by placing a yarn at the measurement point.
[0080] The flow rate of the flowing air may be determined by measuring the pressure difference between the pressures on both sides of the imaginary central plane M.
[0081] In the example shown in Figure 1, above the imaginary central plane M in Figure 1 (left side in Figure 2), the air flow L before the adjustment device 16 is activated flows into the heating furnace 12, whereas on the opposite side of the imaginary central plane M (below the imaginary central plane M in Figure 1, right side in Figure 2), the air flow is discharged from the heating furnace 12.
[0082] After measuring the air flow L (which can also be done manually), when the adjustment device 16 is operated, inappropriate air flow L flows into the heating furnace 12 on one side of the imaginary central plane M. At this time, the first and second states of the first distribution box 44 and the second distribution box 46 are selected to create a state in which air from the adjustment device 16 is supplied to the heating furnace 12 from one of the first air vent 52 and the second air vent 54, and the other air vent becomes an air inlet that draws air into the heating furnace 12.
[0083] In the illustrated embodiment, it is the first vent 52 that draws air into the furnace 12, so the first distribution box 44 and the second distribution box 46 are switched to the second state.
[0084] Next, when the blower 42 is operated, air is sucked in from the heating furnace 12 through the second vent hole 54 and discharged, and an amount of air equal to the amount of discharged air is supplied to the heating furnace 12 through the first vent hole 52.
[0085] In this way, an air flow counter to the air flow L is generated, thereby damping the inappropriate air flow L.
[0086] The speed of the blower 42 is increased until the inadequate air flow L reaches a minimum or stops completely. The speed of the blower 42 can be controlled automatically or manually.
[0087] For example, 4000m per hour 3 (especially m 3 An air flow rate of less than 1 / hour can be delivered by the blower 42.
[0088] Therefore, the inappropriate air flow L that causes the temperature difference Q across the thin film can be minimized or completely prevented by operating the regulator 16.
[0089] This reliably avoids uneven temperature differences and uneven air flow that can cause a deterioration in the quality of the thin film being produced, thereby improving the quality of the thin film being produced.
[0090] The drawings in Figures 5, 6, 7 and 8 show another embodiment of the stretching device 10 of the present invention (which essentially corresponds to the first embodiment), but in the additional drawings, parts that are functionally the same as those shown in Figure 4 are given the same symbols, and only the differences are explained.
[0091] In a second embodiment shown in FIG. 5, the first vent 52 and the second vent 54 each have two flow openings 60 .
[0092] The flow opening 60 of the first vent 52 is fluidly connected to the first conduit 48 and the flow opening 60 of the second vent 54 is fluidly connected to the second conduit 50 .
[0093] Similar to the first embodiment, the plurality of flow openings 60 are arranged outside the thin film running track F in the lateral direction Q.
[0094] The two flow openings 60 are respectively arranged above and below the thin film running track F in the height direction H. To be precise, one of the two flow openings 60 of the first vent hole 52 and one of the multiple flow openings 60 of the second vent hole 54 are arranged above the thin film running track F, but the other of the two flow openings 60 of the first vent hole 52 and the other of the two flow openings 60 of the second vent hole 54 are arranged below the thin film running track F, so that the air from the adjustment device 16 is not blown directly onto the thin film.
[0095] The suction flow rate or supply flow rate of the air flowing above and below the thin film running track F can be controlled and set by changing the internal flow path cross-sectional area of the throttle valves 61 (shown by dashed lines in Figure 5) provided between each of the two flow openings 60 of the first air vent 52 and the second air vent 54.
[0096] FIG. 6 shows a cross-sectional view of a third embodiment of drawing apparatus 10 in which each flow region 62 of first vent 52 and second vent 54 has multiple flow openings 60 .
[0097] The flow apertures 60 may be formed as a plurality of slots, circular apertures, oval apertures, polygonal apertures, or combinations thereof, and the size of each aperture may also vary.
[0098] Since the multiple flow regions 62 of the third embodiment are set in the height direction H from above the thin film running track F to below the thin film running track F, the multiple flow openings 60 can be arranged at substantially the same height relative to the thin film running track F on both the above and below sides of the thin film running track F.
[0099] The plurality of flow regions 62 are arranged in a transverse direction Q of the thin film running track F.
[0100] Similar to the third embodiment of FIG. 6, the fourth embodiment of FIG.
[0101] Unlike the third embodiment, in the fourth embodiment of FIG. 7, a plurality of flow regions 62 are connected in a horizontal lateral direction Q to each of the first vent hole 52 and the second vent hole 54 .
[0102] Specifically, two flow areas 62 are provided for each of the first ventilation hole 52 and the second ventilation hole 54, one flow area 62 being positioned above the thin film running track F and the other flow area 62 being positioned below the thin film running track F.
[0103] The plurality of flow regions 62 are disposed in a direction Q transverse to the imaginary central plane M, but do not intersect the imaginary central plane M.
[0104] For example, the entire flow area 62 is arranged in the horizontal direction Q along the multiple conveying rails 32 and partially along the thin film running track F, so that the multiple flow areas 62 can be arranged to partially extend beyond and protrude outward from the conveying device 32 and the thin film in the horizontal direction Q.
[0105] The flow openings 60 open in the drawing direction R and / or in a direction opposite to the drawing direction R.
[0106] 8 and 9 show a fifth embodiment of a stretching device 10 according to the invention, which substantially corresponds to the fourth embodiment of FIG.
[0107] Unlike the fourth embodiment, the flow openings 60 in FIG.
[0108] 9 are formed in the direction of the thin film travel path F.
[0109] The flow openings 60 of the multiple flow areas 62 provided below the thin film running track F are formed on the upper surface of the conduit forming the flow area 62, and the flow openings 60 of the multiple flow areas 62 provided above the thin film running track F are formed on the lower surface of the conduit forming the flow area 62.
[0110] Therefore, the air flow discharged from the plurality of flow openings 60 is ejected upward or downward in the height direction H and substantially perpendicular to each thin film running track F.
[0111] The multiple flow regions 62 shown in the third, fourth and fifth embodiments further reduce the interaction of the membrane with inappropriate air flow.
Claims
1. A stretching apparatus (10) for stretching a thin film, particularly a transverse stretching apparatus, a longitudinal stretching apparatus and / or a simultaneous stretching apparatus, comprising a heating furnace (12) and an adjusting device (16), The height direction (H), the lateral direction (Q) and the film drawing direction (R) are specified in the heating furnace (12), The conditioning device (16) has a blower (42), a first vent (52), and a second vent (54); the first vent hole (52) and the second vent hole (54) are arranged opposite to each other in the height direction (H) and the drawing direction (R) of the imaginary central plane (M) of the heating furnace (12) and are open into the heating furnace (12); a blower (42) disposed in fluid communication between the first vent (52) and the second vent (54); The drawing apparatus (10) is characterized in that the adjustment device (16) sucks air from within the heating furnace (12) through one of the first air hole (52) and the second air hole (54) and supplies air to the heating furnace (12) through the other of the first air hole (52) and the second air hole (54).
2. 2. The drawing device according to claim 1, wherein the first vent hole (52) and the second vent hole (54) are formed in the same shape.
3. 3. The drawing device according to claim 1, wherein the first vent hole (52) and the second vent hole (54) are arranged at substantially the same position in the drawing direction (R) along the imaginary central plane (M).
4. 2. The drawing apparatus of claim 1, wherein the first vent (52) and the second vent (54) are located in the region of the film entrance into the furnace (12) or the region of the film exit from the furnace (12).
5. 2. The drawing apparatus of claim 1, wherein the first vent (52) and the second vent (54) are located in the neutral zone (28) of the heating furnace (12), in the heat treatment zone (26) of the heating furnace (12) upstream from the neutral zone (28), and / or in the cooling zone (30) of the heating furnace (12) downstream from the neutral zone (28).
6. 2. The stretching apparatus according to claim 1, wherein the first vent hole (52) and the second vent hole (54) are arranged outside in the lateral direction (Q) of the thin film running track (F) provided in the heating furnace (12) and / or are arranged at the same height in the height direction (H) of the thin film running track (F).
7. 7. The drawing apparatus according to claim 6, wherein the first vent (52) and the second vent (54) have two flow openings (60) respectively arranged above and below the film running track (F).
8. The first vent (52) and the second vent (54) each have a plurality of flow openings (60) disposed in at least one flow region (62); The flow region (62) is arranged in a height direction (H) from below to above the thin film running track (F), or 7. A drawing device according to claim 6, wherein the flow area (62) is arranged in the transverse direction (Q) above or below the film running track (F).
9. The blower (42) is located outside the furnace (12) and / or 2. The drawing apparatus according to claim 1, wherein the blower (42) is a centrifugal blower.
10. The first vent (52) is fluidly connected to the blower (42) through a first conduit (48); 2. The drawing apparatus of claim 1, wherein the second vent (54) is fluidly connected to the blower (42) through a second conduit (50).
11. The conditioning device (16) includes a first distribution box (44) fluidly connected to the discharge side of the blower (42) and a second distribution box (46) fluidly connected to the suction side of the blower (42); 11. The drawing device according to claim 10, wherein each of the first conduit (48) and the second conduit (50) is branched into two branches (56, 58), one of which is fluidly connected to the first distribution box (44) and the other of which is fluidly connected to the second distribution box (46).
12. The distribution boxes (44, 46) are switched between a first state and a second state, 12. The drawing apparatus of claim 11, wherein when the distribution boxes (44, 46) are in the first state, the first conduit (48) is fluidly connected to the suction side of the blower (42) and the second conduit (50) is fluidly connected to the extrusion side of the blower (42).
13. 2. The drawing device according to claim 1, wherein the drawing device (10) comprises a detector (40) for detecting the flow direction and / or the flow pressure of the air flow (L).
14. 2. The stretching apparatus according to claim 1, wherein the stretching apparatus (10) comprises a conveying device (14) for moving the thin film in the heating furnace (12) along the thin film running track (F) in the drawing direction (R).
15. measuring the flow rate and / or flow pressure of the air flow (L) in the drawing direction (R) on one side of the imaginary central plane (M) of the heating furnace (12) of the drawing device (10); and operating an adjusting device (16) in response to the results of the measuring process to suck air from within the heating furnace (12) through a first vent (52) on one side of an imaginary central plane (M) of the heating furnace (12) and supply an amount of air to be sucked into the heating furnace (12) through a second vent (54) on the other side of the imaginary central plane (M).