Nozzle box and drawing apparatus with associated nozzle box

Abstract

The invention relates to an improved nozzle box, which comprises the following features: side walls (3b) spaced apart from one another, a bottom (3a) and a ventilation wall (5) spaced apart from the bottom, thereby forming an interior space (2); a plurality of ventilation openings (7) are provided in the ventilation wall (5), which are arranged offset from one another; the nozzle box (1) is provided with a plurality of protrusions (13) on its ventilation wall (5), which protrude with at least one height (H) relative to the section of the ventilation wall (5) adjacent to the protrusions (13) or relative to the upper side or surface (5a) of the ventilation wall (5); the ventilation openings (7) are configured protruding relative to the upper side or surface (5a) of the ventilation wall (5) in the region of the protrusions (13); and / or the ventilation wall (5) has opposite side flanges (19a, 19b) in the transverse direction (Q) of the nozzle box (1), which overlap the side walls (3b) of the nozzle box (1) outside the interior space (2) of the nozzle box (1).

Description

Technical Field

[0001] The present invention relates to a nozzle box and a stretching device having the nozzle box. Background Technology

[0002] For example, such nozzle boxes are used to heat or cool web-like materials, especially in the form of plastic films, particularly in the manufacture of plastic films. These nozzle boxes, used as ventilation nozzles, are generally positioned transversely, i.e., usually perpendicular to the traction direction of the material web, and thus transversely above and / or below the material web in the direction of web travel.

[0003] Here, two or more such nozzle boxes can be assembled above or below the material web to form a ventilation zone, that is, to constitute a so-called ventilation module. The ventilation module, including the associated nozzle box, can have a length, for example, extending laterally along the material web to 1.5 m, 3 m, 5 m, 7.5 m, or even 10 m and greater.

[0004] Depending on the intended use, the ventilation module can, for example, heat air in the preheating zone of the stretching equipment, thereby heating the plastic film. For this purpose, the air is typically heated and preheated using a heater / heating recorder. If the ventilation module is used in a cooling zone, the film can also be cooled with corresponding cooling air. In this case, ambient air is usually drawn in and blown onto the film. The air can also be pre-cooled or a mixture of ambient and warm air can be used. In recirculating air operation, cooler air (compared to the film's temperature) is typically blown onto the film.

[0005] The ventilation module can be configured as either a closed (recirculated air system) or an open (using ambient air) system. When heating material webs, especially plastic films, a closed ventilation system is typically used. This system uses a fan positioned on the side to blow air into the interior space of the nozzle box. The air is then blown out through outlet nozzles in the nozzle box towards the material web / plastic film. The blown air can recirculate between these nozzle boxes, either above or below them. For this purpose, a so-called back-suction box can be provided above or below the nozzle box, or simply a free space can be provided to draw back the blown air and reheat it within the closed system, then resupply the air via the fan. For heating, a heat exchanger can be used, for example. That is, in this recirculated air operation, the air can be circulated multiple times.

[0006] In a preferred embodiment of the invention, the ventilation module with nozzle box is used in wide-width stretching machines or wide-width stretching furnaces, particularly for continuous film stretching equipment or also for synchronous film stretching equipment.

[0007] A nozzle box suitable for the stated purpose is known, for example, from EP 0 907 476 B1. The nozzle box known therefrom comprises, internally, a plurality of air supply chambers extending longitudinally and interconnected. The nozzle box itself has ventilation or nozzle walls or sides, in which a plurality of vents are typically formed, i.e., air outlets or exhaust ports for blowing out air. For this purpose, a plurality of perforated vents are typically formed in a plurality of parallel rows. Here, the nozzle box is typically mounted above and below the material web in a stretching device, such that the so-called ventilation or nozzle wall is oriented toward the material web. In this case, the design of the air outlets or exhaust ports themselves can be configured differently, thus considering both perforated air outlets and nozzle boxes with slit-shaped air outlets.

[0008] An air nozzle device is also known from CN 106003679 B. Multiple outlets are formed on the nozzle outlet side of the nozzle wall, and these outlets can be arranged in a specific pattern. To achieve a specific effect, cylindrical protrusions are provided on the inner side of the nozzle (i.e., the inner side opposite to the nozzle outlet side), thereby increasing the length of the nozzle.

[0009] For completeness, it should also be mentioned that this mainly applies to long nozzle boxes, which, due to manufacturing technology, consist of at least two or more parts that are assembled longitudinally during installation in the stretching equipment.

[0010] Especially in the manufacture and stretching of plastic films used as battery separators (i.e., particularly in the so-called WET process), a series of additives, especially oils, are mixed into the material of the plastic film to be stretched. As the film passes through the oven during the stretching process, the oil flows out from and deposits in the moving material. This results in, particularly for nozzle boxes positioned below the advancing plastic film, the separated oil depositing in the area of ​​the nozzle box's ventilation walls. The separated oil may even then reach the interior of the nozzle channel through the outlet.

[0011] However, oil can enter the nozzle box through any conceivable opening, notch, or slit, such as through flanges, plate joints, etc.

[0012] This results in the oil that eventually enters the nozzle box being partially reabsorbed by the circulating air during operation and blown out along with it. As a result, this oil reaches the surface of the plastic film to be stretched, and this causes an undesirable impact on the quality of the plastic film to be manufactured, i.e., stretched. Summary of the Invention

[0013] Therefore, the object of the present invention is to realize an improved nozzle box, which is particularly for ventilation modules and for stretching devices having such nozzle boxes.

[0014] Regarding the ventilation module, the objective is achieved by a nozzle box according to the invention, the nozzle box having the following characteristics:

[0015] - It has side walls spaced apart from each other, a bottom, and ventilation walls spaced apart from the bottom, thereby forming an interior space.

[0016] - The ventilation wall has multiple staggered ventilation openings.

[0017] - The nozzle box has a plurality of protrusions on its ventilation wall, these protrusions protruding at least one height relative to the section of the ventilation wall adjacent to the protrusion or relative to the upper side or surface of the ventilation wall.

[0018] - The ventilation openings are offset from the upper side or surface of the ventilation wall within the raised area, such that the ventilation openings are farther away from the internal space than the upper side or surface of the ventilation wall adjacent to the raised area.

[0019] and / or

[0020] - The ventilation wall has side flanges opposite each other in the transverse direction of the nozzle box, the side flanges overlapping the side wall of the nozzle box outside the internal space of the nozzle box.

[0021] Furthermore, in terms of the stretching equipment, the objective is achieved using a stretching device having a nozzle box according to the invention.

[0022] The key advantage of the solution according to the invention lies primarily in the fact that, by means of simple measures, oil can be prevented from reaching the area of ​​the nozzle orifice and thus entering the interior of the nozzle housing. Therefore, this also prevents the gaseous treatment medium (typically in the form of air) flowing through the nozzle orifice from entraining deposited oil or oil droplets located therein within the nozzle housing and carrying them towards the film, thereby preventing undesirable oil deposition on the plastic film. When "film" is mentioned here or thereafter, whether referred to as a plastic film or simply as a film or membrane, it refers to any possible material.

[0023] According to the invention, this is ensured by a preferred, specially designed protruding section that is arranged or formed around the vent. Alternatively or preferably additionally, the vent wall has a special shape having side flanges opposite each other in the transverse direction of the nozzle box, the side flanges overlapping the side wall of the nozzle box outside the internal space of the nozzle box.

[0024] In a preferred variation, the protruding section can be introduced into the ventilation wall of the nozzle box via a simple pressing process. The ventilation wall is preferably composed of a sheet metal wall and can therefore be configured as an embossed or deep-drawn portion within the sheet metal wall. In other words, the ventilation opening with the aforementioned protruding section can be created in the nozzle box during a single, simultaneous punching and / or pressing process.

[0025] The shape of the protruding section can be designed in different ways. In this case, the outer boundary of the ventilation protrusion preferably tapers at least slightly from the plane or the outside of the ventilation wall along the protrusion direction. In particular, when the vent is circular, the protruding section is preferably constructed as a frustoconical shape, that is, having a flattened end face for the protruding section. In this case, the end face section surrounding the vent has a width dimension that preferably varies between 0.5 mm and 5 mm for circular or elliptical vents.

[0026] The angle of the cone or conical shape, that is, the angle relative to the outer boundary of the protruding section that is steeply inclined to a certain extent and surrounds the vent, must differ only slightly from a straight line perpendicular to the vent wall, so as not to form a cylinder. Angles less than or equal to 89.75° are already advantageous and beneficial to the stamping process. However, the angle itself can also be achieved and have smaller values, such as 45° and smaller. All values ​​between these angle values ​​are also suitable.

[0027] Furthermore, in a preferred embodiment, the vented wall of the nozzle box, with its vents, is constructed continuously along the transverse direction of the nozzle box. That is, the vented wall is not composed of multiple vented wall segments that extend parallel to each other along the longitudinal direction of the nozzle box and are laterally connected to each other. This prevents oil from entering the interior of the nozzle box through slit-like gaps formed at the flanges on the sides of this multi-part vented wall and then being further conveyed outwards towards the plastic film via the supplied air through the vents.

[0028] Therefore, the continuous ventilation walls in the transverse direction of the nozzle box are preferably provided with angular flanges on the outside, which overlap the adjacent sidewalls of the nozzle box on the outside, so that oil cannot enter the interior of the nozzle box.

[0029] Wherever the nozzle box is composed of at least two or more parts assembled together in the longitudinal direction due to its large length, there are additional special raised ventilation wall edge sections on the ventilation wall (in addition to the preferred overlapping wall sections), so that no gaps are formed extending from the upper or outer side into the interior of the nozzle box, which terminate on the plane of the upper side or surface of the vent, through which oil may enter the interior of the nozzle box.

[0030] Within the scope of this invention, the protruding section, and especially its height, can be designed to have a very small size.

[0031] Finally, the protruding section can also be configured such that it forms not just one vent, but, for example, two (or more) vents within the protruding platform. In other words, it is not necessary to form a separate, independent protrusion for each vent. Attached Figure Description

[0032] Other advantages, details and features of the invention will be apparent from the embodiments described below with reference to the accompanying drawings.

[0033] Specifically:

[0034] Figure 1 A schematic perspective view of the nozzle box according to the present invention is shown;

[0035] Figure 2 Show Figure 1 The nozzle box shown is a schematic transverse cross-sectional view in the transverse direction and perpendicular to the longitudinal direction;

[0036] Figure 3 A magnified detail view of the vent in the raised area is shown in a cross-sectional view. Figure 1 and Figure 2 The nozzle box shown in the image is constructed on the ventilation wall;

[0037] Figure 4 A partial perspective view of two adjacent protrusions is shown, the protrusions having vents formed therein;

[0038] Figure 5 Showing relative to Figure 3 and 4 A slightly modified embodiment;

[0039] Figures 6a to 6c Three partial vertical cross-sectional views are shown along the longitudinal direction of the two nozzle channel sections, which can be assembled together at the end sides in the region, and respectively before assembly, during end-side assembly, and after the end-side assembly of the two nozzle boxes is completed.

[0040] Figures 7a to 7c Three different examples are shown in a top view to illustrate how vents can be configured or oriented differently;

[0041] Figure 8 A schematic diagram of a ventilation module having four nozzle boxes according to the invention is shown, these nozzle boxes being arranged in a parallel orientation and laterally offset from each other along the traction direction of the material web; and

[0042] Figure 9 A schematic end-side view is shown of multiple nozzle boxes arranged above and below the material web along the traction direction of the plastic film web, wherein discharge and / or receiving containers for collecting oil are arranged between the nozzle boxes arranged below the material web. Detailed Implementation

[0043] The following description refers to a first embodiment of the nozzle box according to the present invention.

[0044] The nozzle box 1 has a longitudinal direction L, a transverse direction Q, and a height H. The nozzle box is designed with a rectangular cross-section, although this cross-sectional shape is not mandatory.

[0045] That is, in this embodiment, the nozzle box 1 shown thus has a bottom 3a and two opposing sidewalls 3b, which in the illustrated embodiment extend laterally parallel to each other and are oriented perpendicular to the bottom 3a. Above the bottom 3a, at a distance H relative to the bottom 3a, there is a so-called ventilation or nozzle wall 5.

[0046] Thus, the sidewall 3b, bottom 3a, and ventilation or nozzle wall 5 enclose an internal space 2, also referred to as a supply chamber 4 for supplying air, which can then exit through a vent, described below. Therefore, in the illustrated embodiment, the nozzle box 1 has a rectangular cross-sectional shape as described, although other cross-sectional shapes are also possible. The sidewalls can also be designed to be curved and continuously transition into, for example, the bottom, which also curves and extends in the cross-section, without the sidewalls being separated from the bottom by a distinct edge. That is to say, within the scope of the invention, the specific shape of the nozzle box's cross-section is not important in this regard.

[0047] A plurality of vents 7 are formed in the ventilation or nozzle wall 5 extending in the longitudinal direction L. These vents are sometimes referred to as nozzle openings or vents, or generally as openings 7, regardless of their specific opening shape (i.e., circular, slit-shaped, square, etc.). In the illustrated embodiment, these vents 7 are not only staggered from each other in the ventilation or nozzle wall 5 in the longitudinal direction L, but also in a plurality of rows R staggered from each other in the transverse direction Q. It should be noted here that the form of these vents, such as their arrangement in the longitudinal direction L and the transverse direction Q, can also be different from the illustrated embodiment in any form; that is, these vents 7 are not necessarily required to be fixedly and pre-defined in the rows R relative to each other.

[0048] According to Figure 1As can be seen from the illustrated embodiment, the nozzle box 1 is composed of, or can be composed of, two nozzle box portions 1a and 1b separated in the longitudinal direction L. In order to increase the overall length, the nozzle box portions are at least indirectly fixed to and / or assembled with each other at their mutually facing end sides at an interface 9, and in particular, can be assembled on-site at the interface 9.

[0049] refer to Figure 2 A schematic transverse cross-sectional view of nozzle box 1 along the transverse direction Q and here perpendicular to the longitudinal direction L is shown.

[0050] As can be seen from the figure, the vent 7 is provided or formed in the form of a protrusion 13 in the ventilation or nozzle wall 5 or in the area of ​​such a protrusion 13. Since the nozzle box 1 and especially its ventilation or nozzle wall 5 are preferably made of sheet metal, the vent / nozzle 7 and the matching protrusion 13 formed in this way can preferably be formed in a common, simultaneous stamping and punching process.

[0051] According to Figure 2 The illustrated embodiments and according to Figure 3 Enlarged sectional view of the protrusion 13 of the vent 7 and according to Figure 4 In a partial perspective view of the two protrusions 13, the surrounding outer boundary wall 15 is formed in a conical shape or at least slightly conical shape.

[0052] That is, the outer boundary wall 15 converging conically protrudes from the ventilation wall 5 or the upper side or surface 5a formed therefrom, i.e., in the illustrated embodiment, it is truncated conical. Here, the actual vent 7 is defined by a surrounding opening edge 17, which thus forms a blunt and therefore kragerfrei-free terminating surface for the vent 7. The so-called "kragerfrei-free" terminating surface is important, especially when considering the use of a membrane or thin film as the material web. This is because even when the thin film comes into contact with the surrounding opening edge 17 in the region of the vent 7, it should be ensured that the thin film is not damaged or destroyed or even torn due to wear of the metal krager-shaped surface. In the illustrated embodiment, the opening edge 17 is formed or oriented at least approximately parallel to the upper side or surface 5a of the nozzle wall 5. However, this opening edge 17 is not necessarily required to be oriented parallel to the upper side or surface 5a of the nozzle wall 5. The opening edge 17 may also be curved, for example convex, in a cross-sectional view perpendicular to the upper side 5a, i.e., having a preferred gradually decreasing angle with the upper side or surface 5a in the direction toward the vent 7.

[0053] The opening edge 17 can preferably also be oriented at at least a small angle relative to the upper side of the nozzle wall 5 or the surface 5a. Thus, the opening edge 17 can rise from its outer edge toward the actual vent 7 at a small angle relative to the plane of the surface 5a, for example, at an angle less than 45°, less than 30°, 25°, 20°, 15°, 10° or less than 5°.

[0054] The height H of the protrusion 13 can be designed to be very small, for example, between 0.5 mm and 10 mm. The width of the surrounding opening edge 17 can also be of the same order of magnitude.

[0055] If these protrusions 13 are produced by a stamping process, a slightly tapered and diverging configuration of the protrusions 13 is preferred. However, this configuration is also advantageous even when the ventilation wall 5 is made of plastic injection molding, because the injection mold can then more easily detach from the protrusions formed in this way. However, the protrusions 13 are preferably manufactured together with or simultaneously with the vent 7 in a single processing step, especially for the case of sheet metal, for example, by stamping and punching processes, or by plastic injection molding when the ventilation or nozzle wall 5 should be made of plastic.

[0056] according to Figure 5 and Figure 3 Differently shown, the surrounding outer boundary wall 15 can also be constructed in principle as a cylinder. In this case, a slightly conical design is still preferred in this embodiment, especially extending in a slightly conical convergence from the upper side 5a of the nozzle wall 5. Therefore, (between the planes of the conical inclined boundary wall 15 and the corresponding ventilation wall 5 - Figure 3 The tilt angle α can be less than 90° to avoid forming a cylindrical configuration; that is, the tilt angle is, for example, 89.75° and smaller, advantageously less than 89.5°, 89.25°, 89°, 88°, 87°, 86°, 85°, 84°, 83°, 82°, or 81° or 80°. In other words, this angle can preferably also be less than 60°, 50°, 45° or 40°, in which case the conical shape gradually increases in the direction of the surface of the ventilation wall 5.

[0057] according to Figures 6a to 6c The following partial longitudinal sectional views show, for example, two adjacent ventilation walls 5 of nozzle box sections 1a and 1b to be assembled in the field, before, during and after assembly.

[0058] It can be seen that the ventilation wall 5 has a ventilation wall edge segment 5b protruding at least in the direction of the end side 22. The ventilation wall segment is rolled against the mounting direction of the next nozzle box, that is, preferably, for example, turned 180°, and thus adheres to the upper side 5a of the ventilation wall 5 in the form of a narrow edge strip. That is, this turned edge strip forms another protrusion or another protruding segment 113, which forms a protruding segment extending from the left side edge 20 of the nozzle box to the right side edge 20, so that oil cannot enter the interior of the nozzle box through the gap or mounting gap existing between the two nozzle boxes assembled at the end sides.

[0059] This protection is further reinforced by the fact that one of the two end-mounted ventilation walls 5 has at least one material tongue 19a or flange 19a distributed on a portion of the longitudinal extension of the nozzle boxes 1 and 1b in its end-mounting area. The material tongue 19a or flange 19a extends toward the adjacent next nozzle box 1a and is fitted into the recess 19c formed here in the end side 22 adjacent to the next nozzle box 1. Therefore, two successive nozzle box sections 1a and 1b can be assembled longitudinally even when the wall sections 5 overlap. Here, in Figure 6a The image shows a partial view of the two end sides of the nozzle box before assembly. Figure 6b The diagram shows the two end sides during axial assembly, and in... Figure 6c The image shows the two end sides after final assembly, where the material tongue or flange 19a protruding from the end side 22 of one nozzle box 1b is fitted and recessed into the adjacent end side 22 of the next nozzle box 1b, and the dividing line 23 between the ventilation wall edge segments 5b, which are respectively flipped here. Figure 6c It is located above the material tongue 19a. Therefore, the gap 23 that still exists in this part is covered and sealed towards the interior space of the nozzle box.

[0060] This prevents even the smallest gaps from forming in the assembly area through which oil deposited initially on the upper side 5a of the nozzle wall 5 could enter the internal space 2, i.e., the supply chamber 4. Therefore, it also ensures that the air supplied to the nozzle box 1 at the end cannot carry oil droplets from the internal space 2 and further transport them towards the plastic film via the vent 7.

[0061] In other words, the overlapping arrangement of the ventilation wall or nozzle wall 5 in the mounting area on its end side ensures that the oil deposited on the upper side 5a of the nozzle wall 5 can only flow outward, i.e., to the opposite longitudinal side of the nozzle box 1, and cannot enter the nozzle box.

[0062] Furthermore, in some critical cases, additional seals can still be used, introduced during installation. These seals are positioned in the area between the upper side of the material tongue 19a and the lower side of the wall segment 5c located above the material tongue. Therefore, the wall segment 5c is the area located precisely above the corresponding segment of the material tongue 19a in the final assembled state; in other words, it is the wall segment 5 located below the preferably rolled edge segment 5b facing the interior space 2 of the nozzle box 1. Thus, during disassembly, the seal must be removed (e.g., scraped off), and new sealing material must be introduced during reassembly. The sealing material can be, for example, high-temperature silicone or a similar or related material that maintains its sealing properties even at temperatures >150°C.

[0063] But usually, this sealing material is not needed at all.

[0064] Furthermore, it should be noted that, for example, reinforcement and / or strengthening parts 28 may also be provided on the inner side 2 of the nozzle box 1, below the ventilation or nozzle wall 5, but not necessarily. Figures 6a to 6c As shown in the figure. This reinforcement and / or strengthening part 28 can be designed, for example, as a wall, rib, or slat, and all possible design forms can be considered here.

[0065] according to Figure 2 The edge strips 21, shown in the transverse sectional view and formed on the lateral edge region 20 of the nozzle wall 5, also serve this purpose. These edge strips are bent relative to the ventilation / nozzle wall 5 such that they overlap the sidewall 3a externally, i.e., not inside the nozzle housing 2. The ventilation / nozzle wall 5 with the vent / nozzle opening 7 is continuous in the transverse direction Q, i.e., not two-part, so that no gaps or gaps are formed between the thus formed separate assembly parts, through which, for example, the oil mentioned and flowing from the plastic film during stretching might reach the interior of the nozzle housing 1.

[0066] according to Figure 7a As shown schematically in a partial top view, the vents 7 can also have completely different constructions or shapes, for example, they can be designed as elongated holes. In this case, these vents 7 can also be arranged side by side in multiple rows R.

[0067] according to Figure 7b A similar design is shown, which has an elongated vent 7, but the vent can be set at an angle, i.e., at an acute angle to the longitudinal direction L of the nozzle box 1, for example, the acute angle is 45° ± less than 10° or less than 25°.

[0068] According to Figure 7cThe illustration exemplarily shows that such an elongated hole can also be formed in the ventilation wall of the nozzle box along the transverse direction Q, that is, perpendicular to the longitudinal direction L.

[0069] What all embodiments have in common is that these protrusions 13 (along with at least one or more vents 7 formed thereon) are arranged at intervals on the upper side 5a of the nozzle wall 5, such that oil deposited adjacent to the protrusions 13 on the upper side or surface 5a of the vent or nozzle wall 5 can also flow toward the left or right edge of the nozzle box (i.e., along the lateral direction Q of the nozzle box), and at least for nozzle boxes disposed below the plastic film, the oil flows downward from there, in which the nozzle orifices are oriented upward toward the lower side of the plastic film. That is, in other words, there are multiple material bridges 35 on the upper side 5a of the nozzle wall 5 extending from the left side edge to the right side edge, so that oil deposited on the upper side or surface 5a of the vent or nozzle wall 5 can always flow out toward the side edge of the nozzle box, bypassing the protrusions 13.

[0070] Finally, based on the following: Figure 8 The illustration shows nozzle boxes arranged laterally relative to the traction direction 25 of the plastic film F. End-side views of these nozzle boxes are visible, showing them spaced apart from each other below the plastic film F along the traction direction 25. Typically, the corresponding nozzle boxes are also arranged above the control film / material web at equal and equal vertical spacing along the traction direction, and are oriented with their vents facing upwards towards the plastic film, as shown in the diagram. Figure 9 As shown in the diagram.

[0071] according to Figure 9 Now shown, the nozzle box 1 may have discharge devices 29, mostly in the form of oil troughs, on its sides. These discharge devices are preferably arranged at a defined angle so that the oil can flow out optimally. Thus, oil can be received in these troughs and collected in a receiving container 31 through the outlet. Furthermore, an intermediate plate, designed in a mountain-roof shape, can be introduced between the nozzle boxes to guide the oil into the grooves. The advantage of this is that the oil can be collected, and the furnace bottom is not contaminated by oil.

[0072] This is particularly conceivable, or even necessary, for the Simultaneous Stretching Process (LISIM), in which both width stretching and longitudinal stretching are performed inside the furnace. In the Sequential Stretching Process, longitudinal stretching takes place in a machine (MDO) located upstream of the furnace. Most of the oil is extruded in the MDO and does not enter the furnace. Therefore, it is expected that oil contamination in the furnace will be more severe in the LISIM process or during the transverse stretching stage following the longitudinal stretching process, and the present invention offers significant advantages in this regard.

Claims

1. A nozzle box, wherein the nozzle box has the following characteristics: - It has side walls spaced apart from each other, a bottom, and ventilation walls spaced apart from the bottom, thereby forming an interior space. - The ventilation wall has multiple staggered ventilation openings. - The nozzle box has a plurality of protrusions on its ventilation wall, these protrusions protruding at least one height relative to the section of the ventilation wall adjacent to the protrusion or relative to the upper side or surface of the ventilation wall. - The ventilation openings are offset from the upper side or surface of the ventilation wall within the raised area, such that the ventilation openings are farther away from the internal space than the upper side or surface of the ventilation wall adjacent to the raised area. and - The ventilation wall has side flanges opposite each other in the transverse direction of the nozzle box, the side flanges overlapping the side wall of the nozzle box outside the internal space of the nozzle box.

2. The nozzle box according to claim 1, characterized in that, The protrusion includes a boundary wall extending around one or at least two or more vents, the boundary wall extending at least partially in a cross-sectional view at an acute angle α and / or at least partially perpendicular to the vent wall and oriented away from the interior space.

3. The nozzle box according to claim 2, characterized in that, The tilt angle α is less than 90°.

4. The nozzle box according to claim 3, characterized in that, The tilt angle α is greater than 50°.

5. The nozzle box according to any one of claims 1 to 4, characterized in that, The protrusions are configured to converge in a conical shape at least in part of their height in a direction that extends away from the interior space.

6. The nozzle box according to any one of claims 1 to 4, characterized in that, The protruding end segment, located away from the upper side or surface of the ventilation wall, is configured to be without recesses and / or blunt.

7. The nozzle box according to claim 6, characterized in that, The protruding end segment, located away from the upper side or surface of the ventilation wall, is configured to surround the opening edge of the corresponding ventilation opening.

8. The nozzle box according to claim 7, characterized in that, The opening edge is parallel to the upper side or surface of the ventilation wall or is oriented at an angle less than 45° away from it.

9. The nozzle box according to any one of claims 1 to 4, characterized in that, The protrusion has a height greater than 0.5 mm or greater than 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm or 4.5 mm relative to the upper side or surface of the ventilation wall, and / or the protrusion has a height less than 5.0 mm or less than 4.5 mm, 4.0 mm, 3.5 mm, 3.0 mm, 2.5 mm, 2.0 mm, 1.5 mm or 1 mm relative to the upper side or surface of the ventilation wall.

10. The nozzle box according to any one of claims 1 to 4, characterized in that, The vent or at least a portion of the vent is configured in a circular, elongated, or n-sided shape in the top view, and the protrusion, together with the vent located therein, has a shape in the top view corresponding to the shape of the vent.

11. The nozzle box according to claim 10, characterized in that, The vent is centrally located within the protrusion.

12. The nozzle box according to any one of claims 1 to 4, characterized in that, The vents are spaced apart in one or more rows arranged in the longitudinal direction of the nozzle box, such that the two side edges of the ventilation wall are connected to each other by material bridges.

13. The nozzle box according to any one of claims 1 to 4, characterized in that, At least two vents are disposed in a common protrusion, and the at least two vents are surrounded by a common surrounding boundary wall.

14. The nozzle box according to any one of claims 1 to 4, characterized in that, The ventilation wall has a ventilation wall edge section protruding at the end side in a region of at least one end side, the ventilation wall edge section curving away from the plane of the ventilation wall opposite to the interior space, thereby forming a protruding and / or higher bulge section protruding relative to the upper side or surface of the ventilation wall.

15. The nozzle box according to claim 14, characterized in that, The edge section of the ventilation wall is bent or rolled to fit against the upper side of the ventilation wall.

16. The nozzle box according to claim 14, characterized in that, The protruding section is strip-shaped.

17. The nozzle box according to any one of claims 1 to 4, characterized in that, The nozzle box is composed of at least two nozzle box sections in its longitudinal direction. At least one nozzle box section has a material tongue or flange extending in the installation direction on the inner side of the ventilation wall. The material tongue or flange protrudes from the corresponding end side of the nozzle box section at the end side and is embedded in a corresponding recess in the next adjacent nozzle box. At this time, it covers the gap that may exist between the two adjacent rolled ventilation wall edge sections in the internal space of the nozzle box and seals the gap relative to the internal space of the nozzle box.

18. The nozzle box according to any one of claims 1 to 4, characterized in that, The protrusion - Formed by stamping in a ventilation wall made of metal plates and / or - It is formed of a material cap that is fitted and fixed to the ventilation wall and oil-sealed.

19. A stretching device having a nozzle box according to any one of claims 1 to 18.

20. The stretching device according to claim 19, characterized in that, Multiple nozzle boxes are staggered from each other under the plastic film along the traction direction of the plastic film, and a discharge device and / or a receiving device are provided between at least two nozzle boxes staggered from each other along the traction direction.

21. The stretching device according to claim 20, characterized in that, The discharge device and / or containment device are in the form of a receiving container for oil flowing from the upper side or surface of a ventilated wall.

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