Film stretching production line and hot air jet structure of oven unit

Abstract

The present application relates to the technical field of polymer film production, and discloses a film stretching production line and a hot air jet structure of an oven unit, wherein a first hole group includes a plurality of first ventilation holes arranged in sequence and at intervals along the width direction of the film, and a second hole group includes a plurality of second ventilation holes arranged in sequence and at intervals along the width direction of the film, and the first ventilation holes and the second ventilation holes are arranged in a staggered manner along the conveying direction of the film. In this way, the requirements for the degree of coverage of the film surface by the direct action of the hot air flow are met, and at the same time, the hot air can be sprayed onto the surface of the film in the width direction of the film, so that each position of the film in the width direction is heated uniformly; the hot air ejected outwards by the first hole group and the second hole group is a discontinuous hot air jet beam in the width direction of the film, and does not form a wind curtain, so it will not block each other in the conveying direction of the film, and can be discharged smoothly to the outside, and reflux to the inside of the hot air circulation mechanism, and the heat exchange efficiency is high.

Description

Technical Field

[0001] The present application relates to the technical field of polymer film production, and in particular to a film stretching production line and a hot air jet structure of an oven unit. Background Art

[0002] The oven unit, as an important component of the film stretching production line, provides a specific process environment for various process treatments such as preheating, stretching, heat setting and cooling of the film. The oven unit in the related art includes at least two static pressure boxes arranged on the upper and lower opposite sides of the film. The static pressure box is provided with a plurality of nozzles facing the film. The plurality of nozzles are arranged in sequence along the conveying direction of the film. The heat exchange airflow inside the static pressure box is sprayed onto the surface of the film through the nozzle and contacts the film, thereby achieving heat exchange and playing the role of heating or cooling the film.

[0003] In the related art, the nozzles on the static pressure box are usually arranged in the form of slits, that is, the nozzles extend from one side of the static pressure box to the other side in the transverse direction, and the airflow ejected outward is continuous. In addition, the number of nozzles in the form of slits is generally set to 1 or 2, and is mainly used in the field of special high-functional film production with relatively high temperature accuracy across the wide transverse width of the film. In addition, the nozzles on the static pressure box are also arranged in the form of a porous group, that is, including a plurality of air outlets, and the plurality of air outlets are arranged in sequence and spaced apart in the transverse direction, and the airflow ejected outward is discontinuous. The airflow ejected outward from the nozzles in the form of a porous group is evenly distributed on the working surface of the static pressure box, and is mainly used in the mainstream film biaxial stretching production field where the film production speed is high and the oven thermal cycle requirement is relatively large.

[0004] However, the hot air jet generated by the static pressure box configured in the oven unit of the film stretching production line in the related art cannot fully reflect the ideal heat exchange state in terms of uniformity, stability and high efficiency of the film. Summary of the invention

[0005] Based on this, it is necessary to overcome the defects of the prior art and provide a film stretching production line and a hot air jet structure of an oven unit, which can fully reflect the ideal heat exchange state in terms of uniformity, stability and high efficiency of the film.

[0006] A hot air jet structure for an oven unit, the hot air jet structure for an oven unit comprising:

[0007] Hot air circulation mechanism; and

[0008] Two static pressure box groups, the hot air circulation mechanism is connected to the two static pressure box groups, and the hot air circulation mechanism can provide hot air or cold air for the static pressure box groups; the two static pressure box groups are respectively arranged on opposite sides of the film to be processed, the static pressure box group includes a static pressure box, and the side of the static pressure box facing the film is set as a working surface, and the working surface is provided with a first hole group and a second hole group arranged in sequence along the conveying direction of the film, the first hole group includes a plurality of first ventilation holes arranged in sequence at intervals along the width direction of the film, the second hole group includes a plurality of second ventilation holes arranged in sequence at intervals along the width direction of the film, and the first ventilation holes and the second ventilation holes are staggered in the conveying direction of the film; and the first ventilation holes and the second ventilation holes are each set as an elongated hole extending along the width direction of the film, and the length dimension of the elongated hole is more than 1.5 times the width dimension of the elongated hole.

[0009] In one of the embodiments, the working surface is also provided with a first slit airflow nozzle extending along the width direction of the film, and each of the static pressure boxes has only one first slit airflow nozzle; along the conveying direction of the film, the first slit airflow nozzle is located upstream of the first hole group; the air outlet direction of the first slit airflow nozzle is inclined toward the inlet of the hot air jet structure of the oven unit.

[0010] In one embodiment, the angle formed by the air outlet direction of the first slit airflow nozzle and the conveying direction of the film is a, and a is 10° to 80°; and / or,

[0011] Guide plates are provided on opposite sides of the first slot airflow nozzle. The guide plates are located inside the static pressure box. The two guide plates are relatively spaced apart and cooperate to form a guide channel. The guide channel is connected to the first slot airflow nozzle.

[0012] In one embodiment, the static pressure box also includes an upstream side plate and a transition plate connected between the upstream side plate and the working surface; the first slit airflow nozzle is formed at the intersection of the transition plate and the working surface or on the transition plate.

[0013] In one embodiment, the static pressure box group is provided with at least two static pressure boxes, and at least two of the static pressure boxes are arranged in sequence at intervals along the conveying direction of the film, and the first and last two static pressure boxes along the conveying direction are provided with a second slit airflow nozzle on the side facing away from the film, and the second slit airflow nozzle is extended along the width direction of the film.

[0014] In one embodiment, the geometric intersection position of the center line of the first slot airflow nozzle that ejects hot air outwards and the film surface is located outside the area of ​​the static pressure box projected contour on the film surface.

[0015] In one of the embodiments, a third hole group is further provided on the working surface, and the third hole group is located between the first slit airflow nozzle and the first hole assembly, and the third hole group includes a plurality of third ventilation holes arranged in sequence and spaced apart along the width direction of the film; along the conveying direction of the film, each of the first ventilation holes and each of the second ventilation holes forms a plurality of adjacent positions, and the plurality of the third ventilation holes are arranged in one-to-one correspondence with the plurality of the adjacent positions.

[0016] In one embodiment, the lengths of the first ventilation holes are equal and are evenly arranged along the width direction of the film; the lengths of the second ventilation holes are equal and are evenly arranged along the width direction of the film.

[0017] In one embodiment, the sum of the lengths of all the first ventilation holes in the first hole group along the width direction of the film is set to S1, the sum of the lengths of all the second ventilation holes in the second hole group along the width direction of the film is set to S2, and the sum of the lengths of all the third ventilation holes in the third hole group along the width direction of the film is set to S3; 5% <S3 / S2≤20%,5%<S3 / S1≤20%,80%<S2 / S1≤120%;

[0018] The length of the interval area between two adjacent first ventilation holes along the width direction of the film is set to S4, and the length of the first ventilation hole along the width direction of the film is set to S5. <S4 / S5≤115%。

[0019] A film stretching production line comprises a plurality of the above-mentioned oven unit hot air jet structures.

[0020] The above-mentioned film stretching production line and hot air jet structure of the oven unit are provided with a first hole group and a second hole group, the first hole group includes a plurality of first vents arranged in sequence along the width direction of the film, the second hole group includes a plurality of second vents arranged in sequence along the width direction of the film, and the first vents and the second vents are arranged in a staggered manner along the conveying direction of the film. In this way, the requirements for the degree of coverage of the film surface by the direct action of the hot air flow are met, and at the same time, on the one hand, the hot air of the static pressure box can be sprayed onto the surface of the film in the width direction of the film, so that each position of the film in the width direction is uniformly heated, the heating uniformity is high, and the stability is high; on the other hand, the hot air ejected outward by the first hole group and the second hole group is a discontinuous hot air jet beam in the width direction of the film, in other words, the intermittent hot air jet, that is, no wind curtain is formed, and they will not block each other in the conveying direction of the film, so that the hot air after heat exchange with the film can be smoothly discharged outward and refluxed to the inside of the hot air circulation mechanism, so as to carry out the next cycle, and the heat exchange efficiency is high. It can be seen that the hot air jet structure of the above-mentioned oven unit can fully reflect the ideal heat exchange state in terms of uniformity, stability and high efficiency of the film. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a structural diagram of a film stretching production line according to an embodiment of the present application.

[0022] Figure 2 This is a structural diagram of a hot air jet structure of an oven unit according to an embodiment of the present application.

[0023] Figure 3 for Figure 2 The two static pressure box groups in the hot air jet structure of the drying oven unit are distributed on the opposite sides of the film in the working state diagram.

[0024] Figure 4 for Figure 3 Enlarged structural diagram at A.

[0025] Figure 5 for Figure 3 The orthographic structural diagram of the static pressure box group on the film is shown.

[0026] 10. Film; 20. Hot air jet structure of oven unit; 21. Hot air circulation mechanism; 211. Fan; 212. Heater; 213. Return air duct; 214. Hot air distributor; 22. Static pressure box group; 221. Static pressure box; 2211. Working surface; 2212. First hole group; 22121. First ventilation hole; 2213. Second hole group; 22131. Second ventilation hole; 2214. Third hole group; 22141. Third ventilation hole; 2215. First slit airflow nozzle; 2216. Guide plate; 2217. Upstream side plate; 2218. Transition plate; 2219. Second slit airflow nozzle; 23. Inlet; 31. Preheating section; 32. Stretching section; 33. Heat setting section; 34. Cooling section; 35. Heating zone; 36. Buffer zone. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0028] It should be noted that the longitudinal direction in this embodiment refers to the conveying direction of the film, that is, the length direction of the film. Figure 1 or Figure 5 As shown by the x arrow in the figure; the transverse direction refers to the width direction of the film, which is perpendicular to the longitudinal direction, such as Figure 1 or Figure 5 As shown by the y arrow in .

[0029] As described in the background technology, the hot air jet generated by the static pressure box configured in the hot air jet structure of the oven unit of the film stretching production line in the related art cannot fully reflect the ideal heat exchange state of the film in terms of uniformity, stability and high efficiency. The inventors have found that based on the existing technology, whether it is a nozzle in the form of a slit or a nozzle in the form of a multi-hole group, both have obvious advantages and disadvantages:

[0030] The slit-shaped nozzles used in the related art can produce hot air jets that are continuous, stable and uniform in the transverse direction of the film, and can achieve a wind curtain-like jet. The barrier characteristics of the wind curtain-like jet can effectively control the mutual interference of hot air in the longitudinal direction between adjacent plenums. However, if each plenum is provided with at least two slit-shaped nozzles, the hot air produced by the two adjacent slit-shaped nozzles cannot quickly flow back in the channel between the two plenums due to the wind curtain effect, which seriously affects the thermal cycle efficiency and the stability of the jet; if each plenum is provided with only a single slit-shaped nozzle, the film will be too low in the longitudinal direction due to the airflow layout density, and the film surface will not be directly covered by the hot airflow, resulting in poor stability of heat exchange in the oven, thereby affecting product quality, especially when the production line runs at a relatively low speed.

[0031] In addition, the hot air jets of the porous group nozzles in the related art can be arranged on the entire working surface of the static pressure box, which has an advantage in the longitudinal airflow layout range. The return air after heat exchange with the film can enter the return channel between the two static pressure boxes from the jet beam, which can ensure the heat cycle efficiency. However, the airflow distribution of the cross-section of the porous group hot air jet has the characteristics of high concentration in the center area and relatively weakened near the circumferential area. At the same time, if the film is fully and finely divided into several equal parts in the horizontal direction, it can be found that the geometric width of each circular hole-shaped hot air jet corresponding to each equal part of the film has a great difference in its projected area. The closer to the center point of the circular hole, the larger the longitudinal projected area obtained, and there are cases where some of the finely divided films are located in each circular hole-shaped hot air jet projection that cannot be covered. The above-mentioned porous group nozzles cannot achieve high consistency of the film in the horizontal direction by heat exchange with the film through the hot air jet, and also lack the wind curtain effect to suppress the mutual interference of hot air in the vertical direction between adjacent static pressure boxes.

[0032] In summary, the hot air jet of the static pressure box in the related art cannot meet the ideal heat exchange state of the film in terms of uniformity, stability and high efficiency generated by the hot air jet generated by the static pressure box configured in the hot air jet structure of the oven unit of the film stretching production line.

[0033] Based on the above reasons, the present application provides a film stretching production line and a hot air jet structure of an oven unit, which can satisfy the requirements of the film in terms of uniformity, stability and high efficiency and fully reflect the ideal heat exchange state.

[0034] See also Figure 1 , Figure 1The structure diagram of a film stretching production line in one embodiment of the present application is shown. A film stretching production line provided in one embodiment of the present application includes a plurality of oven unit hot air jet structures 20 arranged in sequence along the conveying direction of the film 10. The plurality of oven unit hot air jet structures 20 construct preheating sections 31, stretching sections 32, heat setting sections 33 and cooling sections 34 of different lengths to meet the stretching process requirements of different films 10.

[0035] The preheating section 31, the stretching section 32, the heat setting section 33 and the cooling section 34 are arranged along the conveying direction of the film 10. Optionally, a heating zone 35 may be provided between the stretching section 32 and the heat setting section 33, and a buffer zone 36 may be provided between the heat setting section 33 and the cooling section 34.

[0036] When the hot air jet structure 20 of the oven unit is working, it will provide a thermal environment with a precise temperature for the film 10 according to the stretching process parameters and the temperature requirements of the film 10; at the same time, fresh air is injected into the internal space and the waste gas released by the film 10 is extracted to improve the processing quality of the film 10.

[0037] See also Figure 2 and Figure 3 In one embodiment of the present application, a hot air jet structure 20 for an oven unit is provided. The hot air jet structure 20 for an oven unit includes a hot air circulation mechanism 21 and two static pressure box groups 22. The hot air circulation mechanism 21 is connected to the two static pressure box groups 22, and the hot air circulation mechanism 21 can provide hot air or cold air to each static pressure box group 22. This embodiment is specifically described by taking the static pressure box group 22 providing hot air as an example, but is not limited thereto.

[0038] See also Figure 3 , the two static pressure box groups 22 are respectively arranged on the opposite sides of the film 10 to be processed. Optionally, the two static pressure box groups 22 are symmetrically distributed on the upper and lower sides of the film 10. In this way, the airflow pressures of the two static pressure box groups 22 spraying to the upper and lower sides of the film 10 are balanced and consistent, which can improve the processing quality of the film 10. The static pressure box group 22 includes a static pressure box 221, and the static pressure box 221 is set as a working surface 2211 facing the side of the film 10. Optionally, the working surface 2211 includes but is not limited to being set as any one or more arbitrary combinations of a plane, a curved surface and an inclined surface. It can be flexibly adjusted and set according to actual needs, and is not limited here. In this embodiment, the working surface 2211 is specifically set to be a plane as an example, but it is not limited to this.

[0039] See also Figure 3 and Figure 5The working surface 2211 is provided with a first hole group 2212 and a second hole group 2213 arranged in sequence along the conveying direction of the film 10. The first hole group 2212 includes a plurality of first ventilation holes 22121 arranged in sequence along the width direction of the film 10, and the second hole group 2213 includes a plurality of second ventilation holes 22131 arranged in sequence along the width direction of the film 10. The first ventilation holes 22121 and the second ventilation holes 22131 are staggered in the conveying direction of the film 10.

[0040] It should be noted that the staggered arrangement in this embodiment means that, along the conveying direction, the center of the first ventilation hole 22121 is not aligned with the center of the second ventilation hole 22131. Specifically, along the conveying direction, one first ventilation hole 22121 is arranged opposite to the interval area between two adjacent second ventilation holes 22131, and one second ventilation hole 22131 is arranged opposite to the interval area between two adjacent first ventilation holes 22121.

[0041] The first ventilation hole 22121 and the second ventilation hole 22131 are each configured as an elongated hole extending along the width direction of the film 10. The length dimension of the elongated hole is more than 1.5 times the width dimension of the elongated hole.

[0042] Optionally, the length of the first ventilation hole 22121 along the width direction of the film 10 is the same as the length of the interval area between two adjacent second ventilation holes 22131 along the width direction of the film 10. In other words, along the conveying direction of the film 10, the first ventilation hole 22121 is complementary to the interval area between two adjacent second ventilation holes 22131. Similarly, the length of the second ventilation hole 22131 along the width direction of the film 10 is the same as the length of the interval area between two adjacent first ventilation holes 22121 along the width direction of the film 10. In other words, along the conveying direction of the film 10, the second ventilation hole 22131 is complementary to the interval area between two adjacent first ventilation holes 22121.

[0043] The lengths of the first ventilation hole 22121 and the second ventilation hole 22131 can be the same or different, and can be flexibly adjusted and set according to actual needs, which is not limited here.

[0044] Of course, as some optional solutions, the first ventilation hole 22121 and the second ventilation hole 22131 may also partially overlap along the conveying direction of the film 10. Optionally, the length of the overlapping area of ​​the first ventilation hole 22121 and the second ventilation hole 22131 along the width direction of the film 10 is, for example, 1% to 10% of the length of the first ventilation hole 22121 along the width direction of the film 10.

[0045] The above-mentioned hot air jet structure 20 of the oven unit is provided with a first hole group 2212 and a second hole group 2213. The first hole group 2212 includes a plurality of first ventilation holes 22121 arranged in sequence and spaced apart along the width direction of the film 10, and the second hole group 2213 includes a plurality of second ventilation holes 22131 arranged in sequence and spaced apart along the width direction of the film 10. The first ventilation holes 22121 and the second ventilation holes 22131 are staggered in the conveying direction of the film 10. In this way, the requirement of the degree of coverage of the surface of the film 10 directly affected by the hot air flow is met. At the same time, on the one hand, the hot air of the static pressure box 221 can be sprayed onto the surface of the film 10 along the width direction of the film 10, so that the film 10 can be evenly heated at various positions along the width direction, with high heating uniformity and high stability; on the other hand, the hot air sprayed outward by the first hole group 2212 and the second hole group 2213 is a discontinuous hot air jet beam along the width direction of the film 10, in other words, the intermittent hot air jet, that is, no wind curtain is formed, and they will not block each other in the conveying direction of the film 10, so that the hot air after heat exchange with the film 10 can be easily discharged outward smoothly and refluxed to the inside of the hot air circulation mechanism 21, so as to carry out the next cycle, and the heat exchange efficiency is high. It can be seen that the above-mentioned hot air jet structure 20 of the oven unit can fully reflect the ideal heat exchange state of the film 10 in terms of uniformity, stability and high efficiency.

[0046] In some embodiments, the first through hole and the second through hole are independently set, for example, as elongated holes, and the elongated holes are extended along the width direction of the film 10. The elongated holes are, for example, waist-shaped holes or strip-shaped holes, etc. Among them, the ratio of the length to the width of the elongated holes is, for example, greater than 5, or even greater than 10, and can be flexibly adjusted and set according to actual needs.

[0047] Optionally, the length and width of each first through hole are the same; all the first through holes are evenly arranged along the width direction of the film 10. In addition, the length and width of each second through hole are the same; all the second through holes are evenly arranged along the width direction of the film 10. In this way, the heating uniformity of each position on the surface of the film 10 can be better, thereby improving the treatment quality.

[0048] It should be noted that the "same" in this embodiment is not strictly "same" in a mathematical sense, but allows for a process deviation within ±10%, for example. Specifically, as an example, the average length of the first through holes is used as a reference to compare with the actual length of each first through hole. When the deviation between the actual length of each first through hole and the average length is within ±10%, the lengths of each first through hole are defined as the same.

[0049] In addition, the "uniform arrangement" in this embodiment is not a strict "uniform arrangement" in the mathematical sense, but allows for a process deviation within ±10%, for example. Specifically, as an example, the average center spacing of two adjacent first through holes is calculated based on the number of first through holes and the spacing between the first and last first through holes in the lateral direction, and the average center spacing is used as a reference to compare with the actual center spacing of each adjacent two first through holes. When the deviation between the actual center spacing of each adjacent two first through holes and the average center spacing is within ±10%, it is defined that each first through hole is uniformly arranged in the lateral direction.

[0050] In addition, the first hole group 2212 and the second hole group 2213 specifically spray hot air onto the side of the film 10 in a manner perpendicular to the side of the film 10. Driven by the surface airflow generated when the film 10 is running, the corresponding hot air jet will flow from the working surface 2211 area of ​​the static pressure box 221 to the downstream in an orderly manner after interacting with the surface of the film 10, and flow out from the return channel between the two adjacent static pressure boxes 221 on the downstream side. This is conducive to the high efficiency of heat exchange.

[0051] See also Figures 3 to 5 In one embodiment, the working surface 2211 is further provided with a first slot airflow nozzle 2215 extending along the width direction of the film 10. Each static pressure box 221 has only one first slot airflow nozzle 2215. Along the conveying direction of the film 10, the first slot airflow nozzle 2215 is located upstream of the first hole group 2212. The air outlet direction of the first slot airflow nozzle 2215 is inclined toward the inlet 23 of the hot air jet structure 20 of the oven unit. In this way, the first slot airflow nozzle 2215 can form a single row of continuous hot air jets to act laterally on the surface of the film 10, meeting the requirement that the film 10 has stable and uniform heat exchange along the width. In addition, the running film 10 will drive a certain amount of surface air to flow downstream together, and the hot air ejected from the first slot airflow nozzle 2215 can form a wind curtain, which plays a good barrier role and can effectively control the mutual interference of hot air between adjacent static pressure boxes 221 in the longitudinal direction. In addition, waste generated during the heating process of the film 10 can be prevented from flowing between adjacent static pressure boxes 221, and a temperature difference can be formed between adjacent static pressure boxes 221.

[0052] Optionally, the first slot airflow nozzle 2215 can be a single through air outlet slot extending from one side of the working surface 2211 to the other side along the width direction of the film 10. Specifically, the length of the air outlet slot is greater than the width of the film 10, and for example, spans the film 10 along the width direction of the film 10.

[0053] In addition, the first slit airflow nozzle 2215 can be a plurality of segmented air outlets arranged in sequence along the width direction of the film 10. By adjusting the arrangement density of the segmented air outlets, when the hot air jets discharged from each segmented air outlet act on the surface of the film 10, they are continuous hot air along the width direction of the film 10, that is, they are slit airflows. Optionally, the sum of the lengths of each segmented air outlet along the width direction of the film 10 is set as L1, and the distance between the first segmented air outlet and the last segmented air outlet is set as L2, 0.8≤L1 / L2<1.

[0054] In one embodiment, the angle formed by the outlet direction of the first slit airflow nozzle 2215 and the conveying direction of the film 10 is a, and a includes but is not limited to 10°~80°. Optionally, a is, for example, 10°, 30°, 45°, 60°, 75° or 80°, and can be flexibly adjusted and set according to actual needs. In this way, the action position of the hot air ejected outward by the first slit airflow nozzle 2215 on the film 10 is moved forward, widening the action range of the static pressure box 221 on the film 10; at the same time, it is convenient for the hot air jet to directly flow out from the reflux channel between the static pressure boxes 221 on the upstream side after acting on the surface of the film 10, further enhancing the effect of barrier and efficient heat exchange.

[0055] When a is adjusted, the position where the hot air ejected from the first slot airflow nozzle 2215 contacts the surface of the film 10 can be adjusted accordingly. In this embodiment, the geometric intersection position of the center line K of the first slot airflow nozzle 2215 ejecting hot air outward and the surface of the film 10 is set to the area outside the projection contour of the static pressure box 221 on the surface of the film 10. Preferably, the geometric intersection position of the center line K and the surface of the film 10 is equal to the spacing between the two adjacent static pressure boxes 221. In this way, the reflow efficiency of the hot air jet is high.

[0056] See also Figure 3 and Figure 4 In one embodiment, guide plates 2216 are provided on opposite sides of the first slot airflow nozzle 2215. The guide plates 2216 are located inside the static pressure box 221, and the two guide plates 2216 are arranged relatively spaced apart and cooperate to form a guide channel. The guide channel is connected to the first slot airflow nozzle 2215. In this way, the hot air inside the static pressure box 221 is first guided through the guide channel, and then ejected outward through the first slot airflow nozzle 2215, so that the size of a can be controlled more accurately.

[0057] In one embodiment, the static pressure box 221 also includes an upstream side plate 2217 and a transition plate 2218 connected between the upstream side plate 2217 and the working surface 2211. Optionally, the transition plate 2218 includes but is not limited to an inclined plate or an arc-shaped plate. The first slot airflow nozzle 2215 is formed at the intersection of the transition plate 2218 and the working surface 2211 or is formed on the transition plate 2218. In this way, the first slot airflow nozzle 2215 is located at the upstream portion of the working surface 2211, which can completely isolate the upstream turbulence outside the area of ​​the static pressure box 221, and also improve the return efficiency.

[0058] In some embodiments, a second slot airflow nozzle 2219 is disposed on the surface of the static pressure box 221 disposed at the intersection of the hot air jet structures 20 of two adjacent oven units facing away from the film 10. Optionally, the structure of the second slot airflow nozzle 2219 is similar to the first slot airflow nozzle 2215, which will not be described in detail here. In this way, the hot air jet generated by the second slot airflow nozzle 2219 is arranged along the width direction of the film 10, which can form a wind curtain effect to prevent hot air from flowing inside the hot air jet structures 20 of adjacent oven units.

[0059] Especially in occasions where it is necessary, such as at each intersection position in the preheating section 31, stretching section 32, heat setting section 33 and cooling section 34 of the oven, the process temperature difference between two adjacent oven unit hot air jet structures 20 is relatively large. The second slot airflow nozzle 2219 can suppress the hot air longitudinal crossflow in the inner space of the oven unit hot air jet structure 20 with a large process temperature difference, thereby improving the process temperature accuracy of each oven unit hot air jet structure 20.

[0060] In a specific embodiment, the static pressure box group 22 is provided with at least two static pressure boxes 221. At least two static pressure boxes 221 are arranged in sequence and spaced apart along the conveying direction of the film 10, and the first and last static pressure boxes 221 along the conveying direction are provided with second slit airflow nozzles 2219 on the side facing away from the film 10, and the second slit airflow nozzles 2219 are extended along the width direction of the film 10. In this way, the first and last static pressure boxes 221 are arranged at the intersection of the hot air jet structures 20 of two adjacent oven units, and because the second slit airflow nozzles 2219 are provided on the side facing away from the film 10, a wind curtain effect can be formed to prevent hot air from flowing inside the hot air jet structures 20 of adjacent oven units.

[0061] The air outlet direction of the second slit airflow nozzle 2219 may be either perpendicular to the side surface of the film 10 or inclined relative to the side surface of the film 10, which is not limited here.

[0062] In a specific embodiment, when the first slit air nozzle 2215, the first hole group 2212 and the second hole group 2213 are simultaneously provided on the working surface 2211 along the conveying direction of the film 10, the continuous hot air ejected from the first slit air nozzle 2215 can act on the side surface of the film 10 along the width direction of the film 10, having high thermal uniformity and serving as a wind curtain barrier; the hot air ejected from the first hole group 2212 and the second hole group 2213 respectively is intermittent hot air along the width direction of the film 10, which can also act transversely on the surface of the film 10 and can satisfy the hot air jet with a large distribution amplitude in the longitudinal direction of the film 10, so that the heat exchange effect is better.

[0063] On the basis of the foregoing embodiment, a third hole group 2214 is further provided on the working surface 2211. The third hole group 2214 is located between the first slit air nozzle 2215 and the first hole group 2212. The third hole group 2214 includes a plurality of third ventilation holes 22141 arranged at intervals in sequence along the width direction of the film 10. Along the conveying direction of the film 10, a plurality of adjacent positions are formed between each first ventilation hole 22121 and each second ventilation hole 22131, and the plurality of third ventilation holes 22141 are arranged in one-to-one correspondence with the plurality of adjacent positions.

[0064] In a specific embodiment, the first hole group 2212, the second hole group 2213 and the third hole group 2214 are all hole-shaped nozzles, that is, a total of three rows of hole-shaped nozzles are provided. Among them, the sum of the lengths of all the first ventilation holes 22121 of the first hole group 2212 along the width direction of the film 10 is set as S1, the sum of the lengths of all the second ventilation holes 22131 of the second hole group 2213 along the width direction of the film 10 is set as S2, and the sum of the lengths of all the third ventilation holes 22141 of the third hole group 2214 along the width direction of the film 10 is set as S3, 5% < S3 / S2 ≤ 20%, 5% < S3 / S1 ≤ 20%. In addition, 80% < S2 / S1 ≤ 120%, and S2 / S1 is specifically, for example, 80%, 85%, 90%, 100%, 105%, 110%, 115% or 120%, etc. The hot air ejected from the third hole group 2214 plays a supplementary role. Although it is located relatively upstream, the hot air flow rate is small and has little influence on the return air efficiency. With such an arrangement, the advantages of stable and uniform heat exchange of the first slit air nozzle 2215 for the film 10 along the wide width are retained, and at the same time, the problem that the density of the air flow layout in the longitudinal direction of the film 10 is too low and the coverage degree of the surface of the film 10 directly affected by the hot air flow is insufficient is solved, and the side effect brought by the wind curtain effect on the hot air return is avoided. In addition, the first hole group 2212 and the second hole group 2213 are located in the middle and lower reaches of the working surface 2211, which is conducive to hot air return.

[0065] In addition, the length of the interval area between two adjacent first ventilation holes 22121 along the width direction of the film 10 is set to S4, and the length of the first ventilation hole 22121 along the width direction of the film 10 is set to S5. <S4 / S5≤115%。

[0066] In addition, 80%≤S1+S2 / L2<1. Thus, S1+S2 is relatively large, and the film 10 has a better heating effect along its width direction.

[0067] In a specific embodiment, the first ventilation holes 22121 are elongated holes whose lengths extend along the width direction of the film 10, and the lengths of the first ventilation holes 22121 are equal, and the first ventilation holes 22121 are evenly arranged along the width direction of the film 10. The second ventilation holes 22131 are elongated holes whose lengths extend along the width direction of the film 10, and the lengths of the second ventilation holes 22131 are equal, and the second ventilation holes 22131 are evenly arranged along the width direction of the film 10. The third ventilation holes 22141 are elongated holes whose lengths extend along the width direction of the film 10, and the lengths of the third ventilation holes 22141 are equal, and the third ventilation holes 22141 are evenly arranged along the width direction of the film 10.

[0068] In some embodiments, the hot air circulation mechanism 21 includes a fan 211, a heater 212, a return air duct 213 and a hot air distributor 214. The fan 211 is connected to the hot air distributor 214, the return air port of the hot air distributor 214 is connected to the return air duct 213, and the air outlet of the hot air distributor 214 is connected to the static pressure box group 22. The heater 212 is, for example, arranged on the return air duct 213. When the fan 211 is working, the return air duct 213 generates a negative pressure, which can reflux the hot air in the environment of the film 10; the hot air refluxes into the hot air distributor 214 through the return air duct 213. The heater 212 is used to heat the gas that flows back into the return air duct 213, so that the gas entering the hot air distributor 214 reaches a precise process temperature. After the hot air flows back into the hot air distributor 214, it is transported to each static pressure box group 22 through the hot air distributor 214, and forms a hot air jet through the nozzle on the working surface 2211 of the static pressure box 221 to act on the two opposite sides of the film 10, so as to heat the film 10, thereby completing the process of preheating, stretching, heat setting and cooling along the line. After the hot air jet completes the heat exchange with the surface of the film 10, it flows back in the channel space between two horizontally adjacent static pressure boxes 221, and is absorbed by the process hot air internal circulation system respectively, and then generates the next cycle.

[0069] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0070] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0071] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0072] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0073] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0074] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0075] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A hot air jet structure of an oven unit, characterized in that: The hot air jet structure of the oven unit comprises: Hot air circulation mechanism; and Two static pressure box groups, the hot air circulation mechanism is connected to the two static pressure box groups, and the hot air circulation mechanism can provide hot air or cold air for the static pressure box groups; the two static pressure box groups are respectively arranged on opposite sides of the film to be processed, the static pressure box group includes a static pressure box, the side of the static pressure box facing the film is set as a working surface, and the working surface is provided with a first hole group and a second hole group arranged in sequence along the conveying direction of the film, the first hole group includes a plurality of first ventilation holes arranged in sequence at intervals along the width direction of the film, the second hole group includes a plurality of second ventilation holes arranged in sequence at intervals along the width direction of the film, the first ventilation holes and the second ventilation holes are staggered in the conveying direction of the film; and the first ventilation holes and the second ventilation holes are each set as an elongated hole extending in the width direction of the film, the length dimension of the elongated hole is 1.5 of the width dimension of the elongated hole times; a first slit airflow nozzle extending along the width direction of the film is also provided on the working surface, and each of the static pressure boxes has only one first slit airflow nozzle; along the conveying direction of the film, the first slit airflow nozzle is located upstream of the first hole group; the air outlet direction of the first slit airflow nozzle is inclined toward the inlet of the hot air jet structure of the oven unit.

2. The hot air jet structure of the oven unit according to claim 1, characterized in that: The angle formed by the air outlet direction of the first slit airflow nozzle and the conveying direction of the film is a, and a is 10° to 80°.

3. The hot air jet structure of the oven unit according to claim 1 or 2, characterized in that: Guide plates are provided on opposite sides of the first slot airflow nozzle. The guide plates are located inside the static pressure box. The two guide plates are relatively spaced apart and cooperate to form a guide channel. The guide channel is connected to the first slot airflow nozzle.

4. The hot air jet structure of the oven unit according to claim 1, characterized in that: The static pressure box also includes an upstream side plate and a transition plate connected between the upstream side plate and the working surface; the first slot airflow nozzle is formed at the intersection of the transition plate and the working surface or on the transition plate.

5. The hot air jet structure of the oven unit according to claim 1, characterized in that: The static pressure box group is provided with at least two static pressure boxes, and at least two of the static pressure boxes are arranged in sequence at intervals along the conveying direction of the film. The first and last two static pressure boxes along the conveying direction are provided with second slit airflow nozzles on the sides facing away from the film, and the second slit airflow nozzles are extended along the width direction of the film.

6. The hot air jet structure of the oven unit according to claim 1, characterized in that: The geometric intersection position of the center line of the first slot airflow nozzle that sprays hot air outwards and the film surface is located outside the projection contour of the static pressure box on the film surface.

7. The hot air jet structure of the oven unit according to claim 1, characterized in that: A third hole group is also provided on the working surface, and the third hole group is located between the first slit airflow nozzle and the first hole assembly. The third hole group includes a plurality of third ventilation holes arranged in sequence and spaced apart along the width direction of the film; along the conveying direction of the film, each of the first ventilation holes and each of the second ventilation holes forms a plurality of adjacent positions, and the plurality of third ventilation holes are arranged in one-to-one correspondence with the plurality of adjacent positions.

8. The hot air jet structure of the oven unit according to claim 1, characterized in that: The first ventilation holes have the same length and are evenly arranged along the width direction of the film; the second ventilation holes have the same length and are evenly arranged along the width direction of the film.

9. The hot air jet structure of the oven unit according to claim 7, characterized in that: The sum of the lengths of all the first ventilation holes in the first hole group along the width direction of the film is set to S1, the sum of the lengths of all the second ventilation holes in the second hole group along the width direction of the film is set to S2, and the sum of the lengths of all the third ventilation holes in the third hole group along the width direction of the film is set to S3; 5% <S3 / S2≤20%,5%<S3 / S1≤20%,80%<S2 / S1≤120%; The length of the interval area between two adjacent first ventilation holes along the width direction of the film is set to S4, and the length of the first ventilation hole along the width direction of the film is set to S5. <S4 / S5≤115%。 10. A film stretching production line, characterized in that: The film stretching production line comprises a plurality of hot air jet structures of the drying oven units as described in any one of claims 1 to 9.

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