Static pressure box and film stretching equipment

Abstract

The present disclosure provides a static pressure box and a film stretching device for blowing air toward the surface of a film, the static pressure box including a box body extending along an axial direction parallel to the surface of the film; a transverse partition provided in the box body and dividing the box body into a first box body and a second box body along the axial direction, an array of air inlets for connecting the first box body and the second box body is formed on the transverse partition; an air inlet provided at one end of the first box body in the axial direction; an air outlet provided on the side of the second box body facing the surface of the film and arranged along the axial direction; a vertical partition forming a drainage chamber in the first box body and a flow balancing chamber in the second box body. According to the present disclosure, the airflow is introduced into the flow balancing chamber through the drainage chamber, and after axial flow balancing in the flow balancing chamber, the air is discharged toward the surface of the film through the air outlet, ensuring that the airflow blown out from the air outlet has a uniform wind speed and a stable direction along the axial direction of the static pressure box.

Description

Technical Field

[0001] The present application relates to the field of film material processing, and in particular to a static pressure box and film stretching equipment. Background Art

[0002] In the film stretching process, a hot air flow or a cold air flow is blown toward one side or both sides of the film through a static pressure box to provide uniform heat for the film. However, in the static pressure box of the prior art, after the air flow enters the static pressure box from the air inlet, it flows directly to the vicinity of the air outlet and is blown out from the air outlet. Since the axial extension size of the static pressure box is large, the axial flow velocity and outflow direction of the air flow blown out from the air outlet are uneven and unstable. The cavity space of a large static pressure box is large, which can still solve this problem to a certain extent, but for a small static pressure box, the air flow velocity, outflow direction uniformity and stability need to be improved. Summary of the Invention

[0003] The present application provides a static pressure box and film stretching equipment.

[0004] Specifically, this application is implemented through the following technical solutions:

[0005] In a first aspect, an embodiment of the present application provides a static pressure box for blowing air toward a film surface, comprising:

[0006] a box body extending along an axial direction parallel to the surface of the film;

[0007] a transverse partition, disposed in the box body and separating the box body into a first box body and a second box body along the axial direction, wherein an array of air vents for connecting the first box body and the second box body are formed on the transverse partition;

[0008] An air inlet is provided at one end of the first box body in the axial direction;

[0009] an air outlet, provided on the side of the second box body facing the surface of the film and arranged along the axial direction;

[0010] A vertical partition forms a drainage cavity in the first box body and a flow equalization cavity in the second box body;

[0011] In which, the drainage cavity faces the flow equalizing cavity, and the flow equalizing cavity and the air outlet are partially separated by the vertical partition along the axial direction, so that the air flow is introduced into the flow equalizing cavity through the drainage cavity, and after axial flow equalization in the flow equalizing cavity, the air is discharged toward the surface of the film through the air outlet.

[0012] In some embodiments, the vertical partition includes a pair of first vertical partitions, which extend from the transverse partition toward the first box body and are arranged on both sides of the first box body along the axial direction, thereby forming a pair of drainage cavities extending along the axial direction together with the side walls of the first box body.

[0013] In some embodiments, a connecting transverse plate is provided between the pair of first vertical partitions, and the connecting transverse plate is connected to the transverse partitions and covers and closes the air outlet located outside the drainage cavity.

[0014] In some embodiments, the vertical partition includes a pair of second vertical partitions, which extend from the second box body near the air outlet side wall toward the second box body and are opposite to the drainage cavity, thereby forming a pair of flow equalization cavities extending along the axial direction together with the second box body side wall.

[0015] In some embodiments, the second box side wall of the flow equalizing chamber includes a vertical side wall, an inclined side wall and a horizontal side wall, and the vertical side wall and the horizontal side wall are connected through the inclined side wall.

[0016] In some embodiments, the air vents are arranged on the transverse partition in an array with variable spacing along the axial direction.

[0017] In some embodiments, the transverse partition is bent toward the second box body to form the air outlet.

[0018] In some embodiments, a pair of third vertical partitions are further included, and the third vertical partitions extend from the air outlet toward the second box body, thereby forming a slit connected to the air outlet between the pair of third vertical partitions, wherein a flow storage cavity is formed between the second vertical partition and the third vertical partition.

[0019] In some embodiments, the pair of third vertical partitions are away from the air outlet side and are respectively provided with a bent portion toward the second vertical partition, and the second vertical partition, the third vertical partition and the bent portion together surround and form the flow storage cavity.

[0020] In a second aspect, an embodiment of the present application provides a film stretching device, comprising:

[0021] Film conveying mechanism;

[0022] a pair of static pressure boxes as described in the first aspect, arranged on both sides of the film, the air outlets of the pair of static pressure boxes facing the two side surfaces of the film respectively;

[0023] Wherein, the axial direction of the static pressure box is perpendicular to the film conveying direction.

[0024] According to various embodiments of the present disclosure, a transverse partition is provided to separate the box body into a first box body and a second box body that are independent of each other, and a vertical partition is provided to form a drainage chamber in the first box body, and a flow equalization chamber in the second box body. The air flow flows into the first box body from the air inlet, and first undergoes the first axial flow equalization in the drainage chamber. The air flow is then directed into the flow equalization chamber in the second box body through the air holes of the transverse partition through the drainage chamber. After the second axial flow equalization is performed in the flow equalization chamber, the air flow is blown from the air outlet to the surface of the film, thereby ensuring that the air flow blown out from the air outlet has a uniform and stable axial flow velocity and direction along the static pressure box.

[0025] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0027] Figure 1 is a schematic diagram of a static pressure box in one embodiment of the present disclosure;

[0028] Figure 2 is a schematic diagram of a static pressure box explosion in one embodiment of the present disclosure;

[0029] Figure 3 is a schematic axial cross-sectional view of a static pressure box in one embodiment of the present disclosure;

[0030] Figure 4 is a schematic cross-sectional view of a static pressure box in one embodiment of the present disclosure;

[0031] Figure 5 is a schematic diagram of a diaphragm in one embodiment of the present disclosure;

[0032] Figure 6 is a schematic diagram of a diaphragm in another embodiment of the present disclosure;

[0033] Figure 7 Schematic diagram of simulated distribution of axial air flow velocity of the static pressure box in one embodiment of the present disclosure;

[0034] Figure 8 This is a schematic diagram of the simulated distribution of the axial air flow direction of the static pressure box in one embodiment of the present disclosure;

[0035] Figure 9 It is a schematic diagram of the simulation verification of the airflow direction of the static pressure box in one embodiment of the present disclosure.

[0036] Reference numerals:

[0037] 10: first box; 20: second box;

[0038] 30: diaphragm;

[0039] 41: first vertical partition; 411: connecting horizontal plate; 42: second vertical partition; 43: third vertical partition;

[0040] 50: air inlet; 60: air outlet; 61: inner bend; 70: air outlet;

[0041] 81: bending part;

[0042] 91: drainage cavity; 92: flow distribution cavity; 921: vertical side wall; 922: horizontal side wall; 923: oblique side wall; 93: flow storage cavity. DETAILED DESCRIPTION

[0043] The present disclosure will now be discussed with reference to several embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and thus implement the present disclosure, rather than implying any limitation on the scope of the present disclosure.

[0044] As used herein, the term "including" and its variations are to be interpreted as open-ended terms meaning "including but not limited to." The term "based on" is to be interpreted as "based, at least in part, on." The terms "embodiment" and "one embodiment" are to be interpreted as "at least one embodiment." The term "another embodiment" is to be interpreted as "at least one other embodiment." The terms "first," "second," etc. may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0045] In the following description, some specific numerical values ​​or numerical ranges may be involved. It should be understood that these numerical values ​​and numerical ranges are merely exemplary, which may be helpful in putting the ideas of the present disclosure into practice. However, the description of these examples is not intended to limit the scope of the present disclosure in any way. Depending on specific application scenarios and needs, these numerical values ​​or numerical ranges can be set separately.

[0046] The static pressure box and film stretching equipment proposed in the embodiments of the present disclosure at least partially solve the above problems. Figures 1 to 9 To describe the static pressure box structure, working principle and simulation verification according to the exemplary embodiment of the present disclosure. First, refer to Figure 1-6 , which shows an exemplary structure of a plenum according to an exemplary embodiment of the present disclosure. The plenum of the present disclosure is suitable for blowing air onto the surface of a film. For example, in the manufacturing process of a biaxially oriented film, two sets of plenums are arranged opposite each other on the two sides of the film. The plenums evenly blow air at the corresponding process temperature onto both sides of the film during different steps of the film stretching process.

[0047] During this process, it is crucial that the airflow velocity and direction blown from the static pressure box to the film surface are uniform and stable. For example, the airflow velocity distribution along the axial direction of the airflow blown out from the air outlet 70 is inconsistent, the airflow direction distribution is inconsistent, the angle between the airflow direction and the film surface is too large, and the airflow velocity or direction fluctuates over a period of time. These problems all need to be improved.

[0048] like Figure 1-5 As shown, in general, the static pressure box described herein includes a box body and a partition structure inside the box body. The box body is in the shape of a long strip extending with a fixed cross-section. The box body is provided with an air inlet 50 at one end of the long strip, and an air outlet 70 is provided along the extension direction. After the air flow enters the box body through the air inlet 50, it flows to the other end of the box body along the extension direction, so that the air flow is filled between the two ends of the box body in the extension direction, and the air flow is blown out from the air outlet 70 through the pressure formed in the box body. In this process, since the air flow flows from one end of the box body to the other end, the pressure formed in the box body is unevenly distributed along the extension direction, and the direction of the air flow also points to a certain extent in the direction away from one end of the air inlet 50. These conditions all need to be overcome.

[0049] In order to clearly describe the embodiments of the present disclosure, the orientation of the static pressure box of the present disclosure is defined, wherein the elongated extension direction of the box body is defined as the axial direction, the surface perpendicular to the axial direction is defined as the cross section, the air outlet direction of the box body air outlet 70 in the cross section is defined as the vertical direction, and the direction perpendicular to the vertical direction in the cross section is defined as the horizontal direction.

[0050] In one embodiment, a transverse partition 30 is provided in the box, and the lateral sides of the transverse partition 30 are respectively connected to the two side walls of the box, thereby dividing the box into a vertically stacked first box 10 and a second box 20. The first box 10 and the second box 20 form an independent space, and the air inlet 50 is provided at one axial end of the first box 10, and the air outlet 70 is provided on the side of the second box 20 facing the film surface. The air flow first flows into the first box 10 through the air inlet 50, and after forming the desired flow state in the first box 10, it flows into the second box 20.

[0051] In one embodiment, the air outlets 70 can be arranged in an axial array on the side of the second box facing the film surface, so that multiple air outlets 70 are arranged in intervals in the axial direction; or they can be arranged in an axially continuous extension on the side of the second box facing the film surface, so that only one air outlet 70 is arranged in the axial direction.

[0052] In one embodiment, an array of air vents 60 are formed on the transverse partition 30 for connecting the first box body 10 with the second box body 20. The air vents 60 can be long strip holes extending in the transverse direction, and multiple long strip holes are arranged in an axially spaced array; the air vents 60 can also be square or circular holes, and multiple directional or circular holes are arranged in a transversely and axially spaced array.

[0053] In one embodiment, Figure 5 As shown, the air vents 60 are arranged in an array with equal intervals along the axial direction to improve the processing performance of the diaphragm 30; in another embodiment, as shown Figure 6 As shown, the air vents 60 can be arranged in an array with gradually increasing spacing along the axial direction, that is, the spacing of the air vents 60 near one end of the air inlet 50 is the smallest, and the spacing of the air vents 60 far from the end of the air inlet 50 is the largest. When the opening area of ​​each air vent 60 is consistent, the air flow velocity between the two ends near and far from the air inlet 50 is distributed in a decreasing manner along the axial direction, so that the air flow pressure in the first box body 10 between the two ends is distributed in a decreasing manner along the axial direction. By gradually increasing the array spacing of the air vents 60, the area of ​​the air vents 60 between the two ends is distributed in a decreasing manner along the axial direction, thereby performing axial balanced compensation for the air flow velocity flowing into the second box body 20.

[0054] In another embodiment, the opening area of ​​each air outlet 60 may be set to be inconsistent. For example, the opening area of ​​the air outlet 60 may be directly set to decrease axially, thereby performing axial balance compensation on the flow rate of the air flow flowing into the second box body 20 .

[0055] In one embodiment, a first vertical partition 41 is provided in the box body, which can be a plate with a groove-shaped cross section, wherein the groove-shaped bottom plate is formed as a connecting transverse plate 411, and the groove-shaped two side plates are formed as a pair of first vertical partitions 41 extending toward the first box body 10, that is, the first vertical partition 41 is provided in the first box body 10, and the connecting transverse plate 411 is connected to the transverse partition 30, so that the connecting transverse plate 411 covers the part of the air outlet 60 located in the middle of the transverse portion of the transverse partition 30, and the pair of first vertical partitions 41 avoid the part of the air outlet 60 located on the transverse sides of the transverse portion of the transverse partition 30, so that the first box body 10 and the second box body 20 are connected. The space between the two boxes can only be connected through the partial air vents 60 on the transverse sides of the transverse partition 30 to achieve the drainage effect; at the same time, when the air flow flowing in from the air inlet 50 is in a vortex state, it will cause the air flow flowing into the second box body 20 to have a transverse airflow direction, thereby making the air flow pressure in the second box body 20 unevenly distributed in the transverse direction, and will also affect the axial distribution of the air flow pressure in the second box body 20. A pair of first vertical partitions 41 extending axially in the first box body 10 will cut and block the vortex, thereby reducing the influence of the vortex on the uniformity of the transverse distribution of the air flow in the second box body 20. It should be noted that the air flow flowing into the first box body 10 from the air inlet 50 can be in a laminar state (such as Figure 9 As shown), it can also be in a vortex state. If it is in a vortex state, this embodiment can solve the above problems very well.

[0056] In another embodiment, a pair of first vertical partitions 41 may also extend from the transverse partition 30 toward the second box body 20, that is, the first vertical partitions 41 are arranged in the second box body 20. In this case, the drainage chamber 91 is located in the second box body 20. Since the airflow flowing out of the first box body 10 directly contacts the first vertical partitions 41, it is further ensured that the airflow flows into the flow equalization chamber 92.

[0057] In another embodiment, the air vent 60 may be formed only on the transverse partition wall between the first vertical partition 41 and the vertical side panel of the first box body 10, and there may be no air vent 60 on the transverse partition 30 between a pair of first vertical partitions 41. There is no need to set a connecting transverse plate 411, so as to ensure that the first box body 10 and the second box body 20 are connected only through the transverse partition 30 at the drainage cavity 91.

[0058] In another embodiment, the diaphragm 30 forms an air vent 60 by bending inward 61, and the inward bend 61 may be toward the inside of the second box body 20 (eg Figure 5 As shown), the inner bend 61 can be located closer to the air inlet 50 end relative to the corresponding air outlet 60, so that the airflow flowing into the second box body 20 through the air outlet 60 tends to flow in the vertical direction due to the Coanda effect. The inner bend 61 can also be located farther away from the air inlet 50 end relative to the corresponding air outlet 60, so that the airflow flowing into the second box body 20 through the air outlet 60 is blocked in the axial direction by the inner bend 61, and the airflow can also tend to flow in the vertical direction under the blocking effect. In another embodiment, the inner bend 61 can also be directed toward the inside of the first box body, so that the airflow in the first box body 10 is more inclined to flow into the air outlet 60. The air outlet 60 is formed by the inner bend 61, which simplifies the molding process of the air outlet 60.

[0059] In one embodiment, a drainage chamber 91 is formed by the first vertical partition 41, the vertical side wall 921 of the first box body 10 and the transverse partition 30. The drainage chamber 91 extends axially. Since the drainage chamber 91 is partially connected to the second box body 20, the pressure in the drainage chamber 91 is lower than that in other areas of the first box body 10. The airflow flowing into the first box body 10 through the air inlet 50 tends to flow into the drainage chamber 91, is stored in the drainage chamber 91 and gradually forms a uniform flow velocity along the axial direction, thereby ensuring that the airflow flowing into the second box body 20 has a uniform flow velocity along the axial direction.

[0060] In one embodiment, a flow equalizing chamber 92 is formed by the second vertical partition 42, the vertical side wall 921 of the second box body 20 and the bottom side wall of the second box body 20. The air outlet 70 is located between a pair of second vertical partitions 42. The two flow equalizing chambers 92 and the air outlet 70 are separated by a pair of second vertical partitions 42, so that the flow equalizing chamber 92 and the drainage chamber 91 are positioned opposite to each other, ensuring that the airflow of the first box body 10 flows directly into the flow equalizing chamber 92 through the drainage chamber 91. Since the flow equalizing chamber 92 extends axially, the airflow is stored in the flow equalizing chamber 92 and gradually forms a uniform flow velocity along the axial direction, ensuring that the airflow flowing out of the flow equalizing chamber 92 again has a uniform flow velocity along the axial direction.

[0061] In one embodiment, the distance between the second vertical partition 42 and the vertical side wall 921 of the second box body 20 can be slightly larger than the distance between the first vertical partition 41 and the vertical side wall 921 of the first box body 10, that is, the opening of the flow balancing chamber 92 is slightly larger than the opening of the drainage chamber 91, thereby ensuring that the airflow flowing out of the drainage chamber 91 basically flows directly into the flow balancing chamber 92.

[0062] In one embodiment, an oblique side wall 923 is provided between the vertical side wall 921 and the horizontal side wall 922 of the second box body 20. After the airflow from the air outlet 70 blows toward the surface of the film, local vortices are formed on both sides. Since the temperature of the local vortex is less, it is expected that the airflow will fully flow back to the air outlet 70 area through the local vortex ( Figure 4 The figure shows the local vortex situation). The oblique side wall 923 forms a smooth transition between the vertical side wall 921 and the horizontal side wall 922, which can guide the airflow outside the static pressure box to flow along the sixth flow direction, thereby strengthening the vortex between the static pressure box and the membrane. In another embodiment, it is also possible to replace the local vortex with a backflow ( Figure 9 The figure shows the reverse flow situation), the inclined side wall 923 can strengthen the reverse flow, so that the airflow with less temperature dissipation can fully flow back to the air outlet 70 area.

[0063] In one embodiment, a pair of third vertical partitions 43 are further provided at the air outlet 70, and the third vertical partitions 43 extend from the air outlet 70 toward the second box body 20, thereby forming a slit connected to the air outlet 70 between the pair of third vertical partitions 43, so that the air flow first flows through the slit before being blown out through the air outlet 70. Since the slit is narrow in the horizontal distance, the air flow is quickly balanced along the axial direction in the slit, and the flow rate equalization treatment is performed for the last time before the air flow is blown out.

[0064] In one embodiment, a bending portion 81 is further provided on the side of the third vertical partition 43 away from the air outlet 70. The second vertical partition 42, the third vertical partition 43 and the bending portion 81 together surround and form a flow storage chamber 93. The airflows flowing out of the flow equalization chambers 92 on both sides meet at the side of the slit away from the air outlet 70. The pressure field generated by the meeting of the two sides tends to cause a part of the airflow to be axially equalized and flow out of the air outlet 70 through the slit, and the other part of the airflow can temporarily flow into the flow storage chamber 93 to avoid the airflow disturbance in the slit area affecting the axial equalization. At the same time, the airflow in the flow storage chamber 93 can be axially equalized again and then flow out.

[0065] According to the working principle of the static pressure box in the embodiment of the present invention, the air flow flows into the first box body 10 from the air inlet 50, and first flows through the first flow direction. If the air flow flowing into the first box body 10 generates a vortex, the air flow can be cut by a pair of first vertical partitions 41 during the first flow direction. At the same time, the first flow velocity balance is completed axially in the guide part, and then it flows directly into the equalizing flow cavity 92 of the second box body 20 through the second flow direction. After the air flow completes the second flow velocity balance axially in the equalizing flow cavity 92 through the third flow direction, it flows to the vicinity of the slit through the fourth flow direction, wherein a part of the air flow directly flows out of the air outlet 70 through the gap, and the other part of the air flow returns and flows through the fifth flow direction in the storage cavity 93 to complete the pressure stabilization near the slit.

[0066] refer to Figure 7-9 , shows a schematic diagram of simulation verification of the flow rate and flow direction distribution of the air outlet 70 of an embodiment of the present disclosure. According to the structure of the static pressure box in the embodiment of the present disclosure, the flow rate and flow direction of the air flowing out of the static pressure box air outlet 70 are balanced and stable.

[0067] In an embodiment of another aspect of the present disclosure, the film stretching equipment includes a film conveying mechanism and a static pressure box. The film conveying mechanism loads the film, and the static pressure box is arranged near the two side surfaces of the film, respectively, and blows air flow to the two side surfaces of the film at the same time. The axial direction of the static pressure box is perpendicular to the film conveying direction, ensuring that the temperature field of the film perpendicular to the conveying direction is uniform.

[0068] The description of the embodiments herein and any references to directions and orientations are for ease of description only and are not to be construed as limiting the scope of the present invention. The following description of the preferred embodiments may involve combinations of features, which may exist independently or in combination. The present invention is not specifically limited to the preferred embodiments. The scope of the present invention is defined by the claims.

[0069] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A static pressure box for blowing air toward the surface of a film, characterized in that: include: a box body extending along an axial direction parallel to the surface of the film; a transverse partition, disposed in the box body and separating the box body into a first box body and a second box body along the axial direction, wherein an array of air vents for connecting the first box body and the second box body are formed on the transverse partition; An air inlet is provided at one end of the first box body in the axial direction; an air outlet, provided on the side of the second box body facing the surface of the film and arranged along the axial direction; A vertical partition forms a drainage cavity in the first box body and a flow equalization cavity in the second box body; The guide cavity faces the flow balancing cavity, and the flow balancing cavity and the air outlet are partially separated by the vertical partition along the axial direction, so that the airflow is introduced into the flow balancing cavity through the guide cavity, and after axial flow balancing in the flow balancing cavity, the air is discharged toward the surface of the film through the air outlet; The vertical partitions include a pair of first vertical partitions, which extend from the transverse partition toward the first box body and are arranged on both sides of the first box body along the axial direction, thereby forming a pair of drainage cavities extending along the axial direction together with the side walls of the first box body; A connecting transverse plate is provided between the pair of the first vertical partitions, the connecting transverse plate is connected to the transverse partitions, and covers and closes the air outlet located outside the drainage cavity; The vertical partitions include a pair of second vertical partitions, which extend from the second box body near the air outlet side wall toward the second box body and are opposite to the drainage cavity, thereby forming a pair of flow equalization cavities extending along the axial direction together with the second box body side wall.

2. The static pressure box according to claim 1, characterized in that The second box side wall of the flow balancing chamber includes a vertical side wall, an oblique side wall and a horizontal side wall, and the vertical side wall and the horizontal side wall are connected through the oblique side wall.

3. The static pressure box according to claim 1, characterized in that The air outlets are arranged on the transverse partition in an array with variable spacing along the axial direction.

4. The static pressure box according to claim 1, characterized in that The transverse partition is bent toward the second box body to form the air outlet.

5. The static pressure box according to claim 1, characterized in that It also includes a pair of third vertical partitions, which extend from the air outlet toward the second box body, so that a slit connected to the air outlet is formed between the pair of third vertical partitions, wherein a flow storage cavity is formed between the second and third vertical partitions.

6. The static pressure box according to claim 5, characterized in that A pair of the third vertical partitions are away from the air outlet side and are respectively provided with a bent portion facing the second vertical partition, and the second vertical partition, the third vertical partition and the bent portion together surround and form the flow storage cavity.

7. A film stretching device, characterized in that: include: Film conveying mechanism; A pair of static pressure boxes according to any one of claims 1 to 6, arranged on both sides of the membrane material, wherein the air outlets of the pair of static pressure boxes are respectively directed toward the two side surfaces of the membrane material; Wherein, the axial direction of the static pressure box is perpendicular to the film conveying direction.

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