Nozzle structure of casting heating box of double-drawing production line

Abstract

The invention discloses a double-drawing production line casting heating box nozzle structure, which belongs to the technical field of casting heating, and comprises a fan interface box, a first airflow box, a second airflow box and a third airflow box, two partition plates are arranged in the fan interface box; the fan interface box is connected with the first airflow box, and airflow in the fan interface box can enter the first airflow box; a rectangular crack is formed in the bottom of the first airflow box, and the first airflow box is connected with the second airflow box through the rectangular crack, so that airflow in the first airflow box can enter the second airflow box through the rectangular crack; the second airflow box is connected with the third airflow box through a pore plate, so that airflow in the second airflow box can enter the third airflow box through the pore plate; the third airflow box is of a Venturi structure and comprises a contraction section, a throat part and a diffusion section. The nozzle structure is used for solving the problems that in an existing nozzle structure of the casting heating box, airflow is not evenly distributed in the width direction, and airflow uniformity and stability are insufficient.

Description

Technical Field

[0001] This invention belongs to the field of casting heating technology for biaxial stretching production equipment of plastic film, and is specifically applied to the casting heating box of the biaxial stretching production line. Specifically, it involves a nozzle structure for distributing and adjusting the airflow in the box to meet the requirements of the casting heating process. Background Technology

[0002] In the field of biaxially oriented film production technology, the casting heating box is one of the important pieces of equipment in the production line. Its main function is to preheat and shape the film. The nozzle structure of the casting heating box, as the main component for airflow delivery and distribution, needs to guide the airflow delivered by the fan to the film surface, so as to achieve uniform heating of the film through stable and uniform airflow.

[0003] In existing technologies, the nozzle structure of a casting heating box typically consists of multiple airflow boxes for gradually guiding and distributing airflow. Specifically, the first and second airflow boxes are usually directly connected through an end box to achieve uniform airflow distribution in the width direction. However, this structural design has drawbacks in practical applications. Due to the lack of effective diversion and regulation measures during airflow transport, the airflow delivered by the fan fails to form a uniform pressure and velocity field after entering the airflow box, resulting in uneven airflow distribution in the width direction. Specifically, the airflow velocity at the inlet end is significantly higher than that at the end. This lack of airflow uniformity and stability leads to uneven heating of the film in the width direction, thereby affecting the film's setting effect and product quality. Summary of the Invention

[0004] The purpose of this invention is to provide a nozzle structure for a casting heating box in a biaxial casting production line, so as to solve the problems of uneven airflow distribution in the width direction, insufficient airflow uniformity and stability in the existing casting heating box nozzle structure.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A nozzle structure for a casting heating box in a biaxially oriented production line includes a fan interface box, a first airflow box, a second airflow box, and a third airflow box;

[0007] The fan interface box is equipped with two partitions inside;

[0008] The fan interface box is connected to the first airflow box, and the airflow in the fan interface box can enter the first airflow box;

[0009] The bottom of the first airflow box is provided with a rectangular slit, and the first airflow box is connected to the second airflow box through the rectangular slit, so that the airflow in the first airflow box can enter the second airflow box through the rectangular slit;

[0010] The second airflow box and the third airflow box are connected by a perforated plate, so that the airflow in the second airflow box can enter the third airflow box through the perforated plate;

[0011] The third airflow box has a venturi structure and includes a constriction section, a throat, and a diffuser section, which are connected in sequence.

[0012] In one possible implementation, the two baffles are used to divide the airflow from the fan into three parts within the fan interface box.

[0013] In one possible implementation, the first airflow box has a variable cross-section structure, where the cross-section of the box at the airflow inlet end is larger than the cross-section of the box at the airflow outlet end.

[0014] In one possible implementation, the number of rectangular slits is three.

[0015] In one possible implementation, the airflow in the fan interface box enters the first airflow box after undergoing two 90° reversals.

[0016] In one possible implementation, the diffusion angle of the diffusion segment ranges from 7° to 15°.

[0017] In one possible implementation, the rectangular slit forms an airflow channel between the first airflow box and the second airflow box, which is used to guide the airflow in the first airflow box into the second airflow box.

[0018] In one possible implementation, the orifice plate is disposed between the constriction section of the second airflow box and the third airflow box, so that the airflow in the second airflow box can pass through the orifice plate and the constriction section in sequence to enter the throat.

[0019] In one possible implementation, the cross-section of the contraction section gradually decreases from the side closer to the orifice plate to the side closer to the throat, while the cross-section of the diffusion section gradually increases from the side closer to the throat to the side farther from the throat.

[0020] Compared with the prior art, the advantages of this invention are as follows:

[0021] The two baffles inside the fan interface box evenly divide the airflow into three parts. Combined with two 90° directional changes, this effectively buffers the initial airflow impact and reduces the velocity entering the first airflow box. The first airflow box adopts a variable cross-section structure. The box design, with a large inlet and a small outlet, maintains stable static pressure inside the box. Combined with the guiding effect of the three rectangular slits at the bottom, it allows the airflow to enter the second airflow box more evenly in the width direction, avoiding the problem of excessive airflow velocity difference between the inlet and outlet in traditional structures. The perforated plate between the second and third airflow boxes can redistribute the airflow, further eliminating local turbulence and allowing the airflow to enter the third airflow box more smoothly. In the Venturi structure of the third airflow box, the contraction section accelerates the airflow through a gradual change in cross-section, eliminating local airflow stagnation. The throat provides a stable transition, and the diffuser section is designed with a gradual expansion angle of 7° to 15° to avoid airflow separation, smoothly converting kinetic energy into static pressure, and ultimately achieving uniformity of the outlet airflow velocity.

[0022] CFD simulations verified that the relative root mean square value σ of the nozzle exit velocity based on the above structure is 0.316, which is 72% lower than the 1.144 of the traditional structure. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the nozzle structure of the casting heating box in a biaxially oriented production line according to an embodiment of the present invention;

[0025] Figure 2 This is a side view of the nozzle structure of the casting heating box in a biaxially oriented production line according to an embodiment of the present invention.

[0026] Figure 3 This is a cross-sectional view of the nozzle structure of the casting heating box in the biaxial drawing production line according to an embodiment of the present invention;

[0027] Figure 4 Velocity cloud diagram of a traditional casting heating box nozzle structure;

[0028] Figure 5 This is a velocity contour plot of a nozzle structure based on a Venturi structure.

[0029] In the attached diagram: 1. Fan interface box; 2. First airflow box; 3. Second airflow box; 4. Throat; 5. Diffusion section; 6. First baffle; 7. Second baffle; 8. Rectangular slot; Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0031] Example:

[0032] It should be noted that the terms "comprising" and "having" and any variations thereof in the embodiments of the present invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such processes, methods, products, or devices.

[0033] Figure 1 This is a schematic diagram of the nozzle structure of the casting heating box in a biaxially oriented production line according to an embodiment of the present invention; Figure 2 This is a side view of the nozzle structure of the casting heating box in a biaxially oriented production line according to an embodiment of the present invention. Figure 3 This is a cross-sectional view of the nozzle structure of the casting heating box in a biaxially oriented production line according to an embodiment of the present invention. See also... Figures 1 to 3 The present invention provides a nozzle structure for a casting heating box in a biaxially oriented production line, comprising a fan interface box, a first airflow box, a second airflow box, and a third airflow box;

[0034] The fan interface box is equipped with two partitions inside;

[0035] The fan interface box is connected to the first airflow box, and the airflow in the fan interface box can enter the first airflow box;

[0036] The bottom of the first airflow box is provided with a rectangular slit, and the first airflow box is connected to the second airflow box through the rectangular slit, so that the airflow in the first airflow box can enter the second airflow box through the rectangular slit;

[0037] The second airflow box and the third airflow box are connected by a perforated plate, so that the airflow in the second airflow box can enter the third airflow box through the perforated plate;

[0038] The third airflow box has a venturi structure and includes a constriction section, a throat, and a diffuser section, which are connected in sequence.

[0039] In some embodiments, the two partitions are used to divide the airflow from the fan into three parts within the fan interface box.

[0040] In some embodiments, the first airflow box has a variable cross-section structure, wherein the cross-section of the airflow inlet end of the first airflow box is larger than the cross-section of the airflow outlet end.

[0041] In some embodiments, the number of rectangular slits is three.

[0042] In some embodiments, the airflow in the fan interface box enters the first airflow box after undergoing two 90° reversals.

[0043] In some embodiments, the diffusion angle of the diffusion section ranges from 7° to 15°.

[0044] In some embodiments, the rectangular slit forms an airflow channel between the first airflow box and the second airflow box, which is used to guide the airflow in the first airflow box into the second airflow box.

[0045] In some embodiments, the perforated plate is disposed between the constriction section of the second airflow box and the third airflow box, so that the airflow in the second airflow box can pass through the perforated plate and the constriction section in sequence and enter the throat.

[0046] In some embodiments, the cross-section of the contraction section gradually decreases from the side near the orifice plate to the side near the throat, and the cross-section of the diffusion section gradually increases from the side near the throat to the side away from the throat.

[0047] The following is an overall description of the nozzle structure of the casting heating box in the biaxial drawing production line.

[0048] The nozzle structure in this embodiment includes a fan interface box, a first airflow box, a second airflow box, and a third airflow box. The fan interface box, as the initial airflow inlet component, has two baffles inside. These two baffles are spaced apart along the width of the fan interface box, evenly dividing the airflow input from the external fan into three parts within the box, achieving initial airflow diversion. Simultaneously, the fan interface box is directly connected to the first airflow box. The diverted airflow inside the fan interface box undergoes two 90-degree direction changes—that is, the airflow direction changes twice by 90 degrees—before entering the first airflow box. This direction-changing process further buffers the airflow impact and reduces initial airflow turbulence.

[0049] The first airflow box is connected to the fan interface box to receive the redirected airflow. It has a variable cross-section structure, specifically, the end of the box closer to the fan interface box at the airflow inlet has a larger cross-section, while the end farther from the fan interface box at the airflow outlet has a smaller cross-section. This variable cross-section design ensures stable static pressure within the box from the inlet to the outlet, guaranteeing uniform airflow to subsequent components in the width direction. Furthermore, three rectangular slits are located at the bottom of the first airflow box, arranged parallel to each other along its width, forming an airflow channel between the first and second airflow boxes. This allows airflow from the first airflow box to flow evenly into the second airflow box through these three rectangular slits.

[0050] After receiving the airflow from the first airflow box through the aforementioned rectangular slit, the second airflow box is connected to the third airflow box via a perforated plate. The perforated plate has uniformly distributed through holes. After the airflow flows out of the second airflow box, it must first pass through the through holes of the perforated plate. With the help of the redistribution of the airflow by the perforated plate, the local turbulence in the airflow is further eliminated, allowing the airflow to enter the third airflow box more smoothly.

[0051] The third airflow box adopts a Venturi structure, including a contraction section, a throat, and a diffuser section connected in sequence. The contraction section is located close to the orifice plate, with one end connected to the orifice plate and the other end connected to the throat. The cross-section of the contraction section gradually decreases from the side closer to the orifice plate to the side closer to the throat, allowing the incoming airflow to accelerate and eliminating local airflow stagnation. The throat connects the contraction section and the diffuser section, providing a stable transition channel for the airflow. The diffuser section is connected to the side of the throat away from the contraction section, and its cross-section gradually increases from the side closer to the throat to the side farther away. The diffusion angle of the diffuser section ranges from 7° to 15°. This angle design prevents airflow separation, smoothly converting the kinetic energy of the airflow into static pressure, ultimately homogenizing the airflow velocity exiting the diffuser section and meeting the requirements for airflow uniformity in tape casting heating.

[0052] The airflow delivered by the external fan enters the fan interface box, is divided into three parts by two baffles, and then enters the first airflow box after two 90° deflections. The first airflow box uses a variable cross-section structure to equalize the static pressure. The airflow then flows into the second airflow box through three rectangular slits, and is further evenly distributed through an orifice plate before entering the contraction section of the third airflow box to accelerate the airflow. After passing through the throat transition, the airflow is finally converted into static pressure by the diffuser section and output evenly. The coordinated action of these components ultimately improves the uniformity and stability of the airflow in the width direction.

[0053] To verify the difference in exit velocity uniformity between the traditional nozzle structure of the casting heating box and the nozzle structure based on the Venturi structure, this embodiment uses CFD simulation for comparative analysis. Simultaneously, through... Figure 4 and Figure 5The velocity cloud diagrams of the conventional nozzle structure and the nozzle structure based on the Venturi structure are shown respectively. It can be clearly and intuitively observed from the figure that the velocity distribution at the outlet of the nozzle structure based on the Venturi structure is more uniform.

[0054] To quantify the uniformity of airflow velocity, this embodiment introduces the relative root mean square value of velocity σ as a criterion, and its calculation formula is as follows:

[0055] (1)

[0056] In the formula, For the airflow velocity at the monitoring point, Let n be the average speed on the monitoring line, and n be the number of monitoring points on the monitoring line.

[0057] In the specific operation, the centerline of the nozzle unit outlet was selected as the airflow velocity monitoring line. The velocity values ​​at each point on this centerline were obtained using the post-processing function of CFD software. These velocity values ​​were then substituted into the formula mentioned above to calculate the root mean square value σ of the velocity on the centerline of the nozzle structure. Calculations showed that the outlet velocity σ of the traditional casting heating box nozzle structure was 1.144, while the outlet velocity σ of the nozzle structure based on the Venturi structure was 0.316, a reduction of 72% compared to the traditional structure. This indicates that the nozzle structure based on the Venturi structure is indeed superior in terms of outlet velocity uniformity.

[0058] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0059] The above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made based on the essence of the content of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A nozzle structure for a casting heating box in a double-stretch production line, characterized in that, It includes a fan interface box, a first airflow box, a second airflow box, and a third airflow box; The fan interface box is equipped with two partitions inside; The fan interface box is connected to the first airflow box, and the airflow in the fan interface box can enter the first airflow box; The bottom of the first airflow box is provided with a rectangular slit, and the first airflow box is connected to the second airflow box through the rectangular slit, so that the airflow in the first airflow box can enter the second airflow box through the rectangular slit; The second airflow box and the third airflow box are connected by a perforated plate, so that the airflow in the second airflow box can enter the third airflow box through the perforated plate; The third airflow box has a venturi structure and includes a constriction section, a throat, and a diffuser section, which are connected in sequence.

2. The nozzle structure of the casting heating box in the double-stretch production line according to claim 1, characterized in that, The two partitions are used to divide the airflow from the fan into three parts within the fan interface box.

3. The nozzle structure of the casting heating box in the double-stretch production line according to claim 1, characterized in that, The first airflow box has a variable cross-section structure, and the cross-section of the box at the airflow inlet end of the first airflow box is larger than the cross-section of the box at the airflow outlet end.

4. The nozzle structure of the casting heating box in the biaxially oriented production line according to claim 1, characterized in that, The number of rectangular slits is three.

5. The nozzle structure of the casting heating box in the double-stretch production line according to claim 1, characterized in that, The airflow in the fan interface box enters the first airflow box after undergoing two 90° reversals.

6. The nozzle structure of the casting heating box in the biaxially oriented production line according to claim 1, characterized in that, The diffusion angle of the diffusion section ranges from 7° to 15°.

7. The nozzle structure of the casting heating box in the double-stretch production line according to claim 1, characterized in that, The rectangular slit forms an airflow channel between the first airflow box and the second airflow box, which is used to guide the airflow in the first airflow box into the second airflow box.

8. The nozzle structure of the casting heating box in the biaxially oriented production line according to claim 1, characterized in that, The orifice plate is positioned between the contraction section of the second and third airflow boxes, allowing the airflow in the second airflow box to pass through the orifice plate and the contraction section sequentially into the throat.

9. The nozzle structure of the casting heating box in the double-stretch production line according to claim 1, characterized in that, The cross-section of the contraction section gradually decreases from the side closer to the orifice plate to the side closer to the throat, while the cross-section of the diffusion section gradually increases from the side closer to the throat to the side farther away from the throat.

Images