A dual-inlet square diaphragm high-efficiency uniform heating device

Abstract

This invention discloses a dual-inlet square diaphragm high-efficiency uniform heating device, comprising a heating device, a concentric rectangular reducer, and a centrifugal fan. The heating device includes an inlet pipe, an air heater, an annular static pressure chamber, a main air duct, a hollow guide structure, and a flow guide. The centrifugal fan is connected to the large end of the concentric rectangular reducer via a flange. The small end of the concentric rectangular reducer is connected to the inlet pipe of the heating device. The other end of the inlet pipe is connected to the annular static pressure chamber, which is connected to the main air duct. The hollow guide structure is disposed within the main air duct, and the flow guide is slidably connected to the main air duct. An air heater is arranged inside the inlet pipe. This invention employs dual centrifugal fan inputs, uses an annular static pressure chamber to control the air velocity from horizontal to vertical, incorporates a hollow guide structure to improve the uniformity of the air velocity at the outlet plane of the heating device, and uses a retractable flow guide to change its distance from the heating diaphragm surface, thereby improving heating efficiency and flow field distribution.

Description

Technical Field

[0001] This invention belongs to the technical field of biaxial stretching machines for thin films, specifically relating to a high-efficiency and uniform heating device for square films with dual inlets. Background Technology

[0002] A biaxially oriented film stretching machine can clamp a square film sheet of a certain specification onto a fixture, guide it through different ovens for heating, stretching, shaping, and cooling. The movement of the fixture stretches the film both laterally and longitudinally to obtain a biaxially oriented film. The heating and stretching process is completed in the stretching zone oven. Uneven airflow from the heating device in the stretching zone can lead to uneven heating of the film sheet, resulting in problems such as film breakage, uneven thickness, or uneven stress after stretching. Summary of the Invention

[0003] The main objective of this invention is to overcome the shortcomings and deficiencies of the prior art and to propose a dual-inlet square diaphragm high-efficiency and uniform heating device.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A dual-inlet square diaphragm high-efficiency uniform heating device includes a heating device, a central rectangular reducer tube, and a centrifugal fan.

[0006] The heating device includes an air inlet pipe, an air heater, an annular static pressure chamber, a main air duct, a hollow flow guide structure, and a flow diverter;

[0007] The centrifugal fan is connected to the large end of the central rectangular reducer pipe via a flange. The small end of the central rectangular reducer pipe is connected to the air inlet pipe of the heating device. The other end of the air inlet pipe is connected to the annular static pressure chamber. The annular static pressure chamber is connected to the main air duct. The hollow guide structure is set inside the main air duct. The guide device is slidably connected to the main air duct. An air heater is arranged inside the air inlet pipe.

[0008] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0009] 1. The device of this invention controls the change of air velocity from horizontal to vertical by rationally designing the cross-sectional change of the annular static pressure chamber (the uniformity of air velocity in the circumferential direction when the airflow enters the main air duct); through guide vanes and circular guide plates, and by optimizing their structural parameters through simulation, the uniformity of the air velocity in the outlet plane of the heating device is improved, and a channel is provided to the infrared temperature measuring device, thereby ensuring that the film can be uniformly heated; by using a retractable flow guide, the distance between it and the surface of the heating film is changed, thereby improving the heating efficiency and improving the flow field distribution. Attached Figure Description

[0010] Figure 1This is a schematic diagram of the overall structure of the device of the present invention;

[0011] Figure 2 This is a schematic diagram of the heating air duct of the device of the present invention;

[0012] Figure 3 This is a schematic diagram of the annular static pressure chamber;

[0013] Figure 4 This is a perspective view of the main air duct;

[0014] Figure 5 This is a schematic diagram of the drainage device in its contracted state;

[0015] Figure 6 This is a schematic diagram of the drainage device in its extended state;

[0016] Reference numerals: 1-Centrifugal fan; 2-Rectangular reducing pipe; 3-Infrared temperature measuring device; 4-Heating device; 41-Inlet pipe; 42-Annular static pressure chamber; 43-Main air duct; 44-Guide vane; 45-Circular baffle; 46-Drainage device; 47-Arc-shaped static pressure box; 48-Air heater. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0018] Example

[0019] like Figure 1 and Figure 2 As shown, the present invention provides a dual-inlet square diaphragm high-efficiency uniform heating device, comprising a heating device 4, an infrared temperature measuring device 3, a central rectangular variable diameter tube 2, and a centrifugal fan 1.

[0020] The heating device includes an air inlet pipe 41, an annular static pressure chamber 42, a main air duct 43, a hollow flow guide structure, a flow diverter 46, and an air heater 48.

[0021] like Figure 1 As shown, there are two sets of the central rectangular reducing pipe, centrifugal fan, air inlet pipe, and air heater.

[0022] The centrifugal fan is connected to the large end of the central rectangular reducer pipe via a flange. The small end of the central rectangular reducer pipe is connected to the air inlet pipe of the heating device. The other end of the air inlet pipe is connected to the annular static pressure chamber. The annular static pressure chamber is connected to the main air duct. The hollow guide structure is set inside the main air duct. The guide device is slidably connected to the main air duct. An air heater is arranged inside the air inlet pipe.

[0023] In this embodiment, as Figure 3As shown, the annular static pressure chamber is specifically composed of two symmetrically opposite variable cross-section arc-shaped static pressure boxes 47 connected together, and has two air inlet ends; the two air inlet ends are respectively connected to the air inlet pipe, and the other end of the air inlet pipe is connected to the small end of the central rectangular variable diameter pipe.

[0024] A circular hole is provided at the top of the annular static pressure chamber, and an infrared temperature measuring device is fixed on the circular hole at the top of the annular static pressure chamber.

[0025] In this embodiment, the two centrifugal fans are arranged symmetrically and discharge air horizontally.

[0026] Considering the air supply characteristics of the static pressure chamber air supply structure, the air will undergo spiral motion after entering the main air duct from the static pressure chamber. The circumferential motion of the airflow in the air duct has a significant negative impact on the velocity uniformity. Therefore, a corresponding hollow guide structure is set up to reduce the impact of the circumferential motion of the air on the outlet velocity, and a channel is provided for the infrared temperature measurement device. The hollow guide structure includes guide vanes 44 and circular baffles 45; if only guide vanes are used, it will inevitably lead to an increase in radial airflow, causing the airflow to converge towards the center of the main air duct. Therefore, a cylindrical baffle is added inside the vanes.

[0027] like Figure 4 As shown, a circular baffle is fixed to the top of the guide vane, and the guide vane and the circular guide vane are welded to the top (top plate) of the annular static pressure chamber. There are multiple guide vanes. When the number of vanes is large, the gas accumulation phenomenon in each independent area is reduced, so that the axial velocity can be distributed more evenly. However, considering that too many vanes will reduce the manufacturability of the structure, the number of vanes in this embodiment is 16.

[0028] In addition, the structural parameters of the guide vanes and circular baffles were optimized through CFD simulation to achieve better uniformity.

[0029] During the heating stage, in order to enable the diaphragm to reach the required temperature more quickly, reduce heat consumption, and improve heating efficiency, the air outlet of the heating device should be within 10mm of the surface of the thick sheet. However, if the heating device is too long, it will affect the movement of the guide rail. Therefore, this embodiment is equipped with a height-adjustable air guide. Figure 2 As shown, the upper and lower ends of the drainage device have different shapes and outlines; the upper end has a circular outline, while the lower end has a square outline.

[0030] The drainage device can be controlled by sliding along a slide rail to control its up and down travel, thereby controlling the distance between the drainage device and the surface of the square membrane.

[0031] The drainage device is in a contracted state during the preheating and stretching phases, such as Figure 5 As shown; it is in an elongated state during the heating stage, as... Figure 6As shown. In the contracted state, the distance between the heating device outlet and the diaphragm should be greater than half the height of the diaphragm clamping mechanism, with a certain safety margin. In the extended state, the distance between the outlet and the diaphragm is only 5-10mm. The principle behind this design is that the film stretching process can be divided into three stages: preheating, heating, and stretching. In the preheating and stretching stages, it is necessary to maintain the overall oven temperature while avoiding excessive local temperatures. Therefore, the outlet distance from the diaphragm is relatively large at this time, allowing the hot airflow to fully develop within the oven. In the heating stage, the main purpose is to increase the diaphragm surface temperature and make it as consistent as possible with the hot airflow temperature, which helps control the diaphragm temperature. Keeping the outlet close to the diaphragm surface reduces heat loss, increases the heating rate, and ensures that the diaphragm surface temperature matches the preset temperature. Furthermore, the retractable structure effectively prevents mechanical collisions during device movement, improving device safety.

[0032] In this embodiment, during the heating process, hot air input by a centrifugal fan passes through an annular static pressure chamber, then through guide vanes and a circular baffle before entering the main air duct. It is then blown out evenly from below the air intake, thereby uniformly heating the diaphragm below it. The air intake can extend and retract, thus changing its distance from the surface of the heated diaphragm, thereby improving heating efficiency and flow field distribution.

[0033] It should also be noted that, in this specification, terms such as "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0034] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A dual-inlet square diaphragm high-efficiency uniform heating device, characterized in that, Includes heating devices, a central rectangular reducing pipe, and a centrifugal fan; The heating device includes an air inlet pipe, an air heater, an annular static pressure chamber, a main air duct, a hollow flow guide structure, and a flow diverter; The centrifugal fan is connected to the large end of the central rectangular reducer via a flange. The small end of the central rectangular reducer is connected to the air inlet pipe of the heating device. The other end of the air inlet pipe is connected to the annular static pressure chamber. The annular static pressure chamber is connected to the main air duct. The hollow guide structure is set inside the main air duct. The guide device is slidably connected to the main air duct. An air heater is arranged inside the air inlet pipe. The hollow flow guide structure includes flow guide blades and a circular baffle, and is equipped with a channel for infrared temperature measurement. There are multiple guide vanes, and a circular baffle is fixed to the top of the guide vanes. The guide vanes and the circular baffle are welded to the top of the annular static pressure chamber. The structural parameters of the guide vanes and circular baffles were obtained through CFD simulation optimization.

2. The dual-inlet square diaphragm high-efficiency uniform heating device according to claim 1, characterized in that, Two of each are provided: a rectangular reducing pipe, a centrifugal fan, an air inlet pipe, and an air heater.

3. The dual-inlet square diaphragm high-efficiency uniform heating device according to claim 2, characterized in that, The annular static pressure chamber is specifically composed of two symmetrically placed, inverted arc-shaped variable cross-section static pressure boxes connected together, and has two air inlet ends.

4. The dual-inlet square diaphragm high-efficiency uniform heating device according to claim 3, characterized in that, The two inlet ends of the annular static pressure chamber are connected to the inlet pipes, and the other end of the inlet pipes is connected to the small end of the central rectangular reducer.

5. The dual-inlet square diaphragm high-efficiency uniform heating device according to claim 2, characterized in that, Two centrifugal fans are arranged symmetrically and discharge air horizontally.

6. The dual-inlet square diaphragm high-efficiency uniform heating device according to claim 1, characterized in that, It also includes infrared temperature measurement devices; A circular hole is opened at the top of the annular static pressure chamber, and an infrared temperature measuring device is fixed on the circular hole at the top of the annular static pressure chamber.

7. The dual-inlet square diaphragm high-efficiency uniform heating device according to claim 1, characterized in that, The upper and lower ends of the drainage device have different shapes and outlines; the upper end is circular and the lower end is square. The drainage device can be controlled by sliding along a slide rail to control its up and down travel, thereby controlling the distance between the drainage device and the surface of the square membrane.

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