Blown film apparatus cooling air ring with local regulation of cooling intensity

Abstract

A cooling air ring for a blown film equipment capable of locally adjusting cooling intensity includes an annular air guide layer between its annular main air duct and an annular air outlet. Multiple radially extending vertical partition plates are uniformly arranged within the annular air guide layer. The annular air guide layer is divided into multiple radial air guide cavities by the vertical partition plates. Each radial air guide cavity is equipped with an air guide cavity cross-section adjustment mechanism, each including a motor, a vertical screw, a nut, and a vertically movable baffle block. An opening is provided in the annular upper clamp to accommodate the baffle block. The radial width of the bottom surface of the baffle block is the same as the radial width of the opening in the annular upper clamp. The outer surface of the lower half of the baffle block slopes from the upper inward to the lower outward. An air guide gap is formed between the outer surface of the baffle block and the sidewall of the opening in the annular upper clamp. This invention can significantly reduce the impact on the airflow of adjacent radial air guide cavities during airflow adjustment in any one radial air guide cavity.

Description

Technical Field

[0001] This invention belongs to the technical field of blown film equipment, and particularly relates to a cooling air ring for blown film equipment that can locally adjust the cooling intensity. Background Technology

[0002] When the blown film equipment is working, molten material is extruded from the gap of the annular die at the die head to form an annular film bubble. Simultaneously, pressurized gas is blown into the film bubble to inflate it; the greater the inflation, the thinner the film bubble becomes. On the other hand, the film bubble reaches a high temperature during extrusion, thus requiring a cooling air ring for cooling to ensure the film bubble's final shape. The cooling air ring includes an annular main air duct on the outer side and an annular air outlet on the inner side. The annular main air duct has a main air inlet, and an annular guide air jacket connects the main air duct to the annular air outlet via the guide air jacket. During operation, the cooling airflow enters the main air duct through the main air inlet, then passes through the guide air jacket and is delivered to the annular air outlet, which is close to and faces the film bubble, thereby cooling it.

[0003] Because the molten material can only enter through a single main feed inlet when it enters the die head of the blown film equipment, and then gradually spreads and distributes within the die head before flowing into the annular die gap, although efforts are made to ensure that the thickness and pressure of the molten material are uniform at all points along the circumference of the annular die gap during this spreading and distribution process, in reality, due to mechanical equipment errors and the limitations of the distribution channel itself, the thickness of the film bubble at each point is difficult to be perfectly uniform in the circumferential direction when the molten material is extruded from the annular die gap; that is, the film bubble thickness is not uniform in the circumferential direction. Similarly, the cooling air ring only has a limited number of 2 to 4 main air inlets, making it difficult to achieve uniform circumferential air velocity at the annular outlet of the cooling air ring.

[0004] In traditional technology, after molten material is extruded from the annular die gap, although the thickness of the bubble can be adjusted by regulating the gas pressure inside the bubble (i.e., adjusting the bubble inflation ratio), this thickness adjustment is systematic and global (i.e., when the thickness at a certain point in the circumferential direction increases, other points in the circumferential direction will inevitably also increase, and vice versa), and cannot be fine-tuned for the thickness at local points in the circumferential direction. Therefore, in traditional technology, even if the thickness is uneven at different points in the circumferential direction after the molten material is extruded from the annular die gap into a bubble, there is a lack of effective remedial measures.

[0005] To address the aforementioned issues, the applicant designed a cooling air ring for blown film equipment capable of locally adjusting the thickness of the film bubble and applied for a Chinese utility model patent, patent number CN202120552112.3. This cooling air ring for blown film equipment has 24 to 72 radially extending vertical partition plates evenly arranged in an annular air guide layer. Each vertical partition plate is evenly distributed radially around the center of the cooling air ring. A radial air guide cavity is formed between every two adjacent vertical partition plates. Each radial air guide cavity is equipped with an air guide channel cross-section adjustment mechanism. Each air guide channel cross-section adjustment mechanism includes a motor, a vertical screw, a nut, and a vertically movable baffle block. In this way, the effective ventilation area of ​​each radial air guide cavity can be controlled independently, thus the cooling intensity of each part of the membrane bubble in the circumferential direction can be controlled independently: when the motor drives the corresponding nut and baffle block to move upward through the vertical screw, so that the vertical position of the baffle block is offset from the vertical position of the radial air guide cavity, the effective area of ​​the corresponding radial air guide cavity is larger, so the membrane bubble in the corresponding position is cooled more, the membrane bubble temperature in the corresponding position is lower, the degree of inflation is smaller, and the film thickness becomes thicker; conversely, when the motor drives the corresponding nut and baffle block to move downward through the vertical screw, so that the vertical position of the baffle block is offset from the vertical position of the radial air guide cavity (or even completely blocks the radial air guide cavity), the effective cross-sectional area of ​​the corresponding radial air guide cavity is smaller, so the membrane bubble in the corresponding position is cooled less (or even has no cooling airflow at all), the membrane bubble temperature in the corresponding position is higher, the degree of inflation is larger, and the film thickness becomes thinner.

[0006] However, in production practice, the applicant found that the above structure still has the following problems that need to be improved: First, when the ventilation area of ​​a radial air guide channel of the cooling air ring is significantly reduced or closed according to the control requirements, it means that the cooling airflow that would normally pass through the radial air guide channel is blocked. This blocked cooling airflow will be forced to flow to the adjacent radial air guide channel, and the airflow in the adjacent radial air guide channel will involuntarily increase. This means that the airflow velocity of any radial air guide channel will be subject to additional and significant interference due to the adjustment action of its adjacent radial air guide channel, thereby affecting the accuracy of the thickness adjustment at each point in the circumferential direction of the membrane bubble, and making the overall control relationship complex and increasing the difficulty of control; Second, the motor (including the control circuit board) of the air guide channel section adjustment mechanism is always in working or standby state, continuously emitting heat. The heat emitted is transferred to the baffle block through the metal screw and nut, making the temperature of the baffle block high. Since the baffle block is located in the radial air guide channel (cooling airflow channel), it affects the cooling effect and also affects the temperature control accuracy. Summary of the Invention

[0007] The purpose of this invention is to overcome the above-mentioned shortcomings by providing a cooling air ring for blown film equipment that can locally adjust the cooling intensity. It can significantly reduce the impact on the airflow of adjacent radial air guide channels during the process of regulating the airflow in any radial air guide channel.

[0008] The objective can be achieved through the following scheme: a cooling air ring for a blown film equipment capable of locally adjusting cooling intensity, comprising an annular main air duct located outside the cooling air ring and an annular air outlet located inside the cooling air ring. The annular main air duct is provided with a main air inlet, and an annular air guide interlayer is provided between the annular main air duct and the annular air outlet. The annular main air duct is connected to the annular air outlet via the annular air guide interlayer. Above the annular air guide interlayer is an upper annular interlayer, and below the annular air guide interlayer is a lower annular interlayer. Multiple radially extending vertical partition plates are uniformly arranged in the annular air guide interlayer. Each vertical partition plate is cooled by... The air-cooling ring is evenly distributed radially from its center. The annular air-guiding interlayer is divided into multiple radial air-guiding cavities by vertical partition plates, with one radial air-guiding cavity formed between each pair of adjacent vertical partition plates. Each radial air-guiding cavity is equipped with an air-guiding cavity cross-section adjustment mechanism, which includes a motor, a vertical screw, a nut, and a vertically movable wind-blocking block. The nut and the wind-blocking block are fixedly connected as one unit. The output shaft of the motor is connected to the vertical screw, and the vertical screw and the nut are screwed together. The annular upper interlayer has openings to accommodate the wind-blocking block.

[0009] When the wind deflector is at the highest point of its vertical movement trajectory, it is located inside the slot of the upper annular clamping plate, with its bottom surface flush with the bottom surface of the upper annular clamping plate. The vertical position of the wind deflector is completely offset from the corresponding radial air guide channel, thus fully opening the radial air guide channel. When the wind deflector is at the lowest point of its vertical movement trajectory, its bottom surface contacts the upper surface of the lower annular clamping plate, and the wind deflector blocks the corresponding radial air guide channel.

[0010] Its main features are that the radial width of the bottom surface of the windbreak block is the same as the radial width of the annular upper plate slot; the outer side of the lower half of the windbreak block slopes from the inner upper to the outer lower; and a wind-guiding gap is formed between the outer side of the windbreak block and the side wall of the annular upper plate slot.

[0011] When the wind deflector is located in the lower middle section of its vertical movement trajectory, the wind deflector gap corresponding to the wind deflector is directly connected to the corresponding radial wind deflector cavity.

[0012] When the wind deflector is at the highest point of its vertical movement trajectory, the bottom surface of the wind deflector will block the opening of the corresponding annular upper clamping plate, and the wind guide gap corresponding to the wind deflector and the corresponding radial wind guide cavity will be separated by the bottom of the wind deflector.

[0013] An annular air chamber is provided above the annular upper clamping plate, and the upper part of the air guide gap is directly connected to the annular air chamber; the annular air chamber is provided with a pressure relief hole that communicates with the outside; the motor is installed in the annular air chamber.

[0014] The number of vertical partition plates in the annular air guide jacket is 24 to 96, and the number of radial air guide channels is 24 to 96.

[0015] When distinguishing between inside and outside, the side closer to the center of the cooling air ring of the blown film equipment is called "inside", and the side farther away from the center of the cooling air ring of the blown film equipment is called "outside".

[0016] The outer side of the wind deflector refers to the side of the wind deflector that faces away from the center of the cooling air ring of the blown film equipment.

[0017] The term "radial" refers to the radial direction of the cooling air ring in the blown film equipment.

[0018] The present invention has the following advantages and effects:

[0019] 1. Because the outer surface of the lower half of the baffle block slopes from the upper inside to the lower outside, and a guide gap is formed between the baffle block and the side wall of the annular upper clamping plate, when the ventilation area of ​​a certain radial guide channel of the cooling air ring is significantly reduced or closed according to the film bubble thickness control requirements of the corresponding position, it means that the baffle block in the corresponding position moves to the lower middle section of its vertical movement trajectory. The cooling airflow blocked by the baffle block will flow upward against the outer surface of the baffle block and be discharged upward through the guide gap; and the smaller the ventilation area of ​​the radial guide channel (equivalent to the lower the vertical position of the baffle block, the greater the degree of obstruction of the cooling airflow), the better. The larger the cooling airflow that needs to be exhausted, the larger the effective ventilation area of ​​the air guide gap (equivalent to a larger effective ventilation area that can exhaust the cooling airflow). Therefore, the cooling airflow in the annular air guide interlayer on the outer end of the corresponding wind baffle block can maintain relatively stable pressure during the control process, thereby significantly reducing the impact on the airflow of adjacent radial air guide cavities. This basically avoids or reduces the additional airflow velocity fluctuations in adjacent radial air guide cavities caused by the control of the airflow velocity of a specific radial air guide cavity, and avoids mutual influence and interference between the radial air guide cavities, making the thickness control of each point in the circumference of the entire membrane bubble more precise and smooth.

[0020] Second, the cooling airflow that flows upward through the air guide gap will converge into the annular air chamber above the annular upper clamping plate. Excess cooling airflow in the annular air chamber can be discharged through the pressure relief hole to avoid excessive pressure in the annular air chamber. The cooling airflow inside the annular air chamber can continuously cool the motor (including the control circuit board), thereby keeping the baffle block that is in physical contact with the motor at a low temperature. This ensures the cooling effect of the cooling airflow through the radial air guide channel on the membrane bubble and also improves the temperature control accuracy. Attached Figure Description

[0021] Figure 1 This is a three-dimensional structural schematic diagram of an embodiment of the present invention.

[0022] Figure 2 yes Figure 1 The structure shown is a cross-sectional view of the windbreak block at the highest point of its vertical movement trajectory.

[0023] Figure 3 yes Figure 2 Schematic diagram of cross-section of KK.

[0024] Figure 4 yes Figure 3 A magnified view of a portion of the Q-axis.

[0025] Figure 5 yes Figure 2 A magnified view of part M in the middle.

[0026] Figure 6 yes Figure 5 The diagram shown is a schematic of the structure after omitting the air guide cavity section adjustment mechanism.

[0027] Figure 7 yes Figure 5 A magnified view of a portion of the image.

[0028] Figure 8 yes Figure 2 The diagram shows the change in the structure as the windbreak block moves to the lowest point of its vertical movement trajectory.

[0029] Figure 9 yes Figure 8 A magnified view of part N in the diagram.

[0030] Figure 10 yes Figure 9 A magnified view of a portion of the image.

[0031] Figure 11 yes Figure 2 The diagram shows the change in the structure as the windbreak block moves to the middle section of its vertical movement trajectory. Detailed Implementation

[0032] Figure 1 , Figure 2 , Figure 3 , Figure 4The cooling air ring of a blown film equipment, which can locally adjust the cooling intensity, includes an annular main air duct 1 located on the outer side of the cooling air ring and an annular air outlet 10 located on the inner side of the cooling air ring. The annular air outlet 10 is arranged circumferentially. The annular main air duct 1 is provided with a main air inlet 11. An annular air guide layer is provided between the annular main air duct 1 and the annular air outlet 10. The annular main air duct 1 is connected to the annular air outlet 10 through the annular air guide layer. Above the annular air guide layer is an annular upper clamping plate 21, and below the annular air guide layer is an annular lower clamping plate 22. Forty-eight radially extending vertical partition plates 2 are uniformly arranged in the annular air guide layer. Each vertical partition plate 2 is evenly distributed radially with the center of the cooling air ring as the center. The annular air guide layer is divided into forty-eight radial air guide channels 20 by the vertical partition plates 2, that is, a radial air guide channel 20 is formed between every two adjacent vertical partition plates 2.

[0033] Figure 2 , Figure 5 , Figure 6 , Figure 7 As shown, each radial air guide channel 20 is provided with an air guide channel cross-section adjustment mechanism. Each air guide channel cross-section adjustment mechanism includes a motor 3, a vertical screw 31, a nut 32, and a wind baffle 4 that can move vertically. The nut 32 and the wind baffle 4 are fixedly connected as one unit and move vertically synchronously. The output shaft of the motor 3 is connected to the vertical screw 31, and the vertical screw 31 and the nut 32 are screwed together. The annular upper clamping plate 21 has a slot 210 for accommodating the wind baffle 4.

[0034] Figure 5 , Figure 7 As shown, the radial width of the bottom surface of the windbreak block 4 (equivalent to...) Figure 7 The radial width of the seam 210 of the annular upper clamp plate (equivalent to the length of AB) and the length of AB. Figure 6 The length of the middle CG is the same; the outer side of the lower half of the windshield block 4 ( Figure 7 The AF surface in the middle slopes from the upper inside to the lower outside (in Figure 7 The middle part is characterized by an inclination from point F to point A, with point F located inside and above point A, and point A located outside and below point F; the outer side of the wind deflector 4 (such as...) Figure 7 The side where AF is located and the side wall of the annular upper splice seam (such as...) Figure 7 An air guide gap 5 is formed between the side wall where RH is located. Figure 2 , Figure 5 , Figure 6 As shown, an annular air chamber 6 is also provided above the annular upper clamping plate 21, and the upper part of the air guide gap 5 is directly connected to the annular air chamber 6; the annular air chamber 6 is provided with a pressure relief hole 60 that communicates with the outside; the motor 3 is installed in the annular air chamber 6.

[0035] When the wind deflector 4 is at the highest point of its vertical movement trajectory, the wind deflector 4 is located inside the slot 210 of the annular upper clamping plate, and the bottom surface of the wind deflector 4 ( Figure 7 The bottom surface of the wind baffle 4 (AB side) is flush with the bottom surface of the annular upper clamping plate 21. The vertical position of the wind baffle 4 is completely offset from the corresponding radial air guide channel 20, thus fully opening the radial air guide channel 20. In addition, the bottom surface of the wind baffle 4 covers the opening 210 of the annular upper clamping plate in the corresponding position. The air guide gap 5 corresponding to the wind baffle 4 and the corresponding radial air guide channel 20 are separated by the bottom of the wind baffle 4. Figure 5 , Figure 6 , Figure 7 As shown;

[0036] When the wind deflector 4 is at the lowest point of its vertical movement trajectory, the bottom surface of the wind deflector 4 contacts the upper surface of the annular lower clamp 22, and the wind deflector 4 blocks the corresponding radial air guide cavity 20, such as... Figure 8 , Figure 9 , Figure 10 As shown;

[0037] When the wind deflector 4 is located in the lower middle section of its vertical movement trajectory, the corresponding air guide gap 5 of the wind deflector 4 is directly connected to the corresponding radial air guide cavity 20, such as... Figure 9 , Figure 10 , Figure 11 As shown.

[0038] The operating principle of the above embodiments is as follows:

[0039] During operation, the membrane bubble continuously moves vertically past the annular air outlet 10; the cooling airflow blows from the annular main air duct 1 through each radial air guide cavity 20 to the annular air outlet 10, and finally blows onto the membrane bubble; when it is detected that the local thickness of some points on the circumference of the membrane bubble is too large, the motor 3 of the corresponding air guide cavity section adjustment mechanism can be started, causing the corresponding wind baffle 4 to move downward. As a result, the ventilation area of ​​the corresponding radial air guide cavity 20 is reduced, the cooling airflow blown onto the membrane bubble through the corresponding radial air guide cavity 20 is reduced, and the temperature of the membrane bubble in the corresponding position increases, the degree of membrane bubble inflation in the corresponding position increases, and the thickness becomes thinner; when the corresponding wind baffle 4 moves downward to the lowest point of its vertical movement trajectory, the bottom surface of the wind baffle 4 contacts the upper surface of the annular lower clamping plate 22, and the wind baffle 4 blocks the corresponding radial air guide cavity 20. During the above process, the intercepted portion of the cooling airflow will flow upwards along the outer surface of the baffle block 4, and then be discharged upwards through the air guide gap 5 and flow into the annular air chamber 6, such as... Figure 10 , Figure 11 As indicated by the arrow (because the annular air chamber 6 is equipped with a pressure relief hole 60, the air pressure in the annular air chamber 6 is basically stable).

[0040] When a local thickness deviation is detected at certain points along the circumference of the membrane bubble, the motor 3 of the corresponding air guide cavity section adjustment mechanism can be activated, causing the corresponding baffle block 4 to move upward. This increases the ventilation area of ​​the corresponding radial air guide cavity 20, enhancing the cooling airflow blowing towards the membrane bubble. Consequently, the membrane bubble temperature decreases, the degree of membrane bubble inflation decreases, and the thickness increases. When the corresponding baffle block 4 moves upward to the highest point of its vertical movement trajectory, its bottom surface blocks the opening 210 of the corresponding annular upper clamping plate. The air guide gap 5 corresponding to the baffle block 4 is separated from the corresponding radial air guide cavity 20 by the bottom of the baffle block 4, and all the cooling airflow flows to the annular outlet 10 / membrane bubble. Figure 7 As indicated by the arrow.

[0041] When the wind deflector 4 moves upward to the middle of its vertical movement trajectory, part of the airflow in the corresponding direction flows towards the annular air outlet 10, and another part of the airflow flows towards the guide gap 5, such as... Figure 11 As shown.

[0042] In the above embodiments, the number of vertical partition plates in the annular air guide jacket can be changed to 24 or 96, and the corresponding number of radial air guide channels is 24 or 96.

Claims

1. A cooling air ring for a blown film equipment capable of locally adjusting cooling intensity, comprising an annular main air duct located outside the cooling air ring and an annular air outlet located inside the cooling air ring. The annular main air duct has a main air inlet, and an annular air guide interlayer is provided between the annular main air duct and the annular air outlet. The annular main air duct is connected to the annular air outlet via the annular air guide interlayer. An upper annular interlayer is located above the annular air guide interlayer, and a lower annular interlayer is located below the annular air guide interlayer. Multiple radially extending vertical partition plates are uniformly arranged in the annular air guide interlayer. Each vertical partition plate is positioned with respect to the center of the cooling air ring. The annular air-guiding interlayer is evenly radially distributed around a central point. It is divided into multiple radial air-guiding cavities by vertical partition plates, with one radial air-guiding cavity formed between each pair of adjacent vertical partition plates. Each radial air-guiding cavity is equipped with an air-guiding cavity cross-section adjustment mechanism. Each air-guiding cavity cross-section adjustment mechanism includes a motor, a vertical screw, a nut, and a vertically movable wind-blocking block. The nut and the wind-blocking block are fixedly connected as one unit. The output shaft of the motor is connected to the vertical screw, and the vertical screw and the nut are screwed together. The annular upper interlayer has openings for accommodating the wind-blocking block. When the wind deflector is at the highest point of its vertical movement trajectory, it is located inside the slot of the upper annular clamping plate, with its bottom surface flush with the bottom surface of the upper annular clamping plate. The vertical position of the wind deflector is completely offset from the corresponding radial air guide channel, thus fully opening the radial air guide channel. When the wind deflector is at the lowest point of its vertical movement trajectory, its bottom surface contacts the upper surface of the lower annular clamping plate, and the wind deflector blocks the corresponding radial air guide channel. Its features are: The radial width of the bottom surface of the windbreak block is the same as the radial width of the annular upper clamping plate seam; the outer side of the lower half of the windbreak block slopes from the inner upper to the outer lower; a wind-guiding gap is formed between the outer side of the windbreak block and the side wall of the annular upper clamping plate seam. When the wind deflector is located in the lower middle section of its vertical movement trajectory, the wind deflector gap corresponding to the wind deflector is directly connected to the corresponding radial wind deflector cavity. When the wind deflector is at the highest point of its vertical movement trajectory, the bottom surface of the wind deflector will block the opening of the corresponding annular upper clamping plate, and the wind guide gap corresponding to the wind deflector and the corresponding radial wind guide cavity will be separated by the bottom of the wind deflector.

2. The cooling air ring of the blown film equipment capable of locally adjusting cooling intensity according to claim 1, characterized in that: An annular air chamber is provided above the annular upper clamping plate, and the upper part of the air guide gap is directly connected to the annular air chamber; the annular air chamber is provided with a pressure relief hole that communicates with the outside; the motor is installed in the annular air chamber.

3. The cooling air ring of the blown film equipment capable of locally adjusting cooling intensity according to claim 1 or 2, characterized in that: The number of vertical partition plates in the annular air guide jacket is 24 to 96, and the number of radial air guide channels is 24 to 96.

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