Hot air knife and high-molecular film-coated plate hot welding equipment and process

Abstract

The hot air knife comprises an air knife body, a hot air cavity is formed in the air knife body, and the hot air knife is characterized in that a main air outlet communicated with the hot air cavity is formed in the front end face of the air knife body; the side wall of the air knife body is provided with at least one air inlet hole communicated with the hot air cavity, and the air inlet hole is arranged close to the rear end of the hot air cavity. An upper air outlet and a lower air outlet which are communicated with the hot air cavity are formed in the top face and the bottom face of the air knife body respectively, and the upper air outlet and the lower air outlet are formed close to the front end face of the air knife body respectively. The laminating efficiency, the qualification rate and the laminating stability of the metal laminated plate are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of metal plate coating, and more particularly to a hot air knife and a hot welding equipment and process for polymer coated plates. Background Technology

[0002] Metal-coated panels are materials that use metal plates as the base material and laminate a polymer film on the surface. Depending on the application scenario, polymer film materials with corresponding functions are laminated onto different or the same metal plates.

[0003] In the production of metal-coated sheets, hot air knives play a crucial role. They spray high-temperature hot air to soften the coating material and force it to adhere tightly to the surface of the metal sheet. However, existing hot air knives simply have an internal chamber with a strip-shaped air outlet at one end, positioned directly at the point where the coating material and metal sheet meet. This design has the following shortcomings: 1. Poor temperature uniformity: Traditional hot air knives cannot guarantee that the temperature of the blown hot air is uniform across the width of the metal plate. For example, when heating a 1.2-meter-wide metal plate with a conventional hot air knife, infrared thermometers show that the temperature difference between the edge and the center of the metal plate can be more than 30°C. This uneven temperature will cause the coating material to be heated unevenly on the surface of the metal plate, resulting in quality problems such as bubbles, wrinkles, and delamination after coating. When the temperature deviation of the metal plate surface exceeds 15°C, the defect rate of the coated product will increase by more than 20%. 2. Low precision in hot air flow control: Existing hot air knife systems lack precision in adjusting hot air flow, failing to make flexible and accurate adjustments based on the material, thickness, and characteristics of the coating material of the metal sheet. When producing metal coated sheets of different specifications, hot air flow is often too high or too low. Excessive hot air flow can blow away incompletely bonded coating material, affecting coating quality; insufficient hot air flow fails to soften the coating material sufficiently, resulting in weak bonding. For example, in the production of 0.6 mm thick aluminum alloy coated sheets, approximately 10% of products exhibited insufficient coating adhesion due to improper hot air flow control. 3. High energy consumption and low thermal efficiency: Most hot air knife systems waste energy during operation. On the one hand, the structural design of the hot air knife itself is unreasonable, resulting in serious heat loss during the transmission of hot air (it is just a chamber set inside with a strip-shaped air outlet at its end). 4. Difficult to adapt to high-speed continuous production: As metal clad laminate manufacturers pursue production efficiency, the operating speed of production lines is constantly increasing. However, the existing hot air knife system cannot heat the metal plate quickly and stably under high-speed production conditions, resulting in unstable cladding quality. Summary of the Invention

[0004] The purpose of this invention is to provide a hot air knife and a hot welding equipment and process for polymer-coated plates. By using this structure and process, the coating efficiency, stability and pass rate are improved, and the production efficiency is also increased.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a hot air knife, comprising a hot air chamber inside the hot air knife body, a main air outlet communicating with the hot air chamber on the front end face of the hot air knife body, and at least one air inlet communicating with the hot air chamber on the side wall of the hot air knife body, wherein the air inlet is located near the rear end of the hot air chamber. The top and bottom surfaces of the air knife body are respectively provided with an upper air outlet and a lower air outlet that communicate with the hot air chamber, and the upper air outlet and the lower air outlet are respectively located near the front end face of the air knife body.

[0006] In the above technical solution, the hot air chamber is also provided with a support frame with a hollow structure, which makes the hot air chamber form multiple air ducts that are connected to the main air outlet, the upper air outlet and the lower air outlet; And / or, multiple air ducts are independently arranged sequentially from left to right; And / or, adjacent air ducts are interconnected.

[0007] In the above technical solution, the support frame includes multiple horizontal plates and multiple vertical plates. The multiple horizontal plates are spaced apart from front to back, and the multiple vertical plates are spaced apart from left to right. Each horizontal plate is perpendicularly connected to the multiple vertical plates, and the multiple horizontal plates and the multiple vertical plates form a mesh structure. Each of the horizontal plates is provided with a plurality of first through holes spaced from left to right, and the horizontal plates between adjacent vertical plates are provided with at least one first through hole; Each of the longitudinal plates is provided with a plurality of second through holes spaced from front to back, and at least one second through hole is provided on the longitudinal plate between adjacent transverse plates.

[0008] In the above technical solution, the two ends of the horizontal plate are respectively connected to the left inner wall and the right inner wall of the hot air chamber, the rear end of the vertical plate is connected to the rear inner wall of the hot air chamber, the front end of the vertical plate is located near the main air outlet, or the front end of the vertical plate is inserted into the main air outlet and located in front of the upper air outlet and the lower air outlet.

[0009] In the above technical solution, the air inlet is connected to the hot air chamber at the rear end of the last horizontal plate.

[0010] In the above technical solution, the support frame divides the hot air chamber into multiple interconnected sub-chambers arranged in a tangential array. There are multiple air inlets, and each of the last sub-chambers in the last row is connected to at least one air inlet.

[0011] In the above technical solution, the diameter of the first through hole on the rear horizontal plate is larger than the diameter of the first through hole on the adjacent front horizontal plate; The diameter of the plurality of second through holes on each of the longitudinal plates gradually decreases from back to front.

[0012] In the above technical solution, multiple sets of temperature control elements are also provided at intervals in the hot air chamber. The multiple sets of temperature control elements are arranged at intervals from left to right, and the temperature control elements are arranged close to the main air outlet or inside the main air outlet. And / or, the temperature control element includes a heating element and a temperature sensor; And / or, a heat insulation layer is provided on the outer surface of the air knife body.

[0013] In the above technical solution, an adjustment plate is also installed on the top of the air knife body. The adjustment plate can move back and forth along the air knife body and adjust the width of the upper air outlet. And / or, the adjustment plate is also provided with multiple longitudinal through slots, which are spaced apart from left to right. When the adjustment plate moves forward, the longitudinal through slots can be positioned directly opposite the upper air outlet.

[0014] This invention also provides a polymer-coated sheet thermal welding device, including a frame, a coating mechanism mounted on the frame, a heater, a metal plate conveying mechanism, and a roll material conveying mechanism. The coating mechanism has a coating space. The metal plate conveying mechanism is used to convey the metal plate to be coated toward the coating space. The roll material conveying mechanism is used to convey the roll material to be bonded toward the coating space. The roll material to be bonded is placed above the metal plate. The device also includes the aforementioned hot air knife, which is mounted on the frame and located behind the coating space. Each air inlet is connected to the heater via a duct. The heater provides hot air to the hot air knife through the duct. The main air outlet is positioned facing the coating space and at the bonding area between the roll material to be bonded and the metal plate to be coated. The upper air outlet is positioned facing the bottom surface of the roll material to be bonded, and the lower air outlet is positioned facing the top surface of the metal plate to be coated. And / or, each of the ducts is provided with a flow regulating device.

[0015] This invention also provides a hot welding process for polymer-coated panels, using the aforementioned hot welding equipment for polymer-coated panels, the steps of which are as follows: S1. The metal sheet conveying mechanism conveys the metal sheet to be coated forward, so that the metal sheet to be coated is continuously conveyed into the coating space. At the same time, the roll material conveying mechanism conveys the roll material to be laminated forward, so that the roll material to be laminated is continuously conveyed into the coating space, and the roll material to be laminated in the coating space is above the metal sheet to be coated. S2. The heater continuously supplies hot air, which is then delivered into the hot air knife through the air duct; S3. The hot air introduced into the hot air knife is sent out from the main air outlet, the upper air outlet and the lower air outlet respectively. The hot air sent out from the upper air outlet blows directly onto the bottom surface of the roll material to be laminated before it enters the lamination space, and preheats the bottom surface of the roll material to be laminated. The hot air from the lower air outlet blows directly onto the top surface of the metal plate to be coated, which has not yet entered the coating space, and preheats the top surface of the metal plate to be coated. The hot air from the main air outlet blows directly onto the contact area between the roll material to be laminated and the metal plate to be laminated in the lamination space to heat it. S4. The laminating mechanism heat-presses the heated roll material to be laminated and the metal plate to be laminated into the laminating space to achieve continuous lamination of the metal plate. After lamination is completed, the metal plate moves forward and leaves the laminating space.

[0016] In the above technical solution, during the process of hot air being delivered by the hot air knife, the temperature of the main air outlet at various positions along its length is detected and adjusted by the temperature control element inside the hot air knife. At the same time, the hot air flow rate of the corresponding air duct is adjusted by the flow rate adjustment device on the air duct so that the temperature at various positions of the main air outlet and / or the upper air outlet and / or the lower air outlet remains basically the same.

[0017] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: 1. In this invention, a main air outlet is provided at the front end of the air knife body, and an upper air outlet and a lower air outlet are respectively provided at the top and bottom of the air knife body near the main air outlet. The upper and lower air outlets can be used to preheat the coil and the metal plate respectively, and then the main air outlet is used to heat the connection between the coil and the metal plate, thereby improving the utilization rate of heat energy, effectively ensuring the coating effect, and also steadily improving production efficiency and pass rate. 2. In this invention, multiple air ducts are set in the hot air chamber, and adjacent air ducts are also connected. This allows the heat sealing to change the flow direction multiple times in the air ducts, making the temperature of the hot air delivered from the air outlet more uniform. This allows the temperature deviation of the hot air blown out in the direction of the width of the metal plate to be controlled within ±5℃, thereby effectively improving the stability and quality of the coating. 3. In this invention, multiple sets of temperature control elements are arranged at intervals from left to right in the hot air chamber and are located close to the main air outlet. This allows the temperature of the main air outlet to be adjusted in real time according to the temperature at different locations at the main air outlet. In addition, the flow rate adjustment device on the air duct adjusts the wind speed of different air ducts, thereby ensuring the uniformity of temperature at the contact point between the hot air and the metal plate, improving the stability and quality of the coating, and also increasing the coating qualification rate. 4. In this invention, by preheating the roll material and the metal sheet, the subsequent lamination efficiency can be effectively improved, thereby increasing production efficiency and reducing production costs. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure in Embodiment 1 of the present invention; Figure 2 yes Figure 1 A bottom view; Figure 3 yes Figure 1 A three-dimensional structural diagram (with an air duct installed on the air inlet); Figure 4 This is a partial cross-sectional view of the front end of the hot air knife in Embodiment 1 of the present invention (support frame not shown). Figure 5 This is a schematic diagram of the internal structure of the air knife body in Embodiment 1 of the present invention; Figure 6 This is a schematic diagram of the structure of the polymer-coated plate hot welding equipment in Embodiment 1 of the present invention; Figure 7 yes Figure 6 Schematic diagram of the middle section.

[0019] The components include: 1. Hot air knife; 2. Roll material; 3. Metal sheet; 4. Frame; 5. Laminating mechanism; 6. Heater; 7. Metal sheet conveying mechanism; 8. Roll material conveying mechanism; 9. Air duct; 11. Air knife body; 12. Hot air chamber; 13. Main air outlet; 14. Air inlet; 15. Upper air outlet; 16. Lower air outlet; 17. Support frame; 18. Air duct; 19. Adjustment plate; 170. Horizontal plate; 171. Vertical plate; 172. First through hole; 173. Second through hole; 174. Partition plate; 190. Longitudinal through groove. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments: Example 1: See Figure 1-7 As shown, a hot air knife includes a hot air knife body 11, a hot air chamber 12 is provided inside the hot air knife body 11, a main air outlet 13 communicating with the hot air chamber 12 is provided on the front end face of the hot air knife body 11, and at least one air inlet 14 communicating with the hot air chamber 12 is provided on the side wall of the hot air knife body 11, and the air inlet 14 is located near the rear end of the hot air chamber 12. The top and bottom surfaces of the air knife body 11 are respectively provided with an upper air outlet 15 and a lower air outlet 16 that communicate with the hot air chamber 12. The upper air outlet 15 and the lower air outlet 16 are respectively located close to the front end face of the air knife body 11.

[0021] In this invention, a hot air knife is positioned between the unbonded coil 2 and the metal plate 3. The main air outlet is positioned directly opposite the bonding area between the coil and the metal plate. During operation, hot air is introduced into the hot air chamber through the air inlet, flows forward, and is expelled from the main air outlet, the upper air outlet, and the lower air outlet. During this process, the hot air from the upper air outlet blows onto the bottom surface of the coil, and the hot air from the lower air outlet blows onto the top surface of the metal plate, thereby achieving advanced bonding between the coil and the metal plate. Preheating is performed, and when the preheated metal sheet and coil are moved to the bonding position, the hot air from the main air outlet blows onto the bonding area, thereby achieving thermal welding (hot pressing) of the coil and metal sheet. In this method, the preheating of the coil and metal sheet allows the coil to be softened in advance, thus ensuring the quality and effect of subsequent lamination. In addition, the preheated hot air can improve the utilization rate of thermal energy and minimize energy waste.

[0022] Preferably, the main air outlet, upper air outlet, and lower air outlet extend from left to right, and their lengths are equal to the left-right length of the front end of the hot air chamber. The lengths of the main air outlet, upper air outlet, and lower air outlet are in the width direction of the coil or metal sheet. More preferably, the width or height of the main air outlet is greater than the width of the upper and lower air outlets. This results in a higher airflow rate at the main air outlet compared to the upper and lower air outlets. The upper and lower air outlets have smaller airflow rates and are mainly used for preheating the coil or metal sheet, while the main air outlet has a larger airflow rate (hot air flow rate) and is used for hot welding and hot-pressing lamination of the coil or metal sheet.

[0023] See Figure 5 As shown, the hot air chamber 12 is also provided with a hollow support frame 17, which makes the hot air chamber 12 form multiple air ducts 18 that are connected to the main air outlet 13, the upper air outlet 15 and the lower air outlet 16.

[0024] Preferably, the multiple air ducts are independently arranged sequentially from left to right, with the rear end of each air duct connected to at least one air inlet. This allows each independent air duct to receive hot air through the air inlet, which is then discharged from the main air outlet, upper air outlet, and lower air outlet. This enables adjustment of the airflow at different locations of the air inlets, i.e., adjusting the airflow at different positions of the main air outlet, upper air outlet, and lower air outlet. This ensures that the temperature at each position along the length of the main air outlet, upper air outlet, and lower air outlet is as consistent as possible, or that the temperature difference at each position is relatively small, thereby ensuring the stability, quality, and pass rate of the coating. Furthermore, the airflow of different air ducts can be adjusted according to the hot airflow requirements of the metal sheet coating location. For example, since the edge of the metal sheet dissipates heat faster, the hot airflow in the air ducts in that area can be appropriately increased to ensure uniform heating between the edge and the center of the metal sheet, thus achieving precise distribution of hot airflow on the surface of the metal sheet (the bonding area between the roll and the metal sheet).

[0025] Furthermore, adjacent air ducts are interconnected. Preferably, the size of the connection point is smaller than the size of the main air outlet, the upper air outlet, and the lower air outlet. In this way, the hot air from the air duct is sent out from the main air outlet, the upper air outlet, and the lower air outlet, and part of it exchanges hot air with other air ducts through the connection point (or exchanges hot air with other air from the hollow support frame). In this way, the hot air sent into the corresponding air duct through different air inlets can flow into other air ducts, so as to ensure that the temperature difference of the hot air sent out by each air duct is as small as possible. By adjusting the flow rate of the hot air sent out by different air inlets, the flow rate of the air at the main air outlet, the upper air outlet, and the lower air outlet of the corresponding air duct can be finely adjusted (slightly larger or smaller). This not only ensures that the temperature difference is small at various positions in the width direction of the metal plate, but also allows for fine-tuning of the hot air flow according to the needs of different positions of the metal plate, so as to ensure the effect, quality, and pass rate of hot welding and hot pressing coating. Of course, different air ducts can be independent of each other or connected to each other, depending on the actual situation. For example, if different air ducts are independent of each other and the same hot air supply equipment is used to supply hot air, it can be ensured that the hot air delivered by each air duct is basically consistent. However, since the hot air delivered to the metal plate heats up the metal plate differently at different locations, it may be difficult to achieve a basically consistent temperature at all locations after the metal plate is heated. Therefore, it is preferable to connect adjacent air ducts. By adjusting the flow rate of different air ducts, the hot air flow rate at different locations can be fine-tuned to minimize the temperature difference after the metal plate is heated.

[0026] See Figure 5As shown, the support frame 17 includes multiple horizontal plates 170 and multiple vertical plates 171. The multiple horizontal plates 170 are spaced apart from front to back, and the multiple vertical plates 171 are spaced apart from left to right. Each horizontal plate 170 is perpendicularly connected to the multiple vertical plates 171, and the multiple horizontal plates 170 and the multiple vertical plates 171 form a mesh structure. Each of the horizontal plates 170 is provided with a plurality of first through holes 172 spaced from left to right, and the horizontal plates 170 between adjacent vertical plates 171 are provided with at least one first through hole 172. Each of the longitudinal plates 171 is provided with a plurality of second through holes 173 spaced from front to back, and the longitudinal plates 171 between adjacent transverse plates 170 are provided with at least one second through hole 173.

[0027] In this embodiment, the horizontal and vertical plates intersect to form a mesh structure. The horizontal and vertical plates are vertically connected, either by welding or by snap-fitting. For example, a lower slot is provided on the bottom surface of the horizontal plate, and an upper slot is provided on the top surface of the vertical plate to engage with the horizontal slot. The horizontal and vertical plates divide the hot air chamber into multiple independent sub-chambers. The presence of the first and second through holes allows adjacent sub-chambers to communicate with each other. Air ducts are formed between adjacent vertical plates, between the leftmost vertical plate and the left inner wall of the hot air chamber, and between the rightmost vertical plate and the right inner wall of the hot air chamber. The horizontal plates, along with the first through holes, connect the front and rear sub-chambers, allowing hot air to flow forward from the rear sub-chambers and exit through the main air outlet, upper air outlet, and lower air outlet. The second through holes connect adjacent sub-chambers, thus connecting adjacent air ducts. Furthermore, the presence of the first and second through holes guides the flow of hot air, causing the hot air to change direction multiple times within the hot air chamber, thereby achieving uniform distribution of hot air. This ensures that the temperature of the hot air blown from the main air outlet, upper air outlet, and lower air outlet is basically the same, and that the temperature deviation of the hot air in the width direction of the metal plate is controlled within ±5℃. This improves the stability of hot welding and hot coating, enhances the coating adhesion, and increases the pass rate.

[0028] Furthermore, the two ends of the horizontal plate are connected to the left and right inner walls of the hot air chamber, respectively, and the rear end of the vertical plate is connected to the rear inner wall of the hot air chamber. The front end of the vertical plate is positioned near the main air outlet, or the front end of the vertical plate is inserted into the main air outlet and positioned in front of the upper and lower air outlets. Preferably, the front end of the vertical plate is positioned near the main air outlet and flush with the front face of the main air outlet. In this way, the hot air delivered from each duct will be delivered from the main air outlet, upper air outlet, and lower air outlet directly opposite the duct (the main air outlet, upper air outlet, and lower air outlet are connected to all ducts).

[0029] The air inlet is connected to the hot air chamber at the rear end of the last horizontal plate. The support frame divides the hot air chamber into multiple interconnected sub-chambers arranged in a tangential array. There are multiple air inlets, and each sub-chamber in the last row is connected to at least one air inlet.

[0030] In this method, hot air can enter the air duct from the rear end of each air duct, then flow forward and be sent out from the main air outlet, the upper air outlet, and the lower air outlet. Preferably, each sub-chamber in the last row is connected to an air inlet. The air inlet can be set on the top surface of the air knife body or on the rear surface of the air knife body. In this embodiment, air inlets are spaced from left to right at the rear end of the top surface of the air knife body. Each air inlet is connected to the top of each sub-chamber in the last row. Furthermore, in addition to multiple air inlets on the top, a first air inlet connected to the hot air chamber can also be provided on the rear end face of the air knife body. This air inlet is connected to the center of the rear end of the hot air chamber. In this way, the last air inlet can be used as the air inlet with the largest flow rate. Hot air is mainly delivered through the last air inlet, while the other air inlets serve as auxiliary, supplementary, or flow rate adjustment. Alternatively, all the air inlets on the top can be used as the main air inlets, while the air inlets at the rear end serve as flow rate supplements. Or, the air inlets at the rear end can be left empty, depending on the actual situation.

[0031] The support frame also includes multiple partitions 174 spaced apart from left to right. The front end of the longitudinal plate is located behind the upper and lower air outlets. The partitions are spaced apart from left to right, with the front end of the partition flush with the front face of the main air outlet. The rear end of the partition is close to the front face of the longitudinal plate, or the rear end of the partition is flush with the front face of the longitudinal plate, or the rear end of the partition is located behind the front face of the longitudinal plate. The air ducts are formed between adjacent partitions and between the outermost partition and the side wall of the hot air chamber. In this way, adjacent air ducts are not connected (the length of the partition is relatively short, less than the length of the longitudinal plate), but they are connected through the first and second through holes between the horizontal and vertical plates, so that the temperature of the hot air entering different air ducts is basically the same and the temperature difference is relatively small. The number of longitudinal plates can be less than the number of partitions, or the number of longitudinal plates can be more than the number of partitions. The partitions, horizontal plates, and longitudinal plates constitute the support frame. In this embodiment, the number of partitions is greater than the number of longitudinal plates, so that the partitions can be used to divide the air ducts into multiple ducts.

[0032] Furthermore, in this embodiment, the top surface of the hot air chamber includes an inclined surface and a first plane, and the bottom surface of the hot air chamber is a second plane. The first plane and the second plane are parallel to each other. The inclined surface is set downwards from back to front, with its rear end connected to the top of the rear end of the hot air chamber, and its front end connected to the rear end of the first plane. The front end of the first plane is flush with the front end of the air knife body. The main air outlet is located at the front end of the first plane and the second plane, the upper air outlet is located on the first plane, and the lower air outlet is located on the second plane. In this way, the air outlet speed of the main air outlet, the upper air outlet, and the lower air outlet will be faster, the air volume will be more concentrated, and the heating effect on the bonding area of ​​the metal plate and the roll material will be better.

[0033] The diameter of the first through hole 172 on the rear horizontal plate 170 is larger than the diameter of the first through hole 712 on the adjacent front horizontal plate 710. The diameter of the plurality of second through holes 172 on each of the longitudinal plates 171 gradually decreases from back to front.

[0034] In this method, the hot air flow direction changes more frequently and faster at the rear end of the hot air chamber, so as to make the temperature of the hot air more uniform at all locations as it flows forward. At the front end of the hot air chamber, the hot air flow direction changes less, so as not to affect the normal air supply of the main air outlet, the upper air outlet, and the lower air outlet as much as possible, and also to minimize the change in direction of the hot air as it flows out of the main air outlet, the upper air outlet, and the lower air outlet. This ensures that the hot air is blown as much as possible onto the corresponding coil, metal plate, and the joint between the two, thereby ensuring the heating of the metal plate and coil and ensuring the subsequent hot welding and hot lamination effects.

[0035] Furthermore, the hot air chamber is also provided with multiple sets of temperature control elements (not shown in the figure), which are arranged from left to right, and the temperature control elements are located near the main air outlet or inside the main air outlet. The temperature control element includes a heating element and a temperature sensor; The heating element can be a miniature heating element, such as a heating wire or heating plate. Each set of temperature control elements is set in an air duct and close to the main air outlet. It can be set directly in front of the upper and lower air outlets and close to the front face of the main air outlet, or it can be set behind the upper and lower air outlets and close to the upper and lower air outlets and the main air outlet. Preferably, the upper and lower air outlets are close to the front face of the air knife body, and the temperature control elements are set in front of the upper and lower air outlets and close to the front face of the air knife body (close to the main air outlet). In this way, since the upper and lower air outlets are mainly used for preheating the coil and metal plate, a slight change in the preheating temperature will not significantly affect the subsequent hot air sent out by the main air outlet to heat-press the bonding area of ​​the metal plate and the coil. The hot air knife is installed on the polymer-coated board hot welding equipment. The temperature control element is connected to the welding equipment's control system. Temperature sensors detect the hot air temperature at the corresponding location of the main air outlet and feed the temperature signal back to the control system (multiple temperature sensors can be spaced out in each temperature control element). When the temperature at a certain location is detected to be lower than the set value, the control system automatically activates the corresponding heating element for compensatory heating or increases the heating power of the heating element. When the temperature is too high, the power of the heating element in that area is reduced. This control further ensures the uniformity of the hot air temperature. Of course, the airflow rate at the corresponding air inlet can also be controlled to adjust the airflow rate and temperature at the corresponding main air outlet.

[0036] In this invention, in order to further reduce the heat loss of the hot air knife, the air knife body can be made of a material with good heat insulation performance. At the same time, a heat insulation layer can be provided on the outer surface of the air knife body to further reduce heat loss, so that the temperature of the air duct body surface can be reduced to below 50°C, effectively improving thermal efficiency.

[0037] See Figure 5 As shown, an adjustment plate 19 is also installed on the top of the air knife body 11. The adjustment plate 19 can move back and forth along the air knife body 11 and adjust the width of the upper air outlet 15.

[0038] In this embodiment, since the hot air from the upper air outlet is used to preheat the roll material, overheating can lead to excessively high roll material temperatures if the main air outlet continues to blow hot air to the junction of the metal plate and the roll material. Furthermore, excessive airflow from the upper air outlet can affect the airflow from the main air outlet, impacting the heating of the metal plate and roll material bonding area. Therefore, an adjusting plate is provided. This adjusting plate can move back and forth, partially or completely blocking the upper air outlet to adjust its width. This allows for adjustment of the flow rate of hot air onto the roll material, preventing overheating. It also adjusts the airflow from the main air outlet, ensuring the bonding quality between the roll material and the metal plate. A groove can be provided on the adjusting plate, and screw holes can be provided on the air knife body. Bolts pass through the groove and screw holes to connect and limit the adjusting plate to the air knife body. When the position of the adjustment plate needs to be adjusted, loosen the bolts, move the adjustment plate, and after the position is adjusted, tighten the bolts to limit the adjustment plate.

[0039] Furthermore, the adjusting plate 19 is also provided with multiple longitudinal through slots 190, which are spaced apart from left to right. When the adjusting plate 19 moves forward, the longitudinal through slots 190 can be positioned directly opposite the upper air outlet 15.

[0040] There is a gap between the front end of the longitudinal channel and the front end of the adjusting plate. This gap can be greater than or less than the width of the upper air outlet. For example, if the gap is greater than the width of the upper air outlet, the adjusting plate can be moved forward so that only part of the longitudinal channel connects to the upper air outlet. In this way, the air delivered from the upper air outlet can only be delivered through the longitudinal channel, which can also reduce the airflow at the upper outlet or facilitate adjustment. Of course, the adjusting plate can also only block part of the upper air outlet, and the longitudinal channel does not connect to the upper air outlet. If the gap is less than the width of the upper air outlet, the front end of the longitudinal channel can still connect to the upper air outlet after the adjusting plate partially blocks the upper air outlet. In this method, when the adjusting plate is not effective in blocking the small gap of the upper air outlet, the longitudinal channel can supplement the airflow at the upper outlet, improving the adjustment effect. Of course, the longitudinal channel can also be omitted as an option.

[0041] See Figure 6 , 7As shown, the present invention also provides a polymer-coated panel thermal welding device, including a frame 4, a coating mechanism 5 mounted on the frame 4, a heater 6, a metal plate conveying mechanism 7, and a roll material conveying mechanism 8 (the above mechanisms are existing structures). The coating mechanism 5 has a coating space, the metal plate conveying mechanism 77 is used to convey the metal plate to be coated toward the coating space, and the roll material conveying mechanism 8 is used to convey the roll material to be bonded toward the coating space. The roll material to be bonded is disposed above the metal plate, and the device also includes the aforementioned... The hot air knife 1 is mounted on the frame 4 and is located on the rear side of the coating space. Each air inlet 14 is connected to the heater 6 via an air duct 9. The heater 6 provides hot air to the hot air knife 1 through the air duct 9. The main air outlet 13 is located facing the coating space and is located at the bonding area between the roll material to be bonded and the metal plate to be coated. The upper air outlet 15 is located on the bottom surface of the roll material to be bonded, and the lower air outlet 16 is located on the top surface of the metal plate to be coated.

[0042] Furthermore, the hot air knife is slidably mounted on the frame, allowing it to move closer to or further away from the coating space. This adjusts the distance between the hot air and the metal plate to ensure the coating effect, and the position of the hot air knife can be adjusted according to the actual situation.

[0043] This invention also provides a hot welding process for polymer-coated panels, using the aforementioned hot welding equipment for polymer-coated panels, the steps of which are as follows: S1. The metal sheet conveying mechanism conveys the metal sheet to be coated forward, so that the metal sheet to be coated is continuously conveyed into the coating space. At the same time, the roll material conveying mechanism conveys the roll material to be laminated forward, so that the roll material to be laminated is continuously conveyed into the coating space, and the roll material to be laminated in the coating space is above the metal sheet to be coated. S2. The heater continuously supplies hot air, which is then delivered into the hot air knife through the air duct; S3. The hot air introduced into the hot air knife is sent out from the main air outlet, the upper air outlet and the lower air outlet respectively. The hot air sent out from the upper air outlet blows directly onto the bottom surface of the roll material to be laminated before it enters the lamination space, and preheats the bottom surface of the roll material to be laminated. The hot air from the lower air outlet blows directly onto the top surface of the metal plate to be coated, which has not yet entered the coating space, and preheats the top surface of the metal plate to be coated. The hot air from the main air outlet blows directly onto the contact area between the roll material to be laminated and the metal plate to be laminated in the lamination space to heat it. S4. The laminating mechanism heat-presses the heated roll material to be laminated and the metal plate to be laminated into the laminating space to achieve continuous lamination of the metal plate. After lamination is completed, the metal plate moves forward and leaves the laminating space.

[0044] In this embodiment, the metal sheet conveying mechanism is used to convey the metal sheet. Since the metal sheet is made of metal, it needs to be conveyed horizontally forward to ensure the coating effect. The coating mechanism uses two coating rollers arranged symmetrically, forming a coating space between them. The bottom surface of the metal sheet and the top surface of the lower coating roller are flush. The roll material conveying mechanism uses an unwinding shaft, on which the roll material is wound. The unwinding shaft is located above the rear end of the hot air knife and releases the roll material through a drive roller, feeding it into the coating space above the metal sheet. Within the membrane space, as the roll material and metal sheet are conveyed forward but before entering the lamination space, hot air from the lower air outlet blows onto the top surface of the metal sheet, and hot air from the upper air outlet blows onto the bottom surface of the metal sheet, preheating both the roll material and the metal sheet. When the roll material and metal sheet enter the lamination space, hot air from the main air outlet blows directly onto the joint between the roll material and the metal sheet, heating the bonding area. Then, two lamination rollers perform hot pressing, thermally welding and pressing the roll material onto the metal sheet. A heater is used to heat the hot air, and the control system can adjust the heater's temperature.

[0045] This invention effectively reduces energy consumption and improves thermal efficiency. Compared with conventional hot air knife structures, the energy consumption of the hot air knife can be reduced by 30% to 40%, effectively lowering costs. Simultaneously, production efficiency is significantly improved, with production line speeds increasing to 6 meters per minute, and the defect rate reduced to below 5% (previously, the defect rate was around 10% to 20%), resulting in a significantly higher pass rate.

[0046] Meanwhile, each of the aforementioned air ducts is equipped with a flow regulating device (not shown in the figure). The flow regulating device is connected to the control system, which adjusts the flow rate delivered into the hot air knife through the air duct, thereby adjusting the flow rate at the corresponding air duct and realizing the adjustment of the flow rate at various positions of the main air outlet. This allows for fine-tuning of the hot air flow rate according to the different hot air flow requirements at different positions of the metal plate. The flow regulating device can be a solenoid valve.

[0047] During the hot air delivery process of the hot air knife, the temperature of the main air outlet at various positions along its length is detected and adjusted by the temperature control element inside the hot air knife. At the same time, the hot air flow rate of the corresponding air duct is adjusted by the flow regulating device on the air duct to ensure that the temperature at various positions of the main air outlet and / or the upper air outlet and / or the lower air outlet is basically consistent, so as to ensure the effect, stability, quality and pass rate of hot welding and hot lamination.

[0048] In the description of this invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0049] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. For instance, the two components can be mechanically connected by contact or abutting; they can also be directly hooked or connected by an intermediate medium; or they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

Claims

1. A hot air knife, comprising a main body, wherein a hot air chamber is provided within the main body, characterized in that: The front end face of the air knife body is provided with a main air outlet communicating with the hot air chamber, and the side wall of the air knife body is provided with at least one air inlet communicating with the hot air chamber. The air inlet is located near the rear end of the hot air chamber. The top and bottom surfaces of the air knife body are respectively provided with an upper air outlet and a lower air outlet that communicate with the hot air chamber, and the upper air outlet and the lower air outlet are respectively located near the front end face of the air knife body.

2. The hot air knife according to claim 1, characterized in that: The hot air chamber is also equipped with a hollow support frame, which makes the hot air chamber form multiple air ducts that are connected to the main air outlet, the upper air outlet and the lower air outlet. And / or, multiple air ducts are independently arranged sequentially from left to right; And / or, adjacent air ducts are interconnected.

3. The hot air knife according to claim 2, characterized in that: The support frame includes multiple horizontal plates and multiple vertical plates. The multiple horizontal plates are spaced apart from front to back, and the multiple vertical plates are spaced apart from left to right. Each horizontal plate is perpendicularly connected to the multiple vertical plates, and the multiple horizontal plates and the multiple vertical plates form a mesh structure. Each of the horizontal plates is provided with a plurality of first through holes spaced from left to right, and the horizontal plates between adjacent vertical plates are provided with at least one first through hole; Each of the longitudinal plates is provided with a plurality of second through holes spaced from front to back, and at least one second through hole is provided on the longitudinal plate between adjacent transverse plates.

4. The hot air knife according to claim 3, characterized in that: The two ends of the horizontal plate are connected to the left inner wall and the right inner wall of the hot air chamber, respectively. The rear end of the vertical plate is connected to the rear inner wall of the hot air chamber. The front end of the vertical plate is located near the main air outlet, or the front end of the vertical plate is inserted into the main air outlet and located in front of the upper air outlet and the lower air outlet.

5. The hot air knife according to claim 3, characterized in that: The air inlet is connected to the hot air chamber at the rear end of the last horizontal plate.

6. The hot air knife according to claim 2, characterized in that: The support frame divides the hot air chamber into multiple interconnected sub-chambers arranged in a tangential array. There are multiple air inlets, and each of the last sub-chambers in the last row is connected to at least one air inlet.

7. The hot air knife according to claim 3, characterized in that: The diameter of the first through hole on the rear horizontal plate is larger than the diameter of the first through hole on the adjacent front horizontal plate; The diameter of the plurality of second through holes on each of the longitudinal plates gradually decreases from back to front.

8. The hot air knife according to claim 1, characterized in that: The hot air chamber is also provided with multiple sets of temperature control elements at intervals. The multiple sets of temperature control elements are arranged at intervals from left to right, and the temperature control elements are located near the main air outlet or inside the main air outlet. And / or, the temperature control element includes a heating element and a temperature sensor; And / or, a heat insulation layer is provided on the outer surface of the air knife body.

9. The hot air knife according to claim 1, characterized in that: An adjustment plate is also installed on the top of the air knife body. The adjustment plate can move back and forth along the air knife body and adjust the width of the upper air outlet. And / or, the adjustment plate is also provided with multiple longitudinal through slots, which are spaced apart from left to right. When the adjustment plate moves forward, the longitudinal through slots can be positioned directly opposite the upper air outlet.

10. A polymer-coated panel thermal welding device, comprising a frame, a coating mechanism mounted on the frame, a heater, a metal plate conveying mechanism, and a roll material conveying mechanism, wherein the coating mechanism has a coating space, the metal plate conveying mechanism is used to convey the metal plate to be coated toward the coating space, the roll material conveying mechanism is used to convey the roll material to be laminated toward the coating space, and the roll material to be laminated is disposed above the metal plate, characterized in that: It also includes a hot air knife as described in any one of claims 1-9, wherein the hot air knife is mounted on the frame and disposed on the rear side of the coating space, each of the air inlets is connected to the heater via an air duct, the heater provides hot air to the hot air knife through the air duct, the main air outlet is disposed facing the coating space and facing the bonding area between the roll material to be bonded and the metal plate to be coated, the upper air outlet is disposed facing the bottom surface of the roll material to be bonded, and the lower air outlet is disposed facing the top surface of the metal plate to be coated; And / or, each of the ducts is provided with a flow regulating device.

11. A hot welding process for polymer-coated panels, characterized in that: The steps of using the polymer-coated panel hot welding equipment as described in claim 10 are as follows: S1. The metal sheet conveying mechanism conveys the metal sheet to be coated forward, so that the metal sheet to be coated is continuously conveyed into the coating space. At the same time, the roll material conveying mechanism conveys the roll material to be laminated forward, so that the roll material to be laminated is continuously conveyed into the coating space, and the roll material to be laminated in the coating space is above the metal sheet to be coated. S2. The heater continuously supplies hot air, which is then delivered into the hot air knife through the air duct; S3. The hot air introduced into the hot air knife is sent out from the main air outlet, the upper air outlet and the lower air outlet respectively. The hot air sent out from the upper air outlet blows directly onto the bottom surface of the roll material to be laminated before it enters the lamination space, and preheats the bottom surface of the roll material to be laminated. The hot air from the lower air outlet blows directly onto the top surface of the metal plate to be coated, which has not yet entered the coating space, and preheats the top surface of the metal plate to be coated. The hot air from the main air outlet blows directly onto the contact area between the roll material to be laminated and the metal plate to be laminated in the lamination space to heat it. S4. The laminating mechanism heat-presses the heated roll material to be laminated and the metal plate to be laminated into the laminating space to achieve continuous lamination of the metal plate. After lamination is completed, the metal plate moves forward and leaves the laminating space.

12. The polymer-coated panel hot welding process according to claim 11, characterized in that: During the hot air delivery process of the hot air knife, the temperature of the main air outlet at various positions along its length is detected and adjusted by the temperature control element inside the hot air knife. At the same time, the hot air flow rate of the corresponding air duct is adjusted by the flow rate adjustment device on the air duct so that the temperature at various positions of the main air outlet and / or the upper air outlet and / or the lower air outlet remains basically the same.

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