Upper and lower air duct structure of online reflow soldering hearth

Abstract

The invention discloses an on-line type reflow soldering hearth upper and lower air duct structure which comprises a plurality of hearths used for being arranged at the upper position and the lower position of a heating area of external reflow soldering equipment respectively, an air outlet cavity and a pressurizing cavity are formed in each hearth, and a circulating air duct allowing cold air outside the hearths to flow back to the pressurizing cavities is arranged in the circumferential direction of the hearths. A pressurizing assembly used for heating and pressurizing cold air in the pressurizing cavity and discharging the cold air out of the hearth through the air outlet cavity is arranged in the pressurizing cavity, and an air uniformizing assembly used for uniformizing and discharging heated and pressurized hot air is arranged on the air outlet cavity. The problems that traditional reflow soldering equipment is uneven in hot air distribution and low in heating efficiency, and nitrogen is prone to being rapidly consumed or overflowing in traditional reflow soldering are solved.

Description

Technical Field

[0001] This invention relates to the field of reflow soldering equipment technology, specifically to an online reflow soldering furnace upper and lower air duct structure. Background Technology

[0002] In the electronics manufacturing industry, reflow soldering is a crucial step in surface mount technology for soldering electronic components, and the performance of the equipment directly affects soldering quality and production efficiency. Traditional reflow soldering equipment often suffers from uneven hot air distribution and low heating efficiency, leading to defects such as inconsistent component heating, incomplete solder joints, or over-melting during the soldering process, making it difficult to meet high-precision soldering requirements. Furthermore, to prevent component oxidation during soldering, some reflow soldering equipment requires the introduction of nitrogen to create a protective atmosphere. However, traditional structures lack effective gas circulation design, allowing nitrogen to easily escape or be consumed rapidly through furnace gaps, increasing production costs and potentially affecting soldering reliability due to unstable nitrogen concentrations. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides an online reflow oven upper and lower air duct structure, which solves the problems of uneven hot air distribution, low heating efficiency, and rapid consumption or overflow of nitrogen in traditional reflow ovens.

[0004] To achieve the above objectives, the present invention provides an online reflow oven upper and lower air duct structure, including several oven chambers located above and below the heating zone of an external reflow oven. Each oven chamber has an air outlet chamber and a pressurization chamber. A circulating air duct is arranged circumferentially around the oven chamber to allow cold air from outside the oven to flow back to the pressurization chamber. The pressurization chamber is equipped with a pressurization component for heating and pressurizing the cold air in the pressurization chamber and discharging it from the oven chamber through the air outlet chamber. The air outlet chamber is equipped with a uniform air distribution component for ensuring that the heated and pressurized hot air is evenly distributed during discharge.

[0005] The advantages of adopting the above technical solution are as follows: By separating the furnace chambers at the upper and lower positions of the heating zone in the reflow soldering equipment, and configuring an exhaust chamber, a pressurization chamber, and a circulating air duct, a complete hot air circulation path is constructed. External cold air flows back to the pressurization chamber through the circulating air duct, is heated and pressurized by the pressurization component, and is then evenly discharged into the furnace chamber by the air distribution component. This effectively solves the problems of uneven hot air distribution and low heating efficiency in traditional reflow soldering equipment, resulting in a more uniform and stable temperature field in the welding area. This reduces defects such as incomplete soldering and over-soldering caused by inconsistent heating of components. Simultaneously, the upper and lower air duct structures form a more enclosed gas circulation space. Combined with the circulating air duct design, this slows down the outflow rate of nitrogen in the furnace. The mixing and recirculation of cold air and hot nitrogen achieves nitrogen recycling, reducing the consumption cost of protective gas and improving the reliability and economy of the welding process.

[0006] The present invention further comprises: the pressurization assembly including a pressurization hood, a centrifugal impeller, and a long-shaft motor for driving the centrifugal impeller; the long-shaft motor is located at the bottom of the furnace; the pressurization hood has an air inlet connected to the pressurization chamber, and the centrifugal impeller is movably disposed in the air inlet; the pressurization hood has air outlets bent at both ends toward the air outlet chamber, and the air outlets have air outlets connected to the air outlet chamber.

[0007] The advantages of adopting the above technical solution are as follows: The pressurization component in the above technology adopts a centrifugal impeller and a long-shaft motor drive structure. The centrifugal force generated by the high-speed rotation of the centrifugal impeller is used to efficiently pressurize the air in the pressurization chamber, so that the airflow enters the pressurization hood at a stable pressure. The air outlets at both ends of the pressurization hood are bent towards the air outlet chamber to form a directional flow channel, which accurately guides the pressurized hot air into the air outlet chamber, avoiding energy loss caused by disordered airflow in the chamber. The above structural design enhances the driving efficiency and pressure stability of the hot air, ensuring that the air outlet chamber can continuously output hot air with a constant pressure. This not only improves the temperature uniformity in the furnace, but also provides a stable power foundation for the subsequent uniform air distribution component to achieve uniform air outlet, effectively improving the welding quality fluctuation problem caused by unstable air pressure in traditional equipment.

[0008] The present invention further comprises: the pressure booster shroud is a symmetrical annular cavity assembly, the pressure booster shroud includes an annular flow channel, the inner arc wall, outer arc wall, front end wall and rear end wall of the annular flow channel form a closed annular flow channel surrounding the air inlet, the closed annular flow channel is connected to the air inlet, the radius of curvature of the inner arc wall is smaller than the radius of curvature of the outer arc wall, the two air outlets are symmetrically arranged on both sides of the annular flow channel radial position, and the ends of the two air outlets are connected to the closed annular flow channel.

[0009] The advantages of adopting the above technical solution are as follows: The pressure booster hood with a symmetrical annular cavity structure in the above technology forms a closed annular flow channel around the air inlet through the curvature difference design of the inner and outer arc walls. This allows the airflow driven by the centrifugal impeller to be evenly distributed in the annular flow channel, avoiding local eddies or uneven air pressure caused by abrupt changes in the flow channel cross-section. The air outlets on both sides are symmetrically arranged and connected to the closed annular flow channel, which can synchronously guide the high-pressure airflow in the annular flow channel to the air outlet chamber, ensuring that the air inlet pressure on both sides of the air outlet chamber is consistent. This results in a symmetrical and uniform hot air output at the top and bottom of the furnace. This symmetrical design not only improves the balance of airflow distribution, but also reduces the problem of airflow deviation in the furnace caused by excessive pressure on one side, further optimizing the temperature consistency of the welding area. It is especially suitable for double-sided welding processes of high-precision PCB boards.

[0010] The invention further includes a heating tube for heating the cold air in the pressurization chamber, the heating tube being disposed in the pressurization chamber.

[0011] The advantages of adopting the above technical solution are as follows: The addition of a heating tube in the pressurization chamber allows for direct preheating of the cold air returning to the pressurization chamber, ensuring the cold air receives initial heating before entering the pressurization assembly. This shortens the heat exchange time during the centrifugal impeller pressurization process, improving overall heating efficiency. The synergistic effect of the heating tube and the centrifugal impeller achieves dual control of airflow temperature and pressure. Specifically, the heating tube ensures the airflow reaches the temperature required for the welding process, while the centrifugal impeller ensures sufficient pressure for the airflow to penetrate the uniform airflow assembly and be evenly discharged. This design avoids the high energy consumption and slow heating problems caused by relying solely on the pressurization assembly for heating in traditional equipment. Furthermore, preheating reduces heat loss in the outlet chamber, making temperature control within the furnace more precise, which is particularly suitable for welding temperature-sensitive electronic components.

[0012] The present invention further comprises: detachable rack plates connected to both ends of the furnace chamber; two rack plates are arranged opposite each other and a heating gap is formed between the two rack plates for external PCB boards to pass through; the rack plates are arranged perpendicularly to the furnace chamber; the air outlet chamber is connected to the top wall of the furnace chamber and forms an air outlet groove; the circulating air duct includes several return air inlets distributed on the two rack plates and several return air holes distributed on both sides of the top wall of the furnace chamber; the return air inlets are arranged along the width direction of the furnace chamber and are all connected to the pressurization chamber; the return air holes are arranged along the length direction of the furnace chamber and are all connected to the pressurization chamber.

[0013] The advantages of adopting the above technical solution are as follows: The detachable rack design at both ends of the furnace forms a heating gap for the PCB board to pass through, which not only ensures the continuous operation requirements of the online reflow soldering equipment, but also facilitates the installation, maintenance and cleaning of the furnace. The distributed layout of the return air inlet and return air hole in the circulating air duct, that is, the return air inlet is arranged along the wide diameter direction and the return air hole is arranged along the long diameter direction, allows the cold air outside the furnace to flow back to the pressurization chamber evenly from multiple directions, avoiding the airflow dead zone caused by a single return path and improving the gas circulation efficiency. At the same time, the air outlet chamber is connected to the air outlet slot formed by the top wall of the furnace, which, together with the upward driving airflow of the bottom pressurization component, forms an up-and-down convection hot air circulation mode in the furnace. This not only enhances the heating effect on the front and back of the PCB board, but also slows down the overflow rate of nitrogen through the closed-loop airflow path, realizing the efficient recovery and utilization of protective gas.

[0014] The present invention further includes: the uniform air distribution component includes a perforated plate covering the top wall of the furnace to seal the air outlet slot, and the perforated plate has a plurality of air outlet holes communicating with the air outlet chamber, and the plurality of air outlet holes are evenly distributed on the perforated plate.

[0015] The advantages of adopting the above technical solution are: the perforated plate of the uniform air distribution component in the above technology transforms the high-pressure hot air in the air outlet chamber into a uniformly dispersed airflow through the evenly distributed air outlet holes, avoiding the problem of hot air concentration or deflection caused by uneven hole diameter or unreasonable layout of traditional air outlets. The sealing effect of the perforated plate on the air outlet slots forces the hot air to be discharged through the regularly arranged air outlet holes. By utilizing the flow guiding and homogenizing effect of the perforated plate, the concentrated airflow output by the pressurization component is transformed into a uniform air field covering the entire PCB board surface, ensuring that the heat intensity of each solder joint in the soldering area is consistent.

[0016] The present invention further provides that the perforated plate is a thermal storage aluminum mesh plate.

[0017] The advantages of adopting the above technical solution are: the perforated plate in the above technology is a heat storage aluminum mesh plate, which utilizes the good thermal conductivity and heat storage performance of aluminum material to quickly absorb and store the heat from the hot air output by the pressurization component, forming a stable heat buffer layer.

[0018] The present invention further includes a temperature sensor mounted on the orifice plate.

[0019] The advantages of adopting the above technical solution are: The temperature sensor installed on the orifice plate can monitor the hot air temperature at the outlet of the uniform air distribution component in real time, providing accurate temperature feedback signals to the control system of the reflow soldering equipment. By comparing the sensor data with preset welding process parameters, the control system can dynamically adjust the motor speed of the booster component and the power of the heating element, achieving closed-loop control of the hot air temperature. This design solves the drawback of traditional equipment relying on experience to set temperature parameters, avoiding unstable welding quality caused by temperature drift within the furnace, and is particularly suitable for flexible welding production scenarios involving multiple varieties and processes. Attached Figure Description

[0020] Figure 1 This is a three-dimensional view of the present invention; Figure 2 This is a front sectional view of the present invention; Figure 3 This is a simplified schematic diagram of the present invention in operation. Figure 4 This is a three-dimensional view of the pressure shroud in this invention. Detailed Implementation

[0021] This invention provides an online reflow oven furnace 1 with upper and lower air duct structure, including several furnace chambers 1 located above and below the heating zone of an external reflow oven. Each furnace chamber 1 has an exhaust chamber 11 and a pressurization chamber 12. A circulating air duct is circumferentially arranged around the furnace chamber 1 to allow external cold air to flow back to the pressurization chamber 12. The pressurization chamber 12 is equipped with a pressurization component for heating and pressurizing the cold air within the pressurization chamber 12 and discharging it from the furnace chamber 11 through the exhaust chamber 11. The exhaust chamber 11 is equipped with a uniform air distribution component for evenly discharging the heated and pressurized hot air. The pressurization component includes a pressurization hood 2, a centrifugal impeller 21, and a long-shaft motor 22 for driving the centrifugal impeller 21. A shaft motor 22 is located at the bottom of the furnace 1. An air inlet 211 is provided on the pressure boosting hood 2, which is connected to the pressure boosting chamber 12. A centrifugal impeller 21 is movably disposed within the air inlet 211. Both ends of the pressure boosting hood 2 are bent towards the air outlet chamber 11, with air outlets 23 on each air outlet 23 connected to the air outlet chamber 11. The pressure boosting hood 2 is a symmetrical annular cavity assembly. The pressure boosting hood 2 includes an annular flow channel 24. The inner arc wall, outer arc wall, front end wall, and rear end wall of the annular flow channel 24 enclose a closed annular flow channel 241 surrounding the air inlet 211. The closed annular flow channel 241 is connected to the air inlet 211. The radius of curvature of the arc wall is smaller than that of the outer arc wall. The two air outlets 23 are symmetrically arranged on both sides of the annular flow channel 24 at radial positions. The ends of the two air outlets 231 are connected to the closed annular flow channel 241. The pressurization assembly also includes a heating pipe 25 for heating the cold air in the pressurization chamber 12. The heating pipe 25 is arranged in the pressurization chamber 12. The furnace chamber 1 is detachably connected to the rack plates 3 at both ends. The two rack plates 3 are arranged opposite each other, and a heating gap 31 is formed between the two rack plates 3 to allow the external PCB board to pass through. The rack plates 3 are arranged perpendicularly to the furnace chamber 1. The air outlet chamber 11 is connected to the top wall of the furnace chamber 1 and forms an air outlet groove. 111, the circulating air duct includes a plurality of return air inlets 32 disposed on two support plates 3 and a plurality of return air holes 13 disposed on both sides of the top wall of the furnace 1. The plurality of return air inlets 32 are arranged along the width direction of the furnace 1 and are all connected to the pressurization chamber 12. The plurality of return air holes 13 are arranged along the length direction of the furnace 1 and are all connected to the pressurization chamber 12. The uniform air assembly includes a perforated plate 4 covering the top wall of the furnace 1 to close the air outlet slot 111. The perforated plate 4 has a plurality of air outlet holes 41 that communicate with the air outlet chamber 11. The plurality of air outlet holes 41 are evenly distributed on the perforated plate 4. The perforated plate 4 is a heat storage aluminum mesh perforated plate 4. A temperature sensor 42 is disposed on the perforated plate 4.

[0022] Operating Procedure: During operation, outside cold air flows evenly back to the pressurization chamber through the return air inlets on the end plates of the furnace and the return air holes on both sides of the top wall, forming a circulating air duct. The heating pipes within the pressurization chamber preheat the cold air, raising its base temperature and reducing subsequent heating energy consumption. Then, the long-shaft motor drives the centrifugal impeller to rotate at high speed, using centrifugal force to pressurize the preheated air, allowing it to enter the closed flow channel of the symmetrical annular pressurization hood at a stable pressure. Inside the pressurization hood, the airflow is evenly distributed along the annular flow channel formed by the inner and outer arc walls, and is directionally guided into the outlet chamber through the symmetrical outlets on both sides, avoiding airflow turbulence and energy loss. The heat-storing aluminum mesh plate at the top of the exhaust chamber, through evenly distributed air outlets, transforms high-pressure hot air into a uniform airflow covering the PCB board surface. The heat storage characteristics of the aluminum mesh simultaneously mitigate temperature fluctuations, ensuring consistent heating of the solder joints. After being discharged by the air distribution assembly, the hot air undergoes double-sided heating and soldering of the PCB board within the furnace heating gap. The low-temperature exhaust gas and unconsumed nitrogen generated during the soldering process are returned to the pressurization chamber via the circulation duct, mixing with externally supplied cold air to form a "recirculation preheating - pressurization and guidance - uniform air outlet - closed-loop recovery" cycle system. During this process, temperature sensors on the perforated plate monitor the exhaust air temperature in real time, feeding back to the control system to dynamically adjust the heating tube power and centrifugal impeller speed, achieving precise closed-loop control of hot air temperature and pressure. This improves soldering quality while mitigating nitrogen leakage through the closed-loop airflow path, achieving efficient recycling of protective gas.

[0023] The foregoing has shown and described the basic principles and main features of the present invention, as well as its advantages. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope. All such changes and modifications fall within the scope of the present invention as claimed, which is defined by the appended claims and their equivalents.

Claims

1. An online reflow oven furnace upper and lower air duct structure, comprising several furnace chambers located above and below the heating zone of an external reflow oven, characterized in that: The furnace is provided with an air outlet chamber and a pressurization chamber. The furnace is provided with a circulating air duct around its circumference for cold air from outside the furnace to flow back to the pressurization chamber. The pressurization chamber is provided with a pressurization component for heating and pressurizing the cold air in the pressurization chamber and discharging it from the furnace through the air outlet chamber. The air outlet chamber is provided with a uniform air distribution component for ensuring that the heated and pressurized hot air is evenly distributed during discharge.

2. The structure of the upper and lower air ducts of an online reflow oven according to claim 1, characterized in that: The pressurization assembly includes a pressurization hood, a centrifugal impeller, and a long-shaft motor for driving the centrifugal impeller. The long-shaft motor is located at the bottom of the furnace. An air inlet is provided on the pressurization hood, which is connected to the pressurization chamber, and the centrifugal impeller is movably disposed in the air inlet. Both ends of the pressurization hood are bent toward the air outlet chamber, and air outlets are provided on the air outlets, which are connected to the air outlet chamber.

3. The structure of the upper and lower air ducts of an online reflow oven according to claim 2, characterized in that: The pressurizing shroud is a symmetrical annular cavity assembly. The pressurizing shroud includes an annular flow channel. The inner arc wall, outer arc wall, front end wall, and rear end wall of the annular flow channel form a closed annular flow channel surrounding the air inlet. The closed annular flow channel is connected to the air inlet. The radius of curvature of the inner arc wall is smaller than that of the outer arc wall. The two air outlets are symmetrically arranged on both sides of the annular flow channel radially. The ends of the two air outlets are connected to the closed annular flow channel.

4. The structure of the upper and lower air ducts of an online reflow oven according to claim 1, characterized in that: The pressurization assembly also includes a heating tube for heating the cold air in the pressurization chamber, the heating tube being disposed in the pressurization chamber.

5. The structure of the upper and lower air ducts of an online reflow oven according to claim 1, characterized in that: Both ends of the furnace are detachably connected to racks. The two racks are arranged opposite each other, and a heating gap is formed between the two racks to allow the external PCB board to be processed to pass through. The racks are arranged perpendicularly to the furnace. The air outlet chamber is connected to the top wall of the furnace and forms an air outlet slot. The circulating air duct includes several return air inlets distributed on the two racks and several return air holes distributed on both sides of the top wall of the furnace. The return air inlets are arranged along the width direction of the furnace and are all connected to the pressurization chamber. The return air holes are arranged along the length direction of the furnace and are all connected to the pressurization chamber.

6. The structure of the upper and lower air ducts of an online reflow oven according to claim 5, characterized in that: The uniform air distribution assembly includes a perforated plate covering the top wall of the furnace to seal the air outlet slot. The perforated plate has a plurality of air outlet holes communicating with the air outlet chamber, and the plurality of air outlet holes are evenly distributed on the perforated plate.

7. The structure of the upper and lower air ducts of an online reflow oven according to claim 6, characterized in that: The perforated plate is a thermal storage aluminum mesh plate.

8. The structure of the upper and lower air ducts of an online reflow oven according to claim 6, characterized in that: A temperature sensor is installed on the orifice plate.

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