SMT reflow soldering furnace

Abstract

The invention relates to an SMT reflow soldering furnace which comprises a furnace body, a preheating area, a soldering area and a cooling area are arranged in the furnace body, a heating assembly for heating the soldering area is arranged on the furnace body, a surrounding plate is arranged in the soldering area, an air exhaust assembly is arranged in the furnace body and comprises a vacuum pump arranged on the furnace body, and the air exhaust end of the vacuum pump communicates with a main air pipe. The main air pipe is communicated with the two branch air pipes, each branch air pipe is communicated with the multiple air suction pipes, the length direction of the air suction pipes is parallel to the length direction of the welding area, the air suction pipes are communicated with the multiple air suction nozzles, and air in the welding area is exhausted in time due to the arrangement of the air exhaust assembly; and the possibility of forming a cavity due to gas residue is reduced, so that the mechanical strength of a welding spot is improved. The welding device has the effect of improving the welding quality.

Description

Technical Field

[0001] The present application relates to the technical field of reflow soldering furnaces, and in particular to an SMT reflow soldering furnace. Background Art

[0002] The SMT reflow oven is a device used for surface mount technology. Its basic principle is to heat the solder paste on the printed circuit board to melt the solder paste, so as to solder the surface mount components to the pads of the PCB board. In this process, the solder paste first goes through a preheating stage, the temperature gradually rises, and the volatile components are removed. Then it enters a high-temperature soldering stage, the solder paste is completely melted, and the liquid solder forms a good metal connection with the component pins and the PCB pad under the action of surface tension and gravity. Finally, after a cooling stage, the solder solidifies and the soldering process is completed.

[0003] However, during the welding process, the welding area is filled with a large amount of gas generated by the melting of solder paste. When the melted solder paste condenses, the gas remaining in the melted solder paste will be retained inside the solder paste, thereby forming voids. Affected by the void factor, the mechanical strength of the solder joint is reduced, and the thermal and electrical conductivity of the solder joint and the electrical function of the equipment are seriously affected. The welding quality of the reflow soldering furnace is reduced, and there are obvious shortcomings. Summary of the invention

[0004] In order to improve the welding quality, the present application provides a SMT reflow oven.

[0005] The SMT reflow oven provided in this application adopts the following technical solution: A SMT reflow oven comprises a furnace body, wherein a preheating zone, a welding zone and a cooling zone are arranged in the furnace body, a conveyor belt for conveying materials to be processed is arranged in the furnace body, a heating assembly for heating the welding zone is arranged on the furnace body, a surrounding plate is arranged in the welding zone, the furnace body cover is arranged on the outer surface of the surrounding plate, an exhaust assembly is arranged in the furnace body, the exhaust assembly comprises a vacuum pump arranged on the furnace body, the exhaust end of the vacuum pump is connected to a main air pipe, two branch air pipes are connected to the main air pipe, the two branch air pipes are respectively arranged inside the inner side walls opposite to each other of the surrounding plate, each branch air pipe is connected to a plurality of suction pipes, the length direction of the suction pipe is parallel to the length direction of the welding zone, the suction pipe is connected to a plurality of suction nozzles, the plurality of suction nozzles are evenly distributed along the length direction of the suction pipe, and the suction direction of the suction nozzle is arranged toward the surface of the material.

[0006] By adopting the above technical scheme, during welding, the heating component makes the preheating zone reach the preheating temperature, and the welding zone reaches the welding temperature, and then the conveyor belt makes the material pass through the heating zone, welding zone and cooling zone in sequence. When the material passes through the welding zone, the vacuum pump is started, and the vacuum pump forms a negative pressure environment in the main air pipe, the branch air pipe and the suction pipe. The gas generated by the melting of the solder paste in the welding zone enters the suction pipe through multiple suction nozzles under the action of the pressure difference. The gas absorbed in the suction pipe is gathered into the main air pipe through the branch air pipe and is finally discharged by the vacuum pump. The setting of the exhaust component realizes the timely discharge of the gas in the welding zone, reduces the possibility of forming voids due to gas residue, thereby improving the mechanical strength of the solder joint and improving the welding quality.

[0007] Optionally, the heating component includes a nitrogen tank, a nitrogen pipeline connected to the welding zone is provided on the nitrogen tank, a heating wire is provided in the nitrogen pipeline, a mixing temperature zone is formed between the outer surface of the enclosure and the inner wall of the welding zone, a plurality of air inlets connected to the mixing temperature zone are opened on the top wall of the enclosure, a windshield cloth is provided on the enclosure, a fixing component and a winding component are provided on the enclosure, a plurality of temperature sensors for detecting the uniformity of temperature distribution in the mixing temperature zone are provided on the inner wall of the mixing temperature zone, when the temperature distribution in the mixing temperature zone is uneven, the fixing component unfolds the windshield cloth, and the windshield cloth covers the plurality of air inlets, and when the temperature distribution in the mixing temperature zone is uniform, the winding component winds up the windshield cloth.

[0008] By adopting the above technical scheme, the heated nitrogen directly enters the mixed temperature zone through the nitrogen pipeline. When multiple temperature sensors detect that the temperature distribution in the mixed temperature zone is in an uneven state, the fixed component fixes the windshield cloth so that the windshield cloth covers multiple air inlets, thereby preventing the nitrogen with uneven temperature distribution in the mixed temperature zone from entering the interior of the enclosure. When the temperature sensor detects that the temperature distribution in the mixed temperature zone is uniform, the fixed component cancels the fixing effect on the windshield cloth, and the winding component drives the windshield cloth to wind up, so that multiple air inlets are opened, and nitrogen with uniform temperature enters the interior of the enclosure, so that the solder paste can be heated more evenly and volatilized evenly during the melting process, avoiding local overheating of the solder paste and causing a large amount of gasification to produce voids. At the same time, the uniformity of the solder paste flow is improved, and the space for gas residue is reduced, thereby reducing the probability of void generation and further improving the welding quality.

[0009] Optionally, the winding assembly includes a winding roller rotatably connected to one side of the enclosure, the windshield cloth is arranged on the outer circumference of the winding roller, one end of the windshield cloth is arranged on the winding roller, and the other end is arranged with a connecting rod, and sliding frames slidably matched with the connecting rod are arranged on opposite sides of the enclosure, a winding spring is arranged on the windshield cloth, one end of the winding spring is arranged on the winding roller, and when the winding spring is in a natural state, the windshield cloth is wound on the winding roller, and an electromagnetic block is arranged on the end of the two sliding frames away from the winding roller, and a magnetic block magnetically connected to the electromagnetic block is arranged on the connecting rod, and the temperature sensor is electrically connected to the electromagnetic block through a control system.

[0010] By adopting the above technical scheme, when multiple temperature sensors detect that the temperature distribution in the mixed temperature zone is uneven, the electromagnetic block attracts the magnetic block, and the connecting rod is fixed by the electromagnetic block at the end of the sliding frame away from the winding roller. At this time, the windshield cloth is unfolded on the surface of the enclosure, and the coil spring is in a flat state. When each temperature sensor detects that the temperature distribution in the mixed temperature zone is uniform, the temperature sensor controls the electromagnetic block to cut off the power, and the adsorption effect of the electromagnetic block on the magnetic block disappears. At this time, the tension on the coil spring disappears, and the coil spring automatically reels under the action of the elastic force. The rewinding of the coil spring drives the windshield cloth to be reeled on the winding roller, and the air inlet is in an open state. Nitrogen with uniform temperature distribution enters the interior of the enclosure through the air inlet, thereby improving the uniformity of heating in the welding area inside the enclosure.

[0011] Optionally, a rubber bellows is provided in each sliding frame, the length direction of the rubber bellows is parallel to the length direction of the sliding frame, the end face of the rubber bellows abuts against the surface of the connecting rod, and the furnace body is provided with an air charging and discharging component for charging and discharging air into the rubber bellows.

[0012] By adopting the above technical solution, when the temperature sensor detects that the temperature distribution in the mixing temperature zone is uneven, the temperature sensor energizes the electromagnetic block through the control system, and at the same time the inflation and deflation assembly starts and inflates the rubber bellows. The rubber bellows inflates and expands and pushes the connecting rod to move toward the electromagnetic block. When the magnetic block moves to the vicinity of the electromagnetic block, the electromagnetic block absorbs the magnetic block, and the connecting rod is fixed by the electromagnetic block and the magnetic block at the end of the sliding frame away from the winding roller, thereby realizing the unfolding of the windshield cloth, preventing nitrogen with uneven temperature distribution in the mixing temperature zone from entering the interior of the enclosure, and ensuring the uniformity of temperature distribution inside the enclosure.

[0013] Optionally, the inflation and deflation assembly includes an air collecting box connected to the air outlet end of the vacuum pump, the air collecting box is connected to inflation pipes corresponding to the two rubber bellows one by one, the inflation pipes are connected to the corresponding rubber bellows, each of the inflation pipes is provided with a first solenoid valve, the temperature sensor is electrically connected to the first solenoid valve through a control system, and the air collecting box is provided with a pressure relief valve.

[0014] By adopting the above technical scheme, the gas extracted by the vacuum pump finally enters the gas collecting box along the main gas pipe. When the temperature sensor detects that the temperature distribution in the mixed temperature zone is uneven, the temperature sensor controls the first solenoid valve to start through the control system, and the gas in the gas collecting box moves to the rubber bellows through the inflation pipe, thereby realizing the unfolding of the windshield cloth. After the windshield cloth is unfolded, the pressure relief valve is started, the pressure in the gas collecting box becomes smaller, and the gas in the rubber bellows flows to the gas collecting box. When the windshield cloth needs to be rolled up, the connecting rod pushes the rubber bellows to reset. Such a setting realizes the utilization of the gas extracted by the vacuum pump, avoids energy waste, and makes the entire reflow soldering furnace system more energy-saving and environmentally friendly.

[0015] Optionally, barrier assemblies are provided at both opposite ends of the welding zone, and the barrier assemblies include a barrier plate arranged on the inner wall of the furnace body, a through groove is opened on the barrier plate, a cylinder is arranged in the through groove, the output shaft of the cylinder is fixedly connected to a baffle, and the outer surface of the baffle is in close contact with the inner wall of the furnace body.

[0016] By adopting the above technical solution, the barrier components set at both ends of the welding area can effectively divide the welding area and other areas, reduce and prevent the gas and heat in the welding area from diffusing outward, thereby effectively ensuring the stability of the temperature in the welding area and improving the welding quality. At the same time, the setting of the cylinder and the baffle can flexibly adjust the blocking degree of the baffle according to the transportation process of the material. When the material is about to pass through the baffle, the cylinder controls the baffle to move upward to the inside of the through groove to ensure the smooth progress of the material transportation process.

[0017] Optionally, the baffle is provided with a groove on the surface facing the conveyor belt, a sealing strip is provided on the inner wall of the groove, an inflation cavity is provided in the sealing strip, and an air supply pipe corresponding to the two sealing strips is connected to the air collecting box, and each air supply pipe is provided with a second solenoid valve. The sealing strip is made of elastic material, and when the sealing strip is inflated, the sealing strip abuts against the surface of the conveyor belt.

[0018] By adopting the above technical solution, when the material is welded in the welding area, the second solenoid valve is started, and the gas in the gas collecting box moves to the inflation chamber through the air supply pipe. When the sealing strip is inflated and tightly abuts against the surface of the conveyor belt, the second solenoid valve is closed. This arrangement further improves the sealing effect of the barrier component, prevents the gas in the welding area from leaking from the gap between the conveyor belt and the barrier component, further strengthens the sealing of the welding area, and further realizes the utilization of the gas extracted by the vacuum pump, avoids energy waste, and makes the entire reflow oven system more energy-saving and environmentally friendly.

[0019] Optionally, a filter plate is provided in the air collecting box.

[0020] By adopting the above technical solution, the gas extracted by the vacuum pump is filtered by setting a filter plate, which effectively prevents impurities from entering the subsequent inflation system, avoids impurities from clogging or damaging the inflation system, ensures the smooth progress of the inflation process, and further ensures the reliability of the entire temperature regulation and sealing system.

[0021] In summary, the present application includes at least one of the following beneficial technical effects: 1. The present application sets a gas extraction and exhaust assembly, which realizes the timely discharge of gas in the welding area, reduces the possibility of gas residue and formation of voids, thereby improving the mechanical strength of the weld and improving the welding quality; 2. The present application sets a windshield, a mixed temperature zone, a fixed component and a winding component. When multiple temperature sensors detect that the temperature distribution in the mixed temperature zone is in an uneven state, the fixed component fixes the windshield so that the windshield covers multiple air inlets, thereby preventing nitrogen with uneven temperature distribution in the mixed temperature zone from entering the interior of the enclosure. When the temperature sensor detects that the temperature distribution in the mixed temperature zone is uniform, the fixed component cancels the fixing effect on the windshield, and the winding component drives the windshield to wind up, so that multiple air inlets are opened, and nitrogen with uniform temperature enters the interior of the enclosure, so that the solder paste can be heated more evenly and volatilized evenly during the melting process, avoiding local overheating of the solder paste and causing a large amount of gasification to produce voids. At the same time, the uniformity of solder paste flow is improved, and the space for gas residue is reduced, thereby reducing the probability of void generation and further improving welding quality. 3. In the present application, a rubber bellows, an air filling chamber, an air charging and discharging assembly and an air supply pipe are provided. A part of the exhaust gas collected by the vacuum pump enters the rubber bellows through the air filling and discharging assembly, thereby realizing the recycling of the windshield cloth, and another part of the exhaust gas enters the air filling chamber through the air supply pipe to realize the inflation and expansion of the sealing strip, thereby further improving the sealing effect of the barrier assembly, preventing the gas in the welding zone from leaking from the gap between the conveyor belt and the barrier assembly, and further strengthening the sealing of the welding zone. Such a setting realizes the utilization of exhaust gas, avoids the waste of energy, and makes the entire reflow oven system more energy-saving and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of this application.

[0023] Figure 2 It is a cross-sectional view of the furnace body in the embodiment of the present application.

[0024] Figure 3 It is a cross-sectional view of the welding area in the embodiment of the present application.

[0025] Figure 4 It is a schematic diagram of the structure of the enclosure and the windshield cloth in the embodiment of the present application.

[0026] Figure 5yes Figure 4 Enlarged view of point A in the middle.

[0027] Figure 6 It is a schematic diagram of the structure of the air collecting box, the air charging pipe and the air delivery pipe in the embodiment of the present application.

[0028] Explanation of reference numerals: 01, furnace body; 02, conveyor belt; 1, preheating zone; 2, welding zone; 3, cooling zone; 4, heating assembly; 41, nitrogen tank; 42, nitrogen pipeline; 5, barrier assembly; 51, barrier plate; 511, through groove; 52, cylinder; 53, baffle; 6, enclosure; 7, exhaust assembly; 71, vacuum pump; 72, main gas pipe; 73, gas distribution pipe; 74, suction pipe; 75, suction nozzle; 8, mixed temperature zone; 61, air inlet; 81, temperature sensor; 9 , windshield cloth; 10, fixing assembly; 11, winding assembly; 111, winding roller; 112, connecting rod; 113, sliding frame; 114, coil spring; 101, electromagnetic block; 102, magnetic block; 12, rubber bellows; 13, charging and discharging assembly; 131, air collecting box; 132, charging pipe; 133, first solenoid valve; 134, pressure relief valve; 14, filter plate; 531, groove; 54, sealing strip; 541, sealing chamber; 15, air supply pipe; 151, second solenoid valve. DETAILED DESCRIPTION

[0029] The following is combined with Figure 1-6 This application is described in further detail.

[0030] The embodiment of the present application discloses an SMT reflow oven.

[0031] Reference Figure 1 and Figure 2 An SMT reflow oven includes a furnace body 01, wherein a preheating zone 1, a welding zone 2 and a cooling zone 3 are arranged inside the furnace body 01, an inlet end (not shown in the figure) and an outlet end (not shown in the figure) are respectively opened at opposite ends of the furnace body 01, and a conveyor belt 02 extending from the inlet end to the outlet end is fixedly installed in the furnace body 01, and the conveyor belt 02 is used to transport materials to be welded, so as to pass the materials to be welded from the inlet end through the preheating zone 1, the welding zone 2 and the cooling zone 3 in sequence, and then transport them out of the furnace body 01 from the outlet end after the reflow welding process is completed.

[0032] Reference Figure 1 and Figure 2 A preheating component (not shown in the figure) for adjusting the temperature of the preheating zone 1 to the preheating temperature is provided in the preheating zone 1. In this embodiment, the preheating component can heat the preheating zone 1 by heating the air with an electric heating tube. Heating the air temperature of the preheating zone 1 with an electric heating tube is a prior art and will not be described in detail here. A heating assembly 4 is provided in the welding area 2. The heating assembly 4 includes a nitrogen tank 41 provided on the ground. The nitrogen tank 41 is filled with nitrogen. A nitrogen pipeline 42 connected to the inside of the welding area 2 is installed on the nitrogen tank 41. A heating wire (not shown in the figure) for increasing the temperature of the nitrogen is installed in the nitrogen pipeline 42. Nitrogen is an inert gas. Heating with nitrogen in the welding area 2 can effectively discharge the oxygen in the welding area 2, forming a relatively oxygen-free environment, thereby effectively reducing the possibility of oxygen-oxidized solder paste forming an oxide layer that affects the welding quality, thereby effectively improving the welding quality; A cooling assembly (not shown in the figure) is provided in the cooling zone 3. In the present embodiment, the cooling assembly adopts air cooling. The method of cooling and solidifying the molten solder paste by air cooling is a prior art and will not be described in detail here.

[0033] Reference Figure 1 and Figure 2 , barrier components 5 are provided at both opposite ends of the welding area 2, and the barrier components 5 include barrier plates 51 fixedly connected to the inner wall of the furnace body 01, the barrier plates 51 are vertically arranged, and each barrier plate 51 is provided with a through slot 511, and a cylinder 52 is fixedly connected to the inner top wall of each through slot 511, and a baffle 53 is fixedly connected to the output shaft of each cylinder 52, and the outer surface of the baffle 53 is in close contact with the inner wall of the furnace body 01.

[0034] When the material is about to move from the preheating zone 1 to the welding zone 2, the cylinder 52 near the entrance end is started, and the cylinder 52 drives the baffle 53 to move toward the inside of the through groove 511, and a gap is formed between the bottom surface of the baffle 53 and the surface of the conveyor belt 02, and the material enters the welding zone 2 through the gap, and then the cylinder 52 near the entrance end drives the baffle 53 to contact the surface of the conveyor belt 02 again; When the material is about to move from the welding zone 2 to the cooling zone 3, the cylinder 52 near the outlet end is started, and the cylinder 52 drives the baffle 53 to move toward the inside of the through groove 511. A gap is formed between the bottom surface of the baffle 53 and the surface of the conveyor belt 02, and the material enters the cooling zone 3 through the gap. Then, the cylinder 52 near the outlet end drives the baffle 53 to abut against the surface of the conveyor belt 02 again. The barrier components 5 set at both ends of the welding zone 2 can effectively divide the welding zone 2 and other areas, reduce and prevent the gas and heat in the welding zone 2 from diffusing outward, thereby effectively ensuring the stability of the temperature of the welding zone 2 and further improving the welding quality.

[0035] Reference Figure 2 and Figure 3A panel 6 is provided in the welding area 2, the panel 6 is fixedly connected to the inside of the furnace body 01 and the furnace body 01 is covered on the outer surface of the panel 6, the panel 6 is covered above the conveying area of ​​the conveyor belt 02, a vacuum assembly 7 is provided in the furnace body 01, the vacuum assembly 7 includes a vacuum pump 71 fixedly connected to the furnace body 01 through a mounting plate (not shown in the figure), the vacuum pump 71 is connected to the exhaust end thereof with a main gas pipe 72, the main gas pipe 72 extends toward the bottom surface of the furnace body 01, the main gas pipe 72 is connected to two gas distribution pipes 73, the length of the two gas distribution pipes 73 is The degree direction is perpendicular to the length direction of the main air pipe 72, and the two branch air pipes 73 extend to the inner side walls opposite to the enclosure 6 respectively. Each branch air pipe 73 is connected to a plurality of suction pipes 74. In the present embodiment, there are two suction pipes 74, and the length direction of the suction pipes 74 is parallel to the length direction of the welding area 2. Each suction pipe 74 is connected to and installed with a plurality of suction nozzles 75. The plurality of suction nozzles 75 are evenly distributed along the length direction of the suction pipes 74, and the suction direction of each suction nozzle 75 is set toward the surface of the material.

[0036] When the material passes through the welding area 2, the vacuum pump 71 is started, and the vacuum pump 71 forms a negative pressure environment in the main air pipe 72, the air distribution pipe 73 and the suction pipe 74. The gas generated by the melting of the solder paste in the welding area 2 enters the suction pipe 74 through multiple suction nozzles 75 under the action of the pressure difference. The gas absorbed in the suction pipe 74 is gathered into the main air pipe 72 through the air distribution pipe 73, and is finally discharged by the vacuum pump 71. The setting of the exhaust component 7 realizes the timely discharge of the gas in the welding area 2, reduces the possibility of forming voids due to gas residue, thereby improving the mechanical strength of the solder joint and improving the welding quality.

[0037] Reference Figure 2 and Figure 3 A mixing temperature zone 8 is formed between the outer surface of the enclosure 6 and the inner surface of the furnace body 01. A plurality of air inlets 61 connected to the mixing temperature zone 8 are opened on the top wall of the enclosure 6. A plurality of temperature sensors 81 are fixedly connected to the inner top wall of the mixing temperature zone 8. The plurality of temperature sensors 81 are evenly arranged in an array on the inner top wall of the furnace body 01. The plurality of temperature sensors 81 are used to detect the temperature uniformity in the mixing temperature zone 8. Detecting the temperature uniformity in the mixing temperature zone 8 by using a plurality of temperature sensors 81 belongs to the prior art and will not be repeated here. A windshield cloth 9 is arranged on the top wall of the enclosure 6. When the temperature distribution in the mixing temperature zone 8 is uneven, the windshield cloth 9 covers the plurality of air inlets 61. A fixing component 10 for fixing the windshield cloth 9 for unfolding and loading and a winding component 11 for winding the windshield cloth 9 are provided on the enclosure 6.

[0038] Reference Figure 2 , Figure 3 and Figure 4The winding assembly 11 includes a winding roller 111 which is rotatably connected to the outer surface of the enclosure 6 through an ear plate, the length direction of the winding roller 111 is parallel to the length direction of the mixing temperature zone 8, the windshield cloth 9 is arranged on the outer surface of the winding roller 111, one end of the windshield cloth 9 is fixedly connected to the winding roller 111, and the other end is fixedly connected to a connecting rod 112, and the opposite sides of the enclosure 6 are fixedly connected with sliding frames 113 which slide with the connecting rod 112, and the length directions of the two sliding frames 113 are perpendicular to the length direction of the winding roller 111, and a coil spring 114 is fixedly connected to the end surface of the windshield cloth 9 parallel to the length direction, and one end of the coil spring 114 is fixedly connected to the take-up roller. When the coil spring 114 is in a natural state, the windshield cloth 9 is wound on the take-up roller.

[0039] Reference Figure 3 , Figure 4 and Figure 5 The fixed component 10 includes an electromagnetic block 101 and a magnetic block 102. The electromagnetic block 101 is fixedly connected to the inner wall of the sliding frame 113 away from the winding roller 111. The magnetic block 102 is fixedly connected to the surface of the connecting rod 112 facing the electromagnetic block 101. The temperature sensor 81 is electrically connected to the electromagnetic block 101 through the control system. When the electromagnetic block 101 is powered on, the electromagnetic block 101 attracts the magnetic block 102.

[0040] The heated nitrogen directly enters the temperature mixing zone 8 through the nitrogen pipeline 42. When the multiple temperature sensors 81 detect that the temperature distribution in the temperature mixing zone 8 is in an uneven state, the electromagnetic block 101 is in a powered-on state, the electromagnetic block 101 attracts the magnetic block 102, and the connecting rod 112 is fixed by the electromagnetic block 101 to the end of the sliding frame 113 away from the winding roller 111. At this time, the windshield cloth 9 is unfolded on the surface of the enclosure 6, and the coil spring 114 is in a flat state, so that the multiple air inlets are covered by the windshield cloth 9, blocking the flow path of the nitrogen in the temperature mixing zone 8, prolonging the mixing time of the nitrogen in the temperature mixing zone 8, and preventing the nitrogen with uneven temperature distribution in the temperature mixing zone 8 from entering the enclosure 6, thereby ensuring the uniformity of the temperature distribution inside the enclosure 6; When the nitrogen is mixed in the mixing zone 8 until the temperature distribution is uniform, the temperature sensor 81 controls the electromagnetic block 101 to cut off the power, and the adsorption effect of the electromagnetic block 101 on the magnetic block 102 disappears. At this time, the tension on the coil spring 114 disappears, and the coil spring 114 automatically reels under the action of the elastic force. The retraction of the coil spring 114 drives the windshield cloth 9 to reel on the reeling roller 111, so that multiple air inlets are opened, and nitrogen with uniform temperature enters the interior of the enclosure 6, so that the solder paste can be heated more evenly and volatilized evenly during the melting process, avoiding local overheating of the solder paste and causing a large amount of gasification to produce voids. At the same time, the uniformity of the solder paste flow is improved, and the space for gas residue is reduced, thereby reducing the probability of void generation and further improving the welding quality.

[0041] Reference Figure 4 , Figure 5and Figure 6 In order to realize the recycling of the windshield cloth 9, a rubber bellows 12 is fixedly connected to the side wall of each sliding frame 113 away from the electromagnetic block 101. The length direction of the rubber bellows 12 is parallel to the length direction of the sliding frame 113. When the windshield cloth 9 is rolled up on the winding roller 111, the end face of the rubber bellows 12 abuts against the surface of the connecting rod 112, and an air charging and discharging component 13 for charging and discharging air into the rubber bellows 12 is provided on the furnace body 01.

[0042] Reference Figure 4 , Figure 5 and Figure 6 The gas charging and discharging assembly 13 includes an air collecting box 131 connected to the air outlet end of the vacuum pump 71, the air collecting box 131 is fixedly installed on the top of the furnace body 01, and the air collecting box 131 is connected to an air charging pipe 132 corresponding to the two rubber bellows 12 one by one. The air charging pipe 132 is connected to the corresponding rubber bellows 12, and a first solenoid valve 133 is fixedly installed on each air charging pipe 132. The temperature sensor 81 is electrically connected to the first solenoid valve 133 through the control system, and a pressure relief valve 134 is fixedly installed on the top of the air collecting box 131.

[0043] Reference Figure 3 In order to avoid damage to the rubber bellows 12 caused by impurities in the gas in the air collecting box 131 and ensure the smooth charging and discharging process of the rubber bellows 12, a filter plate 14 is fixedly installed inside the air collecting box 131, and the connecting ends of the charging pipe 132 and the vacuum pump 71 with the air collecting box 131 are respectively arranged on both sides of the filter plate 14.

[0044] The gas extracted by the vacuum pump 71 finally enters the gas collecting box 131 along the main gas pipe 72, and the solid impurities in the gas are filtered through the filter plate 14. When the temperature sensor 81 detects that the temperature distribution in the temperature mixing zone 8 is uneven, the temperature sensor 81 controls the first solenoid valve 133 to start through the control system, and the gas in the gas collecting box 131 moves to the rubber bellows 12 through the inflation pipe 132. The rubber bellows 12 is inflated and pushes the connecting rod 112 to move toward the direction of the electromagnetic block 101. When the magnetic block 102 moves to the vicinity of the electromagnetic block 101, the electromagnetic block 101 The magnetic block 102 is adsorbed, and the connecting rod 112 is fixed by the electromagnetic block 101 and the magnetic block 102 at the end of the sliding frame 113 away from the winding roller 111, thereby realizing the unfolding of the windshield cloth 9. After the windshield cloth 9 is unfolded, the pressure relief valve 134 is started, and the pressure in the air collecting box 131 becomes smaller, and the gas in the rubber bellows 12 flows into the air collecting box 131. When the windshield cloth 9 needs to be rolled up, the connecting rod 112 pushes the rubber bellows 12 to reset. Such a setting realizes the utilization of the gas extracted by the vacuum pump 71, avoids the waste of energy, and makes the entire reflow oven system more energy-saving and environmentally friendly.

[0045] Reference Figure 2 and Figure 6 A groove 531 is provided on the surface of each baffle 53 facing the conveyor belt 02, and the width of the groove 531 is greater than the width of the conveyor belt 02. A sealing strip 54 is fixedly connected to the inner wall of each groove 531, and an inflation cavity is provided in each sealing strip 54. An air supply pipe 15 corresponding to the two sealing strips 54 is connected to the air collecting box 131, and a second solenoid valve 151 is fixedly installed on each air supply pipe 15. The sealing strip 54 is made of elastic material. When the sealing strip 54 is inflated, the sealing strip 54 abuts against the surface of the conveyor belt 02.

[0046] When the material is welded in the welding area 2, the second solenoid valve 151 is started, and the gas in the gas collecting box 131 moves to the inflation chamber through the air supply pipe 15. When the sealing strip 54 is inflated and tightly abuts against the surface of the conveyor belt 02, the second solenoid valve 151 is closed. This arrangement further improves the sealing effect of the barrier component 5, prevents the gas in the welding area 2 from leaking from the gap between the conveyor belt 02 and the barrier component 5, further strengthens the sealing of the welding area 2, and further realizes the utilization of the gas extracted by the vacuum pump 71, avoids energy waste, and makes the entire reflow oven system more energy-saving and environmentally friendly.

[0047] The implementation principle of an SMT reflow oven in the embodiment of the present application is as follows: when the material is about to move from the preheating zone 1 to the welding zone 2, the cylinder 52 near the entrance end is started, and the cylinder 52 drives the baffle 53 to move toward the inside of the through slot 511, and a gap is formed between the bottom surface of the baffle 53 and the surface of the conveyor belt 02, and the material enters the welding zone 2 through the gap, and then the cylinder 52 near the entrance end drives the baffle 53 to abut against the surface of the conveyor belt 02 again; When the material passes through the welding area 2, the vacuum pump 71 is started, and the vacuum pump 71 forms a negative pressure environment in the main gas pipe 72, the gas distribution pipe 73 and the suction pipe 74. The gas generated by the melting of the solder paste in the welding area 2 enters the suction pipe 74 through multiple suction nozzles 75 under the action of the pressure difference. The gas absorbed in the suction pipe 74 is gathered into the main gas pipe 72 through the gas distribution pipe 73, and is finally discharged by the vacuum pump 71. The setting of the exhaust component 7 realizes the timely discharge of the gas in the welding area 2, reduces the possibility of forming voids due to gas residue, thereby improving the mechanical strength of the solder joint and improving the welding quality; After welding is completed, the cylinder 52 near the outlet end is started, and the cylinder 52 drives the baffle 53 to move toward the inside of the through groove 511. A gap is formed between the bottom surface of the baffle 53 and the surface of the conveyor belt 02. The material enters the cooling zone 3 through the gap. Then, the cylinder 52 near the outlet end drives the baffle 53 to contact the surface of the conveyor belt 02 again. After the cooling in the cooling zone 3 is completed, the conveyor belt 02 transports the material to the outlet end.

[0048] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. An SMT reflow oven, comprising a oven body (01), wherein the oven body (01) is provided with a preheating zone (1), a welding zone (2) and a cooling zone (3), wherein the oven body (01) is provided with a conveyor belt (02) for conveying materials to be processed, wherein: The furnace body (01) is provided with a heating component (4) for heating the welding area (2); a panel (6) is provided in the welding area (2); the furnace body (01) is covered on the outer surface of the panel (6); a gas extraction component (7) is provided in the furnace body (01); the gas extraction component (7) comprises a vacuum pump (71) provided on the furnace body (01); a main gas pipe (72) is provided at the gas extraction end of the vacuum pump (71); two gas distribution pipes (73) are provided in communication with the main gas pipe (72). The two air distribution pipes (73) are respectively arranged inside the inner side walls opposite to each other of the enclosure (6); each of the air distribution pipes (73) is connected to a plurality of air suction pipes (74); the length direction of the air suction pipes (74) is parallel to the length direction of the welding area (2); the air suction pipes (74) are connected to a plurality of air suction nozzles (75); the plurality of air suction nozzles (75) are evenly distributed at equal distances along the length direction of the air suction pipes (74); and the air suction direction of the air suction nozzles (75) is arranged toward the surface of the material.

2. The SMT reflow oven according to claim 1, characterized in that: The heating assembly (4) comprises a nitrogen tank (41), the nitrogen tank (41) is provided with a nitrogen pipeline (42) connected to the welding area (2), a heating wire is provided in the nitrogen pipeline (42), the outer surface of the enclosure (6) and the inner wall of the welding area (2) are enclosed to form a mixed temperature area (8), the top wall of the enclosure (6) is provided with a plurality of air inlets (61) connected to the mixed temperature area (8), the enclosure (6) is provided with a windshield (9), and the enclosure (6) is provided with a heating wire. There are a fixing component (10) and a winding component (11); a plurality of temperature sensors (81) for detecting the uniformity of temperature distribution in the mixing temperature zone (8) are arranged on the inner wall of the mixing temperature zone (8); when the temperature distribution in the mixing temperature zone (8) is uneven, the fixing component (10) unfolds the windshield cloth (9), and the windshield cloth (9) covers the plurality of air inlets (61); when the temperature distribution in the mixing temperature zone (8) is uniform, the winding component (11) winds up the windshield cloth (9).

3. The SMT reflow oven according to claim 2, characterized in that: The winding assembly (11) comprises a winding roller (111) rotatably connected to one side of the enclosure (6); the windshield cloth (9) is arranged around the outer peripheral surface of the winding roller (111); one end of the windshield cloth (9) is arranged on the winding roller (111); and the other end is provided with a connecting rod (112); sliding frames (113) slidably matched with the connecting rod (112) are provided on opposite sides of the enclosure (6); a coil spring (114) is provided on the windshield cloth (9); One end of the coil spring (114) is arranged on the take-up roller. When the coil spring (114) is in a natural state, the windshield cloth (9) is wound on the take-up roller. An electromagnetic block (101) is arranged on one end of the two sliding frames (113) away from the take-up roller (111). A magnetic block (102) magnetically connected to the electromagnetic block (101) is arranged on the connecting rod (112). The temperature sensor (81) is electrically connected to the electromagnetic block (101) through a control system.

4. The SMT reflow oven according to claim 3, characterized in that: A rubber bellows (12) is arranged in each of the sliding frames (113), the length direction of the rubber bellows (12) is parallel to the length direction of the sliding frame (113), the end face of the rubber bellows (12) abuts against the surface of the connecting rod (112), and the furnace body (01) is provided with an air charging and discharging component (13) for charging and discharging air into the rubber bellows (12).

5. The SMT reflow oven according to claim 4, characterized in that: The inflation and deflation assembly (13) comprises an air collecting box (131) connected to the air outlet end of the vacuum pump (71); the air collecting box (131) is connected to an inflation tube (132) corresponding to the two rubber bellows (12) one by one; the inflation tube (132) is connected to the corresponding rubber bellows (12); each inflation tube (132) is provided with a first solenoid valve (133); the temperature sensor (81) is electrically connected to the first solenoid valve (133) through a control system; and the air collecting box (131) is provided with a pressure relief valve (134).

6. The SMT reflow oven according to claim 1, characterized in that: The welding zone (2) is provided with a barrier assembly (5) at both opposite ends, and the barrier assembly (5) comprises a barrier plate (51) arranged on the inner wall of the furnace body (01), and a through groove (511) is provided on the barrier plate (51), and a cylinder (52) is arranged in the through groove (511), and the output shaft of the cylinder (52) is fixedly connected with a baffle plate (53), and the outer surface of the baffle plate (53) is in close contact with the inner wall of the furnace body (01).

7. The SMT reflow oven according to claim 6, characterized in that: The baffle (53) is provided with a groove (531) on the surface facing the conveyor belt (02), and a sealing strip (54) is provided on the inner wall of the groove (531). An inflation cavity is provided in the sealing strip (54). An air supply pipe (15) corresponding to the two sealing strips (54) is connected to the air collecting box (131), and each air supply pipe (15) is provided with a second solenoid valve (151). The sealing strip (54) is made of elastic material. When the sealing strip (54) is inflated, the sealing strip (54) abuts against the surface of the conveyor belt (02).

8. The SMT reflow oven according to claim 5, characterized in that: A filter plate (14) is arranged in the air collecting box (131).

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