Oxygen concentration adjusting mechanism and vacuum furnace

Abstract

The utility model discloses an oxygen concentration regulating mechanism and a vacuum furnace, the oxygen concentration regulating mechanism is arranged at two openings of a hearth of the vacuum furnace along the length direction, the oxygen concentration regulating mechanism comprises a shell, the shell is limited to form a cavity, the shell is provided with an inlet and an outlet along the length direction of the hearth, and the inlet and the outlet are communicated with the cavity. A cavity is formed in the shell, a check curtain assembly is arranged in the cavity, an air exhaust hole communicated with the cavity is formed in a bottom plate of the shell, the air exhaust hole is communicated with an air exhaust pipe, and the air exhaust pipe is connected with an exhaust fan outside the shell. The device controls the pressure difference between the two sides of the hearth of the vacuum furnace, oxygen in the oxygen concentration adjusting mechanisms on the two sides of the hearth is rapidly exhausted through the exhaust pipe after the door is opened and closed every time, fluctuation of the oxygen concentration can be controlled easily, and the influence of opening and closing the door on rising of the oxygen concentration of atmosphere gas in the hearth is reduced; the oxygen concentration is easier to control, so that the total nitrogen flow is saved under the same condition.

Description

Technical Field

[0001] This utility model relates to the field of vacuum furnace technology, and in particular to an oxygen concentration regulating mechanism and a vacuum furnace. Background Technology

[0002] Vacuum furnaces are primarily used for soldering circuit boards with pre-mounted electronic components. The furnace chamber includes heating and cooling zones. The heating zone melts solder paste, fusing the electronic components to the circuit board pads. The cooling zone then cools the solder paste, solidifying the components to the pads. A common method for controlling the oxygen concentration in the vacuum furnace chamber is to introduce nitrogen gas to purge the air from the chamber. This method, by varying the nitrogen flow rate in different areas of the furnace chamber, creates a pressure difference between the different temperature zones, resulting in lateral airflows at the furnace inlet and outlet, thus reducing the oxygen concentration more quickly. However, when the openings at both ends of the vacuum furnace are opened to allow a carrier to enter, excessive air can enter from the outside, leading to excessive oxygen levels in the furnace chamber and affecting its operation. Utility Model Content

[0003] To overcome the above-mentioned shortcomings, the purpose of this utility model is to provide an oxygen concentration regulating mechanism and a vacuum furnace, which controls the pressure difference on both sides of the vacuum furnace chamber and quickly discharges the oxygen in the oxygen concentration regulating mechanism on both sides of the furnace chamber after each door opening and closing. This helps to control the fluctuation of oxygen concentration, reduce the impact of door opening and closing on the increase of oxygen concentration in the atmosphere gas inside the furnace chamber, and save the total nitrogen flow rate under the same conditions by making it easier to control the oxygen concentration.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is as follows: an oxygen concentration regulating mechanism is provided at two openings along the length of the furnace chamber of a vacuum furnace. The oxygen concentration regulating mechanism includes a housing, which defines a cavity. The housing has an inlet and an outlet along the length of the furnace chamber. A curtain assembly is provided inside the cavity. An exhaust hole communicating with the cavity is provided on the bottom plate of the housing. The exhaust hole is connected to an exhaust pipe, which is connected to an exhaust fan outside the housing.

[0005] The beneficial effects of this utility model are as follows:

[0006] When the inlet and outlet are opened, a large amount of air enters the cavity. Through the air extraction hole, air extraction pipe and exhaust fan, the gas containing a large amount of oxygen in the cavity is quickly extracted, which helps to control the fluctuation of oxygen concentration and reduce the impact of opening and closing the door on the increase of oxygen concentration in the furnace atmosphere. This makes it easier to control the oxygen concentration and thus saves the total nitrogen flow under the same conditions.

[0007] The power provided by the exhaust fan allows the atmospheric gas inside the furnace to break through the baffle assembly, achieving unidirectional flow of gas inside the furnace.

[0008] Furthermore, the curtain assembly and the inlet are spaced apart along the length of the furnace chamber, and an exhaust chamber is formed between the curtain assembly and the end plate of the housing with the inlet. The exhaust hole is located on the bottom plate at a position corresponding to the exhaust chamber.

[0009] The exhaust chamber allows for the accumulation and buffering of gas. Due to the obstruction of the curtain assembly, when the inlet is opened, the outside air first accumulates in the exhaust chamber. Therefore, by setting the exhaust port in the exhaust chamber, oxygen can be quickly extracted from it, preventing oxygen from entering the furnace through the curtain assembly.

[0010] Furthermore, an air distribution plate is fixed inside the exhaust chamber, located below the inlet, and has multiple ventilation holes arranged in an array on it. The air distribution plate allows the gas to be extracted evenly and quickly.

[0011] Furthermore, the diameter of the ventilation opening gradually increases from the side closer to the inlet to the side farther away from the inlet. When the inlet is open, the oxygen concentration in the exhaust chamber is higher near the inlet; therefore, setting the diameter of the ventilation opening at this point is larger facilitates the rapid extraction of oxygen and prevents it from escaping towards the outlet. Simultaneously, the diameter of the ventilation opening near the outlet is smaller, allowing for the extraction of less nitrogen overflowing from the furnace.

[0012] Furthermore, an oxygen sensor is installed inside the exhaust chamber, and the oxygen sensor is connected to the exhaust fan, which is a variable frequency fan. The oxygen sensor is used to detect the oxygen content in the exhaust chamber, and the exhaust fan can change the exhaust intensity. When the oxygen sensor detects that the oxygen content is too high, the exhaust fan switches to a higher exhaust intensity setting.

[0013] Furthermore, the baffle assembly includes a horizontal plate and a vertical plate. The horizontal plate is fixed above the vertical plate and located below the inlet. Multiple lower baffles are fixed on the horizontal plate at intervals along the length of the furnace, and each lower baffle corresponds to an upper baffle.

[0014] Furthermore, the lower end of the upper curtain fits into the side of the corresponding lower baffle, and a notch is provided on the upper curtain along the vertical direction.

[0015] Furthermore, a switch door is provided at the entrance, which can move up and down under the drive of a drive device to close or open the entrance.

[0016] Furthermore, the housing has an air inlet near the outlet, which is used to introduce nitrogen into the cavity. When the nitrogen content in the cavity or furnace is insufficient, nitrogen can be added to the cavity through the air inlet. Since the air inlet is located near the outlet, the nitrogen can quickly dissipate into the furnace. Simultaneously, because the nitrogen is introduced towards the outlet, when the exhaust fan is operating, the nitrogen will move towards the inlet, reducing the entry of external oxygen.

[0017] This utility model also discloses a vacuum furnace that uses the above-mentioned oxygen concentration regulating mechanism. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the vacuum furnace in an embodiment of this utility model;

[0019] Figure 2 This is a schematic diagram of the oxygen concentration regulating mechanism in an embodiment of the present invention;

[0020] Figure 3 This is a cross-sectional view of the oxygen concentration regulating mechanism in an embodiment of this utility model.

[0021] In the picture:

[0022] 100. Oxygen concentration regulating mechanism; 200. Vacuum furnace;

[0023] 1. Shell; 11. Inlet; 12. Outlet; 13. Exhaust port; 11a. Exhaust chamber;

[0024] 2. Curtain assembly; 21. Horizontal panel; 22. Vertical panel; 23. Lower baffle; 24. Upper curtain;

[0025] 3. Exhaust pipe; 31. Exhaust fan;

[0026] 4. Air distribution plate; 41. Ventilation holes;

[0027] 51. Drive mechanism; 52. Door opening and closing mechanism;

[0028] 6. Air intake. Detailed Implementation

[0029] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the scope of protection of the present invention.

[0030] In the description of this application, the arrow X in all the figures points in the length direction, the arrow Y points in the width direction, and the arrow Z points in the vertical direction.

[0031] See appendix Figure 1As shown, an oxygen concentration regulating mechanism 100 of this utility model is installed at two openings along the length of the furnace chamber of a vacuum furnace 200. The two oxygen concentration regulating mechanisms 100 are symmetrically arranged. The oxygen concentration regulating mechanism 100 is used to discharge oxygen from areas with high oxygen content to prevent oxygen from entering the furnace chamber.

[0032] The fixture enters and exits the furnace through an opening, which allows air to pass through. This allows oxygen-rich air to enter the furnace, increasing the oxygen concentration and affecting processing quality. In existing technologies, nitrogen flow rates in different furnace zones are typically adjusted to create pressure differences between them, thus generating transverse airflows towards the furnace openings to more quickly reduce oxygen concentration and establish a pressure difference. However, this method of driving gas flow through pressure difference is complex and difficult to adjust in practice. Therefore, this embodiment includes an oxygen concentration regulating mechanism 100, which extracts oxygen from the opening and provides the necessary force for nitrogen to flow towards it, preventing oxygen from entering the furnace.

[0033] See appendix Figure 3 As shown, the oxygen concentration regulating mechanism 100 includes a housing 1. The housing 1 includes two end plates spaced apart along the X direction, a top plate and a bottom plate spaced apart along the Z direction, and two side plates spaced apart along the Y direction. The housing 1 defines a cavity. The housing 1 has an inlet 11 and an outlet 12 along the length of the furnace chamber. The outlet 12 is connected to the opening. The product enters or leaves the cavity through the inlet 11 and enters or leaves the furnace chamber through the outlet 12. A baffle assembly 2 is provided in the cavity to reduce gas overflow from the furnace chamber. An exhaust port 13 communicating with the cavity is provided on the bottom plate of the housing 1. The exhaust port 13 is connected to an exhaust pipe 3, which is connected to an exhaust fan 31 outside the housing 1.

[0034] When inlet 11 and outlet 12 are opened, a large amount of air enters the cavity. Through the vent 13, vent pipe 3, and exhaust fan 31, the oxygen-rich gas inside the cavity is rapidly extracted. The direction of oxygen flow is shown in the appendix. Figure 2 As indicated by the hollow arrow, this helps control fluctuations in oxygen concentration and reduces the impact of opening and closing door 52 on the increase in oxygen concentration in the furnace atmosphere. This allows for easier control of oxygen concentration, thus saving total nitrogen flow under the same conditions. Simultaneously, the power provided by the exhaust fan 31 allows the atmosphere in the furnace to break through the baffle assembly 2, achieving unidirectional gas flow within the furnace. The flow direction of the gas in the furnace at this time is shown in the attached diagram. Figure 2 As shown by the solid arrow in the diagram, the same gas as the furnace gas is formed inside the cavity, achieving unidirectional gas flow and preventing outside air with high oxygen content from entering the furnace.

[0035] A gap is left between the curtain assembly 2 and the inlet 11 along the length of the furnace. An exhaust chamber 11a is formed between the curtain assembly 2 and the end plate of the housing 1 with the inlet 11 or outlet 12. The exhaust port 13 is located on the bottom plate at a position corresponding to the exhaust chamber 11a. The exhaust chamber 11a allows for gas accumulation and buffering. Because of the obstruction of the curtain assembly 2, when the inlet 11 is opened, external air first accumulates in the exhaust chamber 11a. Therefore, placing the exhaust port 13 in the exhaust chamber 11a allows for rapid extraction of oxygen, preventing oxygen from entering the furnace through the curtain assembly 2.

[0036] In one embodiment, a uniform air distribution plate 4 is also fixed inside the exhaust chamber 11a. The uniform air distribution plate 4 is located below the inlet 11, and multiple ventilation holes 41 are arrayed on the uniform air distribution plate 4. The uniform air distribution plate 4 divides the exhaust chamber 11a into an upper chamber and a lower chamber. The inlet 11 is directly connected to the upper chamber, and the exhaust port 13 is directly connected to the lower chamber. The upper and lower chambers are connected through the ventilation holes 41. The uniform air distribution plate 4 allows the gas in the upper chamber to enter the lower chamber evenly and quickly and be extracted.

[0037] In one embodiment, the diameter of the vent 41 gradually increases from the side closer to the inlet 11 to the side farther away from the inlet 11. When the inlet 11 is open, the oxygen concentration in the exhaust chamber 11a is higher near the inlet 11. Therefore, the diameter of the vent 41 at this location is set to be larger to facilitate the rapid extraction of oxygen and prevent oxygen from escaping towards the outlet 12. At the same time, the diameter of the vent 41 near the outlet 12 is smaller, which can extract less nitrogen overflowing from the furnace.

[0038] In one embodiment, an oxygen sensor is installed inside the exhaust chamber 11a, and the oxygen sensor is connected to the exhaust fan 31, which is a variable frequency fan. The oxygen sensor is used to detect the oxygen content inside the exhaust chamber 11a, and the exhaust fan 31 can change the exhaust intensity. When the oxygen sensor detects that the oxygen content is too high, the exhaust fan 31 switches to a higher exhaust intensity setting.

[0039] The housing 1 has an air inlet 6 located near the outlet 12, which is used to introduce nitrogen into the cavity. When the nitrogen content in the cavity or furnace is insufficient, nitrogen can be added to the cavity through the air inlet. The air inlet 6 is located near the outlet 12, so the nitrogen can quickly dissipate into the furnace. At the same time, because the nitrogen is introduced towards the outlet 12, when the exhaust fan 31 is working, the nitrogen will move towards the inlet 11, reducing the entry of external oxygen.

[0040] See appendix Figure 3As shown, the baffle assembly 2 includes a horizontal plate 21 and a vertical plate 22. The horizontal plate 21 is fixed above the vertical plate 22 and located below the inlet 11. Multiple lower baffles 23 are fixed on the horizontal plate 21 at intervals along the length of the furnace. Each lower baffle 23 corresponds to an upper baffle 24. The vertical plate 22 is positioned higher than the height of the upper baffle 24 and the lower baffles 23, placing them at the height of the inlet 11 and the outlet 12. The horizontal plate 21, the vertical plate 22, and the housing 1 enclose an isolation cavity that does not participate in gas exchange, reducing gas loss. The lower baffles 23 and the upper baffles 24 form a curtain-like blocking structure, reducing gas overflow from the furnace and also reducing the entry of outside air into the furnace.

[0041] The lower end of the upper baffle 24 is attached to the side of the corresponding lower baffle 23, and a notch is provided on the upper baffle along the vertical direction. The notch allows gas to pass through, but at this time, the upper baffle 24 and the lower baffle 23 are in contact, and the gas passage is small, so less gas overflows from the furnace and the overflow is slower.

[0042] See appendix Figure 3 As shown, a switch door 52 is provided at the entrance 11. The switch door 52 can move up and down under the drive of the drive device 51 to close or open the entrance 11. The drive device 51 can be a cylinder, which is fixed on the housing 1, and the piston rod of the cylinder is fixed to the switch door 52.

[0043] In one embodiment, the present invention discloses a vacuum furnace 200, which employs the aforementioned oxygen concentration regulating mechanism 100.

[0044] The above embodiments are only for illustrating the technical concept and features of this utility model. Their purpose is to enable those skilled in the art to understand the content of this utility model and implement it. They cannot be used to limit the protection scope of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be covered within the protection scope of this utility model.

Claims

1. An oxygen concentration regulating mechanism, disposed at two openings along the length of the furnace chamber of a vacuum furnace, characterized in that: The oxygen concentration regulating mechanism includes a housing that defines a cavity. The housing has an inlet and an outlet along the length of the furnace. A curtain assembly is installed inside the cavity. An exhaust port communicating with the cavity is provided on the bottom plate of the housing. The exhaust port is connected to an exhaust pipe, which is connected to an exhaust fan outside the housing.

2. The oxygen concentration regulating mechanism according to claim 1, characterized in that: The curtain assembly and the inlet are separated by a gap along the length of the furnace chamber. An exhaust chamber is formed between the curtain assembly and the end plate of the housing with the inlet. The exhaust hole is located on the bottom plate at a position corresponding to the exhaust chamber.

3. The oxygen concentration regulating mechanism according to claim 2, characterized in that: An air distribution plate is also fixed inside the exhaust cavity. The air distribution plate is located below the inlet and has multiple ventilation holes arranged in an array on it.

4. The oxygen concentration regulating mechanism according to claim 3, characterized in that: The diameter of the ventilation hole gradually increases from the side closer to the inlet to the side farther away from the inlet or the outlet.

5. The oxygen concentration regulating mechanism according to claim 2, characterized in that: An oxygen sensor is installed inside the exhaust chamber, and the oxygen sensor is connected to the exhaust fan, which is a variable frequency fan.

6. The oxygen concentration regulating mechanism according to claim 1, characterized in that: The baffle assembly includes a horizontal plate and a vertical plate. The horizontal plate is fixed above the vertical plate and located below the inlet. Multiple lower baffles are fixed on the horizontal plate at intervals along the length of the furnace. Each lower baffle corresponds to an upper baffle.

7. The oxygen concentration regulating mechanism according to claim 6, characterized in that: The lower end of the upper curtain fits into the side of the corresponding lower baffle, and a notch is provided on the upper curtain along the vertical direction.

8. The oxygen concentration regulating mechanism according to claim 1, characterized in that: A switchable door is provided at the entrance, which can move up and down under the drive of a drive device to close or open the entrance.

9. The oxygen concentration regulating mechanism according to claim 1, characterized in that: An air inlet is provided near the outlet of the housing, and the air inlet is used to introduce nitrogen into the cavity.

10. A vacuum furnace, characterized in that: The oxygen concentration regulating mechanism described in any one of claims 1-9 is adopted.

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