An argon backfilling and purging device for a cemented carbide vacuum sintering furnace

Abstract

The application discloses a kind of hard alloy vacuum sintering furnace argon backfilling blowing device, belong to hard alloy vacuum sintering furnace technical field.It includes furnace body, at least connection is provided with vacuum air extraction main road, argon gas inlet branch and dewaxing circuit;Vacuum air extraction main road, port is provided with pump group, is communicated with main vacuum valve and bypass valve;Argon gas inlet branch, one side is imported argon gas source;Including argon gas mass flow meter one and argon gas inlet valve, for controlling argon gas import;Parallel connection has branch gas path on argon gas inlet branch, and is installed with argon furnace body replacement inlet valve, the caliber of argon furnace body replacement inlet valve is greater than the caliber of the argon gas inlet valve;Between pressure-reducing valve with argon gas inlet valve with pressure gauge is connected branch gas path;Dewaxing circuit, is communicated with and is installed with wax catcher and dewaxing valve, and is connected with pump group by dewaxing vacuum valve;Hydrogen discharge fire detection branch, hydrogen detection is carried out to wax catcher, to solve the technical problem that existing argon backfilling speed is slow.

Description

Technical Field

[0001] This invention patent relates to an argon backfilling and purging device for a cemented carbide vacuum sintering furnace, belonging to the technical field of cemented carbide vacuum sintering furnaces. Background Technology

[0002] H2 removal of cemented carbide forming agents is a commonly used process in cemented carbide sintering. This process involves introducing a certain flow rate of hydrogen under slight positive pressure, carrying the vaporized forming agent through the hydrogen ignition port for combustion. Because H2 is a flammable and explosive gas, the furnace body, wax trap, and related pipelines must undergo pre-vacuuming, argon backfilling, argon purging, and hydrogen purging before hydrogen heating to ensure safe operation of the sintering furnace. If air is not completely removed before the H2 dewaxing process, it can enter the furnace and mix with H2, potentially causing an explosion upon heating, resulting in personal injury and equipment damage.

[0003] Currently, argon backfilling in the pretreatment process is carried out using a low-pressure argon inlet valve circuit with a series mass flow control valve, such as in the CN207325945U cemented carbide dewaxing sintering furnace. Due to the limited range of the mass flow valve, the backfilling process from vacuum to atmospheric pressure is very slow, severely affecting the operating cycle of the sintering furnace. Secondly, the initial gas in the wax trap cannot be completely discharged, resulting in insufficient argon backfilling.

[0004] Therefore, it is urgent to propose an argon backfilling and purging device for a cemented carbide vacuum sintering furnace to solve the above problems. Summary of the Invention

[0005] To overcome the above shortcomings, the present invention provides an argon backfilling and purging device for a cemented carbide vacuum sintering furnace, which solves the technical problem of slow argon backfilling speed in existing systems.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An argon backfilling and purging device for a cemented carbide vacuum sintering furnace includes:

[0008] The furnace body is equipped with at least a main vacuum pumping line, an argon gas inlet branch line, and a dewaxing circuit.

[0009] The main vacuum pumping line is equipped with a pump set at the port and is connected to a main vacuum valve and a bypass valve. The main vacuum valve is used for closed-loop regulation of the vacuum level inside the furnace.

[0010] An argon gas inlet branch has an argon gas source introduced into it on one side; it includes an argon mass flow meter and an argon gas inlet valve for controlling the argon gas supply; a branch gas path is connected in parallel to the argon gas inlet branch and is equipped with an argon furnace body replacement inlet valve, the diameter of which is larger than that of the argon gas inlet valve; a branch gas path is connected between a pressure reducing valve with a pressure gauge and the argon gas inlet valve.

[0011] The dewaxing circuit is connected to a wax trap and a dewaxing valve, and is connected to the pump unit through a dewaxing vacuum valve.

[0012] The hydrogen emission flame detection branch detects hydrogen in the wax trap;

[0013] Backfilling method:

[0014] Step 1, Pre-vacuuming: The pump unit starts upon receiving a command from the external control system, and the main vacuum valve, bypass valve, and dewaxing vacuum valve are all opened; the furnace body and wax collector are simultaneously evacuated to the preset vacuum value.

[0015] Step 2, rapid backfilling stage: The control system shuts down the pump unit, and then the main vacuum valve, bypass valve and dewaxing vacuum valve are all closed;

[0016] Open the dewaxing valve and turn on the argon furnace body replacement inlet valve to quickly backfill the furnace body and wax trap to atmospheric pressure; the furnace body and wax trap are connected to the same cavity, and argon gas is simultaneously backfilled into the furnace cavity and wax trap pipeline;

[0017] Open the buffer tank replenishment valve 72; argon gas pressurizes the buffer tank 71 through the buffer tank replenishment valve 72, and the PLC reads the pressure from the pressure transmitter 74; when the set purging pressure A is reached; close the buffer tank replenishment valve 72 to cut off the argon gas supply;

[0018] Subsequently, the dewaxing valve 42 remains closed; the dewaxing vacuum valve 43 remains open, and the pump unit 21 continues to run; the vacuum regulating valve 24 is opened to the dedicated purging opening.

[0019] PLC interlock condition confirmation: The pressure in buffer tank 71 has reached the set value A; the valve position feedback confirmation of each valve is in place; there is no overpressure alarm in wax trap 41;

[0020] Triggering the opening of the pulse quick-opening release valve 81; the high-pressure argon gas in the buffer tank 71 is released instantaneously; after being limited by the flow through the throttling orifice plate 82, the high-speed pulse gas flow rushes into the wax trap 41; and is drawn out of the system by the pump group 21 from the outlet of the wax trap 41 through the dewaxing vacuum valve 43; when the pulse quick-opening release valve 81 is opened, the dewaxing vacuum valve opens, forming a gas flow.

[0021] Repeat step 2, and flush the cavity of the wax trap 41 2-3 times; after completion, close the dewaxing vacuum valve 43 and open the dewaxing valve 42.

[0022] Step 3, Precision pressure adjustment and switching: After reaching atmospheric pressure, close the argon furnace body replacement inlet valve; switch to the argon inlet branch, open the argon inlet valve, and slowly adjust to the micro-positive pressure process pressure required for H2 dewaxing;

[0023] Step 4: Hydrogen gas is introduced into the hydrogen emission and detection branch located at the wax trap, and hydrogen gas is detected in the wax trap.

[0024] In a further technical solution, a vacuum regulating valve is installed in parallel with the bypass valve on the main vacuum pumping line; and a main inlet valve is provided on the argon gas inlet branch line.

[0025] A dewaxing valve is installed between the wax trap and the furnace body.

[0026] In a further technical solution, the argon gas inlet branch includes a pre-positioned pressure reducing valve with a pressure gauge, a manual ball valve, and a PLC-PS pressure switch. The pressure reducing valve with the pressure gauge detects the gas input, and the PLC-PS pressure switch is used to detect the gas pressure in the pipeline and feed the gas pressure signal back to the control system.

[0027] In a further technical solution, the argon gas inlet branch also includes a glass rotor flow meter and an argon mass flow meter connected in series with the argon gas inlet valve. The glass rotor flow meter is used to visually observe the real-time argon gas flow rate; the argon mass flow meter is used to automatically control the argon gas inlet flow rate; and the flow rate value is set by the PLC to control the inlet rate.

[0028] In a further technical solution, the hydrogen emission flame detection branch includes at least a hydrogen regulating valve and an ultraviolet tube. The ultraviolet tube flame detection device detects whether the emission port is ignited, thereby determining whether the hydrogen is pure.

[0029] Basic principle of the device:

[0030] Under normal circumstances, during the pre-vacuuming stage, the pump set is turned on, and the main vacuum valve, bypass valve, and dewaxing vacuum valve are opened. The wax trap and furnace body are evacuated together to the preset vacuum value. During the argon backfilling stage, the pump set, main vacuum valve, bypass valve, and dewaxing vacuum valve are turned off, and the dewaxing valve is opened. Backfilling is carried out through the added large-diameter, high-flow-rate argon furnace body replacement valve. After the wax trap and furnace body quickly reach atmospheric pressure, the circuit switches to the low-pressure argon inlet valve circuit with the series mass flow control valve to slowly and stably reach the pressure control value of hydrogen dewaxing, achieving both fast and stable pressure.

[0031] In a further technical solution, a one-way valve and an argon mass flow meter are connected in series in the branch gas line; the one-way valve prevents argon from flowing back into the branch gas line when the argon mass flow meter is started.

[0032] The argon mass flow meter is used to detect the argon flow rate in the secondary gas path.

[0033] In a further technical solution, a buffer gas path is installed between the argon gas source and the pump group, and a buffer tank is installed on the buffer gas path to buffer and store argon gas.

[0034] The buffer tank and the wax trap are also equipped with a release gas passage, which is used to release the argon gas in the buffer tank when it reaches the specified A, so as to purge the inside of the wax trap cavity.

[0035] In a further technical solution, a buffer tank replenishment valve and a throttling orifice plate are provided between the argon gas source and the buffer tank. The buffer tank replenishment valve is used to open and close the buffer gas path, and the throttling orifice plate is used to reduce the impact of argon gas on the buffer tank.

[0036] A pressure transmitter is installed on the side of the buffer tank to detect the pressure inside the buffer tank and send the feedback to the buffer tank air supply valve.

[0037] A buffer vacuum valve is installed between the buffer tank and the pump unit.

[0038] In a further technical solution, the release gas path includes a pulse quick-opening release valve, a throttling orifice plate II, and a one-way check valve connected in series. The one-way check valve is connected to the inlet of the wax trap; the pulse quick-opening release valve is connected to the outlet of the buffer tank.

[0039] In a further technical solution, in step 1, the buffer tank gas supply valve is closed simultaneously, the buffer tank vacuum valve is opened, the buffer tank is evacuated, and the internal gas is purged.

[0040] In step 2, the buffer tank replenishment valve is opened synchronously; argon gas is supplied to the buffer tank through the replenishment valve, and the PLC reads the pressure from the pressure transmitter; when the set purging pressure A is reached, the buffer tank replenishment valve is closed, cutting off the argon gas supply;

[0041] Subsequently, the dewaxing valve remains closed; the dewaxing vacuum valve remains open, and the pump unit continues to run; the vacuum regulating valve is opened to the designated purging position.

[0042] PLC interlock condition confirmation: The pressure in the buffer tank reaches the set value A; the valve position feedback confirmation is in place; there is no overpressure alarm in the wax trap;

[0043] Triggering the opening of the pulse quick-opening release valve; the high-pressure argon gas in the buffer tank is released instantly; after passing through the throttling orifice plate and flow restriction, the high-speed pulse gas flow rushes into the wax trap; and from the outlet of the wax trap, it is pumped away by the pump unit through the dewaxing vacuum valve and discharged from the system;

[0044] Repeat step 2, flushing the wax trap chamber 2-3 times; after completion, close the dewaxing vacuum valve, open the dewaxing valve, and proceed to step 3.

[0045] The present invention has the following beneficial effects:

[0046] 1. Significantly shortens process preparation time and improves sintering furnace operating cycle time; This invention uses a large-diameter argon furnace body replacement valve for rapid backfilling. This invention ensures that the equipment is quickly backfilled to atmospheric pressure during the hydrogen process pretreatment stage, which saves the entire sintering process time and ensures the safe and reliable operation of the H2 dewaxing process in the vacuum sintering furnace.

[0047] The backfilling time from vacuum to atmospheric pressure has been shortened from tens of minutes to several minutes, significantly reducing the production cycle of a single furnace and improving equipment utilization.

[0048] 2. Balancing backfilling speed with pressure control accuracy;

[0049] After the large-diameter fast-charging circuit completes the coarse charging, it automatically switches to the precision pressure regulation circuit of the small-diameter argon mass flow meter, realizing a phased control strategy of fast charging and fine adjustment. This solves the problem of slow backfilling caused by the limited range of a single mass flow valve, and also ensures the precise control of the micro-positive pressure process pressure required for subsequent hydrogen dewaxing, achieving a balance between speed and precision.

[0050] 3. Eliminate airflow crosstalk and improve system reliability;

[0051] A one-way valve is installed on the large-diameter branch to prevent argon from flowing back into the large-diameter pipeline when the small-diameter argon mass flow meter is working. This eliminates the risk of airflow interference and damage to the precision valve body, and ensures the smooth and reliable switching of the dual circuits.

[0052] 4. Pulse purging achieves deep cleaning of the wax trap, eliminating safety hazards; this invention uses a combination of a buffer tank and a pulse quick-opening valve to generate a high-speed pulsed airflow that powerfully flushes the wax trap, effectively removing residual gas and trace amounts of wax dust from the dead corners of the trap's internal structure. Compared to conventional continuous flow purging methods, this method is more thorough and efficient, fundamentally eliminating the explosion risk caused by the mixture of residual air and hydrogen. The cleaning effect of this method on the wax trap is unattainable by conventional solutions. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the argon backfilling and purging system for the cemented carbide vacuum sintering furnace of the present invention. Figure 1 ;

[0054] Figure 2 This is a schematic diagram of the argon backfilling and purging system for the cemented carbide vacuum sintering furnace of the present invention. Figure 2 ;

[0055] Figure 3 This is a schematic diagram of the argon backfilling and purging system for the cemented carbide vacuum sintering furnace of the present invention. Figure 3 ;

[0056] legend:

[0057] 10. Furnace body;

[0058] 20. Main vacuum pumping line; 21. Pump unit; 22. Main vacuum valve; 23. Bypass valve; 24. Vacuum regulating valve;

[0059] 30. Argon gas inlet branch; 31. Argon mass flow meter 1; 32. Argon gas inlet valve; 33. Pressure reducing valve with pressure gauge; 34. Manual ball valve; 35. PLC-PS pressure switch; 36. Glass rotor flow meter; 37. Main inlet valve;

[0060] 40. Dewaxing circuit; 41. Wax trap; 42. Dewaxing valve; 43. Dewaxing vacuum valve;

[0061] 50. Branch gas path; 51. Argon furnace body replacement inlet valve; 52. Check valve; 53. Argon mass flow meter II;

[0062] 60. Hydrogen emission flame detection branch; 61. Hydrogen regulating valve; 62. Ultraviolet light tube;

[0063] 70. Buffer air path; 71. Buffer tank; 72. Buffer tank air supply valve; 73. Orifice plate one; 74. Pressure transmitter; 75. Buffer vacuum valve;

[0064] 80. Release air path; 81. Pulse quick-opening release valve; 82. Throttling orifice plate II; 83. One-way check valve. Detailed Implementation

[0065] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0066] Example 1

[0067] like Figure 1 The image shows one embodiment of the present invention, specifically an argon backfilling and purging device for a cemented carbide vacuum sintering furnace, comprising:

[0068] The furnace body 10 is equipped with at least a vacuum extraction main line 20, an argon gas inlet branch line 30, and a dewaxing circuit 40; the main cavity for hard alloy sintering holds the product to be sintered and requires high-temperature treatment under a protective atmosphere.

[0069] The main vacuum pumping line 20 provides a vacuum source channel for the furnace body and the wax trap. A pump group 21 is installed at the port and is connected to a main vacuum valve 22 and a bypass valve 23. The main vacuum valve 22 is used for closed-loop regulation of the vacuum level inside the furnace body 10. The main vacuum valve is used to open and close the main passage during vacuuming and to regulate the vacuum level inside the furnace in a closed loop. The bypass valve 23 is a small-diameter passage connected in parallel with the main vacuum valve and is used for fine-tuning at the end of the vacuuming process or as a backup channel.

[0070] Argon inlet branch 30, connected in series with a low-pressure inlet circuit of a mass flow control valve, is responsible for precise micro-pressure regulation after backfilling to atmospheric pressure, and an argon gas source is introduced on one side; it includes an argon mass flow meter 31 and an argon inlet valve 32 for controlling the argon inlet; the argon mass flow meter 31 is a mass flow controller, with the flow rate set by a PLC to automatically and precisely control the inlet rate. A branch gas path 50 is connected in parallel to the argon inlet branch 30, and an argon furnace body replacement inlet valve 51 is installed thereon. The diameter of the argon furnace body replacement inlet valve 51 is larger than the diameter of the argon inlet valve 32; the branch gas path is a large-diameter passage connected in parallel with the argon inlet branch, used for rapid backfilling to atmospheric pressure. A pressure reducing valve 33 with a pressure gauge is connected between the branch gas path 50 and the argon inlet valve 32.

[0071] The dewaxing circuit 40 is a gas passage connecting the furnace body and the wax trap. It is used for gas circulation during the dewaxing process. It connects the wax trap 41 and the dewaxing valve 42, and is connected to the pump group 21 through the dewaxing vacuum valve 43. The wax trap cools the wax-containing gas discharged from the furnace, causing the wax vapor to condense into a solid and be captured, preventing the wax vapor from entering the pump group or being discharged into the atmosphere.

[0072] Hydrogen emission flame detection branch 60 is used as a safety detection channel after hydrogen is introduced, and performs hydrogen detection on wax trap 41.

[0073] Backfilling method:

[0074] Step 1, Pre-vacuuming: Pump unit 21 starts upon receiving a command from the external control system, and the main vacuum valve 22, bypass valve 23 and dewaxing vacuum valve 43 are all opened; the furnace body 10 and the wax collector 41 are simultaneously evacuated to the preset vacuum value, which is generally 200Pa.

[0075] Step 2, rapid backfilling stage: The control system shuts down pump group 21, and then the main vacuum valve 22, bypass valve 23 and dewaxing vacuum valve 43 are all closed;

[0076] Open the dewaxing valve 42 and backfill through the large-diameter, high-flow-rate argon furnace body replacement valve 51 to quickly backfill the furnace body 10 and the wax trap 41 to atmospheric pressure; the furnace body 10 and the wax trap 41 are connected to the same cavity, and argon gas is used to backfill the furnace cavity and the pipeline of the wax trap 41 simultaneously.

[0077] Step 3, Precision pressure adjustment and switching: After reaching atmospheric pressure, close the argon furnace body replacement inlet valve 51; switch to the argon inlet branch 30, open the argon inlet valve 32, and slowly adjust to the micro-positive pressure process pressure required for H2 dewaxing; after the wax trap and furnace body quickly reach atmospheric pressure, switch to the low-pressure argon inlet valve circuit with the series mass flow control valve, and slowly and stably reach the pressure control value for hydrogen dewaxing, so as to achieve both fast and stable pressure.

[0078] Step 4: Hydrogen gas is introduced into the hydrogen emission and detection branch 60 located at the wax trap 41, and hydrogen gas is detected in the wax trap 41.

[0079] Located on the main vacuum pumping line 20, a vacuum regulating valve 24 is installed in parallel on the bypass valve 23. It is installed on the bypass line and has an adjustable opening function to precisely control the pumping speed and prevent the powder dust in the furnace from being blown away due to excessive pumping speed. An argon gas inlet branch line 30 is equipped with a main inlet valve 37, which is the main switch valve of the argon gas inlet branch line and is automatically controlled by the PLC.

[0080] A dewaxing valve 42 is provided between the wax trap 41 and the furnace body 10.

[0081] In a further technical solution, the argon gas inlet branch 30 includes a pre-installed pressure reducing valve 33 with a pressure gauge, a manual ball valve 34, and a PLC-PS pressure switch 35. The pressure reducing valve 33 detects the gas input, and the PLC-PS pressure switch 35 detects the gas pressure in the pipeline and feeds the gas pressure signal back to the control system. The manual ball valve is used to manually cut off the gas supply during equipment maintenance; the PLC-PS pressure switch is an electrical pressure switch that converts the gas pressure signal into an electrical signal and feeds it back to the control system to achieve interlock protection.

[0082] In a further technical solution, the argon gas inlet branch 30 also includes a glass rotor flow meter 36 and an argon mass flow meter 31 connected in series with the argon gas inlet valve 32. The glass rotor flow meter 36 is used to visually observe the real-time argon gas flow rate; the argon mass flow meter 31 is used to automatically control the argon gas inlet flow rate; and the flow rate value is set by the PLC to control the inlet rate.

[0083] In a further technical solution, the hydrogen emission flame detection branch 60 includes at least a hydrogen regulating valve 61 and an ultraviolet (UV) tube 62 to determine whether the UV tube 62 is ignited to detect whether the wax trap 41 is leaking hydrogen. The UV tube 62 determines whether there is hydrogen leakage or abnormal combustion in the wax trap by detecting the ultraviolet signal of the combustion flame.

[0084] Example 2

[0085] like Figure 2 As shown, a one-way valve 52 and an argon mass flow meter 53 are connected in series on the branch gas path 50; the one-way valve 52 prevents argon from flowing back into the branch gas path 50 when the argon mass flow meter 31 is started.

[0086] The argon mass flow meter 53 detects the argon flow rate in branch line 50. A one-way valve is installed on the large-diameter branch to prevent argon from flowing back into the large-diameter pipeline when the small-diameter MFC circuit is working, eliminating the risk of airflow interference and damage to the precision valve body, and ensuring smooth and reliable switching between the two circuits.

[0087] Example 3

[0088] like Figure 3 As shown, another embodiment of the present invention is provided. Based on embodiment 1, a buffer gas path 70 is installed between the argon gas source and the pump group 21. A buffer tank 71 is provided on the buffer gas path 70, and the buffer tank 71 is used to buffer and store argon gas.

[0089] Buffer gas path 70 is an argon gas buffer and pulse purging system used to generate a high-pressure pulse gas flow to powerfully clean the wax trap. Buffer tank 71 is an argon gas storage container that pre-stores argon gas at a certain pressure during non-purging periods for instantaneous release during pulse purging.

[0090] The buffer tank 71 and the wax trap 41 are also provided with a release gas passage 80, which is used to release the argon gas in the buffer tank 71 when it reaches the specified A, so as to purge the inside of the cavity of the wax trap 41.

[0091] like Figure 3 At the bottom, a buffer tank replenishment valve 72 and a throttling orifice plate 73 are provided between the argon gas source and the buffer tank 71. The buffer tank replenishment valve 72 is used to open and close the buffer gas path 70, and the throttling orifice plate 73 is used to prevent high-pressure argon gas from impacting the inner wall of the buffer tank and causing vibration and noise.

[0092] A pressure transmitter 74 is installed on the side of the buffer tank 71 to detect the pressure inside the buffer tank 71 and feed it back to the buffer tank air supply valve 72; the pressure transmitter 74 detects the pressure value inside the buffer tank in real time and feeds it back to the PLC to determine whether the air filling has reached the set value A.

[0093] A buffer vacuum valve 75 is installed between the buffer tank 71 and the pump unit 21.

[0094] like Figure 3 The release gas path is a high-pressure gas release channel from the buffer tank to the wax catcher. The release gas path 80 includes a pulse quick-opening release valve 81, a throttling orifice plate 82 and a one-way check valve 83 connected in series. The one-way check valve 83 is connected to the air inlet of the wax catcher 41; the pulse quick-opening release valve 81 is connected to the air outlet of the buffer tank 71.

[0095] The functions of the buffer tank and pulse purging system are as follows:

[0096] 1) Shorten the purging time;

[0097] In existing technologies, argon purging of wax traps involves continuously introducing argon gas through a small-diameter circuit and continuously pumping it away. This method results in a low gas flow rate, relying solely on concentration dilution to replace residual air within the wax trap, leading to extremely low efficiency. The buffer tank solution, on the other hand, pre-stores gas before purging begins, simultaneously pressurizing the buffer tank to a set value A during the vacuuming phase. During purging, the gas is released instantaneously, creating a high-speed pulsed airflow that intensely washes over the wax trap, relying on momentum impact rather than concentration dilution to expel residual gas.

[0098] 2) Perform powerful cleaning of the hard-to-reach areas inside the wax trap;

[0099] The wax trap has a complex internal structure, containing condenser coils, baffles, and filters. It contains many dead zones for gas flow, such as the back of the baffles, gaps between the coils, and sharp corners of the cavity. Under conventional continuous flow purging, the gas flows only along the path of least resistance, and the residual air in these "dead zones" is almost never displaced, posing a safety hazard.

[0100] The pulsed airflow provided by the buffer tank has the characteristics of instantaneous high pressure and high speed impact. The airflow enters the wax trap cavity with high momentum, generating turbulent diffusion and vortex stirring effects within the cavity, forming multi-directional airflow disturbances. This dynamic impact effect can "entrain" residual gas deposited in dead zones, which is then pumped away. A single pulse may not be sufficient for complete removal, so the design repeats 2-3 pulse flushes. Each impact breaks the previous airflow distribution pattern, gradually stripping away residual gas from dead zones.

[0101] Step 1, Pre-vacuuming: Pump unit 21 starts upon receiving a command from the external control system, and the main vacuum valve 22, bypass valve 23, and dewaxing vacuum valve 43 are all opened; simultaneously, the furnace body 10 and the wax collector 41 are evacuated to the preset vacuum value, generally 200Pa; the buffer tank gas supply valve 72 is closed, the vacuum valve of the buffer tank 71 is opened, and the buffer tank 71 is evacuated to remove the internal gas.

[0102] Step 2, rapid backfilling stage: The control system shuts down pump group 21, and then the main vacuum valve 22, bypass valve 23 and dewaxing vacuum valve 43 are all closed;

[0103] Open the dewaxing valve 42 and backfill through the large-diameter, high-flow-rate argon furnace body replacement valve 51 to quickly backfill the furnace body 10 and the wax trap 41 to atmospheric pressure; the furnace body 10 and the wax trap 41 are connected to the same cavity, and argon gas is used to backfill the furnace cavity and the pipeline of the wax trap 41 simultaneously.

[0104] Step 3, Precision pressure adjustment and switching: After reaching atmospheric pressure, close the argon furnace body replacement inlet valve 51; switch to the argon inlet branch 30, open the argon inlet valve 32, and slowly adjust to the micro-positive pressure process pressure required for H2 dewaxing; after the wax trap and furnace body quickly reach atmospheric pressure, switch to the low-pressure argon inlet valve circuit with the series mass flow control valve, and slowly and stably reach the pressure control value for hydrogen dewaxing, so as to achieve both fast and stable pressure.

[0105] Step 4: Hydrogen gas is introduced into the hydrogen emission and detection branch 60 located at the wax trap 41, and hydrogen gas is detected in the wax trap 41.

[0106] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An argon backfilling and purging device for a cemented carbide vacuum sintering furnace, characterized in that, include: The furnace body (10) is at least connected to a vacuum pumping main line (20), an argon gas inlet branch line (30), and a dewaxing circuit (40). The main vacuum pumping line (20) is equipped with a pump group (21) at the port and is connected to a main vacuum valve (22) and a bypass valve (23). The main vacuum valve (22) is used to regulate the vacuum level inside the furnace body (10) in a closed loop. Argon gas inlet branch (30) is connected to an argon gas source on one side; it includes an argon mass flow meter (31) and an argon gas inlet valve (32) for controlling the argon gas inlet; a branch gas path (50) is connected in parallel to the argon gas inlet branch (30), and an argon furnace body replacement inlet valve (51) is installed thereon, the diameter of the argon furnace body replacement inlet valve (51) is larger than the diameter of the argon gas inlet valve (32); the branch gas path (50) is connected between the pressure reducing valve (33) with pressure gauge and the argon gas inlet valve (32); The dewaxing circuit (40) is connected to a wax trap (41) and a dewaxing valve (42), and is connected to a pump unit (21) via a dewaxing vacuum valve (43). The hydrogen emission flame detection branch (60) discharges hydrogen from the furnace body (10) and the wax trap (41). The discharged hydrogen is ignited at the pipe opening, which is equipped with a flame detection device (62) for hydrogen detection. Backfilling method: Step 1, Pre-vacuuming: The pump unit (21) starts upon receiving an instruction from the external control system, and the main vacuum valve (22), bypass valve (23) and dewaxing vacuum valve (43) are all opened; the furnace body (10) and the wax trap (41) are simultaneously evacuated to the preset vacuum value. Step 2, rapid backfilling stage: The control system shuts down the pump group (21), and then the main vacuum valve (22), bypass valve (23) and dewaxing vacuum valve (43) are all closed; Open the dewaxing valve (42), open the argon furnace body replacement inlet valve (51), and quickly backfill the furnace body (10) and wax trap (41) to atmospheric pressure; the furnace body (10) and wax trap (41) are connected to the same cavity, and argon gas is synchronously backfilled into the furnace cavity and the wax trap (41) pipeline; Step 3, Precision pressure adjustment and switching: After reaching atmospheric pressure, close the argon furnace body replacement inlet valve (51); switch to the argon inlet branch (30), open the argon inlet valve (32), and slowly adjust to the micro-positive pressure process pressure required for H2 dewaxing; Step 4: After the furnace (10) reaches the set pressure for hydrogen dewaxing, the gas inlet is switched from argon to process gas hydrogen to replace the argon in the furnace. Hydrogen is then detected at the hydrogen discharge flame detection branch (60) located at the wax trap (41). After the argon in the furnace (10) is completely replaced by hydrogen, the hydrogen discharged from the argon inlet branch (30) will be ignited. After the flame detection is detected, the equipment will consider the hydrogen pre-treatment to be completed.

2. The argon backfilling and purging device for a cemented carbide vacuum sintering furnace according to claim 1, characterized in that, A vacuum regulating valve (24) is installed in parallel on the bypass valve (23) on the main vacuum pumping line (20); an argon gas inlet branch line (30) is provided with a main inlet valve (37). A dewaxing valve (42) is provided between the wax trap (41) and the furnace body (10).

3. The argon backfilling and purging device for a cemented carbide vacuum sintering furnace according to claim 1, characterized in that, The argon gas inlet branch (30) includes a pressure reducing valve (33) with a pressure gauge, a manual ball valve (34), and a PLC-PS pressure switch (35). The pressure reducing valve (33) with the pressure gauge adjusts the inlet pressure to detect the gas input, and the PLC-PS pressure switch (35) is used to detect the gas pressure in the pipeline and feed back the argon gas source pressure signal to the control system.

4. The argon backfilling and purging device for a cemented carbide vacuum sintering furnace according to claim 3, characterized in that, The argon gas inlet branch (30) also includes a glass rotor flow meter (36) and an argon mass flow meter (31) connected in series with the argon gas inlet valve (32). The glass rotor flow meter (36) is used to visually observe the real-time flow rate of argon gas; the argon mass flow meter (31) is used to automatically control the argon gas inlet flow rate. The flow rate is set by the PLC to control the air intake rate.

5. The argon backfilling and purging device for a cemented carbide vacuum sintering furnace according to claim 3, characterized in that, The hydrogen emission flame detection branch (60) includes at least a hydrogen regulating valve (61) and an ultraviolet tube (62). The ultraviolet tube (62) detects whether the gas emitted from the outlet of the hydrogen emission branch (60) is ignited. If a flame is detected, it indicates that the argon in the furnace has been completely replaced by hydrogen.

6. The argon backfilling and purging device for a cemented carbide vacuum sintering furnace according to claim 3, characterized in that, A one-way valve (52) and an argon mass flow meter II (53) are connected in series on the branch gas path (50); the one-way valve (52) prevents argon from flowing back into the branch gas path (50) when the argon mass flow meter I (31) is started. The argon mass flow meter 2 (53) detects the argon flow rate in the branch gas path (50).

7. The argon backfilling and purging device for a cemented carbide vacuum sintering furnace according to claim 3, characterized in that, A buffer gas path (70) is also installed between the argon gas source and the pump group (21). A buffer tank (71) is installed on the buffer gas path (70). The buffer tank (71) is used to buffer and store argon gas. The buffer tank (71) and the wax trap (41) are also provided with a release gas passage (80) to release the argon gas in the buffer tank (71) when it reaches the specified pressure A, so as to purge the inside of the wax trap (41).

8. The argon backfilling and purging device for a cemented carbide vacuum sintering furnace according to claim 7, characterized in that, A buffer tank gas supply valve (72) and a throttling orifice plate (73) are provided between the argon gas source and the buffer tank (71). The buffer tank gas supply valve (72) is used to open and close the buffer gas path (70), and the throttling orifice plate (73) is used to reduce the impact of argon gas on the buffer tank (71). A pressure transmitter (74) is installed on the side of the buffer tank (71) to detect the pressure inside the buffer tank (71) and feed it back to the buffer tank air supply valve (72). A buffer vacuum valve (75) is installed between the buffer tank (71) and the pump unit (21).

9. The argon backfilling and purging device for a cemented carbide vacuum sintering furnace according to claim 8, characterized in that, The release air path (80) includes a pulse quick-opening release valve (81), a throttling orifice plate (82) and a one-way check valve (83) connected in series. The one-way check valve (83) is connected to the air inlet of the wax trap (41); the pulse quick-opening release valve (81) is connected to the air outlet of the buffer tank (71).

10. The argon backfilling and purging device for a cemented carbide vacuum sintering furnace according to claim 3, characterized in that, In step 1, the gas supply valve of the buffer tank (71) is closed simultaneously, the vacuum valve (75) of the buffer tank (71) is opened, the buffer tank (71) is evacuated, and the internal gas is purged. In step 2, the gas supply valve of the buffer tank (71) is opened synchronously; argon gas is supplied to the buffer tank (71) through the gas supply valve of the buffer tank (71) to pressurize it, and the PLC reads the pressure of the pressure transmitter (74); when the set purging pressure A is reached, the gas supply valve of the buffer tank (71) is closed to cut off the argon gas source; Subsequently, the dewaxing valve (42) remains closed; the dewaxing vacuum valve (43) remains open, the pump unit (21) continues to run; and the vacuum regulating valve (24) is opened to the purging-specific opening. PLC interlock condition confirmation: The pressure of the buffer tank (71) reaches the set value A; the valve position feedback confirmation of each valve is in place; the pressure of the wax trap (41) has no overpressure alarm; Trigger the opening of the pulse quick-opening release valve (81); the high-pressure argon gas in the buffer tank (71) is released instantly; after being limited by the flow through the second throttling orifice plate (82), the high-speed pulse gas flow rushes into the wax trap (41); and is pumped out of the system by the pump group (21) through the dewaxing vacuum valve (43) from the outlet of the wax trap (41); Repeat step 2, and flush the cavity of the wax trap (41) 2-3 times. After the operation is completed, close the dewaxing vacuum valve (43), open the dewaxing valve (42), and proceed with the subsequent step 3.

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