Online filtering system and method for removing light impurities in nitriding salt bath

Abstract

The invention relates to the technical field of impurity filtration, and discloses an on-line filtration system and method for removing light impurities in a nitriding salt bath, and the system comprises a buoyancy monitoring device which monitors buoyancy data of the nitriding salt bath in nitriding equipment in real time, and controls an air compression flow guide device and a collection device based on the buoyancy data; the air compression flow guide device is used for introducing air into the nitriding salt bath in the nitriding equipment after being started and conveying the nitriding salt bath containing light impurities to a filtering device outside the nitriding equipment; the filtering device is used for filtering the conveyed nitriding salt bath containing the light impurities in a multi-layer manner to obtain the light impurities and a de-nitriding salt bath, and conveying the de-nitriding salt bath back to the nitriding salt bath in the nitriding equipment; after the collecting device is started, light impurities are scraped out and collected in a rolling mode. The continuous online automatic filtering process is carried out while production is not interfered, the green, environment-friendly and efficient filtering effect of removing the light impurities in the nitriding salt bath is achieved, the interference of the light impurities on the process is remarkably reduced, and the machining quality of workpieces is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of impurity filtration, and particularly relates to an on-line filtration system and method for removing light impurities in a nitriding salt bath. Background Art

[0002] The QPQ treatment operation process consists of processes such as degreasing with a cleaning agent, rinsing with clean water, preheating, nitriding, oxidizing, desalting with cold water, hot water cleaning, and drying and oil infiltration. Among them, the nitriding process is the most important and core process in the QPQ technology. The purpose of the nitriding process is to form a dense compound layer with sufficient depth and a corresponding diffusion layer of a corresponding depth on the surface of the workpiece. In addition to nitriding temperature, nitriding time, and cyanate content, the state of the nitriding salt solution, especially the slag removal situation, has a great relationship with the maintenance of the quality of the nitrided layer.

[0003] During the nitriding process, metal atoms on the surface of the workpiece may react with oxygen or other oxidizing substances in the salt bath to form metal oxides, and salts in the nitriding salt bath may decompose to produce some solid residues during high-temperature and chemical reaction processes. At the same time, before the workpiece enters the nitriding salt bath, the surface may carry some solid particles due to incomplete cleaning, such as metal chips or abrasive particles remaining during the processing. For these impurities with large particle size and large weight in the nitriding salt bath, a sedimentation tank is usually used to remove them.

[0004] Metal chips, cutting oil, decomposition products of the salt bath, fine particles generated by equipment components, and dust entering from the outside on the surface of the workpiece form light impurities during the nitriding process. Due to their small particle size, strong suspension, easy chemical reaction with the filter medium and salt bath components, and interference from factors such as high-temperature environment and salt bath flow, it is difficult to effectively filter them. In the initial stage of starting the nitriding furnace, due to the low density of the light impurities, they float on the surface of the salt bath. When the liquid level is static, they are relatively stable, and when the liquid level has flow, they will move in the upper part of the salt bath along with the liquid flow; when the temperature in the furnace rises, the impurities containing moisture vaporize first, and the organic impurities decompose and carbonize to form bubbles. This phenomenon will make the distribution of the impurities more chaotic and the spread range wider; some impurities react with the salt bath to generate adsorbed active ions, which will adsorb on the surface of the workpiece and interfere with the nitriding process when approaching the workpiece, and even generate new compounds. Therefore, it is extremely important to remove the light impurities in the nitriding salt bath.

[0005] In view of the continuous instability of the distribution and state of the light impurities during the nitriding process, the existing method usually adopts a shutdown filtration method to complete the filtration under the relatively stable condition of the light impurities, and resume production after removing the light impurities. This method not only affects production efficiency but also cannot completely solve the influence of the light impurities on the workpiece quality during the nitriding process. Summary of the Invention

[0006] The present invention aims to provide an on-line filtration system and method for removing light impurities from a nitriding salt bath, realizing a continuous on-line automatic filtration process without disturbing production, achieving a filtration effect of green, environmental protection and high efficiency in removing light impurities from the nitriding salt bath, significantly reducing the interference of light impurities on the process, effectively alleviating the aging speed of the nitriding salt bath, reducing the thickness of the loose layer of the workpiece, increasing the hardness, and improving the machining quality of the workpiece during the nitriding process.

[0007] The basic solution provided by the present invention is: an on-line filtration system for removing light impurities from a nitriding salt bath, including a buoyancy monitoring device, an air compression and diversion device, a filtration device and a collection device;

[0008] The buoyancy monitoring device is used to monitor the buoyancy data of the nitriding salt bath in the nitriding equipment in real time, and control the air compression and diversion device and the collection device based on the buoyancy data;

[0009] The air compression and diversion device is used to introduce air into the nitriding salt bath in the nitriding equipment after starting, and extract the nitriding salt bath containing light impurities and transport it to the filtration device outside the nitriding equipment;

[0010] The filtration device is used to filter the nitriding salt bath containing light impurities transported in multiple layers, obtain light impurities and the nitriding salt bath without impurities, and transport the nitriding salt bath without impurities back into the nitriding salt bath in the nitriding equipment;

[0011] The collection device is used to scrape out and collect light impurities in a rolling manner.

[0012] Further, the buoyancy monitoring device includes a float valve. The float valve is electrically connected to a pressure sensor through a crank arm. The pressure sensor is electrically connected to a controller, and is electrically connected to the air compression and diversion device and the collection device through the controller.

[0013] Further, the filtration device includes a bracket; a housing is installed on the bracket; a filtration chamber is formed in the inner cavity of the housing; the bottom of the housing is a grid structure and is completely covered with a filtration layer; the filtration layer has a multi-layer stacked structure.

[0014] Further, the multi-layer stacked structure is that the middle layer is at least one filter element, and the upper layer and the lower layer of the middle layer are both at least one filter screen, and the pore size of the filter screen located in the upper layer is smaller than the pore size of the filter screen located in the lower layer.

[0015] Further, the air compression and diversion device includes an air compression device, a compressed air conduit and a filter pipe; the inlet end of the compressed air conduit is connected to the air compression device, and the length of the compressed air conduit satisfies that its exhaust port end is placed at a first preset depth below the liquid level of the nitriding salt bath during use; the drain port end of the filter pipe is communicated with the filtration device, and the length of the filter pipe satisfies that its inlet port end is placed at a second preset depth below the liquid level of the nitriding salt bath during use; wherein, the exhaust port end of the compressed air conduit is communicated with the filter pipe.

[0016] Furthermore, the collection device includes a driving device, an annular slag scraping plate assembly controlled by the driving device, and a slag collection box; the annular slag scraping plate assembly is installed in the filtration chamber and above the filtration layer, and the size of the annular slag scraping plate assembly meets the requirement of contacting the upper surface of the filtration layer as per the preset requirement under the drive of the driving device; the slag collection box is installed outside the housing, communicated with the filtration layer, and located on the side where impurities outside the housing are scraped out.

[0017] Furthermore, the annular slag scraping plate assembly includes a connecting rod, a gear, a chain, and a plurality of slag scraping plates; the gear is connected to the driving device, the chain is sleeved outside the gear, and the plurality of slag scraping plates are arranged on the chain in a preset manner, and the gear is connected to the inner wall of the housing through the connecting rod.

[0018] The present invention is based on an on-line filtration system for removing light impurities from nitriding salt baths, and also provides an on-line filtration method for removing light impurities from nitriding salt baths.

[0019] The working principle and advantages of the present invention are as follows:

[0020] During the continuous nitriding process, although the light impurities float dynamically on the upper part of the salt solution, under the influence of the nitriding process, their distribution and state are extremely unstable and difficult to predict. If targeted dynamic filtration is carried out in a way of predicting the distribution and state of the light impurities, due to the different types and variable properties of the light impurities and different working conditions in the nitriding equipment, very high requirements will be put forward for the prediction equipment and prediction modeling. Therefore, relatively speaking, the existing shutdown filtration method is to take the shutdown of the nitriding equipment after the light impurities accumulate to a certain amount to achieve the stability of the light impurities, avoiding the technical difficulties of the prediction method, and completing the filtration under the state that the light impurities are stable at a certain amount. This method can balance the production efficiency and the difficulty of removing light impurities, but it cannot completely solve the influence of the generation and accumulation of light impurities during the nitriding process on the workpiece quality, and is not applicable to the application scenarios with high requirements for production efficiency.

[0021] To address the above-mentioned existing defects, this solution breaks through the conventional thinking of solving the dynamic floating of light impurities and making dynamic floating predictions. Based on the fact that the salt solution is in a tumbling state during the nitriding process, it ingeniously utilizes the dynamic floating of light impurities itself. Through an air compression and diversion device, it simulates the tumbling state of the salt solution itself and dynamically circulates the salt solution to be filtered to the outside of the nitriding equipment. A stable filtering space is provided for the salt solution to be filtered outside the nitriding equipment. The filtered impurities are collected outside the nitriding equipment, and the filtered salt solution flows back into the nitriding equipment. The dynamic circulation of the entire salt solution adapts to the disturbance of the salt solution in the nitriding equipment and the tumbling state of the nitriding process itself. Therefore, during the dynamic transportation process, it neither interferes with normal production nor makes the state of light impurities become stable and predictable under the control of this system, achieving continuous green, energy-saving, and efficient filtering of light impurities during the workpiece nitriding process and ensuring the workpiece processing quality.

[0022] Compared with the prior art, through the organic combination of a buoyancy monitoring device, an air compression and diversion device, a filtering device, and a collection device, this solution has the following advantages:

[0023] (1) In the environment of the nitriding furnace, due to the presence of impurities, the density of the substances in the furnace varies, and this density difference leads to different buoyancy situations. Therefore, a buoyancy monitoring device is designed to dynamically obtain buoyancy data, and the start and stop of relevant devices are orderly controlled through real-time different buoyancy data, realizing the automated management of the filtering system, greatly reducing the consumption of human resources and the energy-saving and high-efficiency operation of the system.

[0024] (2) The air pressure provided by the air compression device forms a pressure difference in the filter pipe, prompting the nitriding salt bath and the light impurities it carries to smoothly flow towards the filtering device. Moreover, the disturbance caused by the application of air power to the nitriding salt bath is adapted to the disturbance of the salt bath itself when the workpiece is processed in the nitriding salt bath, without interfering with the processing of the workpiece itself. This method not only saves energy but also effectively avoids the negative impact of impurities on the quality of the product infiltration layer due to the increased disturbance, improving the workpiece quality.

[0025] (3) The aperture of the upper layer of the "sandwich" structure filter net, the flat wire net, is close to that of the filter cotton, achieving double filtration. At the same time, the structure of the flat wire net is conducive to the collection of impurities. The lower layer of the flat wire net with a larger aperture prevents the falling of filter cotton debris and prevents secondary pollution of the impurities in the furnace. Moreover, the "sandwich" structure filter net has strong adaptability and flexibility, can select a suitable filter net type according to the nature of the impurities, and can intuitively judge the saturation state of the filter net and whether it needs to be replaced in a timely manner, thus ensuring the filtering efficiency and the continuous operation of the system.

[0026] (4) The unique slag scraping plate structure can automatically concentrate the filtered impurities into the slag collection box, not only simplifying the subsequent cleaning work but also improving the overall efficiency of the system.

[0027] (5) The filtering process of this solution has a relatively low cost, is easy to operate, can effectively remove light impurities, is applicable to nitriding furnaces of different sizes, and brings significant beneficial effects to industrial production. Description of the Drawings

[0028] Figure 1 It is a schematic structural diagram of an on-line filtering system for removing light impurities from nitriding salt bath provided by an embodiment of the present invention;

[0029] Figure 2 It is a schematic structural diagram of the buoyancy monitoring device provided by an embodiment of the present invention;

[0030] Figure 3 It is a schematic principle diagram of the buoyancy monitoring device provided by an embodiment of the present invention;

[0031] Figure 4 It is a schematic structural diagram of the filtering device provided by an embodiment of the present invention;

[0032] Figure 5 It is a schematic diagram of the multi-layer stacked structure of the filter layer provided by an embodiment of the present invention;

[0033] Figure 6 It is a schematic structural diagram of the air compression and diversion device provided by an embodiment of the present invention;

[0034] Figure 7 It is a schematic structural diagram of the collection device provided by an embodiment of the present invention;

[0035] The reference signs in the accompanying drawings of the specification include: float valve 1, crank arm 11, pressure sensor 12, controller 13, bracket 2, housing 21, upper filter screen 22, filter element 23, lower filter screen 24, air compression device 3, compressed air conduit 31, filter pipe 32, driving device 4, gear 41, chain 42, slag scraping plate 43, connecting rod 44, slag collection box 45. Detailed Description of the Invention

[0036] The following is a more detailed description through specific embodiments:

[0037] The embodiment is basically as shown in the attached Figure 1 : An on-line filtering system for removing light impurities from nitriding salt bath, including a buoyancy monitoring device, an air compression and diversion device, a filtering device and a collection device;

[0038] The buoyancy monitoring device is used to monitor the buoyancy data of the nitriding salt bath in the nitriding equipment in real time, and control the air compression and diversion device and the collection device based on the buoyancy data;

[0039] An air compression and diversion device, after starting, introduces air into the nitriding salt bath in the nitriding equipment, and conveys the nitriding salt bath containing light impurities to a filtering device outside the nitriding equipment;

[0040] A filtering device, which is used for multi-layer filtering of the conveyed nitriding salt bath containing light impurities to obtain light impurities and de-impurity nitriding salt bath, and conveys the de-impurity nitriding salt bath back into the nitriding salt bath in the nitriding equipment;

[0041] A collecting device, which is used for scraping and collecting light impurities in a rolling manner.

[0042] Specifically:

[0043] As Figure 2 shown, the buoyancy monitoring device includes a high-precision float ball valve 1. The high-precision float ball valve 1 is electrically connected to a pressure sensor 12 through a crank arm 11. The pressure sensor 12 is electrically connected to a controller 13, and is electrically connected to the air compression and diversion device and the collecting device through the controller 13.

[0044] Among them, the high-precision float ball valve 1 is placed in the nitriding salt bath in the nitriding equipment during use, and can be made of heat-resistant 316 stainless steel. The crank arm 11 can be made of anti-corrosion and heat-resistant 304 stainless steel, and the crank arm 11 can move up and down with the movement of the high-precision float ball valve 1. The controller 13 can be a PLC programmable logic controller.

[0045] In the furnace environment, due to the existence of impurities, the density of the substances in the furnace is different. This density difference will lead to different buoyancy situations, and further make the forces transmitted by the high-precision float ball valve 1 to the pressure sensor 12 through the crank arm 11 different. The controller 13 controls the corresponding devices through the pressure change information transmitted by the pressure sensor 12, and orderly realizes the automatic filtration of this system. As Figure 3 shown is the schematic diagram of starting and stopping the filtration system. The change in pressure converts mechanical motion into an electrical signal to start the filtration system.

[0046] As Figure 4 shown, the filtering device includes a bracket 2; the bracket 2 is installed with a housing 21; the inner cavity of the housing 21 forms a filtering cavity; the bottom of the housing 21 is a grid structure and is completely covered with a filtering layer; the filtering layer has a multi-layer stacked structure.

[0047] Among them, the bracket 2 is used for fixedly connecting the housing 21 and plays a supporting role during use, and can stably support the housing 21 on the nitriding equipment (i.e., the nitriding furnace) during use; in this embodiment, the housing 21 is a basin-like structure with an open top, and its bottom area is smaller than the area of the nitriding furnace furnace mouth, and the area difference can be 0.02 - 0.04 m 2, it can be applied to nitriding furnaces of any size of 300#, 500#, and 800#. It can be understood that the filter layer is connected to the support 2 to form the main filter screen. When in use, the main filter screen is placed on the nitriding furnace.

[0048] As Figure 5 shown, the bottom of the housing 21 completely covers the multi-layer stacked filter layer to strengthen the filtration of impurities in the nitriding salt bath. The multi-layer stacked structure is that the middle layer is at least one filter element 23, and the upper and lower layers of the middle layer are at least one upper filter screen 22 and a lower filter screen 24 respectively; wherein the pore size of the upper filter screen 22 is smaller than the pore size of the lower filter screen 24, and a "sandwich" structure filter screen can be formed. The pore size of the upper filter screen 22 is 2 - 38 μm, the pore size of the lower filter screen 24 is 5 - 72 μm, and the pore size difference is 3 - 70 μm. In this embodiment, it is stacked from a small-pore-size wire mesh, filter cotton, and a large-pore-size wire mesh in sequence from top to bottom. The small-pore-size wire mesh and the large-pore-size wire mesh can be titanium alloy wire meshes. The pore size of the upper titanium alloy wire mesh is smaller than the pore size of the lower titanium alloy wire mesh. The pore size of the upper titanium alloy wire mesh is similar to the pore size of the filter cotton, and the pore size difference is 0 - 10 μm. The filter cotton is any one of aluminosilicate fiber filter cotton, high-aluminum fiber filter cotton, chromium-containing aluminosilicate fiber filter cotton, and mullite fiber filter cotton that is heat-resistant and has a fine fiber spacing to effectively filter impurities and particles in the salt bath. The grid size in the grid structure at the bottom of the housing 21 is adapted to all the pore sizes of the filter layer, ensuring a stable support for the filter layer while not interfering with the downward flow of the liquid filtered by the filter layer back into the nitriding furnace, and at the same time ensuring that the speed and state of the dripping water falling back do not affect the original tumbling state of the nitriding furnace.

[0049] As Figure 6 shown, the air compression and diversion device includes an air compression device 3, a compressed air conduit 31, and a filter pipe 32; the inlet end of the compressed air conduit 31 is connected to the air compression device 3 (only a connection schematic is shown in the figure, and specific effective connections are made according to the actual situation, as long as the functions of this solution can be achieved), and the length of the compressed air conduit 31 meets the requirement that its exhaust port end is placed at a first preset depth h1 below the liquid level of the nitriding salt bath ( Figure 6 shown by the longest dotted line), and the drain port end of the filter pipe 32 is communicated with the filtering device, and the length of the filter pipe 32 meets the requirement that its inlet end is placed at a second preset depth h2 below the liquid level of the nitriding salt bath. Among them, the exhaust port end of the compressed air conduit is communicated with the filter pipe, and the connection point position of the two is determined corresponding to the first preset depth and the second preset depth.

[0050] In this embodiment, both the compressed air duct 31 and the filter duct 32 are Γ-shaped ducts, which are respectively placed above the nitriding furnace. In this embodiment, for the sake of the device's aesthetics, they can be arranged side by side and aligned at the top. In other embodiments, they do not need to be aligned at the top. Generally speaking, the air compression duct enters along the nitriding furnace platform, and the liquid discharge port end of the filter duct should be above the housing. The compressed air duct 31 and the filter duct 32 are fixedly installed on the bracket 2, which can improve the stability of the entire system.

[0051] The intake pipe of the air compression duct 31 ( Figure 6 the horizontal pipe to which the compressed air duct 31 shown belongs) is shorter than the exhaust pipe ( Figure 6 the vertical pipe to which the compressed air duct 31 shown belongs) to accelerate the rapid action of air on the nitriding salt bath. The exhaust pipe is longer to ensure that it can reach the first preset depth below the liquid level of the nitriding salt bath. The length of the intake pipe can be 100 - 200 mm, the length of the exhaust pipe can be 300 - 1200 mm, the pipe diameter is 10 - 15 mm, and the first preset depth h1 (determined by the vertical distance between the liquid level of the horizontally placed nitriding salt bath and the exhaust port end) can be 300 - 1000 mm.

[0052] The liquid inlet pipe of the filter duct 32 ( Figure 6 the vertical pipe to which the filter duct 32 belongs) is longer than the exhaust pipe of the air compression duct. It can be understood that, relative to the liquid level of the nitriding salt bath, the second preset depth h2 is greater than the first preset depth h1. The length of the liquid inlet pipe can be 600 - 1300 mm, the length of the liquid discharge pipe can be 70 - 300 mm, the pipe diameter is 15 - 20 mm, and the second preset depth h2 (determined by the vertical distance between the liquid level of the horizontally placed nitriding salt bath and the liquid inlet end) can be 400 - 1100 mm to achieve the maximum pressure difference between the liquid inlet and the liquid outlet of the filter duct 32. The liquid discharge port end of the filter duct 32 is located above the filter device housing 21. In this embodiment, it is located above the side of the housing 21 away from the slag collection box 45, extending the flow time of the salt liquid in the housing and improving the filtering effect. The height difference between the liquid discharge port end face and the top extension face of the housing 21 is 0 - 50 mm, ensuring that the nitriding salt bath containing light impurities in the nitriding equipment is continuously and efficiently transported to the filter cavity through the filter duct 32.

[0053] As Figure 1 and Figure 7As shown in the figure, the collection device includes a driving device 4, a ring-shaped slag scraping plate assembly controlled by the driving device, and a slag collection box 45; the ring-shaped slag scraping plate assembly is installed in the filtration chamber and above the filtration layer, and the size of the ring-shaped slag scraping plate assembly meets the requirement of contacting the upper surface of the filtration layer under the drive of the driving device 4 according to preset requirements; the slag collection box 45 is installed outside the housing 21, communicated with the filtration layer, and located on the side where impurities outside the housing 21 are scraped out. Since the filtration layer has a strong adsorption capacity, after reasonably controlling the flow rate of the brine entering the filtration chamber, the unfiltered liquid will not overflow into the slag collection box.

[0054] Among them, the ring-shaped slag scraping plate assembly includes a gear 41, a chain 42, a plurality of slag scraping plates 43 and a connecting rod 44; the gear 41 is connected to the driving device 4, the chain 42 is sleeved outside the gear 41, a plurality of slag scraping plates 43 are arranged on the chain 42 in a preset manner, and the gear 41 is connected to the inner wall of the housing 21 through the connecting rod 44, and the connecting rod 44 and the gear 41 are connected through a bearing structure. In this embodiment, the size of the slag scraping plate 55 is 10cm * 2cm, and the thickness is 0.2cm, and it is evenly embedded between the chain plates of the chain 54. The preset requirement for contacting the upper surface of the filtration layer according to the preset requirement is that in the shutdown state, the distance between the bottom surface of the slag scraping plate and the upper surface of the filtration layer is between 0.05 - 0.2cm, so as to ensure the smoothness of the rolling slag scraping process after the upper surface of the filtration layer filters out light impurities.

[0055] All the brine in the nitriding furnace includes light impurities with a relatively small density and dynamically suspended above the brine.

[0056] Applying the above online filtration system for removing light impurities from nitriding salt bath, this solution also provides an online filtration method for removing light impurities from nitriding salt bath, and the method includes:

[0057] Device preparation, the high-precision float valve 1 is placed inside the nitriding salt bath.

[0058] The filtration device is placed on the furnace mouth of the nitriding equipment. The bottom area of the housing 21 is less than the furnace mouth area of the 800# nitriding furnace, which does not affect the nitriding treatment of the workpieces in the 800# nitriding furnace. In other embodiments, the bottom area of the housing 21 is less than the furnace mouth area of any size of nitriding furnace such as 300#, 500#, and 800# to adapt to nitriding furnaces of any size. The filtration layer uses a 400-mesh small-aperture titanium alloy wire mesh, a "sandwich" structure filter screen containing aluminosilicate fiber filter cotton and a 200-mesh large-aperture titanium alloy wire mesh, and completely covers the bottom of the housing 21.

[0059] The exhaust port end of the compressed air conduit 31 is placed at a first preset depth below the liquid level of the nitriding salt bath; the inlet end of the filter pipe 32 is placed at a second preset depth below the liquid level of the nitriding salt bath, and the exhaust port end of the compressed air pipe 31 is connected to the filter pipe.

[0060] After the air compression and diversion device is started, air is introduced into the nitriding salt bath in a preset manner, and the nitriding salt bath containing light impurities is transported to a filtering device outside the nitriding equipment. The preset manner is that the flow rate of air introduced through the compressed air pipe 31 is 0.0056 - 0.11 m 3 / min, and the flow velocity is 31 - 1392 m / min; the flow rate of the nitriding salt bath containing light impurities transported through the filtering pipe 32 is 0.028 - 0.55 m 3 / h, and the filtering speed is 1.5 - 51 m / min. In other embodiments, without being limited to the above data range, as long as the lengths of the compressed air conduit 31 and the filtering pipe 32, the depth below the liquid level of the nitriding salt bath, and the corresponding parameters of the preset manner are reasonably designed, and with various data coordinated designs, based on the pressure effect, it can effectively achieve the entire process of introducing air through the compressed air pipe 31 and transporting the nitriding salt bath through the filtering pipe 32.

[0061] The rate of rolling out light impurities is set to 2 - 4 m / min.

[0062] After the device is ready, it enters the online filtering state:

[0063] The buoyancy monitoring device continuously monitors the buoyancy data of the nitriding salt bath in the nitriding equipment, and controls the start and stop of the air compression and diversion device and the collection device based on the buoyancy data; when the buoyancy data reaches the preset value representing the opening, the air compression and diversion device and the collection device are simultaneously started. Specifically, when impurities appear in the salt liquid, the density increases, the position change of the high-precision float valve 1 drives the crank arm 11 to move, the pressure sensor 12 is connected to the crank arm 11, converts the above mechanical movement into an electrical signal, and the PLC programmable logic controller 13 receives the electrical signal from the pressure sensor 12 and starts the filtering system according to the preset logic program to realize the online automatic start of the filtering system.

[0064] After the air compression and diversion device 3 is started, air is introduced through the compressed air conduit 31 according to the corresponding parameters in the preset manner. Based on the gas pressure effect, the nitriding salt bath containing light impurities is transported to the filtering device outside the nitriding equipment through the filtering pipe 32 according to the corresponding preset parameters, and specifically flows into the filtering cavity.

[0065] The filtering device completely covers the "sandwich" structure filter screen at the bottom of the housing 21 to multi-filter the transported nitriding salt bath containing light impurities, obtaining light impurities and the nitriding salt bath without impurities. The light impurities remain on the surface of the upper filter screen of the filter layer after filtration, and the nitriding salt bath without impurities is directly transported back into the nitriding salt bath in the nitriding equipment located below the filtering device through the lower filter screen.

[0066] After the collection device driving device 4 (motor) starts, it drives the gear 41 to rotate. The rotation of the gear 41 further causes the chain 42 to move, so that the slag scraping plate 43 embedded on the chain plate scrapes on the surface of the upper filter screen of the "sandwich" structure at a preset rate to scrape the slag. The light impurities are collected into the slag collection box 45 under the circular push of the slag scraping plate 43.

[0067] When the buoyancy data reaches the preset value representing the stop, that is, the impurity density decreases, the position change of the high-precision floating ball valve 1 drives the crank 11 to move. The pressure sensor 12 is connected to the crank 11 and converts the above mechanical movement into an electrical signal. The PLC programmable logic controller 13 receives the electrical signal from the pressure sensor 12, first closes the air compression diversion device, and then closes the collection device, so that the nitriding salt bath is effectively filtered, thereby effectively controlling the operation state of the entire online filtration system by monitoring the dynamically changing buoyancy data. If the collection device is closed first, after the salt bath of the air compression diversion device flows into the filtration device, the collection device is in a stopped state, and the impurities will not be collected, and the energy-saving and efficient filtration cooperation cannot be achieved.

[0068] An on-line ensuring filtration system and method for removing light impurities from nitriding salt bath, compared with the prior art, through the organic combination of a buoyancy monitoring device, an air compression diversion device, a filtration device and a collection device, realizes a continuous on-line automatic filtration process without disturbing production, achieves the filtration effect of green, environmental protection and efficient removal of light impurities from the nitriding salt bath, significantly reduces the interference of light impurities on the process, effectively alleviates the aging speed of the nitriding salt bath, reduces the thickness of the loose layer of the workpiece, increases the hardness, and improves the processing quality of the workpiece during the nitriding process. Specifically, in the environment of the nitriding furnace, due to the existence of impurities, the density of the substances in the furnace is different, and this density difference will lead to different buoyancy situations. Therefore, a buoyancy monitoring device is designed to dynamically obtain buoyancy data, and the start and stop of relevant devices are orderly controlled through different real-time buoyancy data, realizing the automatic management of the filtration system, greatly reducing the consumption of human resources and the energy-saving and high-efficiency operation of the system. The air pressure difference is formed in the filter pipe by using the air power provided by the air compressor, which promotes the salt solution and the light impurities carried by it to smoothly flow to the filtration device, and the disturbance caused by the use of air power to the salt bath is adapted to the disturbance of the salt bath itself during the processing of the workpiece in the nitriding salt bath, without disturbing the processing of the workpiece itself. This method not only saves energy, but also can effectively avoid the negative impact of impurities on the quality of the product penetration layer due to the increased disturbance, improving the quality of the workpiece. The aperture of the upper layer of the "sandwich" structure filter screen is close to that of the filter cotton, realizing double filtration. At the same time, the structure of the wire mesh is conducive to the collection of impurities. The lower layer of the wire mesh with a larger aperture prevents the falling of filter cotton debris and prevents secondary pollution of impurities in the furnace. Moreover, the "sandwich" structure filter screen has strong adaptability and flexibility, can select the appropriate filter screen type according to the nature of the impurities, and can intuitively judge the saturation state of the filter screen and whether it needs to be replaced in time, thus ensuring the filtration efficiency and the continuous operation of the system. The unique slag scraping plate structure can automatically collect the filtered impurities into the slag collection box, which not only simplifies the subsequent cleaning work, but also improves the overall efficiency of the system. The filtration process cost of this solution is relatively low, easy to operate, can effectively remove light impurities, is applicable to nitriding furnaces of different sizes, and brings significant beneficial effects to industrial production.

[0069] Embodiment 2

[0070] Different from the first embodiment, in a nitriding furnace with a capacity of 0.028 m3 and a volume of 300#, the temperature inside the furnace is 560 °C. Due to the input of air, the inside of the furnace is always in a state of uniform tumbling. Light impurities such as unreacted metal oxide particles on the surface rust of the workpiece may always be suspended in the salt bath, as well as external dust, etc. When impurities appear in the salt bath inside the nitriding furnace, the density of the salt liquid increases, the position of the high-precision floating ball changes, and the pressure sensor senses the swing of the crank arm, converting the digital signal into an electrical signal and feeding it back to the PLC programmable controller. Then, according to the preset logic program, the air compression diversion system and the filtration system are simultaneously turned on. The air compression conduit 31 introduces air into the nitriding salt bath. The air is replaced every 5 minutes. The radius of the air conduit is 0.005 m, the air flow rate is 0.0056 m3 / min, and the flow velocity is 71 m / min. The filter pipe transports the nitriding salt liquid containing light impurities to the filter chamber covered with a "sandwich" structure filter screen at the bottom. The filter pipe filters once per hour. The radius of the filter pipe is 0.0075 m, the flow rate is 0.028 m3 / h, and the filtration speed is 2.6 m / min. The drive motor of the collection device drives the gear to rotate, which in turn moves the slag scraping plate on the chain. The rate of rolling out the light impurities is set to 2 - 4 m / min, moving the impurities from the upper surface of the "sandwich" filter screen to the slag collection box, finally enabling the light impurities in the entire nitriding salt bath to be filtered in a timely manner without affecting the continuous production of the process inside the furnace.

[0071] The above are only embodiments of the present invention. Specific structures and common knowledge such as characteristics that are well-known in the art are not described in detail here. Those of ordinary skill in the art know all the common technical knowledge in the technical field to which the invention belongs before the application date or the priority date, can know all the existing technologies in this field, and have the ability to apply the conventional experimental means before this date. Those of ordinary skill in the art can, under the inspiration given in this application, combine their own abilities to improve and implement this solution. Some typical well-known structures or well-known methods should not become obstacles for those of ordinary skill in the art to implement this application. It should be noted that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can still be made, and these should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent.

Claims

1. An online filtration system for removing light impurities from a nitriding salt bath, characterized in that: It includes a buoyancy monitoring device, an air compression guide device, a filtering device and a collecting device; A buoyancy monitoring device is used to monitor the buoyancy data of the nitriding salt bath of the nitriding equipment in real time, and to control the start and stop of the air compression guide device and the collection device based on the buoyancy data; An air compression guide device is used to introduce air into the nitriding salt bath of the nitriding equipment after startup, and to transport the nitriding salt bath containing light impurities to a filtering device outside the nitriding equipment; A filtering device, used for multi-layer filtering of the transported nitriding salt bath containing light impurities to obtain light impurities and a denitriding salt bath, and transporting the denitriding salt bath back to the nitriding salt bath in the nitriding equipment; The collecting device is used to scrape out light impurities in a rolling manner and collect them after starting.

2. The online filtration system for removing light impurities in a nitride salt bath according to claim 1, characterized in that: The buoyancy monitoring device comprises a float valve, the float valve is electrically connected to a pressure sensor through a crank arm, the pressure sensor is electrically connected to a controller, and the pressure sensor is electrically connected to an air compression guide device and a collection device through the controller.

3. The online filtration system for removing light impurities in a nitride salt bath according to claim 1, characterized in that: The filtering device comprises a bracket; a shell is installed on the bracket; the inner cavity of the shell forms a filtering cavity; the bottom of the shell is a grid structure and is completely covered with a filtering layer; the filtering layer has a multi-layer stacked structure.

4. The online filtration system for removing light impurities from a nitride salt bath according to claim 3, characterized in that: The multi-layer stacked structure is that the middle layer is at least one layer of filter element, and the upper layer and the lower layer of the middle layer are both at least one layer of filter screen, wherein the pore size of the filter screen located in the upper layer is smaller than the pore size of the filter screen located in the lower layer.

5. The online filtration system for removing light impurities in a nitride salt bath according to claim 1, characterized in that: The air compression guide device includes an air compression device, a compressed air conduit and a filter tube; the air inlet end of the compressed air conduit is connected to the air compression device, and the length of the compressed air conduit is sufficient to place its exhaust port end at a first preset depth below the surface of the nitride salt bath when in use; the liquid discharge port end of the filter tube is connected to the filter device, and the length of the filter tube is sufficient to place its liquid inlet end at a second preset depth below the surface of the nitride salt bath when in use; wherein the exhaust port end of the compressed air conduit is connected to the filter tube.

6. The online filtration system for removing light impurities in a nitride salt bath according to claim 1, characterized in that: The collecting device includes a driving device, an annular scraper assembly controlled by the driving device, and a slag collecting box; the annular scraper assembly is installed in the filter cavity and is located above the filter layer, and the size of the annular scraper assembly meets the contact with the upper surface of the filter layer according to the preset requirements under the drive of the driving device; The slag collecting box is installed on the outside of the shell, communicated with the filter layer, and is located on the side where impurities outside the shell are scraped out.

7. The online filtration system for removing light impurities in a nitriding salt bath according to claim 6, characterized in that: The annular scraper plate assembly includes a connecting rod, a gear, a chain and a plurality of scraper plates; the gear is connected to the driving device, the chain is sleeved on the outside of the gear, the plurality of scraper plates are arranged on the chain in a preset manner, and the gear is connected to the inner wall of the shell through the connecting rod.

8. An online filtration method for removing light impurities from a nitriding salt bath, characterized in that: An online filtration system for removing light impurities from a nitride salt bath as described in any one of claims 1 to 7, the method comprising: The buoyancy monitoring device monitors the buoyancy data of the nitriding salt bath in the nitriding equipment in real time, and controls the start and stop of the air compression guide device and the collection device based on the buoyancy data; After the air compression guide device is started, air is introduced into the nitriding salt bath in a preset manner, and the nitriding salt bath containing light impurities is transported to the filtering device outside the nitriding equipment; The filtering device filters the transported nitriding salt bath containing light impurities in multiple layers to obtain light impurities and a denitriding salt bath, and transports the denitriding salt bath back to the nitriding salt bath in the nitriding equipment; After the collecting device is started, light impurities are scraped out and collected in a rolling manner.

9. The online filtration method for removing light impurities in a nitriding salt bath according to claim 8, characterized in that: The filter device is placed on the furnace mouth of the nitriding equipment; the exhaust port end of the compressed air conduit of the air compression guide device is placed at a first preset depth below the nitriding salt bath liquid surface, and the liquid inlet end of the filter tube is placed at a second preset depth below the nitriding salt bath liquid surface.

10. The online filtration method for removing light impurities in a nitriding salt bath according to claim 8, characterized in that: When the buoyancy data reaches a preset value indicating opening, the air compression guide device and the collection device are opened simultaneously; when the buoyancy data reaches a preset value indicating stopping, the air compression guide device is closed first, and then the collection device is closed.

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