Foam metal material production method based on array pulsating airflow

Abstract

The invention discloses a foam metal material production method based on array pulsating airflow. The foam metal material production method comprises the following steps that firstly, molten metal liquid is placed in a molten liquid pool; 2, pulse frequency is set according to the target bubble diameter and the molten metal property, and the phase difference between adjacent nozzles is calculated based on the pulse frequency; 3, electromagnetic valves of all the nozzles are controlled to be switched on and switched off through a PCL controller, so that the multiple nozzles arranged in an array jet high-pressure gas into the melt pool according to the set pulsation frequency and the set phase difference; if the proportion of the bubbles with the diameters exceeding the set threshold value range is larger than or equal to a set first threshold value, a PID controller is adopted to control the air pressure and flow of the high-pressure gas to adjust the diameters of the bubbles; if the bubble merging rate exceeds a set second threshold value, the phase difference division number is reduced, and the time interval of the high-pressure airflow sprayed by the two adjacent nozzles is increased; and 5, guiding the bubbles to gather by utilizing a discharging guide device to form a foam metal material, and continuously discharging.

Description

Technical Field

[0001] The present invention belongs to the technical field of porous foam materials, and specifically relates to a production method of metal foam materials based on array pulsating air flow. Background Art

[0002] Aluminum foam is made by adding additives to pure aluminum or aluminum alloy and then through a foaming process, and it has both metal and bubble characteristics. Aluminum foam has the advantages of low density, strong high-impact absorption ability, high temperature resistance, strong fire resistance, corrosion resistance, sound insulation and noise reduction, low thermal conductivity, high electromagnetic shielding performance, strong weather resistance, filtering ability, easy processing, easy installation, high forming accuracy, and can be surface coated, etc., and has great market application potential in the fields of railway passenger cars, military, construction, automobiles, decoration, aerospace, aviation, ships, etc. Aluminum foam can be divided into open-cell aluminum foam and closed-cell aluminum foam from the pore structure, and among them, closed-cell aluminum foam has a wider application. The main preparation method of closed-cell aluminum foam is the melt blowing method.

[0003] In the melt blowing process, gas is directly injected into liquid aluminum or aluminum alloy through a blowing head, which has the advantages of low cost and continuous production. However, in the existing blowing method, all bubbles are generated in one or more groups of planar pores, and the gas outlet is uneven and uncontrollable, resulting in different bubble sizes and difficult to accurately control the pore diameter, and finally the pore diameter distribution of the product is uneven.

[0004] The biggest problem of the planar pores in the existing blowing method is that the bubble detachment speed is slow, which greatly affects the production efficiency and the control of the bubble pore diameter. In order to control the bubble pore diameter and improve the production efficiency, the rotary spray blowing method and the reciprocating spray blowing method are proposed. The rotary spray blowing method is to drive the blowing head to rotate to achieve gas dispersion, and the reciprocating spray blowing method disperses bubbles by driving the blowing head to reciprocate. However, the rotary spray blowing method and the reciprocating spray blowing method cause greater disturbance to the melt, and the bubble detachment conditions are quite different, and the pore uniformity of the prepared aluminum foam is poor. In particular, the interference caused by vibration makes a large number of bubbles merge, further exacerbating the bubble non-uniformity and control difficulties.

[0005] In addition, the pore size plays an important role in the performance of metal foam materials. Research has found that when the pore size decreases, the pores tend to be spherical and the structure is more uniform; the liquid film area of the small-pore-diameter aluminum foam decreases, which increases the liquid film stability, the pores are more stable, and it is more likely to flow and deform during hot processing, which is beneficial to the secondary processing of aluminum foam; its mechanical properties will also be greatly improved; the pore collapse phenomenon that occurs during the forming process will also be improved, which is beneficial to the increase of the foaming height, so that large-sized aluminum foam can be prepared, further promoting the industrialization of aluminum foam. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a production method of foam metal material based on array pulsating air flow, which uses pulsating air flow arranged in an array to generate bubbles, can not only control the cell size, but also reduce the bubble coalescence rate and improve the uniformity of bubble distribution.

[0007] To achieve the above purpose, the present invention provides the following technical solutions:

[0008] A production method of foam metal material based on array pulsating air flow is realized by using a foam metal material production system. The foam metal material production system includes:

[0009] A molten metal pool, the upper end of the molten metal pool is open and used to hold molten metal;

[0010] A bubble generating device for generating bubbles;

[0011] A discharge guiding device, which is arranged above the molten metal pool and used to guide the continuous discharge of the formed foam metal material;

[0012] The bubble generating device includes a bubble generator and a bubble control system; the bubble generator is installed in the molten metal pool, and the bubble generator includes a plurality of nozzles arranged in an array, and the nozzles are used to intermittently inject gas in the vertically upward direction; a high-pressure gas pipe is connected to the nozzles, and a solenoid valve for controlling the opening and closing of the nozzles is installed on the high-pressure gas pipe; the bubble control system includes a PLC controller for controlling the on-off frequency and duty cycle of the solenoid valve, and the PLC controller controls the adjacent nozzles to inject gas to form bubbles according to the set phase difference;

[0013] The production method of the foam metal material includes the following steps:

[0014] Step 1: Place the molten metal in the molten metal pool;

[0015] Step 2: Combine the physical properties of the metal liquid and the structural dimensions of the nozzles to construct a bubble generation model under pulsating air flow, obtain the relationship between the pulsating frequency, the volume of gas injected by each nozzle excitation and the bubble diameter, and calculate the phase difference between adjacent nozzles based on the pulsating frequency;

[0016] Step 3: Based on the target bubble diameter, set the preliminary pulsating frequency and preliminary gas volume;

[0017] Step 4: Control the on-off of the solenoid valves of each nozzle through the PCL controller, so that a plurality of nozzles arranged in an array inject gas with a preliminary gas volume into the molten metal pool according to the preliminary pulsating frequency and the set phase difference to form bubbles in the metal liquid;

[0018] Step 5: Detect the bubble diameter:

[0019] If the proportion of bubbles with diameters exceeding the set threshold range is greater than or equal to the set first threshold, the PLC controller is used to control the time interval between each excitation of the nozzle to adjust the volume of gas injected into the molten metal until the proportion of bubbles with diameters exceeding the set threshold range is less than the set first threshold;

[0020] If the bubble coalescence rate exceeds the set second threshold, the pulsation frequency is increased to inhibit bubble coalescence;

[0021] Step Six: The solenoid valves of each nozzle are respectively controlled by the PCL controller to be turned on and off, so that a plurality of nozzles arranged in an array inject gas with a corrected gas volume into the molten pool according to the corrected pulsation frequency and the set phase difference, and bubbles are formed in the molten metal;

[0022] Step Seven: The discharge guiding device is used to guide the bubbles to gather to form a foam metal material and continuously discharge the material; during the continuous discharge of the foam metal material, Steps Five and Six are cyclically executed to keep the bubble diameter within the set threshold range.

[0023] Further, the distance between two adjacent nozzles is 1.5 - 2 times the target bubble diameter, and the phase difference between the gases ejected by two adjacent nozzles is 90° - 180°.

[0024] Further, a buffer tank is provided on the high-pressure gas pipe, and the buffer tank is used to suppress the pressure oscillation caused by the air pressure fluctuation.

[0025] Further, the bubble generation model under pulsating air flow is:

[0026]

[0027] where: D b is the bubble diameter; k is the correction coefficient; V g is the volume of gas injected by each excitation of the nozzle; σ is the surface tension of the molten metal; f is the pulsation frequency; η is the viscosity of the molten metal; d0 is the aperture of the nozzle.

[0028] Further, the bubble generator includes an isolation chamber and a gas channel. The nozzle array is installed on the top surface of the isolation chamber, and the solenoid valve is installed inside the isolation chamber. The gas channel extends from an opening above the molten pool into the molten pool and is connected to the isolation chamber. A ventilation channel is provided in the gas channel corresponding to each high-pressure gas pipe one by one. A first cooling water jacket for controlling the temperature is provided inside the isolation chamber and in the gas channel. Or, the bubble generator includes a mounting seat fixedly installed on the bottom surface of the molten pool. The nozzle is installed inside the mounting seat, and a perforation for passing through the high-pressure gas pipe is provided on the bottom surface of the molten pool. The solenoid valve is installed on the high-pressure gas pipe and is located outside the molten pool. A second cooling water jacket for controlling the temperature is provided outside the solenoid valve.

[0029] Further, the discharge guiding device includes a first guiding portion and a second guiding portion arranged oppositely. An outlet guiding channel for the foam metal material to be formed and discharged is formed between the first guiding portion and the second guiding portion. A bubble guiding plate for guiding the upward floating direction of the bubbles is provided below the outlet guiding channel.

[0030] Further, first guiding rollers and second guiding rollers are respectively arranged at intervals on the opposite sides of the first guiding portion and the second guiding portion facing each other. A first guiding belt is sleeved on the first guiding rollers, and a second guiding belt is provided on the second guiding rollers.

[0031] Further, a third water-cooled jacket for cooling and forming the foam metal material is provided inside the first guiding portion and the second guiding portion. The third water-cooled jacket controls the cooling rate of the foam metal material to be 10 - 50 °C / s.

[0032] Further, the upper computer is connected to the PLC controller, and:

[0033] When the proportion of bubbles with a diameter exceeding the set threshold range is greater than or equal to the set first threshold, the PLC controller controls the time interval of each excitation of the nozzle through the solenoid valve to adjust the volume of gas injected into the molten metal until the proportion of bubbles with a diameter exceeding the set threshold range is less than the set first threshold.

[0034] When the bubble coalescence rate exceeds the set second threshold, the PLC controller controls the nozzle to increase the pulsation frequency through the solenoid valve to inhibit bubble coalescence.

[0035] Further, at least one of the first guiding portion and the second guiding portion is provided with a high-temperature resistant window. The camera collects the surface image of the foam metal material in the outlet guiding channel through the high-temperature resistant window. First bases and second bases are respectively provided at the bottoms of the first guiding portion and the second guiding portion. The high-temperature resistant window is provided on at least one of the first base and the second base.

[0036] The beneficial effects of the present invention are as follows:

[0037] The production method of the metal foam material based on the array pulsating air flow of the present invention arranges a plurality of nozzles in an array in the bubble generator, and intermittently injects gas in the direction of vertically upward by the nozzles. The gas intermittently injected by the nozzles forms a pulsating air flow in the molten pool. After the injected gas enters the molten pool, bubbles are formed in the molten metal. By constructing a bubble generation model under the pulsating air flow, the influence relationship between the bubble diameter and the pulsating frequency and the volume of gas injected by each excitation of the nozzle can be obtained. In this way, during the continuous production process of the metal foam material, by dynamically controlling the pulsating frequency to control the bubble diameter and dynamically controlling the volume of gas injected by each excitation of the nozzle to control the bubble coalescence rate, the amount of gas injected into the molten pool each time can be accurately controlled, making the diameter distribution of the bubbles more uniform. In summary, the production method of the metal foam material based on the array pulsating air flow of the present invention uses the pulsating air flow arranged in an array to generate bubbles, which can not only achieve the control of the cell size, but also reduce the bubble coalescence rate and improve the uniformity of the bubble distribution. Description of the Drawings

[0038] In order to make the objectives, technical solutions, and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration:

[0039] Figure 1 It is a schematic structural diagram of Embodiment 1 of the production system of the metal foam material based on the array pulsating air flow of the present invention;

[0040] Figure 2 For Figure 1 the enlarged view of Area A;

[0041] Figure 3 It is a schematic structural diagram of Embodiment 2 of the production system of the metal foam material based on the array pulsating air flow of the present invention;

[0042] Figure 4 For Figure 3 the enlarged view of Area B;

[0043] Figure 5 It is the surface image of the collected metal foam material.

[0044] Explanation of the Reference Numerals in the Drawings:

[0045] 10 - Melting pool; 11 - Bubble; 12 - Molten metal; 13 - Foamed metal material; 21 - Nozzle; 22 - High-pressure gas pipe; 23 - Solenoid valve; 24 - PLC controller; 25 - Isolation chamber; 26 - Gas channel; 27 - Mounting seat; 28 - Second cooling water jacket; 31 - First guiding part; 311 - First base; 32 - Second guiding part; 321 - Second base; 33 - Discharge guiding channel; 34 - First guiding roller; 35 - First guiding belt; 36 - Second guiding roller; 37 - Second guiding belt; 38 - Tool holder; 39 - Cutting tool; 40 - Bubble guiding plate; 41 - High-temperature resistant window; 51 - Host computer; 52 - Camera. Detailed implementation mode

[0046] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the embodiments cited are not intended to limit the present invention.

[0047] Embodiment 1

[0048] As Figure 1 shown, the foamed metal material production system based on the array pulsating air flow in this embodiment includes a melting pool 10, a bubble generating device and a discharge guiding device. Specifically, the upper end of the melting pool 10 is open and used to accommodate the molten metal 12; the bubble generating device is used to generate bubbles 11; the discharge guiding device is arranged above the melting pool 10 and is used to guide the continuous discharge of the formed foamed metal material.

[0049] In this embodiment, the bubble generating device includes a bubble generator and a bubble control system. Specifically, the bubble generator is installed in the molten pool 10, and the bubble generator includes a plurality of nozzles 21 arranged in an array. The nozzles 21 are used to intermittently eject gas in the vertically upward direction. In this embodiment, the nozzles 21 are arranged in a honeycomb array. Of course, in some other embodiments, the nozzles 21 can also be arranged in a rectangular array, which will not be elaborated here. A high-pressure gas pipe 22 is connected to the nozzles 21 of this embodiment, and a solenoid valve 23 for controlling the opening and closing of the nozzles 21 is installed on the high-pressure gas pipe 22. In this way, by using the opening and closing action of the solenoid valve 23, the amount of gas ejected into the molten pool 10 by the nozzles 21 each time can be accurately controlled, and thus bubbles 11 with a uniform size distribution can be formed in the molten metal. Correspondingly, the bubble control system of this embodiment includes a PLC controller 24 for controlling the on-off frequency and duty cycle of the solenoid valve 23. The PLC controller 24 controls adjacent nozzles 21 to eject gas to form bubbles 11 according to the set phase difference. That is, in this embodiment, on the one hand, the PLC controller 24 controls the duty cycle of each solenoid valve 23 to accurately control the amount of gas ejected into the molten pool 10 by the nozzles 21 each time; on the other hand, it also needs to control the phase difference of gas ejection between different nozzles 21, so that different nozzles 21 eject gas in sequence according to the set order, which can not only make the bubbles form continuously, but also increase the interval between the bubbles 11 and reduce the merging rate of the bubbles 11.

[0050] In this embodiment, the nozzles are made of materials with high temperature resistance, corrosion resistance, and non-affinity with aluminum liquid, such as nickel-based superalloys, tungsten alloys, or ceramics, to ensure reliable long-term use in aluminum liquid. The nozzles are designed in a pointed shape to ensure that the detachment time of the ejected bubbles is significantly less than one pulse period (e.g., less than or equal to 25% of the period).

[0051] In the preferred embodiment of this embodiment, the distance between two adjacent nozzles 21 is equal to 1.5 - 2 times the target bubble diameter, which can not only increase the distance between the bubbles to reduce the merging rate, but also improve the concentration degree of the bubble generation area, so as to facilitate guiding the bubbles to the position of the discharge guiding device.

[0052] In the preferred embodiment of this embodiment, the phase difference of gas ejection between two adjacent nozzles 21 is 90° - 180°, which can increase the distance between the bubbles formed by the gas ejection of two adjacent nozzles 21 in the vertical direction and further reduce the merging rate of the bubbles.

[0053] In the preferred embodiment of this embodiment, a buffer tank (not shown in the figure) is provided on the high-pressure gas pipe 22, and the buffer tank is used to suppress the pressure oscillation caused by the air pressure fluctuation.

[0054] In this embodiment, the bubble generator includes an isolation chamber 25 and a gas channel 26. The nozzle 21 is array-mounted on the top surface of the isolation chamber 25, and the solenoid valve 21 is installed inside the isolation chamber 25. The isolation chamber 25 mainly provides a relatively independent space for the installation and operation of components such as the solenoid valve 21 to isolate the molten metal in the molten metal pool 10. The gas channel 26 of this embodiment extends from the upper opening of the molten metal pool 10 into the molten metal pool 10 and is connected to the isolation chamber 25. In this embodiment, an air vent channel (not shown in the figure) is provided in the gas channel 26 corresponding to each high-pressure gas pipe 22 one by one, that is, each high-pressure gas pipe 22 is connected to the corresponding air vent channel to independently supply high-pressure gas to each high-pressure gas pipe 22. Of course, in some other embodiments, the gas channel 26 is used to introduce high-pressure gas into the isolation chamber 25, and the high-pressure gas pipe 22 is connected to the isolation chamber 25. That is, the isolation chamber 25 also serves as a pressure vessel and stores high-pressure gas at this time. When the solenoid valve 21 is opened, the high-pressure gas is introduced into the nozzle 21 through the high-pressure gas pipe 22 and sprayed into the molten metal pool 10. Of course, the isolation chamber 25 can also function as a buffer tank at this time, capable of balancing pressure fluctuations.

[0055] Specifically, in order to avoid the influence of the high-temperature environment on the solenoid valve 21 and the bubble control system, a first cooling water jacket for controlling the temperature is provided in the isolation chamber 25 and the gas channel 26 in this embodiment. In this embodiment, the nozzle 21 is made of silicon carbide or alumina ceramic, which can meet the use requirements of the high-temperature environment. Preferably, a water-cooled jacket can be provided on the outer wall of each nozzle 21 to further control the temperature of the nozzle 21. In this embodiment, the solenoid valve 21 uses a high-temperature solenoid valve, which can meet the use requirements of the high-temperature environment.

[0056] The discharge guiding device of this embodiment includes a first guiding part 31 and a second guiding part 32 arranged oppositely. A discharge guiding channel 33 for the forming and discharging of the foam metal material is formed between the first guiding part 31 and the second guiding part 32. A bubble guiding plate 40 for guiding the floating position of the bubbles is provided below the discharge guiding channel. In this embodiment, first guiding rollers 34 and second guiding rollers 36 are respectively arranged at intervals on the opposite sides of the first guiding part 31 and the second guiding part 32. A first guiding belt 35 is sleeved on the first guiding roller 34, and a second guiding belt 37 is provided on the second guiding roller 36. In this embodiment, the distance between the first guiding part 31 and the second guiding part 32 is adjustable to control the thickness of the formed foam metal material.

[0057] In this embodiment, a cutting device for cutting the foam metal material is provided on the discharge guiding device. The cutting device is above the discharge guiding device in the vertical direction. The cutting device can be arranged at the outlet of the discharge guiding channel 33. After the foam metal material comes out from the outlet of the discharging device, the cutting device can cut the foam metal material. In some embodiments, the cutting device includes a tool holder 38 and a cutting tool 39. The tool holder 38 is installed on the top surface of the first guiding portion 31. When the cutting tool 39 works, it moves horizontally relative to the first guiding portion 31 to cut the foam metal material. In addition, during the process of the cutting tool 39 cutting the foam metal material, a driving mechanism arranged in the tool holder 38 also drives the cutting tool 39 to move synchronously with the foam metal material, so as to make the cut surface smoother, and the cutting tool 39 will not affect the continuous discharging of the foam metal material.

[0058] In the preferred embodiment of this embodiment, a third water-cooling jacket (not shown in the figure) for cooling and shaping the foam metal material is provided in the first guiding portion 31 and the second guiding portion 32. In this embodiment, the third water-cooling jacket controls the cooling rate of the foam metal material to be 10 - 50 °C / s, which can accelerate the rate of the foam metal material and improve the production efficiency.

[0059] A monitoring system for monitoring the bubble size is provided on the discharge guiding device of this embodiment. The monitoring system includes a host computer 51 and a camera 52. The camera 52 collects the surface image of the foam metal material 13 in the discharge guiding channel 33, as Figure 5 shown. The host computer 51 statistically analyzes the size distribution of the bubbles and the bubble coalescence rate according to the collected surface image of the foam metal material 13. Specifically, the method for judging bubble coalescence is: if the diameter of the bubble 11 is greater than 125% of the target bubble diameter, it indicates that the bubble is obtained by the coalescence of at least two bubbles, and then the bubble coalescence rate is calculated.

[0060] The host computer 51 is connected to the PLC controller 24. After obtaining the size distribution of the bubbles and the bubble coalescence rate through the host computer 51, the bubble size is dynamically adjusted through the PLC controller 24. Specifically:

[0061] When the proportion of bubbles with diameters exceeding the set threshold range is greater than or equal to the set first threshold, the PLC controller 24 controls the time interval of each excitation of the nozzle 21 through the solenoid valve 23 to adjust the volume of gas injected into the molten metal until the proportion of bubbles with diameters exceeding the set threshold range is less than the set first threshold; specifically, when the proportion of bubbles with diameters greater than the set threshold range is greater than or equal to the set first threshold, the PLC controller 24 controls the nozzle 21 through the solenoid valve 23 to reduce the time interval of each excitation to adjust the volume of gas injected into the molten metal until the proportion of bubbles with diameters exceeding the set threshold range is less than the set first threshold; when the proportion of bubbles with diameters less than the set threshold range is greater than or equal to the set first threshold, the PLC controller 24 controls the nozzle 21 through the solenoid valve 23 to increase the time interval of each excitation to adjust the volume of gas injected into the molten metal until the proportion of bubbles with diameters exceeding the set threshold range is less than the set first threshold; ultimately, the size of the bubbles 11 is maintained within the set threshold range.

[0062] When the merging rate of the bubbles 11 exceeds the set second threshold, the PLC controller 24 controls the nozzle 21 through the solenoid valve 23 to increase the pulsation frequency to inhibit the merging of bubbles.

[0063] Specifically, at least one of the first guiding portion 311 and the second guiding portion 32 is provided with a high-temperature resistant viewing window 41, and the camera 52 collects the surface image of the foamed metal material 13 in the discharge guiding channel 33 through the high-temperature resistant viewing window 41. In a preferred embodiment of the present embodiment, the bottoms of the first guiding portion 31 and the second guiding portion 32 are respectively provided with a first base 311 and a second base 321, and at least one of the first base 311 and the second base 321 is provided with a high-temperature resistant viewing window 41. In this embodiment, the high-temperature resistant viewing window 41 is arranged on the first base 311, that is, the high-temperature resistant viewing window 41 is arranged on the first guiding portion 31. By arranging the high-temperature resistant viewing window 41 on the first base 311 and / or the second base 321, the monitoring position can be closer to the bubble generator 20, and the detection response speed can be improved.

[0064] Embodiment 2

[0065] As Figure 2 shown, the foamed metal material production system based on the array pulsating air flow in this embodiment includes a molten liquid pool 10, a bubble generating device, and a discharge guiding device. Specifically, the upper end of the molten liquid pool 10 is open and used to accommodate the molten metal liquid; the bubble generating device is used to generate bubbles; the discharge guiding device is arranged above the molten liquid pool 10 and is used to guide the formed foamed metal material to continuously discharge.

[0066] In this embodiment, the bubble generating device includes a bubble generator and a bubble control system. Specifically, the bubble generator is installed in the molten pool 10, and the bubble generator includes a plurality of nozzles 21 arranged in an array, and the nozzles 21 are used to intermittently inject gas in the vertically upward direction. In this embodiment, the nozzles 21 are arranged in a honeycomb array as multiple ones. Of course, in some other embodiments, the nozzles 21 can also be arranged in a rectangular array as multiple ones, which will not be elaborated here. A high-pressure gas pipe 22 is connected to the nozzle 21 in this embodiment, and a solenoid valve 23 for controlling the opening and closing of the nozzle 21 is installed on the high-pressure gas pipe 22. In this way, by using the opening and closing action of the solenoid valve 23, the amount of gas injected into the molten pool 10 by the nozzle 21 each time can be accurately controlled, and thus bubbles with a uniform size distribution can be formed in the molten metal. Correspondingly, the bubble control system in this embodiment includes a PLC controller 24 for controlling the on-off frequency and duty cycle of the solenoid valve 23, and the PLC controller 24 controls the adjacent nozzles 21 to inject gas to form bubbles according to the set phase difference. That is, in this embodiment, on the one hand, the PLC controller 24 controls the duty cycle of each solenoid valve 23 to accurately control the amount of gas injected into the molten pool 10 by the nozzle 21 each time; on the other hand, it also needs to control the phase difference of gas injection between different nozzles 21, so that different nozzles 21 inject gas in sequence according to the set order, which can not only make the bubbles form continuously, but also increase the interval between bubbles and reduce the bubble coalescence rate.

[0067] In this embodiment, the bubble generator includes a mounting seat 27 fixedly installed on the bottom surface of the molten pool, the nozzle 21 is installed in the mounting seat 27, and a perforation for passing through the high-pressure gas pipe 22 is provided on the bottom surface of the molten pool 10, and the solenoid valve 23 is installed on the high-pressure gas pipe 22 and is located outside the molten pool 10. That is, at this time, except for the nozzle 21, the high-pressure gas pipe 22, the solenoid valve 23, and the bubble control system, etc. can all be arranged outside the molten pool 10, which can effectively reduce the influence of the high-temperature environment in the molten pool 10 on these components. Of course, in order to accurately control the pulsating gas flow ejected by the nozzle 21, the solenoid valve 23 should be arranged close to the nozzle 21, and at this time, a second cooling water jacket 28 for controlling the temperature is provided outside the solenoid valve 21. In this embodiment, the material of the nozzle 21 is silicon carbide or alumina ceramic, which can meet the use requirements of the high-temperature environment. Preferably, a water-cooled jacket can be further arranged on the outer wall of each nozzle 21 to further control the temperature of the nozzle 21. In this embodiment, the solenoid valve 21 is a high-temperature solenoid valve, which can meet the use requirements of the high-temperature environment.

[0068] Other specific implementation manners of this embodiment are the same as or equivalent to those of Embodiment 1, and will not be repeated one by one.

[0069] Embodiment 3

[0070] The following describes the specific implementation of the production method of foam metal materials based on array pulsating airflow of the present invention in combination with the foam metal material production system described in Embodiment 1 and Embodiment 2.

[0071] The production method of foam metal materials based on array pulsating airflow in this embodiment includes the following steps.

[0072] Step 1: Place the molten metal liquid in the molten pool.

[0073] Step 2: Combine the physical properties of the metal liquid and the nozzle structure size to construct a bubble generation model under pulsating airflow, obtain the relationship between the pulsating frequency and the volume of gas injected by each nozzle excitation and the bubble diameter, and calculate the phase difference between adjacent nozzles based on the pulsating frequency.

[0074] In this embodiment, the bubble generation model under pulsating airflow is:

[0075]

[0076] Where: D b is the bubble diameter; k is the correction coefficient; V g is the volume of gas injected by each nozzle excitation; σ is the surface tension of the metal liquid; f is the pulsating frequency; η is the viscosity of the metal liquid; d0 is the aperture of the nozzle.

[0077] Step 3: Based on the target bubble diameter, set the preliminary pulsating frequency and the preliminary gas volume.

[0078] Step 4: Control the on-off of the solenoid valves of each nozzle through the PCL controller, so that multiple nozzles arranged in an array inject gas with the preliminary gas volume into the molten pool according to the preliminary pulsating frequency and the set phase difference, and form bubbles in the metal liquid.

[0079] Step 5: Detect the bubble diameter:

[0080] If the proportion of bubbles with diameters exceeding the set threshold range is greater than or equal to the set first threshold, the PLC controller is used to control the time interval of each nozzle excitation to adjust the volume of gas injected into the metal liquid until the proportion of bubbles with diameters exceeding the set threshold range is less than the set first threshold.

[0081] If the bubble coalescence rate exceeds the set second threshold, increase the pulsating frequency to inhibit bubble coalescence.

[0082] Step 6: Control the on-off of the solenoid valves of each nozzle through the PCL controller, so that multiple nozzles arranged in an array inject gas with the corrected gas volume into the molten pool according to the corrected pulsating frequency and the set phase difference, and form bubbles in the metal liquid;

[0083] Step 7: Use the discharging guiding device to guide the bubbles to gather and form a foam metal material, and continuously discharge the material; in this embodiment, a third water-cooled jacket for cooling and forming the foam metal material is provided in the first guiding portion 31 and the second guiding portion 32, and the third water-cooled jacket controls the cooling rate of the foam metal material to be 10 - 50 °C / s. During the continuous discharging process of the foam metal material, steps 5 and 6 are cyclically executed to keep the bubble diameter within the set threshold range.

[0084] In the preferred implementation manner of this embodiment, the distance between two adjacent nozzles 21 is equal to 1.5 - 2 times the target bubble diameter, which can increase the distance between bubbles to reduce the merging rate, and can also improve the concentration degree of the bubble generation area, so as to facilitate guiding the bubbles to the position of the discharging guiding device.

[0085] In the preferred implementation manner of this embodiment, the phase difference of the gas jets from two adjacent nozzles 21 is 90° - 180°, which can increase the distance between the bubbles formed by the gas jets from two adjacent nozzles 21 in the vertical direction, and further reduce the bubble merging rate.

[0086] A monitoring system for monitoring the bubble size is provided on the discharging guiding device of this embodiment. The monitoring system includes a host computer 51 and a camera 52. The camera 52 collects the surface image of the foam metal material 13 in the discharging guiding channel 33, as Figure 5 shown. The host computer 51 counts the size distribution of the bubbles and the bubble merging rate according to the collected surface image of the foam metal material 13. Specifically, the method for judging bubble merging is: if the diameter of the bubble 11 is greater than 125% of the target bubble diameter, it indicates that the bubble is obtained by merging at least two bubbles, and then the bubble merging rate is calculated.

[0087] The host computer 51 is connected to the PLC controller 24. After obtaining the size distribution of the bubbles and the bubble merging rate through the host computer 51, the bubble size is dynamically adjusted through the PLC controller 24. Specifically:

[0088] When the proportion of bubbles with diameters exceeding the set threshold range is greater than or equal to the set first threshold, the PLC controller 24 controls the time interval between each excitation of the nozzle 21 through the solenoid valve 23 to adjust the volume of gas injected into the molten metal until the proportion of bubbles with diameters exceeding the set threshold range is less than the set first threshold; specifically, when the proportion of bubbles with diameters greater than the set threshold range is greater than or equal to the set first threshold, the PLC controller 24 controls the nozzle 21 to reduce the time interval between each excitation through the solenoid valve 23 to adjust the volume of gas injected into the molten metal until the proportion of bubbles with diameters exceeding the set threshold range is less than the set first threshold; when the proportion of bubbles with diameters less than the set threshold range is greater than or equal to the set first threshold, the PLC controller 24 controls the nozzle 21 to increase the time interval between each excitation through the solenoid valve 23 to adjust the volume of gas injected into the molten metal until the proportion of bubbles with diameters exceeding the set threshold range is less than the set first threshold; ultimately, the size of the bubbles 11 is maintained within the set threshold range.

[0089] When the merging rate of the bubbles 11 exceeds the set second threshold, the PLC controller 24 controls the nozzle 21 to increase the pulsation frequency through the solenoid valve 23 to inhibit the merging of the bubbles.

[0090] Specifically, a high-temperature resistant window 41 is provided on at least one of the first guiding portion 311 and the second guiding portion 32, and the camera 52 acquires the surface image of the foamed metal material 13 in the discharge guiding channel 33 through the high-temperature resistant window 41. In a preferred embodiment of the present embodiment, first bases 311 and second bases 321 are respectively provided at the bottoms of the first guiding portion 31 and the second guiding portion 32, and a high-temperature resistant window 41 is provided on at least one of the first base 311 and the second base 321. In this embodiment, the high-temperature resistant window 41 is provided on the first base 311, that is, the high-temperature resistant window 41 is provided on the first guiding portion 31. By providing the high-temperature resistant window 41 on the first base 311 and / or the second base 321, the monitoring position can be closer to the bubble generator 20, and the detection response speed can be improved.

[0091] The above-described embodiments are only preferred embodiments given to fully illustrate the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the protection scope of the present invention. The protection scope of the present invention is subject to the claims.

Claims

1. A production method of a foamed metal material based on array pulsating air flow, characterized in that: It is realized by a foam metal material production system, and the foam metal material production system includes: A molten metal pool, the upper end of the molten metal pool is open and used to hold molten metal liquid; A bubble generating device for generating bubbles; A discharge guiding device arranged above the molten metal pool and used to guide the continuous discharge of the formed foam metal material; The bubble generating device includes a bubble generator and a bubble control system; the bubble generator is installed in the molten metal pool, and the bubble generator includes a plurality of nozzles arranged in an array, and the nozzles are used to intermittently inject gas in the vertically upward direction; a high-pressure gas pipe is connected to the nozzle, and a solenoid valve for controlling the opening and closing of the nozzle is installed on the high-pressure gas pipe; the bubble control system includes a PLC controller for controlling the on-off frequency and duty cycle of the solenoid valve, and the PLC controller controls the adjacent nozzles to inject gas according to the set phase difference to form bubbles; The foam metal material production method includes the following steps: Step 1: Place the molten metal liquid in the molten metal pool; Step 2: Combine the physical properties of the metal liquid and the structural dimensions of the nozzle to construct a bubble generation model under pulsating air flow, obtain the relationship between the pulsating frequency and the volume of gas injected by each excitation of the nozzle and the bubble diameter, and calculate the phase difference between adjacent nozzles based on the pulsating frequency; Step 3: Based on the target bubble diameter, set the preliminary pulsating frequency and preliminary gas volume; Step 4: Control the on-off of the solenoid valves of each nozzle through the PCL controller, so that a plurality of nozzles arranged in an array inject gas with a preliminary gas volume into the molten metal pool according to the preliminary pulsating frequency and the set phase difference to form bubbles in the metal liquid; Step 5: Detect the bubble diameter: If the proportion of bubbles with diameters exceeding the set threshold range is greater than or equal to the set first threshold, use the PLC controller to control the time interval of each excitation of the nozzle to adjust the volume of gas injected into the metal liquid until the proportion of bubbles with diameters exceeding the set threshold range is less than the set first threshold; If the bubble coalescence rate exceeds the set second threshold, increase the pulsating frequency to inhibit bubble coalescence; Step 6: Control the on-off of the solenoid valves of each nozzle through the PCL controller, so that a plurality of nozzles arranged in an array inject gas with a corrected gas volume into the molten metal pool according to the corrected pulsating frequency and the set phase difference to form bubbles in the metal liquid; Step 7: Use the discharge guiding device to guide the bubbles to converge to form a foam metal material and continuously discharge it; during the continuous discharge of the foam metal material, repeatedly execute Step 5 and Step 6 to keep the bubble diameter within the set threshold range.

2. The production method of the metal foam material based on the pulsating air flow of the array according to claim 1, characterized in that: The distance between two adjacent nozzles is 1.5 - 2 times the target bubble diameter, and the phase difference between the gas injection of two adjacent nozzles is 90° - 180°.

3. The production method of the metal foam material based on the array pulsating air flow according to claim 1, wherein: A buffer tank is provided on the high-pressure gas pipe, and the buffer tank is used to suppress the pressure oscillation caused by the air pressure fluctuation.

4. The method for producing a foamed metal material based on array pulsating air flow according to claim 1, characterized in that: The bubble generation model under pulsating air flow is: Where: D b is the bubble diameter; k is the correction factor; V g is the gas volume injected by each excitation of the nozzle; σ is the surface tension of the molten metal; f is the pulsation frequency; η is the viscosity of the molten metal; d0 is the orifice diameter of the nozzle.

5. The method for producing a foamed metal material based on array pulsating air flow according to claim 1, characterized in that: The bubble generator includes an isolation chamber and a gas channel. The nozzle array is installed on the top surface of the isolation chamber, and the solenoid valve is installed inside the isolation chamber. The gas channel extends from an opening above the molten pool into the molten pool and is connected to the isolation chamber. A ventilation channel corresponding to each high-pressure gas pipe is provided in the gas channel. A first cooling water jacket for controlling the temperature is provided inside the isolation chamber and in the gas channel. Or, the bubble generator includes a mounting base fixedly installed on the bottom surface of the molten pool. The nozzle is installed inside the mounting base, and a perforation for passing through the high-pressure gas pipe is provided on the bottom surface of the molten pool. The solenoid valve is installed on the high-pressure gas pipe and is located outside the molten pool. A second cooling water jacket for controlling the temperature is provided outside the solenoid valve.

6. The production method of the metallic foam material based on array pulsating air flow according to claim 1, characterized in that: The discharge guiding device includes a first guiding part and a second guiding part arranged oppositely. An discharge guiding channel for the forming and discharging of the foamed metal material is formed between the first guiding part and the second guiding part. A bubble guiding plate for guiding the floating direction of the bubbles is provided below the discharge guiding channel.

7. The method for producing a foamed metal material based on pulsating airflow of an array according to claim 6, characterized in that: A third water-cooled jacket for cooling and forming the foamed metal material is provided inside the first guiding part and the second guiding part. The third water-cooled jacket controls the cooling rate of the foamed metal material to be 10 - 50 °C / s.

8. The production method of the metallic foam material based on the array pulsating air flow according to claim 6, characterized in that: A monitoring system for monitoring the bubble size is provided on the discharge guiding device. The monitoring system includes a host computer and a camera. The camera collects the surface image of the foamed metal material in the discharge guiding channel. The host computer statistically analyzes the size distribution and bubble coalescence rate of the bubbles based on the collected surface image of the foamed metal material. The method for judging bubble coalescence is: if the bubble diameter is greater than 125% of the target bubble diameter, it indicates that the bubble is formed by the coalescence of at least two bubbles, and then the bubble coalescence rate is calculated.

9. The method for producing a foamed metal material based on pulsating air flow in an array according to claim 8, characterized in that: The host computer is connected to the PLC controller, and: When the proportion of bubbles with diameters exceeding the set threshold range is greater than or equal to the set first threshold, the PLC controller controls the time interval of each excitation of the nozzle through the solenoid valve to adjust the volume of gas injected into the molten metal until the proportion of bubbles with diameters exceeding the set threshold range is less than the set first threshold. When the bubble coalescence rate exceeds the set second threshold, the PLC controller controls the nozzle to increase the pulsation frequency through the solenoid valve to inhibit bubble coalescence.

10. The method for producing a foamed metal material based on array pulsating air flow according to claim 9, characterized in that: At least one of the first guiding part and the second guiding part is provided with a high-temperature resistant window. The camera collects the surface image of the foamed metal material in the discharge guiding channel through the high-temperature resistant window. First bases and second bases are respectively provided at the bottoms of the first guiding part and the second guiding part. The high-temperature resistant window is provided on at least one of the first base and the second base.

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