Plasma rotating electrode atomization pulverizing system and method based on target particle size powder

Abstract

The invention relates to the technical field of atomization powder making, in particular to a plasma rotating electrode atomization powder making system and method based on target particle size powder, and the system comprises a bar chamber used for storing electrode bars; the material pushing chamber is communicated with the bar material chamber, and a material pushing mechanism and a driving mechanism are arranged in the material pushing chamber; and the atomizing chamber is arranged on one side of the material pushing chamber. The powder characteristic monitoring device is used for monitoring the state of the powder for powder making in real time, process fluctuation can be detected in real time, parameters can be adjusted in time, hysteresis of traditional off-line sampling inspection is avoided, different production modes can be switched by controlling the distribution uniformity characteristic and the distribution width characteristic of the powder at the same time, and the production efficiency is improved. For example, the strict requirements of 3D printing for narrow-distribution and high-uniformity powder are met, for example, for wide-distribution powder needed by thermal spraying, the same equipment can achieve higher production flexibility, and diversified production requirements are met.

Description

Technical Field

[0001] The present invention relates to the technical field of atomization powder making, and particularly to a plasma rotating electrode atomization powder making system and a powder making method based on powders with a target particle size. Background Art

[0002] Benefiting from advantages such as insensitivity to structural complexity, high material utilization rate, and good mechanical properties, powder near-net shaping technology has been increasingly widely applied in many key fields such as aerospace, ocean engineering, medical devices, and construction machinery. High-performance spherical metal powders are the key raw materials for advanced powder near-net shaping technologies represented by additive manufacturing. The quality of these powders fundamentally determines the stability of the forming process and the service performance of the final parts from the source.

[0003] Different forming processes have different requirements for powder properties, and the most prominent characteristic is the particle size and particle size distribution (PSD). For additive manufacturing technologies, the most typical processes include selective laser melting (SLM), laser metal deposition (LMD), electron beam melting (EBM), etc. The most commonly used powder particle size specifications are 15 - 53, 53 - 150, and 45 - 105 μm respectively.

[0004] The characteristics of spherical metal powders are closely related to the preparation technology. The most widely used method for preparing spherical metal powders is the gas atomization process, and typical representatives include vacuum inert gas atomization (VIGA) and electrode induction melting gas atomization (EIGA). The above gas atomization processes are restricted by the "umbrella effect" during the atomization process, resulting in insufficient and uneven fragmentation of droplets (particles), causing a wide particle size distribution of the prepared powders, with a considerable proportion of satellite powder and abnormal-shaped powder particles, and a relatively low comprehensive sphericity index of the powders (usually not exceeding 0.90). In order to obtain usable powders, the prepared powders (through powders) need to be screened and classified to obtain powders in the target section. Since the mass proportion of powders in the target particle size section in the prepared through powders is not high (taking 15 - 53 μm powders as an example, generally about 40%), the higher the demand, the higher the workload of powder making and post-screening processing. This not only brings problems such as low raw material utilization rate and backlog of non-target section powders, but also has an adverse effect that satellite powder particles affect the screening process efficiency and the process performance of the finished powder.

[0005] Different from the atomization principle of the gas atomization process in which a high-speed gas jet impacts and breaks up the metal liquid stream, the plasma rotating electrode process (PREP) melts the end of a high-speed rotating electrode rod by a high-temperature plasma torch. The molten metal (film) formed is sheared and broken under the action of centrifugal force. Since there is no interference from the turbulent flow field under the high-speed jet, the particle movement trajectory is relatively regular and the droplet (particle) production per unit time is low. Therefore, the powder produced by the PREP technology has better sphericity, and the powder particle size distribution is relatively more concentrated (compared with gas atomization). Based on the powder-making principle and powder characteristics, the PREP technology should be an ideal method for producing spherical metal powder.

[0006] However, the energy input in the PREP powder-making process is high, including high rotational speed and high-temperature plasma arc flame. The process is difficult to control, and it is easy to produce poor powder quality due to poor parameter matching. Even abnormal end face morphology of the electrode rod (the molten metal (film) that has been produced is not completely thrown out and solidifies at the edge of the rod end face to form a flash) may cause the dynamic balance of the high-speed rotating rod to be damaged and the powder-making process to be interrupted. Summary of the Invention

[0007] In view of the technical problems existing in the plasma rotating electrode atomization powder-making in the prior art, the first aspect of the present invention proposes a plasma rotating electrode atomization powder-making system based on powder with a target particle size, including:

[0008] A rod chamber for storing electrode rods;

[0009] A feeding chamber communicated with the rod chamber, and a feeding mechanism and a driving mechanism are arranged in the feeding chamber;

[0010] An atomization chamber is arranged on one side of the feeding chamber, and a feeding channel allowing the electrode rod to pass through is provided between the atomization chamber and the feeding chamber. The feeding mechanism and the driving mechanism cooperate to act on the electrode rod to make the electrode rod rotate and enter a predetermined position in the atomization chamber through the feeding channel;

[0011] A plasma generation system for generating a plasma arc and acting on the rotating electrode rod to perform atomization powder-making by heating and melting the end face of the electrode rod exposed in the atomization chamber;

[0012] A collection bin is communicated with the atomization chamber and collects the powder formed after cooling in the atomization chamber;

[0013] A powder characteristic monitoring device is connected to the powder collection channel between the atomization chamber and the collection bin and obtains the powder state characteristics in the powder collection channel in real time;

[0014] A controller is electrically connected to the powder characteristic monitoring device, the plasma generation system, the feeding mechanism and the driving mechanism;

[0015] Among them, the controller is configured to adjust the parameters of the material pushing mechanism, the driving mechanism, and the plasma generation system in real time according to the powder state characteristics obtained by the powder characteristic monitoring device, so that the powder state characteristics are within a preset range.

[0016] Preferably, the powder characteristic monitoring device is configured to obtain the particle size data of the powder in the powder collection channel, and obtain the powder state characteristics based on the particle size data;

[0017] Among them, the particle size data includes D10, D50, and D90. D10 represents the particle diameter corresponding to when the obtained cumulative particle size distribution number of the powder reaches 10%, D50 represents the particle diameter corresponding to when the obtained cumulative particle size distribution number of the powder reaches 50%, and D90 represents the particle diameter corresponding to when the obtained cumulative particle size distribution number of the powder reaches 90%;

[0018] The powder state characteristics include the powder particle size position index I D50 and the powder particle size distribution width correction value Span*.

[0019] Preferably, it is defined that the range of the particle diameter d of the target powder is d0 to d1, and the powder particle size position index I D50 =(D50 - d0) / (d1 - d0), and the powder particle size distribution width correction value Span* = (D90 - D10) / (d1 - d0); where d0 to d1 defines the distribution width range of the target powder particle diameter d, d0 represents the lower limit of the target powder particle diameter distribution width, and d1 represents the upper limit of the target powder particle diameter distribution width;

[0020] Among them, the controller controls and adjusts the parameters of the material pushing mechanism, the driving mechanism, and the plasma generation system 40, so that I A <I D50 <I B , and Span* is not greater than Span* max , I A represents the minimum value of the target powder particle size position index, I B represents the maximum value of the target powder particle size position index, and the maximum value of the powder particle size distribution width is Span* max .

[0021] Preferably, the powder characteristic monitoring device includes a dynamic image analyzer or a laser particle size analyzer, and the powder collection channel is provided with a sampling port for the dynamic image analyzer or the laser particle size analyzer to obtain powder particle size data.

[0022] Preferably, the material pushing mechanism is used to push the electrode rod along its axial direction, and can control the feeding speed by changing the distance between the electrode rod and the plasma gun to control the length L of the plasma arc;

[0023] The driving mechanism is used to drive the electrode rod to rotate and can adjust the rotation speed w of the electrode rod;

[0024] The plasma generation system can adjust the current intensity i of the plasma arc;

[0025] The controller controls the length L of the plasma arc, the rotation speed w of the electrode rod, and the current intensity i of the plasma arc based on the powder state characteristics.

[0026] Preferably, an image acquisition device for monitoring the plasma arc, such as an industrial camera, is further provided outside the atomization chamber, which is electrically connected to the controller, acquires the particle image data of the prepared powder, and obtains the plasma arc length L data through image recognition.

[0027] Preferably, when the powder particle size position index I D50 exceeds the preset range, the controller controls two of the parameters of the rotation speed w of the electrode rod, the length L of the plasma arc, and the current intensity i of the plasma arc to make the powder particle size position index I D50 stable within the preset range;

[0028] When the powder particle size distribution width correction value Span* exceeds the preset range, the controller controls two of the parameters of the length L of the plasma arc and the current intensity i of the plasma arc to make the powder particle size distribution width correction value Span* stable within the preset range.

[0029] Preferably, it further includes a rod vibration monitoring component, the rod vibration monitoring component is electrically connected to the controller, the rod vibration monitoring component is used to monitor the vibration amplitude A of the electrode rod, and the controller controls the powder making state according to the vibration amplitude A of the electrode rod:

[0030] When A ≤ 0.05 mm, it is determined that the powder making state is in a normal state;

[0031] When 0.05 < A ≤ 0.1 mm, the powder making state is in a warning state, and the controller controls the rotation speed w of the electrode rod 11 to decrease;

[0032] When A > 0.1 mm, the powder making state is in an abnormal state, and the controller controls to stop powder making.

[0033] A technical solution is proposed in the second aspect of the present invention. A powder making method using the above-mentioned plasma rotating electrode atomization powder making system based on powders of a target particle size includes the following steps:

[0034] Step 1, matching initial parameters: determining the particle size range of the target particle size, and determining the initial parameters of powder making according to the material characteristics and the target particle size range, including the initial rotation speed w0 of the electrode rod, the initial length L0 of the plasma arc, and the initial current intensity i0 of the plasma arc;

[0035] Step 2, trial production: Carry out plasma rotating electrode atomization powder making according to the initial parameters, and monitor the vibration amplitude A of the electrode rod to judge the powder making state. If it is in a normal state, enter the normal powder making state;

[0036] Step 3, normal powder making: According to the powder state characteristics obtained by the powder characteristic monitoring device, adjust the rotation speed w of the electrode rod, the length L of the plasma arc, and the current intensity i of the plasma arc in real time, so that the powder state characteristics are within a preset range until the powder making is completed;

[0037] Among them, the powder state characteristics are obtained by acquiring the particle size data of the powder in the powder collection channel, and the powder state characteristics include the powder particle size position index I D50 and the powder particle size distribution width correction value Span*. Define the range of the particle size d of the target powder as d0 to d1, and the powder particle size position index I D50 =(D50 - d0) / (d1 - d0), and the powder particle size distribution width correction value Span*=(D90 - D10) / (d1 - d0);

[0038] Among them, the particle size data includes D10, D50, and D90. D10 represents the particle size corresponding to when the cumulative particle size distribution number of the obtained powder reaches 10%, D50 represents the particle size corresponding to when the cumulative particle size distribution number of the obtained powder reaches 50%, and D90 represents the particle size corresponding to when the cumulative particle size distribution number of the obtained powder reaches 90%.

[0039] Preferably, in step 3, when the powder particle size position index I D50 exceeds the preset range, control two of the parameters of the rotation speed w of the electrode rod, the length L of the plasma arc, and the current intensity i of the plasma arc through the controller, so that the powder particle size position index I D50 is stabilized within the preset range;

[0040] When the powder particle size distribution width correction value Span* exceeds the preset range, control two of the parameters of the length L of the plasma arc and the current intensity i of the plasma arc through the controller, so that the powder particle size distribution width correction value Span* is stabilized within the preset range.

[0041] It should be understood that for obtaining powders in a certain target particle size range, it is necessary to match the melting state of the electrode rod stock with the rotation speed of the electrode rod stock. When either or both of the melting state or rotation speed of the electrode rod stock change, the yield of the powder particle size formed during powder making is likely to be low. Therefore, this poses a great challenge to the stability of the process. However, since the melting state at the end of the rod stock and the centrifugal powder making are always dynamic processes, even if the plasma arc length, current, and rotation speed are designed uniformly and their stability is ensured during the powder making process, it is still impossible to ensure a higher proportion of the target particle size range. Obviously, only controlling the parameters during the powder making process has limited improvement on the proportion of the target particle size range.

[0042] Therefore, the present invention aims to monitor the quality of the powder obtained after powder making in real time, dynamically and closed-loop control parameters such as the plasma arc length, current, and rotation speed, so as to increase the proportion of the target particle size range, and proposes a plasma rotating electrode atomization powder making system and preparation process based on the target particle size powder. Compared with the prior art, its significant advantages are as follows:

[0043] (1) Through the powder characteristic monitoring device, the real-time state of the powder during powder making is monitored, which can immediately detect process fluctuations (such as uneven molten pool temperature, abnormal droplet fragmentation), and adjust parameters (such as plasma gun current, rod stock rotation speed) within seconds, avoiding the lag of traditional off-line sampling inspection and reducing the unqualified product rate;

[0044] (2) By simultaneously controlling the distribution uniformity characteristic and the distribution width characteristic of the powder, it avoids the one-sidedness caused by only relying on the median particle size, meets the strict requirements of 3D printing for narrow-distribution and high-uniformity powders. At the same time, by adjusting the upper and lower limits of the distribution uniformity characteristic and the distribution width characteristic, different production modes can be switched. For example, for the wide-distribution powder required for thermal spraying, the same equipment can achieve higher production flexibility and adapt to diverse production needs.

[0045] In the plasma rotating electrode atomization powder making system and method based on the target particle size powder proposed by the present invention, through the dynamic parameter closed-loop regulation based on the target powder particle size characteristics, the superheat degree of the molten pool and the centrifugal force can be accurately controlled, reducing the excessive gasification or splash loss of the molten metal, achieving a powder yield of the target particle size range ≥ 50% (more than 20% higher than the traditional gas atomization process), and reducing the screening and post-treatment workload by 40% - 60%, effectively solving the problem of overstocking of non-target segment powders and raw material waste, and significantly improving the yield and screening efficiency of the target particle size range.

[0046] At the same time, further combining the vibration amplitude monitoring during the powder making process of the electrode rod stock and the particle size characteristics of the powder can suppress the generation of abnormal-shaped particles, improve the comprehensive sphericity of the powder to 0.95 - 0.98, and avoid the flying edge fracture of the rod stock through dynamic balance control, reducing the process interruption rate by 80%. Brief Description of the Drawings

[0047] The drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in each figure may be denoted by the same reference numeral. For the sake of clarity, not every component is labeled in each figure. Now, embodiments of various aspects of the present invention will be described by way of example and with reference to the drawings.

[0048] Figure 1 is a schematic structural diagram of a plasma rotating electrode atomization powder manufacturing system based on powders of a target particle size shown in the present invention.

[0049] Figure 2 is a schematic principle diagram of a plasma rotating electrode atomization powder manufacturing system based on powders of a target particle size shown in the present invention.

[0050] Figure 3 is a histogram of the particle size range of the powders prepared after parameter adjustment shown in Embodiment 3 of the present invention.

[0051] Figure 4 is a scatter plot of sphericity - particle size of the powders prepared after parameter adjustment shown in Embodiment 3 of the present invention. Detailed Description of the Embodiments

[0052] In order to better understand the technical content of the present invention, specific embodiments are hereby given and described in conjunction with the accompanying drawings as follows.

[0053] {Embodiment 1}

[0054] Combined with Figure 1 and Figure 2 shown, a plasma rotating electrode atomization powder manufacturing system according to an embodiment of the present invention includes a rod material chamber 10, a feeding chamber 20, an atomization chamber 30, a plasma generating system 40, a collection bin 50, and a powder characteristic monitoring device 60.

[0055] The rod material chamber 10 is used for storing electrode rods 11. The feeding chamber 20 is communicated with the rod material chamber 10 to enable the electrode rods 11 to enter the feeding chamber 20. The atomization chamber 30 is arranged on one side of the feeding chamber 20, and a feeding channel allowing the electrode rods 11 to pass through is provided between the atomization chamber 30 and the feeding chamber 20. A feeding mechanism and a driving mechanism are arranged in the feeding chamber 20. The feeding mechanism is used for pushing the electrode rods 11 to move along their axial directions, and the driving mechanism is used for driving the electrode rods 11 to rotate. Through the combined action of the feeding mechanism and the driving mechanism on the electrode rods 11, the electrode rods 11 are caused to rotate at high speed and enter a predetermined position in the atomization chamber 30 via the feeding channel.

[0056] Further, the plasma generating system 40 is used for generating a plasma arc 42 and acting on the rotating electrode rods 11 to perform atomization powder manufacturing by heating and melting the end faces of the electrode rods 11 exposed in the atomization chamber 30.

[0057] Among them, the atomization chamber 30 provides a suitable process environment for the powder making process of the electrode rod material 11, such as a suitable intake air pressure, flow rate, and atmosphere environment.

[0058] Among them, the pusher mechanism is designed to push the electrode rod material 11 in the pusher chamber 20 into the atomization chamber 30. By controlling the pushing speed V, the distance between the end of the electrode rod material 11 and the plasma gun 41 can be controlled to ensure that the length of the plasma arc 42 generated between the electrode rod material 11 and the plasma gun 41 meets the process requirements.

[0059] In an optional embodiment, the pusher mechanism includes a motor 111, a screw rod 112, a screw sleeve 113, and a push rod 114. The motor 111 drives the screw rod 112 to rotate at a predetermined speed. The screw sleeve 113 is driven by a thread on the outer wall of the screw rod 112. The push rod 114 is fixedly connected to the screw sleeve. By controlling the speed of the motor 111, the moving speed of the push rod 114 can be controlled to enable the electrode rod material 11 to achieve a suitable feeding speed.

[0060] Among them, the driving mechanism is used to drive the electrode rod material 11 to rotate at a high speed at a predetermined speed w. The speed w is usually set above 20000 r / min. As the electrode rod material 11 rotates, the liquid melted at its end is thrown out due to high-speed centrifugal force to form small droplets and is cooled into powder, realizing the consumption of the electrode rod material 11 and the powder making process.

[0061] In an optional embodiment, the driving mechanism includes a pair of driving rollers 221 and a pressure roller 222. The axis of the channel formed between the pair of driving rollers 221 and the pressure roller 222 coincides with the axis of the pusher channel. After the pressure roller 222 presses on the surface of the electrode rod material 11, the driving rollers 221 can drive the electrode rod material 11 to rotate at a high speed.

[0062] Furthermore, the collection bin 50 is communicated with the atomization chamber 30 and collects the powder formed after cooling in the atomization chamber 30.

[0063] The powder characteristic monitoring device 60 is connected to the powder collection channel 501 between the atomization chamber 30 and the collection bin 50, and can obtain the powder state characteristics of the powder collected in the powder collection channel 501 in real time.

[0064] In an optional embodiment, the powder characteristic monitoring device 60 includes a dynamic image analyzer or a laser particle size analyzer. The powder collection channel 501 is provided with a sampling port for the dynamic image analyzer or the laser particle size analyzer to obtain powder particle size data.

[0065] Taking the dynamic image analyzer as an example, a transparent window 52 is provided on the wall of the powder collection channel 501. The camera of the dynamic image analyzer can obtain the distribution image of the solid particles passing through the powder collection channel 501 through the window 52.

[0066] Optionally, a high-speed camera rapidly and continuously captures particle images, for example, acquires image data at a capture rate of more than 10,000 frames per second, and real-time identifies particle contours through a preset image recognition software to obtain particle size data D10, D50, and D90.

[0067] Further, the controller is electrically connected to the powder characteristic monitoring device 60, the plasma generation system 40, the pusher mechanism, and the driving mechanism, receives the recognition result collected and output by the powder characteristic monitoring device 60, and controls the operations of the plasma generation system 40, the pusher mechanism, and the driving mechanism.

[0068] In an embodiment of the present invention, the controller is configured to adjust the parameters of the pusher mechanism, the driving mechanism, and the plasma generation system 40 in real time according to the powder state characteristics obtained by the powder characteristic monitoring device 60, so that the powder state characteristics are within a preset range.

[0069] Optionally, the powder characteristic monitoring device 60 is configured to obtain the particle size data of the powder in the powder collection channel 501 and obtain the powder state characteristics based on the particle size data.

[0070] Wherein, the particle size data includes D10, D50, and D90. D10 represents the particle diameter corresponding to when the cumulative particle size distribution number of the obtained powder reaches 10%, D50 represents the particle diameter corresponding to when the cumulative particle size distribution number of the obtained powder reaches 50%, and D90 represents the particle diameter corresponding to when the cumulative particle size distribution number of the obtained powder reaches 90%.

[0071] It should be understood that by obtaining the particle size data of the powder, such as D10, D50, and D90, the uniformity of the powder can be reflected. D50 represents the median particle diameter, which refers to the particle diameter value corresponding to when the cumulative distribution percentage reaches 50%. This is a typical value representing the particle size. This value accurately divides the whole into two equal parts, that is, 50% of the particle diameters exceed this value, and 50% of the particle diameters are lower than this value. When D50 is within the particle diameter range of the target powder, it indicates that the powder quality is good and meets the requirements. If D50 is greater than the upper limit value of the particle diameter range of the target powder, it indicates that the powder particle diameter is too large. At the same time, the difference between D90 - D10 represents the width of the powder particle size distribution. If the width is too wide, it indicates that the distribution range of the powder diameter is large and not concentrated enough.

[0072] Therefore, the state of the powder can be evaluated through the particle size data of the powder, and its quality can be characterized. In an embodiment of the present invention, the powder state characteristics include the powder particle size position index I D50 and the powder particle size distribution width correction value Span*.

[0073] Wherein, it is defined that the range of the particle diameter d of the target powder is d0~d1, and the powder particle size position index ID50 = (D50 - d0) / (d1 - d0), the powder particle size distribution width correction value Span* = (D90 - D10) / (d1 - d0).

[0074] Wherein, the controller controls the parameters of the material pushing mechanism, the driving mechanism and the plasma generation system 40 to make I A <I D50 <I B , and Span* is less than or equal to Span* max , I A represents the minimum value of the target powder particle size position index, I B represents the maximum value of the target powder particle size position index, and the maximum value of the powder particle size distribution width is Span* max .

[0075] It should be understood that if I D50 <I A , it indicates that the prepared powder is too fine (the content of powder finer than the lower limit of the target particle size is relatively high). If I D50 > I B , it indicates that the prepared powder is too coarse (the content of powder coarser than the upper limit of the target particle size is relatively high). If I A <I D50 <I B , but Span* > Span* max , it indicates that the D50 of the prepared powder meets the requirement, but the particle size distribution is too wide (usually due to the simultaneous existence of some fine powder tails below the lower limit and coarser powder mixing above the upper limit). Therefore, for the above-mentioned powder preparation defects, appropriate parameters need to be adjusted for compensation, especially by precisely adjusting the process parameters such as the length L of the plasma arc 42, the rotation speed w of the electrode rod 11, and the current intensity i of the plasma arc 42.

[0076] In an alternative embodiment, the material pushing mechanism can push the electrode rod 11 to move along its axial direction and change the distance between the electrode rod 11 and the plasma gun 41, thereby controlling the length L of the plasma arc 42.

[0077] The controller controls the length L of the plasma arc 42, the rotation speed w of the electrode rod 11, and the current intensity i of the plasma arc 42 based on the powder state characteristics.

[0078] In a preferred embodiment, an image acquisition device 43 for monitoring the plasma arc, such as an industrial camera, is further provided outside the atomization chamber 30, which is electrically connected to the controller, collects the particle image data of the prepared powder, and obtains the plasma arc length L data through image recognition.

[0079] Optionally, the aforementioned image acquisition device 43 may adopt a high-speed and high-resolution industrial camera to collect the arc flame image of the plasma arc 42 in real time. Through the image processing and recognition algorithm of the existing technology, for example, through the classic contour processing algorithms of OpenCV (such as Canny detection, Sobel detection, Laplacian detection, etc.), the arc flame edge contour information is obtained and the contour geometric features are processed to obtain the length L of the plasma arc 42. According to the preset set value of the length of the plasma arc 42, by adjusting the appropriate feeding speed of the electrode rod 11, the length L of the plasma arc 42 is stabilized within the preset range.

[0080] In an alternative embodiment, when the powder particle size position index ID50 exceeds the preset range, the controller controls two of the parameters of the rotation speed w of the electrode rod 11, the length L of the plasma arc 42, or the current intensity i of the plasma arc 42 to make the powder particle size position index I D50 stable within the preset range;

[0081] When the powder particle size distribution width correction value Span* exceeds the preset range, the controller controls two of the parameters of the length L of the plasma arc 42 and the current intensity i of the plasma arc 42 to make the powder particle size distribution width correction value Span* stable within the preset range.

[0082] For example, define I A = 0.3, I B = 0.7, Span* max = 1.3. During the powder making process, if I D50 < 0.3, it indicates that the prepared powder is too fine (the content of powder finer than the lower limit of the target particle size is relatively high). The adjustment action is: reducing the rotation speed w of the electrode rod 11 to reduce the generation of fine powder, with an adjustment step of -(500 - 1000) r / min, and simultaneously increasing the length L of the plasma arc 42 to reduce the superheat degree, with an adjustment step of +(1 - 3) mm.

[0083] If I D50 > 0.7, it indicates that the prepared powder is too coarse (the content of powder coarser than the upper limit of the target particle size is relatively high). The adjustment action is: increasing the rotation speed w of the electrode rod 11 to refine the coarse particles, with an adjustment step of +(500 - 1000) r / min, and at the same time reducing the current intensity i of the plasma arc 42 to limit the superheat degree to inhibit the generation of ultra-fine particles, with an adjustment step of -(10 - 30) A.

[0084] If 0.3 ≤ ID50 ≤ 0.7, but Span* > 1.2, it indicates that the prepared powder D50 meets the requirements, but the particle size distribution is too wide (usually due to the simultaneous presence of some fine powder tails below the lower limit and coarse powder mixtures above the upper limit). The adjustment action is to reduce the length L of the plasma arc 42 to increase the energy input, with an adjustment step of -(1 - 3) mm. Synchronously increase the current intensity i of the plasma arc 42 to promote the uniformity of droplet fragmentation, with an adjustment step of +(10 - 30) A.

[0085] In the above embodiment, it further includes a rod vibration monitoring component 32. The rod vibration monitoring component 32 is electrically connected to the controller. The rod vibration monitoring component 32 is used to monitor the vibration amplitude A of the electrode rod 11. The controller controls the powder making state according to whether the vibration amplitude A of the electrode rod 11 is within the preset allowable range. Taking the upper limit of the preset allowable range as 0.05 mm and the lower limit as 0.1 mm as an example:

[0086] When A ≤ 0.05 mm, the powder making state is in a normal state;

[0087] When 0.05 < A ≤ 0.1 mm, the powder making state is in a warning state, and the controller controls the rotation speed w of the electrode rod 11 to decrease;

[0088] When A > 0.1 mm, the powder making state is in an abnormal state, and the controller controls the powder making to stop.

[0089] Specifically, the rod vibration monitoring component 32 includes a laser displacement sensor. By monitoring the displacement of the pressure roller 222, the vibration state of the electrode rod 11 can be reflected. If A ≤ 0.05 mm, it is in a normal state and can continue to run at this time; if 0.05 < A ≤ 0.1 mm, it is in a warning state, automatically triggering a decrease in the rotation speed w, with an adjustment step of -(500 - 1000) r / min; if A > 0.1 mm, then stop immediately, check the dimensional tolerance of the rod, as well as the surface wear of the drive roller and the pressure wheel.

[0090] It should be understood that according to the implementation of the plasma electrode atomization powder making system of the present invention, it is applicable to the preparation of metal alloy powders such as titanium alloys and superalloys.

[0091] {Example 2}

[0092] In this embodiment, the powder making process is realized by using the above-mentioned plasma rotating electrode atomization powder making system based on the powder of the target particle size, including the following steps:

[0093] Step 1. Match the initial parameters: Determine the particle size range of the target particle size, and determine the initial parameters of powder making according to the material characteristics and the target particle size range, including the initial rotation speed w0 of the electrode rod 11, the initial length L0 of the plasma arc 42, and the initial current intensity i0 of the plasma arc 42;

[0094] Step 2, trial production: Carry out plasma rotating electrode atomization powder making according to the initial parameters, and monitor the vibration amplitude A of the electrode rod 11 to judge the powder making state. If it is in a normal state, enter the normal powder making state;

[0095] Step 3, normal powder making: According to the powder state characteristics obtained by the powder characteristic monitoring device 60, adjust the rotation speed w of the electrode rod 11, the length L of the plasma arc 42, and the current intensity i of the plasma arc 42 in real time, so that the powder state characteristics are within the preset range until the powder making is completed;

[0096] Among them, the powder state characteristics are obtained by acquiring the particle size data of the powder in the powder collection channel 501, and the powder state characteristics include the powder particle size position index I D50 and the powder particle size distribution width correction value Span*, define the range of the particle size d of the target powder as d0~d1, and the powder particle size position index I D50 =(D50 - d0) / (d1 - d0), and the powder particle size distribution width correction value Span*=(D90 - D10) / (d1 - d0);

[0097] Among them, the particle size data includes D10, D50, and D90. D10 represents the particle size corresponding to when the cumulative particle size distribution number of the obtained powder reaches 10%, D50 represents the particle size corresponding to when the cumulative particle size distribution number of the obtained powder reaches 50%, and D90 represents the particle size corresponding to when the cumulative particle size distribution number of the obtained powder reaches 90%.

[0098] Preferably, in Step 3, when the powder particle size position index I D50 exceeds the preset range, control two of the rotation speed w of the electrode rod 11, the length L of the plasma arc 42, and the current intensity i of the plasma arc 42 through the controller, so that the powder particle size position index I D50 is stabilized within the preset range;

[0099] When the powder particle size distribution width correction value Span* exceeds the preset range, control two of the length L of the plasma arc 42 and the current intensity i of the plasma arc 42 through the controller, so that the powder particle size distribution width correction value Span* is stabilized within the preset range.

[0100] {Example 3}

[0101] In this embodiment, GH3625 alloy powder is prepared according to the process method of the foregoing embodiment.

[0102] 1) Material classification and parameter matching

[0103] GH3625 belongs to nickel-based superalloys, referring to the parameter window of the reference material GH4169. The preset process parameter range: the diameter of the bar is φ40 - 80mm (vacuum induction melting or forging densification process), the rotational speed w ranges from 18000 - 28000r / min, the length L of the plasma arc 42 ranges from 30 - 60mm, and the plasma arc current intensity i ranges from 1000 - 1500A.

[0104] 2) Confirmation of the target particle size range

[0105] The target particle size range is powder with ≤53μm, belonging to the fine particle size type.

[0106] 3) Setting of initial parameters

[0107] Determine the initial parameters: Determine the initial parameters: the diameter of the bar is φ50mm (vacuum induction melting + forging densification process), the rotational speed w of the bar is 26000r / min, the length L of the plasma arc 42 is 40mm, and the plasma arc current intensity i is 1400A..

[0108] 4) Preparation and inspection of the bar

[0109] After inspecting the finished bar, the batch diameter fluctuation of 0.06mm meets the requirements (≤0.1mm), and the straightness (≤0.025mm), perpendicularity (≤0.15mm), and surface roughness (not exceeding Ra1.6μm) of the bar meet the requirements.

[0110] 5) Trial production and parameter regulation of the plasma rotating electrode

[0111] Set and start the trial production of plasma rotating electrode atomization according to the initial parameters. After real-time detection, the vibration amplitude A of the bar ≤0.05mm, and the dynamic balance of the high-speed rotation of the bar is stable.

[0112] Through the on-line particle size distribution detection of the powder obtained under the initial parameters, the measured D10 = 24μm, D50 = 46μm, D90 = 80μm, ID50 = 46 / 53 = 0.86 > 0.80, Span* = (80 - 24) / (53 - 15) = 1.47 < 1.5. According to the regulation strategy, it is necessary to further increase the rotational speed to promote the refinement of powder particles. Increase the rotational speed w of the bar by 1000r / min (i.e., 27000r / min), and simultaneously reduce the length L of the plasma arc flame by 2mm (i.e., 38mm).

[0113] Conduct on-line detection of the powder obtained after parameter adjustment, combined with Figure 3 and Figure 4As shown, the measured values are D10 = 23 μm, D50 = 42 μm, D90 = 75 μm, ID50 = 42 / 53 = 0.79 < 0.80, Span* = (75 - 23) / (53 - 15) = 1.37 < 1.5, meeting the regulation target. At the same time, the on-line detection result of the powder particle shape (sphericity S) is 0.97 (≥0.95), meeting the control requirements, indicating good matching between parameters, and normal process and powder morphology.

[0114] 6) Verification and mass production

[0115] Powder trial production is carried out under the above-regulated parameters. After that, samples of the obtained powder are taken and detected by the dry sieving method. The proportion of -270 mesh (pore diameter 53 μm) powder reaches 62%. The particle size of the -270 mesh powder is detected by the laser diffraction method, and the results are D10 = 22 μm, D50 = 37 μm, D90 = 52 μm. In summary, the yield and powder particle size distribution in the target section (≤53 μm) meet the requirements. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Those with ordinary knowledge in the technical field to which the present invention pertains can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to what is defined by the claims.

Claims

1. A plasma rotating electrode atomization powder making system based on powders with a target particle size, characterized in that Comprising: A bar stock chamber (10) for storing electrode bar stock (11); A pusher chamber (20) communicating with the bar stock chamber (10), wherein a pusher mechanism and a driving mechanism are provided in the pusher chamber (20); the pusher mechanism is used to push the electrode bar stock (11) to move along its axial direction, and the driving mechanism is used to drive the electrode bar stock (11) to rotate; An atomization chamber (30) arranged on one side of the pusher chamber (20), and a pusher channel allowing the electrode bar stock (11) to pass through is provided between the atomization chamber (30) and the pusher chamber (20), and the pusher mechanism and the driving mechanism cooperate on the electrode bar stock (11) to make the electrode bar stock (11) rotate and enter a predetermined position in the atomization chamber (30) via the pusher channel; A plasma generation system (40) for generating a plasma arc (42) and acting on the rotating electrode bar stock (11), and atomizing and powder-making by heating and melting the end face of the electrode bar stock (11) exposed in the atomization chamber (30); A collection bin (50) communicating with the atomization chamber (30) and collecting the powder formed after cooling in the atomization chamber (30); A powder characteristic monitoring device (60) connected to a powder collection channel (501) between the atomization chamber (30) and the collection bin (50), and obtaining the powder state characteristics in the powder collection channel (501) in real time; A controller electrically connected to the powder characteristic monitoring device (60), the plasma generation system (40), the pusher mechanism and the driving mechanism; Wherein, the controller is configured to adjust the parameters of the pusher mechanism, the driving mechanism and the plasma generation system (40) in real time according to the powder state characteristics obtained by the powder characteristic monitoring device (60) to make the powder state characteristics within a preset range.

2. The plasma rotating electrode atomization powder making system based on the powder with a target particle size according to claim 1, wherein The powder characteristic monitoring device (60) is configured to obtain the particle size data of the powder in the powder collection channel (501) and obtain the powder state characteristics based on the particle size data; Wherein, the particle size data includes D10, D50 and D90, D10 represents the particle size corresponding to when the obtained cumulative particle size distribution number of the powder reaches 10%, D50 represents the particle size corresponding to when the obtained cumulative particle size distribution number of the powder reaches 50%, and D90 represents the particle size corresponding to when the obtained cumulative particle size distribution number of the powder reaches 90%; The powder state characteristics include the powder particle size position index I D50 and the powder particle size distribution width correction value Span*.

3. The plasma rotating electrode atomization powder making system based on the powder with a target particle size according to claim 2, wherein, Define the range of the particle size d of the target powder as d0 to d1, and the powder particle size position index I D50 =(D50 - d0) / (d1 - d0), and the powder particle size distribution width correction value Span* = (D90 - D10) / (d1 - d0); where d0 to d1 define the distribution width range of the particle size d of the target powder, d0 represents the lower limit of the particle size distribution width of the target powder, and d1 represents the upper limit of the particle size distribution width of the target powder; Among them, the controller controls the parameters of the material pushing mechanism, the driving mechanism, and the plasma generation system (40) to make I A <I D50 <I B and Span* is less than or equal to Span* max I A represents the minimum value of the target powder particle size position index, I B represents the maximum value of the target powder particle size position index, Span* max represents the maximum value of the powder particle size distribution width.

4. The plasma rotating electrode atomization powder making system based on powders with a target particle size according to claim 1, wherein The powder characteristic monitoring device (60) includes a dynamic image analyzer or a laser particle size analyzer, and a sampling port for the dynamic image analyzer or the laser particle size analyzer to obtain powder particle size data is provided in the powder collection channel (501).

5. The plasma rotating electrode atomization powder making system based on powders with a target particle size according to claim 1, wherein The pusher mechanism is configured to be able to adjust the distance between the electrode bar stock (11) and the plasma gun (41) to control the length L of the plasma arc (42); The driving mechanism is configured to be able to adjust the rotation speed w of the electrode bar stock (11); The plasma generation system (40) is configured to be able to adjust the current intensity i of the plasma arc (42); The controller controls the length L of the plasma arc (42), the rotational speed w of the electrode rod (11), and the current intensity i of the plasma arc (42) based on the powder state characteristics, so that the powder state characteristics monitored in real time by the powder characteristic monitoring device (60) are within a preset range.

6. The plasma rotating electrode atomization powder making system based on the powder with a target particle size according to claim 5, wherein, An image acquisition device (43) for monitoring the length L of the plasma arc (42) is further provided outside the atomization chamber (30). The controller is electrically connected to the image acquisition device (43) to obtain the data of the length L of the plasma arc (42) monitored by the image acquisition device (43).

7. The plasma rotating electrode atomization powder making system based on the powder with a target particle size according to claim 5, characterized in that When the powder particle size position index I D50 exceeds the preset range, the controller controls two of the rotational speed w of the electrode rod material (11), the length L of the plasma arc (42), and the current intensity i of the plasma arc (42) to make the powder particle size position index I D50 stable within the preset range; When the powder particle size distribution width correction value Span* exceeds the preset range, the controller controls two of the parameters of the length L of the plasma arc (42) and the current intensity i of the plasma arc (42) to make the powder particle size distribution width correction value Span* stable within the preset range.

8. The plasma rotating electrode atomization powder making system based on powders with a target particle size according to claim 1, characterized in that, It further includes a rod vibration monitoring component (32) for monitoring the vibration amplitude A of the electrode rod (11); The controller is electrically connected to the rod vibration monitoring component (32) and controls the powder making state according to the vibration amplitude A of the electrode rod (11): When A ≤ 0.05 mm, it is determined that the powder making state is in a normal state; When 0.05 < A ≤ 0.1 mm, the powder making state is in a warning state, and the controller controls the rotational speed w of the electrode rod (11) to decrease; When A > 0.1 mm, the powder making state is in an abnormal state, and the controller controls to stop powder making.

9. The plasma rotating electrode atomization powder making method of the plasma rotating electrode atomization powder making system based on the powder with a target particle size according to any one of claims 1-8, characterized in that, It includes the following steps: Step 1, matching initial parameters: Determine the particle size range of the target particle size, and determine the initial parameters of powder making according to the material characteristics and the target particle size range, including the initial rotational speed w0 of the electrode rod (11), the initial length L0 of the plasma arc (42), and the initial current intensity i0 of the plasma arc (42); Step 2, trial production: Carry out plasma rotating electrode atomization powder making according to the initial parameters, and monitor the vibration amplitude A of the electrode rod (11) to judge the powder making state. After it is in a normal state, enter the normal powder making process; Step 3, normal powder making: Real-time adjust the rotational speed w of the electrode rod (11), the length L of the plasma arc (42), and the current intensity i of the plasma arc (42) according to the powder state characteristics obtained by the powder characteristic monitoring device (60), so that the powder state characteristics are within the preset range until the powder making ends; Among them, the powder state characteristics are obtained by acquiring the particle size data of the powder in the powder collection channel (501), and the powder state characteristics include the powder particle size position index I D50 and the corrected value Span* of the powder particle size distribution width. It is defined that the range of the particle size d of the target powder is d0 to d1, and the powder particle size position index I D50 =(D50 - d0) / (d1 - d0), and the corrected value Span* of the powder particle size distribution width = (D90 - D10) / (d1 - d0); Among them, the particle size data includes D10, D50, and D90. D10 represents the particle size corresponding to when the cumulative particle size distribution number of the obtained powder reaches 10%, D50 represents the particle size corresponding to when the cumulative particle size distribution number of the obtained powder reaches 50%, and D90 represents the particle size corresponding to when the cumulative particle size distribution number of the obtained powder reaches 90%.

10. The powder making method according to claim 9, characterized in that, In step 3, when the powder particle size position index I D50 exceeds the preset range, the controller controls two of the rotational speed w of the electrode rod material (11), the length L of the plasma arc (42), and the current intensity i of the plasma arc (42), so that the powder particle size position index I D50 is stabilized within the preset range; When the powder particle size distribution width correction value Span* exceeds the preset range, the controller controls two of the parameters of the length L of the plasma arc (42) and the current intensity i of the plasma arc (42) to make the powder particle size distribution width correction value Span* stable within the preset range.

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