Plasma rotating electrode atomization powdering process parameter adjusting method for preparing powder with expected target particle size

Abstract

The invention provides a plasma rotating electrode atomization pulverization process parameter adjusting method for preparing powder with an expected target particle size, which comprises the following steps: in the plasma rotating electrode atomization pulverization process, monitoring image data of the powder in real time, identifying the particle contour in real time through image identification software, and obtaining particle size data D10, D50 and D90; determining powder state characteristics based on the particle size data, wherein the powder state characteristics comprise a powder particle size position index ID50 and a powder particle size distribution width correction value Span *; according to the state characteristics of the powder, parameters of a pushing mechanism, a driving mechanism and a plasma generation system are controlled, so that IAlt; iD501t, ID501t; iB, and Span * is less than or equal to Span * max. By monitoring the quality of the powder obtained after powder preparation in real time and dynamically controlling parameters such as the arc length, the current and the rotating speed of the plasma arc in a closed-loop mode, the proportion of the target particle size section is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of atomization powder making, and particularly relates to a method for adjusting process parameters of plasma rotating electrode atomization powder making for preparing powders with an expected 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 forming technology has been increasingly widely applied in many key fields such as aerospace, ocean engineering, medical devices, and construction machinery. High-performance spherical metal powder is the key raw material for advanced powder near-net forming technologies represented by additive manufacturing. Its own quality 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 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 powder are closely related to the preparation technology. The most widely used method for preparing spherical metal powder 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), resulting in a wide particle size distribution of the prepared powder, with a considerable proportion of satellite powder and abnormal-shaped powder particles, and a relatively low comprehensive sphericity index of the powder (usually not exceeding 0.90). In order to obtain usable powder, the prepared powder (through powder) needs to be screened and classified to obtain the target section powder. Since the mass proportion of the powder in the target particle size section in the prepared through powder is not high (taking the 15 - 53 μm powder as an example, generally about 40%), the higher the demand, the higher the workload of powder making and post-screening treatment required, which not only brings problems such as low raw material utilization rate and backlog of non-target section powder, but also has an adverse effect on the screening process efficiency and the process performance of the finished powder due to satellite powder particles.

[0005] Different from the atomization principle of gas atomization process, where the metal liquid stream is broken up by the impact of a high-speed gas jet, the plasma rotating electrode process (PREP) melts the end of a high-speed rotating electrode rod using a high-temperature plasma torch. The molten metal liquid (film) formed is sheared and broken under the action of centrifugal force. Since there is no interference from the turbulent flow field under high-speed jets, the particle movement trajectories are relatively regular and the production rate of droplets (particles) 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 to gas atomization). Based on the powder production principle and powder characteristics, the PREP technology should ideally be a method for producing spherical metal powder.

[0006] However, the energy input in the PREP powder production 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-quality powder due to improper parameter matching. In some cases, abnormal morphology of the electrode rod end surface may occur (the molten metal liquid (film) that has been formed is not completely thrown out and solidifies at the edge of the rod end surface to form a flash), resulting in the destruction of the dynamic balance of the high-speed rotating rod and the interruption of powder production. Summary of the Invention

[0007] According to the first aspect of the object of the present invention, a method for adjusting the process parameters of plasma rotating electrode atomization for preparing powder with a desired target particle size is proposed, including the following steps:

[0008] During the plasma rotating electrode atomization powder production process, the image data of the powder is monitored in real time, and the particle contours are recognized in real time through image recognition software to obtain the particle size data 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%.

[0009] Based on the particle size data, the powder state characteristics are determined, including the powder particle size position index I D50 and the powder particle size distribution width correction value Span*; and

[0010] According to the powder state characteristics, the parameters of the material pushing mechanism, the driving mechanism, and the plasma generation system are controlled to make I A <I D50 <I B and Span* is less than or equal to Span* max where 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 Span* max represents the maximum value of the powder particle size distribution width.

[0011] As an alternative embodiment, the powder particle size position index I in the powder state characteristics D50 and the powder particle size distribution width correction value Span* are determined as follows:

[0012] Powder particle size position index I D50 , I D50 = (D50 - d0) / (d1 - d0);

[0013] Powder particle size distribution width correction value Span*, Span* = (D90 - D10) / (d1 - d0);

[0014] wherein, d0 to d1 define the distribution width range of the target powder particle size d, d0 represents the lower limit of the target powder particle size distribution width, and d1 represents the upper limit of the target powder particle size distribution width.

[0015] As an alternative embodiment, the method further includes:

[0016] Real-time monitoring of the arc flame image of the plasma arc; and

[0017] Based on the arc flame image recognition, obtaining the length L of the plasma arc.

[0018] As an alternative embodiment, the method further includes:

[0019] Real-time monitoring of the feeding speed of the pusher mechanism for pushing the electrode rod along its axial direction;

[0020] By controlling the feeding speed of the pusher mechanism for driving the electrode rod, adjusting the spacing between the electrode rod and the plasma gun, thereby controlling the length L of the plasma arc.

[0021] As an alternative embodiment, by monitoring the powder particle size position index I D50 discriminating the particle size deviation between the obtained powder and the target powder, wherein:

[0022] If I D50 < I A , it is determined that the obtained powder is finer, that is: the content of powder finer than the target particle size lower limit is higher than expected;

[0023] If I D50 > I B , it is determined that the obtained powder is coarser, that is: the content of powder coarser than the target particle size upper limit is higher than expected;

[0024] If I A < I D50 < I B , it is determined that the particle size distribution of the obtained powder meets the expectation.

[0025] As an optional embodiment, the parameters of the pushing mechanism, the driving mechanism and the plasma generating system are controlled and regulated according to the powder state characteristics so that A D50 B , and Span* is less than or equal to Span* max ,include:

[0026] When the powder particle size position index I D50 When the preset range is exceeded, the controller controls the rotation speed w of the electrode bar, the length L of the plasma arc or the current intensity i of the plasma arc to adjust the powder particle size position index I D50 Stable within the preset range;

[0027] When the powder particle size distribution width correction value Span* exceeds the preset range, the controller stabilizes the powder particle size distribution width correction value Span* within the preset range by controlling two parameters: the length L of the plasma arc and the current intensity i of the plasma arc.

[0028] As an optional embodiment, the method further includes:

[0029] The vibration amplitude A of the electrode bar is monitored in real time by the bar vibration monitoring component, and the controller controls the powder making state according to the vibration amplitude A of the electrode bar:

[0030] When A≤0.05mm, the milling state is judged to be normal;

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

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

[0033] As an optional embodiment, the bar vibration monitoring component uses a laser displacement sensor to characterize the vibration state of the electrode bar by real-time monitoring of the displacement of the pressure roller in the driving mechanism.

[0034] As an optional embodiment, the controller controls the rotation speed w of the electrode rod to decrease, wherein the rotation speed adjustment step is (500-1000) r / min.

[0035] As an optional embodiment, the method is applicable to the preparation of powders of titanium alloys and high-temperature alloys.

[0036] ​​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 rotational speed of the electrode rod stock. When either or both of the melting state or rotational 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 casting powder making are always dynamic processes, even if the plasma arc length, current, and rotational 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.

[0037] Therefore, the present invention aims to improve the proportion of the target particle size range by monitoring the quality of the powder obtained after powder making in real time and dynamically and closed-loop controlling parameters such as the plasma arc length, current, and rotational speed, and proposes a method for adjusting the process parameters of plasma rotating electrode atomization powder making for preparing powders with the expected target particle size. Compared with the prior art, its significant advantages are as follows:

[0038] (1) The real-time status of the powder during powder making is monitored by a powder characteristic monitoring device, which can immediately detect process fluctuations (such as uneven molten pool temperature and abnormal droplet fragmentation), and adjust parameters (such as plasma gun current and rod stock rotational speed) within seconds, avoiding the lag of traditional off-line sampling inspection and reducing the unqualified product rate;

[0039] (2) By simultaneously controlling the distribution uniformity characteristic and the distribution width characteristic of the powder, the one-sidedness caused by relying only on the median particle size is avoided, meeting the strict requirements of 3D printing for powders with narrow distribution and high uniformity. 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.

[0040] The method for adjusting the process parameters of plasma rotating electrode atomization powder making for preparing powders with the expected target particle size proposed by the present invention can accurately control the superheat degree of the molten pool and the centrifugal force through dynamic parameter closed-loop regulation based on the target powder particle size characteristics, reduce the excessive gasification or splash loss of the molten metal, achieve a powder yield of the target particle size range ≥ 50% (more than 20% higher than the traditional gas atomization process), and reduce the screening and post-treatment workload by 40% - 60%, effectively solving the problems of backlog of non-target segment powders and waste of raw materials, and significantly improving the yield and screening efficiency of the target particle size range.

[0041] Combined with the monitoring of the vibration amplitude during the powder making process of the electrode rod stock and the particle size characteristics of the powder, the generation of abnormal particles can be suppressed, the comprehensive sphericity of the powder is increased to 0.95 - 0.98, and the flying edge fracture of the rod stock is avoided through dynamic balance control, reducing the process interruption rate by 80%.

[0042] It should be understood that all combinations of the foregoing concepts and additional concepts described in greater detail below are considered to be part of the inventive subject matter of the present disclosure as long as such concepts are not mutually inconsistent. Additionally, all combinations of the claimed subject matter are considered to be part of the inventive subject matter of the present disclosure.

[0043] The foregoing and other aspects, embodiments, and features of the teachings of the present invention can be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as the features and / or beneficial effects of exemplary embodiments, will be apparent from the following description or will be learned through practice of specific embodiments in accordance with the teachings of the present invention. Description of the Drawings

[0044] Figure 1 is a schematic structural diagram of a plasma rotating electrode atomization powder making system according to an embodiment of the present invention.

[0045] Figure 2 is a schematic principle diagram of the plasma rotating electrode atomization powder making system shown in the present invention.

[0046] Figure 3 is a histogram of the particle size range of the powder prepared after parameter adjustment in Example 3 of the present invention.

[0047] Figure 4 is a scatter plot of sphericity - particle size of the powder prepared after parameter adjustment in Example 3 of the present invention. Detailed Description of the Embodiments

[0048] 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.

[0049] In the present disclosure, aspects of the present invention are described with reference to the accompanying drawings, in which numerous illustrative embodiments are shown. The embodiments of the present disclosure are not necessarily intended to cover all aspects of the present invention. It should be understood that the various concepts and embodiments introduced above, as well as those concepts and embodiments described in greater detail below, can be implemented in any of a number of ways, because the concepts and embodiments disclosed in the present invention are not limited to any particular embodiment. Additionally, some aspects of the present invention can be used alone or in any suitable combination with any other aspects of the present invention.

[0050] {Embodiment 1}

[0051] Combined Figure 1 and Figure 2 shown, a plasma rotating electrode atomization powder making 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.

[0052] The bar stock chamber 10 is used to store the electrode bar stock 11. The pusher chamber 20 is communicated with the bar stock chamber 10 to enable the electrode bar stock 11 to enter the pusher chamber 20. The atomization chamber 30 is 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. A pusher mechanism and a driving mechanism are arranged 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. Through the combined action of the pusher mechanism and the driving mechanism on the electrode bar stock 11, the electrode bar stock 11 is made to rotate at a high speed and enter a predetermined position in the atomization chamber 30 via the pusher channel.

[0053] Furthermore, the plasma generation system 40 is used to generate the plasma arc 42 and act on the rotating electrode bar stock 11, and atomized powder is produced by heating and melting the end face of the electrode bar stock 11 exposed in the atomization chamber 30.

[0054] Among them, the atomization chamber 30 provides a suitable process environment for the powder making process of the electrode bar stock 11, such as a suitable intake air pressure, flow rate, and atmosphere environment.

[0055] Among them, the pusher mechanism is designed to push the electrode bar stock 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 bar stock 11 and the plasma gun 41 can be controlled to ensure that the length of the plasma arc 42 generated between the electrode bar stock 11 and the plasma gun 41 meets the process requirements.

[0056] In an alternative embodiment, the pusher mechanism includes a motor 111, a screw 112, a nut 113, and a push rod 114. The motor 111 drives the screw 112 to rotate at a predetermined speed. The nut 113 is driven by the screw 112 through a thread transmission. The push rod 114 is fixedly connected to the nut. The moving speed of the push rod 114 can be controlled by the speed of the motor 111 to enable the electrode bar stock 11 to achieve a suitable feeding speed.

[0057] Among them, the driving mechanism is used to drive the electrode bar stock 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 bar stock 11 rotates, the liquid melted at its end is thrown out due to the high-speed centrifugal force to form small droplets and is cooled into powder, realizing the consumption of the electrode bar stock 11 and the powder making process.

[0058] In an alternative embodiment, the driving mechanism includes a pair of driving rollers 221 and a pressure roller 222. The channel formed between the pair of driving rollers 221 and the pressure roller 222 coincides with the axis of the pusher channel. When the pressure roller 222 presses on the surface of the electrode bar stock 11, the driving rollers 221 can drive the electrode bar stock 11 to rotate at a high speed.

[0059] Further, the collection bin 50 is in communication with the atomization chamber 30 and collects the powder formed after cooling in the atomization chamber 30.

[0060] 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 obtains the powder state characteristics of the powder collected in the powder collection channel 501 in real time.

[0061] In an optional embodiment, the powder characteristic monitoring device 60 includes a dynamic image analyzer or a laser particle size analyzer, and 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.

[0062] Taking the dynamic image analyzer as an example, a transparent window 52 is provided on the wall of the powder collection channel 501, and 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.

[0063] 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 the particle contours through a pre-set image recognition software to obtain the particle size data D10, D50, and D90.

[0064] 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 operation of the plasma generation system 40, the pusher mechanism, and the driving mechanism.

[0065] In the 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.

[0066] 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.

[0067] 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%.

[0068] 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 size, which is the particle size value corresponding to when the cumulative distribution percentage reaches 50%. This is a typical value representing the particle size, which accurately divides the whole into two equal parts. That is to say, 50% of the particle sizes exceed this value, and 50% of the particle sizes are lower than this value. When D50 is within the particle size range of the target powder, it indicates that the powder quality is good at this time and meets the requirements. If D50 is greater than the upper limit value of the particle size range of the target powder, it indicates that the powder particle size 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 means that the distribution range of the powder diameter is large and not concentrated enough.

[0069] Therefore, the state of the powder can be evaluated through the particle size data of the powder, and its quality can be characterized. In the embodiments 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*.

[0070] Among them, 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 powder particle size distribution width correction value Span*=(D90 - D10) / (d1 - d0).

[0071] Among them, the controller controls 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 less than or equal to Span*, I 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 .

[0072] 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, indicating that the obtained 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). Therefore, for the above-mentioned powder-making defects, appropriate parameters need to be adjusted for compensation, especially through 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 to precisely adjust the process parameters.

[0073] In an alternative embodiment, the pusher 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.

[0074] 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.

[0075] 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, acquires the particle image data of the obtained powder, and obtains the plasma arc length L data through image recognition.

[0076] Optionally, the aforementioned image acquisition device 43 can use a high-speed and high-resolution industrial camera to real-time collect the arc flame image of the plasma arc 42, and through the image processing and recognition algorithm of the existing technology, for example, through the classic contour processing algorithm of OpenCV (such as Canny detection, Sobel detection, Laplacian detection, etc.) to obtain the arc flame edge contour information and process the contour geometric features, obtain the length L of the plasma arc 42, and according to the preset set value of the length of the plasma arc 42, realize the length L of the plasma arc 42 to be stable within the preset range by adjusting the appropriate feeding speed of the electrode rod 11.

[0077] 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;

[0078] 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.

[0079] For example, define I A = 0.3, I B = 0.7, Span* max = 1.3. During the powder-making process, if ID50 <0.3, indicating that the prepared powder is finer (the content of powder finer than the lower limit of the target particle size is higher). The adjustment actions are: reducing the rotation speed w of the electrode rod stock 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.

[0080] If I D50 >0.7, indicating that the prepared powder is coarser (the content of powder coarser than the upper limit of the target particle size is higher). The adjustment actions are: increasing the rotation speed w of the electrode rod stock 11 to refine the coarse particles, with an adjustment step of +(500 - 1000) r / min, and simultaneously reducing the current intensity i of the plasma arc 42 to limit the superheat degree to inhibit the generation of ultrafine particles, with an adjustment step of -(10 - 30) A.

[0081] If 0.3 ≤ ID50 ≤ 0.7, but Span* > 1.2, indicating that the D50 of the prepared powder meets the requirement, but the particle size distribution is too wide (usually due to the coexistence of partial fine powder tails below the lower limit and coarse powder mixtures above the upper limit). The adjustment actions are: reducing the length L of the plasma arc 42 to increase the energy input, with an adjustment step of -(1 - 3) mm, and simultaneously increasing the current intensity i of the plasma arc 42 to promote the uniformity of droplet fragmentation, with an adjustment step of +(10 - 30) A.

[0082] In the above embodiments, it further includes a rod stock vibration monitoring component 32. The rod stock vibration monitoring component 32 is electrically connected to the controller. The rod stock vibration monitoring component 32 is used to monitor the vibration amplitude A of the electrode rod stock 11. Taking the upper limit of the preset allowable range as 0.05 mm and the lower limit as 0.1 mm as an example, the controller controls the powder making state according to whether the vibration amplitude A of the electrode rod stock 11 is within the preset allowable range:

[0083] When A ≤ 0.05 mm, the powder making state is in a normal state;

[0084] 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 stock 11 to decrease;

[0085] When A > 0.1 mm, the powder making state is in an abnormal state, and the controller controls the powder making to stop.

[0086] Specifically, the rod stock 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 stock 11 can be reflected. If A ≤ 0.05 mm, it is in a normal state, and at this time, it can continue to run; if 0.05 < A ≤ 0.1 mm, it is in a warning state, and the rotation speed w is automatically triggered to decrease, with an adjustment step of -(500 - 1000) r / min; if A > 0.1 mm, then it stops immediately, and the dimensional tolerance of the rod stock, as well as the surface wear of the driving roller and the pressure wheel, are checked.

[0087] It should be understood that the implementation of the plasma electrode atomization powder preparation system according to the present invention is applicable to the preparation of metal alloy powders such as titanium alloys and superalloys.

[0088] {Example 2}

[0089] In this embodiment, the powder preparation process is realized by using the above-mentioned plasma rotating electrode atomization powder preparation system based on the powder with the target particle size, including the following steps:

[0090] Step 1, matching initial parameters: determining the particle size range of the target particle size, and determining the initial parameters of powder preparation 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;

[0091] Step 2, trial production: carrying out plasma rotating electrode atomization powder preparation according to the initial parameters, and monitoring the vibration amplitude A of the electrode rod 11 to judge the powder preparation state. If it is in the normal state, it enters the normal powder preparation state;

[0092] Step 3, normal powder preparation: adjusting 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 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 preparation is completed;

[0093] 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*, defining the range of the particle size d of the target powder as d0 to d1, the powder particle size position index I D50 =(D50 - d0) / (d1 - d0), the powder particle size distribution width correction value Span*=(D90 - D10) / (d1 - d0);

[0094] 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%.

[0095] Preferably, in step 3, when the powder particle size position index I D50 exceeds the preset range, two of the parameters 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 are controlled by the controller, so that the powder particle size position index I D50 is stabilized within the preset range;

[0096] When the corrected value Span* of the powder particle size distribution width exceeds the preset range, two of the parameters of the length L of the plasma arc 42 and the current intensity i of the plasma arc 42 are controlled by the controller to stabilize the corrected value Span* of the powder particle size distribution width within the preset range.

[0097] {Example 3}

[0098] In this example, GH3625 alloy powder is prepared according to the process method of the foregoing example.

[0099] 1) Material classification and parameter matching

[0100] GH3625 belongs to nickel-based superalloy, and the parameter window of the reference base material GH4169 is referred to. The preset process parameter range: the rod diameter φ40 - 80 mm (vacuum induction melting or forging densification process), the rotation speed w ranges from 18000 - 28000 r / min, the length L of the plasma arc 42 ranges from 30 - 60 mm, and the plasma arc current intensity i ranges from 1000 - 1500 A.

[0101] 2) Confirmation of the target particle size range

[0102] The target particle size range is powder with ≤53 μm, belonging to the fine particle size type.

[0103] 3) Initial parameter setting

[0104] Determine the initial parameters: Determine the initial parameters: the rod diameter is φ50 mm (vacuum induction melting + forging densification process), the rod rotation speed w is 26000 r / min, the length L of the plasma arc 42 is 40 mm, and the plasma arc current intensity i is 1400 A..

[0105] 4) Rod preparation and inspection

[0106] After inspecting the finished rod, the batch diameter fluctuation of 0.06 mm meets the requirements (≤0.1 mm), and the rod straightness (≤0.025 mm), perpendicularity (≤0.15 mm), and surface roughness (not exceeding Ra1.6 μm) meet the requirements.

[0107] 5) Plasma rotating electrode trial production and parameter regulation

[0108] Set and start the plasma rotating electrode atomization trial production according to the initial parameters. After real-time detection, the vibration amplitude A of the rod ≤0.05 mm, and the dynamic balance of the high-speed rotation of the rod is stable.

[0109] Through the online particle size distribution detection of the powder prepared under the initial parameters, the measured values are 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 rotation speed to promote the refinement of powder particles. Increase the rotation speed w of the bar stock by 1000 r / min (i.e., 27000 r / min), and simultaneously reduce the length L of the plasma arc flame by 2 mm (i.e., 38 mm).

[0110] Carry out online detection on the powder prepared after parameter adjustment, combined with Figure 3 and Figure 4 As shown, the measured values are D10 = 23μm, D50 = 42μm, D90 = 75μm, 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 online detection result of the powder particle shape (sphericity S) is 0.97 (≥0.95), meeting the control requirements, indicating that the parameters match well and the process and powder morphology are normal.

[0111] 6) Verification and mass production

[0112] Carry out powder trial production under the above-mentioned regulated parameters. After completion, take samples of the prepared powder and detect it by the dry sieving method. The proportion of -270 mesh (aperture 53μm) powder reaches 62%; carry out particle size detection on the -270 mesh powder by the laser diffraction method, and the results are D10 = 22μm, D50 = 37μm, D90 = 52μm. In summary, the yield of the target segment (≤53μm) and the powder particle size distribution 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 changes and modifications 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.

[0113] 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 changes and modifications 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 method for adjusting the process parameters of plasma rotating electrode atomization for preparing powders with an expected target particle size, characterized in that, It includes the following steps: During the plasma rotating electrode atomization powder making process, the image data of the powder is monitored in real time, the particle contours are recognized in real time through image recognition software, and the particle size data D10, D50, and D90 are obtained. 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%. Determining the powder state characteristics based on the particle size data includes the powder particle size position index I D50 and the corrected value Span* of the powder particle size distribution width; And According to the powder state characteristics, control the parameters of the material pushing mechanism, the driving mechanism, and the plasma generation system to make I A <I D50 <I B , and Span* is less than or equal to Span* max , where 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.

2. The method for adjusting the process parameters of plasma rotating electrode atomization for preparing powders with an expected target particle size according to claim 1, characterized in that, The powder particle size position index I in the powder state characteristics D50 and the powder particle size distribution width correction value Span* are determined by being set as follows: Powder particle size position index I D50 , I D50 =(D50 - d0) / (d1 - d0); The powder particle size distribution width correction value Span*, Span* = (D90 - D10) / (d1 - d0); Wherein, d0 to d1 define the distribution width range of the target powder particle size d, d0 represents the lower limit of the target powder particle size distribution width, and d1 represents the upper limit of the target powder particle size distribution width.

3. The method for adjusting the process parameters of plasma rotating electrode atomization for preparing powders with an expected target particle size according to claim 1, characterized in that The method further includes: Monitoring the arc flame image of the plasma arc in real time; and Obtaining the length L of the plasma arc based on the recognition of the arc flame image.

4. The method for adjusting the process parameters of plasma rotating electrode atomization for preparing powders with an expected target particle size according to claim 3, characterized in that The method further includes: Monitoring the feeding speed of the pusher mechanism for pushing the electrode rod along its axial direction in real time; Adjusting the distance between the electrode rod and the plasma gun by controlling the feeding speed of the pusher mechanism for driving the electrode rod, thereby controlling the length L of the plasma arc.

5. The method for adjusting the process parameters of plasma rotating electrode atomization for preparing powders with an expected target particle size according to claim 1, characterized in that By monitoring the powder particle size position index I D50 to determine the particle size deviation between the prepared powder and the target powder, where: If I D50 <I A , it is determined that the produced powder is too fine, that is: the content of powder finer than the lower limit of the target particle size is higher than expected; If I D50 >I B , it is determined that the obtained powder is too coarse, that is: the content of powder coarser than the upper limit of the target particle size is higher than expected; If I A <I D50 <I B , it is determined that the particle size distribution of the obtained powder meets the expectation.

6. The method for adjusting the process parameters of plasma rotating electrode atomization for preparing powders with the expected target particle size according to any one of claims 1-5, characterized in that, Controlling the parameters of the material pushing mechanism, the driving mechanism, and the plasma generation system according to the powder state characteristics, so that I A <I D50 <I B , and Span* is less than or equal to Span* max , including: When the powder particle size position index I D50 exceeds the preset range, the controller controls two parameters among the rotation speed w of the electrode rod, the length L of the plasma arc, or the current intensity i of the plasma arc 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 parameters among 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.

7. The method for adjusting the process parameters of plasma rotating electrode atomization for preparing powders with an expected target particle size according to any one of claims 1-5, characterized in that, The method further includes: Monitoring the vibration amplitude A of the electrode rod in real time through the rod vibration monitoring component, and the controller controls the powder making state according to the vibration amplitude A of the electrode rod: When A ≤ 0.05mm, it is determined that the powder making state is in a normal state; When 0.05 < A ≤ 0.1mm, the powder making state is in a warning state, and the controller controls the rotation speed w of the electrode rod to decrease; When A > 0.1mm, the powder making state is in an abnormal state, and the controller controls to stop powder making.

8. The method for adjusting the process parameters of plasma rotating electrode atomization for preparing powders with an expected target particle size according to claim 7, characterized in that, The rod vibration monitoring component uses a laser displacement sensor to monitor the displacement of the pressure roller in the driving mechanism in real time to characterize the vibration state of the electrode rod.

9. The method for adjusting the process parameters of the plasma rotating electrode atomization powder making process for preparing powders with an expected target particle size according to claim 7, characterized in that, The controller controls the rotation speed w of the electrode rod to decrease, and the rotation speed adjustment step size is (500 - 1000) r / min.

10. The method for adjusting the process parameters of plasma rotating electrode atomization for preparing powders with an expected target particle size according to claim 1, characterized in that, The method is applicable to the powder preparation of titanium alloys and superalloys.

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