4D printing device for a titanium-nickel shape memory alloy and method for regulating components thereof

Abstract

The present invention discloses a 4D printing device for a titanium-nickel shape memory alloy and a method for regulating its components; the device includes an industrial control computer, a fiber laser, a collimation and focusing component, a beam splitter, a laser input energy real-time monitor, and a LIBS element detection component. In the present invention, the titanium-nickel alloy powder with a particle size of 15-53 μm is first activated in a discharge plasma-assisted high-energy ball mill, and then metallurgically combined with nano-scale zirconium powder with a particle size of 200-800 nm to obtain a modified mixed powder as the raw material powder for 4D printing and forming; then the modified powder is added to a selective laser melting forming equipment for forming. During the forming process, part of the laser beam is split by the beam splitter into the laser input energy real-time monitor to ensure the consistency of the laser power during the selective laser melting process; at the same time, non-destructive element analysis and monitoring are carried out on the printed and formed layer to identify the variant structure data of the titanium-nickel memory alloy, adaptively match the process database, and realize the 4D printing and regulated forming of the titanium-nickel shape memory alloy with no cracks on the surface and excellent performance.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and particularly relates to a 4D printing device for a titanium-nickel shape memory alloy and a method for regulating and controlling its components. Background Art

[0002] The titanium-nickel shape memory alloy is the earliest developed memory alloy. Due to its excellent memory effect, stable performance, and good biocompatibility, it has received extensive attention in the fields of materials science and engineering and has been widely used in consumer products, industrial applications (intelligent structures and composite materials), automobiles, aerospace, micro actuators and microelectromechanical systems (MEMS), robotics, biomedicine and other fields.

[0003] For the formed titanium-nickel alloy, the traditional casting method and powder metallurgy process are prone to introducing impurity elements such as C and O and composition segregation, and it is difficult to form structures with complex shapes. At the same time, due to the superelastic properties of the titanium-nickel alloy, the subsequent machining process is prone to serious tool wear.

[0004] The problems in the above aspects limit its popularization and application in other fields. To solve the above problems, scientific research workers need to continuously develop and explore new preparation processes.

[0005] Selective laser melting (SLM) technology is a metal additive manufacturing technology that uses metal powder to be completely melted under the thermal action of a laser beam and then solidifies by cooling to form a shape.

[0006] Compared with the traditional method, the samples prepared by SLM technology have higher dimensional accuracy and can process parts with complex shapes that cannot be processed by the traditional method. However, most of the titanium-nickel shape memory alloys printed by SLM have cracks, which seriously affect their mechanical properties and use effects and limit the application of 4D printing of titanium-nickel shape memory alloys. And a slight change in the atomic ratio (Ni / Ti ratio) between the Ni element and the Ti element inside the nickel-titanium alloy will have a great impact on the phase transition temperature of the nickel-titanium alloy (even a 0.1% change in the Ni content will cause a phase transition temperature change of about 10°C). How to prepare a crack-free 4D printed titanium-nickel shape memory alloy that can real-time monitor the Ti / Ni ratio of the formed parts and achieve quality control is the key to this technology. Summary of the Invention

[0007] The object of the present invention is to overcome the above-mentioned shortcomings and deficiencies of the prior art, and to provide a 4D printing device for a titanium-nickel shape memory alloy and a method for regulating its components. By using a modified titanium-nickel alloy powder with a particle size of 15-53 microns added with 2%-5% by mass of nanoscale zirconium powder as the raw material metal powder for forming, during the selective laser melting forming process, a beam splitter divides part of the laser beam into a laser input energy real-time monitoring system to ensure the consistency of the laser power during the printing process. At the same time, non-destructive analysis and monitoring are carried out on the printed forming layer to identify the variant structure data of the titanium-nickel memory alloy, match the process database, realize the intelligent printing of deformation, defect identification, positioning, reconstruction and precise regulation of the Ni / Ti ratio adaptive characteristic process parameters of the nickel-titanium alloy, and steadily improve the quality of the 4D printed components of the titanium-nickel shape memory alloy.

[0008] The present invention is realized through the following technical solutions:

[0009] A 4D printing device for a titanium-nickel shape memory alloy, including a forming chamber, a collimating mirror 3, a focusing mirror 4, a high-speed scanning galvanometer 7 and an industrial control computer 1, characterized in that: the 4D printing device further includes a beam splitter 5, a laser input energy real-time monitor 6 and a LIBS element non-destructive detector 9;

[0010] The beam splitter 5 is arranged on the laser light path between the focusing mirror 4 and the high-speed scanning galvanometer 7; the beam splitter 5 is used to distribute a part of the laser on the laser light path to the laser input energy real-time monitor 6, that is, the laser input energy real-time monitor 6 collects the current laser power value through the beam splitter 5 and transmits it to the industrial control computer 1, and compares it with the preset laser power value in the forming process. When it exceeds the range of 1%-2.5% of the preset laser power value, fine-tuning and correction are carried out;

[0011] The LIBS element non-destructive detector 9 is used for non-destructive element detection of the selectively laser melted formed entity area A, and transmits the non-destructive element detection data to the industrial control computer 1. If the measured value of the element content deviates from the range of 0.3%-0.8%, the industrial control computer 1 then feeds back to the process database to adaptively adjust and control the process parameters.

[0012] A light transmission window 8 is opened on the side wall of the forming chamber, and the light transmission window 8 is a sealed transparent substrate; the LIBS element non-destructive detector 9 is located on the side of the light transmission window 8.

[0013] The LIBS (laser-induced breakdown spectroscopy) element non-destructive detector 9 is a four- or eight-channel fiber optic spectrometer with a wavelength range of 190-1060 nm and an average spectral resolution of 0.08-0.22 nm, mainly detecting and displaying the four elements of Ti, Ni, Zr, and O in the formed titanium-nickel alloy parts; the detection angle of the LIBS element non-destructive detector 9 covers the entire forming working surface.

[0014] In the present invention, titanium-nickel alloy powder with a particle size of 15-53 μm is first activated in a spark plasma assisted ball mill, and then metallurgically combined with nano-scale zirconium powder with a particle size of 200-800 nm to obtain modified mixed powder as the raw material powder for 4D printing and forming; then the modified powder is added to a selective laser melting forming device for forming. Part of the laser beam is split by a beam splitter and sent to a laser input energy real-time monitor to ensure the consistency of the laser power during the selective laser melting process; at the same time, non-destructive elemental analysis and monitoring are performed on the printed and formed layer to identify the variant structure data of the titanium-nickel shape memory alloy, and the process database is adaptively matched to achieve crack-free, uniform microstructure, and high-density 4D printing and forming control of the titanium-nickel shape memory alloy surface.

[0015] The 4D printing device further includes a powder recovery and blanking port 10, a powder cylinder 12, and a flexible powder spreading mechanism 13.

[0016] A method for regulating the quality stability of a 4D printed component is as follows:

[0017] Step 1: According to the attribute requirements of the part, the data model of the part is processed, and the data is imported into the selective laser melting forming system.

[0018] Step 2: Add the modified titanium-nickel alloy mixed powder into the forming cylinder 11, set the initial optimized process parameters, introduce an inert protective gas, evacuate the oxygen in the forming chamber, and keep the oxygen content below 100 ppm during the entire forming process, and then start processing.

[0019] Step 3: During the selective laser melting forming process, the laser input energy real-time monitor 6 collects the current laser power value through the beam splitter 5 and transmits it to the industrial control computer 1, and compares it with the preset laser power value in the forming process. When it is within the range of 1% - 2.5% of the preset laser power value, continue with the processing operation. If it is outside the range of 1% - 2.5% of the preset laser power value, perform fine-tuning and correction.

[0020] The LIBS elemental non-destructive detector 9 is used to perform non-destructive elemental detection on the selectively laser melted and formed solid region A, and transmit the non-destructive elemental detection data to the industrial control computer 1. If the measured value of the elemental content is within the range of 0.3% - 0.8%, then continue to process the next layer; if the measured value of the elemental content is outside the range of 0.3% - 0.8%, after the industrial control computer 1 feeds back to the process database to adaptively match and adjust the process parameters, then process the next layer.

[0021] Step 4: Repeat Step 3 until the entire part is processed, thereby obtaining a titanium-nickel shape memory alloy part with stable quality.

[0022] The modified titanium-nickel alloy mixed powder is obtained by metallurgical bonding of titanium-nickel shape memory alloy powder with a particle size of 15 - 53 μm and nano-scale zirconium powder with a particle size of 200 - 800 nm;

[0023] The metallurgical bonding process is as follows: First, activate the titanium-nickel shape memory alloy powder in a spark plasma-assisted ball mill, and then perform metallurgical bonding with nano-scale zirconium powder with a particle size of 200 - 800 nm to obtain the modified titanium-nickel alloy mixed powder.

[0024] The mass fraction of the nano-scale zirconium powder is 2% - 5%.

[0025] The conditions for the metallurgical bonding discharge treatment are: voltage 110 - 130 V, current 1 - 2 A, electrode rotation speed 500 - 1000 r / min, the duration of the discharge treatment is 1.0 - 5 h, the number of discharge treatments is 3 - 5 times, and the interval between two adjacent discharge treatments is 0.5 - 1 h; the entire treatment process is carried out in an argon atmosphere.

[0026] The operating parameters of selective laser melting are: laser power 160 - 200 W, scanning speed 400 - 600 mm / s, scanning spacing 0.08 mm, powder layer thickness 0.03 mm; the scanning strategy adopts an orthogonal layer fault scanning strategy.

[0027] Compared with the prior art, the present invention has the following advantages and effects:

[0028] 1. Select titanium-nickel alloy powder added with zirconium element as the forming material. The zirconium element promotes the precipitation of second phases such as Ti2Ni, hinders grain growth and refines grains. The average grain size of the part is smaller, the number of grain boundaries per unit volume is larger, and the propagation of cracks needs to pass through more grain boundaries, achieving the effect of suppressing crack generation and propagation.

[0029] 2. At the same time, the addition of zirconium element improves the recovery force of the titanium-nickel memory alloy. The principle is that with the addition of more zirconium, the binding force between atoms increases, the strength of the alloy increases accordingly, and the yield strength of martensite also increases correspondingly, with better mechanical properties.

[0030] 3. Using the special equipment of the present invention, during the selective laser melting forming process, the consistency of the laser input energy is closed-loop controlled, realizing precise control of key technical parameters (such as laser energy input, spot size, scanning parameters, etc.) during the printing process of the titanium-nickel memory alloy.

[0031] 4. Perform element non-destructive analysis and monitoring on the printed forming layer, which can identify the data of the variant structure components of the titanium-nickel memory alloy. Combining with the matching process database, it realizes deformation, defect identification, positioning and reconstruction, and precise regulation of the Ni / Ti ratio adaptive characteristic process parameters of the nickel-titanium alloy for intelligent printing. Description of the Drawings

[0032] Figure 1 This is a schematic diagram of the principle of the 4D printing device of the present invention.

[0033] Figure 2 This is a schematic diagram of the 4D control printing operation process of a titanium-nickel shape memory alloy.

[0034] Appendix Figure 1 Label description: industrial control computer 1, fiber laser 2, collimating mirror 3, focusing mirror 4, beam splitter 5, laser input energy real-time monitor 6, high-speed scanning galvanometer 7, light-transmitting window 8, LIBS element non-destructive detector 9, powder recovery hopper 10, forming cylinder 11, powder cylinder 12, flexible powder spreading mechanism 13; A - laser selective melting formed entity, B - laser selective melting forming area. Specific implementation mode

[0035] The present invention will be further described in detail below in conjunction with specific embodiments.

[0036] Embodiment

[0037] As Figure 1-2 shown. The present invention discloses a 4D printing device for a titanium-nickel shape memory alloy, including a forming chamber, a collimating mirror 3, a focusing mirror 4, a high-speed scanning galvanometer 7 and an industrial control computer 1. The 4D printing device further includes a beam splitter 5, a laser input energy real-time monitor 6 and a LIBS element non-destructive detector 9;

[0038] The beam splitter 5 is arranged on the laser optical path between the focusing mirror 4 and the high-speed scanning galvanometer 7; the beam splitter 5 is used to distribute a part of the laser on the laser optical path to the laser input energy real-time monitor 6, that is, the laser input energy real-time monitor 6 collects the current laser power value through the beam splitter 5 and transmits it to the industrial control computer 1, and compares it with the preset laser power value in the forming process. When it exceeds the range of 1% - 2.5% of the preset laser power value, fine-tuning and correction are performed;

[0039] The LIBS element non-destructive detector 9 is used to perform non-destructive element detection on the laser selective melting formed entity area A, and transmit the non-destructive element detection data to the industrial control computer 1. If the measured value of the element content deviates from the range of 0.3% - 0.8%, the industrial control computer 1 will feedback to the process database to adaptively adjust and control the process parameters.

[0040] A light-transmitting window 8 is opened on the side wall of the forming chamber. The light-transmitting window 8 is a sealed transparent substrate; the LIBS element non-destructive detector 9 is located on the side of the light-transmitting window 8.

[0041] The LIBS (Laser Induced Breakdown Spectroscopy) element non-destructive detector 9 is a four- or eight-channel fiber optic spectrometer with a wavelength range of 190 - 1060 nm and an average spectral resolution of 0.08 - 0.22 nm. It mainly detects four elements, namely Ti, Ni, Zr, and O, in the formed titanium-nickel alloy parts. The detection angle of the LIBS element non-destructive detector 9 covers the entire forming operation surface.

[0042] The 4D printing device further includes a powder recovery and blanking port 10, a powder cylinder 12, and a flexible powder spreading mechanism 13.

[0043] In the present invention, first, titanium-nickel alloy powder with a particle size of 15 - 53 μm is activated in a spark plasma assisted ball mill, and then metallurgically combined with nanoscale zirconium powder with a particle size of 200 - 800 nm to obtain a modified mixed powder as the raw material powder for 4D printing forming. Then, the modified powder is added to a selective laser melting forming equipment for forming. Part of the laser beam is split by a beam splitter and sent to a laser input energy real-time monitor to ensure the consistency of the laser power during the selective laser melting process. At the same time, element non-destructive analysis and monitoring are carried out on the printed and formed layer to identify the variant structure data of the titanium-nickel shape memory alloy, and the process database is adaptively matched to achieve crack-free and excellent performance 4D printing controlled forming of the titanium-nickel shape memory alloy surface.

[0044] A method for regulating the quality stability of a 4D printed component is as follows:

[0045] Step 1: According to the attribute requirements of the part, perform data processing on the data model of the part and import the data into the selective laser melting forming system.

[0046] Step 2: Add the modified titanium-nickel alloy mixed powder into the forming cylinder 11, set the initial optimized process parameters, introduce an inert protective gas, evacuate the oxygen in the forming chamber, and keep the oxygen content below 100 ppm during the entire forming process, and then start processing.

[0047] Step 3: During the selective laser melting forming process, the laser input energy real-time monitor 6 collects the current laser power value through the beam splitter 5 and transmits it to the industrial control computer 1, and compares it with the preset laser power value in the forming process. When it is within the range of 1% - 2.5% of the preset laser power value, continue with the processing operation. If it is outside the range of 1% - 2.5% of the preset laser power value, perform fine-tuning and correction.

[0048] The LIBS element non-destructive detector 9 is used to perform element non-destructive detection on the selectively laser melted and formed solid area A, and transmit the element non-destructive detection data to the industrial control computer 1. If the measured value of the element content is within the range of 0.3% - 0.8%, then continue to process the next layer. If the measured value of the element content is outside the range of 0.3% - 0.8%, after the industrial control computer 1 feeds back to the process database for adaptive matching and adjustment of the process parameters, then process the next layer.

[0049] Step 4: Repeat Step 3 until the entire part is machined to obtain a titanium-nickel shape memory alloy part with stable quality.

[0050] The modified titanium-nickel alloy mixed powder is obtained by metallurgical bonding of titanium-nickel shape memory alloy powder with a particle size of 15 - 53 μm and nanoscale zirconium powder with a particle size of 200 - 800 nm.

[0051] The metallurgical bonding process is as follows: First, activate the titanium-nickel shape memory alloy powder in a spark plasma-assisted ball mill, and then perform metallurgical bonding with nanoscale zirconium powder with a particle size of 200 - 800 nm to obtain the modified titanium-nickel alloy mixed powder.

[0052] The mass fraction of the added nanoscale zirconium powder is 2.5%.

[0053] The discharge treatment conditions for promoting powder activity activation are: voltage 110V, current 1.2A, electrode rotation speed 1000 r / min, discharge treatment duration 1.5 h, number of discharge treatments three times, and the interval between adjacent two discharge treatments 0.5 h.

[0054] The discharge treatment conditions for powder metallurgical bonding are: add ball milling medium, voltage 120V, current 1.6A, electrode rotation speed 600 r / min, discharge treatment duration 4 h, number of discharge treatments four times, and the interval between adjacent two discharge treatments 0.5 h.

[0055] The optimized forming process parameters are: laser power 160W, scanning speed 600 mm / s, scanning spacing 0.08 mm, powder layer thickness 0.03 mm; the scanning strategy adopts an orthogonal layer fault scanning strategy.

[0056] The regulation scheme of the present invention provides metallurgically bonded titanium-nickel alloy modified powder with 2.5% zirconium added as the forming raw material, real-time monitoring of the laser input energy to ensure the consistency of the laser power during the printing process, non-destructive analysis and monitoring of the printed forming layer, identification of the titanium-nickel memory alloy variant structure data, and matching with the process database, so as to improve the quality of the 4D printing components of the titanium-nickel shape memory alloy.

[0057] As described above, the present invention can be preferably realized.

[0058] The implementation manners of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement manners and are all included in the protection scope of the present invention.

Claims

1. A method for regulating the quality stability of 4D printed components by a 4D printing device for a titanium-nickel shape memory alloy, characterized in that, The 4D printing device for the titanium-nickel shape memory alloy includes a forming chamber, a focusing mirror (4), a high-speed scanning galvanometer (7), and an industrial control computer (1). The 4D printing device further includes a beam splitter (5), a laser input energy real-time monitor (6), and a LIBS element non-destructive detector (9); The beam splitter (5) is arranged on the laser light path between the focusing mirror (4) and the high-speed scanning galvanometer (7); the beam splitter (5) is used to distribute a part of the laser on the laser light path to the laser input energy real-time monitor (6), that is, the laser input energy real-time monitor (6) collects the current laser power value through the beam splitter (5) and transmits it to the industrial control computer (1), and compares it with the preset laser power value in the forming process. When it exceeds the range of 1% - 2.5% of the preset laser power value, fine-tuning correction is performed; The LIBS element non-destructive detector (9) is used to perform non-destructive element detection on the laser selective melting formed solid region A, and transmit the non-destructive element detection data to the industrial control computer (1). If the measured element content deviates from the range of 0.3% - 0.8%, the industrial control computer (1) will feedback to the process database to adaptively adjust the process parameters; The regulation method is as follows: Step 1: According to the attribute requirements of the part, perform data processing on the data model of the part, and import the data into the laser selective melting forming system; Step 2: Add the modified titanium-nickel alloy mixed powder into the forming cylinder (11), set the initial optimized process parameters, introduce an inert protective gas, evacuate the oxygen in the forming chamber, so that the oxygen content remains below 100 ppm during the whole forming process, and start processing; Step 3: During the laser selective melting forming process, the laser input energy real-time monitor (6) collects the current laser power value through the beam splitter (5) and transmits it to the industrial control computer (1), and compares it with the preset laser power value in the forming process. When it is within the range of 1% - 2.5% of the preset laser power value, continue with the processing operation. If it is outside the range of 1% - 2.5% of the preset laser power value, perform fine-tuning correction; The LIBS element non-destructive detector (9) is used to perform non-destructive element detection on the laser selective melting formed solid region A, and transmit the non-destructive element detection data to the industrial control computer (1). If the measured element content is within the range of 0.3% - 0.8%, then continue to process the next layer; if the measured element content is outside the range of 0.3% - 0.8%, after the industrial control computer (1) feedbacks to the process database to adaptively match and adjust the process parameters, then process the next layer; Step 4: Repeat Step 3 until the whole part is processed, so as to obtain a titanium-nickel shape memory alloy part with stable quality; The modified titanium-nickel alloy mixed powder is obtained by metallurgical bonding of titanium-nickel shape memory alloy powder with a particle size of 15 - 53 μm and nano-scale zirconium powder with a particle size of 200 - 800 nm; The metallurgical bonding process is: first activate the titanium-nickel shape memory alloy powder in a discharge plasma-assisted high-energy ball mill, and then perform metallurgical bonding with nano-scale zirconium powder with a particle size of 200 - 800 nm to obtain the modified titanium-nickel alloy mixed powder.

2. The method for regulating the quality stability of 4D printed components by the 4D printing device for a titanium-nickel shape memory alloy according to claim 1, characterized in that: A light-transmitting window (8) is provided on the side wall of the forming chamber, and the light-transmitting window (8) is a sealed transparent substrate; the LIBS element non-destructive detector (9) is located on the side of the light-transmitting window (8).

3. The method for regulating the quality stability of 4D printed components by the 4D printing device for a titanium-nickel shape memory alloy according to claim 2, characterized in that: The LIBS element non-destructive detector (9) is a four- or eight-channel fiber optic spectrometer with a wavelength range of 190 - 1060 nm and an average spectral resolution of 0.08 - 0.22 nm, mainly for detecting and displaying four elements of Ti, Ni, Zr, and O in the formed titanium-nickel alloy parts; the detection angle of the LIBS element non-destructive detector (9) covers the entire forming operation surface.

4. The method for regulating the quality stability of 4D printed components by the 4D printing device for a titanium-nickel shape memory alloy according to claim 2, characterized in that: The 4D printing device further includes a powder recovery and blanking port (10), a powder cylinder (12), and a flexible powder spreading mechanism (13).

5. The method for regulating the quality stability of 4D printed components by the 4D printing device for a titanium-nickel shape memory alloy according to claim 2, characterized in that, The mass fraction of the nano-level zirconium powder is 2% - 5%.

6. The method for regulating the quality stability of 4D printed components by the 4D printing device for a titanium-nickel shape memory alloy according to claim 2, characterized in that, The metallurgical bonding discharge treatment conditions are as follows: voltage 110 - 130 V, current 1 - 2 A, electrode rotation speed 500 - 1000 r / min, the duration of the discharge treatment is 1.0 - 5 h, the number of discharge treatment times is 3 - 5 times, and the interval between two adjacent discharge treatments is 0.5 - 1 h; the entire treatment process is carried out in an argon atmosphere.

Images