Interlayer hammering ultrasonic in-situ auxiliary composite additive manufacturing method and device

Abstract

The invention discloses an interlayer hammering ultrasonic in-situ auxiliary composite additive manufacturing method and device. The method comprises the steps that a forming base plate or a to-be-repaired part is fixed to a machining platform; preparing a laser cladding layer on the forming substrate or the to-be-repaired part by using a preset laser cladding process; after the preset number of laser cladding layers are newly formed every time, the thicknesses of the preset number of laser cladding layers are obtained; according to the thickness of the preset number of laser cladding layers, parameters of ultrasonic waves are adjusted; and according to the adjusted ultrasonic parameters, ultrasonic waves are controlled to achieve interlayer hammering aging treatment and ultrasonic energy field auxiliary aging treatment on the preset number of laser cladding layers at the same time. The additive manufacturing forming quality and efficiency of the metal parts are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of laser additive manufacturing, and in particular to an interlayer hammering ultrasonic in-situ assisted composite additive manufacturing method and device. Background Art

[0002] Laser additive manufacturing technology, also known as laser 3D printing technology, is different from traditional "subtractive" manufacturing technology (using cutting and grinding methods to process raw materials to produce parts of the desired shape). It manufactures parts by stacking materials layer by layer. Starting from computer-aided design (CAD), the three-dimensional solid model is sliced ​​into two-dimensional layers, and the two-dimensional layers are discretized into one-dimensional lines. Laser cladding technology is used for point-by-point stacking, and finally a laser manufacturing technology for forming three-dimensional solid parts is realized. It can efficiently process parts with complex geometric shapes, with a small amount of material waste, improve production efficiency, shorten production cycle, and improve material utilization.

[0003] However, there are still some challenges in "structural control" and "performance control" for additively manufactured parts. First, due to uneven temperature distribution and large temperature gradients, defects such as cracks and pores may appear in additive parts. Thermal effects can cause a large amount of residual tensile stress, and the high cooling rate properties can cause oxidation phase changes and large columnar crystal structures in additively manufactured parts, which seriously affect the tensile properties and fatigue life of the parts. Second, different positions of key components need to bear corresponding functions. During use, stress concentration is very likely to form in local positions, resulting in deformation and cracks, leading to fatigue failure of the entire component. Therefore, the damaged area has higher performance requirements. Therefore, it is necessary to improve the performance of additive parts through effective strengthening methods.

[0004] For example, Chinese patent CN107520449A discloses a mold deposition forming laser impact forging composite additive manufacturing method and device. The patent first casts the mold body, melts the metal powder through a heat source to form a cladding layer, and the controller controls the laser generator to synchronously impact forge the molten metal area at the plastic deformation temperature. Then the cladding layer is stacked layer by layer to a certain thickness until the workpiece is formed and then the workpiece surface is treated. The patent has the following shortcomings: the metallurgical bonding between the laser cladding formed part and the mold body makes demolding extremely difficult. At the same time, laser impact forging has the problem of a shallow action layer, so it is impossible to effectively improve the internal defects of large molded parts.

[0005] For example, Chinese patent CN103862050A discloses a metal 3D printer and its printing method based on interlayer impact strengthening process. The patented process combines three processes of cladding, heating and strengthening, aiming to improve the performance of 3D printed metal parts. However, the process has practical problems: it is difficult to eliminate internal defects by laser shock strengthening after the cladding layer cools; the heating device of the cladding layer is complicated, and the local heating technology is difficult and inefficient; it is difficult to achieve local strengthening by mechanical shot peening, and the shot cleaning is difficult. These limitations affect the promotion and popularization of the patented process in practical applications.

[0006] For example, Chinese patent CN108176857A discloses a metal 3D printing composite manufacturing method and device thereof, and discloses the technical features of "under the action of an ultrasonic vibration energy field, fusing metal powder according to a preset 3D printing and filling scanning path to form a cladding layer of a workpiece; simultaneously subjecting the cladding layer to laser shock treatment under the action of an ultrasonic vibration energy field, so that the ultrasonic vibration wave and the shock wave induced by the laser shock impact forge the cladding layer; and stacking the cladding layer layer by layer to obtain a workpiece". In this method, a laser nozzle emits a laser and simultaneously combines with an ultrasonic vibration wave emitted by an ultrasonic vibrator to impact forge the cladding layer. This is a combination of three processes: cladding or melting / solidification-laser shock+ultrasonic shock. The process parameters of these three processes are selected independently, do not affect each other, and are implemented separately. In the interlayer laser shock control process, since the constraining layer (such as water and black tape used in the traditional way) needs to be replaced after each treatment, it not only increases the complexity and cost of the process, but also leads to low actual processing efficiency, because replacing the constraining layer requires additional time and resources, thus limiting the wide application and efficient implementation of the interlayer control technology. Therefore, those skilled in the art are in urgent need of exploring a new interlayer control process. Summary of the invention

[0007] In order to solve the technical problems existing in the background technology, the present invention proposes an interlayer hammering ultrasonic in-situ assisted composite additive manufacturing method and device.

[0008] In a first aspect, the present invention provides an interlayer hammering ultrasonic in-situ assisted composite additive manufacturing method and device, comprising:

[0009] Fix the formed substrate or the parts to be repaired on the processing platform;

[0010] Using a preset laser cladding process to prepare a laser cladding layer on the formed substrate or the component to be repaired;

[0011] wherein after each preset number of laser cladding layers are newly formed, the thickness of the preset number of laser cladding layers is obtained;

[0012] According to the thickness of the preset number of laser cladding layers, adjusting the parameters of the ultrasonic wave; wherein the ultrasonic wave is a combined ultrasonic wave formed by two ultrasonic waves of different frequencies;

[0013] According to the adjusted ultrasonic parameters, the ultrasonic wave is controlled to simultaneously realize interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment for the preset number of laser cladding layers.

[0014] Preferably, the ultrasonic wave is controlled according to the adjusted ultrasonic parameters to simultaneously implement interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment on the preset number of laser cladding layers, specifically including:

[0015] Obtaining the temperature of the preset number of laser cladding layers;

[0016] When the temperature of the preset number of laser cladding layers is in the preset optimal plastic forming temperature range, the ultrasonic wave is controlled according to the adjusted ultrasonic parameters to simultaneously achieve interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment on the preset number of laser cladding layers.

[0017] Preferably, before preparing a laser cladding layer on the molded substrate or the component to be repaired by using a preset laser cladding process, the method further includes:

[0018] According to the damage area and depth of the damaged area of ​​the model of the part to be formed or the part to be repaired, the number of printing layers of the part to be formed or the part to be repaired and the thickness of each printing layer are obtained;

[0019] According to the number of printing layers of the part to be formed or repaired and the thickness of each printing layer, the number of times that ultrasonic waves are used to simultaneously realize interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment during the entire printing process and the number of newly formed laser cladding layers before each simultaneous use of ultrasonic waves to realize interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment are determined.

[0020] Preferably, the frequency of each ultrasonic wave in the combined ultrasonic wave is within the range of 18-35 KHz.

[0021] Preferably, the influence depth H of the ultrasonic energy field assisted aging treatment layer is U The following conditions need to be met:

[0022] H U有效 >H D ×n;

[0023] In the formula, H U有效 It represents the influence depth of ultrasonic energy field assisted aging treatment, H D is the thickness of a single laser cladding layer, n is the number of layers of the preset number of laser cladding layers, and n is a positive integer;

[0024] in,

[0025] In the formula, H U有效 represents the effective depth of grain refinement, a represents the material absorption coefficient, and w 0 represents the initial power density, and Wthreshold represents the threshold power density for grain refinement.

[0026] Preferably, the impact depth of interlayer hammer aging treatment must meet the following conditions:

[0027] H C >H S >H R ;

[0028] In the formula, H C H is the depth of influence of interlayer peening treatment, that is, the depth of work hardening caused by peening; R H is the remelting depth, that is, the depth of the remelting of the surface of the previous laser cladding layer when the new layer is laser cladding. S is the thickness of the plastic deformation layer.

[0029] In a second aspect, the present invention also proposes an interlayer hammering ultrasonic in-situ assisted composite additive manufacturing device, comprising: a laser cladding mechanism, a powder feeding mechanism, a cladding workshop, a thickness measuring mechanism, a heat source nozzle, a three-dimensional moving mechanism, an ultrasonic hammering mechanism and a control mechanism;

[0030] The workbench is arranged horizontally in the cladding workshop; the powder feeding mechanism is used to lay metal powder on the molding substrate or the parts to be repaired fixed on the processing platform;

[0031] The three-dimensional moving mechanism is located in the cladding workshop on one side of the workbench; the ultrasonic hammer head of the ultrasonic hammering mechanism and the heat source nozzle of the laser cladding mechanism are both installed on the moving end of the three-dimensional moving mechanism, and the three-dimensional moving mechanism is used to drive the heat source nozzle and the ultrasonic hammer head to move;

[0032] The laser cladding control mechanism is used to perform laser cladding on the metal powder located on the formed substrate or the part to be repaired through the heat source nozzle; the thickness measuring mechanism is used to measure the thickness; the ultrasonic hammering mechanism is used to simultaneously realize the interlayer hammering aging treatment and the ultrasonic energy field assisted aging treatment through the ultrasonic wave output by the ultrasonic hammer head; wherein the ultrasonic wave is a combined ultrasonic wave formed by two ultrasonic waves of different frequencies;

[0033] The powder feeding mechanism, thickness measuring mechanism, three-dimensional moving mechanism, laser cladding mechanism and ultrasonic hammering mechanism are all electrically connected to the control mechanism, and the control mechanism is used to control the powder feeding mechanism, three-dimensional moving mechanism, thickness measuring mechanism, laser cladding mechanism and ultrasonic hammering mechanism to coordinate their actions to achieve layer-by-layer printing and forming of the parts to be formed or layer-by-layer printing and repair of the parts to be repaired.

[0034] Preferably, during the printing process, the control mechanism controls the powder feeding mechanism, the three-dimensional moving mechanism and the laser cladding mechanism to cooperate to perform laser cladding on the formed substrate or the component to be repaired to form a laser cladding layer;

[0035] After each preset number of laser cladding layers are newly formed, the control mechanism controls the thickness measuring mechanism to obtain and store the thickness of the laser cladding layers;

[0036] The control mechanism adjusts the ultrasonic parameters according to the thickness of the preset number of laser cladding layers;

[0037] The control mechanism controls the three-dimensional moving mechanism and the ultrasonic hammering mechanism to cooperate so that the ultrasonic hammer head can simultaneously perform interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment on the preset number of laser cladding layers according to the adjusted ultrasonic parameters.

[0038] Preferably, it also includes an infrared thermal imager, which is electrically connected to the control mechanism;

[0039] The control mechanism is also used to control the infrared thermal imager to take the temperature of the preset number of laser cladding layers; when the temperature of the preset number of laser cladding layers is in a preset optimal plastic forming temperature range, the ultrasonic wave is controlled according to the adjusted ultrasonic parameters to simultaneously achieve interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment for the preset number of laser cladding layers.

[0040] Preferably, the control mechanism is used to obtain the number of printing layers of the part to be formed or the part to be repaired and the thickness of each printing layer according to the damaged area and depth of the damaged area of ​​the model of the part to be formed or the part to be repaired, before controlling the powder feeding mechanism, the three-dimensional moving mechanism, the thickness measuring mechanism, the laser cladding mechanism and the ultrasonic hammering mechanism to coordinate the actions to realize the layer-by-layer printing and forming of the part to be formed or the layer-by-layer printing and repair of the part to be repaired;

[0041] According to the number of printing layers of the part to be formed or repaired and the thickness of each printing layer, the number of times that ultrasonic waves are used to simultaneously realize interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment during the entire printing process and the number of newly formed laser cladding layers before each simultaneous use of ultrasonic waves to realize interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment are determined.

[0042] Preferably, the three-dimensional moving mechanism comprises two first moving rails, two sliders, a second moving rail, two first driving assemblies, a second driving assembly, a third driving assembly and a fourth driving assembly;

[0043] Two first movable guide rails are symmetrically fixed on two opposite side walls of the cladding workshop, and each first movable guide rail is arranged vertically;

[0044] The two sliders are respectively slidably arranged on the two first movable guide rails in the vertical direction; the two first driving assemblies are respectively drivingly connected to the two sliders, and the first driving assemblies are used to drive the corresponding sliders to slide vertically along the first movable guide rails;

[0045] Each first sliding block is provided with a sliding groove arranged along its length direction.

[0046] The second movable guide rail is horizontally arranged between the two first sliders, and the two ends of the second movable guide rail slide in the slide grooves of the two sliders respectively. The second driving component is drivingly connected to the second movable guide rail, and the second driving component is used to drive the second guide rail to slide along the length direction of the slider;

[0047] The heat source nozzle and the ultrasonic hammer are both slidably connected to the second movable guide rail, the third driving assembly is drivably connected to the heat source nozzle, and the third driving assembly is used to drive the heat source nozzle to slide along the second movable guide rail, and the fourth driving assembly is drivably connected to the ultrasonic hammer, and the fourth driving assembly is used to drive the ultrasonic hammer to slide along the second movable guide rail;

[0048] The first drive assembly, the second drive assembly, the third drive assembly and the fourth drive assembly are all electrically connected to the control mechanism.

[0049] Preferably, the ultrasonic wave is a combined ultrasonic wave formed by ultrasonic waves of multiple different frequencies.

[0050] Preferably, the combined ultrasonic wave comprises ultrasonic waves of two different frequencies.

[0051] Preferably, the frequency of each ultrasonic wave in the combined ultrasonic wave is within the range of 18-35 KHz.

[0052] Preferably, the influence depth H of the ultrasonic energy field assisted aging treatment layer is U The following conditions need to be met:

[0053] H U有效 >H D ×n;

[0054] In the formula, H U有效 It represents the influence depth of ultrasonic energy field assisted aging treatment, H D is the thickness of a single laser cladding layer, n is the number of layers of the preset number of laser cladding layers, and n is a positive integer;

[0055] in,

[0056] In the formula, H U有效 represents the effective depth of grain refinement, a represents the material absorption coefficient, and w 0 represents the initial power density, and Wthreshold represents the threshold power density for grain refinement.

[0057] Preferably, the impact depth of interlayer hammer aging treatment must meet the following conditions:

[0058] H C >H S >H R ;

[0059] In the formula, H C H is the depth of influence of interlayer peening treatment, that is, the depth of work hardening caused by peening; R H is the remelting depth, that is, the depth of the remelting of the surface of the previous laser cladding layer when the new layer is laser cladding; S is the thickness of the plastic deformation layer.

[0060] In the present invention, the proposed interlayer hammering ultrasonic in-situ assisted composite additive manufacturing method and device obtains the thickness of the preset number of laser cladding layers after each new number of laser cladding layers are formed; according to the thickness of the preset number of laser cladding layers, the parameters of the ultrasonic wave are adjusted so that the ultrasonic wave performs ultrasonic hammering forging on the preset number of laser cladding layers to realize the combined application of interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment, and ensures that the surface coverage rate reaches 100%, and the influence depth of the ultrasonic energy field assisted aging treatment during hammering forging in the depth direction can cover The preset number of laser cladding layers allows for a smooth geometric transition at the bonding points of the laser cladding layers, thereby greatly reducing stress concentration caused by excess height and pits at the bonding points; moreover, laser cladding and ultrasonic hammer forging are performed alternately to efficiently and high-quality complete the "forging constraint" forming in the same process, ultimately obtaining metal parts with a certain value of residual compressive stress generated inside and with strengthened internal materials, greatly improving the fatigue strength and fatigue life of the metal parts, eliminating residual stress, reducing the generation of defects such as deformation and cracking, and improving the additive manufacturing forming quality and efficiency of metal parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 A schematic diagram of the process of an interlayer hammering ultrasonic in-situ assisted composite additive manufacturing method in one embodiment of the present invention.

[0062] Figure 2 This is a schematic structural diagram of an interlayer hammering ultrasonic in-situ assisted composite additive manufacturing device in one embodiment of the present invention.

[0063] Figure 3 It is a schematic flow chart of the printing process of each layer in one embodiment of the present invention.

[0064] Figure 4A schematic diagram of the microstructure detection results in an embodiment of the present invention; wherein, a1 is a schematic diagram of the microstructure detection results of a metal structure without interlayer hammering at a size of 250μm, a2 is a schematic diagram of the microstructure detection results of a metal structure without interlayer hammering at a size of 50μm, b1 is a schematic diagram of the microstructure detection results of a metal structure with interlayer hammering at a size of 250μm, and b2 is a schematic diagram of the microstructure detection results of a metal structure with interlayer hammering at a size of 50μm. DETAILED DESCRIPTION

[0065] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0066] First, as Figure 1 As shown, the present invention also proposes an interlayer hammering ultrasonic in-situ assisted composite additive manufacturing method, comprising:

[0067] Fix the formed substrate or the parts to be repaired on the processing platform;

[0068] Using a preset laser cladding process to prepare a laser cladding layer on the formed substrate or the component to be repaired;

[0069] After each preset number of laser cladding layers are newly formed, obtaining the thickness of the preset number of laser cladding layers;

[0070] According to the thickness of the preset number of laser cladding layers, adjusting the parameters of the ultrasonic wave; wherein the ultrasonic wave is a combined ultrasonic wave formed by two ultrasonic waves of different frequencies;

[0071] According to the adjusted ultrasonic parameters, the ultrasonic wave is controlled to simultaneously realize interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment for the preset number of laser cladding layers.

[0072] The present invention obtains the thickness of the preset number of laser cladding layers after each newly formed preset number of laser cladding layers; adjusts the ultrasonic parameters according to the thickness of the preset number of laser cladding layers, so that the ultrasonic wave performs ultrasonic hammer forging on the preset number of laser cladding layers to realize the combined application of interlayer hammer aging treatment and ultrasonic energy field assisted aging treatment, and ensures that the surface coverage rate reaches 100%, and the influence depth of the ultrasonic energy field assisted aging treatment during hammer forging in the depth direction can cover the preset number of laser cladding layers, so that a smooth geometric transition is generated at the bonding point of the laser cladding layers, thereby greatly reducing the stress concentration caused by the residual height and pits at the bonding point; and, laser cladding and ultrasonic hammer forging are alternately performed, and the "forging constraint" forming is completed efficiently and with high quality in the same process, and finally a metal part with a certain value of residual compressive stress generated inside and the internal material strengthened is obtained, the fatigue strength and fatigue life of the metal part are greatly improved, the residual stress is eliminated, the generation of defects such as deformation and cracking is reduced, and the additive manufacturing forming quality and efficiency of the metal part are improved.

[0073] Among them, interlayer hammering aging treatment is a process that introduces local plastic deformation on the surface of the laser cladding layer through ultrasonic hammering, mainly forming a reinforced plastic deformation layer on the surface of the cladding layer. This treatment method has a shallow depth of action and is mainly used to improve the surface microstructure to improve the surface hardness and fatigue resistance.

[0074] Among them, ultrasonic energy field assisted aging treatment is a process method that uses the high-frequency ultrasonic energy field emitted by the hammer probe to act on the printed laser cladding layer, further refining the grains inside the cladding layer and reducing residual stress. The depth of action of this treatment method can be achieved by adjusting the ultrasonic frequency combination, thereby affecting the mechanical properties of the deeper layer of the cladding layer.

[0075] In this embodiment, the process of measuring the thickness of the laser cladding layer includes:

[0076] The thickness of the laser cladding layer was measured using a micrometer.

[0077] In this embodiment, the ultrasonic wave is controlled according to the adjusted ultrasonic parameters to simultaneously implement the interlayer hammering aging treatment and the ultrasonic energy field assisted aging treatment on the preset number of laser cladding layers, specifically including:

[0078] Obtaining the temperature of the preset number of laser cladding layers;

[0079] When the temperature of the preset number of laser cladding layers is in the preset optimal plastic forming temperature range, the ultrasonic wave is controlled according to the adjusted ultrasonic parameters to simultaneously achieve interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment on the preset number of laser cladding layers.

[0080] This embodiment can monitor the real-time temperature of the laser cladding layer online in real time. After the laser cladding layer is clad, when its temperature field is in the optimal plastic forming temperature range, the ultrasonic wave is controlled according to the adjusted ultrasonic parameters to perform ultrasonic hammer forging on the preset number of laser cladding layers in the optimal plastic forming temperature range. In addition, the GPa-level shock wave induced by the combined ultrasonic wave produces a mechanical effect, which can effectively improve the microstructure of the metal, thereby forming refined metal grains.

[0081] In this embodiment, before using a preset laser cladding process to prepare a laser cladding layer on the formed substrate or the component to be repaired, the process further includes:

[0082] According to the damage area and depth of the damaged area of ​​the model of the part to be formed or the part to be repaired, the number of printing layers of the part to be formed or the part to be repaired and the thickness of each printing layer are obtained;

[0083] According to the number of printing layers of the part to be formed or repaired and the thickness of each printing layer, the number of times that ultrasonic waves are used to simultaneously realize interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment during the entire printing process and the number of newly formed laser cladding layers before each simultaneous use of ultrasonic waves to realize interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment are determined.

[0084] Among them, the number of newly formed laser cladding layers before each use of ultrasound to simultaneously achieve interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment can be the same or different, which is specifically determined according to the number of printed layers of the part to be formed or the part to be repaired, the thickness of each printed layer and the aging treatment range of the ultrasonic wave, thereby improving the printing efficiency while ensuring the effects of the interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment.

[0085] The ultrasonic wave outputted by the ultrasonic source in this embodiment is a combined ultrasonic wave formed by ultrasonic waves of multiple different frequencies.

[0086] Since the farther the ultrasonic wave propagates, the weaker the echo signal is, in order to avoid limiting the impact depth of the ultrasonic interlayer hammering process, this embodiment uses a combined wave composed of multiple ultrasonic waves of different frequencies to impact forge the metal layer in the forging temperature window, so that the ultrasonic signal can be transmitted to a farther distance, achieving 100% coverage of the laser cladding layers.

[0087] Specifically, the combined ultrasonic wave includes two ultrasonic waves of different frequencies.

[0088] Assume that the frequencies of the two ultrasonic waves are f 1 and f 2 The calculation formula for the influence depth of ultrasonic energy field assisted aging treatment is: Where C is the speed of sound wave propagation in metal materials (unit: m / s). The speed of sound wave propagation in different metal materials is different. 1 and f 2 is the frequency of two different ultrasonic waves, in Hz. Therefore, according to the formula combination, we can get

[0089] Therefore, by adjusting f 1 and f 2 The difference can change the characteristics of the envelope frequency and optimize the transmission depth and effect.

[0090] Therefore, the ultrasonic parameters in this embodiment are the frequencies of two ultrasonic waves of different frequencies. By accurately adjusting the two different ultrasonic frequencies, the combined ultrasonic-induced shock waves can achieve full coverage and synchronous impact forging of the cladding layer in the easy plastic deformation temperature region.

[0091] Among them, the influence depth of interlayer hammer aging treatment H C The following conditions must be met:

[0092] H C >H S >H R ;

[0093] In the formula, H C H is the depth of influence of interlayer peening treatment, that is, the depth of work hardening caused by peening treatment, R H is the remelting depth, that is, the depth of the remelting of the surface of the previous laser cladding layer when the new layer is laser cladding. S is the thickness of the plastic deformation layer.

[0094] In actual ultrasonic transmission, combined ultrasound is used to enhance the ultrasonic penetration depth and action area, where the influence depth H of ultrasonic energy field-assisted aging treatment is U The following conditions need to be met:

[0095] H U有效 >H D ×n;

[0096] In the formula, the influence depth of ultrasonic energy field assisted aging treatment is H U有效 , H D is the thickness of the single-layer cladding layer measured in step 3, n is the number of layers of the preset number of laser cladding layers, n=1, 2, 3... and n is an integer.

[0097] It should be understood that the effective grain refinement depth depends not only on the propagation depth of the ultrasonic wave, but also on the following factors: the power density of the ultrasonic wave (W / cm 2), material absorption coefficient, and threshold power density. Among them, the higher the power density of the ultrasound, the stronger the shock wave energy and the greater the depth of grain refinement. Each material has a different absorption coefficient for ultrasound, resulting in different energy attenuation with depth. Actual grain refinement requires an ultrasound power density higher than the threshold power density of the material.

[0098] Among them, the effective grain refinement depth can be calculated by the energy attenuation formula:

[0099]

[0100] In the formula, H U有效 represents the effective depth of grain refinement (unit: m), a represents the material absorption coefficient (unit: dB / m), w 0 Indicates the initial power density (unit: W / cm 2 ), Wthreshold represents the threshold power density of grain refinement (unit: W / cm 2 ).

[0101] In this embodiment, the number of the ultrasonic wave source is one or more.

[0102] Specifically, the number of ultrasonic sources is 1-7.

[0103] In this embodiment, the frequency of each ultrasonic wave in the combined ultrasonic wave is within the range of 18-35 KHz.

[0104] In this embodiment, the speed of ultrasonic hammer forging is 20-40 m / h, and the working current is 0.5-2.0A.

[0105] In this embodiment, the laser cladding layer is prepared on the molded substrate or the component to be repaired by using a preset laser cladding process, and further includes:

[0106] According to the damage area and depth of the damaged area of ​​the model of the part to be formed or the part to be repaired, the number of printing layers of the part to be formed or the part to be repaired and the thickness of each printing layer are obtained to facilitate layer-by-layer printing.

[0107] Second, as Figure 2 As shown, the present invention proposes an interlayer hammering ultrasonic in-situ assisted composite additive manufacturing method and device, comprising: a laser cladding mechanism, a powder feeding mechanism, a cladding workshop, a thickness measuring mechanism, a heat source nozzle, a three-dimensional moving mechanism, an ultrasonic hammering mechanism and a control mechanism;

[0108] The workbench is arranged horizontally in the cladding workshop; the powder feeding mechanism is used to lay metal powder on the molding substrate or the parts to be repaired fixed on the processing platform;

[0109] The three-dimensional moving mechanism is located in the cladding workshop on one side of the workbench; the ultrasonic hammer head of the ultrasonic hammering mechanism and the heat source nozzle of the laser cladding mechanism are both installed on the moving end of the three-dimensional moving mechanism, and the three-dimensional moving mechanism is used to drive the heat source nozzle and the ultrasonic hammer head to move;

[0110] The laser cladding control mechanism is used to perform laser cladding on the metal powder located on the formed substrate or the part to be repaired through the heat source nozzle; the thickness measuring mechanism is used to measure the thickness; the ultrasonic hammering mechanism is used to simultaneously achieve interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment through the ultrasonic wave output by the ultrasonic hammer head;

[0111] The powder feeding mechanism, thickness measuring mechanism, three-dimensional moving mechanism, laser cladding mechanism and ultrasonic hammering mechanism are all electrically connected to the control mechanism, and the control mechanism is used to control the powder feeding mechanism, three-dimensional moving mechanism, thickness measuring mechanism, laser cladding mechanism and ultrasonic hammering mechanism to coordinate their actions to achieve layer-by-layer printing and forming of the parts to be formed or layer-by-layer printing and repair of the parts to be repaired.

[0112] Wherein, during the printing process, the control mechanism controls the powder feeding mechanism, the three-dimensional moving mechanism and the laser cladding mechanism to cooperate to perform laser cladding on the formed substrate or the component to be repaired to form a laser cladding layer;

[0113] After each preset number of laser cladding layers are newly formed, the control mechanism controls the thickness measuring mechanism to obtain and store the thickness of the preset number of laser cladding layers;

[0114] The control mechanism adjusts the ultrasonic parameters according to the thickness of the preset number of laser cladding layers;

[0115] The control mechanism controls the three-dimensional moving mechanism and the ultrasonic hammering mechanism to cooperate so that the ultrasonic hammer head can simultaneously perform interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment on the preset number of laser cladding layers according to the adjusted ultrasonic parameters.

[0116] The control mechanism is used to obtain the number of printing layers of the part to be formed or the part to be repaired and the thickness of each printing layer according to the damaged area and depth of the damaged area of ​​the model of the part to be formed or the part to be repaired, before controlling the powder feeding mechanism, the three-dimensional moving mechanism, the thickness measuring mechanism, the laser cladding mechanism and the ultrasonic hammering mechanism to coordinate the actions to realize the layer-by-layer printing and forming of the part to be formed or the layer-by-layer printing and repair of the part to be repaired;

[0117] According to the number of printing layers of the part to be formed or repaired and the thickness of each printing layer, the number of times that ultrasonic waves are used to simultaneously realize interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment during the entire printing process and the number of newly formed laser cladding layers before each simultaneous use of ultrasonic waves to realize interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment are determined.

[0118] The control mechanism controls the three-dimensional moving mechanism and the laser cladding mechanism to cooperate so that the heat source nozzle performs laser cladding on the metal powder, specifically including:

[0119] The control mechanism controls the three-dimensional moving mechanism to drive the heat source nozzle to move in a preset moving direction, and at the same time controls the laser cladding mechanism to enable the heat source nozzle to perform laser cladding.

[0120] The control mechanism controls the three-dimensional moving mechanism and the ultrasonic hammering mechanism to cooperate so that the ultrasonic hammer head performs ultrasonic hammering on the laser cladding layer according to the adjusted ultrasonic parameters, specifically including:

[0121] The control mechanism controls the three-dimensional moving mechanism to drive the ultrasonic hammer to move in a preset moving direction, and at the same time controls the ultrasonic hammer mechanism so that the ultrasonic hammer performs ultrasonic hammering on the laser cladding layer according to the adjusted ultrasonic parameters.

[0122] In this embodiment, an infrared thermal imager is also included, and the infrared thermal imager is electrically connected to the control mechanism.

[0123] Specifically, after obtaining the thickness of the preset number of laser cladding layers, the control mechanism is also used to control the infrared thermal imager to obtain the temperature of the preset number of laser cladding layers;

[0124] When the temperature of the preset number of laser cladding layers is in the preset optimal plastic forming temperature range, the ultrasonic wave is controlled according to the adjusted ultrasonic parameters to simultaneously achieve interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment on the preset number of laser cladding layers.

[0125] In this embodiment, the three-dimensional moving mechanism includes two first moving rails, two sliders, a second moving rail, two first driving assemblies, a second driving assembly, a third driving assembly and a fourth driving assembly;

[0126] Two first movable guide rails are symmetrically fixed on two opposite side walls of the cladding workshop, and each first movable guide rail is arranged vertically;

[0127] The two sliders are respectively slidably arranged on the two first movable guide rails in the vertical direction; the two first driving assemblies are respectively drivingly connected to the two sliders, and the first driving assemblies are used to drive the corresponding sliders to slide vertically along the first movable guide rails;

[0128] Each first sliding block is provided with a sliding groove arranged along its length direction.

[0129] The second movable guide rail is horizontally arranged between the two first sliders, and the two ends of the second movable guide rail slide in the slide grooves of the two sliders respectively. The second driving component is drivingly connected to the second movable guide rail, and the second driving component is used to drive the second guide rail to slide along the length direction of the slider;

[0130] The heat source nozzle and the ultrasonic hammer are both slidably connected to the second movable guide rail, the third driving assembly is drivably connected to the heat source nozzle, and the third driving assembly is used to drive the heat source nozzle to slide along the second movable guide rail, and the fourth driving assembly is drivably connected to the ultrasonic hammer, and the fourth driving assembly is used to drive the ultrasonic hammer to slide along the second movable guide rail;

[0131] The first drive assembly, the second drive assembly, the third drive assembly and the fourth drive assembly are all electrically connected to the control mechanism.

[0132] Specifically, the thickness measuring mechanism includes a micrometer, and the thickness of the laser cladding layer is measured by the micrometer.

[0133] In this embodiment, the number of the ultrasonic hammering devices is one or more.

[0134] Specifically, the number of the ultrasonic hammer heads is 1-7, and the diameter of the ultrasonic hammer heads is 2-5 mm.

[0135] In this embodiment, the frequency of each ultrasonic wave in the combined ultrasonic wave is within the range of 18-35 KHz.

[0136] In this embodiment, the speed of ultrasonic hammer forging is 20-40 m / h, and the working current is 0.5-2.0A.

[0137] In this embodiment, a water cooling plate is provided on the workbench, and the water cooling plate is connected to a water cooling box through a delivery pipe, and the water cooling box is installed outside the cladding workshop.

[0138] The present invention will be described below with reference to specific embodiments.

[0139] Example 1

[0140] The interlayer hammering ultrasonic in-situ assisted composite additive manufacturing method and device proposed in the present invention are used to carry out composite manufacturing of 17-4PH.

[0141] Among them, the laser power of the laser cladding mechanism is P=2000w, the moving speed of the heat source nozzle is 0.015m / s, the powder feeding rate of the powder feeding mechanism is 1.2r / min, and argon is used as the protective gas. After drying, the 17-4PH powder is placed in the powder feeding mechanism for laser deposition additive manufacturing. The number of ultrasonic hammer heads is 1.

[0142] Wherein, during the printing process, the control mechanism controls the powder feeding mechanism, the three-dimensional moving mechanism and the laser cladding mechanism to cooperate to perform laser cladding on the formed substrate or the component to be repaired to form a laser cladding layer;

[0143] After each preset number of laser cladding layers are newly formed, the control mechanism controls the thickness measuring mechanism to obtain and store the thickness of the laser cladding layers;

[0144] Next, the control mechanism adjusts the ultrasonic parameters according to the thickness of the preset number of laser cladding layers;

[0145] After the preset number of laser cladding layers are formed, the control mechanism controls the infrared thermal imager to obtain the temperature of the preset number of laser cladding layers;

[0146] When the preset number of laser cladding layers are in the preset optimal plastic forming temperature range, the control mechanism controls the three-dimensional moving mechanism and the ultrasonic hammering mechanism to cooperate so that the ultrasonic hammer head can simultaneously perform interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment on the preset number of laser cladding layers according to the adjusted ultrasonic parameters.

[0147] The control mechanism is used to obtain the number of printing layers of the part to be formed or the part to be repaired and the thickness of each printing layer according to the damaged area and depth of the damaged area of ​​the model of the part to be formed or the part to be repaired, before controlling the powder feeding mechanism, the three-dimensional moving mechanism, the thickness measuring mechanism, the laser cladding mechanism and the ultrasonic hammering mechanism to coordinate the actions to realize the layer-by-layer printing and forming of the part to be formed or the layer-by-layer printing and repair of the part to be repaired;

[0148] According to the number of printing layers of the part to be formed or repaired and the thickness of each printing layer, the number of times that ultrasonic waves are used to simultaneously implement interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment during the entire printing process and the number of newly formed laser cladding layers before each simultaneous use of ultrasonic waves to implement interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment are determined. The number of layers here is the preset number of laser cladding layers n.

[0149] like Figure 3 As shown, the heat source nozzle scans and melts the metal powder sent out to form a laser cladding layer, and the temperature field of the laser cladding layer is monitored online in real time by an infrared thermal imager.

[0150] When the new preset number of laser cladding layers is completed and its temperature field is in the optimal plastic forming temperature range, the ultrasonic hammer mechanism is adjusted by current and resonance to form two different ultrasonic frequencies, so that the ultrasonic hammer head can achieve full coverage and synchronous impact forging of the laser cladding layer in the easy plastic deformation temperature zone. At the same time, the GPa-level shock wave induced by the combined ultrasonic wave can produce a mechanical effect, thereby improving the metal microstructure and forming refined metal grains.

[0151] In this embodiment, when n=3, H D=1.37mm, the two best ultrasonic process parameters are: the first ultrasonic wave, the ultrasonic control box working current of this ultrasonic wave is 1.0A, the frequency f 1 =25KHZ; the second ultrasonic wave, the ultrasonic control box of this ultrasonic wave has an operating current of 1.6A and a frequency of f 2 =30KHZ. The combined ultrasonic wave containing these two ultrasonic waves has an influence depth of H U The preset laser cladding layer depth material can be fully forged and thoroughly forged. The ultrasonic hammer head moves along the set track in a single track under the control of the three-dimensional moving mechanism, and acts on the top of the laser cladding layer in the form of pulses. The distance from the ultrasonic hammer head to the surface of the laser cladding layer is 10 mm, the moving speed of the ultrasonic hammer head is 20 m / h, and two hammer strikes are performed. The hardness of the third layer of laser cladding layer is measured and observed by a hardness tester and an optical microscope. s =1.21mm, H R =0.79mm.

[0152] like Figure 3 As shown, during the entire printing process, the formation of the laser cladding layer and the simultaneous interlayer hammering aging treatment using ultrasound and the ultrasonic energy field assisted aging treatment are repeated alternately several times to finally complete the manufacturing of the part to be formed.

[0153] Among them, the thickness of the part to be formed is t = 13.77 mm, the average layer thickness HA = 1.25 mm, and H D >H A >H S >H R Among them, the parameter values ​​are: n = 3, f 1 =25KHZ, f 2 =30KHZ, t=13.77mm, H D =1.37mm,H A =1.25mm, C=5200m / s, a=100dB / m, W 0 =12W / cm 2 , Wthreshold=10W / cm 2 , thus we can calculate H U有效 =15.8mm>H D *n, the grains partially recrystallize. The effective depth of ultrasonic-induced shock waves for grain refinement usually depends on the above factors. When the shock intensity is high (such as power density>10W / cm 2 ), the depth may increase further, but the grain refinement effect gradually weakens with depth.

[0154] Finally, the parts to be formed are surface treated by grinding or polishing to ensure that their surface quality meets the design requirements.

[0155] In this embodiment, the microstructure of the solid body of the part to be formed is tested, and the test results are as follows: Figure 4 As shown. Figure 4 It can be seen that the interlayer hammering ultrasonic in-situ assisted technology proposed in the present invention promotes the uneven nucleation of β grains at the bottom of the molten pool below the heat source nozzle. Due to the heat dissipation effect of the water-cooled plate in the processing platform, the heat loss is high, resulting in a high temperature gradient. The microstructure of the single laser cladding layer along the additive manufacturing direction is uneven, consisting of epitaxial growth grains close to the substrate and small equiaxed grains close to the top surface. Among them, the formation of small equiaxed grains involves two factors. One is the heterogeneous nucleation on the surface of the molten pool. During the laser cladding forming process, equiaxed grains are generated based on heterogeneous nucleation sites of incompletely molten powder or some high-melting point particles; the other is the transformation from columnar to equiaxed.

[0156] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An interlayer hammering ultrasonic in-situ assisted composite additive manufacturing method, characterized in that: include: Fix the formed substrate or the parts to be repaired on the processing platform; Using a preset laser cladding process to prepare a laser cladding layer on the formed substrate or the component to be repaired; wherein after each preset number of laser cladding layers are newly formed, the thickness of the preset number of laser cladding layers is obtained; According to the thickness of the preset number of laser cladding layers, adjusting the parameters of the ultrasonic wave; wherein the ultrasonic wave is a combined ultrasonic wave formed by two ultrasonic waves of different frequencies; According to the adjusted ultrasonic parameters, the ultrasonic wave is controlled to simultaneously realize interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment for the preset number of laser cladding layers.

2. The interlayer hammering ultrasonic in-situ assisted composite additive manufacturing method according to claim 1 is characterized in that: According to the adjusted ultrasonic parameters, the ultrasonic wave is controlled to simultaneously perform interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment on the preset number of laser cladding layers, specifically including: Obtaining the temperature of the preset number of laser cladding layers; When the temperature of the preset number of laser cladding layers is in the preset optimal plastic forming temperature range, the ultrasonic wave is controlled according to the adjusted ultrasonic parameters to simultaneously achieve interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment on the preset number of laser cladding layers.

3. The interlayer hammering ultrasonic in-situ assisted composite additive manufacturing method according to claim 1 is characterized in that: Before using a preset laser cladding process to prepare a laser cladding layer on a molded substrate or a component to be repaired, it also includes: According to the damage area and depth of the damaged area of ​​the model of the part to be formed or the part to be repaired, the number of printing layers of the part to be formed or the part to be repaired and the thickness of each printing layer are obtained; According to the number of printing layers of the part to be formed or repaired and the thickness of each printing layer, the number of times that ultrasonic waves are used to simultaneously realize interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment during the entire printing process and the number of newly formed laser cladding layers before each simultaneous use of ultrasonic waves to realize interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment are determined.

4. The interlayer hammering ultrasonic in-situ assisted composite additive manufacturing method according to claim 1 is characterized in that: The frequency of each ultrasonic wave in the combined ultrasonic wave is within the range of 18-35 KHz.

5. The interlayer hammering ultrasonic in-situ assisted composite additive manufacturing method according to claim 1 is characterized in that: The influence depth of ultrasonic energy field assisted aging treatment H U The following conditions need to be met: H U有效 >H D ×n; In the formula, H U有效 It represents the influence depth of ultrasonic energy field assisted aging treatment, H D is the thickness of a single laser cladding layer, n is the number of layers of the preset number of laser cladding layers, and n is a positive integer; in, In the formula, H U有效 represents the effective depth of grain refinement, a represents the material absorption coefficient, w0 represents the initial power density, and Wthreshold represents the threshold power density of grain refinement; The influence depth of interlayer hammer aging treatment H C The following conditions must be met: H C >H S >H R ; In the formula, H C H is the depth of influence of interlayer peening treatment, that is, the depth of work hardening caused by peening; R H is the remelting depth, that is, the depth of the remelting of the surface of the previous laser cladding layer when the new layer is laser cladding; S is the thickness of the plastic deformation layer.

6. An interlayer hammering ultrasonic in-situ assisted composite additive manufacturing device, characterized in that: include: Laser cladding mechanism, powder feeding mechanism, cladding workshop, thickness measuring mechanism, heat source nozzle, three-dimensional moving mechanism, ultrasonic hammering mechanism and control mechanism; The workbench is arranged horizontally in the cladding workshop; the powder feeding mechanism is used to lay metal powder on the molding substrate or the parts to be repaired fixed on the processing platform; The three-dimensional moving mechanism is located in the cladding workshop on one side of the workbench; the ultrasonic hammer head of the ultrasonic hammering mechanism and the heat source nozzle of the laser cladding mechanism are both installed on the moving end of the three-dimensional moving mechanism, and the three-dimensional moving mechanism is used to drive the heat source nozzle and the ultrasonic hammer head to move; The laser cladding control mechanism is used to perform laser cladding on the metal powder located on the formed substrate or the part to be repaired through the heat source nozzle; the thickness measuring mechanism is used to measure the thickness; the ultrasonic hammering mechanism is used to simultaneously realize the interlayer hammering aging treatment and the ultrasonic energy field assisted aging treatment through the ultrasonic wave output by the ultrasonic hammer head; wherein the ultrasonic wave is a combined ultrasonic wave formed by two ultrasonic waves of different frequencies; The powder feeding mechanism, thickness measuring mechanism, three-dimensional moving mechanism, laser cladding mechanism and ultrasonic hammering mechanism are all electrically connected to the control mechanism, and the control mechanism is used to control the powder feeding mechanism, three-dimensional moving mechanism, thickness measuring mechanism, laser cladding mechanism and ultrasonic hammering mechanism to coordinate their actions to achieve layer-by-layer printing and forming of the parts to be formed or layer-by-layer printing and repair of the parts to be repaired.

7. The interlayer hammering ultrasonic in-situ assisted composite additive manufacturing device according to claim 6 is characterized in that: During the printing process, the control mechanism controls the powder feeding mechanism, the three-dimensional moving mechanism and the laser cladding mechanism to cooperate to perform laser cladding on the formed substrate or the component to be repaired to form a laser cladding layer; Wherein, after each preset number of laser cladding layers are newly formed, the control mechanism controls the thickness measuring mechanism to obtain the thickness of the preset number of laser cladding layers; The control mechanism adjusts the ultrasonic parameters according to the thickness of the preset number of laser cladding layers; The control mechanism controls the three-dimensional moving mechanism and the ultrasonic hammering mechanism to cooperate so that the ultrasonic hammer head can simultaneously perform interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment on the preset number of laser cladding layers according to the adjusted ultrasonic parameters.

8. The interlayer hammering ultrasonic in-situ assisted composite additive manufacturing device according to claim 7 is characterized in that: It also includes an infrared thermal imager, which is electrically connected to the control mechanism; The control mechanism is also used to control the infrared thermal imager to take the temperature of the preset number of laser cladding layers; when the temperature of the preset number of laser cladding layers is in a preset optimal plastic forming temperature range, the ultrasonic wave is controlled according to the adjusted ultrasonic parameters to simultaneously achieve interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment for the preset number of laser cladding layers.

9. The interlayer hammering ultrasonic in-situ assisted composite additive manufacturing device according to claim 5 is characterized in that: The control mechanism is used to obtain the number of printing layers of the part to be formed or the part to be repaired and the thickness of each printing layer according to the damaged area and depth of the damaged area of ​​the model of the part to be formed or the part to be repaired, before controlling the powder feeding mechanism, the three-dimensional moving mechanism, the thickness measuring mechanism, the laser cladding mechanism and the ultrasonic hammering mechanism to coordinate the actions to realize the layer-by-layer printing and forming of the part to be formed or the layer-by-layer printing and repair of the part to be repaired; According to the number of printing layers of the part to be formed or repaired and the thickness of each printing layer, the number of times that ultrasonic waves are used to simultaneously realize interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment during the entire printing process and the number of newly formed laser cladding layers before each simultaneous use of ultrasonic waves to realize interlayer hammering aging treatment and ultrasonic energy field assisted aging treatment are determined.

10. The interlayer hammering ultrasonic in-situ assisted composite additive manufacturing method according to claim 6, characterized in that: The influence depth of ultrasonic energy field assisted aging treatment needs to meet the following conditions: H U有效 >H D ×n; In the formula, H U有效 It represents the influence depth of ultrasonic energy field assisted aging treatment, H D is the thickness of a single laser cladding layer, n is the number of layers of the preset number of laser cladding layers, and n is a positive integer; in, In the formula, H U有效 represents the effective depth of grain refinement, a represents the material absorption coefficient, w0 represents the initial power density, and Wthreshold represents the threshold power density of grain refinement; The depth of influence of interlayer hammer aging treatment must meet the following conditions: H C >H S >H R ; In the formula, H C H is the depth of influence of interlayer peening treatment, that is, the depth of work hardening caused by peening; R H is the remelting depth, that is, the depth of the remelting of the surface of the previous laser cladding layer when the new layer is laser cladding; S is the thickness of the plastic deformation layer.

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