Laser fuse additive manufacturing forming control method

Abstract

The invention discloses a laser fuse additive manufacturing forming control method, which relates to the technical field of metal additive manufacturing, and comprises the following steps: carrying out layering and channel separation treatment on a three-dimensional model of a part to generate a multi-channel and multi-layer deposition path; selecting the size of a single-channel deposition layer and steady-state process parameters corresponding to the size of the single-channel deposition layer under a steady-state condition according to the thickness of the sub-layer and the width of the sub-channel, and selecting corresponding laser power according to the local heat dissipation volume of a deposition point when laser moves along a deposition path so as to ensure that the power for forming a molten pool is not changed; and generating process parameters corresponding to the change of the deposition path and the change of the local heat dissipation volume of the deposition point, and carrying out additive manufacturing on the part channel by channel and layer by layer to finally obtain the laser fuse additive manufacturing part. The method is high in real-time performance, simple, reliable and capable of actively controlling the size of the single deposition layer in advance, it is guaranteed that the size of each deposition layer is kept stable, and therefore it is guaranteed that the forming size of the part meets the requirement.

Description

Technical Field

[0001] The present invention relates to the technical field of metal additive manufacturing, and in particular to a laser fuse additive manufacturing forming control method. Background Art

[0002] Laser directed energy deposition technology has the advantages of simple process, high forming accuracy, and the ability to manufacture large continuous parts. It is widely used in aerospace, automobile, shipbuilding, biomedicine and other fields. This technology can be divided into two additive manufacturing technologies: laser powder melting and laser fuse according to the deposition material. Laser fuse additive manufacturing has the advantages of low cost, fast deposition speed, easy material storage and high utilization rate; however, the forming control technology for laser fuse additive manufacturing has not yet been perfected, and the forming accuracy is difficult to effectively guarantee, so its promotion and application are limited.

[0003] Laser fuse additive manufacturing is a process in which a single deposition layer formed by laser melting a metal wire is overlapped one by one to form a layer of deposition layer, and then layer by layer is stacked to form a part of the desired shape. Therefore, the shape and size of each deposition layer directly affects the forming accuracy of the entire part.

[0004] In the prior art, when the online real-time automatic control of the melt width is adopted, the laser will have a great impact on the measurement accuracy of the device for detecting the melt width of the molten pool (such as: optical cameras, infrared imagers, laser scanners and other optical devices); coupled with the fast scanning speed of laser fuse additive manufacturing, the melt pool fluctuates greatly, the image processing time is long, and the measurement and control system cannot meet the faster dynamic response, resulting in the fact that the automatic control technology of the melt width has not yet been perfected. If constant standard parameters (laser power, scanning speed, wire feeding speed, etc.) are used for additive manufacturing, the melt width of the molten pool at the deposition point will change due to the different heat dissipation capabilities of the deposition points at different positions, and the stability of the deposition layer width cannot be ensured. For example: at the edges and corners, due to the small heat dissipation volume of the base metal below the molten pool, the molten pool will overheat and become larger in size, and even the molten pool will collapse.

[0005] Therefore, how to effectively realize the forming control of laser fuse additive manufacturing is a key issue currently faced. Summary of the invention

[0006] In view of the defects of the prior art, the purpose of the present invention is to provide a laser fuse additive manufacturing forming control method, which adjusts the laser power according to the heat dissipation capacity of the deposition point, controls the power of forming a molten pool to be constant to ensure the size of the molten pool, and achieves the stability of the size of a single deposition layer, thereby ensuring the forming accuracy of additively manufactured parts layer by layer.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A laser fuse additive manufacturing forming control method comprises the following steps: (1) Establish a three-dimensional model of the part, perform layering and lane processing on the model, and generate multi-channel and multi-layer deposition paths; (2) selecting the size of a single-channel deposition layer and the steady-state process parameters corresponding to the size of the single-channel deposition layer under steady-state conditions according to the layer thickness and the channel width of the divided channels; (3) Under the premise of ensuring that the power for forming the molten pool remains unchanged, the corresponding laser power is calculated and selected according to the local heat dissipation volume of the deposition point when the laser moves along the deposition path, and the process parameters corresponding to the changes in the deposition path and the local heat dissipation volume of the deposition point are generated; (4) According to the deposition path generated in step (3) and its corresponding process parameters, additive manufacturing of the part is performed layer by layer, and finally a laser fuse additively manufactured part is obtained.

[0009] Furthermore, the steady state described in step (2) refers to: when a laser fuse single-pass deposition test is carried out in the middle of a flat plate having a size of not less than 150 mm × 75 mm × 30 mm at room temperature, in the middle stage of the deposition process, the molten pool temperature field is in a relatively stable stage and the molten pool size is also in a stable state.

[0010] Furthermore, in step (2), the dimensions of the single-channel deposition layer include height, width and cross-sectional area.

[0011] Furthermore, in step (2), the steady-state process parameters of the single-channel deposition layer refer to the parameters under which a stable deposition process and a stable deposition layer size can be obtained. The cross-sectional profile of the single-channel deposition layer is close to an arc shape, and its height is equal to the layer thickness of the layer. Its cross-sectional area is equal to the layer thickness of the layer multiplied by the track width of the layer. The height of the deposition layer obtained by overlapping the single-channel deposition layer with the track width as the spacing is equal to the layer thickness of the layer. The size of the single-channel deposition layer is the size of the single-channel deposition layer under steady-state conditions selected based on the layer thickness of the layer and the track width.

[0012] Furthermore, the steady-state process parameters include at least: wire diameter, wire feeding speed, scanning speed, laser power, fiber laser wavelength, spot diameter, argon flow rate, wire feeding angle, wire feeding method, wire material, matrix material and interlayer temperature. The values ​​of the steady-state process parameters are determined through process tests and parameter optimization.

[0013] Furthermore, in step (3), based on the multi-channel and multi-layer deposition paths generated in step (1), the local heat dissipation volume of the deposition point position is calculated point by point, and then the laser power to be selected at the position is calculated based on the local heat dissipation volume. In this way, the calculation is performed channel by channel and layer by layer to generate a laser power that changes accordingly with the deposition path. Other parameters are steady-state parameters that remain unchanged, thereby generating a deposition path and its corresponding process parameters.

[0014] Furthermore, on the deposition path, when calculating the local heat dissipation volume of the deposition point position point by point, the interval between each point is in the range of 2-5 mm.

[0015] Furthermore, the local heat dissipation volume V at the deposition point x , refers to the area falling on r W is the volume of the base metal within a spherical region of radius r, the base metal including the plate and the deposited layers, W is the local heat dissipation radius in steady state, that is, the temperature from the center of the molten pool to the plate in steady state is T C The distance at C The interlayer temperature that needs to be maintained for multi-layer cladding.

[0016] Furthermore, according to the local heat dissipation volume V of the deposition point x The specific method for calculating laser power is: P Jx =P JW -C(V W -V x ); Among them, P Jx is the laser power corresponding to the deposition point x, P JW is the laser power in steady state, C is a constant, V W is the local heat dissipation volume in steady state, V x is the local heat dissipation volume at the deposition point, P JW 、V W The values ​​of and C are obtained through process experiments and parameter optimization.

[0017] The laser fuse additive manufacturing forming control method according to claim 9 is characterized in that the local heat dissipation volume in steady state where r W is the local heat dissipation radius in steady state, that is, the temperature from the center of the molten pool to the flat plate is the interlayer temperature T C The distance between the

[0018] Beneficial effects:

[0019] (1) The present invention aims to solve the problem that during constant specification parameter additive manufacturing, deposition points at different positions may cause the size of the molten pool to change due to different heat dissipation capabilities. In combination with the characteristic that laser fuse additive manufacturing is formed by successive accumulation of multiple layers and multiple deposition layers, the present invention proposes for the first time a scheme for adjusting the laser power according to the local heat dissipation capability of the deposition point to achieve a constant molten pool power. The power for forming the molten pool at this position is kept consistent with the power for forming a steady-state molten pool, thereby keeping the size of each deposition layer stable. By controlling the stability of the size of a single deposition layer, it is finally ensured that the forming size of the laser wire additively manufactured part meets the design requirements.

[0020] (2) The present invention reflects the local heat dissipation capacity at the deposition point through the local heat dissipation volume, and defines a calculation method for the local heat dissipation volume, thereby reflecting the local heat dissipation capacity at different positions.

[0021] (3) The method for controlling the size of a single-track deposition layer of the present invention is simple and reliable. By analyzing the relationship between power and heat conversion in the laser fuse forming process, a calculation formula between the local heat dissipation volume at the deposition point and the laser power is established. According to the local heat dissipation volume at the deposition point during the deposition process, the laser power to be selected at the position can be conveniently calculated based on the calculation formula, thereby realizing the control of the size of a single-track deposition layer at different positions.

[0022] (4) The control method of the single-pass deposition layer size adopted in the present invention is pre-active control. Before the laser fuse automatic deposition device performs additive manufacturing, the corresponding laser power is predicted, calculated and selected in advance based on the local heat dissipation volume of the deposition point. During additive manufacturing, the control of the molten pool width is highly real-time and there is no lag.

[0023] (5) The size (height and width) of a single-pass deposition layer under steady-state conditions and the steady-state process parameters corresponding to the size of the single-pass deposition layer selected by the present invention are obtained through a large number of process tests and parameter optimizations, which can ensure a stable deposition process and a stable deposition layer size, thereby ensuring the forming size of the laser wire additively manufactured parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the working flow chart of the forming control method of the present invention.

[0025] Figure 2 The local heat dissipation radius r is measured when the laser fuse single-pass deposition test is carried out using the selected steady-state process parameters under steady-state conditions. W and local heat dissipation volume V W Schematic diagram of the method.

[0026] Figure 3 When the deposition point is at the edge, r W The local heat dissipation volume V of the base metal in the spherical area with a radius L Schematic diagram of .

[0027] Figure 4 This is a three-dimensional image of a circular ring part in Example 1.

[0028] Figure 5 It is a three-dimensional diagram of the predicted formation of the ring part after layering and lane division, which is formed by depositing layer by layer according to the size of the single-pass deposition layer and the generated deposition path under the selected steady-state condition.

[0029] Figure 6When the deposition point is in the second layer, r W The local heat dissipation volume V of the base metal in the spherical area with a radius 2 Schematic diagram of .

[0030] Figure 7 When the deposition point is at the third layer, r W The local heat dissipation volume V of the base metal in the spherical area with a radius 3 Schematic diagram of .

[0031] Figure 8 When the deposition point is at the 9th layer, the W The local heat dissipation volume V of the base metal in the spherical area with a radius 9 Schematic diagram of .

[0032] Markings in the figure: 1, substrate, 2, molten pool, 3, deposited layer, 4, thermocouple. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] In the laser fuse additive manufacturing process, the laser interacts with the metal wire, base metal, molten pool and plasma cloud. Part of the laser energy is converted into heat energy and absorbed by the metal wire, molten pool and base metal. Part of this heat energy is used to melt the metal wire and base metal to form a molten pool, and the other part of the heat energy is dissipated by conduction, convection, radiation, etc. (referred to as heat dissipation energy Q S The heat energy absorbed by the wire and the base metal (Q X ), the heat energy of the molten metal wire and the base metal to form a molten pool (abbreviated as Q R ) and heat dissipation energy Q S The following relationship exists:

[0035] Q X = Q R + Q S (Formula 1)

[0036] Q R = Q X -Q S (Formula 2)

[0037] Dividing both ends of formula (2) by time t, it is converted into the power P absorbed by the wire and the base metal. X , the power P of the melted wire and base metal to form a molten pool R And the heat dissipation power P S The relationship between:

[0038] P R =P X -PS (Formula 3)

[0039] The power P of the melted wire and base metal to form a molten pool R Directly determines the size and dimensions of the molten pool. When the process parameters such as wire feeding method, wire feeding angle and wire feeding speed, laser scanning speed, wire diameter, and base material remain unchanged, the cross-sectional area S of a single-pass deposition layer remains unchanged, and P R The larger the value, the larger the molten pool width, and the corresponding single-channel deposition layer width is larger and the height is smaller; P R The smaller the value, the smaller the molten pool width, and the smaller the width and the greater the height of the corresponding single-pass deposition layer. R By keeping it constant, the molten pool width can be controlled to remain constant during the additive manufacturing process, which can ensure the stability of the width of a single deposition layer, thereby ensuring the stability of the forming dimensions of the additively manufactured parts layer by layer.

[0040] When laser fuse additive manufacturing is performed with constant specification parameters, the power P absorbed by the wire and the base metal is X remains unchanged; as the position of the deposition point changes, the heat dissipation capacity of the molten pool at that position also changes (such as the edge and corner position), resulting in the heat dissipation power P S will also change, which will lead to P R Therefore, as the position of the deposition point changes during the additive manufacturing process, its heat dissipation capacity changes, resulting in changes in P S When the laser power changes, P X The value of P R By keeping it unchanged, the stability of the molten pool size can be ensured, ensuring the forming accuracy of the additively manufactured parts.

[0041] Based on the influence of the local heat dissipation capacity at the deposition point on the molten pool power, the present invention proposes a laser fuse additive manufacturing forming control method, which selects the corresponding laser power according to the local heat dissipation volume of the deposition point to ensure that the power of forming the molten pool remains unchanged, such as Figure 1 As shown, the method is mainly implemented by the following steps:

[0042] (1) Establish a three-dimensional model of the part, and perform layering and lane processing on the model according to the characteristics and process requirements of laser fuse additive manufacturing to generate multi-channel and multi-layer deposition paths.

[0043] (2) According to the layer thickness and the lane width of the layers, the size (height and width) of the single-channel deposition layer under steady-state conditions and the steady-state process parameters corresponding to the size of the single-channel deposition layer are selected.

[0044] (3) In order to control the stability of the molten pool width, the corresponding laser power is selected according to the local heat dissipation volume of the deposition point when the laser moves along the deposition path during the deposition process to ensure that the power for forming the molten pool remains unchanged, and the process parameters corresponding to the changes in the deposition path and the local heat dissipation volume of the deposition point are generated.

[0045] (4) According to the deposition path generated in step (3) and its corresponding process parameters, additive manufacturing of the part is performed layer by layer, and finally a laser fuse additively manufactured part is obtained.

[0046] In the present invention, the steady state means that when a laser fuse single-pass deposition test is carried out in the middle of a flat plate with a size of not less than 150mm×75mm×30mm at room temperature, in the middle stage of the deposition process, the molten pool temperature field is in a relatively stable stage and the molten pool size is also stable.

[0047] The stable process parameters of the single-channel deposition layer under the steady state condition are obtained through a large number of process tests and parameter optimization. Under the parameters, a stable deposition process and a stable deposition layer size can be obtained. The cross-sectional profile of the single-channel deposition layer is close to an arc shape, and its height is equal to the layer thickness of the layer, and its cross-sectional area is equal to the layer thickness of the layer multiplied by the width of the channel. The height of the deposition layer obtained by overlapping the single-channel deposition layer one by one with the channel width as the spacing is equal to the layer thickness of the layer. The size of the single-channel deposition layer is the size of the single-channel deposition layer under the steady state condition selected according to the layer thickness and the channel width. Under the steady state condition, through process tests and parameter optimization, the size of the single-channel deposition layer under the steady state condition selected according to the layer thickness and the channel width and the steady-state process parameters corresponding to the size of the single-channel deposition layer can be obtained.

[0048] The steady-state process parameters include: welding wire diameter, wire feeding speed, scanning speed, laser power, fiber laser wavelength, spot diameter, argon gas flow, wire feeding angle, wire feeding method, welding wire material, matrix material and interlayer temperature, etc.

[0049] The specific principle and process of the present invention for obtaining steady-state process parameters through process tests and parameter optimization, and selecting corresponding laser power according to the local heat dissipation volume of the deposition point are as follows.

[0050] When the process parameters such as wire feeding method, wire feeding angle and wire feeding speed, laser scanning speed, spot diameter, wire diameter, and base material in laser fuse additive manufacturing remain unchanged, the power P absorbed by the wire and base metal is X With laser power P J The proportional relationship between them is a fixed value, and the conversion absorption coefficient K is used 1 Represented. Then from formula (3), we can get formula 4:

[0051] P R = K 1 P J-P S (Formula 4)

[0052] Since the heat dissipation speed of metal is very fast, the energy of convection and radiation to the air can be ignored, and the heat dissipation power P S It is mainly the heat power conducted by the base metal in the form of heat conduction. The heat dissipation power P of the metal object is S The relationship between its thermal resistance R is:

[0053]

[0054] In formula 5, T 1 is the temperature at one end of the object, T 2 is the temperature at the other end of the object.

[0055] Due to the high scanning speed of laser fuse additive manufacturing, the temperature field around the molten pool at the deposition point is also changing. In the steady state, the local temperature field of the moving molten pool is in a relatively stable stage, and the local base metal area around the molten pool can be selected to calculate its local thermal resistance.

[0056] Laser fuse additive manufacturing is a continuous multi-pass multi-layer cladding process. The interlayer temperature T that needs to be maintained during multi-pass multi-layer cladding of the part metal is selected. C As T 1 , T 2 Choose the melting point temperature T of the metal R .like Figure 2 As shown, when a single-pass deposition test is performed using the selected steady-state process parameters under steady-state conditions, a temperature sensor (usually a thermocouple 4) is installed on the substrate 1 to measure the temperature from the center of the molten pool 2 to the substrate as T C The distance r W As the local heat dissipation radius in steady state, r W The local thermal resistance R of the base metal in the spherical area with a radius of W .

[0057] It should be noted that in laser wire feeding additive manufacturing, in the spherical area of ​​the local heat dissipation radius centered on the deposition point, there is no base metal in the upper half, which is the operating space for the laser head, welding wire and robotic arm, and the lower half is the base for additive manufacturing. Therefore, in the following calculations, the upper half of the spherical area is ignored, and only the hemispherical area of ​​the lower half is taken as the volume of heat conduction and the calculation of thermal resistance.

[0058] In a hemispherical object that dissipates heat around the molten pool, when its radius and heat conduction temperature difference remain unchanged, its thermal resistance R is proportional to its volume V, that is:

[0059]

[0060] Where K 2 It is a constant related to the thermal conductivity of the material, radius, temperature difference, etc.

[0061] According to formula (6), we can get:

[0062] Where V W is the steady state condition with r W The local heat dissipation volume of the base metal in the spherical region with a radius of , that is, the volume of the intersection of the spherical region and the substrate 1, as Figure 2 As shown, V W is a hemispherical volume.

[0063] Under steady-state conditions, when the optimal stable single-pass deposition layer process parameters are used for deposition, the steady-state laser power P JW , the power P required to form a steady-state molten pool RW And the heat dissipation power P SW The relationship between can be expressed as:

[0064] P RW =K 1 P JW -P SW (Formula 8)

[0065] Then, according to equations 5 and 7, the heat dissipation power P in steady state is SW It can be expressed as:

[0066]

[0067] Where, ΔT = T R -T C .

[0068] In the laser fuse additive manufacturing process, when the deposition point moves to a certain x position, the laser power P used is Jx , the power P to form the molten pool Rx And the heat dissipation power P Sx The relationship between can be expressed as:

[0069] P Rx = K 1 P Jx -P Sx (Formula 10)

[0070] Similar to the steady state case, at this position r W The local thermal resistance R of the base metal in the spherical area of ​​radius x , V x At this position, r Wis the local heat dissipation volume of the base metal in the spherical area of ​​radius, and the base metal includes the substrate 1 and the completed deposition layer 3. From formula (6), it can be seen that R x With V x The relationship between them is:

[0071]

[0072] Among them, Vx is included in r W The volume of the flat base metal and the deposited base metal in the spherical area with a radius of r can be added to the deposition point in the 3D software during actual calculation. W The volume of the hemisphere with a radius of φ is calculated by the intersection of the hemisphere with the flat substrate and the deposited base metal to obtain Vx.

[0073] Then the heat dissipation power P Sx It can be expressed as:

[0074]

[0075] In order to ensure that the molten pool width at the deposition point at position x is consistent with the molten pool width in the steady state, it is necessary to ensure that the power to form the molten pool is equal, that is: P RW =P Rx According to formulas (8), (9) and (10), (12), we can get formula (13):

[0076]

[0077] Where C is K 1 , K 2 A constant related to ΔT.

[0078] Through the above process tests and parameter optimization, the process parameters of the single-channel deposition layer corresponding to the single-channel deposition layer size selected by the layer thickness and the channel width can be obtained (called steady-state process parameters), and the corresponding P JW 、V W and r W The value of .

[0079] Furthermore, if Figure 3 As shown in the figure, a single-pass laser fuse deposition test is carried out at the edge position. The other process parameters are the same as the steady-state process parameters. Only the laser power value is adjusted to make the deposition layer size at the edge position consistent with the single-pass deposition layer size under the selected steady-state condition. At this time, the P corresponding to the edge position can be obtained. JL 、V L Substituting into formula (13) we can find the value of constant C:

[0080]

[0081] So far, the above experiments have obtained P JW 、V W 、r W and C values. In the predicted three-dimensional forming model, when the molten pool moves to a certain x position, the position of the deposition point can be calculated based on the three-dimensional size of the formed part. W The local heat dissipation volume V of the base metal in the spherical area with a radius x , substituting into formula (13) we can get the power P at that position Jx , so that the power P of the molten pool is formed at this position Rx The power P required to form a steady-state molten pool RW equal, thereby ensuring that the size of the single-channel deposition layer at this position is consistent with the size of the single-channel deposition layer in the selected steady-state condition, thereby achieving the control of the size of the single-channel deposition layer in the laser fuse additive manufacturing process.

[0082] According to the above method, based on the generated multi-channel and multi-layer deposition paths, as the position of the deposition point changes during the channel-by-channel and layer-by-layer deposition process, the local heat dissipation volume of the position is calculated point by point, and then the laser power to be selected at the position can be calculated according to formula (13). In this way, by calculating and selecting point by point, channel by channel and layer by layer, the process parameters that change correspondingly with the change of the deposition path can be generated. Other parameters remain unchanged, and the laser power changes with the change of the local heat dissipation volume, that is, the deposition path and its corresponding process parameters are generated.

[0083] Finally, the laser fuse automatic deposition device performs additive manufacturing of parts layer by layer according to the final generated process path and corresponding process parameters.

[0084] Among them, when calculating the local heat dissipation volume of the deposition point point by point along the deposition path, the smaller the spacing selected for the point-by-point calculation, the greater the amount of calculation will be, but the more precise the power regulation and control will be; in practical applications, a balanced consideration is required, and the spacing value range of the point-by-point calculation is usually 2-5mm.

[0085] Example 1

[0086] The present invention is further described below by taking the additive manufacturing of a circular ring part (made of stainless steel 316L) as an example.

[0087] The three-dimensional model of the ring part in this embodiment is as follows: Figure 4 As shown in the figure, the part is a ring with an outer diameter of 100 mm, a wall thickness of 1 mm, and a height of 10 mm. According to the characteristics and process requirements of laser fuse additive manufacturing, the model is layered and processed in lanes. The layer thickness h c =0.5mm, track width w d=1.0mm; then generate the multi-channel multi-layer deposition path for the part: a total of 22 layers, each layer is a circular track with a width of 1mm and a diameter of 99mm. According to the layer thickness of 0.5mm and the width of 1.0mm, the size of the single-channel deposition layer in the steady state is selected as the height h a =0.5mm and width w a =1.49mm, its cross-sectional profile is close to a circular arc, and the cross-sectional area S a =0.5mm 2 According to the size of the single deposition layer under the selected steady state and the generated deposition path, the predicted forming diagram of the ring part is deposited layer by layer. Figure 5 shown.

[0088] Before additive manufacturing, a large number of process tests and parameter optimization were performed to obtain the single-pass deposition layer size (h a =0.5mm, w a =1.49mm and S a =0.5mm 2 )The corresponding steady-state process parameters are shown in Table 1.

[0089] Table 1 Steady-state process parameters Parameter name unit Numeric Wire diameter d mm 0.8 <![CDATA[Wire feeding speed V f > mm / s 7 <![CDATA[Scanning speed V s > mm / s 7 <![CDATA[Laser power P JW > W 450 Fiber laser wavelength μm 1080 Spot diameter mm 0.6 Argon gas flow Q L / min 10 Wire feeding angle ° 60 Wire feeding method Post wire feeding Welding wire material Stainless steel 316L Base material Stainless steel 316L <![CDATA[Interlayer temperature T C > ℃ 200

[0090] Selection of interpass temperature T for stainless steel 316L during laser fuse additive manufacturing C is 200℃, according to Figure 2 The method shown in the figure, when a single-pass deposition test is performed using the selected steady-state process parameters under steady-state conditions, the temperature from the center of the molten pool to the plate is measured as T C The distance from (local heat dissipation radius in steady state) r W =4mm. In steady state, r W The local heat dissipation volume of the flat base metal (i.e., substrate 1) in the spherical area with a radius

[0091] Then, if Figure 3 As shown in the figure, a single-pass laser fuse deposition test is carried out at the edge position. The other process parameters are the same as the steady-state process parameters. Only the laser power value is adjusted to make the deposition layer size at the edge position consistent with the single-pass deposition layer size under the selected steady-state condition. Thus, the P corresponding to the edge position can be obtained. JL =430W, V L =85.528mm 3 , substituting into formula (14) we can find the value of constant C:

[0092]

[0093] Since the part is a centrally symmetrical part, as mentioned above, when calculating the local heat dissipation volume, the upper hemisphere of the spherical area is ignored, and only the volume of the base metal in the lower hemisphere is calculated. Therefore, for this part, the local heat dissipation volume of each deposition point located in the same layer is the same, and the steady-state heat dissipation volume is also the same. Therefore, there is no need to calculate point by point and channel by channel, but only to find out the local heat dissipation volume of each layer and the corresponding laser power layer by layer.

[0094] The first layer is deposited on the base plate (i.e., substrate 1), and its power P J1 The laser power P in steady state JW The same, that is, P J1 =450W.

[0095] The schematic diagram of the local heat dissipation volume V2 of the base metal in the spherical area with radius rW when the deposition point is in the second layer is as follows Figure 6 As shown, according to the three-dimensional dimensions of the formed part, V2 = 114.951 mm3 can be calculated. Substituting it into formula (13) can obtain the power at this position

[0096] P 62 =P 6w -C(V w -V 2 )=450-C(134.041-114.951)=442.135W.

[0097] The schematic diagram of the local heat dissipation volume V3 of the base metal in the spherical area with radius rW when the deposition point is in the third layer is as follows Figure 7 As shown, according to the three-dimensional dimensions of the formed part, V3 = 96.55 mm3 can be calculated. Substituting into formula (13) we can get the power P at this position: 63 =434.554W.

[0098] By analogy, the schematic diagram of the local heat dissipation volume V9 of the base metal in the spherical area with a radius of rW when the deposition point is at the 9th layer is as follows: Figure 8 As shown, based on the three-dimensional dimensions of the formed part, V9 = 37.023 mm3 is calculated. Substituting into formula 13, the power P at this position can be obtained. 6< =410.029W.

[0099] Using this method, the local heat dissipation volume and laser power of each layer are calculated as shown in Table 2. Table 2 Local heat dissipation volume and laser power of each layer Number of layers <![CDATA[Local heat dissipation volume V x / mm 3 > <![CDATA[Laser power P Jx / W]]> 1 134.041 450 2 114.951 442.135 3 96.550 434.554 4 79.525 427.539 5 64.554 421.371 6 52.286 416.317 7 43.332 412.628 8 38.220 410.522 9 37.023 410.029 10 37.023 410.029 … … … 22 37.023 410.029

[0100] The laser fuse automatic deposition device performs additive manufacturing of parts layer by layer according to the process path generated above and the process parameters corresponding to each layer (other steady-state process parameters remain unchanged, and the laser power of each layer is selected according to Table 2). This ensures that the power of the molten pool formed at each deposition point remains consistent, thereby keeping the size of each deposition layer stable. Finally, it ensures that the forming size of the laser wire additively manufactured parts meets the design requirements.

[0101] The present invention actively controls the size of a single deposition layer in advance, and the method is simple and reliable. Before the laser fuse automatic deposition device performs additive manufacturing, the laser power at the position is predicted and selected in advance based on the local heat dissipation volume of the deposition point position in the process of layer-by-layer deposition, while ensuring that the power for forming a molten pool remains unchanged. The control of the molten pool width is highly real-time, and process parameters obtained through a large number of process tests and parameter optimization are used in the deposition process, which can stabilize the deposition process and the size of each deposition layer, and finally ensure that the forming size of the laser metal wire additively manufactured parts meets the design requirements.

[0102] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A laser fuse additive manufacturing forming control method, It is characterized in that The following steps are involved: (1) Establish a three-dimensional model of the part, perform layering and lane processing on the model, and generate multi-channel and multi-layer deposition paths; (2) selecting the size of a single-channel deposition layer and the steady-state process parameters corresponding to the size of the single-channel deposition layer under steady-state conditions according to the layer thickness and the channel width of the divided channels; (3) Under the premise of ensuring that the power for forming the molten pool remains unchanged, the corresponding laser power is calculated and selected according to the local heat dissipation volume of the deposition point when the laser moves along the deposition path, and the process parameters corresponding to the changes in the deposition path and the local heat dissipation volume of the deposition point are generated; (4) According to the deposition path generated in step (3) and its corresponding process parameters, additive manufacturing of the part is performed layer by layer, and finally a laser fuse additively manufactured part is obtained.

2. A laser fuse additive manufacturing forming control method according to claim 1, It is characterized in that The steady state described in step (2) means that when a laser fuse single-pass deposition test is carried out in the middle of a flat plate having a size of not less than 150 mm × 75 mm × 30 mm at room temperature, in the middle stage of the deposition process, the molten pool temperature field is in a relatively stable stage and the molten pool size is also in a stable state.

3. A laser fuse additive manufacturing forming control method according to claim 1, It is characterized in that In step (2), the dimensions of a single deposition layer include height, width and cross-sectional area.

4. A laser fuse additive manufacturing forming control method according to claim 1, It is characterized in that In step (2), the steady-state process parameters of the single-channel deposition layer refer to the parameters under which a stable deposition process and a stable deposition layer size can be obtained. The cross-sectional profile of the single-channel deposition layer is close to an arc shape, and its height is equal to the layer thickness of the layer. Its cross-sectional area is equal to the layer thickness of the layer multiplied by the track width of the layer. The height of the deposition layer obtained by overlapping the single-channel deposition layer with the track width as the spacing is equal to the layer thickness of the layer. The size of the single-channel deposition layer is the size of the single-channel deposition layer under steady-state conditions selected based on the layer thickness of the layer and the track width.

5. A laser fuse additive manufacturing forming control method according to claim 4, It is characterized in that The steady-state process parameters include at least: wire diameter, wire feeding speed, scanning speed, laser power, fiber laser wavelength, spot diameter, argon flow rate, wire feeding angle, wire feeding method, welding wire material, matrix material and interlayer temperature. The values ​​of the steady-state process parameters are determined through process tests and parameter optimization.

6. A laser fuse additive manufacturing forming control method according to claim 1, It is characterized in that In step (3), based on the multi-channel and multi-layer deposition paths generated in step (1), the local heat dissipation volume of the deposition point position is calculated point by point, and then the laser power to be selected at the position is calculated based on the local heat dissipation volume. In this way, the calculation is performed layer by layer to generate a laser power that changes accordingly with the deposition path. Other parameters are steady-state parameters that remain unchanged, thereby generating a deposition path and its corresponding process parameters.

7. The laser fuse additive manufacturing forming control method according to claim 1, It is characterized in that On the deposition path, when calculating the local heat dissipation volume of the deposition point position point by point, the spacing between each point ranges from 2 to 5 mm.

8. A laser fuse additive manufacturing forming control method according to claim 6, It is characterized in that Local heat dissipation volume V at the deposition point x , refers to the area falling on r W is the volume of the base metal within a spherical region of radius r, the base metal including the plate and the deposited layers, W is the local heat dissipation radius in steady state, that is, the temperature from the center of the molten pool to the plate in steady state is T C The distance at C The interlayer temperature that needs to be maintained for multi-layer cladding.

9. A laser fuse additive manufacturing forming control method according to claim 8, It is characterized in that According to the local heat dissipation volume V at the deposition point x The specific method for calculating laser power is: P Jx =P JW -C(V W -Vx); Among them, P Jx is the laser power corresponding to the deposition point x, P JW is the laser power in steady state, C is a constant, V W is the local heat dissipation volume in steady state, V x is the local heat dissipation volume at the deposition point, P JW 、V W The values ​​of and C are obtained through process experiments and parameter optimization.

10. A laser fuse additive manufacturing forming control method according to claim 9, It is characterized in that Local heat dissipation volume at steady state where r W is the local heat dissipation radius in steady state, that is, the temperature from the center of the molten pool to the flat plate is the interlayer temperature T C The distance between the

Images