Additive manufacturing method for automobile three-way catalytic converter and automobile three-way catalytic converter

Abstract

In order to overcome the problems existing in the prior art, the present invention discloses an additive manufacturing method for an automobile three-way catalytic converter, comprising: step 1 obtaining metal powder for preparing the three-way catalytic converter; step 2 dividing the metal powder in step 1 into at least two subdivided metal powders with different particle size ranges; step 3 the additive manufacturing equipment obtains the subdivided metal powder and performs a three-way catalytic converter model analysis; step 4 performs a printing analysis according to the analysis results of the three-way catalytic converter model analysis; step 5 controls the additive manufacturing equipment to perform additive manufacturing according to the printing analysis results to obtain the automobile three-way catalytic converter. The present invention introduces a normal distribution design of the particles of the powder material when designing the printing model, so that it fits the particle distribution morphology in the actual printing component to the maximum extent, and through the particle distribution optimization, the theoretical performance of the digital model reaches or exceeds the design performance.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile three-way catalytic converter preparation, and in particular to an additive manufacturing method for automobile three-way catalytic converter and an automobile three-way catalytic converter. Background Art

[0002] The three-way catalytic converter is the most important external purification device installed in the automobile exhaust system. It can convert harmful gases such as CO, HC and NOx emitted from automobile exhaust into harmless carbon dioxide, water and nitrogen through oxidation and reduction.

[0003] Iron-chromium-aluminum alloy (FeCrAl alloy) has the advantages of good oxidation resistance, high operating temperature and light weight, and is an excellent automobile three-way catalyst carrier metal. However, the processing performance of iron-chromium-aluminum alloy is poor, and automobile three-way catalytic converters generally need to adopt a honeycomb structure to expand the contact area between the catalyst and the exhaust gas. However, iron-chromium-aluminum alloy is difficult to be processed into a honeycomb shape. The existing technology generally adopts a processing method of welding thin sheets one by one or fixing them in sequence in other ways to obtain a honeycomb structure of iron-chromium-aluminum alloy automobile three-way catalytic converter carrier. The processing efficiency is low, resulting in high cost of use, which is difficult to promote and use.

[0004] The use of 3D printing technology can effectively overcome the problem of poor processing performance of iron-chromium-aluminum alloy. However, since the automobile three-way catalytic converter is a relatively precise component, the performance uniformity of the printed parts is required to be high. When printing using conventional 3D printing technology, the performance of the printed parts is often quite different from the theoretical performance, and the yield rate of the printed parts is not high. It cannot effectively overcome the problems of the existing processing methods of piece-by-piece welding or other fixing methods. Summary of the invention

[0005] In order to solve the problems raised in the above background technology, the present invention provides an additive manufacturing method for an automobile three-way catalytic converter, comprising:

[0006] Step 1: Obtain metal powder for preparing a three-way catalytic converter.

[0007] Step 2: The metal powder of step 1 is divided into at least two subdivided metal powders with different particle size ranges.

[0008] Step 3: The additive manufacturing equipment obtains finely divided metal powder and performs three-way catalytic converter model analysis.

[0009] Step 4 performs printing analysis based on the analysis results of the three-way catalytic converter model analysis.

[0010] Step 5 controls the additive manufacturing equipment to perform additive manufacturing according to the printing analysis results to obtain the automobile three-way catalytic converter.

[0011] Wherein, the three-way catalytic converter model analysis method includes:

[0012] Step 3.1 obtains the particle size range data Xn corresponding to the subdivided metal powder, and sorts them according to radius from large to small. At the same time, obtains the digital model of the three-way catalytic converter and places it in a three-dimensional coordinate system, and theoretically obtains the optimal volume percentage Ym corresponding to each subdivided metal powder Xn.

[0013] Step 3.2 generates a random number Kx through a random function and converts the random number Kx into a normally distributed particle radius through the Box-Muller algorithm.

[0014] Step 3.3. Randomly place Kx particles with a normally distributed particle radius generated in step 3.2 within the range of the three-way catalytic converter digital model.

[0015] Step 3.4 performs an overlap judgment to confirm whether the particle placed in step 3.3 overlaps with the adjacent particle in the particle group P already placed in the three-way catalytic converter digital model. When the particle placed in step 3.3 overlaps with the adjacent particle in the particle group P already placed in the three-way catalytic converter digital model, the placed particle is subjected to an anti-overlapping process.

[0016] Step 3.5 If the boundary of the particle placed in step 3.3 exceeds the boundary of the three-way catalytic converter digital model, it is considered that the particle exceeds the boundary and needs to be returned to the boundary.

[0017] Step 3.6: After all particles in step 3.3 are placed, the particle radius and particle spatial position data of the particles placed this time are stored, and the particles are combined with other previously placed particle groups P to form a new placed particle group P, and the volume percentage T of all current particles is calculated.

[0018] Step 3.7 Repeat the above steps 3.2 to 3.6 so that the volume percentage T of the particle Xn satisfies Ym in order from large to small radius.

[0019] Furthermore, the method of converting the random number Kx into a normally distributed particle radius by Box-Muller algorithm in step 3.2 includes:

[0020] Step 3.2.1. Design two independent standard normal distributions X~N(0,1) and Y~N(0,1). Since they are independent of each other, the joint probability density function is:

[0021]

[0022] Step 3.2.2: Transform equation 1 into polar coordinates to obtain:

[0023]

[0024] Step 3.3.3 Convert equation 2 to a standard uniform distribution, then:

[0025] θ~Unif(0,2π)=2πV Equation 3.

[0026] Another density function is:

[0027]

[0028] Step 3.3.4 combines equation 3 and equation 4 into the cumulative distribution function CDF:

[0029]

[0030] Step 3.3.5 Reverse equation 5 to obtain:

[0031]

[0032] Step 3.3.6 According to the inverse transform sampling principle, if we have the PDF of P(R), then the sample distribution obtained by uniform sampling of the inverse function of the aligned CDF will conform to the distribution of P(R). If u is uniformly distributed, then U=1-u is also uniformly distributed, so replace 1-u with U, and finally we can get:

[0033]

[0034] The two uniformly distributed random numbers U and V in equation 7 and equation 8 are obtained by a random function.

[0035] Step 3.3.7: Substitute the random numbers U and V into the Box-Buller algorithm to obtain the normally distributed particle radius corresponding to the random number Kx and randomly set the particle position.

[0036] Furthermore, the method for performing overlap determination in step 3.4 includes:

[0037] First, the center position of particle 1 in the three-way catalytic converter is (x1, y1, z1), and the radius is R1. The center position of particle 2 is (x2, y2, z2), and the radius is R2. ... The center position of particle V is (x v ,y v ,z v ), with a radius of R v The V is the natural number sequence number of the particles adjacent to the particle 1, with the particle 1 as the center.

[0038] Secondly, taking particle 1 as the target, the distances from particle 1 to the surrounding particles 2 and particle V are calculated as and get min =Min(d2,d3,d4…d v ).

[0039] Then, taking particle 1 as the target, calculate the relationship between particle 1 and d min The sum of the radii of the corresponding particles C m =R1+R m . Where m is d min The corresponding particle number.

[0040] Finally, make a judgment: If d min <C m , they are considered overlapping.

[0041] At this time, the anti-overlapping processing method described in step 3.4 includes:

[0042] First, the center position of particle 1 (x1, y1, z1) and the center position of particle m (x m ,y m ,z m ) and make a line O between them.

[0043] Next, calculate D m =(C m -d min ).

[0044] Finally, the center position of particle 1 is displaced D away from particle m along the extension line of line O. m , completing the anti-overlapping process.

[0045] After each anti-overlapping process is completed, the overlap judgment and anti-overlapping process are repeated with the new center position of particle 1 until d min ≥C m .

[0046] Furthermore, the method for performing overlap determination in step 3.4 includes:

[0047] First, the center position of particle 1 filled in the digital model of the three-way catalytic converter is obtained as (x1, y1, z1), and the radius is R1. The center position of particle 2 is (x2, y2, z2), and the radius is R2. ... The center position of particle V is (x v ,y v ,z v ), with a radius of R v The V is the natural number sequence number of the particles adjacent to the particle 1, with the particle 1 as the center.

[0048] Secondly, taking particle 1 as the target, the distances from particle 1 to the surrounding particles 2 and particle V are calculated as

[0049] Then, taking particle 1 as the target, the sum of the radius C of the particles between particle 1 and particle V is calculated.v =R1+R v .

[0050] Finally, count all d v <C v to obtain particle group D. If there are particles in particle group D, it is determined that there are overlapping particles.

[0051] At this time, the anti-overlapping processing method described in step 3.4 includes:

[0052] First, a vector group E is formed from particle 1 pointing to the centers of all particles in particle group D.

[0053] Afterwards, the sum vector F of the vector group E is calculated, and the inverse vector G of the sum vector F is obtained by calculation.

[0054] Finally, the center of particle 1 is displaced according to the reverse vector G to complete the anti-overlapping process.

[0055] After the anti-overlapping process is completed each time, the overlap judgment and anti-overlapping process are repeated with the new center position of particle 1 until there is no particle in particle group D.

[0056] Furthermore, the out-of-bounds particle is taken as the target particle B, and the back-bounds processing in step 3.5 includes:

[0057] First, the ratio S=Hb / H0 between the volume Hb of the target particles B exceeding the digital model of the three-way catalytic converter and the total volume H0 of the target particles B is determined.

[0058] Afterwards, determine: if S≥0.5, delete the particle. If S<0.5, proceed to the following steps.

[0059] (1) Determine whether there is a particle above the target particle B. If so, delete the particle. If not, proceed to step (2).

[0060] (2) Take the line connecting the center of the target particle B and the center of the surrounding particles as the vector group I, and make the sum vector I0 of the vector group I.

[0061] (3) Make the sum vector I0 point to the vertical vector IC inside the digital model of the three-way catalytic converter, as well as the inverse vector ID of the vertical vector IC.

[0062] (4) Taking the center of the target particle B as the starting point, draw a line W connecting the center of the target particle B and the boundary surface of the target particle B along the direction of the reverse vector ID.

[0063] (5) Taking the boundary surface of the three-way catalytic converter digital model as the boundary, the line W is divided into a part W1 inside the three-way catalytic converter digital model and a part W2 outside the three-way catalytic converter digital model.

[0064] (6) The target particle B is displaced by W2 along the vertical vector IC to complete the boundary return process.

[0065] (7) After completing the boundary return process, the overlap judgment described in step 3.4 is performed again. If there are overlapping particles, anti-overlapping processing is performed.

[0066] Furthermore, if the out-of-bounds or overlapping problem still cannot be eliminated after the same particle is repeatedly subjected to the back-bounds processing and the anti-overlapping processing for a preset number of times, the particle is deleted.

[0067] Furthermore, the printing analysis in step 4 includes:

[0068] Step 4.1: Get the digital model of the three-way catalytic converter to be printed, the diameter A of the printing nozzle, and A as the thickness of each printing layer.

[0069] In step 4.2, A is taken as the thickness of each printing layer, and the digital model of the three-way catalytic converter to be printed is equally divided into several printing layers L.

[0070] Step 4.3 obtains the particle size distribution diagram of the particles in the printing layer L and the average particle size value MD-L. In the particle size distribution of the printing layer L, the particle size distribution interval where the main particle size is located is selected, and the number of particles corresponding to each interval is NLe%. Where e is the natural number of the particle size distribution interval where the main particle size is located.

[0071] Step 4.4 obtains the particle size range of the finely divided metal powder, and adjusts the proportion values ​​t1, t2, t3, ..., tr of the finely divided metal powder according to the information described in step 4.3, so that the particle size DP-L of the mixed finely divided metal powder ≈ the average particle size value MD-L of the printing layer L.

[0072] The proportion values ​​t1, t2, t3, ..., tr of the finely divided metal powder are the printed analysis results.

[0073] Furthermore, the method of adjusting the proportions t1, t2, t3, ..., tj of the subdivided metal powder according to the information in step 4.3 includes:

[0074] Step 4.4.1: Obtain the D50 of each subdivided metal powder to obtain D50-1, D50-2, ..., D50-r, where r is the number of types of subdivided metal powder.

[0075] Step 4.4.2 obtains the particle size distribution of the printed layer L and selects the particle size distribution interval where the main particle size is located: DU-L-1, DU-L-2, ..., DU-Le, where DU-L is the particle size distribution interval of the L layer, and e is the natural number of the particle size distribution interval.

[0076] In step 4.4.3, obtain D50-1, D50-2, ..., D50-r that are closest to DU-L-1, DU-L-2, ..., DU-Le respectively, and use NLe% corresponding to DU-L-1, DU-L-2, ..., DU-Le as the adjustment coefficients p1, p2, p3, ..., pe of D50-1, D50-2, ..., D50-r, and take the sum of the adjustment coefficients of the same fine metal powder to obtain t1, t2, t3, ..., tr.

[0077] Step 4.4.4 Calculate DP-L = t1*D50-1+t2*D50-2+...+tr*D50-r, where DP-L is the calculated average particle size of the L layer.

[0078] In step 4.4.5, according to the difference between (DP-L) and (MD-L), the values ​​of t1 to tr are adjusted back and forth one by one in descending order, and each adjustment is a preset amplitude value, so that DP-L∈((MD-L)-UM, (MD-L)+UM) is finally achieved, where UM is the accuracy value of the three-way catalytic converter.

[0079] Furthermore, the additive manufacturing equipment described in step 5 includes: a 3D printing cavity and a microprocessor. A three-dimensional displacement system is provided in the 3D printing cavity, and the three-dimensional displacement system drives the print head to perform fixed-point displacement in a three-dimensional coordinate system under the control of the microprocessor. A melting mixer is provided at the bottom of the print head. The melting mixer is provided with at least two feeding ends and is connected to at least two subdivided metal powder feeding devices with different particle size ranges through one-to-one corresponding connecting pipes. A forced feeding device is provided at one end of the connecting pipe close to the melting mixer. The discharge end of the melting mixer is connected to the printing nozzle through another forced feeding device. The microprocessor controls the corresponding subdivided metal powder feeding device and the forced feeding device to feed the melting mixer according to the ratio values ​​t1, t2, t3, ..., tj of each subdivided metal powder.

[0080] The second object of the present invention is to provide an additively manufactured automotive three-way catalytic converter, which is prepared using FeCrAl alloy powder as raw material and the above-mentioned additive manufacturing method for automotive three-way catalytic converter.

[0081] In terms of mass percentage, the mass fraction of Cr in the FeCrAl alloy is 18%-25%, the mass fraction of Al is 4.5%-5.5%, and the balance is Fe.

[0082] When performing additive manufacturing, the FeCrAl alloy powder is divided into a screened part of finely divided metal powder and an unscreened part of finely divided metal powder by at least a 100-200 mesh sieve.

[0083] Preferably, the FeCrAl alloy further contains rare earth elements in an amount of 0.01%-0.2% by mass.

[0084] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0085] 1. The present invention introduces a normal distribution design of the particles of the powder material when designing the printing model, so that it fits the particle distribution morphology in the actual printed component to the greatest extent, and through particle distribution optimization, the theoretical performance of the digital model reaches or exceeds the design performance.

[0086] 2. The present invention controls the particle composition of the printing layer during printing so that the actual particle composition of each layer of the printed part is similar to the particle composition of the theoretical model, thereby making the actual performance of the printed part close to the theoretical performance of the digital model.

[0087] 3. The automobile three-way catalytic converter printed by the present invention has a small performance difference and stable component performance, and can realize efficient, low-cost, and large-scale preparation of FeCrAl alloy automobile three-way catalytic converters. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] Figure 1 It is a schematic structural diagram of the main components of the additive manufacturing equipment of the present invention.

[0089] Figure 2 Schematic diagram of the printing layers of the layer-by-layer printing method. DETAILED DESCRIPTION

[0090] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0091] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0092] Example 1

[0093] A three-way catalytic converter for an automobile is prepared by an additive manufacturing method using FeCrAl alloy powder as a raw material.

[0094] In the FeCrAl alloy powder, in terms of mass percentage, the mass fraction of Cr is 20%, the mass fraction of Al is 5%, and the balance is Fe.

[0095] The additive manufacturing method comprises:

[0096] Step 1: Obtain FeCrAl alloy powder for preparing a three-way catalyst and dry the powder in a vacuum oven at a temperature of 150°C.

[0097] Step 2: The FeCrAl alloy powder is screened through a 120-mesh screen to be divided into a screened part of the finely divided metal powder and an unscreened part of the finely divided metal powder. The screened part of the finely divided metal powder and the unscreened part of the finely divided metal powder are subjected to a powder particle size test to obtain the test results of the particle size distribution parameters, including D50, D90, particle size distribution range, etc., and the test results are numbered and recorded. The screened FeCrAl alloy powder is added to the corresponding silo.

[0098] Step 3: The additive manufacturing equipment obtains finely divided metal powder and performs three-way catalytic converter model analysis.

[0099] Step 4 performs printing analysis based on the analysis results of the three-way catalytic converter model analysis.

[0100] Step 5 controls the additive manufacturing equipment to perform additive manufacturing according to the printing analysis results to obtain the automobile three-way catalytic converter.

[0101] Wherein, the three-way catalytic converter model analysis method includes:

[0102] Step 3.1 obtains the particle size range data Xn corresponding to the subdivided metal powder, and sorts them according to radius from large to small. At the same time, obtains the digital model of the three-way catalytic converter and places it in a three-dimensional coordinate system, and theoretically obtains the optimal volume percentage Ym corresponding to each subdivided metal powder Xn.

[0103] Step 3.2 generates a random number Kx through a random function and converts the random number Kx into a normally distributed particle radius through the Box-Muller algorithm.

[0104] Step 3.3. Randomly place Kx particles with a normally distributed particle radius generated in step 3.2 within the range of the three-way catalytic converter digital model.

[0105] Step 3.4 performs an overlap judgment to confirm whether the particle placed in step 3.3 overlaps with the adjacent particle in the particle group P already placed in the three-way catalytic converter digital model. When the particle placed in step 3.3 overlaps with the adjacent particle in the particle group P already placed in the three-way catalytic converter digital model, the placed particle is subjected to an anti-overlapping process.

[0106] Step 3.5 If the boundary of the particle placed in step 3.3 exceeds the boundary of the three-way catalytic converter digital model, it is considered that the particle exceeds the boundary and needs to be returned to the boundary.

[0107] Step 3.6: After all particles in step 3.3 are placed, the particle radius and particle spatial position data of the particles placed this time are stored, and the particles are combined with other previously placed particle groups P to form a new placed particle group P, and the volume percentage T of all current particles is calculated.

[0108] Step 3.7 Repeat the above steps 3.2 to 3.6 so that the volume percentage T of the particle Xn satisfies Ym in order from large to small radius.

[0109] The step 5 specifically includes:

[0110] Step 5.1 Based on the printing analysis results, perform printing control according to the designed 3D printing digital model, and pay attention to the control of feed during the process.

[0111] Step 5.2 The FeCrAl three-way catalytic converter blank obtained by 3D printing is placed on the working bed for 2 hours, and then taken out and dried in a drying oven at 200°C for 2 hours.

[0112] Step 5.3: bury the dried green body in Al2O3 and sinter it in an argon atmosphere at 350°C for 2 hours. The final sintering temperature is 1500°C, and the green body is kept for 5 hours. The green body is then cooled in the furnace to obtain the automotive three-way catalytic converter.

[0113] When the existing technology performs 3D printing to manufacture three-way catalytic converters, the constructed printing model generally does not consider the particle size distribution of the printing material, but defaults to designing the printing model with the theoretically optimal particle distribution, and then controls the 3D printing equipment to print and prepare according to the printing model. However, during the printing process, the distribution of metal particles is not carried out according to the optimal distribution. The particle size of metal particles is often randomly distributed within a range, and in the printed components, under the action of various external forces, the coarse particles and fine particles are basically randomly distributed. This leads to uncontrollable differences in the performance of the printed components and the performance of the designed model, which seriously affects the yield rate of the three-way catalytic converter prepared by 3D printing.

[0114] The present invention gives priority to the distribution of particles of different sizes in the three-way catalytic converter when constructing the model, and constructs the 3D printed digital model in a random normal distribution manner that best fits the actual printed component, thereby significantly reducing the floating variation in the performance difference between the theoretical performance of the digital model and the performance of the actual printed component, and significantly improving the yield rate of the three-way catalytic converter prepared by 3D printing.

[0115] In addition, the present invention needs to meet the optimal volume percentage of particles of various particle sizes when constructing the digital model, so that the theoretical performance of the final digital model can reach or exceed the design requirements. Combined with the small difference between the performance of the digital model of the present invention and the actual component, the actual performance of the 3D printed component can be made to be excellent and stable.

[0116] Compared with the prior art, the FeCrAl automobile three-way catalytic converter prepared by the present invention has the advantages of high dimensional accuracy, large specific surface area, long service life, excellent comprehensive mechanical properties, high purification effect and high reliability, and also has the functions of silencing and dust prevention, and can meet the requirements of the Euro 5 standard for the emission of particulate matter content in exhaust gas.

[0117] Example 2

[0118] Based on the automobile three-way catalytic converter of Example 1, the method of converting the random number Kx into a normally distributed particle radius by using the Box-Muller algorithm in step 3.2 includes:

[0119] Step 3.2.1. Design two independent standard normal distributions X~N(0,1) and Y~N(0,1). Since they are independent of each other, the joint probability density function is:

[0120]

[0121] Step 3.2.2: Transform equation 1 into polar coordinates to obtain:

[0122]

[0123] Step 3.3.3 Convert equation 2 to a standard uniform distribution, then:

[0124] θ~Unif(0,2π)=2πV Equation 3.

[0125] Another density function is:

[0126]

[0127] Step 3.3.4 combines equation 3 and equation 4 into the cumulative distribution function CDF:

[0128]

[0129] Step 3.3.5 Reverse equation 5 to obtain:

[0130]

[0131] Step 3.3.6 According to the inverse transform sampling principle, if we have the PDF of P(R), then the sample distribution obtained by uniform sampling of the inverse function of the aligned CDF will conform to the distribution of P(R). If u is uniformly distributed, then U=1-u is also uniformly distributed, so replace 1-u with U, and finally we can get:

[0132]

[0133] The two uniformly distributed random numbers U and V in equation 7 and equation 8 are obtained by a random function.

[0134] Step 3.3.7: Substitute the random numbers U and V into the Box-Buller algorithm to obtain the normally distributed particle radius corresponding to the random number Kx and randomly set the particle position.

[0135] By constructing this random particle distribution model, the particle distribution in the digital model for printing can be highly similar to the particle distribution of the actual printed component, thereby improving the similarity of the powder particle distribution morphology between the digital model and the actual printed component, making the theoretical performance of the digital model more consistent with the actual performance of the printed component, which is conducive to obtaining high-precision 3D printed components.

[0136] Example 3

[0137] Based on the automobile three-way catalytic converter of Example 1, the method for performing overlap judgment in step 3.4 includes:

[0138] First, the center position of particle 1 in the three-way catalytic converter is (x1, y1, z1), and the radius is R1. The center position of particle 2 is (x2, y2, z2), and the radius is R2. ... The center position of particle V is (x v ,y v ,z v ), with a radius of R v The V is the natural number sequence number of the particles adjacent to the particle 1, with the particle 1 as the center.

[0139] Secondly, taking particle 1 as the target, the distances from particle 1 to the surrounding particles 2 and particle V are calculated as and get min =Min(d2,d3,d4…d v ).

[0140] Then, taking particle 1 as the target, calculate the relationship between particle 1 and dmin The sum of the radii of the corresponding particles C m =R1+R m . Where m is d min The corresponding particle number.

[0141] Finally, make a judgment: If d min <C m , they are considered overlapping.

[0142] At this time, the anti-overlapping processing method described in step 3.4 includes:

[0143] First, the center position of particle 1 (x1, y1, z1) and the center position of particle m (x m ,y m ,z m ) and make a line O between them.

[0144] Next, calculate D m =(C m -d min ).

[0145] Finally, the center position of particle 1 is displaced D away from particle m along the extension line of line O. m , completing the anti-overlapping process.

[0146] After each anti-overlapping process is completed, the overlap judgment and anti-overlapping process are repeated with the new center position of particle 1 until d min ≥C m .

[0147] Example 4

[0148] Based on the automobile three-way catalytic converter of Example 1, the method for performing overlap judgment in step 3.4 includes:

[0149] First, the center position of particle 1 filled in the digital model of the three-way catalytic converter is obtained as (x1, y1, z1), and the radius is R1. The center position of particle 2 is (x2, y2, z2), and the radius is R2. ... The center position of particle V is (x v ,y v ,z v ), with a radius of R v The V is the natural number sequence number of the particles adjacent to the particle 1, with the particle 1 as the center.

[0150] Secondly, taking particle 1 as the target, the distances from particle 1 to the surrounding particles 2 and particle V are calculated as

[0151] Then, taking particle 1 as the target, the sum of the radius C of the particles between particle 1 and particle V is calculated. v=R1+R v .

[0152] Finally, count all d v <C v to obtain particle group D. If there are particles in particle group D, it is determined that there are overlapping particles.

[0153] At this time, the anti-overlapping processing method described in step 3.4 includes:

[0154] First, a vector group E is formed from particle 1 pointing to the centers of all particles in particle group D.

[0155] Afterwards, the sum vector F of the vector group E is calculated, and the inverse vector G of the sum vector F is obtained by calculation.

[0156] Finally, the center of particle 1 is displaced according to the reverse vector G to complete the anti-overlapping process.

[0157] After the anti-overlapping process is completed each time, the overlap judgment and anti-overlapping process are repeated with the new center position of particle 1 until there is no particle in particle group D.

[0158] Embodiment 3 and embodiment 4 provide two methods for particle overlap judgment and anti-overlap processing, wherein embodiment 3 has a better processing effect when the particle size distribution range is relatively different, while embodiment 4 has a better processing effect when the particle size distribution range is relatively different.

[0159] Through the anti-overlapping process, it is possible to avoid the overlapping of randomly distributed particles in the digital model, which should not occur in the actual printed component, thereby affecting the similarity of the particle distribution between the digital model and the actual printed component.

[0160] Example 5

[0161] Based on the automobile three-way catalytic converter of Example 1, the particles that are out of bounds are taken as target particles B, and the return-to-bounds treatment in step 3.5 includes:

[0162] First, the ratio S=Hb / H0 between the volume Hb of the target particles B exceeding the digital model of the three-way catalytic converter and the total volume H0 of the target particles B is determined.

[0163] Afterwards, determine: if S≥0.5, delete the particle. If S<0.5, proceed to the following steps.

[0164] (1) Determine whether there is a particle above the target particle B. If so, delete the particle. If not, proceed to step (2).

[0165] (2) Take the line connecting the center of the target particle B and the center of the surrounding particles as the vector group I, and make the sum vector I0 of the vector group I.

[0166] (3) Make the sum vector I0 point to the vertical vector IC inside the digital model of the three-way catalytic converter, as well as the inverse vector ID of the vertical vector IC.

[0167] (4) Taking the center of the target particle B as the starting point, draw a line W connecting the center of the target particle B and the boundary surface of the target particle B along the direction of the reverse vector ID.

[0168] (5) Taking the boundary surface of the three-way catalytic converter digital model as the boundary, the line W is divided into a part W1 inside the three-way catalytic converter digital model and a part W2 outside the three-way catalytic converter digital model.

[0169] (6) The target particle B is displaced by W2 along the vertical vector IC to complete the boundary return process.

[0170] (7) After completing the boundary return process, the overlap judgment described in step 3.4 is performed again. If there are overlapping particles, anti-overlapping processing is performed.

[0171] Since the positions of particles are randomly distributed during modeling in the present invention, and whether the particles exceed the model boundary is not considered during anti-overlap processing, it is inevitable that some particles will exceed the model boundary. In the actual printing process, it is hoped that particles exceeding the boundary (affecting the surface uniformity of the component) will be avoided as much as possible. This method can make the constructed digital model have no particles exceeding the boundary, so that the total amount of particles exceeding the boundary in the actual component can be reduced during actual 3D printing, making the constructed surface smoother and the component surface performance better.

[0172] According to one embodiment of the present invention, if the same particle still cannot eliminate the out-of-bounds or overlapping problem after repeating the back-bound processing and anti-overlapping processing for a preset number of times, the particle is deleted. In this case, it means that the space in the model where the particle is located is not enough to support the complete filling of the particle, so the particle should be deleted for re-positioning.

[0173] Example 6

[0174] According to the automobile three-way catalytic converter of Example 1, the printing analysis in step 4 includes:

[0175] Step 4.1: Get the digital model of the three-way catalytic converter to be printed, the diameter A of the printing nozzle, and A as the thickness of each printing layer.

[0176] In step 4.2, A is taken as the thickness of each printing layer, and the digital model of the three-way catalytic converter to be printed is equally divided into several printing layers L.

[0177] Step 4.3 obtains the particle size distribution diagram of the particles in the printing layer L and the average particle size value MD-L. In the particle size distribution of the printing layer L, the particle size distribution interval where the main particle size is located is selected, and the number of particles corresponding to each interval is NLe%. Where e is the natural number of the particle size distribution interval where the main particle size is located.

[0178] Step 4.4 obtains the particle size range of the finely divided metal powder, and adjusts the proportion values ​​t1, t2, t3, ..., tr of the finely divided metal powder according to the information described in step 4.3, so that the particle size DP-L of the mixed finely divided metal powder ≈ the average particle size value MD-L of the printing layer L.

[0179] The proportion values ​​t1, t2, t3, ..., tr of the finely divided metal powder are the printed analysis results.

[0180] The method for adjusting the proportion values ​​t1, t2, t3, ..., tj of the subdivided metal powder according to the information in step 4.3 comprises:

[0181] Step 4.4.1: Obtain the D50 of each subdivided metal powder to obtain D50-1, D50-2, ..., D50-r, where r is the number of types of subdivided metal powder.

[0182] Step 4.4.2 obtains the particle size distribution of the printed layer L and selects the particle size distribution interval where the main particle size is located: DU-L-1, DU-L-2, ..., DU-Le, where DU-L is the particle size distribution interval of the L layer, and e is the natural number of the particle size distribution interval.

[0183] In step 4.4.3, obtain D50-1, D50-2, ..., D50-r that are closest to DU-L-1, DU-L-2, ..., DU-Le respectively, and use NLe% corresponding to DU-L-1, DU-L-2, ..., DU-Le as the adjustment coefficients p1, p2, p3, ..., pe of D50-1, D50-2, ..., D50-r, and take the sum of the adjustment coefficients of the same fine metal powder to obtain t1, t2, t3, ..., tr.

[0184] Step 4.4.4 Calculate DP-L = t1*D50-1+t2*D50-2+...+tr*D50-r, where DP-L is the calculated average particle size of the L layer.

[0185] In step 4.4.5, according to the difference between (DP-L) and (MD-L), the values ​​of t1 to tr are adjusted back and forth one by one in descending order, and each adjustment is a preset amplitude value, so that DP-L∈((MD-L)-UM, (MD-L)+UM) is finally achieved, where UM is the accuracy value of the three-way catalytic converter.

[0186] For example, the nozzle diameter of the printer used in this embodiment is 150 microns, so the thickness of a printed layer is 150 microns, the D50 of the sieved part of the finely divided metal powder is 115 microns, and the D50 of the unsieved part of the finely divided metal powder is 130 microns.

[0187] like Figure 2 As shown, when a three-way catalytic converter is printed, after analysis, the particle size distribution range of the main particle size of the first layer (L1) includes: 100-110 microns, the number of particles accounts for N-1-1% = 5.21%; 110-120 microns, the number of particles accounts for N-1-2% = 33.45%; 130-140 microns, the number of particles accounts for N-1-3% = 59.23%; 140-150 microns, the number of particles accounts for N-1-4% = 1.88%, and the remaining particles should account for less than the preset control margin upper limit, such as 0.25%, in this embodiment: 0.23%. The average particle size MD-L of the first layer (L1) is 124.13 microns, and the accuracy UM of the three-way catalytic converter is: 10 nanometers, that is, 0.01 microns. Therefore, ((MD-L)-UM, (MD-L)+UM)=(124.13-0.01, 124.13+0.01)=(124.12, 124.14). When calculating the average particle size MD-L, the particles whose volume in the digital model of the layer is half or more of the total volume of the particles in the layer are counted and calculated.

[0188] At this time, D50-1=115, D50-2=130, DU-1-1=100-110, DU-1-2=110-120, DU-1-3=130-140, DU-1-4=140-150, and the adjusted composition is:

[0189] DP-1=N-1-1%*D50-1+N-1-2%*D50-1+N-1-3%*D50-2+N-1-4%*D50-2=p1*D50-1+p2*D50-1+p3*D50-2+p4*D50-2 =(p1+p2)*D50-1+(p3+p4)*D50-2=(0.0521+0.3345)*115+(0.5923+0.0188)*130=44.459+79.443=123.902 microns.

[0190] MD-1=125.33,

[0191] Therefore: (DP-L)-(MD-L)=123.902-124.13=-0.228; a preset amplitude value is 0.1%=0.001. The current difference is negative, that is, DP-L is less than MD-L, so it is necessary to increase the adjustment coefficient of particles greater than 123.902, that is, D50-2, and reduce the adjustment coefficient of particles less than 123.902, that is, D50-1.

[0192] After the first adjustment:

[0193] DP-1=(0.0511+0.3335)*115+(0.5933+0.0198)

[0194] *130=44.229+79.703=123.932 microns, still does not belong to (124.12, 124.14),

[0195] A second adjustment is needed:

[0196] DP-1=(0.0501+0.3325)*115+(0.5943+0.0208)

[0197] *130=43.999+79.963=123.962 microns, which still does not belong to (124.12, 124.14).

[0198] A third adjustment is needed: ...After the final adjustment:

[0199] DP-1=(0.0441+0.3265)*115+(0.6003+0.0268)

[0200] *130=42.619+81.523=124.142≈124.14, which is (124.12, 124.14). That is, the final output adjustment coefficient of the feeding mechanism for the screened part of the subdivided metal powder is t1=(0.0441+0.3265)

[0201] =0.3696, the adjustment coefficient of the feeding mechanism for the unscreened part of the subdivided metal powder is t2=(0.6003+0.0268)=0.6271.

[0202] Similarly, we can obtain t1 and t2 corresponding to L2, L3, ..., and the last layer respectively.

[0203] That is, according to the output flow rate of the print head during printing, 37.06% of the material is provided by the screened part of the subdivided metal powder feeding mechanism, and 62.71% of the material is provided by the unscreened part of the subdivided metal powder feeding mechanism. The remaining amount of 0.23% is the control remaining amount. If the amount of material stored in the mixed material bin is large during the printing process, the remaining amount can be omitted. If the amount of material stored in the mixed material bin is small, the control remaining amount can be evenly divided into the screened part of the subdivided metal powder feeding mechanism and the unscreened part of the subdivided metal powder feeding mechanism, that is, the screened part of the subdivided metal powder feeding mechanism provides 37.06% + 0.115% = 37.175% ≈ 37.17%, and the unscreened part of the subdivided metal powder feeding mechanism provides 62.71% + 0.115% = 62.825% ≈ 62.83%.

[0204] When the prior art performs 3D printing, the printing model is designed based on the ideal particle distribution, that is, the particles are of the same size and evenly distributed, or particles of different sizes are cross-arranged in the best arrangement, so the particle material distribution corresponding to each printing layer digital model is uniform. Therefore, during actual printing, the caliber of the print nozzle is generally used as the basic thickness, and printing is performed layer by layer or area by area according to the contour of the printing model. The supply of particle material during the printing process is uniform, that is, the feeding relationship of each layer of the printed part is not changed. However, due to various external factors such as fluidity, particle size differences, and self-neutrality, the distribution of particles in the actual printing layer is not constant and uniform, and there is a large degree of randomness. As a result, there will be a performance difference between the random distribution of the printed part particle material and the ideal distribution of the printed model particle material, so that the performance of the printed part is always unstable and different from the theoretical performance of the model.

[0205] The present invention simulates the random distribution state of particles during printing when constructing the printing model, and optimizes based on the optimal content of granular materials of each particle size, so that the design model reaches or exceeds the design performance. The optimal content of granular materials of each particle size can be obtained by simulation through a simulation system as needed. On this basis, the particle size distribution of each printing layer of the present invention is not uniform, so it is necessary to adjust the ratio of different particles in the feed to obtain a mixture close to the ideal particle composition of each printing layer for printing, so that the performance of the resulting print is very close to the theoretical performance of the digital model, so that on the basis of the digital model reaching or exceeding the design performance, the performance of the printed component can also reach or exceed the design performance, thereby significantly improving the yield rate of the printed component on the one hand, and significantly reducing the performance difference between the printed components on the other hand, that is, the stability of product quality is significantly improved.

[0206] Example 7

[0207] According to the automobile three-way catalytic converter of embodiment 1, Figure 1As shown, the additive manufacturing equipment in step 5 includes: a 3D printing cavity, a microprocessor 1. A three-dimensional displacement system is provided in the 3D printing cavity, and the three-dimensional displacement system drives the print head 10 to perform fixed-point displacement in the three-dimensional coordinate system under the control of the microprocessor 1. A melting mixer 8 is provided at the bottom of the print head 10. The melting mixer 8 is provided with two feeding ends and is connected to the first subdivided metal powder feeding device 3 through the first connecting pipe 6, and is connected to the second subdivided metal powder feeding device 2 through the second connecting pipe 7. The first subdivided metal powder feeding device 3 is used to store and provide the screened part of the subdivided metal powder, and the second subdivided metal powder feeding device 2 is used to store and provide the unscreened part of the subdivided metal powder. The first connecting pipe 6 is provided with a first electrically controlled forced feeding mechanism 5 near the melting mixer 8, and the second connecting pipe 7 is provided with a second electrically controlled forced feeding mechanism 4 near the melting mixer 8. The discharge end of the melting mixer 8 is connected to the printing nozzle 11 through the third electrically controlled forced feeding mechanism 9.

[0208] The microprocessor 1 controls the first subdivided metal powder feeding device 3 to feed according to the ratio value t1 of the sieved part of the subdivided metal powder. The microprocessor 1 controls the feeding amount of the sieved part of the subdivided metal powder by controlling the first electrically controlled forced feeding mechanism 5. The microprocessor 1 controls the second subdivided metal powder feeding device 2 to feed according to the ratio value t2 of the unsieved part of the subdivided metal powder. The microprocessor 1 controls the feeding amount of the unsieved part of the subdivided metal powder by controlling the second electrically controlled forced feeding mechanism 4.

[0209] This device is improved to cooperate with the present invention. Compared with the conventional 3D printing device, the printing material output by the print head of the present invention is a mixture from different silos mixed by the melt mixer 8, so that the particle composition relationship of each actual printing layer is close to the particle composition of the printing layer obtained by simulating the digital model of the present invention.

[0210] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An additive manufacturing method for an automobile three-way catalytic converter, characterized in that: include: Step 1: obtaining metal powder for preparing a three-way catalyst; Step 2: dividing the metal powder obtained in step 1 into at least two subdivided metal powders with different particle size ranges; Step 3: The additive manufacturing equipment obtains the finely divided metal powder and performs a three-way catalytic converter model analysis; Step 4: Printing and analyzing the analysis results of the three-way catalytic converter model analysis; Step 5: controlling the additive manufacturing equipment to perform additive manufacturing according to the printing analysis results to obtain the automobile three-way catalytic converter; Wherein, the three-way catalytic converter model analysis method includes: Step 3.1 Obtain the particle size range data Xn corresponding to the subdivided metal powders, and sort them according to the radius from large to small, and at the same time obtain the digital model of the three-way catalytic converter and place it in a three-dimensional coordinate system, and theoretically the optimal volume percentage Ym corresponding to each subdivided metal powder Xn; Step 3.2 Generate a random number Kx through a random function; The random number Kx is converted into a normally distributed particle radius through the Box-Muller algorithm, which includes: Step 3.2.

1. Design two independent standard normal distributions X~N(0,1) and Y~N(0,1); since they are independent of each other, the joint probability density function is: Step 3.2.2: Transform equation 1 into polar coordinates to obtain: Step 3.3.3 Convert equation 2 to a standard uniform distribution, then: θ~Unif(0,2π)=2πV Equation 3; Another density function is: Step 3.3.4 Combine equation 3 and equation 4 into the cumulative distribution function CDF: Step 3.3.5 Reverse equation 5 to obtain: Step 3.3.6 According to the inverse transform sampling principle, if we have the PDF of P(R), then the sample distribution obtained by uniformly sampling the inverse function of the aligned CDF will conform to the distribution of P(R); if u is uniformly distributed, then U=1-u is also uniformly distributed, so replace 1-u with U, and finally we can get: The two uniformly distributed random numbers U and V in equations 7 and 8 are obtained by a random function; Step 3.3.7: Substitute the random numbers U and V into the Box-Buller algorithm to obtain the normally distributed particle radius corresponding to the random number Kx and randomly set the particle position; Step 3.

3. Randomly place Kx particles with a normally distributed particle radius generated in step 3.2 within the range of the three-way catalytic converter digital model; Step 3.4 performs an overlap judgment to confirm whether the particle placed in step 3.3 overlaps with the adjacent particle in the particle group P already placed in the digital model of the three-way catalytic converter; when the particle placed in step 3.3 overlaps with the adjacent particle in the particle group P already placed in the digital model of the three-way catalytic converter, an anti-overlapping process is performed on the placed particle; The method for performing overlap judgment comprises: First, the center position of particle 1 in the three-way catalytic converter is (x1, y1, z1), and the radius is R1; the center position of particle 2 is (x2, y2, z2), and the radius is R2; ... The center position of particle V is (x v ,y v ,z v ), with a radius of R v ; V is the natural number sequence number of the particles adjacent to particle 1, with particle 1 as the center; Secondly, taking particle 1 as the target, the distances from particle 1 to the surrounding particles 2 and particle V are calculated as and get min =Min(d2,d3,d4…d v ); Then, taking particle 1 as the target, calculate the relationship between particle 1 and d min The sum of the radii of the corresponding particles C m =R1+R m ; where m is d min The corresponding particle number; Finally, make a judgment: If d min <C m , they are considered to be overlapping; At this time, the anti-overlapping processing method described in step 3.4 includes: First, the center position of particle 1 (x1, y1, z1) and the center position of particle m (x m ,y m ,z m ) make a line O between them; Next, calculate D m =(C m -d min ); Finally, the center position of particle 1 is displaced D away from particle m along the extension line of line O. m , completing the anti-overlapping process; After each anti-overlapping process is completed, the overlap judgment and anti-overlapping process are repeated with the new center position of particle 1 until d min ≥C m ; or, The method for performing overlap judgment comprises: First, the center position of particle 1 filled in the digital model of the three-way catalytic converter is obtained as (x1, y1, z1), with a radius of R1; the center position of particle 2 is (x2, y2, z2), with a radius of R2; ... The center position of particle V is (x v ,y v ,z v ), with a radius of R v ; V is the natural number sequence number of the particles adjacent to particle 1, with particle 1 as the center; Secondly, taking particle 1 as the target, the distances from particle 1 to the surrounding particles 2 and particle V are calculated as Then, taking particle 1 as the target, the sum of the radius C of the particles between particle 1 and particle V is calculated. v =R1+R v ; Finally, count all d v <C v to obtain a particle group D; if there are particles in the particle group D, it is determined that there are overlapping particles; At this time, the anti-overlapping processing method includes: First, a vector group E is formed from particle 1 pointing to the centers of all particles in particle group D; Afterwards, the sum vector F of the vector group E is calculated, and the inverse vector G of the sum vector F is calculated; Finally, the center of particle 1 is displaced according to the reverse vector G to complete the anti-overlapping process; After each anti-overlapping process is completed, the overlap judgment and anti-overlapping process are repeated with the new center position of particle 1 until there is no particle in particle group D; Step 3.5 If the boundary of the particle placed in step 3.3 exceeds the boundary of the three-way catalytic converter digital model, it is considered that the particle exceeds the boundary and needs to be returned to the boundary; The out-of-bounds particle is taken as the target particle B, and the back-to-bounds processing includes: First, determine the ratio S=Hb / H0 between the volume Hb of the target particle B exceeding the digital model of the three-way catalytic converter and the total volume H0 of the target particle B; Afterwards, judge: if S≥0.5, delete the particle; if S<0.5, perform the following steps; (1) Determine whether there is a particle above the target particle B. If so, delete the particle. If not, proceed to step (2); (2) The line connecting the center of the target particle B and the center of the surrounding particles is taken as the vector group I, and the sum vector I0 of the vector group I is obtained; (3) Make the sum vector I0 point to the vertical vector IC inside the digital model of the three-way catalytic converter, and the inverse vector ID of the vertical vector IC; (4) Taking the center of the target particle B as the starting point, draw a line W connecting the center of the target particle B and the boundary surface of the target particle B along the direction of the reverse vector ID; (5) Taking the boundary surface of the three-way catalytic converter digital model as the boundary, the line W is divided into a portion W1 inside the three-way catalytic converter digital model and a portion W2 outside the three-way catalytic converter digital model; (6) The target particle B is displaced by W2 along the vertical vector IC to complete the boundary return process; (7) After completing the boundary return process, the overlap judgment described in step 3.4 is performed again. If there are overlapping particles, anti-overlapping processing is performed; Step 3.6: After all particles in step 3.3 are placed, the particle radius and particle spatial position data of the particles placed this time are stored, and the particles are combined with other previously placed particle groups P to form a new placed particle group P, and the volume percentage T of all the particles currently is calculated; Step 3.7 Repeat the above steps 3.2 to 3.6 so that the volume percentage T of the particle Xn satisfies Ym in order from large to small radius.

2. The additive manufacturing method for a three-way catalytic converter for an automobile according to claim 1, characterized in that: If the out-of-bounds or overlapping problem cannot be solved after the same particle is repeatedly processed for a preset number of times, the particle will be deleted.

3. The additive manufacturing method for a three-way catalytic converter for an automobile according to claim 1, characterized in that: The printing analysis in step 4 includes: Step 4.1 Obtain the digital model of the three-way catalytic converter to be printed, the diameter A of the printing nozzle, and A is the thickness of each printing layer; Step 4.2: With A as the thickness of each printing layer, the digital model of the three-way catalytic converter to be printed is equally divided into a number of printing layers L; Step 4.3: Obtain the particle size distribution diagram of the particles in the printing layer L, and the average particle size value MD-L; select the particle size distribution interval where the main particle size is located in the particle size distribution of the printing layer L, and the number of particles corresponding to each interval NLe%; where e is the natural number of the particle size distribution interval where the main particle size is located; Step 4.4 obtains the particle size range of the subdivided metal powder, and adjusts the proportions t1, t2, t3, ..., tr of the subdivided metal powder according to the information in step 4.3, so that the particle size DP-L of the mixed subdivided metal powder ≈ the average particle size MD-L of the printing layer L; The proportion values ​​t1, t2, t3, ..., tr of the finely divided metal powder are the printed analysis results.

4. The additive manufacturing method for a three-way catalytic converter for an automobile according to claim 3, characterized in that: The method for adjusting the proportion values ​​t1, t2, t3, ..., tj of the subdivided metal powder according to the information in step 4.3 comprises: Step 4.4.1 Obtain the D50 of each subdivided metal powder to obtain D50-1, D50-2, ..., D50-r, where r is the number of types of subdivided metal powder; Step 4.4.2: Select the particle size distribution interval where the main particle size is located in the particle size distribution of the printed layer L: DU-L-1, DU-L-2, ..., DU-Le, where DU-L is the particle size distribution interval of the L layer, and e is the natural number of the particle size distribution interval; Step 4.4.3: Obtain D50-1, D50-2, ..., D50-r that are closest to DU-L-1, DU-L-2, ..., DU-Le respectively, and use the NLe% corresponding to DU-L-1, DU-L-2, ..., DU-Le as the adjustment coefficients p1, p2, p3, ..., pe of D50-1, D50-2, ..., D50-r. The adjustment coefficients of the same fine metal powder are summed to obtain t1, t2, t3, ..., tr; Step 4.4.4: Calculate DP-L = t1*D50-1 + t2*D50-2 + ​​... + tr*D50-r; where DP-L is the calculated average particle size of the L layer; In step 4.4.5, according to the difference between (DP-L) and (MD-L), the values ​​of t1 to tr are adjusted back and forth one by one in descending order, and each adjustment is a preset amplitude value, so that DP-L∈((MD-L)-UM, (MD-L)+UM) is finally achieved, where UM is the accuracy value of the three-way catalytic converter.

5. According to the additive manufacturing method for automobile three-way catalytic converters as claimed in claim 3, the additive manufacturing equipment in step 5 comprises: A 3D printing cavity, a microprocessor; a three-dimensional displacement system is arranged in the 3D printing cavity, and under the control of the microprocessor, the three-dimensional displacement system drives the print head to perform fixed-point displacement in a three-dimensional coordinate system; a melting mixer is arranged at the bottom of the print head, and the melting mixer is provided with at least two feeding ends and is respectively connected with at least two subdivided metal powder feeding devices with different particle size ranges through one-to-one corresponding connecting pipes; a forced feeding device is arranged at one end of the connecting pipe close to the melting mixer; the discharge end of the melting mixer is connected with the printing nozzle through another forced feeding device; the microprocessor controls the corresponding subdivided metal powder feeding device and the forced feeding device to feed the melting mixer according to the ratio values ​​t1, t2, t3, ..., tj of each subdivided metal powder.

6. An automobile three-way catalytic converter, characterized in that: The FeCrAl alloy powder is used as raw material and is prepared by the additive manufacturing method of the automotive three-way catalytic converter according to any one of claims 1 to 5; wherein: In terms of mass percentage, the mass fraction of Cr in the FeCrAl alloy is 18%-25%, the mass fraction of Al is 4.5%-5.5%, and the balance is Fe; When performing additive manufacturing, the FeCrAl alloy powder is divided into a screened part of finely divided metal powder and an unscreened part of finely divided metal powder by at least a 100-200 mesh sieve.

7. The automobile three-way catalytic converter according to claim 6, characterized in that: The FeCrAl alloy also contains rare earth elements with a mass fraction of 0.01%-0.2%.

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