CN110496965B

CN110496965B - Method and device for preparing flexible additive gradient functional material

Info

Publication number: CN110496965B
Application number: CN201910788424.1A
Authority: CN
Inventors: 鲁金忠; 徐刚; 罗开玉
Original assignee: Jiangsu University
Current assignee: Jiangsu University
Priority date: 2019-08-26
Filing date: 2019-08-26
Publication date: 2022-01-11
Anticipated expiration: 2039-08-26
Also published as: CN110496965A

Abstract

The invention relates to the field of laser additive manufacturing, in particular to a method and a device for preparing a flexible additive gradient functional material, wherein the proportion of mixed powder of each layer is changed in the additive process, so that the element gradient distribution of an additive component is realized, dissimilar metal powder is fully and uniformly mixed, and the uniformity and compactness of the additive component are ensured; meanwhile, the recovery of redundant powder in the mixed powder is realized, the cost is saved to a great extent, and the quality of the additive component is improved.

Description

Method and device for preparing flexible additive gradient functional material

Technical Field

Background

The FGMS is an advanced material, and is characterized in that the change of the volume composition and element content of the material is helpful to correspondingly change the material performance according to the functional requirements. The multifunctional state of the assembly is adjusted by the material distribution of the microstructure to meet the desired performance requirements. The microstructural grading resulting from the gradient change of the elements contributes to a smooth transition between the properties of the material. Functionally Graded Materials (FGMS) are characterized by the ability to vary the material properties accordingly to the functional requirements. From the view point of gradient distribution of materials, the gradient functional materials are different from homogeneous materials and composite materials. The material is a material with gradient function formed by selecting two (or more) materials with different properties, and continuously changing the composition and the structure of the two (or more) materials to ensure that the interface disappears, so that the properties of the material are slowly changed along with the change of the composition and the structure of the material.

Laser Additive Manufacturing (LAM) is a new rapid forming technology, and has the characteristics of shallow heat affected layer, high precision of a material-added component and the like, and meanwhile, the Laser additive manufacturing does not need to use a casting mold, can realize rapid forming manufacturing of a metal component, reduces the production cost, and improves the quality of the material-added component. The traditional gradient functional materials are mainly prepared by a self-propagating high-temperature synthesis method, a dry spraying and temperature gradient sintering method and a laser heating synthesis method, a large amount of heat is easily introduced in the preparation process of the traditional gradient functional materials, so that a large amount of residual tensile stress is introduced, and the prepared gradient functional materials are low in precision and are not easy to meet the application of the gradient functional materials in industrial production. Meanwhile, the method and the device well solve the problem that metal powder is not easy to recover in the preparation process of the gradient material by using the powder-spreading type laser additive manufacturing method, save the production cost and are more beneficial to popularization of industrial application.

Disclosure of Invention

The invention provides a method and a device for a flexible additive gradient functional material, wherein the proportion of mixed powder of each layer is changed in the additive process, so that the element gradient distribution of an additive component is realized, dissimilar metal powder is fully and uniformly mixed, and the uniformity and compactness of the additive component are ensured; the problems of thermal stress damage of the prepared gradient functional material and difficult recovery of metal powder in the preparation process are effectively solved, the service quality of the gradient functional material is improved, and the production cost is reduced.

The invention provides a device for flexible additive gradient functional material, which comprises: the powder spreading machine comprises a movable piston I, a powder spreading scraper I, a powder feeding barrel A, a shielding gas inlet, a powder spreading scraper II, a movable piston II, a feeding barrel B, a residual powder collecting device, a porous film, an electromagnetic adsorption device, a powder spreading roller, a movable piston III, a scanning laser head, a shielding gas outlet, a shell, a laser, a working platform and a PLC (programmable logic controller) control system; the powder spreading scraper I, the powder spreading scraper II, the residual powder collecting device, the porous film, the electromagnetic adsorption device, the powder spreading roller and the scanning laser head are positioned in the shell, the residual powder collecting device is installed in the electromagnetic adsorption device, and the porous film is installed at the bottom end of the electromagnetic adsorption device; the powder feeding barrel A, the powder feeding barrel B and the working platform are positioned at the bottom end of the shell from left to right and are communicated with the shell; the movable piston I is positioned in the powder feeding barrel A, the movable piston II is positioned in the powder feeding barrel B, and the movable piston III is positioned below the working platform; the upper surfaces of the feeding barrel A, the feeding barrel B and the working platform are positioned on the same horizontal plane, the electromagnetic adsorption device is positioned above the feeding barrel B, the powder spreading scraper blade is positioned on the left side of the feeding barrel A, the powder spreading scraper blade is positioned on the left side of the feeding barrel B, the powder spreading roller is positioned on the right side of the feeding barrel B, the scanning laser head is positioned right above the working platform and connected with a laser positioned outside the shell, and the air inlet and the air outlet are respectively positioned on the left side and the right side of the shell; the movable piston I, the powder paving scraper II, the movable piston II, the electromagnetic adsorption device, the powder paving roller, the movable piston III, the scanning laser head and the laser all work under the control of the PLC control system.

The invention relates to a method for preparing a flexible additive gradient functional material, which is characterized in that the current passing through an electromagnetic adsorption device is adjusted according to the mass of powder with different particle sizes, a layer of porous film is attached to the bottom end of the electromagnetic adsorption device to change the mass of adsorbed matrix metal powder, and then a feeding barrel A is used for filling the vacancy of the adsorbed matrix metal powder with another metal powder to complete the mixing of dissimilar metal powder; then, scanning the layer of powder by using laser to complete the laser 3D printing process of the layer, and changing the porosity of the porous film after completing the 3D printing of the layer, so that the mixing proportion of the mixed powder is changed, and finally the 3D printing process of the whole metal component made of the gradient functional material is completed; the method comprises the following specific steps:

(1) the movable piston in the feeding barrel B moves upwards to enable the thickness a of the metal powder on the upper surface of the feeding barrel B to be 0.5-0.8 mm.

(2) Attaching a porous film with porosity of X on the electromagnetic adsorption device, wherein the porosity of the porous film has a gradient increasing trend from 0% to less than 100%, and a current with a size of I is introduced into the electromagnetic adsorption device, and the magnetic force in the electromagnetic adsorption device and the current passing through the electromagnetic adsorption device satisfy the following relation: f_x＝5.1×I²×(d_L/d_δ) Wherein Fx is the magnetic force of the electromagnetic adsorption device, and I is the current passing through the coil; the magnetic force of the electromagnetic adsorption device simultaneously satisfies the following conditions: f_x＝40/3Πd³Rho, wherein d is the particle size of the metal powder and rho is the density of the metal powder, and the adsorbed matrix metal powder is in the residual powder collecting device and generates vacancies in the powder above the feeding barrel B.

(3) Upward movement of the movable piston in the feed barrel A causes upward movement of the powder, resulting in a thickness of the powderA is larger than a, the thickness of the metal powder on the feeding barrel B is a value, and the height of the starting point of the powder spreading scraper I is H_{Powder spreading scraper 1}，H_{Powder spreading scraper 1}And (d) placing another metal powder at a powder vacancy position above the material conveying barrel B from left to right by a powder laying baffle I to finish the mixing of the dissimilar powder.

(4) Adjusting the initial height of the powder spreading roller to be H_{Powder spreading roller}＝H_{Powder spreading scraper 1}Moving from right to left, transferring the redundant powder to a feeding barrel A to recover the redundant powder, fully mixing the dissimilar metal mixed powder above a feeding barrel B, and adjusting the initial height of a powder spreading scraper blade II to be H_{Powder spreading scraper 1}Moving the dissimilar metal mixed powder above the feeding barrel B to a workbench on the right side, scanning the metal powder on the layer by using laser, and completing the laser 3D printing process of the layer, wherein the thickness B of the layer after material increase is 0.5-0.8 mm; the laser power is 10-100W, and the scanning speed is 0.01-10 m/s.

(5) Changing the porosity of the porous film on the electromagnetic adsorption device to change the mixing proportion of the mixed powder, and meanwhile, moving the first movable piston and the second movable piston upwards, moving the working platform downwards, wherein the moving distances are both b, and b is 0.5-0.8 mm. And (5) repeating the steps (2) to (4) to finish the laser additive manufacturing process of the whole gradient functional material except the last layer.

(6) Closing the electromagnetic adsorption device, moving the movable piston upwards, moving the working platform downwards, wherein the moving distances are b, and b is 0.5-0.8 mm; the movable piston II is fixed, the initial height of the powder spreading scraper I is adjusted to be 0, metal powder is moved to the upper portion of the feeding barrel B from the feeding barrel A, the height of the powder spreading roller is still a, the powder spreading roller moves from right to left, the metal powder is moved to the feeding barrel A to recover redundant powder, the metal mixed powder above the feeding barrel B is moved to the workbench on the right side by the powder spreading scraper II, laser is used for scanning the metal powder on the layer, and the laser 3D printing process of the last layer is completed.

The gain effect of the invention is as follows:

1) the invention can change the proportion of each layer of mixed powder in the additive process, thereby realizing the gradient distribution of the element content of the additive component, fully and uniformly mixing the dissimilar metal powder and ensuring the uniformity and compactness of the additive component;

2) the invention can realize the classified recovery of different powders in the material increasing process, thereby saving the cost to a great extent and improving the powder utilization rate.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions of the prior art, the drawings used in the examples or the prior art are briefly described below.

Fig. 1 is a schematic view of an apparatus according to the present invention.

FIG. 2 is a schematic view of a porous membrane.

Table 1 shows the tensile properties of tensile specimens taken at different heights.

1. A first movable piston; 2. spreading a powder scraper I; 3. a powder feeding barrel A; 4. a shielding gas inlet; 5. spreading a powder scraper II; 6. a second movable piston; 7. a feeding barrel B; 8. a residual powder collecting device; 9. a porous film; 10. an electromagnetic adsorption device; 11. a powder spreading roller; 12. a movable piston III; 13. scanning a laser head; 14. adding a material sample; 15. a shielding gas outlet; 16. a housing; 17. a laser; 18. a working platform; 19. and (4) a PLC control system.

Detailed Description

The following detailed description of the present invention will be made with reference to the accompanying drawings and examples, but the present invention should not be limited to the examples.

The base metal powder used in example 1 was TC4 titanium alloy powder having a particle size of 10 μm, and the mixed powder was 316L stainless steel powder having a particle size of 10 μm.

The porous film is a macromolecular polyester plastic film, the porosity of the porous film is 0, 20%, 40%, 60% and 80% in sequence, and the porous film is purchased from Shenzhen hongmei film Co.

The method comprises the following specific steps:

(1) the movable piston II in the feeding barrel B moves upwards to enable the thickness of the TC4 titanium alloy powder on the upper surface of the feeding barrel B to be 0.6 mm.

(2) In the electromagnetic adsorption deviceAttaching a porous film with porosity of 0, and introducing into an electromagnetic adsorption device with size of 2.42 × 10^-5Direct current of A, magnetic force F of electromagnetic device_xIs 6 x 10^-10N, the magnetic force of the electromagnetic device is equal to the gravity of the TC4 titanium alloy powder.

(3) And a movable piston in the feeding barrel A moves upwards to enable the 316L stainless steel powder to move upwards, so that the thickness of the 316L stainless steel powder is larger than 0.6mm, the height of a starting point of the powder spreading baffle plate 1 is adjusted to be 0.6mm, and the 316L stainless steel powder is placed at a vacant position of TC4 titanium alloy powder by the powder spreading baffle plate 1 from left to right to complete the mixing of dissimilar powder.

(4) Adjusting the initial height of a powder spreading roller to be 0.6mm, moving the powder spreading roller from right to left, moving 316L stainless steel powder to a material conveying barrel A to recycle redundant powder, fully mixing heterogeneous metal mixed powder above a material conveying barrel B, adjusting the initial height of a powder spreading scraper to be 0mm, moving the heterogeneous metal mixed powder above the material conveying barrel B to a workbench on the right side, scanning the metal powder on the layer by using laser, wherein the laser power is 50W, the scanning speed is 5m/s, completing the laser 3D printing process of the layer, and increasing the thickness of the layer to be 0.6 mm.

(5) Changing the porosity of the porous film on the electromagnetic adsorption device to be 20%, 40%, 60% and 80% in sequence to change the mixing proportion of the mixed powder, meanwhile, moving the movable piston I and the movable piston II upwards, moving the working platform downwards, wherein the moving distance is 0.6mm, repeating the steps (2) - (4), and completing the laser material additive manufacturing process of the whole gradient functional material except the last layer.

(6) And (3) closing the electromagnetic adsorption device, moving the piston upwards, moving the working platform downwards, and keeping the moving distance of 0.6 mm. And (3) fixing a movable piston, adjusting the initial height of a powder paving scraper blade I to be 0, moving metal powder to the upper part of a feeding barrel B from the feeding barrel 1, moving a powder paving roller from right to left, moving 316L stainless steel powder to a feeding barrel A to recover redundant powder, adjusting the powder paving scraper blade to move mixed powder of dissimilar metals above the feeding barrel B to a workbench on the right side, scanning the metal powder on the layer by using the same laser parameters as those in the step (4), and finishing the laser 3D printing process of the last layer.

(7) Tensile samples were cut at different heights of the additive-manufactured gradient functional material, tensile tests were performed at a tensile speed of 0.5mm/s and a load of 200N, and the obtained tensile data are shown in table 1.

TABLE 1

Claims

1. a device for preparing flexible additive gradient functional material, is characterized in that, described device comprises movable piston 1, powder spreading scraper one, powder feeding bucket A, protective gas inlet, powder spreading scraper two, movable Piston 2, feeding barrel B, residual powder collecting device, porous film, electromagnetic adsorption device, powder spreading roller, movable piston 3, scanning laser head, protective gas outlet, shell, laser, working platform, PLC control system; among them, Powder spreading scraper 1, powder spreading scraper 2, residual powder collecting device, porous film, electromagnetic adsorption device, powder spreading roller and scanning laser head are located in the shell, and the residual powder collecting device is installed in the electromagnetic adsorption device, and is installed in the electromagnetic adsorption device. A porous film is installed at the bottom of the device; the powder feeding barrel A, the feeding barrel B and the working platform are located at the bottom end of the casing from left to right and communicate with the casing; the first movable piston is located in the powder feeding barrel A, and the second movable piston is located in In the powder feeding barrel B, the movable piston 3 is located under the working platform; the upper surface of the feeding barrel A, the feeding barrel B and the working platform are on the same level, the electromagnetic adsorption device is located above the feeding barrel B, and the powder spreading scraper 1 is located in the feeding barrel The left side of A, the second powder spreading scraper is located on the left side of the feeding bucket B, the powder spreading roller is located on the right side of the feeding bucket B, the scanning laser head is located directly above the working platform and connected to the laser outside the shell, the air inlet and the air outlet are respectively It is located on the left and right sides of the shell; movable piston 1, powder spreading scraper 1, powder spreading scraper 2, movable piston 2, electromagnetic adsorption device, powder spreading roller, movable piston 3, scanning laser head, laser are all in PLC work under the control of the control system.

2. The method for preparing a flexible additive gradient functional material using the device according to claim 1, wherein the current passing through the electromagnetic adsorption device is adjusted according to the quality of powders of different particle sizes, and a layer is attached to the bottom end of the electromagnetic adsorption device. The porous film changes the quality of the adsorbed base metal powder, and then the feeding barrel A uses another metal powder to fill the vacancies of the adsorbed base powder to complete the mixing of dissimilar metal powders; then use a laser to scan the layer of powder to complete the process. In the laser 3D printing process of the layer, after the 3D printing of the layer is completed, the porosity of the porous film is changed, thereby changing the mixing ratio of the mixed powder, and finally the 3D printing process of the entire gradient functional material metal component is completed. The specific steps are as follows:

(1) The movable piston two in the feeding barrel B moves upward so that the thickness of the metal powder on the upper surface of the feeding barrel B is a;

(2) A layer of porous film with a porosity of X is attached to the bottom end of the electromagnetic adsorption device, and at the same time, a current of size I is passed into the electromagnetic adsorption device, and the adsorbed base metal powder is collected in the residual powder collection device and fed in vacancies are created in the powder above barrel B;

(3) The movable piston in the feeding barrel A moves upward to move the powder upward, so that the powder thickness is greater than a, and the starting point height of the powder spreading baffle 1 is H powder spreading scraper 1, H powder spreading scraper 1= a. Powder spreading baffle 1 places another metal powder at the powder vacancy above feeding barrel B from left to right to complete the mixing of dissimilar powders;

(4) Adjust the initial height of the powder spreading roller to H powder spreading roller=H powder spreading scraper 1, move from right to left, move the excess powder to the feeding bucket A to recover the excess powder, and make the dissimilar species above the feeding bucket B Mix the metal mixed powder thoroughly, adjust the initial height of powder spreading scraper 2 to H powder spreading scraper 1=0, move the dissimilar metal mixed powder above the feeding bucket B to the worktable on the right, and use the laser The metal powder is scanned to complete the laser 3D printing process of the layer;

(5) Change the porosity of the porous film on the electromagnetic adsorption device to change the mixing ratio of the mixed powder. At the same time, the movable piston 1 and movable piston 2 move upward, the working platform moves downward, and repeat step (2)- (4), complete the laser additive manufacturing process of the entire gradient functional material except the last layer;

(6) Turn off the electromagnetic adsorption device, move the movable piston one upward, the movable piston two does not move, the working platform moves down, adjust the initial height of the powder spreading scraper 1 to 0, and move the metal powder from the feeding bucket A to the feeding Above the barrel B, the height of the powder spreading roller remains the same, and it moves from right to left to move the metal powder to the feeding barrel A to recover the excess powder. The powder spreading scraper 2 moves the metal powder above the feeding barrel B to On the workbench on the right, a laser is used to scan the metal powder of this layer to complete the laser 3D printing process of the last layer.

3. The method of claim 2, wherein in step (1), a is 0.5-0.8 mm.

4. The method according to claim 2, characterized in that, in step (2), the magnetic force in the electromagnetic adsorption device and the passing current satisfy the relationship: F _x =5.1×I ² ×(d _L /d _δ ), wherein Fx is the magnetic force of the electromagnetic adsorption device, I is the current passing through the coil, L is the inductance of the coil, δ is the length of the air gap; the magnetic force of the electromagnetic adsorption device simultaneously satisfies: F _x =40/3Πd ³ ρ, wherein, d is the metal powder The particle size, ρ is the density of the metal powder.

5. The method of claim 2, wherein the change trend of the porosity X of the porous film is a gradient increase from 0% to less than 100%, and the mixing ratio of dissimilar metals is changed by changing the porosity of the porous film.

6 . The method of claim 2 , wherein the process parameters of the laser additive manufacturing are: laser power 10-100 W, and scanning speed 0.01-10 m/s. 7 .

7. method as claimed in claim 2 is characterized in that, in step (5), movable piston 1 and movable piston 2 move upward, working platform moves downward, and the distance of movement is b, and b is 0.5- 0.8mm, b=a.

8. The method according to claim 2, characterized in that, in step (6), as soon as the movable piston moves upward, the working platform moves downward, and the moving distance is b, and b is 0.5-0.8 mm, and b= a.