CN106334792A - Preparing and printing molding methods for metal low-temperature 3D printing material - Google Patents

Abstract

The invention discloses a material for metal low-temperature 3D printing, a preparation method thereof and a metal low-temperature 3D printing method. The formula uses stainless steel powder as a matrix, and an appropriate amount of binder is added therein. When the binder melts, the stainless steel powder obtains flow The metal body is printed layer by layer through the powder feeding 3D printer head, and the metal product is obtained through degreasing and sintering; the invention adopts low-temperature printing, and the printer head has the characteristics of low unit cost and customization. The printing method is practical, and the final metal Products with high precision and good quality. The invention has a wide range of applications, such as medical treatment, aerospace, machinery manufacturing and other industries, so as to meet people's needs for individualized metal products.

Description

A kind of preparation and printing molding method for metal low temperature 3D printing material

technical field

The present invention relates to the technical field of metal 3D printing, in particular to a preparation method for metal low-temperature 3D printing materials and a metal low-temperature 3D printing molding method.

Background technique

3D printing technology has become one of the most concerned emerging technologies in the world. This new mode of production, together with other digital production modes, will promote the realization of the third industrial revolution. One of the bottlenecks restricting the rapid development of 3D printing technology is printing materials, especially metal printing materials. The development and production of metal materials with better performance and greater versatility is the key to improving 3D printing technology. In terms of direct manufacturing of high-performance metal components using 3D printing technology, various metal powders with fine particle size, uniform particle size, high sphericity, and low oxygen content are required.

Traditional metal material 3D printing mainly adopts SLS (selective laser sintering) technology at present. Selective sintering is also called selective laser sintering. It uses CO ₂ laser as energy, and uses computer-controlled infrared laser beams to process non-metallic powders, metal powders or composites. The thin layer of powder is scanned and sintered at a certain speed and energy density according to the layered two-dimensional data, and the layers are piled up to form a three-dimensional solid product. The cost of the equipment is extremely expensive, and the price of processed products is calculated in grams. At the same time, due to the limitation of the particle size of the material and the intensity of the laser beam, many small holes may appear on the surface of the processed part, and the post-processing process of the workpiece is relatively complicated.

Secondly, 3D printing of traditional metal materials requires high-temperature melting of metal powder, which involves various physical processes such as solid-liquid phase transition of metal, surface diffusion, and heat conduction. Thermal deformation caused by high temperature can cause the geometry of 3D printed metal parts to deviate from the expected design. For stainless steel materials, it is relatively easy to oxidize at high temperature. Once oxidized, it is difficult to remove the scale on its surface by other methods.

In addition, most of the domestic metal powder materials used for 3D printing rely on imports, which are expensive, increase manufacturing costs, and limit the application and development of metal 3D printing technology to a certain extent. Therefore, raw material preparation is one of the key technologies for metal 3D printing.

At present, there is no effective solution for the above-mentioned technical problems.

Contents of the invention

Aiming at the above-mentioned technical problems in related technologies, the present invention proposes a method for the preparation of metal low-temperature 3D printing materials and its metal low-temperature 3D printing method, which can realize metal low-temperature 3D printing and open up new ideas for metal printing.

In order to realize the purpose of said metal low-temperature 3D printing, the technical scheme of the present invention is as follows:

A material for metal low-temperature 3D printing, which is composed of stainless steel metal powder and a binder, and its raw materials are calculated in parts by mass:

85-94 parts of stainless steel metal powder;

Binder system 6-15 parts;

The composition of the binder system includes:

Wherein, the stainless steel metal powder adopts 500 mesh, no agglomeration, and the stainless steel material grade is 316L powdery solid.

Further, the particle shape of the stainless steel metal powder is spherical.

The invention further discloses that the material used for metal low-temperature 3D printing is prepared by the following method:

S1) Put 316L stainless steel metal powder, epoxidized soybean oil EOS, paraffin PW, and stearic acid SA into an internal mixer, and heat and blend at 60°C to 80°C;

S2) Put in ethylene-vinyl acetate copolymer EVA, polypropylene PP, polyoxymethylene POM, and polylactic acid PLA for blending in sequence, wherein the feeding interval of each material is P1, and the temperature of the mixing room is 110 ° C ~ 130 ° C, The rotor speed is 60r/min～80r/min, and the mixing time is P2, to obtain the mixed material for metal low temperature 3D printing;

S3) crushing the mixed material obtained in step S2) to obtain spherical pellets with a uniform size and an average diameter of 3 mm;

S4) Dry the spherical pellets obtained in step S3) in a drying oven at an ambient temperature of 40° C. to 50° C. for 2 to 4 hours to obtain material particles for metal low-temperature 3D printing.

Further, in the step S2 of the material preparation method, the feeding interval P1 of each material is 2 minutes, and the mixing time P2 is 25 minutes to 35 minutes.

The invention also discloses a metal low-temperature 3D printing method, which includes:

1) using the method described in any one of claims 3-4 to prepare material particles for metal low-temperature 3D printing;

2) The powder-feeding 3D printer is used to transport and melt the material particles in the melt, and then spray through the nozzle, and print out the three-dimensional green body through layer-by-layer accumulation. During the process, the melt temperature is 160°C to 180°C. The printing platform temperature is 40℃～70℃;

3) Degreasing the three-dimensional green body. The degreasing process is to put the green body into a high-temperature sintering furnace and raise the temperature to 250°C at a slow speed of 0.1°C/min, and keep it warm for 48 hours to completely remove the metal green body. Binders in the body;

4) Continue sintering the green body to obtain 3D printed stainless steel metal products.

Further, in the step 2), after the material particles enter the head of the 3D printer, they are heated and melted to obtain a polymer melt, and then pushed into the melt cavity of the nozzle by the screw, and the polymer melt is sprayed from the nozzle driven by back pressure. out.

Further, in the step 3), the debinding and sintering are carried out in a vacuum environment.

Further, in the step 3), the degreasing process puts the green body into a high-temperature sintering furnace and slowly raises the temperature to 250°C at 0.1°C/min, and keeps the temperature for 48 hours to completely remove the bond in the metal green body agent.

Further, in the step 4), the sintering is carried out by gradually raising the temperature, and the sintering temperature is between 1000°C and 1400°C.

Further, in the step 4), the sintered metal product is naturally cooled to room temperature in the furnace.

Beneficial effects of the present invention: the formulation uses stainless steel powder as the matrix, and an appropriate amount of binder is added therein. When the binder melts, the stainless steel powder obtains fluidity, and the metal body is obtained by printing layer by layer through the powder feeding 3D printer head, Metal products are obtained through degreasing and sintering; the invention adopts low-temperature printing, the printer head has the characteristics of low unit cost and customization, the printing method is practical, and the final metal products have high precision and good quality.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some of the present invention. Embodiments, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

Fig. 1 is a process flow diagram of a metal low-temperature 3D printing method according to an embodiment of the present invention;

Fig. 2 is a structural schematic diagram of a 3D printer head according to an embodiment of the present invention;

Fig. 3 is the tensile strength variation curve of the metal products obtained by different metal contents;

Fig. 4 is the bending resistance variation curve of the metal products obtained by different metal contents;

Fig. 5 is the impact displacement change curve of metal products obtained with different metal contents.

In the picture:

1. Pressure holding chamber; 2. Solenoid valve; 3. Nozzle; 4. Melt chamber; 5. Stop valve needle; 6. Nozzle.

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention belong to the protection scope of the present invention.

A material for low-temperature 3D printing of metals according to an embodiment of the present invention, the material is composed of stainless steel metal powder and a binder, and its raw materials are calculated in parts by mass:

85-94 parts of stainless steel metal powder;

Binder system 6-15 parts;

The composition of the binder system includes:

Wherein, the stainless steel metal powder is a powdery solid with a particle size of 500 mesh, no agglomeration, and the grade of stainless steel material is 316L, and the particle shape of the stainless steel metal powder is spherical.

Example 1

Weigh each raw material according to the formula in Table 1, 100 parts in total according to the mass of the stainless steel metal powder and binder system.

316L stainless steel metal powder 85 copies PW 3.6 ESO 0.9 EVA 3.3 PP 2.7 POM 2.4 SA 0.3 PLA 1.8

Materials for low-temperature 3D printing of metals prepared by the following methods:

S1) Put 316L stainless steel metal powder, epoxidized soybean oil EOS, paraffin PW, and stearic acid SA into an internal mixer, and heat and blend at 60°C to 80°C;

S2) Put in ethylene-vinyl acetate copolymer EVA, polypropylene PP, polyoxymethylene POM, and polylactic acid PLA for blending in sequence. The feeding interval of each material is 2 minutes, and the temperature of the mixing room is 110 ° C ~ 130 ° C. The rotor speed is 60r/min-80r/min, and the mixing time is 25min-35min to obtain a mixture for metal low-temperature 3D printing;

S3) Put the mixture obtained in step S2) into a pulverizer for pulverization after cooling, to obtain spherical pellets with uniform size and average diameter of 3 mm;

S4) Dry the spherical pellets obtained in step S3) in a drying oven at an ambient temperature of 40° C. to 50° C. for 2 to 4 hours to obtain pellets for metal low-temperature 3D printing.

The above obtained pellets are used for metal low temperature 3D printing, as shown in Figure 1, the method includes:

1) Using the method described above to prepare pellets for low-temperature 3D printing of metals; put the pellets into a 3D printer for printing.

2) Using a powder-feeding 3D printer, the material particles are placed into the melt from the feed port, transported and melted in the melt, and then sprayed through the nozzle, and the three-dimensional green body is printed out through layer-by-layer accumulation. The melt temperature is 160°C-180°C, and the printing platform temperature is 40°C-70°C.

In order to facilitate the understanding of the above-mentioned technical solution of the present invention, the above-mentioned technical solution of the present invention will be described in detail below through a specific usage mode.

Specifically, its working principle is shown in FIG. 2 . The DC motor drives the screw to rotate, conveying the pellets into the hot runner, pushed in by the screw after heating, enters the pressure holding chamber 1 through the runner, and then enters the melt chamber 4 above the nozzle 6. Good airtightness in the melt cavity 4 ensures continuous and stable back pressure of the melt.

The electromagnet in the solenoid valve 2 is driven by the square wave pulse signal. On the rising edge of the signal, it overcomes the spring force and drives the shut-off valve needle 5 to quickly impact downwards to close the nozzle 6; when the rising edge of the signal ends, the falling edge begins to appear. The magnetic force of the electromagnet decreases rapidly, and the spring drives the shut-off valve needle 5 to bounce back to the initial position. At this time, the melt is driven by the back pressure and is quickly ejected from the nozzle 3.

When the ejection volume meets the expected demand and complete molten droplets are formed, the solenoid valve 2 closes the nozzle for the second time, and the molten droplets outside the nozzle 3 break away from the nozzle under the action of gravity and inertial force, and are injected on the flat plate, and are rapidly cooled and solidified , forming a droplet.

So far, the spraying device has completed a droplet cycle. The screw rotates stably, conveys the material at a uniform speed, and establishes a steadily increasing back pressure. The electromagnet repeatedly impacts and rebounds, and periodically releases the back pressure increase and the injection melt increase.

Among them, the temperature of the head is controlled at 180°C, and the three-dimensional body is finally printed.

3) Degreasing the three-dimensional green body. The degreasing process is to put the green body into a high-temperature sintering furnace at a slow rate of 0.1°C/min to 250°C, and keep it warm for 48 hours to completely remove the metal green body binder in.

4) Continue to sinter the green body by vacuum sintering, and the degreasing sintering is carried out by gradually increasing the temperature, the sintering temperature is between 1000°C and 1400°C, and the duration is 6-8 hours. The sintered metal product is naturally cooled to room temperature in the furnace.

5) Obtain 3D printed stainless steel metal products and test them.

Example 2

Weigh each raw material according to the formula in Table 1, 100 parts in total according to the mass of the stainless steel metal powder and binder system.

316L stainless steel metal powder 90 copies PW 2.4 ESO 0.6 EVA 2.2 PP 1.8 POM 1.6 SA 0.2 PLA 1.2

1) According to the material ratio in the table, according to the mixing method of Example 1, the material for metal temperature 3D printing is obtained;

2) Using a powder-feeding 3D printer, the material particles are placed into the melt from the feed port, transported and melted in the melt, and then sprayed through the nozzle, and the three-dimensional green body is printed out through layer-by-layer accumulation. The melt temperature is 160°C-180°C, and the printing platform temperature is 40°C-70°C;

3) Degreasing the three-dimensional green body. The degreasing process is to put the green body into a high-temperature sintering furnace and raise the temperature to 250°C at a slow speed of 0.1°C/min, and keep it warm for 48 hours to completely remove the metal green body. Binders in the body;

4) Continue to sinter the green body by vacuum sintering, and the degreasing sintering is carried out by gradually increasing the temperature, the sintering temperature is between 1000°C and 1400°C, and the duration is 6-8 hours. Naturally cool the sintered metal product to room temperature in the furnace;

5) Obtain 3D printed stainless steel metal products and test them.

Example 3

Weigh each raw material according to the formula in Table 1, 100 parts in total according to the mass of the stainless steel metal powder and binder system.

316L stainless steel metal powder 92 copies PW 1.92 ESO 0.48 EVA 1.76 PP 1.44 POM 1.28 SA 0.16 PLA 0.96

1) According to the material ratio in the table, according to the mixing method of Example 1, the material for metal temperature 3D printing is obtained;

2) Using a powder-feeding 3D printer, the material particles are placed into the melt from the feed port, transported and melted in the melt, and then sprayed through the nozzle, and the three-dimensional green body is printed out through layer-by-layer accumulation. The melt temperature is 160°C-180°C, and the printing platform temperature is 40°C-70°C;

3) Degreasing the three-dimensional green body. The degreasing process is to put the green body into a high-temperature sintering furnace and raise the temperature to 250°C at a slow speed of 0.1°C/min, and keep it warm for 48 hours to completely remove the metal green body. Binders in the body;

4) Continue to sinter the green body by vacuum sintering, and the degreasing sintering is carried out by gradually increasing the temperature, the sintering temperature is between 1000°C and 1400°C, and the duration is 6-8 hours. Naturally cool the sintered metal product to room temperature in the furnace;

5) Obtain 3D printed stainless steel metal products and test them.

Example 4

Weigh each raw material according to the formula in Table 1, 100 parts in total according to the mass of the stainless steel metal powder and binder system.

316L stainless steel metal powder 94 copies PW 1.44 ESO 0.36 EVA 1.32 PP 1.08 POM 0.96 SA 0.12 PLA 0.72

1) According to the material ratio in the table, according to the mixing method of Example 1, the material for metal temperature 3D printing is obtained;

2) Using a powder-feeding 3D printer, the material particles are placed into the melt from the feed port, transported and melted in the melt, and then sprayed through the nozzle, and the three-dimensional green body is printed out through layer-by-layer accumulation. The melt temperature is 160°C-180°C, and the printing platform temperature is 40°C-70°C;

3) Degreasing the three-dimensional green body. The degreasing process is to put the green body into a high-temperature sintering furnace at a slow rate of 0.1°C/min to 250°C, and keep it warm for 48 hours to completely remove the metal green body binder in

4) Continue to sinter the green body by vacuum sintering, and the degreasing sintering is carried out by gradually increasing the temperature, the sintering temperature is between 1000°C and 1400°C, and the duration is 6-8 hours. Naturally cool the sintered metal product to room temperature in the furnace;

5) Obtain 3D printed stainless steel metal products and test them.

The metal product test result obtained to four groups of embodiments is shown in the following table:

Figures 3, 4, and 5 are graphs showing the variation of various properties of metal products with metal content.

Wherein Fig. 3 is the tensile strength variation curve of the metal products obtained by different metal contents; Fig. 4 is the bending resistance variation curve of the metal products obtained by different metal contents; Fig. 5 is the impact displacement variation curve of the metal products obtained by different metal contents .

It can be seen from Figures 3-5 that the metal low-temperature 3D printing materials prepared by the above examples are used for 3D metal low-temperature printing, and the obtained 3D printed stainless steel metal products have good performance. With the increase of metal content, the tensile strength and resistance The bending force increases, while the impact displacement decreases with the increase of metal content. At the same time, the feasibility of metal low-temperature 3D printing is verified through the above examples, and the obtained metal products have high precision and good quality.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (10)

1. A material for metal low-temperature 3D printing, characterized in that the material is composed of stainless steel metal powder and a binder, and its raw materials are calculated in parts by mass: 85-94 parts of stainless steel metal powder; Binder system 6-15 parts; The composition of the binder system includes: Wherein, the stainless steel metal powder adopts 500 mesh and the powdery solid of stainless steel grade is 316L. 2. The material for low-temperature 3D printing of metals according to claim 1, wherein the particle shape of the stainless steel metal powder is spherical. 3. The material for metal low-temperature 3D printing according to claim 2, wherein the material is prepared by the following method: S1) Put 316L stainless steel metal powder, epoxidized soybean oil EOS, paraffin PW, and stearic acid SA into an internal mixer, and heat and blend at 60°C to 80°C; S2) Put in ethylene-vinyl acetate copolymer EVA, polypropylene PP, polyoxymethylene POM, and polylactic acid PLA for blending in sequence, wherein the feeding interval of each material is P1, and the temperature of the mixing room is 110 ° C ~ 130 ° C, The rotor speed is 60r/min～80r/min, and the mixing time is P2, to obtain the mixed material for metal low temperature 3D printing; S3) crushing the mixed material obtained in step S2) to obtain spherical pellets with a uniform size and an average diameter of 3 mm; S4) Dry the spherical pellets obtained in step S3) in a drying oven at an ambient temperature of 40° C. to 50° C. for 2 to 4 hours to obtain material particles for metal low-temperature 3D printing. 4. The material for metal low temperature 3D printing according to claim 3, characterized in that, In the step S2 of the material preparation method, the feeding interval P1 of each material is 2 minutes, and the mixing time P2 is 25 minutes to 35 minutes. 5. A metal low temperature 3D printing method, characterized in that the method comprises: 1) using the method described in any one of claims 3-4 to prepare material particles for metal low-temperature 3D printing; 2) The powder-feeding 3D printer is used to transport and melt the material particles in the melt, and then spray through the nozzle, and print out the three-dimensional green body through layer-by-layer accumulation. During the process, the melt temperature is 160°C to 180°C. The printing platform temperature is 40℃～70℃; 3) Degreasing the three-dimensional green body. The degreasing process is to put the green body into a high-temperature sintering furnace and raise the temperature to 250°C at a slow speed of 0.1°C/min, and keep it warm for 48 hours to completely remove the metal green body. Binders in the body; 4) Continue sintering the green body to obtain 3D printed stainless steel metal products. 6. The metal low-temperature 3D printing method according to claim 5, characterized in that, in the step 2), after the material particles enter the 3D printer head, they are heated and melted to obtain a polymer melt, and then pushed into the nozzle by a screw. In the melt chamber, the polymer melt is ejected from the nozzle driven by back pressure. 7. The metal low-temperature 3D printing method according to claim 5, characterized in that, in the step 3), the degreasing and sintering are carried out in a vacuum environment. 8. The metal low-temperature 3D printing method according to claim 7, characterized in that, in the step 3), the degreasing process puts the embryo into a high-temperature sintering furnace and slowly raises the temperature to 250°C at 0.1°C/min, And keep warm for 48 hours to completely remove the binder in the metal embryo body. 9. The metal low-temperature 3D printing method according to claim 7, characterized in that, in the step 4), the sintering is carried out by gradually increasing the temperature, and the sintering temperature is between 1000°C and 1400°C. 10. The metal low-temperature 3D printing method according to claim 9, characterized in that in step 4), the sintered metal product is naturally cooled to room temperature in a furnace.