RU2802607C1 - Method for additive manufacturing of metal, ceramic or composite products - Google Patents

Abstract

FIELD: powder metallurgy.

SUBSTANCE: methods for layer-by-layer synthesis of complex metal products from powder materials. It can be used for the manufacture of products for the aviation, automotive, shipbuilding industries. The method for additive production of metal, ceramic or composite products includes layer-by-layer application by supplying powder material to the zone in front of the leveling device, while in the process of applying each layer, a vibration effect on the powder material is carried out. The powder material is fed through multi-nozzle piezoelectric printheads with a layer thickness of 10 to 100 µm. A self-hardening binder or binder, followed by curing to form a blank is applied to the specified sections of the layer. After that, unbound powder material is removed and the blank is sintered or impregnated with metal.

EFFECT: obtaining products of complex configuration with high accuracy.

12 cl, 1 dwg, 2 ex

Description

The invention relates to technological processes in metallurgy and powder metallurgy, namely to the technology of layer-by-layer synthesis of complex metal products from powder materials, using powder from at least one metal and at least one binder. The invention can be used in the manufacture of metal, metal-ceramic, ceramic and composite products using the additive manufacturing method (layer-by-layer synthesis) in various branches of mechanical engineering, for example, for the production of metal products for the aviation, automotive, shipbuilding and other industries with high precision and surface quality.

A method of manufacturing products from metal powders RU 2713254 C1, 02/04/2020 is known from the prior art, according to which a mixture of metal powder with a binder is prepared in the form of a paste in the ratio of 78-82% metal powder, 18-22% binder. Liquid glass is used as a binder, and cast iron shavings are used as metal powder. The workpiece is formed according to a digital model layer by layer using extrusion printing on a 3D printer. The resulting workpiece is sintered and simultaneously impregnated with bronze. Products are manufactured using pressless powder sintering.

The disadvantages of the known method include low productivity and low accuracy of the resulting products, which is due to the extrusion printing technology used.

The prior art knows a method for manufacturing bulk products from a powder composition (RU 95110182 A1, 04/10/1997), including sequential layer-by-layer placement of a powder composition in a machine for selective laser synthesis (hereinafter referred to as SLS), processing of each layer with laser radiation (hereinafter referred to as LR) along a given contour and removing the resulting product from the machine with removal of the powder composition that did not take part in the formation of the volumetric product.

The disadvantages of the known technical solution include the fact that the method is characterized by large and sharp temperature changes in the sintering zone, which leads to the appearance of internal stresses in the material, warping, cracking and a decrease in the strength and quality of the model.

A method for manufacturing bulk products from powder compositions RU 2217265 C2, 11/27/2003 is known from the prior art. The method includes placing a powder composition in a machine for laser synthesis of volumetric products and laser processing of a layer-by-layer formed volumetric product, removing it from the machine with removing the powder composition that did not take part in the formation of the volumetric product. As a powder composition, sifted powder mixtures based on nickel-aluminium, nickel-titanium, aluminum and titanium are used for self-propagating high-temperature synthesis, in accordance with the stoichiometric composition. After removing the products from the machine and removing the powder composition that did not take part in the formation, they are infiltrated with polyvinyl acetate or epoxy glue, followed by drying.

The disadvantages of the known technical solution include low productivity, as well as the inability to produce products of complex shapes. These disadvantages are due to the technology used for laser synthesis of bulk products using selective laser sintering. This decision was made for the sinking.

The task to which the present invention is aimed is to eliminate the shortcomings of the known level of technology, as well as to increase the availability of additive technologies for the production of metal products for various fields of industry. In addition, the goal is to eliminate traditional operations in the production of small-scale, single products, as well as product prototypes, by manufacturing products directly from metal powder using layer-by-layer synthesis, which will make it possible to obtain products of complex shapes and reduce production time.

The technical result achieved when using the claimed invention is to increase the complexity of products through the use of additive manufacturing technology and layer-by-layer synthesis, increasing the accuracy of the product through the use of multi-nozzle piezoelectric print heads with an extremely small droplet diameter, which allows the formation of a layer with a thickness of 10 to 200 microns , and also at the same time, by reducing the force of internal friction in the applied layers of powder materials, due to the vibration effect in the applied material, to ensure an increase in the accuracy of the product, its strength and uniformity of laying of the powder material.

In addition, another advantage of the proposed method compared to other additive processing methods is that the molding process occurs at room temperature and atmosphere (pressure), which avoids problems associated with oxidation, residual stress, segregation of elements and phase transitions, unrelated The powder is easily processed, which eliminates the need for expensive sealed chambers for vacuum or inerting the working volume of the machine.

Another important advantage compared to known technical solutions is that when implementing the proposed method for the additive production of metal, metal-ceramic, ceramic and composite products from powder materials, the creation of supporting structures necessary for other layer-by-layer synthesis technologies is not required.

The essence of the claimed invention lies in the fact that the method of additive production of metal, metal-ceramic, ceramic and composite products includes:

a. applying a layer of powder material to the working surface;

b. bonding the powder material in areas of the applied powder layer;

c. lowering the working platform by the amount of the layer;

d repeating stages “a”, “b” and “c” many times until a metal (cermet, ceramic, composite) product is obtained from a cured powder material and a binder component;

in this case, the powder material is bonded with a liquid binder supplied to the areas of the applied powder layer; the powder material is selected from the group of metals, metal-ceramics, ceramics, composite materials and mixtures thereof; in the process of applying each layer, vibration is applied to the powder material at the place where the powder is leveled with a leveling device; The powder for applying a new layer is supplied from the supply device to the area of the working platform in front of the leveling device, the thickness of the powder layer ranges from 10 to 200 microns; the binder material is fed through multi-nozzle piezoelectric print heads; after which, if necessary, in accordance with the type of binder used, the final cure of the binder is carried out by heating the entire working volume together with the workpieces and holding for the time necessary to ensure curing, or the final cure is carried out by gas purge or ultrasonic influence or microwave influence or electromagnetic influence , ensuring the hardening of the binder; or they use self-hardening binders (for example, molten wax, cyanoacrylates, etc.), then remove and clean the workpiece from the working volume, burn out the binder material from the workpieces, sinter the workpieces into a monolithic product or impregnate them with metal (infiltration method).

In addition, the essence of the technical solution of the claimed invention is that the average particle diameter of the powder material, determined using sieve analysis, is from 1 to 100 μm, preferably from 5 to 40 μm; the device for applying the binder is located at a distance of no more than 3 mm from the layer being treated; the vibration effect is carried out from the vibration of the feed mechanism of the mixture feeding and leveling devices; the vibration effect is carried out by an ultrasonic or electromagnetic vibrator located on the leveling device; the supply of powder material for applying a new layer from the feeder is carried out evenly, with the amount of powder per unit time necessary and sufficient to form a layer; the supply of powder for applying a new layer from the feeder is carried out discretely, in portions with the amount of powder necessary and sufficient to form a layer; the content of the binder material is from 20 to 100% of the powder saturation level (the percentage of filling of the volume of voids in the powder material with the binder material); The size (volume) of a droplet of the binding component supplied through multi-nozzle piezoelectric print heads ranges from 1 to 200 pl, the droplet distribution density (print resolution) is in the range of 100-900 dots per inch (dpi).

In addition, the essence of the technical solution of the claimed invention lies in the fact that after applying the binder material on each layer, the surface of the powder material is additionally subjected to thermal influence, heating the entire working volume along with the workpieces for final curing of the binder is carried out to a temperature of 40-500°C. Burning is carried out at temperatures from 300 to 1000°C, depending on the type of binder material.

Thus, when using the proposed method, the complexity of products increases due to the use of additive manufacturing technology and layer-by-layer synthesis. The accuracy of the product is increased through the use of multi-nozzle piezoelectric print heads with an extremely small droplet diameter, which allows the application of binder material layer thicknesses of up to 10 microns. The use of the proposed method provides the ability to produce metal products of any configuration in the shortest possible time, which significantly speeds up the introduction of the product to the market, increases the individualization of production and the speed of response to new needs of markets and mechanical engineering. In addition, the claimed set of additive manufacturing operations makes it possible to increase the productivity and quality of layer application by reducing the force of internal friction, namely due to the vibration effect in the applied material, which in turn also increases the accuracy of the product, its strength and the uniformity of laying of the powder material.

Also, by reducing internal friction, the rate of application of powder materials increases, which leads to increased productivity of the technological process as a whole.

The essence of the proposed invention is illustrated by the following description and the accompanying illustration, which shows a diagram of the implementation of a method for the additive production of removable casting models from powder materials, where

1 - powder material

2 - leveling device

3 - working platform

4 - casting model

5 - new layer

6 - working chamber

7 - unapproved powder

8 - print head

9 - binding component

10 - adding a binder component

11 - metal for impregnation (infiltration)

With reference to FIG. arrows a, b, c show the processes of the proposed method: applying a layer of powder material 1 to the working platform 2, introducing a binder material 9 into program-defined areas of the applied powder layer to bind powder particles in selected areas, lowering the working platform 3 by the amount of the layer, respectively. These steps are repeated many times until a workpiece of a metal, metal-ceramic, ceramic or composite product is obtained from a cured powder material and a binder component.

Powder material 1 is selected from the group containing metals, metal-ceramics, ceramics, and composites. The average particle diameter of the powder material, determined by sieve analysis, is from 1 to 100 μm, preferably from 5 to 40 μm. Powder material or mixtures thereof are applied to the working platform 3.

Then, to bind the powder material together, a liquid binding component 9 is supplied to the areas of the applied layer of powder material. The binder is fed through multi-nozzle piezoelectric print heads 8 (the application process is shown in position 10) with a layer thickness of 10 to 200 microns. In this case, the print heads are placed at a distance of no more than 3 mm from the layer being processed.

The size (volume) of a droplet of the binder component supplied through multi-nozzle piezoelectric print heads ranges from 1 to 200pl, the droplet distribution density (print resolution) is in the range of 100-900 dots per inch (dpi).

The binder content ranges from 20 to 100% of the saturation level (percentage of void volume in the powder material filled with binder material).

The binding component is selected depending on the type of powder material (metal, non-metal, mixture): carnauba wax, paraffin wax (paraffin wax), polyethylene wax (PE WAX) or an acid-based binder, where the binding of the powder is controlled by the reaction of the acid-based binder metal salts, where the bond between powder particles can be formed as a result of salt recrystallization or salt substitution reaction, or a binder (solvent-based or water-based) that creates a desired structure after evaporation of the solvent (for example, polyvinyl alcohol), as well as self-hardening binders in air ( for example cyanoacrylates).

The layer-by-layer application of the powder material on the working surface is repeated, and the powder is supplied to the zone in front of the leveling device 2. The supply of the powder material is carried out evenly with the amount of powder per unit of time necessary and sufficient for the formation of a layer or carried out discretely, portionwise with the amount of powder necessary and sufficient for the formation layer.

During the application of each layer, a vibration effect is applied to the powder material to the depth of the applied layer in the place where the powder is leveled by leveling device 2. The vibration effect is carried out from the vibration of the feed mechanism of the powder feeding and leveling devices or from an ultrasonic (electromagnetic) vibrator located on the leveling device.

After applying the binder material, it is cured (if a self-hardening binder is not used). To cure the binder component by heat, each layer of the surface of the powder material is exposed to heat. The entire working volume, together with the workpieces, is heated to a temperature of 40-500°C. Other known methods for curing the binder may be used to cure the binder, such as gas purge, ultrasonic, microwave, or electromagnetic effects.

After curing, the workpiece is removed from the working volume, cleaned, and the binder material is burned out of the workpiece to remove unbound powder. Burning is carried out at temperatures from 300 to 1000°C, depending on the type of binder material.

At the final stage, the workpieces are sintered or impregnated with metal (infiltration method) into a monolithic product.

To implement the invention, known equipment is used, for example, a BPrint M-Maxi or BPrint M-Mini installation.

The following shows examples of implementation of the proposed method.

Example No. 1

Niresist powder material was used to create the pump impeller. The average particle diameter of the powder material is 20 microns. During the experiment, niresist was applied to the working platform of a 3D printer in a layer 5 diameters of powder material particles. Then 1% of the binder by weight of the powder was added. Polyethylene wax (PE WAX) was used as a binder. The binder component was fed through multi-nozzle piezoelectric print heads with a volume of each drop of 30 pl, with a drop distribution density of 600 dpi, while the print head was located at a distance of 2 mm from the processed layer. The void filling coefficient was 0.8. Then 500 layers were applied sequentially, and with each new layer a vibration effect was applied to a depth of 5 particle diameters of the powder material. The powder material was supplied to the area in front of the leveling device, and the vibration effect was carried out by an ultrasonic vibrator located on the leveling device. Heating for curing was not performed for this binder; burning was carried out at a temperature of 500°C for 3 hours. Sintering was carried out at a temperature of 1200°C for 2 hours. The resulting complex product - a pump impeller - is of high quality; its production during the experiment took 12 hours.

Example No. 2

AlSil0Mg powder material was used to create a piston for an unmanned aerial vehicle. The average particle diameter of the powder material is 50 microns. During the experiment, AlSil0Mg was applied to the working platform of a 3D printer in a layer 2 diameters of powder material particles. Then 1.2% of the binder by weight of the powder was added. An aqueous solution of polyvinyl alcohol was used as a binder. The binder component was fed through multi-nozzle piezoelectric print heads with a volume of each drop of 30 pl, with a drop distribution density of 650 dpi, while the print head was located at a distance of 2 mm from the processed layer. The void filling coefficient was 0.65. Then 1300 layers were applied sequentially, and with each new layer a vibration effect was applied to a depth of 2 particle diameters of the powder material. The powder material was supplied to the area in front of the leveling device, and the vibration effect was carried out by an electromagnetic vibrator located on the leveling device. Heating for curing for this binder was carried out at a temperature of 100°C, burning was carried out in two stages, 1st at a temperature of 230°C for 3 hours, then at a temperature of 350°C for 2 hours. Sintering was carried out at a temperature of 550°C for 3 hours. The resulting complex product - a piston for an unmanned aerial vehicle - is of high quality; its production during the experiment took 18 hours.

Thus, the claimed invention, a method for the additive production of removable casting models from powder materials, allows increasing the complexity of products through the use of additive manufacturing technology and layer-by-layer synthesis, increasing the accuracy of the product through the use of multi-nozzle piezoelectric print heads with an extremely small droplet diameter, which allows the formation of a thick layer from 10 to 100 microns, and also by reducing the force of internal friction in the applied layers of powder materials, due to the vibration effect in the applied material, in turn, also increasing the accuracy of the product, its strength and uniformity of laying of the powder material.

Claims (12)

1. A method for the additive production of metal, ceramic or composite products, including layer-by-layer application of powder material to a working surface, applying a binder component to specified areas of a layer of powder material, lowering the working platform by the amount of the layer, repeating the process until the specified shape of the product is formed, characterized in that the powder material is fed into the zone in front of the leveling device, while in the process of applying each layer, vibration is applied to the powder material in the area of its leveling; a self-hardening binder or binder is applied through multi-nozzle piezoelectric print heads with a layer thickness of 10 to 100 microns, followed by curing with forming a preform, removing unbound powder material, and then sintering or impregnating the preform with metal to produce a monolithic product. 2. The method according to claim 1, characterized in that the binder is selected from the group consisting of carnauba wax, paraffin wax, polyethylene wax, acid-based binder, metal salt binder and water-based binder. 3. The method according to claim 1, characterized in that a powder material with a particle diameter of 1 to 100 microns, preferably from 5 to 40 microns, is used. 4. The method according to claim 1, characterized in that multi-nozzle piezoelectric print heads are located at a distance of no more than 3 mm from the processed layer of powder material. 5. The method according to claim 1, characterized in that the vibration effect is carried out by vibration of the feeding and/or leveling device or an ultrasonic vibrator located on the leveling device. 6. The method according to claim 1, characterized in that the supply of powder material is carried out evenly with the amount per unit time necessary and sufficient to form the layer. 7. The method according to claim 1, characterized in that the supply of powder material is carried out discretely in portions with the amount necessary to form a layer. 8. The method according to claim 1, characterized in that the binder content is from 20 to 100% of the saturation level. 9. The method according to claim 1, characterized in that the droplet size of the binder component is from 1 to 200 pl, the droplet distribution density is in the range of 100-900 dpi. 10. The method according to claim 1, characterized in that the binder is cured by applying heat to the surface of the powder material of each layer. 11. The method according to claim 1, characterized in that for the final curing of the binder, the workpiece is heated to a temperature of 40-500°C. 12. The method according to claim 1, characterized in that the unbound powder material is removed by burning the binder at a temperature of 300 to 1000°C.