METHOD FOR MANUFACTURING A PART FROM POWDER

Abstract

The method for manufacturing a part from powder relates to the electrical engineering field. In particular, to the processing of materials and the production of flat or three-dimensional products from both metal and plastic, ceramics, metal-plastic and metal-ceramics using microwave heating. The purpose is a method that uses the means of heating due to microwave radiation to sinter or melt the materials, both ceramic and plastic materials and metal powders. The method includes the creation of a microwave field within the operating chamber with a microwave radiation power of 100 W to 150 MW and a frequency of 1 GHz to 10 THz, depending on the physical properties of the powder, the dimensions, degree of accuracy and complexity of the geometric shapes of the sintered (melted) part, the development in the created microwave field of zones with increased intensity of microwave radiation, in which the powder heating zones are developed corresponding to the zones with increased intensity of microwave radiation, which shape follows the point or flat cutting (section) or the spatial pattern of the part, with the intensity of microwave radiation being sufficient for the thermal energy release to heat the powder to its sintering/melting temperature, taking into account the initial temperature of the powder, and where the powder is sintered or melted to produce the part by means of the released thermal energy in the heating zones of the powder.

Claims

1. A method of manufacturing a part from powder comprising placement of the powder with a particle size of maximum 1 mm in the air, gas, liquid or solid transit medium with the microwave field, which are located in the operating chamber, the impact on the powder by zones of increased microwave field intensity, which is characterized in that the method includes creation of a microwave field within the operating chamber with a microwave radiation power of 100 W to 150 MW and a frequency of 1 GHz to 10 THz, depending on the physical properties of the powder, the dimensions, degree of accuracy and complexity of the geometric shapes of the sintered part, the development in the created microwave field of zones with increased intensity of microwave radiation, in which the powder heating zones are developed corresponding to the zones with increased intensity of microwave radiation, which shape follows the point or flat cutting or the spatial pattern of the part, with the intensity of microwave radiation being sufficient for the thermal energy release to heat the powder to its sintering temperature, taking into account the initial temperature of the powder, and where the powder is sintered or melted to produce the part by means of the released thermal energy in the heating zones of the powder.

2. A method of manufacturing a part from powder according to claim 1, characterized in that the thermal energy sufficient to heat the powder to the sintering temperature, is released as a result of microwave radiation absorption in high intensity zones, which location corresponds to a volumetric holographic image of the part and is set by the interference matrix representing a irradiated microwave radiation plate with the programmed holographic interference image of the produced part placed in the operating chamber relative to the microwave radiation source so that microwave radiation radiates the interference matrix, or passes through it.

3. A method of manufacturing a part from powder according to claim 1, characterized in that the thermal energy is generated by causing in a microwave breakdown in the determined area being the heating zone of the powder, which occurs when the intensity of the microwave field in said zone exceeds the critical value due to the connection of a virtual resonator to said zone by focusing ionizing light or laser flux by a lens, or a solid resonator, with at least one resonator being moved in space over the respective powder layer creating the powder heating zones, where the powder is sintered or melted in points corresponding to the geometric place of the points of the determined two-dimensional layer of the three-dimensional part.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0037] The method is illustrated by drawings that do not cover all possible options of the method implementation.

[0038] FIG. 1 shows a sintering/melting apparatus, which can be applied to implement the proposed method using a holographic three-dimensional image of the part;

[0039] FIG. 2 shows sintering/melting devices, which can be used to implement the proposed method by causing a microwave breakdown in the determined zone using a resonator;

[0040] FIG. 2a shows a device with a physical resonator on a carriage;

[0041] FIG. 2b shows a device with a virtual resonator on a carriage;

[0042] FIG. 2c shows a device with a virtual resonator with a deflecting optical system;

[0043] Below are examples of two implementation options, but they do not cover all possible implementation examples of this method.

[0044] Example 1. FIG. 1 shows a sintering/melting apparatus, which can be applied to implement the proposed method using a holographic three-dimensional image of the part.

INDUSTRIAL APPLICABILITY

[0045] The work is carried out as follows.

[0046] A chamber similar to a standard microwave oven for industrial or consumer heating is taken as an operating chamber (conventionally not shown), which uses microwave radiation depending on the scope of sintering, its physical properties and the complexity and accuracy of the manufactured part geometry. It has a source of (1) the required power of the microwave radiation and frequency inside that creates a microwave field of the pre-set intensity in the operating chamber, for example, a wave guide, a maser, a magnetron, a klystron, etc. Microwave radiation passes through the interference matrix (2) (containing a holographic interference image of the part), which is used to create a three-dimensional holographic image of the part in the operating chamber section with the transit medium with powder (3).

[0047] At that, no mechanical part, such as a 3D printer is required since the operating chamber does not need to be moved. By generating (3) a holographic three-dimensional image of the part in the form of zones with increased intensity of microwave radiation in the operating chamber (not only in the transit medium, but also in the powder) with the use of an interference pattern, the heating zones are established, where the powder is sintered/melted at the required points. The part is manufactured by creating a part from powder simultaneously in all heating zones of the powder, “manifesting” it in the powder mass. Then it is only required to release the produced part from the remains of the transit medium and excess powder.

[0048] Example 2. FIG. 2 shows sintering/melting devices, which can be used to implement the proposed method by causing a microwave breakdown in the determined zone using a resonator.

[0049] The work is carried out as follows.

[0050] At least one instance of the following components is placed in the operating chamber (filled with gas or liquid) (conventionally not shown): a hopper feeder (4), which is a powder source for the part synthesis, a (5) powder filling-laying carriage for the powder supply and laying (3) into the operating hopper (6), an operating hopper (6) with a mobile platform (7), which can move the powder and the product (8) in the vertical direction, as well as a carriage for resonator connection (9) (see FIGS. 2a, b) to the powder surface and the microwave radiation source (a wave guide, an antenna, a magnetron, etc.) (1). Produced part (8). Microwave breakdown zone (10). Resonator (11).

[0051] Having received a portion of powder from the hopper feeder (4) the filling-laying carriage (5) lays it out in a determined layer on a mobile platform (7) in the operating hopper (6).

[0052] The operating chamber shall be filled with a microwave field (continuously or in pulse mode). The perfect configuration of the microwave field is when a uniform microwave field is created over the entire surface of the top powder layer in the operating chamber, or when a microwave field is created in the operating chamber above the top powder layer (3) only in the area of the resonator (11) and breakdown (10).

[0053] FIG. 2a shows a rod as a resonator (11), which is fixed to the mobile resonator supply carriage (9), the fastening is shown conventionally, the breakdown zone (10) in the case of a solid resonator is small and takes place between the end of the resonator (11) (see FIG. 2a) and the part (8).

[0054] An item of a special shape can be used as a resonator (11), which geometric characteristics are calculated and depend on the wave length of the used electromagnetic (microwave) radiation (usually a rod or a split ring, etc.), fixed on a carriage (9) providing for independent movement of the resonator along three axes in order to bring it to the surface of the laid powder layer in any place with the determined accuracy and to remove it from said surface (see FIG. 2a).

[0055] FIGS. 2b, c show cases when a virtual resonator (11) can be used as a resonator, which is a controlled ionized channel (ionic trace), brought by ionizing radiation to the transit medium filling the operating chamber (6). The ionizing beam emitter (12) can be a UV light source or a laser (see FIGS. 2b, c). In this case, the breakdown (10) occurs along the entire length of the ionizing beam exposed to the microwave field.

[0056] FIG. 2b shows the case when the ionizing beam emitter (12) is fastened on the resonator supply carriage (9) (which is shown conventionally), i. e., for example, a round laser is fixed on its mobile carriage (9), which movement is used to control the ionizing beam.

[0057] FIG. 2c shows the case where the ionizing beam can be controlled by deflecting it with a swinging mirror (13), and focused, for example, with the use of optical lenses (14).

[0058] Hereinafter all types of resonators are designated simply as a resonator (11).

[0059] As a result of supplying the resonator (11) to the required zone near the powder surface, the microwave field intensity in said zone at the end of the resonator (between the resonator (11) and the powder (3)) increases sharply, which leads to the appearance and development of a microwave breakdown of the transit medium, accompanied by the release of a large amount of heat providing for sintering/melting of the powder particles (3) in the transit medium in said zone. By placing the resonator (11) in the required places, the geometric location of the points of the powder sintering/melting zones is established. The aggregate of these points represents a flat section of the manufactured part in a specific layer.

[0060] After the sintering/melting process of the part layer is over, the platform (7) with the powder and the part in the operating hopper (6) is lowered, and the filling-laying carriage (5) applies a new powder layer from the hopper feeder (4), and then the process is repeated.

[0061] Movement of the resonator (11) with a microwave breakdown of the proposed process is similar to the movement of the electrode with an arc in electric arc welding. However, unlike the welding electrode, the resonator in the proposed method is not the main source of charged particles emission and is not exposed to increased wear, and the melted material is not transferred through an electric arc and is not sprayed out, which has a positive effect on the quality and strength of the resulting products.

[0062] An additional positive factor is the occurrence in the microwave breakdown zone (which is a kind of electric discharge) of the pinch effect based on the mutual attraction of parallel electric currents by Ampere forces, which, in its turn, provides additional mutual compression (compaction) of the powder particles in a plane perpendicular to the of current direction, resulting in a significant increase in the density and strength of the sintered/melted part in comparison with SLS/SLM/EBM methods.

[0063] The process will not be accompanied by heat convection either, since the powder will not be heated to the sintering/melting temperature in the neighboring zones, therefore, no “coat” will be formed.

[0064] The ability to control the microwave radiation power and the gap between the resonator and the powder surface enables to dynamically influence the dimensions of the microwave breakdown zone and, accordingly, the dimensions of the powder sintering/melting zone, which makes it possible to manufacture large and small elements of the part with a spot of various diameters without realigning the equipment. This provides for a multi-fold increase in the process productivity in comparison with the processes using a laser or an electron beam. This reason is that in contrast to the proposed method, the laser spot during focusing cannot be dynamically changed within a wide range.

[0065] The price of microwave radiation sources is at least two orders less than the price of lasers of the respective power, providing for the mass production of low-budget class devices (the power contour of the device is in general similar to household microwave ovens, while its mechanical part is similar to a standard FDM 3D printer), which will also contribute to the absence of harmful stray radiation.