CN101985176A - Preheating temperature controllable method for preparing heterogeneous material components based on SLS prototyping - Google Patents

Abstract

A preheating temperature controllable method for preparing heterogeneous material components based on selected laser sintering (SLS) prototyping comprises the following steps: 1) constructing a 3D model of the heterogeneous material components to be machined; 2) determining the change curve formed by the machining height directions and preheating temperature of the heterogeneous material components to be machined according to sintered density distribution of the heterogeneous material components to be machined along the height direction and the corresponding curve of the preheating temperature and the sintered density in an SLS prototyping machine under the condition of set laser power; and 3) inputting the 3D model into the SLS prototyping machine, machining and controlling the 3D model according to the change curve formed by the machining height directions and preheating temperature and machining the 3D model by layers in sequence according to the machining height to obtain the heterogeneous material components. The heterogeneous density variable material components can be machined by the method and the method has good practicability.

Description

Preparation method of non-homogeneous material parts with controllable preheating temperature based on SLS forming

technical field

The invention relates to parts manufacturing technology, in particular to a method for preparing parts made of heterogeneous materials.

Background technique

Rapid Prototyping (RP) technology originated in the United States in the late 1980s, and soon developed to Western Europe and Japan. It is a major breakthrough in the field of manufacturing technology for more than 20 years. Rapid prototyping technology is the technical integration of CAD, numerical control technology, laser technology, and material science and engineering. It can automatically and quickly materialize design ideas into prototypes with certain structures and functions or directly manufacture parts, so that product design can be carried out. Rapid evaluation and modification to respond to market demand and improve the competitiveness of enterprises; the emergence of rapid prototyping technology reflects the development trend of modern manufacturing technology itself and the significant impact of fierce market competition on the development of manufacturing technology.

Since the birth of rapid prototyping technology, a variety of technologies have been developed. At present, the more mature rapid prototyping technologies are as follows: three-dimensional printing, laminated entity manufacturing, fused deposition modeling, and selective laser sintering.

The emergence of the concept of Ideal Functional Material Components (IFMC) is another achievement of bionics. After long-term survival of the fittest, the functions and structures of many organisms in nature have reached an almost perfect level. Plants such as bamboo, for example, achieve the survival requirements of high strength and low weight in a heterogeneous form; while the existence of mesoscopic fine structures makes the bones of some animals have a negative Poisson's ratio, ensuring the flexibility requirements of the bones . Like this, it is designed and manufactured according to the best functional requirements of the parts. It is composed of homogeneous materials, gradient-changing tissue components, fine-structure materials distributed according to certain rules, and embedded devices to achieve the best material structure and part performance. The combined parts are ideal material parts. It is oriented to specific mechanical, thermal, electromagnetic and other aspects of gradient functions and intelligent performance requirements. In different areas, combined with preset geometric features, process characteristics and material properties of adjacent areas, from homogeneous materials and non-homogeneous materials Choose the most suitable structural material among homogeneous materials.

In fact, in nature, high-precision and self-assembled heterogeneous materials are very common, and gradient structures widely exist in various organisms and animals. Animal bones and teeth are perfect natural heterogeneous materials. The density of bone cells in the bones gradually increases from the inside to the outside. This gradient structure of spongy to compact bones is hard and strong rather than flexible, and has a good mechanical properties and support. It is impossible to process such non-homogeneous and variable-density materials using traditional processing methods.

Contents of the invention

In order to overcome the inadequacy that the existing part processing technology cannot process non-homogeneous variable-density material parts, the present invention provides a kind of non-homogeneous material with controllable preheating temperature based on SLS molding that can process non-homogeneous variable-density material parts and has good practicability Part preparation method.

The technical solution adopted by the present invention to solve its technical problems is:

A method for preparing a non-homogeneous material part with controllable preheating temperature based on SLS molding, the method for preparing a non-homogeneous material part comprises the following steps:

1) Construct a three-dimensional model of the heterogeneous material part to be processed;

2) According to the sintering density distribution along the height direction of the non-homogeneous material parts to be processed, and according to the corresponding curve between the preheating temperature and the sintering density under the set laser power conditions in the SLS forming machine, determine the non-homogeneous material parts to be processed. The change curve of processing height direction and preheating temperature of homogeneous material parts;

3) The three-dimensional model is input into the SLS forming machine, and the processing is controlled according to the change curve of the processing height direction and the preheating temperature, and the inhomogeneous material parts are obtained by layering and processing according to the processing height.

As a preferred solution: in the step 2), the distribution of the sintered density changes in a gradient, and the change curve changes in a gradient.

The technical concept of the present invention is: Selected Laser Sintering (SLS) is to use a precisely guided laser beam to sinter or solidify material powder to form a three-dimensional prototype or part. That is to say, the molding machine uses the laser beam to selectively scan and melt the thin and evenly layered material powder on the workbench according to the prototype layered profile output by the computer. The powders in the scanning area selected by the layered pattern are fused by the laser beam and bonded together, while the powders not in this area remain loose. When one layer is scanned, the worktable is moved up (or down) to control the sintering of a new layer. After all the sintering, the excess powder is removed, and then the prototype or parts are obtained by grinding and drying.

The design idea of heterogeneous material parts based on SLS forming is the same as that of ideal material parts, that is, according to different functional requirements of parts, it is divided into limited regions, and in each region, the component phase and volume ratio of materials are the same. Continuously changing according to needs; exhibiting the non-uniformity of the material and function of the part as a whole. Since the SLS molding machine used in the experiment uses a single nylon material during processing, its non-uniformity is manifested by the different densities of different parts of the part, so the heterogeneous material parts based on SLS molding are variations in ideal material parts. Density material parts.

In the SLS molding process, the molding strength of parts is determined by the sintering density, which is not only related to process parameters, but also related to the placement of parts. The SLS molding experiments that have been done show that the SLS molding process and the preheating temperature field in the sintering area greatly affect the microstructure and macrostructure of the sintered parts (such as porosity distribution and anisotropic dimensional accuracy, etc.), and the non-uniform The preheating temperature field affects the sintering density of the test pieces placed in different positions, and thus leads to the strength change of the test pieces in different positions, which provides the possibility for processing parts of inhomogeneous materials.

The beneficial effects of the invention are mainly manifested in that it can process non-homogeneous and variable-density material parts, and has good practicability.

Description of drawings

Figure 1 is a schematic diagram of the processing of SLS molding equipment.

Figure 2 is a schematic diagram of the setting of preheating temperature and part position.

Figure 3 is a schematic diagram of the change curve of sintering density with preheating temperature. From top to bottom, it is the curve of sintering density with preheating temperature when sintering with laser power of 30W, 28W, 26W, 24W, 22W and 20W.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

Referring to Figures 1 to 3, a method for preparing a non-homogeneous material part with controllable preheating temperature based on SLS molding, the method for preparing a non-homogeneous material part includes the following steps:

1) Construct a three-dimensional model of the heterogeneous material part to be processed;

2) According to the sintering density distribution along the height direction of the non-homogeneous material parts to be processed, and according to the corresponding curve between the preheating temperature and the sintering density under the set laser power conditions in the SLS forming machine, determine the non-homogeneous material parts to be processed. The change curve of processing height direction and preheating temperature of homogeneous material parts;

3) The three-dimensional model is input into the SLS forming machine, and the processing is controlled according to the change curve of the processing height direction and the preheating temperature, and the inhomogeneous material parts are obtained by layering and processing according to the processing height.

In the step 2), the distribution of the sintered density presents a gradient change, and the change curve presents a gradient change.

In this embodiment, the processed parts are made of a single material, and the different properties (mainly referring to the tensile strength) of the parts are due to the different densities, and the different densities are obtained by adjusting the preheating temperature of the powder bed of the SLS molding machine to control.

In this embodiment, the main experimental equipment used is the Sinterstation HiQ+HS selective laser sintering molding machine produced by 3D Systems in the United States. Referring to Figure 1, 1 is the molding cylinder, 2 is the powder supply cylinder, and 3 is the powder overflow Cylinder, 4 is the inhomogeneous material part to be processed, 5 is the scanning mirror, 6 is the preheating device, 7 is the optical system, 8 is the CO ₂ laser., 9 is the roller.

Referring to Figure 2, the parts and the preheating temperature match the positions set in the powder bed, and as the preheating temperature decreases, the density of the parts decreases from bottom to top.

Referring to Figure 3, the sintering density varies with the preheating temperature. It can be seen from Figure 3 that: under the same laser power, the sintering density of the part increases according to a certain law with the increase of the preheating temperature, that is, it changes according to the change curve. the

Claims (2)

1. A method for preparing parts of heterogeneous material with controllable preheating temperature based on SLS molding, characterized in that: the method for preparing parts of heterogeneous material comprises the following steps: 1) Construct a three-dimensional model of the heterogeneous material part to be processed; 2) According to the sintering density distribution along the height direction of the non-homogeneous material parts to be processed, and according to the corresponding curve between the preheating temperature and the sintering density under the set laser power conditions in the SLS forming machine, determine the non-homogeneous material parts to be processed. The change curve of processing height direction and preheating temperature of homogeneous material parts; 3) The three-dimensional model is input into the SLS forming machine, and the processing is controlled according to the change curve of the processing height direction and the preheating temperature, and the inhomogeneous material parts are obtained by layering and processing according to the processing height. 2. The method for manufacturing heterogeneous material parts with controllable preheating temperature based on SLS molding according to claim 1, characterized in that: in the step 2), the distribution of the sintered density changes in a gradient, and the change The curve has a gradient change.

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