• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
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    • 专利摘要:
    The object of the present invention is a device that allows two or more concentric compactions, in different stages of filling and compaction, being able to use different masses and pressures that, once sintered, result in zones of different porosity in a single piece and with a gradient transition according to the design. It is applicable in solutions for bone implants, self-lubricating parts, high efficiency heat dissipators and simulation of nuclear fuels. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2632888A1
    申请号:ES201600197
    申请日:2016-03-14
    公开日:2017-09-15
    发明作者:José Antonio RODRIGUEZ ORTIZ；Paloma TRUEBA MUÑOZ；Yadir TORRES HERNÁNDEZ；Juan José PAVÓN PALACIO
    申请人:Universidad de Sevilla；
    IPC主号:
    专利说明:

     Powder compaction device to obtain sintered parts with radial gradient porosity, procedure for obtaining and using 5 Technical sector The invention falls within the area of Materials Science and Engineering, more specifically in the manufacture of parts with customary geometry in the powder technology process and with a radial porosity gradient. In particular, it is of special interest in 10 solutions for bone implants, self-lubricated parts, high efficiency heat sinks and simulation of irradiated or spent nuclear fuel pellets. 15 State of the art A porosity gradient material is one that has an inhomogeneous distribution of porosity in at least one of the three directions of space. One of the most used aspects is the manufacture of this type of parts based on processes from powders. The following describes, briefly and in an orderly manner, the different techniques recognized in the manufacture of pieces with gradient porosity, classified according to the source of heat input during the powder consolidation process: /. Materials with sintered porosity gradient applying temperature. /.one. Techniques based on conventional powder metallurgy: i) from different sized metal particles saw different diffusion coefficients: these techniques stack layers with different metal particles and which are subsequently compacted. It is worth highlighting the work of 25 Oh (1) where it is applied to sinter Ti with gradient porosity to decrease Young's modulus. The result continues to give an elastic modulus even much higher than those of the bone. ii) "Ioose sintering" V limits of conventional sintering: address the powder metallurgy technique in the absence of compaction or with very low compaction pressure, respectively, with the DESCRIPTIONwhich volume of the material to be sintered has a greater amount of porosity (1-6) than conventional powder metallurgy. 1.2. Techniques that use spacers: i) from the use of space holders in different sizes and / or proportions, combined with PM techniques: This technique requires the use of spacers to generate additional pores, including the stacking variant of layers with different concentrations of spacer, in the mixture with powder, between a layer and the consecutive one. The removal of the spacer particle is required (by leaching or evaporation, depending on the typology) ii) by generation of porous areas on solid cores: This type of techniques addresses the idea of combining a solid core with a porous outer layer 10 that serves to facilitate the in-growth of bone tissue while the core guarantees mechanical strength. It is remarkable the work of Dewidar and Lim (2008) where they successfully apply this technique in TiAiGV4 alloy (7), manufacturing samples with different surface porosities (30, 50 and 70%). iii) Hot Isostatic Press (HIP) and Capsule-Free Hot Isostatic Pressinq (CF-HIP): spacers are used as described in the other techniques, but densification is performed with a hot isostatic pressing. For example, NaF is used in conjunction with HIP or NH4HC03 with its CF-HIP variant. iv) sintering with hollow spherical preforms: This technique achieves highly porous materials by sintering of previously obtained hollow metal spheres. It has been widely used with Cu, Ni, steel and Ti. v) metal powder injection molding (MIM): it combines the forming of complex parts thanks to injection molding, with the mechanical performance of metal alloys. The metal powders and spacers are mixed with lubricants and plasticizers that act as conductors of the metal load and allow the assembly to flow, to enable its injection into molds and obtain a green forming to sinter. 1.3. Directional cooling molding techniques: They are used to obtain elongated and directed porosity (8-9). It has been traditionally used to process ceramic materials (10) and, more recently, for the production of metal foams (11). This technique has been reviewed and applied in Ti by Dunand and Chino (11) using water as a fluid and applying a directional solidification in its freezing, obtaining a highly anisotropic material. There are other works such as that carried out by Yook (12), where a suspension of cantene and TiH2 is used, which minimizes oxygen contamination. 1.4. Other Techniques: i) using foaming agents: The foaming agents are mixed with powders, then continue by conventional PM route. When the temperature rises, the release of the gas and the total or partial melting of the metal is caused, which allows the formation of poresThey stabilize during cooling. ii) from gas trapped in metallic powder: The controlled expansion of Ar trapped in compacts of metallic powder is better known, then continue on the conventional PM route. iii) high temperature self-propagation techniques, SHS: they are based on strongly exothermic chemical reactions, whose heat given off allows their self propagation by means of a wave or combustion front. iv) skeleton replication techniques: These techniques are based primarily on the immersion of structures made of polymeric material in a suspension of powder and binder, to proceed to its subsequent drying. In this way, the geometry of the base skeleton is reproduced and when the metallic powder is completely dry, the polymeric skeleton is thermally removed, leaving the material ready to sinter. //. Porosity gradient materials sintered with electric current. 11.1. Sintering techniques assisted by electric field: they are also called Electric Current Assisted 5intering (ECAS). Basically, it is about using electric current to boost or improve the sintering of the powders as a result of the Joule effect, aided by the application of a small compression load. The two most commonly used variants are: i) Electric Resistance Sintering (SRE) and ii) Spark Plasma Sintering (SPS). //.2. Capacitor electro-discharge (EDC) techniques: the works carried out with this technique have evaluated the different energies used, the pore size and the necks 20 obtained, as well as the mechanical properties (13). Two variants have been evaluated regarding the configuration of the electrodes, the input energy and the mass of the sample (14) and all the results indicate the feasibility of manufacturing dental implants of commercial Ti by powder atomization and EDC techniques. Authors, such as Wen, have obtained the appropriate parameters to manufacture porous implants of Ti c.p. by EDe (15). On the other hand, 25 processes have been developed for the manufacture of metallic foams from Ti and Mg powder (16) with electro discharge techniques, which have exceptional characteristics. //one. Porosity gradient materials sintered by other techniques. //1.1. Selective laser fusion (5L5): it has proven to be an effective means for the construction of dental implants with a functionally graduated material, which adapts better to the elastic properties of the bone (1, 17). The work of Traini in 2008 (18) is remarkable, where the authors present the technique of manufacturing a sample with gradient porosity from theinside to the outer surface manufactured by SLS, starting from an alloy of TiAI6V4 by sintering layer to layer of metallic powder. 111.2. Electron Sickle Sintering Techniques (EBM): they are based on the phenomenon of generation of an electron beam (by electric and magnetic fields) and how the collision of the electron beam with a solid matter transforms the kinetic energy into a high heat transfer This phenomenon gives the possibility to achieve a very rapid and controlled local heating, powerful enough to sinter a layer of metallic powder. It is an additive process where it is sintered layer by layer until the piece is completed. 111.3. 3D Printing Techniques: they are used to generate complex three-dimensional pieces 10 directly from a computer model by layered printing and has had a boom in the last decade, with the development of 3D printers and CAD techniques. Layers of material are generated one on top of the other and the stratification process is repeated until the piece is completed. 15 Despite the existing techniques for the manufacture of this type of pieces, it would be desirable to obtain compact with radial gradient porosity that allow the control of the porosity in the different areas of the piece (core, intermediate and outer crowns for which it can be set, vary and / or combine the following parameters of the procedure: 1) type of powder metallurgical technique (conventional and spacers), 2) compaction pressure and 3) type 20 size and proportion of the spacer. The invention responds to the need to develop and implement techniques for manufacturing parts with gradient and controlled porosity in at least three different sectors: biomedical (primarily bone implants), aerospace (heat sinks in space vehicles) and nuclear energy (simulation of irradiated or spent nuclear fuel pellets). The manufacture of this type of materials, represents a breakthrough in the structural replication of those parts to which it intends to replace to mimic or obtain improvements. 1. Biomedicine, for the manufacture of bone implants: Materials such as commercially pure titanium and its TiAI6V4 alloy, have the best performance in vivo (standard 15010993-1) and high specific mechanical properties. They are also bioinert and chemically stable, presenting excellent corrosion resistance, especially against physiological environments. All this makes them the most used in these applications. However, they have disadvantages that in many cases compromise the reliability of implants and prostheses: l) limited osseointegration capacity, which makes theiroptimization so as to reduce the risk of implant loosening, 2) A marked difference in stiffness far superior to that of the bone tissues that are intended to be replaced. This implies a screening of the tensions that promotes bone resorption, with which the density of the adjacent bone decreases, thus increasing the probability of fracture. In this context, it is very interesting to design materials for new implants with a "à la carte" gradient porosity, inspired by the receiving biomechanical systems, always guaranteeing the mechanical balance, and also the biological balance so as to facilitate in-growth and osseointegration is improved. An example is gradient porosity in the radial direction resembling the structure of bone tissue in intervertebral discs and the replacement of bone tissue affected by tumors. 2. Space vehicles, for the manufacture of Loop Heat Pipe type devices: These devices perform a high efficiency heat transfer, dissipating the heat generated in the electronic support plates to the outer space through the radiator surface. The operation of this device is based on the diode effect: heat transfer in only one direction. First, heat enters the evaporator and vaporizes the working fluid on the outer surface of the so-called primary wick, also commonly known by its English word, wick. The wicks are nothing more than porous metallic materials. The possibility of manufacturing this radial gradient porosity instead of homogeneous suggest a direct effect of improving the efficiency of these devices. 20 3. Nuclear fuels, for the manufacture of materials that simulate the structure of irradiated or spent nuclear fuel pellets: The use of real nuclear fuels, raises the need to know in detail the behavior of the irradiated or spent fuel, stored in a repository intermediate or definitive, in order to meet your requirements. On a laboratory scale, ceramic materials are used that are similar to the 25 nuclear fuels and that simulate some of the characteristics of the actual irradiated or spent fuel pellets, such as mechanical properties, chemical properties, oxide formation, secondary phases, etc. Among all the analogs used for the study of the characterization of irradiated or spent fuel, Ce02 is being widely used because its structure is similar to the structure and properties of uranium oxides and actinides such as plutonium. In this context, it is very interesting to use materials with radial gradient simulating the actual structure of the nuclear fuel pellets after reacting in the reactor as a result of the appearance of He, gases and other fission products that are formed during the reactions and that interact and modify the microstructure of the fuel itself.References (1) Oh et al. Microstructures and Mechanical Properties of Porosity-Graded. 2003, Materials Transactions, Vol. 44, No. 4 (2003) pp. 657 to 660. (2) Asaoka K., et al. 5.1 .: Journal of Biomedical Materials Research. 19 (6): p. 699-713., 1985. 5 (3) Cirincione R., et al. Processing and Properties of Lightweight Cellular Metals and Structures. 2002. (4) Dunand, D. e. Processing of titanums foams. 2004. Advanced Engineering Materials. 6 (6): p. 369-376. (5) Schuh, e., Et al. 2000. Materiality Act, 48 (8): p. 1639-1653. 10 (6) Taylor, N., et al. 1993. Acta Metallurgica Et Materialia. 41 (3): p. 955-965. (7) Dewidar, Lim. Properties of Ti-6AI-4V solid core and porous surface. 2008, Journal of Alloys and Compounds 454,442-446. (8) Singh R., Lee P.D., Dashwood R.J. Lindey T. Titanium foams for biomedical applications: a review. 2010, Materials Technology, Vol 25, NO 3/4, pag: 127-136. 15 (9) Ryan, G. E., et al. Biomaterials 2008. 29 (27): p. 3625-3635. [10) Studart A.R, Gonzenbach U.T, Tervoort E, Gauckler L. J. 2006, J. Am. Ceram. Soc., 89, (6), 1771. (11) Chinese Y., Dunand D.e. Directionally freeze-cast titanium foams with aligned elongated pores. 2008; Acta Materialia, 56, 105-113. 20 (12) Yook S.w., Yoon B.H., Kim H.E., Koh Y.H. and Kim Y.S. 2008: Mater. Lett., 62, (30), 4506-4508. (13) Okazaki, Lifland and. The mechanical properties of a Ti-6AI-4V dental implant. 1993. (14) Lifland M.L., Okazaki K. Properties of titanium dental implants produced by electro-discharge compaction. 1994. Clinical Material. V17.Pages 203-209. 25 (15) Wen, e. E., et a. Processing of Ti and Mg porous and biocompatible. 2001, Scripta Materialia, 45 (10): p. 1147-1153. (16) Lee, W. H. and Hyun, e. Y. Journal of Materials Processing Technology, 2007. 189 (1-3): p. 219-223.2007, Journal of Materials Processing Technology. 189 (1-3): p. 219-223. (17) Vamsi Krishna, B., et al. 2008. Acta Biomaterialia, 4 (3): p. 697-706. 30 (18) Traini, Mangano, Sammons, Macchi, Piattelli. Direct laser metal sintering, as a new approach for the manufacture of a functionally graduated isoelastic material for the manufacture of porous Ti dental implants. 20085 DETAILED DESCRIPTION OF THE INVENTION The subject of the present invention is a powder compaction device for obtaining sintered parts with radial gradient porosity, as well as the method of obtaining sintered parts and their corresponding uses. The device, made of materials such as steels. of high strength, WC-Co, quick acers, ceramics, etc., allows to obtain a piece with a radial gradient of N layers (where N varies from 2 to an integer value that will depend on the width of the layers and the total diameter of the piece , the latter being a maximum of 300mm) is constituted by the following elements, when a single uniaxial pressure is applied with simple superior effect in the compaction: a) 1 matrix. b) 1 sufridera c) Set of compaction punches, consisting of: 1 core punch and (N-l) punch-bushes. D) Extraction tools, consisting of: 1 extractor base, N extractors and their corresponding extractor base supplements. e) Centering tooling, consisting of 1 centering and 1 centering base. In the case of applying uniaxial compaction pressure with double effect, that is, superior and inferior, the device will consist of: a) 1 matrix. b) Compaction punch set, consisting of: 1 core-punch pair (upper and lower), (N-l) pairs of punch-caps. c) Extraction tools, consisting of: 1 extractor base, N extractors and their corresponding 25 extractor base supplements. d) Centering tooling, consisting of 1 centering device and 1 centering base The device allows manufacturing parts from any type of material and powder mixture, with or without spacers, and their respective combinations. Dusts and spacers can have different composition, particle size and morphology. In the case of using spacers, they must be removed prior to the sintering stage, in an appropriate manner according to their nature (by heat treatment or leaching).In addition, it allows to obtain pieces from different powders V their combinations. In addition, different compaction pressures, geometries, lubrication types, radial porosity gradient designs can be used. These possible variations are detailed below: The device allows to apply compaction pressures equal V / or different (both in the 5 core and in the different concentric layers i) V manufacture parts with any geometry or combination, of constant or stepped section (cylindrical , regular or irregular polygonal), to obtain volumes of two or more concentric layers, even with the hollow core. Depending on the capacity of the presses V of the mechanical properties of the materials used to manufacture the compaction device, as well as the degree of compressibility of the materials to be compacted V in an orientative manner, the height of the pieces in green can vary between 1 V 40 mm V the width or diameter, depending on the number V thickness of the gradient layers, will vary between 6 V 300 mm. The lubrication described in the process of obtaining can be replaced by a mass lubrication of the powder mixture. 15 The use of the device allows different porosity radial gradient designs to be obtained, which can vary from the core of the compact towards the outside, increasing V / or decreasing, total or by areas. To obtain the designed gradients, V / o can be varied: 20 Starting powder material: type, size V particle morphology. Use of spacers: proportion, size V particle morphology. Compaction pressures. Temperature, time V sintering atmosphere. Detailed description of the procedure for obtaining 25 The procedure for obtaining in its two variants A) V B) is described in detail below.5 10 15 20 25 A. Applying uniaxial compaction pressure with simple effect. It comprises the following stages: a) Preparation and homogenization of the material: the necessary mass of the powder material is calculated, based on the final dimensions of the piece and the porosity designed in each layer. The porosity will depend on the powder or the mixture of powder with spacers and lubricants in each case. b) First compaction in which the green core piece is obtained. It takes place after the following steps: 1) the inner surface of the smaller diameter punch-bushing is lubricated; 2) the parts of the device are placed in this order: die, die and (N-i) punch-bushing, starting from the one corresponding to layer N; 3) the central cylindrical hollow is filled with powder material; 4) the powder is compacted with the core punch; 5) the entire assembly is placed on the extractor base and the corresponding supplement, to extract the core in green using the extractor-core and, finally; 6) the remains of lubricant inside the oven are removed at a suitable temperature and time depending on the type of lubricant. c) Compaction of the consecutive layers i (2 <i <N). It takes place after the following steps: 1) the inner surface of the punch-bushing (i + 1) is lubricated; 2) the parts of the device are placed in this order: die, die and punch-bushes from N to (i + l); 3) the green piece obtained after the last compaction (i-1) is placed and centered; 4) the corresponding punch assembly (up to i-l) is centered with centering tooling and centering; 5) the hollow of layer i is filled with powder material; 6) centering tooling is removed; 7) the powder is compacted with the layer i punch; 8) the whole set is placed on the extractor base and the corresponding supplement i; 9) the entire pressed part has been removed so far with the extractor-layer i and finally; 10) the remains of lubricant inside the oven are removed at a suitable temperature and time depending on the type of lubricant. d) Sintering of the resulting piece: It takes place in an oven at the appropriate temperature, time and atmosphere for the material used. 30 B. Applying uniaxial compaction pressure with double effect. It comprises the following stages: a) Preparation and homogenization of the material: the necessary mass of the powder material is calculated, based on the final dimensions of the piece and the porosity designed in each5 10 15 20 layer. The porosity will depend on the powder or the mixture of powder with spacers and lubricants in each case. b) First compaction in which the green core piece is obtained. The following steps have louvers: 1) the inner surface of the smaller diameter punch-bushing is lubricated; 2) the parts of the device are placed in this order: matrix, (N-1) punch-bushes, starting from the one corresponding to layer N; 3) the central cylindrical hollow is filled with powder material; 4) the powder is compacted with the core-punch pair; 5) the entire assembly is placed on the extractor base and the corresponding supplement, to extract the core in green using the extractor-core and, finally; 6) the remains of lubricant inside the oven are removed at a suitable temperature and time depending on the type of lubricant. c) Compaction of the consecutive layers i (2 <i <N). It takes place after the following steps: 1) the inner surface of the pair of punch-bushes (i + 1) is lubricated; 2) the parts of the device are placed in this order: matrix and punch-bushes from N to (i + 1); 3) the lower punch assembly is formed, formed by the core punch and the sleeve punches to the layer i; 4) place and center the piece in green obtained after the last compaction (i-1); 5) the corresponding upper punch assembly is centered (up to i-l), with centering tooling and centering; 6) the hollow of layer i is filled with powder material; 7) centering tooling is removed; 8) the powder is compacted with the pair of layer i punches; 9) the whole set is placed on the extractor base and the corresponding supplement i; 10) the entire pressed part is extracted so far with the extractor-layer i and, finally; 11) the remains of lubricant inside the oven are removed at a suitable temperature and time depending on the type of lubricant. 25 d) Sintering of the resulting piece: It takes place under the appropriate conditions for the material used (temperature, time and atmosphere). Example of embodiment of the invention The present invention is illustrated by the following non-limiting example: Ti cylinder c.p. with radial gradient porosity in 3 concentric layers. It comprises the following stages:5 10 15 20 25 a) Preparation and homogenization of the material: the necessary mass of Ti powder c.p. Grade IV, with density = 4.51 gjcm3 and average particle size of 59 ~ m, depending on the height and porosity previously designed in each layer. The powder compressibility curve is available. The following table 1 shows the diameters and heights of the design as well as compaction pressure, relative density and mass calculated in each layer. Table 1. Dimensions, compaction pressure, relative density and mass by layers. Layer Diameter Height Pressure compaction Density Mass Ti {mm} {mm} {MPa} relative {%} {g} Core 8 20 500 78.00 3.53 N = 2 14 20 250 63.75 5.96 N = 3 20 20 125 54.37 7.85 b) First compaction in which the green core piece is obtained. It takes place after the following steps: 1) The inner surface of the 14mm diameter punch-bushing is lubricated, with wax suspension in acetone (20 g of wax per 100 cm3 of acetone). 2) The parts of the device are placed in this order: die, die, punch-bushing of layer N = 3 and punch-bushing of layer N = 2. 3) The central hole is filled with 3.53 g of Ti c.p. 4) The powder is compacted with the core punch at 500 MPa in a universal uniaxial loading machine. 5) The entire assembly is placed on the extractor base and the extractor base supplement for N = 1, to extract the core in green using the extractor for N = 1. 6) The remains of lubricant inside the oven are removed at a temperature of 500 ° C for 60 minutes under high vacuum. c) Compaction of the N = 2 layers. It takes place after the following steps. 1) The inner surface of the 20mm diameter punch-bushing is lubricated, with wax suspension in acetone (20 g of wax per 100 cm3 of acetone). 2) The parts of the device are placed in this order: die, die and punch-cap of layer N = 35 10 15 20 25 30 3) The green piece obtained in the previous compaction is placed and centered. 4) The punch-core assembly is centered with centering tooling and centering. S) Fill the gap of layer N = 2 with 5.96 g of Ti c.p. 6) The centering tool is removed 7) The powder is compacted with the punch-bushing of layer N = 2, at 250 MPa in a universal uniaxial loading machine. 8) The whole set is placed on the extractor base and the corresponding extractor base supplement N = 2. 9) The entire pressed part has been removed so far with the layer N = 2 extractor. 10) The remains of lubricant inside the oven are removed at a temperature of 60 ° C for 60 minutes under high vacuum. d) Compaction of layers N = 3. It takes place after the following steps. 1) The inside surface of the matrix is lubricated with a wax suspension in acetone (20 g of wax per 100 cm3 of acetone). 2) The parts of the device are placed in this order: matrix and sufridera. 3) The green piece obtained in the previous compaction is placed and centered. 4) The assembly of punch-core and punch-bush of layer N = 2 is centered, with centering tooling and centering. S) Fill the gap of layer N = 3 with 7.85 g of Ti c.p. 6) Centering tooling is removed. 7) The powder is compacted with the punch-cap of layer N = 3, at 125 MPa in a universal uniaxial loading machine. 8) The whole set is placed on the extractor base and the corresponding extractor base supplement N = 3. 9) The entire pressed part has been removed so far with the layer N = 3 extractor. 10) The remains of lubricant inside the oven are removed at a temperature of 60 ° C for 60 minutes under high vacuum. e) Sintering of the resulting piece: The resulting piece in green is introduced into the sintering furnace at 1250 ° C, under high vacuum, for 2 hours. The characteristics of the finished piece are shown in the following Table 2.Table 2.-Mechanical and geometric characteristics of the piece to finish. Layer M.de Young Porosity Limit Diameter Height Experiment. (Gpa) creep (Mpa) Experimet. (% Vol) outside (mm) (mm) Core 77 14 7 18.50 N = 2 31 283.5 38 15 17.80 N = 3 11 57 18 18.70 Description of the figures S Figure 1.-Describe the parts that make up the uniaxial compaction device for use with simple effect (A) and double effect (B), in the case of obtaining cylindrical pieces with layers N = 4. 1.-matrix 2.-sufridera 10 3 Y 3b.-punch-bushing of the layer N = 4 4 Y 4b.-punch-bushing of the layer N = 3 s and sb.-punch-bushing of the layer N = 2 7 Y 7b.-punch-core 8.-centering base 15 9.-centering 10.-extractor base 11.-extractor base extractor core l2.-extractor base extractor layer N = 2 13.-extractor base extractor layer N = 3 20 l4.-extractor base extractor layer N = 4 ls.-extractor layer N = 2 l6.-extractor layer N = 3 17.-extractor layer N = 4Figure 2.-Longitudinal sections of the device at three different moments of the uniaxial compaction procedure with simple effect (A). Case of obtaining cylindrical pieces with layers N = 4. Left Image: core compaction. Central image: centered for the compaction of the N = 2 layer. Right image: extraction after compaction of the 5 layer N = 2. 6. Ti powder c.p. Figure 3.-Longitudinal sections of the device at three different moments of the uniaxial compaction procedure with double effect (B). Case of obtaining cylindrical pieces with layers N = 4. Left Image: core compaction. Central image: centered 10 for the compaction of the N = 2 layer. Right image: extraction after compaction of the N = 2 layer. 
    权利要求:
    Claims (1)
    [1]
    1.-Device for compacting powders to obtain sintered parts with radial gradient porosity, characterized in that it comprises: a) A matrix. 5 b) A nose cone c) Set of compaction punches, consisting of: 1 punch-core and (N-l) punches-bushings. d) Extraction tools, consisting of: 1 extractor base, N extractors and their corresponding extractor base supplements. 10 e) Centering tooling, consisting of 1 centering device and 1 centering base. 15 20 25 30 2.-Procedure for obtaining sintered parts using the device described in claim 1, characterized in that it comprises the following stages: -ª. L Preparation and homogenization of the material: the necessary mass of the powder material is calculated, depending on of the final dimensions of the piece and the porosity designed in each layer. The porosity will depend on the powder or the mixture of powder with spacers and lubricants in each case. hl First compaction in which the green core piece is obtained. It takes place after the following steps: 1) the inner surface of the smaller diameter punch-bushing is lubricated; 2) the parts of the device are placed in this order: die, anvil and (N-1) punch-cap, starting from the one corresponding to layer N; 3) the central cylindrical hole is filled with powdered material; 4) the powder is compacted with the core punch; 5) the whole assembly is placed on the extractor base and the corresponding supplement, to extract the core in green using the extractor-core and, finally; 6) the remains of lubricant are eliminated inside the oven at a suitable temperature and time depending on the type of lubricant. 9 Compaction of consecutive i layers (2 <i <N). It takes place after the following steps: 1) the inner surface of the punch-bushing (i + 1) is lubricated; 2) the parts of the device are placed in this order: die, anvil and punches-shells from N to (i + 1); 3) the piece in green obtained after the last compaction (i-1) is placed and centered; 4) the corresponding punch assembly (up to i-1) is centered with the centering tool and the centering device; 5) the gap of layer i is filled with powder material; 6) the centering tool is removed; 7) the powder is compacted with the punch CLAIMS5 10 15 layer i; 8) the whole assembly is placed on the extractor base and the corresponding supplement i; 9) the entire piece pressed so far is extracted with the extractor-layer i and, finally; 10) the remains of lubricant are eliminated inside the oven at a suitable temperature and time depending on the type of lubricant. ill Sintering of the resulting piece: It takes place in a furnace at the appropriate temperature, time and atmosphere for the material used. 3. -Procedure according to claim 2, characterized in that a uniaxial compaction pressure is applied with a simple superior effect. 4.-Device for compacting powders to obtain sintered parts with radial gradient porosity, characterized in that it comprises: a) A matrix. b) A set of compaction punches, consisting of: 1 pair of punch-core (upper and lower), (N-l) pairs of punches-bushings. c) Extraction tools, consisting of: 1 extractor base, N extractors and their corresponding extractor base supplements. d) Centering tooling, consisting of 1 centering device and 1 centering base. 20 5.-Procedure for obtaining sintered parts using the device described in claim 4 characterized in that it comprises the following steps: 25 30 ª-.l Preparation and homogenization of the material: the necessary mass of the powder material is calculated, depending on the final dimensions of the piece and the porosity designed in each layer. The porosity will depend on the powder or the mixture of powder with spacers and lubricants in each case. Ql First compaction in which the core piece is obtained in green. It takes place after the following steps: 1) the inner surface of the smaller diameter punch-bushing is lubricated; 2) the parts of the device are placed in this order: die, (N-1) punches-bushings, starting from the one corresponding to layer N; 3) the central cylindrical hole is filled with powdered material; 4) the powder is compacted with the core-punch pair; S) the whole assembly is placed on the extractor base and the corresponding supplement, to extract the green core using the5 10 15 extractor-core and, finally; 6) the remains of lubricant are eliminated inside the oven at a suitable temperature and time depending on the type of lubricant. º-Compaction of consecutive i layers (2 <i <N). It takes place after the following steps: 1) the inner surface of the pair of punches-bushings (i + 1) is lubricated; 2) the parts of the device are placed in this order: die and punches-bushings from N to (i + 1); 3) the assembly of lower punches is placed, formed by the punch-core and the punches-bushings up to layer i; 4) the piece in green obtained after the last compaction (i-1) is placed and centered; 5) the corresponding upper punch assembly is centered (up to i-l), with the centering tool and the centering device; 6) the gap of layer i is filled with powder material; 7) the centering tool is removed; 8) the powder is compacted with the pair of punches layer i; 9) the whole assembly is placed on the extractor base and the corresponding supplement i; 10) the entire piece pressed so far is extracted with the extractor-layer i and, finally; 11) the remains of lubricant are eliminated inside the oven at a suitable temperature and time depending on the type of lubricant. Ql Sintering of the resulting piece: It takes place under the appropriate conditions for the material used (temperature, time and atmosphere). 6. -Procedure according to claim 5, characterized in that a uniaxial compaction pressure is applied with a double upper and lower effect. 25 30 7. Sintered parts obtained according to previous claims, for use in bone implants, self-lubricated parts, high efficiency heat sinks and simulation of irradiated or spent nuclear fuel pellets.
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    公开号 | 公开日 | 专利标题
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    MXPA04001040A|2001-08-03|2004-05-27|Gkn Sinter Metals Inc|Method and apparatus for manufacturing multi-material powder metal components.|
    WO2004002659A1|2002-06-26|2004-01-08|Höganäs Ab|Compaction method for high density powder metal products|
    WO2009124380A1|2008-04-11|2009-10-15|Stackpole Limited|Device and method for pressing a metal powder compact|
    EP2221131A1|2009-05-29|2010-08-25|Sandvik Intellectual Property AB|Methods of producing a powder compact and a sintered composite body|
    EP2636470A1|2010-11-04|2013-09-11|Aida Engineering, Ltd.|High density molding method and high density molding device for mixed powder|
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