CN111055493A - Laser sintering forming device and forming method - Google Patents
Laser sintering forming device and forming method Download PDFInfo
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- CN111055493A CN111055493A CN201811203535.3A CN201811203535A CN111055493A CN 111055493 A CN111055493 A CN 111055493A CN 201811203535 A CN201811203535 A CN 201811203535A CN 111055493 A CN111055493 A CN 111055493A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
- B29C64/10—Processes of additive manufacturing
- B29C64/141—Processes of additive manufacturing using only solid materials
- B29C64/153—Processes of additive manufacturing using only solid materials using layers of powder being selectively joined, e.g. by selective laser sintering or melting
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
- B29C64/20—Apparatus for additive manufacturing; Details thereof or accessories therefor
- B29C64/264—Arrangements for irradiation
- B29C64/268—Arrangements for irradiation using laser beams; using electron beams [EB]
- B29C64/273—Arrangements for irradiation using laser beams; using electron beams [EB] pulsed; frequency modulated
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
- B29C64/30—Auxiliary operations or equipment
- B29C64/307—Handling of material to be used in additive manufacturing
- B29C64/321—Feeding
- B29C64/336—Feeding of two or more materials
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y10/00—Processes of additive manufacturing
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y30/00—Apparatus for additive manufacturing; Details thereof or accessories therefor
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y40/00—Auxiliary operations or equipment, e.g. for material handling
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Abstract
The invention relates to the technical field of 3D printing forming, and discloses a laser sintering forming device and a forming method, wherein the device comprises a powder box system, a light source system and a working platform system, the powder box system comprises a first powder box (1) and a second powder box (2), the light source system comprises a laser source (4), the working platform system comprises a working platform (5) and a paving roller (3), the method adopts two materials with large melting point difference to perform cross powder paving, the materials after powder paving are subjected to cross sintering, the formed workpiece structure is an interpenetrating network, and the two materials respectively provide the effects of supporting and supplementary bonding. Compared with the prior art, the laser sintering forming device and the forming method provided by the invention have the advantages that the screening range of materials used in the laser sintering technology is expanded, the porosity of a workpiece is effectively reduced, the density of the workpiece is improved, the adhesion force among powder is increased, and the performance of the workpiece is greatly improved.
Description
Technical Field
The invention relates to the technical field of 3D printing and forming, in particular to a laser sintering forming device and a forming method.
Background
Selective Laser Sintering (SLS) is one of additive manufacturing technologies, also called layered manufacturing technologies, and the Selective Laser Sintering (SLS) method uses an infrared laser as an energy source, and most of used molding materials are powder materials. During processing, the powder is first preheated to a temperature slightly lower than the melting point of the powder, then the powder is spread under the action of a leveling roller, laser beams are selectively sintered under the control of a computer according to layered section information, the next layer of sintering is carried out after one layer of sintering is finished, and redundant powder is removed after all the sintering is finished, so that a sintered part can be obtained. This technique has been widely used in finished metal part machining and investment casting molds, prototypes, artware and functional parts using thermoplastic resin machining.
The laser sintering thermoplastic resin materials which are widely researched at present are generally nylon 11, nylon 12, polypropylene, polyether ether ketone and the like. The performance of the laser sintering finished product depends on the performance, the density and the sintering process of the adopted raw materials. When two materials are used in a composite mode, if the difference between the melting points of the two materials is large, the adopted laser power cannot meet the requirements of the two materials at the same time, the problems of large gaps of a workpiece, poor powder bonding, powder falling and the like are often caused, the mechanical strength and the service life of a product are seriously influenced, and the difficulty of limiting the application of a laser sintering technology in the industry is also caused.
Therefore, the problem that when two materials are used in a composite mode, a product formed by laser sintering has large void ratio, low density and low powder adhesion is needed to be solved in the field.
Disclosure of Invention
The invention aims to overcome the problems of large porosity, low density and low bonding force between powder of a workpiece in the prior art, and provides a laser sintering forming device and a forming method. Correspondingly, the invention provides a calculation method for selecting the laser sintering power through the inherent properties of the material. Compared with the prior art, the laser sintering forming device and the forming method provided by the invention have the advantages that the screening range of materials used in the laser sintering technology is expanded, the porosity of a workpiece is effectively reduced, the density of the workpiece is improved, the adhesion force among powder is increased, and the performance of the workpiece is greatly improved.
In order to achieve the above object, the present invention provides a laser sintering molding apparatus, which includes a powder box system, a light source system and a work platform system, wherein the powder box system includes a first powder box 1 and a second powder box 2, the light source system includes a laser source 4, and the work platform system includes a work platform 5 and a spreader 3;
the first powder box 1 and the second powder box 2 are positioned right above the working platform 6 and are used for containing different material powders with different particle sizes;
the laser source 4 is output by a light source system and is used for laser sintering powder;
the paving roller 3 is located above the working platform 5 and moves for paving powder.
The invention provides a laser sintering forming method of a composite material, which comprises the step of repeatedly and alternately laying powder and performing laser sintering on at least two different material powders with different particle sizes on the laser sintering forming device.
The laser sintering forming device and the forming method have the following advantages:
(1) the laser sintering forming device and the forming method adopt two powder discharging boxes, and when two materials are used in a composite mode, powder is respectively discharged and powder is paved in a crossed mode, so that a workpiece is small in void ratio, high in density and high in adhesive force between powder.
(2) The invention adopts different laser sintering powers according to different used material powders, and provides a calculation formula of the laser sintering power, so that the laser sintering power required by two composite materials during respective sintering can be effectively calculated.
Drawings
FIG. 1 is a schematic view of a laser sintering molding apparatus.
Description of the reference numerals
1 first powder box 2 second powder box 3 spreading roller
4 laser source 5 work platform
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
In the present invention, the use of directional terms such as "upper, lower, left, right" generally means "upper, lower, left, right" in the abstract drawings provided herein, unless otherwise specified.
The invention provides a laser sintering forming device, which comprises a powder box system, a light source system and a working platform system, wherein the powder box system comprises a first powder box 1 and a second powder box 2, the light source system comprises a laser source 4, and the working platform system comprises a working platform 5 and a paving roller 3.
In the present invention, the first powder box 1 and the second powder box 2 are located right above the working platform 5 and are used for containing different material powders with different particle sizes, wherein a linear distance between the first powder box 1 and the second powder box 2 and a height from the working platform 5 are not particularly limited and may be well known to those skilled in the art.
In the present invention, the laser sources 4 are output from a light source system for laser sintering powder, the number and the positions of the laser sources 4 are not particularly limited in the present invention, and according to a preferred embodiment of the present invention, the laser sources 4 can emit laser with different laser sintering powers.
In the invention, the light beam of the laser source 4 is vertical to the horizontal plane of the working platform 5 and can move according to the graph required by 3D printing, so that the laser sintering of the powder-paved material powder is realized.
In the invention, the paving roller 3 is positioned above the working platform 5 and moves for paving powder. The shape of the paving roller 3 is not particularly limited, the paving roller can be a cylinder, a cuboid, a triangular prism and the like, the platform has a tangent plane, reciprocating motion can be performed in the platform range, the moving direction can be not limited, and the paving roller can achieve the effect of uniformly paving the material powder discharged from the first powder box 1 and the second powder box 2.
The invention provides a laser sintering forming method of a composite material, which comprises the step of repeatedly and alternately laying powder and carrying out laser sintering on at least two different material powders with different particle sizes on the laser sintering forming device for multiple times.
In the present invention, the material powder includes a material a and a material B, the material a being at least one selected from a first polymer, a first metal, and a first ceramic; the material B is selected from at least one of a second polymer, a second metal and a second ceramic; the first polymer also comprises a first silicon rubber, and the second polymer also comprises a second silicon rubber.
Preferably, the material a is a first polymer; the material B is a second polymer.
More preferably, the first polymer is selected from at least one of polypropylene, polycarbonate, nylon 66, nylon 11, nylon 12, polyetheretherketone, polyurethane, silicone rubber and polystyrene, and the second polymer is selected from at least one of polypropylene, polycarbonate, nylon 66, nylon 11, nylon 12, polyetheretherketone, polyurethane, silicone rubber and polystyrene powder.
In the embodiment of the present invention, the first polymer and the second polymer are not selected from the same polymer, and for example, when the first polymer is polypropylene, the second polymer is at least one of polycarbonate, nylon 66, nylon 11, nylon 12, polyetheretherketone, polyurethane, silicone rubber, and polystyrene.
In the present invention, the minimum value of the particle size of the material a is greater than the maximum value of the particle size of the material B, for example, when the particle size of the powder of the material a is 200-300 μm, and the particle size of the powder of the material B may be 10-60 μm, in the present invention, since the minimum value of the particle size of the material a is greater than the maximum value of the particle size of the material B, the particle size of the material a is larger, and the material a can provide a void for the material B, so the material B can enter the void provided by the material a, thereby increasing the compactness of the product, wherein the material a and the material B may be a mixture of powders with multiple particle sizes satisfying the above particle size range, and in the present invention, the particle sizes are measured by a scanning electron microscope.
In the present invention, the laser sintering molding method of the composite material further includes:
placing a material A in a first powder box 1 and a material B in a second powder box 2;
(II) controlling the powder discharge of the material A to the surface of a working platform 5, moving a spreading roller 3 to spread the powder A, forming a cut layer A on the surface of the working platform 5, and irradiating the cut layer A by using a laser source 4 to perform first laser sintering;
(III) controlling the material B to powder out of the gap of the cut layer A, moving a paving roller 3 to pave the powder B, filling the gap of the cut layer A with the material B, and irradiating the material B with a laser source 4 to perform second laser sintering;
(IV) lowering the working platform 5, repeating the steps II and III, finishing the same-layer cross powder paving of the powder paving A and the powder paving B for multiple times, and performing laser sintering to obtain a finished piece.
In the invention, the filled cutting layer A is continuously accumulated and sintered and the working platform 5 is descended until the finished piece is manufactured.
In the invention, before step (i) is performed, the slice shape of the three-dimensional image may be imported into a computer device, and the shape of the obtained object is the shape imported into the computer device.
In the present invention, the laser source 4 is output by the light source system, and the number of the laser sources is not specifically limited, and may be 1 or 2, as long as it can output laser beams with different laser powers.
In the invention, the material A and the material B are respectively preheated at corresponding preheating temperatures before the material A is placed in the first powder box 1 and the material B is placed in the second powder box 2, wherein the preheating temperature is lower than the laser sintering temperature.
According to the laser sintering method, after a material A in a first powder box 1 is subjected to powder paving A, a laser source 4 irradiates a cutting layer A to form a light spot, the material A reaches the temperature required by laser sintering due to the energy of first laser sintering carried by the light spot, the material A is sintered to form laser sintering points, a large number of gaps are formed among the laser sintering points of the material A and are filled with a material B in a second powder box 2, after the material B is paved in the second powder box 2, the material B is irradiated by the laser source 4 to form the light spot, and the material B reaches the temperature required by laser sintering due to the energy of second laser sintering carried by the light spot, and is sintered to form the laser sintering points. Wherein the distance between the laser sintering points is 0.05-0.15 mm.
In the invention, because the materials selected for the material A and the material B are different, the power of the first laser sintering is different from that of the second laser sintering, the power of the first laser sintering is determined by the material selected for the material A, and the power of the second laser sintering is determined by the material selected for the material B.
In the present invention, in order to obtain the precise power of the first laser sintering and the precise power of the second laser sintering, the power of the first laser sintering and the power of the second laser sintering can be calculated by the following formulas:
PL＝ν·hmρmCm·(T-T0)·S/(τm·t)；
wherein t is dL/ν；
Wherein v is the laser scanning speed; h ismIs the laser penetration depth; rhomIs the density (g/cm) of the material3)；CmThe specific heat capacity (J/(g ℃)) of the material; t is the material laser sintering temperature (DEG C); t is0Preheating temperature (DEG C) of the material; s is the spot area (mm)2)；dLSpot diameter (cm); tau ismAbsorbance (%); t is the spot heating time(s).
In the invention, the laser scanning speed is 1.2-1.5m/s, the powder spreading thickness is 0.10-0.20mm, and the spot diameter is 0.1-0.5 mm.
In the invention, the penetration depth is related to the material density, the material surface reflectivity, the absorptivity and the light wavelength, and the penetration depth is 103Multiple powder spreading thickness.
In the invention, in the calculation process of the first laser sintering power and the second laser sintering power, the light absorption rate is equal to the refractive index, and the refractive index is related to the property of the material, the particle size and the shape of the material.
In the present invention, the material density, the specific heat capacity of the material, the expected sintering temperature of the material, the preheating temperature of the material and the light absorption rate are related to the specific material selected, for example, when the selected material is nylon 66, the material density is 1.13-1.16g/cm3The specific heat capacity is 1.67-1.70J/(g DEG C), the sintering temperature is 250-270 ℃, the preheating temperature is 150-170 ℃ and the light absorption rate is 10-18 percent;
when the selected material is polypropylene, the material density is 0.85-0.92g/cm3The specific heat capacity is 1.92-1.94J/(g DEG C), the sintering temperature is 165- & ltSUB & gt 175 DEG CThe preheating temperature is 150-160 ℃ and the light absorption rate is 18-25 percent;
when the selected material is polycarbonate, the density of the material is 1.20-1.22g/cm3The specific heat capacity is 1.20-1.24J/(g DEG C), the sintering temperature is 190-210 ℃, the preheating temperature is 140-180 ℃ and the light absorption rate is 8-15%;
when the selected material is polystyrene, the density of the material is 1.04-1.08g/cm3The specific heat capacity is 1.30-1.35J/(g DEG C), the sintering temperature is 110-125 ℃, the preheating temperature is 60-90 ℃ and the light absorption rate is 17-20%.
In the invention, if the material is a crystalline polymer, the laser sintering temperature value of the polymer is higher than the melting point value of the polymer. If the material is an amorphous polymer, the laser sintering temperature of the polymer should be above the glass transition temperature of the polymer.
In the invention, because different measuring methods can obtain different data parameters, specific measuring methods are provided for the density, the specific heat capacity, the refractive index and the melting point of the material,
wherein the material density is determined by GB/T1033.1-2008;
the specific heat capacity is measured by DSC method, specifically referring to "comparison of specific heat capacities of substances measured by DSC and MDSC" (Lu Red, et al, Analyzer [ J ], 2011(3): 70-74).
The refractive index is determined by extrapolation, specifically referring to "measurement of refractive index of Polymer" (Shen Min et al, proceedings of the national academy of metrology [ J ], 1997(1): 71-75).
Melting points were determined by GB/T19466.3-2004.
The present invention will be described in detail below by way of examples. In the following examples:
tensile Strength determination according to GB/T1040.2-2006 tensile Properties part 2: test conditions for molded and extruded plastics, ";
impact strength was determined according to GB/T1043.1-2008 Plastic simple Beam impact Performance part 1: the method of non-instrumental impact test is adopted for determination;
the density is determined according to the method of GB 4472-1984 general rules for determining density and relative density of chemical products, wherein the relative density is actual density/theoretical density, and the relative density is the density.
The molding shrinkage is according to ISO 294-4: 2001 injection molding of a sample of a plastic thermoplastic material, part 4 determination of the mold shrinkage.
The density of the nylon 66 raw material is 1.13g/cm3The specific heat capacity is 1.6J/(g DEG C), the light absorption rate is 15 percent, and the melting point is 260 ℃;
the density of the polypropylene raw material is 0.89g/cm3The specific heat capacity is 1.9J/(g DEG C), the light absorption rate is 20 percent, and the melting point is 166 ℃;
the density of the polycarbonate starting material was 1.21g/cm3The specific heat capacity is 1.2J/(kg. DEG C), the light absorption rate is 10 percent, and the glass transition temperature is 148 ℃;
the density of the polystyrene raw material is 1.05g/cm3The specific heat capacity is 1.3J/(g DEG C), the light absorption rate is 18 percent, and the glass transition temperature is 80 ℃;
example 1
(1) According to the laser sintering molding device shown in FIG. 1, polypropylene with the particle size of 200-250 μm is preheated at 160 ℃, polycarbonate with the particle size of 10-30 μm is preheated at 150 ℃, and then polypropylene is placed in a first powder box and polycarbonate is placed in a second powder box;
(2) firstly, controlling the polypropylene in a first powder box to discharge powder to the surface of a working platform 5, moving a paving roller 3 from right to left to pave the powder polypropylene, wherein the powder paving thickness is 0.15mm, forming a polypropylene cut layer, calculating according to a laser sintering power formula to obtain a first laser sintering power of 7.17W by combining the sintering temperature of a first laser, the spot diameter of 0.3mm, the sintering point interval of 0.1mm and the scanning speed of 1.2m/s, and irradiating a laser source 4 on the polypropylene cut layer under the laser power condition to perform first laser sintering on the polypropylene cut layer;
(3) controlling the polycarbonate in the second powder box to discharge powder into gaps of polypropylene of the cutting layer, paving the polycarbonate on the polypropylene cutting layer from left to right by the paving roller 3, wherein the powder paving thickness is 0.10mm, so that the polycarbonate enters the gaps of the polypropylene, calculating a second laser sintering power of 61.55W according to a laser sintering power formula by combining the sintering temperature of a second laser of 200 ℃, the spot diameter of 0.35mm, the sintering point interval of 0.1mm and the scanning speed of 1.5m/s, and irradiating the laser source 4 on the polypropylene cutting layer filled with the polycarbonate under the laser power condition to perform second laser sintering on the polycarbonate;
(4) and (5) descending the working platform 5, repeating the steps (2) and (3), finishing the cross powder paving of the polypropylene powder and the polycarbonate powder for multiple times on the same layer, and performing laser sintering to obtain a finished piece.
The sintered and formed product was tested for tensile strength, impact strength, density and mold shrinkage, and the results are shown in table 1.
Example 2
(1) According to the laser sintering molding device shown in FIG. 1, nylon 66 with the particle size of 250-300 μm is preheated at 168 ℃, polystyrene with the particle size of 30-60 μm is preheated at 80 ℃, and then the nylon 66 is placed in a first powder box, and the polystyrene is placed in a second powder box;
(2) firstly, controlling the nylon 66 in a first powder box to discharge powder to the surface of a working platform 5, moving a paving roller 3 from right to left to pave the nylon 66 with the powder paving thickness of 0.2mm to form a nylon 66 cutting layer, calculating according to a laser sintering power formula to obtain a first laser sintering power of 20.43W by combining the sintering temperature of a first laser, the spot diameter of 0.4mm, the sintering point interval of 0.12mm and the scanning speed of 0.5m/s, and irradiating a laser source 4 on the nylon 66 cutting layer under the laser power condition to perform first laser sintering on the nylon 66 cutting layer;
(3) controlling polystyrene in a second powder box to be discharged into gaps of the cut nylon 66, paving polystyrene on the cut nylon 66 layer from left to right by a paving roller 3, wherein the powder paving thickness is 0.10mm, so that the polystyrene enters the gaps of the nylon 66, calculating to obtain a second laser sintering power of 19.28W according to a laser sintering power formula by combining the sintering temperature of a second laser of 110 ℃, the spot diameter of 0.4mm, the sintering point interval of 0.1mm and the scanning speed of 1.5m/s, and irradiating the laser source 4 on the nylon 66 cut layer filled with the polystyrene under the laser power condition to perform second laser sintering on the polystyrene;
(4) and (3) descending the working platform 5, repeating the steps (2) and (3), finishing the cross powder paving of the same layer of the powder paving nylon 66 and the powder paving polystyrene for multiple times, and performing laser sintering to obtain a finished piece.
The sintered and formed product was tested for tensile strength, impact strength, density and mold shrinkage, and the results are shown in table 1.
Example 3
(1) According to the laser sintering molding device shown in FIG. 1, polypropylene with the particle size of 200-260 μm is preheated at 160 ℃, polystyrene with the particle size of 20-40 μm is preheated at 80 ℃, and then the polypropylene is placed in a first powder box, and the polystyrene is placed in a second powder box;
(2) firstly, controlling the polypropylene in a first powder box to discharge powder to the surface of a working platform 5, moving a paving roller 3 from right to left to pave the powder polypropylene, wherein the powder paving thickness is 0.20mm, forming a polypropylene cut layer, calculating according to a laser sintering power formula to obtain a first laser sintering power of 10.75W by combining the sintering temperature of a first laser of 175 ℃, the spot diameter of 0.3mm, the sintering point interval of 0.1mm and the scanning speed of 1.2m/s, and irradiating a laser source 4 on the polypropylene cut layer under the laser power condition to perform first laser sintering on the polypropylene cut layer;
(3) controlling polystyrene in a second powder box to discharge powder into gaps of polypropylene of a cutting layer, paving polystyrene on the polypropylene cutting layer from left to right by a paving roller 3, wherein the powder paving thickness is 0.15mm, so that the polystyrene enters the gaps of the polypropylene, calculating according to a laser sintering power formula to obtain a second laser sintering power of 25.72W by combining the sintering temperature of a second laser of 120 ℃, the spot diameter of 0.3mm, the sintering point interval of 0.1mm and the scanning speed of 1.2m/s, and irradiating a laser source 4 on the polypropylene cutting layer filled with the polystyrene under the laser power condition to perform second laser sintering on the polystyrene;
(4) and (5) descending the working platform 5, repeating the steps (2) and (3), finishing the cross powder paving of the polypropylene powder and the polystyrene powder for multiple times on the same layer, and performing laser sintering to obtain a finished piece.
The sintered and formed product was tested for tensile strength, impact strength, density and mold shrinkage, and the results are shown in table 1.
Comparative example 1
The laser sintering forming device shown in the figure 1 is used for manufacturing a workpiece, two material powders are completely put into a first powder box, and the operation is as follows:
(1) preheating polypropylene with the particle size of 10-60 mu m at 160 ℃, preheating polycarbonate with the particle size of 200-300 mu m at 140 ℃, uniformly mixing the preheated polypropylene and the polycarbonate, and putting the mixture into a first powder box;
(2) controlling the mixed material of polypropylene and polycarbonate in a first powder box to powder on the surface of a working platform 5, moving a paving roller 3 from right to left to pave the powder, wherein the powder paving thickness is 0.15mm, and forming a polypropylene and polycarbonate mixed cut layer, wherein a laser source 4 irradiates on the polypropylene and polycarbonate mixed cut layer under the conditions that the sintering temperature of the laser source is 250 ℃, the spot diameter is 0.3mm, the interval of sintering points is 0.1mm, the scanning speed is 1.2m/s and the laser sintering power is about 20W, so as to perform laser sintering on the polypropylene and polycarbonate mixed cut layer;
(3) and (5) descending the working platform 5, repeating the step (2), finishing multiple times of powder paving of the polypropylene and polycarbonate mixed material, and performing laser sintering to obtain a finished piece.
The sintered and formed articles were tested for tensile strength, impact strength, compactness and mold shrinkage, and the results are shown in table 1.
Comparative example 2
The laser sintering forming device shown in fig. 1 is used for manufacturing a workpiece, the particle size ranges of the two material powders are the same, and the specific operations are as follows:
(1) preheating polypropylene with the particle size of 10-200 mu m at 160 ℃, preheating polycarbonate with the particle size of 10-200 mu m at 140 ℃, and then placing the polypropylene in a first powder box and the polycarbonate in a second powder box;
(2) firstly, controlling the polypropylene in a first powder box to discharge powder to the surface of a working platform 5, moving a paving roller 3 from right to left to pave the polypropylene, wherein the powder paving thickness is 0.15mm, forming a polypropylene cut layer, calculating according to a laser sintering power formula to obtain a first laser sintering power of 7.17W by combining the sintering temperature of first laser of 170 ℃, the spot diameter of 0.3mm, the interval of sintering points of 0.1mm and the scanning speed of 1.2m/s, and irradiating a laser source 4 on the polypropylene cut layer under the laser power condition to perform first laser sintering on the polypropylene cut layer;
(3) controlling the polycarbonate in a second powder box to discharge powder to the surface of the cut layer polypropylene, paving the powder polycarbonate on the cut layer polypropylene by a paving roller 3 from left to right, wherein the powder paving thickness is 0.15mm, forming the cut layer polycarbonate on the surface of the cut layer polypropylene, calculating a second laser sintering power of 73.86W according to a laser sintering power formula by combining the sintering temperature of a second laser of 200 ℃, the spot diameter of 0.3mm, the sintering point interval of 0.1mm and the scanning speed of 1.2m/s, and irradiating a light source 4 on the cut layer of the polycarbonate under the laser power condition to perform second laser sintering on the polycarbonate;
(4) and (5) descending the working platform 5, repeating the steps (2) and (3), finishing the cross powder paving of the polypropylene powder paving and the polycarbonate powder paving for multiple times, and performing laser sintering to obtain a finished piece.
The sintered and formed product was tested for tensile strength, impact strength, density and mold shrinkage, and the results are shown in table 1.
TABLE 1
As can be seen from the results in Table 1, the tensile strength of the article of example 1 was 6.73MPa and the impact strength was 5.31MJ/m2The density was 0.734 and the mold shrinkage was 0.27%. In comparative example 1, two materials having different powder particle size ranges were mixed and put into the same powder box to obtain a product having a tensile strength of 2.53MPa and an impact strength of 3.44MJ/m2The density was 0.392 and the molding shrinkage was 2.98%, in comparative example 2, two materials having the same particle size range were added to the two powder boxes of the present invention, respectively, to obtain the tensile strength of the articleThe degree is 3.32MPa, and the impact strength is 2.19MJ/m2The compactness is 0.410, and the molding shrinkage is 1.66%, so that the product obtained by the laser sintering forming device and the forming method provided by the invention has obviously better effects on tensile strength, impact strength, compactness and molding shrinkage.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (10)
1. A laser sintering forming device comprises a powder box system, a light source system and a working platform system, wherein the powder box system comprises a first powder box (1) and a second powder box (2), the light source system comprises a laser source (4), and the working platform system comprises a working platform (5) and a paving roller (3);
the first powder box (1) and the second powder box (2) are positioned right above the working platform (5) and are used for containing different material powders with different particle sizes;
the laser source (4) is output by a light source system and is used for laser sintering powder;
the paving roller (3) is located above the working platform (5) and moves for paving powder.
2. The device according to claim 1, wherein the work platform (5) further comprises a controller for controlling the work platform (5) to move vertically up and down.
3. A laser sintering molding method of a composite material, which comprises subjecting at least two different material powders different in particle size to multiple repetitions of cross-powdering and laser sintering on the laser sintering molding apparatus described in claim 1 or 2.
4. The method of claim 3, wherein the material powder comprises material A and material B, the material A being selected from at least one of a first polymer, a first metal, and a first ceramic; the material B is selected from at least one of a second polymer, a second metal and a second ceramic.
5. The method as claimed in claim 4, wherein the minimum value of the particle size of the material A is larger than the maximum value of the particle size of the material B, preferably, the particle size of the powder of the material A is 200-300 μm, and the particle size of the powder of the material B is 10-60 μm.
6. The method of claim 5, wherein the method further comprises:
placing a material A in a first powder box (1), and placing a material B in a second powder box (2);
(II) controlling the powder discharge of the material A to the surface of a working platform (5), moving a spreading roller (3) to spread the powder A, forming a cutting layer A on the surface of the working platform (5), and irradiating the cutting layer A by using a laser source (4) to perform first laser sintering;
(III) controlling the material B to powder out of the gap of the cut layer A, moving a paving roller (3) to pave the powder B, filling the gap of the cut layer A with the material B, and irradiating the material B with a laser source (4) to perform second laser sintering;
and (IV) descending the working platform (5), repeating the steps (II) and (III), finishing the same-layer cross powder paving of the powder paving A and the powder paving B for multiple times, and performing laser sintering to obtain a finished piece.
7. Method according to claim 6, wherein the material A and the material B are preheated at respective preheating temperatures before being placed in the first powder bin (1) and the material B in the second powder bin (2).
8. The method of claim 7, wherein the pre-heat temperature is less than a laser sintering temperature.
9. The method of claim 6, wherein the power of the first laser sintering and the power of the second laser sintering satisfy the following formula:
PL＝ν·hmρmCm·(T-T0)·S/(τm·t)；
wherein t is dL/ν；
Wherein v is the laser scanning speed; h ismFor laser penetration depth, 103Multiple powder spreading thickness; rhomIs the density (g/cm) of the material3)；CmThe specific heat capacity (J/(g ℃)) of the material; t is the material laser sintering temperature (DEG C); t is0Preheating temperature (DEG C) of the material; s is the spot area (mm)2)；dLSpot diameter (mm); tau ismIs the absorbance; t is the spot heating time(s).
10. The method of claim 9, wherein the laser scanning speed is 0.5-1.5m/s, the laydown thickness is 0.1-0.2mm, and the spot diameter is 0.3-0.4 mm.
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