A method for preparing large complex structure metal parts

Abstract

The present invention belongs to the field of metal casting technology, and relates to a method for preparing large-scale complex structure metal parts. For the forming of large-scale complex structure metal parts, starting from the four dimensions of wall thickness, microchannel tube thickness, lattice structure rod diameter and porosity, the parts are divided into two parts according to dimensional accuracy, namely the overall structure part and the complex lattice structure. The wax model of the overall structure is prepared by selective laser sintering; the wax model of the complex structure is prepared by digital light processing. The present invention makes full use of the advantages of selective laser sintering technology and digital light processing technology, greatly improves the production size, surface quality and precision of parts, can cast larger parts with complex lattice structures, improves the production efficiency of the casting industry, and is a major advancement in precision casting technology.

Description

Technical Field

[0001] The invention relates to the technical field of metal casting, and in particular to a method for preparing large-scale metal parts with complex structures. Background Art

[0002] When using material molding technology with additive manufacturing technology as the core to prepare large precision parts, the preparation of wax models often needs to face the problem of weighing accuracy and cost between different technologies. The traditional use of a single additive preparation method has its own defects. For example, when faced with the requirements for preparing parts for aerospace, medical implants, automobiles and mold manufacturing, these parts are often complex lattice structures with thin walls, fine lattices and microchannels in some parts, while other parts have overall structures with regular geometric features. If the selective laser sintering (SLS) process is directly used for processing, it will lead to higher costs and lower efficiency, and the complex lattice structure cannot be accurately prepared. If digital light processing (DLP) is used directly for preparation, it will be limited by the current equipment process level, and it is impossible to prepare large wax models, and the cost is high. Therefore, it is necessary to develop a new manufacturing process for large complex lattice structures to solve the above technical problems. Summary of the invention

[0003] In order to solve the problems existing in the prior art, the main purpose of the present invention is to provide a method for preparing large-scale complex structure metal parts.

[0004] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0005] A method for preparing large complex structure metal parts, comprising the following steps:

[0006] S1, using selective laser sintering technology and digital light processing technology to prepare wax models;

[0007] S2, wax mold casting to obtain a preform, the preform is heated to obtain a gypsum casting;

[0008] S3. Casting to obtain large and complex structural metal parts.

[0009] As a preferred embodiment of the method for preparing a large complex structure metal component of the present invention, step S1 specifically comprises:

[0010] S11. 3D modeling of large and complex metal parts: Design and model large and complex metal parts in 3D modeling software;

[0011] S12, 3D model partition cutting: according to the dimensional accuracy of the 3D model, the model is divided into a complex lattice structure and an overall structure from four dimensions: wall thickness, microchannel tube thickness, lattice structure rod diameter and porosity, and the 3D model is divided into a complex lattice structure model and an overall structure model;

[0012] S13, importing the model into the printing software, slicing and then printing to prepare a wax model, wherein the complex lattice structure model is imported into the digital light processing printer, and the overall structure model is imported into the selected area laser sintering printer;

[0013] S14. Wax model interface bonding: Use sandpaper to polish the wax model interface that needs to be bonded, and then use alcohol to clean it to ensure that the interface is clean and remove impurities that may affect the bonding. Then use acetone adhesive to evenly apply it on the wax model interface that needs to be bonded, and apply appropriate pressure. Then place the bonded wax model in a well-ventilated environment to dry, so that the acetone in the adhesive can evaporate, complete the bonding process, and obtain a complete wax model.

[0014] As a preferred embodiment of the method for preparing large-scale complex structure metal parts described in the present invention, in which: in the step S12, the part with wall thickness ≤3mm, microchannel tube thickness ≤4mm, lattice structure rod diameter ≤5mm or porosity ≥65% is classified as a complex lattice structure, and the rest is an integral structure.

[0015] As a preferred embodiment of the method for preparing large complex structure metal parts described in the present invention, step S12 also includes reconstruction and optimization of the model size after segmentation: along the segmentation interface of the overall structure model, the thickness is uniformly increased by 1 to 6 mm to reconstruct the model.

[0016] As a preferred embodiment of the method for preparing large-scale complex structure metal parts described in the present invention, in step S13, the investment material used for selective laser sintering is environmentally friendly composite wax powder, and the investment material used for digital light processing is photosensitive resin.

[0017] As a preferred embodiment of the method for preparing large-scale complex structure metal parts described in the present invention, in step S14, 240 mesh, 400 mesh, 600 mesh, 800 mesh, 1200 mesh, 1500 mesh, 2000 mesh, and 7000 mesh sandpaper are used for grinding in sequence, and each mesh is ground for 5 minutes.

[0018] As a preferred embodiment of the method for preparing large-scale complex structure metal parts described in the present invention, in which: in the step S2, vacuum plaster is cast on the complete wax model, and a preform is obtained after the gypsum solidifies, the preform is dried, and then heated in a wax model baking furnace to obtain a gypsum casting.

[0019] As a preferred embodiment of the method for preparing large-scale complex structure metal parts described in the present invention, in which: in the step S2, the mass ratio of bauxite to hemihydrate gypsum in the gypsum casting raw material is 1:1, and the water-solid ratio is 45mL:100g.

[0020] As a preferred embodiment of the method for preparing large-scale complex structure metal parts described in the present invention, in step S2, the heating process is: heating from room temperature to 180°C for 120 minutes, then heating from 180°C to 250°C for 120 minutes, then heating from 250°C to 400°C for 60 minutes, then heating from 400°C to 900°C for 210 minutes.

[0021] As a preferred embodiment of the method for preparing large-scale complex structure metal parts described in the present invention, in which: in the step S3, the metal material to be cast is pretreated, and then a vacuum pressure casting machine is used to heat the metal material in a vacuum furnace and press it into a gypsum mold, and the gypsum is cleaned to obtain the large-scale complex structure metal parts.

[0022] The beneficial effects of the present invention are as follows:

[0023] The present invention proposes a method for preparing large-scale complex structure metal parts. Aiming at the forming of large-scale complex structure metal parts, starting from the four dimensions of wall thickness, microchannel tube thickness, lattice structure rod diameter and porosity, the parts are divided into two parts according to dimensional accuracy, namely the overall structure part and the complex lattice structure. The wax model of the overall structure is prepared by selective laser sintering; the wax model of the complex structure is prepared by digital light processing. The present invention makes full use of the advantages of selective laser sintering technology and digital light processing technology, greatly improves the production size, surface quality and precision of parts, can cast larger parts with complex lattice structures, improves the production efficiency of the casting industry, and is a major advancement in precision casting technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0025] Figure 1 It is a schematic diagram of the process of the method for preparing large-scale complex structure metal parts of the present invention.

[0026] Figure 2 This is a schematic diagram of the model constructed in Example 1 of the present invention.

[0027] Figure 3 Schematic diagram of the complex lattice structure model after segmentation in Example 1 of the present invention.

[0028] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0029] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] According to one aspect of the present invention, the present invention provides the following technical solution:

[0031] like Figure 1 As shown, a method for preparing large complex structure metal parts includes the following steps:

[0032] S1, using selective laser sintering technology and digital light processing technology to prepare wax models;

[0033] S2, wax mold casting to obtain a preform, the preform is heated to obtain a gypsum casting;

[0034] S3. Casting to obtain large and complex structural metal parts.

[0035] Preferably, the step S1 specifically includes:

[0036] S11. 3D modeling of large and complex metal parts: Design and model large and complex metal parts in 3D modeling software;

[0037] S12, 3D model partition cutting: according to the dimensional accuracy of the 3D model, the model is divided into a complex lattice structure and an overall structure from four dimensions: wall thickness, microchannel tube thickness, lattice structure rod diameter and porosity, and the 3D model is divided into a complex lattice structure model and an overall structure model;

[0038] S13, importing the model into the printing software, slicing and then printing to prepare a wax model, wherein the complex lattice structure model is imported into the digital light processing printer, and the overall structure model is imported into the selected area laser sintering printer;

[0039] S14. Wax model interface bonding: Use sandpaper to polish the wax model interface that needs to be bonded, and then use alcohol to clean it to ensure that the interface is clean and remove impurities that may affect the bonding. Then use acetone adhesive to evenly apply it on the wax model interface that needs to be bonded, and apply appropriate pressure. Then place the bonded wax model in a well-ventilated environment to dry, so that the acetone in the adhesive can evaporate, complete the bonding process, and obtain a complete wax model.

[0040] Preferably, in step S12, the part with wall thickness ≤3 mm, microchannel tube thickness ≤4 mm, lattice structure rod diameter ≤5 mm or porosity ≥65% is classified as a complex lattice structure, and the rest is an integral structure.

[0041] Preferably, the step S12 further comprises reconstructing and optimizing the size of the model after segmentation: along the segmentation interface of the overall structure model, the thickness is uniformly increased by 1 to 6 mm to reconstruct the model.

[0042] Preferably, in step S13, the molten pattern material used for selective laser sintering is an environmentally friendly composite wax powder (with EVA3 wax powder as the base material, 0.5wt% carbon black, 2wt% sodium dodecylbenzene sulfonate and 0.5wt% white carbon black as additives), and the molten pattern material used for digital light processing is a photosensitive resin (prepared with acrylic resin prepolymer, monomer diluent, photoinitiator, etc.).

[0043] Preferably, in step S14, 240 mesh, 400 mesh, 600 mesh, 800 mesh, 1200 mesh, 1500 mesh, 2000 mesh and 7000 mesh sandpaper are used for grinding in sequence, and each mesh is ground for 5 minutes.

[0044] Preferably, in step S2, vacuum plaster casting is performed on the complete wax model, and a preform is obtained after the gypsum solidifies. The preform is dried and then heated in a wax model baking furnace to obtain a gypsum casting.

[0045] Preferably, in step S2, the mass ratio of bauxite to hemihydrate gypsum in the gypsum casting raw material is 1:1, and the water-solid ratio is 45mL:100g.

[0046] Preferably, in step S2, the heating process is: heating from room temperature to 180°C for 120 minutes, then heating from 180°C to 250°C for 120 minutes, then heating from 250°C to 400°C for 60 minutes, then heating from 400°C to 900°C for 210 minutes.

[0047] Preferably, in step S3, the metal material to be cast is pretreated, and then a vacuum pressure casting machine is used to heat the metal material in a vacuum furnace and press it into a gypsum mold, and the gypsum is cleaned to obtain large complex structure metal parts.

[0048] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0049] Example 1

[0050] This embodiment provides a method for preparing a large complex structure metal component, comprising the following steps:

[0051] S1, using selective laser sintering technology and digital light processing technology to prepare wax models;

[0052] The step S1 specifically includes:

[0053] S11. 3D modeling of large complex structure metal parts: In 3D modeling software (solidworks), design and model large complex structure metal parts models (such as Figure 2 As shown, Figure 2 (a) is the left view of the component. Figure 2 (b) is the top view of the component. Figure 2 (c) is the right view of the component. Figure 2 (d) is the front view of the component. Figure 2 (e) is the bottom view of the component. Figure 2 (f) is the rear view of the component).

[0054] S12, 3D model partition cutting: According to the dimensional accuracy of the 3D model, from the four dimensions of wall thickness, microfluidic tube thickness, lattice structure rod diameter and porosity, the parts with wall thickness ≤3mm, microfluidic tube thickness ≤4mm, lattice structure rod diameter ≤5mm or porosity ≥65% are classified as complex lattice structures (such as Figure 3 As shown, Figure 3 (a)-(c) are pipeline 1, pipeline 2, and pipeline 3 respectively. Figure 3 (d) is the blade), and the rest is the overall structure. The 3D model is divided into a complex lattice structure model and an overall structure model. The size of the model is reconstructed and optimized after segmentation: along the segmentation interface of the overall structure model, the thickness is uniformly increased by 2 mm to reconstruct the model.

[0055] S13, import the model into the printing software, slice it and then print it to prepare the wax model, wherein the complex lattice structure model is imported into the digital light processing printer, and the overall structure model is imported into the selective laser sintering printer. The melting mold material used for the selective laser sintering is an environmentally friendly composite wax powder (using EVA3 wax powder as the base material, adding 0.5wt% carbon black, 2wt% sodium dodecylbenzene sulfonate and 0.5wt% white carbon black as additives), and the melting mold material used for digital light processing is a photosensitive resin (photosensitizer (2,4,6-trimethylol Benzoyl-diphenylphosphine oxide), two diluents (isodecyl acrylate and isobornyl methacrylate), two oligomers (pure acrylate and polyurethane acrylate), prepare photosensitive resin solution, photosensitive resin parameters: bending modulus 1.192~2.525; bending strength 49~58MPa; tensile strength 42~62MPa; thermal deformation temperature 65℃); digital light processing printing process parameters: first layer exposure time 65s, layer thickness 0.05mm, other layers exposure time 7s. Selective laser sintering printing process parameters: laser scanning speed 7600mm / s, layer thickness 0.1mm, preheating temperature 136℃, laser power 20W.

[0056] S14. Wax model interface bonding: Use sandpaper to polish the wax model interface that needs to be bonded. Use 240 mesh, 400 mesh, 600 mesh, 800 mesh, 1200 mesh, 1500 mesh, 2000 mesh, and 7000 mesh sandpaper to polish in sequence, and polish each mesh for 5 minutes; then use alcohol to clean it to ensure that the interface is clean and remove impurities that may affect the bonding. Then use acetone adhesive to evenly apply it on the wax model interface that needs to be bonded, and apply appropriate pressure. Then place the bonded wax model in a well-ventilated environment to dry for 12 hours to allow the acetone in the adhesive to evaporate, complete the bonding process, and obtain a complete wax model.

[0057] S2. Vacuum gypsum casting is performed on the complete wax model. After the gypsum solidifies, a preform is obtained. The preform is air-dried for 7 natural days, and then heated in a wax model baking furnace to obtain a gypsum casting. The mass ratio of bauxite to hemihydrate gypsum in the gypsum casting raw materials is 1:1, and the water-solid ratio is 45mL:100g. The heating process is: heating from room temperature to 180°C after 120min, then heating from 180°C to 250°C after 120min, then heating from 250°C to 400°C after 60min, and then heating from 400°C to 900°C after 210min.

[0058] S3. Pre-treat the ZL702 alloy to be cast, and then use a vacuum pressure casting machine to heat the ZL702 alloy in a vacuum furnace and press it into a gypsum mold. The die-casting speed is 5m / s, the mold preheating temperature is 200℃, the vacuum degree is 15kPa, and the melt temperature is 750℃; after cleaning the gypsum, large complex structure metal parts are obtained.

[0059] The present invention aims at the forming of large-scale complex structure metal parts. Starting from the four dimensions of wall thickness, microchannel tube thickness, lattice structure rod diameter and porosity, the parts are divided into two parts according to dimensional accuracy, namely the overall structure part and the complex lattice structure. The wax model of the overall structure is prepared by selective laser sintering; the wax model of the complex structure is prepared by digital light processing. The present invention makes full use of the advantages of selective laser sintering technology and digital light processing technology, greatly improves the production size, surface quality and accuracy of parts, can cast larger parts with complex lattice structures, improves the production efficiency of the casting industry, and is a major advancement in precision casting technology.

[0060] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing large complex structure metal parts, characterized in that: The steps include: S1. Use selective laser sintering technology and digital light processing technology to prepare wax models, including: S11. 3D modeling of large and complex metal parts: Design and model large and complex metal parts in 3D modeling software; S12. Partition cutting of three-dimensional model: According to the dimensional accuracy of the three-dimensional model, the model is divided into complex lattice structure and overall structure from four dimensions: wall thickness, microfluidic tube thickness, lattice structure rod diameter and porosity. The parts with wall thickness ≤3mm, microfluidic tube thickness ≤4mm, lattice structure rod diameter ≤5mm or porosity ≥65% are classified as complex lattice structure, and the rest are overall structure; the three-dimensional model is divided into complex lattice structure model and overall structure model, and the reconstruction and optimization of the model size after division: along the division interface of the overall structure model, the thickness is uniformly increased by 1~6mm to reconstruct the model; S13, importing the model into the printing software, slicing and then printing to prepare a wax model, wherein the complex lattice structure model is imported into the digital light processing printer, and the overall structure model is imported into the selected area laser sintering printer; S14, wax model interface bonding: use sandpaper to polish the wax model interface to be bonded, then use alcohol to clean it to ensure that the interface is clean and remove impurities that may affect bonding, then use acetone adhesive to evenly apply it on the wax model interface to be bonded, and apply appropriate pressure, then place the bonded wax model in a well-ventilated environment to dry, so that the acetone in the adhesive evaporates, complete the bonding process, and obtain a complete wax model; S2, wax mold casting to obtain a preform, the preform is heated to obtain a gypsum casting; the heating process is: heating from room temperature to 180°C for 120 minutes, then heating from 180°C to 250°C for 120 minutes, then heating from 250°C to 400°C for 60 minutes, then heating from 400°C to 900°C for 210 minutes; S3. Casting to obtain large and complex structural metal parts.

2. The method for preparing large complex structure metal parts according to claim 1, characterized in that: In the step S13, the investment material used for the selective laser sintering is an environmentally friendly composite wax powder, and the investment material used for the digital light processing is a photosensitive resin.

3. The method for preparing large complex structure metal parts according to claim 1, characterized in that: In the step S14, 240 mesh, 400 mesh, 600 mesh, 800 mesh, 1200 mesh, 1500 mesh, 2000 mesh and 7000 mesh sandpaper are used for grinding in sequence, and each mesh is ground for 5 minutes.

4. The method for preparing large complex structure metal parts according to claim 1, characterized in that: In the step S2, vacuum plaster is poured on the complete wax model, and a preform is obtained after the plaster solidifies. The preform is dried and then heated in a wax model baking furnace to obtain a plaster casting.

5. The method for preparing large complex structure metal parts according to claim 1, characterized in that: In the step S2, the mass ratio of bauxite to hemihydrate gypsum in the gypsum casting raw material is 1:1, and the water-solid ratio is 45mL:100g.

6. The method for preparing large complex structure metal parts according to claim 1, characterized in that: In step S3, the metal material to be cast is pretreated, and then a vacuum pressure casting machine is used to heat the metal material in a vacuum furnace and press it into a gypsum mold, and the gypsum is cleaned to obtain large complex structure metal parts.

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