Liquid abrasive for additive manufacturing of profiled parts and method for its preparation

Abstract

The application provides a liquid abrasive for additive manufacturing of special-shaped parts, which comprises the following components in parts by weight: polished abrasive grains: 30-45 parts, acrylate: 50-65 parts, photoinitiator: 0.5-1 part, dispersant: 1-2 parts, PH regulator: 1-2 parts. The liquid abrasive for additive manufacturing of special-shaped parts has good surface removal, and long-chain molecules are generated through photopolymerization. The entanglement between the long-chain molecules and the winding effect on the processing surface can generate a certain flow resistance, so that the abrasive grains in the abrasive repeatedly process the surface, and good removal efficiency and universality are obtained. By changing the length of the ultraviolet irradiation time, the ratio of long-chain molecules to short-chain molecules in the abrasive can be controlled, so that abrasives with different viscoelasticity can be obtained to meet the requirements of different materials and working conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polishing abrasives, in particular to a liquid abrasive for additive manufacturing of special-shaped parts. BACKGROUND

[0002] Now with the progress of additive manufacturing technology, the technology is popular in the field of processing, especially in the field of special-shaped part forming; additive manufacturing obtains target parts through layer-by-layer stacking of materials, and often the surface quality is poor, which needs subsequent polishing processing. However, for the processing of complex special-shaped components formed by additive manufacturing, the traditional polishing processing method usually cannot be processed due to poor accessibility.

[0003] The polishing liquid is in liquid state and has good accessibility, but chemical polishing has high toxicity and is not suitable for polishing processing of parts such as bone scaffolds and dental crowns. Therefore, a safe polishing abrasive is urgently needed to realize mechanical polishing of parts; and the abrasive with too much fluidity often has insufficient contact force and contact time between abrasive particles and workpiece surface, resulting in poor polishing effect. SUMMARY

[0004] The purpose of the present application is to overcome and supplement the deficiencies in the prior art, and to provide a liquid abrasive for additive manufacturing of special-shaped parts. The liquid abrasive has better accessibility and can better process complex structures such as porous structures, thin-walled structures, etc.

[0005] The technical solution adopted by the present application is:

[0006] A liquid abrasive for additive manufacturing of special-shaped parts, wherein: by weight, the following components are included:

[0007] Polishing abrasive: 30-45 parts;

[0008] Acrylate: 50-65 parts;

[0009] Photoinitiator: 0.5-1 part;

[0010] Dispersant: 1-2 parts;

[0011] PH adjuster: 1-2 parts.

[0012] Preferably, the liquid abrasive for additive manufacturing of special-shaped parts, wherein: the polishing abrasive is selected from one or more of tetragonal silicon nitride, alumina, boron nitride and silicon carbide with a particle size of 5-30um. The light refraction index and light absorption rate of non-oxide ceramic powder are high, which can act as a polymerization inhibitor in the liquid viscoelastic abrasive, inhibiting the rapid curing of the abrasive during use under ultraviolet light, ensuring the stability of the liquid abrasive.

[0013] Preferably, the liquid abrasive for additive manufacturing of special-shaped parts, wherein: the acrylate is a monofunctional acrylate.

[0014] Preferably, the liquid abrasive for additive manufacturing of special-shaped parts, wherein: the monofunctional acrylate is selected from one or more of beta-hydroxyethyl methacrylate, isobornyl acrylate, beta-carboxyethyl acrylate and 2-phenoxyethyl acrylate. The monofunctional monomer has a lower crosslinking density, and can reduce the curing speed, and better control the ratio of long and short chains by controlling the UV irradiation time to obtain different viscoelastic abrasives.

[0015] Preferably, the liquid abrasive for additive manufacturing of special-shaped parts, wherein: the dispersant is selected from one of sodium polyacrylate, triamine citrate, and polyacrylamide. The dispersant reduces the surface energy of the abrasive particles, and makes the abrasive particles uniformly distributed in the abrasive.

[0016] Preferably, the liquid abrasive for additive manufacturing of special-shaped parts, wherein: the PH agent regulator is selected from one of citric acid, aliphatic amine and aromatic amine. The PH agent regulator selects different PH agents to adjust the acidity and alkalinity of the abrasive according to the different abrasive powders and the properties of the processed parts.

[0017] A preparation method of a liquid abrasive for additive manufacturing of special-shaped parts, comprising the following steps:

[0018] S1, according to the proportion of each raw material, the polishing abrasive, acrylate, photoinitiator, dispersant, PH regulator are weighed, the acrylate and photoinitiator are mixed and vacuum stirred to obtain an acrylic resin;

[0019] S2, the polishing abrasive, dispersant and PH regulator are added into the acrylic resin, and the liquid abrasive is obtained after vacuum stirring;

[0020] S3, the liquid abrasive is placed in a transparent container and irradiated with a dot matrix ultraviolet light source for a certain time;

[0021] S4, the liquid abrasive in step S3 is vacuum stirred to obtain a liquid viscoelastic abrasive.

[0022] Preferably, the preparation method of the liquid abrasive for additive manufacturing of special-shaped parts, wherein: the wavelength of the dot matrix ultraviolet light source in step S3 is 250-405nm, and the time is 20S-60S.

[0023] The liquid abrasive material for additive manufacturing of special-shaped parts has better entering property, can better process complex structures, such as porous structures, thin-walled structures and the like.

[0024] Preferably, the method for preparing the liquid abrasive material for additive manufacturing of special-shaped parts, wherein: the vacuum degree of the vacuum stirring in the step S1, the step S2 and the step S4 is 0.06-0.08 MPa, the stirring speed is 900-1000 rpm, and the stirring time is 5-15 min.

[0025] The liquid abrasive material for additive manufacturing of special-shaped parts is in liquid state, has good entering property, and can cross-link and polymerize part of short-chain molecules in the abrasive material to generate long molecular chains in response to the action of the dot array ultraviolet light, so that the abrasive material has certain viscoelasticity.

[0026] Advantages of the present application:

[0027] (1) The liquid abrasive material for additive manufacturing of special-shaped parts has better entering property, can better process complex structures, such as porous structures, thin-walled structures and the like.

[0028] (2) The liquid abrasive material for additive manufacturing of special-shaped parts has good surface removal property, and long-chain molecules are generated through photopolymerization, the entanglement between the long-chain molecules and the winding effect on the processed surface can produce certain flow resistance, so that the abrasive particles repeatedly process the surface to obtain good removal efficiency.

[0029] (3) The liquid abrasive material for additive manufacturing of special-shaped parts has good universality, and the proportion of long-chain molecules and short-chain molecules in the abrasive material can be controlled by changing the length of ultraviolet irradiation time, so that abrasive materials with different viscoelasticity are obtained to meet the requirements of different materials and working conditions. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The process diagram for controlling the viscoelasticity of the abrasive material.

[0031] Figure 2 A special-shaped part formed by using a light curing technology.

[0032] Figure 3 The liquid abrasive of the present application is used to polish the micro-holes of the special-shaped part.

[0033] Figure 4 The surface condition of the micro-hole flow channel of the special-shaped part before and after polishing by the abrasive of Example 4 is compared. DETAILED DESCRIPTION

[0034] The present application will be further described below in conjunction with specific drawings and examples.

[0035] Figure 1 A schematic diagram of the process for regulating the viscoelasticity of the abrasive, Figure 2 As shown, the micro-hole flow channel of the special-shaped part formed by using a light curing technology is relatively rough and needs further polishing processing. However, it is difficult to polish the special-shaped flow channel hole with too small diameter. For this purpose, as shown, Figure 3 The polishing operation of the micro-hole is carried out by using the special abrasive of the present application. The polishing method is to load the part into the clamp of the industrial finishing machine, and through the rotation of the main shaft and the self-rotation of the clamp, the abrasive continuously scratches and inserts the surface of the part to obtain the polishing effect.

[0036] Example 1

[0037] A liquid abrasive for additive manufacturing of a special-shaped part, wherein: by weight parts, it comprises the following components: silicon nitride abrasive particles: 35 parts, acrylic ester (methyl methacrylate-β-hydroxyethyl ester): 60 parts, photoinitiator (TPO): 1 part, dispersant (sodium polyacrylate): 2 parts, PH agent (citric acid): 2 parts.

[0038] The preparation method of the liquid abrasive for additive manufacturing of a special-shaped part of Example 1 comprises the following steps:

[0039] S1, mix the acrylic ester and the photoinitiator in proportion, and stir under vacuum stirring at 0.08 mpa, 900 rpm for 15 min to obtain a uniform acrylic resin;

[0040] S2, add appropriate amount of polishing abrasive, dispersant and PH regulator to the above acrylic resin, and stir under vacuum stirring at 0.06 mpa, 1000 rpm for 15 min to obtain a liquid abrasive after vacuum stirring.

[0041] Example 2

[0042] The liquid abrasive of Example 2 is the same as Example 1 in terms of each component and weight parts.

[0043] The preparation method of the liquid abrasive for additive manufacturing of a special-shaped part of Example 2 comprises the following steps:

[0044] S1, mix acrylic ester and photoinitiator in proportion, stir for 15 min under vacuum stirring at 0.08 mpa, 900 rpm to obtain uniform acrylic resin;

[0045] S2, add appropriate amount of polishing abrasive, dispersant and PH regulator to the above acrylic resin, stir for 15 min under vacuum stirring at 0.06 mpa, 1000 rpm to obtain liquid abrasive after vacuum stirring;

[0046] S3, place the liquid abrasive in step S2 in a transparent container and irradiate with a dot matrix ultraviolet light source with a wavelength of 405 nm for 20 s;

[0047] S4, stir the abrasive in step S3 under vacuum stirring at 0.06 mpa, 1000 rpm for 5 min to obtain liquid viscoelastic abrasive.

[0048] Example 3

[0049] The components and weight parts of the liquid abrasive of example 3 are the same as those of example 1.

[0050] The preparation method of the liquid abrasive for additive manufacturing of special-shaped parts of example 3 comprises the following steps:

[0051] S1, mix acrylic ester and photoinitiator in proportion, stir for 15 min under vacuum stirring to obtain uniform acrylic resin;

[0052] S2, add appropriate amount of polishing abrasive, dispersant and PH regulator to the above acrylic resin, stir for 15 min under vacuum stirring to obtain liquid abrasive after vacuum stirring;

[0053] S3, place the liquid abrasive in step S2 in a transparent container and irradiate with a dot matrix ultraviolet light source with a wavelength of 405 nm for 60 s;

[0054] S4, stir the abrasive in step S3 under vacuum stirring at 0.06 mpa, 1000 rpm for 5 min to obtain liquid viscoelastic abrasive.

[0055] Example 4

[0056] A liquid abrasive for additive manufacturing of special-shaped parts, comprising the following components by weight: silicon nitride abrasive: 30 parts, acrylic ester (β-hydroxyethyl methacrylate): 65 parts, photoinitiator (TPO): 1 part, dispersant (sodium polyacrylate): 2 parts, PH agent (citric acid): 2 parts,

[0057] The preparation method of the liquid abrasive for additive manufacturing of special-shaped parts of example 4 comprises the following steps:

[0058] S1, mix the acrylate and the photoinitiator in proportion, and stir under vacuum stirring at 0.08mpa, 900rpm for 15min to obtain the uniform acrylate resin;

[0059] S2, add proper amount of polishing abrasive, dispersant and PH regulator into the acrylate resin, and stir under vacuum stirring at 0.06mpa, 1000rpm for 15min to obtain the liquid abrasive after vacuum stirring;

[0060] S3, place the liquid abrasive in step S2 into a transparent container, and irradiate with a dot UV light source with wavelength of 405nm for 20s;

[0061] S4, stir the abrasive in step S3 under vacuum stirring at 0.06mpa, 1000rpm for 5min to obtain the liquid viscoelastic abrasive.

[0062] Measure the liquid abrasive in above examples 1-4 with viscosity agent respectively, and the viscosity coefficient obtained is shown in table 1.

[0063] Table 1: viscosity coefficient comparison table of the abrasive in examples 1-4

[0064] Example Viscosity (in mPa-s, 25°C) Example 1 103.5 Example 2 254.6 Example 3 459.7 Example 4 238.6

[0065] As can be seen from table 1, the viscosity of the abrasive is obviously changed after the UV irradiation for different time, the controllable adjustment of the viscosity of the abrasive is realized, in addition, the viscoelasticity of the abrasive can also be slightly adjusted by controlling the mass fraction of the abrasive particles, which proves the controllability of the viscoelasticity of the liquid abrasive.

[0066] As Figure 4 The surface condition comparison chart of the abrasive prepared in example 4 before and after polishing the micro-porous flow channel, after polishing with the abrasive, the surface roughness of the additive manufacturing part is reduced, and the surface finish is obviously improved, which proves the excellent surface removal property of the liquid abrasive.

[0067] The present application provides a kind of liquid abrasive for the polishing problem of additive manufacturing special-shaped parts, utilizes the flowability of abrasive and the entanglement of long chain molecule, the abrasive has good access and removal, provides a kind of simple process, low cost method for the polishing of additive manufacturing special-shaped parts.

[0068] Finally, it should be explained that the above specific embodiments are only used to illustrate the technical solutions of the present application but not limit, although the present application is described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalent replaced without departing from the spirit and scope of the technical solutions of the present application, which should be covered in the scope of claims of the present application.

Claims

1. A method for preparing liquid abrasive for additive manufacturing of irregularly shaped parts, characterized in that: Liquid abrasives, by weight, include the following components: polishing abrasive grains: 30-45 parts; Acrylic ester: 50-65 parts; Photoinitiator: 0.5-1 part; Dispersant: 1-2 parts; pH adjuster: 1-2 parts; The preparation method includes the following steps: S1. Weigh the polishing abrasive, acrylate, photoinitiator, dispersant, and pH adjuster according to the proportions of each raw material. Mix the acrylate and photoinitiator and stir under vacuum to obtain acrylic resin. S2. Add polishing abrasive, dispersant and pH adjuster to acrylic resin, and stir under vacuum to obtain liquid abrasive; S3. Place the liquid abrasive in a transparent container and irradiate it with a dot matrix ultraviolet light source for a certain period of time. S4. Vacuum stir the liquid abrasive in step S3 to obtain liquid viscoelastic abrasive; In step S3, the wavelength of the dot matrix ultraviolet light source irradiation is 250-405nm, and the time is 20S-60S.

2. The method for preparing liquid abrasive for additive manufacturing of irregularly shaped parts according to claim 1, characterized in that: The polishing abrasive grains are selected from one or more of tetragonal silicon nitride, aluminum oxide, boron nitride, and silicon carbide with a particle size of 5-30 μm.

3. The method for preparing liquid abrasive for additive manufacturing of irregularly shaped parts according to claim 1, characterized in that: The acrylate is a monofunctional acrylate.

4. The method for preparing liquid abrasive for additive manufacturing of irregularly shaped parts according to claim 3, characterized in that: The monofunctional acrylate is selected from one or more of β-hydroxyethyl methacrylate, isobornyl acrylate, β-carboxyethyl acrylate and 2-phenoxyethyl acrylate.

5. The method for preparing liquid abrasive for additive manufacturing of irregularly shaped parts according to claim 1, characterized in that: The dispersant is selected from sodium polyacrylate, triamine citrate, and polyacrylamide, and the photoinitiator is photoinitiator TPO.

6. The method for preparing the special liquid abrasive for additive manufacturing of irregularly shaped parts according to claim 1, characterized in that: The pH adjuster is selected from citric acid, fatty amines, and aromatic amines.

7. The method for preparing liquid abrasive for additive manufacturing of irregularly shaped parts according to claim 1, characterized in that: In steps S1, S2 and S4, the vacuum degree of vacuum stirring is 0.06-0.08 MPa, the stirring speed is 900-1000 rpm, and the stirring time is 5-15 min.

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