阅读说明：本技术 一种适用于磁性复合材料的4d打印制造方法 (4D printing manufacturing method suitable for magnetic composite material ) 是由 闫春泽 伍宏志 苏彬 张策 陈鹏 刘主峰 史玉升 于 2019-09-29 设计创作，主要内容包括：本发明属于复合材料4D打印相关技术领域,其公开了一种适用于磁性复合材料的4D打印制造方法,所述方法包括以下步骤：(1)将柔性高分子粉末、强磁性粉末和流变助剂混合得到多种复合粉末,多种复合粉末中所述强磁性粉末的质量分数呈梯度分布；(2)基于多种复合粉末及待制造零件的三维模型,采用激光选区烧结工艺成形待制造梯度零件的成形件；(3)对所述成形件进行充磁以使所述成形件具有永磁性,并将充磁后的所述成形件放置在磁场中以使所述成形件发生变形,由此完成待制造梯度零件的4D打印制造。本发明提高了零件的性能,灵活性较强,且增强了成形件的力学性能,成形件高度方向上磁粉含量呈梯度分布,能够实现对弯曲角度的控制。(The invention belongs to the technical field related to 4D printing of composite materials, and discloses a 4D printing manufacturing method suitable for magnetic composite materials, which comprises the following steps: (1) mixing flexible polymer powder, ferromagnetic powder and rheological additive to obtain multiple composite powders, wherein the mass fractions of the ferromagnetic powder in the multiple composite powders are in gradient distribution; (2) forming a forming part of the gradient part to be manufactured by adopting a selective laser sintering process based on the three-dimensional models of the various composite powders and the part to be manufactured; (3) and magnetizing the formed piece to enable the formed piece to have permanent magnetism, and placing the magnetized formed piece in a magnetic field to deform the formed piece, thereby completing the 4D printing manufacture of the gradient part to be manufactured. The invention improves the performance of parts, has stronger flexibility, enhances the mechanical property of the formed piece, has gradient distribution of magnetic powder content in the height direction of the formed piece, and can realize the control of the bending angle.)

1. A 4D printing fabrication method suitable for use with magnetic composites, the method comprising the steps of:

(1) mixing flexible polymer powder, ferromagnetic powder and rheological additive to obtain multiple composite powders, wherein the mass fractions of the ferromagnetic powder in the multiple composite powders are in gradient distribution;

(2) forming a formed part of the part to be manufactured by adopting a selective laser sintering process based on the three-dimensional models of the various composite powders and the part to be manufactured;

(3) and magnetizing the formed piece to enable the formed piece to have permanent magnetism, and placing the magnetized formed piece in a magnetic field to deform the formed piece, thereby completing the 4D printing and manufacturing of the part to be manufactured.

2. The 4D printing fabrication method suitable for magnetic composites as claimed in claim 1, wherein: the molded article has different deformation amounts in each portion in the height direction, and has different mass contents of the ferromagnetic powder corresponding to each portion.

3. The 4D printing fabrication method suitable for magnetic composites as claimed in claim 2, wherein: the mass content of the ferromagnetic powder in each part of the forming piece from bottom to top is distributed in a gradient way along the height of the forming piece.

4. The 4D printing fabrication method for magnetic composites as claimed in claim 1, wherein: the flexible polymer powder is polymer powder with the elastic modulus lower than 50 MPa.

5. The 4D printing fabrication method for magnetic composites as claimed in claim 4, wherein: the flexible high polymer powder is thermoplastic polyurethane.

6. The 4D printing fabrication method suitable for magnetic composites as claimed in any of claims 1 to 5, wherein: the ferromagnetic powder is one or more of neodymium iron boron powder, ferrite powder, iron nickel powder and iron cobalt powder.

7. The 4D printing fabrication method suitable for magnetic composites as claimed in any of claims 1 to 5, wherein: the rheological additive is one or more of fumed silica, castor oil derivatives and polyethylene wax.

8. The 4D printing fabrication method suitable for magnetic composites as claimed in any of claims 1 to 5, wherein: the mass ratio of the sum of the flexible polymer powder and the ferromagnetic powder to the rheological additive is 1000: (10-12).

9. The 4D printing fabrication method suitable for magnetic composites as claimed in any of claims 1 to 5, wherein: during forming, when composite powder with the mass fraction of the ferromagnetic powder being a preset value is needed, the powder feeding cylinder provided with the composite powder is replaced, and meanwhile, technological parameters are adjusted to be matched with the composite powder.

10. The 4D printing fabrication method suitable for magnetic composites of claim 9, wherein: along with the increase of the mass fraction of the strong magnetic powder in the composite powder, the temperature of the forming working cavity is increased; the mass fraction of the strong magnetic powder is increased by 10%, and the temperature of the working cavity is increased by 3 ℃.

Technical Field

The invention belongs to the technical field of composite material 4D printing, and particularly relates to a 4D printing manufacturing method suitable for a magnetic composite material.

Background

The performance requirements of the manufacturing field on the components are higher and higher, the trend that the traditional mechanical performance and kinetic energy performance are gradually developed to the intelligent characteristic is shown, and the intelligent component has the intelligent characteristic that the shape, performance or function of the intelligent component can be controllably changed along with external stimulation. However, the former of conventional 3D printing technology is "stationary" and does not have the intelligent feature. The intelligent component often possesses the structure that becomes more meticulous, complicates, is particularly suitable for adopting 3D printing technique shaping. Along with the lapse of time, under the external stimulus, the shape, performance, function of the intelligent component that 3D printed and formed can take place controllable change, and this intelligence characteristic introduces this one-dimensional (D) of time into 3D printing technique, derives 4D printing technique from this, and it is the subversive manufacturing technique of the intercropping of emerging multidisciplinary, and the deep research to it will promote the development in fields such as intelligent material, intelligent structure and 3D printing technique, has important scientific research and production application value.

The external stimulation mainly includes forms of heat energy, a magnetic field, an electric field, a pH value, water, humidity and the like, and most researches are carried out on the stimulation of the heat energy at present, namely, under the condition that the temperature is increased to a higher temperature, the intelligent component formed by 3D printing is stimulated to return to an initial shape from a temporary shape under the condition that the high temperature is used. This way of deforming the thermal energy driving member causes the driving distance to be greatly limited,and controllable driving cannot be achieved. At present, those skilled in the art gradually adopt magnetic field to drive the member to deform to realize 4D printing, for example, patent CN105771003A discloses a method for preparing a biodegradable polymer self-expandable intravascular stent based on 3D printing technology, which utilizes biodegradable polylactic acid-based shape memory polyurethane/Fe₃O₄The invention discloses a nano composite material, which is prepared into a vascular stent by a fused deposition manufacturing technology, and a shape memory polymer is remotely excited to recover the shape by utilizing a magnetocaloric effect.

Disclosure of Invention

Aiming at the defects or improvement requirements in the prior art, the invention provides a 4D printing manufacturing method suitable for a magnetic composite material, which is based on the manufacturing characteristics of the existing intelligent component and researches and designs a gradient 4D printing manufacturing method suitable for the magnetic composite material with better performance. According to the method, flexible polymer powder is selected as a base material, so that the formed part is easy to deform, and the deformation of the formed part is driven by a magnetic field, so that the remote controllable control of the deformation can be realized; by selecting strong magnetic permanent magnetic powder, the formed piece can generate larger deformation in a magnetic field, the magnetic composite material is formed by adopting a selective laser sintering process, the interlayer bonding strength of the formed piece is increased, the mechanical property of the formed piece is improved, the magnetic powder content in the height direction of the magnetic formed piece is in gradient distribution, and the control on the bending angle of the formed piece can be realized.

To achieve the above object, the present invention provides a 4D printing manufacturing method suitable for a magnetic composite material, the method comprising the steps of:

(1) mixing flexible polymer powder, ferromagnetic powder and rheological additive to obtain multiple composite powders, wherein the mass fractions of the ferromagnetic powder in the multiple composite powders are in gradient distribution;

(2) forming a formed part of the part to be manufactured by adopting a selective laser sintering process based on the three-dimensional models of the various composite powders and the part to be manufactured;

(3) and magnetizing the formed piece to enable the formed piece to have permanent magnetism, and placing the magnetized formed piece in a magnetic field to deform the formed piece, thereby completing the 4D printing and manufacturing of the part to be manufactured.

Further, the molded article has different deformation amounts at each portion in the height direction, and has different mass contents of the ferromagnetic powder corresponding to each portion in the height direction.

Further, the mass content of the ferromagnetic powder in each part of the formed piece from bottom to top is distributed in a gradient manner along the height of the formed piece.

Furthermore, the flexible polymer powder is polymer powder with the elastic modulus lower than 50 MPa.

Further, the flexible polymer powder is thermoplastic polyurethane.

Further, the ferromagnetic powder is one or more of neodymium iron boron powder, ferrite powder, iron nickel powder and iron cobalt powder.

Further, the rheological additive is one or more of fumed silica, castor oil derivatives and polyethylene wax.

Further, the mass ratio of the sum of the mass of the flexible polymer powder and the ferromagnetic powder to the mass of the rheological aid is 1000: (10-12).

Further, when the composite powder having the ferromagnetic powder mass fraction of a predetermined value is required in the molding, the powder feeding cylinder on which the composite powder is mounted is replaced, and the process parameters are adjusted to match the composite powder.

Further, as the mass fraction of the strong magnetic powder in the composite powder increases, the temperature of the forming working cavity increases; the mass fraction of the strong magnetic powder is increased by 10%, and the temperature of the working cavity is increased by 3 ℃.

In general, compared with the prior art, through the above technical solution conceived by the present invention, the 4D printing manufacturing method suitable for the magnetic composite material provided by the present invention mainly has the following beneficial effects:

1. the invention adopts the selective laser sintering process to form the magnetic composite powder material, thereby improving the interlayer bonding strength of the formed piece and enhancing the mechanical property of the formed piece.

2. The invention adopts the flexible polymer powder material, the strong magnetic permanent magnetic powder material and the rheological additive to mix to obtain a plurality of composite powders, the flexible polymer material enables the formed piece to be easy to deform, and the strong magnetic material enables the deformation amount of the magnetic formed piece in a magnetic field to be increased.

3. The mass fractions of the ferromagnetic powder in the multiple composite powders are distributed in a gradient manner, and then a formed piece with the mass content of the ferromagnetic powder distributed in a gradient manner along the height of the formed piece is obtained, so that the forces of the magnetic fields applied to different heights are different, and the stress bending angle of the formed piece can be quantitatively controlled.

4. The flexible polymer powder is selected as the base material, so that the formed piece is easy to deform, and the magnetized formed piece is placed in the magnetic field to deform the formed piece, so that the deformation of the formed piece is driven by the magnetic field, and the remote controllable control of the deformation can be realized.

Drawings

FIG. 1 is a schematic flow chart of a 4D printing method for manufacturing a magnetic composite material according to a preferred embodiment of the present invention;

fig. 2 shows (a) a magnetic field generated by a permanent magnet and (b) a magnetic field generated by a 4D printing method for manufacturing a magnetic composite material in fig. 1; (b) the figure is the magnetic field generated by the energized coil;

fig. 3 is a schematic flow chart of a 4D printing manufacturing method suitable for a magnetic composite material according to a first embodiment of the present invention;

FIG. 4 is a schematic diagram showing the gradient distribution of the mass fraction of magnetic powder in the height direction of a formed article manufactured by the 4D printing manufacturing method for the magnetic composite material in FIG. 3;

FIG. 5 is a schematic diagram of the distribution of magnetic induction at the center of a formed part obtained by the 4D printing manufacturing method for the magnetic composite material in FIG. 3;

fig. 6 is a graph showing the relationship between the amount of deformation in a magnetic field and the content of ferromagnetic powder in a molded article obtained by the 4D printing method for manufacturing a magnetic composite material shown in fig. 3.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Referring to fig. 1 and fig. 2, a 4D printing method for manufacturing a magnetic composite material according to a preferred embodiment of the present invention mainly includes three steps of mixing powder, forming, and magnetizing, and specifically includes the following steps:

the method comprises the following steps of firstly, mixing flexible polymer powder, ferromagnetic powder and rheological additive to obtain multiple composite powder, wherein the mass fraction of the ferromagnetic powder in the multiple composite powder is distributed in a gradient manner.

Specifically, flexible polymer powder, ferromagnetic powder and a rheological additive capable of improving the flowability of the powder are selected, the flexible polymer powder and the ferromagnetic powder are respectively dried and then are mixed with the rheological additive capable of improving the flowability of the powder to obtain composite powder, and the mass fraction of the ferromagnetic powder in the composite powder obtained by mixing is in gradient distribution.

In this embodiment, the flexible polymer powder is a polymer powder material with an elastic modulus lower than 50MPa and good toughness, and mainly includes Thermoplastic Polyurethane (TPU); the ferromagnetic powder mainly comprises neodymium iron boron (NdFeB) powder, ferrite powder, iron-nickel powder, iron-cobalt powder and the like; the rheological additive capable of improving the powder flowability is a powdery material, and mainly comprises gas-phase silicon dioxide, castor oil derivatives, polyethylene wax and other rheological additives. The addition content of the rheological additive is 10-12 g per 1000g of the flexible polymer and the ferromagnetic permanent magnetic powder.

And secondly, forming a formed part of the part to be manufactured by adopting a selective laser sintering process based on the multiple composite powders and the three-dimensional model of the part to be manufactured.

Specifically, a selective laser sintering process is adopted, the content of the ferromagnetic powder is in gradient distribution along the height direction of a formed part, when the composite powder with certain ferromagnetic powder content is needed, a powder feeding cylinder filled with the composite powder is replaced, and process parameters are adjusted to be matched with the composite powder, so that gradient forming can be realized, and the formed part with the ferromagnetic powder content in gradient distribution along the height direction is obtained.

The technological parameters of selective laser sintering include laser scanning rate of 3800-4000 mm/s, scanning interval of 0.2-0.3 mm, laser power of 40-42W and powder spreading layer thickness of 0.1-0.12 mm. When the polymer powder is TPU, the temperature of the working cavity is 125-135 ℃. As the mass fraction of the ferromagnetic powder increases, the temperature of the forming chamber needs to be increased appropriately. Typically the temperature of the working chamber increases by 3 c for every 10 wt% increase in mass fraction. And after the forming is finished, naturally cooling to room temperature and taking out the formed piece.

And step three, magnetizing the formed piece to enable the formed piece to have permanent magnetism, and placing the magnetized formed piece in a magnetic field to deform the formed piece, thereby completing 4D printing and manufacturing of the part to be manufactured.

Specifically, the formed part is magnetized by a magnetizing machine, the magnetizing voltage is 1800V-2000V adjustable, after the magnetizing is finished, the formed part has permanent magnetism, and can be deformed when being placed in an external magnetic field, so that 4D printing driven by the magnetic field is realized. The applied magnetic field has two main forms: a magnetic field generated by the permanent magnet and a magnetic field generated by the electrified coil.

The invention is described in further detail below with reference to two examples.