CN112276367B - Porous titanium artificial bone microstructure and manufacturing method thereof - Google Patents

Abstract

The invention discloses a porous titanium artificial bone microstructure and a manufacturing method thereof, wherein the porous titanium artificial bone microstructure comprises a variable topology internal microstructure and a composite three-dimensional curved surface microstructure, the variable topology internal microstructure comprises a bearing line arranged along a space stress point according to the size and the direction of each stress point and artificial bone pores which are positioned in the crossed bearing lines and enclose an internal microstructure and have the same value with the natural bone pores, and the composite three-dimensional curved surface microstructure comprises main convex parts and secondary convex parts which are uniformly distributed on the surface of an artificial bone at intervals. The variable topology internal microstructure of the invention uses the bearing wire to bear the main stress, the pores are distributed inside the variable topology internal microstructure, the mass can be reduced, the variable topology internal microstructure is beneficial to the growth of bone tissues and the transmission and lubrication of body fluid, and can be better combined with the bone tissues of human bodies under the condition of meeting the mechanical requirement, and the biocompatibility is good.

Description

Porous titanium artificial bone microstructure and manufacturing method thereof

Technical Field

The invention relates to an artificial bone, in particular to a porous titanium artificial bone microstructure and an application and manufacturing method thereof.

Background

Nowadays, the artificial bone material includes bioceramics, titanium and its alloys. The biological ceramic is well combined with human bone tissues, but the Young modulus of the biological ceramic is not matched with that of natural bones, and the mechanical property is poor; titanium and its alloy have good mechanical properties, but it is poorly combined with human body, and it is easy to have inflammation, artificial bone loosening and even shedding. In the aspect of microstructure morphology, the microstructure is a hydrophobic surface microstructure represented by bionic shark skin and lotus effect, and the microstructure morphology of adhesion is very few.

In the manufacture of microstructured surfaces, there are methods such as shot blasting, polishing, micro milling, electrochemistry, and photolithography. Although the surface of the microstructure processed by shot blasting and polishing has specific roughness, the shape of the microstructure is uncontrollable; although the regular microstructure surface can be prepared by adopting micro milling and an electrochemical method, the problems of complex method, complex process, low efficiency and the like exist; the existing pulse energy laser etching metal can cause the defects of surface roughness and the like caused by heat influence.

Chinese patent publication No. CN108081437A discloses a method for manufacturing a ceramic implant, which includes forming a plurality of microstructures on a surface of a mold, covering the surface of the mold with a ceramic composite material using the mold, demolding, and sintering the ceramic composite material after demolding to form a ceramic implant with a microstructure surface, but the method still has the following problems: although the artificial bone prepared by the method can be used for preparing a surface microstructure, the shape precision of the microstructure is difficult to ensure, and errors can be generated during demoulding and sintering; meanwhile, the preparation method is too difficult, the requirement on the precision of the die is high, and the requirement on the proficiency of an operator is high, so that the preparation difficulty is increased.

Chinese patent publication No. CN110757092A discloses a processing apparatus and a processing method for an artificial bone surface functional microstructure, which process the artificial bone surface by a five-axis linkage machine tool, electromagnetic vibration absorption, and liquid-electric mixed spraying to prepare an artificial bone with a functional microstructure surface, but the method still has the following problems: the artificial bone prepared by the method can not avoid the abrasion of a cutter in the processing process, and the cutting edge of the cutter is gradually abraded along with the lengthening of the processing time and mileage, so that the depth of a microstructure is inconsistent, the shape is irregular, burrs and plastic deformation are easy to generate, the surface roughness is easy to deteriorate, and the like. And the preparation method is complex, and has higher requirement on the proficiency of operators, thereby increasing the preparation difficulty.

Chinese patent publication No. CN110919172A discloses a device, system and method for making a microstructure on a roll surface, which ensures the consistency of the shape by engraving the microstructure with focused laser, but the method still has the following problems: the microstructure surface prepared by the method only ensures the shape, but the microstructure of the processed and formed surface is influenced by heat, and the defects of rough processed surface and the like cannot be overcome.

Therefore, it is desired to solve the above problems.

Disclosure of Invention

The purpose of the invention is as follows: it is a first object of the present invention to provide a porous titanium artificial bone microstructure that facilitates bone tissue growth, transport and lubrication of body fluids, while effectively increasing adhesion and wear resistance of the microstructure surface.

The second purpose of the invention is to provide a manufacturing method of the porous titanium artificial bone microstructure.

The technical scheme is as follows: in order to achieve the purpose, the invention discloses a porous titanium artificial bone microstructure which comprises a variable topology internal microstructure and a composite three-dimensional curved surface microstructure, wherein the variable topology internal microstructure comprises a bearing line arranged along a space stress point according to the size and the direction of each stress point and artificial bone pores which are positioned in the crossed bearing lines and enclose an internal microstructure and have the same value with the natural bone pores, and the composite three-dimensional curved surface microstructure comprises main bulges and secondary bulges which are uniformly distributed on the surface of an artificial bone at intervals.

The main convex parts and the secondary convex parts are alternately arranged along the horizontal direction, and the connecting line of the centers of the main convex parts and the secondary convex parts in the direction is marked as a convex gradient line.

Preferably, the main convex parts and the secondary convex parts are alternately arranged along a direction forming an angle of 60 degrees with the horizontal direction, and a connecting line of the centers of the main convex parts and the secondary convex parts in the direction is marked as a convex gradient line.

Furthermore, the main convex parts are sequentially arranged along the direction forming an angle of 120 degrees with the horizontal direction.

Further, the secondary convex parts are sequentially arranged along a direction forming an angle of 120 degrees with the horizontal direction.

Preferably, the main boss is a hexagonal prism, and an arc chamfer is arranged on the upper edge of the main boss; the secondary bulge is a cylinder, and the upper edge of the secondary bulge is provided with an arc chamfer.

Furthermore, the side length L of the main convex part is 100-300 μm, the height H is 10-30 μm, and the radius of the arc chamfer is the same as the height of the main convex part.

Furthermore, the side length of the main convex part is the same as the radius of the cylinder of the secondary convex part, the height of the main convex part is the same as that of the secondary convex part, and the distance between the centers of the adjacent main convex part and the secondary convex part is 2L + 50-150 μm.

The invention relates to a method for manufacturing a porous titanium artificial bone microstructure, which comprises the following steps:

(1) importing the designed variable topology internal microstructure model into three-dimensional software, dividing lines on the variable topology internal microstructure model at equal intervals according to a fixed direction, dividing points on the lines at equal intervals, and obtaining points on equidistant offset plane surfaces to obtain a processing track control program;

(2) firstly, laying titanium powder on a metal substrate, then obtaining a processing track control program according to the step (1), and controlling a laser beam to scan a processing path through a computer; when the energy laser acts on the titanium powder, the titanium powder positioned in the action area of the laser beam is melted and fused with the metal substrate; then the metal substrate descends, a layer of powder is paved again, the powder in the laser focal distance in the layer of powder is melted and is melted with the lower layer, and the powder and the lower layer are stacked layer by layer to finally form the required porous titanium variable topology internal microstructure;

(3) opening the laser, enabling the laser to emit laser, reflecting the laser by a reflector, finally focusing the laser by a spherical condensing lens, ensuring the diameter of a beacon light spot to be a certain value by a concave lens, enabling the ablation width to be fixedly acted on the surface of a workpiece, setting the power, the frequency and the speed of the laser with energy required by processing, and then accurately placing the workpiece to be processed on a moving platform according to the laser focus;

(4) turning on an ultrasonic generator to send out ultrasonic waves, generating vibration through an ultrasonic transducer to enable the workpiece to vibrate up and down, and adjusting current and frequency to realize the up-and-down vibration of the workpiece;

(5) simultaneously starting a moving platform of the machine tool, compiling a machine tool moving platform control program according to the composite three-dimensional curved surface microstructure, controlling the movement of the moving platform, driving the workpiece to move, finishing the microstructure appearance processing of different positions of the workpiece, and finishing the processing of the microstructure depth of the composite three-dimensional curved surface by multiple times of etching;

(6) and immediately closing the laser and the ultrasonic generator after the machining is finished, stopping the platform from moving, taking down the workpiece, and sequentially putting the workpiece into acetone, absolute ethyl alcohol and deionized water for ultrasonic cleaning.

Has the advantages that: compared with the prior art, the invention has the following remarkable advantages: the variable topology internal microstructure of the invention uses the bearing wire to bear the main stress, the pores are distributed inside the variable topology internal microstructure, the mass can be reduced, the variable topology internal microstructure is beneficial to the growth of bone tissues and the transmission and lubrication of body fluid, and can be better combined with the bone tissues of human body under the condition of meeting the mechanical requirement, and the biocompatibility is good; according to the invention, a composite three-dimensional curved surface microstructure is designed according to the animal sole adhesive surface microstructure, wherein the main protrusions and the secondary protrusions are staggered to ensure good adhesion and have better wear resistance; the invention adopts energy laser and ultrasonic wave composite processing to prepare the artificial bone composite three-dimensional curved surface microstructure, the size of an energy laser focused beam can be smaller than 1 mu m, a shape fine microstructure is carved, and meanwhile, ultrasonic vibration is carried out, so that the problems of rough surface and the like after processing and forming are solved, and a smooth curved surface microstructure is obtained.

Drawings

FIGS. 1(a) -1 (c) are flow charts of the present invention for obtaining the best line of force;

FIG. 2 is a schematic structural view of the artificial bone pores of the present invention;

FIG. 3 is a schematic structural diagram of a composite three-dimensional curved surface microstructure according to the present invention;

FIG. 4 is a partial schematic view of a composite three-dimensional curved surface microstructure according to the present invention;

FIG. 5 is a schematic diagram of a processing system according to the present invention;

FIG. 6 is a schematic diagram of the combined use of the lenses of the invention.

Detailed Description

The technical scheme of the invention is further explained by combining the attached drawings.

The porous titanium artificial bone microstructure is characterized in that the artificial bone is made of porous titanium, the porosity of the porous titanium is 5.8-62%, and the aperture ratio is 60-99.5%, so that excellent biocompatibility and good corrosion resistance are guaranteed; porous titanium with Young's modulus porosity matched with that of natural bone is selected, so that the in-growth and body fluid circulation of new bone cell tissue are ensured, and the biomechanical compatibility of the new bone cell tissue is improved. The porous titanium artificial bone microstructure comprises a variable topology internal microstructure and a composite three-dimensional curved surface microstructure, wherein the variable topology internal microstructure comprises a bearing line arranged along a space stress point according to the size and the direction of each stress point and artificial bone pores which are positioned in the crossed bearing lines and enclose an internal microstructure and have the same value with the natural bone pores. The bearing line is arranged according to the stress point, and finite element analysis is carried out according to the stress condition of the artificial bone to obtain the stress condition of each point in space; and (4) making a stress circle according to the stress distribution, and finally obtaining a main bearing line according to the made stress circle. As shown in fig. 1(a) -1 (c) and fig. 2, taking a femur as an example, first, a femur model is divided into tetrahedral mesh networks, material properties are defined, a certain load is applied, and stress of each tetrahedral unit is calculated; topology optimization iteration: sorting the stress of each tetrahedral unit, removing 50-70% of the unit areas with smaller stress values, reserving the rest unit areas, continuously removing 50-70% of the material through a plurality of iterations, distributing the result in the direction along the maximum principal stress, namely the area playing a key role in resisting the load, and obtaining the optimal bearing line according to the result.

Setting the porosity value of the corresponding position of the artificial bone to be the same as that of the natural bone according to the difference of the porosities of the different positions of the natural bone; the porosity of the artificial bone pores is 5.8-62%, the artificial bone pores are manufactured by additive manufacturing, mechanical requirements are met, meanwhile, the quality is reduced, and bone tissue growth and body fluid transmission and lubrication are facilitated.

The composite three-dimensional curved surface microstructure comprises main convex parts 9 and secondary convex parts 10 which are uniformly distributed on the surface of the artificial bone at intervals, and is designed and determined by combining the surface characteristics of natural bones according to the characteristics of the adhesive surface structure of animal foot soles, so that the combining capacity of the artificial bone and bone tissues is improved; thereby having better abrasion resistance while ensuring good adhesion. The main lug boss and the secondary lug boss are alternately arranged along the horizontal direction, and the connecting line of the center of the main lug boss and the center of the secondary lug boss in the direction is marked as a lug gradient line; the main convex parts and the secondary convex parts are alternately arranged along the direction forming an angle of 60 degrees with the horizontal direction, and the connecting line of the centers of the main convex parts and the secondary convex parts in the direction is marked as a convex gradient line 11; the main convex parts are sequentially arranged along the direction forming an angle of 120 degrees with the horizontal direction; the secondary protrusions are sequentially arranged in a direction forming an angle of 120 ° with the horizontal direction. The main convex part is a hexagonal prism, and the upper edge of the main convex part is provided with an arc chamfer; the secondary bulge is a cylinder, and the upper edge of the secondary bulge is provided with an arc chamfer. The side length L of the main convex part is 100-300 mu m, the height H is 10-30 mu m, and the radius of the arc chamfer is the same as the height of the main convex part. The side length of the main convex part is the same as the radius of the cylinder of the secondary convex part, the height of the main convex part is the same as that of the secondary convex part, and the distance between the centers of the adjacent main convex part and the secondary convex part is 2L + 50-150 mu m.

The composite three-dimensional curved surface microstructure of the artificial bone is processed by adopting energy wave combination, specifically ultrasonic waves and laser, and is prepared by a built processing system. The processing system comprises a workpiece 1, a concave lens 2, a spherical lens 3, a reflector 4, a laser generator 5, a moving platform 6, an ultrasonic generator 7 and an ultrasonic transducer 8, wherein the spherical lens 3 and the concave lens 2 are combined for use, the two lenses are both horizontally arranged, the spherical lens 3 is arranged above the concave lens 2, light is focused by the spherical lens 3 and then passes through the concave lens 2, the diameter of a finally generated constant light spot is ensured, and the energy light etching width is constant; the laser is emitted by a laser generator, the power of the laser is 10-100W, the frequency is 1-100 KHz, the beam diameter is 5mm, the laser power, the laser speed and the laser pulse frequency are adjusted by a digital signal generator, the specific waveform and frequency of the laser output are controlled, and finally the laser acts on a workpiece. The ultrasonic wave is sent by an ultrasonic generator, the ultrasonic power is 0-300W, the frequency is 20 KHz-40 KHz, the ultrasonic wave acts on a machine tool moving platform through a transducer, and the vertical vibration of a workpiece is finally realized, so that the better surface quality of the microstructure is obtained, and the curved surface is smoother and smoother. The moving platform 6 is a plane moving platform, the moving speed is 0.1-5 m/min, the acceleration is 1-30 m/min2, and the strokes of an X axis and a Y axis are-100 mm; the X-axis and Y-axis movement of the platform is controlled by writing a machine tool moving platform control program, and a workpiece is driven to be machined.

The processing principle of the invention is as follows: the laser generator emits laser, the laser is reflected by the reflector for 3 times and is finally focused by the spherical lens, and the concave lens ensures that the diameter of a laser spot is a certain value, so that the ablation width is fixed and acts on the surface of a workpiece. Meanwhile, the ultrasonic generator emits ultrasonic waves, and the ultrasonic transducer vibrates to enable the workpiece to vibrate up and down, so that the surface of the processed curved surface is smoother. And during processing, turning on a laser to emit energy laser, adjusting the speed, the power and the frequency, reflecting the energy laser by a reflector, and maintaining a constant light spot diameter to ablate the surface of the porous titanium artificial bone through a condensing lens and a concave lens. Meanwhile, a moving platform of the machine tool is started, a machine tool moving platform control program is compiled according to the composite three-dimensional curved surface microstructure, the moving platform is controlled to move, the workpiece is driven to move, the microstructure appearance processing of different positions of the workpiece is completed, and the processing is completed by etching for multiple times on places with different depths in the composite three-dimensional curved surface microstructure. The whole process adopts composite processing of energy laser and ultrasonic wave, the energy laser is reflected by a reflector and focused by a lens combination and vertically and downwards hits the surface of a workpiece to etch the surface of the workpiece; meanwhile, the ultrasonic generator sends ultrasonic waves, the ultrasonic waves act on the moving platform through the ultrasonic transducer, the moving platform vibrates vertically, and therefore the workpiece is driven to vibrate vertically, the surface quality of the machined and formed microstructure is higher, and the curved surface is smoother. Thermal defects on the surface of the material are easily caused by independent laser processing, and pores, large-particle slag and the like are formed; the ultrasonic vibration of the invention increases the cooling speed and reduces the oxidation effect of the processing surface; when the workpiece is subjected to ultrasonic vibration, the nano particles solidified on the surface of the laser etching material are finer, denser and uniformly distributed; the formation of large-particle slag and a recasting layer is effectively avoided, the processing surface precision is improved, and the surface is smoother; the invention adopts the energy laser and the ultrasonic wave to process and prepare the surface microstructure of the artificial bone, the size of the focused beam of the energy laser can be smaller than 1 mu m, the fine microstructure of the shape is carved, and meanwhile, the ultrasonic vibration solves the problems of rough surface and the like after processing and forming, and the smooth curved surface microstructure is obtained. The invention realizes that the etching diameter and the etching depth of a light spot are several micrometers during final focusing by adjusting the speed, the power and the frequency of laser, and realizes the etching of the groove and the curved surface of the composite curved surface microstructure.

The invention relates to a method for manufacturing a porous titanium artificial bone microstructure, which comprises the following steps:

(1) importing the designed variable topology internal microstructure model into three-dimensional software, dividing lines on the variable topology internal microstructure model at equal intervals according to a fixed direction, dividing points on the lines at equal intervals, and obtaining points on equidistant offset plane surfaces to obtain a processing track control program;

(2) firstly, laying titanium powder on a metal substrate, then obtaining a processing track control program according to the step (1), and controlling a laser beam to scan a processing path through a computer; when the energy laser acts on the titanium powder, the titanium powder positioned in the action area of the laser beam is melted and fused with the metal substrate; then the metal substrate descends, a layer of powder is paved again, the powder in the laser focal distance in the layer of powder is melted and is melted with the lower layer, and the powder and the lower layer are stacked layer by layer to finally form the required porous titanium variable topology internal microstructure;

(3) opening the laser, enabling the laser to emit laser, reflecting the laser by a reflector, finally focusing the laser by a spherical condensing lens, ensuring the diameter of a laser spot to be a certain value by a concave lens, enabling the ablation width to be fixedly acted on the surface of a workpiece, setting the power, the frequency and the speed of the laser with energy required by processing, and then accurately placing the workpiece to be processed on a moving platform according to the laser focus;

(4) turning on an ultrasonic generator to send out ultrasonic waves, generating vibration through an ultrasonic transducer to enable the workpiece to vibrate up and down, and adjusting current and frequency to realize the up-and-down vibration of the workpiece;

(5) simultaneously starting a moving platform of the machine tool, compiling a machine tool moving platform control program according to the composite three-dimensional curved surface microstructure, controlling the movement of the moving platform, driving the workpiece to move, finishing the microstructure appearance processing of different positions of the workpiece, and finishing the processing of the positions with different depths of the composite three-dimensional curved surface microstructure through multiple times of etching;

(6) and immediately closing the laser and the ultrasonic generator after the machining is finished, stopping the platform from moving, taking down the workpiece, and sequentially putting the workpiece into acetone, absolute ethyl alcohol and deionized water for ultrasonic cleaning.

In the description of the present invention, it should be noted that the terms "middle", "upper", "lower", "left", "right", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or the orientations or positional relationships that the products of the present invention usually place when using, which are only used for convenience of description and simplicity of description, but do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.

Although the preferred embodiments of the present invention have been described in detail, the present invention is not limited to the details of the embodiments, and various equivalent modifications can be made within the technical spirit of the present invention, and the scope of the present invention is also within the scope of the present invention. It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. The invention is not described in detail in order to avoid unnecessary repetition.

Claims (2)

1. A porous titanium artificial bone microstructure is characterized in that: the artificial bone comprises a variable topology internal microstructure and a composite three-dimensional curved surface microstructure, wherein the variable topology internal microstructure comprises a bearing line arranged along a space stress point according to the size and the direction of each stress point and artificial bone pores which are positioned on the crossed bearing lines and enclose an internal microstructure and have the same value with the natural bone pores, and the composite three-dimensional curved surface microstructure comprises main convex parts and secondary convex parts which are uniformly distributed on the surface of the artificial bone at intervals; the main convex parts and the secondary convex parts are alternately arranged along the horizontal direction, and the connecting line of the centers of the main convex parts and the secondary convex parts in the direction is marked as a convex gradient line; the main convex parts and the secondary convex parts are alternately arranged along the direction forming an angle of 60 degrees with the horizontal direction, and the connecting line of the centers of the main convex parts and the secondary convex parts in the direction is marked as a convex gradient line; the main convex parts are sequentially arranged along the direction forming an angle of 120 degrees with the horizontal direction, and the secondary convex parts are sequentially arranged along the direction forming an angle of 120 degrees with the horizontal direction; the main convex part is a hexagonal prism, and the upper edge of the main convex part is provided with an arc chamfer; the secondary convex part is a cylinder, and the upper edge of the secondary convex part is provided with an arc chamfer; the side length L of the main convex part is 100-300 mu m, the height H is 10-30 mu m, and the radius of the arc chamfer is the same as the height of the main convex part; the side length of the main convex part is the same as the radius of the cylinder of the secondary convex part, the height of the main convex part is the same as that of the secondary convex part, and the distance between the centers of the adjacent main convex part and the secondary convex part is 2L + 50-150 mu m.

2. The method for manufacturing the porous titanium artificial bone microstructure according to claim 1, comprising the steps of:

(1) importing the designed variable topology internal microstructure model into three-dimensional software, dividing lines on the variable topology internal microstructure model at equal intervals according to a fixed direction, dividing points on the lines at equal intervals, and obtaining points on equidistant offset plane surfaces to obtain a processing track control program;

(2) firstly, laying titanium powder on a metal substrate, then obtaining a processing track control program according to the step (1), and controlling a laser beam to scan a processing path through a computer; when the energy laser acts on the titanium powder, the titanium powder positioned in the action area of the laser beam is melted and fused with the metal substrate; then the metal substrate descends, a layer of powder is paved again, the powder in the laser focal distance in the layer of powder is melted and is melted with the lower layer, and the powder and the lower layer are stacked layer by layer to finally form the required porous titanium variable topology internal microstructure;

(3) opening the laser, enabling the laser to emit laser, reflecting the laser by a reflector, finally focusing the laser by a spherical condensing lens, ensuring the diameter of a laser spot to be a certain value by a concave lens, enabling the ablation width to be fixedly acted on the surface of a workpiece, setting the power, the frequency and the speed of the laser with energy required by processing, and then accurately placing the workpiece to be processed on a moving platform according to the laser focus;

(4) turning on an ultrasonic generator to send out ultrasonic waves, generating vibration through an ultrasonic transducer to enable the workpiece to vibrate up and down, and adjusting current and frequency to realize the up-and-down vibration of the workpiece;

(5) simultaneously starting a moving platform of the machine tool, compiling a machine tool moving platform control program according to the composite three-dimensional curved surface microstructure, controlling the movement of the moving platform, driving the workpiece to move, finishing the microstructure appearance processing of different positions of the workpiece, and finishing the processing of the positions with different depths of the composite three-dimensional curved surface microstructure through multiple times of etching;

(6) and immediately closing the laser and the ultrasonic generator after the machining is finished, stopping the platform from moving, taking down the workpiece, and sequentially putting the workpiece into acetone, absolute ethyl alcohol and deionized water for ultrasonic cleaning.

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