1. A3D printing method of a medical CT machine collimator comprises the steps of establishing a 3D model of the collimator by adopting 3D modeling software, carrying out slicing processing on the 3D model, starting a 3D printer to print, and carrying out heat treatment on the printed collimator, and is characterized in that the specific operation of carrying out heat treatment on the collimator is as follows: and taking the printed collimator out of the printing bin, immediately putting the printed collimator into an experimental furnace, rapidly heating to a high-temperature state under a hydrogen atmosphere for heat preservation treatment, and then performing gradient cooling heat preservation treatment.

2. The 3D printing method of the medical CT machine collimator according to claim 1, characterized in that: the specific requirements of the rapid heating to the high temperature state for heat preservation treatment are as follows: under the hydrogen atmosphere, the temperature in the experimental furnace is firstly raised to the high temperature state of 450-550 ℃ within 1h, and then the temperature is kept for 1.5-2.5 h.

3. The 3D printing method of the medical CT machine collimator according to claim 1, characterized in that: the specific requirements of the gradient cooling and heat preservation treatment are as follows: in the hydrogen atmosphere, the temperature in the experimental furnace is reduced at the speed of 95-105 ℃/h, when the temperature is reduced to 400 ℃, the temperature is preserved for 1h, then the temperature is continuously reduced to 300 ℃ at the same temperature reduction speed, the temperature is preserved for 1h, the temperature is continuously reduced to 150 ℃ at the speed of 150 ℃/h, and after the temperature is preserved for 1h, the experimental furnace is naturally cooled to the room temperature.

4. The 3D printing method of the medical CT machine collimator according to claim 2, characterized in that: the temperature of the high temperature state was 500 ℃.

5. The 3D printing method of the medical CT machine collimator according to claim 2, characterized in that: the heat preservation time in the high-temperature state is 2 hours.

6. The 3D printing method of the medical CT machine collimator according to claim 3, characterized in that: and during the gradient cooling and heat preservation treatment, when the temperature in the experimental furnace is higher than 300 ℃, the cooling speed is 100 ℃/h.

7. The 3D printing method of the medical CT machine collimator according to claim 1, characterized in that: the forming method of the hydrogen atmosphere comprises the steps of vacuumizing the experiment furnace to 0.02MPa in a closed experiment furnace, and then filling hydrogen to ensure that products in the experiment furnace obtain hydrogen protection.

8. The 3D printing method of the medical CT machine collimator according to claim 7, characterized in that: after the hydrogen protection is obtained, the experimental furnace needs to be detonated.

9. The 3D printing method of the medical CT machine collimator set according to any one of claims 1 to 8, wherein: the medical CT machine collimator is made of a pure tungsten material.

Background

The X-ray detector of the CT machine consists of three main parts, namely an X-ray collimator, a collimator support and a photoelectric conversion module. The construction of the X-ray collimator, i.e. the collimator of a CT machine, has been the 1D construction for many years. The structure adopts the traditional powder metallurgy preparation and deep processing technology and the precision assembly technology, can meet the general medical requirements, but along with the requirements of development of the medical high-end image industry and high-precision diagnosis and treatment, particularly the rapid and precise identification and treatment of the current new crown epidemic situation, a more precise collimator is needed, the deviation value between the positioning dimension of the rib of the collimator and the design is required to be within 0.02-0.015mm, the traditional CT machine collimator which is printed after 3D or welded and assembled by the precision assembly technology has reasonable deviation between the positioning dimension of the rib of the design element and the design value due to the thermoplasticity of the machine and the material, the deviation can be along with the rapid cooling or natural cooling after the collimator is printed, the reasonable deviation can be further expanded due to the existence of residual thermal stress, thereby causing the larger deformation and instability of the collimator, if the deviation range is further extended to be greater than 0.025mm, the precision of the medical collimator will not be met, so that it is very important to maintain the deviation range after printing reasonably and stably, and the yield of the product is high.

Disclosure of Invention

The invention aims to provide a 3D printing method of a medical CT (computed tomography) machine collimator, which aims to solve the problems that the traditional medical CT machine collimator provided in the background art cannot maintain the stability of the processing precision and has a large rejection rate.

In order to achieve the purpose, the invention provides the following technical scheme:

A3D printing method of a medical CT machine collimator comprises the steps of establishing a 3D model of the collimator by adopting 3D modeling software, carrying out slicing processing on the 3D model, starting a 3D printer to print, and carrying out heat treatment on the printed collimator, and is characterized in that the specific operation of carrying out heat treatment on the collimator is as follows: and taking the printed collimator out of the printing bin, immediately putting the printed collimator into an experimental furnace, rapidly heating to a high-temperature state under a hydrogen atmosphere for heat preservation treatment, and then performing gradient cooling heat preservation treatment.

Further, the specific requirements of the rapid heating to the high temperature state for the heat preservation treatment are as follows: under the hydrogen atmosphere, the temperature in the experimental furnace is firstly raised to the high temperature state of 450-550 ℃ within 1h, and then the temperature is kept for 1.5-2.5 h.

Further, the specific requirements of the gradient cooling and heat preservation treatment are as follows: in the hydrogen atmosphere, the temperature in the experimental furnace is reduced at the speed of 95-105 ℃/h, when the temperature is reduced to 400 ℃, the temperature is preserved for 1h, then the temperature is continuously reduced to 300 ℃ at the same temperature reduction speed, the temperature is preserved for 1h, the temperature is continuously reduced to 150 ℃ at the speed of 150 ℃/h, and after the temperature is preserved for 1h, the experimental furnace is naturally cooled to the room temperature.

Further, the temperature of the high temperature state is 500 ℃.

Further, the heat preservation time in the high-temperature state is 2 hours.

Further, during the gradient temperature reduction and heat preservation treatment, when the temperature in the experimental furnace is higher than 300 ℃, the temperature reduction speed is 100 ℃/h.

Further, the forming method of the hydrogen atmosphere comprises the steps of vacuumizing the experiment furnace to 0.02MPa in a closed experiment furnace, and then filling hydrogen, so that the product in the experiment furnace obtains hydrogen protection.

Further, after obtaining hydrogen protection, the experimental furnace needs to be detonated.

Further, the medical CT machine collimator is made of a pure tungsten material.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the invention, the thermal stress of the medical CT machine collimator can be eliminated through the annealing at the temperature, and meanwhile, the cooling stress of the medical CT machine collimator is further reduced in a cooling mode according to an isothermal cooling curve, so that the stress is released more slowly, the size of a product is kept stable after printing, and the phenomenon that the size of the precise medical CT machine collimator is further changed after the precise medical CT machine collimator is placed for a period of time or cooled rapidly due to residual stress, so that the precise medical CT machine collimator is changed into a waste product is avoided.

2. According to the invention, after the medical CT machine collimator is printed, the dimensional accuracy of a printed piece is basically maintained, the deformation is reduced, the deviation value range of the distance from the center line of the printed product and the designed given rib to the center of the right hole and the deviation value range of the printed product after being stabilized are controlled within 0.015mm, the stability of the product is enhanced, and the qualified rate is increased.

Drawings

FIG. 1 is a cross-sectional view of a medical CT machine collimator;

fig. 2 is a theoretical data diagram of the distance from the center line of the rib of the medical CT machine collimator to the center line of the positioning hole on the right side.

FIG. 3 is a graph showing deviation values between the data of the position of the rib measured immediately after the collimator of the medical CT machine of example 1 is printed and the data of the position of the rib after the thermal treatment is stabilized and the theoretical data of FIG. 2;

FIG. 4 is a graph showing deviation values between the data of the position of the rib measured immediately after the collimator of the medical CT machine in example 2 is printed and the data of the position of the rib after the thermal treatment is stabilized and the theoretical data in FIG. 2;

fig. 5 is a deviation value graph of the position degree data of the rib measured immediately after the printing of the medical CT machine collimator in embodiment 3 and the position degree data of the rib after the heat treatment stabilization and the theoretical data in fig. 2;

FIG. 6 is a graph showing deviation values between data of the position of the rib measured immediately after the medical CT machine collimator of comparative example 1 is printed and data of the position of the rib after the standing treatment and the theoretical data of FIG. 2;

FIG. 7 is a graph showing deviation values between data of the position of the rib measured immediately after the printing of the collimator of the medical CT machine in comparative example 2 and data of the position of the rib after the stabilization of the heat treatment and the theoretical data in FIG. 2;

FIG. 8 is a graph showing deviation values between the data of the position of the rib measured immediately after the printing of the collimator of the medical CT machine in comparative example 3 and the data of the position of the rib after the stabilization by the heat treatment and the theoretical data in FIG. 2;

fig. 9 is a graph of deviation values of the measured data of the position degree of the rib immediately after the printing of the medical CT machine collimator in comparative example 4 and the data of the position degree of the rib after the heat treatment stabilization from the theoretical data in fig. 2.

Wherein, in fig. 1, 1-0: a medical CT machine collimator; 1-1: the center line of the rib; 1-2: the center line of the positioning hole on the right side;

in FIG. 3-graph, curve a: a deviation value connecting line for measuring the distance from the center line of each rib to the center line of the right side positioning hole immediately after printing and designing the distance from the center line of the given rib to the center line of the right side positioning hole;

curve b: a deviation value connecting line of the distance from the center line of the processed rib to the center line of the right side positioning hole and the distance from the center line of the designed rib to the center line of the right side positioning hole); abscissa (number of bar); ordinate (mean deviation value); wall number: the number of the bar; bottom: the distance from the central point of the bottom surface of the rib to the central line of the central hole on the right side; top: the distance from the center point of the upper surface of the rib to the center line of the center hole on the right side.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

A3D printing method of a pure tungsten medical CT machine collimator specifically comprises the following steps:

s1, as shown in figure 1, establishing a 3D model of the collimator by using 3D modeling software UG, stretching out the outline of the collimator by using the software, arranging mounting holes at two ends of the outline, arranging the mounting hole at the right side as a positioning hole, arranging uniformly distributed ribs in the outline, and setting the position of each rib to the positioning hole according to the data in figure 2;

s2, slicing the 3D model of the collimator, slicing the model of the collimator through software Simplify3Dv3.0, and setting a layer thickness parameter of the slice to be 0.05 mm;

s3, starting the 3D printer to print, and setting the filling scanning power of the printer: 440-460W; filling scan speed: 500-550 mm/s; filling a scanning line gap: 0.05 mm; contour scan power: 320-330W; profile scan speed: 600 mm/s; checkerboard vector number/size: 8 is multiplied by 8; checkerboard scan power: 450W (fill power), 320W (profile scan power); checkerboard scanning speed: 500mm/s (fill scan speed), 300mm/s (profile scan speed); and (3) filling the scanning line gaps with checkerboards: 0.06 mm; rotation angle between layers: 67 degrees, then, a powder bin and a power supply device of the 3D printer are well checked, a base plate is arranged in the material bin, a printer door is closed, and 3D printing is carried out;

s4, carrying out heat treatment on the printed collimator: taking the printed collimator out of the printing bin, immediately placing the printed collimator into an experimental furnace, vacuumizing the experimental furnace to 0.02MPa, filling hydrogen, performing ignition and detonation treatment, quickly heating the temperature in the experimental furnace to 500 ℃ in the hydrogen atmosphere, performing heat preservation treatment at 500 ℃ for 2 hours, performing uniform temperature reduction at the speed of 100 ℃/h after performing heat preservation for 2 hours, performing heat preservation for 1 hour when the temperature in the furnace is reduced to 400 ℃, then cooling to 300 ℃ at the same speed, performing heat preservation for 1 hour at the temperature, after finishing heat preservation, continuously cooling to 150 ℃ at the speed of 150 ℃/h, performing heat preservation at the temperature for 1 hour, and then naturally cooling to the room temperature, thereby finally completing the heat treatment process of the collimator;

and S5, detecting the collimator after heat treatment, and packaging qualified products for storage.

Example 2

On the basis that steps S1, S2, S3 and S5 in embodiment 1 are the same, step S4 in embodiment 1 is changed, specifically: and (3) carrying out heat treatment on the printed collimator: taking the printed collimator out of the printing bin, immediately placing the collimator into an experimental furnace, quickly heating the temperature in the experimental furnace to 550 ℃ in the hydrogen atmosphere, then carrying out heat preservation treatment at 550 ℃ for 1.5h, carrying out heat preservation, cooling at a constant speed of 105 ℃/h after 1.5h, carrying out heat preservation for 1h when the temperature in the furnace is reduced to 400 ℃, then cooling to 300 ℃ at the same speed, carrying out heat preservation for 1h at the temperature, then continuously cooling to 150 ℃ at a speed of 150 ℃/h after the heat preservation is finished, carrying out natural cooling to a room temperature state after the temperature is kept for 1h, and finally finishing the heat treatment process of the collimator to obtain a finished collimator product.

Example 3

On the basis that steps S1, S2, S3 and S5 in embodiment 1 are the same, step S4 in embodiment 1 is changed, specifically: and (3) carrying out heat treatment on the printed collimator: taking the printed collimator out of the printing bin, immediately placing the collimator into an experimental furnace, quickly heating the temperature in the experimental furnace to 450 ℃ in the hydrogen atmosphere, then carrying out heat preservation treatment at 450 ℃ for 2.5h, carrying out uniform temperature reduction at the speed of 95 ℃/h after heat preservation for 2.5h, carrying out heat preservation for 1h when the temperature in the furnace is reduced to 400 ℃, then cooling to 300 ℃ at the same speed, carrying out heat preservation for 1h at the temperature, then continuously cooling to 150 ℃ at the speed of 150 ℃/h after heat preservation is finished, and naturally cooling to the room temperature after heat preservation for 1h at the temperature, thereby finally completing the heat treatment process of the collimator.

Comparative example 1

A3D printing method of a pure tungsten medical CT machine collimator specifically comprises the following steps:

s1, as shown in figure 1, establishing a 3D model of the collimator by using 3D modeling software UG, stretching out the outline of the collimator by using the software, arranging mounting holes at two ends of the outline, arranging the mounting hole at the right side as a positioning hole, arranging uniformly distributed ribs in the outline, and setting the position of each rib to the positioning hole according to the data in figure 2;

s2, slicing the 3D model of the collimator, slicing the model of the collimator through software Simplify3Dv3.0, and setting a layer thickness parameter of the slice to be 0.05 mm;

s3, starting the 3D printer to print, and setting the filling scanning power of the printer: 440-460W; filling scan speed: 500-550 mm/s; filling a scanning line gap: 0.05 mm; contour scan power: 320-330W; profile scan speed: 600 mm/s; checkerboard vector number/size: 8 is multiplied by 8; checkerboard scan power: 450W (fill power), 320W (profile scan power); checkerboard scanning speed: 500mm/s (fill scan speed), 300mm/s (profile scan speed); and (3) filling the scanning line gaps with checkerboards: 0.06 mm; rotation angle between layers: 67 degrees, then, the powder bin and the power supply device of the 3D printer are well checked, the base plate is arranged in the material bin, the door of the printer is closed, 3D printing is carried out, the printed collimator is directly and naturally cooled to room temperature, and a collimator finished product without heat treatment is obtained.

Comparative example 2

Printing out a collimator by adopting the same steps as S1-S3 in the embodiment 1, cleaning the printed collimator to obtain powder, putting the powder into an experimental furnace, heating to 700 ℃ in a hydrogen atmosphere, preserving heat for 3h, then cooling to 500 ℃ at room temperature, preserving heat for 2h, naturally cooling to 300 ℃ and preserving heat for 1h, and finally naturally cooling to room temperature to obtain a finished collimator.

Comparative example 3

After the collimator printed by 3D in steps S1, S2 and S3 in example 1 was used to clean the powder, the powder was put into an experimental furnace, heated to 600 ℃ in a hydrogen atmosphere and kept warm for 3 hours, and finally cooled naturally to room temperature to obtain the finished collimator.

Comparative example 4

Printing out the collimator by adopting the same steps as S1-S3 in the embodiment 1, cleaning the printed collimator, putting the cleaned powder into an experimental furnace, heating to 400 ℃ in a hydrogen atmosphere, preserving heat for 1h, then preserving heat for 0.5h when cooling to 300 ℃, naturally cooling to 200 ℃ and preserving heat for 0.5h, and finally naturally cooling to a room temperature state to obtain a finished collimator.

Performance test data:

after the basic overall outline full-size inspection is passed, the distances from the bottom surface center points of the ribs and the distances from the upper surface center points of the ribs to the center line of the right central hole of different collimators obtained in the examples 1, 2, 3, 1, 2, 3 and 4 are detected by a kirschner image dimension measuring instrument IM-8000, comparing each rib given by design, calculating a deviation value by taking the distance from the bottom center point of each rib to the center line of the right central hole and the distance from the upper surface center point of each rib to the center line of the right central hole, taking the average value of the deviation values of each rib, connecting the corresponding average deviation values of all the ribs through a smooth line to obtain a deviation value diagram of all the ribs of the collimator to be detected, wherein the detection results are respectively shown in figures 3 to 9,

the above experiments are average data obtained by repeating the experiments a plurality of times. Wherein the detonation treatment can make the experimental operation safer.

As can be seen from fig. 3 to 9, the average deviation value (curve a in the figure) of the distance from the center line of the rib to the right center hole measured immediately after printing and the distance from the center line of the designed given rib to the right center hole measured in examples 1 to 3 and the average deviation value (curve b in the figure) of the distance from the center line of the rib to the right center hole measured after heat treatment stabilization and the distance from the center line of the designed given rib to the right center hole measured in comparative examples 1 to 4 are significantly better than the coincidence ratio of the curves a and b in comparative examples 1 to 4, so that it can be found that the coincidence ratio of the design elements of the collimator processed by the method in examples 1 to 3, i.e. the distance from the center line of the rib to the center line of the right positioning hole after printing and the deviation curve after heat treatment is high, so that the collimator in examples 1 to 3 substantially maintains the print size, the requirement of size control precision is met, wherein the size deviation amount of the collimator in the embodiment 1 is the minimum, so that the size deviation amount of the collimator can be controlled within 0.015mm, the stability of a printed product is enhanced, residual thermal stress is eliminated, and the qualification rate of the product is improved.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.