KR102291751B1 - MONITORING METHOD and APPARATUS FOR 3D PRINTING - Google Patents

Abstract

A metal 3D printer monitoring method and monitoring device capable of low-cost and high-speed process monitoring are proposed. The metal 3D printer monitoring method according to the present invention is a process monitoring method of a 3D printer for manufacturing a 3D output using metal powder, the wavelength of the second light generated from the metal powder melted by the first light irradiated from the printing head and a first step of measuring the intensity; and a second step of diagnosing the printing process of the 3D printer by using the result value of at least one of the wavelength and intensity of light.

Description

Metal 3D printer monitoring method and monitoring device {MONITORING METHOD and APPARATUS FOR 3D PRINTING}

The present invention relates to a metal 3D printer monitoring method and monitoring apparatus, and more particularly, to a metal 3D printer monitoring method and monitoring apparatus capable of low-cost and high-speed process monitoring.

The basic principle of 3D printers, which are being used in a wide variety of fields such as industry, life, or medicine, is to build 3D objects by stacking thin 2D layers. A 3D printer can form a 3D output using a photocurable resin or metal. Among them, a metal 3D printer is largely divided into a PBF (Powder Bed Fusion) method and a DED (Directed Energy Deposition) method.

In the DED type 3D printer, when a high-power laser beam is irradiated onto the metal surface from the center of the DED head, a molten pool is instantaneously generated, and metal powder is also supplied, and the printer head is moved and laminated in real time to form a 3D output. The metal powder is supplied into the 3D printer by flowing the metal powder using a carrier gas such as nitrogen or argon gas.

The process conditions of the DED type 3D printer are very diverse, such as laser power, laser head moving speed, laser head and molten pool distance, carrier gas flow rate, and powder injection speed, so it is difficult to find the optimal process conditions experimentally. It is very difficult and even if the same process conditions are used, there is a problem in that the process quality varies according to changes in the surrounding environment such as temperature and humidity.

Accordingly, the process conditions were monitored to ensure that the quality of the 3D output could be maintained as uniformly as possible. Conventionally, the shape and temperature of the molten pool were monitored through a thermal imaging camera, etc. to monitor the process. However, thermal imaging cameras are very expensive and have disadvantages in that real-time monitoring is difficult because high-speed measurement is difficult.

The present invention has been devised to solve the above problems, and an object of the present invention is to provide a metal 3D printer monitoring method and a monitoring device capable of process monitoring at low cost and high speed.

The metal 3D printer monitoring method according to an embodiment of the present invention for achieving the above object is a process monitoring method of a 3D printer for producing a 3D output using a metal powder, melted by the first light irradiated from the printing head A first step of measuring the wavelength and intensity of the second light generated from the metal powder; and a second step of diagnosing the printing process of the 3D printer by using the result value of at least one of the wavelength and intensity of light.

The first step may be performed using a spectrometer.

The spectrometer is connected to the optical fiber, and the second light may be introduced into the spectrometer through the optical fiber.

The second step may be a step of diagnosing that the metal powder is dispersed when the wavelength band of the second light is wide.

The second step may be a step of diagnosing that the amount of the metal powder is large or that the first light is strong when the intensity of the second light is large.

The metal 3D printer monitoring method according to the present invention may further include a feedback step of stopping the process or changing the process conditions when a process abnormality diagnosis result occurs after performing the second step.

The first step may be performed using photodiodes having different wavelength response characteristics or using a photodiode and a wavelength filter.

The photodiode includes a first photodiode and a second photodiode, and the wavelength response characteristics of the first photodiode and the second photodiode are different, or the second photodiode is located together with the wavelength filter and is filtered by the wavelength filter. It can receive light.

There are a plurality of photodiodes, and each photodiode may have different wavelength response characteristics or may include different wavelength filters to receive light filtered by different wavelength filters.

Different wavelength filters can pass wavelength bands of 300 nm, 500 nm and 700 nm.

According to another aspect of the present invention, as a metal 3D printer monitoring device for performing a metal 3D printer monitoring method, a light inlet unit for introducing a second light generated from a metal powder melted by a first light irradiated from a printing head ; and an optical analyzer for measuring the wavelength and intensity of the introduced second light; a metal 3D printer monitoring device comprising a.

According to another aspect of the present invention, a 3D printing unit for producing a 3D output by irradiating and melting metal powder with light; And a monitoring unit for monitoring the printing process conditions by analyzing the light generated when the metal powder is melted; a metal 3D printer system capable of monitoring the process is provided, including.

According to embodiments of the present invention, 3D printing can be monitored at high speed compared to the process monitoring method using a conventional thermal imaging camera, and real-time monitoring is possible, so that high-quality 3D output can be obtained through change in process conditions. have.

In addition, according to the present invention, it is possible to calculate the optimal process conditions by performing various process monitoring, thereby eliminating errors in setting the initial conditions of the 3D printing process, thereby increasing the efficiency of the process.

1 is a cross-sectional view of a 3D printer monitored by a metal 3D printer monitoring method according to an embodiment of the present invention.
2 is a diagram illustrating a metal 3D printer system according to another embodiment of the present invention, and FIG. 3 is a diagram illustrating a metal 3D printer system according to another embodiment of the present invention.
4 is a graph analyzing light from a 3D output of a 3D printer by a metal 3D printer monitoring method according to another embodiment of the present invention, and FIG. 5 is a graph analyzing light when the printing head is moved 3 mm upward am.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiment of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. Embodiments of the present invention are provided in order to more completely explain the present invention to those of ordinary skill in the art. Although there may be components shown to have a specific pattern or a predetermined thickness in the accompanying drawings, this is for convenience of explanation or distinction, so even if the present invention has a specific pattern and a predetermined thickness, the characteristics of the components shown It is not limited to

1 is a cross-sectional view of a 3D printer monitoring by a metal 3D printer monitoring method according to an embodiment of the present invention, FIG. 2 is a view showing a metal 3D printer system according to another embodiment of the present invention, and FIG. It is a view showing a metal 3D printer system according to another embodiment of the invention. Hereinafter, it will be described with reference to FIGS. 1 to 3 .

Referring to FIG. 1 , a laser light 110 is irradiated from the printhead of the metal 3D printer 100 , and a 3D output 130 is output while the metal powder 120 is supplied. In this embodiment, the 3D printer is a 3D printer of the DED method. When a high-power laser beam is irradiated to the metal surface from the center of the DED head, a molten pool is instantaneously generated, and metal powder is also supplied, and the 3D molded body is laminated in real time while the printer head moves. to form The metal 3D printer monitoring apparatus 200 according to the present invention can monitor process conditions when molding the 3D output 130 in this way.

The metal 3D printer monitoring apparatus 200 according to the present invention is a metal 3D printer monitoring apparatus for performing a metal 3D printer monitoring method. a light inlet 210 for introducing a second light generated from the metal powder 120 that is melted by the first light, which is the laser light 110 irradiated from the printing head; and an optical analysis unit 220 that measures the wavelength and intensity of the introduced second light.

The metal 3D printer monitoring device 200 includes a first step of measuring the wavelength and intensity of the second light generated from the metal powder 120 melted by the first light irradiated from the printing head; and a second step of diagnosing the printing process of the 3D printer using the result value of at least one of the wavelength and intensity of light.

Referring to FIG. 2 , in the 3D output 130 , the metal powder 120 is melted by the laser light 110 , and light is generated, and the intensity and wavelength of the generated second light are analyzed by the optical analysis unit 220 . Process conditions can be monitored.

The optical analyzer 220 of the first step may be a spectrometer. The spectrometer acquires the second light generated from the 3D output 130 through the light inlet 210 such as an optical fiber, and measures the intensity and wavelength of the second light. The light analyzer 220 may output the intensity and wavelength measurement values of the second light to the display unit 230 .

When the metal powder 120 is injected into the region where the laser light 110 is concentrated, the metal powder 120 is melted and light is generated. At this time, when all of the metal powder 120 is injected into the region where the laser light 110 is concentrated, light having a narrow wavelength as a whole is generated. That is, it can be determined that the temperatures of the melted powders are relatively uniform. On the other hand, when the metal powder 120 is out of the region where the laser light 110 is concentrated, the temperature of the powder to be melted is non-uniform, so that light having a wide wavelength band is generated. Using this phenomenon, the metal 3D printing process is monitored by measuring the wavelength of light emitted while the metal powder 120 is melted.

In FIG. 3, instead of using the light inlet 210, the second light generated from the 3D output 130 is directly monitored. A dependent beamsplitter 210 may be used. In this case, an optical fiber can be connected to the spectrometer to be used as an auxiliary, or the spectrometer can be used directly without an optical fiber.

The optical analyzer 220 may include a photodiode and a wavelength filter. The photodiode includes a first photodiode and a second photodiode, and each photodiode has a different wavelength response characteristic or the second photodiode is positioned together with the wavelength filter to receive light filtered by the wavelength filter. . Alternatively, a plurality of photodiodes may be provided, and each photodiode may have different wavelength response characteristics or may include different wavelength filters to receive light filtered by different wavelength filters. For example, different wavelength filters may pass wavelength bands of 300 nm, 500 nm and 700 nm.

As the optical analyzer 220 , a photodiode and a wavelength filter may be used instead of an expensive spectrometer. For example, the optical analyzer 220 may be composed of two photodiodes and a wavelength filter used together with one photodiode. A photodiode without a wavelength filter monitors the entire light, and a photodiode with a wavelength filter monitors only the light of a corresponding band. When an abnormal process occurs based on the light amount of the photodiode under normal conditions, the presence or absence of process abnormality can be monitored from the value of each photodiode.

The optical analysis unit 220 may be configured using three photodiodes and a wavelength filter. For example, in the case of configuring the optical analysis unit 220 with three photodiodes and three wavelength filters, each filter is a filter that passes only a 300 nm band, a filter that passes only a 500 nm band, and a filter that passes only a 700 nm band. configurable. By comparing the reference value for each photodiode in the process under normal conditions and the value of the photodiode in the process, it is possible to check whether the process is abnormal or not, so metal 3D printing can be monitored.

4 is a graph analyzing light from a 3D output of a 3D printer by a metal 3D printer monitoring method according to another embodiment of the present invention, and FIG. 5 is a graph analyzing light when the printing head is moved 3 mm upward am. The graph of FIG. 4 shows a narrow wavelength band as a whole depending on the process conditions, so it is assumed that the metal powder is uniformly melted.

In contrast, the graph of FIG. 5 shows that light of a wide wavelength band is generated. FIG. 5 is a case in which the printer head is moved 3 mm upward than in the case of FIG. It can be seen that the melting by the laser light was not uniform because it was not located in the area and was widely distributed.

According to the analysis result of the optical analyzer, if the wavelength band of the second light is wide, it can be diagnosed that the metal powder is dispersed, and when the intensity of the second light is large, it can be diagnosed that the amount of the metal powder is large or the first light is strong. have. Accordingly, if the wavelength band is wide, the position of the print head may be adjusted, and if the intensity of the second light is high, the amount of metal powder may be reduced or the intensity of the laser beam may be reduced to return to the normal condition.

The metal 3D printer monitoring method according to the present invention may further include a feedback step of stopping the process or changing the process conditions when a process abnormality diagnosis result occurs after performing the second step. During the process, by monitoring the wavelength and intensity of light, if an abnormality occurs in the wavelength and intensity, the manufacturing cost can be reduced by stopping the process, or the stability of the process can be improved through feedback control.

According to another aspect of the present invention, a 3D printing unit for producing a 3D output by irradiating and melting metal powder with light; And a monitoring unit for monitoring the printing process conditions by analyzing the light generated when the metal powder is melted; a metal 3D printer system capable of monitoring the process is provided, including.

The monitoring method in the present invention can be applied to any method in which light is generated among methods of laminating metal by melting, such as PDF method, arc welding method, etc. in addition to the DED type 3D printer.

In the above, although embodiments of the present invention have been described, those of ordinary skill in the art can add, change, delete or add components within the scope that does not depart from the spirit of the present invention described in the claims. The present invention may be variously modified and changed by, etc., and this will also be included within the scope of the present invention.

100: 3D printer
110: laser light
120: metal powder
130: 3D output
200: metal 3D printer monitoring device
210: light inlet
220: optical analysis unit
230: display unit

Claims (12)

In the process monitoring method of a 3D printer for manufacturing 3D output using metal powder,
A first step of measuring the wavelength and intensity of the second light generated from the metal powder melted by the first light irradiated from the printing head; and
A metal 3D printer monitoring method comprising a; a second step of diagnosing the printing process of the 3D printer using the result value of at least one of the wavelength and intensity of light,
The first step is carried out using a spectrometer,
The second step is a metal 3D printer monitoring method, characterized in that if the wavelength band of the second light is wide, it is a step of diagnosing that the metal powder is dispersed.
delete The method according to claim 1,
A metal 3D printer monitoring method, characterized in that the spectrometer is connected to an optical fiber, and the second light is introduced into the spectrometer through the optical fiber.
delete delete The method according to claim 1,
After performing the second step, if a process abnormality diagnosis result occurs, a feedback step of stopping the process or changing the process conditions; Metal 3D printer monitoring method further comprising a.
The method according to claim 1,
The first step is a metal 3D printer monitoring method, characterized in that it is performed using a photodiode having different wavelength response characteristics, or using a photodiode and a wavelength filter.
8. The method of claim 7,
The photodiode includes a first photodiode and a second photodiode, and the wavelength response characteristics of the first photodiode and the second photodiode are different, or
A metal 3D printer monitoring method, characterized in that the second photodiode is positioned together with the wavelength filter to receive the light filtered by the wavelength filter.
8. The method of claim 7,
A metal 3D printer monitoring method, comprising a plurality of photodiodes, and each photodiode having different wavelength response characteristics or receiving light filtered by different wavelength filters including different wavelength filters.
10. The method of claim 9,
A metal 3D printer monitoring method, characterized in that the different wavelength filters pass the wavelength bands of 300 nm, 500 nm and 700 nm.
A metal 3D printer monitoring device for performing the metal 3D printer monitoring method according to claim 1,
a light inlet for introducing a second light generated from the metal powder melted by the first light irradiated from the printing head; and
A metal 3D printer monitoring device comprising a; an optical analyzer for measuring the wavelength and intensity of the introduced second light,
The optical analysis unit includes a spectrometer,
The optical analysis unit diagnoses the printing process of the 3D printer by using the result value of at least one of the wavelength and intensity of the light, and diagnoses that the metal powder is dispersed when the wavelength band of the second light is wide. .
a 3D printing unit for producing 3D output by irradiating and melting metal powder with light; and
A metal 3D printer system capable of process monitoring including; a monitoring unit including a metal 3D printer monitoring device according to claim 11 .

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