KR20220142313A - Optical coherence tomography system for sls metal 3d printer monitoring - Google Patents

Abstract

An optical coherence tomography system for monitoring a 3D printer in conjunction with the 3D printer according to an embodiment of the present invention includes: a light source radiating light; an optical splitter controlling paths of light; a reference end reflecting reference light distributed by the optical splitter to a reference reflected light; a measurement end directing measurement light distributed by the optical splitter towards an object being produced by the 3D printer, and delivering measurement reflected light reflected from the object; a detection unit receiving and analyzing interference light formed by the reference reflected light and the measurement reflected light; and an image generation unit generating a 2D or 3D image of the object based on the interference light analyzed by the detection unit, wherein the measurement end is designed to ensure that a laser light path of the printer and an optical path of the measurement light are the same at a specific point. As a result, it is possible to monitor the manufacturing process of a 3D structure without altering the shape and function of the manufactured object while remaining the structure or function of a selective laser sintering (SLS) metal 3D printer unchanged.

Description

OPTICAL COHERENCE TOMOGRAPHY SYSTEM FOR SLS METAL 3D PRINTER MONITORING

The present invention relates to an optical coherence tomography system for monitoring an SLS metal 3D printer, and more particularly, to an optical coherence tomography system for monitoring an SLS metal 3D printer for monitoring a product of a metal 3D printer.

A 3D printer is a device that produces three-dimensional objects, and the typical types of 3D printers are FDM (Fused Deposition Modeling), SLS (Selective Laser Sintering), SLA (Stereo Lithography Apparatus), and DLP (Digital Light Processing). ) methods, etc.

Among them, the SLS method selectively heats only a specific part of the powder material to harden it, and the pedestal in the powder moves to stack the output layer by layer. It has advantages, but it takes a relatively long time and the equipment is expensive.

In particular, in the case of an SLS metal 3D printer that uses titanium powder, the loss is large when a defect occurs because the titanium powder itself is a product. Fatal problems can arise.

To prevent this, it is necessary to monitor the manufacturing process of the 3D structure manufactured by the printer, but in the case of the SLS metal 3D printer, 3D monitoring of the structure in production is impossible due to the invisibility inside the production chamber that creates the 3D structure.

Therefore, the conventional monitoring method simply takes a picture using a camera at the top of the production chamber and performs monitoring in a way that reconstructs it in three dimensions, so there is a problem that the efficiency is low because the difference from the three-dimensional structure actually produced is large. have.

Korean Patent Publication No. 10-1850339

The present invention has been devised to solve the above problems, and an object of the present invention is to monitor the manufacturing process of the 3D structure by monitoring the fish chamber of the 3D structure produced by the 3D printer, and the manufacturing process of the 3D structure To provide an optical coherence tomography system for monitoring SLS metal 3D printers that can solve problems that may occur in

An optical coherence tomography system for monitoring the 3D printer in conjunction with a 3D printer according to an embodiment of the present invention for achieving the above object includes: a light source for irradiating light; a light splitter for controlling the path of light; a reference stage for transmitting the reference reflected light by reflecting the reference light distributed from the light splitter; a measuring stage irradiating the measurement light distributed from the light splitter toward the product manufactured by the 3D printer and transmitting the measurement reflected light reflected from the product; a detector for receiving and analyzing the interference light formed by the reference reflected light and the measured reflected light; and an image generator for generating a two-dimensional or three-dimensional image of the product based on the interference light analyzed by the detector, wherein the measuring end has the same laser optical path and the optical path of the measurement light at a specific point prepared to be done

Here, the measurement light may be irradiated outside the chamber in which the product is produced.

And the measuring end may include a dichroic mirror for making the laser optical path and the optical path of the measurement light the same.

In addition, the measurement end is located at the rear end of the dichroic mirror with respect to the direction in which the measurement light travels toward the product, and controls the optical path of the laser and the measurement light passing through the dichroic mirror. It may further include a galvanometer scanner (GS).

And it may further include a feedback unit that provides feedback to the 3D printer based on the image generated by the image generator, and controls the galvanometer scanner to change the optical path of the laser based on the feedback.

According to one aspect of the present invention described above, by providing an optical coherence tomography system for monitoring an SLS metal 3D printer, the shape and function of the manufactured product can be improved without changing the structure or function of the SLS type metal 3D printer. It is possible to monitor the manufacturing process of a 3D structure without deformation.

In addition, by monitoring the production process of a product using expensive powder, it is possible to prevent the production of defective products that occur during product production, as well as to prevent wastage of expensive powder due to the generation of defective products, thereby reducing costs.

1 is a view for explaining a state in which an optical coherence tomography system and a 3D printer are interlocked according to an embodiment of the present invention;
2 is a schematic diagram for explaining the structure of an optical coherence tomography system according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0016] Reference is made to the accompanying drawings, which show by way of illustration specific embodiments in which the present invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the present invention. It should be understood that the various embodiments of the present invention are different but need not be mutually exclusive. For example, certain shapes, structures, and characteristics described herein with respect to one embodiment may be implemented in other embodiments without departing from the spirit and scope of the invention. In addition, it should be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the present invention. Accordingly, the detailed description set forth below is not intended to be taken in a limiting sense, and the scope of the present invention, if properly described, is limited only by the appended claims, along with all scope equivalents to those claimed. Like reference numerals in the drawings refer to the same or similar functions throughout the various aspects.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the drawings.

1 is a view for explaining a state in which the optical coherence tomography system 1 and the 3D printer P are interlocked according to an embodiment of the present invention, and FIG. 2 is optical interference according to an embodiment of the present invention. It is a schematic diagram for demonstrating the structure of the tomography system 1 .

In general, in the case of an SLS-type metal 3D printer using titanium powder, a product is produced by melting titanium powder using a laser and then laminating it. Since it must be filled with gas, it is impossible to visually check the inside of the chamber (PC), and for this reason, three-dimensional monitoring of the product is impossible using the naked eye or an imaging device such as a camera.

In addition, in the case of titanium powder, because of its high cost, the reuse rate is high. As the frequency of reuse of titanium powder increases, the defect rate of the product also increases, so monitoring the production process of the product is essential.

The optical coherence tomography system 1 according to the present embodiment monitors the manufacturing process of the product manufactured by the 3D printer in conjunction with the 3D printer P as shown, and provides feedback according to the monitoring result to provide a defect rate of the product of course, it is possible to reduce the cost due to the production of defective products. The optical coherence tomography system 1 includes a communication unit 10 , an input unit 20 , a storage unit 30 , a control unit 40 , a light source 100 , an optical splitter 200 , a reference stage 300 , and a measurement stage. (400).

The input unit 20 is an input means for receiving a user command, and the communication unit 10 is for transmitting and receiving information provided for transmitting and receiving necessary information from an external device including a 3D printer and an external network. Although not shown in the drawings, an output unit (not shown) for displaying monitoring results such as a monitoring process of a product and a video image may be further included, and a display may be included as such an output unit.

In addition, the storage unit 30 records a program for performing monitoring, and provides a storage space necessary for the operation of the control unit 40 to temporarily or permanently store data processed by the control unit 40, and a volatile storage medium or a non-volatile storage medium, but the scope of the present invention is not limited thereto. Also, the storage unit 30 may store data accumulated while monitoring is performed. In addition, the storage unit 30 may store information including specific details such as the shape and dimensions of a product manufactured through the 3D printer P.

Meanwhile, the control unit 40 controls the communication unit 10 , the input unit 20 , the storage unit 30 , the light source 100 , the light splitter 200 , the reference terminal 300 , and the measurement terminal 400 to perform monitoring. and generates a result according to the monitoring, and generates feedback according to the monitoring result to provide feedback to the 3D printer (P). To this end, the control unit 40 may be provided to include a detection unit 500 , an image generation unit 600 , and a feedback unit 700 .

The detection unit 500 detects a spectrum of the interference light based on the interference light transmitted through the optical splitter 200, and can obtain an interference spectrum image through spectrum analysis, and uses this interference spectrum image to generate the image generation unit 600 can be passed to The configuration of the detection unit 500 will be described later in more detail along with the description of the measurement stage 400 .

The image generator 600 generates a two-dimensional or three-dimensional tomography image representing a product by processing the scan signal received from the detector 500 in an appropriate manner.

In addition, the feedback unit 700 may determine whether a product is defective or a matching rate based on the image of the product generated by the image generator 600 and provide feedback to the 3D printer P. Specifically, the feedback unit 700 compares the detailed information about the product under production stored in the storage unit 30 with the image of the generated product to determine whether the product is defective or the consistency rate of the product, and based on whether the product is defective or the matching rate You can generate feedback. And the feedback unit 700 controls the second galvanometer scanner 460 to be described later so that the optical path of the 3D printer (P) laser PL is changed based on the generated feedback, or the production of a product currently being produced is A stop signal may be transmitted to the printer P to be stopped. To this end, in the optical coherence tomography system 1 according to the present embodiment, software (application) for providing feedback may be installed and executed, and the control unit 40 including the feedback unit 700 is controlled by such software. can be

This not only lowers the defect rate of the product produced by the printer P, but also makes it possible to stop the operation of the printer P when the product being manufactured is defective as a result of monitoring, so a material such as powder for producing the product is required. It is possible to prevent overuse. In particular, in the case of the SLS-type metal 3D printer (P), since expensive titanium powder is used, the cost incurred due to defective products can also be reduced, thereby providing an economical effect.

Meanwhile, the light source 100 generates and emits light as a light source in the near-infrared band. The light source 100 is a light source for outputting light having a broad spectral radiation spectrum including a near-infrared region, and a high-brightness diode (Super Luminescent Diode), a titanium sapphire laser (Ti-Sapphire Laser), or a femtosecond laser (femtosecond laser) may be used. can

On the other hand, the optical splitter 200 is provided to adjust the path of the light, and the optical splitter 200 in this embodiment located at the rear end of the light source 100 based on the path through which the light moves is a fiber coupler, FC), it is possible to achieve stable and constant light distribution and output regardless of the angle of incidence of light, and to achieve a simple and compact configuration. And as shown in FIG. 2 , the light splitter 200 distributes the light output from the light source 100 to the reference end 300 and the measurement end 400 , and receives and measures the reference reflected light from the reference end 300 . The measurement reflected light may be received from the stage 400 and transmitted to the detection unit 500 . In this case, the distribution ratio of the reference light and the measurement light distributed by the light splitter 200 is preferably set to 50:50, but this may be changed as needed.

On the other hand, the reference stage 300 may reflect the reference light input through the light splitter 200 and transmit the reference reflected light reflected by the reference light back to the light splitter 200. For this purpose, as shown in FIG. 2, the first collimator It may be provided to include the 310 , the first lens 320 and the mirror 330 . The first collimator 310 is located at the rear end of the light splitter 200 based on the direction in which the reference light input through the light splitter 200 travels, and can convert the reference light into parallel light, and convert the parallel light into the first lens. forward to (320).

The first lens 320 is located at the rear end of the first collimator 310 and may transmit the received reference light to the mirror 330 , where the first lens 320 may be provided as a focusing lens.

In addition, the mirror 330 reflects the reference light received from the first lens 320 to generate reference reflected light, and the generated reference reflected light moves in the reverse direction of the path on which the reference light is incident and can be transmitted to the light splitter 200. have.

On the other hand, the measurement stage 400 irradiates the measurement light input through the light splitter 200 toward the product manufactured by the 3D printer P, and transmits the measurement reflected light generated by being reflected from the product to the light distributor 200 . do. In addition, the measuring stage 400 according to this embodiment is provided so that the optical path of the 3D printer laser PL and the optical path of the measurement light are the same at a specific point, so that the state of the product produced by the 3D printer P can be monitored. , for this purpose, the measurement stage 400 may allow the measurement light to be irradiated toward the product from the outside of the chamber PC in which the product of the 3D printer P is produced.

The measuring stage 400 according to this embodiment includes a second collimator 410 , a second lens 420 , a first galvanometer scanner 430 , a third lens 440 , a dichroic mirror 450 , It may include a second galvanometer scanner 460 and a fourth lens 470 .

Hereinafter, in describing the position of each component, the direction in which the measurement light distributed and input from the light splitter 200 moves toward the product will be described as a reference.

First, the second collimator 410 may be located at the rear end of the light splitter 200 to convert the measurement light distributed by the light splitter 200 into parallel light, and transmit the parallel light to the second lens 420 . have.

The second lens 420 is located at the rear end of the second collimator 410 and may transmit the received measurement light to a first galvanometer scanner (GS) 430, where the second lens 420 is It may be provided as a relay lens.

Meanwhile, the first galvanometer scanner 430 may be located at the rear end of the second lens 420 and may be reflected by continuously changing the angle of the incident light. The first galvanometer scanner 430 transmits the measurement light received from the second lens 420 to the third lens 440 .

And the third lens 440 is located at the rear end of the first galvanometer scanner 430, and transmits the measurement light reflected from the first galvanometer scanner 430 to the dichroic mirror 450, the third lens Like the second lens 420 , 440 may also be provided as a relay lens.

On the other hand, the dichroic mirror 450 is to make the optical path of the 3D printer laser PL and the optical path of the measurement light transmitted from the third lens 440 the same, and is located at the rear end of the third lens 440 but It may be provided to be positioned on a path through which the light of the 3D printer laser PL moves. In addition, the measurement light and the laser PL light having the same optical path through the dichroic mirror 450 are transmitted to the second galvanometer scanner 460 . Since the dichroic mirror 450 in this embodiment adds the existing optical path of the 3D printer laser PL, it does not change the structure or function of the existing SLS 3D printer P, as well as It may not change the form and function.

The second galvanometer scanner 460 is located at the rear end of the dichroic mirror 450 to adjust the optical path of the laser PL and the measurement light passing through the dichroic mirror 450, and through this, the measurement light And the light of the laser PL may be irradiated toward the workpiece. The light of the laser PL whose angle is adjusted through the second galvanometer scanner 460 and the measurement light are transmitted to the fourth lens 470 . In addition, the angle of the second galvanometer scanner 460 is adjusted by the control of the feedback unit 700. Based on the feedback generated by the feedback unit 700, the laser ( PL) Since the optical path of the light can be controlled, the production of defective products can be reduced.

The fourth lens 470 is located at the rear end of the second galvanometer scanner 460, and the measurement light and the laser PL light of which the angle is adjusted by the second galvanometer scanner 460 are irradiated toward the product. make it possible

In the measurement stage 400, through the above configuration, measurement light and laser (PL) light are irradiated into the chamber (PC) of the 3D printer where the product is being manufactured, and the measurement light generated by reflecting the measurement light from the product is the measurement light. Make it move in the opposite direction of the transmitted direction.

The reference reflected light and the measurement reflected light generated by the above-described reference terminal 300 and the measurement terminal 400 may be combined in the optical splitter 200, and as a result, the light interfered by the optical splitter 200 may be formed. The interference light may be transmitted to the detector 500 .

The detection unit 500 transmits the interference spectrum image obtained through spectrum analysis as described above to the image generation unit 600, and the detection unit 500 includes a third collimator 510, as shown in FIG. It may include a diffraction grating (DG) 520 , a fifth lens 530 , and a line scanner camera (LSC) 540 . Hereinafter, the direction in which the interference light is input to the detection unit 500 and travels will be described as a reference.

The third collimator 510 converts the input interference light into parallel light and transmits the parallel light to the diffraction grating 520 .

The diffraction grating 520 is located at the rear end of the third collimator 510 to diffract the interference light. In this embodiment, the diffraction grating 520 can be selected in various ways according to specifications, and the light diffracted from the diffraction grating 520 . Silver may be transmitted to the line scanner camera 540 through the fifth lens 530 provided at the rear end of the diffraction grating 520 . At this time, the fifth lens 530 is provided as a focusing lens, and a scan signal is generated through the line scanner camera 540 and transmitted to the image generator 600 . The image generator 600 may generate an image of a tomographic image of the product by measuring depth information of the product through Fourier transform on each pixel of the interference spectrum image received from the detection unit 500 .

Through the optical coherence tomography system 1 according to this embodiment, it is possible to monitor the process of manufacturing the 3D product in the 3D printer P.

In the above, various embodiments of the present invention have been illustrated and described, but the present invention is not limited to the specific embodiments described above, and it is common in the technical field to which the present invention pertains without departing from the gist of the present invention as claimed in the claims. Various modifications are possible by those having the knowledge of, of course, and these modifications should not be individually understood from the technical spirit or perspective of the present invention.

1: optical coherence tomography system 10: communication department
20: input unit 30: storage unit
40: control unit 100: light source
200: light splitter 300: reference stage
310: first collimator 320: first lens
330: mirror 400: measuring end
410: second collimator 420: second lens
430: first galvanometer scanner 440: third lens
450: dichroic mirror 460: second galvanometer scanner
470: fourth lens 500: detection unit
510: third collimator 520: diffraction grating
530: fifth lens 540: line scanner camera
600: image generating unit 700: feedback unit
P: SLS Metal 3D Printer PL: Printer Laser
PC: Chamber

Claims (5)

In the optical coherence tomography system for monitoring the 3D printer in conjunction with the 3D printer,
a light source irradiating light;
a light splitter for controlling the path of light;
a reference stage for transmitting the reference reflected light by reflecting the reference light distributed from the light splitter;
a measuring stage irradiating the measurement light distributed from the light splitter toward the product manufactured by the 3D printer and transmitting the measurement reflected light reflected from the product;
a detector for receiving and analyzing the interference light formed by the reference reflected light and the measured reflected light; and
An image generator for generating a two-dimensional or three-dimensional image of the product based on the interference light analyzed by the detector,
The measuring stage is
An optical coherence tomography system provided so that the laser optical path of the printer and the optical path of the measurement light are the same at a specific point. According to claim 1,
The measurement light is
Optical coherence tomography system, characterized in that irradiated outside the chamber in which the product is produced. 3. The method of claim 2,
The measuring stage is
and a dichroic mirror for making the laser optical path and the optical path of the measurement light the same. 4. The method of claim 3,
The measuring stage is
A galvanometer scanner that is located at the rear end of the dichroic mirror with respect to the direction in which the measurement light travels toward the product, and controls the optical path of the laser and the measurement light passing through the dichroic mirror (Galvanometer Scanner, GS), optical coherence tomography system, characterized in that it further comprises. 5. The method of claim 4,
Light characterized in that it provides feedback to a 3D printer based on the image generated by the image generator, and further comprises a feedback unit for controlling the galvanometer scanner to change the optical path of the laser based on the feedback coherence tomography system.

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