CN111781731A - Double-light-path coupling shaping device for metal SLM printing - Google Patents

Abstract

The invention provides a double-light-path coupling shaping device for metal SLM printing, which comprises two light path systems, a galvanometer system, a light beam coupler and a working platform, wherein a third variable-magnification beam expander and a galvanometer system are arranged in the propagation direction of flat-top light spots emitted by the first light path system, the third variable-magnification beam expander is connected with a first light beam shaping mechanism, the second light path system is vertically arranged above the space between the third variable-magnification beam expander and the galvanometer system, the light beam coupler is arranged at the vertical intersection of the flat-top light spots respectively emitted by the first light path system and the second light path system, and the working platform is arranged below the galvanometer system. The first optical path system and the second optical path system can perform synchronous or mutually independent coupling input of laser beams in different wavelength intervals through the beam coupler, one set of system can realize processing of different power interaction of two laser powers and six beam forms, and a new solution is provided for developing research of low-cost and multi-directional additive processing.

Description

A Dual Optical Path Coupling Shaping Device for Metal SLM Printing

technical field

The invention relates to the field of laser 3D printing, in particular to a double optical path coupling shaping device for metal SLM printing.

Background technique

Metal 3D printing is a current international research hotspot and an emerging field. 3D printing technology represented by selective metal laser melting (SLM) has been listed as one of the key core technologies of basic research work in my country. The difficulty lies in how to improve efficiency and ensure quality and consistency.

At present, SLM research at home and abroad basically defaults that the laser beam must conform to the Gaussian distribution. Once the power is increased, the unstable pinhole phenomenon will lead to a decrease in the amount, so that the printing efficiency cannot be fundamentally improved. According to relevant studies, the use of a near-flat-top distributed light source can improve the printing quality (significantly suppress splashes and reduce printing defects). In addition, when printing highly reflective materials such as copper/aluminum, short-wavelength lasers can significantly improve the laser absorption rate and reduce printing defects. production, thereby improving printing efficiency and quality.

Develop an optical device that takes into account both beam shaping and dual optical path coupling. On the one hand, the energy distribution and spot size of the beam can be changed, and lasers of different wavelengths and powers can be input synchronously or independently of each other. The research on metal additive manufacturing in the state of composite action is of great significance.

SUMMARY OF THE INVENTION

In order to solve the defects existing in the prior art, the present invention provides a dual optical path coupling input capable of realizing different wavelength bands and different powers, and at the same time, each optical path system can separately perform beam energy distribution state and spot shape shaping for metal SLM printing. Double optical path coupling shaping device, the specific scheme is as follows:

The optical path system includes a laser, a collimator, a variable magnification beam expander and a beam shaping mechanism arranged in sequence along the propagation direction of the outgoing laser beam from the laser. The laser is connected to the collimator through an optical fiber, and the collimator is connected to the variable magnification beam expander. , the variable magnification beam expander is connected to the beam shaping mechanism.

Further, the beam shaping mechanism includes an electric switching device, a beam homogenizer and a beam shaper, the electric switching device includes a first electric module, a second electric module and a fixing bracket, the first electric module and the second electric module are respectively fixed on both sides of the fixed bracket, the two ends of the first electric module are respectively provided with a first limit switch and a second limit switch, and the two ends of the second electric module are respectively provided with a third limit switch. A position switch and a fourth limit switch are provided, the beam homogenizer is arranged on the telescopic piece of the first electric module, and the beam shaper is arranged on the telescopic piece of the second electric module.

Further, the shape of the flat-top light spot after shaping by the beam homogenizer is a circular flat-top light spot, and the shape of the flat-top light spot after being shaped by the beam shaper is a rectangular flat-top light spot, a linear flat-top light spot, and an elliptical light spot. Flat-top light spot or custom-made flat-top light spot of specific shape according to demand.

Further, a control system is included, the control system is respectively connected to the first electric module, the second electric module, the first limit switch, the second limit switch, the third limit switch and the fourth limit switch.

The double optical path coupling shaping device for metal SLM printing includes a third variable magnification beam expander, a galvanometer system, a beam coupler, a working platform and an optical path system. There are two optical path systems, and the first optical path system emits a flat beam. The propagation direction of the top spot is provided with a third variable magnification beam expander and a galvanometer system, the third variable magnification beam expander is connected to the first beam shaping mechanism, and the second optical path system is vertically arranged on the third variable magnification beam expander. Above and between the galvanometer system, the beam coupler is arranged at the vertical intersection of the flat-top light spots respectively emitted by the first optical path system and the second optical path system, and the working platform is arranged below the galvanometer system.

Further, the galvanometer system is mainly composed of a first galvanometer, a second galvanometer and a field mirror, the first galvanometer is arranged in the horizontal direction where the beam shaping mechanism emits a flat-top spot and the second galvanometer is arranged side by side. In the vertical direction of the first galvanometer, the field mirror is arranged below the second galvanometer.

Adopting the shaping method for the double optical path coupling shaping device for metal SLM printing includes the following steps: the flat top light spot emitted by the first optical path system is adjusted by the third variable magnification beam expander to adjust its spot size with the second optical path system. The emitted flat-top light spots are respectively coupled into a beam of flat-top light spots through the beam coupler and enter the galvanometer system, and are collected by the galvanometer system on the working platform for laser processing.

Advantages of the present invention

(1) The present invention provides a dual optical path coupling shaping device for metal SLM printing, which can perform independent or synchronous coupling input of light sources of different wavelength bands and different powers.

(2) Each optical path system in the dual optical path of the present invention can realize Gaussian circular light spot, circular flat top light spot, rectangular flat top light spot, linear flat top light spot, Automatic switching of beam forms such as elliptical flat-top spot or custom-shaped flat-top spot according to requirements.

(3) In the dual optical path coupling shaping device of the present invention, since the laser beam has a flat-top distribution, the energy density within the range of the light spot is basically the same. In order to ensure that the power per unit area will not burn the material, the size of the light spot can be increased when the laser power is larger, thereby increasing the width and thickness of a single processing, thereby improving the printing efficiency.

(4) The dual optical path coupling shaping device of the present invention can input two lasers of different powers simultaneously, one of which is used as the main processing optical path, and the other is used for preheating or post-processing, which can effectively reduce the occurrence of printing cracks in high-hard materials. Tendency to improve print quality.

(5) The dual optical path coupling shaping device of the present invention can realize the processing of the interaction of two laser powers and six beam forms (each laser power is three beam forms) with different power interactions in one system, so as to develop low-cost and low-cost The study of multi-directional additive processing provides a solution.

Description of drawings

1 is a schematic structural diagram of a dual-optical path coupling beam shaping device for metal SLM printing according to the present invention;

FIG. 2 is a schematic diagram of a Gaussian laser emitted by a laser of each optical path system of FIG. 1 .

FIG. 3 is a schematic diagram of the shaped light spot coupling of the dual optical path system of FIG. 1;

FIG. 4 is a schematic diagram of the dual optical path coupling optical path of FIG. 1;

FIG. 5 is a schematic structural diagram of the beam shaping mechanism of FIG. 1 .

In the figure: 1, the first laser; 2, the first collimator; 3, the first variable magnification beam expander; 4, the beam homogenizer; 5, the beam shaper; 6, the third variable magnification beam expander Mirror; 7, beam coupler; 8, second laser; 9, second collimator; 10, second variable magnification beam expander; 11, first galvanometer; 12, second galvanometer; 13, field Mirror; 14. Working platform; 15. The first limit switch; 16. The second limit switch; 17. The third limit switch; 18. The fourth limit switch; 19. The first electric module; 20. The first Two electric modules; 21. Fixed bracket; G. Gaussian laser; r: spot radius of Gaussian laser; N: energy density; F1: circular flat-top spot; F2: rectangular flat-top spot; F3: linear flat-top spot; R: the spot radius of the flat-top spot; N1: the energy density of the flat-top spot.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the specific embodiments and accompanying drawings are not intended to limit the scope of rights of the present invention.

As shown in FIGS. 1 to 5 , the double optical path coupling shaping device for metal SLM printing provided by this specific embodiment includes an optical path system, a galvanometer system, a beam coupler 7 and a working platform 14. There are two optical path systems, respectively For the first optical path system and the second optical path system, a third variable magnification beam expander 6 and a galvanometer system are arranged in the propagation direction of the flat top light spot emitted by the first optical path system.

The first optical path system is composed of a first laser 1, a first collimator 2 along the propagation direction of the laser beam emitted by the first laser 1, a first variable magnification beam expander 3 and a first beam shaping mechanism to form a beam transmission channel, The first laser 1 is a fiber laser with a wavelength of 1070-1080 nm, and the laser beam is a Gaussian laser in a divergent state. The first laser 1 is connected to a first collimator 2 with an optical fiber interface through an optical fiber, the first collimator 2 is connected to the first variable magnification beam expander 3 through bolts, and the first variable magnification beam expander 3 is connected through bolts The first beam shaping mechanism, the first beam shaping mechanism 3 is connected to the third variable magnification beam expander 6 by bolts, and the first collimator 2 converts the laser beam emitted by the first laser 1 from a divergent state to a parallel state. The variable magnification beam expander 3 appropriately adjusts the size of the incident laser beam in the parallel state to meet the incident size requirements of the first beam shaping mechanism, and the shaped flat-top spot emitted by the first beam shaping mechanism is adjusted to achieve energy distribution and spot size changes.

The second optical path system is vertically arranged above the first optical path system and the galvanometer system. The second optical path system consists of the second laser 8, the second collimator 9 along the propagation direction of the laser beam emitted by the second laser 8, The second variable magnification beam expander 10 and the second beam shaping mechanism form a beam transmission channel, the second laser 8 is a non-fiber laser, the non-fiber laser is a semiconductor laser or a green laser, and the laser beam is in a nearly flat-top state or Gaussian divergence The state, wavelength and the first laser 1 are different. The second laser 8 is connected to the second collimator 9 with an optical fiber interface through an optical fiber, the second collimator 9 is connected to the second variable magnification beam expander 10 through bolts, and the second variable magnification beam expander 10 is connected through bolts The second beam shaping mechanism, the second collimator 9 converts the laser beam emitted by the second laser 8 from a divergent state to a parallel state, and the second variable magnification beam expander 10 appropriately adjusts the size of the incident laser beam in the parallel state , in order to meet the incident size requirement of the second beam shaping mechanism, and the flat-top spot adjustment after shaping by the second beam shaping mechanism realizes the change of energy distribution and spot size.

The functions of the first laser 1 and the second laser 2 are to emit laser beams and transmit them through an optical fiber. The laser beams are emitted from the optical fibers and then diverge and transmit.

The function of the first collimator 2 and the second collimator 9 is to connect the laser beams emitted by the first laser 1 and the second laser 2 respectively, and adjust the divergent transmission of the laser beams to be parallel transmission, and the energy distribution is Gaussian. distributed.

The functions of the first variable magnification beam expander 3 and the second variable magnification beam expander 10 are to appropriately adjust the size of the parallel light spots output by the first collimator 2 and the second collimator 9 respectively, so as to satisfy the requirements of the first beam respectively. The size requirements of the shaping mechanism and the second beam shaping mechanism for the laser beam.

The function of the third variable magnification beam expander 6 is to adjust the spot size of the flat-top spot emitted by the first optical path system.

The beam coupler is arranged at the vertical intersection of the flat top light spots respectively emitted by the first optical path system and the second optical path system. The first laser 1 and the second laser 2 can respectively emit laser beams of different powers and wavelengths synchronously, and the two laser beams can be coupled into one laser beam through the beam coupler 7 and then enter the galvanometer system to realize dual optical path coupling processing. The first laser 1 and the second laser 2 can also individually emit laser beams, which are coupled into the galvanometer system through the beam coupler 7 to realize single optical path coupling processing. The beam coupler 7 selects suitable coatings according to the wavelengths of the first laser 1 and the second laser 8, and configures the corresponding circulating cooling unit according to the corresponding power, which can effectively reduce the loss during the transmission of the laser beam and improve the service life.

As shown in FIG. 5 , the first beam shaping mechanism and the second beam shaping mechanism respectively include an electric switching device, a beam homogenizer 4, a beam shaper 5, a first limit switch 15, a second limit switch 16, a third The limit switch 17, the fourth limit switch 18 and the control system. The electric switching device includes a first electric module 19, a second electric module 20 and a fixed bracket 21. The first electric module 19 and the second electric module The group 20 is respectively fixed on both sides of the fixed bracket 21, the beam homogenizer 4 is arranged on the telescopic part of the first electric module 19, the first limit switch 15 and the second limit switch 16 are respectively arranged on the first electric module 19, the beam shaper 5 is arranged on the telescopic part of the second electric module 20, the third limit switch 17 and the fourth limit switch 18 are respectively arranged at both ends of the second electric module 20, the first The electric module 12 , the second electric module 13 , the first limit switch 15 , the second limit switch 16 , the third limit switch 17 and the fourth limit switch 18 are respectively connected to the control system.

The shape of the flat-top light spot after shaping by the beam homogenizer 4 is a circular flat-top light spot, and the shape of the flat-top light spot after being shaped by the beam shaper 5 is a rectangular flat-top light spot, a linear flat-top light spot, an elliptical flat-top light spot or according to Need to customize a specific shape of the flat top spot.

In use, in the initial state, the retractable part of the first electric module 19 is located at the first limit switch 15 , and the retractable part of the second electric module 20 is located at the third limit switch 17 .

When the laser beam in the divergent transmission state needs to be shaped into a circular flat-top spot, the control system controls the retractable part of the first electric module 19 to drive the beam homogenizer 4 to extend forward and enter the beam transmission channel, and the second limit After the switch 16 detects the signal of the beam homogenizer 4, it controls the first motorized module 19 to stop working, and sends the in-position detection signal of the beam homogenizer 4 entering the beam transmission channel to the control system.

When it needs to be shaped into a rectangular flat-top light spot, a linear flat-top light spot, an elliptical flat-top light spot, or a flat-top light spot with a specific shape customized according to requirements, the control system controls the expansion part of the first electric module 19 to drive the beam homogenizer 4 Retract backward and exit the beam transmission channel. After the first limit switch 15 detects the signal of the beam homogenizer 4, it controls the first electric module 19 to stop working, and sends the in-position detection information that the beam homogenizer 4 returns to the initial position. For the control system, the control system controls the retractable part of the second electric module 13 to drive the beam shaper 5 to extend forward and enter the beam transmission channel. After the fourth limit switch 18 detects the signal of the beam shaper 5, it controls the second The electric module 20 stops working, and sends the in-position detection signal of the beam shaper 5 entering the beam transmission channel to the control system.

The function of the beam homogenizer 4 is to adjust the circular parallel light spot with a Gaussian distribution to a circular parallel light spot with a flat top distribution, and the size of the light spot does not change before and after.

The function of the beam shaper 5 is to adjust the circular parallel light spot with Gaussian distribution into a rectangular or linear parallel light spot with flat top distribution, and the size of the light spot changes before and after.

The function of the electric switching device is to realize the automatic switching between the beam homogenizer 4 and the beam shaper 5, so as to realize the conversion of the circular flat-top spot and the rectangular/linear flat-top spot; After the beam shaper 5 is displaced, the original output state of the Gaussian laser is maintained.

The purpose of the first limit switch 15 is to limit the retractable member of the first electric module 19 to retract backward to the initial state, and to send an in-position detection signal of the initial position to the control system.

The purpose of the second limit switch 16 is to limit the forwardly extending position of the telescopic element of the first electric module 19 and to send a position detection signal of the forwardly extending beam homogenizer 4 to the control system.

The purpose of the third limit switch 17 is to limit the retractable member of the second electric module 20 to retract backward to the initial state, and to send the in-position detection signal of the initial position to the control system.

The purpose of the fourth limit switch 18 is to limit the forwardly extending position of the telescopic element of the second electric module 20, and to send the in-position detection signal of the forwardly extending beam shaper 5 to the control system.

The galvanometer system is mainly composed of a first galvanometer 11, a second galvanometer 12 and a field mirror 13. The first galvanometer 11 is arranged in the horizontal direction of the flat-top light spot propagation from the beam shaping mechanism, and the second galvanometer 12 is arranged side by side in the first galvanometer. In the vertical direction of the first galvanometer 11, the field mirror 13 is arranged below the second galvanometer 12, and the flat-top light spot is collected by the field mirror 13 and reaches the surface of the working platform 14 to process the metal powder. The working platform 14 is used as a powder printing carrier. below the mirror system.

The functions of the first galvanometer mirror 11 and the second galvanometer mirror 12 are to drive the mirrors to rotate through the rotation of the motor, thereby changing the transmission direction of the laser beam, and realizing the adjustment of the laser position in the X/Y directions. This system adopts a double galvanometer structure, and can design and select the galvanometer system and field mirror according to the printing format, power and wavelength requirements of the equipment.

The function of the field lens 13 is to focus the laser beam of the second galvanometer 12 to an appropriate size.

The working platform 14 is used as a platform for carrying metal powder, and the metal powder on the platform is melted by laser heating and multi-layered to form the final desired product.

The shaping method used for metal SLM printing double optical path coupling shaping device includes the following steps: the flat-top light spot emitted by the first optical path system is adjusted by the third variable magnification beam expander 6 after adjusting its spot size and the second optical path system respectively. The flat-topped light spot is coupled into a flat-topped light spot by the beam coupler 7 and enters the first galvanometer 11. After rotating the lens of the first galvanometer 11 to change the transmission direction of the flat-topped light spot, it enters the second galvanometer 12 and rotates the second galvanometer. The lens of the mirror 12 changes the transmission direction of the flat-top light spot and enters the field lens 13, and the field lens 13 gathers it on the working platform 14 for laser processing.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within the range.

Claims (7)

1. optical path system, it is characterized in that, comprise laser, collimator, variable magnification beam expander and beam shaping mechanism that are arranged successively along laser exit laser beam propagation direction, laser connects collimator by optical fiber, and collimator connects The variable magnification beam expander is connected to the beam shaping mechanism. 2 . The optical path system according to claim 1 , wherein the beam shaping mechanism includes an electric switching device, a beam homogenizer and a beam shaper, and the electric switching device includes a first electric module, a second electric A module and a fixing bracket, the first electric module and the second electric module are respectively fixed on both sides of the fixing bracket, and the two ends of the first electric module are respectively provided with a first limit switch and a second limit switch. Both ends of the second electric module are respectively provided with a third limit switch and a fourth limit switch, the beam homogenizer is arranged on the telescopic part of the first electric module, and the beam shaper is arranged on the telescopic part of the second electric module on the piece. 3 . The optical path system according to claim 2 , wherein the shape of the flat-topped light spot after shaping by the beam homogenizer is a circular flat-topped light spot, and the shape of the flat-topped light spot after being shaped by the beam shaper is 3 . For rectangular flat-top spot, linear flat-top spot, elliptical flat-top spot or custom-shaped flat-top spot on demand. 4. The optical path system according to claim 2, characterized in that it comprises a control system, the control system is respectively connected to the first electric module, the second electric module, the first limit switch, the second limit switch, The third limit switch and the fourth limit switch. 5. Double optical path coupling shaping device for metal SLM printing, characterized in that it comprises a third variable magnification beam expander, a galvanometer system, a beam coupler, a working platform and the optical path described in any one of claims 1 to 4 There are two optical path systems, the first optical path system is provided with a third variable magnification beam expander and a galvanometer system in the propagation direction of the flat top light spot, and the third variable magnification beam expander is connected to the first beam shaping The second optical path system is vertically arranged above between the third variable magnification beam expander and the galvanometer system, and the beam coupler is arranged at the vertical intersection of the flat top light spots emitted by the first optical path system and the second optical path system respectively, The working platform is set under the galvanometer system. 6. The dual optical path coupling shaping device for metal SLM printing according to claim 5, wherein the galvanometer system is mainly composed of a first galvanometer, a second galvanometer and a field mirror, and the first galvanometer system is composed of a field mirror. The mirror is arranged in the horizontal direction of the flat top light spot emitted by the beam shaping mechanism, the second galvanometer is arranged in parallel in the vertical direction of the first galvanometer, and the field mirror is arranged below the second galvanometer. 7. using the shaping method for metal SLM printing dual optical path coupling shaping device according to claim 5, it is characterized in that, comprises the following steps, the flat-top light spot emitted by the first optical path system is adjusted by the third variable magnification beam expander After the spot size, it is coupled with the flat-topped light spot emitted by the second optical path system through the beam coupler to form a flat-topped light spot, which enters the galvanometer system, and is focused on the working platform by the galvanometer system for laser processing.

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