CN111266581A

CN111266581A - Online coaxial closed-loop control laser selective melting/sintering printer and printing method

Info

Publication number: CN111266581A
Application number: CN202010188456.0A
Authority: CN
Inventors: 林紫雄; 林文雄; 黄见洪; 吴鸿春; 张志�; 陈金明; 翁文
Original assignee: Fujian Institute of Research on the Structure of Matter of CAS
Current assignee: Fujian Institute of Research on the Structure of Matter of CAS
Priority date: 2020-03-17
Filing date: 2020-03-17
Publication date: 2020-06-12
Anticipated expiration: 2040-03-17
Also published as: CN111266581B

Abstract

The invention discloses a selective laser melting/sintering printer based on online coaxial closed-loop control of sintering temperature and a printing method thereof. The printer controls laser output energy according to a molten pool temperature signal to form an online closed-loop temperature control system, the temperature of the surface of a material acted on is controllable and fixed no matter the material batch and the laser power attenuation or fluctuation, the optimal process parameters of a certain batch of laser states are obtained without a large number of manpower and material resources experiments, the parameters of power, speed and the like are determined without a large number of experiments, and the success rate and the stability of a selective laser melting/sintering part are obviously improved.

Description

Online coaxial closed-loop control laser selective melting/sintering printer and printing method

Technical Field

The invention belongs to the technical field of additive manufacturing, and particularly relates to a selective laser melting/sintering printer based on online coaxial closed-loop control of sintering temperature and a printing method.

Background

The selective laser melting/sintering additive manufacturing can realize the layer-by-layer stacking additive manufacturing of high polymer materials, metal materials and the like, and can prepare various complex structure molding processing which cannot be realized by the traditional method. However, the selective laser melting/sintering technique has a high dependence on the technological parameters of materials and equipment, resulting in a low success rate of the finished product. In order to improve the printing success rate, a large amount of manpower and material resources are often consumed to search for proper process parameters. And with different material batches, the change of the laser stability can bring about the change of the optimal process parameters, and the change of the performance of the finished piece is easy to cause. The principle of melting/sintering is that the proper laser energy density acts on the surface of the material, the temperature of the material rises, and the material is melted and sintered. The change of material parameters and laser parameters finally changes the energy density acting on the surface of the material or the absorption efficiency of the material to laser, thereby affecting the processing temperature of the material, bringing about the change of the microstructure components and the morphology of a workpiece and causing the performance fluctuation of the workpiece. At present, mainstream laser selective melting/sintering equipment does not have the capability of monitoring the online processing temperature, printing process parameters depend on a large amount of process tests and basic process data, the overall processing process parameter setting is blindness, and the success rate and the performance stability of a finished piece are generally low.

Disclosure of Invention

The invention aims to provide a selective laser melting/sintering printer based on-line coaxial closed-loop control of sintering temperature and a printing method.

In order to achieve the above object, according to one aspect of the present invention, there is provided a selective laser melting/sintering printer based on online coaxial closed-loop control of sintering temperature, comprising: a first dichroic mirror disposed on the optical path for reflecting the light beam of a specific wavelength returned from the powder to be printed; the scanning galvanometer and the light beam focusing device are arranged on the light path and are used for scanning and focusing the light beam; the printing bed is arranged opposite to the scanning galvanometer so that the laser reaches the powder to be printed on the printing bed; one end of the first dichroic mirror is sequentially connected with a filter and a high-speed thermometer, the part of the light beam reflected by the first dichroic mirror is filtered by the filter, the passing specific wavelength light beam reaches the high-speed thermometer, and the measured temperature information of the powder molten pool to be printed is fed back to the high-speed temperature controller, so that the laser energy output of the laser is regulated and controlled.

According to the invention, the light beam focusing device is a field lens arranged at the lower end of the scanning galvanometer or a dynamic focusing lens and a lens between the laser and the first dichroic mirror, and is used for focusing the light beam before entering the printing bed.

According to the invention, the selective laser melting/sintering printer further comprises a second dichroic mirror arranged on the light path, and the second dichroic mirror is connected with a CCD imaging temperature measuring device.

Preferably, the second dichroic mirror is disposed between the laser and the first dichroic mirror. More preferably, the frame rate of the CCD imaging thermometry device is 1000 fps. Preferably, the second dichroic mirror is coated with a different film than the first dichroic mirror.

According to the invention, the laser is a continuous wave fiber laser. Preferably, the continuous wave fiber laser has a wavelength of 1080nm and a power of 500W.

According to the invention, the high-speed thermometer is a dual-wavelength thermometer or a multi-wavelength thermometer. Preferably, the wavelength range is 900-1100 nm, and the response time of the wavelength meter is controlled in microsecond.

Preferably, the wavemeter response time is 50 μ s. Preferably, the response period and the sampling period of the high-speed temperature controller are in the order of microseconds. More preferably, the response period and the sampling period of the high-speed temperature controller are 200 μ s.

According to the invention, the selective laser melting/sintering printer further comprises a powder laying system, a powder feeding system, an atmosphere management system and a powder recovery system.

According to another aspect of the present invention, there is also provided a printing method of a selective laser melting/sintering printer based on online coaxial closed-loop control of sintering temperature, comprising the following steps:

s1, setting the target processing temperature and processing parameters of the material to be printed in advance according to the known performance parameters of the material to be printed;

s2, under the drive of the digital model layer cutting of the control system, sending an instruction to control the laser to emit laser, and focusing the output laser on a material to be printed of the printing bed after passing through the first dichroic mirror, the scanning galvanometer and the field lens; or the output laser is focused on the material to be printed of the printing bed after passing through the dynamic focusing lens, the first dichroic mirror and the scanning galvanometer;

s3, absorbing laser energy by the material to be printed, raising the temperature of a molten pool, and sending an infrared band temperature signal;

s4, after the infrared band temperature signal is totally reflected by the field lens, the scanning galvanometer and the first dichroic mirror, the temperature signal with the specific wavelength left by filtering of the filter plate reaches the high-speed thermometer to obtain an actually measured highest temperature signal of the molten pool, and the actually measured highest temperature signal is fed back to the high-speed temperature measurement controller;

and S5, the high-speed temperature measurement controller controls the laser power control signal by using a PID or neural network control algorithm according to the comparison analysis of the received measured temperature and the target processing temperature, and adjusts the output power of the laser to ensure that the temperature of a molten pool where the laser heats the material to be printed is kept at the target processing temperature value.

According to the present invention, the step of adjusting the laser output power in step S5 includes: when the measured temperature is lower than the target processing temperature of the material to be printed, the high-speed temperature controller sends a signal for increasing laser energy output to the laser device, the laser energy output of the material to be printed on the printing bed is improved, and the temperature of the printing bed is further improved; when the measured temperature is higher than the target processing temperature of the material to be printed, the laser energy output of the material to be printed on the printing bed is reduced, and the temperature of the printing bed is reduced.

According to the invention, the other path of temperature signal with specific infrared wavelength is reflected by the field lens, the scanning galvanometer and the second dichroic mirror and then enters the CCD imaging temperature measuring device to obtain the temperature distribution diagram of the light intensity of the spot sintering area at the molten pool along with the position distribution.

Preferably, the method further comprises the step of calibrating the maximum temperature measured by the high-speed thermometer, and the step comprises: and comparing the highest temperature of the molten pool measured by the high-speed temperature detector with the highest temperature measured by the CCD imaging temperature measuring device to calibrate the temperature field measured by the CCD imaging temperature measuring device, so that complete and accurate temperature distribution of the molten pool is output.

The invention has the beneficial effects that:

in the prior art, the batch change of materials and the change of sintering power caused by the attenuation and fluctuation of the power used by a laser are common and inevitable in the printing process, the selective laser melting/sintering printer can avoid the influence of the factors on the success rate and the performance of a workpiece, the target processing temperature and the processing parameters of a material to be printed, such as laser scanning speed, scanning interval and the like, are preset according to the performance parameters of the known materials, such as melting point, hot melting and the like, an online closed-loop temperature control system is formed by monitoring the sintering temperature on line and controlling the output energy of the laser according to the temperature signal of a molten pool at the powder position in the printing process, the temperature of the molten pool of powder can be directly monitored in the sintering process, the temperature of the laser acting on the surface of the material to be printed is ensured to be controllable and fixed, namely, the temperature of the material to be printed in the, the power density acting on the surface of the material is relatively determined, and no matter attenuation or fluctuation of material batches and laser power, a large amount of manpower and material resources experiments are not needed to be consumed to obtain the optimal process parameters of a batch in a certain laser state, and the process parameters of power, speed and the like are not needed to be determined through a large amount of experiments, so that the success rate and stability of the melting/sintering parts in the selective laser area are remarkably improved, and the economic benefit is remarkable.

Drawings

Fig. 1 is a schematic structural diagram of a selective laser melting/sintering printer according to embodiment 1 of the present invention.

Fig. 2 is a schematic view of the working flow of the selective laser melting/sintering printer in embodiment 1 of the present invention.

Fig. 3 is a schematic structural diagram of a selective laser melting/sintering printer in embodiment 2 of the present invention.

Reference numerals: 1. a laser; 2. a second dichroic mirror; 3. a CCD imaging temperature measuring device; 4. a first dichroic mirror; 5. a filter plate; 6. a high-speed thermometer; 7. scanning a galvanometer; 8. a field lens; 9. a printing bed; 21. a dynamic focusing mirror; 31. a lens; 91. focused laser beam.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings and embodiments. It should be emphasized that the specific embodiments described herein are merely illustrative of the invention, are some, not all, and therefore do not limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

As shown in fig. 1-3, the present invention provides a selective laser melting/sintering printer based on online coaxial closed-loop control of sintering temperature, wherein the online coaxial closed-loop control system of sintering temperature is the core of the printer. The printer comprises a laser 1, a printing bed 9, a first dichroic mirror 4 arranged on a light path, a scanning galvanometer 7 and a light beam focusing device. Wherein the scanning galvanometer 7 and the beam focusing means are used for scanning and focusing the light beam. The printing bed 9 is disposed opposite the scanning galvanometer 7 so that the laser heats the material to be printed on the printing bed 9. One end of the first dichroic mirror 4 is sequentially connected with a filter 5 and a high-speed thermometer 6, the first dichroic mirror 4 is used for reflecting a light beam with a specific wavelength returned from a position of a material to be printed, the light beam part reflected back through the first dichroic mirror 4 is filtered by the filter 5, the passing light beam with the specific wavelength reaches the high-speed thermometer 6, the temperature information of the material to be printed at a measured molten pool is fed back to the high-speed temperature controller, and then the laser energy output size of the laser 1 is regulated and controlled. In addition, the overall printer includes a powder spreading system, a powder feeding system, an atmosphere management system, and a powder recovery system (not shown).

In a preferred embodiment of the present invention, as shown in fig. 1, the beam focusing means is a field lens 8 disposed at the lower end of the scanning galvanometer 7 for focusing the beam before it is incident on the print bed 9.

In another preferred embodiment of the present invention, as shown in fig. 3, the beam focusing means is a dynamic focusing mirror 21 and a lens 31 disposed in sequence on the optical path. The anti-reflection coating of the field lens or the dynamic focusing lens 21 is matched with the laser wavelength. Preferably, dynamic focusing mirror 21 and lens 31 may be disposed between laser 1 and first dichroic mirror 4.

Preferably, in the case of large light spots, high-speed printing and the need of accurately monitoring the temperature distribution of the molten pool, one set or more than one set of second dichroic mirror 2 and a CCD imaging temperature measuring device 3 connected with the second dichroic mirror can be further provided. The CCD imaging temperature measuring device 3 can obtain the light intensity distribution of the appearance of the molten pool, the temperature recorded by the pixel points is calculated based on a Planck formula, and the highest temperature is obtained through the high-speed temperature measurer to calibrate the highest temperature of the CCD imaging temperature measuring device 3, so that the accurate temperature distribution of the molten pool is obtained.

Preferably, the second dichroic mirror 2 is disposed between the laser output head of the laser 1 and the first dichroic mirror 4. The two dichroic mirrors are commercially available products, but are coated differently, thereby reflecting laser beams of different wavelengths. The filter coating can filter out part of the laser light scattered and returned.

Preferably, the laser 1 is a continuous wave fiber laser. In one embodiment of the invention, the continuous wave fiber laser has a wavelength of 1080nm and a power of 500W. Preferably, the frame rate of the CCD imaging temperature measuring device 3 is 1000 fps.

Preferably, the high-speed thermometer 6 is a dual-wavelength thermometer or a multi-wavelength thermometer, the wavelength range is 900-1100 nm, the wavelength coverage range covers the sintering laser wavelength, and the response time of the wavelength meter is controlled in microsecond level. For example, the wavemeter response time may be 50 mus.

Preferably, the response period and the sampling period of the high-speed temperature controller are as short as possible, and are in the microsecond range. For example, the response period and sampling period of the high speed temperature controller may be 200 mus.

As shown in fig. 2, the present invention further provides a method for controlling a selective laser melting/sintering printer based on online coaxial closed-loop control of sintering temperature, comprising the following steps:

and S1, setting the target processing temperature and the processing parameters of the material to be printed in advance according to the known performance parameters of the material to be printed. The performance parameters of the material to be printed include, but are not limited to, melting point of the material, heat fusing, and the processing parameters include, but are not limited to, laser scanning speed, scanning interval, etc.

And S2, sending an instruction by the system according to the model layer cutting data, and cooperatively operating the scanning galvanometer 7 and the laser 1. The laser 1 emits laser, and the output laser passes through the first dichroic mirror 4, the scanning galvanometer 7 and the field lens 8 and then is focused on a material to be printed of the printing bed 9; or the output laser is focused on the material to be printed of the printing bed 9 after passing through the dynamic focusing mirror 21, the lens 32, the first dichroic mirror 4 and the scanning galvanometer 7.

S3, the material to be printed absorbs the laser energy (generally powder), the temperature of the powder at the molten pool rises rapidly, and an infrared band signal is sent out.

S4, reflecting the infrared wavelength temperature signal through the field lens 8, the scanning galvanometer 7 and the first dichroic mirror 2, then totally reflecting the specific wavelength temperature signal left after filtering through the filter 5 to the high-speed thermometer 6, actually measuring to obtain a molten pool highest temperature signal, and feeding back the actually measured highest temperature to the high-speed temperature controller.

And S5, the high-speed temperature controller outputs a control laser power control signal by using a PID (proportion integration differentiation) or neural network control algorithm and the like according to the comparison analysis of the received measured temperature and the target processing temperature, so that the output power of the laser is adjusted, and the temperature of the laser heating powder is at the target processing temperature value through the adjustment of the laser period. Therefore, the laser heating online coaxial closed-loop control is realized in the whole process, the powder sintering is ensured to be in a melting state rather than a gasification state, and the optimal process temperature is set according to the material characteristics without carrying out a large number of process test experiments blindly.

In the selective laser melting/sintering printer shown in fig. 1, another specific infrared wavelength temperature signal is also provided, and the other specific infrared wavelength temperature signal enters the CCD imaging temperature measuring device 3 after being reflected by the field lens 8, the scanning galvanometer 7 and the second dichroic mirror 2, so as to obtain a temperature distribution map of the light intensity of the spot sintering area at the molten pool along with the position distribution.

According to the present invention, the step of adjusting the laser output power in step S5 includes: when the measured temperature is lower than the target processing temperature of the material to be printed, the high-speed temperature controller sends a signal for increasing laser energy output to the laser, so that the laser energy output of the material to be printed on the printing bed 9 is improved, and the temperature of the printing bed 9 is further improved; when the measured temperature is higher than the target processing temperature of the material to be printed, the laser energy output of the material to be printed on the printing bed 9 is reduced, and the temperature of the printing bed 9 is reduced.

When the temperature distribution measured by the CCD imaging temperature measuring device is not accurate enough, the highest temperature obtained by the actual measurement of the high-speed temperature measuring meter 6 can be calibrated, and the method comprises the following steps: and comparing the highest temperature of the molten pool measured by the high-speed temperature detector 6 with the highest temperature measured by the CCD imaging temperature measuring device 3 to calibrate the temperature field measured by the CCD imaging temperature measuring device 3, so as to output complete and accurate temperature distribution of the molten pool.

The technical scheme of the invention is further explained by combining specific examples.

Example 1

As shown in the structure of fig. 1, the breadth of the printing bed of the selective laser melting/sintering printer based on online coaxial closed-loop control of sintering temperature is 300 × 300(mm), a continuous wave fiber laser is adopted, the wavelength is 1080nm, the power is 500W, and a power control voltage or current control mode is adopted. The focal length of the field lens 8 is 392mm, and the focused light spot is about 90 μm. The high-speed thermometer is a dual-wavelength pyrometer with the wavelength range of 900-1100 nm and the response time of 50 mu s. The frame rate of the CCD imaging temperature measuring device is 1000 fps. The high-speed temperature controller has a current or voltage output control function and adopts a period of 200 mu s.

The specific working process is as follows: the printing model is a five-pointed star, the powder to be printed is TC4 material, the melting point temperature is 1678 ℃, the printing process parameters are input in advance, the printing target processing temperature is set to 1750 ℃, the processing parameters are such as the laser scanning speed of 0.8m/s, and the interval is 75 um.

Under the drive of the digital layer cutting, the system sends out an instruction to control the laser to emit light and scan the galvanometer to work in coordination. Laser passes through a laser output head (beam expanding collimating lens), two dichroic mirrors, a scanning galvanometer and a field lens and then is focused on a printing bed, and powder absorbs laser energy, so that the temperature rises and a temperature signal is sent out. One path of specific infrared wavelength temperature signal is reflected to enter a CCD imaging temperature measuring device after passing through a field lens, a scanning galvanometer and a first dichroic mirror, and a signal of light intensity distribution along with the position in a light spot sintering area is obtained. And the other path of specific wavelength temperature signal is returned and then reflected back through the field lens, the scanning galvanometer and the second dichroic mirror, part of the specific wavelength temperature signal is filtered by the filter, the passing specific wavelength light beam enters the high-speed thermodetector to obtain a highest temperature signal of the molten pool, and then the highest temperature signal is fed back to the high-speed temperature controller, the measured actual temperature and the target processing temperature are compared and analyzed by the high-speed temperature controller, and then the optimal laser control signal output quantity is obtained according to a PID (proportion integration differentiation) or neural network algorithm, and the laser energy output is controlled. And if the actual measurement temperature is lower than the target processing temperature, increasing the laser energy output, improving the energy input of the target printing bed powder, and improving the temperature of the printing bed. And if the actual measurement temperature is higher than the target processing temperature, reducing the laser energy output and reducing the temperature of the printing bed. In the whole process, online closed-loop temperature control is realized. The highest temperature of the molten pool measured by the high-speed temperature detector is compared with the highest temperature measured by the CCD imaging temperature measuring device, and the temperature field measured by the CCD imaging temperature measuring device is calibrated, so that complete and accurate temperature distribution of the molten pool is output.

Example 2

As shown in FIG. 3, the selective laser melting/sintering printer based on online coaxial closed-loop control of sintering temperature uses a continuous wave fiber laser, the laser output head can select a collimator, the wavelength is 1080nm, the power is 500W, and the power control voltage or current control mode can be selected. The printing bed is arranged on an output light path below the scanning galvanometer, and the breadth of the printing bed is 300 x 300 (mm). The dynamic focusing mirror, the lens, the second dichroic mirror and the scanning vibration mirror are sequentially arranged on the light path, one end of the second dichroic mirror is provided with a high-speed temperature detector, and the filter is arranged between the second dichroic mirror and the high-speed temperature detector. The dynamic focusing light spot is about 90 mu m, the high-speed thermometer is a dual-wavelength pyrometer, the wavelength range is 900-1100 nm, and the response time is 50 mu s; the high-speed temperature controller adopts a period of 200 mu s and has a current or voltage output control function.

The specific working process is as follows: the printing model is a five-pointed star, the powder to be printed is TC4 material, the melting point temperature is 1678 ℃, the printing process parameters are input in advance, the processing temperature of the printing target is 1750 ℃, the laser scanning speed is 0.8m/s, and the interval is 75 um.

Under the drive of the digital layer cutting, the system sends out an instruction to control the laser to emit light and the dynamic focusing mirror to work cooperatively. Laser passes through a laser output head (beam expanding collimating lens), a dynamic focusing lens, a dichroic mirror and a scanning galvanometer and then is focused on a powder bed. The powder absorbs the laser energy, the temperature rises and a temperature signal is sent out. One path of specific infrared wavelength temperature signal is reflected to enter a CCD imaging temperature measuring device after passing through a scanning vibrating mirror and a second dichroic mirror, and a signal of light intensity distribution along with the position in a light spot sintering area is obtained. And the other path of temperature signal with specific wavelength returns, then is reflected by the scanning vibrating mirror and the first dichroic mirror, part of the temperature signal is filtered by the filter, and the passing light beam with specific wavelength enters the high-speed temperature detector to obtain the highest temperature signal of the molten pool. And the highest temperature signal of the molten pool is accessed into a high-speed temperature measurement controller, the measured temperature is compared with the target set temperature for analysis, the optimal laser control signal output is obtained according to a PID (proportion integration differentiation) or neural network algorithm, and the laser energy output is controlled. If the measured temperature is below the target set temperature, the laser energy output is increased, the target powder bed energy input is increased, and the powder bed temperature is increased. If the measured temperature is above the target set temperature, the laser energy output is reduced, reducing the powder bed temperature.

Because the whole process realizes on-line closed-loop temperature control, the temperature of the material in the printing process is controllable in real time, the printing is successfully realized once, the problem that the process parameters are obtained by a blind trial and error mode (generally, new materials are printed for more than 5 times) in the past printing is solved, and the printing success rate and the stability are greatly improved.

Claims

1. A selective laser melting/sintering printer based on online coaxial closed-loop control of sintering temperature comprises:

a first dichroic mirror (4) disposed on the optical path for reflecting the light beam of a specific wavelength returned from the powder to be printed;

the scanning galvanometer (7) and the light beam focusing device are arranged on the light path and are used for scanning and focusing the light beam; and

a printing bed (9) arranged opposite to the scanning galvanometer (7) so that the laser light reaches the powder to be printed on the printing bed;

wherein, the one end of first dichroic mirror (4) connects gradually filter (5) and high-speed thermoscope (6), and the process the light beam part that first dichroic mirror (4) reflect back is filtered by filter (5), and the specific wavelength light beam that passes through reachs high-speed thermoscope (6), feeds back the temperature information of waiting to print the powder molten bath of survey to high-speed temperature controller, and then regulates and control the laser energy output size of laser instrument (1).

2. The selective laser melting/sintering printer according to claim 1, characterized in that the beam focusing means is a field lens (8) arranged at the lower end of the scanning galvanometer (7) for focusing the beam before it is incident on the printing bed (9).

3. The selective laser melting/sintering printer of claim 1,

the light beam focusing device is a dynamic focusing mirror (21) and a lens (31) which are arranged between the laser and the first dichroic mirror (4) and are used for focusing the light beam before the light beam is incident on the printing bed (9).

4. The selective laser melting/sintering printer according to claim 1 or 2, further comprising a second dichroic mirror (2) disposed in the optical path, wherein the second dichroic mirror (2) is connected with a CCD imaging temperature measuring device (3).

Preferably, the second dichroic mirror (2) is arranged between the laser (1) and the first dichroic mirror (4).

More preferably, the frame rate of the CCD imaging temperature measuring device (3) is 1000 fps.

Preferably, the second dichroic mirror (2) is coated differently from the first dichroic mirror (4).

5. The selective laser melting/sintering printer according to claim 1, characterized in that the laser (1) is a continuous wave fiber laser.

6. A selective laser melting/sintering printer according to any of claims 1 to 5, characterised in that the high-speed thermometers (6) are dual-wavelength thermometers or multi-wavelength thermometers.

Preferably, the wavelength range is 900-1100 nm, and the response time of the wavelength meter is controlled in microsecond.

Preferably, the wavemeter response time is 50 μ s.

Preferably, the response period and the sampling period of the high-speed temperature controller are microsecond.

More preferably, the response period and the sampling period of the high-speed temperature controller are 200 μ s.

7. The selective laser melting/sintering printer of any of claims 1-6 further comprising a powder placement system, a powder delivery system, an atmosphere management system, and a powder recovery system.

8. The printing method of the selective laser melting/sintering printer based on the online coaxial closed-loop control of the sintering temperature as claimed in any one of claims 1 to 7, comprising the steps of:

s2, under the drive of the digital model layer cutting of the control system, sending an instruction to control the laser (1) to emit laser, wherein the output laser passes through the first dichroic mirror (4), the scanning galvanometer (7) and the field lens (8) and then is focused on a material to be printed on the printing bed (9); or

The output laser passes through a dynamic focusing mirror (21), a lens (32), a first dichroic mirror (4) and a scanning galvanometer (7) and then is focused on a material to be printed of a printing bed (9);

s4, after the infrared band temperature signal is totally reflected by the field lens (8), the scanning galvanometer (7) and the first dichroic mirror (2), the temperature signal with the specific wavelength left after being filtered by the filter plate (5) reaches the high-speed temperature detector (6), the actual measurement highest temperature signal of the molten pool is obtained, and the actual measurement highest temperature signal is fed back to the high-speed temperature measurement controller;

9. The method according to claim 8, wherein the step of adjusting the laser output power in step S5 comprises:

when the measured temperature is lower than the target processing temperature of the material to be printed, the high-speed temperature controller sends a signal for increasing laser energy output to the laser, so that the laser energy output of the material to be printed on the printing bed (9) is improved, and the temperature of the printing bed (9) is further improved;

when the measured temperature is higher than the target processing temperature of the material to be printed, the laser energy output of the material to be printed on the printing bed (9) is reduced, and the temperature of the printing bed (9) is reduced.

10. The control method according to claim 8 or 9, characterized in that the other path of temperature signal with specific infrared wavelength enters the CCD imaging temperature measuring device (3) after being reflected by the field lens (8), the scanning galvanometer (7) and the second dichroic mirror (2), so as to obtain the temperature distribution map of the light intensity of the light spot sintering area along with the position distribution at the molten pool.

Preferably, the method further comprises the step of calibrating the maximum temperature measured by the high-speed thermometer (6), and the step comprises the following steps: and comparing the highest temperature of the molten pool measured by the high-speed temperature detector (6) with the highest temperature measured by the CCD imaging temperature measuring device (3) to calibrate the temperature field measured by the CCD imaging temperature measuring device (3), thereby outputting complete and accurate temperature distribution of the molten pool.