CN108838397A - A kind of laser gain material manufacture on-line monitoring method - Google Patents

Abstract

The invention discloses an on-line monitoring method for laser additive manufacturing, which includes: collecting the central temperature and diameter of the molten pool in real time; when the collected central temperature of the molten pool or the diameter of the molten pool does not meet the pre-stored laser power P When there is a relationship between the temperature of the molten pool center and the diameter of the molten pool, the laser power P is adjusted according to the relationship so that the collected central temperature of the molten pool and the diameter of the molten pool are in line with the pre-stored laser power P and the center of the molten pool. The relationship between temperature and molten pool diameter. Applying the online monitoring method of laser additive manufacturing provided by the present invention realizes the purpose of online monitoring and control, and changes post-event detection into in-event intervention. It has the advantages of good controllability and high processing efficiency, and can be better applied to ships and rails Large-scale, large-area online monitoring in transportation and other fields is better adapted to the flexible manufacturing environment and has far-reaching practical significance.

Description

A method for online monitoring of laser additive manufacturing

technical field

The invention relates to the technical field of additive manufacturing, and more specifically, to an online monitoring method for laser additive manufacturing.

Background technique

The process of laser additive manufacturing is different from that of traditional materials. After casting, forging, and processing, traditional materials use X-ray, ultrasonic and other testing methods to determine whether the materials are qualified. Unqualified products are scrapped or welded. method to remedy. However, because laser additive manufacturing is produced by layer-by-layer stacking, it is significantly different from traditional manufacturing methods in terms of quality monitoring and monitoring.

For additive manufacturing, typically, each laser scan melts and resolidifies several layers of powder, typically 20 μm to several mm thick. After each laser shot, additional powder is scraped from the work area (powder spreading) or fresh powder is directly fed (powder feeding) for melting, and the process is repeated until a solid three-dimensional (3D) part is built. Each "build" process contains thousands of layers, so each run can take tens to hundreds of hours. Each "build" can generate dozens of identical or different parts.

Considering the above issues together, especially those parts that play a key role in the structure, the major challenge for the wide application of additive manufacturing technology is the qualification of the finished product and how to verify its qualification. Recently, several reports on additive manufacturing have called for in-line, closed-loop process control and sensors to ensure the quality, consistency and reproducibility of additive manufacturing. In-line quality monitoring, which facilitates waste reduction, will eliminate the need for inspection or destructive testing that would normally be performed after construction.

With the rapid development of industries such as ships, aerospace, rail transit, etc., under the influence of the price drop of laser equipment and the improvement of automation, the requirements for the quality of additive manufacturing are getting higher and higher, and the existing quality inspection methods can no longer meet the current requirements. There are quality requirements for laser additive manufacturing and realistic needs for automation in the manufacturing industry. Therefore, it is necessary to design an online monitoring method for laser additive manufacturing.

To sum up, how to effectively solve the problems that the quality requirements of laser additive manufacturing are difficult to meet is an urgent problem for those skilled in the art.

Contents of the invention

In view of this, the object of the present invention is to provide an online monitoring method for laser additive manufacturing, which can effectively solve the problem that the quality requirements of laser additive manufacturing are difficult to meet.

In order to achieve the above object, the present invention provides the following technical solutions:

An online monitoring method for laser additive manufacturing, comprising:

Real-time collection of molten pool center temperature and molten pool diameter;

When the collected melt pool center temperature or melt pool diameter does not conform to the relationship between the pre-stored laser power P and the melt pool center temperature and melt pool diameter, the laser power P is adjusted according to the relationship so that the collected The temperature at the center of the molten pool and the diameter of the molten pool conform to the pre-stored relationship between the laser power P and the central temperature of the molten pool and the diameter of the molten pool.

Preferably, in the above online monitoring method for laser additive manufacturing, the relationship between the pre-stored laser power P and the central temperature of the molten pool and the diameter of the molten pool specifically includes:

By fixing any two of the laser power P, laser scanning speed V and powder feeding rate Mp respectively, change the other one to conduct experiments and record the temperature at the center of the molten pool and the diameter of the molten pool, and use metallographic analysis and calculation The resulting dilution rate and cladding layer shape factor determine and store the relationship between the laser power P, the temperature of the center of the molten pool and the diameter of the molten pool;

Or by fixing any two of the laser power P, laser scanning speed V and powder coating thickness respectively, change the other one to test and record the temperature at the center of the molten pool and the diameter of the molten pool, and use metallographic analysis and calculation The resulting dilution rate and cladding layer shape factor determine and store the relationship between the laser power P, the temperature of the center of the molten pool and the diameter of the molten pool.

Preferably, in the online monitoring method of laser additive manufacturing, before the real-time collection of the central temperature of the molten pool, the steps further include:

S01: Place the test sample at the designated location;

S02: Fix the laser scanning speed V and the laser powder feeding rate Mp, change the laser power P to conduct experiments, record the temperature of the molten pool center and the diameter of the molten pool, and obtain the temperature data of the molten pool center and the molten pool under different laser power P diameter data;

And carry out metallographic analysis on the obtained experimental sample, obtain the molten pool shape parameter data of the experimental sample, and determine the suitable laser power and the corresponding molten pool center temperature data and molten pool diameter data, and obtain the laser The scanning speed V and the laser powder feeding rate Mp or the relationship between the center temperature of the molten pool and the diameter of the molten pool and the laser power under the powder coating thickness are determined according to the effective relationship T1;

S03: Fix the laser power P and the laser powder feeding rate Mp or the powder coating thickness, change the laser scanning speed V to conduct experiments, record the temperature of the molten pool center and the diameter of the molten pool, and obtain the temperature data of the molten pool center at different laser scanning speeds V and molten pool diameter data;

And carry out metallographic analysis to the obtained experimental sample, obtain the molten pool shape parameter data of described experimental sample, and determine suitable described laser scanning velocity V and corresponding molten pool central temperature data and molten pool diameter data, obtain the obtained The relationship between the laser power P and the laser powder feeding rate Mp or the laser scanning speed V when the powder thickness is constant, the temperature of the center of the molten pool and the diameter of the molten pool is determined according to the criterion to determine the effective relationship T2;

S04: Fix the laser power P and laser scanning speed V, change the powder feeding rate Mp or powder coating thickness to conduct experiments, record the temperature of the molten pool center and the diameter of the molten pool, and obtain the molten pool under different powder feeding rates Mp or powder coating thickness Central temperature data and molten pool diameter data;

And carry out metallographic analysis to the obtained experimental sample, obtain the molten pool shape parameter data of the experimental sample, and determine the suitable powder feeding rate Mp or powder coating thickness and corresponding molten pool center temperature data and molten pool diameter data, obtain the relationship between the laser power P and the laser scanning speed when the laser powder feeding rate Mp or powder coating thickness and the center temperature of the molten pool and the diameter of the molten pool are determined, and the effective relationship T3 is determined according to the criterion;

S05: According to the effective relational expression T1, the effective relational expression T2 and the effective relational expression T3, determine the laser scanning power P and the molten pool center temperature and melting The valid relation T4 for the pool diameter is stored.

Preferably, in the online monitoring method of laser additive manufacturing, the recording of the temperature and diameter of the molten pool center specifically includes using a temperature recorder to record the temperature at the center of the molten pool and using an infrared CCD camera to record the diameter of the molten pool.

Preferably, in the above online monitoring method for laser additive manufacturing, before the step S1, it also includes:

Install the multi-wavelength pyrometer, CCD high-speed infrared camera, laser processing head, laser power detector, CCD high-speed camera and protective gas pipeline according to the requirements.

Preferably, in the online monitoring method of laser additive manufacturing, the laser processing head, the laser power meter, the CCD high-speed camera and the multi-wavelength pyrometer are coaxially installed, and the shielding gas pipeline is aligned with the laser melting Central location of the pool.

Preferably, in the above online monitoring method for laser additive manufacturing, the adjustment of the laser power P is specifically:

The laser power P is adjusted by a laser power detector.

Apply the online monitoring method of laser additive manufacturing provided by the present invention, by collecting the center temperature of the molten pool in real time; When the relationship between the laser power P and the molten pool center temperature and molten pool diameter is adjusted, the laser power P is adjusted so that the collected molten pool central temperature and molten pool diameter are consistent with the pre-stored laser power P and molten pool central temperature Corresponding relationship with the molten pool diameter. In this way, the purpose of online monitoring and control can be realized, and post-event detection can be changed into intervention in the event, which has far-reaching practical significance for the development of green manufacturing and intelligent manufacturing. At the same time, it can avoid the disadvantages of difficult operation and huge loss of destructive detection after the event.

In a preferred embodiment, the relationship between the pre-stored laser power P and the temperature of the molten pool center and the diameter of the molten pool specifically includes: fixing any of the laser power P, laser scanning speed V and powder feeding rate Mp respectively Two, change the other to test and record the temperature of the molten pool center and the diameter of the molten pool, and use the metallographic analysis and calculated dilution rate and cladding layer shape factor to determine the laser power P and the temperature of the molten pool center and The relationship between the molten pool diameter and stored. Use this relational data to process the actual workpiece, and compare it with the standard data stored in the system, that is, the relational expression, to check whether it meets the requirements of laser additive materials, so as to achieve the purpose of online monitoring and control. In this way, it is simple and reliable to obtain the relationship between the laser power P and the temperature of the center of the molten pool and the diameter of the molten pool.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a schematic flow chart of an online monitoring method for laser additive manufacturing according to a specific embodiment of the present invention;

Fig. 2 is a structural schematic diagram of an online monitoring device using the laser additive online monitoring method provided by the present invention;

Figure 3 is a schematic diagram of the shape during laser additive manufacturing.

The markings in the attached drawings are as follows:

1-substrate; 2-shielding gas tube; 3-cladding layer; 4-laser beam; 5-high temperature thermometer; 6-laser power meter; 7-optical fiber; Cladding layer; 10-substrate; W-melting layer width; H-melting layer height; b-substrate is melted depth.

The cladding layer dilution rate d is: The cladding layer shape factor AR is:

Detailed ways

The embodiment of the present invention discloses an on-line monitoring method for laser additive manufacturing, so as to realize the online monitoring requirement when it is necessary to prepare a material containing a ceramic strengthening phase coating for additive manufacturing.

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Please refer to Fig. 1-Fig. 3, Fig. 1 is a schematic flow chart of the online monitoring method of laser additive manufacturing in a specific embodiment of the present invention; Fig. 2 is a schematic structural diagram of an online monitoring device using the online monitoring method of laser additive manufacturing provided by the present invention ; Figure 3 is a schematic diagram of the shape of the laser additive manufacturing process.

In a specific embodiment, the online monitoring method of laser additive manufacturing provided by the present invention can be specifically used for laser additive manufacturing when metal powder is added with reinforced phase ceramic powder, including the following steps:

S1: Real-time collection of molten pool center temperature and molten pool diameter;

S2: When the collected melt pool center temperature or melt pool diameter does not conform to the relationship between the pre-stored laser power P, melt pool center temperature, and melt pool diameter, then according to the relationship between laser power P, melt pool center temperature, and melt pool diameter, Relationship Adjust the laser power P so that the collected melt pool center temperature and melt pool diameter are consistent with the pre-stored relationship between the laser power P and the melt pool center temperature and melt pool diameter.

That is, the relationship between the laser power P and the center temperature of the molten pool and the diameter of the molten pool is obtained in advance and stored. In the laser additive manufacturing process, the actual workpiece is processed using a relational expression. When the real-time collected molten pool center temperature or molten pool diameter does not conform to the relationship, the laser power P is adjusted accordingly so that the collected current molten pool central temperature The corresponding relationship between the diameter of the molten pool and the current laser power P conforms to the above pre-acquired corresponding relationship. Through the above process to achieve the purpose of online monitoring and control, changing post-event detection into in-event intervention has far-reaching practical significance for the development of green manufacturing and intelligent manufacturing. At the same time, it can avoid the disadvantages of difficult operation and huge loss of destructive detection after the event.

Specifically, the relationship between the pre-stored laser power P and the center temperature of the molten pool and the diameter of the molten pool includes:

By fixing any two of the laser power P, laser scanning speed V and powder feeding rate Mp respectively, change the other one to conduct experiments and record the temperature at the center of the molten pool and the diameter of the molten pool, and use metallographic analysis and calculation The resulting dilution rate and cladding layer shape factor determine and store the relationship between the laser power P, the temperature of the center of the molten pool and the diameter of the molten pool;

Or by fixing any two of the laser power P, laser scanning speed V and powder coating thickness respectively, change the other one to test and record the temperature at the center of the molten pool and the diameter of the molten pool, and use metallographic analysis and calculation The resulting dilution rate and cladding layer shape factor determine and store the relationship between the laser power P, the temperature of the center of the molten pool and the diameter of the molten pool.

That is to say, through the test, the center temperature of the molten pool and the diameter of the molten pool corresponding to the surface of the test sample are obtained during additive manufacturing, and the dilution rate and cladding layer shape factor obtained by metallographic analysis and calculation are used to determine and form the corresponding relationship data , using the relational data to process the actual workpiece.

Specifically, before step S1 collects the central temperature of the molten pool and the diameter of the molten pool in real time, it also includes steps:

S01: Place the test sample at the designated location;

Preferably, before placing the test sample, each device can also be installed and set up. Specifically, the multi-wavelength pyrometer, CCD high-speed infrared camera, laser processing head, laser power detector, CCD high-speed camera and protective gas pipeline are installed and set up according to requirements.

S02: Fix the laser scanning speed V and the laser powder feeding rate Mp or the powder coating thickness, change the different laser power P to conduct experiments, record the temperature of the molten pool center and the diameter of the molten pool, and obtain the temperature of the molten pool center under different laser power P data and molten pool diameter data;

Wherein, recording the temperature at the center of the molten pool and the diameter of the molten pool specifically includes using a temperature recorder to record the temperature at the center of the molten pool and using a CCD high-speed camera to record the shape of the molten pool. According to needs, other conventional equipment can also be used to respectively collect and record the temperature of the center of the molten pool and the shape of the molten pool.

It should be noted that the fixed laser scanning speed V and the laser powder feeding rate Mp or the powder coating thickness refer to the fixed laser scanning speed V and the laser powder feeding rate Mp, or the fixed laser scanning speed V and the powder coating thickness. Other process parameters include laser The spot D and the laser defocus amount keep the existing parameters of the equipment unchanged during the entire processing process, the same as below. Specifically, a temperature recorder can be used to record the temperature at the center of the molten pool and the diameter of the molten pool, and a CCD camera can be used to record the shape of the molten pool to obtain the above-mentioned fixed laser scanning speed V and laser powder feeding rate Mp, and the molten pool under different laser powers P Center temperature data and melt pool diameter data, or obtain the melt pool center temperature data and melt pool diameter data under different laser power P under the above-mentioned fixed laser scanning speed V and powder coating thickness. Specifically, the infrared CCD camera directly photographs the shape of the molten pool, and the connected computer is used to automatically calculate the size of the molten pool.

S03: Perform metallographic analysis on the experimental sample obtained in step S02 to obtain the shape parameter data of the molten pool of the experimental sample, and determine the appropriate laser power and the corresponding molten pool center temperature data and molten pool diameter data to obtain the laser scanning speed The relationship between V and the laser powder feeding rate Mp or the center temperature of the molten pool under the thickness of the powder coating, the diameter of the molten pool and the laser power, and the effective relationship T1 is determined according to the criterion;

It should be noted that the effective relational formula T1 is determined according to the criterion, and its selection principle is shown in Figure 3. During metallographic analysis, the corresponding width W of the molten layer is measured using the scale attached to the metallographic microscope. The height H of the melting layer and the depth b of the substrate being melted are brought into the dilution rate formula and the cladding layer shape coefficient formula for calculation. The dilution rate is required to meet: 0<d≤8, and the cladding layer coefficient satisfies: 5<AR, and Both requirements are met simultaneously. At the same time, when conducting experiments, those that cannot form molten pools, melt channels, discontinuous forming, and other naked eyes that do not meet the forming requirements will not be calculated, and the corresponding processing parameters will be directly eliminated. The effective relationship T1 is determined by eliminating the molten pool center temperature, molten pool diameter and laser power data that do not meet the forming requirements and do not meet the requirements of the dilution rate and cladding layer shape coefficient. The criteria for the subsequent effective relational expression T2, effective relational expression T3 and effective relational expression T4 are the same as the above principles.

S04: Fix the laser power P and the laser powder feeding rate Mp or the powder coating thickness, change the laser scanning speed V to conduct experiments, record the temperature of the molten pool center and the diameter of the molten pool, and obtain the temperature data of the molten pool center at different laser scanning speeds V and molten pool diameter data;

S05: Perform metallographic analysis on the experimental sample obtained in step S04 to obtain the shape parameter data of the molten pool of the experimental sample, and determine the suitable laser scanning speed V and the corresponding molten pool center temperature data and molten pool diameter data to obtain the laser The relationship between the power P and the laser powder feeding rate Mp or the laser scanning speed V when the powder thickness is constant, the temperature of the center of the molten pool and the diameter of the molten pool is based on the criterion to determine the effective relationship T2;

In the above step S04, when the laser scanning speed V and the laser powder feeding rate Mp are fixed in step S02, the laser power P and the laser powder feeding rate Mp are correspondingly fixed; when the laser scanning speed V and the powder coating thickness are fixed in step S02, then Corresponding fixed laser power P and powder coating thickness.

S06: Fix the laser power P and laser scanning speed V, change the powder feeding rate Mp or the powder coating thickness to conduct experiments, record the temperature at the center of the molten pool and the diameter of the molten pool, and obtain the molten pool under different powder feeding rates Mp or powder coating thickness Central temperature data and molten pool diameter data;

S07: Conduct metallographic analysis on the experimental sample obtained in step S06, obtain the shape parameter data of the molten pool of the experimental sample, and determine the appropriate powder feeding rate Mp or powder coating thickness and the corresponding molten pool center temperature data and molten pool diameter Data, the relationship between the laser powder feeding rate Mp or the powder coating thickness and the center temperature of the molten pool and the diameter of the molten pool is obtained when the laser power P and the laser scanning speed are constant, and the effective relationship T3 is determined according to the criterion;

It should be noted that the determination of the effective relational expression T1 in the above-mentioned steps S02 and S03, the determination of the effective relational expression T2 in the steps S04 and S05, and the determination of the effective relational expression T3 in the steps S06 and S07 are preferably determined in sequence according to the above-mentioned sequence. Relational expression T1, effective relational expression T2 and effective relational expression T3 can also adjust the determination order of each effective relational expression according to needs, that is, the whole of steps S02, S03, the whole of steps S04, S05 and the whole of steps S06, S07, The order of the three is not limited.

S08: According to the effective relationship T1, the effective relationship T2 and the effective relationship T3, determine and store the effective relationship T4 between the laser scanning power P and the molten pool center temperature under different laser scanning speeds, different powder feeding rates or powder coating thicknesses.

The determined effective relationship T4 between the laser scanning power P, the center temperature of the molten pool and the diameter of the molten pool under different laser scanning speeds, different powder feeding rates or powder coating thicknesses is stored and stored, and then the relationship data is subsequently used to process the actual workpiece.

Specifically, the laser processing head, laser power meter, CCD high-speed camera and multi-wavelength pyrometer are coaxially installed, and the protective gas pipeline is aligned with the center of the laser melting pool.

On the basis of the above-mentioned embodiments, the laser power P is adjusted, specifically:

The laser power P is adjusted by a laser power detector. That is to say, the laser power detector has feedback and detection functions, and is used for power measurement and feedback, and automatic adjustment of power. Preferably, the laser power detector can perform on-line measurement of laser light with a wavelength in the range of 800-1200 nm.

Preferably, the above-mentioned pyrometer is used to measure the central temperature of the laser melting pool, and the temperature measurement range is 800-2700°C. The pyrometer is an automatic and non-contact measuring device, and the pyrometer is directly connected to the optical fiber.

The above-mentioned infrared camera collects the temperature of the entire laser action area. The basic requirement of the infrared camera configuration is that the shooting speed is more than 40 images per second, and the camera can stably shoot in the temperature range of 600-2900°C. The camera is mounted coaxially with the laser beam. The infrared CCD camera directly captures the shape of the molten pool, and the connected computer automatically calculates the size of the molten pool.

In the above effective relationship T4, the temperature of the center of the molten pool and the diameter of the molten pool are directly controlled as variables. When the scanning speed and powder feeding rate (or when the powder coating thickness is constant), the temperature change is correspondingly determined by the laser power. Corresponding changes, so as to achieve online monitoring. The effective relationship T1, the effective relationship T2, the effective relationship T3 and the effective relationship T4 can be determined by the experimental results, and the main units are: P is the actual laser power, the unit is W, V is the actual laser scanning speed, the unit is mm·S ^-1 , Mp is the powder feeding rate in g.min ^-1 (during powder feeding), and the unit of powder spreading thickness is mm (during powder spreading).

The technical solutions of the present invention will be clearly and completely described below through specific embodiments. Apparently, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

Embodiment one:

An online monitoring method for laser additive manufacturing containing a ceramic reinforced phase coating, comprising the following steps:

S1: Install and set up each device; specifically, multi-wavelength pyrometer, CCD high-speed infrared camera, laser processing head, laser power detector (with feedback and detection functions, used for power measurement and feedback, and automatic adjustment of power), CCD high-speed camera and protective gas pipeline are installed and set up according to the requirements;

S2: The test sample is placed at the designated position; here, Fe-based stainless steel powder is selected, and additive manufacturing is carried out on the Fe-based stainless steel 316L substrate. The strengthening phase is WC, and the proportion of WC in the strengthening phase is 2.5%, 5% and 10%. The method of feeding powder is adopted. The WC and Fe-based powders are uniformly mixed using a ball mill.

S3: Fix laser scanning speed (V=10mm.s ^-1 ) and laser powder feeding rate (Mp=10g/min, laser spot D=4mm and laser defocus amount F=0, keep the equipment in the whole processing process The parameters remain the same, the same as below), and different laser powers (P=2000～500W) are used for experiments. The temperature recorder is used to record the temperature of the center of the molten pool and the shape of the molten pool is recorded by a CCD camera, and the molten pool under different laser powers is obtained. Pool center temperature data and molten pool diameter data;

S4: Conduct metallographic analysis on the experimental sample in S3 to obtain the shape parameter data of the molten pool of the sample, and then determine the appropriate laser power and the corresponding data of the center temperature of the molten pool and the diameter of the molten pool, and obtain the scanning speed and feed rate. The relationship between molten pool temperature and molten pool diameter and laser power under the powder rate, the effective relationship T1 is determined according to the criterion. The molten pool diameter, molten pool temperature and parameter data under the parameters are all in one-to-one correspondence.

S5: Fix the laser power (P=3000W) and powder feeding rate (Mp=103g/min), change the laser scanning speed (V=6～20mm.s ^-1 ), and conduct a series of experiments to obtain the results of different scanning speeds. The data of molten pool center temperature and molten pool diameter under the condition;

S6: Conduct metallographic analysis on the experimental sample obtained in S5 to obtain the shape coefficient of the sample, thereby determine the relationship between the scanning speed, the diameter of the molten pool and the temperature of the molten pool when the power and powder feeding rate are constant, and determine the effective Relation T2, the effective molten pool diameter at this time is: 3.6~4.21mm, and the scanning speed is: 7~15mm.s ^-1 ; the molten pool diameter, molten pool temperature and parameter data under each specific parameter are the same One to one correspondence.

S7: Fix the laser power (P=3000W) and laser scanning speed (10mm.s ^-1 ), change the powder feeding rate (here choose the powder feeding mode, powder feeding rate Mp=10-40g.min ^-1 ), get A series of data of powder feeding rate and molten pool center temperature and molten pool diameter;

S8: Carry out metallographic analysis on the sample in S7, and determine the effective relationship T3 according to the criterion, and the obtained effective data is: the diameter of the molten pool is 3.7-4.2mm, and the powder feeding rate is Mp=10-40g.min ^-1 ;

S9: Arrange the effective relational expressions T1, T2 and T3 together to determine the relational expression T4 between the change of laser power P and the temperature of the center of the molten pool and the diameter of the molten pool. The center temperature is 1330-1400°C. Each combination of laser power P and scanning speed has a certain powder feeding rate corresponding to it. Similarly, each combination of laser power P and powder feeding rate has a certain corresponding to the scanning speed.

S10: Use relational formula T4 to perform on-line monitoring of laser additive manufacturing on the actual workpiece;

S11: If temperature fluctuations are found during the monitoring process, since the laser power is selected as the change control quantity during the online monitoring process, when using the laser power, scanning speed and powder feeding rate stored in the system for laser additive manufacturing, the measured If the temperature of the center of the molten pool fluctuates, the laser power is adjusted to the corresponding laser power in the system for processing to ensure that the laser power and temperature are corresponding. When the measured molten pool diameter fluctuates, the laser power is adjusted to the corresponding laser power in the system for processing to ensure that the laser power corresponds to the molten pool diameter. The system automatically adjusts the laser power according to the relation T4. This completes the entire laser on-line monitoring process. Specifically, when both the temperature of the molten pool and the diameter of the molten pool fluctuate and do not conform to the relationship T4, the system will alarm, and at this time it is considered that the interference determines how to deal with it.

Embodiment two:

In this embodiment, the powder used is Ni-based alloy In625, the experimental substrate is 316 stainless steel, and the strengthening phase is TiC powder. The content of TiC in the period is 10%, 20%, 30%, and the difference with embodiment one is

In the acquisition stage of T1 parameters, the laser scanning speed (V=10mm.s ^-1 ) and laser powder feeding rate (Mp=10g/min, laser spot D=4mm and laser defocusing amount F=0 are fixed, during the whole processing process Keep the existing parameters of the equipment unchanged, the same as below), change different laser powers (P=2000～500W) to conduct experiments, use a temperature recorder to record the temperature in the center of the molten pool and use a CCD camera to record the diameter of the molten pool to obtain different laser The molten pool temperature center data and molten pool diameter data under the power; determine the effective relationship T1 according to the criterion, the effective range of the molten pool diameter at this time is 3.75 ~ 4.15mm, the laser power is 3000 ~ 5000W, each specific parameter The molten pool diameter, molten pool temperature and parameter data are all in one-to-one correspondence;

To obtain the parameters in the T2 stage, fix the laser power (P=3000W) and powder feeding rate (Mp=10g/min), change the laser scanning speed (V=6～20mm.s ^-1 ), conduct a series of experiments, and thus get The data of the molten pool center temperature and molten pool diameter under the condition of different scanning speeds; the metallographic analysis of the obtained experimental samples was carried out to obtain the shape coefficient of the sample, and the dilution rate and shape coefficient of the cladding layer were calculated, so as to determine the laser power and When the powder feeding rate is constant, the relationship between the scanning speed, the diameter of the molten pool and the temperature of the molten pool center is determined according to the criterion. ~14.5mm.s ^-1 ; The molten pool diameter, molten pool temperature and parameter data under each specific parameter combination are in one-to-one correspondence;

Acquisition of parameters in the T3 stage: fix the laser power (P=3000W) and laser scanning speed (10mm.s ^-1 ), change the powder feeding rate (powder feeding rate Mp=10-40g.min ^-1 ), and obtain a series of powder feeding Data on rate versus pool center temperature and pool diameter. Carry out metallographic analysis to the sample obtained, and determine the effective relational formula T3 according to the criterion, and the effective data obtained are: the molten pool diameter is: 3.74-4.16mm, and the powder feeding rate Mp=10.3-39.4g.min ⁻¹ ;

Arrange the relationship expressions T1, T2 and T3 together to determine the relationship expression T4 between the change of laser power and the temperature of the center of the molten pool and the diameter of the molten pool. : 3000-5000W, the center temperature of the laser molten pool is 1390-1572°C, each combination of laser power and scanning speed has a certain powder feeding rate corresponding to it, similarly, each laser power and powder feeding rate combination, there is a certain scanning speed corresponding to it.

Embodiment three:

The difference between this embodiment and the first embodiment is that

The powder feeding method is used for laser additive manufacturing. The powder used is Co-based alloy Stellite6, the experimental substrate is 316 stainless steel, and the strengthening phase is TiN powder.

In the acquisition stage of T1 parameters, the laser scanning speed (V=10mm.s ^-1 ) and laser powder feeding rate (Mp=10g/min, laser spot D=4mm and laser defocusing amount F=0 are fixed, during the whole processing process Keep the existing parameters of the equipment unchanged, the same as below), and experiment with different laser powers (P=2000~500W), use a temperature recorder to record the temperature of the center of the molten pool and use a CCD camera to record the shape of the molten pool to obtain different laser The temperature center data of the molten pool and the data of the molten pool diameter under the power; determine the effective relationship T1 according to the criterion, the effective range of the molten pool diameter at this time is 3.81 ~ 4.12mm, the laser power is 3000 ~ 4000W, each specific parameter The molten pool diameter, molten pool temperature and parameter data below are in one-to-one correspondence.

To obtain the parameters in the T2 stage, fix the laser power (P=3000W) and powder feeding rate (Mp=10g/min), change the laser scanning speed (V=6～20mm.s ^-1 ), conduct a series of experiments, and thus get The data of molten pool temperature and molten pool shape under the condition of different scanning speeds; the metallographic analysis of the obtained experimental samples is carried out to obtain the shape coefficient of the sample, and the dilution rate and shape coefficient of the cladding layer are calculated, so as to determine the power and powder feeding The relationship between the scanning speed and the diameter of the molten pool when the rate is constant, the effective relationship T2 is determined according to the criterion, the effective molten pool diameter at this time is: 3.64 ~ 4.16mm, and the scanning speed is: 7.4 ~ 14.5mm.s ^-1 ; The molten pool diameter, molten pool temperature and parameter data under each specific parameter combination are in one-to-one correspondence

Acquisition of parameters in the T3 stage: fix the laser power (P=3000W) and laser scanning speed (10mm.s ^-1 ), change the powder feeding rate (powder feeding rate Mp=10-40g.min ^-1 ), and obtain a series of powder feeding The data of rate and molten pool temperature; metallographic analysis is carried out on the obtained sample, and the effective relational formula T3 is determined according to the criterion. The obtained effective data is: molten pool diameter: 3.75-4.12mm, powder feeding rate Mp=11.4 -39.4g.min ^-1 ;

Arrange the relationship expressions T1, T2 and T3 together to determine the relationship expression T4 between the power change and the temperature of the molten pool. At this time, the variation range of the molten pool diameter is 3.7-4.12mm, and the variation range of the laser power is: 3000-5000W. The temperature of the molten pool is 1520-1691°C. Each combination of laser power and scanning speed has a certain powder feeding rate corresponding to it. Similarly, each combination of laser power and powder feeding rate has a certain The scanning speed corresponds to it.

In summary, the present invention provides an online monitoring method for laser additive manufacturing. By optimizing the process parameters and analyzing and calculating the data curves measured with the test samples, the most suitable laser processing parameters are obtained, and the parameters are used as the The actual measured data is calculated and analyzed to compare whether the effective molten pool diameter range meets the standard so as to achieve the purpose of on-line monitoring and control. It has the advantages of good controllability and high processing efficiency, and can be better used in ships, rail transit, machinery manufacturing and other fields that require cladding to prepare ceramic strengthening phases, better adapt to flexible manufacturing environments, and has a more profound practical significance.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (7)

1. An online monitoring method for laser additive manufacturing, characterized in that, comprising: Real-time collection of molten pool center temperature and molten pool diameter; When the collected melt pool center temperature or melt pool diameter does not conform to the relationship between the pre-stored laser power P and the melt pool center temperature and melt pool diameter, the laser power P is adjusted according to the relationship so that the collected The temperature at the center of the molten pool and the diameter of the molten pool are all consistent with the relationship between the pre-stored laser power P, the central temperature of the molten pool, and the diameter of the molten pool. 2. The online monitoring method of laser additive manufacturing according to claim 1, wherein the relationship between the pre-stored laser power P and the center temperature of the molten pool and the diameter of the molten pool specifically includes: By fixing any two of the laser power P, laser scanning speed V and powder feeding rate Mp respectively, and changing the other one to conduct experiments and record the temperature of the molten pool center and the diameter of the molten pool, and obtain it by metallographic analysis and calculation The dilution rate and the shape factor of the cladding layer determine and store the relationship between the laser power P and the temperature of the center of the molten pool and the diameter of the molten pool; Or by fixing any two of the laser power P, laser scanning speed V and powder coating thickness respectively, change the other one to conduct experiments and record the temperature and diameter of the molten pool center, and obtain it by metallographic analysis and calculation The dilution rate and the shape factor of the cladding layer are used to determine and store the relationship between the laser power P, the temperature of the center of the molten pool and the diameter of the molten pool. 3. The online monitoring method of laser additive manufacturing according to claim 1, characterized in that, before the real-time collection of the central temperature of the molten pool, further comprising the steps of: S01: Place the test sample at the designated location; S02: Fix the laser scanning speed V and the laser powder feeding rate Mp or the powder coating thickness, change different laser power P to conduct experiments, record the temperature and diameter of the molten pool center, and obtain the temperature data of the molten pool center under different laser power P and molten pool diameter data; And carry out metallographic analysis to the obtained experimental sample, obtain the molten pool shape parameter data of the experimental sample, and determine the suitable described laser power P and corresponding molten pool center temperature data and molten pool diameter data, obtain the described The laser scanning speed V and the laser powder feeding rate Mp or the relationship between the center temperature of the molten pool under the powder coating thickness and the diameter of the molten pool and the laser power are determined according to the effective relationship T1; S03: Fix the laser power P and the laser powder feeding rate Mp or powder coating thickness, change the laser scanning speed V to conduct experiments, record the temperature of the molten pool center and the diameter of the molten pool, and obtain the temperature data of the molten pool center at different laser scanning speeds V and molten pool diameter data; And carry out metallographic analysis to the obtained experimental sample, obtain the molten pool shape parameter data of described experimental sample, and determine suitable described laser scanning velocity V and corresponding molten pool central temperature data and molten pool diameter data, obtain the obtained The relationship between the laser power P and the laser powder feeding rate Mp or the laser scanning speed V when the powder thickness is constant, the temperature of the molten pool center and the diameter of the molten pool is determined according to the criterion. Effective relationship T2; S04: Fix the laser power P and laser scanning speed V, change the powder feeding rate Mp or powder coating thickness to conduct experiments, record the temperature of the molten pool center and the diameter of the molten pool, and obtain the molten pool under different powder feeding rates Mp or powder coating thickness Central temperature data and molten pool diameter data; And carry out metallographic analysis to the obtained experimental sample, obtain the molten pool shape parameter data of the experimental sample, and determine the suitable powder feeding rate Mp or powder coating thickness and corresponding molten pool center temperature data and molten pool diameter data, obtain the relationship between the laser power P and the laser scanning speed when the laser powder feeding rate Mp or the powder coating thickness and the center temperature of the molten pool and the diameter of the molten pool are determined, and the effective relationship T3 is determined according to the criterion; S05: According to the effective relational expression T1, the effective relational expression T2 and the effective relational expression T3, determine the laser scanning power P and the molten pool center temperature and melting The valid relation T4 for the pool diameter is stored. 4. The online monitoring method of laser additive manufacturing according to claim 3, wherein the recording of the temperature at the center of the molten pool and the diameter of the molten pool specifically includes using a temperature recorder to record the temperature at the center of the molten pool and using infrared The CCD camera records the diameter of the molten pool. 5. The online monitoring method of laser additive manufacturing according to claim 3, characterized in that, before the step S1, further comprising: Install the multi-wavelength pyrometer, CCD high-speed infrared camera, laser processing head, laser power detector, CCD high-speed camera and protective gas pipeline according to the requirements. 6. The online monitoring method of laser additive manufacturing according to claim 5, wherein the laser processing head, the laser power meter, the CCD high-speed camera and the multi-wavelength pyrometer are coaxially installed, and the The protective gas pipeline is aligned with the center of the laser melting pool. 7. The online monitoring method for laser additive manufacturing according to any one of claims 1-6, wherein the adjustment of the laser power P is specifically: The laser power P is adjusted by a laser power detector.