CN111673084A

CN111673084A - Temperature control method, electronic device, and computer-readable storage medium

Info

Publication number: CN111673084A
Application number: CN202010542636.4A
Authority: CN
Inventors: 俞红祥; 张�杰; 庞伟; 黄少俯
Original assignee: Hangzhou Dedi Intelligent Technology Co ltd
Current assignee: Hangzhou Dedi Intelligent Technology Co ltd
Priority date: 2020-06-15
Filing date: 2020-06-15
Publication date: 2020-09-18
Anticipated expiration: 2040-06-15
Also published as: CN111673084B

Abstract

The present application relates to a temperature control method, an electronic device, and a computer-readable storage medium. The temperature control method comprises the following steps: detecting a temperature distribution of a surface of a laminated molding section of a three-dimensional laminated molding device; extracting a first temperature distribution of a non-fusion bonding area of the surface of the laminated modeling part from the temperature distribution, and controlling the heating power of a preheating unit of the three-dimensional laminated modeling device according to the first temperature distribution; a second temperature distribution of the fusion bonding region of the surface of the laminated molded part is extracted from the temperature distribution, and the laser emission power or the laser scanning speed of a laser scanning unit of the three-dimensional laminated molding device is controlled in accordance with the second temperature distribution. Through the application, the problem of unstable control of the preheating temperature and the melting combination temperature of the three-dimensional stacking and modeling device is solved, and the control stability of the preheating temperature and the melting combination temperature of the three-dimensional stacking and modeling device is improved.

Description

Temperature control method, electronic device, and computer-readable storage medium

Technical Field

The present application relates to the field of three-dimensional printing, and more particularly, to a temperature control system, a three-dimensional stack molding apparatus, a temperature control method, an electronic apparatus, and a computer-readable storage medium.

Background

In recent years, additive manufacturing/3D printing technology, which is centered on a layer-by-layer accumulation manner, has gradually received attention from the manufacturing field. Due to the advantages of high forming freedom, no need of a mold, one-time direct forming of a digital-analog and the like, the 3D printing technology is regarded as a necessary supplement of the traditional manufacturing technology and also bears the expectation of the future technology of the manufacturing industry. In a plurality of 3D printing devices, based on a Selective Laser Melting (SLM) and Selective Laser Sintering (SLS) three-dimensional laminating molding device, a powder thin layer specific area on a powder bed is selectively irradiated by a Laser beam and is melted and combined into a high-precision sheet-shaped whole.

Existing SLM/SLS based three-dimensional stack molding machines commonly employ a laser beam as a means of directionally applying energy to powder layers in selected areas of a stack molding section (e.g., a powder bed). In order to improve the efficiency of three-dimensional forming, the laser beam needs to rapidly scan the fusion bonding area covering each powder layer at a high linear speed, which greatly limits the total amount of energy and action time applied to the powder layer by the laser beam, and the high-power laser also greatly increases the equipment cost of the SLM/SLS-based three-dimensional laminated molding device. Reducing the energy requirements of the laser beam for fusion bonding of powder layers has become one of the main directions for improving the performance of the equipment of the three-dimensional laminated molding apparatus. The powder layer on the powder bed is wholly preheated to be slightly lower than the critical temperature of fusion bonding, so that the laser beam only needs to apply a small amount of energy to the powder in the selected area to realize the fusion bonding of the powder in the irradiated area, and the aim of reducing the power requirement of a laser at the same scanning speed or realizing higher scanning speed at the same laser power is fulfilled.

In order to avoid the problems of excessive preheating of the powder layer and generation of metamorphic agglomeration, the SLM/SLS-based three-dimensional laminated modeling device must perform measurement and closed-loop control on the preheating temperature of the powder layer, i.e., maintain the preheating temperature stable by dynamically adjusting the electric heating power. In order to avoid the continuous accumulation of energy in the continuous laser scanning, which may cause overheating of the fusion bonding region, the SLM/SLS-based three-dimensional stack molding apparatus further requires the measurement and closed-loop control of the fusion bonding temperature of the powder, i.e. the fusion bonding temperature is maintained stable by dynamically adjusting the laser beam power. However, in the process of the three-dimensional laminating modeling device, the preheating function and the laser beam irradiation heating function act on the powder layer at the same time, the powder layer temperature generated by the combined action of the two heat sources is directly fed back to the two closed-loop control circuits, the powder layer temperature fluctuation caused by the laser beam scanning can inject high-frequency disturbance into the preheating control circuit, the dynamic response of the preheating control circuit to the high-frequency disturbance of the laser beam can also generate low-frequency oscillation in the laser power control circuit, and further the instability of the preheating temperature and the melting combined temperature control is induced, the printing quality is directly influenced, and even the serious consequence of printing failure is caused.

Disclosure of Invention

Embodiments of the present application provide a temperature control method, an electronic apparatus, and a computer-readable storage medium to solve at least the problem of unstable control of the preheating temperature and the melt bonding temperature of a three-dimensional stack molding apparatus in the related art.

In a first aspect, an embodiment of the present application provides a temperature control method, including:

detecting a temperature distribution of a surface of a laminated molding section of a three-dimensional laminated molding device;

extracting a first temperature distribution within a first preset range from the temperature distributions, and controlling the heating power of a preheating unit of the three-dimensional laminated modeling device according to the first temperature distribution, wherein the first preset range is determined based on the preheating temperature;

and extracting a second temperature distribution within a second preset range from the temperature distribution, and controlling the laser emission power or the laser scanning speed of a laser scanning unit of the three-dimensional laminated modeling apparatus according to the second temperature distribution, wherein the second preset range is determined based on the melting and bonding temperature of the modeling material.

In some of these embodiments, controlling the heating power of the preheating unit of the three-dimensional stack molding apparatus according to the first temperature distribution includes:

calculating a weighted average of the first temperature distribution;

and controlling the heating power of a preheating unit of the three-dimensional laminated modeling device by using the weighted average value of the first temperature distribution as negative feedback.

In some of these embodiments, controlling the laser emission power or the laser scanning speed of the laser scanning unit of the three-dimensional stack molding apparatus according to the second temperature distribution includes:

calculating a weighted average of the second temperature distribution;

and controlling the laser emission power or the laser scanning speed of a laser scanning unit of the three-dimensional laminated modeling device by using the weighted average value of the second temperature distribution as negative feedback.

In a second aspect, an embodiment of the present application provides a temperature control method, including:

extracting a first temperature distribution of a non-fusion bonding region of the surface of the laminated modeling portion from the temperature distribution, and controlling the heating power of a preheating unit of the three-dimensional laminated modeling device according to the first temperature distribution;

and extracting a second temperature distribution of the fusion bonding area of the surface of the laminated modeling part from the temperature distribution, and controlling the laser emission power or the laser scanning speed of a laser scanning unit of the three-dimensional laminated modeling device according to the second temperature distribution.

calculating a weighted average of the first temperature distribution;

calculating a weighted average of the second temperature distribution;

In some of these embodiments, extracting a first temperature profile of a non-fusion bonded region of the laminate molding surface from the temperature profile comprises:

acquiring fusion bonding area data of a current three-dimensional laminating modeling task;

determining the fusion bonding area according to the fusion bonding area data, and taking the other area of the surface of the three-dimensional laminated modeling part except the fusion bonding area as the non-fusion bonding area;

extracting the first temperature profile of the non-fusion bonded region from the temperature profile.

In a third aspect, an embodiment of the present application provides a temperature control apparatus, including:

a temperature detection module for detecting the temperature distribution of the surface of the laminated modeling part of the three-dimensional laminated modeling device;

the first temperature extraction module is used for extracting a first temperature distribution in a first preset range from the temperature distribution;

a first control module for controlling a heating power of a preheating unit of the three-dimensional stack molding apparatus according to the first temperature distribution, wherein the first preset range is determined based on a preheating temperature;

the second temperature extraction module is used for extracting a second temperature distribution in a second preset range from the temperature distribution;

and the second control module is used for controlling the laser emission power or the laser scanning speed of a laser scanning unit of the three-dimensional laminated modeling device according to the second temperature distribution, wherein the second preset range is determined based on the melting and combining temperature of the modeling material.

In a fourth aspect, embodiments of the present application provide an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, where in some embodiments, the processor implements the temperature control method according to the first aspect, and/or the temperature control method according to the second aspect when executing the computer program.

In a fifth aspect, embodiments of the present application provide a computer-readable storage medium on which a computer program is stored, where in some embodiments the program is executed by a processor to implement the temperature control method according to the first aspect and/or the temperature control method according to the second aspect.

Compared with the related art, the temperature control method, the electronic device and the computer readable storage medium provided by the embodiment of the application solve the problem of instability in control of the preheating temperature and the melting bonding temperature of the three-dimensional laminating molding device in the related art, and improve the control stability of the preheating temperature and the melting bonding temperature of the three-dimensional laminating molding device.

The details of one or more embodiments of the application are set forth in the accompanying drawings and the description below to provide a more thorough understanding of the application.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:

FIG. 1 is a flow chart of a method of temperature control according to an embodiment of the present application;

FIG. 2 is a circuit topology diagram of a temperature control system according to an embodiment of the present application;

FIG. 3 is a flow chart of another method of temperature control according to an embodiment of the present application;

fig. 4 is a schematic perspective view of a three-dimensional stack molding apparatus according to a preferred embodiment of the present application;

fig. 5 is a schematic sectional structure view of a three-dimensional stack molding apparatus according to a preferred embodiment of the present application;

fig. 6 is an electrical configuration diagram of a three-dimensional laminated molding apparatus according to a preferred embodiment of the present application;

fig. 7 is a schematic view showing a change in the operating state of the three-dimensional stack molding apparatus according to the preferred embodiment of the present application;

FIG. 8 is a schematic flow chart of the extraction temperature distribution in step S705 according to the preferred embodiment of the present application;

FIG. 9 is a control schematic diagram of the graphic controller 100 in step S705 according to the preferred embodiment of the present application;

FIG. 10 is a block diagram of a temperature control device according to an embodiment of the present application;

fig. 11 is a hardware configuration diagram of an electronic device according to an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments provided in the present application without any inventive step are within the scope of protection of the present application.

It is obvious that the drawings in the following description are only examples or embodiments of the present application, and that it is also possible for a person skilled in the art to apply the present application to other similar contexts on the basis of these drawings without inventive effort. Moreover, it should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another.

Reference in the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the specification. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of ordinary skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments without conflict.

Unless defined otherwise, technical or scientific terms referred to herein shall have the ordinary meaning as understood by those of ordinary skill in the art to which this application belongs. Reference to "a," "an," "the," and similar words throughout this application are not to be construed as limiting in number, and may refer to the singular or the plural. The present application is directed to the use of the terms "including," "comprising," "having," and any variations thereof, which are intended to cover non-exclusive inclusions; for example, a process, method, system, article, or apparatus that comprises a list of steps or modules (elements) is not limited to the listed steps or elements, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus. Reference to "connected," "coupled," and the like in this application is not intended to be limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The term "plurality" as referred to herein means two or more.

The present invention provides a temperature control method for solving the problems that, when a three-dimensional laminated modeling apparatus in the related art performs closed-loop control of a preheating temperature and a fusion bonding temperature, temperature distribution on a surface of a laminated modeling portion of the three-dimensional laminated modeling apparatus is directly subjected to closed-loop control, so that high-frequency disturbance is injected into a preheating control circuit due to temperature fluctuation of a powder layer caused by laser beam scanning, and dynamic response of the preheating control circuit to the high-frequency disturbance of the laser beam also generates low-frequency oscillation in a laser power control circuit, so as to induce instability of control of the preheating temperature and the fusion bonding temperature, directly affect printing quality, and even cause serious consequences of printing failure.

Fig. 1 is a flowchart of a temperature control method according to an embodiment of the present application, and as shown in fig. 1, the flowchart includes the following steps:

in step S101, the temperature distribution on the surface of the laminated molding section of the three-dimensional laminated molding apparatus is detected.

The three-dimensional laminated modeling device mainly uses a 3D printer based on SLM/SLS, and the forming principle thereof is that a thin layer of powder (metal powder or mixed powder of metal powder and binder) is generally laid on a liftable laminated modeling portion (for example, a modeling platform such as a powder bed), and then the powder layer is irradiated by laser scanning to melt and solidify the powder in a certain area; and after the primary laminating modeling is finished, the laminating modeling part descends by one layer, then powder is continuously spread on the surface of the laminating modeling part, and the processes are repeated until all printing is finished. In order to increase the 3D printing speed and reduce the laser power requirement, it is generally necessary to preheat the surface of the laminated molding portion.

In this embodiment, in order to be able to detect the temperature distribution on the surface of the laminated molding section of the three-dimensional laminated molding apparatus, a noncontact temperature sensor is preferably used. Among them, since it is inefficient to detect the surface temperature of the laminated shape portion with a single noncontact temperature sensor, it is possible to obtain the temperature distribution of the surface of the laminated shape portion by scanning the surface of the laminated shape portion with the noncontact temperature sensors arranged in a line. Further, in order to simplify the structure and improve the temperature measurement efficiency, it is preferable to simultaneously detect the temperature distribution of the entire surface of the laminated molded part using a noncontact temperature sensor array.

Step S102, extracting a first temperature distribution in a first preset range from the temperature distributions, and controlling the heating power of a preheating unit of the three-dimensional laminating molding device according to the first temperature distribution, wherein the first preset range is determined based on the preheating temperature.

Step S103, extracting a second temperature distribution within a second preset range from the temperature distributions, and controlling the laser emission power or the laser scanning speed of the laser scanning unit of the three-dimensional laminated modeling apparatus according to the second temperature distribution, wherein the second preset range is determined based on the melt bonding temperature of the modeling material.

In the present embodiment, in the primary laminate molding, the region of the surface of the laminate molding portion which is being scanned or has been scanned and irradiated by the laser scanning unit and heated and melted is referred to as a fusion-bonded region, and the region which is not scanned by the laser scanning unit is referred to as a non-fusion-bonded region. To avoid melting or sheeting of the powder layers of the non-fusion bonded areas, the non-fusion bonded areas will be preheated to a temperature value below the fusion bonding critical temperature; and the temperature value in the fusion bonding area, especially the area being heated by the laser scanning unit, will be higher than the fusion bonding critical temperature.

Therefore, the temperature value of the region mainly affected by the preheating unit on the surface of the laminated molding section will be within a first preset range, which is determined based on the preheating temperature. For example, the first preset range is a temperature range not higher than the preheating temperature. Then, if the first temperature distribution within the first preset range is extracted from the temperature distribution obtained in step S101, the first temperature distribution is mainly affected by the heating power of the preheating unit, and therefore, controlling the heating power of the preheating unit of the three-dimensional stack molding apparatus according to the first temperature distribution can avoid that the temperature fluctuation of the powder layer caused by the laser beam scanning injects high-frequency disturbance into the preheating control loop, thereby solving the problem of unstable control of the preheating temperature and the fusion bonding temperature of the three-dimensional stack molding apparatus in the related art.

The temperature value of the region on the surface of the laminated molding part, which is simultaneously affected by the preheating unit and the laser scanning unit, will be within a second preset range, which is determined based on the melt-bonding temperature of the molding material. Since the melt-bonding temperature of the modeling material is higher than the preheating temperature, the first predetermined range and the second predetermined range are two temperature ranges that do not overlap with each other. A second temperature distribution within a second preset range is extracted from the temperature stabilization step obtained in step S101, and the excitation radiation power or the laser scanning speed of the laser scanning unit of the three-dimensional stack molding apparatus is controlled according to the second temperature distribution, thereby realizing control of the thermal fusion bonding temperature.

In this embodiment, the temperature distributions of different regions are extracted from the temperature distribution, and the preheating temperature control and the thermal fusion bonding temperature control are respectively performed according to the temperature distributions of the different regions, so that the large thermal inertia and low-speed radiation preheating are realized, the thermal energy decoupling control with the small thermal inertia and high-speed laser thermal fusion is realized, and the control stability of the preheating temperature and the fusion bonding temperature of the three-dimensional laminated modeling device is further improved.

The temperature control in the present embodiment preferably employs negative feedback closed-loop control by which the temperature is reduced when the temperature is higher than the set value and increased when the temperature is lower than the set value, thereby controlling the temperature in the vicinity of the set value.

In order to improve the control precision and avoid measurement errors, the average value of the temperature distribution is used as negative feedback control quantity to carry out temperature control, and a good effect can be achieved. Meanwhile, it is considered that, in the obtained first temperature distribution and the second temperature distribution, the temperature value of the region at the boundary of the two temperature distributions is inevitably affected by the laser scanning unit and is higher than the other regions other than the fusion bonding region; the temperature of the region in the fusion bonding region, which has been irradiated by the laser scanning unit and has passed a certain time, may be higher than the preheating temperature but lower than the fusion bonding temperature threshold value to be solidified; due to these factors, the average temperature value obtained by directly arithmetically averaging the temperature distributions may be higher or lower than the true preheating temperature or the melt-bonding temperature. In order to reduce the influence of the temperature values of the areas at the boundaries of the two temperature distributions, a weighted average method can be adopted, and the weight of the temperature values of the areas at the boundaries of the two temperature distributions and the areas which are fused, combined and solidified and formed is reduced or even set to be zero, so that the temperature control precision is improved.

For example, when the heating power of the preheating unit of the three-dimensional stack molding apparatus is controlled based on the first temperature distribution, a weighted average of the first temperature distribution is calculated; the weighted average value of the first temperature distribution is used as negative feedback to control the heating power of the preheating unit of the three-dimensional laminated modeling apparatus. Or calculating a weighted average value of the second temperature distribution when controlling the laser emission power or the laser scanning speed of the laser scanning unit of the three-dimensional laminated modeling device according to the second temperature distribution; the weighted average value of the second temperature distribution is used as negative feedback to control the laser emission power or the laser scanning speed of the laser scanning unit of the three-dimensional laminated modeling apparatus.

The temperature control method can be realized by digitizing the detected temperature distribution and then by a computer program; it can also be implemented by analog circuits or digital-analog hybrid circuits. A temperature control system based on an analog circuit or a digital-analog hybrid circuit to implement the above temperature control method will be described below.

Fig. 2 is a circuit topology diagram of a temperature control system according to an embodiment of the present application, which is applied to a three-dimensional laminated molding apparatus having a laminated molding section, a preheating unit, and a laser scanning unit. As shown in fig. 2, the temperature control system includes: a temperature detection device 20, a high-pass filter 21, a low-pass filter 22, a first negative feedback closed-loop controller 23, and a second negative feedback closed-loop controller 24.

The temperature detection device 20 may be, for example, a non-contact temperature sensor array. The temperature detection device 20 is electrically connected to the high-pass filter 21 and the low-pass filter 22, and the temperature detection device 20 can detect the temperature distribution on the surface of the laminated molded portion. The quantity detected and output by the temperature detection device 20 may be either a digital quantity or an analog quantity, and depending on the digital type or the analog type of the circuit of the device connected at the rear end thereof, a D/a converter or an a/D converter may be added between the temperature detection device 20 and the device connected at the rear end.

The high pass filter 21 may be an analog high pass filter or a digital high pass filter, which functions to allow temperature values above a set point to be fed into the first negative feedback closed loop controller 23, while temperature values below the set point are blocked. The temperature value higher than the set value is equivalent to the temperature value within the second preset range.

The low pass filter 22 may be an analog low pass filter or a digital low pass filter that functions to allow temperatures below the set point to be fed into the second negative feedback closed loop controller 24 while temperature values above the set point are blocked. The temperature value lower than the set value is equivalent to the temperature value within the first preset range.

The first and second negative feedback closed

loop controllers

23 and 24 may employ a negative feedback closed loop controller known in the related art, and may be, for example, a proportional controller, a proportional-integral (PI) controller, a proportional-integral-derivative (PID) controller, or a fuzzy controller with negative feedback.

The PI controller is a linear controller, which forms a control deviation from a given value and an actual output value, and linearly combines the proportion and integral of the deviation to form a control quantity to control a controlled object. The PI controller includes proportional regulation and integral regulation. Wherein, the proportion regulation is the deviation of the proportion reaction system, and once the deviation occurs in the system, the proportion regulation immediately generates the regulation function to reduce the deviation. The proportion is large, so that the adjustment can be accelerated, and the error can be reduced, but the stability of the system is reduced and even the system is unstable due to the overlarge proportion. The integral adjustment is to eliminate the steady-state error of the system and improve the error-free degree. Because of the error, the integral adjustment is carried out until no difference exists, the integral adjustment is stopped, and the integral adjustment outputs a constant value. The PI controller can improve the steady state performance of the temperature control system.

The control quantity output by the first negative feedback closed loop controller 23 is used for controlling the heating power of the preheating unit; the control amount output by the second negative feedback closed loop controller 24 is used to control the laser emission power or the laser scanning speed of the laser scanning unit.

In some of these embodiments, the temperature control system may further comprise: a first power controller and a second power controller, wherein the first power controller is electrically connected to the first negative feedback closed-loop controller 23 for controlling the heating power of the preheating unit; the second power controller is electrically connected to the second negative feedback closed-loop controller 24 for controlling the laser emission power or the laser scanning speed of the laser scanning unit. The control quantity output by the PI controller cannot directly drive the controlled equipment generally, so a driving device can be added between the PI controller and the controlled equipment. In the present embodiment, the first power controller is used as the driving means to drive and control the heating power of the preheating unit, and the second power controller is used as the driving means to drive and control the laser emission power or the laser scanning speed of the laser scanning unit.

In some of these embodiments, the temperature control system further comprises an a/D converter, a first D/a converter, and a second D/a converter. Wherein, the high-pass filter 21 is a digital high-pass filter, and the low-pass filter 22 is a digital low-pass filter; the a/D converter is connected in series to the output end of the temperature detection device 20, and is configured to convert the analog quantity output by the temperature detection device 20 into a digital quantity; the first D/a converter is connected in series between the high pass filter 21 and the first negative feedback closed loop controller 23, and is used for converting the digital quantity output by the high pass filter 21 into an analog quantity; the second D/a converter is connected in series between the low pass filter 22 and the second negative feedback closed loop controller 24 for converting the digital quantity output from the low pass filter 22 into an analog quantity. By means of A/D conversion and D/A conversion, both the high-pass filter 21 and the low-pass filter 22 can adopt digital filters, so that the temperature distribution data can be processed by using a digital chip such as an FPGA (field programmable gate array) chip, and the integration of the temperature control system can be improved.

Fig. 3 is a flowchart of another temperature control method according to an embodiment of the present application, and as shown in fig. 3, the flowchart includes the following steps:

in step S301, the temperature distribution on the surface of the laminated molding section of the three-dimensional laminated molding apparatus is detected.

Step S302 is to extract a first temperature distribution of the non-fusion bonding region of the surface of the laminated molding section from the temperature distributions, and to control the heating power of the preheating unit of the three-dimensional laminated molding apparatus according to the first temperature distribution.

Step S303 is to extract a second temperature distribution of the fusion-bonded region on the surface of the laminated molded part from the temperature distribution, and to control the laser emission power or the laser scanning speed of the laser scanning unit of the three-dimensional laminated molding apparatus according to the second temperature distribution.

The difference from the flowchart of the temperature control method shown in fig. 2 is that, in the present embodiment, the extraction temperature distribution is based on the area division of the fusion-bonded area and the non-fusion-bonded area. The fusion bonding area may be obtained by an image recognition method, or may be obtained from a print job of a current powder layer.

For example,

in some of these embodiments, extracting a first temperature profile of a non-fusion bonded region of the laminate molding surface from the temperature profile comprises: acquiring fusion bonding area data of a current three-dimensional laminating modeling task; determining a fusion bonding area according to the fusion bonding area data, and taking the other areas except the fusion bonding area on the surface of the three-dimensional laminated modeling part as non-fusion bonding areas; a first temperature distribution of the non-fusion-bonded region is extracted from the temperature distribution. Since in each powder layer printing task, it is determined which areas are the areas to be scanned and irradiated by the laser scanning unit, and these areas are the fusion bonding areas; other regions than these include non-fusion bonded regions.

Similar to the embodiment shown in fig. 2, in this embodiment, the temperature values corresponding to the fusion bonding region and the non-fusion bonding region may also be determined by means of arithmetic average or weighted average, so as to reduce the measurement error and improve the control accuracy. For example, when the heating power of the preheating unit of the three-dimensional stack molding apparatus is controlled based on the first temperature distribution, a weighted average of the first temperature distribution is calculated; the weighted average value of the first temperature distribution is used as negative feedback to control the heating power of the preheating unit of the three-dimensional laminated modeling apparatus. Calculating a weighted average value of the second temperature distribution when controlling the laser emission power or the laser scanning speed of a laser scanning unit of the three-dimensional laminated modeling device according to the second temperature distribution; the weighted average value of the second temperature distribution is used as negative feedback to control the laser emission power or the laser scanning speed of the laser scanning unit of the three-dimensional laminated modeling apparatus.

There is also provided in an embodiment of the present application a three-dimensional stack molding apparatus including a stack molding section, a preheating unit, a laser scanning unit, and a temperature control system shown in fig. 2.

In some of these embodiments, the three-dimensional laminated molding apparatus further comprises: a box body; the cavity is opened to box inside, and range upon range of molding portion holds in the cavity. The box body is used for keeping the surface temperature of the laminated modeling part relatively stable. Preferably, the box body is a heat preservation box body.

In some embodiments, the box body is provided with an opening; the laser scanning unit is disposed outside the cabinet and is capable of scanning and heating the surface of the laminated molding portion through the opening. In order to avoid overheating of the laser scanning unit and facilitate heat dissipation of the laser scanning unit, an opening is formed in the box body, and the laser scanning unit is arranged outside the box body.

In some of the embodiments, the temperature distribution of the surface of the laminated molding section is detected by a non-contact temperature detecting device which is provided outside the case and is capable of detecting the temperature distribution of the surface of the laminated molding section through the opening.

In some of these embodiments, the case further comprises a transparent slide covering the opening.

Through the arrangement, the temperature of the laminated modeling part in the three-dimensional laminated modeling device can be maintained and is not influenced by the external temperature, and meanwhile, the laser scanning unit and the temperature detection device are arranged outside the box body, so that the service life of the electronic devices of the laser scanning unit and the temperature detection device is prevented from being shortened due to high temperature.

The embodiments of the present application are described and illustrated below by means of preferred embodiments.

In order to overcome the defects in the prior art, the preferred embodiment of the present application provides a thermal energy decoupling control method for a three-dimensional stacked molding device, which can effectively decouple the coupling relationship between two heat source control loops, realize high-stability preheating temperature control and high-precision fusion bonding temperature control, and has low requirements on laser beam energy.

Fig. 4 is a schematic perspective view of a three-dimensional laminated molding apparatus according to a preferred embodiment of the present application, and fig. 5 is a schematic sectional view of the three-dimensional laminated molding apparatus according to the preferred embodiment of the present application, which includes, as shown in fig. 4 and 5: a forming bin 42 is arranged on the rigid frame 41, a forming cylinder 43 is arranged in the rigid frame 41, and the top of the forming cylinder 43 is connected with the bottom plate of the forming bin 42; a forming platform 44 is arranged in the forming cylinder 43, the forming platform 44 can move up and down in the forming cylinder 43 and is positioned, and when the finished product platform 44 moves up to the highest point, the finished product platform, the bottom plate of the forming bin 42 and the upper edge of the forming bin 43 form a complete plane; the bottom in the forming bin 42 is provided with a powder spreading unit 45, the powder spreading unit 45 can reciprocate on the bottom plate of the forming bin 42, and a flat powder layer is spread on the forming platform 44; a preheating unit 46 is arranged at the top in the forming bin 42, and the preheating unit 46 can uniformly radiate and heat the powder layer on the forming platform 44; the laser scanning unit 47 is arranged on the outer side of the top of the forming bin 42, and the laser scanning unit 47 can scan and irradiate the area of the forming platform 44 through the optical window 421; a temperature sensing array 48 is arranged on the outer side of the top of the forming bin 42, and the temperature sensing array 48 can detect the temperature distribution of the powder layer in the area of the forming platform 44 through an optical window 421;

FIG. 6 is an electrical schematic diagram of a three-dimensional laminated molding apparatus according to a preferred embodiment of the present invention, as shown in FIG. 6, a molding controller 100 is connected to a molding stage 44, the molding controller 100 is connected to a powder spreading unit 45, the molding controller 100 is connected to a preheating unit 46, the molding controller 100 is connected to a laser scanning unit 47, and the molding controller 100 is connected to a temperature sensing array 48; the forming controller 100 sends an electric signal to the forming platform 44 to control the forming platform 44 to move up and down and position in the forming cylinder 43; the forming controller 100 sends an electric signal to the powder spreading unit 45 to control the powder spreading unit to move on the bottom plate of the forming bin 42 in a reciprocating manner and spread powder on the forming platform 44; the shaping controller 100 sends an electrical signal to the preheating unit 46 to control the preheating unit 46 to perform radiation heating on the powder layer on the shaping platform 44; the shaping controller 100 sends an electrical signal to the laser scanning unit 47 to control the laser scanning unit 47 to scan and heat the laser beam on the powder layer on the shaping platform 44; the molding controller 100 sends an electrical signal to the temperature sensing array 48 to control the temperature sensing array 48 to detect the temperature division of the powder layer on the molding platform 44, and perform the region splitting, filtering and weighting calculation to obtain the preheating temperature measurement value and the hot-melt bonding temperature measurement value.

By applying the heat energy decoupling control method of the three-dimensional laminating molding device of the preferred embodiment, the work flow of the three-dimensional laminating molding device comprises the following steps:

before the first layer of powder is hot-melted and formed, sufficient powder materials are injected into the powder paving unit; the forming controller sends a moving instruction to the forming platform, and the forming platform is controlled to move upwards to a height corresponding to the single-layer curing thickness from the top end of the forming cylinder; the forming controller sends a powder laying instruction to the powder laying unit, the powder laying unit is controlled to pass above the forming platform at a constant speed, so that a powder thin layer is laid on the forming platform, and the powder thin layer just fills a space formed by an upper opening of the forming cylinder and the forming platform; the forming controller sends a preheating instruction to the preheating unit, and the preheating unit is controlled to radiate and heat the powder thin layer; the forming controller measures the preheating temperature of the powder thin layer through the temperature sensing array, and adjusts the heating power of the preheating unit according to the deviation of the measured value of the preheating temperature and a set value until the preheating temperature rises and is stabilized near the set value.

When the first layer of powder is subjected to hot melting forming, the forming controller sends a scanning instruction to the laser scanning unit, and the laser scanning unit is controlled to perform laser beam scanning irradiation on a powder layer hot melting forming area; the forming controller sends hot-melting forming area data to the temperature sensing array, the temperature sensing array is controlled to simultaneously acquire the temperature distribution of a powder layer hot-melting area and a non-hot-melting area, and the temperature measurement value of the non-hot-melting area and the temperature measurement value of the hot-melting area are calculated; the forming controller dynamically adjusts the heating power of the preheating unit according to the temperature measured value of the non-hot-melting area so as to maintain the preheating temperature of the powder layer to be stable; the forming controller dynamically adjusts the laser beam power of the laser scanning unit according to the temperature measured value of the hot melting area so as to maintain the stability of the hot melting forming temperature; the preheating temperature and the hot-melting forming temperature are continuously adjusted until the laser scanning unit finishes scanning irradiation of the first layer forming area, and a solidified forming object generated by hot-melting combination is attached to the forming platform.

When the subsequent layer of powder is subjected to hot melting forming, the forming controller firstly controls the forming platform to descend to a height corresponding to the single-layer curing thickness, and then controls the powder laying unit to lay a powder thin layer on the forming platform, so that the powder thin layer just fills a space formed by an upper opening of the forming cylinder and the upper layer of powder and a curing forming object; the forming controller controls the preheating unit to heat the powder thin layer until the preheating temperature rises and is stabilized near a set value; the forming controller sends a scanning instruction to the laser scanning unit, and the laser scanning unit is controlled to carry out laser beam scanning irradiation on the powder layer hot melting forming area; the forming controller sends hot-melting forming area data to the temperature sensing array, the temperature sensing array is controlled to simultaneously acquire the temperature distribution of a powder layer hot-melting area and a non-hot-melting area, and the temperature measurement value of the non-hot-melting area and the temperature measurement value of the hot-melting area are calculated; the forming controller dynamically adjusts the heating power of the preheating unit according to the temperature measured value of the non-hot-melting area so as to maintain the preheating temperature of the powder layer to be stable; the forming controller dynamically adjusts the laser beam power of the laser scanning unit according to the temperature measured value of the hot melting area so as to maintain the stability of the hot melting forming temperature until the laser scanning unit finishes the scanning irradiation of the current layer, and a solidified forming object generated by hot melting combination is attached to the surface of a solidified object obtained by the laser irradiation of the previous layer; and the steps of powder laying, preheating and laser scanning irradiation are repeated, and the solidified formed objects generated by hot melt bonding are accumulated layer by layer until a complete hot melt bonding three-dimensional formed body is formed.

According to the heat energy decoupling control method of the three-dimensional laminating modeling device, the temperature sensing array of the three-dimensional laminating modeling device adopts a non-contact mode to detect the temperature distribution of the complete powder layer on the forming platform; according to the laser scanning area data, dividing the complete powder layer temperature distribution data into a hot melting combination area and a non-hot melting combination area, so as to obtain a preheating temperature measurement value mainly influenced by preheating power and a hot melting combination temperature measurement value mainly influenced by instantaneous laser irradiation power; according to the regional temperature measuring method, the preheating control loop and the laser beam power control loop can independently run without interfering with each other, so that decoupling control of preheating heat energy and laser beam irradiation heat energy is realized, and the dual purposes of stable preheating temperature control and rapid and accurate hot melt combination problem control are achieved.

The preheating temperature set value of the embodiment of the application can approach the hot-melt bonding critical value of the powder material, and the problem of powder deterioration and agglomeration caused by large fluctuation of the preheating temperature is not considered; the hot-melt bonding temperature set value of the embodiment of the application can approach the ideal temperature value of the hot-melt bonding of the powder material, and the problem of uneven hot-melt bonding temperature distribution caused by the accumulation of laser irradiation heat in the single-row continuous scanning process is solved. The embodiment of the application can reduce the requirement of hot-melt bonding on the energy of the laser beam and improve the secondary recovery utilization rate of the powder, thereby obviously improving the economical efficiency of the three-dimensional powder forming device and having good popularization prospect in various three-dimensional powder forming applications based on the hot-melt bonding principle.

The operation of the three-dimensional laminated molding apparatus will be described and explained with reference to the drawings.

Fig. 7 is a schematic view showing a change in an operation state of the three-dimensional stack molding apparatus according to the preferred embodiment of the present application, and as shown in fig. 7, the operation of the three-dimensional stack molding apparatus sequentially includes the steps of:

step S701: the powder stereo forming process is executed to the nth layer, the powder 201 accumulated in the 1 st to the (n-1) th layer of powder stereo forming process and the hot melting combination 202 are arranged in the forming cylinder 43 and on the forming platform 44;

step S702: the forming platform 44 descends by a height corresponding to the thickness of single-layer curing and curing, the powder laying unit 45 reciprocates once on the bottom plate of the forming bin 42, and the laid nth layer of powder layer 203 just fills a forming cylinder opening gap generated by descending of the slow forming platform 44;

step S703: the preheating unit 46 performs radiation heating on the nth powder layer 203, and controls the preheating temperature through the temperature sensing array 48 until the temperature of the nth powder layer 203 rises and is stabilized near a set value;

step S704: the laser scanning unit 47 scans and irradiates the thermal fusion bonding region 2031 of the nth powder layer 203 to generate an nth thermal fusion bonding material 2032, and the nth thermal fusion bonding material 2032 is attached to the upper surface of the thermal fusion bonding material 202; after the laser scanning unit 47 finishes scanning and irradiating the thermal fusion bonding area 2031, the nth layer of thermal fusion bonding material 2032 extends to the whole 2031 area;

step S705: during the execution of step S704, the temperature sensing array 48 continuously detects the temperature distribution of the powder layer 203, and obtains the preheating temperature measurement value and the thermal fusion bonding temperature measurement value according to the range of the thermal fusion bonding area 2031, and the formation controller 100 continuously adjusts the heating power of the preheating unit 46 and the laser beam power of the laser scanning unit 47 according to the preheating temperature measurement value and the thermal fusion bonding temperature measurement value to maintain the preheating temperature and the thermal fusion bonding temperature stable;

fig. 8 is a schematic flow chart of extracting the temperature distribution in step S705 according to the preferred embodiment of the present application, and as shown in fig. 8, the temperature sensing array 48 detects the thermal radiation signal of the powder layer 203 and converts the thermal radiation signal into the raw measurement value array 301; the original measured value array 301 obtains a temperature distribution measured value array 302 through sensor characteristic correction and target reflectivity correction; the temperature distribution measurement array 302 is divided into a non-thermal melting temperature distribution array 3021 and a thermal melting temperature distribution array 3022 according to the thermal melting bonding area 2031; the non-hot-melting temperature distribution array 3021 obtains a preheating temperature measurement value 3031 through filtering and weighting calculation, and the hot-melting temperature distribution array 3022 obtains a hot-melting bonding temperature measurement value 3032 through filtering and weighting calculation;

fig. 9 is a schematic diagram illustrating the control of the graphic controller 100 in step S705 according to the preferred embodiment of the present application, and as shown in fig. 9, the graphic controller 100 has a preheating control loop 101 and a laser beam power control loop 102; the preheating control loop 101 is internally provided with a preheating temperature set value 1011, a deviation calculation module 1012, a control algorithm module 1013 and a signal output module 1014; the laser beam power control loop 102 is internally provided with a hot melting combination temperature set value 1021, a deviation calculation module 1022, a control algorithm module 1023 and a signal output module 1024; the preheating temperature measured value 3031 and the preheating temperature set value 1011 are input to the deviation calculation module 1012, the deviation calculation module 1012 outputs the preheating temperature deviation value to the control algorithm module 1013, the control algorithm module 1013 outputs a control signal to the signal output module 1014, and the signal output module 1014 outputs a power adjustment signal to the preheating unit 46; the measured value 3032 of the thermal fusion bonding temperature and the set value 1021 of the thermal fusion bonding temperature are input to the deviation calculation module 1022, the deviation calculation module 1022 outputs the thermal fusion bonding temperature deviation value to the control algorithm module 1023, the control algorithm module 1023 outputs a control signal to the signal output module 1024, and the signal output module 1024 outputs a power adjustment signal to the laser scanning unit 47.

The temperature sensing array of the embodiment of the application can detect the temperature distribution of all areas of the powder layer on the forming platform and convert the temperature distribution of the powder layer into a two-dimensional array of temperature measurement values arranged in a plane lattice; the temperature sensing array of the embodiment of the application can receive hot-melting forming area data sent by a forming controller, and the complete temperature measurement value two-dimensional array is split into a non-hot-melting area temperature measurement value array and a hot-melting area temperature measurement value array according to the hot-melting forming area data; the temperature sensing array of the embodiment of the application can be used for measuring the temperature of the non-hot-melting area and the hot-melting area according to the split temperature measurement value array of the non-hot-melting area and the split temperature measurement value array of the hot-melting area; according to the temperature sensing array, a non-hot-melting area temperature measured value array is subjected to filtering and weighted calculation to obtain a preheating temperature measured value, and a hot-melting area temperature measured value array is subjected to filtering and weighted calculation to obtain a hot-melting combination temperature measured value; the preheating temperature measurement value of the embodiment of the application is not influenced by the temperature change of the laser irradiation area powder layer, and the temperature change of the preheating area powder layer does not influence the hot melting combination temperature measurement value.

According to the preheating control loop, preheating temperature negative feedback closed-loop control is performed according to the preheating temperature measurement value output by the temperature sensing array; the laser beam power control loop of the embodiment of the application carries out hot melt combination temperature negative feedback closed-loop control according to the hot melt combination temperature measurement value output by the temperature sensing array; the preheating and the hot melting of the powder layer are combined, two independent control loops, independent power devices and independent temperature detection areas are adopted, the large thermal inertia and low-speed radiation preheating is realized, and the heat energy decoupling control of the small thermal inertia and high-speed laser hot melting is realized, so that the powder in a non-hot melting area is not overheated and does not deteriorate and agglomerate while the whole powder layer is fully preheated; laser irradiation, rapid heating and hot melting combination temperature control of the hot melting combination area are realized, and the problems of coking deterioration or insufficient hot melting caused by large temperature fluctuation are avoided.

According to the heat energy decoupling control method of the three-dimensional laminating modeling device, the temperature sensing array has strong pertinence to temperature measurement of different areas of the powder layer, and the preheating process and the hot melting combination process reflected by the temperature measurement value are more accurate; the temperature of a hot melting area is rapidly fluctuated due to laser irradiation heating, severe high-frequency disturbance cannot be injected into a preheating control loop, the preheating temperature of a powder layer slowly floats, the high-speed laser scanning irradiation and instantaneous heating are equal to fixed offset, and the dynamic control precision of the hot melting combination temperature cannot be influenced; the heat energy decoupling control method of the three-dimensional laminating molding device is reasonable in scheme, simple in structure, low in laser beam energy requirement and easy to popularize and apply in a low-cost and high-performance powder three-dimensional forming device.

The present embodiment further provides a temperature control device, which is used to implement the foregoing embodiments and preferred embodiments, and the description of the temperature control device is omitted for brevity. As used hereinafter, the terms "module," "unit," "subunit," and the like may implement a combination of software and/or hardware for a predetermined function. Although the means described in the embodiments below are preferably implemented in software, an implementation in hardware, or a combination of software and hardware is also possible and contemplated.

Fig. 10 is a block diagram of a temperature control device according to an embodiment of the present application, and as shown in fig. 10, the temperature control device includes:

a temperature detection module 1001 for detecting a temperature distribution on the surface of the laminated molding section of the three-dimensional laminated molding apparatus.

A first temperature extraction module 1002, coupled to the temperature detection module 1001, is configured to extract a first temperature distribution of a non-fusion bonding region of the surface of the laminated mold part from the temperature distribution.

A first control module 1003 coupled to the first temperature extraction module 1002 is configured to control a heating power of a preheating unit of the three-dimensional stack molding apparatus according to the first temperature distribution.

A second temperature extraction module 1004 coupled to the temperature detection module 1001 for extracting a second temperature distribution of the fusion bonding region of the surface of the laminated molding part from the temperature distribution.

A second control module 1005, coupled to the second temperature extraction module 1004, is used for controlling the laser emission power or the laser scanning speed of the laser scanning unit of the three-dimensional stack modeling apparatus according to the second temperature distribution.

In some of these embodiments, the first control module 1003 includes: a first calculating unit, coupled to the first temperature extracting module 1002, for calculating a weighted average of the first temperature distribution; and the first control unit is coupled to the first calculation unit and used for controlling the heating power of the preheating unit of the three-dimensional laminated modeling device by taking the weighted average value of the first temperature distribution as negative feedback.

In some of these embodiments, the second control module 1005 includes: a second calculating unit, coupled to the second temperature extracting module 1004, for calculating a weighted average of the second temperature distribution; and the second control unit is coupled to the second calculation unit and used for controlling the laser emission power or the laser scanning speed of the laser scanning unit of the three-dimensional laminated modeling device by taking the weighted average value of the second temperature distribution as negative feedback.

In some of these embodiments, the first temperature extraction module 1002 comprises: the acquisition unit is used for acquiring fusion bonding area data of the current three-dimensional laminating modeling task; the determining unit is coupled to the acquiring unit and used for determining the fusion bonding area according to the fusion bonding area data and taking the other areas of the surface of the three-dimensional laminated modeling part except the fusion bonding area as non-fusion bonding areas; an extraction unit, coupled to the determination unit, for extracting a first temperature distribution of the non-fusion bonding region from the temperature distribution.

There is also provided in this embodiment an electronic device, and fig. 11 is a schematic diagram of a hardware structure of an electronic device according to an embodiment of the present application, and as shown in fig. 11, the electronic device includes a memory 1101 and a processor 1102, where the memory 1101 stores a computer program 1103, and the processor 1102 is configured to execute the computer program 1103 to perform the steps in any one of the above embodiments of the temperature control method.

Optionally, the electronic apparatus may further include a transmission device 1104 and an input/output device 1105, where the transmission device 1104 is connected to the processor 1102, and the input/output device 1105 is connected to the processor 1102.

Optionally, in this embodiment, the processor 1102 may be configured to execute the following steps by the computer program 1103:

in step S1, the temperature distribution on the surface of the laminated molding section of the three-dimensional laminated molding device is detected.

In step S2, a first temperature distribution of the non-fusion bonding region of the surface of the laminated molding section is extracted from the temperature distributions, and the heating power of the preheating unit of the three-dimensional laminated molding device is controlled according to the first temperature distribution.

In step S3, a second temperature distribution of the fusion-bonded region of the surface of the laminated molded part is extracted from the temperature distribution, and the laser emission power or the laser scanning speed of the laser scanning unit of the three-dimensional laminated molding device is controlled according to the second temperature distribution.

Optionally, the specific examples in this embodiment may refer to the examples described in the above embodiments and optional implementation manners, and this embodiment is not described herein again.

There is also provided in the present embodiment a computer-readable storage medium having stored thereon a computer program, characterized in that the program, when executed by a processor, implements the temperature control method of the above-described embodiment.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A method of temperature control, comprising:

2. The temperature control method according to claim 1, wherein controlling the heating power of the preheating unit of the three-dimensional stack molding apparatus according to the first temperature distribution includes:

calculating a weighted average of the first temperature distribution;

3. The temperature control method according to claim 1, wherein controlling laser emission power or laser scanning speed of a laser scanning unit of the three-dimensional stack molding apparatus according to the second temperature distribution includes:

calculating a weighted average of the second temperature distribution;

4. A method of temperature control, comprising:

5. The temperature control method according to claim 4, wherein controlling the heating power of the preheating unit of the three-dimensional stack molding apparatus according to the first temperature distribution includes:

calculating a weighted average of the first temperature distribution;

6. The temperature control method according to claim 4, wherein controlling the laser emission power or the laser scanning speed of the laser scanning unit of the three-dimensional stack molding apparatus according to the second temperature distribution includes:

calculating a weighted average of the second temperature distribution;

7. The temperature control method according to claim 4, wherein extracting the first temperature distribution of the non-fusion-bonded region of the laminated molding surface from the temperature distribution includes:

8. A temperature control apparatus, characterized in that the apparatus comprises:

9. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the temperature control method according to any of claims 1 to 3 and/or the temperature control method according to any of claims 4 to 7 when executing the computer program.

10. A computer-readable storage medium, on which a computer program is stored, which program, when being executed by a processor, is adapted to carry out a temperature control method according to any one of claims 1 to 3 and/or a temperature control method according to any one of claims 4 to 7.