Multi-field coupled laser printing method and device

Abstract

The present invention proposes a multi-field coupled laser printing method, comprising: using a powder spreading device to spread powder on a forming worktable; controlling a laser to output laser light to scan and shape the powder spread on the forming worktable to form a printed layer; using a monitoring device to monitor the status value of the printed layer in real time, and comparing the difference between the status value and a preset reference value, wherein the status value includes at least one of a single laser printing energy input value, a multi-laser printing energy input value, a cooling air field flow rate value, a forming surface profile value, and a forming surface temperature value; when the difference exceeds a preset threshold, controlling the laser to reduce the energy density output to the powder using a control device. The present invention also provides a multi-field coupled laser printing device, comprising: a forming worktable; a powder spreading device; a laser; a monitoring device; and a control device. This method achieves thermal equilibrium between the temperature field and the circulating air field, thereby improving the quality of the printed object.

Description

Technical Field

[0001] The present invention relates to the technical field of laser printing, and in particular to a multi-field coupling laser printing method and device. Background Art

[0002] Selective Laser Melting (SLM) technology is currently the most precise forming method in metal 3D printing. SLM technology uses high-density laser spots to quickly scan two-dimensional graphics in a box with a protective atmosphere, so that the molten metal powder material solidifies into a thin layer of 30μm-50μm, and then prints precise 3D objects layer by layer.

[0003] Part formation during laser additive manufacturing involves the coupling of temperature, stress, and circulating air fields. Existing technologies present at least the following challenges: The input energy from laser printing causes the surface temperature of the printed part to rise, creating a significant temperature difference with the surrounding area. This leads to cooling and contraction, which in turn creates stress in the part under these large temperature differences and gradually releases at higher temperatures. Furthermore, the thermal balance between the temperature field and the circulating air field caused by this heat accumulation can vary over a wide temperature range, resulting in dimensional errors beyond the intended tolerances. Summary of the Invention

[0004] In view of the above, it is necessary to propose a multi-field coupled laser printing method and device to reduce the dimensional error of the printed body.

[0005] An embodiment of the present application provides a multi-field coupled laser printing method, comprising using a powder spreading device to spread powder on a forming workbench; controlling a laser to output laser light to scan and form the powder spread on the forming workbench to form a printed layer; using a monitoring device to monitor the state value of the printed layer in real time, and comparing the difference between the state value and a preset reference value, wherein the state value includes at least one of a single laser printing energy input value, a multi-laser printing energy input value, a cooling air field flow rate value, a forming surface contour dimension value, and a forming surface temperature value; when the difference exceeds a preset threshold value, using a control device to control the laser to reduce the energy density value output to the powder.

[0006] In some embodiments, using a control device to control the laser to reduce the energy density value output to the powder includes: using a database system to adjust the printing parameter data of the laser in real time, wherein the printing parameter data includes at least one of laser power and scanning speed; the control device adjusts the acquired printing parameter data to reduce the energy density value; when the difference does not exceed the preset threshold, the control device stops adjusting the printing parameter data.

[0007] In some embodiments, adjusting the acquired printing parameter data using the control device to reduce the energy density value includes: reducing printing laser power, and / or increasing scanning speed.

[0008] In some embodiments, controlling the laser to output laser light to scan and shape the powder laid on the forming workbench includes: controlling the laser to output a single laser beam to scan and shape the powder laid on the forming workbench, wherein the energy density of the single laser beam initially output to the powder is 50-80 J / mm 3 .

[0009] In some embodiments, the controlling the laser to output laser light to scan and shape the powder laid on the forming workbench includes: controlling the laser to output multiple laser beams to scan and shape the powder laid on the forming workbench, wherein the energy density of each laser beam initially output to the powder is 50-80 J / mm 3 .

[0010] The embodiment of the present application also provides a multi-field coupled laser printing device, including: a forming workbench; a powder spreading device for spreading powder on the forming workbench; a laser for outputting laser to scan and form the powder spread on the forming workbench to form a printing layer; a monitoring device for real-time monitoring of the state value of the printing layer, and comparing the difference between the state value and a preset reference value, wherein the state value includes at least one of a single laser printing energy input value, a multi-laser printing energy input value, a cooling wind field flow rate value, a forming surface contour dimension value, and a forming surface temperature value; a control device, communicatively connected to the monitoring device and the laser, and used to control the laser to reduce the energy density value output to the powder when the difference exceeds a preset threshold.

[0011] In some embodiments, the multi-field coupled laser printing device further includes: a database system, which is communicatively connected to the laser and the control device, respectively, and is used to adjust the printing parameter data of the laser in real time, so that the control device adjusts the acquired printing parameter data to reduce the energy density value, wherein the printing parameter data includes at least one of laser power and scanning speed.

[0012] In some embodiments, the control device is further configured to stop adjusting the printing parameter data when the difference does not exceed the preset threshold.

[0013] In some embodiments, the forming workbench is set in a circulating wind field, and the air supply volume of the circulating wind field is 100-130m 3 / h, the powder includes titanium alloy powder, and the laser is adjusted to output the energy density value in the range of 50-80J / mm 3 .

[0014] In some embodiments, the monitoring device includes a size monitoring element and a temperature monitoring element, and the size monitoring element and the temperature monitoring element are respectively communicated with the control device. The size monitoring element is used to monitor the contour size value of the forming surface of the printed layer, and the temperature monitoring element is used to monitor the temperature value of the forming surface of the printed layer.

[0015] In this way, during the process of using a laser to scan and form the powder laid on the forming workbench, the monitoring device monitors the forming state value of the powder. When the difference between each forming value and the preset reference value is compared and it is monitored that the difference exceeds the preset threshold, the control device is used to control the laser to reduce the energy density value output to the powder, so as to reduce the heat generated during the laser printing process, so that the temperature field and the circulating air field reach thermal equilibrium, the surface temperature of the printed body reaches a constant, the size of the printed body is kept in a stable state, the dimensional error of the printed body during printing is reduced, the stress of the printed body is ensured to be minimized, and the quality of the printed body is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 FIG. 1 is a schematic diagram of a multi-field coupled laser printing device according to a first embodiment of the present invention.

[0017] Figure 2 FIG. 4 is a schematic diagram of a second embodiment of the multi-field coupled laser printing device provided by the present invention.

[0018] Figure 3 It is a schematic diagram of a monitoring device in a multi-field coupled laser printing device provided by the present invention.

[0019] Figure 4 FIG. 4 is a flow chart of the multi-field coupled laser printing method provided by the present invention in the first embodiment.

[0020] Figure 5 FIG. 4 is a flow chart of the multi-field coupled laser printing method provided by the present invention in the second embodiment.

[0021] Figure 6 FIG. 4 is a flow chart of the multi-field coupled laser printing method provided by the present invention in the third embodiment.

[0022] Description of main component symbols

[0023] Laser 130

[0024] Monitoring device 140

[0025] Control device 150

[0026] Database System 160

[0027] Dimension monitoring element 141

[0028] Temperature monitoring element 142 DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0030] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", clockwise", "counterclockwise" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0031] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections, or mutual communication; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0032] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0033] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0034] See also Figure 1 In a first embodiment of the present invention, a multi-field coupled laser printing device is provided. The multi-field coupled laser printing device includes a forming workbench (not shown), a powder spreading device (not shown), a laser 130, a monitoring device 140, and a control device 150. The powder spreading device is used to spread powder on the forming workbench. The laser 130 is used to output a laser to scan and shape the powder spread on the forming workbench to form a printed layer. The monitoring device 140 is used to monitor the status value of the printed layer in real time and compare the difference between the status value and a preset reference value, wherein the status value includes at least one of a single laser printing energy input value, a multi-laser printing energy input value, a cooling air field flow rate value, a forming surface profile value, and a forming surface temperature value. The control device 150 is in communication with the monitoring device 140 and the laser 130 and is used to control the laser 130 to reduce the energy density value output to the powder when the difference exceeds a preset threshold.

[0035] In this way, by using the laser 130 to scan and form the powder laid on the forming workbench, the forming state value of the powder is monitored by the monitoring device 140. When the difference between the forming value and the preset reference value is compared and it is monitored that the difference exceeds the preset threshold, the control device 150 is used to control the laser 130 to reduce the energy density value output to the powder, which can reduce the heat generated during the laser printing process, so that the temperature field and the circulating air field reach thermal equilibrium, thereby making the surface temperature of the printed body constant, keeping the size of the printed body tending to a stable state, reducing the dimensional error of the printed body during printing, ensuring that the stress of the printed body tends to be minimized, and improving the quality of the printed body.

[0036] In such Figure 2 In the second embodiment shown, the multi-field coupled laser printing device further includes a database system 160. The database system 160 is in communication with the laser 130 and the control device 150, respectively, and is configured to store and adjust the printing parameter data of the laser 130 in real time. The control device 150 obtains the printing parameter data from the database system 160 and, based on the obtained printing parameter data and a comparison between the formed state value and a preset reference value, adjusts the printing parameter data so that the laser 130 emits laser light according to the adjusted printing parameter data, thereby reducing the energy density.

[0037] The printing parameter data includes at least one of laser power and scanning speed. The control device 150 reduces the laser power and / or scanning speed to enable the laser to reduce the energy density of the laser light emitted.

[0038] The control device 150 is further configured to stop adjusting the printing parameter data when the difference does not exceed a preset threshold value. This configuration stops adjusting the printing parameter data after the energy density of the laser 130 is reduced to achieve thermal equilibrium between the temperature field and the circulating air field, thereby maintaining thermal equilibrium between the temperature field and the circulating air field.

[0039] When the powder is titanium alloy powder, the laser 130 adjusts the energy density value output to the powder to be in the range of 50-80 J / mm 3 The range of energy density initially outputted by the laser 130 to the powder is limited. In this embodiment, the air volume of the circulating wind field is 100-130m 3 / h, which is convenient for adjusting the thermal balance between the temperature field and the circulating air field.

[0040] See also Figure 3In one embodiment, the monitoring device 140 includes a dimension monitoring element 141 and a temperature monitoring element 142, each of which is in communication with the control device 150. The dimension monitoring element 141 is used to monitor the contour dimension of the forming surface and transmit the monitored contour dimension value of the forming surface to the control device 150. The temperature monitoring element 142 is used to monitor the temperature of the forming surface and transmit the monitored temperature value of the forming surface to the control device 150. The control device 150 changes the contour dimension value and the temperature value of the forming surface by adjusting the energy density value of the input printing layer.

[0041] The present invention also provides a multi-field coupling laser printing method, which is applied to the multi-field coupling laser printing device mentioned above. Figure 4 In the first embodiment shown, the steps of the multi-field coupled laser printing method are as follows:

[0042] Step S210: using a powder spreading device to spread powder on a forming workbench.

[0043] Step S220: Control the laser 130 to output laser light to scan and shape the powder laid on the forming workbench to form a printing layer.

[0044] Step S230: Use the monitoring device 140 to monitor the status value of the printed layer in real time, and compare the difference between the status value and the preset reference value, wherein the status value includes at least one of the single laser printing energy input value, the multi-laser printing energy input value, the cooling air field flow rate value, the forming surface contour dimension value and the forming surface temperature value.

[0045] It can be understood that the status value includes at least one of a single laser printing energy input value, a multi-laser printing energy input value, a cooling air flow rate value, a forming surface profile value, and a forming surface temperature value. The forming surface profile value is the size of the printed object, and the forming surface temperature is the temperature of the printed object surface. The preset reference value includes the standard size value of the printed object and the maximum temperature value that does not affect the printing accuracy.

[0046] Step S240: When the difference exceeds a preset threshold, the control device 150 is used to control the laser 130 to reduce the energy density output to the powder.

[0047] It can be understood that the preset thresholds include a dimensional error threshold and a temperature rise threshold, wherein the dimensional error threshold can be specifically set to 0.3 mm, and the temperature rise threshold is based on the surface temperature of the printed body when the continuous printing height reaches 20 mm, and is set to an upper limit of 50°C. That is, when the difference between the contour dimension value of the formed surface of the printed body and the standard dimension value of the printed body during the printing process exceeds 0.3 mm, the control device 150 controls the laser 130 to reduce the energy density value output to the powder to reduce the difference between the contour dimension value of the formed surface of the printed body and the standard dimension value of the printed body, thereby ensuring the precision of the printed body; or, when the temperature of the surface of the printed body rises by more than 50°C at the reference temperature relative to the highest temperature value that does not affect the forming accuracy of the printed body, the control device 150 controls the laser 130 to reduce the energy density value output to the powder to maintain the thermal balance between the temperature field and the circulating air field; or, when the difference between the contour dimension value of the formed surface of the printed body and the standard dimension value of the printed body exceeds 0.3 mm and the temperature of the surface of the printed body rises by more than 50°C relative to the reference temperature value that does not affect the forming accuracy of the printed body, the control device 150 controls the laser 130 to reduce the energy density value output to the powder.

[0048] In this way, when the difference between the powder forming state value and the preset reference value is monitored to exceed the preset threshold during the printing process, the laser 130 is controlled to reduce the energy density value output to the powder to reduce the heat generated during the laser printing process, so that the temperature field and the circulating air field reach thermal equilibrium, the surface temperature of the printed body reaches a constant, the size of the printed body is kept in a stable state, the dimensional error of the printed body during printing is reduced, the stress of the printed body is ensured to be minimized, and the quality of the printed body is improved.

[0049] like Figure 5 In the second embodiment shown, in step S240 of the multi-field coupled laser printing method, using the control device 150 to control the laser 130 to reduce the energy density value output to the powder specifically includes: using the database system 160 to adjust the printing parameter data of the laser 130 in real time, wherein the printing parameter data includes at least one of the laser power and the scanning speed; using the control device 150 to adjust the obtained printing parameter data to reduce the energy density value; when the difference does not exceed the preset threshold, the control device 150 stops adjusting the printing parameter data.

[0050] It is understandable that when the difference between the contour dimension value of the formed surface of the printed body and the standard dimension value of the printed body does not exceed 0.3 mm and the temperature of the printed body surface does not increase by more than 50°C relative to the maximum temperature value that does not affect the forming accuracy of the printed body, the control device 150 stops adjusting the laser 130 to reduce the energy density value output to the powder, and no real-time parameter adjustment is required at this time.

[0051] In this way, the control device 150 is used to adjust the acquired printing parameter data to reduce the energy density value, and when the difference does not exceed the preset threshold, the control device 150 stops adjusting the printing parameter data to adjust the laser power and scanning speed during the printing process, thereby achieving control of the laser 130 to reduce the energy density value output to the powder.

[0052] like Figure 6 In the third embodiment shown, in step S240 of the multi-field coupled laser printing method, adjusting the acquired printing parameter data to reduce the energy density value by using the control device 150 includes: reducing the printing laser power, and / or increasing the scanning speed.

[0053] Specifically, it includes: gradually and multiple times reducing the printing laser power, reducing it by 10W each time, and the number of reductions shall not exceed 5 times, or gradually and multiple times increasing the scanning speed, increasing it by 50mm / s each time, and the number of adjustments shall not exceed 3 times. Reducing the printing laser power for adjustment can be preferred.

[0054] In some embodiments, controlling the laser 130 to output laser light to scan and shape the powder laid on the forming workbench includes: controlling the laser 130 to output a single laser beam to scan and shape the powder laid on the forming workbench, and the energy density of the single laser beam initially output to the powder is 50-80 J / mm 3 .

[0055] It is understandable that when using a single laser beam for printing, the printing format is limited to 280mm*280mm. In this state, the air supply volume of the circulating wind field is 100-130m 3 / h to achieve a better thermal balance between the temperature field and the circulating air field. Furthermore, the dimensional error threshold is set at 0.2mm, and the temperature rise threshold is set at 35°C. When the difference between the contour dimension of the printed surface and the standard dimension of the printed body exceeds 0.2mm, or the surface temperature of the printed body rises by more than 35°C relative to the maximum temperature that does not affect the printed body's forming accuracy, the control device 150 controls the laser 130 to reduce the energy density output to the powder. This limits the range of energy density initially outputted by a single laser beam to the powder, facilitating the adjustment of the thermal balance between the temperature field and the circulating air field.

[0056] In some embodiments, controlling the laser 130 to output laser light to scan and shape the powder laid on the forming workbench includes: controlling the laser 130 to output multiple laser beams to scan and shape the powder laid on the forming workbench, and the energy density of each laser beam initially output to the powder is 50-80 J / mm 3 .

[0057] It is understood that when using multiple laser beams for printing, the printing format is limited to 450mm*450mm—600mm*600mm, and the air supply volume of the circulating air field is set to 180-300m 3 / h to achieve a better thermal balance between the temperature field and the circulating air field. Furthermore, the dimensional error threshold is set at 0.3mm, and the temperature rise threshold is set at 50°C. When the difference between the contour dimension of the printed surface and the standard dimension of the printed body exceeds 0.3mm, or the temperature of the printed surface rises by more than 50°C relative to the maximum temperature that does not affect the printed body's forming accuracy, the control device 150 controls the laser 130 to reduce the energy density output to the powder. This limits the range of energy density values ​​initially output to the powder by each of the multiple laser beams, facilitating the adjustment of the thermal balance between the temperature field and the circulating air field.

[0058] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

[0059] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A multi-field coupled laser printing method, characterized in that: include: Using a powder spreading device to spread powder on a forming workbench; the forming workbench is located in a circulating air field; Controlling the laser to output laser light to scan and shape the powder laid on the forming workbench to form a printing layer; Using a monitoring device to monitor the state value of the printed layer in real time, and comparing the difference between the state value and a preset reference value, wherein the state value includes a cooling air field flow velocity value, a forming surface profile size value, and a forming surface temperature value, and the state value also includes a single laser printing energy input value or a multi-laser printing energy input value; When the difference exceeds a preset threshold, the control device is used to control the laser to reduce the energy density value output to the powder.

2. The multi-field coupled laser printing method according to claim 1, wherein: The controlling the laser to reduce the energy density output to the powder by using a control device comprises: Using a database system to adjust the printing parameter data of the laser in real time, wherein the printing parameter data includes at least one of laser power and scanning speed; The control device adjusts the acquired printing parameter data to reduce the energy density value; When the difference does not exceed the preset threshold, the control device stops adjusting the printing parameter data.

3. The multi-field coupled laser printing method according to claim 2, wherein: The step of adjusting the acquired printing parameter data by the control device to reduce the energy density value includes: Reduce the printing laser power, and / or, Increase scanning speed.

4. The multi-field coupled laser printing method according to claim 1, wherein: The controlling laser outputting laser to scan and shape the powder laid on the forming workbench comprises: The laser is controlled to output a single laser beam to scan and shape the powder laid on the forming workbench, and the energy density value of the single laser beam initially output to the powder is 50-80 J / mm³.

5. The multi-field coupled laser printing method according to claim 1, wherein: The controlling laser outputting laser to scan and shape the powder laid on the forming workbench comprises: The laser is controlled to output multiple laser beams to scan and shape the powder laid on the forming workbench, and the energy density value of each laser beam initially output to the powder is 50-80J / mm³.

6. A multi-field coupled laser printing device, characterized in that: include: Forming table; a powder spreading device, for spreading powder on the forming workbench; a laser, configured to output laser light to scan and shape the powder laid on the forming workbench to form a printing layer; A monitoring device is used to monitor the status value of the printed layer in real time and compare the difference between the status value and a preset reference value, wherein the status value includes a cooling air field flow rate value, a forming surface contour dimension value and a forming surface temperature value, and the status value also includes a single laser printing energy input value or a multi-laser printing energy input value; a control device is communicatively connected to the monitoring device and the laser, and is used to control the laser to reduce the energy density value output to the powder when the difference exceeds a preset threshold.

7. The multi-field coupled laser printing device according to claim 6, wherein: Also includes: A database system is respectively connected to the laser and the control device for adjusting the printing parameter data of the laser in real time, so that the control device adjusts the acquired printing parameter data to reduce the energy density value, wherein the printing parameter data includes at least one of laser power and scanning speed.

8. The multi-field coupled laser printing device according to claim 6, wherein: The control device is also used to: When the difference does not exceed the preset threshold, the control device stops adjusting the printing parameter data of the laser.

9. The multi-field coupled laser printing device according to claim 6, wherein: The forming workbench is arranged in a circulating wind field, the air supply volume of the circulating wind field is 100-130m³ / h, the powder includes titanium alloy powder, and the laser is adjusted to output the energy density value in the range of 50-80J / mm³ on the titanium alloy powder.

10. The multi-field coupled laser printing device according to claim 6, wherein: The monitoring device includes a size monitoring element and a temperature monitoring element, and the size monitoring element and the temperature monitoring element are respectively communicated with the control device. The size monitoring element is used to monitor the contour size value of the forming surface of the printed layer, and the temperature monitoring element is used to monitor the temperature value of the forming surface of the printed layer.

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