High-precision temperature control selective laser melting high-temperature preheating device and method

Abstract

The invention discloses a selective laser melting high-temperature preheating device with high-precision temperature control. The selective laser melting high-temperature preheating device comprises a laser; a forming cylinder; the piston is arranged in the forming cylinder in a lifting manner; the mounting plate is arranged on the piston, and a first accommodating groove is formed in the top surface of the mounting plate; the heating plate is arranged in the first accommodating groove and is provided with a heater; the forming base plate is arranged above the heating plate and is provided with a temperature sensor; the cooling mechanism is used for cooling the piston, the mounting plate, the heating plate and the forming base plate; a heat insulation plate is arranged between the bottom wall of the first containing groove of the installation plate and the heating plate. The invention further discloses a selective laser melting high-temperature preheating method with high-precision temperature control. Through the mode, the problem of cracking caused by overlarge temperature gradient in the SLM forming process is solved, the problems of low preheating temperature, low cooling speed and inaccurate temperature control of the formed substrate are also solved, the powder laser absorptivity can be improved to a certain extent, the scanning speed is increased, and the production efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of 3D printers, in particular to a high-precision temperature control laser selective melting high-temperature preheating device and method. BACKGROUND

[0002] Laser selective melting (SLM) technology, as an advanced additive manufacturing technology, can directly form any complex structure, has the characteristics of metallurgical bonding, dense structure and excellent mechanical properties. With the rapid development of aerospace field, the demand for lightweight and complex structure parts is increasing, and the development of aluminum alloy, titanium alloy, nickel-based high-temperature alloy and other materials makes SLM technology have wide application prospect in aerospace field.

[0003] In the SLM forming process, the printing powder is first laid on the printing substrate, then the laser emitted by the laser is used to melt the printing powder, after completion, the substrate is driven to descend in the forming cylinder by the driving cylinder, and the printing powder is laid again for printing, and the operation is repeated. However, in the traditional way, the temperature gradient between the temperature of the printing powder melting and the temperature of the substrate is large, and multiple laser melting is continuously carried out, which is easy to cause high residual stress of the substrate, and the precipitated phase in the alloy is easy to induce the generation of cracks, which brings many challenges to the printing of high-quality parts.

[0004] Research shows that substrate preheating can effectively reduce the problems of large temperature gradient and fast cooling speed in the SLM forming process, relieve the residual stress in the printing process, and improve the cracking of the alloy. In addition, substrate preheating can also improve the laser absorption rate of the material and speed up the scanning speed to improve the production efficiency.

[0005] However, although some researches have proposed to use substrate preheating to eliminate micro-cracks in the SLM forming process, the existing preheating methods have the problems of low preheating temperature, slow cooling speed, inaccurate temperature control, etc. Therefore, a high-precision temperature control laser selective melting high-temperature preheating device and method are needed. SUMMARY

[0007] (I) Technical problems to be solved In view of the deficiencies of the prior art, the present application provides a high-precision temperature control laser selective melting high-temperature preheating device and method, which can solve the above technical problems.

[0008] (II) Technical solutions To solve the above technical problems, the application provides a high-precision temperature control laser selective melting high-temperature preheating device, which comprises a laser arranged at the top of the printing cavity of a printer, a forming cylinder arranged at the bottom wall of the printing cavity and below the laser, and a piston arranged in the forming cylinder and capable of being lifted, characterized in that it further comprises a mounting plate arranged on the piston, wherein the top surface of the mounting plate is provided with a first receiving groove; a heating plate arranged in the first receiving groove, wherein the heating plate is provided with a heater electrically connected with a controller of the 3D printer; a forming base plate arranged above the heating plate, wherein the forming base plate is provided with a temperature sensor electrically connected with the controller; a cooling mechanism arranged at the bottom of the piston and used for cooling the piston, the mounting plate, the heating plate and the forming base plate; wherein a heat insulation plate is arranged between the bottom wall of the first receiving groove of the mounting plate and the heating plate, the heater of the heating plate is used for heating the heating plate and the forming base plate when the temperature sensor detects that the temperature of the forming base plate is too low, and the cooling mechanism is used for cooling the heating plate and the forming base plate when the temperature sensor detects that the temperature of the forming base plate is too high.

[0009] Further, the top surface of the heat insulation plate is provided with a second receiving groove, the heating plate is arranged in the second receiving groove, wherein the thickness of the heat insulation plate is equal to the depth of the first receiving groove, the thickness of the heating plate is equal to the depth of the second receiving groove, and the forming base plate is arranged on the top surface of the mounting plate.

[0010] Further, the top wall of the inner cavity of the forming cylinder is composed of a heat insulation material, the bottom wall of the first receiving groove of the mounting plate is provided with a first perforation, the bottom wall of the second receiving groove of the heat insulation plate is provided with a second perforation, wherein the conductive wire of the controller passes through the first perforation and the second perforation and is electrically connected with the heater, and the first adjusting structure and the second adjusting structure for adjusting the parallelism of the heating plate are arranged at intervals on the bottom wall of the first receiving groove of the mounting plate.

[0011] Further, the forming substrate for melting aluminum alloy powder, titanium alloy powder or nickel alloy powder, the heater comprises a first resistance wire, a second resistance wire and a third resistance wire in a strip shape, the first resistance wire is used for preheating the forming substrate for melting aluminum alloy powder, the second resistance wire is used for preheating the forming substrate for melting titanium alloy powder, and the third resistance wire is used for preheating the forming substrate for melting nickel alloy powder, wherein the first resistance wire, the second resistance wire and the third resistance wire are uniformly arranged in the heating plate, both ends of the first resistance wire, the second resistance wire and the third resistance wire are exposed in the second through hole and the first through hole, the first resistance wire, the second resistance wire and the third resistance wire are arranged at intervals and in the same horizontal plane, and the outer diameters and resistance values of the first resistance wire, the second resistance wire and the third resistance wire are different.

[0012] Further, the cooling mechanism comprises a first cooling inner cavity arranged in the piston, a first conveying pipe and a second conveying pipe, the first conveying pipe is used for inputting cold water to the first cooling inner cavity, and the second conveying pipe is used for outputting cooling water in the first cooling inner cavity, wherein one end of the first conveying pipe is connected with an input end of the first cooling inner cavity through a conveying pump, and one end of the second conveying pipe is connected with an output end of the first cooling inner cavity.

[0013] Further, the cooling mechanism further comprises a second cooling inner cavity arranged in the heating plate, the second cooling inner cavity is communicated with the first cooling inner cavity through a first channel and a second channel, wherein a first switch valve electrically connected with the controller is arranged in the first channel, and a second switch valve electrically connected with the controller is arranged in the second channel.

[0014] Further, the cooling mechanism further comprises a third cooling inner cavity arranged in the forming substrate, the third cooling inner cavity is communicated with the first cooling inner cavity through a third channel and a fourth channel, wherein a third switch valve electrically connected with the controller is arranged in the third channel, and a fourth switch valve electrically connected with the controller is arranged in the fourth channel.

[0015] Further, the heating plate and the forming substrate are arranged in a plane shape and in close contact, wherein an expansion structure is arranged on the top surface of the side wall of the second accommodating groove of the heat insulation plate or between the heating plate and the forming substrate, when the temperature of the heating plate reaches a dangerous temperature value, the expansion structure gradually expands to gradually expand the distance between the heating plate and the forming substrate.

[0016] To solve the above technical problems, the application provides another technical scheme: a high-precision temperature control laser selective melting high-temperature preheating method, characterized in that the above device is used for work, and the preheating method comprises the following steps: judging the powder to be melted on the forming substrate, the powder comprising aluminum alloy powder, titanium alloy powder or nickel alloy powder; selecting the corresponding resistance wire according to the powder type to heat the heating plate to preheat the forming substrate; and when the temperature sensor detects that the temperature of the forming substrate is too high, the cooling mechanism is used to cool the heating plate and the forming substrate.

[0017] Further, the step of cooling the heating plate and the forming substrate by the cooling mechanism comprises the following steps: in the forming stage of the forming substrate, the forming substrate is kept in constant temperature regulation, cold water is input into the first cooling inner cavity through the first conveying pipe, the cooling water in the first cooling inner cavity is output through the second conveying pipe, or when the temperature of the forming substrate is relatively high, the first switch valve in the first channel and the second switch valve in the second channel are controlled to be opened, so that the cold water in the first cooling inner cavity is input into the second cooling inner cavity to circulate and flow to cool the heating plate; after the printing and forming of the forming substrate are completed, the cold water is input into the first cooling inner cavity through the first conveying pipe, the cooling water in the first cooling inner cavity is output through the second conveying pipe, and the first switch valve in the first channel and the second switch valve in the second channel are controlled to be opened, so that the cold water in the first cooling inner cavity is input into the second cooling inner cavity to circulate and flow to cool the heating plate, and the third switch valve in the third channel and the fourth switch valve in the fourth channel are controlled to be opened at the same time, so that the cold water in the first cooling inner cavity is input into the third cooling inner cavity to circulate and flow to cool the forming substrate, so as to rapidly reduce the temperature of the forming substrate and shorten the printing cycle.

[0018] (Three) beneficial effects Compared with existing technologies, this invention provides a high-precision temperature-controlled laser selective melting (SLM) high-temperature preheating device and method, which has the following beneficial effects: The high-precision temperature-controlled laser selective melting (SLM) high-temperature preheating device disclosed in this invention includes: a laser, a forming cylinder, a piston that can be lifted and lowered within the forming cylinder, a mounting plate, a heating plate, a forming substrate, and a cooling mechanism. The mounting plate is mounted on the piston, and its top surface has a first receiving groove. The heating plate is located within the first receiving groove and is equipped with a heater. The forming substrate is positioned above the heating plate and contains a temperature sensor. The cooling mechanism is used to cool the piston, mounting plate, heating plate, and forming substrate. Through the above method, this invention solves the cracking problem caused by excessive temperature gradients during SLM forming, as well as the problems of low preheating temperature of the forming substrate, slow cooling rate, and inaccurate temperature control. It can also improve the powder laser absorption rate to a certain extent, accelerate scanning speed, and improve production efficiency. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the high-precision temperature control laser selective melting high-temperature preheating device of the present invention. Figure 2 for Figure 1 A partial structural diagram of the high-temperature preheating device for selective laser melting in the middle zone; Figure 3 for Figure 1 A schematic diagram of the second partial structure of the laser selective melting high-temperature preheating device; Figure 4 for Figure 1 A schematic diagram of the heating plate in a high-temperature preheating device for selective laser melting. Figure 5 for Figure 1 A partial structural schematic diagram of another embodiment of the laser selective melting high-temperature preheating device; Figure 6 for Figure 1 Electrical connection diagram of the controller of the laser selective melting high-temperature preheating device; Figure 7 This is a schematic flowchart of the high-precision temperature control laser selective melting high-temperature preheating method of the present invention. Figure 8 for Figure 7 A flowchart illustrating the sub-steps of step S103. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] like Figures 1-6 As shown, the high-precision temperature-controlled laser selective melting high-temperature preheating device disclosed in this invention includes a laser 11 disposed at the top of the printing cavity 10 of the printer, a forming cylinder 12 disposed on the bottom wall of the printing cavity 10 and located below the laser 11, a piston 13 that can be lifted and lowered in the forming cylinder 12, a mounting plate 14, a heating plate 15, a forming substrate 16, and a cooling mechanism.

[0022] Mounting plate 14 is mounted on piston 13, wherein the top surface of mounting plate 14 is provided with a first receiving groove 141.

[0023] A heating plate 15 is disposed within a first receiving slot 141, wherein a heater 21 electrically connected to the controller 20 of the 3D printer is provided within the heating plate 15. It should be understood that the heating plate 15 is made of a thermally conductive material, and the heat generated by the heater can be transferred to the heating plate 15.

[0024] Preferably, a heat insulation plate 17 is provided between the bottom wall of the first receiving groove 14 of the mounting plate 14 and the heating plate 15, so that heat can be reduced and transferred to the mounting plate 14.

[0025] The molding substrate 16 is positioned above the heating plate 15, allowing heat from the heating plate 15 to be transferred to the molding substrate 16. The molding substrate 16 contains a temperature sensor 22 electrically connected to the controller 20. It should be understood that the temperature sensor 22 can detect the temperature value of the molding substrate 16 in real time and transmit it to the controller 20.

[0026] A cooling mechanism is located at the bottom of piston 13 to cool piston 13, mounting plate 14, heating plate 15, and molding substrate 16. It should be understood that piston 13, mounting plate 14, heating plate 15, heat insulation plate 17, molding substrate 16, and cooling mechanism are all located inside the molding cylinder.

[0027] In other words, this embodiment can heat the molding substrate 16 using the heater 21 or cool the molding substrate 16 using the cooling mechanism, which can greatly improve the accuracy of temperature control and effectively solve the problems of low preheating temperature and slow cooling speed of the molding substrate.

[0028] In this embodiment, when the temperature sensor 22 detects that the temperature of the molding substrate 16 is too low, the heater 21 of the heating plate 15 is used to heat the heating plate 15 and the molding substrate 16. When the temperature sensor 22 detects that the temperature of the molding substrate 16 is too high, the cooling mechanism is used to cool the heating plate 15 and the molding substrate 16.

[0029] Preferably, the top surface of the heat insulation plate 17 is provided with a second receiving groove 171, and the heating plate 15 is disposed in the second receiving groove 171. The thickness of the heat insulation plate 17 is equal to the depth of the first receiving groove 141, and the thickness of the heating plate 15 is equal to the depth of the second receiving groove 171, so that the heat generated by the heating plate 15 is transferred upward to the molding substrate 16, and the molding substrate 16 is disposed on the top surface of the mounting plate 14. That is to say, the heating plate 15 is sealed and surrounded by the heat insulation plate 17 and the molding substrate 16, and the heat of the heating plate 15 is blocked by the heat insulation plate 17 from being transferred downward, so that the preheating effect of the heating plate 15 on the molding substrate 16 is better.

[0030] In this embodiment, the top wall of the inner cavity of the molding cylinder 12 is made of heat insulation material, the bottom wall of the first receiving groove 141 of the mounting plate 14 is provided with a first through hole, and the bottom wall of the second receiving groove 171 of the heat insulation plate 17 is provided with a second through hole. The second through hole and the second through hole correspond to each other, wherein the conductive wire of the controller 20 passes through the first through hole and the second through hole and is electrically connected to the heater 20.

[0031] Preferably, the bottom wall of the first receiving groove 141 of the mounting plate 14 is provided with a first adjustment structure 142 and a second adjustment structure 143 for adjusting the parallelism of the heating plate 15, so that the horizontal plane of the heating plate 15 can be adjusted by the first adjustment structure 142 and the second adjustment structure 143, thereby adjusting the parallelism of the molding substrate 16.

[0032] In this embodiment, the molding substrate 16 is used to melt aluminum alloy powder, titanium alloy powder, or nickel alloy (i.e., nickel-based high-temperature alloy) powder. Of course, the molding substrate 16 in this embodiment can also melt powders of other materials.

[0033] It is worth noting that, after research, the two key parameters for preheating the substrate 16 in the laser selective melting process are preheating temperature and cooling rate. The selection of preheating temperature mainly depends on factors such as material properties and forming efficiency. This invention has conducted in-depth research on the printing process of easily cracked alloys such as aluminum alloys, titanium alloys, and nickel alloys. These alloys will precipitate different types of precipitated phase components during the forming process, with decomposition temperatures of approximately 500°C for aluminum alloys, approximately 800°C for titanium alloys, and approximately 1000°C for nickel alloys. Therefore, the preheating temperature needs to be set below 1000°C to ensure the best forming effect in the printing process of different alloy materials.

[0034] In practical applications, for aluminum alloys, controlling the preheating temperature of the forming substrate 16 to above 300℃ is sufficient to effectively suppress residual stress generated during laser selective melting; for titanium alloys, a preheating temperature of above 500℃ is required to completely suppress residual stress; and for nickel alloys, a preheating temperature of above 600℃ is required to completely suppress residual stress. In other words, for aluminum alloys, a preheating temperature of 300℃-500℃ is needed for the forming substrate 16; for titanium alloys, a preheating temperature of 500℃-800℃ is needed; and for nickel alloys, a preheating temperature of 600℃-1000℃ is needed. It should be understood that the controller 20 is used to obtain the type of printing powder. The type of printing powder can be manually input into the acquisition module. When the controller 20 obtains from the acquisition module that the input type of printing powder is aluminum alloy, the controller 20 automatically controls the heating plate 15 to heat and keep the temperature of the molding substrate 16 within 300℃-500℃; when the controller 20 obtains from the acquisition module that the input type of printing powder is titanium alloy, the controller 20 automatically controls the heating plate 15 to heat and keep the temperature of the molding substrate 16 within 500℃-800℃; when the controller 20 obtains from the acquisition module that the input type of printing powder is nickel alloy, the controller 20 automatically controls the heating plate 15 to heat and keep the temperature of the molding substrate 16 within 600℃-1000℃.

[0035] Furthermore, higher preheating temperatures not only help regulate the microstructure and composition of titanium and nickel alloys, but also further optimize their mechanical properties and microstructure. Based on a comprehensive analysis of multiple factors, including alloy characteristics, residual stress suppression mechanisms, alloy performance regulation, and equipment heating capacity, the preheating temperature was ultimately controlled below 600℃. A constant high-temperature preheating process was achieved through a temperature control system, effectively suppressing the generation of microcracks in the alloy.

[0036] Furthermore, the heater 21 includes a first resistance wire 211, a second resistance wire 212, and a third resistance wire 213 in the shape of an elongated strip. The first resistance wire 211 is energized and heated to preheat the molten aluminum alloy powder forming substrate 16. The second resistance wire 212 is energized and heated to preheat the molten titanium alloy powder forming substrate 16. The third resistance wire 213 is energized and heated to preheat the molten nickel alloy powder forming substrate 16. In other words, the temperature range that the first resistance wire 211 can generate is 300℃-500℃, the temperature range that the second resistance wire 212 can generate is 500℃-800℃, and the temperature range that the third resistance wire 213 can generate is 600℃-1000℃. When it is necessary to melt aluminum alloy powder on the molding substrate 16, the molding substrate 16 can be preheated by energizing the first resistance wire 211. When it is necessary to melt titanium alloy powder on the molding substrate 16, the molding substrate 16 can be preheated by energizing the second resistance wire 212. When it is necessary to melt titanium alloy powder on the molding substrate 16, the molding substrate 16 can be preheated by energizing the third resistance wire 213.

[0037] In other words, when the controller 20 determines that aluminum alloy powder needs to be melted on the molding substrate 16, the controller 20 energizes the first resistance wire 211 (while the controller 20 does not energize the second resistance wire 212 and the third resistance wire 213) to preheat the molding substrate 16; when the controller 20 determines that titanium alloy powder needs to be melted on the molding substrate 16, the controller 20 energizes the second resistance wire 212 (while the controller 20 does not energize the first resistance wire 211 and the third resistance wire 213) to preheat the molding substrate 16; when the controller 20 determines that titanium alloy powder needs to be melted on the molding substrate 16, the controller 20 energizes the third resistance wire 213 (while the controller 20 does not energize the first resistance wire 211 and the second resistance wire 212) to preheat the molding substrate 16.

[0038] Preferably, the first resistance wire 211, the second resistance wire 212, and the third resistance wire 213 are evenly distributed within the heating plate 15. Both ends of the first resistance wire 211, the second resistance wire 212, and the third resistance wire 213 are exposed within the second and first through holes, respectively. The first resistance wire 211, the second resistance wire 212, and the third resistance wire 213 are spaced apart and located on the same horizontal plane, and their outer diameters and resistance values ​​are different. It should be understood that because the outer diameters and resistance values ​​of the first resistance wire 211, the second resistance wire 212, and the third resistance wire 213 are different, the temperatures they reach after being energized and heated are different. Specifically, the temperature reached by the first resistance wire 211 after being energized and heated is 300℃-500℃, the temperature reached by the second resistance wire 212 after being energized and heated is 500℃-800℃, and the temperature reached by the third resistance wire 213 after being energized and heated is 600℃-1000℃.

[0039] In this embodiment, the cooling mechanism includes a first cooling cavity 131 disposed within the piston 13, a first delivery pipe, and a second delivery pipe. The first cooling cavity 131 is used to contain cold water, which can be used to cool the piston 13, mounting plate 14, heating plate 15, heat insulation plate 17, and molding substrate 16. The first delivery pipe is used to input cold water into the first cooling cavity 131, and the second delivery pipe is used to output the cooling water from the first cooling cavity 131. One end of the first delivery pipe is connected to the input end of the first cooling cavity 131 via a delivery pump 23, and one end of the second delivery pipe is connected to the output end of the first cooling cavity 131. It should be understood that both the first and second delivery pipes are connected to a water chiller 24, which is electrically connected to a controller 20. The water chiller 24 can generate cold water and pump it into the first cooling cavity 131 through the first delivery pipe, and then recover the cooled water through the second delivery pipe.

[0040] Furthermore, the cooling mechanism also includes a second cooling cavity 151 disposed within the heating plate 15. The second cooling cavity 151 is connected to the first cooling cavity 131 via a first channel 152 and a second channel 153. The first channel 152 contains a first switching valve electrically connected to the controller 20, and the second channel 153 contains a second switching valve electrically connected to the controller 20. It should be understood that when the controller 20 controls the first switching valve to open, cold water in the first cooling cavity 131 can enter the second cooling cavity 151 through the first channel 152. When the controller 20 controls the second switching valve to open, cooling water in the second cooling cavity 151 can be output to the first cooling cavity 131 through the second channel 153. Additionally, the first channel 152 is also provided with a first one-way valve that directs the flow of cold water from the first cooling cavity 131 to the second cooling cavity 151, and the second channel 153 is also provided with a second one-way valve that directs the flow of cooling water from the second cooling cavity 151 to the first cooling cavity 131.

[0041] It is worth noting that the heating plate 15 in this embodiment has a receiving cavity, which is not connected to the second cooling cavity 151 and is not on the same plane. The heater 21 is disposed in the receiving cavity, that is, the first resistance wire 211, the second resistance wire 212, and the third resistance wire 213 are tightly disposed in the receiving cavity, and the receiving cavity is filled with a thermally conductive material layer, so that the heat generated by the first resistance wire 211, the second resistance wire 212, or the third resistance wire 213 can be quickly transferred. Of course, when the resistance wires of the heating plate 15 are heated, there is no water in the second cooling cavity 151.

[0042] Furthermore, the cooling mechanism also includes a third cooling cavity 161 disposed within the molded substrate 16. The third cooling cavity 161 is connected to the first cooling cavity 131 via a third channel 162 and a fourth channel 163. A third switching valve electrically connected to the controller 20 is disposed in the third channel 162, and a fourth switching valve electrically connected to the controller 20 is disposed in the fourth channel 163. It should be understood that when the controller 20 controls the third switching valve to open, cold water in the first cooling cavity 131 can enter the third cooling cavity 161 through the third channel 162. When the controller 20 controls the fourth switching valve to open, cooling water in the third cooling cavity 161 can be output to the first cooling cavity 131 through the fourth channel 163. Additionally, a third one-way valve is disposed in the third channel 162 to direct the flow of cold water from the first cooling cavity 131 towards the third cooling cavity 161, and a fourth one-way valve is disposed in the fourth channel 163 to direct the flow of cooling water from the third cooling cavity 161 towards the first cooling cavity 131.

[0043] It is worth noting that in this embodiment, the molded substrate 16 can be cooled by multiple cooling cavities or by a single cooling cavity. Specifically, when the molded substrate 16 is preheated using the first resistance wire 211 (since the temperature generated by the first resistance wire 211 is not high), when cooling is required, the piston 13, mounting plate 14, heating plate 15, heat insulation plate 17, and molded substrate 16 are cooled using the first cooling cavity 131; when the molded substrate 16 is cooled using the second resistance wire 212... During preheating (since the temperature generated by the second resistance wire 212 is not high), when cooling is required, the piston 13, mounting plate 14, heating plate 15, heat insulation plate 17, and molding substrate 16 are cooled using the second cooling cavity 151; when the molding substrate 16 is preheated using the third resistance wire 213 (since the temperature generated by the third resistance wire 213 is not high), when cooling is required, the piston 13, mounting plate 14, heating plate 15, heat insulation plate 17, and molding substrate 16 are cooled using the third cooling cavity 161.

[0044] Of course, in other embodiments, multiple resistance heating wires can be used simultaneously to preheat the molded substrate 16. The number of resistance wires used for heating corresponds one-to-one with the number of cooling cavities used for cooling. Each resistance wire and each cooling cavity also corresponds one-to-one (i.e., the first resistance wire 211 corresponds to the first cooling cavity 131, the second resistance wire 212 corresponds to the second cooling cavity 151, and the third resistance wire 213 corresponds to the third cooling cavity 161; the resistance wires and their corresponding cooling cavities must operate simultaneously, and the cooling cavity corresponding to the operating resistance wire must be used for cooling). When the first resistance wire is used... When the resistance wire 211 and the second resistance wire 212 preheat the molding substrate 16, the piston 13, mounting plate 14, heating plate 15, heat insulation plate 17 and molding substrate 16 are cooled using the first cooling cavity 131 and the second cooling cavity 151 when cooling is required. When the first resistance wire 211, the second resistance wire 212 and the third resistance wire 213 are used to preheat the molding substrate 16, the piston 13, the mounting plate 14, the heating plate 15 and the heat insulation plate 17 and molding substrate 16 are cooled using the first cooling cavity 131, the second cooling cavity 151 and the third cooling cavity 161 when cooling is required.

[0045] In this embodiment, the heating plate 15 and the molding substrate 16 are planar and in close contact. However, to improve safety, in other embodiments, an expansion structure is provided between the heating plate 15 and the molding substrate 16 or on the top surface of the side wall of the second receiving groove 171 of the heat insulation plate 17 (i.e., an expansion structure can be provided between the heating plate 15 and the molding substrate 16, and an expansion structure can also be provided between the top surface of the side wall of the second receiving groove 171 of the heat insulation plate 17 and the molding substrate 16). When the temperature of the heating plate 15 or the molding substrate 16 reaches a dangerous temperature value (e.g., 1200 degrees Celsius), the expansion structure gradually expands to gradually increase the distance between the heating plate 15 and the molding substrate 16, so that the molding substrate 16 does not contact the heating plate 15, preventing further heating. Alternatively, when the molding substrate 16 has just finished printing, the expansion structure is controlled to gradually expand to gradually increase the distance between the heating plate 15 and the molding substrate 16, which facilitates faster heat dissipation. At the same time, during the gradual expansion of the expansion structure, the third cooling cavity 161 is also controlled to cool the molding substrate 16. It should be understood that the expansion structure is a structure that automatically expands when the temperature reaches a dangerous temperature (the expansion structure contains expansion material, which will automatically expand when the temperature reaches a dangerous temperature, thereby lifting the molding substrate 16). It may be equipped with a trigger. When the temperature of the heating plate 15 reaches the dangerous temperature value, the trigger will trigger an alarm to cause the expansion structure to expand, thereby triggering the expansion structure to automatically expand to lift the molding substrate 16, so that the molding substrate 16 is not in close contact with the heating plate 15.

[0046] Of course, in other embodiments, an expansion structure may not be provided between the heating plate 15 and the molding substrate 16, or between the top surface of the side wall of the second receiving groove 171 of the heat insulation plate 17 and the molding substrate 16. That is, a drive cylinder may be provided between the top surface of the side wall of the second receiving groove 171 of the heat insulation plate 17 and the molding substrate 16. Specifically, the top surface of the side wall of the second receiving groove 171 of the heat insulation plate 17 has a concave hole, and the drive cylinder is disposed in the concave hole (that is, the drive cylinder and its telescopic rod are both received in the concave hole). The telescopic rod of the drive cylinder is connected to the molding substrate 16, and the molding substrate 16 can be lifted by extending the telescopic rod of the drive cylinder to separate the molding substrate 16 from the heating plate 15. When the temperature sensor detects that the temperature of the heating plate 15 or the molding substrate 16 reaches a dangerous temperature value, the controller 20 controls the drive cylinder to work so that the telescopic rod of the drive cylinder extends to lift the molding substrate 16.

[0047] like Figure 7 As shown, this invention also discloses a high-precision temperature-controlled laser selective melting high-temperature preheating method. This method uses the aforementioned apparatus and specifically includes the following steps: Step S101: Determine the powder to be melted on the molding substrate 16, which includes aluminum alloy powder, titanium alloy powder, or nickel alloy powder. It should be understood that step S101 can obtain the type of powder to be melted on the molding substrate 16 through an acquisition module.

[0048] Step S102: Select the corresponding resistance wire according to the type of powder to heat the heating plate 15 to preheat the molding substrate 16. That is, each type of resistance wire corresponds to a type of powder that needs to be melted.

[0049] Step S103: When the temperature sensor 22 detects that the temperature of the molding substrate 16 is too high, the heating plate 15 and the molding substrate 16 are cooled by the cooling mechanism.

[0050] Furthermore, such as Figure 8 As shown, step S103, which involves cooling the heating plate and the molding substrate using the cooling mechanism, includes the following steps: Step S1031: During the molding stage of the molding substrate 16, ensure that the molding substrate 16 is under constant temperature regulation, input cold water into the first cooling cavity 131 through the first conveying pipe, and output the cooling water in the first cooling cavity 131 through the second conveying pipe, or when the temperature of the molding substrate 16 is relatively high, control the first switch valve in the first channel and the second switch valve in the second channel to open, so that the cold water in the first cooling cavity 131 is input into the second cooling cavity 151 for circulation to cool the heating plate 15.

[0051] Step S1032: After the molding substrate 16 is printed, cold water is input into the first cooling cavity 131 through the first delivery pipe and the cooling water in the first cooling cavity 131 is output through the second delivery pipe. At the same time, the first switch valve in the first channel and the second switch valve in the second channel are opened, so that the cold water in the first cooling cavity 131 is input into the second cooling cavity 151 for circulation to cool the heating plate 15. At the same time, the third switch valve in the third channel and the fourth switch valve in the fourth channel are opened, so that the cold water in the first cooling cavity 131 is input into the third cooling cavity 33 for circulation to cool the molding substrate 16, thereby achieving a rapid reduction in the temperature of the molding substrate 16 and shortening the printing cycle.

[0052] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A high-precision temperature-controlled laser selective melting high-temperature preheating device, comprising a laser disposed at the top of the printing cavity of a printer, a forming cylinder disposed on the bottom wall of the printing cavity and below the laser, and a piston that can be vertically and vertically disposed within the forming cylinder, characterized in that, Also includes: A mounting plate is disposed on the piston, wherein the top surface of the mounting plate is provided with a first receiving groove; A heating plate is disposed in the first receiving slot, wherein the heating plate is provided with a heater that is electrically connected to the controller of the 3D printer; A molding substrate is disposed above the heating plate, wherein a temperature sensor electrically connected to the controller is provided inside the molding substrate; A cooling mechanism is provided at the bottom of the piston for cooling the piston, the mounting plate, the heating plate, and the molding substrate; A heat insulation plate is provided between the bottom wall of the first receiving groove of the mounting plate and the heating plate. When the temperature sensor detects that the temperature of the molding substrate is too low, the heater of the heating plate is used to heat the heating plate and the molding substrate. When the temperature sensor detects that the temperature of the molding substrate is too high, the cooling mechanism is used to cool the heating plate and the molding substrate.

2. The high-precision temperature-controlled laser selective melting high-temperature preheating device according to claim 1, characterized in that, The heat insulation plate has a second receiving groove on its top surface, and the heating plate is disposed in the second receiving groove. The thickness of the heat insulation plate is equal to the depth of the first receiving groove, the thickness of the heating plate is equal to the depth of the second receiving groove, and the molded substrate is disposed on the top surface of the mounting plate.

3. The high-precision temperature-controlled laser selective melting high-temperature preheating device according to claim 2, characterized in that, The top wall of the inner cavity of the forming cylinder is made of heat insulation material. The bottom wall of the first receiving groove of the mounting plate is provided with a first through hole, and the bottom wall of the second receiving groove of the heat insulation plate is provided with a second through hole. The conductive wire of the controller passes through the first through hole and the second through hole and is electrically connected to the heater. The bottom wall of the first receiving groove of the mounting plate is provided with a first adjustment structure and a second adjustment structure for adjusting the parallelism of the heating plate at intervals.

4. The high-precision temperature-controlled laser selective melting high-temperature preheating device according to claim 3, characterized in that, The molding substrate is used to melt aluminum alloy powder, titanium alloy powder, or nickel alloy powder. The heater includes a first resistance wire, a second resistance wire, and a third resistance wire in the shape of elongated strips. The first resistance wire is energized and heated to preheat the molding substrate containing molten aluminum alloy powder. The second resistance wire is energized and heated to preheat the molding substrate containing molten titanium alloy powder. The third resistance wire is energized and heated to preheat the molding substrate containing molten nickel alloy powder. The first, second, and third resistance wires are uniformly distributed within the heating plate. Both ends of the first, second, and third resistance wires are exposed within the second and first through holes, respectively. The first, second, and third resistance wires are spaced apart and located on the same horizontal plane. The outer diameter and resistance value of the first, second, and third resistance wires are all different.

5. The high-precision temperature-controlled laser selective melting high-temperature preheating device according to claim 4, characterized in that, The cooling mechanism includes a first cooling chamber disposed inside the piston, a first delivery pipe and a second delivery pipe. The first delivery pipe is used to input cold water into the first cooling chamber, and the second delivery pipe is used to output the cooling water in the first cooling chamber. One end of the first delivery pipe is connected to the input end of the first cooling chamber through a delivery pump, and one end of the second delivery pipe is connected to the output end of the first cooling chamber.

6. The high-precision temperature-controlled laser selective melting high-temperature preheating device according to claim 5, characterized in that, The cooling mechanism further includes a second cooling cavity disposed within the heating plate. The second cooling cavity is connected to the first cooling cavity via a first channel and a second channel. The first channel is provided with a first switching valve electrically connected to the controller, and the second channel is provided with a second switching valve electrically connected to the controller.

7. The high-precision temperature-controlled laser selective melting high-temperature preheating device according to claim 6, characterized in that, The cooling mechanism further includes a third cooling cavity disposed within the molded substrate. The third cooling cavity is connected to the first cooling cavity via a third channel and a fourth channel. A third switching valve electrically connected to the controller is disposed in the third channel, and a fourth switching valve electrically connected to the controller is disposed in the fourth channel.

8. The high-precision temperature-controlled laser selective melting high-temperature preheating device according to claim 4, characterized in that, The heating plate and the molding substrate are planar and in close contact. An expansion structure is provided between the heating plate and the molding substrate or on the top surface of the side wall of the second receiving groove of the heat insulation plate. When the temperature of the heating plate reaches a dangerous temperature value, the expansion structure gradually expands to gradually increase the distance between the heating plate and the molding substrate.

9. A high-precision temperature-controlled laser selective melting high-temperature preheating method, characterized in that, The preheating method, which operates using the apparatus as described in claims 1-8, comprises: Determine the powder that needs to be melted on the molded substrate, including aluminum alloy powder, titanium alloy powder, or nickel alloy powder. The heating plate is heated by selecting the corresponding resistance wire according to the type of powder to preheat the molded substrate; When the temperature sensor detects that the temperature of the molding substrate is too high, the cooling mechanism is used to cool the heating plate and the molding substrate.

10. The high-precision temperature-controlled laser selective melting high-temperature preheating method according to claim 9, characterized in that, The step of cooling the heating plate and the molding substrate using the cooling mechanism includes: During the molding stage of the substrate, the substrate is kept under constant temperature regulation. Cold water is input into the first cooling cavity through the first conveying pipe and the cooling water in the first cooling cavity is output through the second conveying pipe. Alternatively, when the temperature of the substrate is relatively high, the first switching valve in the first channel and the second switching valve in the second channel are opened to allow the cold water in the first cooling cavity to be input into the second cooling cavity for circulation to cool the heating plate. After the molding substrate is printed, cold water is input into the first cooling cavity through the first delivery pipe and output from the first cooling cavity through the second delivery pipe. At the same time, the first switch valve in the first channel and the second switch valve in the second channel are opened, so that the cold water in the first cooling cavity is input into the second cooling cavity for circulation to cool the heating plate. Simultaneously, the third switch valve in the third channel and the fourth switch valve in the fourth channel are opened, so that the cold water in the first cooling cavity is input into the third cooling cavity for circulation to cool the molding substrate. This achieves rapid reduction of the temperature of the molding substrate and shortens the printing cycle.

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