A real-time temperature control system and control method for additive manufacturing deposition process

Abstract

The present invention discloses an intelligent real-time temperature control system and control method for an additive remanufacturing deposition process, including a base device, a temperature sensor, a fixture and a temperature control platform; the base device includes a base body and a base plate, the base plate is fixed on the top of the base body; a heating tank and a cooling pipe are arranged in the base body; the temperature sensor is embedded in the base plate; a resistance wire is arranged in the heating tank; one end of the cooling pipe is a water inlet, and the other end is a water outlet, the water inlet is connected to a running water faucet, and the water outlet is used for drainage. Therefore, the present invention can perform intelligent control based on the difference between the actual temperature of the system and the target temperature fed back, and quickly and stably maintain the target temperature range. It solves the problem that the prior art can only cool, that is, the temperature can only go downward in one direction.

Description

Technical Field

[0001] The present invention relates to the technical field of additive remanufacturing engineering, and in particular to an intelligent real-time temperature control system and a control method thereof for an additive remanufacturing deposition process. Background Art

[0002] Additive remanufacturing technology is a general term for a series of advanced technologies used to restore the defect size and service performance of damaged parts (components). The size restoration and performance improvement of damaged parts (components) is a discrete-accumulation process. In this nonlinear strong coupling process, the heat source energy density is concentrated, and the temperature and physical properties of the material are extremely non-uniform, which is inevitably accompanied by the evolution of stress and strain. During the forming process, there is a huge temperature gradient between the forming layer and the substrate, which generates huge thermal stress. When the thermal stress reaches the material limit, the specimen will crack or even break.

[0003] During the deposition forming process, improper temperature control can lead to overheating of the forming layer and the workpiece, thermal deformation and aging of the substrate material, and damage stress caused by the mismatch between the thermal expansion coefficient of the forming structure and the substrate. When damage occurs due to overheating and thermal stress, the formed part will peel off during use.

[0004] Effective temperature control methods are required during the additive remanufacturing process to avoid overheating or overcooling.

[0005] In existing cooling technologies, the cooling method using compressed air and liquid CO2 cannot efficiently and quickly remove the heat generated during the remanufacturing process, resulting in cooling intervals in the gaps between the forming layers, which in turn leads to reduced production efficiency and waste of powder, fuel or energy. In addition, CO2 and air can easily cause oxidation of the metal coating surface, thereby reducing the deposition efficiency of the powder on the substrate.

[0006] Therefore, how to develop an effective real-time temperature control intelligent system for the substrate and its forming control method to effectively reduce the temperature gradient of the forming structure and the substrate during the forming process, improve the temperature distribution during the forming process, reduce the temperature gradient and thermal stress during the forming process, inhibit the generation of cracks in the forming structure during the deposition process, reduce production costs and improve production efficiency has become an important issue that urgently needs to be solved in additive remanufacturing technology.

[0007] Regarding the temperature control technology of the additive remanufacturing deposition process, Chinese patent document CN108115135B (application number 201711459891.7) discloses a device for temperature control of the metal additive manufacturing process, including a printing substrate, a printing component arranged on the outer surface of the printing substrate, a cooling device and a temperature monitor, wherein the temperature monitor is used to monitor the real-time temperature of the printing component; the cooling device includes a water mist nozzle, an integrated pipeline connected to the water mist nozzle, an air supply unit and a water supply unit connected to the integrated pipeline, wherein the water mist nozzle is arranged inside the printing substrate, the water mist nozzle is at a preset distance from the inner surface of the printing substrate, the water mist nozzle is used to spray cooling water mist, and the cooling water mist acts on the printing substrate in contact with the printing component; and the printing substrate is introduced with balancing water for balancing the overall temperature of the printing component. The present invention has a simple structure, realizes rapid and uniform cooling, and accurately controls the printing temperature, with an error within ±15°C.

[0008] Chinese patent document CN111250853B (application number 202010085413.X) discloses a synchronous cooling device and method based on electron beam fuse additive manufacturing. The device includes a moving device and a synchronous cooling system arranged in a vacuum chamber. The upper end of the moving device is fixed to the top of the vacuum chamber. The synchronous cooling system is connected to the moving device. The moving device drives the synchronous cooling system to move up and down. During electron beam fuse additive manufacturing, the synchronous cooling system and the electron beam synchronously contact the upper surface of the component; the synchronous cooling system includes a cooling box, a flange clamp, a transition device, a clamping device, a woven copper mesh and a coolant. The upper end of the transition device is connected to the cooling box through a flange clamp, and the lower end of the transition device is connected to the woven copper mesh through a clamping device; the cooling box includes a water-cooling block arranged at the upper part and a cooling cavity arranged at the lower part, and the water-cooling block and the cooling cavity are separated by the lower end surface of the water-cooling block.

[0009] For example, Chinese patent document CN112338207A (application number 202011311707.6) discloses an additive workpiece dot matrix circulation cooling mechanism, including a cooling table, on which a cooling module for cooling the upper surface of the workpiece is provided, and a cooling channel for circulating coolant is provided inside the cooling module, and the bottom surface of the cooling module in contact with the upper surface of the workpiece protrudes downward from the bottom surface of the cooling table; by arranging a plurality of cooling modules with cooling channels in an array on the cooling table, the purpose of cooling the upper surface of the workpiece is achieved, the cooling efficiency of the upper surface of the workpiece is improved, and by cooling the upper surface of the printed workpiece, the heat on the upper surface of the workpiece can complete the cooling process before being transferred to other parts of the workpiece.

[0010] The above temperature control technologies only consider how to achieve rapid cooling, but do not consider the problem of correcting the deviation between the actual temperature and the target temperature if the cooling is excessive. Summary of the invention

[0011] The technical problem to be solved by the present invention is to provide an intelligent real-time temperature control system and a control method thereof that can quickly and stably maintain an additive remanufacturing deposition process within a target temperature range.

[0012] The technical solution for achieving the first purpose of the present invention is an intelligent real-time temperature control system for additive remanufacturing deposition process, including a base device, a temperature sensor, a fixture and a temperature control platform; the base device includes a base body and a base plate, and the base plate is fixed on the top of the base body; a heating groove and a cooling pipe are arranged in the base body; the temperature sensor is embedded in the base plate; a resistance wire is arranged in the heating groove; one end of the cooling pipe is a water inlet, and the other end is a water outlet, the water inlet is connected to a running water faucet, and the water outlet is drained.

[0013] The temperature control platform includes a temperature control unit, a microprocessor, a mobile terminal, an electric automatic temperature control valve and a self-holding pulse solenoid valve; the temperature control unit is connected to the self-holding pulse solenoid valve and the electric automatic temperature control valve, the self-holding pulse solenoid valve controls the temperature of the regulating resistance wire, and the electric automatic temperature control valve is installed on the cooling pipeline.

[0014] The plane where the heating groove is located is closer to the base plate than the plane where the cooling pipe is located.

[0015] Optionally, the heating grooves are arranged in a continuous "bow" shape in the base body, and the resistance wires in the heating grooves are arranged in a Z shape.

[0016] The temperature sensors are evenly arranged on the base plate, and temperature sensors are set at the four corners, edges and center of the base plate; the signals of all temperature sensors are transmitted to the temperature control platform.

[0017] The microprocessor of the temperature control platform is connected to the temperature control unit by signal, and the microprocessor includes a data acquisition module, a data analysis module and a communication module; the data acquisition module acquires the temperature parameters of the substrate; the data analysis module compares the acquired temperature with the set value of the substrate temperature in the additive remanufacturing technology process to obtain the temperature value that needs to be increased or decreased; the communication module sends the obtained temperature value that needs to be increased or decreased to the temperature control unit; the microprocessor is connected to a terminal for displaying the set temperature by wire or wirelessly.

[0018] The technical solution for achieving the second object of the present invention is the control method of the above control system, comprising the following steps:

[0019] S1: Fix the substrate to be remanufactured on the base plate by a clamp, and the substrate is in contact with the temperature sensor.

[0020] S2: The data acquisition module of the microprocessor of the temperature control platform collects the temperature parameters of the additive remanufacturing substrate; the data analysis module receives the collected temperature parameters, compares them with the temperature range values ​​set by the mobile terminal, and obtains the temperature value that needs to be increased or decreased. The mobile terminal can display the temperature parameters; the communication module sends the obtained temperature value that needs to be increased or decreased to the temperature control unit as a reference.

[0021] S3: When the temperature needs to be increased during the substrate preheating stage, the temperature control unit transmits a signal to the self-holding pulse solenoid valve to start the resistance wire heating to reach the set temperature value to achieve substrate preheating.

[0022] S4: When the substrate needs to be cooled down, the temperature control unit sends a signal to the electric automatic temperature control valve, which intelligently adjusts the cooling water flow rate to achieve a refrigeration cycle, lower the substrate temperature, and maintain the substrate temperature in the additive remanufacturing process within the set substrate temperature range to achieve cooling of the substrate.

[0023] The present invention has positive effects:

[0024] (1) The intelligent real-time temperature control system of the present invention detects the temperature of the substrate through a temperature sensor to obtain a temperature signal, and then feeds the temperature signal back to the control processing unit for calculation processing to generate a linear control signal, so that the current of the resistance wire and the cooling water flow are under the linear control signal. The heating of the resistance wire and the cooling of the water circulation control the substrate temperature in the additive remanufacturing process within a set range. Therefore, the present invention can perform intelligent control based on the difference between the actual temperature of the system and the target temperature fed back, and quickly and stably maintain the target temperature range. It solves the problem that the prior art can only cool, that is, the temperature can only go down in one direction.

[0025] (2) The real-time temperature control system of the present invention can adjust and control the preheating temperature of the substrate and the cooling time of the formed structure during the additive remanufacturing process, thereby solving the problems of thermal deformation and aging of the substrate material, eliminating the cooling interval, and realizing additive remanufacturing at a faster speed and lower cost.

[0026] At the same time, the intelligent control system ensures a low and stable temperature gradient when the formed structure is combined with the substrate through real-time monitoring and control of the substrate temperature, improves the temperature distribution during the forming process, reduces the temperature gradient and thermal stress during the forming process, and inhibits the generation of cracks in the formed structure during the deposition process, thereby achieving high-efficiency and high-quality additive remanufacturing.

[0027] (3) The present invention can be widely applied to additive remanufacturing technologies such as laser cladding, welding, and thermal spraying. It can adjust the temperature parameters required by the substrate for different additive remanufacturing technologies and solve the influence of heat input on the substrate in different additive manufacturing technologies.

[0028] (4) During the additive manufacturing process, the intelligent control system can preset the substrate temperature range according to different additive manufacturing process methods (laser cladding, welding, thermal spraying, etc.). The intelligent control system intelligently adjusts the substrate temperature during the additive manufacturing process according to the preset temperature with an accuracy of ±10°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the three-dimensional structure of the base device of the real-time temperature control system of the present invention.

[0030] Figure 2 Schematic diagram of the arrangement of heating slots in the base body.

[0031] Figure 3 Schematic diagram of the arrangement of cooling channels in the base body.

[0032] Figure 4 Schematic diagram of the arrangement of temperature sensors embedded in the base plate.

[0033] Figure 5 This is a connection diagram of the temperature sensor embedded in the base plate.

[0034] Figure 6 A schematic diagram of the fixture.

[0035] Figure 7 for Figure 6 Bottom view of the fixture.

[0036] Figure 8 for Figure 6 Top view of the fixture.

[0037] Fig. 9 Schematic diagram of the base equipment module of the control system.

[0038] Fig.10 This is the macroscopic morphology of the high aluminum bronze coating prepared by thermal spraying technology in Example 2.

[0039] Fig.11 This is the macroscopic morphology of the high entropy alloy forming layer prepared by laser cladding forming technology in Example 3.

[0040] The markings in the above drawings are as follows: base body 1, base plate 2, heating tank 3, cooling tube 4, temperature sensor 5, clamp 6. DETAILED DESCRIPTION

[0041] (Example 1)

[0042] See Figures 1 to 10The intelligent real-time temperature control system for the additive remanufacturing deposition process of this embodiment includes a base device, a temperature sensor 5, a fixture 6 and a temperature control platform. The base device includes a base body 1 and a base plate 2, and the base plate 2 is fixed above the base body 1. A heating tank 3 and a cooling pipe 4 are set in the base body 1; the temperature sensor 5 is embedded in the base plate 2.

[0043] The plane where the heating groove 3 is located and the plane where the cooling pipe 4 is located are parallel to the base plate 2; the plane where the heating groove 3 is located is closer to the base plate 2 than the plane where the cooling pipe 4 is located.

[0044] The heating grooves 3 are arranged in a continuous "bow" shape in the base body 1, and resistance wires are arranged in the heating grooves 3. In this embodiment, the resistance wires are arranged in a Z shape in the heating grooves 3. The heating temperature range of the resistance wires is 0 to 1400°C.

[0045] The laminar cooling pipe 4 is arranged in a continuous "bow" shape in the base body 1. One end of the cooling pipe 4 is a water inlet, and the other end is a water outlet. The water inlet is connected to a running water faucet, and the water outlet is drained to a recycling bucket. The valve on the cooling pipe 4 is an electric automatic temperature control valve, which adjusts the amount of circulating water in the cooling pipe.

[0046] The temperature sensor 5 is a B-type thermocouple with a temperature range of 0 to 1800°C, which is used to monitor the substrate temperature. The temperature sensors 5 are evenly arranged on the base plate 2, and the temperature sensors 5 are set at the four corners, edges and center of the base plate 2. The signals of all temperature sensors are transmitted to the temperature control platform.

[0047] The clamp 6 is assembled on the base device, and a plurality of screw holes are provided on the clamp 6. The clamp 6 can freely move and clamp the base according to the size of the base, and fix the base by studs so that the base is parallel and close to the base device and contacts the temperature sensor 5 embedded in the base plate 2.

[0048] The temperature control platform includes a temperature control unit, a microprocessor, a mobile terminal, an electric automatic temperature control valve and a self-holding pulse solenoid valve. The temperature control unit is connected to the self-holding pulse solenoid valve and the electric automatic temperature control valve, and is used to control the opening, closing and size adjustment of the resistance wire and cooling water according to the temperature set by the substrate; the self-holding pulse solenoid valve is used to control the temperature of the resistance wire.

[0049] The microprocessor is connected to the temperature control unit by signal, and the microprocessor includes a data acquisition module, a data analysis module and a communication module. The data acquisition module is used to collect the temperature parameters of the substrate; the data analysis module is used to compare the collected temperature with the set value of the substrate temperature in the additive remanufacturing process to obtain the temperature value that needs to be increased or decreased; the communication module is used to send the obtained temperature value that needs to be increased or decreased to the temperature control unit as a reference value. The microprocessor is connected to a terminal for displaying the set temperature by wire or wireless, such as a mobile terminal, which can be selected from a mobile phone, a tablet computer, a laptop computer, etc.

[0050] Using the above control system, the real-time temperature control method in the additive manufacturing deposition process includes the following steps:

[0051] S1: Fix the substrate to be additively manufactured above the base plate 2 by means of a clamp 6 , and the substrate is in contact with the temperature sensor 5 .

[0052] S2: The data acquisition module of the microprocessor of the temperature control platform collects the temperature parameters of the additive remanufacturing substrate; the data analysis module receives the collected temperature parameters, compares them with the temperature range values ​​set by the mobile terminal, and obtains the temperature value that needs to be increased or decreased. The mobile terminal can display the temperature parameters; the communication module sends the obtained temperature value that needs to be increased or decreased to the temperature control unit as a reference.

[0053] S3: When the temperature needs to be increased during the substrate preheating stage, the temperature control unit transmits a signal to the self-holding pulse solenoid valve to start the resistance wire heating to reach the set temperature value to achieve substrate preheating.

[0054] S4: When the substrate needs to be cooled down, the temperature control unit sends a signal to the electric automatic temperature control valve, which intelligently adjusts the cooling water flow rate to achieve a refrigeration cycle, lower the substrate temperature, and maintain the substrate temperature in the additive remanufacturing process within the set substrate temperature range to achieve cooling of the substrate.

[0055] During the additive remanufacturing process, the intelligent control system can preset the substrate temperature range according to different additive remanufacturing process methods (laser cladding, welding forming, thermal spray forming, etc.). The intelligent control system intelligently adjusts the substrate temperature during the additive remanufacturing process according to the preset temperature with an accuracy of ±10°C.

[0056] (Example 2)

[0057] The present embodiment is used to prepare a high-aluminum bronze coating for volume damage repair, with reference to a high-aluminum bronze coating for volume damage repair and a preparation method thereof disclosed in Chinese patent document CN104962776A. The difference from the preparation method of the patent is that the present embodiment adopts the intelligent real-time temperature control system and the control method of the above-mentioned additive remanufacturing deposition process to control the substrate temperature within 100°C~205°C, replacing the measuring temperature and stopping the spraying in the high-aluminum bronze coating for volume damage repair and a preparation method thereof disclosed in Chinese patent document CN104962776A to reduce the substrate temperature during the spraying process.

[0058] The high aluminum bronze coating for volume damage repair prepared in this embodiment is as follows Fig.10 Compared with the 3 mm coating prepared in the Chinese patent document CN104962776A, the coating thickness prepared in this embodiment reaches 8 mm, realizing the additive remanufacturing process of thermal spraying, and since there is no need to stop spraying and wait for cooling, the spraying time is greatly shortened, the generation of cracks in the molding structure during the deposition process is suppressed, the production cost is reduced, and the production efficiency is improved.

[0059] (Example 3)

[0060] This embodiment adopts laser cladding forming technology to prepare high entropy alloy forming structure and forming layer.

[0061] Laser cladding forming technology was used to prepare high entropy alloy forming structures and forming layers. In order to reduce the influence of oxidation during the forming process, continuously flowing Ar gas (flow rate of 15 L / min) was used as the protective gas. At the same time, in order to reduce residual stress, before the deposition forming began, the intelligent real-time temperature control system and control method of the additive manufacturing deposition process were used to control the substrate temperature at about 300°C during the forming process to reduce the temperature gradient between the forming structure (layer) and the substrate.

[0062] For the Al0.4CoCu0.6NiSi0.2 high entropy alloy single-layer single-pass forming layer, the laser spot is a large spot with a diameter of 4.5 mm, the powder feeding rate is 25 g / min, the laser power is 2600 W, and the scanning speed range is determined to be 6~15 mm / s.

[0063] The shaped layer prepared is as follows Fig.11 ,Depend on Fig.11 It can be seen that the macroscopic morphology of the formed structure surface is good, with few cracks, the heights of the two ends are basically consistent with the middle section, and even the two ends are higher than the middle, and the average geometric size is 80X14 mm.

Claims

1. An intelligent real-time temperature control system for additive manufacturing deposition process, Features: The invention comprises a base device, a temperature sensor (5), a fixture (6) and a temperature control platform; the base device comprises a base body (1) and a base plate (2), wherein the base plate (2) is fixed on the top of the base body (1); a heating groove (3) and a cooling pipe (4) are arranged in the base body (1), and the plane where the heating groove (3) is located is closer to the base plate (2) than the plane where the cooling pipe (4) is located; the temperature sensor (5) is embedded in the base plate (2) to collect the temperature parameters of the additively manufactured base; a resistance wire is arranged in the heating groove (3); one end of the cooling pipe (4) is a water inlet and the other end is a water outlet, the water inlet is connected to a running water faucet, and the water outlet is used for drainage; The temperature control platform comprises a temperature control unit, a microprocessor, a mobile terminal, an electric automatic temperature control valve and a self-holding pulse solenoid valve; the temperature control unit is connected to the self-holding pulse solenoid valve and the electric automatic temperature control valve, the self-holding pulse solenoid valve controls the temperature of the regulating resistance wire, and the electric automatic temperature control valve is installed on the cooling pipe (4).

2. The intelligent real-time temperature control system for the additive manufacturing deposition process according to claim 1, Features: The heating grooves (3) are arranged in a continuous "bow" shape inside the base body (1), and the resistance wires inside the heating grooves (3) are arranged in a Z shape.

3. The intelligent real-time temperature control system for the additive manufacturing deposition process according to claim 1, Features: The temperature sensors (5) are evenly arranged on the base plate (2), and the temperature sensors (5) are arranged at the four corners, the edge and the center of the base plate (2); the signals of all the temperature sensors (5) are transmitted to the temperature control platform.

4. The intelligent real-time temperature control system for the additive manufacturing deposition process according to claim 1, Features: The microprocessor of the temperature control platform is connected to the temperature control unit by signal, and the microprocessor includes a data acquisition module, a data analysis module and a communication module; the data acquisition module acquires the temperature parameters of the substrate; the data analysis module compares the acquired temperature with the set value of the substrate temperature in the additive remanufacturing technology process to obtain the temperature value that needs to be increased or decreased; the communication module sends the obtained temperature value that needs to be increased or decreased to the temperature control unit; the microprocessor is connected to a terminal for displaying the set temperature by wire or wirelessly.

5. A control method of the intelligent real-time temperature control system for the additive manufacturing deposition process as claimed in claim 1, The following steps are involved: S1: Fixing the substrate to be remanufactured above the base plate (2) by means of a clamp (6), so that the substrate is in contact with the temperature sensor (5); S2: The data acquisition module of the microprocessor of the temperature control platform collects the temperature parameters of the additive manufacturing substrate; the data analysis module receives the collected temperature parameters, compares them with the temperature range values ​​set by the mobile terminal, and obtains the temperature value that needs to be increased or decreased, and the mobile terminal can display the temperature parameters; the communication module sends the obtained temperature value that needs to be increased or decreased to the temperature control unit as a reference; S3: When the temperature needs to be increased during the preheating stage of the substrate, the temperature control unit transmits a signal to the self-holding pulse solenoid valve to start the resistance wire heating to reach the set temperature value to achieve preheating of the substrate; S4: When the substrate needs to be cooled down, the temperature control unit sends a signal to the electric automatic temperature control valve, which intelligently adjusts the cooling water flow rate to achieve a refrigeration cycle, lower the substrate temperature, and maintain the substrate temperature in the additive remanufacturing process within the set substrate temperature range to achieve cooling of the substrate.

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