Shape-controllable metal local heat treatment method and device

Abstract

The invention discloses a shape-controllable metal local heat treatment method and device, and belongs to the technical field of metal heat treatment. According to the method, a patterned conductive covering film is arranged on an upper substrate, a driving electric field is applied, heat conduction liquid forms a heat conduction liquid column consistent with a pattern, heat flow is guided to be gathered in metal, and precise local heat treatment is achieved. The system comprises an upper substrate movement module, a lower substrate movement module, a temperature monitoring module, a processing monitoring module and the like, can realize flexible control of the shape of a heat treatment area, is suitable for annealing, tempering and other processes, and has the advantages of accurate heat affected zone, small deformation, low energy consumption and the like.

Description

Technical Field

[0001] This invention relates to the field of heat treatment technology for metallic materials, and particularly to a shape-controllable local heat treatment method and apparatus for metals. The method involves designing a patterned conductive coating area on the side of the upper substrate facing the metal part, applying a driving electric field to drive a heat-conducting liquid to form a heat-conducting liquid column of a specific shape, thereby achieving precise local heat treatment of a specific area of ​​the metal part. This method is applicable to annealing, tempering, and other processes for specific metals, aiming to achieve an effective combination of metal strength and stiffness. Background Technology

[0002] Traditional metal heat treatment processes (such as annealing and tempering) typically involve heating the entire metal part. This method has several inherent drawbacks: First, the "one-size-fits-all" approach of traditional metal heat treatment makes it difficult to create performance gradients on a single part, failing to meet the complex requirements of modern precision devices (such as aerospace and medical devices) that demand different hardness and toughness in different areas. Second, traditional metal heat treatment processes have a high risk of deformation. During the overall heating and cooling of the metal, thermal stress and phase transformation stress can easily lead to distortion, warping, and other deformations in thin-walled and complex-structured metal parts, resulting in low yield rates. Third, traditional metal heat treatment methods have long production cycles and high energy consumption. Heating the entire metal part and furnace cavity requires a significant amount of time and energy, resulting in long equipment downtime and low production efficiency. Therefore, there is an urgent need in this field for a novel localized heat treatment technology that can achieve controllable shape, uniform heat input, and precise definition of the heat-affected zone. Summary of the Invention

[0003] The core of this invention lies in the following: a patterned conductive coating is provided on the upper substrate facing the metal part; a thermally conductive liquid column is formed in a preset patterned area between the heated metal part and the upper substrate using a driving electric field. This thermally conductive liquid column is essentially a shape-controllable superconducting heat channel that can drastically alter the heat flow distribution within the metal part. Under thermodynamic drive, heat strongly converges from other areas of the metal part and flows through this channel, causing the target area to experience a heat flow density far higher than other areas, thereby establishing a dynamically stable high-temperature field within it and achieving precise local phase change heat treatment.

[0004] To achieve the above objective, the method specifically involves providing a lower substrate (i.e., a metal part) and an upper substrate. The upper substrate has a patterned conductive coating on the side facing the metal part, and the patterned conductive coating area has the same shape as a preset heat treatment area.

[0005] Thermally conductive liquid is dropped onto the area to be processed of the metal part and the patterned conductive film area of ​​the upper substrate facing the metal part; the relative positions of the two are adjusted to form a narrow gap; a high-voltage power supply is connected to the metal part and the patterned conductive film surface of the upper substrate facing the metal part, respectively. After power is applied, the driving electric field is effectively established only between the patterned conductive film area and the metal part, driving the thermally conductive liquid at this location to form a stable thermally conductive liquid column connecting the upper and lower substrates through electrowetting effect.

[0006] The heating platform beneath the metal component is activated for heating. Heat is conducted within the metal component and, guided by the superconducting heat channels formed by the heat-conducting liquid columns, the heat flow strongly converges in the metal region corresponding to those channels. This results in a significantly higher heat flux density in that region compared to other regions, thereby establishing a dynamically stable localized high-temperature field and achieving precise localized heat treatment.

[0007] By changing different patterned conductive coating areas, the shape of the heat-conducting liquid column and the heat treatment area can be altered. After processing, the power is cut off, the heat-conducting liquid column disappears, and heat input stops. Furthermore, the method applies a driving electric field to the upper and lower substrates. Since only the patterned conductive coating area of ​​the upper substrate is conductive, the driving electric field is only applied to the pre-prepared patterned conductive coating area on the lower surface of the upper substrate. This allows for the real-time and flexible formation of heat-conducting liquid columns of arbitrary shapes, from simple to complex, thereby creating precisely corresponding heat treatment areas on the metal part.

[0008] According to another aspect of the present invention, a shape-controllable local heat treatment apparatus for implementing the above-described method is provided. The apparatus mainly includes an overall support module, a temperature monitoring module, a processing monitoring module, an upper substrate motion module, and a lower substrate motion module. These modules work together to ensure the precise formation of narrow gaps, the uniform and stable driving electric field, the accurate shape of the heat-conducting liquid column, and the monitorability and controllability of the process in the above-described method.

[0009] The overall support module is mainly composed of a steel frame, providing a foundation for the installation and load-bearing of each module; The temperature monitoring module includes a thermal imager and its driving mechanism, which is used to monitor the surface temperature distribution of the metal parts in real time, so as to compare and adjust with the preset pattern and ensure the accuracy and consistency of the heat treatment effect. The processing monitoring module includes a high-speed camera and its drive mechanism, used to move along the X-axis and observe the formation process and morphology of the heat-conducting liquid column within the narrow gap in real time. This module directly monitors the core steps of the method, providing visual verification and diagnostic basis for process reliability. The upper substrate motion module includes an integrated XYZ three-axis motion mechanism for precise positioning of the upper substrate in three-dimensional space. Specifically, the X and Y axis moving devices achieve in-plane alignment between the upper substrate and the metal component, while the Z-axis moving device controls the distance between them. The Z-axis moving device has a suction cup at its end for adsorbing and directly driving the upper substrate along the Z-axis, thus precisely controlling the distance between the upper substrate and the metal component. This is a prerequisite for uniformly driving the heat-conducting liquid column with the driving electric field and for stable heat transfer. The lower substrate motion module includes a lower substrate Y-axis moving device and a lower substrate Z-axis moving device. The main function of this module is to support and position the metal component (i.e., the lower substrate). Through the coordinated adjustment of the Y and Z axes, it ensures that the metal component can be accurately moved to a predetermined position relative to the upper substrate, forming a narrow gap that meets the requirements together with the upper substrate. This forms the basis for the subsequent electric field-driven formation of the heat-conducting liquid column. This module integrates a heating stage, which serves as the main heat source of the device. Its heat is conducted through the metal component itself and, guided by the superconducting heat channels formed by the specifically shaped heat-conducting liquid column, converges in the target area to achieve precise local heat treatment.

[0010] Furthermore, the workflow of the device is adapted to the steps of the method: The upper substrate motion module and the lower substrate motion module work together to complete the loading, positioning, and precise setting of narrow gaps for the metal parts. The electric field application module is connected to the upper substrate and the metal part respectively, so that it can generate a corresponding driving electric field signal and apply it to the electrode according to the heat treatment pattern information of the patterned conductive film on the side of the upper substrate facing the metal part, so as to perform thermal conductive liquid column forming. After the heating platform is started, it heats the metal part as a whole. Under the guidance of the superconducting heat channel formed by the heat-conducting liquid column, the heat flow converges in the target area of ​​the metal part, realizing local heating and heat treatment in that area. The temperature monitoring module and the processing monitoring module work in real time during the processing to acquire temperature and visual information, respectively.

[0011] Furthermore, the method and apparatus of the present invention include the following preferred technical solutions: The thermally conductive liquid is a liquid metal with high thermal conductivity, good electrowetting properties and thermal stability, including but not limited to gallium-indium alloys; The voltage range of the driving electric field is 5-10 kV.

[0012] When performing localized high-temperature annealing, the upper substrate is made of high thermal conductivity and high-temperature resistant quartz glass, with a tin-doped gallium oxide coating on its inner side; when performing localized low-temperature tempering, the upper substrate can be made of ordinary glass, with an indium tin oxide coating on its inner side.

[0013] After the heat treatment is completed, the driving electric field is removed or changed, and the shape of the heat-conducting liquid column changes or disappears accordingly, and the heat input stops.

[0014] According to another aspect of the present invention, a shape-controllable local heat treatment method for metal is provided, implemented using the aforementioned apparatus, comprising the following steps: S1. A metal component and an upper substrate are provided, wherein the upper substrate has a patterned conductive coating on the side facing the metal component; S2. A thermally conductive liquid is dropped between the area to be processed of the metal part and the patterned conductive coating area of ​​the upper substrate facing the metal part. S3. Adjust the relative position and orientation of the upper substrate and the metal part to form a narrow gap filled with the heat-conducting liquid between them. S4. Apply a driving electric field corresponding to the pattern to the narrow gap filled with the thermally conductive liquid, so that the thermally conductive liquid forms a thermally conductive liquid column with the same shape as the pattern under the action of the driving electric field; S5. The metal part is heated from the bottom to conduct heat through the metal part; under the guidance of the superconducting heat channel formed by the heat-conducting liquid column, the heat flow converges in the area to be treated to form a local high temperature field, thereby achieving local heat treatment in the area. S6. After the heat treatment is completed, the driving electric field is removed.

[0015] Overall, compared with the prior art, the present invention has the following significant advantages: 1. The present invention achieves controllable shape of the heat treatment area by replacing the pre-patterned upper substrate; 2. This invention guides the heat flow to redistribute within the metal and converge in the target area through a heat-conducting liquid column with controllable shape, thereby strictly limiting the heat-affected zone within the target shape and avoiding overall thermal stress. It is particularly suitable for processing thin-walled, precision and complex parts, significantly reducing the risk of deformation and improving the yield rate. 3. Unlike point heat sources such as laser scanning, the present invention uses a heat-conducting liquid column as a surface heat source, which can provide uniform and stable heat input, avoid local overheating and thermal shock, and result in a uniform tissue with fewer defects after treatment; 4. This invention eliminates the need for an overall heating furnace and complex scanning devices, resulting in rapid heating and cooling, fast production pace, short equipment downtime, and low energy consumption. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating steps 1 to 5 of a shape-controllable local heat treatment method for metals. Figure 2This is a schematic diagram of the transformation process of the heat-conducting liquid column from the initial state (a) to the target shape (d) under the action of the driving electric field in an embodiment of the present invention, which intuitively shows the controllable change of the shape of the heat-conducting liquid column as the driving electric field is turned on and off; Figure 3 This is a schematic diagram of the shape-controllable local heat treatment device for metal according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the upper substrate motion module structure according to an embodiment of the present invention; Figure 4-1 This is a schematic diagram of the Z-axis moving device of the upper substrate in an embodiment of the present invention; Figure 5 This is a schematic diagram of the substrate motion module structure according to an embodiment of the present invention; Figure 5-1 This is a schematic diagram of the substrate Z-axis moving device according to an embodiment of the present invention; Figure 5-2 This is a schematic diagram of the substrate Y-axis moving device according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the temperature monitoring module structure according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the processing monitoring module structure according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the electric field application module structure of the present invention.

[0017] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein 1-temperature monitoring module, 11-thermal imager, 2-upper substrate motion module, 23-upper substrate Z-axis moving device, 231-upper substrate, 232-suction cup, 3-integral support module, 4-lower substrate motion module, 41-lower substrate Z-axis moving device, 411-heating stage, 42-lower substrate Y-axis moving device, 421-metal part, 5-processing monitoring module, 51-high-speed camera, 61-unpatterned conductive coating area of ​​upper substrate, 62-patterned conductive coating area of ​​upper substrate, 71-high voltage power supply. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the implementation process of the method of this invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0019] The following will, in conjunction with the accompanying drawings, illustrate in detail how the shape-controllable local heat treatment method for metals described in this invention is implemented through a specific embodiment. This embodiment employs... Figure 3The illustrated shape-controllable local heat treatment apparatus for metal is used as an implementation tool to demonstrate the complete process flow of the method.

[0020] First, the device structure used in this embodiment is briefly introduced. The device mainly includes: a lower substrate motion module 4 for supporting and positioning the metal part 421 (i.e., the lower substrate) and providing a heat source; an upper substrate motion module 2 for achieving precise three-dimensional positioning of the upper substrate 231; a temperature monitoring module 1 for real-time monitoring of the surface temperature field of the metal part 421; a processing monitoring module 5 for real-time observation of the heat-conducting liquid column formation process; an electric field application module for generating an electric field corresponding to a preset pattern; and an overall support module 3 providing the mounting foundation for each module. The functional design of each module is fundamentally aimed at ensuring the accurate and reliable execution of the method steps.

[0021] Next, the entire process of executing the method based on this device will be described in detail: S1. Connect the output terminal of the high voltage power supply 71 to the patterned conductive coating on the side of the upper substrate 231 facing the metal part 421 and the metal part 421 respectively, thereby establishing a circuit that can apply a driving electric field between the upper substrate 231 and the metal part 421.

[0022] S2. A metal part 421 to be processed is provided. A piece of quartz glass is selected as the upper substrate 231, and its lower surface is coated with a tin-doped gallium oxide transparent conductive film. In order to achieve shape control of the heat treatment area, the conductive film needs to be pre-patterned and processed to form a specific conductive pattern corresponding to the preset heat treatment pattern. For example, for the strip-shaped heat treatment area in this example, a matching strip-shaped conductive area can be prepared on the conductive film through photolithography and etching processes, while the surrounding area is an insulating non-conductive area.

[0023] like Figure 5 As shown, the metal part 421 is placed on the heating stage 411. Gallium-indium alloy is selected as the heat transfer fluid. To ensure the stability of the heat transfer fluid column at high temperatures and to prevent splashing, the heat treatment process is preferably carried out in an inert atmosphere or vacuum environment. If necessary, protective barriers can be set around the metal part 421. Using a dropper, an appropriate amount of gallium-indium alloy droplets are precisely applied above the intended strip area of ​​the metal part 421 and the patterned conductive coating area on the side of the upper substrate 231 facing the metal part 421.

[0024] As an extension of the present invention, for heat treatment processes at higher temperatures, the heat-conducting liquid can be replaced with other liquid media compatible with the high-temperature environment, such as high-temperature molten salts of specific components or high-melting-point liquid metal alloys, and a corresponding atmosphere protection or vacuum environment can be configured.

[0025] S3, such as Figure 4 , Figure 5As shown, the upper substrate 231 is adjusted in spatial orientation by the upper substrate motion module 2 so that its lower surface is strictly parallel to the upper surface of the metal part 421. Subsequently, the upper substrate 231 is slowly lowered to form a narrow gap of uniform thickness between the lower surface of the upper substrate 231 and the upper surface of the metal part 421. The thickness of the narrow gap is 5-10 mm. This thickness range is set to effectively confine the pre-dropped heat-conducting liquid within the gap and to provide a basis for the uniform application of the driving electric field and the stable formation of the heat-conducting liquid column. It should be understood that the specific thickness of the narrow gap can be adjusted according to the actual process conditions. For example, through the precise control of the upper substrate motion module 2, the gap can be adjusted and maintained at different values ​​such as 6 mm, 8 mm, or 9.5 mm.

[0026] S4, such as Figure 2 As shown, the positive and negative terminals of the high-voltage power supply 71 are connected to the patterned conductive coating on the side of the upper substrate 231 facing the metal part 421 and the lower metal part 421, respectively. The power is turned on, and a driving electric field (approximately 5kV high voltage is applied) is applied to the narrow gap. Under the action of the driving electric field, the gallium-indium alloy liquid within the narrow gap undergoes an instantaneous electrowetting effect, significantly reducing its contact angle with the upper and lower surfaces, causing the liquid to rapidly spread and redistribute. Within seconds, the liquid self-organizes to form a stable, vertically connected thermally conductive liquid column that perfectly matches the patterned conductive pattern on the side of the upper substrate 231 facing the metal part 421. This thermally conductive liquid column is essentially a stable, shape-controllable liquid thermally conductive liquid column connecting the metal part 421 and the upper substrate 231.

[0027] S5. Activate the heating stage 411 located below the metal part 421 to heat the entire metal part 421 to the process temperature (e.g., approximately 900°C for titanium alloys). Heat is conducted within the metal part 421, resulting in distinctly different thermal effects due to differences in the heat transfer paths: In non-target areas, the narrow gap between the metal part 421 and the upper substrate 231 creates high thermal resistance, effectively blocking heat and maintaining a relatively uniform reference temperature in the area.

[0028] In the target region, the superconducting heat channels formed by the heat-conducting liquid columns provide a convergence and conduction path for heat flow with extremely low thermal resistance. This causes heat from the bottom of the metal part 421 and other parts to be strongly guided and continuously concentrated in this region, resulting in a sharp increase in its heat flux density. Under this dynamic equilibrium, the metal in the target region stably forms and maintains a local high-temperature field due to the continuous and dense heat flow input, thereby achieving precise local heat treatment.

[0029] During this process, the thermal imager 11 of the temperature monitoring module 1 and the high-speed camera 51 of the processing monitoring module 5 monitor the temperature field and the morphology of the heat-conducting liquid column in real time to ensure the accuracy and stability of the process. Maintaining this heating state for a predetermined time completes the local heat treatment.

[0030] S6, such as Figure 2 As shown, after the predetermined heat preservation time is reached, the high-voltage power supply 71 is first cut off by the control device, and the driving electric field is removed. After the driving electric field disappears, the electrowetting force that maintains the shape of the heat-conducting liquid column also disappears. Under the action of its own surface tension, the gallium-indium alloy heat-conducting liquid column instantly becomes unstable and contracts, breaking the connection with the upper substrate 231 and the metal part 421, and the efficient heat transfer channel is physically cut off. The heating process of the target area immediately stops. Subsequently, the heating stage 411 is turned off, and the upper substrate motion module 2 lifts the upper substrate 231, separating it from the metal part 421. Finally, the processed metal part 421 is removed, and the device is ready for the next operation.

[0031] In summary, this embodiment fully demonstrates how the method of the present invention can be executed through the aforementioned system device. The key lies in defining the area of ​​application of the driving electric field by pre-setting a pattern on the patterned conductive coating, and then using the driving electric field to control the formation of a thermally conductive liquid column of the corresponding shape. This thermally conductive liquid column acts as a superconducting heat channel, guiding heat to converge directionally in the target area, thereby achieving controllable shape of the local heat treatment area of ​​the metal part. Those skilled in the art will understand that the above embodiments are only for clearly illustrating the principles of the present invention. Equivalent changes and modifications made to process parameters (such as materials, temperature, driving electric field strength, and pattern) and the specific mechanical implementation of modules without departing from the essence of the present invention should be included within the scope of protection of the present invention.

Claims

1. A shape-controllable local heat treatment method for metal, characterized in that, Includes the following steps: S1. A metal component and an upper substrate are provided, wherein the upper substrate has a patterned conductive coating on the side facing the metal component; S2. A thermally conductive liquid is dropped between the area to be processed of the metal part and the patterned conductive coating area of ​​the upper substrate facing the metal part. S3. Adjust the relative position and orientation of the upper substrate and the metal part to form a narrow gap filled with the heat-conducting liquid between them. S4. Apply a driving electric field corresponding to the pattern to the narrow gap filled with the thermally conductive liquid, so that the thermally conductive liquid forms a thermally conductive liquid column with the same shape as the pattern under the action of the driving electric field; S5. The metal part is heated from the bottom to conduct heat through the metal part; under the guidance of the superconducting heat channel formed by the heat-conducting liquid column, the heat flow converges in the area to be treated to form a local high temperature field, thereby achieving local heat treatment in the area. S6. After the heat treatment is completed, the driving electric field is removed.

2. The method according to claim 1, characterized in that, The thermally conductive liquid is a liquid metal with high thermal conductivity, good electrowetting properties and thermal stability, including but not limited to gallium-indium alloys.

3. The method according to claim 1, characterized in that, The voltage range of the driving electric field is 5-10 kV.

4. The method according to claim 1, characterized in that, The thickness of the narrow gap filled with the thermally conductive liquid is 5-10 mm.

5. The method according to claim 1, characterized in that, In step S5, a thermal imager is used to monitor the temperature field in real time, and a high-speed camera is used to monitor the morphology of the heat-conducting liquid column in real time.

6. A shape-controllable local heat treatment apparatus for carrying out the method according to any one of claims 1 to 5, characterized in that, include: The lower substrate motion module is used to support and position the metal parts, and integrates a heating stage to heat the metal parts; The upper substrate motion module is used to drive the upper substrate with the patterned conductive coating to perform three-dimensional spatial positioning, so that the upper substrate and the metal part form the narrow gap filled with the thermally conductive liquid. An electric field application module is used to generate a driving electric field corresponding to a preset heat treatment pattern and apply it to the narrow gap filled with the thermally conductive liquid; Temperature monitoring module, including a thermal imager, is used to monitor the surface temperature distribution of metal parts in real time; The processing monitoring module includes a high-speed camera for real-time observation of the formation process and morphology of the heat-conducting liquid column within the narrow gap; And the overall support module, which provides the foundation for the installation and load-bearing of the above modules.

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