A heat treatment process for reducing quenching deformation cracking of die casting die steel

Abstract

The application discloses a heat treatment process for reducing quenching deformation cracking of die casting die steel, improves the heat treatment process, and has high operability, does not increase process cost, and is simple in process; the process controls the cooling gas pressure and fan rotating speed in sections, realizes precooling-weak cooling-strong cooling in each stage of die quenching, and controls the deformation and even cracking of the weak part of the die caused by improper cooling. The process controls the cooling gas pressure and fan rotating speed in sections, ensures the uniform distribution of the hardness of the die in heat treatment, and the non-uniformity of the hardness of the die is less than 1.5 HRC; the impact energy is increased by 80-100 J compared with the conventional heat treatment process. After 1000 times of thermal fatigue cycle, the main crack length is reduced by 250-260 mu m, and the crack width is reduced by 7-24 mu m compared with the conventional heat treatment process, and the process has good thermal fatigue performance.

Description

Technical Field

[0001] This invention relates to the field of heat treatment technology for materials, specifically to a heat treatment process for reducing quenching deformation and cracking in die-casting mold steel. Background Technology

[0002] Molds are among the most important process equipment in the manufacturing industry, and the level of mold manufacturing is a significant indicator of a country's manufacturing level. Die-casting mold steel is the primary tool for forming liquid metal. Due to the influence of product structure, mold shapes are often very complex, inevitably containing many thin walls, sharp corners, and especially stepped thickness differences. These factors can cause some deformation or even cracking during mold quenching. Excessive deformation or cracking of the mold directly increases mold manufacturing costs and significantly impacts product delivery time.

[0003] H13 steel is currently the most widely used and representative hot work die steel. As is well known, hot fatigue cracks tend to propagate at grain boundaries. At present, improving the hot fatigue performance of hot work die steel is mainly achieved by adding alloying elements to enable solid solution strengthening and second-phase strengthening, thereby inhibiting the initiation and propagation of hot fatigue cracks.

[0004] Existing technical literature, patent number: 201010224086.8, entitled "Vacuum Isothermal Heat Treatment Process for Large Die-casting Molds," discloses a vacuum isothermal heat treatment process for large die-casting molds that can achieve ideal microstructure and minimal deformation. However, its technical problems include the introduction of 9 bar nitrogen gas at the start of quenching and cooling. For large, especially complex, die-casting molds, this rapid cooling generates significant thermal and structural stresses, posing a risk of deformation or cracking. Furthermore, the higher the pressure, the greater the temperature difference acting on different structural surfaces of the mold, resulting in greater thermal and structural stresses.

[0005] To address the aforementioned shortcomings, this application develops a low-cost, simple, and easy-to-implement heat treatment process to reduce heat treatment deformation or cracking of H13 type die-casting mold steel. Summary of the Invention

[0006] To overcome the above-mentioned defects, the purpose of this invention is to provide a heat treatment process that reduces quenching deformation and cracking of die casting mold steel. The heat treatment process is improved and controlled, which is highly operable, does not increase process costs, and is simple. The process of this invention achieves pre-cooling, weak cooling and strong cooling of each stage of mold quenching by segmenting the cooling gas pressure and fan speed, so as to control the deformation or even cracking of weak parts of the mold caused by improper cooling.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A heat treatment process to reduce quenching deformation and cracking in die-casting mold steel includes the following steps:

[0009] (1) Place the prepared mold in a vacuum high-pressure gas quenching furnace, heat and hold it using conventional quenching process to allow the mold to fully austenitize;

[0010] (2) After the mold has been fully austenitized in step (1), 3 bar of high-purity nitrogen is introduced into the mold in slow inflation mode at an inflation rate of 0.15 bar / second. The cooling fan is started and the speed is set to 1800 rpm. The mold is kept cooled for 1 minute.

[0011] (3) After the mold in step (2) has been cooled and held for 1 minute, high-purity nitrogen gas is introduced in slow inflation mode and pressurized to 6 bar. The inflation rate is 0.30 bar / second. The speed of the cooling fan is increased to 2200 rpm and kept cooled for 1 minute.

[0012] (4) After cooling and heat preservation in step (3), the mold is pressurized to 9 bar by high-purity nitrogen in slow inflation mode. The inflation rate is 0.45 bar / second. The speed of the cooling fan is increased to 2600 rpm and kept cooling for 1 minute.

[0013] (5) After step (4) is completed, high-purity nitrogen gas is injected into the vacuum high-pressure gas quenching furnace in a fast-injection mode and pressurized to 12-14 bar. The gas injection rate is 0.80 bar / second. The cooling fan speed is increased to 3000 rpm. When the mold surface temperature drops to 450°C, the nitrogen pressure and fan speed are adjusted according to the mold core temperature until the temperature difference between the mold surface and the core is less than 100°C. Then, high-purity nitrogen gas pressure of 12-14 bar is injected into the vacuum high-pressure gas quenching furnace, and the cooling fan speed is increased to 3000 rpm. Cooling is stopped when the high-speed high-pressure cooling of the mold core temperature reaches 110°C.

[0014] Step (1) Conventional quenching process: Heat to 620℃ at 180-200℃ / hour, and after the mold core reaches 590℃, heat to 820℃ at 200℃ / hour, and after the mold core reaches 800℃, heat to 1015℃ in 30 minutes, and after the mold core reaches 1005℃, hold for 45 minutes.

[0015] Steps (2) through (5) are all cooled in the same container, with 99.99% high-purity nitrogen as the medium.

[0016] The nitrogen pressure and cooling fan speed in steps (2) to (5) are in a segmented pressurization and acceleration mode, and the cooling fan is a variable frequency cooling fan.

[0017] Step (5) When the mold surface temperature drops to 450℃, adjust the nitrogen pressure and cooling fan speed according to the mold core temperature. Specifically, the nitrogen pressure is fixed at 3 bar, the isothermal temperature is set at 450℃, with an upper deviation of +10℃ and a lower deviation of -20℃, meaning the mold surface temperature is controlled within the range of 460~430℃. When the mold surface temperature rises due to core temperature conduction, and exceeds 460℃, the fan speeds up. When the mold surface temperature drops to 430℃, the fan speeds down or even stops. If the mold surface temperature continues to drop when the fan stops, it will automatically start heating, always maintaining the mold surface temperature within the set isothermal temperature range, until the mold core temperature drops to 530℃ (450+80℃) and continues for 3~8 minutes, after which the isothermal process ends. The mold then enters the next program – charging with 12~14 bar of nitrogen and the fan at 3000 rpm.

[0018] It also includes step (6) of hot melt treatment for the hot melt crystallization reinforcement of the thin wall surface of the mold, which specifically includes the following steps:

[0019] (6.1) The mold is transferred to the laser melting chamber. The laser melting chamber is equipped with a laser melting system, an infrared temperature sensor and a powder feeding system. The powder feeding system is used to spread metal powder on the surface of the mold. The laser melting system generates a laser for thermally melting the surface of the mold. The infrared temperature sensor is used to obtain the temperature of the melting surface in real time. The laser melting system includes several laser emission points. The several laser emission points form a laser scanning heating surface to scan and ablate the surface of the mold.

[0020] (6.2) Turn on the powder feeding system to spread the metal powder on the surface of the mold. The metal powder is melted by laser and solidified on the surface of the mold until the metal powder is melted on the surface of the mold to form a cladding structure. During the heat melting process of the mold surface, the infrared temperature sensor obtains the temperature of the melting surface in real time and adjusts the laser parameters accordingly to keep the temperature of the mold melting surface within a suitable heating temperature range. The laser parameters are adjusted according to the shape of the mold melting surface. The laser parameters are based on the temperature of the melting surface and the thickness of the cladding structure, and the laser power, scanning speed and spot diameter are adjusted accordingly.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. The segmented pressurization acceleration method of this invention uses low pressure and low speed in the initial cooling stage to pre-cool the weak parts of the mold (such as sharp corners, thin walls, holes, etc.). At this time, because the cooling rate is low, the mold does not generate large thermal stress and structural stress, thus effectively avoiding deformation or even cracking of the weak parts of the mold. Subsequently, the pressure is gradually increased until the cooling air pressure reaches 12-14 bar, and the fan runs at full speed. Since the risk of deformation and cracking of the weak parts of the mold is avoided, the effective quenching cooling air pressure can be 3-5 bar higher than the original, increasing the cooling capacity of the die-casting mold core, thus achieving a more ideal hardened layer depth.

[0023] 2. The process of this invention ensures uniform hardness distribution in the mold after heat treatment by segmenting and controlling the cooling gas pressure and fan speed. Taking a mold with a diameter of 1800*960*560mm as an example, the hardness non-uniformity is less than 1.5HRC. Compared with conventional heat treatment processes, it improves the impact energy by 80-100J. After 1000 thermal fatigue cycles, the process of this invention reduces the main crack length by 250-260μm and the crack width by 7-24μm compared with conventional heat treatment processes, demonstrating excellent thermal fatigue performance.

[0024] 3. The method of the present invention also incorporates a hot-melt treatment process for hot-melt crystallization reinforcement of the thin wall surface of the mold, eliminating internal defects of the thin wall surface of the mold. Metal powder is laser-melted and solidified on the surface of the mold until the metal powder is fused onto the surface of the mold to form a cladding structure. During the hot-melt treatment of the mold surface, an infrared temperature sensor acquires the temperature of the molten surface in real time, so that the temperature of the molten surface of the mold is within a suitable preset temperature range. Through the above-mentioned hot-melt crystallization reinforcement of the thin wall surface of the mold, the warping and cracking of the thin wall surface of the mold is significantly reduced, effectively avoiding cracks, fissures, and warping deformation, improving the internal and external quality of the mold and the comprehensive mechanical properties of the mold surface, and effectively preventing deformation or even cracking of weak parts of the mold.

[0025] To more clearly illustrate the structural features and effects of the present invention, a detailed description is provided below in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description

[0026] Figure 1 Metallographic micrograph (100x) of the die-casting mold after heat treatment according to the present invention;

[0027] Figure 2 Metallographic micrograph (500x) of the die-casting mold after heat treatment according to the present invention;

[0028] Figure 3 Metallographic micrograph (1000x) of the die-casting mold after heat treatment according to the present invention;

[0029] Figure 4The graph shows the performance measurement of the die-casting mold after the heat treatment method of the present invention. Detailed Implementation

[0030] 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.

[0031] Example: See Appendix Figure 1-4 This embodiment provides a heat treatment process to reduce quenching deformation and cracking in die-casting mold steel, including the following steps:

[0032] (1) Place the prepared mold in a vacuum high-pressure gas quenching furnace, heat and hold it using conventional quenching process to allow the mold to fully austenitize;

[0033] (2) After the mold has been fully austenitized in step (1), 3 bar of high-purity nitrogen is introduced into the mold in slow inflation mode at an inflation rate of 0.15 bar / second. The cooling fan is started and the speed is set to 1800 rpm. The mold is kept cooled for 1 minute.

[0034] (3) After the mold in step (2) has been cooled and held for 1 minute, high-purity nitrogen gas is introduced in slow inflation mode and pressurized to 6 bar. The inflation rate is 0.30 bar / second. The speed of the cooling fan is increased to 2200 rpm and kept cooled for 1 minute.

[0035] (4) After cooling and heat preservation in step (3), the mold is pressurized to 9 bar by high-purity nitrogen in slow inflation mode. The inflation rate is 0.45 bar / second. The speed of the cooling fan is increased to 2600 rpm and kept cooling for 1 minute.

[0036] (5) After step (4) is completed, high-purity nitrogen gas is injected into the vacuum high-pressure gas quenching furnace in a fast-injection mode and pressurized to 12-14 bar. The gas injection rate is 0.80 bar / second. The cooling fan speed is increased to 3000 rpm. When the mold surface temperature drops to 450°C, the nitrogen pressure and fan speed are adjusted according to the mold core temperature until the temperature difference between the mold surface and the core is less than 100°C. Then, high-purity nitrogen gas pressure of 12-14 bar is injected into the vacuum high-pressure gas quenching furnace, and the cooling fan speed is increased to 3000 rpm. Cooling is stopped when the high-speed high-pressure cooling of the mold core temperature reaches 110°C.

[0037] Step (1) Conventional quenching process: Heat to 620℃ at 180-200℃ / hour, and after the mold core reaches 590℃, heat to 820℃ at 200℃ / hour, and after the mold core reaches 800℃, heat to 1015℃ in 30 minutes, and after the mold core reaches 1005℃, hold for 45 minutes.

[0038] Steps (2) through (5) are all cooled in the same container, with 99.99% high-purity nitrogen as the medium.

[0039] The nitrogen pressure and cooling fan speed in steps (2) to (5) are in a segmented pressurization and acceleration mode, and the cooling fan is a variable frequency cooling fan.

[0040] Step (5) When the mold surface temperature drops to 450℃, adjust the nitrogen pressure and cooling fan speed according to the mold core temperature. Specifically, the nitrogen pressure is fixed at 3 bar, the isothermal temperature is set at 450℃, with an upper deviation of +10℃ and a lower deviation of -20℃, meaning the mold surface temperature is controlled within the range of 460~430℃. When the mold surface temperature rises due to core temperature conduction, and exceeds 460℃, the fan speeds up. When the mold surface temperature drops to 430℃, the fan speeds down or even stops. If the mold surface temperature continues to drop when the fan stops, it will automatically start heating, always maintaining the mold surface temperature within the set isothermal temperature range, until the mold core temperature drops to 530℃ (450+80℃) and continues for 3~8 minutes, after which the isothermal process ends. The mold then enters the next program – charging with 12~14 bar of nitrogen and the fan at 3000 rpm.

[0041] Existing vacuum isothermal heat treatment processes for die-casting molds involve initial heating and holding at a certain temperature, followed by air cooling at a pressure not less than 9 Bar. When the mold surface temperature reaches 427°C, the cooling pressure is reduced to 2 Bar, and air cooling is stopped. Isothermal treatment is then performed using a convection fan. After isothermal treatment, the pressure is increased to above 6 Bar for further air cooling. Introducing nitrogen at 9 Bar at the start of quenching and cooling can cause significant thermal and structural stresses in large, especially complex, die-casting molds due to rapid cooling, posing a risk of deformation or cracking. Furthermore, higher pressure results in greater temperature differences across different structural surfaces of the mold, leading to increased thermal and structural stresses.

[0042] The present invention uses a segmented, gradual pressure increase and acceleration method to approach and pass through the proeutectoid ferrite and proeutectoid carbide regions at an appropriate cooling rate without generating pearlite structure. At this time, the temperature difference between the surfaces of each structure of the quenched die-casting mold is small, and the resulting thermal stress and structural stress have little effect, thereby avoiding mold deformation or cracking.

[0043] The isothermal process of this invention is more reliable than that of the vacuum isothermal heat treatment process for large die-casting molds. The vacuum isothermal heat treatment process for large die-casting molds, which uses a fixed-speed convection fan and 2 bar nitrogen pressure to control the mold surface temperature within a certain range, is difficult to achieve. In contrast, this invention uses a fixed nitrogen pressure of 3 bar and sets the isothermal temperature at 450°C, with an upper deviation of +10°C and a lower deviation of -20°C, meaning the mold surface temperature is controlled within the range of 460–430°C. When the mold surface temperature rises due to core temperature conduction, and exceeds 460°C, the fan speeds up. When the mold surface temperature drops to 430°C, the fan speeds down or even stops. If the mold surface temperature continues to drop after stopping, it will automatically restart heating, maintaining the mold surface temperature within the set isothermal temperature range until the mold core cools to 530°C (450 + 80°C) and remains there for 3–8 minutes, at which point the isothermal process ends. The mold enters the next stage of the program - nitrogen gas is introduced at 12-14 bar, and the blower operates at 3000 rpm.

[0044] In comparison, the cooling nitrogen pressure that crosses the coarse bainite region after isothermal treatment is 6-8 bar higher. For die casting molds, especially large die casting molds, the probability of obtaining non-martensitic structure is lower, and the hardened layer is deeper, the impact toughness is higher, and the mold's resistance to thermal fatigue is improved.

[0045] The segmented pressurization acceleration method of this invention uses low pressure and low speed in the initial cooling stage to pre-cool the weak parts of the mold (such as sharp corners, thin walls, and holes). At this time, because the cooling rate is low, the mold does not generate large thermal stress and structural stress, thus effectively avoiding deformation or even cracking of the weak parts of the mold. Subsequently, the pressure is gradually increased until the cooling air pressure reaches 12-14 bar, and the fan runs at full speed. Since the risk of deformation and cracking of the weak parts of the mold is avoided, the effective quenching cooling air pressure can be 3-5 bar higher than the original, increasing the cooling capacity of the die-casting mold core, thus achieving a more ideal hardened layer depth.

[0046] The process of this invention ensures uniform hardness distribution of the mold by segmented control of cooling gas pressure and fan speed. Taking 1800*960*560mm as an example, the hardness non-uniformity of the mold is less than 1.5HRC.

[0047] The processing technology of this invention improves the impact energy by 80-100J compared to conventional heat treatment processes. After 1000 thermal fatigue cycles, the main crack length is reduced by 250-260μm and the crack width is reduced by 7-24μm compared to conventional heat treatment processes, demonstrating excellent thermal fatigue performance.

[0048] The method of this invention also incorporates a hot-melt treatment process for hot-melt crystallization and reinforcement of the thin-walled surface of the mold, eliminating internal defects in the thin-walled surface of the mold, specifically including the following steps:

[0049] The mold is transferred to the laser melting chamber, which is equipped with a laser melting system, an infrared temperature sensor, and a powder feeding system. The powder feeding system is used to spread metal powder on the surface of the mold. The laser melting system generates a laser to heat-melt the surface of the mold. The infrared temperature sensor is used to obtain the temperature of the melting surface in real time. The laser melting system includes several laser emission points, which form a laser scanning heating surface to scan and ablate the surface of the mold. The temperature range of the laser scanning heating surface is 600-800℃.

[0050] The powder feeding system is activated, and metal powder is spread on the surface of the mold. The metal powder is then melted and solidified on the surface of the mold by laser until the metal powder is fused to form a cladding structure on the surface of the mold. During the heat melting process on the surface of the mold, the infrared temperature sensor acquires the temperature of the molten surface in real time and adjusts the laser parameters accordingly to keep the temperature of the molten surface of the mold within a suitable heating temperature range. The laser parameters are also adjusted according to the shape of the molten surface of the mold. The laser parameters are based on the temperature of the molten surface and the thickness of the cladding structure, and the laser power, scanning speed, and spot diameter are adjusted accordingly.

[0051] In this embodiment, the metal powder is one or more of magnesium alloy powder, lead alloy powder, and aluminum alloy powder. The particle size of the metal powder is 20-100 mesh, preferably 20-30 mesh. The thickness of the cladding structure layer is 1000 micrometers to 3000 micrometers. The laser power is 400-10000W. The scanning speed is 1-10mm / s. The spot diameter is 1-5mm. The protective gas is an inert gas.

[0052] This invention incorporates a hot-melt treatment process to solidify and reinforce the thin-walled surface of a mold, eliminating defects in the thin-walled mold. Metal powder is laser-melted and solidified on the mold surface until it forms a cladding structure. During the hot-melt treatment of the mold surface, an infrared temperature sensor continuously monitors the temperature of the molten surface, ensuring that the temperature of the molten surface remains within a suitable preset temperature range.

[0053] By using the above-mentioned hot-melt crystallization reinforcement of the thin wall surface of the mold, the warping and cracking of the thin wall surface of the mold is significantly reduced, effectively avoiding cracks, ruptures, and warping deformation, improving the internal and external quality of the mold and the comprehensive mechanical properties of the mold surface, and effectively preventing deformation or even cracking in the weak parts of the mold.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art can make many possible variations and modifications to the technical solution of the present invention, or modify it into equivalent embodiments, without departing from the scope of the present invention's technical solution. Therefore, all equivalent changes made based on the shape, structure, and principle of the present invention without departing from the scope of the present invention's technical solution should be covered within the protection scope of the present invention.

Claims

1. A heat treatment process to reduce quenching deformation and cracking in die-casting mold steel, characterized in that, Includes the following steps: (1) Place the prepared mold in a vacuum high-pressure gas quenching furnace, heat and keep it warm using a quenching process to fully austenitize the mold; (2) After the mold has been fully austenitized in step (1), high-purity nitrogen gas is introduced into the mold in slow gas filling mode and pressurized to 3 bar. The cooling fan is started and the speed is set to 1800 rpm. The mold is kept cooled for 1 minute. (3) After the mold in step (2) has been cooled and held for 1 minute, high-purity nitrogen gas is introduced in slow inflation mode and pressurized to 6 bar. The speed of the cooling fan is increased to 2200 rpm and kept cooled for 1 minute. (4) After cooling and heat preservation in step (3), the mold is filled with high-purity nitrogen in slow inflation mode and pressurized to 9 bar. The speed of the cooling fan is increased to 2600 rpm and kept cooling for 1 minute. (5) After step (4) is completed, high-purity nitrogen gas is injected into the vacuum high-pressure gas quenching furnace in fast charging mode and pressurized to 12-14 bar. The speed of the cooling fan is increased to 3000 rpm. When the surface temperature of the mold drops to 450°C, the nitrogen pressure is reduced and the fan speed is adjusted according to the core temperature of the mold until the temperature difference between the mold surface and the core is less than 100°C. Then, high-purity nitrogen gas is injected into the vacuum high-pressure gas quenching furnace and pressurized to 12-14 bar. The speed of the cooling fan is increased to 3000 rpm. Cooling is stopped when the core temperature of the mold reaches 110°C under high-speed and high-pressure cooling.

2. The heat treatment process for reducing quenching deformation and cracking of die-casting mold steel according to claim 1, characterized in that, In step (2), high-purity nitrogen gas is introduced and pressurized to 3 bar, with a gas filling rate of 0.15 bar / second.

3. The heat treatment process for reducing quenching deformation and cracking of die-casting mold steel according to claim 1, characterized in that, In step (3), high-purity nitrogen gas is introduced and pressurized to 6 bar, with a gas filling rate of 0.30 bar / second.

4. The heat treatment process for reducing quenching deformation and cracking of die-casting mold steel according to claim 1, characterized in that, In step (4), high-purity nitrogen is introduced and pressurized to 9 bar in slow inflation mode, with an inflation rate of 0.45 bar / second.

5. The heat treatment process for reducing quenching deformation and cracking of die-casting mold steel according to claim 1, characterized in that, In step (5), high-purity nitrogen gas is introduced and pressurized to 12-14 bar, with a gas filling rate of 0.80 bar / second.

6. The heat treatment process for reducing quenching deformation and cracking of die-casting mold steel according to claim 1, characterized in that, All steps (2) to (5) are cooled in the same container, with 99.99% high-purity nitrogen as the medium.

7. The heat treatment process for reducing quenching deformation and cracking of die-casting mold steel according to claim 1, characterized in that, The cooling fan is a variable frequency cooling fan.

8. The heat treatment process for reducing quenching deformation and cracking of die-casting mold steel according to claim 1, characterized in that, When the mold surface temperature drops to 450°C, step (5) involves reducing the nitrogen pressure and adjusting the cooling fan speed based on the mold core temperature. Specifically, this includes the following steps: The nitrogen pressure is fixed at 3 bar, and the isothermal temperature is set at 450℃, with an upper deviation of +10℃ and a lower deviation of -20℃. That is, the mold surface temperature is controlled within the range of 460 to 430℃. When the mold surface temperature rises due to the heat conduction from the core, and the mold surface temperature rises above 460℃, the fan speeds up. When the mold surface temperature drops to 430℃, the fan speeds down or even stops. If the mold surface temperature continues to drop when the fan stops, it will automatically start heating to keep the mold surface temperature within the set isothermal temperature range until the mold core temperature drops to 530℃ and remains there for 3 to 8 minutes, at which point the isothermal test ends.

9. The heat treatment process for reducing quenching deformation and cracking of die-casting mold steel according to claim 1, characterized in that, It also includes step (6) of hot melt treatment for the hot melt crystallization reinforcement of the thin wall surface of the mold, which specifically includes the following steps: (6.1) The mold is transferred to the laser melting chamber. The laser melting chamber is equipped with a laser melting system, an infrared temperature sensor and a powder feeding system. The powder feeding system is used to spread metal powder on the surface of the mold. The laser melting system generates a laser for thermally melting the surface of the mold. The infrared temperature sensor is used to obtain the temperature of the melting surface in real time. The laser melting system includes several laser emission points. The several laser emission points form a laser scanning heating surface to scan and ablate the surface of the mold. (6.2) Turn on the powder feeding system to spread the metal powder on the surface of the mold. The metal powder is melted by laser and solidified on the surface of the mold until the metal powder is melted on the surface of the mold to form a cladding structure. During the heat melting process of the mold surface, the infrared temperature sensor obtains the temperature of the melting surface in real time and adjusts the laser parameters accordingly to keep the temperature of the mold melting surface within a suitable heating temperature range. The laser parameters are adjusted according to the shape of the mold melting surface. The laser parameters are based on the temperature of the melting surface and the thickness of the cladding structure, and the laser power, scanning speed and spot diameter are adjusted accordingly.

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