Apparatus and method for producing hot-stamped parts

Abstract

This invention provides an apparatus and method for producing mass-produced hot-stamped parts. The apparatus includes a heating furnace unit and a hot stamping unit; the heating furnace unit has multiple independent airtight chambers, including a feeding chamber, a heating chamber, and a discharging chamber connected in sequence; the hot stamping unit includes a stamping press; the discharging chamber is connected to the stamping press. Using the apparatus of this invention to perform airtight heat treatment and hot stamping of blanks, especially aluminum-silicon coated blanks, produces high-strength aluminum-silicon coated parts with significantly lower hydrogen content than those produced in conventional atmosphere furnaces, resulting in a lower risk of hydrogen embrittlement. This method is particularly suitable for hot-formed aluminum-silicon coated parts with strength ≥1500MPa.

Description

Technical Field

[0001] This invention relates to the field of hot stamping, specifically to an apparatus and method for preparing hot stamped parts. Background Technology

[0002] Currently, the most widely used material in the hot stamping industry is aluminum-silicon coated steel sheet. This coating effectively prevents oxidation of the billet during the austenitizing heating process. Therefore, the atmosphere inside commonly used furnaces does not require oxygen potential control; instead, moisture content is controlled by adjusting the gas dew point. However, during continuous mass production in ordinary atmosphere furnaces, aluminum-silicon coated steel sheets are prone to reacting with residual moisture in the hot air to generate hydrogen, leading to hydrogen-induced delayed fracture. Hydrogen-induced delayed fracture, also known as hydrogen embrittlement, is a phenomenon caused by hydrogen atoms dissolving in metallic materials, resulting in weakened or embrittled properties. Hydrogen accelerates the propagation of internal cracks in the metal, causing the fracture surface to change from ductile to brittle. In actual production, the dew point in austenitizing furnaces is generally required to be controlled between -15℃ and -20℃ to inhibit moisture production and prevent moisture from reacting with surface elements such as iron, aluminum, and silicon to generate hydrogen. However, in actual mass production, the roller hearth furnaces and box furnaces commonly used lack multiple airtight cavities. When billets enter and exit the furnace, outside air containing a large amount of moisture enters the furnace cavity, making it difficult to control the dew point atmosphere inside the furnace. Furthermore, due to equipment malfunctions, billets may remain in the furnace for extended periods, causing the aluminum-silicon coating to absorb a large number of hydrogen atoms, thus triggering hydrogen embrittlement. Currently, the method of introducing dry air into the austenitizing furnace to control moisture only mitigates the hydrogen absorption problem of the aluminum-silicon coating during the heating process. In the manufacturing process of aluminum-silicon coated plates, the steel sheet enters the molten aluminum, which also contains a large amount of hydrogen. While dry, high-purity nitrogen is typically introduced into the molten aluminum to remove hydrogen, a portion of hydrogen will always remain in the molten aluminum, and this portion cannot be removed by controlling the dew point in the austenitizing furnace. Although vacuum heating is widely used in the heat treatment industry, commonly used vacuum heating equipment is only suitable for small parts, and the heating cycle is measured in hours, which cannot meet the requirements of large size and high cycle time (tens of seconds) for automotive body parts. Therefore, the hot forming heating of aluminum-silicon coated steel sheets has always been achieved using non-airtight continuous roller hearth and box furnaces.

[0003] With increasingly stringent fuel consumption regulations, the demand for lightweight vehicles is becoming more urgent, leading to the application of more and more lightweight materials in various automotive components. In recent years, press-hardened steel (PHS) has gained popularity among OEMs due to its superior strength, good formability, and high dimensional accuracy, and is widely used in automotive structural parts. Currently, PHS with a tensile strength of 1500 MPa is widely used, and some steel mills can mass-produce PHS with a strength above 1800 MPa. However, the higher the strength, the greater the risk of hydrogen embrittlement. Steel with a tensile strength of 1500 MPa already exhibits the risk of hydrogen-induced delayed fracture; for 1800 MPa and even 2000 MPa steel, the risk is even greater and more severe. Hydrogen embrittlement severely limits the application of aluminum-silicon coated materials for ultra-high strength steel above 1800 MPa. Furthermore, for coated steel sheets at the 1500 MPa level, the elongation needs to be greater than 5%, while for coated steel sheets above 1800 MPa, the elongation is only about 4%, with a bending angle between 35 and 40 degrees. This lack of toughness causes coated panels with a strength of 1800 MPa or higher to crack during impacts, severely impacting their application. Summary of the Invention

[0004] In order to overcome the defects in the prior art, solve the hydrogen embrittlement problem of coated plates above 1800 MPa and improve the toughness of coated steel plates at 1800 MPa, the first objective of this invention is to provide an apparatus for preparing mass-produced hot-stamped parts; the second objective of this invention is to provide a method for preparing mass-produced hot-stamped parts; and the third objective of this invention is to provide hot-stamped parts with aluminum-silicon coatings prepared by this method.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] On one hand, the present invention provides an apparatus for manufacturing mass-produced hot-stamped parts, the apparatus comprising:

[0007] Heating furnace unit and hot stamping unit;

[0008] The heating furnace unit has multiple independent airtight chambers, including a feeding chamber, a heating chamber, and a discharging chamber connected in sequence; the hot stamping unit includes a stamping machine;

[0009] The discharge chamber is connected to the stamping machine.

[0010] In the above-described device, preferably, the inlet of the feeding chamber has an airtight feeding furnace door; and an airtight first isolation furnace door is provided between the outlet of the feeding chamber and the inlet of the heating chamber.

[0011] In the above-described device, preferably, the outlet of the discharge chamber has an airtight discharge furnace door; and an airtight second isolation furnace door is provided between the inlet of the discharge chamber and the outlet of the heating chamber.

[0012] In the above-described apparatus, preferably, the heating chamber is selected from a vacuum chamber or an atmosphere chamber.

[0013] In the above-described apparatus, preferably, when the heating chamber is a vacuum chamber, the vacuum degree inside the heating chamber is 1 to 10000 Pa, preferably 100 to 1000 Pa, and the temperature inside the chamber is 880 to 1000°C, preferably 930°C; the heating chamber is used to heat multiple sets of billets simultaneously.

[0014] In the above-described apparatus, preferably, when the heating chamber is an atmosphere chamber, the atmosphere in the heating chamber is dry air or other dry gas, and the dry air or other dry gas has a water vapor content of less than 1000 ppm (volume fraction), preferably 100 ppm (volume fraction); the air pressure in the chamber is the outdoor atmospheric pressure, and the temperature in the chamber is 880-1000℃, preferably 930℃; the heating chamber is used to heat multiple sets of billets simultaneously.

[0015] In the above-described device, preferably, the temperature of the discharge chamber is 400-800℃, and more preferably 600-700℃.

[0016] In the above-described device, preferably, a feeding platform is provided upstream of the feeding chamber; and a discharging platform is provided downstream of the discharging chamber.

[0017] On the other hand, the present invention also provides a method for preparing mass-produced hot-stamped parts, the method using the above-mentioned apparatus, comprising the following steps:

[0018] The billet is fed into an airtight feeding chamber, and then the feeding chamber is evacuated to a certain degree of vacuum.

[0019] The billet is then sent to an airtight heating chamber for austenitizing heating to obtain a hot billet;

[0020] The hot billet is fed into an airtight discharge chamber;

[0021] The blanks conveyed through the discharge chamber are transferred to the stamping press for hot stamping and forming.

[0022] In the above preparation method, preferably, the billet is fed into the feeding chamber through the feeding furnace door; the billet in the feeding chamber is sent to the heating chamber through the first isolation furnace door; the hot billet in the heating chamber is sent to the discharge chamber through the second isolation furnace door; and the billet in the discharge chamber is sent to the stamping machine through the discharge furnace door.

[0023] In the above preparation method, preferably, the blank includes an aluminum-silicon coated blank.

[0024] In the above preparation method, preferably, when the heating chamber is a vacuum chamber, after the billet enters the feeding chamber through the feeding furnace door, the feeding chamber is evacuated to a vacuum degree higher than 10000 Pa, preferably 100 to 1000 Pa;

[0025] Once the vacuum level in the feeding chamber is close to that in the heating chamber, the first isolation furnace door between the feeding chamber and the heating chamber is opened, and the billet is fed into the heating chamber for austenitizing heating. Then, the first isolation furnace door between the feeding chamber and the heating chamber is closed.

[0026] In the above preparation method, preferably, when the heating chamber is a vacuum chamber, before the billet is heat-treated in the heating chamber and ready to be unloaded from the furnace, the discharge chamber is evacuated to a vacuum level higher than 10000 Pa, preferably 100 to 1000 Pa.

[0027] Once the vacuum level in the discharge chamber is close to that in the heating chamber, the second isolation furnace door between the discharge chamber and the heating chamber is opened, and the billet is fed into the discharge chamber. Then the second isolation furnace door between the discharge chamber and the heating chamber is closed.

[0028] Before opening the discharge furnace door of the discharge chamber, fill the discharge chamber with dry air or other dry gas until the outdoor air pressure is reached, and then open the discharge furnace door.

[0029] In the above preparation method, preferably, when the heating chamber is a dry atmosphere chamber, after the billet enters the feeding chamber through the feeding furnace door, the feeding chamber is evacuated to a vacuum degree higher than 10000 Pa, preferably 100-1000 Pa; then dry air or other dry gas is introduced into the feeding chamber, the dry air or other dry gas having a water vapor content of less than 1000 ppm, preferably 100 ppm;

[0030] Once the air pressure in the feeding chamber is close to that in the heating chamber, the first isolation furnace door between the feeding chamber and the heating chamber is opened, and the billet is sent into the heating chamber for austenitizing heating. Then the first isolation furnace door between the feeding chamber and the heating chamber is closed.

[0031] In the above preparation method, preferably, when the heating chamber is a vacuum chamber, before the billet is heat-treated in the heating chamber and ready to be unloaded from the furnace, the discharge chamber is evacuated to a vacuum degree higher than 10000 Pa, preferably 100-1000 Pa; then dry air or other dry gas is introduced into the discharge chamber, the dry air or other dry gas having a water vapor content of less than 1000 ppm, preferably 100 ppm;

[0032] Once the air pressure in the discharge chamber is close to that in the heating chamber, the second isolation furnace door between the discharge chamber and the heating chamber is opened, and the billet is fed into the discharge chamber. Then the second isolation furnace door between the discharge chamber and the heating chamber is closed.

[0033] Before opening the discharge furnace door of the discharge chamber, fill the discharge chamber with dry air or other dry gas until the outdoor air pressure is reached, and then open the discharge furnace door.

[0034] In the above preparation method, preferably, the hot stamping forming method in the stamping press includes laser welding of the output blank.

[0035] In the above preparation method, preferably, the temperature of the blank being hot-stamped in the stamping press is controlled within the range of 500 to 700°C and the heating rate is less than 7°C / s.

[0036] In another aspect, the present invention also provides a hot-stamped part with an aluminum-silicon coating, which is prepared by the above-described preparation method.

[0037] Preferably, the tensile strength of the hot-stamped part is ≥1500MPa.

[0038] Preferably, the production cycle of the hot-stamped parts is between 20 and 40 seconds.

[0039] The beneficial effects of this invention are:

[0040] This invention employs a heating furnace with airtight chambers, achieving a vacuum level exceeding 10000 Pa by evacuating the gas within these chambers. This ensures that the water vapor content within the furnace is less than 1000 ppm, corresponding to a dew point of approximately -15°C. Heating can then be achieved through two methods: one involves evacuating the furnace from its independent chambers and then introducing dry air with an even lower dew point, maintaining consistent pressure inside and outside the furnace; the other is vacuum heating, where heating is performed while maintaining a certain vacuum level within the airtight chambers. Furthermore, vacuum heating facilitates the diffusion of hydrogen from the raw materials into the vacuum, thus reducing the hydrogen content in the raw materials. The use of three independent airtight chambers cleverly avoids the drawbacks of conventional vacuum furnaces. The atmosphere in the heating chambers, which simultaneously heat multiple sets of raw materials, is consistently maintained at a certain vacuum level or a dry atmosphere, eliminating the need for frequent evacuation from one atmosphere to a specific vacuum level. This avoids damage to the vacuum equipment caused by high-temperature evacuation and also avoids the prolonged evacuation required for large-volume chambers. Only the inlet and outlet chambers are evacuated. Each chamber holds only one set of billets, has a small volume, and requires short evacuation times. Using a single, independent chamber for both inlet / outlet and heating would severely damage the vacuum equipment, especially given the high temperatures (above 900°C). Furthermore, mass production requires heating multiple sets of billets simultaneously, and a large inlet / outlet chamber would result in excessively long vacuuming times. Maintaining a certain furnace temperature in the outlet chamber is one of the innovative aspects of this invention. This is because the billets, after austenitic heating, need to be quickly transferred to the press for pressing. If the transfer time exceeds 12 seconds, the martensite content in the hot-pressed and quenched product will be insufficient, leading to substandard mechanical properties. When the billets exit the heating chamber and pass through the outlet chamber, there is a waiting time in the outlet chamber for the furnace door to open. This results in excessively long times from the billets to the press, affecting the product's mechanical properties. The inventors discovered that if the discharge chamber maintains a certain temperature, the billet will retain sufficient temperature while waiting in the discharge chamber, ensuring that the mechanical properties of the product are up to standard after being pressed by the press. Although the discharge chamber also requires evacuation, the gas temperature is much lower than that of the heating chamber, thus having no adverse effect on the vacuum equipment.

[0041] To make the above and other objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a schematic diagram of the apparatus for producing mass-produced hot-stamped parts according to the present invention.

[0044] Figure 2 The figure shows the spot welding test results of the hot stamping part prepared in Embodiment 1 of the present invention.

[0045] Figure 3 The figure shows the test results of the structural adhesive of the hot-stamped part prepared in Example 1 of the present invention.

[0046] Figure 4 The figure shows the electrophoretic coating test results of the hot stamping part prepared in Example 1 of the present invention.

[0047] Explanation of symbols in the attached drawings:

[0048] 1. Billet; 2. Feeding platform; 3. Feeding furnace door; 4. Feeding chamber; 5. First isolation furnace door; 6. Heating chamber; 7. Second isolation furnace door; 8. Discharge chamber; 9. Discharge furnace door; 10. Discharge platform; 11. Stamping machine. Detailed Implementation

[0049] 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.

[0050] This invention provides an apparatus for manufacturing large quantities of hot-stamped parts, such as... Figure 1 As shown, the device includes:

[0051] The heating furnace unit and the hot stamping unit are provided. The heating furnace unit has multiple independent airtight chambers, including a feeding chamber 4, a heating chamber 6 and a discharging chamber 8 connected in sequence. The hot stamping unit includes a stamping machine 11. The discharging chamber 8 is connected to the stamping machine 11.

[0052] In a preferred embodiment, the inlet of the feeding chamber 4 has an airtight feeding furnace door 3; and an airtight first isolation furnace door 5 is provided between the outlet of the feeding chamber 4 and the inlet of the heating chamber 6.

[0053] In a preferred embodiment, the outlet of the discharge chamber 8 has an airtight discharge furnace door 9; and an airtight second isolation furnace door 7 is provided between the inlet of the discharge chamber 8 and the outlet of the heating chamber 6.

[0054] In a preferred embodiment, the heating chamber 6 is selected from a vacuum chamber or an atmosphere chamber.

[0055] In a preferred embodiment, when the heating chamber 6 is a vacuum chamber, the vacuum degree inside the heating chamber 6 is 1 to 10000 Pa, preferably 100 to 1000 Pa, and the temperature inside the chamber is 880 to 1000°C, preferably 930°C; the heating chamber 6 is used to heat multiple sets of billets simultaneously.

[0056] In a preferred embodiment, when the heating chamber 6 is an atmosphere chamber, the atmosphere in the heating chamber 6 is dry air or other dry gas, wherein the dry air or other dry gas has a water vapor content of less than 1000 ppm (volume fraction), preferably 100 ppm (volume fraction); the air pressure in the chamber is the outdoor atmospheric pressure, and the temperature in the chamber is 880-1000°C, preferably 930°C; the heating chamber 6 is used to heat multiple sets of billets simultaneously.

[0057] In a preferred embodiment, the temperature of the discharge chamber 8 is 400-800°C, preferably 650°C.

[0058] In a preferred embodiment, a feeding platform 2 is provided upstream of the feeding chamber 4; and a discharging platform 10 is provided downstream of the discharging chamber 8.

[0059] This embodiment also provides a method for preparing mass-produced hot-stamped parts. The method uses the above-mentioned apparatus and includes the following steps:

[0060] The blank 1 is fed into the airtight feeding chamber 4, and then the feeding chamber 4 is evacuated to a certain degree of vacuum.

[0061] The billet is then sent to an airtight heating chamber 6 for austenitizing heating to obtain a hot billet;

[0062] The hot billet is fed into the airtight discharge chamber 8;

[0063] The blank conveyed through the discharge chamber 8 is transferred to the stamping press 11 for hot stamping.

[0064] In a preferred embodiment, the billet 1 is fed into the feeding chamber 4 through the feeding furnace door 3; the billet in the feeding chamber 4 is sent to the heating chamber 6 through the first isolation furnace door 5; the hot billet in the heating chamber 6 is sent to the discharge chamber 8 through the second isolation furnace door 7; and the billet in the discharge chamber 8 is sent to the stamping machine 11 through the discharge furnace door 9.

[0065] In a preferred embodiment, the blank 1 is selected from aluminum-silicon coated blanks.

[0066] In a preferred embodiment, when the heating chamber 6 is a vacuum chamber, after the billet 1 enters the feeding chamber 4 through the feeding furnace door 3, the feeding chamber 4 is evacuated to a vacuum level higher than 10000 Pa, preferably 100 to 1000 Pa.

[0067] Once the vacuum level in the feeding chamber 4 is close to that in the heating chamber 6, the first isolation furnace door 5 between the feeding chamber 4 and the heating chamber 6 is opened, and the billet is fed into the heating chamber 6 for austenitizing heating. Then the first isolation furnace door 5 between the feeding chamber 4 and the heating chamber 6 is closed.

[0068] In a preferred embodiment, when the heating chamber 6 is a vacuum chamber, before the billet is heat-treated in the heating chamber 6 and ready to be unloaded from the furnace, the discharge chamber 8 is evacuated to a vacuum level higher than 10000 Pa, preferably 100 to 1000 Pa.

[0069] Once the vacuum level in the discharge chamber 8 is close to that in the heating chamber 6, the second isolation furnace door 7 between the discharge chamber 8 and the heating chamber 6 is opened, and the billet is sent into the discharge chamber 8. Then the second isolation furnace door 7 between the discharge chamber 8 and the heating chamber 6 is closed.

[0070] Before opening the discharge furnace door 9 of the discharge chamber 8, dry air or other dry gas is filled into the discharge chamber 8 to reach the outdoor air pressure, and then the discharge furnace door 9 is opened.

[0071] In a preferred embodiment, when the heating chamber 6 is a dry atmosphere chamber, after the billet 1 enters the feeding chamber 4 through the feeding furnace door 3, the feeding chamber 4 is evacuated to a vacuum degree higher than 10000 Pa, preferably 100-1000 Pa; then dry air or other dry gas is introduced into the feeding chamber 4, the dry air or other dry gas having a water vapor content of less than 1000 ppm, preferably 100 ppm;

[0072] Once the air pressure in the feeding chamber 4 is close to the air pressure in the heating chamber 6, the first isolation furnace door 5 between the feeding chamber 4 and the heating chamber 6 is opened, and the billet is sent into the heating chamber 6 for austenitizing heating. Then the first isolation furnace door 5 between the feeding chamber 4 and the heating chamber 6 is closed.

[0073] In a preferred embodiment, when the heating chamber 6 is a vacuum chamber, before the billet is heat-treated in the heating chamber 6 and ready to be unloaded from the furnace, the discharge chamber 8 is evacuated to a vacuum level higher than 10000 Pa, preferably 100-1000 Pa; then dry air or other dry gas is introduced into the discharge chamber 8, wherein the dry air or other dry gas has a water vapor content of less than 1000 ppm, preferably 100 ppm;

[0074] After the air pressure in the discharge chamber 8 is close to the air pressure in the heating chamber 6, the second isolation furnace door 7 between the discharge chamber 8 and the heating chamber 6 is opened, and the billet is sent into the discharge chamber 8. Then the second isolation furnace door 7 between the discharge chamber 8 and the heating chamber 6 is closed.

[0075] Before opening the discharge furnace door 9 of the discharge chamber 8, dry air or other dry gas is filled into the discharge chamber 8 to reach the outdoor air pressure, and then the discharge furnace door 9 is opened.

[0076] In a preferred embodiment, the hot stamping process in the stamping press 11 includes laser welding of the output blank.

[0077] In a preferred embodiment, the temperature of the blank being hot-stamped in the stamping press 11 is controlled within the range of 500 to 700°C, and the heating rate is less than 7°C / s.

[0078] This embodiment also provides a hot-stamped part with an aluminum-silicon coating, which is prepared by the above-described preparation method.

[0079] In a preferred embodiment, the tensile strength of the hot-stamped part is ≥1500MPa.

[0080] In a preferred embodiment, the production cycle of the hot-stamped part is between 20 and 40 seconds.

[0081] The present invention will now be described in detail through specific embodiments:

[0082] Example 1:

[0083] First, hot-stamped aluminum-silicon coated blanks with a tensile strength of 1800 MPa (1.8 mm thick) are fed into a vacuum furnace with three airtight chambers: a feeding chamber (4), a heating chamber (6), and a discharging chamber (8). The vacuum level in the heating chamber is 10 Pa. The process is as follows: Before the blank enters the feeding chamber (4), it is filled with air to reach the outside air pressure. The furnace door (3) is opened, the blank is fed in, and the furnace door (3) is closed. Air is then evacuated from the feeding chamber (4) to achieve a vacuum level of 10–100 Pa. Then, the first airtight isolation furnace door (5) between the feeding chamber (4) and the heating chamber (6) is opened, and the blank is fed into the heating chamber (6) for heating. After austenitization heating is completed, the blank is prepared to be sent to the discharging chamber (8). Before the second airtight isolation furnace door (7) between the heating chamber (6) and the discharging chamber (8) is opened, the discharging chamber (8) is first evacuated to a vacuum level of 10–100 Pa. Then the second isolation furnace door 7 is opened, and the billet is sent into the discharge chamber 8. Then the second isolation furnace door 7 is closed. Before the discharge furnace door 9 is opened, dry air or other dry gas with a dew point of -45°C is filled into the discharge chamber 8 to reach the outdoor air pressure, and then the discharge furnace door 9 is opened. The furnace temperature is 930 degrees Celsius, the heating time is 300 seconds, and the billet is sent out of the furnace and fed into the stamping press 11 for stamping.

[0084] Example 2:

[0085] First, hot-stamped aluminum-silicon coated blanks with a tensile strength of 1800 MPa (1.8 mm thick) are fed into a vacuum furnace with three airtight chambers: a feeding chamber (4), a heating chamber (6), and a discharging chamber (8). The vacuum level in the heating chamber is 10 Pa. The process is as follows: Before the blank enters the feeding chamber (4), it is filled with air to reach the outside air pressure. The furnace door (3) is opened, the blank is fed in, and the furnace door (3) is closed. Air is then evacuated from the feeding chamber (4) to achieve a vacuum level of 10–100 Pa. Then, the first airtight isolation furnace door (5) between the feeding chamber (4) and the heating chamber (6) is opened, and the blank is fed into the heating chamber (6) for heating. After austenitization heating is completed, the blank is prepared to be sent to the discharging chamber (8). Before the second airtight isolation furnace door (7) between the heating chamber (6) and the discharging chamber (8) is opened, the discharging chamber (8) is first evacuated to a vacuum level of 10–100 Pa. Then the second isolation furnace door 7 is opened, and the billet is sent into the discharge chamber 8. The second isolation furnace door 7 is then closed. Before the discharge furnace door 9 is opened, dry air or other dry gas with a dew point of -45°C is filled into the discharge chamber 8 to reach the outdoor air pressure, and then the discharge furnace door 9 is opened. The furnace temperature is 930 degrees Celsius, the heating time is 600 seconds, and the billet is sent out of the furnace and fed into the stamping press 11 for stamping.

[0086] Example 3:

[0087] First, hot-pressed aluminum-silicon coated billets with a tensile strength of 1800 MPa (1.8 mm thick) are fed into an atmosphere furnace with three airtight chambers: a feeding chamber (4), a heating chamber (6), and a discharging chamber (8). The atmosphere in the heating chamber (6) has a dew point of -45°C and a pressure of one atmosphere. The process is as follows: Before the billet enters the feeding chamber (4), it is filled with air to reach the outside air pressure. The furnace door (3) is opened, the billet is fed in, the furnace door (3) is closed, and the air in the feeding chamber (4) is evacuated to a vacuum of 10-100 Pa. Then, dry air with a dew point of -45°C is introduced into the feeding chamber (4) to reach the pressure of the heating chamber (6), which is one atmosphere. Next, the airtight first isolation furnace door (5) between the feeding chamber (4) and the heating chamber (6) is opened, and the billet is fed into the heating chamber (6) for heating. After austenitization heating is completed, the billet is ready to be sent to the discharging chamber (8). Before opening the airtight second isolation furnace door 7 between the heating chamber 6 and the discharge chamber 8, the discharge chamber 8 must first be evacuated to a vacuum level of 10-100 Pa and then filled with dry air at a dew point of -45°C to reach the pressure of the heating chamber 6, which is one atmosphere. Then, the second isolation furnace door 7 is opened, the billet is fed into the discharge chamber 8, and then the second isolation furnace door 7 is closed. The furnace temperature is 930 degrees Celsius, and the heating time is 300 seconds. Then, the discharge furnace door 9 is opened, and the billet is sent out of the furnace and fed onto the stamping press 11 for stamping.

[0088] Comparative Example 1:

[0089] First, a 1.8mm thick 22MnB5 aluminum-silicon coated sheet with a hot stamping thickness of 1800Mpa is placed in an atmosphere furnace with a dew point of -5℃ and heated to a furnace temperature of 930 degrees for 300 seconds. After austenitization heating is completed, it is placed on a stamping press for stamping.

[0090] Comparative Example 2:

[0091] First, a 1.8mm thick 1800Mpa hot stamping sheet of 22MnB5 aluminum-silicon coated plate is placed in an atmosphere furnace with a dew point of -5℃ and heated at 930 degrees for 600 seconds. After the austenitization heating is completed, it is placed on a stamping machine for stamping.

[0092] Comparative Example 3:

[0093] First, a 1.8mm thick 22MnB5 aluminum-silicon coated sheet with a hot stamping thickness of 1800Mpa is placed in an atmosphere furnace with a dew point of -5℃ and heated to a furnace temperature of 930 degrees for 300 seconds. After austenitization heating is completed, it is placed on a stamping press for stamping.

[0094] Comparative Example 4:

[0095] First, a 1.8mm thick 1800Mpa hot stamping sheet of 22MnB5 aluminum-silicon coated plate is placed in an atmosphere furnace with a dew point of -5℃ and heated at 930 degrees for 600 seconds. After the austenitization heating is completed, it is placed on a stamping machine for stamping.

[0096] Table 1 Performance results of the examples and comparative examples

[0097]

[0098] The parts prepared in Examples 1, 2, 1, 2, 3, and 4 were sprayed with salt spray for 10 minutes every 4 hours under neutral salt spray. The results are shown in Table 2.

[0099] Table 2 Comparison of four-point bending performance between the examples and the comparative examples.

[0100]

[0101] Spot welding tests were performed on the parts prepared in Example 1, and the experimental results are shown in Table 3 below. Figure 2 As shown in the figure, its welding performance is OK.

[0102] Table 3. Experimental results of spot welding test

[0103]

[0104] The structural adhesive was tested on the parts prepared in Example 1, and the results are as follows: Figure 3 As shown in the image, its adhesive properties are OK.

[0105] Electrophoretic coating tests were performed on the parts prepared in Example 1, and the results are as follows: Figure 4 As shown, its paintability is OK.

[0106] Furthermore, as shown in Tables 1 and 2, parts produced using this method have lower diffusible hydrogen content, higher elongation than those produced using conventional atmosphere furnace methods, better bending performance, and lower risk of hydrogen embrittlement. Welding performance, adhesive properties, and coating performance are all satisfactory. This is because, under vacuum conditions, fewer H2O molecules react with the aluminum-silicon coating during part heating, resulting in less diffusible hydrogen. In contrast, conventional atmosphere furnace heating produces more H2O molecules, leading to greater hydrogen generation from the reaction with the aluminum-silicon coating. This increased hydrogen content enters the heated austenitic billet, leading to increased internal stress and defects during martensite formation upon cooling, thus increasing elongation, bending angle, and risk of hydrogen embrittlement.

[0107] Specific embodiments have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. An apparatus for producing large quantities of hot-stamped parts, characterized in that, The hot-stamped part is an aluminum-silicon coated hot-stamped part, and the apparatus includes: Heating furnace unit and hot stamping unit; The heating furnace unit has multiple independent airtight chambers, including a feeding chamber, a heating chamber, and a discharging chamber connected in sequence; the hot stamping unit includes a stamping machine; The discharge chamber is connected to the stamping machine; wherein... The feeding chamber and the discharging chamber each contain only one set of blanks. The temperature of the discharging chamber is 400~800℃, so that the blanks can maintain a sufficient temperature while waiting in the discharging chamber, and thus the mechanical properties of the products after being pressed by the stamping press are qualified. The heating chamber is an atmosphere chamber, and the atmosphere in the heating chamber is always maintained in a certain dry atmosphere, so it is not necessary to frequently evacuate the heating chamber from one atmosphere to a certain vacuum degree. The heating chamber is used to heat multiple sets of billets simultaneously; the atmosphere in the heating chamber is dry air or other dry gas, and the dry air or other dry gas has a water vapor content of less than 1000 ppm by volume; the air pressure in the heating chamber is the outdoor atmospheric pressure, and the temperature in the heating chamber is 880~1000℃; The production cycle of the hot-stamped parts is between 20 and 40 seconds.

2. The apparatus according to claim 1, characterized in that: The inlet of the feeding chamber has an airtight feeding furnace door; an airtight first isolation furnace door is provided between the outlet of the feeding chamber and the inlet of the heating chamber.

3. The apparatus according to claim 1, characterized in that: The outlet of the discharge chamber has an airtight discharge furnace door; an airtight second isolation furnace door is provided between the inlet of the discharge chamber and the outlet of the heating chamber.

4. The apparatus according to claim 1, characterized in that: The temperature of the discharge chamber is 600~700℃.

5. The apparatus according to claim 1, characterized in that: A feeding platform is provided upstream of the feeding chamber; a discharging platform is provided downstream of the discharging chamber.

6. The apparatus according to claim 1, characterized in that: The moisture content of the dry air or other dry gas is 100 ppm by volume; the temperature inside the heating chamber is 930°C.

7. A method for manufacturing parts by mass production of hot stamping, characterized in that, The method uses the apparatus described in any one of claims 1 to 6 for preparation, and includes the following steps: The billet is fed into an airtight feeding chamber, and then the feeding chamber is evacuated to a certain degree of vacuum. The billet is then sent to an airtight heating chamber for austenitizing heating to obtain a hot billet; The hot billet is fed into an airtight discharge chamber; The blanks conveyed through the discharge chamber are transferred to the stamping press for hot stamping and forming.

8. The preparation method according to claim 7, characterized in that, The billet is fed into the feeding chamber through the feeding furnace door; the billet in the feeding chamber is sent to the heating chamber through the first isolation furnace door; the hot billet in the heating chamber is sent to the discharge chamber through the second isolation furnace door; and the billet in the discharge chamber is sent to the stamping machine through the discharge furnace door.

9. The preparation method according to claim 7, characterized in that, The blank includes an aluminum-silicon coated blank.

10. The preparation method according to claim 8, characterized in that, After the billet enters the feeding chamber through the feeding furnace door, the feeding chamber is evacuated to a vacuum level higher than 10000Pa; then dry air or other dry gas is introduced into the feeding chamber, and the dry air or other dry gas has a water vapor content of less than 1000ppm. Once the air pressure in the feeding chamber is close to that in the heating chamber, the first isolation furnace door between the feeding chamber and the heating chamber is opened, and the billet is sent into the heating chamber for austenitizing heating. Then the first isolation furnace door between the feeding chamber and the heating chamber is closed.

11. The preparation method according to claim 10, characterized in that, After the billet enters the feeding chamber through the feeding furnace door, the feeding chamber is evacuated to a vacuum degree of 10~100Pa; then dry air or other dry gas is introduced into the feeding chamber, and the water vapor content of the dry air or other dry gas is 100ppm.

12. The preparation method according to claim 7 or 8, characterized in that, Methods for hot stamping in a stamping press include laser welding of the output blanks.

13. The preparation method according to claim 7 or 8, characterized in that, The temperature of the blank for hot stamping in the stamping press is controlled within the range of 500~700℃, and the heating rate is less than 7℃ / s.

14. A hot-stamped part with an aluminum-silicon coating, which is prepared by the preparation method according to any one of claims 7 to 13.

15. The hot-stamped part according to claim 14, characterized in that, The tensile strength of the hot-stamped part is ≥1500MPa.

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