Apparatus and method for controlling shape and property gradient of ultra-high strength steel

Abstract

The application discloses a shape property gradient control device of ultrahigh-strength steel, which comprises a conveying frame, a first heating furnace, a rolling device and a second heating furnace are sequentially arranged between an input end and an output end of the conveying frame, and the output end of the conveying frame is connected with a stamping device; the stamping device comprises a matched upper male die and a lower female die, the lower female die is provided with a telescopic device on the side surface in face-to-face mode, the output end of the telescopic device is connected with an edge roller track; a plurality of cooling water channels are uniformly arranged in the upper male die and the lower female die, each cooling water channel is controlled independently, and the temperature of each cooling water channel is monitored by a thermocouple. The application further discloses a shape property gradient control method of ultrahigh-strength steel, which comprises the following steps: preheating, variable-thickness online rolling, austenitizing and synchronous shaping and stress relieving, hot stamping and partition quenching. The synchronous control of the rigidity, strength and toughness gradient of the ultrahigh-strength steel plate is effectively realized, so that the shape property of the steel plate has a gradient, and the lightweight design is realized while the rigidity design requirement is ensured.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hot stamping forming, and particularly relates to a shape-property gradient control device and method for super-high-strength steel. BACKGROUND

[0002] The automobile industry is one of the five pillar industries of the national economy of China and is also the largest carrier of high-tech. Under the premise of ensuring safety performance, the introduction of lightweight material structural parts in the vehicle body can reduce the vehicle body weight, improve fuel efficiency and reduce vehicle maintenance costs.

[0003] Super-high-strength steel is a kind of steel with super-high tensile strength (above 1380 MPa) and a martensitic structure. In recent years, it has been increasingly favored by the automobile industry due to its low cost, high tensile strength and obvious weight reduction benefits. Super-high-strength steel plates are generally manufactured by hot forming technology. This technology involves heating the super-high-strength steel plate to austenitization, then sending it into a hot stamping die with a cooling water channel through a mechanical hand or other equipment for stamping and pressure holding quenching to form a hot stamping part with high strength and high precision.

[0004] Chinese invention patent CN201510096852.X, "Hot stamping method for performance gradient distribution of high-strength steel parts", proposes a method of twice heating and quenching cooling to obtain hot stamping parts with different mechanical properties. The disadvantage of this process is that the process is relatively complex, the production efficiency is low, and it is not suitable for large-scale production. Chinese invention patent CN201410110908.8, "Method for processing high-strength steel hot stamping forming parts", proposes that for parts with uniform performance after hot stamping forming, local tempering or annealing treatment is performed, the heat conduction of the plate is used to realize the gradient change of the tempering or annealing temperature, and the performance gradient change is realized. This process requires a specially designed induction heating coil, and the part will deform during quenching.

[0005] At present, hot forming of super-high-strength steel generally manufactures steel plates with the same wall thickness, and the performance gradient achieved is also homogeneous. With the continuous advancement of automobile lightweight design, the demand for super-high-strength steel parts with gradient changes in stiffness and strength is increasingly strong. However, quenching can only change the strength, and the stiffness problem cannot be solved, so the cross-section deformation method is needed to design the stiffness. At present, there is no public research report on hot stamping technology with gradient changes in strength and stiffness. SUMMARY

[0006] The application provides a shape-property gradient control device and method for super-high-strength steel, which solves the technical problem of shape-property gradient change in hot stamping technology.

[0007] In order to solve the above technical problems, the technical scheme adopted by the present application is: a shape property gradient control device of ultra-high strength steel, comprising a conveying frame, conveying rollers are arranged at intervals along the length direction of the conveying frame, a first heating furnace, a rolling device and a second heating furnace are sequentially arranged between the input end and the output end of the conveying frame; the output end of the conveying frame is connected with a stamping device; the stamping device comprises a matched upper male die and a lower female die, an extension device is mounted on the side surface of the lower female die arranged face to face, and the output end of the extension device is connected with an edge roller track; a plurality of cooling water channels are uniformly arranged in the interior of the upper male die and the lower female die, each cooling water channel is controlled independently, and the temperature of each cooling water channel is monitored by a thermocouple.

[0008] Further, a plurality of groups of sizing rollers are arranged in the second heating furnace, which plays a role of removing residual stress under sizing conditions.

[0009] Further, a connecting plate is mounted on the side surface of the lower female die arranged face to face, and the extension device is arranged on the connecting plate.

[0010] Further, the extension device comprises an L-shaped support fixedly connected with the connecting plate, and a hydraulic cylinder or a pneumatic cylinder is connected with the L-shaped support.

[0011] Further, the output end of the conveying frame is connected with the input end of the edge roller track through a group of guide plates.

[0012] Further, the edge roller track is a side U-shaped track, and a conveying roller is arranged on the inner bottom surface of the side U-shaped edge roller track.

[0013] Further, a positioning pin is arranged on the top surface of the lower female die, and the positioning pin is used for limiting the ultra-high strength steel plate to be stamped.

[0014] A shape property gradient control method of ultra-high strength steel, characterized in that the method comprises the following steps:

[0015] The punched ultra-high strength steel plate is moved to the first heating furnace, preheated and kept for a period of time under nitrogen protection;

[0016] The preheated ultra-high strength steel plate is moved out of the first heating furnace, and is subjected to variable-thickness online rolling, so that the thickness of the ultra-high strength steel plate has a gradient;

[0017] The rolled ultra-high strength steel plate is moved to the second heating furnace, and is continuously heated and kept for a period of time under nitrogen protection, so that the plate is austenitized;

[0018] The red-hot plate after austenitization is quickly transferred to the position to be stamped of the stamping device, and is subjected to stamping and partition quenching.

[0019] Further, the heating temperature in the first heating furnace is 720-760 DEG C, the holding time is t=d*n; the heating temperature in the second heating furnace is 910-940 DEG C, the holding time is t=d*m; wherein: d is the thickness of the plate, unit: mm; t is the holding time, unit: s; n and m are both constants, the value of n is 60-65, the value of m is 100-110.

[0020] Further, the second heating furnace is provided with a plurality of groups of shaping rollers; the upper punch and the lower die of the stamping device are uniformly provided with a plurality of cooling water channels, each cooling water channel is controlled independently, and each cooling water channel is monitored in temperature by a thermocouple.

[0021] The present application has the following beneficial effects:

[0022] 1. The process control based on the variable thickness online rolling, austenitizing synchronous shaping stress relief and partition quenching to regulate the martensite content in the hot forming process, effectively realizes the synchronous control of the rigidity, strength and toughness gradient of the ultra-high strength steel, and provides a solution for the optimized design of the automobile safety parts.

[0023] 2. The red-hot plate after austenitizing is quickly transferred to the position to be stamped of the stamping device by using the edge roller track instead of the mechanical arm. The mutual cooperation of the conveying speed of the edge roller track and the quick withdrawal of the edge roller track under the driving of the telescopic device shortens the plate transfer time, avoids the dissipation of the plate temperature during the transfer, reduces the oxidation of the plate surface, effectively reduces the initial heating temperature, and improves the forming efficiency and quality.

[0024] 3. The upper punch and the lower die of the stamping device are uniformly provided with a plurality of cooling water channels, each cooling water channel is controlled independently, and each cooling water channel is monitored in temperature by a thermocouple. In the stamping quenching process, the cooling speed is accurately fed back, so that the cooling rate of each cooling water channel is accurately adjusted, the ultra-high strength steel with strength gradient is obtained, and the light weight requirement of the automobile is met. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the present application;

[0026] Figure 2 It is a schematic diagram of the edge roller track and the telescopic device of the present application;

[0027] Figure 3 It is a schematic diagram of the upper punch and the lower die of the present application.

[0028] In the diagram: 1-Ultra-high strength steel plate; 2-Robot arm; 3-Transfer frame; 4-First heating furnace; 5-Rolling device; 6-Second heating furnace; 7-Side roller track; 8-Punching device; 9-Telescopic device; 10-Connecting plate; 11-Guide plate; 12-Hydraulic cylinder / pneumatic cylinder; 13-Lower die; 14-Positioning pin; 15-Upper punch; 16-Thermocouple; 17-Cooling water channel; 18-L-shaped bracket; 19-Conveying roller. Detailed Implementation

[0029] The present invention will now be further described. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0030] Example 1

[0031] like Figure 1 As shown in the figure, this embodiment of the invention provides a shape gradient control device for ultra-high strength steel, including a conveyor frame 3, with conveyor rollers spaced apart along the length of the conveyor frame 3, allowing the sheet material to be processed to move on the conveyor frame 3. A first heating furnace 4, a rolling device 5, and a second heating furnace 6 are sequentially arranged on the conveyor frame 3 from the input end to the output end. The output end of the conveyor frame 3 is connected to a stamping device 8 via a side roller track 7. The first heating furnace 4 is used to preheat the ultra-high strength steel sheet 1; the rolling device 5 is used to roll the preheated sheet material online with varying thickness; the second heating furnace 6 is used to austenitize the rolled sheet material and simultaneously shape and relieve stress; the stamping device 8 is used to stamp and quench the austenitized red-hot sheet material in sections. In this embodiment, the second heating furnace 6 is equipped with several sets of shaping rollers, which enable the sheet material to remove residual stress under shaping conditions. Based on the process control of variable thickness online rolling, simultaneous austenitization and stress relief, and zoned quenching to regulate martensite content during hot forming, the synchronous control of the stiffness, strength, and toughness gradients of ultra-high strength steel is effectively achieved, providing a solution for the optimized design of automotive safety components.

[0032] like Figure 3 As shown, the stamping device 8 includes a matching upper punch 15 and a lower die 13. Several cooling channels 17 are evenly distributed inside the upper punch 15 and the lower die 13. Each cooling channel 17 is individually controlled, and its temperature is monitored by a thermocouple 16. The thermocouple 16 provides feedback through an integrated controller, achieving precise feedback on the cooling rate, thereby accurately adjusting the cooling rate of each cooling channel 17, effectively completing the stamping and quenching process to obtain ultra-high strength steel with a strength gradient. The output end of the conveyor frame 3 is connected to the lower die 13 of the stamping device 8 via a set of guide plates 11. In this embodiment, nine cooling channels 17 are evenly distributed inside the upper punch 15 and the lower die 13.

[0033] The telescopic device 9 is installed on the side surface of the lower die 13, and the output end of the telescopic device 9 is connected with the edge roller track 7, the length of the edge roller track 7 is greater than the length of the lower die 13, and the telescopic device 9 can control the edge roller track 7 to move close to or away from each other. Figure 2 As shown in the figure, the connecting plate 10 is provided with the telescopic device 9, the telescopic device 9 includes an L-shaped support 18 fixedly connected with the connecting plate 10, a hydraulic cylinder or a pneumatic cylinder 12 is connected with the L-shaped support 18, and the output end of the hydraulic cylinder or the pneumatic cylinder 12 is connected with the edge roller track 7. In the embodiment, the edge roller track 7 is a side U-shaped track, and the inner bottom surface of the side U-shaped track is provided with a conveying roller 19. The edge roller track 7 is used to replace the mechanical arm to quickly transfer the austenitized red-hot plate to the stamping position of the stamping device 8. Through the cooperation of the conveying speed of the edge roller track 7 and the quick withdrawal of the edge roller track 7 under the driving of the telescopic device 9, the plate transfer time is shortened, the temperature dissipation of the plate during the transfer is avoided, the surface oxidation of the plate is reduced, the initial heating temperature can be effectively reduced, and the forming efficiency and quality are improved.

[0034] The top surface of the lower die 13 is provided with a compressible positioning pin 14, the positioning pin 14 is used for limiting the ultra-high strength steel plate 1 to be stamped, and the positioning pin 14 is used for limiting the ultra-high strength steel plate 1 to be stamped. When the edge roller track 7 quickly transfers the red-hot plate to the stamping device 8, the positioning pin 14 immediately acts, so that the plate can accurately enter the stamping area, and the stamping accuracy is ensured. The front half and the rear half of the edge roller track 7 are controlled by positive and reverse rotation respectively, the speed of the edge roller track 7 is uniformly reduced from the initial speed to 0 m / s; and the reverse conveying roller is supported by a damping material, so that the plate can be quickly stopped at the positioning pin, and the damage caused by the impact of the plate is eliminated.

[0035] Embodiment 2

[0036] Based on the same inventive concept as in embodiment 1, the present embodiment provides a shape gradient control method of ultra-high strength steel, which comprises the following steps:

[0037] The punched ultra-high strength steel plate is moved to the first heating furnace, preheated under nitrogen protection, the heating temperature is 720-760 DEG C, and the temperature is kept for a period of time; the holding time is t, t = d x n; in the formula: d is the thickness of the plate, unit: mm; the unit of t is s; n is a constant, and the value of n is 60-65.

[0038] The preheated ultra-high strength steel plate is moved out of the first heating furnace and is subjected to online rolling, so that the thickness of the ultra-high strength steel plate has a gradient.

[0039] The rolled ultra-high strength steel plate is moved to a second heating furnace, and heated under nitrogen protection, with a heating temperature of 910-940 DEG C, and kept for a period of time to make it austenitized; the holding time is t, t=d*m; in the formula: d is the thickness of the plate, unit: mm; t is the unit of s; m is a constant, the value of m is 100-110. The second heating furnace is provided with several groups of shaping rollers, so that the plate can remove residual stress under shaping conditions.

[0040] The red-hot plate after austenitizing is quickly transferred to the stamping position of the stamping device through the edge roller track, and is stamped and partition quenched.

[0041] Example 3

[0042] The embodiment of the application provides a shape gradient control method of ultra-high strength steel, and specifically comprises the following steps:

[0043] 1) preheating: the punched ultra-high strength steel plate is moved to a first heating furnace, preheated to 720-760 DEG C under nitrogen protection; and kept for a period of time, t=d*n; in the formula: d is the thickness of the plate, unit: mm; t is the unit of s; n is a constant, the value of n is 60-65.

[0044] 2) variable-thickness online rolling: the ultra-high strength steel plate is moved out of the first heating furnace through the conveying roller, and is online rolled to make its thickness have a gradient; the deformation amount of the variable-thickness online rolling part is controlled to be 30%-50%, and the thinning area is not more than 30%.

[0045] 3) austenitizing and synchronous shaping stress relief: the rolled ultra-high strength steel plate is moved to a second heating furnace, and heated under nitrogen protection, with a heating temperature of 910-940 DEG C, and kept for a period of time to make it austenitized; the holding time is t, t=d*m; in the formula: d is the thickness of the plate, unit: mm; t is the unit of s; m is a constant, the value of m is 100-110. The second heating furnace is provided with several groups of shaping rollers, so that the plate can remove residual stress under shaping conditions while keeping the geometric shape.

[0046] 4) transfer: the red-hot plate is quickly transferred to the stamping position of the stamping device through the edge roller track; from the lower roller conveying to the edge roller conveying. The edge roller track uniformly decreases from the initial speed 0.5 m / s to 0 m / s.

[0047] 5) Punching and partition quenching: when the positioning of the austenitized plate in the hot punching device is completed, the edge roller track is removed by the hydraulic cylinder / air cylinder (i.e. the set of edge roller tracks are away from each other), and the removal speed is ≤0.5 m / s; the closing and separation of the upper punch and the lower die in the punching device are realized. The upper punch is pressed down, the closed die is operated for hot punching; while the punch pressure is maintained, the upper punch and the lower die are cooled at a cooling rate by the cooling water channel, partition quenching is realized, and gradient microstructure performance is obtained. The cooling rate is 10℃ / s-50℃ / s.

[0048] 6) Piling: after the punching and partition quenching is completed, the set of edge roller tracks is controlled to be close to each other by the hydraulic cylinder / air cylinder, and the super high strength steel plate is continuously conveyed for piling.

[0049] Example 4

[0050] In the embodiments of the present application, a shape gradient control method of super high strength steel is provided, which specifically comprises the following steps:

[0051] 1) Punching: a 22MnB5 super high strength steel plate with a thickness of 2mm is selected and punched into 1000mm×500mm;

[0052] 2) Preheating: the punched super high strength steel plate is moved to the first heating furnace, preheated to 720℃ under nitrogen protection, and kept for 120s;

[0053] 3) Variable thickness online rolling: the super high strength steel plate is moved out of the first heating furnace through the conveying roller, and online rolling is performed, so that the thickness of the plate within 10mm from the edge width is 1.2mm;

[0054] 4) Austenitizing and synchronous shaping and stress relieving: the rolled super high strength steel plate is moved to the second heating furnace, the plate is shaped by the shaping roller in the furnace, and heated to 920℃ under nitrogen protection; and kept for 200s;

[0055] 5) Transfer: the red-hot plate is quickly transferred to the punching position of the punching device by using the edge roller track, i.e. from the lower roller conveying to the edge roller conveying, and the edge roller track uniformly decreases from the initial speed of 0.5m / s to 0m / s during the transfer process.

[0056] 6) Punching and partition quenching: when the positioning of the austenitized plate in the hot punching device is completed, the edge roller track is removed by the hydraulic cylinder (i.e. the set of edge roller tracks move away from each other) at a removal speed of 0.2 m / s; the closing and separation of the upper punch and the lower die in the punching device are realized. The upper punch is pressed down, the closed die is operated for hot punching; while maintaining the pressure of the punch, the upper punch and the lower die are cooled at a cooling rate regulated by the cooling water channel, so that the cooling rate of the ultra-high strength steel is 15℃ / s within the edge width of 10 mm and the cooling rate of the central region is 40℃ / s, realizing partition quenching and obtaining the strength gradient of the same plate.

[0057] 7) After the punching and partition quenching is completed, the set of edge roller tracks is controlled to move close to each other by the hydraulic cylinder / air cylinder, and the ultra-high strength steel plate is continuously conveyed for stacking treatment.

[0058] Example 5

[0059] In the embodiments of the present application, a shape-property gradient control method of ultra-high strength steel is provided, which specifically comprises the following steps:

[0060] 1) Punching: a 27MnCrB5 ultra-high strength steel plate with a thickness of 3 mm is selected and punched into 1200 mm x 700 mm;

[0061] 2) Preheating: the punched ultra-high strength steel plate is moved to the first heating furnace and preheated to 740℃ under nitrogen protection, and kept for 180s;

[0062] 3) Variable thickness online rolling: the ultra-high strength steel plate is moved out of the first heating furnace through the conveying roller and rolled online, so that the central region of the plate within a width of 100 mm is thinned to 1.5 mm;

[0063] 4) Austenitizing and synchronous shaping and stress relieving: the rolled ultra-high strength steel plate is moved to the second heating furnace, the plate is shaped by the shaping roller in the furnace, and heated to 930℃ under nitrogen protection; and kept for 330s;

[0064] 5) Transfer: the red-hot plate is quickly transferred to the punching position of the punching device by the edge roller track, i.e. from the lower roller conveying to the edge roller conveying, and the edge roller track uniformly decreases from the initial speed of 0.5 m / s to 0 m / s during the transfer process.

[0065] 6) Punching and partition quenching: when the positioning of the austenitized plate in the hot punching device is completed, the edge roller track is removed by the hydraulic cylinder (i.e. the set of edge roller tracks move away from each other) at a speed of 0.4 m / s; the closing and separation of the upper punch and the lower die in the punching device are realized. The upper punch is pressed down, the closed die is operated for hot punching; while maintaining the pressure of the punch, the upper punch and the lower die are cooled at a cooling rate of 50℃ / s within 200mm of the center area of the super high strength steel and 15℃ / s at the edge through the cooling water channel, realizing partition quenching and obtaining the same plate strength gradient.

[0066] 7) After the punching and partition quenching is completed, the set of edge roller tracks is controlled to move close to each other by the hydraulic cylinder / air cylinder, and the super high strength steel plate is continuously conveyed for stacking treatment.

[0067] Example 6

[0068] The embodiment of the present application provides a shape-property gradient control method of super high strength steel, which specifically comprises the following steps:

[0069] 1) Punching: a 37MnB4 super high strength steel plate with a thickness of 1.5 mm is selected and punched into 1400 mm x 500 mm;

[0070] 2) Preheating: the punched super high strength steel plate is moved to the first heating furnace and preheated to 760℃ under nitrogen protection, and kept for 90s;

[0071] 3) Variable thickness online rolling: the super high strength steel plate is moved out of the first heating furnace through the conveying roller and subjected to online rolling, so that the plate is thinned to 1mm within a width of 20mm from the edge;

[0072] 4) Austenitizing and synchronous shaping and stress relieving: the rolled super high strength steel plate is moved to the second heating furnace, the plate is shaped by the shaping roller in the furnace, and heated to 940℃ under nitrogen protection; and kept for 165s;

[0073] 5) Transfer: the red-hot plate is quickly transferred to the punching position of the punching device by the edge roller track, i.e. from the lower roller conveying to the edge roller conveying, and the edge roller track uniformly decreases from the initial speed of 0.5m / s to 0m / s during the transfer process.

[0074] 6) Punching and partition quenching: when the positioning of the austenitized plate in the hot punching device is completed, the edge roller track is removed by the pneumatic cylinder (i.e. the set of edge roller tracks move away from each other) and the removal speed is 0.5 m / s; the closing and separation of the upper punch and the lower die in the punching device is realized. The upper punch is pressed down, the closed die performs hot punching operation; while maintaining the pressure of the punch, the upper punch and the lower die are cooled by the cooling water channel to adjust the cooling rate, so that the cooling rate of the ultra-high strength steel within 20 mm from the edge width is 60 ℃ / s, and the cooling rate of the edge is 20 ℃ / s, realizing partition quenching and obtaining the same plate strength gradient.

[0075] 7) After the punching and partition quenching is completed, the set of edge roller tracks is controlled to move close to each other by the hydraulic cylinder / pneumatic cylinder, and the ultra-high strength steel plate continues to be conveyed for stacking treatment.

[0076] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and modifications can be made, and these improvements and modifications should also be considered as the protection scope of the present application.

Claims

1. A method for controlling the shape gradient of ultra-high strength steel, the shape gradient control device comprising a conveyor frame, wherein conveyor rollers are spaced apart along the length of the conveyor frame, characterized in that, The first heating furnace, the rolling device, and the second heating furnace are sequentially arranged on the conveyor from the input end to the output end; The output end of the conveyor frame is connected to the stamping device via a side roller track; The stamping device includes a matching upper punch and a lower die. A telescopic device is installed on the side of the lower die facing each other, and the output end of the telescopic device is connected to the side roller track. The upper punch and the lower die are evenly arranged with several cooling water channels inside. Each cooling water channel is controlled individually and its temperature is monitored by a thermocouple. Connecting plates are respectively installed on the sides of the lower die facing each other, and telescopic devices are provided on the connecting plates; the telescopic device includes an L-shaped bracket fixedly connected to the connecting plate, and a hydraulic cylinder or a pneumatic cylinder is connected to the L-shaped bracket; The telescopic device can control the group of side roller tracks to move closer or further apart; the side roller tracks are U-shaped, and conveyor rollers are laid on the inner bottom surface of the U-shaped side roller tracks; Inside the first heating furnace, the punched ultra-high strength steel plates are preheated and held at that temperature for a period of time under nitrogen protection. The rolling device moves the preheated ultra-high strength steel plate to perform variable thickness online rolling, so that the thickness of the ultra-high strength steel plate has a gradient; The second heating furnace is equipped with several sets of shaping rollers. The conveying rollers move the rolled ultra-high strength steel plate into the second heating furnace, where it is heated and held at a certain temperature for a period of time under nitrogen protection to austenitize it. The austenitized red-hot sheet is quickly transferred to the stamping position of the stamping device via the side roller track. While maintaining the punch pressure, the upper punch and lower die adjust the cooling rate of the ultra-high strength steel through the cooling water channel, so that the cooling rate of the ultra-high strength steel in the edge area is G1 and the cooling rate in the center area is G2, thereby achieving partitioned quenching and obtaining the same sheet with a strength gradient. The punched ultra-high strength steel plate is transferred to the first heating furnace and preheated to 720~760℃ under nitrogen protection; and held at that temperature for a period of time, t=d×n; where: d is the thickness of the plate in mm; t is in s; n is a constant, and the value of n is 60~65; The ultra-high strength steel plate is moved out of the first heating furnace by conveyor rollers and rolled online to give it a gradient thickness; the deformation of the variable thickness online rolling part is controlled at 30%~50%, while the thinning area does not exceed 30%; The rolled ultra-high strength steel plate is transferred to the second heating furnace and heated under nitrogen protection at a temperature of 910~940℃. It is then held at this temperature for a period of time to austenitize it. The holding time is t, where t = d × m. In the formula, d is the thickness of the plate in mm, t is in seconds, and m is a constant with a value of 100~110. The red-hot sheet metal is quickly transferred to the stamping position of the stamping device using the side roller track; the conveying method changes from the lower roller to the side roller; the side roller track decreases uniformly from an initial speed of 0.5m / s to 0m / s; When the austenitized sheet metal is positioned in the hot stamping device, the side roller track is removed by a hydraulic cylinder / pneumatic cylinder, and the removal speed is ≤0.5m / s; The upper punch and lower die in the stamping device are closed and separated; the upper punch is pressed down, and the die is closed for hot stamping; while maintaining the punch pressure, the upper punch and lower die are cooled by adjusting the cooling rate through cooling water channels to achieve zoned quenching and obtain gradient microstructure properties; the cooling rate is 10℃ / s~50℃ / s. After stamping and partition quenching are completed, the hydraulic cylinder / pneumatic cylinder controls the side roller tracks to move closer to each other and continue to transport ultra-high strength steel plates for stacking.

2. The shape gradient control device and control method according to claim 1, characterized in that, The output end of the conveyor frame is connected to the input end of the side roller track via a set of guide plates.

3. The shape gradient control device control method according to claim 1, characterized in that, The top surface of the lower die is provided with a positioning pin, which is used to limit the ultra-high strength steel plate to be stamped.

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