CN211757698U - Shape gradient control device of ultrahigh-strength steel - Google Patents

Abstract

The utility model discloses a shape gradient control device for ultra-high-strength steel. The output end of the frame is connected with the punching device; the punching device includes a matching upper punch and a lower punch, a telescopic device is installed on the side of the lower punch facing each other, and the output end of the expansion device is connected to the side roller track; Several cooling water channels are evenly arranged inside the lower die, each cooling water channel is controlled independently, and the temperature of each cooling water channel is monitored by a thermocouple. Effectively realize the synchronous control of the gradient of stiffness, strength and toughness of ultra-high-strength steel sheets, so that the shape and properties of ultra-high-strength steel have gradients, and achieve lightweight while ensuring stiffness design requirements.

Description

A shape gradient control device for ultra-high strength steel

technical field

The utility model belongs to the technical field of hot stamping and particularly relates to a shape gradient control device of ultra-high strength steel.

Background technique

The automobile industry is one of the five pillar industries of my country's national economy and the largest carrier of high-tech. Under the premise of ensuring safety performance, by introducing lightweight material structural parts into the body, the body mass can be reduced, the fuel efficiency can be improved, and the maintenance cost of the vehicle can be reduced.

Ultra-high-strength steel is a kind of steel with ultra-high tensile strength (above 1380Mpa) and its structure is martensite. Because of its low cost, high tensile strength, and obvious weight reduction benefits, it has become more and more popular in the automotive industry in recent years. of favor. Ultra-high-strength steel plates are generally manufactured by hot forming technology. This technology is to heat ultra-high-strength steel materials to austenitize them, and then send them into hot stamping dies with cooling water channels through robots and other equipment for stamping and preservation. Press hardening to form hot stamped parts with high strength and precision.

Chinese invention patent CN201510096852.X, "A Hot Stamping Method for Gradient Distribution of Properties of High-strength Steel Parts", proposes two heating and quenching cooling methods to obtain hot stamping parts with different mechanical properties. Disadvantages of this process The process is relatively complex, the production efficiency is low, and it is not suitable for large-scale production. Chinese invention patent CN201410110908.8, "A method of processing high-strength steel hot stamping parts", proposes that parts with uniform properties after hot stamping should be partially tempered or annealed, and the heat conduction of the sheet material is used to achieve the return Gradient changes in fire or annealing temperature to achieve gradient changes in performance. This process requires specially designed induction heating coils, and the parts are deformed during quenching heating.

At present, the hot forming of ultra-high-strength steel is generally to manufacture steel plates with the same wall thickness, and the achieved performance gradient is also homogeneous. The demand for parts is increasing. However, only the strength problem can be changed by heat treatment, and the stiffness problem cannot be solved. At present, there is no published research report on the hot stamping technology with gradient changes in strength and stiffness.

SUMMARY OF THE INVENTION

The utility model provides a shape gradient control device of ultra-high-strength steel, which solves the technical problem of shape gradient change in hot stamping technology.

In order to solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a shape gradient control device of ultra-high strength steel, comprising a conveying frame, and conveying rollers are arranged at intervals along the length direction of the conveying frame, and the conveying frame is A first heating furnace, a rolling device and a second heating furnace are arranged between the input end and the output end in sequence; the output end of the conveying frame is connected with the punching device; the punching device includes matching upper punches and lower punches , a telescopic device is installed on the side of the lower concave die facing each other, and the output end of the telescopic device is connected to the side roller track; a number of cooling water channels are evenly arranged inside the upper punch and the lower concave die, and each cooling water channel is independently controlled, and The temperature of each cooling channel is monitored by thermocouples.

Further, several sets of shaping rollers are arranged in the second heating furnace. It plays the role of removing the residual stress of the plate under the setting conditions.

Further, connecting plates are respectively installed on the side faces of the lower concave die facing each other, and a telescopic device is provided on the connecting plates.

Further, the telescopic device includes an L-shaped bracket fixedly connected with the connecting plate, and a hydraulic cylinder or a pneumatic cylinder is connected to the L-shaped bracket.

Further, the output end of the conveying frame and the input end of the side roller track are connected by a set of guide plates.

Further, the side roller track is of a side U-shape, and conveying rollers are laid on the inner bottom surface of the side U-shape side roller track.

Further, a positioning pin is provided on the top surface of the lower concave die, and the positioning pin is used to limit the ultra-high-strength steel sheet to be punched.

Beneficial effects achieved by the utility model:

1. Based on the process control of variable thickness on-line rolling, austenitizing synchronous shaping stress relief and zone quenching to control martensite content in the hot forming process, the synchronous control of the stiffness, strength and toughness gradients of ultra-high strength steel is effectively realized. The optimal design of automotive safety parts provides a solution.

2. The austenitized red-hot plate is quickly transferred to the to-be-stamped position of the stamping device by using the side roller track instead of the mechanical arm. Through the cooperation of the conveying speed of the side roller track and the rapid withdrawal of the side roller track driven by the telescopic device, the transfer time of the plate is shortened, the dissipation of the plate temperature during the transfer is avoided, and the surface oxidation of the plate is also reduced, which can effectively reduce the Initial heating temperature to improve forming efficiency and quality.

3. Several cooling water channels are evenly arranged inside the upper punch and lower die of the stamping device, each cooling channel is controlled separately, and each cooling channel is monitored by a thermocouple for temperature. In the process of stamping and quenching, accurate feedback of the cooling rate is realized, so as to accurately adjust the cooling rate of each cooling water channel, and obtain ultra-high-strength steel with strength gradient to meet the lightweight requirements of automobiles.

Description of drawings

Fig. 1 is the structural representation of the present invention;

Fig. 2 is the schematic diagram of the side roller track and the telescopic device of the present invention;

FIG. 3 is a schematic diagram of the upper punch and the lower die according to the present invention.

In the figure: 1-Ultra-high strength steel plate; 2-Robot; 3-Transfer frame; 4-First heating furnace; 5-Rolling device; 6-Second heating furnace; 7-Side roller track; 8-Stamping device ; 9- telescopic device; 10- connecting plate, 11- guide plate; 12- hydraulic cylinder/pneumatic cylinder; 13- lower die; 14- locating pin; 15- upper punch; 16- thermocouple; 17- cooling water channel ; 18-L-shaped bracket; 19-conveyor roller.

Detailed ways

The present utility model will be further described below in conjunction with the accompanying drawings. The following examples are only used to illustrate the technical solutions of the present invention more clearly, and cannot be used to limit the protection scope of the present invention.

Example 1

As shown in FIG. 1, an embodiment of the present invention provides a shape gradient control device for ultra-high strength steel, which includes a conveying frame 3, and conveying rollers are arranged at intervals along the length direction of the conveying frame 3, and the sheet to be processed can be placed in the conveying frame. 3 to move on. A first heating furnace 4 , a rolling device 5 and a second heating furnace 6 are arranged in sequence from the input end to the output end of the transfer frame 3 . The first heating furnace 4 is used for preheating the ultra-high strength steel sheet 1; the rolling device 5 is used for on-line rolling of the preheated sheet to change the thickness; the second heating furnace 6 is used for rolling the rolled sheet. Intensifying and simultaneous shaping and stress relief; stamping device 8 is used for stamping and zone quenching of austenitized red-hot plate. In this embodiment, the second heating furnace 6 is provided with several sets of shaping rollers, which play the role of enabling the plate to remove residual stress under shaping conditions. Based on the process control of variable thickness on-line rolling, austenitizing synchronous shaping stress relief and zone quenching to control martensite content in the hot forming process, the synchronous control of the stiffness, strength and toughness gradients of ultra-high strength steel is effectively realized, which is beneficial to automobile safety. The optimal design of parts provides a solution.

As shown in FIG. 3 , the punching device 8 includes a matching upper punch 15 and a lower punch 13 , a plurality of cooling channels 17 are evenly arranged inside the upper punch 15 and the lower punch 13 , and each cooling channel 17 is individually controlled, and The temperature of each cooling channel 7 is monitored by a thermocouple 16 . The thermocouple 16 realizes the accurate feedback of the cooling rate through the feedback of the integrated controller, so as to accurately adjust the cooling rate of each cooling water channel 17, effectively complete the stamping and quenching, and obtain ultra-high strength steel with strength gradient. The output end of the transfer frame 3 is connected with the lower die 13 of the punching device 8 through a set of guide plates 11 . In this embodiment, nine cooling water channels 17 are arranged inside the upper punch 15 and the lower die 13 .

A telescopic device 9 is installed on the side of the lower die 13 facing each other. The output end of the expansion device 9 is connected to the side roller track 7. The length of the side roller track 7 is greater than the length of the lower die 13. The expansion device 9 can control the set of side roller tracks. 7 are close to each other or far away from each other. Specifically, connecting plates 10 are respectively installed on the side faces of the lower die 13 facing each other. As shown in FIG. 2 , a telescopic device 9 is provided on the connecting plate 10. The telescopic device 9 includes an L-shaped bracket 18 that is fixedly connected to the connecting plate. The hydraulic cylinder or the pneumatic cylinder 12 is connected to the type bracket 18 , and the output end of the hydraulic cylinder or the pneumatic cylinder 12 is connected with the side roller track 7 . In this embodiment, the side roller track 7 is a side U-shaped, and the inner bottom surface of the side U-shaped side roller track is laid with conveying rollers 19 . The austenitized red-hot plate is quickly transferred to the position to be punched by the punching device 8 by using the side roller track 7 instead of the robot arm. Through the mutual cooperation of the conveying speed of the side roller track 7 and the rapid withdrawal of the side roller track 7 driven by the telescopic device 9, the transfer time of the plate is shortened, the dissipation of the plate temperature during the transfer is avoided, and the surface oxidation of the plate is also reduced. It can effectively reduce the initial heating temperature and improve the forming efficiency and quality.

A compressible positioning pin 14 is provided on the top surface of the lower die 13. The positioning pin 14 is used to limit the ultra-high-strength steel sheet 1 to be punched. Using light sensing or position sensing, when the side roller track 7 quickly transfers the red-hot sheet When entering the punching device 8, the positioning pins 14 act immediately, so that the plate can accurately enter the area to be punched, and the accuracy of punching is ensured. The rollers of the first half and the second half of the side roller track 7 are controlled in forward and reverse directions respectively, and the side roller track 7 is uniformly reduced from the initial speed to 0m/s; and the reverse conveying roller is supported by the damping material, which makes the plate stop quickly. At the locating pin, the damage caused by the impact of the sheet is eliminated.

Example 2

Based on the same inventive concept as Embodiment 1, this embodiment provides a formability gradient control method for ultra-high strength steel, which includes the following steps:

Move the punched ultra-high-strength steel sheet to the first heating furnace, pre-heat under nitrogen protection, the heating temperature is 720-760 ℃, and keep for a period of time; the holding time is t, t=d×n; In the formula: d is the thickness of the plate, the unit is mm; the unit of t is s; n is a constant, and the value of n is 60-65.

The preheated ultra-high-strength steel sheet is removed from the first heating furnace and rolled on-line, so that the thickness of the ultra-high-strength steel sheet has a gradient.

Move the rolled ultra-high-strength steel sheet to the second heating furnace, continue heating under nitrogen protection, the heating temperature is 910-940 ° C, and keep for a period of time to make it austenitic; the holding time is t, t=d×m; in the formula: d is the thickness of the plate, the unit is mm; the unit of t is s; m is a constant, and the value of m is 100-110. Several sets of shaping rollers are arranged in the second heating furnace, so that the plate can remove residual stress under shaping conditions.

The austenitized red-hot plate is quickly transferred to the to-be-stamped position of the stamping device through the side roller track for stamping and zone quenching.

Example 3

The present embodiment provides a method for controlling the shape gradient of ultra-high strength steel, which specifically includes the following steps:

1) Preheating: move the punched ultra-high-strength steel sheet to the first heating furnace, and preheat it to 720-760°C under nitrogen protection; and keep it for a period of time, t=d×n; where: d is the thickness of the plate, the unit is mm; the unit of t is s; n is a constant, and the value of n is 60 to 65.

2) On-line rolling with variable thickness: The ultra-high-strength steel sheet is moved from the first heating furnace through the transfer roller, and rolled on-line to make its thickness gradient; the deformation of some areas of on-line rolling with variable thickness is controlled at 30% to 50%, while the thinning area does not exceed 30%.

3) Austenitizing and simultaneous setting stress relief: move the rolled ultra-high-strength steel sheet to the second heating furnace, continue heating under nitrogen protection, the heating temperature is 910-940 ° C, and keep it for a period of time, Make it austenitizing; the holding time is t, t=d×m; in the formula: d is the thickness of the plate, the unit is mm; the unit of t is s; m is a constant, and the value of m is 100-110. Several sets of setting rollers are arranged in the second heating furnace to austenitize the sheet and remove residual stress while maintaining the geometric shape.

4) Transfer: Use the side roller track to quickly transfer the red-hot plate to the position to be punched by the punching device; from the bottom roller conveying to the side roller conveying. The track of the side rollers decreases uniformly from the initial speed of 0.5m/s to 0m/s.

5) Stamping and zone quenching: When the positioning of the austenitized sheet in the hot stamping device is completed, the side roller tracks are removed by hydraulic cylinders/pneumatic cylinders (that is, the set of side roller tracks are kept away from each other), and the The removal speed is less than or equal to 0.5m/s; the closure and separation of the upper punch and the lower die in the stamping device are realized. The upper punch is pressed down, and the die is closed for hot stamping operation; while the punch pressure is maintained, the cooling rate of the upper punch and the lower punch is adjusted through the cooling water channel to achieve zone quenching and obtain gradient microstructure and properties. The cooling rate is 10°C/s to 50°C/s.

6) Stacking: When the stamping and zone quenching are completed, the hydraulic cylinder/air pressure cylinder controls the set of side roller tracks to approach each other, and continues to transport ultra-high-strength steel sheets for stacking processing.

Example 4

The present embodiment provides a method for controlling the shape gradient of ultra-high strength steel, which specifically includes the following steps:

1) Punching: Select 2mm thick 22MnB5 ultra-high-strength steel sheet, and punch it 1000mm×500mm;

2) Preheating: move the punched ultra-high-strength steel sheet to the first heating furnace, preheat it to 720°C under nitrogen protection, and keep it for 120s;

3) On-line rolling with variable thickness: The ultra-high-strength steel sheet is moved from the first heating furnace through the conveying roller, and the on-line rolling is carried out, so that the thickness of the sheet within 10 mm of the edge width is 1.2 mm;

4) Austenitizing and simultaneous setting stress relief: move the rolled ultra-high-strength steel sheet to the second heating furnace, shape the sheet by the setting roller in the furnace, and heat it to 920 ℃ under nitrogen protection; and Keep warm for 200s;

5) Transfer: Use the side roller track to quickly transfer the red-hot plate to the punching position of the stamping device, that is, from the bottom roller conveying to the side roller conveying. During the transfer process, the side roller track is uniformly reduced from the initial speed of 0.5m/s to 0m /s.

6) Stamping and zone quenching: When the positioning of the austenitized sheet in the hot stamping device is completed, the side roller tracks are removed by a hydraulic cylinder (that is, the set of side roller tracks are far away from each other), and the removal speed is 0.2m/s; realize the closing and separation of the upper punch and the lower die in the stamping device. The upper punch is pressed down, and the die is closed for hot stamping operation; while maintaining the punch pressure, the cooling rate of the upper punch and the lower die is adjusted through the cooling water channel, so that the cooling rate of the ultra-high strength steel within 10mm of the edge width The cooling rate in the central area is 15°C/s, and the cooling rate in the central area is 40°C/s, which realizes zone quenching and obtains the strength gradient of the same sheet.

7) When the stamping and zone quenching are completed, the hydraulic cylinder/air pressure cylinder controls the set of side roller tracks to approach each other, and continues to transport ultra-high-strength steel sheets for stacking processing.

Example 5

The present embodiment provides a method for controlling the shape gradient of ultra-high strength steel, which specifically includes the following steps:

1) Punching: select 3mm thick 27MnCrB5 ultra-high strength steel plate, and punch it 1200mm×700mm;

2) Preheating: move the punched ultra-high-strength steel sheet to the first heating furnace, preheat it to 740°C under nitrogen protection, and keep it for 180s;

3) On-line rolling with variable thickness: The ultra-high-strength steel plate is moved out of the first heating furnace through the transfer roller, and rolled on-line, so that the width of the central area of the plate is reduced to 1.5mm within 100mm;

4) Austenitization and simultaneous setting stress relief: move the rolled ultra-high-strength steel sheet to the second heating furnace, shape the sheet by the setting roller in the furnace, and heat it to 930 ℃ under nitrogen protection; and Keep warm for 330s;

5) Transfer: Use the side roller track to quickly transfer the red-hot plate to the punching position of the stamping device, that is, from the bottom roller conveying to the side roller conveying. During the transfer process, the side roller track is uniformly reduced from the initial speed of 0.5m/s to 0m /s.

6) Stamping and zone quenching: When the positioning of the austenitized sheet in the hot stamping device is completed, the side roller tracks are removed by a hydraulic cylinder (that is, the set of side roller tracks are far away from each other), and the removal speed is 0.4m/s; realize the closing and separation of the upper punch and the lower die in the stamping device. The upper punch is pressed down, and the die is closed for hot stamping operation; while maintaining the punch pressure, the cooling rate of the upper punch and the lower punch is adjusted through the cooling water channel, so that the ultra-high strength steel is cooled within 200mm of the central area. The cooling rate of the edge is 50°C/s and the cooling rate of the edge is 15°C/s to realize zone quenching and obtain the strength gradient of the same sheet.

7) When the stamping and zone quenching are completed, the hydraulic cylinder/air pressure cylinder controls the set of side roller tracks to approach each other, and continues to transport ultra-high-strength steel sheets for stacking processing.

Example 6

The present embodiment provides a method for controlling the shape gradient of ultra-high strength steel, which specifically includes the following steps:

1) Punching: choose 1.5mm thick 37MnB4 ultra-high strength steel plate, and punch it 1400mm×500mm;

2) Preheating: move the punched ultra-high-strength steel sheet to the first heating furnace, preheat it to 760°C under nitrogen protection, and keep it for 90s;

3) On-line rolling with variable thickness: The ultra-high-strength steel sheet is moved out of the first heating furnace through the transfer roller, and rolled on-line to reduce the thickness of the sheet to 1 mm within 20 mm from the edge width;

4) Austenitizing and simultaneous setting stress relief: move the rolled ultra-high-strength steel sheet to the second heating furnace, shape the sheet by the setting rollers in the furnace, and heat it to 940 ℃ under nitrogen protection; and Keep warm for 165s;

5) Transfer: Use the side roller track to quickly transfer the red-hot plate to the punching position of the stamping device, that is, from the bottom roller conveying to the side roller conveying. During the transfer process, the side roller track is uniformly reduced from the initial speed of 0.5m/s to 0m /s.

6) Stamping and zone quenching: When the positioning of the austenitized sheet in the hot stamping device is completed, the side roller tracks are removed by a pneumatic cylinder (that is, the set of side roller tracks are far away from each other), and the removal speed is 0.5m/s; realize the closing and separation of the upper punch and the lower die in the stamping device. The upper punch is pressed down, and the die is closed for hot stamping operation; while maintaining the punch pressure, the cooling rate of the upper punch and the lower punch is adjusted through the cooling water channel, so that the ultra-high strength steel is within 20mm of the width from the edge. The cooling rate is 60°C/s, and the cooling rate at the edge is 20°C/s, to realize zone quenching and obtain the strength gradient of the same sheet.

7) When the stamping and zone quenching are completed, the hydraulic cylinder/air pressure cylinder controls the set of side roller tracks to approach each other, and continues to transport ultra-high-strength steel sheets for stacking processing.

The above is only the preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, some improvements and deformations can be made without departing from the technical principle of the present invention. These improvements and deformation should also be regarded as the protection scope of the present invention.

Claims (7)

1. The shape gradient control device for the ultrahigh-strength steel comprises a conveying frame, wherein conveying rollers are arranged at intervals along the length direction of the conveying frame, and is characterized in that a first heating furnace, a rolling device and a second heating furnace are sequentially arranged on the conveying frame from an input end to an output end;

the output end of the conveying frame is connected with the stamping device through the edge roller track;

the stamping device comprises an upper male die and a lower female die which are matched, a telescopic device is arranged on the side surface opposite to the lower female die, and the output end of the telescopic device is connected with the edge roller track;

and a plurality of cooling water channels are uniformly distributed in the upper male die and the lower female die, each cooling water channel is independently controlled, and each cooling water channel is monitored by a thermocouple.

2. The apparatus according to claim 1, wherein a plurality of sets of shaping rollers are provided in said second heating furnace.

3. A shape gradient control device for ultra-high strength steel according to claim 1, wherein connecting plates are respectively installed on the side surfaces of the lower concave die which are arranged opposite to each other, and telescopic devices are arranged on the connecting plates.

4. A shape gradient control device of ultra-high strength steel according to claim 3, wherein the telescopic device comprises an L-shaped bracket fixedly connected with the connecting plate, and a hydraulic cylinder or a pneumatic cylinder is connected to the L-shaped bracket.

5. A shape gradient control device of ultra-high strength steel according to claim 1, wherein the output end of the conveying frame is connected with the input end of the edge roller track through a group of guide plates.

6. The apparatus for controlling shape gradient of ultra-high strength steel as claimed in claim 1, wherein the side roller rail is a side U-shape, and a conveying roller is laid on an inner bottom surface of the side U-shape side roller rail.

7. The apparatus according to claim 1, wherein a positioning pin is provided on the top surface of the lower cavity die, and the positioning pin is used for limiting the ultra-high strength steel plate to be stamped.

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