CN103949552B - Optimum temperature control device for thermoforming of high-strength steel - Google Patents

Abstract

The invention discloses an optimal temperature control device for hot forming of high-strength steel, which aims to overcome the problem of insufficient strength of parts caused by poor hot-formability of high-strength steel material and insufficient cooling rate. It includes upper mechanism, lower mechanism and unloading mechanism. The upper mechanism is located directly above the lower mechanism, and the unloading mechanism is located on the right side of the lower mechanism. The lower mechanism includes a lower heat conduction plate (4), a lower mold base (5), a heat sink frame (7), a heat dissipation mechanism and a lower thermocouple (13). The lower thermocouples (13) are respectively installed in the grooves on the upper surface of the lower heat conduction plate (4), and each lower thermocouple (13) is connected in the groove of the lower heat conduction plate (4) by spot welding, and the lower heat conduction plate (4) The lower surface of the lower mold base (5) is in contact with the upper surface of the lower mold base (5) and is connected by welding, the lower surface of the lower mold base (5) is in contact with the upper surface of the heat sink frame (7) and is connected by welding, the heat dissipation mechanism Located at the center of the lower part of the heat sink frame (7).

Description

Optimum temperature control device for hot forming of high-strength steel

technical field

The invention relates to a control device in the field of hot forming of high-strength steel, more precisely, the invention relates to an optimal temperature control device for hot forming of high-strength steel.

Background technique

In order to pursue the lightweight of the body, without changing the body specifications, the weight of the body structure can be realized by optimizing the body structure, updating the manufacturing and connection process of body parts, and replacing traditional low-strength steel with lightweight materials. For a long time, steel has been the basis of machine manufacturing. Although the amount of composite materials such as magnesium-aluminum alloys and plastics is increasing in the automobile manufacturing process, high-strength steels are characterized by their high weight reduction potential, high impact absorption energy, high fatigue strength, high formability and low plane anisotropy, etc. It has an irreplaceable position in the field of body lightweight materials. However, as the strength of the steel plate increases, its formability also deteriorates accordingly. Using the traditional stamping forming process will cause many problems such as severe springback, difficult forming, and easy cracking. Corresponding to the application of high-strength steel and the progress of lightweight technology is the improvement of sheet metal forming methods. Among them, hydroforming and internal high-pressure forming are important forming methods for high-strength materials, but the equipment they require is more complicated and expensive than ordinary punching machines. And it has the disadvantages of difficult use, maintenance, and maintenance, low industrial productivity, and limitations in the shape of formed parts, so it cannot be widely used in large-scale industrial production, and high-strength steel hot forming technology is a new type of forming technology that can solve the above problems . The hot forming process of high-strength steel in the existing industrial production is as follows: put the high-strength steel material cut on the cutting machine into the heating furnace to heat and keep it warm until the microstructure is completely austenitized, and then immediately transfer it to the water-cooled mold for stamping. And quenching under pressure, and finally obtain the formed parts with high strength, high hardness and no springback with a yield strength of more than 1000MPa at room temperature. Fig. 1 shows the process flow chart of hot forming of medium and high-strength steel in the existing industrial production. And there are three problems in existing technological process:

1. The temperature is too high when the sheet is formed, which is not the best forming temperature, the formability of the sheet is poor, and thermoforming defects such as wrinkling and cracking are prone to occur;

2. The cooling rate of the stamping die is insufficient, resulting in a low cooling rate of the sheet metal, and a certain amount of soft phase is contained in the material structure, which greatly reduces the mechanical properties of the formed part;

3. During the forming process, the high-temperature sheet material aggravates the wear on the surface of the forming die, which affects the forming accuracy.

Therefore, it is necessary to add a new device to the existing high-strength steel hot forming process to form the sheet within its optimum forming temperature range under the premise of ensuring the cooling rate of the sheet.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the problem of insufficient hot formability of high-strength steel material and insufficient cooling rate in the prior art, and provide an optimal temperature control device for high-strength steel hot forming.

In order to solve the above-mentioned technical problems, the present invention adopts the following technical solutions: the optimal temperature control device for hot forming of high-strength steel includes an upper mechanism, a lower mechanism and a discharge mechanism.

The upper mechanism is located directly above the lower mechanism, and the unloading mechanism is located on the right side of the lower mechanism.

The lower mechanism includes a lower heat conduction plate, a lower mold base, a heat sink frame, a heat dissipation mechanism and 9 to 17 lower thermocouples with the same structure.

9 to 17 lower thermocouples with the same structure are respectively installed in the grooves on the upper surface of the lower heat conduction plate, each lower thermocouple (13) is connected in the groove of the lower heat conduction plate (4) by spot welding, and the lower heat conduction plate (4) ) lower surface is in contact with the upper surface of the lower mold base (5) and is connected by welding, the lower surface of the lower mold base (5) is in contact with the upper surface of the heat sink frame (7) and is connected by welding, and the heat dissipation mechanism is located at Center the lower part of the heat sink frame (7).

The heat dissipation mechanism described in the technical solution includes a heat dissipation fan and a heat dissipation fan frame. The heat dissipation fan frame is a two-layer frame structure, the top of the heat dissipation fan frame is a protective cover for a ventilation net, and the middle layer of the cooling fan frame is a mesh compartment for a ventilation net. The center of the mesh compartment is provided with a central hole for installing a cooling fan, and the lower end of the cooling fan is inserted into the center hole of the mesh compartment and connected with the output end of the fan motor.

The lower heat conduction plate described in the technical proposal is a cuboid structural part, the length and width of the lower heat conduction plate are respectively the same as the length and width of the lower mold base, the lower heat conduction plate is made of copper material with good thermal conductivity, and the center of the upper surface of the lower heat conduction plate is There are two rows of grooves for installing the lower thermocouple at equal intervals of 200 mm, and the two rows of grooves are arranged perpendicular to each other, and there are through holes for arranging wires around the lower heat conducting plate.

The lower mold base described in the technical proposal is a cuboid structural part, and the middle part of the lower mold base is provided with 9 to 17 circular through holes parallel to each other, that is, the lower cooling water channel. The lower cooling water channel is arranged in two staggered layers. The diameter of the cooling channel is 40mm, the center-to-center distance between two adjacent lower cooling channels in each layer is 160mm, and the vertical center-to-center distance between the upper and lower cooling channels is 120mm.

The upper mechanism described in the technical solution includes 4 upper mold guide pillars with the same structure, an upper mold base, an upper heat conducting plate, and 9 to 17 upper thermocouples with the same structure. The lower end of the guide post of the upper mold is screwed to the threaded blind holes at the four corners of the upper surface of the upper mold base. The lower surface of the upper mold base is in contact with the upper surface of the upper heat conducting plate and connected by welding. The upper thermocouple is installed on the upper heat conducting plate. In the groove on the lower surface, the upper thermocouple is connected in the groove on the upper heat conducting plate by spot welding.

The upper mold base described in the technical proposal is a cuboid structural part, the length and width of the upper mold base are respectively the same as the length and width of the lower mold base, and the four corners of the upper surface of the upper mold base are provided with guide posts for connecting the upper mold base. There are 9 to 17 parallel circular through holes in the middle of the upper die base, that is, the upper cooling water channel. The cooling water channel is arranged in two layers. The diameter of the upper cooling water channel is 40mm, and each layer is adjacent to two upper The center-to-center distance of the cooling channels is 160mm, and the vertical center-to-center distance between the upper and lower cooling channels is 120mm.

The upper heat conduction plate described in the technical proposal is a cuboid structural part, the length and width of the upper heat conduction plate are respectively the same as the length and width of the upper mold base, and the upper heat conduction plate is made of copper material with good thermal conductivity, and the lower surface of the upper heat conduction plate is Two rows of grooves are set at the center at equal intervals of 200mm, and the two rows of grooves are arranged perpendicular to each other, and upper thermocouples are installed in the two rows of grooves; there are through holes for arranging wires around the upper heat conducting plate.

The unloading mechanism described in the technical solution includes a pusher plate, two pusher plate supports with the same structure and two cover plates on the pusher plate with the same structure. The push plate is set on the top rails of the two push plate brackets with the same structure through its two rectangular through holes, and the cover plates of the two push plate brackets with the same structure are installed on the rails of the two push plate brackets with the same structure On the top, the upper surface of the track is in contact with the lower surface of the cover plate on the pusher plate, and is connected by bolts, and the base of the pusher plate support is fixed in the clamp on the ground.

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

1. The technical problem solved by the optimal temperature control device for hot forming of high-strength steel according to the present invention is to overcome the problem of insufficient strength of parts caused by poor thermoformability of high-strength steel stock and insufficient cooling rate in the existing industrial production process, A device capable of controlling the forming temperature and cooling rate of sheet metal is provided to obtain thermoformed parts with good forming properties and mechanical properties.

2. Compared with the thermoforming production process in the existing industrial production, the present invention also has:

1) The optimal temperature control device for hot forming of high-strength steel according to the present invention can effectively improve the mechanical properties of the formed parts, the hardness can reach above 450HV, and the tensile strength can reach above 1500MPa;

Referring to Figure 3 and Figure 2, in the existing high-strength steel hot forming process, when the high-temperature sheet is taken out of the heating furnace, the initial temperature difference between the sheet and the forming die is large, and at this time it can be ensured that the sheet is in the mold. There is a very high cooling rate during the pressure quenching process after upper forming, which is greater than the critical cooling rate of martensitic transformation (25°C/s). With the heat exchange between the high-temperature sheet and the mold surface, the high-temperature sheet transfers its own heat to the low-temperature mold, causing the temperature of the high-temperature sheet to drop and the temperature of the low-temperature mold to rise. When the temperature of the sheet drops to close to the surface temperature of the mold, the sheet The cooling rate drops rapidly. In the continuous hot stamping process of industrial production, the surface temperature of the stamping die can be as high as 150°C, which will cause the cooling rate of the sheet to be kept in the temperature range of 500°C to 250°C, which is much lower than that of the martensitic transformation. Critical cooling rate (25°C/s). This will cause soft phase mixtures such as bainite, ferrite, and pearlite to be produced in the internal structure of the sheet metal, resulting in the final hot-formed parts failing to meet the strength requirements of body parts. However, in the existing high-strength steel thermoforming process, by adding the optimal temperature control device for high-strength steel thermoforming, the high-temperature sheet material transferred from the heating furnace can be quickly reduced from 800°C to 650°C (the temperature during the transfer process from 900°C to 800°C). In this process, the cooling rate of the sheet can be adjusted according to actual needs. In order to avoid the occurrence of soft phase during heat preservation and quenching when the high-temperature sheet is transferred to the stamping die for stamping, and to ensure that the sheet structure is completely formed into martensite, the high-temperature sheet must be placed in the optimal temperature control device for high-strength steel thermoforming Increase the cooling rate as much as possible, that is, as shown in Figure 3, make the continuous cooling curve move to the left as much as possible, so that the cooling rate of the sheet metal is much higher than the critical cooling rate of martensitic transformation (25 ℃ / s), so After the high-temperature sheet is transferred to the stamping die, even if the cooling rate of the sheet is lower than the critical cooling rate of the martensitic phase transformation (25°C/s) in the later stage of cooling, that is, when the continuous cooling curve slightly shifts to the right, it can ensure that the sheet The material is still in the martensitic region when it is cooled, so as to avoid the generation of soft phase, and finally obtain hot-formed parts that meet the requirements of body parts. Figure 2 shows the flow chart of the improved high-strength steel hot forming process.

2) The optimal temperature control device for hot forming of high-strength steel according to the present invention can effectively avoid the generation of hot forming defects such as wrinkling and cracking during sheet metal forming, and improve the qualified rate of formed parts;

Referring to Figure 4 and Figure 5, in the existing high-strength steel hot forming process, when the high-temperature sheet is taken out of the heating furnace and transferred to the stamping die for forming, the temperature is about 800 ° C, and this temperature is not high-strength boron The optimal forming temperature of steel, according to the stress-strain test curve of boron steel shown in the figure (when the strain rate is 1.0s ^-1 ), it can be seen that when the temperature drops from 800°C to 600°C, the ductility of the material does not change. Large, but the strength of the material is nearly doubled due to work hardening. Since work hardening can make the deformation more uniform and eliminate local necking, the formability of the material can be significantly improved. Therefore, when the forming temperature of the material is 600°C instead of 800°C, parts with more complex shapes can be formed, and so on, when the forming temperature is 500°C, the formability of the material will be better, and this is only from The stress-strain relationship analysis of the material is obtained. Further analysis of the material hardening index N, which is an important index to measure the formability of metal materials, the greater the value of N, the greater the strengthening effect of the material when plastic deformation occurs, the more uniform the deformation, and the uniformity of the strain distribution of the sheet metal is improved. During the deformation process, the compensation effect of the surrounding materials on the materials in the dangerous area is improved, which increases the deformation stability of the sheet metal. As shown in Figure 5, when the temperature is between 650°C and 700°C, the hardening index of the material reaches the maximum value, and the formability of the sheet metal is also the best in this temperature range. Taking the above two factors into consideration, it is determined that the optimum hot forming temperature of the high-strength steel in the present invention is 650°C.

3) The optimal temperature control device for hot forming of high-strength steel according to the present invention reduces the temperature during sheet metal forming, thereby reducing the holding time of stamping parts on the mold and improving productivity;

In the existing high-strength steel hot forming process, the temperature when the high-temperature sheet is transferred to the stamping die for forming is about 800°C. Due to the high temperature of the sheet, more heat is transferred to the die during the holding and quenching stage. , so that the surface temperature of the mold increases, thereby prolonging the time it takes for the sheet to cool to the final temperature, that is, increasing the forming cycle and reducing productivity. In the improved process flow, the forming temperature of the sheet metal is lower, so that less heat is transferred to the mold during the holding and quenching stage, so that the surface temperature of the mold does not increase significantly, thereby reducing the holding time and improving productivity .

4) The heat to be absorbed by the stamping die is reduced, which reduces the requirements for the cooling system of the stamping die and simplifies the design of the stamping die;

In the existing high-strength steel hot forming process, in order to ensure that the plate has a sufficient cooling rate in the stamping die and ensure the transformation of austenite to the strengthening phase martensite, it is necessary to set up a cooling system with a high-pressure cooling liquid flow in the die. system, thus increasing the mold cost and the difficulty of mold design and layout. However, in the improved technological process of adding the optimum temperature control device for hot forming of high-strength steel according to the present invention, due to the reduction of the forming temperature of the sheet metal, the heat absorbed by the stamping die is reduced, thereby reducing the requirements for the cooling system of the die, greatly Die design is simplified.

5) The optimal temperature control device for hot forming of high-strength steel of the present invention reduces the temperature of the stamping die, shortens its working temperature cycle, slows down the wear and deformation of the die surface, and improves the service life of the die.

In the existing high-strength steel hot forming process, due to the high temperature of the sheet during forming, the mold needs to absorb more heat, and the mold temperature rises significantly, and the temperature rise will aggravate the wear of the mold surface coating and the deformation of the mold surface , greatly reducing the life of the mold. However, in the improved technological process of adding the optimal temperature control device for high-strength steel thermoforming according to the present invention, since the forming temperature of the sheet metal is reduced, the heat to be absorbed by the stamping die is reduced, and the working temperature cycle of the die is from 800°C to 250°C. The temperature is lowered to 650℃～250℃, which greatly slows down the wear of the mold surface and improves the service life of the mold.

Description of drawings

Below in conjunction with accompanying drawing, the present invention will be further described:

Fig. 1 is the flowchart of existing high-strength steel thermoforming process;

Fig. 2 is the flowchart of the improved high-strength steel hot forming process;

Fig. 3 is the 22MnB5 continuous cooling test curve diagram when existing austenitizing temperature 900 ℃, holding time 5min;

Figure 4 is the stress-strain test curves of boron steel at temperatures of 500, 600, 700, and 800°C respectively (strain rate 1.0s ^-1 );

Fig. 5 is the variation trend graph of the hardening exponent N of boron steel under existing different temperatures;

Fig. 6 is an axonometric projection view of the upper mechanism structure of the optimal temperature control device for high-strength steel hot forming according to the present invention;

Fig. 7 is an axonometric projection view of the lower mechanism structure of the optimal temperature control device for high-strength steel hot forming according to the present invention;

Fig. 8 is an axonometric projection view of the structural composition of the unloading mechanism in the optimum temperature control device for hot forming of high-strength steel according to the present invention;

Fig. 9 is a schematic diagram of the distribution positions of upper thermocouples on the upper heat conducting plate in the optimal temperature control device for hot forming of high-strength steel according to the present invention;

Fig. 10 is an axonometric projection view of the cooling fan frame in the lower mechanism of the optimal temperature control device for high-strength steel thermoforming according to the present invention;

Fig. 11 is an axonometric projection view of the cooling fan in the lower mechanism of the optimal temperature control device for high-strength steel thermoforming according to the present invention;

Fig. 12 is a front view of the cooling fan assembly in the lower mechanism of the optimal temperature control device for high-strength steel thermoforming according to the present invention;

Fig. 13 is a sectional view at A-A place in Fig. 8;

Fig. 14 is a front view of the structural composition of the optimal temperature control device for high-strength steel hot forming according to the present invention in the low-level working state;

Fig. 15 is a front view of the structural composition of the high-strength steel thermoforming optimal temperature control device according to the present invention in advanced working state;

Fig. 16 is a front view of the structural composition of the high-strength steel thermoforming optimal temperature control device according to the present invention when unloading;

In the figure: 1. Upper mold guide column, 2. Upper mold base, 3. Upper heat conduction plate, 4. Lower heat conduction plate, 5. Lower mold base, 6. Heat sink, 7. Heat sink frame, 8. Heat sink frame Fixing bolts, 9. Cooling fan, 10. Fixing bolts of cooling fan frame, 11. Cooling fan frame, 12. Lower cooling channel, 13. Lower thermocouple, 14. Upper thermocouple, 15. Upper cooling channel, 16. Push material Plate, 17. pusher plate support, 18. cover plate on pusher plate, 19. upper cover plate fixing bolt, 20. high-strength steel sheet, 21. fan motor.

Detailed ways

The present invention is described in detail below in conjunction with accompanying drawing:

The optimal temperature control device for hot forming of high-strength steel according to the invention includes an upper mechanism, a lower mechanism and a discharge mechanism.

Referring to Fig. 6, the upper mechanism includes four upper mold guide pillars 1 with the same structure, an upper mold base 2, an upper heat conducting plate 3, and 9 to 17 upper thermocouples 14 with the same structure.

The upper mold guide post 1 is a cylindrical structure with equal cross-section, and the upper and lower ends of the upper mold guide post 1 are respectively provided with external threads for connection. The upper mold guide column 1 is used to fixedly connect the upper mechanism to the processing equipment, drive the entire upper mechanism to move up and down, and play a guiding role.

The upper die holder 2 is a rectangular parallelepiped structure, and the four corners of its upper surface are provided with threaded blind holes for connecting the upper die guide pillar 1 . The middle part of the upper mold base 2 is provided with 9 to 17 circular through holes parallel to each other, that is, the upper cooling channel 15. In order to ensure that the cooling channel can quickly and evenly absorb the heat transferred from the upper heat conducting plate 3, the circular upper cooling channel 15 are arranged in two layers staggered, the diameter of the upper cooling water channel 15 is 40mm, the center-to-center distance of two adjacent upper cooling water channels 15 in each layer is 160mm, and the center-to-center distance of the upper and lower upper cooling water channels 15 is 120mm in the thickness (vertical) direction.

Referring to Fig. 6 and Fig. 9, the upper heat conduction plate 3 is a cuboid structural member, and the length and width of the upper heat conduction plate 3 are respectively the same as the length and width of the upper mold base 2, and are used to transmit the pressure exerted on the high-temperature high-strength steel sheet 20 The upper heat conduction plate 3 is made of red copper material with good thermal conductivity, and the upper heat conduction plate 3 can quickly transfer the heat of the high-temperature high-strength steel material 20 to the upper mold base 2 . The center of the lower surface of the upper heat conducting plate 3 is provided with two rows of grooves at equal intervals of 200mm, and the two rows of grooves are vertically and symmetrically arranged with each other, and upper thermocouples 14 are installed in the two rows of grooves. The surrounding (end surface) of the upper heat conducting plate 3 is provided with through holes for arranging wires, and the upper thermocouple 14 is connected with the external control system by wires to ensure that the measurement information of the thermocouples is fed back to the external control system in real time.

The upper thermocouple 14 is a thermocouple whose model is WRNG-430 or WRN2G-430, which is used to measure the real-time temperature of the upper surface of the high-temperature sheet metal.

The upper mold guide post 1 is located at the uppermost part of the whole device, the upper end of the upper die guide post 1 is threadedly connected with the slider on the press, and the lower end of the upper die guide post 1 is threaded with the threaded blind holes at the four corners of the upper surface of the upper die base 2 , the lower surface of the upper mold base 2 is in contact with the upper surface of the upper heat conducting plate 3 and connected by welding, the upper thermocouple 14 is installed in the groove on the lower surface of the upper heat conducting plate 3, and the upper thermocouple 14 is connected by spot welding In the groove on the upper heat conducting plate 3.

Referring to Fig. 7, described lower mechanism comprises fan motor 21, lower heat conduction plate 4, lower mold base 5, heat sink 6, heat sink frame 7, 12 identical heat sink frame fixing bolts 8, heat dissipation mechanism (radiation fan 9. Cooling fan frame 11, 8 identical cooling fan frame fixing bolts 10), 9 to 17 lower thermocouples 13 with the same structure.

The structure, shape and size of the lower heat conduction plate 4 and the upper heat conduction plate 3 are exactly the same. The lower heat conduction plate 4 is made of red copper material with good thermal conductivity, which can quickly transfer the heat of the high-temperature sheet metal to the lower mold base 5. The center of the upper surface of the lower heat conduction plate 4 There are two rows of grooves arranged at equal intervals of 200mm, the two rows of grooves are arranged vertically and symmetrically with each other, and the lower thermocouple 13 is installed in the two rows of grooves. The surroundings of the lower heat conducting plate 4 are provided with through holes for arranging wires, and wires are used to connect the lower thermocouple 13 and the external control system to ensure that the measurement information of the thermocouples is fed back to the external control system in real time.

The structure shape and size of the lower mold base 5 and the upper mold base 2 are exactly the same, and the middle part of the lower mold base 5 is provided with 9 to 17 circular through holes parallel to each other, that is, the lower cooling channel 12, in order to ensure that the cooling channel can quickly and evenly absorb The heat transferred from the lower heat conduction plate 4, the lower cooling water channel 12 is arranged in two layers staggered, the diameter of the lower cooling water channel 12 is 40mm, and the center distance between two adjacent lower cooling water channels 12 in each layer is 160mm, the lower cooling channels of the upper and lower layers The distance between the centers of the water channels 12 in the thickness (vertical) direction is 120 mm.

The cooling fins 6 are similar to the sheet-like structural parts on the household radiators, and are used to increase the contact area between the structure and the surrounding air to accelerate heat dissipation.

The heat sink frame 7 is a hollow frame structure, the upper part of which is used to install the heat sink 6 and to support the upper mechanism and the lower mechanism.

The heat sink frame fixing bolts 8 are Ф30 anchor bolts.

Referring to Figure 11, cooling fan 9 adopts the cooling fan model BCY-L30, the operating voltage is 380/220V, the dimensions (length×width×height) are 1350×800×1700mm, and the size of the air outlet (length×height): It is 1080×1080mm.

The cooling fan frame fixing bolts 10 are anchor bolts of Ф20.

Referring to Fig. 10, the heat dissipation fan frame 11 is a two-layer frame structure, and the upper part of the heat dissipation fan frame 11 (that is, the position between the mesh shield at the top and the mesh interlayer in the middle) is used for installing the heat dissipation fan 9. The top of the fan frame 11 is a mesh protective cover, the middle of the cooling fan frame 11 is provided with a mesh interlayer, the center of the mesh interlayer is provided with a central hole for installing the cooling fan 9, and the lower end of the cooling fan 9 is inserted below it. In the central hole of the mesh interlayer, and connected to the output end of the fan motor 21, the upper and lower parts of the cooling fan frame 11 are communicated through the mesh interlayer, and the lower part of the cooling fan frame 11 is used to discharge the heat flowing through the upper cooling fan 9. Hot air flow.

The lower thermocouple 13 adopts a thermocouple whose model is WRNG-430 or WRN2G-430, and is used to measure the real-time temperature of the lower surface of the high-temperature plate in the device.

The lower heat conduction plate 4 is located directly below the upper heat conduction plate 3, and the two are in a separated state when not working. Each lower thermocouple 13 is installed in the groove at the center of the upper surface of the lower heat conducting plate 4 in sequence, and each lower thermocouple 13 is connected in the groove on the lower heat conducting plate 4 by spot welding. The position of the lower thermocouple 13 on the lower heat conducting plate 4 is the same as that of the upper thermocouple 14 on the upper heat conducting plate 3 . The lower surface of the lower heat conducting plate 4 is in contact with the upper surface of the lower mold base 5 and is connected by welding, the lower surface of the lower mold base 5 is in contact with the upper surface of the heat sink frame 7 and is connected by welding, and the heat sink frame 7 is a cuboid Shaped frame structure, the top (around) of the heat sink frame 7 is evenly distributed with heat sinks 6, and the heat sink 6 forms an integral structure with the heat sink frame 7 by casting. The lower part of the heat sink frame 7 is connected to the ground through 12 Ф30 heat sink frame fixing bolts 8, the cooling fan frame 11 is located at the center of the lower part of the heat sink frame 7, and the cooling fan 9 is arranged on the upper part of the cooling fan frame 11, and the lower part is connected by 8 The Ф20 cooling fan frame fixing bolts 10 are connected to the ground, and the structural composition of the cooling fan assembly can be referred to in Figure 12.

Referring to Figure 8, the unloading mechanism includes a pusher plate 16, 2 pusher plate supports 17 with the same structure, 2 pusher plate cover plates 18 with the same structure, and 4 identical upper cover plate fixing bolts 19.

The pusher plate 16 is a rectangular plate structure, on which two parallel rectangular chutes (through holes) are arranged for sliding back and forth on the track on the pusher plate support 17 tops, and the left end of the pusher plate is used for During the unloading process, the high-strength steel sheet 20 is pushed out from the lower heat conducting plate 4 to facilitate the removal of the sheet.

The top of the pusher plate support 17 is provided with a (inverted T-shaped) track fitted with the pusher plate 16, and two threaded holes are evenly arranged on the top surface of the track, and the top track makes the pusher plate 16 only have the freedom to move left and right. The middle part is a hollow rectangular plate structure, and the bottom end is arranged with a flange plate base, and the bolt through holes are evenly arranged on the flange plate base.

The cover plate 18 on the pusher plate is a rectangular plate structure with bolt through holes, the distance between the two bolt through holes on the cover plate 18 on the pusher plate and the two threads of the top track of the pusher plate support 17 The distances of the holes are equal, and the cover plate 18 on the pusher plate is used to constrain the degree of freedom of the pusher plate 16 in the up and down direction.

The upper cover plate fixing bolt 19 is a hexagon head bolt of Ф16, which is used for connecting the cover plate 18 on the push plate and the push plate support 17 .

Referring to Fig. 13, the pusher plate 16 is set on the rails at the top of two pusher plate supports 17 with the same structure through two rectangular through holes, and the two pusher plate covers 18 with the same structure are installed on the two same structure On the track of the pusher plate support 17, the upper surface of the track is in contact with the lower surface of the cover plate 18 on the pusher plate, and the two are connected by bolts to facilitate the replacement of the pusher plate 16. The pusher plate 16 can be installed in two structures. Move left and right on the track of identical pushing plate support 17. The base of the pusher plate support 17 is fixed in the clamp on the ground, guarantees that the pusher plate support 17 does not move when working.

Among them, the upper mold base 2 and the lower mold base 5 are made of Al ₂ O ₃ /Cu high temperature resistant composite material manufactured by Thyssen, and the upper heat conduction plate 3 and the lower heat conduction plate 4 are made of red copper material, which is easy to obtain and has a large thermal conductivity. And it is still in a solid state at 900 ° C, and other parts are made of 4Cr5MoSiV material.

The actual working process of the optimal temperature control device for high-strength steel hot forming will be introduced below in combination with two specific examples.

Example 1: Low-level working process.

Referring to Fig. 14 and Fig. 16, when the thickness of the high-strength steel material 20 to be cooled is thin and the size is small, the low-level working process can be considered. For example, the 22MnB5 rough sheet of 800mm×600mm×1.5mm is used as the operation object to ensure that the optimum forming temperature is 650°C before forming.

The low-level working process consists of the following steps:

1. Use a cutting machine to cut a 22MnB5 blank sheet of 800mm×600mm×1.5mm;

2. Transfer it to a heating furnace through a mechanical device, raise the temperature to 900°C, and keep it warm for 5 minutes to ensure that the internal structure of the blank sheet is completely transformed into uniform austenite;

3. Subsequently, the fully austenitized high-temperature high-strength steel material 20 is quickly transferred to the lower heat conduction plate 4 of the optimal temperature control device for high-strength steel hot forming through a mechanical device, and the upper cooling water channel 15 and the lower cooling water channel 12 are opened at the same time the switch;

4. Driven by the upper mold guide pillar 1, the upper mold base 2 and the upper heat conduction plate 3 move downward at a speed of 3m/s, so that the lower surface of the upper heat conduction plate 3 and the high-temperature high-strength steel material 20 on the lower heat conduction plate 4 The upper surfaces are in contact, and a pressure of 10 MPa is applied to the high-temperature high-strength steel material 20 through the upper heat conducting plate 3. During the whole process, the upper thermocouples 14 distributed on the lower surface of the upper heat conducting plate 3 and the lower thermocouples distributed on the upper surface of the lower heat conducting plate 4 Even 13 for real-time temperature measurement;

5. When the average surface temperature of the high-temperature high-strength steel material 20 reaches 650°C, quickly close the switches of the upper cooling water channel 15 and the lower cooling water channel 12, and make the upper mold guide column 1 drive the upper mold base 2 and the upper heat conducting plate 3 for a distance of 3m Move upward at a speed of 1/s, and at the same time turn on the power of the unloading mechanism, the pushing plate 16 moves forward at a speed of 1m/s, and pushes the high-temperature high-strength steel material 20 on the upper surface of the lower heat conducting plate 4 away from the lower heat conducting plate 4 ;

6. The high-temperature high-strength steel sheet 20 is clamped by a mechanical device, quickly transferred to the punching machine, and the press moves downward to drive the mold to close, and the sheet is quickly punched and formed, and the final thermoformed part is obtained by heat preservation and pressure.

The pressure of 10 MPa applied in step 4 is to eliminate the gap between the upper and lower surfaces of the high-temperature high-strength steel material 20 and the surfaces of the upper heat conduction plate 3 and the lower heat conduction plate 4 to accelerate heat conduction. In the whole process, the heat of the high-temperature high-strength steel material 20 is quickly transferred to the upper mold base 2 through the upper heat conduction plate 3, and is transferred to the lower mold base 5 through the lower heat conduction plate 4, and the heat is quickly transferred to the upper cooling channel 15, The circulating cooling water in the lower cooling water channel 12 in the lower mold base 5 is absorbed and taken away; at the same time, the heat sink 6 on the heat sink frame 7 also consumes a part of the heat of the high-temperature sheet metal by dissipating heat to the surrounding environment. At this time, the heat dissipation fan The cooling fan 9 on the frame 11 is in a closed state.

Example 2: Advanced working process.

Referring to Fig. 15 and Fig. 16, when the thickness of the high-strength steel material 20 to be cooled is thick and the size is large, an advanced working process can be considered. For example, the 22MnB5 rough sheet of 2000mm×1500mm×3mm is used as the operation object to ensure that the optimum forming temperature is 650°C before forming.

The high-level working process includes the following steps:

1. Use a cutting machine to cut a 22MnB5 blank sheet of 2000mm×1500mm×3mm;

2. Transfer it to a heating furnace through a mechanical device, raise the temperature to 900°C, and keep it warm for 5 minutes to ensure that the internal structure of the blank sheet is completely transformed into uniform austenite;

3. Subsequently, the fully austenitized high-temperature high-strength steel material 20 is quickly transferred to the lower heat conduction plate 4 of the optimal temperature control device for high-strength steel hot forming through a mechanical device, and the upper cooling water channel 15 and the lower cooling water channel 12 are opened at the same time the switch;

4. Driven by the upper mold guide pillar 1, the upper mold base 2 and the upper heat conduction plate 3 move downward at a speed of 3m/s, so that the lower surface of the upper heat conduction plate 3 and the high-temperature high-strength steel material 20 on the lower heat conduction plate 4 The upper surfaces are in contact, and a pressure of 20 MPa is applied to the high-temperature high-strength steel material 20 through the upper heat conducting plate 3. During the whole process, the upper thermocouples 14 distributed on the lower surface of the upper heat conducting plate 3 and the lower thermocouples distributed on the upper surface of the lower heat conducting plate 4 Thermocouple 13 carries out real-time temperature measurement;

5. When the average surface temperature of the high-temperature high-strength steel material 20 reaches 650°C, quickly close the switches of the upper cooling water channel 15, the lower cooling water channel 12, and the cooling fan 9, and make the upper mold guide post 1 drive the upper mold base 2 and the upper heat conduction The plate 3 moves upward at a speed of 3m/s, and at the same time the power of the unloading mechanism is turned on, and the pushing plate 16 moves forward at a speed of 1m/s to push away the high-temperature high-strength steel material 20 on the upper surface of the lower heat conducting plate 4 Lower heat conducting plate 4;

6. The high-temperature high-strength steel sheet 20 is clamped by a mechanical device, quickly transferred to the punching machine, and the press moves downward to drive the mold to close, and the sheet is quickly punched and formed, and the final thermoformed part is obtained by heat preservation and pressure.

The pressure of 20 MPa applied in step 4 is to eliminate the gap between the upper and lower surfaces of the high-temperature high-strength steel material 20 and the surfaces of the upper heat conduction plate 3 and the lower heat conduction plate 4 to accelerate heat conduction. In the whole process, the heat of the high-temperature high-strength steel material 20 is quickly transferred to the upper mold base 2 through the upper heat conduction plate 3, and is transferred to the lower mold base 5 through the lower heat conduction plate 4, and the heat is quickly transferred to the upper cooling channel 15, The circulating cooling water in the lower cooling water channel 12 in the lower mold base 5 is absorbed and taken away; at the same time, the heat sink 6 on the heat sink frame 7 also consumes a part of the heat of the high-temperature sheet metal by dissipating heat to the surrounding environment. At this time, the heat dissipation fan The cooling fan 9 on the frame 11 is in working condition. Under its action, the air flow around the heat sink 6 is accelerated, so that the low-temperature air flows in from around the heat sink 6, and the high-temperature air flows out from the lower part of the cooling fan 9, further accelerating the cooling rate of the high-temperature high-strength steel sheet 20.

Claims (5)

1. An optimal temperature control device for hot forming of high-strength steel, characterized in that, the optimal temperature control device for hot forming of high-strength steel includes an upper mechanism, a lower mechanism and a discharge mechanism; The upper mechanism is located directly above the lower mechanism, and the unloading mechanism is located on the right side of the lower mechanism; The upper mechanism includes four upper mold guide pillars (1) with the same structure, an upper mold base (2), an upper heat conducting plate (3), and 9 to 17 upper thermocouples (14) with the same structure; The lower end of the upper mold guide post (1) is threadedly connected with the threaded blind holes at the four corners of the upper surface of the upper mold base (2), and the lower surface of the upper mold base (2) is in contact with the upper surface of the upper heat conducting plate (3). Connected by welding, the upper thermocouple (14) is installed in the groove on the lower surface of the upper heat conducting plate (3), and the upper thermocouple (14) is connected in the groove on the upper heat conducting plate (3) by spot welding; Described upper mold base (2) is a cuboid structure, and the length and width of upper mold base (2) are identical with the length and width of lower mold base (5) respectively, and the four corners of the upper surface of upper mold base (2) A threaded blind hole for connecting the upper mold guide post (1) is provided at the place, and the middle part of the upper mold base (2) is provided with 9 to 17 circular through holes parallel to each other, that is, the upper cooling water channel (15), and the upper cooling water channel ( 15) Arranged in two layers staggered, the diameter of the upper cooling water channel (15) is 40mm, the center-to-center distance between two adjacent upper cooling water channels (15) in each layer is 160mm, and the upper cooling water channel (15) of the upper layer and the lower layer is in the vertical direction Center distance is 120mm; The lower mechanism includes a lower heat conducting plate (4), a lower mold base (5), a heat sink frame (7), a heat dissipation mechanism and 9 to 17 lower thermocouples (13) with the same structure; 9 to 17 lower thermocouples (13) with the same structure are respectively installed in the grooves on the upper surface of the lower heat conduction plate (4), and each lower thermocouple (13) is connected in the groove of the lower heat conduction plate (4) by spot welding , the lower surface of the lower heat conducting plate (4) is in contact with the upper surface of the lower mold base (5) and is connected by welding, and the lower surface of the lower mold base (5) is in contact with the upper surface of the heat sink frame (7) and is welded mode connection, the cooling mechanism is located at the center of the bottom of the heat sink frame (7); The lower mold base (5) is a cuboid structural member, and the middle part of the lower mold base (5) is provided with 9 to 17 circular through holes parallel to each other, that is, the lower cooling water channel (12), the lower cooling water channel (12) Arranged in two layers staggered, the diameter of the lower cooling water channel (12) is 40 mm, the center distance between two adjacent lower cooling water channels (12) in each layer is 160 mm, and the center distance between the lower cooling water channel (12) of the upper layer and the lower layer in the vertical direction is 120mm. 2. The optimal temperature control device for hot forming of high-strength steel according to claim 1, characterized in that, the heat dissipation mechanism includes a heat dissipation fan (9) and a heat dissipation fan frame (11); The heat dissipation fan frame (11) is a two-layer frame structure, the top of the heat dissipation fan frame (11) is the center of the protective cover of the ventilation net, and the middle layer of the heat dissipation fan frame (11) is also set as the center. The mesh interlayer of the ventilation net, the center of the mesh interlayer is provided with a central hole for installing a cooling fan (9), and the lower end of the cooling fan (9) is inserted into the central hole of the mesh interlayer and connected with the fan motor (21) The output terminal is connected. 3. According to the optimal temperature control device for hot forming of high-strength steel according to claim 1, it is characterized in that, the lower heat conducting plate (4) is a cuboid structure, and the length and width of the lower heat conducting plate (4) are respectively Same as the length and width of the lower mold base (5), the lower heat conduction plate (4) is made of red copper material with good thermal conductivity, and the center of the upper surface of the lower heat conduction plate (4) is provided with two rows of lower thermocouples (13 ) grooves, two rows of grooves are arranged perpendicularly to each other, and through holes for arranging wires are arranged around the lower heat conducting plate (4). 4. The optimal temperature control device for hot forming of high-strength steel according to claim 1, characterized in that, the upper heat conducting plate (3) is a cuboid structural member, and the length and width of the upper heat conducting plate (3) are respectively The same length and width as the upper mold base (2), the upper heat conducting plate (3) is made of red copper material with good thermal conductivity, and the center of the lower surface of the upper heat conducting plate (3) is provided with two rows of grooves at equal intervals of 200mm. The grooves are arranged perpendicular to each other, and upper thermocouples (14) are installed in the two rows of grooves; through holes for arranging wires are arranged around the upper heat conducting plate (3). 5. According to the optimal temperature control device for high-strength steel hot forming according to claim 1, it is characterized in that, the described unloading mechanism includes a pusher plate (16), 2 pusher plate supports (17) with the same structure ), 2 pusher plate cover plates (18) with the same structure; The pusher plate (16) is set on the track on the top of 2 pusher plate supports (17) with the same structure through its two rectangular through holes, and the 2 pusher plate cover plates (18) with the same structure are installed on 2 On the track of the pusher plate support (17) with the same structure, the upper surface of the track is in contact with the lower surface of the pusher plate cover plate (18), and is connected by bolts, and the base of the pusher plate support (17) is fixed Inside the fixture on the ground.