A hot stamping die

Abstract

The application discloses a hot stamping die, which comprises a die frame, a discharging mechanism, a concave die mechanism, a pressure ring and a convex die mechanism arranged in sequence from top to bottom in the die frame; the discharging mechanism is arranged on the concave die mechanism; the concave die mechanism, the pressure ring and the convex die mechanism are connected through a guide mechanism; the concave die mechanism is provided with a first cooling water channel; and the convex die mechanism is provided with a second cooling water channel and a temperature measuring device. The application aims to solve the forming problem of insufficient cooling of complex hot stamping parts.

Description

Technical Field

[0001] This invention relates to hot stamping forming equipment, and more specifically, to a hot stamping die. Background Technology

[0002] The vehicle body, as one of the four major systems of an automobile, accounts for approximately 40% of the total vehicle weight and is a key component for vehicle lightweighting. Currently, the main material used for vehicle body lightweighting is ultra-high-strength steel sheet, which combines the advantages of lightweighting and safety. However, if ultra-high-strength steel sheet is directly processed using traditional cold stamping technology, the resulting parts have poor formability, low dimensional accuracy, and large springback deviation, while also leading to a shortened die life. Hot stamping technology, on the other hand, is a new and advanced manufacturing technology specifically designed for forming ultra-high-strength stamped parts, effectively solving the problems that hot stamping cannot overcome.

[0003] Hot stamping technology involves heating ultra-high-strength steel sheets to fully austenitize them, rapidly transferring them to a die, and then closing and holding the die under pressure. The high-temperature ultra-high-strength steel sheets undergo in-die quenching during forming, resulting in a martensitic transformation and ultimately producing parts with tensile strengths of around 1500 MPa or even higher. The martensitic transformation of ultra-high-strength steel sheets begins at 425℃. To obtain a fully martensitic structure, the cooling rate of the sheet material between 800 and 425℃ must exceed the critical cooling rate. The cooling rate directly affects the microstructure transformation of the sheet material, and the in-die quenching process directly determines the final properties of the formed part. While forming the sheet material, the hot stamping die must also possess sufficient cooling capacity. The cooling rate directly affects the microstructure transformation, and the in-die quenching process directly determines the final properties of the formed part. Ensuring a rapid cooling rate while avoiding cooling deformation caused by uneven temperature distribution is crucial to obtaining qualified ultra-high-strength steel parts. Therefore, a reasonable and comprehensive cooling system is indispensable.

[0004] Currently, conventional hot stamping dies typically employ an integrated punch design and a straight-through cooling channel layout to reduce processing difficulty. However, this design is not conducive to measuring the internal temperature of the die and ensuring uniform cooling of the sheet metal. Summary of the Invention

[0005] In view of the above-mentioned defects in the prior art, the purpose of this invention is to provide a hot stamping die, which aims to solve the forming problem of insufficient cooling of complex hot stamping parts.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A hot stamping die includes a die frame and an unloading mechanism, a die cavity mechanism, a blank holder ring, and a punch mechanism arranged sequentially from top to bottom within the die frame.

[0008] The unloading mechanism is mounted on the die cavity mechanism, and the die cavity mechanism, the pressure ring, and the punch mechanism are connected by a guide mechanism.

[0009] The die mechanism is provided with a first cooling water channel;

[0010] The punch mechanism is equipped with a second cooling water channel and a temperature measuring device.

[0011] Preferably, the die mechanism includes an upper pad, an upper template, and a die body;

[0012] The upper template is fixedly connected to the lower surface of the upper pad by pins and screws;

[0013] The concave mold body is fixedly connected to the lower surface of the upper template by pins and screws;

[0014] The cavity body is provided with the first cooling water channel.

[0015] Preferably, the unloading mechanism includes an unloading baffle, an unloading push rod, and a rubber ring;

[0016] The unloading baffle is fixedly connected to the upper surface of the upper pad by pins;

[0017] The upper end of the unloading ejector rod is connected to the unloading baffle via the rubber ring, and the lower end passes through the upper template and the die body.

[0018] Preferably, the upper surface of the pressure ring is provided with a rectangular groove for mounting a positioning block and a mounting hole for mounting an elastic pin.

[0019] A rubber pad is provided inside the rectangular groove.

[0020] Preferably, the punch mechanism includes a lower template, a lower backing plate, a punch sealing plate, and a punch body;

[0021] The lower pad is fixedly connected to the upper surface of the lower template by pins and screws;

[0022] The punch sealing plate is fixedly connected to the upper surface of the lower pad by pins and screws, and the punch sealing plate has inlet and outlet water ports inside;

[0023] The punch body is fixedly connected to the upper surface of the punch sealing plate by pins and screws. The punch body is provided with the second cooling water channel and the tree-shaped groove for installing the temperature measuring device.

[0024] The second cooling water channel is connected to the inlet and outlet.

[0025] Preferably, the first cooling channel includes a first cooling pipe and cooling water inlet and outlet formed on the die body;

[0026] The first cooling pipes are all parallel to the mold surface contour of the die body;

[0027] The first cooling pipe is a blind hole with a diameter of 10 mm. The inner wall of the hole is 15 mm away from the nearest side wall of the die body. The entrance of the blind hole is sealed with set screws wrapped with PTFE tape. The distance between the central axis of each first cooling pipe and the die surface of the die body is between 9 and 10 mm.

[0028] The cooling water inlet and outlet are located on the side of the die body perpendicular to the central axis of the first cooling pipe and are connected to the first cooling pipe.

[0029] The diameter of the cooling water inlet and outlet is 30mm.

[0030] Preferably, the rectangular groove has two grooves, which are distributed on opposite sides of the inner ring of the pressure ring;

[0031] The rectangular groove has a length of 206 mm and a depth of 20 mm.

[0032] Preferably, the punch body includes two identical punch blocks;

[0033] The second cooling channel includes a second cooling pipe that is opened within the punch block and parallel to the die surface contour of the punch body;

[0034] The second cooling pipe is a blind hole with a diameter of 10 mm. The bottom surface of the hole is 16 mm away from the nearest side wall of the punch block. The entrance of the blind hole is sealed with set screws wrapped with PTFE tape. The distance between the central axis of each second cooling pipe and the die surface of the punch block is between 9 and 10 mm.

[0035] The inlet and outlet are water tanks located 15mm away from the side wall of the punch block, machined perpendicular to the bottom surface of the punch block, with a width of 10mm, and connected to the second cooling pipe.

[0036] Preferably, the temperature measuring device is a thermocouple;

[0037] The distance between the dendritic groove and the die surface of the punch body is 1.1 mm, and the groove depth is 2 mm.

[0038] Preferably, the guiding mechanism includes guide posts and guide holes located at the four corners of the die body, the pressure ring, and the punch body;

[0039] The guide pillar is vertically disposed within the mold frame;

[0040] The die body, the pressure ring, and the punch body are fitted onto the guide post through the guide hole and move vertically along the guide post.

[0041] The hot stamping die provided by this invention has the following beneficial effects:

[0042] 1) The punch body adopts a segmented structure design. While ensuring the rigidity of the punch structure, the cooling pipes inside the punch are centrally supplied and drained through a trapezoidal water tank, and the punch is cooled evenly and effectively. This makes it easy to process the thermocouple grooves for installing thermocouples in the segmented punch, and makes it easy to install and replace thermocouples.

[0043] 2) The blank holder uses a special parting line method, so that the sample after forming is completely inside the punch and die, and there is no need to add cooling channels inside the blank holder for quenching.

[0044] 3) The upper surface of the pressure ring is equipped with spring pins, positioning blocks and rubber pads, which together position the sheet material. In addition, the positioning blocks also play a role in adjusting the pressure gap during the forming process. The flow of the sheet material is controlled between the pressure ring and the die through the pressure gap. Attached Figure Description

[0045] Figure 1 This is an overall schematic diagram of the hot stamping die of the present invention;

[0046] Figure 2 yes Figure 1 A side view diagram;

[0047] Figure 3 This is a schematic diagram of the die body in the hot stamping die of the present invention;

[0048] Figure 4 This is a schematic diagram of the punch body in the hot stamping die of the present invention;

[0049] Figure 5 This is a schematic diagram of the dendritic groove on the punch body in the hot stamping die of the present invention;

[0050] Figure 6 This is a schematic diagram of the punch sealing plate in the hot stamping die of the present invention;

[0051] Figure 7 This is a schematic diagram of the second cooling water channel and the inlet and outlet of the hot stamping die of the present invention;

[0052] Figure 8 This is a schematic diagram of the blank holder in the hot stamping die of the present invention;

[0053] Figure 9This is a schematic diagram of the parting line on the pressure ring in the hot stamping die of the present invention;

[0054] Figure 10 This is a schematic diagram of the unloading mechanism in the hot stamping die of the present invention. Detailed Implementation

[0055] To better understand the above-mentioned technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0056] Combination Figure 1 , Figure 2 and Figure 10 As shown, the hot stamping die provided by the present invention includes a four-column die frame, and an unloading mechanism, a die cavity mechanism, a pressure ring and a punch mechanism arranged sequentially from top to bottom within the die frame.

[0057] The unloading mechanism is located on the die mechanism, and the die mechanism, the pressure ring 12 and the punch mechanism are connected by a guide mechanism.

[0058] The die mechanism is equipped with a first cooling water channel.

[0059] The punch mechanism is equipped with a second cooling water channel and a temperature measuring device.

[0060] The unloading mechanism includes an unloading baffle 1, an unloading ejector rod 2, and a rubber ring 3; the die mechanism includes an upper pad 4, an upper template 5, and a die body 6.

[0061] The unloading baffle 1 is fixedly connected to the upper surface of the upper pad 4 by two M10 pins 7.

[0062] The upper end of the ejector pin 2 is connected to the ejector baffle 1 via a rubber ring 3, and the lower end passes through the upper template 5 and the die body 6.

[0063] The upper template 5 is fixedly connected to the lower surface of the upper pad 4 by six 8mm diameter pins 8 and six M10 screws 9.

[0064] Infrared temperature sensor 27 is fixed to the upper template 5 by screw 41, and measures the temperature change of the sample during the forming process through the through hole that passes through the upper template 5 and the die body 6.

[0065] The die body 6 is fixedly connected to the lower surface of the upper template 5 by four 20mm diameter pins 10 and twelve M10 screws 11. The die body 6 has a first cooling water channel machined inside.

[0066] The upper surface of the pressure ring 12 has a rectangular groove 14 for mounting the positioning block 13 and a mounting hole 16 for mounting the elastic pin 15 for positioning the sheet metal. A rubber pad 16 is provided in the rectangular groove 14.

[0067] The punch mechanism includes a lower template 17, a lower backing plate 18 (with three pieces), a punch sealing plate 19, and a punch body 20.

[0068] The lower pad 18 is positioned and fastened to the upper surface of the lower template 17 by six 8mm diameter pins 21 and six M10 screws 22, and is used to support the punch sealing plate 19 and the punch body 20.

[0069] The punch sealing plate 19 is fixedly connected to the upper surface of the lower pad plate 18 by six 8mm diameter pins 23 and six M10 screws 24. The punch sealing plate 19 has inlet and outlet ports for the punch body 20.

[0070] The punch body 20 is fixedly connected to the upper surface of the punch sealing plate 19 by pins 25 and screws 26. The punch body 20 has a second cooling water channel inside and a tree-shaped groove 36 for installing a temperature measuring device.

[0071] A groove is machined on the connecting surface of the punch body 20 and the punch sealing plate 19. This groove is used to install a rubber sealing ring, which facilitates the sealing of cooling water between the punch body 20 and the punch sealing plate 19 and ensures the flow of cooling water.

[0072] The structure of the pressure ring 12 is determined by the parting line of the punch.

[0073] Combination Figure 3 As shown, the die body 6 adopts an integral structure design, and 14 first cooling channels 30 parallel to the mold surface contour of the die body 6 are machined inside. The first cooling channel 30 is cylindrical and is a blind hole with a diameter of 10mm. The inner wall of the hole is 15mm away from the nearest side wall of the die body 6, and the entrance of the blind hole is sealed with set screws wrapped with PTFE tape. The distance between the central axis of each first cooling channel 30 and the mold surface of the die body 6 is between 9 and 10mm.

[0074] Two cylindrical holes, each 30mm in diameter, are machined on the side of the die body 6 perpendicular to the central axis of the first cooling pipe 30. These holes are directly connected to the first cooling pipe 30 or connected to a flexible hose, serving as cooling water inlets and outlets 31 and 32 within the die body 6. This allows for centralized water supply and drainage to the first cooling pipes 30 inside the die body 6 through four cooling water inlets and outlets 31 and 32, while maintaining the structural rigidity of the die body 6. This provides uniform and effective cooling to the die body 6. The materials used are heat-treated, and the depth of the first cooling pipes 30 must be strictly controlled during machining; otherwise, leakage of the mold will occur.

[0075] Combined Figure 2 and Figure 4As shown, the punch body 20 adopts a segmented structure design, including two identical punch segments 201 and 202. Each punch segment 201 and 202 has 14 second cooling channels 33 that are parallel to the mold surface contour of the punch body 20. The second cooling channel 33 is cylindrical and is a blind hole with a diameter of 10 mm. The inner wall of the hole is 16 mm away from the nearest side wall of the punch body 20. The entrance of the blind hole is sealed with set screws wrapped with PTFE tape. The distance between the central axis of each second cooling channel 33 and the mold surface of the punch body 20 is between 9 and 10 mm.

[0076] Trapezoidal water channels 34, each 10mm wide and perpendicular to the bottom surface of punch blocks 201 and 202, are machined 15mm away from their side walls and connected to the second cooling pipes 33. These channels serve as inlets and outlets for cooling water within the punch blocks 201 and 202. This allows for centralized water supply and drainage to the second cooling pipes 33 inside the punch body 20 while maintaining structural rigidity. The second cooling pipes 33 also provide uniform and effective cooling to the punch body 20. Furthermore, the punch blocks 201 and 202 are easily machined with dendritic grooves 36 (thermocouple grooves) for installing thermocouples 35, facilitating the installation and replacement of thermocouples 35.

[0077] Combination Figure 5 As shown, the temperature measuring device is a thermocouple 35. There are 11 thermocouples 35 in total, distributed at 11 temperature measuring points (see...). Figure 5 (Temperature measuring points 1 to 11) The distance between the measuring position of thermocouple 35 and the mold surface of punch blocks 201 and 202 is 1.1 mm, and the groove depth is 2 mm. The thermocouple 35 is fixed in the thermocouple groove by welding. This layout can effectively measure the temperature change and distribution of the mold surface of punch blocks 201 and 202.

[0078] Combination Figure 6 As shown, the punch sealing plate 19 has four Φ24 through holes 37 machined on the side parallel to the bottom surface of the punch blocks 201 and 202. A groove with a width of 2mm and a depth of 1m is machined around the bottom surface of the through holes 37 to place the rubber sealing ring for connecting the second cooling pipe 33 on the two punch blocks 201 and 202. Two M24 threaded holes 40 are machined on the two sides respectively as the inlet and outlet of cooling water in the punch sealing plate 19 for centralized water supply and drainage to ensure the consistency of water velocity.

[0079] Combination Figure 7As shown, the cooling water channels between the punch sealing plate 19 and the two punch blocks 201 and 202 adopt a "centralized-dispersed-centralized" design. The cooling water channels within the punch blocks 201 and 202 are two parallel routes with the same principle, controlling the flow of cooling water through 14 second cooling pipes 33 within the punch blocks 201 and 202 respectively. The water channel route 100 follows the flow direction CDEFGHJK. Port C is the inlet for cooling water to enter the punch sealing plate 19. Then, at point D, the cooling water enters the seven second cooling pipes 33 within the punch blocks 201 and 202 respectively, and then flows into port G through the connecting water pipe installed at port E. Similarly, the water supply to the seven second cooling pipes 33 within the punch blocks 201 and 202 is distributed. Finally, the water flows out from the outlet port K of the punch sealing plate 19 in a concentrated manner, completing the cooling of the die body 20 surface.

[0080] Combined Figure 2 and Figure 8 As shown, the assembly diagram of the pressure ring 12, positioning block 13, elastic pin 15, and rubber pad 16 is shown. The upper surface of the pressure ring 12 has two rectangular grooves 14 with a length of 206mm and a depth of 20mm, which are used to install the rubber pad 16 and the positioning block 13 whose bottom surface does not contact the rectangular grooves 14. The positioning block 13 is limited by M4 screws 38 connected to the pressure ring 12. The connecting hole on the positioning block 13 is an M5 through hole. The positioning block 13 can move elastically a small distance in the direction perpendicular to the bottom surface. The spring pin 15 is installed on the upper surface of the pressure ring 12. The positioning block 13 and the elastic pin 15 together position the sheet metal. In addition, the positioning block 13 also plays the role of adjusting the pressure gap during the forming process. The flow of the sheet metal is controlled between the pressure ring 12 and the die body 6 through the pressure gap.

[0081] Combined Figure 1 and Figure 2 As shown, the guiding mechanism includes a guide post 39 and guide holes located at the four corners of the die body 6, the pressure ring 12, and the punch body 20. The guide post 39 is vertically disposed within the mold frame. The die body 6, the pressure ring 12, and the punch body 20 are fitted onto the guide post 39 through the guide holes and move vertically along the guide post 39.

[0082] Combination Figure 9As shown, the parting line BB of the punch is located on the side of the punch blocks 201 and 202, 36mm away from the lower radius of the punch body 20. The traditional parting line is located at AA. After the traditional parting line is fully closed, part of the sheet metal will remain at the blank holder. The quenching process requires the participation of the blank holder 12, so cooling water channels and thermocouple grooves need to be opened in the blank holder 12, which will significantly increase the processing cost and manufacturing difficulty. The parting line involved in this invention causes the blank holder 12 to perform the first stage of blank holding during the forming process, and the punch body 20 to perform the blank holding at the end. This makes the boron steel sheet completely within the punch blocks 201 and 202 and the die body 6 after forming. Cooling pipes do not need to be set in the blank holder 12 for cooling during the pressure holding and quenching stage.

[0083] Combination Figure 10 As shown, the unloading mechanism includes an unloading baffle 1, an unloading ejector rod 2, and a rubber ring 3. The diameter of the unloading ejector rod 2 is 10mm, and its lower end passes through the upper template 5 and the die body 6. The bottom surface of the unloading ejector rod 2 is located 10mm below the upper plane of the inner wall of the die body 6. During the mold closing process, the unloading ejector rod 2 will be subjected to an upward force, which will cause the rubber ring 3 to be compressed. During the demolding process, the rubber ring 3 provides a downward force to the unloading ejector rod 2, and finally acts on the top of the molded part, which facilitates the demolding of the molded part.

[0084] In summary, this invention employs a segmented punch and a novel cooling system for hot stamping dies to achieve uniform cooling and improved performance of complex boron steel forming parts. The segmented structure of the punch enhances its machinability and facilitates thermocouple installation and replacement. A centralized water supply and drainage system for cooling pipes, along with a method of designing cooling pipe paths based on the die surface contour, ensures uniform and effective cooling of the punch and die interiors. A special parting line method alters the action of the blank holder force during forming, ensuring pressure holding and quenching effects of the hot stamped parts even when cooling pipes are only arranged in the die and punch, but not in the blank holder ring (simplifying the cooling system).

[0085] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A hot stamping die characterized by: The mold frame, and the unloading mechanism, the die mechanism, the edge ring and the punch mechanism arranged in sequence from top to bottom in the mold frame; The unloading mechanism is arranged on the die mechanism, and the die mechanism, the edge ring and the punch mechanism are connected through the guide mechanism; The first cooling water channel is arranged on the die mechanism; The second cooling water channel and the temperature measuring device are arranged on the punch mechanism, The punch mechanism comprises a lower die plate, a lower pad, a punch sealing plate and a punch body; The lower pad is fixedly connected to the upper surface of the lower die plate through a pin and a screw; The punch sealing plate is fixedly connected to the upper surface of the lower pad through a pin and a screw, and the punch sealing plate is internally provided with water inlet and outlet openings; The punch body is fixedly connected to the upper surface of the punch sealing plate through a pin and a screw, and the punch body is internally provided with the second cooling water channel and a dendritic recess for mounting the temperature measuring device; The second cooling water channel is in communication with the water inlet and outlet openings, The punch body comprises two punch sub-blocks arranged in the same way; The second cooling water channel comprises a second cooling pipeline arranged in the punch sub-block and parallel to the die surface profile of the punch body.

2. The hot stamping die of claim 1, wherein: The die mechanism comprises an upper pad, an upper die plate and a die body; The upper die plate is fixedly connected to the lower surface of the upper pad through a pin and a screw; The die body is fixedly connected to the lower surface of the upper die plate through a pin and a screw; The die body is internally provided with the first cooling water channel.

3. The hot stamping die of claim 2, wherein: The unloading mechanism comprises an unloading baffle, an unloading ejector rod and a rubber ring; The unloading baffle is fixedly connected to the upper surface of the upper pad through a pin; The upper end of the unloading ejector rod is connected to the unloading baffle through the rubber ring, and the lower end penetrates through the upper die plate and the die body.

4. The hot stamping die of claim 2, wherein: The upper surface of the edge ring is provided with a rectangular recess for mounting a positioning block and a mounting hole for mounting an elastic pin; The rectangular recess is internally provided with a rubber pad.

5. The hot stamping die of claim 2, wherein: The first cooling water channel comprises a first cooling pipeline arranged on the die body and cooling water inlet and outlet openings; The first cooling pipeline is parallel to the die surface profile of the die body; The first cooling pipeline is a blind hole with a diameter of 10 mm, the inner wall of the hole is 15 mm away from the nearest side wall of the die body, and the inlet of the blind hole is sealed by a close screw and a raw material belt; the center axis of each first cooling pipeline is 9-10 mm away from the die surface of the die body; The cooling water inlet and outlet openings are located on the side surface of the die body perpendicular to the center axis of the first cooling pipeline and are connected with the first cooling pipeline; The diameter of the cooling water inlet and outlet openings is 30 mm.

6. The hot stamping die of claim 4, wherein: The rectangular recess has two, which are distributed on the opposite sides of the inner ring of the edge ring; The length of the rectangular recess is 206 mm, and the depth is 20 mm.

7. The hot stamping die according to claim 1, characterized in that: The second cooling pipe is a blind hole with a diameter of 10 mm, the distance between the bottom surface of the blind hole and the side wall of the closest punch block is 16 mm, and the inlet of the blind hole is sealed by a jam screw and a raw material belt, the distance between the center axis of each second cooling pipe and the die surface of the punch block is between 9-10 mm; The water inlet and outlet are water grooves which are arranged in the punch block, 15 mm away from the side wall of the punch block, perpendicular to the bottom surface of the punch block, with a width of 10 mm, and connected with the second cooling pipe.

8. The hot stamping die of claim 5, wherein: The temperature measuring device is a thermocouple. The distance between the dendritic groove and the die surface of the punch block is 1.1 mm, and the groove depth is 2 mm.

9. The hot stamping die of claim 2, wherein: The guide mechanism includes guide columns and guide holes arranged at the four corner positions of the concave die body, the blank holder and the punch block; The guide columns are vertically arranged in the mold frame; The concave die body, the blank holder and the punch block are sleeved on the guide columns through the guide holes and move vertically along the guide columns.

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