A method for producing hot stamping parts

Abstract

The embodiment of the present application provides a method for producing hot stamping parts, the method comprising: determining the sheet size and hot stamping process parameters; according to the sheet size and the hot stamping process parameters, blanking the sheet and performing austenitizing heat treatment to generate an initial sheet; hot stamping the initial sheet without holding pressure to generate a hot formed part; hot punching and hot trimming the hot formed part to generate an initial part; holding pressure quenching the initial part to generate a target part; and testing the shape accuracy and performance of the target part. The technical solution of the embodiment of the present application enables the part to complete punching and trimming under very low strength, and then perform holding pressure quenching to improve the strength of the part.

Description

Technical Field

[0001] The present application relates to the technical field of stamping technology, and in particular to a method for producing hot stamping parts. Background Art

[0002] Generally, the tensile strength of hot-formed parts can be above 1350MPa. With the development of higher-strength materials, hot-formed steel with a tensile strength of 1800MPa and 2GPa has been developed. After the application of high-strength hot-formed steel, the strength of the stamped hot-formed parts is very high. High strength is an advantage of this part, but because the strength of the part is too high, it also has certain disadvantages. For example, it is difficult to perform subsequent punching and trimming. For such high-strength automotive parts, the edge is greatly damaged during the punching and trimming process. It is easy to cause the punching and trimming molds to need to be repaired after a small number of parts have been punched and trimmed.

[0003] Based on this, technical personnel in this field urgently need a production method for hot stamping parts, which can complete punching and trimming of parts under very low strength conditions, and then perform pressure holding quenching to improve the strength of the parts. Summary of the invention

[0004] The embodiments of the present application provide a method for producing hot stamping parts, which can, at least to a certain extent, enable the parts to complete punching and trimming under very low strength conditions, and then perform pressure-holding quenching to improve the strength of the parts.

[0005] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by the practice of the present application.

[0006] According to one aspect of an embodiment of the present application, a method for producing hot stamping parts is provided, the method comprising: determining a sheet size and hot stamping process parameters; blanking the sheet according to the sheet size and the hot stamping process parameters, and performing an austenitizing heat treatment to generate an initial sheet; hot stamping the initial sheet without holding pressure to generate a hot-formed part; hot punching and hot trimming the hot-formed part to generate an initial part; holding pressure quenching the initial part to generate a target part; and performing shape accuracy and performance testing on the target part.

[0007] In some embodiments of the present application, the determining of sheet material size and hot stamping process parameters includes: determining a reasonable sheet material size and contour, and specific values ​​of hot stamping process parameters based on stamping simulation and collision simulation analysis of the target part.

[0008] In some embodiments of the present application, blanking the sheet material includes: blanking the sheet material by various technical means such as a shearing machine, a blanking line and laser cutting.

[0009] In some embodiments of the present application, the austenitizing heat treatment to generate the initial sheet material includes: heating the sheet material in a heating furnace and keeping the temperature for a set time, so that the sheet material is completely austenitized to generate the initial sheet material.

[0010] In some embodiments of the present application, the hot stamping of the initial sheet material includes: transferring the initial sheet material to a press machine for hot stamping.

[0011] In some embodiments of the present application, the hot punching and hot trimming of the thermoformed part to generate the initial part includes: the lifting cylinder action of the lower worktable of the press to lift the punching die and the trimming die to move upward to cut off the excess sheet material at the punching holes and edges of the thermoformed part.

[0012] In some embodiments of the present application, the holding pressure for pressurizing and quenching the initial part is 1000 kN to 8000 kN, and the holding time is 5S to 10S.

[0013] In some embodiments of the present application, the method further includes: designing and developing a target part; and designing and developing a mold for the target part.

[0014] In some embodiments of the present application, based on the aforementioned scheme, the design and development of hot stamping parts includes: determining the positions of punching and trimming of the target parts through the design and development of the hot stamping parts.

[0015] In some embodiments of the present application, based on the aforementioned scheme, the design and development of the hot stamping part mold includes: designing and developing related molds based on the completed designed target part.

[0016] Based on the above solution, the technical solution provided by this application has at least the following advantages and improvements:

[0017] The technical solution provided by the present application, through the combination of hot punching, hot trimming and hot stamping, enables the parts to complete punching and trimming under very low strength conditions. Then pressure-holding quenching is carried out to improve the strength of the parts. Thereby, the subsequent laser cutting process can be omitted. If hot punching cannot be performed at individual locations, hot punching can also be achieved by optimizing the design of parts and molds. In extremely rare cases, when laser cutting must be used for punching, the process technology of the invention can also be used to complete hot punching and hot cutting at other locations first, thereby saving the cost and time of laser cutting.

[0018] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present application, and together with the specification, are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0020] Figure 1 A flow chart showing a method for producing a hot stamping part according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0021] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be more comprehensive and complete and fully convey the concept of the example embodiments to those skilled in the art.

[0022] See also Figure 1 .

[0023] Figure 1 A flow chart showing a method for producing a hot stamping part according to an embodiment of the present application is shown. Figure 1 As shown, the method may include steps S101-S106:

[0024] Step S101, determining sheet material size and hot stamping process parameters.

[0025] Step S102, according to the sheet size and the hot stamping process parameters, the sheet is blanked and austenitized to generate an initial sheet.

[0026] Step S103, hot stamping the initial sheet material without holding the pressure to generate a hot-formed part.

[0027] Step S104, hot punching and hot trimming are performed on the hot formed part to generate an initial part.

[0028] Step S105, performing pressure-maintaining quenching on the initial part to generate a target part.

[0029] Step S106, performing shape accuracy and performance testing on the target part.

[0030] The technical solution provided by the present application, through the combination of hot punching, hot trimming and hot stamping, enables the parts to complete punching and trimming under very low strength conditions. Then pressure-holding quenching is carried out to improve the strength of the parts. Thereby, the subsequent laser cutting process can be omitted. If hot punching cannot be performed at individual locations, hot punching can also be achieved by optimizing the design of parts and molds. In extremely rare cases, when laser cutting must be used for punching, the process technology of the invention can also be used to complete hot punching and hot cutting at other locations first, thereby saving the cost and time of laser cutting.

[0031] In the present application, the determination of sheet material size and hot stamping process parameters includes: determining a reasonable sheet material size and profile, as well as specific values ​​of hot stamping process parameters based on stamping simulation and collision simulation analysis of the target part.

[0032] In this application, the reasonable sheet material size and profile, as well as the specific values ​​of the hot stamping process parameters can be determined based on the stamping simulation and collision simulation analysis of the parts. Compared with the previous trial and error method, the application of simulation technology has greatly improved production efficiency and reduced production costs. For automotive parts, the parts are mainly required to meet stamping performance and collision performance. At the same time, save costs as much as possible to improve the cost performance of the car. At present, there are a variety of simulation software that can be used for stamping and collision simulation analysis of automotive parts. Through simulation analysis, the optimal sheet material profile size and process parameter values ​​are finally determined.

[0033] In the present application, blanking the sheet material includes: blanking the sheet material by various technical means such as a shearing machine, a blanking line and laser cutting.

[0034] In this application, the actual sheet material can be blanked according to the sheet material profile and size determined by the design. The sheet material is blanked at room temperature, and the actual sheet material can be blanked by various technical means such as shearing machine, blanking line and laser cutting. Thus, the original sheet material is provided for the subsequent stamping production.

[0035] In the present application, the austenitizing heat treatment to generate the initial sheet material includes: heating the sheet material in a heating furnace and keeping the temperature for a set time, so that the sheet material is completely austenitized to generate the initial sheet material.

[0036] In this application, the sheet is heated in a heating furnace and kept warm for a certain period of time so that the sheet is completely austenitized. When a roller bottom heating furnace is used, the heating temperature is usually set from 850°C to 930°C, and the heating time is usually 3 minutes to 8 minutes. Different parts have different thicknesses, so the thickness of the sheet is also inconsistent. The required austenitizing holding temperature and holding time should also be adjusted accordingly according to the actual parts and sheets.

[0037] In the present application, the hot stamping of the initial sheet material includes: transferring the initial sheet material to a press machine for hot stamping.

[0038] In the present application, the initial sheet material after austenitizing heat treatment can be quickly transferred to a press for stamping. The sheet material is usually transferred by a manipulator and placed on the supporting device of the mold. After the sheet material is placed, the upper worktable of the press moves downward, which will drive the upper mold to move downward, and then the sheet material is stamped and formed. Stamped into the actual part shape. After stamping, the press does not apply pressure to maintain the pressure, so as to avoid rapid cooling of the parts, increase the strength, and be unfavorable for the hot punching and hot cutting of the next process. This process has high requirements on the stamping speed and stop position of the press. During the stamping process, the press completes the stamping action as soon as possible, and accurately stops the downward movement after completing the stamping to avoid applying pressure to the parts. For parts with a certain degree of tolerance in shape accuracy, the gap between the upper mold and the lower mold can be appropriately increased when the upper mold stops, thereby reducing the heat transfer from the sheet material to the mold.

[0039] In the present application, the hot punching and hot trimming of the thermoformed part to generate the initial part may include: the cylinder-pushing action of the lower worktable of the press to lift the punching die and the trimming die to move upwards, and cut off the excess sheet material at the punching holes and edges of the thermoformed part.

[0040] After the sheet is hot stamped into the shape of the part, the punching die and trimming die are lifted up by the top cylinder of the worktable under the press to move upward, and the sheet at the punching position and the edge is cut off. The hot-formed part has not yet undergone complete martensitic transformation at high temperature, and the strength of the material is not high at this time. It is easy to punch and trim. The higher the temperature of the sheet during hot punching and hot trimming, the lower the strength of the material.

[0041] During the hot forming process, the strength of the material is significantly affected by temperature. The relationship between the mold hot punching gap and hot trimming gap and temperature is shown below. The sheet temperature can be obtained by welding thermocouple detection on the sheet, buried welding thermocouple on the mold, and infrared temperature measurement.

[0042] The relationship between the specific mold hot punching gap and hot trimming gap and temperature can be shown in Table 1:

[0043] Table 1 Relationship between die hot punching gap and hot trimming gap and temperature

[0044] Sheet temperature T / ℃ Thermal cutting edge clearance Hot punching clearance T≥800 12％ 9％ 800＞T≥750 11％ 8％ 750＞T≥700 10％ 7％ 700＞T≥650 9％ 6％ 650＞T 8％ 5％

[0045] In the present application, the holding pressure for pressurizing and quenching the initial part may be 1000 kN to 8000 kN, and the holding time may be 5S to 10S.

[0046] In this application, after hot punching and hot trimming, the press applies pressure to hold and quench the parts. The holding quenching is used to improve the strength of the parts. Generally, the greater the pressure, the higher the quenching efficiency of the parts, the more significant the heat exchange between the hot parts and the cold mold, and the more conducive to the martensitic transformation of the sheet. The holding pressure usually ranges from 1000kN to 8000kN, and the holding time ranges from 5s to 10s.

[0047] In this application, after the hot stamping process is completed, the parts can be taken out to test the shape accuracy of the parts. Because the parts are formed at high temperature and pressure-holding quenching is performed at the same time, the pressure-holding quenching process also has the function of shaping, so the springback of the hot stamping parts is very small, and the parts can usually be made within the required shape accuracy. At the same time, the organization and performance of the parts need to be tested. Thus, it is determined whether the performance of the parts meets the requirements. By checking the shape accuracy and organizational performance of the parts, if they are qualified, further adjustment of the parameters is not necessary; if there are unqualified places in the test, it is necessary to further optimize and adjust the relevant parameters of the material, sheet material and stamping process. Thereby ensuring that the shape accuracy and organizational performance of the parts meet the requirements.

[0048] In the present application, the method may further include: designing and developing a target part; and designing and developing a mold for the target part.

[0049] In the present application, the method for designing and developing a hot stamping part may include: determining the positions of punching holes and trimming edges of a target part through designing and developing the hot stamping part.

[0050] In this application, in the process of developing new automobile models, it is usually necessary to design new hot stamping parts, or design the original cold stamping parts into hot stamping parts. Through the design of hot stamping parts, the positions of punching and trimming of parts are determined, and the subsequent welding and installation requirements are met.

[0051] In the present application, the method for designing and developing the hot stamping part mold may include: designing and developing related molds based on the designed target part.

[0052] Based on the designed hot stamping parts, the relevant molds are designed and developed. In order to realize this new process method, the structural position of hot punching and hot cutting edge needs to be designed. At the same time, it is ensured that the water channel of the parts does not interfere with the punching.

[0053] On the working table of the hot stamping press, the lower working table can be designed with an ejector pin and an ejector device, and the ejector device can be designed and installed with a punching and trimming module. After the stamping is completed, the ejector device ejects the punching and trimming die to cut off the holes and edge materials.

[0054] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the embodiments disclosed herein. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include common knowledge or customary technical means in the art that are not disclosed in the present application.

[0055] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A method for producing hot stamping parts, characterized in that: The method comprises: Determine sheet size and hot stamping process parameters; According to the sheet size and the hot stamping process parameters, the sheet is blanked and subjected to austenitizing heat treatment to generate an initial sheet; Hot stamping the initial sheet material without holding the pressure to generate a hot-formed part; Performing hot punching and hot trimming on the hot formed part to generate an initial part; Performing pressure-maintaining quenching on the initial part to generate a target part; Performing shape accuracy and performance testing on the target part; The step of hot punching and hot trimming the hot formed part to generate an initial part comprises: The lifting cylinder of the lower worktable of the press moves to lift the punching die and the trimming die to move upward, and cut off the excess sheet material at the punching hole and the edge of the hot-formed part; The relationship between the temperature T of the thermoformed part and the gap between the punching die and the trimming die includes: When the temperature T of the hot-formed part is ≥800°C, the hot trimming clearance of the trimming die is 12%, and the hot punching clearance of the punching die is 9%; When the temperature T of the hot-formed part is 800°C>T≥750°C, the hot trimming clearance of the trimming die is 11%, and the hot punching clearance of the punching die is 8%; When the temperature T of the hot-formed part is 750°C>T≥700°C, the hot trimming clearance of the trimming die is 10%, and the hot punching clearance of the punching die is 7%; When the temperature T of the hot-formed part is 700°C>T≥650°C, the hot trimming clearance of the trimming die is 9%, and the hot punching clearance of the punching die is 6%; When the temperature T of the hot-formed part is 650°C>T, the hot trimming clearance of the trimming die is 8%, and the hot punching clearance of the punching die is 5%.

2. The method according to claim 1, characterized in that The step of determining sheet material size and hot stamping process parameters includes: Based on the stamping simulation and collision simulation analysis of the target parts, the reasonable sheet size and contour, as well as the specific values ​​of the hot stamping process parameters are determined.

3. The method according to claim 1, characterized in that The step of blanking the sheet material comprises: The blanking of the sheet metal is carried out by shearing machines, blanking lines and laser cutting.

4. The method according to claim 1, characterized in that: The austenitizing heat treatment to generate the initial sheet material comprises: The sheet material is heated in a heating furnace and kept at the temperature for a set time, so that the sheet material is completely austenitized to generate an initial sheet material.

5. The method according to claim 1, characterized in that The hot stamping of the initial sheet material comprises: The initial sheet material is transferred to a press for hot stamping.

6. The method according to claim 1, characterized in that The holding pressure for the pressure-holding quenching of the initial part is 1000 kN to 8000 kN, and the holding time is 5S to 10S.

7. The method according to claim 1, characterized in that The method further comprises: Design and develop target parts; Design and develop molds for target parts.

8. The method according to claim 7, characterized in that The design and development of target parts includes: Through the design and development of the target parts, the punching and trimming positions of the target parts are determined.

9. The method according to claim 7, characterized in that: The design and development of the target part mold includes: Based on the designed target parts, design and develop related molds.

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