Patent Application
20250222505
This U.S. Patent Application claims the benefit of CN Patent Application Serial No. 20/241,00309786 filed on Jan. 9, 2024 and titled “PRODUCTION METHOD AND DIE FOR HOT STAMPED MEMBER COMPRISING LOCAL SOFT REGION, AND HOT STAMPED MEMBER”, the entire disclosure of which is hereby incorporated by reference.
The present invention relates to the technical field of hot stamping, and in particular to a production method and die for a hot stamped member comprising a local soft region, and a hot stamped member.
At present, the use of lightweight materials such as high-strength hot stamping steel in place of conventional steel materials has become an important way to reduce the weight of automobiles. However, since the hardness of base materials of high-strength hot stamped parts is too high, the problem of riveting difficulty is present in vehicle body assembly and the like. In order to solve this problem, it is generally necessary to perform softening treatment at a connection position on a corresponding hot stamped part, so as to lower material hardness, thereby facilitating riveting without affecting the overall performance of the part. In addition, a softened region of a hot stamped part also has a good energy-absorbing effect in the event of a vehicle collision, thereby reducing the impact on passengers within the vehicle. Therefore, hot stamped parts for vehicles often need to be locally softened (Tailored Tempering Properties, TTP). A softened region may have microstructures including ferrite or bainite and pearlite, and ferrite or bainite and pearlite have lower yield strength and greater ductility than martensite.
Soft region formation technology is still in the development stage at present, and although a variety of process methods for achieving performance exist, many problems still occur in mass production. The main problems include severe dimensional deviations of parts, difficulty in ensuring stability, high maintenance costs of hot stamping dies, etc. Among existing patents, all patents involving soft region formation technology have limits regarding shapes. When the area of a soft region and a transition region is large, the performance and the size of parts cannot be both ensured.
The main reason why the size of a formed soft region cannot be ensured is because during shaping of a slab, a certain temperature is ensured therefor, so that austenite therein is transformed into bainite and pearlite. After stamping, the temperature of a soft region of a part is about 500 to 550 degrees Celsius, but the temperature of a hard region is 100 to 250 degrees Celsius. After cooling, both the temperature of the soft region and the temperature of the hard region are lowered to room temperature, and a large temperature difference therebetween causes the soft region and the hard region to shrink to different sizes during the cooling process, finally resulting in difficulty ensuring the dimensional stability thereof. Therefore, development of a production method for a hot stamped member having high dimensional stability and comprising a local soft region is a technical problem that needs to be solved.
In view of the above defects in the prior art, the present invention provides a production method and die for a hot stamped member comprising a local soft region, and a hot stamped member. According to this method, a soft region is provided with ribs during thermoforming, and the ribs shrink during shaping to compensate for a dimensional change caused by the soft region cooling and shrinking, thereby not only ensuring the performance of a soft region of a part, but also solving the problems of severe dimensional deviation and poor dimensional stability after TTP formation.
In order to achieve the above objective, in one aspect, the present invention provides a production method for a hot stamped member comprising a local soft region. The method includes the following steps:
Further, the TTP thermoforming die has soft and hard regions, and the soft region employs an in-die heating TTP process, the die removal temperature thereof being higher than the die removal temperature of the hard region by 250° C. to 350° C.
Further, in step S103, the pressure is applied by means of an insert mounted in the shaping die, to press the ribs of the soft region lower and wider until they are the same shape as the digital product model.
Further, in step S103, the ribs of the soft region are pressed lower and wider under the pressure so as to be flush with a hard region of an adjacent section.
In another aspect, the present invention provides a production die for a hot stamped member comprising a local soft region. The production die is used to implement the above production method. The production die comprises a TTP thermoforming die and a shaping die, with several ribs protruding from the TTP thermoforming die in a soft region position, the height and the width of the ribs depending on the length to which the soft region cools and shrinks, and the shaping die pressing, when pressure is applied, the ribs of the soft region lower and wider until they are the same shape as a digital product model.
Further, the shaping die applies pressure by an insert mounted in the die.
Further, a cooling water channel is provided in the insert.
In yet another aspect, the present invention provides a hot stamped member, comprising a local soft region, and which is produced by the above production method.
Compared with the prior art, the present invention has the following advantages or beneficial effects:
The present invention and the features, the shape, and advantages thereof will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following accompanying drawings. The same reference numerals refer to the same portions throughout the accompanying drawings. The accompanying drawings are not completely drawn to scale, and the focus is to show the substance of the present invention.
Exemplary embodiments of the present disclosure will be described in further detail below with reference to the accompanying drawings. It should be understood that all of these described exemplary embodiments are merely part of rather than all of the embodiments and examples of the present invention. Instead, these exemplary embodiments are provided so that those skilled in the art can more thoroughly understand the present disclosure, and the technical content of the present disclosure can be more completely conveyed to those skilled in the art.
Referring to
In step S101, the method includes heating a slab in a heating furnace to fully austenitize the same.
In step S102, the method includes moving the slab into a TTP thermoforming die. Referring to
In step S103, the method includes rapidly moving a thermoformed member from the TTP thermoforming die into a shaping die, and shaping the soft region in the shaping die. Referring to
In step S104, the method includes removing a shaped part from a shaping press.
As a preferred embodiment, this process consists of the heating furnace, a robot I, the thermoforming die, a robot II, the shaping die, and a robot III. The heating furnace heats the slab to austenitize the same. The robot I places the heated slab in the TTP thermoforming die. The TTP thermoforming die presses the slab into a semi-finished part having soft and hard regions. The robot II places the semi-finished part in the shaping die. The shaping die presses the ribs in the soft region of the part lower, and stretches the same wider to finally form a desired product, and the robot III removes the desired product from the shaping die. Certainly, the robots I, II, and III are mainly for distinguishing between implementations of robot actions, and implementations are not necessarily performed by using three robots.
The TTP thermoforming die has soft and hard regions. Preferably, the soft region employs an in-die heating TTP process, and the die removal temperature thereof is higher than the die removal temperature of the hard region by 250° C. to 350° C.
It can be understood that during the shaping in step S103 of the present invention, the pressure that presses the ribs in the soft region lower and wider until they are the same shape as the digital product model may be applied externally. As a preferred embodiment, in step S103, the pressure is applied by an insert mounted in the shaping die, to press the ribs of the soft region lower and wider until they are the same shape as the digital product model. Further still, a cooling water channel is provided in the insert, so as to cool the soft region of the part rapidly.
According to the production method provided in the present embodiment, ribs are provided in a soft region during thermoforming, and the shrinking of the ribs during shaping is utilized to compensate for a dimensional change caused by the soft region cooling and shrinking. In addition, the height of the ribs that have been pressed lower and the increased width do not affect the overall effect of a product, thereby not only ensuring the performance of a soft region of a part, but also solving the problems of severe dimensional deviation and poor dimensional stability after TTP formation.
The present embodiment provides a production method for a hot stamped member comprising a local soft region. Referring to
The present embodiment provides a production die for a hot stamped member comprising a local soft region, used to implement the production method in Embodiment 1 or Embodiment 2. The production die includes a TTP thermoforming die and a shaping die, with several ribs protruding from the TTP thermoforming die in a soft region position. The height and the width of the ribs depend on the length to which the soft region cools and shrinks. The shaping die presses, when pressure is applied, the ribs of the soft region lower and wider until they are the same shape as a digital product model.
As a preferred embodiment, the shaping die applies pressure by an insert mounted in the die.
The present embodiment provides a hot stamped member, including a local soft region and produced by the production method in Embodiment 1 or Embodiment 2.
In summary, the present invention provides a production method and die for a hot stamped member comprising a local soft region, and a hot stamped member. The production method includes the steps of moving an austenitized slab into a TTP thermoforming die, the TTP thermoforming die pressing several ribs at a soft region position, moving a thermoformed member from the TTP thermoforming die into a shaping die, and pressing, when pressure is applied, the ribs of the soft region lower and wider until they are the same shape as a digital product model, etc. According to the present invention, a soft region is provided with ribs during thermoforming, the shrinking of the ribs during shaping is utilized to compensate for a dimensional change caused by the soft region cooling and shrinking, thereby not only ensuring the performance of a soft region of a part, but also solving the problems of severe dimensional deviation and poor dimensional stability after TTP formation.
It should be noted that configurations of power mechanisms, power supply systems, control systems, etc., of apparatuses (for example, the heating furnace, the dies, and the robots) in the present application document are not completely described, but those skilled in the art understanding the principles of the invention can clearly learn details of the power mechanisms, the power supply systems, and the control systems thereof.
The preferred embodiments of the present invention have been described above. It is to be understood that the present invention is not limited to the particular embodiments described above, and that devices and structures not described in detail should be understood to be implemented by using common means in the art. Any person skilled in the art can make many possible variations and modifications to the technical solution of the present invention by using the above-disclosed methods and technical contents without departing from the scope of the technical solution of the present invention, or change the same into equivalent embodiments of equivalent variations, without affecting the substance of the present invention. Therefore, any simple changes, equivalent variations, or modifications made to the above embodiments according to the technical substance of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection of the technical solution of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2024100309786 | Jan 2024 | CN | national |
