CN105149428A - Thermal stamping processing method for blank forming and edge trimming, and thermal stamping processing mold device - Google Patents

Abstract

The present invention relates to a hot stamping processing method and a mold device, in particular to a hot stamping processing method and a mold device for blank forming and edge trimming which simultaneously realize blank forming and edge trimming. The hot stamping die device includes: a lower die, which has a first cooling surface, and the first cooling surface is in close contact with the formed portion of the heated blank to cool the formed portion; an upper die, at a first position close to the lower die and Move between the second position away from the lower mold, with a second cooling surface, which is opposite to the first cooling surface and pressurizes and cools the forming part of the blank together with the first cooling surface; the punch is arranged on the second of the upper mold Around the cooling surface, it moves between a third position where shear stress is applied to the blank to cut the boundary between the blank forming portion and the flash portion, and a fourth position away from the blank. The hot stamping processing of the present invention realizes forming and trimming at the same time, thereby reducing processing cost and time. In addition, since the hardness of the flash portion is low, the life of the trimming punch is increased, and the cutting surface is clean.

Description

Hot stamping processing method for blank forming and edge trimming and die device

technical field

The present invention relates to a hot stamping processing method and a mold device, more particularly, to a hot stamping processing method and a mold device for simultaneously realizing blank forming and trimming.

Background technique

In order to reduce weight and improve crash safety, hot stamped components with a tensile strength of 1.3 GPa or more after hot stamping are used for the body. The hot stamping process is a processing method in which boron steel heated to about 850-950°C is quickly transferred to a mold, and then pressurized before the steel plate is cooled and quenched in the mold. If this processing method is adopted, the material has a strength about 3 to 5 times higher than that before processing. Due to the effect of heat treatment similar to quenching, its strength is improved.

Hot stamped components have high strength and hardness, so trimming or punching by shear dies is almost impossible. Therefore, most of them use lasers to achieve edge trimming or hole processing. However, laser processing has a problem that the processing cost is high and time-consuming, so the efficiency is very low.

Therefore, recently, in order to improve the productivity and reduce the cost of shearing hot stamped members, the technology of processing with a shearing die is being studied. However, when shearing a hot stamped member having high hardness, there is a problem that the die life is too short.

prior art literature

patent documents

Patent Document 1: Korean Granted Patent No. 10-0907266

Contents of the invention

As described above, conventionally, a laser has been used to trim the edge of a hot-stamped member. This method has the problems of high processing cost and time-consuming. The present invention is proposed to solve the above problems, and aims to provide a method and a mold device capable of simultaneously realizing blank forming and edge trimming.

A hot stamping die device according to the present invention for achieving the above object includes: a lower die having a first cooling surface that is in close contact with a molding portion of a heated blank for cooling the molding portion. part; an upper mold that moves between a first position close to the lower mold and a second position away from the lower mold, and has a second cooling surface opposite to the first cooling surface , and together with the first cooling surface pressurize and cool the forming part of the blank; the punch, which is arranged around the second cooling surface of the upper die, and applies shear stress to the blank to cut The blank is moved between a third position at the boundary of the forming portion and the flash portion and a fourth position remote from the blank.

Preferably, the hot stamping die device further includes a heating support plate, which is arranged around the lower die and has a heating surface that supports and heats the burr portion of the blank.

The heated support plate may be configured to descend with the punch when the punch moves to the third position, and to return to the fly supporting the blank when the punch returns to the fourth position. position of the edge.

The heating support plate includes a groove formed on the heating surface, the electric heater is inserted into the groove, and the groove can be sealed by a heat transfer member. Preferably, the heat transfer component is copper.

In addition, preferably, a heat insulating material is provided between the lower mold and the heating support plate, and the heat insulating material is used to prevent heat exchange between the lower mold and the heating support plate.

Preferably, after the upper die is moved to the first position to cool the forming portion of the blank, the punch moves to a third position to cut the boundary between the forming portion and the flash portion of the blank.

The hot stamping processing method of the present invention for achieving the above purpose includes the following steps: (a) step, heating the blank to 850-950°C; (b) step, putting the heated blank into the upper mold between the lower mold and the lower mold; (c) the step of closing the upper mold and the lower mold to form the molding part of the blank into a prescribed shape, and cooling the blank at a cooling rate of 30°C to 100°C per second The forming part of the blank is cooled to below 200° C., and at the same time, the trimming part of the blank is air-cooled; (d) step, cutting the trimming part.

In the step (c), the temperature of the blank before starting to form is preferably above 700°C. In addition, in the step (d), the temperature of the flash portion is preferably 450° C. or higher.

Another hot stamping processing method of the present invention for achieving the above purpose may include the following steps: (a) step, heating the blank to 850-950°C; (b) step, putting the heated blank into Between the upper mold and the lower mold of the stamping die device; (c) step, the upper mold and the lower mold of the stamping die device are closed, the molding part of the blank is formed into a prescribed shape, and the mold is formed at a rate of 30 per second. Cooling the molded part of the blank to below 200°C at a cooling rate of 100°C to 200°C, while heating the trimming part of the blank; (d) step, cutting the trimming part.

The hot stamping process involved in the present invention realizes forming and trimming at the same time, thus reducing processing cost and time. In addition, the hardness of the flash portion is low, which prolongs the life of the punch used for edge trimming, and the cut surface is clean.

Description of drawings

FIG. 1 is a schematic diagram showing a mold-opening state in one embodiment of a hot stamping die apparatus according to the present invention.

Fig. 2 is a schematic view showing a closed state of the mold device shown in Fig. 1 .

Fig. 3 is a schematic diagram showing a state in which a punch of the mold device shown in Fig. 1 is lowered.

Fig. 4 is a schematic view showing a mold-opened state in another embodiment of the hot stamping die device according to the present invention.

Fig. 5 is a schematic view showing a closed state of the mold device shown in Fig. 4 .

Fig. 6 is a schematic diagram showing a state in which a punch of the mold device shown in Fig. 4 is lowered.

Reference signs:

10: Lower mold 11: The first cooling surface

12: Cooling water channel 20: Upper mold

21: Second cooling surface 22: Cooling water channel

30: punch 40: heating support plate

41: heating surface 43: electric heater

45: coil spring

Detailed ways

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments described below are provided only as examples in order to fully convey the idea of the present invention to those skilled in the art. Therefore, the present invention is not limited to the embodiments described below, but may also be implemented in other forms. In addition, in the drawings, the width, length, thickness, etc. of the constituent elements may be exaggerated for convenience of illustration. Throughout the specification, the same reference numerals denote the same constituent elements.

Fig. 1 is a schematic diagram showing a mold-opening state of an embodiment of a hot stamping die device according to the present invention, Fig. 2 is a schematic diagram showing a mold-closing state of the mold device shown in Fig. 1 , and Fig. 3 is a diagram showing A schematic diagram of the descending state of the punch of the die device shown in Fig. 1 is shown.

Referring to FIGS. 1 to 3 , a die set for hot stamping according to an embodiment of the present invention includes a lower die 10 , an upper die 20 and a punch 30 . The hot stamping die device according to this embodiment can perform blank forming and edge trimming simultaneously. The blank may be formed from a quench-hardened metallic material, such as boron steel. The blank is divided into the molding part A that constitutes the product and the flash part B that is the periphery of the molding part A that needs to be removed after molding.

In the present invention, the formed portion A and the flash portion B of the blank are heat-treated under different conditions, so that edge trimming can be easily performed after forming. The blank is thrown between the upper die 20 and the lower die 10 of the hot stamping die apparatus in a state heated to 850 to 950° C. by induction heating or heat treatment. The heated blank can be thrown in by a worker using pliers or the like, but it is preferable to put it in by a robot arm from the viewpoint of safety. The molded portion A of the blank thrown into the heated state between the upper mold 20 and the lower mold 10 is rapidly cooled while being molded. The blank that is cooled rapidly after being heated is hardened as if it had been quenched. After the forming part A of the blank is formed, its hardness is HRC41-50, the tensile strength is above 1.3GPa, and it is almost impossible to perform shearing. On the contrary, the flash portion B of the blank is not rapidly cooled by the lower mold 10 and the upper mold 20, but is slowly cooled in the air. Therefore, since the hardness of the burr portion B is lower than that of the formed portion A, it is easier to cut by the shear stress of the punch 30 .

The lower die 10 is combined with a lower die support plate 1 , and the lower die support plate 1 is supported by a backing plate (bolster) 2 . The lower mold 10 has a first cooling surface 11, and the first cooling surface 11 is closely attached to the lower surface of the forming part A of the blank for cooling the forming part A. The inside of the lower die 10 has a cooling water passage 12 through which cooling water flows. The first cooling surface 11 is cooled by the cooling water flowing through the cooling water channel 12 .

The upper die 20 is combined with the hammer 3, and the hammer 3 moves linearly up and down through the interval 4. The spacer 4 is used to ensure the installation space of the punch 30 combined with the upper die 20 .

The linear reciprocating motion of the hammer 3 can be realized by mechanisms such as a crankshaft (Crank), an eccentric wheel (Eccentric), a toggle (Toggle), a hinge (Link), a cam (Cam), or a hydraulic cylinder. The structure of the linear reciprocating motion of the hammer 3 is well known, so detailed description is omitted.

The upper mold 20 moves between a first position (see FIG. 2 ) close to the lower mold 10 and a second position (see FIG. 1 ) away from the lower mold 10 by the linear reciprocating motion of the hammer 3 . The upper mold 20 has a second cooling surface 21 that faces the first cooling surface 11 and pressurizes and cools the molding portion A of the blank together with the first cooling surface 11 . The second cooling surface 21 of the upper mold 20 is in contact with the upper surface of the molding portion A of the blank. When the upper mold 20 is located at the first position, the upper mold 20 and the lower mold 10 are in a mold-closed state, thereby pressurizing the molded part A. The first cooling surface 11 and the second cooling surface 21 have a surface shape that molds a heated blank into a predetermined shape. For example, it may have the shape of an automobile component that requires light weight and rigidity, such as a vehicle frame. When the upper mold 20 is in the second position, the upper mold 20 and the lower mold 10 are in the mold-opening state. At this time, the blank is dropped into between the lower mold 10 and the upper mold 20, or the blank that has been formed and trimmed is removed.

The punch 30 functions to apply a shear stress to the blank so as to cut the flash portion B from the formed portion A of the blank. The punch 30 is disposed in the through hole 23 formed along the periphery of the second cooling surface 21 of the upper die 20 . The punch 30 can be linearly reciprocated by a hydraulic cylinder 31 . The punch 30 moves between a third position (see FIG. 3 ) where the blank is cut by applying shear stress to the blank, and a fourth position (see FIG. 1 ) remote from the blank.

After the upper mold 20 and the lower mold 10 are closed to perform blank forming, the punch 30 is lowered to cut the burr portion B. FIG. Since the blank is deformed during the forming process, cutting is preferably performed after the blank has been formed. Preferably, the blank is cut when the temperature of the molded part A of the blank is cooled to about 200°C. Since the flash portion B of the blank is air-cooled, when the temperature of the forming portion A of the blank is 200° C., the flash portion B of the blank is maintained at a temperature much higher than this temperature, thereby making it easy to cut. When the blank flash portion B is cut, the temperature of the blank flash portion B is preferably 450° C. or higher.

Next, the action of the hot stamping die device will be described.

Heat the blank to 850-950°C by heat treatment or the like.

The upper mold 20 is located at the second position, and cooling water is pre-supplied in the cooling water passages 12 and 22 of the upper mold 20 and the lower mold 10 before the blank is put into the mold. The first cooling surface 11 and the second cooling surface 21 of the upper mold 20 and the lower mold 10 are cooled by the supplied cooling water.

The heated blank is put into between the upper mold 20 and the lower mold 10 by the robot arm, and the upper mold 20 lowers to the first position while pressing and cooling the forming part A of the blank, so that the upper mold 20 and the lower mold The shape of the first cooling surface 11 and the second cooling surface 21 of 10 shapes the blank. The heated blank is cooled while it is thrown into the space between the upper mold 20 and the lower mold 10 by the robot arm, so the temperature before the start of forming is lower than the temperature when it is discharged from the heat treatment furnace. Preferably, the blank temperature before the start of molding is 700°C or higher. The blank is cooled to below 200°C at a cooling rate of 30°C to 100°C per second.

When the temperature of the formed portion A of the blank reaches about 200° C., the punch 30 is lowered to cut the burr portion B which is being cooled in the air. The punch 30 descends when the time previously input to the control box (not shown) elapses. Since the relationship between time and blank temperature is determined based on pre-measured data, a separate temperature sensor for measuring blank temperature can be omitted. The flash portion B of the blank is cooled in the air, and therefore, maintains a higher temperature than the forming portion A of the blank, making it easier to cut. When the blank flash portion B is cut, the temperature of the blank flash portion B is preferably 450° C. or higher.

Fig. 4 is a schematic view showing the mold opening state of another embodiment of the hot stamping die device according to the present invention, Fig. 5 is a schematic view showing the mold closing state of the die device shown in Fig. 4 , and Fig. 6 is A schematic diagram showing a state in which the punch of the die device shown in FIG. 4 is lowered.

This embodiment is different from the embodiments shown in FIGS. 1 to 3 , and further includes a heating support plate 40 . The heating support plate 40 has a heating surface 41 for supporting and heating the flash portion B of the blank. The heating support plate 40 is disposed around the first cooling surface 11 of the lower mold 10 . Preferably, the heating support plate 40 is at a predetermined distance from the lower die 10 . The reason is that there is a possibility of unnecessarily heating the lower mold 10 and the forming portion A of the blank. In addition, it is preferable to provide a heat insulating material 47 between the lower mold 10 and the heating support plate 40 .

The heating support plate 40 is fixed on the support plate 1 of the lower mold through a coil spring 45 , and the coil spring 45 provides elastic force to make the heating support plate 40 move away from the support plate 1 of the lower mold. A groove 42 is formed on the heating surface 41 of the heating support plate 40 , and an electric heater 43 is disposed in the groove 42 . A heat transfer member 44 such as copper may be filled between the electric heater 43 and the tank 42 . When the punch 30 descends and presses the blank, the coil spring 45 is compressed and the heating support plate 40 descends. After the flash portion B of the blank is cut by the punch 30, the punch 30 rises, and the coil spring 45 is stretched to restore the heating support plate 40 to its original position.

Compared with the embodiments shown in FIGS. 1 to 3 , this embodiment has the disadvantage of complex structure. However, in the embodiment shown in FIGS. 1 to 3, although the flash portion B of the blank is not in direct contact with the first cooling surface 11 and the second cooling surface 21, it may be rapidly cooled and hardened by heat conduction. The embodiment prevents these problems and is therefore more effective than the embodiment shown in FIGS. 1 to 3 .

The above-described embodiments are merely illustrative of preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the illustrated embodiments. It should be understood that, for those of ordinary skill in the art, within the scope not exceeding the technical idea and protection scope of the present invention, various changes, deformations or replacements can be made, and these embodiments all belong to the protection scope of the present invention Inside.

Claims (9)

1. a drop stamping processing mold device, it comprises:

Counterdie, it has the first cooling surface, and this first cooling surface is close to by the forming part of the blank heated, to cool described forming part;

Patrix, it is moving close between the primary importance of described counterdie and the second place away from described counterdie, and have the second cooling surface, this second cooling surface is relative with described first cooling surface, and pressurizes together with described first cooling surface and cool the forming part of described blank;

Drift, it is arranged on around the second cooling surface of described patrix, and is applying shear stress to move between the 3rd position on the border of the forming part and overlap portion of cutting described blank and the 4th position away from described blank to described blank;

Heated support plate, it is arranged on around described counterdie, has the heating surface in the overlap portion supporting and heat described blank.

2. drop stamping processing mold device as claimed in claim 1, is characterized in that,

When described drift moves to the 3rd position, described heated support plate declines together with described drift, and when described drift returns to the 4th position, described heated support plate turns back to the position in the overlap portion supporting described blank.

3. drop stamping processing mold device as claimed in claim 1, is characterized in that,

Described heated support plate is included in the groove that heating surface is formed, in described groove, be inserted with electric heater, and described groove is sealed by heat transfer component.

4. drop stamping processing mold device as claimed in claim 3, is characterized in that,

Described heat transfer component is copper.

5. drop stamping processing mold device as claimed in claim 1, is characterized in that,

Between described counterdie and described heated support plate, be provided with heat-barrier material, this heat-barrier material is for preventing the heat exchange between described counterdie and described heated support plate.

6. drop stamping processing mold device as claimed in claim 1, is characterized in that,

Described patrix moves to primary importance with after the forming part cooling described blank, and described drift moves to the 3rd position with the border of the forming part and overlap portion of cutting described blank.

7. a drop stamping processing method, comprises the steps:

A () step, is heated to 850 ~ 950 DEG C by blank;

B () step, puts between the patrix of punching die device and counterdie by the described blank through heating;

(c) step, make the upper die and lower die mold closing of described punching die device, the forming part of described blank is shaped to regulation shape, and with the cooling velocity of 30 DEG C to 100 DEG C per second, the forming part of described blank is cooled to less than 200 DEG C, meanwhile, the heating surface by being arranged on the heated support plate around described counterdie supports and heats the overlap portion of described blank;

D () step, cuts described overlap portion.

8. drop stamping processing method as claimed in claim 7, is characterized in that,

In described (c) step, the temperature of the described blank before shaping beginning is more than 700 DEG C.

9. drop stamping processing method as claimed in claim 7, is characterized in that,

In described (d) step, the temperature in described overlap portion is more than 450 DEG C.