US20180071806A1

US20180071806A1 - Multi-station continuous hot stamping production line and method

Info

Publication number: US20180071806A1
Application number: US15/560,038
Authority: US
Inventors: Yanli Song; Lin Hua; Yuhan SHEN; Dingguo DAI; Genpeng ZHU; Jue Lu
Original assignee: Wuhan University of Technology WUT
Current assignee: Wuhan University of Technology WUT
Priority date: 2015-10-29
Filing date: 2016-07-05
Publication date: 2018-03-15
Also published as: CN105215160B; CN105215160A; WO2017071294A1

Abstract

A production line sequentially includes a feeding platform, a feeding robot, a pressing unit, a conveying robot, a quenching device, a discharging robot, and a conveyor belt. The pressing unit includes a heating device, a die device, and at least one press used for mounting the die device. The heating device is used for wholly or partially heating the preformed blank to produce a hot blank, and the die device is used for stamping the hot blank, holding the hot blank at a certain pressure, and shaving and punching the hot blank, so as to produce a hot stamped part. The production line can continuously achieve rapid heating, stamping, pressure holding, shaving, punching, and quenching. Heating efficiency is improved, and a transferring process before stamping the hot blank is avoided.

Description

FIELD OF THE INVENTION

The present disclosure relates generally to the technical field of hot stamping, and in particular, to a multi-station continuous hot stamping production line and a method of operating the same.

BACKGROUND OF THE INVENTION

Hot stamping is a new technology for forming light-weight and high-strength parts. It has advantages of being able to produce stamped parts having small springback ratio, good fittability and high dimensional accuracy. Use of stamped car parts made of light-weight and high-strength sheet materials can help to improve safety performance of cars and reduce weight of cars, thereby contributing to achievement of light weight of cars.
In a traditional hot stamping process, a preformed blank made of a light-weight and high-strength sheet material is first heated to a hot stamping temperature; then the heated blank is rapidly transferred to a die, immediately stamped, held at a pressure, and quenched to complete a structural transformation thereof; after that, the hot stamped part is cooled at room temperature, and finally cut by a laser to produce a product.
A hot stamping production line generally comprises a feeding platform, a manipulator, a heating furnace, a transmission system, a press, and a laser cutting system. At present, hot stamping technologies studied in China are mainly used on ultra-high-strength sheet steel. Existing hot stamping production lines have the following problems. First, because a blank of ultra-high-strength sheet steel is usually heated in a roller hearth heating furnace, a large amount of heat can be lost in a shaft and in air, which may decrease the heating efficiency. Second, transferring process of the blank prolongs the production period, and meanwhile the hot blank is contacted with air, which results in great heat loss and oxidation (oxidation is particularly true of bare sheets that are widely used in China). An oxide coating formed on the sheet can easily wear a surface of the stamping die. Third, the quenched hot stamped part has an ultra-high strength and rigidity and is usually cut using a laser in practice which is very time-consuming and costing. For bare sheet hot stamping, a subsequent shot peening operation is required. In other countries, researches are also being done of hot stamping of aluminum alloy sheets, which, however, has same problems such as low heating efficiency, time-consuming hot blank transferring, rapid cooling of the hot blank, etc. It is urgent to solve these problems in order to improve production efficiency and achieve continuous, rapid, and stable production.

SUMMARY OF THE INVENTION

The objective of the present disclosure is to provide a multi-station continuous stamping production line and method, which can continuously achieve rapid heating, stamping, pressure holding, shaving, punching, and quenching, and enhance production efficiency. Heating efficiency is improved, and a transferring process before stamping the hot blank is avoided. For a hot stamped part made of sheet steel, punching and shaving thereof at high temperature avoids an increase of cutting difficulty caused by formation of martensites at normal temperatures. Punching and shaving forces are decreased and desired cutting edges can be obtained.
In order to achieve the above objective, the present disclosure provides the following technical solutions.
A multi-station continuous hot stamping production line is provided. The production line sequentially comprises a feeding platform, a feeding robot, a pressing unit, a conveying robot, a quenching device, a discharging robot, and a conveyor belt. The feeding platform is used for placing a preformed blank. The feeding robot is used for transferring the preformed blank to the pressing unit. The pressing unit includes a heating device, a die device, and at least one press used for mounting the die device, wherein the heating device is used for wholly or partially heating the preformed blank to produce a hot blank, and the die device is used for stamping the hot blank, holding the hot blank at a certain pressure, and shaving and punching the hot blank, so as to produce a hot stamped part. The conveying robot is used for conveying the hot stamped part to the quenching device. The quenching device is used for quenching the hot stamped part, and the discharging robot is used for transferring a quenched workpiece to the conveyor belt.
According to the above technical solution, the heating device is an electrical heating device which comprises a power supply, electrodes, and insulating members. The electrodes are mounted on the insulating members and are located at upper and lower sides of the preformed blank, and portions of the electrodes located at either the lower side or the upper side of the preformed blank are connected with the power supply. In a power-on state, the power supply, the electrodes, and the preformed blank together form an electrically conductive loop, and a current flows through the preformed blank and produces joule heat which heats the preformed blank.
According to the above technical solution, the heating device is a laser heating device which comprises a laser head, and a laser that is connected with the laser head. The laser head is used to produce a high-energy laser beam to heat the preformed blank.
According to the above technical solution, the heating device is an induction heating device which comprises an induction coil, and an iron core disposed in the induction coil. In a power-on state, the induction coil and the iron core produce an alternating magnetic field, and the preformed blank generates an induced current in presence of the alternating magnetic field and is thus heated.
According to the above technical solution, the die device comprises a stamping-shaving punching progressive die, and provided is one press which is called press A. The stamping-shaving punching progressive die is mounted on the press A.
According to the above technical solution, the die device comprises a hot forming die and a shaving punching die, and provided are two presses which are press B and press C, respectively. Both the hot forming die and the heating device are mounted on the press B, and the shaving punching die is mounted on the press C. The press B and the press C are provided therebetween with a robot.
According to the above technical solution, the quenching device includes a quenching chamber, and a movable clamping member and a spraying member that are provided in the quenching chamber. The movable clamping member is mounted slidably at top of the quenching chamber and is used to transfer the hot stamped part grasped by the conveying robot to the discharging robot, and the spraying member is used to spray a quenching medium onto the hot stamped part in motion.
According to the above technical solution, the quenching device includes a quenching bath which is provided therein with a quenching medium.
According to the above technical solution, the preformed blank is made of a material selected from a group including, but not limited to, ultra-high-strength sheet steel, high-strength sheet steel, sheet metal of aluminum alloy, or sheet metal of titanium alloy.
The present disclosure further provides a multi-station continuous hot stamping method, which comprises:
a heating step S1, during which a feeding robot grasps a preformed blank from a feeding platform and places the preformed blank on a die device, and then the preformed blank is immediately heated wholly or partially by a heating device to a stamping temperature to produce a hot blank;
a stamping and pressure holding step S2, during which the die device stamps the hot blank and holds the hot blank at a certain pressure for 2 s to 5 s, so as to obtain a hot stamped part;
a shaving and punching step S3, during which the die device shaves and punches the hot stamped part;
a quenching step S4, during which a conveying robot grasps the hot stamped part and transfers the hot stamped part to a quenching device in which the hot stamped part is quenched; and
a cooling step S5, during which a discharging robot transfers a quenched hot stamped part to a conveyor belt and the hot stamped part is then cooled in air.
The present disclosure achieves the following beneficial effects. By providing the heating device on the press, the preformed blank can be rapidly heated and then stamped at a same place, which achieves a high heating efficiency and speed. In this way, a transferring process before stamping of the hot blank and a transferring device are avoided. Besides, heat loss and air oxidation are reduced. This greatly improves energy utilization and heating efficiency, and ensures surface quality of the hot blank. In addition, in the present disclosure, punching and shaving of the hot stamped part are performed prior to pressure holding and quenching when the strength and rigidity of punching and shaving areas are low, by way of which punching and shaving forces can be reduced and service life of the punching shaving die can be prolonged, and at the same time, a laser cutting process is not used and the production cost is decreased. Furthermore, because a metal material can bear a larger shear force at high temperature due to its improved plasticity, punching and shaving at high temperature can ensure quality of the punching and shaving, and obtain desired cutting edges. Geometrical shapes and dimensional accuracy of hot stamped part can thus be ensured. While decreasing the production cost, the present disclosure also greatly shortens the production time, thereby improving production efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will be described in a more detailed way below in conjunction with the accompanying drawings and embodiments.

FIG. 1 schematically shows structure of a first embodiment of the present disclosure.

FIG. 2 schematically shows structure of a second embodiment of the present disclosure.

FIG. 3 schematically shows structure of a third embodiment of the present disclosure.

FIG. 4 schematically shows structure of a fourth embodiment of the present disclosure.

FIG. 5 schematically shows a flow chart of an embodiment of the present disclosure.

FIG. 6 schematically shows structure of an electrical heating device of an embodiment of the present disclosure.

FIG. 7 schematically shows structure of a laser heating device of an embodiment of the present disclosure.

FIG. 8 schematically shows structure of an induction heating device of an embodiment of the present disclosure.

LIST OF REFERENCES

1—preformed blank; 2—feeding platform; 3—feeding robot; 4—press A; 5—conveying robot; 6—quenching chamber; 61—movable clamping member; 62—spraying member; 7—discharging robot; 8—conveyor belt; 9—press B; 10—robot; 11—press C; 12—quenching bath; 13—bracket; 14—forming concave die; 15—forming convex die; 16—shaving concave die; 17—punching convex die; 18—power supply; 19—electrode; 20—insulating member; 21—laser beam; 22—laser head; 23—laser; 24—induction coil; 25—iron core.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present disclosure will be further explained below in connection with the accompanying drawings and embodiments so that the objectives, the technical solutions, and advantages of the present disclosure can be clearer. It should be appreciated that the specific embodiments described below are intended only for explaining, rather than, limiting the present disclosure.
As shown in FIGS. 1 to 5, a multi-station continuous hot stamping production line comprises a feeding platform 2, a feeding robot 3, a pressing unit, a conveying robot 5, a quenching device, a discharging robot 7, and a conveyor belt 8. The feeding platform 2 is used for placing a preformed blank 1 after blanking. The feeding robot 3 is used for transferring the preformed blank 1 to the pressing unit. The pressing unit includes a heating device, a die device, and at least a press used for mounting the die device. The heating device is used for wholly or partially heating the preformed blank to produce a hot blank. The die device is used for stamping the hot blank, holding the hot blank at a certain pressure, and shaving and punching the hot blank, so as to produce a hot stamped part. The conveying robot 5 is used for conveying the stamped part to the quenching device. The quenching device is used to quenching the hot stamped part. The discharging robot 7 is used for transfer a quenched workpiece to the conveyor belt 8.
In a preferred embodiment of the present disclosure, as shown in FIG. 6, the heating device is an electrical heating device which comprises a power supply 18, electrodes 19, and insulating members 20. The electrodes 19 are mounted on the insulating members 20 and are located at upper and lower sides of the preformed blank. Portions of the electrodes 19 located at either the lower side or the upper side of the preformed blank 1 are connected with the power supply 18. In a power-on state, the power supply 18, the electrodes 19, and the preformed blank together form an electrically conductive loop. In this way, a current flows through the preformed blank and produces joule heat which heats the preformed blank.
In a preferred embodiment of the present disclosure, as shown in FIG. 7, the heating device is a laser heating device which comprises a laser head 22, and a laser 23 that is connected with the laser head 22. The laser head 22 is configured to produce a high-energy laser beam 21 which heats the preformed blank.
In a preferred embodiment of the present disclosure, as shown in FIG. 8, the heating device is an induction heating device which comprises an induction coil 24, and an iron core 25 that is provided in the induction coil 24. In a power-on state, the induction coil 24 and the iron core 25 produce an alternating magnetic field, and the preformed blank generates an induced current in presence of the alternating magnetic field. The preformed blank is thus heated.
In a preferred embodiment of the present disclosure, as shown in FIGS. 1, 3, and 5, the die device comprises a stamping-shaving punching progressive die, and provided is one press which is called press A4. The stamping-shaving punching progressive die is mounted on the press A4 on which the heating device is also mounted.
In a preferred embodiment of the present disclosure, as shown in FIGS. 2, 4, and 5, the die device comprises a hot forming die and a shaving punching die, and provided are two presses which are press B9 and press C11, respectively. Both the hot forming die and the heating device are mounted on the press B9, and the shaving punching die is mounted on the press C11. The press B9 and the press C11 are provided therebetween with a robot 10.
In a preferred embodiment of the present disclosure, as shown in FIGS. 1 and 2, the quenching device includes a quenching chamber 6, and a movable clamping member 61 and a spraying member 62 that are provided in the quenching chamber 6. The movable clamping member 61 is mounted slidably at top of the quenching chamber 6 and is used to transfer the hot stamped part grasped by the conveying robot 5 to the discharging robot 7. The spraying member 62 is used to spray a quenching medium to the hot stamped part in motion.
In a preferred embodiment of the present disclosure, as shown in FIGS. 3 and 4, the quenching device includes a quenching bath 12 which is provided therein with a quenching medium.
In a preferred embodiment of the present disclosure, the preformed blank is made of a material selected from a group including, but not limited to, ultra-high-strength sheet steel, high-strength sheet steel, sheet metal of aluminum alloy, or sheet metal of titanium alloy.
Accordingly, the production line can continuously achieve rapid heating, stamping, pressure holding, shaving, punching, and quenching. Heating efficiency is improved, and a transferring process before stamping the hot blank is avoided. For a hot stamped part made of sheet steel, punching and shaving thereof at high temperature avoids an increase of cutting difficulty caused by formation of martensites at normal temperatures, and punching and shaving forces are decreased and desired cutting edges can be obtained.
The present disclosure further provides a multi-station continuous hot stamping method, which comprises the following steps.
Step S1: Heating
A feeding robot grasps a preformed blank from a feeding platform and places the preformed blank on a die device. Then, the preformed blank is immediately heated wholly or partially by a heating device to a stamping temperature to produce a hot blank.
Step S2: Stamping and Pressure Holding
The die device is used to stamp the hot blank and hold the hot blank at a certain pressure for 2 s to 5 s, so as to obtain a hot stamped part.
Step S3: Shaving and Punching
The die device is used to shave and punch the hot stamped part.
Step S4: Quenching
A conveying robot grasps the hot stamped part and transfers it to a quenching device in which the hot stamped part is quenched.
Step S5: Cooling
A discharging robot transfers a quenched hot stamped part to a conveyor belt where the hot stamped part is cooled in air.
Two solutions are provided for the die device. The number of presses used matches the types of the die device. The quenching device is used for quenching the hot stamped part through two approaches, spraying and soaking. The present disclosure therefore can at least provide four types of production lines.
As shown in FIG. 1, a multi-station continuous hot stamping production line I sequentially comprises a feeding platform 2, a feeding robot 3, a press A4, a conveying robot 5, a quenching chamber 6, a discharging robot 7, and a conveyor belt 8. A heating device and a stamping-shaving punching progress die are mounted on the press A4.
As shown in FIG. 2, a multi-station continuous hot stamping production line II sequentially comprises a feeding platform 2, a feeding robot 3, a press B9, a robot 10, a press C11, a conveying robot 5, a quenching chamber 6, a discharging robot 7, and a conveyor belt 8. A heating device and a hot forming die are mounted on the press B9. A shaving punching die is mounted on the press C11.
As shown in FIG. 3, a multi-station continuous hot stamping production line III sequentially comprises a feeding platform 2, a feeding robot 3, a press A4, a conveying robot 5, a quenching bath 12, a discharging robot 7, and a conveyor belt 8. A heating device and a stamping-shaving punching progress die are mounted on the press A4.
As shown in FIG. 4, a multi-station continuous hot stamping production line IV sequentially comprises a feeding platform 2, a feeding robot 3, a press B9, a robot 10, a press C11, a conveying robot 5, a quenching bath 12, a discharging robot 7, and a conveyor belt 8. A heating device and a hot forming die are mounted on the press B9. A shaving punching die is mounted on the press C11.
In the present disclosure, the heating device is used to heat the performed blank wholly or partially. Heating methods may include electrical heating, induction heating, laser heating, or others. The stamping-shaving punching progressive die is used for stamping the preformed blank, holding the hot stamped part at a certain pressure, and shaving and punching the hot stamped part. The hot forming die is used for stamping the preformed blank, and holding the hot stamped part at a certain pressure. The shaving punching die is used for shaving and punching the hot stamped part. The quenching chamber is used for spray quenching, and is provided therein with a movable clamping member and a spraying member. The movable clamping member is used for clamping and moving the hot stamped part, and the spraying member is used for spraying a quenching medium onto a moving hot stamped part. The quenching bath is used for soak quenching, and is provided therein with a quenching medium into which a shaved and punched hot stamped part is soaked to complete the quenching process. All the robots in the present disclosure are multi-link manipulators or linear robots, which are used for transferring, feeding, or discharging of preformed blanks or hot stamped parts.
In the present disclosure, as shown in FIG. 5, the die device includes a bracket 13, a forming concave die 14, and a forming convex die 15 that matches the forming concave die 14, a shaving concave die 16, and a punching convex die 17.
As shown in FIG. 5, the multi-station continuous hot stamping method specifically comprises the following steps.
Step I: Heating
The feeding robot 3 grasps the preformed blank from the feeding platform and places the preformed blank on the bracket 13. Then, the preformed blank is immediately heated wholly or partially by the heating device to a stamping temperature to produce a hot blank.
Step II: Stamping and Pressure Holding
The forming concave die 14 descends to join the forming convex die 15, so as to stamp the hot blank on the bracket 13 and hold the hot blank at a certain pressure for 2 s to 5 s, thus obtaining a hot stamped part.
Step III: Shaving and Punching
The shaving concave die 16 and the punching convex die 17 descend so as to shave and punch the hot stamped part.
Step IV: Quenching
The conveying robot grasps a shaved and punched hot stamped part and placed the hot stamped part onto the movable clamping member 61 in the quenching chamber. The movable clamping member 61 clamps the hot stamped part tightly and moves along a guiding rail. The spraying member 62 quenches the hot stamped part in motion by spraying a quenching medium. Alternatively, the conveying robot grasps the shaved and punched hot stamped part and soaked the hot stamped part in the quenching bath 12 for quenching.
Step VI: Cooling
The discharging robot 7 transfers the quenched hot stamped part to the conveyor belt 8 for a subsequent process, and meanwhile the hot stamped part is cooled in air.
The above steps altogether form an entire process. Continuous production can be achieved by repeating these steps.
The present disclosure abandons processes in traditional hot stamping technologies in which the three operations of sheet material heating, forming and quenching, and shaving and punching are separated, and achieves multi-station continuous production of heating-forming-punching-quenching of hot stamped parts.
It should be appreciated that one skilled in the art can make improvements on or variations to the present disclosure according to the above description, but all such improvements or variations shall fall within the protection scopes of the claims of the present disclosure.

Claims

What is claimed is:

1. A multi-station continuous hot stamping production line, characterized in that the production line sequentially comprises a feeding platform, a feeding robot, a pressing unit, a conveying robot, a quenching device, a discharging robot, and a conveyor belt, wherein:

the feeding platform is used for placing a preformed blank,

the feeding robot is used for transferring the preformed blank to the pressing unit,

the pressing unit includes a heating device, a die device, and at least one press used for mounting the die device, wherein the heating device is used for wholly or partially heating the preformed blank to produce a hot blank, and the die device is used for stamping the hot blank, holding the hot blank at a certain pressure, and shaving and punching the hot blank, so as to produce a hot stamped part,

the conveying robot is used for conveying the hot stamped part to the quenching device,

the quenching device is used for quenching the hot stamped part, and

the discharging robot is used for transferring a quenched workpiece to the conveyor belt.

2. The production line according to claim 1, characterized in that the heating device is an electrical heating device which comprises a power supply, electrodes, and insulating members, wherein:

the electrodes are mounted on the insulating members and are located at upper and lower sides of the preformed blank, and portions of the electrodes located at either the lower side or the upper side of the preformed blank are connected with the power supply, wherein in a power-on state, the power supply, the electrodes, and the preformed blank together form an electrically conductive loop, and a current flows through the preformed blank and produces joule heat which heats the preformed blank.

3. The production line according to claim 1, characterized in that the heating device is a laser heating device which comprises a laser head, and a laser that is connected with the laser head, wherein:

the laser head is used to produce a high-energy laser beam to heat the preformed blank.

4. The production line according to claim 1, characterized in that the heating device is an induction heating device which comprises an induction coil, and an iron core disposed in the induction coil, wherein:

in a power-on state, the induction coil and the iron core produce an alternating magnetic field, and the preformed blank generates an induced current in presence of the alternating magnetic field and is thus heated.

5. The production line according to claim 1, characterized in that the die device comprises a stamping-shaving punching progressive die, and provided is one press which is called press A, wherein:

the stamping-shaving punching progressive die is mounted on the press A.

6. The production line according to claim 1, characterized in that the die device comprises a hot forming die and a shaving punching die, and provided are two presses which are press B and press C, respectively, wherein:

both the hot forming die and the heating device are mounted on the press B, and the shaving punching die is mounted on the press C, and

the press B and the press C are provided therebetween with a robot.

7. The production line according to claim 1, characterized in that the quenching device includes a quenching chamber, and a movable clamping member and a spraying member that are provided in the quenching chamber, wherein:

the movable clamping member is mounted slidably at top of the quenching chamber and is used to transfer the hot stamped part grasped by the conveying robot to the discharging robot, and the spraying member is used to spray a quenching medium onto the hot stamped part in motion.

8. The production line according to claim 1, characterized in that the quenching device includes a quenching bath which is provided therein with a quenching medium.

9. The production line according to claim 1, characterized in that the preformed blank is made of a material selected from a group including, but not limited to, ultra-high-strength sheet steel, high-strength sheet steel, sheet metal of aluminum alloy, or sheet metal of titanium alloy.

10. A multi-station continuous hot stamping method, characterized in that the method comprises:

a heating step S1, during which a feeding robot grasps a preformed blank from a feeding platform and places the preformed blank on a die device, and then the preformed blank is immediately heated wholly or partially by a heating device to a stamping temperature to produce a hot blank;

a stamping and pressure holding step S2, during which the die device stamps the hot blank and holds the hot blank at a certain pressure for 2 s to 5 s, so as to obtain a hot stamped part;

a shaving and punching step S3, during which the die device shaves and punches the hot stamped part;

a quenching step S4, during which a conveying robot grasps the hot stamped part and transfers the hot stamped part to a quenching device in which the hot stamped part is quenched; and

a cooling step S5, during which a discharging robot transfers a quenched hot stamped part to a conveyor belt and the hot stamped part is then cooled in air.