CN117324479A - Ultralow-temperature two-point progressive forming and in-mold creep aging treatment device and treatment method - Google Patents

Abstract

The invention discloses an ultralow-temperature two-point incremental forming and in-mold creep aging treatment device and a treatment method, and designs a mixing process device capable of realizing the integration of ultralow-temperature forming and creep aging treatment based on the strong/plastic dual-increasing effect of ultralow-temperature forming on an aluminum alloy plate and the acceleration effect of time-effect strengthening process. Aiming at the technical characteristics of two-point progressive forming, the device ensures that the forming surface has proper lubrication conditions while realizing ultralow-temperature environment forming, realizes controllable loading and heating on the forming plate by using a supporting die, realizes creep aging treatment on ultralow Wen Zhijian, obviously shortens aging time, and improves forming precision by creep effect correction. The device solves the problems of poor formability, long post-treatment time, low forming precision and the like of the plate in the traditional forming process. Realizing the high-efficiency and high-precision forming of the high-strength aluminum alloy complex curved surface thin-wall structural member.

Description

Ultra-low temperature two-point progressive forming and in-mold creep aging treatment device and treatment method

Technical field

The invention relates to an ultra-low temperature two-point progressive forming and in-mold creep aging treatment device for efficient and high-precision manufacturing of high-strength and complex curved surface aluminum alloy thin-walled components, and belongs to the technical field of multi-process mixed processing.

Background technique

Incremental sheet forming (ISF) is a flexible sheet forming process with high flexibility and formability. With the continuous development of ISF basic research, two-point progressive forming (TPIF) has emerged. As a variant of ISF, TPIF enhances the forming stability by using an additional full mold or partial mold on the other side of the sheet, further improving the Improved forming performance and accuracy. At present, there are two main limitations to the development of ISF: On the one hand, difficult-to-deform materials such as aluminum alloys have poor plasticity at room temperature, which exceeds the forming limit when processing complex-shaped components. Although the traditional heat-assisted forming process improves the plasticity of the sheet, the strength loss caused by the dynamic recovery of the material at high temperatures is still a big challenge. Additional post-processing processes such as aging strengthening after high-temperature forming seriously reduce production efficiency. On the other hand, the geometric accuracy of incrementally formed parts is poor, and plate springback is the cause of geometric errors in most areas of the formed parts.

In recent years, in order to overcome the shortcomings of traditional hot forming processes, ultra-low temperature forming processes have emerged. As a face-centered cubic structure material, aluminum alloy shows a double-increase effect when deformed at ultra-low temperatures, that is, the strength and plasticity of the material increase at the same time. This provides the feasibility of using low-temperature environments to produce aluminum alloy parts with high strength and complex structures. With the continuous development of ultra-low temperature technology, new ultra-low temperature forming processes have been continuously proposed, such as ultra-low temperature stamping, ultra-low temperature rolling, ultra-low temperature pipe hydraulic bulging, etc. The ultra-low temperature incremental forming process that has been proposed so far is only aimed at single point incremental forming (SPIF). For complex curved thin-walled configurations, the forming accuracy of the ultra-low temperature single-point progressive forming method is difficult to meet the rapid forming requirements of high-precision parts. The warpage and springback of the sheet during the forming process are important reasons for the reduction in forming accuracy. Two-point incremental forming (TPIF) effectively suppresses springback phenomena such as the "pillow effect" of the plate by supporting the mold, and greatly improves springback accuracy. At present, the combination of ultra-low temperature and two-point incremental forming process faces challenges. Research shows that the cooling method of immersing the plate in a liquid nitrogen environment will cause serious deterioration of the surface quality and cannot further improve the forming performance of the plate.

The ultra-low temperature forming process can not only improve the sheet forming performance by utilizing the strength/plastic dual enhancement effect, but also significantly affect the age hardening of the material. Existing research data shows that ultra-low temperature forming can accelerate the aging dynamics of materials. Compared with room temperature parts, ultra-low temperature parts achieve a short-term age hardening effect. In the subsequent aging treatment process, the age hardening speed of ultra-low temperature parts is significantly improved. For example, the Shanghai Jiao Tong University research team has proposed a pre-hardened low-temperature forming process for aluminum alloy plates, using cryogenic forming to improve the post-processing efficiency of parts and achieve efficient production of complex thin-walled components of high-strength aluminum alloys. Creep aging forming (CAF) is an advanced forming technology that has the advantages of short lead time and low cost for formed parts. CAF uses creep deformation caused by stress at high temperatures to deform the plate in its elastic zone, thereby avoiding the introduction of excessive residual stress. This process can effectively suppress springback and improve forming accuracy. At present, due to the limitations of the forming equipment, there is a discontinuity problem between the ultra-low temperature forming process and aging post-processing. After the sheet is formed, the parts need to be transferred to the corresponding post-processing equipment to continue the next process stage. Long-term transfer and transportation reduce the cost Production efficiency does not affect the performance of parts. Therefore, how to continuously realize ultra-low temperature forming and aging strengthening treatment under the same equipment is also an important issue that needs to be solved urgently.

Contents of the invention

In order to realize the integrated process of ultra-low temperature two-point progressive forming, creep aging strengthening and orthopedic treatment of high-strength aluminum alloy plates, the present invention provides an ultra-low temperature two-point progressive forming and in-mold creep aging treatment device, which mainly has the following functions: 1. Realize two-point progressive forming of the plate in an ultra-low temperature environment, and use the deep cooling strength/plastic double enhancement effect to improve the forming performance of the plate; 2. Use the support mold to heat the ultra-low temperature formed parts to achieve rapid aging strengthening of the parts and improve the manufacturing process in a short time. The strength of the parts can meet actual production needs; 3. Creep aging treatment can be achieved in the mold, and the high-temperature creep effect can be used to further deform the formed parts and improve the forming accuracy of the parts.

In order to realize the above functions, the present invention adopts the following technical solutions:

In the first aspect, the present invention proposes a device that can realize ultra-low temperature two-point progressive forming, creep aging strengthening, and orthopedic treatment of high-strength aluminum alloy plates. It includes a two-point progressive forming module, a creep aging treatment module, and a cooling medium circulation supply. material module and control system; the two-point progressive forming module includes a forming tool, an upper clamping mold, a lower clamping mold and a support mold; the creep aging treatment module includes a driving device, a heating element, a temperature measurement device, a force Sensor; the cooling medium circulation feeding module includes a liquid nitrogen storage cavity; the top of the liquid nitrogen storage cavity is open, the target plate is set on the top, and the upper and lower clamping molds are used to clamp the edge of the target plate and along the The guide pillar installed vertically in the storage cavity slides up and down. Below the plate is a support mold, which is also installed in the liquid nitrogen storage cavity; a liquid nitrogen overflow hole is provided on the liquid nitrogen storage cavity; and the liquid nitrogen storage cavity is connected to the liquid nitrogen storage cavity. The nitrogen container and the liquid nitrogen pump are connected; the temperature measurement device monitors the target plate temperature in real time; the heating element and force sensor are set on the support mold, and the support mold is driven by the driving device; the control system controls the creep aging treatment module and cooling medium circulation feeding module.

As a further technical solution, a three-dimensional force measuring sensor is also included. The three-dimensional force measuring sensor is arranged below the entire liquid nitrogen storage chamber to monitor the forming forces in the X, Y, and Z directions of the target sheet in real time during the forming process.

As a further technical solution, the driving device is installed at the bottom of the support mold to drive the support mold to move in a direction closer to the target plate or away from the target plate.

As a further technical solution, the plurality of heating elements are distributed inside the supporting mold for heating the target plate.

As a further technical solution, the temperature measurement device mainly consists of a multi-channel thermometer and a thermocouple. The temperature measurement end of the thermocouple is connected to the edge of the target plate to monitor the temperature of the target plate in real time.

As a further technical solution, the force sensor is arranged in the support mold, and the force-bearing surface contacts the target plate, and is used to monitor the pressure of the support mold on the target plate.

As a further technical solution, a liquid nitrogen inlet and a liquid nitrogen outlet are provided on both sides of the bottom of the liquid nitrogen storage chamber. An inlet electromagnetic switch valve is installed at the liquid nitrogen inlet, and an outlet electromagnetic switch valve is installed at the liquid nitrogen outlet.

As a further technical solution, liquid nitrogen is ejected from the liquid nitrogen container, and returns to the liquid nitrogen container through the inlet electromagnetic switch valve, hydraulic sensor, liquid nitrogen storage chamber, outlet electromagnetic switch valve, and liquid nitrogen pump in order to achieve circulation.

As a further technical solution, the side wall of the liquid nitrogen storage chamber is provided with multiple liquid nitrogen overflow holes arranged vertically in sequence and connected to the liquid nitrogen transportation pipeline.

In the second aspect, the present invention is based on the above-mentioned ultra-low temperature two-point progressive forming and in-mold creep aging treatment device, and also proposes a method for processing the target plate using the above-mentioned ultra-low temperature two-point progressive forming and in-mold creep aging treatment device. as follows:

Place the target plate on the supporting mold and fix it through the upper and lower clamping mold;

Weld/glue the thermocouple wire in the temperature measuring device around the target plate, monitor the temperature changes of the plate in real time through a multi-channel thermometer, and feed the temperature signal back to the control system;

Liquid nitrogen flows into the liquid nitrogen storage chamber, the device enters the cooling stage, and the control system monitors the target plate temperature and transportation pipeline pressure in real time;

When the pressure in the liquid nitrogen storage chamber is too high, the liquid nitrogen storage chamber will leak;

When the temperature of the target plate drops to the set temperature and remains stable, the device enters the forming stage. The forming tool starts to form the target plate according to the predetermined trajectory. The plate slowly moves downward under the clamping of the mold, and the overflowing liquid nitrogen overflows through the liquid nitrogen. The hole is discharged to the liquid nitrogen transport pipeline and enters the circulation;

After the first stage of forming, the liquid nitrogen in the liquid nitrogen storage chamber is emptied, the heating element is started, and the device enters the heating stage.

When the temperature measurement device detects that the temperature of the target plate has stabilized to the set temperature, the forming tool contacts the upper clamping mold and remains stationary. The motor drives the screw to cause the support mold to exert upward pressure on the plate. The force sensor feeds back the plate pressure in real time, and the control system controls the The motor keeps the pressure on the plate constant, and the device enters the creep aging strengthening treatment stage for the set time. At the same time, the formed parts are further deformed through the creep effect;

After the creep aging treatment is completed, the heating element is switched off and the forming tool is moved to the non-working position.

The beneficial effects of the present invention are as follows:

1. The present invention designs a processing device that can realize ultra-low temperature two-point progressive forming and aging heat treatment process integration. The device uses liquid nitrogen circulation cooling to achieve two-point progressive forming of the plate at ultra-low temperature, and realizes the processing of the plate by modifying the support mold. With the heating function, this structural design eliminates the need for transfer of ultra-low-temperature formed parts, and allows direct aging strengthening in the forming mold, greatly improving processing efficiency. At the same time, the short-term age hardening effect of ultra-low temperature forming on the parts is used to reduce the manufacturing cost. The aging strengthening time required for the parts strength to meet production requirements.

2. The ultra-low temperature two-point progressive forming and aging treatment integrated device designed by the present invention can realize in-mold creep aging forming of ultra-low temperature formed parts. The device drives the supporting mold through a designed driving device to cause the target plate to creep, and utilizes The creep effect deforms the workpiece while strengthening through aging. This device combines two processes, ultra-low temperature forming and creep aging forming, to improve the forming accuracy.

3. In view of the unique processing characteristics of the two-point progressive forming process, the present invention proposes a device that can realize two-point progressive forming at ultra-low temperature. By designing a dedicated liquid nitrogen storage chamber structure, the forming plane can be raised and lowered in the chamber. The device can continue processing in ultra-low temperature environments (-170°C). The overflow structure designed by the device ensures that the forming surface is dry and lubricated, making use of ultra-low temperature conditions. The dual strength/plastic effect of aluminum alloy significantly improves the formability of the plate.

Description of drawings

The description and drawings that constitute a part of the present invention are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

Figure 1 is a design diagram of the overall device of the present invention;

Figure 2 is the feedback and control roadmap;

Figure 3 is the process roadmap of 7050 ultra-low temperature two-point progressive forming and in-mold creep aging;

In the figure: The distance or size between each part is exaggerated to show the position of each part. The schematic diagram is for illustrative purposes only. 1 electric liquid nitrogen pump, 2 outlet electromagnetic switch valve, 3 liquid nitrogen overflow hole, 4 temperature measuring device, 5 target plate, 6 heating element, 7 force sensor, 8 forming tool, 9 upper clamping mold, 10 guide pillar, 11 sliding pair, 12 control system, 13 lower clamping mold, 14 support mold, 15 hydraulic sensor, 16 imported electromagnetic switch valve, 17 screw, 18 motor, 19 liquid nitrogen pipeline, 20 self-pressurized liquid nitrogen tank, 21 Liquid nitrogen storage chamber, 22 three-dimensional load cells.

Detailed ways

It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings commonly understood by one of ordinary skill in the art to which this invention belongs.

It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, the singular forms are intended to include the plural forms as well, unless the invention clearly dictates otherwise. Furthermore, it will be understood that when the terms "comprises" and/or "includes" are used in this specification, they Indicate the existence of features, steps, operations, devices, components and/or combinations thereof;

As introduced in the background art, there are deficiencies in the prior art. In order to solve the above technical problems, the present invention proposes an ultra-low temperature two-point progressive forming and in-mold creep aging treatment device. This device combines ultra-low temperature two-point progressive forming with creep aging forming, uses ultra-low temperature strength/plastic double enhancement effect to improve the forming performance of aluminum alloy plates, and adds creep aging treatment process to achieve short-term aging strengthening and improve the performance of formed parts. Forming accuracy. Through single-side contact cooling, the device provides a dry lubrication environment for the ultra-low temperature two-point progressive forming process. The motor drives the screw to move the support mold to obtain constant load conditions. The heating unit on the support mold can maintain the plate through contact heating. Constant aging heat treatment temperature finally achieves short-term creep aging forming of ultra-low temperature parts.

The invention will be described in detail below with reference to Figures 1 and 2. The specific structure is as follows: The invention provides an ultra-low temperature two-point progressive forming and in-mold creep aging treatment device, which mainly includes a two-point progressive forming module, a creep aging treatment device Module, cooling medium circulation feeding module and control system;

The two-point progressive forming module includes the forming tool 8, the upper clamping mold 9, the lower clamping mold 13, the guide pillar 10, the target plate 5, the sliding pair 11, the support mold 14, and the three-dimensional load cell 22, of which the upper clamping mold 9 The cross-section is L-shaped, and the protruding part serves as a protective wall to surround the forming area to prevent liquid nitrogen from overflowing into the forming area and thereby deteriorating the lubrication environment. A sliding guide rail is provided on the inner wall of the liquid nitrogen storage cavity 21 and forms a sliding pair 11 with the outside of the clamping mold. The target plate 5 The four guide pillars 10 can move up and down under the clamping of the upper clamping mold 9 and the lower clamping mold 13. The support mold 14 is placed directly under the plate in the center of the device. The three-dimensional load sensor 22 is installed in the entire liquid nitrogen storage cavity 21. Below, the forming forces in the X, Y, and Z directions of the target plate 5 during the forming process are monitored in real time.

The creep aging treatment module includes a motor 18, a screw 17, a heating element 6, a temperature measurement device 4, and a force sensor 7. The motor 18 is connected to the screw 17 to drive the screw 17 to rotate, and the other end of the screw 17 is connected to the support mold 14 , the motor 18 can control the support mold 14 to move up and down through the screw 17. Multiple heating elements 6 are distributed inside the support mold 14 for heating. The temperature measurement device 4 is mainly composed of a multi-channel thermometer and a thermocouple. The thermocouple measures The warm end is connected to the edge of the target plate 5 to monitor the temperature of the target plate in real time. The force sensor 7 is arranged in the support mold 14 and the force-bearing surface contacts the target plate 5 for monitoring the pressure of the support mold 14 on the target plate 5 .

The cooling medium circulation feeding module includes a liquid nitrogen storage chamber 21, a liquid nitrogen transportation pipeline 19, a self-pressurizing liquid nitrogen container 20, a hydraulic sensor 15, an outlet electromagnetic switch valve 2, an inlet electromagnetic switch valve 16, and an electric liquid nitrogen pump 1. The top of the liquid nitrogen storage chamber 21 is open. The target plate is directly placed on the top of the liquid nitrogen storage chamber 21 and is in contact with the liquid nitrogen. There are liquid nitrogen inlets and liquid nitrogen outlets on both sides of the bottom of the liquid nitrogen storage chamber 21 connected to the liquid nitrogen transportation pipeline. 19. The liquid nitrogen inlet is provided with an inlet electromagnetic switch valve 16, and the liquid nitrogen outlet is provided with an outlet electromagnetic switch valve 2. The liquid nitrogen storage chamber 21 is provided with four guide posts 10, and a threaded hole is provided in the center of the bottom to connect the screw 17. The liquid nitrogen storage The side wall of the cavity 21 is provided with a plurality of liquid nitrogen overflow holes 3 arranged vertically in sequence and connected to the liquid nitrogen transport pipeline 19. The liquid nitrogen is ejected from the self-pressurized liquid nitrogen container 20 and passes through the inlet electromagnetic switch valve 16, hydraulic The sensor 15, liquid nitrogen storage chamber 21, outlet electromagnetic switch valve 2, and electric liquid nitrogen pump 1 return to the container to achieve circulation.

The control system 12 is connected to the inlet electromagnetic switch valve 16, the electric liquid nitrogen pump 1, the outlet electromagnetic switch valve 2, the hydraulic sensor 15, the motor 18, the heating element 6, the temperature measuring device 4, and the force sensor 7. Among them, the temperature measuring device 4 and the hydraulic sensor 15. The force sensor 7 feeds back the temperature signal of the plate, the pressure signal in the cavity and pipeline, and the pressure signal of the mold 14 supported by the plate to the control system 12. The control system 12 controls the connection inlet electromagnetic switch valve 16 and the electric valve according to the feedback information. Liquid nitrogen pump 1, outlet electromagnetic switch valve 2, heating element 6, and motor 18 practice operations such as cooling, heating, temperature control, and creep deformation of the target plate.

In this embodiment, the bottom of the plate and the outside of the clamping mold are surrounded by a liquid nitrogen storage cavity. The upper and lower clamping molds and the liquid nitrogen storage cavity are connected through guide rails to form a sliding pair. A closed space is formed under the target plate to store liquid nitrogen and thereby cool the target. Plate. The self-pressurizing liquid nitrogen container can continuously provide liquid nitrogen to the device, and transport liquid nitrogen into the liquid nitrogen chamber through the liquid nitrogen transportation pipeline. A liquid nitrogen inlet and a liquid nitrogen outlet are provided at both ends of the bottom of the liquid nitrogen storage chamber. The liquid nitrogen is self-increasing. The pressurized liquid nitrogen container is sprayed out and enters the cavity through the solenoid valve. After it is full, it is discharged through the liquid nitrogen outlet and flows back to the self-pressurized liquid nitrogen container to realize liquid nitrogen circulation feeding.

Furthermore, the temperature measurement device monitors the temperature of the target plate in real time through a low-temperature thermocouple. When the temperature drops to ultra-low temperature (about -170°C), the forming tool runs based on the shape of the bottom support mold, and at the same time the target plate moves downward along the guide pillar to achieve Two-point progressive forming at ultra-low temperature.

Furthermore, the upper clamping mold is designed with a protective wall to surround the processing area to prevent overflowing liquid nitrogen from flowing into the forming area, thereby affecting the surface quality of the formed parts.

There are liquid nitrogen overflow holes arranged vertically on the side wall of the liquid nitrogen storage chamber and connected to the liquid nitrogen transportation pipeline. As the formed plate moves downward, the liquid nitrogen overflow hole discharges the overflowing liquid nitrogen into the circulation pipeline. .

An electromagnetic switch valve and a pressure sensor are installed in the pipeline near the liquid nitrogen inlet and outlet. During the cooling stage of the device, the solenoid valve at the inlet is opened and the solenoid valve at the outlet is closed, allowing liquid nitrogen to quickly fill the device and cool it down. The hydraulic sensor detects the pressure in the circulation pipeline and the liquid nitrogen storage chamber. When the liquid nitrogen fills the device and the pressure in the chamber increases, the solenoid valve at the inlet is closed and the forming stage is entered.

An electric liquid nitrogen pump is installed in the pipeline at the liquid nitrogen outlet, which can increase the discharge flow and quickly empty the liquid nitrogen in the device. During the forming process, the three-dimensional force sensor displays and records the forming change process in real time.

After the first pass of cryogenic two-point progressive forming is completed, the device can directly start the in-mold creep aging treatment. The electromagnetic switch valve at the liquid nitrogen inlet is closed, and the electric liquid nitrogen pump is turned on to empty the liquid nitrogen in the liquid nitrogen storage chamber. Then the heating unit in the support mold is started, contact heating is performed on the target plate through heat conduction in the mold, and the temperature of the target plate is monitored in real time through the temperature measurement device. When the temperature reaches the target aging temperature, the motor is controlled to drive the screw to slowly move the support mold upward. The force sensor on the support mold is used to monitor the force of the plate in real time to keep the load on the plate constant and achieve creep aging treatment in the mold.

Utilizing the enhanced effect of ultra-low temperature on the aging power of aluminum alloys, the device can greatly shorten the aging strengthening time. At the same time, the creep aging strengthening treatment can realize the correction of the first-pass formed parts and improve the forming accuracy of the parts.

Based on the above device, this embodiment also provides a specific processing method, which is as follows:

Place the target plate on the supporting mold and fix it through the upper and lower clamping mold;

Weld/glue the thermocouple wire in the temperature measuring device around the target plate, monitor the temperature changes of the plate in real time through a multi-channel thermometer, and feed the temperature signal back to the control system;

Liquid nitrogen flows into the liquid nitrogen storage chamber, the device enters the cooling stage, and the control system monitors the target plate temperature and transportation pipeline pressure in real time;

When the pressure in the liquid nitrogen storage chamber is too high, the liquid nitrogen storage chamber will leak;

When the temperature of the target plate drops to the set temperature and remains stable, the device enters the forming stage. The forming tool starts to form the target plate according to the predetermined trajectory. The plate slowly moves downward under the clamping of the mold, and the overflowing liquid nitrogen overflows through the liquid nitrogen. The hole is discharged to the liquid nitrogen transport pipeline and enters the circulation;

After the first stage of forming, the liquid nitrogen in the liquid nitrogen storage chamber is emptied, the heating element is started, and the device enters the heating stage.

When the temperature measurement device detects that the temperature of the target plate has stabilized to the set temperature, the forming tool contacts the upper clamping mold and remains stationary. The motor drives the screw to cause the support mold to exert upward pressure on the plate. The force sensor feeds back the plate pressure in real time, and the control system controls the The motor keeps the pressure on the plate constant, and the device enters the creep aging strengthening treatment stage for the set time. At the same time, the formed parts are further deformed through the creep effect;

After creep aging, the heating element is switched off and the forming tool is moved to the non-working position.

Implementation case:

Taking the 1mm thick 7050-W (solid solution) aluminum alloy plate as an example, the specific process of this device to achieve ultra-low temperature two-point progressive forming and in-mold creep aging treatment is described in detail. Figure 3 is the process roadmap for the 7050 alloy device.

1. According to the "Heat Treatment Specifications for Deformed Aluminum and Aluminum Alloys", perform solution heat treatment on the 7050 plate with a solution temperature of 475°C and a holding time of 30 minutes to obtain the target plate 7050-W;

2. Place the target plate on the supporting mold and fix it by clamping the mold upper and lower;

3. Weld/glue the thermocouple wire in the temperature measurement device around the target plate, monitor the temperature changes of the plate in real time through a multi-channel thermometer, and feed the temperature signal back to the control system;

4. Open the electromagnetic switch valve (inlet) and self-pressurizing liquid nitrogen container, close the outlet electromagnetic switch valve, liquid nitrogen flows into the liquid nitrogen storage chamber, the device enters the cooling stage, and the control system monitors the target plate temperature and transportation pipeline pressure in real time;

5. When the pressure in the liquid nitrogen storage chamber is too high, the control system controls the outlet electromagnetic switch valve to open the leakage;

6. When the temperature of the target plate drops to -170℃±5℃ and remains stable, the device enters the forming stage. The forming tool starts to form the target plate according to the predetermined trajectory. The three-dimensional load sensor continues with the forming process, and the plate is in the mold clamp. Hold down and move downward slowly, and the overflowing liquid nitrogen will be discharged through the liquid nitrogen overflow hole to the liquid nitrogen transportation pipeline and enter the circulation;

7. After the first stage of forming, open the electromagnetic switch valve (inlet), close the self-pressurizing liquid nitrogen container, turn on the electric liquid nitrogen pump, quickly empty the liquid nitrogen in the liquid nitrogen storage chamber, start the heating element, and the device enters heating stage, according to the "Heat Treatment Specifications for Deformed Aluminum and Aluminum Alloys", the target aging temperature is 160°C;

8. When the temperature measuring device detects that the target plate temperature has stabilized to 160°C, the forming tool contacts the upper clamping mold and remains stationary. The motor drives the screw to make the supporting mold exert upward pressure on the plate. The force sensor feeds back the plate pressure in real time, and the control system passes The motor is controlled to keep the pressure on the plate constant, and the device enters the creep aging strengthening treatment stage, which lasts for 6 hours. At the same time, the formed parts are further deformed through the creep effect.

9. After the creep aging treatment is completed, the heating element is turned off, the motor is turned off, and the forming tool moves to the non-working position.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims (10)

1. The ultra-low temperature two-point incremental forming and in-mold creep aging treatment device is characterized by comprising a two-point incremental forming module, a creep aging treatment module, a cooling medium circulating feeding module and a control system; the two-point progressive forming module comprises a forming tool, an upper clamping die, a lower clamping die and a supporting die; the creep aging treatment module comprises a driving device, a heating element, a temperature measuring device and a force sensor; the cooling medium circulating feeding module comprises a liquid nitrogen storage cavity; the top of the liquid nitrogen storage cavity is open, a target plate is arranged at the top of the liquid nitrogen storage cavity, an upper clamping die and a lower clamping die are used for clamping the edge of the target plate and slide up and down along a guide post vertically arranged in the storage cavity, a supporting die is arranged below the plate, and the supporting die is also arranged in the liquid nitrogen storage cavity; a liquid nitrogen overflow hole is arranged on the liquid nitrogen storage cavity; the liquid nitrogen storage cavity is connected with a liquid nitrogen container and a liquid nitrogen pump; the temperature measuring device monitors the temperature of the target plate in real time, the heating element and the force sensor are arranged on the supporting die, the supporting die is driven by the driving device, and the control system controls the creep aging treatment module and the cooling medium circulating feeding module.

2. The ultralow temperature two-point incremental forming and in-mold creep aging treatment device according to claim 1, further comprising a three-dimensional force transducer, wherein the three-dimensional force transducer is arranged below the whole liquid nitrogen storage cavity, and is used for monitoring forming forces of a target plate in three directions X, Y, Z in the forming process in real time.

3. The ultra-low temperature two-point incremental forming and in-mold creep aging treatment device according to claim 1, wherein the driving device is arranged at the bottom of the supporting die and drives the supporting die to move in a direction approaching to the target plate or in a direction separating from the target plate.

4. The ultra-low temperature two-point incremental forming and in-mold creep aging apparatus of claim 1 wherein the plurality of heating elements are distributed within the support die for heating the target sheet.

5. The ultra-low temperature two-point incremental forming and in-mold creep aging treatment device according to claim 1, wherein the temperature measuring device mainly comprises a plurality of temperature measuring instruments and thermocouples, and the temperature measuring ends of the thermocouples are connected to the edges of the target plate to monitor the temperature of the target plate in real time.

6. The ultra-low temperature two-point incremental forming and in-mold creep aging treatment apparatus of claim 1 wherein the force sensor is disposed within the support die and the force bearing surface contacts the target sheet material for monitoring the pressure of the support die against the target sheet material.

7. The ultralow temperature two-point incremental forming and in-mold creep aging treatment device according to claim 1, wherein a liquid nitrogen inlet and a liquid nitrogen outlet are arranged on two sides of the bottom of the liquid nitrogen storage cavity, an inlet electromagnetic switch valve is arranged at the liquid nitrogen inlet, and an outlet electromagnetic switch valve is arranged at the liquid nitrogen outlet.

8. The ultralow temperature two-point incremental forming and in-mold creep aging treatment device according to claim 7, wherein liquid nitrogen is sprayed out of the liquid nitrogen container and returns to the liquid nitrogen container through an inlet electromagnetic switch valve, a hydraulic sensor, a liquid nitrogen storage cavity, an outlet electromagnetic switch valve and a liquid nitrogen pump in sequence to realize circulation.

9. The ultralow temperature two-point incremental forming and in-mold creep aging treatment device according to claim 1, wherein a plurality of liquid nitrogen overflow holes are arranged on the side wall of the liquid nitrogen storage cavity and are sequentially and vertically arranged and connected with a liquid nitrogen transportation pipeline.

10. A method for processing a target plate by using the ultralow temperature two-point incremental forming and in-mold creep aging treatment device according to any one of claims 1 to 9, characterized by comprising the following steps:

placing a target plate on a supporting die, and fixing the target plate through an upper clamping die and a lower clamping die;

welding/gluing thermocouple wires in a temperature measuring device around a target plate, monitoring the temperature change of the plate in real time through a plurality of paths of thermometers, and feeding back a temperature signal to a control system;

liquid nitrogen flows into the liquid nitrogen storage cavity, the device enters a cooling stage, and a control system monitors the temperature of a target plate and the pressure of a conveying pipeline in real time;

when the pressure in the liquid nitrogen storage cavity is too high, the liquid nitrogen storage cavity leaks;

when the temperature of the target plate is reduced to the set temperature and kept stable, the device enters a forming stage, a forming tool starts forming the target plate according to a preset track, a three-dimensional force transducer continuously performs the forming process, the plate slowly moves downwards under the clamping of a die, and overflowed liquid nitrogen is discharged to a liquid nitrogen conveying pipeline through a liquid nitrogen overflow hole to enter circulation;

after the first stage of forming, evacuating the liquid nitrogen storage cavity, starting the heating element, making the device enter into heating stage,

when the temperature measuring device monitors that the temperature of the target plate is stable to the set temperature, the forming tool contacts the upper clamping die and keeps static, the motor drives the screw rod to enable the supporting die to upwards apply pressure to the plate, the force sensor feeds back the pressure of the plate in real time, the control system keeps the pressure born by the plate constant by controlling the motor, the device enters the creep aging strengthening treatment stage for a set time, and meanwhile, the formed part is further shaped through the creep effect;

after the creep-age process is completed, the heating element is turned off and the forming tool is moved to a non-operative position.