CN113607632B - A testing device for liquid-filled forming performance and forming rules of tailor-welded blanks - Google Patents

Abstract

The invention relates to a testing device for liquid-filled forming performance and forming rules of tailor-welded plates, and belongs to the technical field of special forming technology of tailor-welded plates. The device of the invention adopts the design of the block holder ring. Each block holder is equipped with a hydraulic cylinder. Each hydraulic cylinder applies a blank holder force to the blank holder respectively and controls the size of the blank holder force. The pressure of each block holder is The blank holder force is independently controlled and adjusted, which can flexibly control the blank holder force on the sheets on both sides of the weld, while meeting the compression requirements of tailor-welded blanks of different sizes. It not only controls the movement of the weld seam, but also prevents wrinkles. Through changes The blank holder force can satisfy the research on the influence of different blank holder forces on the forming rules. At the same time, the test device is used to adjust the active radial hydraulic pressure on the left side and the active radial hydraulic force on the left side respectively, and fix the active diameter on a certain side. By changing the active radial hydraulic pressure on the other side, the influence of different active radial hydraulic forces on the forming performance and forming rules of the tailor-welded blank can be obtained.

Description

A test device for liquid-filled forming performance and forming rules of tailor-welded plates

Technical field

The invention relates to a testing device for liquid-filled forming performance and forming rules of tailor-welded plates, and belongs to the technical field of special forming technology of tailor-welded plates.

Background technique

With the further development of science and technology and the continuous progress of society, lightweight structure plays an increasingly important role in improving resource utilization, reducing energy consumption and improving the performance of parts. It has become one of the development trends of today's manufacturing industry. , and there are two main ways to achieve structural lightweighting: material and structure. The structural approach refers to using strong components such as variable thickness plates or variable cross-sections instead of equal thickness plates and equal cross-section members, which can save materials, reduce weight and make full use of the strength and stiffness of the materials, such as tailor-welded plate technology. Tailored welded blanks refer to the technical method of joining two or more plates with different thicknesses, properties or surface coatings together through welding technology and then forming them. The application of tailor-welded blanks can give full play to the role of materials and greatly reduce resource waste, becoming one of the important ways to lightweight structures.

Tailored welded plate liquid-filled forming technology is a comprehensive application of tailor-welded plate forming technology and liquid-filled forming technology. It combines the dual advantages of these two advanced forming technologies and can greatly improve its forming performance while retaining liquid-filled flexibility. The characteristics of forming, forming precision and complex variable thickness and hollow variable cross-section structural parts, are an important means to achieve lightweight forming of parts at present and in the future. Its development is in line with the trend of social development, and its research is of great significance.

At present, there are many studies on the traditional stamping forming of tailor-welded blanks at home and abroad, but there are few studies on the liquid-filled forming technology of tailor-welded blanks. Different test methods, forming rules and deformation mechanisms of tailor-welded blanks are different. same. Because the mechanical properties of tailor-welded blanks are inconsistent with the required deformation conditions, uneven deformation is prone to occur, resulting in large-scale weld movement. It is easy to break during the forming process and cause the product to be scrapped. Therefore, it is necessary to improve the liquid-filled forming performance of tailor-welded blanks. Further research is needed to understand the plastic deformation characteristics of liquid-filled forming of tailor-welded blanks, master the liquid-filled forming rules and deformation mechanisms of tailor-welded blanks, and explore the core issues of this technology, in order to guide and control the liquid-filled forming of tailor-welded blanks. To lay the foundation for application, the present invention provides a test device and a test method for studying the liquid-filled formability and forming rules of tailor-welded plates. The test device and test method can be used to obtain the liquid-filled formability and forming rules of tailor-welded plates.

Contents of the invention

The technical problem solved by the present invention is to overcome the shortcomings of the existing technology. The present invention discloses a test device for studying the liquid-filled forming performance and forming rules of tailor-welded plates, and provides a liquid-filled forming of tailor-welded plates that is simple to operate and easy to implement. The test device and test method for performance and forming rules can be used to obtain the liquid-filled forming performance and forming rules of tailor-welded blanks.

In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

A test device for the liquid-filled forming performance and forming rules of tailor-welded plates. The device includes a base, a glass plate, an O-shaped rubber sealing ring D, a cushion block, a concave mold cover, an O-shaped rubber sealing ring A, and an independent hydraulic system. Source III, O-shaped rubber seal B, backing plate, left clamping ring, hydraulic cylinder III, O-shaped rubber sealing ring C, baffle, hydraulic cylinder II, hydraulic cylinder I, right clamping ring, independent hydraulic system source I , independent hydraulic system source II, vacuum pump system and forming law measurement system;

There is a sealing groove above the base for placing the O-shaped rubber seal D, and the glass plate and gasket are sealed on the base;

The right side of the cushion block has a vacuum pump system interface combined with the vacuum pump system and a high-pressure liquid outlet channel;

There is a sealing groove above the pad for placing the O-shaped rubber seal A, and the die sleeve is sealed on the pad;

There is a liquid filling interface and a high-pressure liquid inlet channel combined with the independent hydraulic system source III on the left side of the die sleeve. The active radial high-pressure liquid generated by the independent hydraulic system source III enters the left side of the tailor-welded plate through the liquid inlet channel. The liquid-filled chamber applies the active radial pressure of the liquid to the outer periphery of the left side of the tailor-welded blank;

There is a liquid filling interface and a high-pressure liquid inlet channel combined with the independent hydraulic system source II on the right side of the die sleeve. The active radial high-pressure liquid generated by the independent hydraulic system source II enters the left side of the tailor-welded plate through the liquid inlet channel. The liquid-filled chamber applies the active radial pressure of the liquid to the outer periphery of the right side of the tailor-welded blank;

Add a backing plate between the thin plate of the tailor-welded blank and the left edge ring;

The left blank holder and the right blank holder form a circular ring. There is an O-ring seal groove on the outside of the baffle for installing the O-shaped rubber seal C. The top of the baffle is connected to the hydraulic cylinder II for controlling the location of the baffle. s position;

On the right side of the right pressure side circle, there is a liquid filling interface combined with the independent hydraulic system source I and a liquid inlet channel for high-pressure liquid;

A forming regularity measurement system is installed in the center of the base and under the high transmittance glass plate.

The left edge ring has a semi-circular ring structure. There is an O-ring seal groove inside the ring, which is used to install the O-shaped rubber seal C. It is used for sealing between the baffle and the baffle. There is an O-ring seal groove on the outside. Groove, install O-shaped rubber sealing ring B, which is used to seal the active radial high-pressure liquid generated by the independent hydraulic system source III. The lower part of the left clamping ring is directly installed on the top of the backing plate, and the upper part of the left clamping ring is directly connected to the hydraulic cylinder III. Connection, hydraulic cylinder III is used to control the size of the blank holder force loaded on the left blank holder ring.

The right clamping ring has a semi-circular ring structure, with an O-ring seal groove on the outside, and an O-shaped rubber seal B is installed, which is used to seal the active radial high-pressure liquid generated by the independent hydraulic system source II, underneath the right clamping ring It is directly installed on the top of the tailor-welded plate, and the top of the right blank holder is connected to the hydraulic cylinder I. The hydraulic cylinder I is used to control the size of the blank holder force loaded on the right blank holder.

On the right side of the pad, there is a liquid outlet port that is combined with the vacuum pump system and a liquid outlet channel for high-pressure liquid. A sealing gasket and a cone surface composite seal are used between the liquid outlet port and the joint of the liquid outlet port.

The forming rule measurement system includes a laser rangefinder, binocular vision system, LED charging light source, data transmission cable, data acquisition system, and computer system. The data of the vacuum pump system is transmitted to the data acquisition system through the data transmission cable;

The forming law measurement system collects the deformation data of the tailor-welded blank during the hydraulic bulging process by collecting the deformation image of the tailor-welded blank through the binocular vision system.

The binocular vision system is a non-contact optical measurement system that uses digital image processing technology to obtain the three-dimensional geometry and relative displacement of each point on the surface of the tailor-welded blank during the liquid-filling forming process, so as to realize dynamic monitoring of the liquid-filled forming process of the tailor-welded blank and obtain The real-time weld movement pattern data of the tailor-welded plate and the strain data used to calculate the forming pattern of the tailor-welded plate are uploaded to the data acquisition system in real time through the transmission cable. At the same time, the independent hydraulic system sources I radial hydraulic pressure data, independent hydraulic pressure The data of system source II liquid-filled forming force and independent hydraulic system source III radial hydraulic pressure are uploaded to the data acquisition system in real time through the transmission cable. The laser range finder measures the displacement of the tailor-welded plate during the bulging process in real time. Laser range measurement The instrument data is also uploaded to the data acquisition system in real time through the transmission cable. Glass plates require visible light transmittance greater than 90%.

The left side of the die sleeve has a liquid filling interface combined with the independent hydraulic system source III and a liquid inlet channel for high-pressure liquid. The joint between the liquid filling interface and the liquid inlet channel III uses a sealing gasket and a cone surface composite seal.

Tailored welded plates include thin plates, thick plates and welds. The tailor welded plates are placed on the die set, the welds are placed in the center, and a backing plate is added between the thin plate and the left edge ring to ensure the equalization of the edge flange. Thickness, the backing plate is a semi-circular ring backing plate, the thickness of the backing plate is (t _h - _{t b} ) mm, and the grid is printed on the tailor-welded plate.

The thickness difference between thin plates and thick plates is quantitatively described by the thickness ratio eta _t , which is equal to the ratio of the thickness of thick plates to thin plates:

η _t =th _h /t _b

In the formula: t _b - thin plate thickness, t _h - thick plate thickness, the value range of plate thickness ratio is eta _t ≥ 1, the larger the thickness ratio eta _t is, the greater the plate thickness difference of differential thickness tailor-welded plates is;

The weld position is quantitatively expressed by the chord height ratio eta _d , which is equal to the ratio of the chord height of the thin plate in the bulging zone of the tailor-welded plate to the diameter of the bulging zone:

η _d =D _b /D ₀

In the formula: D _b - the chord height of the thin plate, D ₀ - the diameter of the bulging area of the tailor-welded plate, the value range of the chord-to-height ratio is 0 ≤ eta _d ≤ 1, when eta _d = 1, it means that the tailor-welded plate is completely thin plate, When eta _d =0, it means that the tailor-welded blank is completely thick. As the chord-to-height ratio decreases, the proportion of thin plates in the tailor-welded blank decreases.

Compared with the prior art, the beneficial effects of the present invention are:

1. The device of the present invention adopts a block blank holder design. Each block holder is equipped with a hydraulic cylinder. Each hydraulic cylinder applies a blank holder force to the blank holder respectively to control the size of the blank holder force. Each block holder is equipped with a hydraulic cylinder. The blank holder force of the ring can be independently controlled and adjusted, which can flexibly control the blank holder force on the sheets on both sides of the weld, and at the same time meet the compression requirements of tailor-welded blanks of different sizes (plate thickness ratio and chord height ratio), which not only controls the welding Seam movement and wrinkle prevention. By changing the blank holder force, the research on the influence of different blank holder forces on the forming rules can be satisfied. At the same time, the test device is used to adjust the active radial hydraulic pressure on the left side and the active radial hydraulic pressure on the left side respectively. By fixing the active radial hydraulic force on one side and changing the active radial hydraulic force on the other side, we can study the influence of different active radial hydraulic forces on the forming performance and forming rules of tailor-welded blanks;

2. The test device of the present invention adopts a modular, combined, detachable and replaceable structure. The test device can replace different forms of blank holders and backing plates according to different experimental conditions to meet the needs of tailor-welded blanks with different plate thickness ratios and different position welds. There is no need to change molds, and different plate thickness ratios and different position welding can be achieved. Research on the forming performance and forming rules of tailor-welded blanks has greatly saved costs;

3. The test device of the present invention uses a binocular vision system and a laser rangefinder to obtain deformed images captured by cameras during the liquid-filled forming process of tailor-welded plates. After image preprocessing, feature extraction, stereo matching, timing matching, and three-dimensional reconstruction, etc. Work, solve the three-dimensional information of the tested sample, realize the three-dimensional tracking of the sample in time series, and complete the strain measurement during the liquid-filled forming process of the tailor-welded blank.

4. The test device of the present invention adopts a data acquisition system based on a single-chip microcomputer and a computer bus interface with a computer as the control core, which can realize real-time and high-precision collection of deformation data during the liquid-filled forming process of tailor-welded plates, and at the same time, the hydraulic cylinder pressure and bulging height and other measurement results are transmitted to the data acquisition system in a timely manner to ensure the precise unification of the timing of each measurement data and the accuracy of various measurement data.

5. The experimental method of the present invention is easy to operate, has low experimental cost and high experimental efficiency. When the invention involves a test device and test method for studying the liquid-filled forming performance and forming rules of tailor-welded plates, the required operating steps are few and easy to operate. Generally, only 1-3 steps are required for each type of tailor-welded plate. Only one test is required, the test results are stable, repeated tests are avoided, and the test cost is low.

Description of the drawings

Figure 1 is a schematic diagram showing the main parameters of tailor-welded blanks;

Figure 2 is a schematic diagram of a test device according to the present invention for studying the liquid-filled forming performance and forming rules of tailor-welded plates;

Figure 3 is a process flow chart of the invention to study the liquid-filled forming performance and forming test of tailor-welded blanks;

Figure 4 is a schematic diagram of the grid of tailor-welded plates;

Figure 5 shows the effect of plate thickness ratio on the ultimate bulging height (ηd=0.5);

Figure 6 shows the effect of weld position on the ultimate bulging height (etat=1.5);

Figure 7 shows the influence of plate thickness differences on the weld movement of tailor-welded plates;

Figure 8 shows the influence of plate thickness difference on the maximum movement of the weld.

Detailed ways

The present invention will be described in detail below with reference to the drawings and specific embodiments.

A test device of the present invention for studying the liquid-filled forming performance and forming rules of tailor-welded plates relates to a tailor-welded plate. Tailor-welded plates refer to two or more pieces with different thicknesses, properties or surface coatings made by welding technology. The plates connected together are mainly composed of thin plates, thick plates and welds. The schematic diagram of its main parameters is shown in Figure 1;

The thickness difference between thin plates and thick plates and the weld position of tailor-welded blanks are two basic physical quantities that characterize the forming of tailor-welded blanks. The difference in plate thickness is the most important feature that distinguishes differential-thickness tailor-welded blanks from equal-thickness tailor-welded blanks. The weld position is closely related to the stress and strain state during the hydraulic bulging process of the tailor-welded blanks, and is an important factor that affects differential-thickness tailor-welded blanks. One of the main parameters of the plastic deformation characteristics of welded plates.

Figure 1 shows a schematic diagram showing the main parameters of the tailor-welded blank. It can be seen from the figure that the thickness difference between thin plates and thick plates can be quantitatively described by the thickness ratio eta _t . The plate thickness ratio is equal to the ratio of the thickness of the thick plate to the thickness of the thin plate:

η _t =th _h /t _b

In the formula: t _b -thickness of thin plate, t _h -thickness of thick plate. The value range of the plate thickness ratio is eta _t ≥1. The larger the thickness ratio eta _t is, the greater the difference in plate thickness of differential-thickness tailor-welded plates is. The initial position of the weld seam (referred to as the weld seam position) directly determines the proportion of thin plates and thick plates in the slab, and is an important factor affecting the hydroforming of differentially thick tailor-welded blanks. When the weld position changes, the chord height of the thick plate (D _h ) and the chord height of the thin plate (D _b ) also change. On the premise that the total forming diameter remains unchanged, the chord height of the thin plate (D _b ) The ratio to the forming diameter of the tailor-welded blank will inevitably change accordingly. The weld position can be quantitatively expressed by the chord height ratio eta _d , which is equal to the ratio of the chord height of the thin plate in the bulging zone of the tailor-welded blank to the diameter of the bulging zone:

η _d =D _b /D ₀

In the formula: D _b - the chord height of the thin plate, D ₀ - the diameter of the bulging zone of the tailor-welded plate. The value range of the chord-to-height ratio is 0≤eta _d≤1 . When eta _d =1, it means that the tailor-welded blank is completely thin. When eta _d =0, it means that the tailor-welded plate is completely thick plate. As the chord-to-height ratio decreases, the proportion of thin plates in the tailor-welded blanks decreases. Different plate thickness ratios and different weld positions have different liquid-filled forming performance and forming rules of tailor-welded plates. For this reason, the present invention is a test device and test method for studying the liquid-filled forming performance and forming rules of tailor-welded plates. , this test device and test method can be used to obtain the liquid-filled forming performance and forming rules of tailor-welded blanks under different conditions.

A test device for studying the liquid-filled forming performance and forming rules of tailor-welded blanks. The test device adopts a block holder design. Each block holder is equipped with a hydraulic cylinder, and each hydraulic cylinder applies pressure to the blank holder respectively. Edge force, control the size of the blank holder. The blank holder force of each block blank holder ring is independently controlled and adjusted. It can flexibly control the size of the blank holder on the sheets on both sides of the weld, while meeting the needs of different sizes (plate thickness ratio and chord). The compression requirements of tailor-welded blanks (high ratio) can not only control the movement of the weld, but also prevent wrinkles. By changing the blank holder force, it can meet the research on the influence of different blank holder forces on the forming rules. The test device adopts modular, combined, Detachable and replaceable structure. The test device can replace different forms of blank holders and backing plates according to different experimental conditions to meet the needs of tailor-welded blanks with different plate thickness ratios and different position welds. There is no need to change molds, and different plate thickness ratios and different position welding can be achieved. Research on the forming performance and forming rules of tailor-welded blanks with seams has greatly saved costs; the diagram is shown in Figure 2.

A test device for studying the liquid-filled forming performance and forming rules of tailor-welded blanks. The entire device adopts a modular, combined, removable, and replaceable structure. The modules can be adjusted and adjusted according to differential thickness tailor-welded blanks with different plate thickness ratios. replace. Including base 35, high transmittance glass plate 34, O-shaped rubber sealing ring D (33), cushion block 32, female mold cover 31, O-shaped rubber sealing ring A30, independent hydraulic system source III29, liquid filling interface III28, Liquid inlet channel III27, O-shaped rubber sealing ring B26, backing plate 25, left edge ring 24, hydraulic cylinder III23, O-shaped rubber sealing ring C22, baffle 21, hydraulic cylinder II20, tailor welded plate 19, hydraulic cylinder I18, Liquid inlet channel I17, right pressure edge ring 15, liquid filling interface I14, independent hydraulic system source I13, liquid inlet channel II12, liquid filling interface II11, independent hydraulic system source II10, liquid outlet channel 9, liquid outlet channel interface 8, vacuum pump System 7, computer system 6, data acquisition system 5, connecting cable 4, LED charging light source 3, binocular vision system 2 and laser rangefinder 1;

There is a sealing groove above the base 35. After placing the O-shaped rubber sealing ring D (33) in the sealing groove, the high transmittance glass plate 34 and the cushion block 32 are placed on the base 35 in sequence for sealing. Sealing of filled liquids during the process. The high transmittance glass plate 34 requires a visible light transmittance greater than 90%, which facilitates the video device to record the forming process through the high transmittance glass plate 34 .

The right side of the cushion block 32 is provided with a vacuum pump system interface 8 combined with the vacuum pump system 7 and a liquid outlet channel 9 for high-pressure liquid. When the tailor-welded plate 19 bursts, the liquid and gas flowing out can be quickly passed through the liquid outlet by the vacuum pump system 7 The channel 9 is extracted, and the sealing gasket and cone surface composite seal are used between the interface 8 and the joint of the vacuum pump system 7.

There is a sealing groove above the cushion block 32, and an O-shaped rubber sealing ring is placed in the sealing groove. After placing the O-shaped rubber sealing ring A30 in the sealing groove, place the female mold cover 31 on the cushion block 32. Sealing, used to seal the liquid-filled liquid during the forming process.

The left side of the die sleeve 31 is provided with a liquid filling interface III28 combined with an independent hydraulic system source III29 and a liquid inlet channel III27 for high-pressure liquid. A sealing gasket and a tapered surface are used between the joints of the liquid filling interface III28 and the liquid inlet channel III27. Composite seal, the active radial high-pressure liquid generated by the independent hydraulic system source III29 is controlled by an independent hydraulic control system and enters the liquid filling chamber on the left side of the tailor-welded plate through the liquid inlet channel 27, applying the active radial pressure of the liquid to On the outer periphery of the left side of the tailor-welded plate, the active radial pressure is independently controlled and adjusted through a separate hydraulic cylinder. By individually controlling the magnitude of the active radial hydraulic force on the left side, the material in the flange area of the thin and thick sides of the tailor-welded plate is controlled. The flow then controls the forming of the tailor-welded blanks, thereby controlling the plastic deformation characteristics of the tailor-welded blanks;

There is a liquid filling interface 11 combined with the independent hydraulic system source II10 and a liquid inlet channel 12 for high-pressure liquid on the right side of the die sleeve 31. A sealing gasket and a tapered surface are used between the joints of the liquid filling interface 11 and the liquid inlet channel 12. Composite seal, the active radial high-pressure liquid generated by the independent hydraulic system source II10 is controlled by the independent hydraulic control system and enters the liquid filling chamber on the left side of the tailor-welded plate through the liquid inlet channel 12, applying the active radial pressure of the liquid to On the outer periphery of the right side of the tailor-welded plate, the active radial pressure is independently controlled and adjusted through a separate hydraulic cylinder. By individually controlling the magnitude of the active radial hydraulic force on the right side, the material flow in the flange area of the thin and thick sides of the tailor-welded plate is controlled. Then control the forming of tailor-welded blanks, and then control the plastic deformation characteristics of tailor-welded blanks;

The tailor-welded plate 17 is composed of a thin plate 17-I, a thick plate 17-III and a weld 17-II. The tailor-welded plate 17 is placed on the die set 31, and the weld 17-II is placed in the center. On the thin plate A pad 25 is added between the left edge ring 24 to ensure the equal thickness of the edge flange. The pad 25 is a semicircular ring pad. The shape of the pad 25 is as shown in Figure 3, and the thickness is (t _h - t _b )mm, print the grid as shown in Figure 4 on the tailor-welded plate;

The left edge ring 24 has a semi-circular ring structure. There is an O-ring seal groove inside the ring, which is used to install the O-shaped rubber seal C22 and is used for sealing between the baffle 21. There is an O-ring seal on the outside. ring groove, install the O-shaped rubber sealing ring B26, which is used to seal the active radial high-pressure liquid generated by the independent hydraulic system source III27. The bottom of the left blank holder 24 is directly installed on the top of the thin plate 17-I side of the tailor-welded plate 17. Above the backing plate 25, the top of the left blank holder 24 is directly connected to the hydraulic cylinder III23. The hydraulic cylinder III23 can directly control the size of the blank holder force loaded on the left blank holder 24.

The right edge ring 15 has a semi-circular ring structure, and the inside of the ring is the sealing surface. It is sealed with the shaped rubber sealing ring C22 installed on the side of the baffle 21. There is an O-shaped sealing ring groove on the outside, and the O-shaped rubber seal is installed. Ring B26 is used to seal the active radial high-pressure liquid generated by the independent hydraulic system source II10. The lower part of the right clamping ring 15 is directly installed above the thick plate 17-III side of the tailor-welded plate 17, and the upper part of the right clamping ring 15 is directly installed. Connected to the hydraulic cylinder I18, the hydraulic cylinder I18 can directly control the size of the blank holder force loaded on the right blank holder ring 15.

The left blank holder ring 24 and the right blank holder ring 15 form a circular ring. There is a sealing groove on the side of the semicircular ring for sealing the gap between the left blank holder ring 24 and the right blank holder ring 15. The outer side of the baffle 21 has a sealing groove. There is an O-shaped sealing ring groove. After installing the O-shaped rubber sealing ring C22, it is then installed into the inner cavity of the ring composed of the left clamping ring 24 and the right clamping ring 15. The top of the baffle 21 is directly connected to the hydraulic cylinder II20. , used to control the position of the baffle 21.

There is a liquid filling interface I14 combined with the independent hydraulic system source I13 and a liquid inlet channel I16 for high-pressure liquid on the right side of the right pressure edge ring 15. A sealing gasket and a cone are used between the joints of the liquid filling interface I14 and the liquid inlet channel I16. Surface composite seal, the bulging high-pressure liquid generated by the independent hydraulic system source I13 is controlled by an independent hydraulic control system, and enters the left pressure side ring 24, the right pressure side ring 15, through the liquid filling interface I14 and the liquid inlet channel I16 The baffle 21 and the tailor-welded plate 17 jointly form a high-pressure liquid filling chamber, and then the pressure of the high-pressure liquid is directly applied to the top of the tailor-welded plate 17 in the high-pressure liquid filling chamber. The pressure is independently controlled and adjusted through the independent hydraulic system source I13. The magnitude of the high-pressure liquid filling pressure can be controlled to control the forming of the tailor-welded plate 17 and thereby control the plastic deformation characteristics of the tailor-welded plate;

The right side of the pad 32 has a liquid outlet port 8 combined with the vacuum pump system 7 and a liquid outlet channel 9 for high-pressure liquid. The liquid outlet port 8 and the joint of the liquid outlet port 8 adopt a sealing gasket and a cone surface composite type. seal. The data of the vacuum pump system is transmitted to the data acquisition system 5 through the data transmission cable 4. A forming pattern measurement system is installed in the center of the base 35 and below the high transmittance glass plate 34. The forming pattern measurement system mainly consists of a laser rangefinder 1, a binocular vision system 2, an LED charging light source 3, and a data transmission cable 4. It is composed of data acquisition system 5 and computer system 6. The data acquisition system 5 is designed with a computer as the control core and based on the microcontroller and computer bus interface. The circuit uses a high-resolution AD conversion chip to design a digital-to-analog conversion circuit, and uses a digital filtering method to filter the collected force signals, so that the acquisition system has high reliability and integration, and is used to complete the force signal processing. Real-time, high-precision collection of signal data.

The measurement system collects the deformation data of the tailor-welded plate 17 during the hydraulic bulging process by collecting the deformation image of the tailor-welded plate 17 through the binocular vision system 2 . The binocular vision system 2 is a non-contact optical measurement system that uses digital image processing technology to obtain the three-dimensional geometry and relative displacement of each point on the surface of the tailor-welded blank during the liquid-filling forming process, thereby realizing dynamic monitoring of the liquid-filling forming process of the tailor-welded blank 17 , obtain the real-time weld movement pattern data of the tailor-welded plate 17 and the strain data used to calculate the forming pattern of the tailor-welded plate 7, and upload them to the data acquisition system 5 in real time through the transmission cable 4. At the same time, the independent hydraulic system source I13 radial hydraulic pressure The force data, the independent hydraulic system source II10 liquid-filled forming force and the independent hydraulic system source III29 radial hydraulic force data are uploaded to the data acquisition system 5 in real time through the transmission cable 4. On the other hand, the laser rangefinder 1 can real-time Measuring the displacement during the bulging process of the tailor-welded blank enables non-contact and rapid bulging height measurement. The data from the laser rangefinder 1 is also uploaded to the data acquisition system 5 in real time through the transmission cable 4. It ensures that the finally calculated stress and strain can be accurately unified in time series, ensuring the accuracy of the weld movement rules and forming rules.

The invention also provides a test device and a test method for studying the liquid-filled forming performance and forming rules of tailor-welded plates using the above device, which is used to study the liquid-filled forming performance and forming rules of tailor-welded plates. The test process mainly includes the following steps:

Step 1. Preparation of differential thickness tailor welded plate specimens. Preparation of differential thickness tailor welded plates. The materials of the prepared tailor welded plates are steel, aluminum alloy, magnesium alloy, titanium alloy and other materials. The following is the differential thickness tailor welded plate. The preparation steps are described in detail:

1.1. First, the plate is cut through the sheet metal shearing machine, and then the plate is chemically cleaned using chemical degreasing and alkali cleaning methods to obtain rectangular thin plates and rectangular thick plates. The thickness of the thin plates and thick plates is between 0.3mm and 5mm. between;

1.2. Use welding equipment to weld rectangular thin plates and thick plates to obtain tailor-welded plates of different specifications and thicknesses 19. The welding equipment uses tungsten arc welding, laser welding, electron beam and other welding methods according to the welding characteristics of the materials;

1.3. According to the size of the test device, the differentially thick tailor-welded plates are then cut into circular blanks through wire cutting;

Requirements for the produced circular blanks: 1) It should be ensured that there are no cracks on the edges of the produced circular blanks; 2) Samples of different sizes and shapes should be prepared, and there should be no less than 3 samples of each type, and each sample should be prepared under the same conditions. Conduct three experiments for each experiment, and take the average of the three experiments as the final experimental result. The experimental steps are as follows:

Step 2: Make a grid on the surface area of the circular blank that needs to be measured. The grid can be made by manual spray painting or laser ablation. The shape of the grid is shown in Figure 4. The grids produced on the surface of the round blank should be randomly distributed. The contrast between the grid lines and the original surface of the plate should be obvious. The production range of the grid should be larger than the measured deformation area. The sample should be degreased and cleaned with alcohol and marked. Use a machine or laser engraving machine to mark the numbers and make corresponding records.

Step 3: Calibrate the measuring instrument before the experiment to ensure the accuracy of the measurement data.

3.1. Calibrate the sensor and laser rangefinder before the experiment to obtain the proportional relationship between the load size corresponding to the tensile output analog quantity and the digital quantity.

3.2. After the dual cameras and light source device are fixed, perform offline calibration of the binocular vision system to determine the internal parameters of each of the dual cameras and the external parameters between the two cameras for subsequent three-dimensional reconstruction and strain calculation;

Step 4: Install the test device and place the differential thickness tailor-welded plate into the test device. The installation steps are described in detail below:

4.1 Install the O-shaped rubber seal D (33) on the base 35, then place the high transmittance glass plate 34 on the base 35, then install the gasket 32 on the base 35, and install the O-shaped rubber seal A30 into the sealing groove of the cushion block 32, and the female mold sleeve 31 is installed on the cushion block 32. After the installation is completed, the independent hydraulic system source II10 and the independent hydraulic system source III29 are connected to the female mold sleeve 31 using a high-pressure adapter to form a diameter to the pressure generation sources II and III, and then the independent hydraulic system source II10 and the independent hydraulic system source III are connected to the data acquisition system 5 through the data cable 4, and the hydraulic cylinder pressure data is uploaded to the data acquisition system 5 in real time;

4.2 Place the differential thickness tailor-welded plate blank 17 completed in step 1 on the female mold sleeve 31, with the side of the differential thickness tailor-welded plate 17 having a stepped surface facing upward, and the thin plate side 17-I placed on the left side of the female mold sleeve 31 , add a backing plate 25 between the thin plate and the left blank holder ring 24 to ensure equal thickness and equal clearance of the blank holder flange. The shape of the backing plate 25 is as shown in Figure 3, and the thickness is (t _h - t _b ) mm;

4.3 Install the LED charging light source 3, binocular vision system 2 and laser rangefinder 1 respectively on the test platform. The signal output ends of the binocular vision system 2 and laser rangefinder 1 are respectively connected to the data acquisition system 5, and the data are synchronized. The acquisition system 5 is connected to the computer system 6 . The vacuum pump system 7 is also connected to the data acquisition system 5 through cables, and the system data can be uploaded to the data acquisition system 5 in real time.

4.4 Place the components installed in step 4.2 on the forming pattern measurement system composed of step 4.3, and place the forming pattern measurement system in the center of the base 35, below the high transmittance glass plate 34.

4.5 Install the left blank holder 24 on the hydraulic cylinder III23 and the right blank holder 15 on the hydraulic cylinder II20, adjust the position, and install the O-shaped rubber sealing ring B26 on the left blank holder 24 and the right blank holder. In the sealing groove of 15, after the installation is completed, use the high-pressure adapter to connect the independent hydraulic system source I13 with the right pressure side ring 15 to form the source I of the liquid filling pressure, and then the source I of the liquid filling pressure passes through the data cable 4 is connected to the data acquisition system 5, and uploads the hydraulic cylinder pressure data to the data acquisition system 5 in real time;

4.6 Install the O-shaped rubber sealing ring C22 into the sealing groove of the baffle 21 to form the baffle assembly, then install the baffle assembly into the ring formed by the left clamping ring 24 and the right clamping ring 15, and finally install the baffle assembly. The plate assembly is connected to hydraulic cylinder I18. Hydraulic cylinder I18, hydraulic cylinder II20, and hydraulic cylinder III23 individually control the hydraulic pressure and are connected to the data acquisition system 5 through the data cable 4 to upload the hydraulic cylinder pressure data to the data acquisition system 5 in real time. At the same time, the independent hydraulic system source I13, the independent hydraulic system source II10, and the independent hydraulic system source III29 are respectively connected to the data acquisition system 5 through the data cable 4, and upload the hydraulic cylinder pressure data to the data acquisition system 5 in real time.

Step 5: Forming test, the forming test steps are described in detail below;

5.1 In the test, the plate thickness ratio eta _t and the chord height ratio eta _d were taken as variable parameters respectively to study the influence of the plate thickness difference and weld position of the tailor-welded plate on the cracking pressure, ultimate bulging height and weld movement of the tailor-welded plate. When studying the effect of plate thickness difference on the forming of tailor-welded plates, it is necessary to set the chord-to-height ratio of the tailor-welded plates to eta and _d as a fixed value; when studying the effect of the weld position on the forming of tailor-welded plates, it is necessary to set the The plate thickness ratio eta _t is a constant value.

5.2 During the experiment, first control the hydraulic cylinder I18, hydraulic cylinder II20, and hydraulic cylinder III23, and at the same time control the left clamping ring 24, the right clamping ring 15 and the baffle 21 to move upward, and then adjust the thickness difference made in step 1 The tailor welded plate 17 is placed on the die sleeve 31, with the side of the differential thickness tailor welded plate 17 having a stepped surface upward, and the thin plate side 17-I placed on the left side of the die sleeve 31, between the thin plate and the left edge ring 24 Add a backing plate 25 to ensure equal thickness and equal clearance of the edge flange. The shape of the backing plate 25 is shown in Figure 3, and the thickness is (t _h - t _b ) mm.

5.3 Control the hydraulic cylinder I18, hydraulic cylinder II20, and hydraulic cylinder III23 to control the left blank holder ring 24, the right blank holder ring 15, and the baffle 21 to close the mold downward, and then increase the blank holder force of the hydraulic cylinder I18 and the hydraulic cylinder III23 to ensure expansion. No flow occurs during the forming process, and the blank holder force of the hydraulic cylinder I18 and hydraulic cylinder III23 remains unchanged during the liquid-filled forming process;

5.4 Control the independent hydraulic system source II10 and the independent hydraulic system source III29 to control the radial pressure generation sources II and III so that they are at a fixed value. According to the test conditions, different radial pressure II and radial pressure III can be converted The influence of different radial pressures on the liquid-filled forming rules of differentially thick tailor-welded plates was obtained.

5.5 Control the independent hydraulic system source I13 according to the preset liquid filling pressure curve to control the liquid filling pressure, and slowly fill the die sleeve 31 with liquid. In order to ensure the comparability of the test results, each liquid filling The time, frequency and deformation rate are as stable as possible, and the curve of the actual filling pressure versus time is consistent with the curve of the preset filling pressure. As the liquid filling time continues, the forming degree of the differential-thickness tailor-welded plate continues to increase. When the forming reaches its forming limit, the differential-thickness tailor-welded plate breaks. During the forming process, the source I of the liquid-filling pressure is followed by the data cable 4. The data acquisition system 5 is connected, and the hydraulic cylinder pressure data is uploaded to the data acquisition system 5 in real time. When the crack occurs, the forming pressure reaches the peak and then decreases, and the cracking pressure value is the peak value of the forming pressure. During the experiment, the laser rangefinder 1 differentially transmits the bulging height of the thick tailor-welded plate to the data acquisition system 5 in real time. While filling the liquid, the vacuum pump system 7 of the device needs to be turned on, and the die sleeve 31 and the spacer block 32. The gas and liquid in the cavity formed by the high transmittance glass plate 34 and the differential thickness tailor-welded plate 17 are eliminated in real time, and the data information is uploaded to the data acquisition system in real time. After the forming is completed, control the hydraulic cylinder I18, hydraulic cylinder II20, and hydraulic cylinder III23 to control the left blank holder 24, the right blank holder 15, and the baffle 21 to move upward. After moving to a safe position, close the equipment and take out the formed sample. ;

Step 6: Utilize the modular, combined, detachable and replaceable structure of the test device of the present invention, replace different forms of blank holders and pads according to different experimental conditions, and then replace different plate thickness ratios and different For tailor-welded blanks with welded seams at different positions, repeat steps 5.1 to 5.5 to obtain research on the forming performance and forming rules of tailor-welded blanks with different plate thickness ratios and welded seams at different positions;

Step 7. Use the test device to control the hydraulic cylinder I18 and the hydraulic cylinder III23, respectively adjust the size of the blank holder force exerted on the left blank holder 24 and the right blank holder 15, fix the blank holder force on one side, and change the blank holder force on the other side. Regarding the size of the blank holder force, repeat steps 5.1 to 5.5 to obtain a study on the impact of different blank holder forces on the forming performance and forming rules of tailor-welded blanks;

Step 8. Use the test device to control the independent hydraulic system source II10 and the independent hydraulic system source III29, respectively adjust the active radial hydraulic pressure on the left and the active radial hydraulic pressure on the left, and fix the active radial hydraulic pressure on a certain side. Force, change the size of the active radial hydraulic force on the other side, repeat steps 5.1 to 5.5, and obtain a study on the influence of different active radial hydraulic forces on the forming performance and forming rules of tailor-welded blanks;

Step 9. Data processing after forming test

After the forming test is completed, the data processing software on the computer system 6 processes the data obtained by the data acquisition system during the forming process, and then exports and then processes it, and finally obtains the weld movement law and the forming law curve of the differential thickness tailor-welded plate. .

Example

In the experiment, the plate thickness ratio η _t and the chord-to-height ratio eta _d were taken as variable parameters to study the influence of the plate thickness difference and weld position of the tailor-welded plates on the cracking pressure, ultimate bulging height and weld movement of the tailor-welded plates. As shown in Table 1, there are five cases of plate thickness ratio, namely eta _t =3:1.5=2.0, eta _t =3:1.8=1.67, eta _t =3:2=1.5, eta _t =3:2.3 =1.3 and eta _t =3:2.5=1.2. There are five cases of welding seam position, namely eta _d =0.18, eta _d =0.32, eta _d =0.5, eta _d =0.68 and eta _d =0.82. When studying the influence of plate thickness difference on the forming of tailor-welded blanks, it is necessary to set the chord-to-height ratio of the tailor-welded blanks to η _d = 0.5 as a fixed value, that is, the weld seam is located in the center of the tailor-welded blanks; when studying the relative position of the weld seams When considering the influence on the forming of welded plates, it is necessary to set the plate thickness ratio eta _t = 1.5 of the tailor-welded plates as a fixed value. The detailed research plan is shown in Table 2.

5.1 In the test, the plate thickness ratio eta _t and the chord height ratio eta _d were taken as variable parameters respectively to study the influence of the plate thickness difference and weld position of the tailor-welded plate on the cracking pressure, ultimate bulging height and weld movement of the tailor-welded plate. When studying the influence of plate thickness differences on the forming of tailor-welded plates, the chord-to-height ratio of the tailor-welded plates needs to be set to a fixed value of eta _d = 0.5, that is, the weld is located in the center of the tailor-welded plates; when studying the position of the welds, When considering the influence on the forming of welded plates, it is necessary to set the plate thickness ratio eta _t = 1.5 of the tailor-welded plates as a fixed value. The detailed research plan is shown in Table 2.

Table 1 Parameters affecting hydraulic bulging of tailor-welded blanks

Table 2 Research plan

The tailor-welded plates in this experiment were welded by argon arc welding. After the welding was completed, the welds were polished and then laser cut into round billets with the same diameter of Φ220mm. Each sample was processed under the same conditions. Three experiments were carried out, and the average value of the three samples was taken as the final experimental result.

In order to study in detail the influence of plate thickness differences on the ultimate bulging height of differential-thickness tailor-welded plates, the influence of different plate thickness differences on the ultimate bulging height with the weld position at the center was analyzed. Figure 5 shows the changing trend of the ultimate bulging height of tailor-welded plates with plate thickness ratio, and Figure 6 shows the influence of weld position on the ultimate bulging height (etat=1.5);

Hydraulic bulging of differentially thick tailor-welded blanks with different plate thickness ratios (η _t =2.0, η _t =1.67, η _t =1.5, eta _t =1.3 and eta _t =1.2) with the weld seam located in the center of the tailor-welded blank. From the experimental results, it can be seen from the figure that the bulging results of differentially thick tailor-welded blanks with different plate thickness ratios are different, the most obvious of which is the different bulging heights of tailor-welded blanks.

When the plate thickness ratio eta _t =3:2=1.5, the hydraulic pressure of tailor-welded plates with different weld positions (eta _d =0.18, eta _d =0.32, eta _d =0.5, eta _d =0.68 and eta _d =0.82) From the bulging experimental results, it can be seen from the figure that the forming results of tailor-welded blanks with different weld positions are different. The most obvious one is that the ultimate bulging height of tailor-welded blanks is different.

In order to study the influence of plate thickness differences on weld seam movement, different plate thickness ratios (η _t =2.0, eta _t =1.67, eta _t =1.5, eta _t =1.3 and eta _t = 1.2) performed finite element simulation on the liquid-filled forming of aluminum alloy differential-thickness tailor-welded plates, and analyzed the weld movement pattern when the bulge height of the tailor-welded plates was 15 mm. Figure 7 shows the influence of different plate thickness ratios on the movement of hydraulic bulge welds in differential-thick tailor-welded plates, and Figure 8 shows the influence of plate thickness ratios on the maximum movement of the welds in differential-thick tailor-welded plates.

The parts of the present invention that are not described in detail are common knowledge to those skilled in the art. The specific embodiments described are only illustrative of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or substitute them in similar ways, without departing from the spirit of the invention or beyond the scope defined by the appended claims.

Claims (8)

1. A testing device for the liquid-filled forming performance and forming rules of tailor-welded blanks, which is characterized by: The test device includes a base (35), a glass plate (34), an O-shaped rubber sealing ring D (33), a cushion block (32), a female mold cover (31), an O-shaped rubber sealing ring A (30), an independent hydraulic System source III, O-shaped rubber sealing ring B (26), backing plate (25), left clamping ring (24), hydraulic cylinder III, O-shaped rubber sealing ring C (22), baffle (21), hydraulic cylinder II. Hydraulic cylinder I, right holder (15), independent hydraulic system source I, independent hydraulic system source II, vacuum pump system and forming law measurement system; Among them, the forming regularity measurement system includes a laser rangefinder, binocular vision system, LED charging light source, data transmission cable, data acquisition system, and computer system. The data of the vacuum pump system is transmitted to the data acquisition system through the data transmission cable; forming The regular measurement system collects the deformation data of the tailor-welded plate during the hydraulic bulging process by collecting the deformation image of the tailor-welded plate through the binocular vision system; The tailor-welded plate includes a thin plate, a thick plate and a weld. The tailor-welded plate is placed on the die sleeve (31), the weld is placed in the center, and a backing plate (24) is added between the thin plate and the left edge ring (24). 25) to ensure the equal thickness of the blanking flange. The backing plate (25) is a semicircular ring backing plate. The thickness of the backing plate (25) is t _h - t _b mm. The grid is printed on the tailor-welded plate. ; The t _b is the thickness of the thin plate, and t _h is the thickness of the thick plate; There is a sealing groove above the base (35) for placing the O-shaped rubber sealing ring D (33), and the glass plate (34) and the gasket (32) are sealed on the base (35); The right side of the cushion block (32) has a vacuum pump system interface combined with the vacuum pump system and a high-pressure liquid outlet channel; There is a sealing groove above the pad (32) for placing the O-shaped rubber sealing ring A (30), and the die sleeve (31) is sealed on the pad (32); The left side of the die sleeve (31) has a liquid filling interface combined with the independent hydraulic system source III and a high-pressure liquid inlet channel. The active radial high-pressure liquid generated by the independent hydraulic system source III enters the tailor-welded plate through the liquid inlet channel. The liquid-filled chamber on the left applies the active radial pressure of the liquid to the left periphery of the tailor-welded blank; The right side of the die sleeve (31) has a liquid filling interface and a high-pressure liquid inlet channel combined with the independent hydraulic system source II. The active radial high-pressure liquid generated by the independent hydraulic system source II enters the tailor-welded plate through the liquid inlet channel. The liquid-filled chamber on the left applies the active radial pressure of the liquid to the outer periphery of the right side of the tailor-welded blank; The left blank holder (24) and the right blank holder (15) form a ring. There is an O-ring seal groove on the outside of the baffle (21) for installing the O-shaped rubber seal C (22). The baffle (21) 21) The upper part is connected to the hydraulic cylinder II, which is used to control the position of the baffle (21); The right side of the right pressure side ring (15) has a liquid filling interface combined with the independent hydraulic system source I and a liquid inlet channel for high-pressure liquid; A forming regularity measurement system is installed in the center of the base (35) and below the high transmittance glass plate (34). 2. A testing device for liquid-filled forming performance and forming rules of tailor-welded plates according to claim 1, characterized by: The left edge ring (24) has a semi-circular ring structure. There is an O-ring seal groove inside the ring, which is used to install the O-shaped rubber seal C (22) and is used for sealing with the baffle (21). , there is an O-ring seal groove on the outside, and the O-shaped rubber seal B (26) is installed. It is used to seal the active radial high-pressure liquid generated by the independent hydraulic system source III. It is directly installed under the left pressure edge ring (24). The top of the backing plate (25) and the top of the left blank holder (24) are directly connected to the hydraulic cylinder III. The hydraulic cylinder III is used to control the size of the blank holder force loaded on the left blank holder (24). 3. A testing device for liquid-filled forming performance and forming rules of tailor-welded plates according to claim 1, characterized by: The right edge ring (15) has a semi-circular ring structure, with an O-ring seal groove on the outside, and an O-ring rubber seal B (26) is installed to seal the active radial high-pressure liquid generated by the independent hydraulic system source II. , the bottom of the right blank holder (15) is directly installed on the top of the tailor-welded plate, and the top of the right blank holder (15) is connected to the hydraulic cylinder I. The hydraulic cylinder I is used to control the blank holder loaded to the right blank holder (15). Magnitude of the force. 4. A testing device for liquid-filled forming performance and forming rules of tailor-welded plates according to claim 1, characterized by: The right side of the cushion block (32) has a liquid outlet port that is combined with the vacuum pump system and a liquid outlet channel for high-pressure liquid. A sealing gasket and a cone surface composite seal are used between the liquid outlet port and the joint of the liquid outlet port. 5. A testing device for liquid-filled forming performance and forming rules of tailor-welded plates according to claim 1, characterized by: The binocular vision system is a non-contact optical measurement system that uses digital image processing technology to obtain the three-dimensional geometry and relative displacement of each point on the surface of the tailor-welded blank during the liquid-filling forming process, so as to realize dynamic monitoring of the liquid-filled forming process of the tailor-welded blank and obtain The real-time weld movement pattern data of the tailor-welded plate and the strain data used to calculate the forming pattern of the tailor-welded plate are uploaded to the data acquisition system in real time through the transmission cable. At the same time, the independent hydraulic system sources I radial hydraulic pressure data, independent hydraulic pressure The data of system source II liquid-filled forming force and independent hydraulic system source III radial hydraulic pressure are uploaded to the data acquisition system in real time through the transmission cable. The laser range finder measures the displacement of the tailor-welded plate during the bulging process in real time. Laser range measurement The instrument data is also uploaded to the data acquisition system in real time through the transmission cable. 6. A testing device for liquid-filled forming performance and forming rules of tailor-welded plates according to claim 1, characterized by: Glass plates require visible light transmittance greater than 90%. 7. A testing device for liquid-filled forming performance and forming rules of tailor-welded plates according to claim 1, characterized by: The left side of the die sleeve (31) has a liquid filling interface combined with the independent hydraulic system source III and a liquid inlet channel for high-pressure liquid. The joint between the liquid filling interface and the liquid inlet channel III uses a sealing gasket and a cone surface composite Type seal. 8. A testing device for liquid-filled forming performance and forming rules of tailor-welded plates according to claim 1, characterized by: The thickness difference between thin plates and thick plates is quantitatively described by the thickness ratio eta _t , which is equal to the ratio of the thickness of thick plates to thin plates: η _t =th _h /t _b In the formula: t _b - thickness of thin plate, t _h - thickness of thick plate, the value range of plate thickness ratio is eta _t ≥ 1, the larger the thickness ratio eta _t is, the greater the difference in plate thickness of differentially thick tailor-welded plates is; The weld position is quantitatively expressed by the chord height ratio eta _d , which is equal to the ratio of the chord height of the thin plate in the bulging zone of the tailor-welded plate to the diameter of the bulging zone: η _d =D _b /D _o In the formula: D _b - the chord height of the thin plate, D ₀ - the diameter of the bulging area of the tailor-welded plate, the value range of the chord-to-height ratio is 0η≤ _d ≤1, when η _d =1, it means that the tailor-welded plate is completely thin plate, and When eta _d =0, it means that the tailor-welded blank is completely thick. As the chord-to-height ratio decreases, the proportion of thin plates in the tailor-welded blank decreases.