Fluid medium-activated uniaxial biaxial stretch forming apparatus and method of use

Abstract

The application is suitable for the technical field of metal material tensile test, and provides a uniaxial bidirectional tensile forming device with fluid medium and a using method thereof.The device is composed of an outer cylinder, a piston assembly, a fluid medium, a large fluid cavity, a small fluid cavity and a supply system.The outer cylinder is connected with the supply system through a stop valve.The sliding piston assembly is composed of a large piston, a sealing ring I, a piston cylinder, a sealing ring II, a support cylinder, a pull rod I, a test piece, a pull rod II, a thrust bearing, a tensile piston, a sealing ring III, a connecting screw and a sealing ring IV.The forming method based on the device realizes bidirectional tensile deformation of the test piece by using volume change of the fluid medium.The method includes the steps of installing the test piece, injecting the fluid medium, tensile testing the test piece, unloading and taking out the test piece.The application can realize bidirectional deep drawing of the test piece, realize uniform deformation, and can test mechanical properties of the test piece in different fluid media.

Description

Technical Field

[0001] This invention belongs to the field of tensile testing technology for metallic materials, and particularly relates to a uniaxial biaxial tensile forming device under the action of a fluid medium and its usage method. Background Technology

[0002] The research, development, and application of novel materials have always been a hot topic in contemporary research. New high-performance materials have played a driving role in promoting the high-tech modernization of countries worldwide. To promote the development of manufacturing, and to facilitate the rapid development of the military and national economies, exploring high-strength and high-toughness materials has become a viable option. Tensile testing is the primary method for detecting the basic mechanical properties of materials.

[0003] Existing tensile testing apparatuses monitor the potential changes of hollow rod-shaped specimens in real time using a potential testing component. This establishes a correlation between hydrogen content in the material under sulfuric acid corrosion with an inhibitor and under cathodic potential hydrogen charging, allowing for a relatively short time to obtain the relationship between hydrogen-induced cracking sensitivity, potential, and hydrogen content. By setting up a bidirectional threaded rod, a moving block, and a graduated scale, the initial position is recorded. Rotating the bidirectional threaded rod moves the moving block to both sides, stretching the metal material. When the metal breaks, the ending position is recorded, and the elongation is calculated from the distance difference. However, the use of unidirectional tension during the test easily leads to uneven deformation of the material. Furthermore, existing tensile testing apparatuses struggle to perform online testing under different fluid media conditions or tensile forming tests requiring atmospheric protection for certain materials. Adding additional testing equipment or offline processing significantly prolongs the testing process, reducing efficiency and cycle time. Therefore, testing specimens with special requirements has become a major issue in materials science research, necessitating the development of specialized instruments for this purpose. Summary of the Invention

[0004] The purpose of this invention is to provide a uniaxial biaxial stretching forming apparatus and its method of use under the action of a fluid medium, in order to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A uniaxial biaxial stretching forming apparatus under the action of a fluid medium includes an outer cylinder, a piston assembly, a fluid medium, a large fluid cavity, a small fluid cavity, and a supply system. The outer cylinder is provided with an injection hole and is connected to the supply system through a shut-off valve. The piston assembly includes a first sealing ring, a piston cylinder, a second sealing ring, a support cylinder, a test piece, a thrust bearing, a tension piston, a third sealing ring, a connecting screw, and a fourth sealing ring, as well as: A large piston, wherein a limiting block is fixedly connected to the top of the large piston, and at least one through hole is provided inside the top of the large piston; Tie rod one, wherein the tie rod one is connected to the large piston by welding or thread; Tie rod 2, with limit block 2 fixedly connected to the top of the flange of tie rod 2, and threaded hole opened at the bottom of the flange of tie rod 2, the threaded hole being threadedly connected to the connecting screw, and connecting the thrust bearing, sealing ring 3 and tension piston; The large fluid cavity is composed of the bottom of the large piston, a sealing ring, and the inner wall of the outer cylinder. The small fluid cavity consists of the top of the large piston, the inner wall of the piston cylinder, the second sealing ring, the bottom of the tension piston, the third sealing ring, the connecting screw, and the fourth sealing ring. The bottom of the piston cylinder is threadedly connected to the large piston, and the bottom of the piston cylinder is sealed and fixed to the large piston by means of a fixed installation of sealing ring two; The side wall of the large piston is slidably connected to the outer cylinder, and the side wall of the large piston is sealed to the outer cylinder by a fixedly installed sealing ring. The side wall of the stretching piston is slidably connected to the inner side wall of the piston cylinder, and the side wall of the stretching piston is sealed to the piston cylinder by fixing and installing sealing ring four. The support cylinder is installed between the large piston and the tension piston to support and restrict the rotation of the tension piston. The side wall of the support cylinder is provided with symmetrically arranged openings, the size of which is larger than the size of the test piece. The two ends of the support cylinder are respectively provided with a first slot and a second slot, which are respectively embedded in a first limiting block and a second limiting block.

[0006] The test piece is connected to the large piston in the small fluid cavity via a pin or thread and a pull rod one. The test piece is also connected to the tension piston in the small fluid cavity via a pin or thread and a pull rod two.

[0007] There are at least two pins.

[0008] The fluid medium includes hydraulic oil, pure water, salt water, alkaline water, seawater, air, nitrogen, oxygen, and methane.

[0009] The outer cylinder is placed vertically or horizontally.

[0010] A method of using a uniaxial biaxial stretching forming apparatus under fluid medium action includes the following steps: Step 1: Install the test specimen Place the support cylinder between the large piston and the second tie rod. The first and second slots on the top of the support cylinder are respectively embedded in the first and second limit blocks. Connect the test piece between the first and second tie rods using a pin or thread. At the same time, place the thrust bearing, tension piston, third seal ring, connecting screw, and fourth seal ring on the top of the second tie rod. Rotate the connecting screw to make the connecting screw threadedly connected to the second tie rod, but do not tighten it. At this time, press down the piston cylinder. When the piston cylinder contacts the thread of the large piston, fix the large piston. Then rotate the piston cylinder to make the piston cylinder threadedly connected to the large piston and press the second seal ring. Tighten the connecting screw and press the third seal ring to achieve sealing and fixation. The test piece is now installed. Step 2: Inject fluid medium Open the shut-off valve, and the supply system will fill the large fluid chamber with fluid medium through the injection hole. At the same time, the fluid medium will enter the piston cylinder through the through hole on the large piston until the fluid fills the large fluid chamber and the small fluid chamber. Then close the shut-off valve. Step 3, Tensile test specimen By pressing down the piston cylinder with external force, the large piston moves downward and forces the fluid medium in the large fluid cavity to flow into the small fluid cavity. The fluid medium in the small fluid cavity acts on the tensile piston, forcing the tensile piston to move upward and stretch the test piece, thus achieving tensile deformation of the test piece. Step 4: Unload and remove the test piece. Remove the external load, open the shut-off valve, connect the supply system, and continue to increase the system pressure. At this time, fix the position of the tension piston. As the system pressure increases, it lifts the piston cylinder and the large piston assembly. When the entire piston cylinder is exposed, close the shut-off valve and fix the position of the piston cylinder and the large piston assembly. At this time, open the shut-off valve to allow the fluid medium in the large fluid chamber to flow out, and then allow the fluid medium in the small fluid chamber to flow back into the large fluid chamber until the fluid stops flowing. Then rotate the piston cylinder, remove the tension piston, and take out the remaining test piece from the support cylinder.

[0011] Furthermore, the thrust bearing is used to ensure that the rotational movement of the piston cylinder driving the tension piston during installation will not cause the pull rod to rotate.

[0012] Furthermore, the test specimens include steel, aluminum and its alloys, magnesium and its alloys, copper and its alloys, and titanium and its alloys.

[0013] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention utilizes the properties of hydraulic or pneumatic transmission. With a constant volume, force is applied and material deformation is achieved by changing the volume ratio. The external force acting on the piston cylinder is decomposed into a downward force and an upward force on the tensile test specimen. The mechanical property changes of the test specimen under tensile deformation are detected. Furthermore, the test specimen can be subjected to cyclic stress by changing the pressure, which is used for material fatigue testing.

[0014] 2. This invention utilizes the multidirectional nature of pressure transmission in fluid media to achieve flexible and directional loading by converting pressure into tensile force, and it is a uniaxial bidirectional tensile loading, resulting in more uniform material deformation.

[0015] 3. By using the same fluid medium and sample storage medium, this invention avoids abnormalities in material testing data caused by sample contamination, thus preventing the material properties from being accurately reflected. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the present invention, wherein: Figure 1 a is a schematic diagram of a uniaxial biaxial stretching forming device under fluid medium action when there is no hydraulic medium. Figure 1 b is a schematic diagram of a uniaxial biaxial stretching forming device under the action of a fluid medium when there is a hydraulic medium.

[0017] Figure 2 This is a schematic diagram of the piston assembly in this invention.

[0018] Figure 3 This is a schematic diagram of a uniaxial biaxial stretching forming device under the action of a fluid medium.

[0019] Figure 4 This is a schematic diagram of the support cylinder in this invention.

[0020] Figure 5 This is a schematic diagram of the second pull rod in this invention.

[0021] Figure 6 This is a schematic diagram of the components consisting of the tension piston, the second tie rod, the thrust bearing, and the fourth sealing ring in this invention.

[0022] Figure 7 This is a schematic diagram showing the positions of the limiting block and the through hole in this invention.

[0023] Figure 8 This is a schematic diagram of the connection between the dumbbell-shaped test piece with threads on both ends and the pull rod one and pull rod two in this invention.

[0024] Figure 9 This is a schematic diagram of the forming process of the test piece in this invention, wherein: Figure 9 a is a schematic diagram of the process of installing the test piece with the support cylinder placed between the large piston and the second tie rod; Figure 9 b is a schematic diagram of placing the thrust bearing, tension piston, sealing ring three, connecting screw and sealing ring four on top of the pull rod two, rotating the connecting screw to achieve a threaded connection between the connecting screw and the pull rod two, but without tightening it; Figure 9 c is a schematic diagram of the piston cylinder being fitted into the piston assembly; Figure 9 d is a schematic diagram of the piston cylinder fully inserted into the piston assembly and tightened. Figure 9 e is a schematic diagram of the piston assembly being installed into the outer cylinder; Figure 9 f is a schematic diagram of the piston assembly fully installed in the outer cylinder.

[0025] In the diagram: 1-Outer cylinder, 2-Piston assembly, 3-Fluid medium, 4-Large fluid cavity, 5-Small fluid cavity, 6-Supply system, 101-Injection hole, 102-Stop valve, 201-Large piston, 202-Sealing ring one, 203-Piston cylinder, 204-Sealing ring two, 205-Support cylinder, 206-Tie rod one, 207-Pin, 208-Test piece, 209-Tie rod two, 210-Thrust bearing, 211-Tension piston, 212-Sealing ring three, 213-Connecting screw, 214-Sealing ring four, 2011-Limiting block one, 2012-Through hole, 2091-Limiting block two, 2092-Threaded hole, 2051-Opening, 2052-Slot one, 2053-Slot two. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0027] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0028] like Figures 1-9 As shown, a uniaxial biaxial stretching forming apparatus for fluid medium action provided in one embodiment of the present invention includes an outer cylinder 1, a piston assembly 2, a fluid medium 3, a large fluid cavity 4, a small fluid cavity 5, and a supply system 6, characterized in that: The outer cylinder 1 is provided with an injection hole 101 and is connected to the supply system 6 through a shut-off valve 102. The piston assembly 2 includes a first sealing ring 202, a piston cylinder 203, a second sealing ring 204, a support cylinder 205, a test piece 208, a thrust bearing 210, a tension piston 211, a third sealing ring 212, a connecting screw 213, and a fourth sealing ring 214, and: A large piston 201, the top of which is fixedly connected to a limiting block 2011, and at least one through hole 2012 is provided in the top of the large piston 201. Tie rod 206, wherein the tie rod 206 is connected to the large piston 201 by welding or thread; Tie rod 209, the top of the flange of tie rod 209 is fixedly connected to limit block 2091, the bottom of the flange of tie rod 209 is provided with threaded hole 2092, the threaded hole 2092 is threadedly connected to connecting screw 213, and the thrust bearing 210, sealing ring 3 212 and tension piston 211 are connected. The large fluid cavity 4 is composed of the bottom of the large piston 201, the sealing ring 202, and the inner wall of the outer cylinder 1; The small fluid cavity 5 is composed of the top of the large piston 201, the inner wall of the piston cylinder 203, the second sealing ring 204, the bottom of the tension piston 211, the third sealing ring 212, the connecting screw 213, and the fourth sealing ring 214. The bottom of the piston cylinder 203 is threadedly connected to the large piston 201, and the bottom of the piston cylinder 203 is sealed and fixed to the large piston 201 by means of a fixed installation of a sealing ring 204. The side wall of the large piston 201 is slidably connected to the outer cylinder 1, and the side wall of the large piston 201 is sealed to the outer cylinder 1 by means of a fixedly installed sealing ring 202. The side wall of the stretching piston 211 is slidably connected to the inner side wall of the piston cylinder 203, and the side wall of the stretching piston 211 is sealed to the piston cylinder 203 by fixing and installing sealing ring 214. The support cylinder 205 is installed between the large piston 201 and the tension piston 211 to support and restrict the rotation of the tension piston 211. The side wall of the support cylinder 205 is provided with symmetrically arranged openings 2051. The size of the openings 2051 is larger than the size of the test piece 208. The two ends of the support cylinder 205 are respectively provided with a first slot 2052 and a second slot 2053. The first slot 2052 and the second slot 2053 are respectively embedded in the first limiting block 2011 and the second limiting block 2091.

[0029] In a preferred embodiment of the invention, when an external force acts on the top of the piston cylinder 203, the fluid medium 3 in the large fluid cavity 4 continues to enter the piston cylinder 203 through the through hole 2012 and compresses and stretches the piston 211 to move upward.

[0030] Figure 4 The diagram shows a support cylinder 205. During the forming process, the support cylinder 205 has symmetrically arranged openings 2051 on its side wall. The size of the openings 2051 is larger than the size of the test piece 208. The two ends of the support cylinder 205 are respectively provided with a first slot 2052 and a second slot 2053. The first slot 2052 and the second slot 2053 are respectively embedded in the first limiting block 2011 and the second limiting block 2091.

[0031] Figure 5 A structural schematic diagram of tie rod 209.Figure 6 The diagram shows the assembly consisting of the stretch piston 211, the second tie rod 209, the thrust bearing 210, and the fourth sealing ring 214. During the forming process, the test piece 208 is connected by the pin 207, and the connecting screw 213 is threaded to the threaded hole 2092 on the second tie rod 209, but not tightened. At this time, the piston cylinder 203 is pressed down, and after the piston cylinder 203 is connected to the thread of the large piston 201 and tightened, the connecting screw 213 is tightened to press the third sealing ring 212.

[0032] Figure 7 The diagram shows the positions of the limiting block 2011 and the through hole 2012. During the forming process, the first tie rod 206 and the second tie rod 209 are connected to the test piece 208 through the pin 207. The limiting block 2011 on the large piston 201 is embedded in the slot of the support cylinder 205. At the same time, during the forming process, the fluid medium 3 enters the piston cylinder 203 through the through hole 2012 and flows into the small fluid cavity 5.

[0033] Figure 8 In another embodiment of the connection between the test piece 208 and the first pull rod 206 and the second pull rod 209 of the present invention, referring to 8a and 8b, the test piece 208 is a dumbbell shape with threads on both ends. Threaded connection holes are provided in both the first pull rod 206 and the second pull rod 209. The threaded connection holes are adapted to the threads at the ends of the test piece 208. The test piece 208 is threadedly connected to the first pull rod 206 and to the second pull rod 209, thereby completing the installation of the dumbbell-shaped test piece 208 with threads on both ends.

[0034] Figure 9 This is a schematic diagram of the test piece during the forming process: Figure 9 a is a schematic diagram of the process of placing the support cylinder 205 between the large piston 201 and the second pull rod 209, with the first slot 2052 and the second slot 2053 at the end of the support cylinder 205 respectively embedded in the first limit block 2011 and the second limit block 2091, and then connecting the test piece 208 between the first pull rod 206 and the second pull rod 209 through the pin 207; Figure 9 b is a schematic diagram of the process of placing the thrust bearing 210, the tension piston 211, the sealing ring three 212, the connecting screw 213 and the sealing ring four 214 on the top of the pull rod two 209, so that the connecting screw 213 and the pull rod two 209 are threadedly connected, but not tightened. Figure 9 c is the pressurized piston cylinder 203. When the piston cylinder 203 is in threaded contact with the large piston 201, the large piston 201 is fixed and the piston cylinder 203 is rotated so that the piston cylinder 203 is threadedly connected to the large piston 201 and the sealing ring 204 is pressed. Figure 9d is a schematic diagram of the process of tightening the connecting screw 213 to press the sealing ring 212 to achieve sealing and fixation, and the test piece 208 is installed. Figure 9 e is a schematic diagram of the process of installing piston assembly 2 into outer cylinder 1 and making sealing ring 214 completely enter outer cylinder 1, and then introducing fluid medium 3. Figure 9 f is a schematic diagram of the process in which the piston assembly 2 is fully installed into the outer cylinder 1 and acts on the tensile piston 211 through the fluid medium 3, causing the test piece 208 to deform.

[0035] like Figure 1 and Figure 2 As shown, in a preferred embodiment of the present invention, the test piece 208 is connected to the large piston 201 in the small fluid cavity 5 via a pin 207 and a pull rod 206, and the test piece 208 is connected to the tension piston 211 in the small fluid cavity 5 via a pin 207 and a pull rod 209.

[0036] like Figure 2 As shown, in a preferred embodiment of the present invention, at least two pins 207 are provided.

[0037] like Figure 1 As shown, in a preferred embodiment of the present invention, the fluid medium 3 includes hydraulic oil, pure water, salt water, alkaline water, seawater, air, nitrogen, oxygen, and inert gases such as methane.

[0038] like Figure 1 As shown, in a preferred embodiment of the present invention, the outer cylinder 1 is placed vertically or horizontally.

[0039] A method of using a uniaxial biaxial stretching forming apparatus under fluid medium action includes the following steps: Step 1: Install test piece 208 The support cylinder 205 is placed between the large piston 201 and the second pull rod 209. The first slot 2052 and the second slot 2053 on the top of the support cylinder 205 are respectively embedded in the first limit block 2011 and the second limit block 2091. The test piece 208 is connected between the first pull rod 206 and the second pull rod 209 by the pin 207. At the same time, the thrust bearing 201, the tension piston 211, the third sealing ring 212, the connecting screw 213, and the fourth sealing ring 214 are placed on the second pull rod 209. At the top, rotate the connecting screw 213 to make the connecting screw 213 and the pull rod 209 threadedly connected, but not tightened. At this time, press down the piston cylinder 203. When the piston cylinder 203 and the large piston 201 are in threaded contact, fix the large piston 201. Then rotate the piston cylinder 203 to make the piston cylinder 203 and the large piston 201 threadedly connected, and press the sealing ring 204. Tighten the connecting screw 213 and press the sealing ring 212 to achieve sealing and fixation. The test piece 208 is installed. Step 2: Inject fluid medium 3 Open the shut-off valve 102, and the supply system 6 fills the large fluid chamber 4 with fluid medium 3 through the injection hole 101. At the same time, the fluid medium 3 enters the piston cylinder 203 through the through hole 2012 on the large piston 201 until the fluid fills the large fluid chamber 4 and the small fluid chamber 5. Then close the shut-off valve 102. Step 3, Tensile test specimen 208 By pressing down the piston cylinder 203 with external force, the large piston 201 moves downward and forces the fluid medium 3 in the large fluid cavity 4 to flow into the small fluid cavity 5. The fluid medium 3 in the small fluid cavity 5 acts on the tensile piston 211, forcing the tensile piston 211 to move upward to stretch the test piece 208, thereby achieving the tensile deformation of the test piece 208. Step 4: Unload and remove test piece 208. Remove the external load, open the shut-off valve 102, connect the supply system 6, and continue to increase the system pressure. At this time, fix the position of the tension piston 211. As the system pressure increases, it lifts the piston cylinder 203 and the large piston 201 assembly. When the piston cylinder 203 is fully exposed, close the shut-off valve 102 and fix the position of the piston cylinder 203 and the large piston 201 assembly. At this time, open the shut-off valve 102 to allow the fluid medium 3 in the large fluid chamber 4 to flow out, and then allow the fluid medium 3 in the small fluid chamber 5 to flow back into the large fluid chamber 4 until the fluid stops flowing. Then rotate the piston cylinder 203, remove the tension piston 211, and take out the remaining test piece 208 from the support cylinder 205.

[0040] In this embodiment of the invention, the method can detect the changes in the mechanical properties of the test specimen 208 material under the influence of different fluid media 3.

[0041] like Figure 2As shown, in a preferred embodiment of the present invention, the thrust bearing 210 is used to ensure that the rotational movement of the piston cylinder 203 driving the tension piston 211 during installation will not cause the pull rod 209 to rotate.

[0042] like Figure 2 Figure 2 As shown, in a preferred embodiment of the present invention, the test piece 208 includes steel, aluminum and its alloys, magnesium and its alloys, copper and its alloys, and titanium and its alloys, etc.

[0043] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A uniaxial biaxial stretching forming apparatus under the action of a fluid medium, comprising an outer cylinder, a piston assembly, a fluid medium, a large fluid cavity, a small fluid cavity, and a supply system, characterized in that: The outer cylinder is provided with an injection hole and is connected to the supply system through a shut-off valve. The piston assembly includes a first sealing ring, a piston cylinder, a second sealing ring, a support cylinder, a test piece, a thrust bearing, a tension piston, a third sealing ring, a connecting screw, and a fourth sealing ring, as well as: A large piston, wherein a limiting block is fixedly connected to the top of the large piston, and at least one through hole is provided inside the top of the large piston; Tie rod one, wherein the tie rod one is connected to the large piston by welding or thread; Tie rod 2, with limit block 2 fixedly connected to the top of the flange of tie rod 2, and threaded hole opened at the bottom of the flange of tie rod 2, the threaded hole being threadedly connected to the connecting screw, and connecting the thrust bearing, sealing ring 3 and tension piston; The large fluid cavity is composed of the bottom of the large piston, a sealing ring, and the inner wall of the outer cylinder. The small fluid cavity consists of the top of the large piston, the inner wall of the piston cylinder, the second sealing ring, the bottom of the tension piston, the third sealing ring, the connecting screw, and the fourth sealing ring. The bottom of the piston cylinder is threadedly connected to the large piston, and the bottom of the piston cylinder is sealed and fixed to the large piston by means of a fixed installation of sealing ring two; The side wall of the large piston is slidably connected to the outer cylinder, and the side wall of the large piston is sealed to the outer cylinder by a fixedly installed sealing ring. The side wall of the stretching piston is slidably connected to the inner side wall of the piston cylinder, and the side wall of the stretching piston is sealed to the piston cylinder by fixing and installing sealing ring four. The support cylinder is installed between the large piston and the tension piston to support and restrict the rotation of the tension piston. The side wall of the support cylinder is provided with symmetrically arranged openings, the size of which is larger than the size of the test piece. The two ends of the support cylinder are respectively provided with a first slot and a second slot, which are respectively embedded in a first limiting block and a second limiting block. The test piece is connected to the large piston in the small fluid cavity via a pin or thread and a pull rod one. The test piece is also connected to the tension piston in the small fluid cavity via a pin or thread and a pull rod two.

2. The uniaxial biaxial stretching forming apparatus under fluid medium action according to claim 1, characterized in that, There are at least two pins.

3. The uniaxial biaxial stretching forming apparatus under fluid medium action according to claim 1, characterized in that, The fluid medium includes hydraulic oil, pure water, salt water, alkaline water, seawater, air, nitrogen, oxygen, and methane.

4. The uniaxial biaxial stretching forming apparatus under fluid medium action according to claim 1, characterized in that, The outer cylinder is placed vertically or horizontally.

5. A method of using a uniaxial biaxial stretching forming apparatus under the action of a fluid medium according to any one of claims 1-4, characterized in that, Includes the following steps: Step 1: Install the test specimen Place the support cylinder between the large piston and the second tie rod. The first and second slots on the top of the support cylinder are respectively embedded in the first and second limit blocks. Connect the test piece between the first and second tie rods using a pin or thread. At the same time, place the thrust bearing, tension piston, third seal ring, connecting screw, and fourth seal ring on the top of the second tie rod. Rotate the connecting screw to make the connecting screw threadedly connected to the second tie rod, but do not tighten it. At this time, press down the piston cylinder. When the piston cylinder contacts the thread of the large piston, fix the large piston. Then rotate the piston cylinder to make the piston cylinder threadedly connected to the large piston and press the second seal ring. Tighten the connecting screw and press the third seal ring to achieve sealing and fixation. The test piece is now installed. Step 2: Inject fluid medium Open the shut-off valve, and the supply system will fill the large fluid chamber with fluid medium through the injection hole. At the same time, the fluid medium will enter the piston cylinder through the through hole on the large piston until the fluid fills the large fluid chamber and the small fluid chamber. Then close the shut-off valve. Step 3, Tensile test specimen By pressing down the piston cylinder with external force, the large piston moves downward and forces the fluid medium in the large fluid cavity to flow into the small fluid cavity. The fluid medium in the small fluid cavity acts on the tensile piston, forcing the tensile piston to move upward and stretch the test piece, thus achieving tensile deformation of the test piece. Step 4: Unload and remove the test piece. Remove the external load, open the shut-off valve, connect the supply system, and continue to increase the system pressure. At this time, fix the position of the tension piston. As the system pressure increases, it lifts the piston cylinder and the large piston assembly. When the entire piston cylinder is exposed, close the shut-off valve and fix the position of the piston cylinder and the large piston assembly. At this time, open the shut-off valve to allow the fluid medium in the large fluid chamber to flow out, and then allow the fluid medium in the small fluid chamber to flow back into the large fluid chamber until the fluid stops flowing. Then rotate the piston cylinder, remove the tension piston, and take out the remaining test piece from the support cylinder.

6. The method of using the uniaxial biaxial stretching forming apparatus under fluid medium action according to claim 5, characterized in that, The thrust bearing is used to ensure that the rotational movement of the piston cylinder driving the tension piston during installation will not cause the pull rod to rotate.

7. The method of using the uniaxial biaxial stretching forming apparatus under fluid medium action according to claim 5, characterized in that, The test specimens include steel, aluminum and its alloys, magnesium and its alloys, copper and its alloys, and titanium and its alloys.

Images