Rapid ejection off-target device for material dynamic impact test

Abstract

The invention relates to the technical field of material impact tests, and provides a material dynamic impact test rapid ejection off-target device which comprises a hydraulic cylinder connected with a hydraulic power assembly for realizing oil supply and oil return; the elastic energy storage element is mounted on the cylinder body of the hydraulic cylinder; the tool bottom plate is used for supporting a test piece, is fixedly connected with a piston rod of the hydraulic cylinder and enables the elastic energy storage element to be compressed to store force under the thrust action of the piston rod; the impact head is connected to a loading component of the material testing machine; and a position detection element. According to the position detection element, when the impact head is loaded to a target position, the hydraulic power assembly obtains an off-target signal, the hydraulic cylinder is unloaded, the tool bottom plate and the piston rod of the hydraulic cylinder generate large acceleration under the action of the elastic energy storage component and eject downwards instantaneously, rapid off-target of a test piece is achieved, the test piece is disengaged from stress, and the test piece is accurately detected. Therefore, the dynamic fracture toughness of the cracks of the metal material under the dynamic impact high strain rate is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of material impact testing, in particular to a rapid ejection and miss-target device for a material dynamic impact test. Background Art

[0002] The impact performance of metal materials is an important indicator that requires attention. Metal materials in structures such as nuclear power pipelines and reactor pressure vessels are subject to dynamic impact loads such as vibration and earthquake, and are easily cracked by stress corrosion, chemical corrosion and other reasons. Under dynamic impact and high strain rates, cracks are easy to initiate and expand, causing damage, failure or even breakage of components. Therefore, for metal materials in the nuclear power field, when selecting materials and designing structures, it is necessary not only to consider quasi-static design criteria, but also the influence of dynamic impact and high strain rates on metal materials and components.

[0003] At present, the Charpy impact method is often used to assess the impact properties of materials and measure the impact toughness of materials. Its scope of application is limited to testing the impact resistance of the passivation notch of the material, cold brittle tendency, quality after hot processing and metallurgical quality. In addition, the Charpy impact test does not pre-form cracks and cannot reflect the toughness and brittleness characteristics of the material cracks under impact. In existing material testing machines, the impact load provided at a high loading rate will break the tested metal material, and the dynamic fracture toughness of the metal material crack under dynamic impact and high strain rate cannot be obtained. Therefore, how to provide a device that allows the tested metal material to stop being stressed instantaneously for a specific time after being impacted by the high loading rate of the material testing machine (that is, when the test piece is torn to a certain extent, it is instantly separated from the stress) to obtain the dynamic fracture toughness of the metal material crack under dynamic impact and high strain rate is a problem that needs to be solved in this field. Summary of the Invention

[0004] The purpose of the present invention is to provide a rapid ejection and miss-target device for dynamic impact testing of materials, so as to solve the defect that existing material testing machines cannot achieve the instantaneous cessation of stress on metal materials within a specific time after being impacted by a high loading rate.

[0005] The present invention is achieved through the following technical solutions:

[0006] A rapid ejection and miss-target device for a material dynamic impact test, comprising:

[0007] A hydraulic cylinder connected to a hydraulic power assembly for oil supply and oil return;

[0008] An elastic energy storage element, which is mounted on the cylinder body of the hydraulic cylinder;

[0009] A tooling base plate used to support the test piece, which is fixedly connected to the piston rod of the hydraulic cylinder and compresses the elastic energy storage element to store energy under the thrust of the piston rod;

[0010] The impact head is connected to the loading component of the material testing machine;

[0011] And a position detection element is used to send an off-target signal when the impact head is loaded to the target position. Then the hydraulic cylinder is unloaded, and the tooling base plate is ejected downward under the action of the elastic energy storage element, so that the test piece is freed from the force.

[0012] Optionally, the position detection element is a travel switch, the travel switch and the cylinder body of the hydraulic cylinder are relatively fixed in position, and the impact head is connected to a touch piece for triggering the travel switch.

[0013] Optionally, the touch member is a plate-shaped structure, one end of the touch member is rotatably connected to the impact head via a pin shaft, and the pin shaft is sleeved with a torsion spring to keep the touch member in a downward rotation tendency, and the impact head is provided with a limit member below the touch member for limiting the downward rotation of the touch member.

[0014] Optionally, a mounting bracket for mounting the elastic energy storage element is provided on the top of the cylinder body of the hydraulic cylinder, and the travel switch is mounted on a connecting bracket, which is connected to the mounting bracket.

[0015] Optionally, the mounting bracket includes a mounting block and two support rods, the support rods are fixedly connected to the top of the cylinder body of the hydraulic cylinder, the mounting block is connected to the upper ends of the two support rods, the upper end of the elastic energy storage element is fixedly connected to the mounting block, and the lower end of the elastic energy storage element is against the tooling base plate; the connecting bracket is sleeved on the support rods, and the upper and lower sides are locked by nuts.

[0016] Optionally, two support seats are provided at intervals on the top of the tooling base plate for supporting the ends of the test piece.

[0017] Optionally, a slide is fixedly provided on the top of the tooling base plate, and the two support seats are slidably provided on the top of the slide. Connecting arms are fixedly connected on both sides of the support seat, and locking screws for tightening the slide are connected to the connecting arms, and a limiting step is provided on the slide for limiting the downward displacement of the locking screw.

[0018] Optionally, the elastic energy storage element is a nitrogen spring.

[0019] Optionally, the hydraulic power assembly includes an oil tank, a servo motor, an oil pump, a reversing valve and a logic valve; the servo motor drives the oil pump to supply oil to the lower chamber of the hydraulic cylinder through the oil supply line, so that the piston rod of the hydraulic cylinder extends upward; the lower chamber of the hydraulic cylinder is connected to the oil tank through the return oil line via the logic valve and the reversing valve, and the reversing valve reverses after receiving the off-target signal, controls the logic valve to relieve pressure, and allows the hydraulic oil in the lower chamber of the hydraulic cylinder to flow back to the oil tank through the logic valve.

[0020] Optionally, the hydraulic power assembly further includes an overflow valve, which is arranged on an overflow pipeline, one end of the overflow pipeline is connected to the oil tank, and the other end of the overflow pipeline is connected to the oil supply pipeline.

[0021] The technical solution of the present invention has at least the following advantages and beneficial effects: in the present invention, after the piston rod of the hydraulic cylinder is extended, the elastic energy storage element is in an energy storage compression state under the extrusion of the tooling base plate. During the test, the impact head impacts downward at a constant speed, applying a load to the specimen placed on the tooling base plate. After loading to the target position, the position detection element detects the position of the impact head, the hydraulic power assembly obtains an off-target signal, the hydraulic cylinder is unloaded, and at the same time the elastic energy storage element releases energy. The tooling base plate and the piston rod of the hydraulic cylinder generate a large acceleration under the action of the elastic energy storage component, and are instantly ejected downward, achieving rapid off-target of the specimen, so that the specimen is free from stress, thereby obtaining the dynamic fracture toughness of the metal material crack under dynamic impact and high strain rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic structural diagram of a rapid ejection and miss-target device for a material dynamic impact test provided by the present invention;

[0023] Figure 2 Schematic diagram of the installation structure of the elastic energy storage element;

[0024] Figure 3 Schematic diagram of the installation structure of the support base;

[0025] Figure 4 Schematic diagram of the structure of the impact head;

[0026] Figure 5 It is the main view of the impact head;

[0027] Figure 6 This is a schematic diagram of the installation structure of the position detection element;

[0028] Figure 7 This is the working principle diagram of the hydraulic power component;

[0029] Figure markings: 1-hydraulic cylinder, 101-piston rod, 102-cylinder body, 2-elastic energy storage element, 3-impact head, 4-position detection element, 5-mounting frame, 501-mounting block, 502-support rod, 6-connecting bracket, 7-touch member, 8-limiting member, 9-tooling base plate, 10-slide seat, 11-support seat, 12-connecting arm, 13-locking screw, 14-oil tank, 15-servo motor, 16-oil pump, 17-reversing valve, 18-logic valve, 19-overflow valve, 20-check valve, 21-filter, 22-temperature sensor, 23-pressure sensor, 24-test piece. DETAILED DESCRIPTION

[0030] refer to Figure 1 , a fast ejection off-target device for dynamic impact test of materials, comprising a hydraulic cylinder 1, an elastic energy storage element 2, a tooling base plate 9, an impact head 3 and a position detection element 4. The off-target device provided by the present invention is used in conjunction with an existing material testing machine. There is no restriction on the specific type of material testing machine, as long as it can apply a compressive load to the material. As an option, for example, this embodiment adopts an Instron VHS 160 / 100-20 high-speed material testing machine, that is, the Instron brand VHS series, a high-speed material testing machine with a model of 160 / 100-20. In actual application, a material testing machine (not shown) is used as a basic stand, and the hydraulic cylinder 1 is used as the main body. The various components are installed and integrated into a whole, which can be quickly installed on the base of the material testing machine. A force sensor can be set at the bottom of the hydraulic cylinder 1 to facilitate the detection of impact loads.

[0031] The hydraulic cylinder 1 is connected to a hydraulic power assembly for oil supply and oil return, that is, the hydraulic cylinder 1 realizes loading and unloading of hydraulic oil through the hydraulic power assembly. The elastic energy storage element 2 is installed on the cylinder body 102 of the hydraulic cylinder 1, and the tooling base 9 is fixedly connected to the piston rod 101 of the hydraulic cylinder 1. Under the thrust of the piston rod 101, the tooling base 9 compresses the elastic energy storage element 2 to store energy. At the same time, the tooling base 9 is used to support the specimen 24. The impact head 3 is connected to the loading component of the material testing machine. During the test, the impact head 3 impacts downward at a constant speed to apply a load to the specimen 24 placed on the tooling base 9. After loading to the target, the position detection element 4 detects the position of the impact head 3, the hydraulic power assembly obtains an off-target signal, the hydraulic cylinder 1 is unloaded, and the elastic energy storage element 2 releases energy at the same time. The tooling base 9 and the piston rod 101 of the hydraulic cylinder 1 generate a large acceleration under the action of the elastic energy storage component, and are instantly ejected downward, achieving a rapid off-target of the specimen 24, so that the specimen 24 is free from stress, thereby obtaining the dynamic fracture toughness of the metal material crack under dynamic impact and high strain rate.

[0032] refer to Figure 2 , two elastic energy storage elements 2 are symmetrically arranged to ensure uniform force. As an option, the elastic energy storage element 2 of this embodiment is a nitrogen spring. It should be understood that the nitrogen spring uses high-pressure nitrogen as the medium, has a high compression ratio, high energy storage density, and fast response, which facilitates the rapid off-target of the test piece 24. In addition, the nitrogen spring has the advantages of constant elastic force, small size, long life (over 1 million times), strong adjustability, and flexible installation. In other embodiments, the nitrogen spring can of course be replaced by other elements, such as a hydraulic spring.

[0033] As an option, in this embodiment, the position detection element 4 is a travel switch (for example, a travel switch of the brand Omron, model D4MC-5020), that is, a mechanical trigger is used to detect the position of the impact head 3. In other embodiments, of course, the position of the impact head 3 can also be detected by an electronic trigger, for example, the position detection element 4 is a displacement sensor.

[0034] refer to Figure 1 as well as Figure 4-Figure 6 On the basis of selecting a travel switch as the position detection element 4, the travel switch and the cylinder body 102 of the hydraulic cylinder 1 are relatively fixed in position. As an option, a mounting bracket 5 for mounting the elastic energy storage element 2 is provided on the top of the cylinder body 102 of the hydraulic cylinder 1. The travel switch is mounted on the connecting bracket 6, and the connecting bracket 6 is connected to the mounting bracket 5. Furthermore, the mounting bracket 5 includes a mounting block 501 and two support rods 502. The support rods 502 are fixedly connected to the top of the cylinder body 102 of the hydraulic cylinder 1. The mounting block 501 is connected to the upper ends of the two support rods 502. The upper end of the elastic energy storage element 2 is fixedly connected to the mounting block 501, and the lower end of the elastic energy storage element 2 is against the tooling base plate 9. The connecting bracket 6 is sleeved on the support rod 502, and the upper and lower sides are locked by nuts. It is easy to understand that the support rod 502 is a threaded rod. It is worth noting that in this way, it is easy to adjust the height of the connecting bracket 6, thereby realizing the height adjustment of the travel switch to adapt to different types of test pieces 24.

[0035] The impact head 3 is connected to a touch member 7 for triggering a travel switch. When the impact head 3 applies a load to the test piece 24, the touch member 7 touches the travel switch, thereby triggering the travel switch. As an option, the touch member 7 is a plate-shaped structure, one end of which is rotatably connected to the impact head 3 via a pin, and a torsion spring is sleeved on the pin to keep the touch member 7 in a downward rotation trend. The impact head 3 is provided with a limit member 8 below the touch member 7 for limiting the downward rotation of the touch member 7. Under the action of the limit member 8, the touch member 7 remains parallel to the tooling base 9. Preferably, the limit member 8 is replaced by a screw. It is worth noting that such a setting ensures that the touch member 7 can trigger the travel switch while allowing the touch member 7 to rotate upward, avoiding a hard collision between the touch member 7 and the travel switch due to setting errors or failures, thereby avoiding damage to the travel switch and its connecting structure.

[0036] refer to Figure 3Two support seats 11 are spaced apart on the top of the tooling base plate 9 to support the ends of the test piece 24. It is easy to understand that the impact position of the impact head 3 on the test piece 24 is between the two support seats 11, ensuring that the test piece 24 has space to bend after being impacted. Furthermore, as an option, the distance between the two support seats 11 in this embodiment can be adjusted to accommodate test pieces 24 of different lengths. Specifically, a slide 10 is fixedly provided on the top of the tooling base plate 9, and the two support seats 11 are slidably provided on the top of the slide 10. Connecting arms 12 are fixedly connected on both sides of the support seats 11. The connecting arms 12 are connected to locking screws 13 for tightening the slide 10, and the slide 10 is provided with a limiting step for limiting the downward displacement of the locking screw. After adjusting the position of the support seat 11, the position of the support seat 11 can be fixed by tightening the locking screw 13. In addition, a scale can be provided on the top of the slide 10 to facilitate observing the distance between the two support seats 11.

[0037] refer to Figure 7 In this embodiment, the hydraulic power assembly includes an oil tank 14, a servo motor 15, an oil pump 16, a relief valve 19, a reversing valve 17, and a logic valve 18. Optionally, the oil pump 16 can be a plunger pump. The servo motor 15 drives the oil pump 16 to supply oil to the lower chamber of the hydraulic cylinder 1 through the oil supply line, causing the piston rod 101 of the hydraulic cylinder 1 to extend upward. The relief valve 19 is located on the relief line, one end of which is connected to the oil tank 14 and the other end to the oil supply line. The lower chamber of the hydraulic cylinder 1 is connected to the oil tank 14 via the return oil line, through the logic valve 18 and the reversing valve 17. Upon receiving an off-target signal, the reversing valve 17 switches direction, controlling the logic valve 18 to relieve pressure, allowing the hydraulic oil in the lower chamber of the hydraulic cylinder 1 to flow back to the oil tank 14 through the logic valve 18. In actual application, a one-way valve 20 and a filter 21 should be provided on the end of the oil supply line close to the oil tank 14. A temperature sensor 22 for detecting the internal hydraulic oil temperature is provided on the oil tank 14. In order to accurately control the pressure, a pressure sensor 23 can also be provided on the oil supply line.

[0038] There is no restriction on the brands and models of the various electrical components. For example, in this embodiment, the brand of the servo motor 15 is Shenzhen Huichuan Technology, and the model is MS1H1-10C30CB; the brand of the oil pump 16 is Guiyang Haizhili, and the model is HYC-MP1F0.65B; the brand of the overflow valve 19 is Ningbo Ketai, and the model is LRV-08; the brand of the reversing valve 17 is Ningbo Ketai, and the model is LSV6-12-2NOSP; the brand of the logic valve 18 is Beijing Huade, and the model is LC32B05E7X; the brand of the one-way valve 20 is Ningbo Ketai, and the model is CVR2000-G14; the brand of the filter 21 is Xinxiang Tongyuan, and the model is FLDA; the brand of the temperature sensor 22 is Beijing Xingyi, and the model is CWD-Z11; the brand of the pressure sensor 23 is Holywell, and the model is GPTJG3YG400BSCHX.

[0039] In actual applications, each electrical component is connected to the control system of the material testing machine to facilitate automatic control. It should be understood that controlling the operation of each electrical component through the control system can be achieved by those skilled in the art based on existing technology and common knowledge in the field, and is not an improvement point of the present invention. Therefore, it will not be elaborated in this embodiment.

[0040] On the basis of the above, the workflow of the off-target device is divided into three stages: test preparation stage, standby stage and rapid off-target stage, as follows.

[0041] Test preparation stage: The servo motor 15 works to drive the oil pump 16 to rotate and provide a power source. The reversing valve 17 is normally closed and is in the left working state in the figure. The logic valve 18 controls the chamber pressure to increase. The logic valve 18 is in the closed state. The hydraulic oil flows to the lower chamber of the hydraulic cylinder 1. The piston rod 101 of the hydraulic cylinder 1 moves upward to the highest point under the action of the hydraulic oil. The elastic energy storage element 2 is in an energy storage compression state under the thrust of the piston rod 101.

[0042] Standby stage: When the piston rod 101 of the hydraulic cylinder 1 is at its highest point, the servo motor 15 continues to run at a low speed to maintain the pressure in the hydraulic cylinder 1. When the servo motor 15 is on standby to maintain pressure, the overflow valve 19 continues to overflow and generate heat. The temperature sensor 22 detects the temperature of the hydraulic oil and issues an alarm when it reaches a certain temperature value. When it exceeds the set value, the motor is controlled to stop. Therefore, the standby state should not be too long.

[0043] Rapid off-target stage: the impact head 3 impacts vertically downward at a constant speed under the action of the material testing machine. When loaded to the target position, the touch member 7 triggers the travel switch, thereby sending an off-target signal. The off-target signal is transmitted to the reversing valve 17, which controls the reversing valve 17 to be in the right working state in the figure. The control chamber of the logic valve 18 is depressurized, and the hydraulic oil in the lower chamber of the hydraulic cylinder 1 is discharged to the oil tank 14 at a large flow rate through the logic valve 18, thereby realizing the unloading of the hydraulic cylinder 1. At the same time, the elastic energy storage element 2 releases energy, and the tooling base plate 9 and the piston rod 101 of the hydraulic cylinder 1 generate a large acceleration under the action of the elastic energy storage element 2, and are instantly ejected downward, thereby realizing the rapid off-target of the test piece 24, so that the test piece 24 is free from the force.

[0044] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A rapid ejection and miss-target device for dynamic impact testing of materials, characterized in that: include: A hydraulic cylinder connected to a hydraulic power assembly for oil supply and oil return; An elastic energy storage element, which is mounted on the cylinder body of the hydraulic cylinder; A tooling base plate used to support the test piece, which is fixedly connected to the piston rod of the hydraulic cylinder and compresses the elastic energy storage element to store energy under the thrust of the piston rod; The impact head is connected to the loading component of the material testing machine; and a position detection element to send an off-target signal when the impact head is loaded to the target position. The hydraulic cylinder then unloads, and the tooling base plate is ejected downward under the action of the elastic energy storage element, so that the test piece is freed from the force.

2. The rapid ejection and miss-target device for dynamic impact testing of materials according to claim 1, characterized in that: The position detection element is a travel switch, the travel switch and the cylinder body of the hydraulic cylinder are relatively fixed in position, and the impact head is connected to a touch piece for triggering the travel switch.

3. The rapid ejection and miss-target device for dynamic impact testing of materials according to claim 2, characterized in that: The touch member is a plate-shaped structure, one end of which is rotatably connected to the impact head via a pin shaft, and the pin shaft is sleeved with a torsion spring to keep the touch member in a downward rotation trend. The impact head is provided with a limit member below the touch member for limiting the downward rotation of the touch member.

4. The rapid ejection and miss-target device for dynamic impact testing of materials according to claim 2, characterized in that: A mounting bracket for mounting the elastic energy storage element is provided on the top of the cylinder body of the hydraulic cylinder. The travel switch is mounted on a connecting bracket, and the connecting bracket is connected to the mounting bracket.

5. The rapid ejection and miss-target device for dynamic impact testing of materials according to claim 4, characterized in that: The mounting bracket includes a mounting block and two support rods. The support rods are fixedly connected to the top of the cylinder body of the hydraulic cylinder. The mounting block is connected to the upper ends of the two support rods. The upper end of the elastic energy storage element is fixedly connected to the mounting block, and the lower end of the elastic energy storage element is against the tooling base plate. The connecting bracket is sleeved on the support rods, and the upper and lower sides are locked by nuts.

6. The rapid ejection and miss-target device for dynamic impact testing of materials according to claim 1, characterized in that: Two support seats are arranged at intervals on the top of the tooling bottom plate for supporting the ends of the test piece.

7. The rapid ejection and miss-target device for dynamic impact testing of materials according to claim 6, characterized in that: A slide is fixedly provided on the top of the tooling base plate, and the two support seats are slidably provided on the top of the slide. Connecting arms are fixedly connected on both sides of the support seat, and locking screws for tightening the slide are connected to the connecting arms, and a limiting step is provided on the slide for limiting the downward displacement of the locking screw.

8. The rapid ejection and miss-target device for dynamic impact testing of materials according to claim 1, characterized in that: The elastic energy storage element is a nitrogen spring.

9. The rapid ejection and miss-target device for dynamic impact testing of materials according to any one of claims 1 to 8, characterized in that: The hydraulic power assembly includes an oil tank, a servo motor, an oil pump, a reversing valve and a logic valve; the servo motor drives the oil pump to supply oil to the lower chamber of the hydraulic cylinder through the oil supply pipeline, so that the piston rod of the hydraulic cylinder extends upward; the lower chamber of the hydraulic cylinder is connected to the oil tank through the return oil pipeline via the logic valve and the reversing valve. The reversing valve reverses after receiving the off-target signal, controls the logic valve to relieve pressure, and allows the hydraulic oil in the lower chamber of the hydraulic cylinder to flow back to the oil tank through the logic valve.

10. The rapid ejection and miss-target device for dynamic impact testing of materials according to claim 9, characterized in that: The hydraulic power assembly further comprises an overflow valve, which is arranged on an overflow pipeline. One end of the overflow pipeline is connected to the oil tank, and the other end of the overflow pipeline is connected to the oil supply pipeline.

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