CN106483020B - High temperature and high pressure fretting fatigue testing machine - Google Patents

Abstract

The invention discloses a high-temperature, high-pressure fretting fatigue testing machine, which can be used for fretting fatigue testing in high-temperature, high-pressure water, steam or liquid environments. The normal force loading device used in the testing machine only needs to use a small-load linear motor The constant normal force loading on the sample can be realized, and the force value lost after the wear between the compression gasket and the sample can be compensated in real time during the whole test process, which can significantly improve the load control and measurement accuracy , obtain a stable normal force loading force value, and then improve the overall test accuracy of the fretting fatigue testing machine.

Description

High temperature and high pressure fretting fatigue testing machine

technical field

The invention relates to a high-temperature and high-pressure fretting fatigue testing machine.

Background technique

Fretting is a kind of wear phenomenon that occurs on two contact surfaces. It usually appears on the contact surfaces with small and continuous relative motion. Generally, the displacement range is on the order of microns, usually tens to hundreds between many microns. Fretting fatigue refers to the phenomenon that under the action of cyclic load, the fatigue strength of the component decreases or the early fracture occurs due to the small amplitude relative sliding between a certain part of the surface and other contact surfaces. Fretting fatigue (Fretting Fatigue, FF) phenomenon widely exists in the fields of machinery, transportation, electric power, aerospace, and even biomedical engineering. It will accelerate the initiation and growth of fatigue cracks in components, thereby significantly reducing service life and even causing disasters. Sexual accidents, so fretting injuries have been called the cancer of industry. Studies have shown that fretting energy reduces the fatigue life of components by 20% to 80%, or even lower. Therefore, systematically studying the damage behavior and protective measures of fretting fatigue has important theoretical significance and engineering application value.

However, the wear of components in the industrial field often occurs in high-temperature and/or high-pressure water chemical environments or gas environments, and the data measured between components on conventional mechanical testing machines cannot be applied. In the prior art, there is no fretting fatigue testing machine for high-temperature water chemical environment or high-temperature gas environment in the industrial field. This application proposes to address the above-mentioned problems. Fretting fatigue test provides a complete set of test equipment.

In addition, in the fretting fatigue test, it is very important to maintain the long-term stable loading of the normal force, which is the key to quantitatively characterize the effect of fretting on the fatigue life of materials. At present, the commonly used fretting fatigue normal force loading method is bolt loading or stress ring loading. The disadvantage of this method is that as the test progresses, wear will occur between the gasket and the sample, thus causing the gap between the two The normal force cannot be kept constant, it will continue to decrease, and even the normal force will be zero. This method may be able to use manual adjustments to compensate for the loss of normal force at room temperature and pressure, but in a high-temperature, high-pressure airtight environment, manual adjustments and compensations cannot be performed, and manual adjustments and compensations cannot be adjusted in real time.

Contents of the invention

The object of the present invention is to provide a high temperature and high pressure fretting fatigue testing machine in order to overcome the shortcomings of the prior art.

In order to achieve the above object, the technical solution adopted by the present invention is: a high-temperature, high-pressure fretting fatigue testing machine, including a machine base, a main shaft arranged on the machine base up and down, and a pressure force fixed on the machine base. The pressure vessel has a closed environment chamber that can be filled with a high temperature and high pressure environment, the main shaft extends into the environmental chamber, and the sample is fixed on the main shaft by a clamp and placed in the environmental chamber , the testing machine also includes a normal force loading device for carrying out normal force loading on the sample, and the normal force loading device includes:

Compression pads, there are two groups of compression pads, and the two groups of compression pads are respectively arranged on different sides of the radial direction of the sample to compress the sample radially;

The gasket guide plate is fixedly arranged in the environmental chamber relative to the fixture, and the gasket guide plate is provided with accommodation grooves for the sample to penetrate in the radial direction, respectively located in the accommodation chamber. Two guide grooves on both sides of the groove and connected with the receiving groove, and two sets of the pressing pads are respectively arranged in the guide grooves on both sides in a sliding fit;

Pressing and holding mechanism, said holding mechanism has two groups, respectively used to apply two groups of said pressing pads to compress force, said holding mechanism includes a linear motor fixed on said machine base, affixed to The pressure self-balancing stretching shaft on the motor shaft of the linear motor, the pressure self-balancing stretching shaft has an output end extending into the environmental chamber, the output end is fixedly connected with a force sensor, the The pressing mechanism also includes a connecting shaft with one end fixedly connected to the force sensor, and the other end of the connecting shaft is a pressing end for pushing the pressing pad to apply a pressing force;

The normal force loading device further includes a controller capable of controlling the working states of the two sets of linear motors according to the pressure values fed back by the two sets of force sensors.

Preferably, the pressing ends of the connecting shafts on both sides respectively protrude into the corresponding guide grooves in the axial direction to exert a pressing force on the pressing washers.

Preferably, the contact end surface of the compression gasket in contact with the sample is an arc surface, a plane or a spherical surface, and the centerlines of the compression gaskets on both sides are collinear and along the radial direction of the sample. Centerline extended.

Preferably, the gasket guide plate is disc-shaped, the receiving groove is U-shaped with its opening facing radially outward, and the gasket guide plate is fixed on the clamp.

Preferably, the pressing washer and the guide groove are arranged in a clearance fit manner.

Preferably, the pressure vessel is an autoclave that can be filled with a high-temperature and high-pressure gas or liquid environment, and the autoclave includes a kettle body fixed on the machine base, and a cooperably opened and closed kettle body located above the kettle body. The kettle cover, the main shaft of the fatigue testing machine passes through the kettle cover and extends into the inner cavity of the autoclave.

Further, the fixture is fixedly installed on the kettle cover and the sample is fixedly installed between the fixture and the main shaft, and the gasket guide plate is relatively fixed to the kettle cover and the fixture ground setting.

As a specific embodiment, the clamp includes a clamp seat and a plurality of connecting columns fixedly connecting the clamp seat and the kettle cover, and the gasket guide plate is fixedly arranged on the plurality of connecting columns.

Further, the fatigue testing machine also includes a beam whose position can be adjusted up and down relative to the machine base, the kettle cover is mounted on the beam; the main shaft can be vertically lifted on the beam, The beam is also provided with a lift drive mechanism for driving the main shaft to lift up and down in the vertical direction.

Furthermore, the lifting drive mechanism includes an oil cylinder arranged on the upper part of the crossbeam, the telescopic rod of the oil cylinder protrudes downwards and is connected with the main shaft, and there is also a Another force sensor, the main shaft adopts another pressure self-balancing tension shaft, and the top of the oil cylinder is also provided with a displacement sensor.

Due to the application of the above-mentioned technical scheme, the present invention has the following advantages compared with the prior art: the high temperature and high pressure fretting fatigue testing machine of the present invention can be used for fretting fatigue testing under high temperature and high pressure water, steam or liquid environment, the testing machine The normal force loading device used in the test can realize the constant loading of the normal force only by using a linear motor with a small load, and compensate the loss of force value after the wear between the compression gasket and the sample in real time, and maintain the normal force. The force value is constant, which can significantly improve the load control and measurement accuracy, and obtain a stable normal force loading force value, thereby improving the overall test accuracy of the fretting fatigue testing machine.

Description of drawings

Accompanying drawing 1 is the three-dimensional schematic view of the overall structure of the fatigue testing machine of the present invention;

Accompanying drawing 2 is the front view of fatigue testing machine of the present invention;

Accompanying drawing 3 is the side view sectional schematic diagram of fatigue testing machine of the present invention;

Accompanying drawing 4 is the enlarged schematic diagram of normal force loading device part in accompanying drawing 3;

Accompanying drawing 5 is the installation sketch map of sample;

Accompanying drawing 6 is the schematic diagram of gasket guide plate;

Accompanying drawings 7, 8, 9 and 10 are respectively schematic diagrams of the loading adjustment principle of the normal force loading device.

Among them: 10. Machine base; 20. Beam; 30. Column; 40. Oil cylinder; 50. Displacement sensor; 60. Force sensor; 70. Connecting flange; 80. Connecting column;

1. Autoclave; 11. Kettle body; 12. Kettle cover; 2. Main shaft; 3. Sample; 4. Fixture; 41. Fixture seat; 42. Connecting column; plate; 61, storage tank; 62, guide groove; 7, holding mechanism; 71, linear motor; 72, pressure self-balancing stretching shaft; 73, force sensor; 74, connecting shaft; 8, controller.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Referring to Figures 1 to 6, a high-temperature, high-pressure fretting fatigue testing machine includes a base 10, two columns 30 fixedly arranged on the base 10 and extending vertically, and vertically arranged on the uprights 30. The upper and lower beams 20 are adjustable relative to the machine base 10. The beam 20 is provided with a main shaft 2, and the main shaft 2 is arranged on the beam 20 up and down. The top of the crossbeam 20 is also provided with a lifting drive mechanism for driving the main shaft 2 up and down. Here, the lifting driving mechanism adopts an oil cylinder 40, and the telescopic rod of the oil cylinder 40 stretches out downwards and is connected with the main shaft 2 for providing and Control the reciprocating motion under certain amplitude or load and frequency. A force sensor 60 is also arranged between the main shaft 2 and the above-mentioned telescopic rod. What the main shaft 2 adopts here is a pressure self-balancing stretching shaft; displacement.

Referring to Figures 1 to 6, the fatigue testing machine also includes a pressure vessel fixed on the machine base 10, the pressure vessel has a closed environment chamber that can be filled with high temperature and high pressure gas or liquid environment, here, the pressure vessel adopts The autoclave 1 is an autoclave 1, which includes a kettle body 11 fixedly arranged on the machine base 10, a kettle lid 12 that can be opened and closed on the top of the kettle body 11, and the kettle lid 12 is cooperatively covered on the kettle body 11. The inner cavity of the autoclave 11 is sealed so that it can be filled with a high-temperature and high-pressure gas or liquid environment, and the environmental parameters in the environmental chamber of the autoclave 1 are controlled by additionally setting a water circulation and water chemical detection system.

The main shaft 2 extends into the environmental chamber of the autoclave 1 through the kettle cover 12 , and the sample 3 is fixed on the main shaft 2 by the clamp 4 and placed in the environmental chamber of the autoclave 1 . Here, since the main shaft 2 is a pressure self-balancing stretching shaft, which has a pressure self-balancing function, it can offset the pressure difference inside and outside the autoclave 1, eliminate the thrust generated by the pressure difference, and can realize dynamic sealing under high temperature and high pressure environment , the pressure self-balancing tensile shaft is used to connect the actuating part of the testing machine and the fixture 4 in the kettle, which can ensure that the actuating part of the fatigue testing machine is not affected by the pressure difference between the inside and outside of the autoclave 1 on the load during the reciprocating movement.

Referring to Fig. 1 and Fig. 2, the kettle cover 12 is connected to the crossbeam 20 through the loading and unloading kettle mechanism, and the crossbeam 20 drives its lifting relative to the kettle body 11 to realize opening and closing. Specifically, the above-mentioned loading and unloading kettle mechanism includes a connecting flange 70 and a plurality of connecting columns 80. The connecting flange 70 is fixedly connected to the lower end surface of the beam 20 by bolts, and the lower end of the connecting column 80 is fixedly connected to the kettle cover 12, and its upper end passes through the The through hole on the connection flange 70 is locked by a nut, so that when the autoclave 1 is installed, the crossbeam 20 moves downward, and the kettle cover 12 descends. When the nut on the connection column 80 is not in contact with the surface of the connection flange 70 , it can be determined that the kettle cover 12 is installed in cooperation with the kettle body 11. The above arrangement of the connecting column 80 and the connecting flange 70 can avoid the fixed connection. During the installation of the kettle cover 12, when the kettle cover 12 is installed with the kettle body 11, the crossbeam 20 moves excessively and the whole device is under stress. , resulting in damage to the test device.

Referring to the accompanying drawings, the fatigue testing machine also includes a normal force loading device for carrying out normal force loading on the sample 3, and the normal force loading device includes:

Compression pads 5, the compression pads 5 have two groups, respectively arranged on different sides of the sample 3 in the radial direction to compress the sample 3 in the radial direction. The contact end surface of the compression gasket 5 in contact with the sample 3 can be an arc surface, a plane or a spherical surface, and the type of the contact end surface is determined according to the test requirements. The centerlines of the compression gaskets 5 on both sides are collinear and extend with the radial centerline of the sample 3, so as to ensure that the normal force is applied to the sample 3 when the two compression gaskets 5 are respectively compressed from both sides;

The gasket guide plate 6 is fixedly arranged in the environment chamber of the autoclave 1 relative to the fixture 4 for providing motion guidance when the two compression gaskets 5 compress the sample 3 . Specifically, as shown in FIG. 6, the gasket guide plate 6 is disc-shaped, and there are receiving grooves 61 on which the sample 3 can penetrate in the radial direction. 61 is connected with two guide grooves 62, the receiving groove 61 is U-shaped with the opening facing its radially outer side, the sample 3 enters the receiving groove 61 along the radial direction, and the compression gaskets 5 on both sides can slide and fit respectively. Set in the guide grooves 62 on both sides, the spacer between the compression gasket 5 and the guide grooves 62 can be arranged in a loose fit, and the gap value should be as small as possible under the premise of ensuring free sliding during high temperature expansion. In this embodiment, the gasket guide plate 6 is fixedly arranged on the fixture 4, specifically, the fixture 4 includes a fixture seat 41 and a plurality of connecting columns 42 fixedly connected between the fixture seat 41 and the lid 12 of the autoclave 1 , the gasket guide plate 6 is fixed on the above-mentioned plurality of connecting columns 42, as shown in Figure 5;

The pressing mechanism 7 has two groups, which are respectively used to apply the pressing force to the pressing pads 5 on both sides, so as to apply the normal force to the sample 3 . Referring to Fig. 3 and Fig. 4, each set of holding mechanism 7 includes a linear motor 71 fixedly arranged on the machine base 10, a pressure self-balancing stretching shaft 72 fixed on the motor shaft of the linear motor 71, the The pressure self-balancing stretching shaft 72 has an output end extending into the environment chamber of the autoclave 1, and a force sensor 73 is fixedly connected to the output end; the pressing mechanism 7 also includes a connecting shaft 74, and one end of the connecting shaft 74 Fixed to the force sensor 73, the other end of the connecting shaft 73 is a pressing end for pushing the pressing pad 5 to apply a pressing force. When the normal force is applied, the pressing ends of the connecting shafts 73 on both sides respectively protrude into the corresponding guide grooves 62 in the axial direction to exert a pressing force on the corresponding pressing washers 5 .

The normal force loading device also includes a controller 8, which is connected to the force sensors 73 on both sides for signals, and is also connected to the linear motors 71 on both sides for signals. The controller 8 can control the working states of the two sets of linear motors 71 according to the pressure values fed back by the force sensors 73 on both sides, so that the normal force applied to the sample 3 by the compression pads 5 on both sides remains at a set value or within the setting range.

The following briefly describes the working process and working principle of the high temperature and high pressure fretting fatigue testing machine of the present embodiment:

Firstly, the fixture 4 is installed on the lid 12 of the autoclave 1, and the gasket guide plate 6 is installed at the same time, and then the sample 3 is installed between the fixture seat 41 and the main shaft 2, and the sample 3 passes through the The receiving groove 61 of the gasket guide plate 6, and then put the two compression gaskets 5 into the two guide grooves 61 of the gasket guide plate 6, so that the compression gasket 5 on both sides is in slight contact with the sample 3, When installing, try to make the center connection line between the compression gaskets 5 on both sides and the sample 3 in contact with the sample 3 extend along the radial center line of the sample 3. Next, the beam 20 is lowered relative to the machine base 10, so that the kettle cover 12 is matched with the kettle body 11 to form a closed environmental chamber, and the environment in the environmental chamber of the autoclave 1 is controlled through the water circulation and water chemical detection system parameters, so that the environmental state filled in the environmental chamber meets the test requirements.

Next, load the normal force. Initially, as shown in FIG. 7, the pressing end of the connecting shaft 74 has not yet stretched into the guide groove 62 of the washer guide plate 6. At this time, the normal force F ₀ =0 . First determine the distance S between the pressing end of the connecting shaft 74 and the end surface of the pressing gasket 5, and the controller 8 switches to the displacement control mode. As shown in Figure 8, the controller 8 controls the linear motors 71 on both sides to work so that after the displacement of the pressing end of the connecting shaft 74 reaches S, the linear motor 71 temporarily stops working. There is slight contact between the end faces, and the normal force F ₀ =0.

Then, the controller 8 switches to the force control mode, and the controller 8 receives the pressure values fed back by the force sensors 73 on both sides to control the working state of the linear motor 71 . Specifically as follows: as shown in Figure 9, the controller 8 controls two groups of linear motors 71 to work so that the connecting shafts 74 on both sides move toward each other and gradually approach the compression pads 5 on both sides respectively, and the force sensors 73 on both sides respectively Feedback the detected pressure value F ₀ to the controller 8 in real time, when the detected pressure value F ₀ is less than the test preset stress value F ₁ , the controller 8 controls the two linear motors 71 to work and continue to drive the two connecting shafts 74 move in opposite directions until the pressure value _F0 fed back to the controller 8 by the force sensor 73 is equal to _F1 , as shown in Figure 10, the controller 8 controls the two linear motors 71 to stop moving and maintain the pressure value, and the fretting fatigue test starts .

During the fretting fatigue test, the normal force loading device always keeps the normal force applied by the compression gasket 5 on the sample 3 within the set range, and the set range is F ₀ =F ₁ ±f , where f is the fluctuation amplitude of the normal force value set in the fatigue test. Specifically, the two force sensors 73 respectively feed back the detected pressure value F ₀ to the controller 8 in real time, and when F ₁ -f ≤ F ₀ ≤ _{F 1} +f, the controller 8 controls the linear motor 71 to keep the state of stopping motion; When F ₀ ≤ F ₁ -f, the controller 8 controls the linear motor 71 to work to drive the two connecting shafts 74 to move toward each other to increase the pressure value; when F ₀ ≥ _{F 1} -f, the controller 8 controls the linear motor 71 to work and Drive the two connecting shafts 74 to move in opposite directions to reduce the pressure value. This ensures a constant loading of the normal force throughout the fretting fatigue test.

In summary, the high temperature and high pressure fretting fatigue testing machine of the present invention has the following advantages:

(1) The fretting fatigue testing machine can simulate the fretting fatigue test under the temperature and pressure water chemical conditions of the primary and secondary circuits of the nuclear power plant;

(2) The fretting fatigue test is carried out using the fretting fatigue testing machine. The contact mode between the sample 3 and the compression gasket 5 can be point, line or surface contact, and the fatigue life cycle of each sample can be obtained by measurement number, multiple groups of samples, and different parameters, the fatigue life curve of the sample can be obtained, that is, the S-N curve;

(3) The structure of the fatigue testing machine is simple, and its verticality and levelness can be easily adjusted to ensure the coaxiality and verticality of the fatigue testing machine;

(4) The normal force loading device used in this fatigue testing machine only needs to use a linear motor with a small load to achieve constant loading of the normal force, and compensate for the wear between the compression gasket and the sample in real time. The lost force value can improve the load control and measurement accuracy, and obtain a stable normal force loading force value;

(5) The pressure self-balancing tensile shaft design can realize the offset of the pressure difference inside and outside the autoclave 1, eliminate the thrust generated by the pressure difference, and further improve the accuracy of the test.

The above-mentioned embodiments are only to illustrate the technical concept and characteristics of the present invention, and the purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and not to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention shall fall within the protection scope of the present invention.

Claims (10)

1. The utility model provides a high temperature high pressure micro-motion fatigue testing machine, includes the frame, locates with the oscilaltion main shaft on the frame, set firmly in pressure vessel on the frame, pressure vessel has the airtight environment cavity that can full high temperature high pressure environment, the main shaft stretches into in the environment cavity, the sample is fixed through the anchor clamps on the main shaft and juxtaposing in the environment cavity, its characterized in that, the testing machine still includes and is used for carrying out normal force loading device of normal force loading to the sample, normal force loading device includes:

the two groups of the pressing gaskets are respectively arranged on two different sides of the sample in the radial direction so as to respectively press the sample in the radial direction;

the gasket guide plate is fixedly arranged in the environment chamber relative to the clamp, a containing groove for the sample to penetrate in the radial direction and two guide grooves which are respectively positioned at two sides of the containing groove and communicated with the containing groove are formed in the gasket guide plate, and two groups of compression gaskets are respectively arranged in the guide grooves at two sides in a sliding fit manner;

the pressing mechanism comprises two groups of pressing gaskets for applying pressing force, the pressing mechanism comprises a linear motor fixedly arranged on the base and a pressure self-balancing stretching shaft fixedly connected to a motor shaft of the linear motor, the pressure self-balancing stretching shaft is provided with an output end extending into the environment chamber, a force sensor is fixedly connected to the output end, the pressing mechanism further comprises a connecting shaft, one end of the connecting shaft is fixedly connected to the force sensor, and the other end of the connecting shaft is a pressing end for pushing the pressing gaskets to apply the pressing force;

the normal force loading device also comprises a controller which can control the working states of the two groups of linear motors according to the pressure values fed back by the two groups of force sensors, wherein the normal force loading device always keeps the normal force applied by the compression gasket to the sample within a set range in the process of micro fatigue test,

the setting range is F ₀ =F ₁ F (+/-F), wherein F ₀ Feeding back the detected pressure value to the controller in real time for the force sensor, F ₁ The stress value preset for the test is f, which is the fluctuation amplitude value of the normal force value set by the fatigue test; when F ₁ -f≤F ₀ ≤F ₁ When +f, the controller controls the linear motor to keep a state of stopping movement; when F ₀ ＜F ₁ -f, when the controller controls the linear motor to work so as to drive the two groups of connecting shafts to move oppositely to increase the pressure value; when F ₀ ＞F ₁ And when +f, the controller controls the linear motor to work so as to drive the two groups of connecting shafts to move in opposite directions to reduce the pressure value.

2. The high temperature high pressure fretting fatigue testing machine according to claim 1, wherein: the pressing ends of the connecting shafts on the two sides extend into the corresponding guide grooves along the axial direction respectively so as to apply the pressing gaskets to press the force.

3. The high temperature high pressure fretting fatigue testing machine according to claim 1, wherein: the contact end face of the compaction gasket, which is in contact with the sample, is an arc surface, a plane or a spherical surface, and the central lines of the compaction gaskets on two sides are collinear and extend along the radial central line of the sample.

4. The high temperature high pressure fretting fatigue testing machine according to claim 1, wherein: the gasket guide plate is disc-shaped, the accommodating groove is U-shaped with an opening facing the radial outer side of the accommodating groove, and the gasket guide plate is fixed on the clamp.

5. The high temperature high pressure fretting fatigue testing machine according to claim 1, wherein: the compression gasket and the guide groove are arranged in a clearance fit manner.

6. The high temperature high pressure fretting fatigue testing machine according to claim 1, wherein: the pressure vessel is an autoclave capable of filling high-temperature high-pressure gas or liquid environment, the autoclave comprises a kettle body fixedly arranged on the base and a kettle cover arranged above the kettle body and capable of being opened and closed in a matched mode, and the main shaft of the fatigue testing machine penetrates through the kettle cover and stretches into an inner cavity of the autoclave.

7. The high temperature high pressure fretting fatigue testing machine according to claim 6, wherein: the clamp is fixedly arranged on the kettle cover, the sample is fixedly arranged between the clamp and the main shaft, and the gasket guide plate, the kettle cover and the clamp are relatively fixedly arranged.

8. The high temperature high pressure fretting fatigue testing machine according to claim 7, wherein: the clamp comprises a clamp seat, a plurality of connecting columns fixedly connected with the clamp seat and the kettle cover, and the gasket guide plates are fixedly arranged on the connecting columns.

9. The high temperature high pressure fretting fatigue testing machine according to claim 6, wherein: the fatigue testing machine also comprises a cross beam with an adjustable upper and lower position relative to the machine base, and the kettle cover is arranged on the cross beam; the main shaft can be arranged on the cross beam in a lifting manner along the vertical direction, and a lifting driving mechanism for driving the main shaft to lift along the vertical direction is further arranged on the cross beam.

10. The high temperature high pressure fretting fatigue testing machine according to claim 9, wherein: the lifting driving mechanism comprises an oil cylinder arranged on the upper portion of the cross beam, a telescopic rod of the oil cylinder extends downwards to be connected with the main shaft, another force sensor is further arranged between the main shaft and the telescopic rod, the main shaft adopts another pressure self-balancing stretching shaft, and a displacement sensor is further arranged on the upper portion of the oil cylinder.