Multi-station high-temperature dynamic compression fatigue test bench

Abstract

The invention relates to the field of mechanics and mechanical engineering, in particular to a multi-station high-temperature dynamic compression fatigue test bed. According to the test bed, a lifting column is arranged on a base, a transverse plate is installed at the upper end of the lifting column, a center hole is formed in the center of the transverse plate and used for installing a flange linear bearing, and a through hole is formed beside the center hole and used for installing an eddy current displacement sensor; a thermal environment box is arranged between the base and the transverse plate; a temperature sensor is arranged in the thermal environment box; the upper end of the push rod is connected with the grinding block and penetrates through the guide plate, the spring and the flange linear bearing; the lower portion of the push rod penetrates through the top of the thermal environment box and is connected with a tool clamp arranged in the thermal environment box. A displacement measuring plate and a piezoelectric force sensor are arranged in the middle of the push rod; a T-shaped vertical bearing seat is arranged on the transverse plate; the multi-station transmission shaft is positioned and mounted in a radial rolling bearing of the T-shaped vertical bearing seat through a shaft shoulder; three cams are distributed on the multi-station transmission shaft at equal intervals, and the cams are in higher pair contact with the grinding blocks; a servo motor is arranged on the lifting seat; a rotating shaft of the servo motor is connected with a multi-station transmission shaft through a flexible coupling; and the control computer is used for collecting, analyzing and controlling. The device can accurately measure the vibration load and the dynamic displacement, is simple in structure and reasonable in design, and can perform loading test measurement on a plurality of samples at the same time.

Description

Technical Field

[0001] The invention relates to the field of mechanics and mechanical engineering, and in particular to a multi-station high-temperature dynamic compression fatigue test bench. Background Art

[0002] The high temperature dynamic test bench is a key equipment in the product development stage. It simulates the high temperature environment and alternating load conditions that the product may encounter in actual application in a laboratory environment. By collecting test data under dynamic loading, the equipment can evaluate the mechanical behavior and fatigue resistance of the product, thereby guiding the optimization of product structure and strength design.

[0003] At present, the typical application equipment commonly used in engineering to generate excitation includes eccentric vibrators, exciters and electro-hydraulic servo dynamic and static testing machines. Their main working principles are mechanical principle, electromagnetic principle and electro-hydraulic servo principle. Among them, due to the limitation of its working principle, it is difficult to accurately control the vibration trajectory of the eccentric vibrator, and its stability is poor during long-term operation; the electromagnetic exciter generates a magnetic field through electric current. The greater the magnetic force, the greater the amplitude. During fatigue testing, the mechanical properties of the material change, and the amplitude will also change accordingly, making it difficult to achieve precise control of the amplitude; the working load range of the electro-hydraulic servo dynamic and static testing machine is usually between 20kN and 1000kN, and there are limitations in the accurate measurement of small loads. In addition, the recommended vibration frequency of the equipment is about 10Hz, which is not conducive to efficient fatigue testing.

[0004] Although the excitation devices in the prior art can perform dynamic mechanical or fatigue tests on specimens, they have obvious limitations in terms of long-term operating stability, working efficiency, and accuracy of small load measurements. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a multi-station high-temperature dynamic compression fatigue test bench which can accurately measure vibration load and dynamic displacement, has a simple structure, a reasonable design, and can perform loading test measurements on multiple samples at the same time.

[0006] The present invention provides a multi-station high temperature dynamic compression fatigue test bench, comprising:

[0007] A lifting column is arranged on the base, and a horizontal plate is installed on the upper end of the lifting column. A center hole is opened in the center of the horizontal plate for installing a flange linear bearing.

[0008] A through hole is provided next to the central hole to install an eddy current displacement sensor;

[0009] A thermal environment box is provided between the base and the horizontal plate;

[0010] The upper and lower ends of the thermal environment box are designed with through holes corresponding to the multiple stations, and temperature sensors are set inside;

[0011] A push rod, the upper end of which is connected to the grinding block and passes through the guide plate, spring and flange linear bearing;

[0012] The lower part of the push rod passes through the top of the thermal environment box and is connected to a fixture disposed in the thermal environment box;

[0013] A displacement measuring plate and a piezoelectric force sensor are arranged in the middle of the push rod;

[0014] A T-type vertical bearing seat is arranged on the horizontal plate, and the multi-station transmission shaft is installed in the radial rolling bearing of the T-type vertical bearing seat through the shaft shoulder positioning;

[0015] Three cams are evenly spaced on the multi-station transmission shaft, and keyways are arranged at intervals of 2π / 3.

[0016] The cam and the grinding block are in high-pair contact;

[0017] A servo motor is arranged on the lifting seat, and the rotating shaft of the servo motor is connected to the multi-station transmission shaft through a flexible coupling;

[0018] The control computer is used to collect temperature data in real time using the temperature sensor, and implement heating control of the thermal environment box according to the temperature data, collect piezoelectric force sensor signals and eddy current displacement sensor signals, and control the movement of the servo motor according to the analysis of pressure and displacement signals.

[0019] In a specific embodiment of the present invention, the top corners of the base are provided with four threaded holes for installing threaded lifting columns, the top corners of the cross plate are provided with through holes with a diameter slightly larger than the outer diameter of the threaded lifting columns, and the base and the cross plate are adjusted, positioned and installed by nuts.

[0020] In a specific embodiment of the present invention, it also includes a cylindrical pin, and the cross plate and the base are positioned by two front and rear cylindrical pins.

[0021] In a specific embodiment of the present invention, the control computer starts and controls the operation of the servo motor through a servo motor controller to achieve frequency control of 1 to 30 Hz, and then uses a flexible coupling to efficiently transmit the torque of the servo motor spindle to the multi-station transmission shaft.

[0022] In a specific embodiment of the present invention, the cylindrical probe of the eddy current sensor passes through the through hole of the horizontal plate and is vertically installed above the end surface of the displacement measuring plate to convert the displacement signal of the displacement measuring plate into an electrical signal.

[0023] In a specific implementation manner of the present invention, the fixture and the piezoelectric force sensor are connected by using heat-insulating bakelite.

[0024] In a specific embodiment of the present invention, the thermal environment box is a split-type structure, and the heating resistors in the box are connected in series; the box design adopts a three-layer structure, from inside to outside: silicon carbide furnace tiles, with alloy resistance wires directly embedded inside; the middle layer adopts carbon ceramic fiber insulation material; and the outer layer is covered with 304 stainless steel thin plates.

[0025] In a specific embodiment of the present invention, retaining ring grooves are provided on both sides of the cam assembly position for installing elastic retaining rings for the shaft.

[0026] In a specific embodiment of the present invention, the cam is made of high-hardness alloy steel material and has been subjected to quenching and tempering treatment, and the grinding block is made of high-hardness alloy steel material that has not been heat-treated.

[0027] In a specific embodiment of the present invention, the cam profile is processed according to the cosine acceleration motion law, and the cam keyway is designed at a radial position corresponding to the maximum thrust hmax. The effect of changing the excitation amplitude can be achieved by replacing cams with different profiles.

[0028] Compared with the prior art, the multi-station high temperature dynamic compression fatigue test bench of the present invention has the following beneficial effects:

[0029] (1) Use a multi-station cam transmission mechanism to achieve precise and controllable reciprocating linear motion excitation. When the test bench is working, the rotation speed of the cam is adjusted by controlling the speed of the drive motor, thereby adjusting the reciprocating linear motion frequency of the push rod to achieve frequency control of 1 to 30 Hz. The camshaft adopts an innovative multi-station design, which enables the test bench to perform dynamic compression tests on multiple specimens at the same time, greatly improving the efficiency of fatigue testing. The drive shaft and cam are separate designs, and the amplitude and waveform can be adjusted by simply replacing cams with different working profiles. In addition, the thermal environment chamber equipped with the test bench can simulate various environmental conditions from room temperature to 300°C, meeting the dynamic mechanical properties test requirements of the specimens under thermal coupling conditions.

[0030] (2) Not only is the design reasonable and the structure simple, but the layout of key components is also optimized. The combination of flange linear bearings and precision guide plates provides a highly stable and precise reciprocating linear excitation for the test bench. The force sensor and displacement sensor are both arranged outside the temperature control box. Effective heat insulation treatment is performed by using high-performance heat-insulating bakelite materials to avoid sensor performance degradation or data distortion caused by high temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the structure of a multi-station high-temperature dynamic compression fatigue test bench;

[0032] Figure 2 A block diagram of the test control system provided by the present invention;

[0033] Figure 3 It is a schematic diagram of the horizontal plate structure;

[0034] Figure 4 It is a schematic diagram of the multi-station cam structure;

[0035] Figure 5 It is the schematic diagram of the thermal environment box structure;

[0036] Figure 6 is a schematic diagram of the guide plate structure;

[0037] In the figure: 1-base, 2-lifting seat, 3-lifting column, 4-thermal environment chamber, 5-test sample, 6-cross plate, 7-servo motor, 8-flexible coupling, 9-T-type vertical bearing seat, 10-guide plate, 11-guide bracket, 12-cylindrical pin, 13-multi-station transmission shaft, 14-cam, 15-grinding block, 16-radial rolling bearing, 17-spring, 18-push rod, 19-flange linear bearing, 20-piezoelectric force sensor, 21-displacement measurement plate, 22-thermal insulation bakelite, 23-tooling fixture, 24-control computer. DETAILED DESCRIPTION

[0038] In order to further understand the present invention, the embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the present invention.

[0039] The embodiment of the present invention discloses a multi-station high temperature dynamic compression fatigue test bench, such as Figures 1 to 6 As shown, including:

[0040] A lifting column 3 is provided on the base 1, and a horizontal plate 6 is installed on the upper end of the lifting column 3. A center hole 6c is opened in the center of the horizontal plate 6 for installing a flange linear bearing 19.

[0041] A through hole 6e is opened next to the center hole to facilitate the installation of the eddy current displacement sensor in the limited space in the vertical direction; the cylindrical probe of the eddy current sensor passes through the through hole 6e of the cross plate 6 and is vertically installed above the end face of the displacement measuring plate 21 to convert the displacement signal of the displacement measuring plate 21 into an electrical signal.

[0042] The left and right ends of the transverse plate 6 are provided with threaded mounting holes 6d for the T-shaped vertical bearing seat 9, and the front and rear are provided with through holes 6b which are clearance-matched with the cylindrical pins 12.

[0043] The transverse plate 6 and the base 1 are positioned by the two front and rear cylindrical pins 12 .

[0044] The lifting column 3 is preferably a threaded lifting column.

[0045] Specifically, four threaded holes are provided at the top corners of the base 1 for installing threaded lifting columns, and three threaded holes are arranged equidistantly in the center of the base 1 for installing a fixture 23. In order to install the threaded lifting column on the base 1, a wrench groove is processed on its upper end and is tightened and loosened by a nut.

[0046] The top corners of the transverse plate 6 are provided with four through holes 6a, the size of which is slightly larger than the outer diameter of the spiral lifting column to reserve a certain horizontal adjustment margin, and the lifting height of the transverse plate 6 is adjusted and locked by the nut on the spiral lifting column.

[0047] A thermal environment box 4 is provided between the base 1 and the horizontal plate 6;

[0048] The thermal environment box 4 is a split-body buckle-type structure, the heating resistors in the box are connected in series, and through holes corresponding to multiple stations are designed at the upper and lower ends of the box, and a temperature sensor 26 is arranged inside the box;

[0049] The external wiring inside the box is placed in the stainless steel connecting hinge. The box design adopts a three-layer structure, from the inside to the outside: silicon carbide furnace tiles that are resistant to high temperatures and have excellent thermal conductivity, with alloy resistance wires directly embedded inside to ensure effective transfer and uniform distribution of heat energy, and the heating temperature can reach 300°C; the middle layer uses lightweight and efficient carbon ceramic fiber insulation material to maintain a stable temperature in the box cavity and reduce heat loss; the outer layer is covered with a structurally stable 304 stainless steel sheet to protect the internal structure from the outside environment.

[0050] The push rod 18 is connected to the grinding block 15 at its upper end and passes through the guide plate 10, the spring 17 and the flange linear bearing 19; the flange linear bearing 19 and the guide plate 10 are used to limit the freedom of the push rod 18 so that it can only move in the Z-axis direction, and the spring 17 plays the role of returning the component.

[0051] The lower part of the push rod 18 passes through the top of the thermal environment box 4 and is connected to a fixture 23 disposed in the thermal environment box 4;

[0052] A displacement measuring plate 21 and a piezoelectric force sensor 20 are provided in the middle of the push rod 18; the fixture 23 and the piezoelectric force sensor 20 are connected by heat-insulating bakelite 22, and the thermal conductivity of bakelite is between 0.17 and 0.27 W / (m·K), which effectively isolates the high temperature of the fixture 23 and prevents the temperature from being transferred to the force sensor and causing loss of collected data.

[0053] A T-type vertical bearing seat 9 is provided on the horizontal plate 6, and the multi-station transmission shaft 13 is installed in the radial rolling bearing 16 of the T-type vertical bearing seat 9 through the shaft shoulder positioning;

[0054] Three cams 14 are evenly distributed on the multi-station transmission shaft 13, and keyways are arranged at intervals of 2π / 3 to achieve that the sum of the inertial force vector and the torque vector generated by each cam is zero. In order to ensure that the cam on the shaft is easy to assemble and position, the shaft diameter at the assembly position is larger than the shaft diameter at other positions. Considering that no positioning shoulder is provided and the cam has no axial force, in order to limit the axial movement of the cam, retaining ring grooves are provided on both sides of the assembly position of the cam 14 according to standard GB / T894.1 to install elastic retaining rings for the shaft.

[0055] The profile of the cam 14 is processed according to the law of cosine acceleration motion (also known as the law of simple harmonic motion), and the cam keyway is designed at the radial position corresponding to the maximum thrust hmax. The effect of changing the excitation amplitude can be achieved by replacing cams with different profiles. Considering that the cam 14 and the grinding block 15 interact with each other in a rigid contact manner, violent collisions may occur. In order to reduce the wear rate of the cam, the cam 14 is made of high-hardness alloy steel material and is tempered. Preferably, the material is 40Cr with higher hardness, and is tempered to achieve Rockwell hardness HRC40-45. The grinding block 15 is made of high-resistance alloy steel material that has not been heat-treated. Preferably, the material of the grinding block 15 is 40Cr, and no heat treatment is performed.

[0056] The cam 14 is used to generate longitudinal displacement excitation;

[0057] The cam 14 and the grinding block 15 are in high-pair contact;

[0058] A servo motor 7 is provided on the lifting seat 2, and the rotating shaft of the servo motor 7 is connected to the multi-station transmission shaft 13 through a flexible coupling 8;

[0059] The servo motor 7 is installed on the lifting seat 2 through a horizontal fixed bracket, and the lifting seat 2 adopts a turbine to achieve stepless adjustment of height.

[0060] The control computer 24 is used to collect temperature data in real time using a temperature sensor, and implement heating control on the thermal environment box 4 according to the temperature data, collect signals from the piezoelectric force sensor 20 and the eddy current displacement sensor, and control the movement of the servo motor according to the analysis of the pressure and displacement signals.

[0061] The control computer 24 starts and controls the operation of the servo motor through the servo motor controller to achieve frequency control of 1 to 30 Hz, and then uses a flexible coupling to efficiently transmit the torque of the servo motor main shaft to the multi-station transmission shaft.

[0062] The operation process of the multi-station high temperature dynamic compression fatigue test bench of the present invention is as follows:

[0063] The height of the cross plate 6 and its mounting components are adjusted according to the clamping height of the test sample 5, and the cross plate 6 is aligned and positioned with the base plate 1 by the front and rear cylindrical pins 12, and then locked with nuts.

[0064] The main shaft of the servo motor 7 is adjusted to a corresponding height of the multi-station transmission shaft 13 by using the lifting seat 2, the servo motor 7 and the multi-station transmission shaft 13 are connected by the flexible coupling 8, and then the servo motor 7 is fixed by bolts.

[0065] The solid-state relay is controlled by the program of the control computer 24 to start or cut off the heating of the thermal environment box 4, and the temperature sensor is used to collect temperature data in real time. In order to prevent the thermal environment box from switching too frequently when it is close to the set target temperature, a temperature adjustment threshold is designed according to the test requirements to allow a certain range of temperature fluctuations. Only when the real-time temperature exceeds this range will the system start or stop the heating process.

[0066] The servo motor controller starts and controls the operation of the servo motor 7 to achieve frequency control of 1 to 30 Hz, and then the flexible coupling 8 is used to efficiently transmit the torque of the motor main shaft to the multi-station transmission shaft 13. The flexible coupling 8 can also compensate for the installation misalignment error between the motor main shaft and the transmission shaft, and has a certain vibration reduction and buffering effect.

[0067] The three cams 14 evenly distributed on the multi-station transmission shaft 13 convert the rotary motion into reciprocating linear motion. When the cam 14 is at the push angle, the excitation assembly compresses the test sample 5; when it is at the return angle, the push rod 18 is reset under the elastic force of the spring 17. There is a high-pair contact between the cam 14 and the grinding block 15, and the friction force is small, but there is still a certain component force in the horizontal direction. In order to eliminate the influence of this component force, the following design is used Figure 6 The guide plate 10 shown in the figure cooperates with the flange linear bearing 19 so that the push rod 18, the cam 14 and the multi-station transmission shaft 13 can achieve stable linear vibration only in the Z-axis direction.

[0068] The piezoelectric force sensor 20 generates a corresponding electrical signal according to the change in the set load; the cylindrical probe of the eddy current sensor passes through the through hole of the horizontal plate 6 and is vertically installed above the end surface of the displacement measuring plate 21, converting the displacement signal of the displacement measuring plate 21 into an electrical signal; the dynamic data collector collects and transmits the above two real-time electrical signals, and controls the computer 24 to receive and process the signals of the temperature acquisition card and the dynamic data collector, so as to obtain the various data required for material testing, and then draw various function relationship diagrams characterizing the characteristics of the specimen.

[0069] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0070] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multi-station high temperature dynamic compression fatigue test bench, characterized in that: include: A lifting column is arranged on the base, and a horizontal plate is installed on the upper end of the lifting column. A center hole is opened in the center of the horizontal plate for installing a flange linear bearing. A through hole is provided next to the central hole to install an eddy current displacement sensor; A thermal environment box is provided between the base and the horizontal plate; The upper and lower ends of the thermal environment box are designed with through holes corresponding to the multiple stations, and temperature sensors are set inside; A push rod, the upper end of which is connected to the grinding block and passes through the guide plate, spring and flange linear bearing; The lower part of the push rod passes through the top of the thermal environment box and is connected to a fixture disposed in the thermal environment box; A displacement measuring plate and a piezoelectric force sensor are arranged in the middle of the push rod; A T-type vertical bearing seat is arranged on the horizontal plate, and the multi-station transmission shaft is installed in the radial rolling bearing of the T-type vertical bearing seat through the shaft shoulder positioning; Three cams are evenly spaced on the multi-station transmission shaft, and keyways are arranged at intervals of 2π / 3. The cam and the grinding block are in high-pair contact; A servo motor is arranged on the lifting seat, and the rotating shaft of the servo motor is connected to the multi-station transmission shaft through a flexible coupling; The control computer is used to collect temperature data in real time using the temperature sensor, and implement heating control of the thermal environment box according to the temperature data, collect piezoelectric force sensor signals and eddy current displacement sensor signals, and control the movement of the servo motor according to the analysis of pressure and displacement signals.

2. The multi-station high temperature dynamic compression fatigue test bench according to claim 1 is characterized in that: The top corners of the base are provided with four threaded holes for installing threaded lifting columns, the top corners of the cross plate are provided with through holes with a diameter slightly larger than the outer diameter of the threaded lifting columns, and the base and the cross plate are adjusted, positioned and installed by nuts.

3. The multi-station high temperature dynamic compression fatigue test bench according to claim 1 is characterized in that: It also includes cylindrical pins, and the cross plate and the base are positioned by two front and rear cylindrical pins.

4. The multi-station high temperature dynamic compression fatigue test bench according to claim 1 is characterized in that: The control computer starts and controls the operation of the servo motor through the servo motor controller to achieve frequency control of 1 to 30 Hz, and then uses a flexible coupling to efficiently transmit the torque of the servo motor main shaft to the multi-station transmission shaft.

5. The multi-station high temperature dynamic compression fatigue test bench according to claim 1 is characterized in that: The cylindrical probe of the eddy current sensor passes through the through hole of the horizontal plate and is vertically installed above the end surface of the displacement measuring plate to convert the displacement signal of the displacement measuring plate into an electrical signal.

6. The multi-station high temperature dynamic compression fatigue test bench according to claim 1 is characterized in that: The fixture and the piezoelectric force sensor are connected by using heat-insulating bakelite.

7. The multi-station high temperature dynamic compression fatigue test bench according to claim 1 is characterized in that: The thermal environment box is a split-type structure, and the heating resistors in the box are connected in series; the box design adopts a three-layer structure, from the inside to the outside: silicon carbide furnace tiles, with alloy resistance wires directly embedded inside; the middle layer uses carbon ceramic fiber insulation material; and the outer layer is covered with 304 stainless steel sheets.

8. The multi-station high temperature dynamic compression fatigue test bench according to claim 1 is characterized in that: Circlip grooves are arranged on both sides of the cam assembly position for installing elastic circlips for the shaft.

9. The multi-station high temperature dynamic compression fatigue test bench according to claim 1 is characterized in that: The cam is made of high-hardness alloy steel material and has been subjected to quenching and tempering treatment, and the grinding block is made of high-hardness alloy steel material that has not been heat-treated.

10. The multi-station high temperature dynamic compression fatigue test bench according to claim 1, characterized in that: The cam profile is processed according to the cosine acceleration motion law, and the cam keyway is designed at a radial position corresponding to the maximum thrust stroke hmax. The effect of changing the excitation amplitude can be achieved by replacing cams with different profiles.

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