Asphalt mixture performance testing machine

Abstract

The utility model discloses an asphalt mixture performance testing machine which comprises a machine body, a hydraulic system and a control system, an upper objective table and a lower objective table are arranged on the machine body, and an asphalt mixture test piece to be tested is arranged on the lower objective table and clamped between the upper objective table and the lower objective table; the hydraulic system comprises a hydraulic station, a hydraulic cylinder and a high-frequency electromagnetic valve, the hydraulic station provides hydraulic power for the hydraulic cylinder, the high-frequency electromagnetic valve controls the action direction of the hydraulic cylinder, and a piston rod of the hydraulic cylinder is connected with the lower loading table and can drive the lower loading table to move up and down; the control system comprises a control card, a controller and sensors, the controller is in communication connection with the control card, the control card is in communication connection with the high-frequency electromagnetic valve, the sensors are arranged on the action part and the test piece, and the controller sends action instructions to the high-frequency electromagnetic valve through the control card and receives feedback values of the sensors at the same time, so that the control system forms signal closed-loop control. The hydraulic cylinder is controlled through the control card and the high-frequency electromagnetic valve, and the precision of test data is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of automatic control performance detection, and particularly relates to a machine capable of testing the performance of asphalt mixture through automatic control. Background Technique

[0002] At present, it is necessary to test asphalt mixture to check the changes of its various performances over time under long-term compression, so as to determine its service life, so that timely repair can be carried out, and the maintenance cycle and cost can be predicted in advance. However, the existing machines cannot achieve automatic control, and the accuracy coefficient is not high, resulting in insufficient accuracy of test data, thus causing conclusion deviation, affecting the budget, and road safety.

[0003] Therefore, how to solve the above problems and improve the automatic control level of the test process and the accuracy of test data is an urgent problem to be solved in the industry. Summary of the Utility Model

[0004] A main object of the utility model is to provide an asphalt mixture performance testing machine capable of improving the automatic control level of the test process and the accuracy of test data.

[0005] To achieve the above utility model object, the utility model adopts the following technical solutions:

[0006] As an aspect of the utility model, an asphalt mixture performance testing machine is provided, including:

[0007] A machine body, on which an upper loading platform and a lower loading platform are arranged, and the asphalt mixture test piece to be tested is placed on the lower loading platform and clamped between the upper loading platform and the lower loading platform;

[0008] A hydraulic system, which includes a hydraulic station, a hydraulic cylinder and a high-frequency solenoid valve. The hydraulic station provides hydraulic power for the hydraulic cylinder, the high-frequency solenoid valve controls the action direction of the hydraulic cylinder, and the piston rod of the hydraulic cylinder is connected to the lower loading platform and can drive the lower loading platform to move up and down;

[0009] A control system, which includes a control card, a controller and sensors. The controller is communicatively connected to the control card, the control card is communicatively connected to the high-frequency solenoid valve, the sensors are arranged on the moving parts and the test piece, and the controller sends an action instruction to the high-frequency solenoid valve through the control card, and at the same time receives the feedback value of the sensor, so that the control system forms a closed-loop control of the signal.

[0010] As an embodiment of the present utility model, the machine body includes a three-axis positioning structure, which is connected between the upper loading platform and the lower loading platform, and can enable the upper loading platform and the lower loading platform to move coaxially relative to each other up and down in the vertical plane.

[0011] As an embodiment of the present utility model, the three-axis positioning structure includes three vertically arranged guiding shafts. The lower ends of the guiding shafts are fixedly connected to the lower loading platform, and the upper ends pass through the upper loading platform and are slidably sleeved with the upper loading platform.

[0012] As an embodiment of the present utility model, the three guiding shafts are evenly arranged in the circumferential direction.

[0013] As an embodiment of the present utility model, the sensors include a pressure sensor, a position sensor, and a strain sensor. The pressure sensor is arranged between the piston rod and the lower loading platform, the position sensor is arranged at the bottom of the piston rod, and the strain sensor is arranged around the test piece.

[0014] As an embodiment of the present utility model, there are three strain sensors, which are evenly arranged at equal angles in the circumferential direction.

[0015] As an embodiment of the present utility model, positioning pins are arranged on the test piece. There are three groups of positioning pins, which are evenly arranged at equal angles in the circumferential direction of the test piece. Each group of positioning pins includes one upper and one lower piece. A fixing clip is connected to each positioning pin, and a support frame is connected to the fixing clip. The strain sensor is installed between the two support frames.

[0016] As an embodiment of the present utility model, the positioning pins are uniformly fixed and bonded to the outer circumferential surface of the test piece through a concentric positioning and installation device. The concentric positioning and installation device includes three output parts that move synchronously and concentrically. The output parts press the positioning pins against the test piece.

[0017] As an embodiment of the present utility model, the upper loading platform and the lower loading platform are buckled in the environmental chamber, and a temperature control system is arranged in the environmental chamber.

[0018] As an embodiment of the present utility model, the temperature control system includes a water cooling device. The water cooling device includes a water cooling tank, a refrigerating machine, and heat dissipation fins. The water cooling tank has water inlet and outlet ports and circulates with the refrigerating machine. A refrigerating sheet is arranged inside the water cooling tank to provide a cold source; heating tubes are installed inside the heat dissipation fins; fans are evenly distributed on the heat dissipation fins.

[0019] It can be seen from the above technical solutions that the advantages and positive effects of the asphalt mixture performance testing machine of the present utility model are as follows:

[0020] In this utility model, a high-frequency solenoid valve is used to control a hydraulic cylinder to drive a downloading platform to extrude a test piece, and an instruction is sent to the high-frequency solenoid valve through a control card, so as to improve the automatic control level of the test process and the accuracy of test data. Brief Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the prior art. Obviously, the drawings described below are only some embodiments recorded in the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to these drawings.

[0022] Figure 1 It is a schematic diagram of the overall structure of the asphalt mixture performance testing machine of the present utility model.

[0023] Figure 2 It is a schematic diagram of the structure in which a test piece is positioned through a concentric positioning and installation device in the asphalt mixture performance testing machine of the present utility model.

[0024] Figure 3 It is Figure 2 the schematic A-sectional view in

[0025] Figure 4 It is a schematic diagram of the viewing state of a test piece in the asphalt mixture performance testing machine of the present utility model.

[0026] Figure 5 It is a schematic sectional view of the test state of a test piece in the asphalt mixture performance testing machine of the present utility model.

[0027] Figure 6 It is a schematic diagram of the overall structure in the test state of the asphalt mixture performance testing machine of the present utility model.

[0028] Figure 7 It is a three-dimensional schematic diagram of a positioning pin arranged on a test piece in the asphalt mixture performance testing machine of the present utility model.

[0029] Figure 8 It is a top view schematic diagram of a positioning pin arranged on a test piece in the asphalt mixture performance testing machine of the present utility model.

[0030] Figure 9 It is a schematic diagram of the control principle in the asphalt mixture performance testing machine of the present utility model. Detailed Embodiments

[0031] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, the exemplary embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this utility model will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. Like reference numerals in the figures denote like or similar structures, and thus their detailed description will be omitted.

[0032] In the following description of different examples of this utility model, reference is made to the accompanying drawings, which form a part of this utility model, and in which are shown, by way of example, different exemplary structures, systems, and steps by which various aspects of this utility model can be implemented. It should be understood that other specific solutions of components, structures, exemplary devices, systems, and steps can be used, and structural and functional modifications can be made without departing from the scope of this utility model. Moreover, although terms such as "top", "bottom", "front", "rear", "side", etc. may be used in this specification to describe different exemplary features and elements of this utility model, these terms are used herein for convenience only, for example, the orientation of the examples as shown in the drawings. Nothing in this specification should be construed as requiring a specific three-dimensional orientation of the structure to fall within the scope of this utility model.

[0033] Figure 1 It is a schematic diagram of the overall structure of the asphalt mixture performance testing machine of this utility model.

[0034] Figure 2 It is a schematic diagram of the structure in which the test piece in the asphalt mixture performance testing machine of this utility model is positioned by the concentric positioning installation device.

[0035] Figure 3 is Figure 2 the schematic sectional view in the A direction in

[0036] Figure 4 It is a schematic view of the viewing state of the test piece in the asphalt mixture performance testing machine of this utility model.

[0037] Figure 5 It is a schematic sectional structure view of the test state of the test piece in the asphalt mixture performance testing machine of this utility model.

[0038] Figure 6 It is a schematic diagram of the overall structure in the test state of the asphalt mixture performance testing machine of this utility model.

[0039] Figure 7 It is a three-dimensional structure schematic diagram of the positioning pin arranged on the test piece in the asphalt mixture performance testing machine of this utility model.

[0040] Figure 8This is a top view structural schematic diagram of a positioning pin provided on a test piece in the asphalt mixture performance testing machine of the present utility model.

[0041] Figure 9 This is a schematic diagram of the control principle in the asphalt mixture performance testing machine of the present utility model.

[0042] As Figures 1 to 9 shown, the present utility model provides an asphalt mixture performance testing machine, including:

[0043] A machine body 1, on which an upper loading platform 13 and a lower loading platform 12 are provided. The asphalt mixture test piece 5 to be tested is placed on the lower loading platform 12 and clamped between the upper loading platform 13 and the lower loading platform 12.

[0044] A hydraulic system 3, which includes a hydraulic station 32, a hydraulic cylinder 2, and a high-frequency solenoid valve 31. The hydraulic station 31 provides hydraulic power for the hydraulic cylinder 2, and the high-frequency solenoid valve 31 controls the action direction of the hydraulic cylinder 2. The piston rod 21 of the hydraulic cylinder 2 is connected to the lower loading platform 12 and can drive the lower loading platform 12 to move up and down.

[0045] A control system 4, which includes a control card 41, a controller 42, and a sensor 51. The controller 42 is communicatively connected to the control card 41, the control card 41 is communicatively connected to the high-frequency solenoid valve 31, and the sensor 51 is arranged on the moving part and the test piece 5. The controller 42 sends an action instruction to the high-frequency solenoid valve 31 through the control card 41 and simultaneously receives the feedback value of the sensor 51, so that the control system forms a closed-loop control of the signal. The moving part can be the piston rod 21.

[0046] In an embodiment of the present utility model, the control system enables a sinusoidal pressure wave to act on both ends of the test piece 5 through the PID algorithm.

[0047] In an embodiment of the present utility model, after the test piece is subjected to a sinusoidal stress, a sinusoidal strain is generated. By analyzing the stress-strain relationship, the dynamic modulus and phase angle of the test piece are calculated.

[0048] In an embodiment of the present utility model, the feedback signal in the control system is provided by an external ADC module.

[0049] In an embodiment of the present utility model, the machine body 1 includes a three-axis positioning structure, which is connected and arranged between the upper loading platform 13 and the lower loading platform 12 and can enable the upper loading platform 13 and the lower loading platform 12 to move coaxially relative to each other up and down in the vertical plane.

[0050] In an embodiment of the present utility model, the three-axis positioning structure includes three vertically arranged guiding shafts 14. The lower ends of the guiding shafts 14 are fixedly connected to the lower loading platform 12, and the upper ends pass through the upper loading platform 13 and are slidably sleeved with the upper loading platform 13.

[0051] In an embodiment of the present utility model, the three guiding shafts 14 are evenly arranged in the circumferential direction.

[0052] In an embodiment of the present utility model, the sensor includes a pressure sensor, a position sensor and a strain sensor. The pressure sensor is arranged between the piston rod 21 and the download stage 12, the position sensor is arranged at the bottom of the piston rod 21, and the strain sensor is arranged around the test piece 5.

[0053] In an embodiment of the present utility model, there are three strain sensors 51, which are evenly arranged at equal angles in the circumferential direction.

[0054] In an embodiment of the present utility model, positioning pins 6 are arranged on the test piece 5. There are three groups of positioning pins 6, which are evenly arranged at equal angles in the circumferential direction of the test piece 5. Each group of positioning pins 6 includes one piece at the upper and lower parts. A fixing clip is connected to each positioning pin 6, and a support frame is connected to the fixing clip. The strain sensor 51 is installed between the two support frames.

[0055] In an embodiment of the present utility model, the positioning pins 6 are evenly fixed and bonded to the outer circumferential surface of the test piece 5 through a concentric positioning and installation device 8. The concentric positioning and installation device 8 includes three output parts 84 that move synchronously and concentrically. The output parts 84 press the positioning pins 6 against the test piece 5.

[0056] In an embodiment of the present utility model, the concentric positioning and installation device includes:

[0057] A frame 80, the frame 80 is a cylindrical shell, including an outer peripheral surface 801, an upper end surface 802 and a base 803. The test piece 5 is arranged between the upper end surface 802 and the base 803 and is coaxial with the frame 80;

[0058] A synchronous pulley 81, the synchronous pulley 81 is rotatably installed on the upper end surface 802 and is coaxial with the frame 80. Two or more synchronous connecting rods 82 are arranged on the synchronous pulley 81. The two or more synchronous connecting rods 82 are evenly distributed and the symmetry center is located on the axis of the synchronous pulley 81;

[0059] Guide blocks 83, there are two or more guide blocks 83, corresponding to the synchronous connecting rods 82 one by one, and are fixedly arranged at the ends of the synchronous connecting rods 82, located inside the outer peripheral surface, and the symmetry center is located on the center line of the frame 80;

[0060] Output parts 84, there are two or more output parts 84, corresponding to the guide blocks 83 one by one. The output parts 84 pass through the outer peripheral surface 801 and the guide blocks 83 at the same time. The radial output position of the output parts 84 is determined, and the output ends of the output parts 84 are connected with the positioning pins 6. The positioning pins 6 are synchronously bonded to the test piece 5 under the drive of the output parts 84.

[0061] In an embodiment of the present utility model, the outer peripheral surface of the frame 80 is a hollow structure.

[0062] In an embodiment of the present utility model, there are three synchronous link rods 82, guide blocks 83, and output parts 84 respectively. The output part 84 includes upper and lower layers of output ends, and there are six positioning pins 6, which correspond to the output ends one by one.

[0063] In an embodiment of the present utility model, the concentric positioning and mounting device 8 further includes a lifting and pressing column 86 and an upper pressing plate. The lifting and pressing column 86 passes through the shaft hole of the synchronous pulley 81 and is connected to the upper pressing plate, and the upper pressing plate presses against the test piece 5.

[0064] In an embodiment of the present utility model, a guide seat 87 is also sleeved outside the lifting and pressing column 86, and the guide seat 87 is located above the synchronous pulley 81.

[0065] In an embodiment of the present utility model, the synchronous link rod 82 is L-shaped, one end is connected to the synchronous pulley 81, and the other end extends outwards beyond the synchronous pulley 81.

[0066] In an embodiment of the present utility model, the output part 84 includes a guide shaft 842 and a guide fixing block 841. The guide shaft 842 is installed on the guide fixing block 841. The end of the guide shaft 842 forms an output end, and a spring 843 is sleeved on the part of the guide shaft 842 between the guide fixing block 841 and the outer peripheral surface 801.

[0067] In an embodiment of the present utility model, a positioning pin clamping piece is arranged at the output end to clamp the positioning pin 6.

[0068] In an embodiment of the present utility model, the concentric positioning and mounting device 8 includes a locking rod 88 and a ejector rod 89. The locking rod 88 is threadedly connected and passes through the guide block 83 to abut against the test piece 5, and the ejector rod 89 cooperates with the locking rod 88 to abut against the other side of the test piece 5.

[0069] In an embodiment of the present utility model, the upper loading platform 13 and the lower loading platform 12 are buckled in the environmental chamber, and a temperature control system is arranged in the environmental chamber.

[0070] In an embodiment of the present utility model, the temperature control system includes a water cooling device. The water cooling device includes a water cooling tank, a refrigerating machine, and heat dissipation fins. The water cooling tank has water inlets and outlets and circulates with the refrigerating machine. A refrigerating sheet is arranged in the water cooling tank to provide a cold source; a heating pipe is installed in the heat dissipation fins; fans are evenly distributed on the heat dissipation fins.

[0071] This process includes the following parts:

[0072] 1. Apply a sinusoidal axial compressive stress test load to the test piece.

[0073] 2. Use a pressure sensor for closed-loop feedback and simultaneously obtain the actual pressure value.

[0074] 3. Divide the pressure value by the cross-sectional area of the test piece to obtain the stress on the test piece.

[0075] 4. After the test piece receives pressure, it will deform, and the waveform of the deformation is the same as the pressure waveform.

[0076] 5. Divide the deformation by the total height of the test piece to obtain the strain value.

[0077] 6. Stress / Strain = Dynamic modulus.

[0078] 7. The stress and strain are waveforms with the same frequency, but due to different materials, there is a phase difference between the two waveforms. By comparing the two waveforms, the phase difference can be obtained.

[0079] 8. The magnitude of the dynamic modulus reflects the strength of the material.

[0080] 9. The phase difference reflects the elastic properties of the material.

[0081] In an embodiment of the present utility model, the sensor 51 includes a pressure sensor, a position sensor, and a strain sensor. The pressure sensor is disposed between the piston rod 21 and the lower loading table 12. The position sensor is disposed at the bottom of the piston rod 21, and the strain sensor is disposed around the test piece 5.

[0082] Three strain sensors (Lvdt1, Lvdt2, Lvdt3) are installed around the test piece 5 along a 120° distribution. An environmental chamber 11 is installed on the workbench surface, which can control the temperature to ensure that a temperature environment meeting the requirements is provided for the test piece 5. The PC software in the controller 42 sends required instructions to the control card 41. The control card 41 controls the action of the high-frequency solenoid valve 31 and simultaneously receives the feedback values of the pressure sensor, the spindle position sensor, and the Lvdt1..3 sensors. The test piece 5 is synchronously positioned through the concentric positioning and mounting device 16 to achieve precise positioning.

[0083] In an embodiment of the present utility model, there are three strain sensors, which are evenly arranged at equal angles along the circumferential direction.

[0084] In an embodiment of the present utility model, the controller 42 is disposed in a computer, and the sensor 51 inputs signals into the computer through an acquisition card.

[0085] In an embodiment of the present utility model, the high-frequency solenoid valve 31 is an electro-hydraulic proportional valve. The input control signal of the electro-hydraulic proportional valve is in a direct proportional relationship with the output oil pressure, and the output hydraulic value of the high-frequency solenoid valve 31 is controlled by the signal input value sent by the control card 41.

[0086] For the mechanical testing instrument developed by the present utility model, the control precision of the pressure wave is the key core. Only when the load waveform applied to the test piece 5 is sufficiently close to the set standard waveform can the actual working conditions of the instrument fully conform to the data processing model.

[0087] The core devices for achieving high-precision control are mainly the high-frequency solenoid valve 31, the control card 41, and the pressure sensor 51. The high-frequency solenoid valve 31 is an electro-hydraulic proportional valve. The valve input control signal is in a direct proportional relationship with the output oil pressure. The output hydraulic value of the high-frequency solenoid valve 31 is controlled by the signal input value given by the control card 41. The pressure sensor 51 then converts the pressure received by the test piece 5 into an electrical signal in real time and inputs it into the control computer through the acquisition card, forming a closed-loop control of control-signal input.

[0088] After the execution device control and feedback form a closed loop, the PID control method is introduced to achieve precise air pressure control. PID control is a digital control algorithm based on the control theories of proportion, integration, and derivative. It adjusts the three PID parameters to regulate the response of the system, making the system have good dynamic characteristics and steady-state performance. The essence of integration is to integrate the error signal to gradually reduce the integration error and make the system more stable. The essence of differentiation is to prevent the system from overresponding to external interference. The PID control principle is to adjust the proportional gain according to the deviation between the output value and the input value so that the system can reach the input set value. When the deviation between the output and the input increases, the proportional gain is increased; conversely, when the deviation between the output and the input is small, the proportional gain is decreased.

[0089] There are two types of PID algorithms: one is the position type and the other is the incremental type. The incremental type formula is adopted for pressure wave control, and its incremental formula is:

[0090] PID = Uk + KP * [E(k) - E(k - 1)] + KI * E(k) + KD * [E(k) - 2E(k - 1) + E(k - 2)]

[0091] In the formula, E(k) represents the current error, E(k - 1) represents the error at the previous moment, and E(k - 2) represents the error at the moment before E(k - 1). These error data are updated in real time during the calculation process.

[0092] The implementation of the pressure wave control algorithm is completed using the STM32F407 series single-chip microcomputer. The STM32F407 is a 32-bit high-performance ARM Cortex-M4 processor with a system clock as high as 168 MHz. It supports FPU (floating-point budget) and DSP instructions.

[0093] To ensure the sampling accuracy, the feedback signal in the pressure wave control system is provided by an external ADC module, whose sampling accuracy is better than four ten-thousandths, ensuring the sampling accuracy.

[0094] The above PID control process is as Figure 9 shown.

[0095] In this experiment, the test piece 5 is subjected to controlled sinusoidal compressive stresses at different frequencies at a specific test temperature. The applied stress and the resulting axial strain are measured as a function of time and used to calculate the dynamic modulus and phase angle. The dynamic modulus is used to evaluate the performance of asphalt mixtures, characterize and evaluate the stiffness of asphalt mixtures, for the mechanical empirical design of pavements, draw the dynamic modulus curve for pavement structure design, and can also be used to analyze the causes of pavement cracking. The flow value is an attribute related to the resistance of asphalt mixture pavements to permanent deformation, and is used to evaluate and design the ability of asphalt mixture pavements to resist permanent deformation. The damage characteristic curve can reflect the basic relationship between the damage and integrity of asphalt mixtures, and this characteristic is independent of temperature, frequency and loading mode. Combining with the linear viscoelastic properties of asphalt mixtures, the damage characteristic curve can be used to evaluate the fatigue characteristics of asphalt mixtures. Combining with the fatigue failure principle and pavement response model can predict the fatigue characteristics of in-service pavements.

[0096] As an embodiment of the present utility model, the upper stage 13 and the lower stage 12 are mutually guided and connected through a guide shaft 14, so that only relative up-and-down movement is possible between the upper stage 13 and the lower stage 12. The present utility model uses three columns to install circular plates 15 / 16 up and down, ensuring concentricity. The hydraulic main body is installed at the bottom of the concentric lower plate, the hydraulic rod is extended, and a loading force is applied. A pressure sensor is installed on the hydraulic rod, a test piece fixing plate is installed on the lower bottom plate, and an oil sealing groove is provided. Sealing rings are installed on the outer surface. The environmental chamber 11 can be automatically raised and lowered by a pneumatic control method, and the cavity is kept sealed after descending. The guide shaft 14 adopts three-axis vertical positioning, more stable to ensure concentricity. Sealing grooves are machined on the inner walls of the upper and lower fixing rings and the outer circular ring surfaces, and sealing rings are installed. The outer sealing ring contacts the inner wall of the outer perspective cover, and the inner sealing ring contacts the inner perspective cover, ensuring the sealing of the double-layer perspective cover. The double-layer perspective cover can be evacuated, making it easier to control temperature and keep warm.

[0097] The environmental chamber 11 adopts a temperature control system, and the temperature control system adopts a water cooling device, in which the water cooling tank has water inlet and outlet ports and circulates with the refrigerator. A refrigeration chip is built in the water cooling tank to provide a cold source; heating tubes are installed in the heat dissipation fins; fans are evenly distributed on the fins, and the chamber is evenly cooled. The refrigerator, refrigeration chip and heating tube are controlled by a program to start and stop, ensuring the refrigeration rate and reaching the required low temperature for the experiment.

[0098] The installation of the sensor 51 on the test piece 5 of the present utility model further includes the following content:

[0099] 1. The refrigeration component upper water tank plate is installed on the loading shaft to ensure the central position.

[0100] 2. The lower loading device is installed at the center position of the upper plate of the frame assembly.

[0101] 3. During the test, the upper loading plate is placed on the upper surface of the test piece to ensure concentric position.

[0102] 4. Positioning blocks need to be evenly bonded to the circumferential surface of the test piece.

[0103] 5. Install the LVDT displacement sensor on the axial positioning block to monitor the displacement change during the experiment.

[0104] In the present utility model, the positioning pins are evenly bonded to the circumferential surface of the test piece 5 to ensure uniform distribution of positions. The test piece is placed at the center of the fixed sleeve, and the lower base has a positioning step hole to ensure concentric positioning. The triple-link rods move towards the center of the circle simultaneously to ensure that the positioning pins contact and bond with the test piece 5. Finally, the upper pressing plate presses down to the surface of the test piece 5, and the height and uniform distribution of the bonding positions of the positioning pins and the test piece are very important for the dynamic experimental data. The displacement change in the dynamic experiment is less than 1 mm.

[0105] Generally speaking, in an embodiment of the present utility model, it mainly includes the following parts:

[0106] 1. Pressure load part (hydraulic cylinder, hydraulic valve); apply pressure to the test piece, which is realized by controlling the hydraulic cylinder through the hydraulic valve.

[0107] 2. Simulated environmental temperature part (methods for high temperature and low temperature); control the temperature of the test environment of the test piece through the temperature control part.

[0108] 3. Strain measurement part (main shaft displacement, auxiliary shaft displacement); measure the strain of the test piece and the displacement of the piston rod through sensors and transmit them to the control system.

[0109] 4. Test piece installation part (design of concentric positioning installation device); the test piece needs to be accurately positioned, and its position accuracy is ensured through a delicately designed concentric positioning installation device.

[0110] 5. Hydraulic station part (hydraulic station main body, hydraulic station cooling); the hydraulic station provides power for the pressure load part.

[0111] 6. Method for realizing the opening and closing of the environmental chamber (cylinder); realize the opening and closing through automatic lifting to improve the degree of automatic control.

[0112] From the above technical solutions, the advantages and positive effects of the asphalt mixture performance testing machine of the present utility model are as follows:

[0113] In the present utility model, a high-frequency solenoid valve 31 is adopted to control a hydraulic cylinder 2 to drive a downloading table 12 to extrude a test piece 5, and an instruction is sent to the high-frequency solenoid valve 31 through a control card 41, so as to improve the automatic control level of the test process and improve the accuracy of test data.

[0114] Those of ordinary skill in the art to which the present utility model pertains should understand that the specific structures and technological processes shown in the above specific implementation part are merely exemplary, rather than restrictive. Moreover, those of ordinary skill in the art to which the present utility model pertains can combine the various technical features shown above in various possible ways to form new technical solutions, or make other modifications, all of which fall within the scope of the present utility model.

Claims

1. An asphalt mixture performance testing machine, characterized in that, Including: A machine body, on which an upper loading platform and a lower loading platform are arranged. The asphalt mixture test piece to be tested is placed on the lower loading platform and clamped between the upper loading platform and the lower loading platform. A hydraulic system, which includes a hydraulic station, a hydraulic cylinder, and a high-frequency solenoid valve. The hydraulic station provides hydraulic power for the hydraulic cylinder. The high-frequency solenoid valve controls the action direction of the hydraulic cylinder. The piston rod of the hydraulic cylinder is connected to the lower loading platform and can drive the lower loading platform to move up and down. A control system, which includes a control card, a controller, and sensors. The controller is communicatively connected to the control card. The control card is communicatively connected to the high-frequency solenoid valve. The sensors are arranged on the moving parts and the test piece. The controller sends action instructions to the high-frequency solenoid valve through the control card and simultaneously receives the feedback values of the sensors, so that the control system forms a closed-loop control of signals.

2. The asphalt mixture performance testing machine according to claim 1, wherein: The machine body includes a three-axis positioning structure, which is connected between the upper loading platform and the lower loading platform and can enable the upper loading platform and the lower loading platform to move coaxially relative to each other up and down in the vertical plane.

3. The asphalt mixture performance testing machine according to claim 2, characterized in that: The three-axis positioning structure includes three vertically arranged guiding shafts. The lower ends of the guiding shafts are fixedly connected to the lower loading platform, and the upper ends pass through the upper loading platform and are slidably sleeved with the upper loading platform.

4. The asphalt mixture performance testing machine according to claim 3, characterized in that: The three guiding shafts are evenly arranged in the circumferential direction.

5. The asphalt mixture performance testing machine according to claim 1, characterized in that: The sensors include a pressure sensor, a position sensor, and a strain sensor. The pressure sensor is arranged between the piston rod and the lower loading platform. The position sensor is arranged at the bottom of the piston rod. The strain sensor is arranged around the test piece.

6. The asphalt mixture performance testing machine according to claim 5, characterized in that: There are three strain sensors, which are evenly arranged at equal angles in the circumferential direction.

7. The asphalt mixture performance testing machine according to claim 6, wherein: Positioning pins are arranged on the test piece. There are three groups of positioning pins, which are evenly arranged at equal angles in the circumferential direction of the test piece. Each group of positioning pins includes one upper and one lower piece. A fixing clamp is connected to each positioning pin, and a support frame is connected to the fixing clamp. The strain sensor is installed between the two support frames.

8. The asphalt mixture performance testing machine according to claim 7, characterized in that: The positioning pins are uniformly fixed and bonded to the outer circumferential surface of the test piece through a concentric positioning installation device. The concentric positioning installation device includes three output parts that move synchronously and concentrically. The output parts press the positioning pins against the test piece.

9. The asphalt mixture performance testing machine according to claim 1, characterized in that: The upper loading platform and the lower loading platform are buckled in an environmental chamber, and a temperature control system is arranged in the environmental chamber.

10. The asphalt mixture performance testing machine according to claim 9, wherein: The temperature control system includes a water cooling device, which includes a water cooling tank, a refrigerating machine, and heat dissipation fins. The water cooling tank has water inlet and outlet ports and circulates with the refrigerating machine. A refrigerating sheet is arranged inside the water cooling tank to provide a cold source. Heating tubes are installed in the heat dissipation fins. Fans are evenly distributed on the heat dissipation fins.

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