Pressure measuring device and calibration system for large-size large-tonnage flexible flat actuator

Abstract

The invention discloses a pressure measuring device and a calibration system for a large-size large-tonnage flexible flat actuator. The device comprises a monitoring unit, a partial load unit and a retainer, the monitoring units are distributed in an array mode and used for bearing and monitoring pressure, each monitoring unit comprises a multi-cylinder assembly, a first round end socket and an LVDT displacement sensor, the multi-cylinder assembly is composed of a plurality of first cylinders which are concentrically sleeved together at intervals, the two ends of each first cylinder are aligned, and the LVDT displacement sensors are used for measuring the axial movement distance of the first round end socket and inversely calculating the loading force borne by the corresponding monitoring unit; the partial load units are smaller than the monitoring units in diameter, are distributed in gaps of the monitoring unit array in an array manner, are as high as the monitoring units, are used for sharing the load to make the load uniform, and comprise cylinders II and round sealing heads II; and the retainer is used for keeping the positions of the monitoring units and the partial load units. The device can be deployed in a limited space, meets the calibration range requirement, and can meet the calibration of the 50,000-ton flexible actuator.

Description

Technical Field

[0001] The present invention relates to deep geotechnical engineering tests, and in particular to a pressure measuring device and a calibration system for a large-size and large-tonnage flexible flat actuator. Background Art

[0002] When conducting deep geotechnical engineering tests, actuators are required to load large-sized specimens with large tonnage in a narrow space to fully simulate the deep geotechnical environment. In order to meet the requirements of use in a narrow space and the requirements of applying large-tonnage loading to large-sized specimens, large-sized and large-tonnage flexible flat actuators are required. The loading contact surface of this actuator can reach a range of 2m×2m, with a thickness of less than half a meter, a design limit pressure of 130Mpa, and a loading force of 52,000 tons.

[0003] In order to ensure that large-sized and large-tonnage flexible flat actuators work accurately and reliably, their loading performance needs to be calibrated. During the calibration process, the pressure distribution and changes on the calibration surface need to be monitored in real time. However, current pressure measurement generally uses strain gauge-type tension and pressure sensors. The maximum range of a single sensor is about 300t, and approximately one hundred and seventy of them are required to meet the calibration range requirements. However, there is insufficient space on the calibration bench to accommodate so many sensors. If a larger range sensor is required, due to the working characteristics of the resistance strain gauge, the volume of a single sensor will be very large, and the layout space will also be insufficient. Summary of the Invention

[0004] The purpose of the present invention is to provide a pressure measuring device for a large-size and large-tonnage flexible flat actuator, and a calibration system for a large-size and large-tonnage flexible flat actuator comprising the above-mentioned device. The device can be deployed in a limited space and meet the calibration range requirements, and can meet the calibration of 50,000-ton flexible actuators.

[0005] The technical solution adopted in the present invention is: A pressure measuring device for a large-sized, large-tonnage flexible flat actuator comprises a monitoring unit, a load-sharing unit and a retainer; the monitoring unit is distributed in an array and is used to bear and monitor pressure, and comprises a multi-cylinder assembly, a circular head and an LVDT displacement sensor. The multi-cylinder assembly is a plurality of concentrically spaced cylinders nested together with their ends aligned, each cylinder having a regularly distributed hollow structure for guiding axial elastic compression. The two ends of the multi-cylinder assembly are respectively a pressure-bearing end and a support end. The circular head covers the pressure-bearing end of the multi-cylinder assembly and radially limits each cylinder. The LVDT displacement sensor is used to measure the axial movement distance of the circular head and inversely calculate the loading force borne by the monitoring unit. The load-sharing unit has a smaller diameter than the monitoring unit, is distributed in an array between the gaps of the monitoring unit array, and is at the same height as the monitoring unit. It is used to share the load to make the load uniform. It includes a second cylinder and a second round head. The second cylinder is regularly distributed with a hollow structure for guiding axial elastic compression. The two ends of the second cylinder are respectively a pressure end and a support end. The second round head covers and is placed on the pressure end of the second cylinder and limits the second cylinder radially. The retainer is used to maintain the position of each monitoring unit and the load-sharing unit. It is flat. The retainer is distributed with through holes for accommodating each monitoring unit and each load-sharing unit and performing radial limitation. The first round head and the second round head are exposed through holes and have axial activity space when under pressure.

[0006] Preferably, in cylinder one and cylinder two, the hollow structure is a plurality of wire holes arranged along the circumferential direction, the wire holes in the same layer are evenly distributed around the axis, the wire holes in adjacent layers are staggered with each other, and both ends of the wire holes are arc-shaped expansions.

[0007] Preferably, notches are provided on the pressure-bearing ends of the cylinders of cylinder one and cylinder two. The notches are grouped in twos, and the two notches in the same group are adjacent to each other and a protrusion is formed between the two notches. The protrusion corresponds to the midpoint of the length of the adjacent wire holes in the axial direction.

[0008] Preferably, cylinder one and cylinder two are made of the same material, and both adjust the axial compression deformation capacity by adjusting the wall thickness and hollow structure and verifying it through simulation experiments, so that the monitoring unit and the load-sharing unit can deform in a coordinated manner as a whole.

[0009] Preferably, both cylinder one and cylinder two are made of high-strength elastic alloy material with an elastic modulus greater than 200 GPa and a yield strength of 800-1200 MPa.

[0010] Preferably, the pressure-bearing front surface of the circular head 1 is provided with a plurality of concentric annular grooves.

[0011] Preferably, the pressure-bearing back side of the round head one is provided with a convex disc one and several convex rings, the convex disc one is located at the center of the circle and is used to cooperate with the insertion into the innermost cylinder one to achieve radial limitation, and the convex rings are concentrically distributed about the center of the circle and are used to cooperate with the insertion into other cylinders one to achieve radial limitation; the pressure-bearing back side of the round head two is provided with a convex disc two, the convex disc two is located at the center of the circle and is used to cooperate with the insertion into the cylinder two to achieve radial limitation.

[0012] Preferably, the tail end of the LVDT displacement sensor is installed on a bracket, which has multiple connectors. The support end of the innermost cylinder is distributed with mounting grooves corresponding to each connector. When each connector is installed in each mounting groove, the LVDT displacement sensor is at the axis center and the measuring end is against the center of the circular head.

[0013] Preferably, in the retainer, the through hole corresponding to the monitoring unit is a stepped hole and one end matches the diameter of the outermost cylinder 1, and the other end matches the diameter of the round head 1; the through hole corresponding to the load sharing unit is a stepped hole and one end matches the diameter of the cylinder 2, and the other end matches the diameter of the round head 2; the pressure back sides of the round head 1 and the round head 2 are at a certain distance from the inner end faces of their respective through holes.

[0014] Preferably, a plurality of wiring grooves are provided on a side of the retainer away from the first and second circular heads, each wiring groove can extend from the edge of the retainer to all through holes, and the wiring grooves are used for wiring of LVDT displacement sensors.

[0015] Preferably, the retainer is made of die steel.

[0016] A calibration system for a large-size, large-tonnage flexible flat actuator comprises a calibration stand, a pad and the above-mentioned pressure measuring device. The calibration stand has a cylindrical cavity. The pad is located in the cavity and fits on both sides of the cavity. An installation space is formed between the pads on both sides. The large-size, large-tonnage flexible flat actuator is located in the installation space and is at the center of the cavity. The pressure measuring device is located in the installation space and is on one side or both sides of the large-size, large-tonnage flexible flat actuator. One side of the pressure measuring device is in contact with the large-size, large-tonnage flexible flat actuator directly or through a pad, and the other side is provided with a reaction force by the pad.

[0017] The beneficial effects of the present invention are: The monitoring unit uses a plurality of cylinders with hollow structures that are concentrically spaced together, which does not affect the elastic compression of each other, and can greatly increase the range of a single monitoring unit in a limited space without increasing the outer diameter and wall thickness, so that it can be deployed in a limited space and meet the calibration range requirements, which can meet the calibration of 50,000-ton flexible actuators. By combining the loading forces measured by each monitoring unit, the overall loading force and loading force distribution of large-size and large-tonnage flexible flat actuators can be obtained, and the loading performance of the actuator can be calibrated; the monitoring unit uses a plurality of cylinders that are concentrically spaced together, and the number and wall thickness of the cylinders can be determined as needed, with low processing difficulty. There is less material waste, and the round head not only ensures the relative position of each cylinder, but also can compress each cylinder synchronously, so that the multi-cylinder assembly can bear the load evenly; the load-sharing unit can share the load and can also be axially compressed under the load, so that the load can be distributed as evenly as possible to avoid the load being concentrated at the monitoring unit position and causing measurement deviation; the retainer can maintain the position of each monitoring unit and the load-sharing unit, which can not only avoid the unit shifting during the loading process, but also perform rigid limiting at the end of the loading to avoid damage to the LVDT displacement sensor; each monitoring unit and each load-sharing unit is installed in its own through hole, independent of each other, and convenient for maintenance and replacement. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 It is a top view of the pressure measuring device of the large-sized and large-tonnage flexible flat actuator in the present invention.

[0020] Figure 2 It is a three-dimensional diagram of the pressure measuring device of the large-sized and large-tonnage flexible flat actuator in the present invention.

[0021] Figure 3 It is the three-dimensional monitoring unit of the present invention. Figure 1 .

[0022] Figure 4 It is the three-dimensional monitoring unit of the present invention. Figure 2 .

[0023] Figure 5 It is a disassembly diagram of the monitoring unit in the present invention.

[0024] Figure 6 It is a three-dimensional diagram of the load-sharing unit in the present invention.

[0025] Figure 7 It is a disassembled diagram of the load-sharing unit in the present invention.

[0026] Figure 8 It is a perspective view of the retainer of the present invention.

[0027] Figure 9 It is a front view of the calibration system of the large-size and large-tonnage flexible flat actuator in the present invention.

[0028] Figure 10 It is a stereoscopic diagram of the calibration system of the large-size and large-tonnage flexible flat actuator in the present invention.

[0029] In the picture: 1-Monitoring unit; 11-Circular seal head 1; 111-Annular groove; 112-Convex disc 1; 113-Convex ring; 12-Cylinder 1; 121-Wire hole; 1211-Flaring; 122-Notch; 123-Mounting slot; 13-LVDT displacement sensor; 14-Bracket; 2- load-sharing unit; 21- round head 2; 211- convex disc 2; 22- cylinder 2; 221- line hole; 2211- flared mouth; 222- notch; 3-retainer; 31-through hole 1; 32-through hole 2; 33-wiring groove; 100-pressure measuring device; 200-calibration bench; 300-pad; 400-pad; 500-large size and large tonnage flexible flat actuator. DETAILED DESCRIPTION

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0032] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0033] In addition, the terms "round head one", "round head two", "cylinder one", "cylinder two", "convex disk one", "convex disk two", "through hole one", "through hole two", etc. are only used to distinguish descriptions and cannot be understood as indicating or implying relative importance.

[0034] The features and performance of the present application are further described in detail below with reference to the embodiments.

[0035] Example 1 This embodiment discloses a pressure measuring device for a large-sized and large-tonnage flexible flat actuator, such as Figure 1 and Figure 2 As shown, it includes a monitoring unit 1, a load-sharing unit 2 and a retainer 3; wherein: The monitoring unit 1 is distributed in an array and is used to bear and monitor pressure. It includes a multi-cylinder assembly, a circular head 11 and an LVDT displacement sensor 13. The multi-cylinder assembly is a plurality of concentrically spaced cylinders 12 that are nested together and aligned at both ends. Each cylinder 12 is regularly distributed with a hollow structure for guiding axial elastic compression. The two ends of the multi-cylinder assembly are respectively the pressure end and the support end. The circular head 11 is placed on the pressure end of the multi-cylinder assembly and radially limits each cylinder 12. The LVDT displacement sensor 13 is used to measure the axial movement distance of the circular head 11 and inversely calculate the loading force borne by the monitoring unit. Figures 1 to 5 ; The load-sharing unit 2 has a smaller diameter than the monitoring unit 1 and is distributed in an array between the gaps of the monitoring unit 1 array. It is at the same height as the monitoring unit 1 and is used to share the load to make the load uniform. It includes a cylinder 22 and a round head 21. The cylinder 22 is regularly distributed with hollow structures for guiding axial elastic compression. The two ends of the cylinder 22 are respectively a pressure end and a support end. The round head 21 covers the pressure end of the cylinder 22 and limits the radial position of the cylinder 22. Figure 1 、 Figure 2 、 Figure 6 and Figure 7 ; The retainer 3 is used to maintain the position of each monitoring unit 1 and the load-sharing unit 2. It is flat. The retainer 1 is provided with a through hole 1 31 for accommodating each monitoring unit 1 and performing radial position limiting, and a through hole 2 32 for accommodating each load-sharing unit 2 and performing radial position limiting. The circular head 11 is exposed through hole 1 31 and has axial movement space when under pressure. The circular head 21 is exposed through hole 2 32 and has axial movement space when under pressure. Figure 1 、 Figure 2 and Figure 8 .

[0036] According to the above scheme, we can know that: The monitoring unit 1 is composed of multiple hollow cylinders 12 concentrically spaced together, which does not affect the elastic compression of each unit. Without increasing the outer diameter and wall thickness, the range of a single monitoring unit 1 can be greatly increased within a limited space. As a result, it can be deployed within a limited space and meet the calibration range requirements. It can meet the calibration of 50,000-ton flexible actuators. By combining the loading forces measured by each monitoring unit 1, the overall loading force and loading force distribution of large-size and large-tonnage flexible flat actuators can be obtained, thereby realizing the calibration of the actuator's loading performance. The monitoring unit 1 uses multiple cylinders 12 that are concentrically spaced and nested together. The number and wall thickness of the cylinders 12 can be determined as needed, with low processing difficulty and minimal material waste. In addition, the round head 11 not only ensures the relative positions of the cylinders 12, but also allows the cylinders 12 to be compressed synchronously, allowing the multi-cylinder assembly to evenly bear the load. The load-sharing unit 2 can not only share the load but also be axially compressed under the load, so that the load can be distributed as evenly as possible to avoid the load being concentrated at the monitoring unit 1 and causing measurement deviation; The holder 3 can maintain the position of each monitoring unit 1 and the load-sharing unit 2, which can not only prevent the units from shifting during the loading process, but also provide rigid positioning at the end of the loading process to avoid damage to the LVDT displacement sensor 13; Each monitoring unit 1 and each load-sharing unit 3 is installed in its own through hole, independent of each other, and convenient for maintenance and replacement; The LVDT displacement sensor 13 is used to collect data, which has the characteristics of high precision, reliability, high repeatability and low temperature drift.

[0037] Regarding the specific structure of the monitoring unit 1, in this embodiment: like Figures 3 to 5 As shown, preferably, in each cylinder 12, the hollow structure is a plurality of line holes 121 arranged along the circumferential direction, the line holes 121 in the same layer are evenly distributed around the axis, the line holes 121 in adjacent layers are staggered with each other, and both ends of the line holes 121 are arc-shaped flares 1211; the multiple layers of staggered circumferential line holes 121 can guide axial compression, and the arc-shaped flares 1211 are used to avoid stress concentration, which can prevent the axial compression from developing into circumferential fission and maintain stable compression.

[0038] like Figure 3 and Figure 5 As shown, preferably, on the cylinder body of cylinder 12, a notch 122 is provided at the pressure-bearing end of the cylinder body, and the notches 122 are in a group of two. The two notches 122 in the same group are adjacent and a protrusion is formed between the two notches 122, and the protrusion corresponds to the length midpoint of the adjacent wire hole 121 in the axial direction; the setting of the notch 122 can guide the force downward to the length midpoint of the wire hole 121, promote its first compression, and facilitate subsequent compression.

[0039] like Figure 3 and Figure 5 As shown, preferably, the tail end of the LVDT displacement sensor 13 is installed on the bracket 14, and the bracket 14 has a plurality of connectors. The supporting end of the innermost cylinder 12 is distributed with mounting grooves 123 corresponding to each connector. When each connector is installed in each mounting groove 123, the LVDT displacement sensor 13 is at the axis center and the measuring end is against the center of the circular head 11; the installation of the bracket 14 and the innermost cylinder 12 is a multi-point positioning method in which multiple connectors and multiple mounting grooves 123 are matched, which can ensure that the LVDT displacement sensor 13 is at the axis center and measure the most accurate axial movement of the circular head 11.

[0040] like Figure 4 As shown, preferably, the pressure-bearing front of the circular head 11 is provided with a plurality of concentric annular grooves 111; the pressure-bearing front of the circular head 11 is relatively large, and the surface will be deformed when loaded. On the one hand, the annular grooves 111 can accommodate the material generated by the surface deformation to ensure good contact of the contact surface, and on the other hand, can avoid the phenomenon of gluing.

[0041] like Figure 5 As shown, preferably, the pressure-bearing back side of the round head 11 is provided with a convex disc 112 and several convex rings 113, the convex disc 112 is located at the center of the circle and is used to cooperate with the insertion of the innermost cylinder 12 to achieve radial limitation, and the convex rings 113 are concentrically distributed about the center of the circle and are used to cooperate with the insertion of other cylinders 12 to achieve radial limitation.

[0042] Regarding the specific structure of the load sharing unit 2, in this embodiment: like Figure 6 and Figure 7 As shown, preferably, the hollow structure in cylinder 22 comprises a plurality of circumferentially arranged linear holes 221. The linear holes 221 in the same layer are evenly distributed around the axis, while the linear holes 221 in adjacent layers are staggered. Both ends of the linear holes 221 are arc-shaped flares 2211. The multiple layers of staggered circumferential linear holes 221 guide axial compression, while the arc-shaped flares 2211 are used to avoid stress concentration, preventing the axial compression from developing into circumferential fission, and maintaining stable compression.

[0043] like Figure 6 and Figure 7 As shown, preferably, on the cylinder body of cylinder 22, a notch 222 is provided at the pressure-bearing end of the cylinder body, and the notches 222 are in a group of two. The two notches 222 in the same group are adjacent and a protrusion is formed between the two notches 222, and the protrusion corresponds to the length midpoint of the adjacent wire hole 221 in the axial direction; the setting of the notch 222 can guide the force downward to the length midpoint of the wire hole 221, promote its first compression, and facilitate subsequent compression.

[0044] like Figure 7As shown, preferably, a second convex disc 211 is provided on the pressure-bearing back side of the second circular head 21. The second convex disc 211 is located at the center of the circle and is used to cooperate with and be inserted into the second cylinder 21 to achieve radial limitation.

[0045] Regarding the collaboration between the monitoring unit 1 and the load-sharing unit 2, in this embodiment: Cylinder 1 12 and Cylinder 2 22 are made of the same material. Their axial compressive deformation capacity is adjusted by adjusting the wall thickness and hollow structure (size, number, and location of the holes). This is verified through simulation experiments to ensure coordinated deformation of the monitoring unit 1 and the load-sharing unit 2. Cylinder 1 12 and Cylinder 2 22 can be made of a high-strength elastic alloy with an elastic modulus greater than 200 GPa and a yield strength of 800-1200 MPa, such as the elastic alloy 3J33.

[0046] Regarding the arrangement of the monitoring unit 1 and the load sharing unit 2, in this embodiment: The size and distribution of the monitoring unit 1 and the load-sharing unit 2 should be designed according to the loading contact surface range of the large-size and large-tonnage flexible flat actuator. Taking the loading contact surface in the range of 2m×2m as an example, in the monitoring unit 1, the diameter of the round head 11 is 400mm, the diameter of the outermost cylinder 12 is slightly smaller than the cylinder 11, the monitoring units 1 are arranged in a 5×5 array, and the distance between adjacent monitoring units 1 is as close as possible. In the load-sharing unit 2, the load-sharing unit 2 is arranged in a 4×4 array, the diameter of the round head 21 is 200mm, the diameter of the cylinder 22 is slightly smaller than the cylinder 21, and the load-sharing unit 2 is at the center of the array gap of the monitoring unit 1.

[0047] Regarding the retainer 3, in this embodiment: like Figure 8 As shown, preferably, the through hole 1 31 is a stepped hole and one end matches the diameter of the outermost cylinder 12, and the other end matches the diameter of the round head 11. The pressure back of the round head 11 is at a certain distance from the inner end face of the through hole 1 31. The through hole 2 32 is a stepped hole and one end matches the diameter of the cylinder 2 22, and the other end matches the diameter of the round head 21. The pressure back of the round head 21 is at a certain distance from the inner end face of the through hole 2 32.

[0048] like Figure 8 As shown, preferably, a plurality of wiring grooves 33 are provided on a side of the retainer 3 away from the circular head 11 and the circular head 2 21, and each wiring groove 33 can extend from the edge of the retainer to all through holes 1 31 and all through holes 2 32, and the wiring grooves are used for wiring of the LVDT displacement sensor 13.

[0049] Preferably, the retainer 3 may be made of die steel, which has the characteristics of high toughness and low residual stress, such as DC53.

[0050] Example 2 This embodiment discloses a calibration system for a large-sized and large-tonnage flexible flat actuator, such as Figure 9 and Figure 10 As shown, the apparatus comprises a calibration stand 200, a spacer 300, and the pressure measuring device 100. The calibration stand 200 has a cylindrical cavity. The spacer 300 is located within the cavity and adheres to both sides of the cavity. An installation space is formed between the spacer 300 on both sides. A large-sized, large-tonnage, flexible, flat actuator 500 is located within the installation space and at the center of the cavity. The pressure measuring device 100 is located within the installation space and to one side of the large-sized, large-tonnage, flexible, flat actuator 500. One side of the pressure measuring device 100 contacts the large-sized, large-tonnage, flexible, flat actuator 500 via a spacer 400, and the other side receives a reaction force from the spacer 300. Of course, depending on specific needs, the pressure measuring device 100 can be installed on one or both sides of the actuator 500, with the pressure measuring device 100 contacting the actuator 500 directly or through a spacer 400. The LVDT displacement sensor 13 can also be installed on all, some, or only the center of the monitoring unit 1.

[0051] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

Claims

1. A pressure measuring device for a large-sized and large-tonnage flexible flat actuator, characterized by: It includes a monitoring unit, a load-sharing unit and a retainer; the monitoring unit is distributed in an array and is used to bear and monitor pressure, and includes a multi-cylinder assembly, a round head and an LVDT displacement sensor. The multi-cylinder assembly is a plurality of concentrically spaced cylinders that are nested together and aligned at both ends. Each cylinder is regularly distributed with a hollow structure for guiding axial elastic compression. The two ends of the multi-cylinder assembly are respectively a pressure end and a support end. The round head is placed on the pressure end of the multi-cylinder assembly and radially limits each cylinder. The LVDT displacement sensor is used to measure the axial movement distance of the round head and inversely calculate the loading force borne by the monitoring unit; the diameter of the load-sharing unit is smaller than that of the monitoring unit. The units are distributed in an array between the gaps of the monitoring unit array and are at the same height as the monitoring units. They are used to share the load to make the load uniform. They include a second cylinder and a second round head. A hollow structure for guiding axial elastic compression is regularly distributed on the second cylinder. The two ends of the second cylinder are respectively a pressure end and a support end. The second round head covers and is placed on the pressure end of the second cylinder and limits the second cylinder radially. The retainer is used to maintain the position of each monitoring unit and the load-sharing unit. It is flat-plate-shaped. Through holes are distributed on the retainer for accommodating each monitoring unit and each load-sharing unit and for radial limitation. The first round head and the second round head are exposed through holes and have axial activity space when under pressure.

2. The pressure measuring device for a large-size and large-tonnage flexible flat actuator according to claim 1, characterized in that: In cylinder 1 and cylinder 2, the hollow structure is a plurality of wire holes arranged along the circumference. The wire holes in the same layer are evenly distributed around the axis, and the wire holes in adjacent layers are staggered with each other. Both ends of the wire holes are arc-shaped expansions.

3. The pressure measuring device for a large-size, large-tonnage flexible flat actuator according to claim 2, characterized in that: On the cylinders of cylinder 1 and cylinder 2, notches are provided at the pressure ends of the cylinders. The notches are grouped in two, and the two notches in the same group are adjacent to each other and a protrusion is formed between the two notches. The protrusion corresponds to the midpoint of the length of the adjacent wire holes in the axial direction.

4. The pressure measuring device for a large-size, large-tonnage flexible flat actuator according to claim 1, characterized in that: Cylinder 1 and Cylinder 2 are made of the same material. Both adjust the axial compression deformation capacity by adjusting the wall thickness and hollow structure and verify it through simulation experiments, so that the monitoring unit and the load-sharing unit can deform in a coordinated manner as a whole.

5. The pressure measuring device for a large-size and large-tonnage flexible flat actuator according to claim 1 or 4, characterized in that: Cylinder 1 and cylinder 2 are both made of high-strength elastic alloy with an elastic modulus greater than 200 GPa and a yield strength of 800~1200 MPa.

6. The pressure measuring device for a large-size and large-tonnage flexible flat actuator according to claim 1, characterized in that: The pressure-bearing front surface of the circular head is provided with a plurality of concentric annular grooves.

7. The pressure measuring device for a large-size and large-tonnage flexible flat actuator according to claim 1, characterized in that: The pressure-bearing back side of the circular head one is provided with a convex disc one and several convex rings. The convex disc one is located at the center of the circle and is used to cooperate with the insertion of the innermost cylinder one to achieve radial limitation. The convex rings are concentrically distributed about the center of the circle and are used to cooperate with the insertion of other cylinders one to achieve radial limitation; the pressure-bearing back side of the circular head two is provided with a convex disc two. The convex disc two is located at the center of the circle and is used to cooperate with the insertion of the cylinder two to achieve radial limitation.

8. The pressure measuring device for a large-size and large-tonnage flexible flat actuator according to claim 1, characterized in that: The tail end of the LVDT displacement sensor is installed on the bracket, which has multiple connectors. The support end of the innermost cylinder is distributed with mounting grooves corresponding to each connector. When each connector is installed in each mounting groove, the LVDT displacement sensor is at the axis center and the measuring end is against the center of the circular head.

9. The pressure measuring device for a large-size and large-tonnage flexible flat actuator according to claim 1, characterized in that: In the retainer, the through hole corresponding to the monitoring unit is a stepped hole and one end matches the diameter of the outermost cylinder 1, and the other end matches the diameter of the round head 1. The through hole corresponding to the load-sharing unit is a stepped hole and one end matches the diameter of the cylinder 2, and the other end matches the diameter of the round head 2. The pressure back sides of the round head 1 and the round head 2 are at a certain distance from the inner end faces of their respective through holes.

10. The pressure measuring device for a large-size and large-tonnage flexible flat actuator according to claim 1, characterized in that: A plurality of wiring grooves are provided on a side of the retainer away from the first and second circular heads. Each wiring groove can extend from the edge of the retainer to all through holes. The wiring grooves are used for wiring of LVDT displacement sensors.

11. The pressure measuring device for a large-size and large-tonnage flexible flat actuator according to claim 1, characterized in that: The retainer is made of die steel.

12. A calibration system for a large-size, large-tonnage flexible flat actuator, characterized by: The invention comprises a calibration stand, a pad and a pressure measuring device for a large-size and large-tonnage flexible flat actuator as described in any one of claims 1 to 11, the calibration stand having a cylindrical cavity, the pad being located in the cavity and being attached to both sides of the cavity, an installation space being formed between the pads on both sides, the large-size and large-tonnage flexible flat actuator being located in the installation space and at the center of the cavity, the pressure measuring device being located in the installation space and at one side or both sides of the large-size and large-tonnage flexible flat actuator, one side of the pressure measuring device being in contact with the large-size and large-tonnage flexible flat actuator directly or through a pad, and the other side being provided with a reaction force by the pad.

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