A pressure measuring device for mechanical experiments

Abstract

The application relates to a pressure measuring device for mechanical experiments, which comprises a cylinder body, a force transmission diaphragm arranged at the upper end of the cylinder body, a top pressure head fixed on the force transmission diaphragm, an annular protrusion arranged on the outer periphery of the top pressure head, an upper protrusion side taper and a lower protrusion side taper arranged in sequence on the annular protrusion, a plurality of positioning blocks arranged in sequence along the circumference of a calibration port on the upper end of the cylinder body, the positioning blocks being movably assembled on the cylinder body along the radial direction of the calibration port, one side of the positioning blocks being provided with positioning grooves matched with the annular protrusion, the positioning blocks having a limiting position during movement, in which the upper and lower groove walls of the positioning grooves are in contact with the upper protrusion side taper and the lower protrusion side taper respectively, and a avoiding position during movement, in which the upper and lower groove walls of the positioning grooves are arranged at intervals from the upper protrusion side taper and the lower protrusion side taper respectively. The application solves the technical problem that excessive liquid filling will cause plastic deformation of the force transmission diaphragm and affect the force value detection precision in the prior art.

Description

Technical Field

[0001] This invention relates to pressure measuring devices, and more particularly to a pressure measuring device for mechanical experiments. Background Technology

[0002] A pressure measuring device, also known as a pressure sensor, is a pressure measuring device used to detect the pressure of equipment.

[0003] Traditional pressure measuring devices typically include a hydraulic cylinder. The cylinder comprises a cylinder body and a piston that moves in a sealed manner with the cylinder body. A hydraulic sensor is mounted on the cylinder body to detect the pressure of the liquid within the cylinder. When calibrating the output pressure of a press, the press head applies pressure to the piston. The hydraulic sensor measures the pressure of the liquid within the cylinder, and then calculates the force on the piston—that is, the press's output pressure—based on the effective contact area between the piston and the liquid. This measurement of the press's output pressure is then used to calibrate the press.

[0004] In this traditional pressure measuring device, there is friction between the piston and the cylinder. This friction affects the accuracy of pressure detection, especially during the process of the press applying pressure to the piston. This friction is static friction, and the instability of static friction will also cause instability in the readings of the hydraulic sensor, ultimately affecting the calibration accuracy.

[0005] To address this issue, Chinese patent CN110398315A discloses "a force standard and a hydraulic bearing device", which includes a pressure bearing device. The pressure bearing device includes a cylinder with an inner cavity for filling with liquid. The force standard also includes a hydraulic sensor for detecting the liquid pressure in the cylinder. A calibration port is provided on the cylinder, and a force-transmitting diaphragm for transmitting pressure in the inward and outward directions is sealed and fixed at the calibration port and has its inner surface in contact with the liquid.

[0006] A pressure head, with its outer end protruding from the cylinder body, is fixed to the outer side of the force-transmitting diaphragm. A gap exists between the pressure head and the wall of the calibration port. The cylinder body includes a base and a pressure cap fixed to the upper end of the base. The gap is formed between the pressure head and the pressure cap. The force-transmitting diaphragm has an outer ring fixing portion fixed between the base and the pressure cap, and an inner ring fixing portion fixed to the pressure head. The outer ring fixing portion is located outside the gap, and the inner ring fixing portion is located inside the gap. An outer extension section is formed on the force-transmitting diaphragm between the outer ring fixing portion and the gap, and an inner extension section is formed on the force-transmitting diaphragm between the inner ring fixing portion and the gap.

[0007] During use, liquid is filled into the inner cavity of the cylinder through a liquid compensator. The amount of liquid filled should be sufficient to flatten the force-transmitting diaphragm. This can be controlled by adjusting the height of the pressure head, as the pressure head corresponds to a specific height when the diaphragm is flat, resulting in minimal deformation and maximizing calibration accuracy. However, existing technology has a problem: overfilling can easily occur when filling the inner cavity. When too much liquid is added, the middle of the diaphragm deforms upwards. While existing technology can prevent the diaphragm from being sheared by the extension deformation of the inner extension section, the hydraulic force causes an inelastic extension deformation—an irreversible plastic deformation—which affects the accuracy of force measurement. Similarly, when too little liquid is added, the middle of the diaphragm undergoes a downward, irreversible extension deformation. Furthermore, during storage or transportation, the weight of the pressure head acts directly on the force transmission diaphragm, which is also very prone to plastic deformation under prolonged pressure. This plastic deformation of the force transmission diaphragm will affect the force value detection. Summary of the Invention

[0008] The purpose of this invention is to provide a pressure measuring device for mechanical experiments, which solves the technical problem in the prior art that excessive liquid filling can cause plastic deformation of the force-transmitting diaphragm, thus affecting the accuracy of force measurement.

[0009] The technical solution of a pressure measuring device for mechanical experiments in this invention is as follows:

[0010] A pressure measuring device for mechanical experiments includes a cylinder with an inner cavity for filling with liquid and a hydraulic sensor for detecting the liquid pressure in the cylinder. The cylinder has a filling port and a calibration port. A force-transmitting diaphragm, which seals the calibration port and has its inner surface in contact with the liquid, is used to transmit pressure in the inward and outward directions. A pressure head is fixed on the force-transmitting diaphragm. The pressure head has an annular protrusion on its outer periphery, and the annular protrusion has an upper conical surface and a lower conical surface arranged vertically. Multiple positioning blocks are arranged sequentially along the circumference of the calibration port at the upper end of the cylinder. Each positioning block is radially guided and mounted on the cylinder. A positioning block drive mechanism is provided on the cylinder to drive the positioning blocks to move radially along the calibration port. The moving structure has a positioning groove on the side of the positioning block facing the annular protrusion that is adapted to the annular protrusion. During the movement of the positioning block, there are limiting positions where the upper and lower groove walls of the positioning groove contact the upper and lower conical surfaces of the protrusion, respectively, and clearance positions where the upper and lower groove walls of the positioning groove are spaced apart from the upper and lower conical surfaces of the protrusion, respectively, as the positioning block moves toward the top pressure head. The bottom surface of each positioning block, the bottom surface of the top pressure head, and the upper end surface of the force transmission diaphragm are coplanar. When each positioning block is in the limiting position, the bottom surface of the positioning block contacts the bottom surface of the top pressure head, and the bottom surfaces of adjacent positioning blocks contact each other. The bottom surface of the top pressure head and the bottom surfaces of each positioning block together form a limiting plane with a size larger than the calibration port size.

[0011] Furthermore, the outer peripheral surface of the annular protrusion is composed of an upper conical surface and a lower conical surface.

[0012] Furthermore, the number of positioning blocks shall not be less than six.

[0013] Furthermore, the positioning block drive structure includes a fixed sleeve fixed to the upper end of the cylinder body, each positioning block is located inside the fixed sleeve, and the fixed sleeve is threaded with an adjusting screw corresponding to the number of positioning blocks, the inner end of the adjusting screw being rotatably connected to the corresponding positioning block.

[0014] Furthermore, when each positioning block is in the avoidance position, the inner end of the positioning block protrudes beyond the edge of the calibration port.

[0015] Furthermore, an mounting ring groove is provided at the upper end of the cylinder around the calibration port, and the outer periphery of the force transmission diaphragm is welded and fixed in the mounting ring groove.

[0016] Furthermore, the thickness of the force-transmitting diaphragm is consistent with the depth of the mounting ring groove. The upper end of the cylinder is provided with a guide groove corresponding to the number of positioning blocks around the mounting ring groove. The guiding direction of the guide groove is consistent with the radial direction of the calibration port. The bottom of the positioning block is provided with a guide block that cooperates with the guide groove to guide the movement.

[0017] The beneficial effects of this invention are as follows: When using this invention, if liquid needs to be filled into the inner cavity through the filling port, the positioning block drive structure drives each positioning block to move towards the pressure head to the limiting position. At this time, the upper and lower walls of the positioning groove contact and cooperate with the upper and lower conical surfaces of the protrusion on the pressure head. The up and down movement of the pressure head is restricted by the positioning blocks, and the weight of the pressure head does not act on the force transmission diaphragm. Simultaneously, the bottom surface of the positioning block contacts the bottom surface of the pressure head, and the bottom surfaces of adjacent positioning blocks contact each other. The bottom surface of the pressure head and the bottom surfaces of each positioning block together form a limiting plane with a size larger than the calibration port size. Only the liquid needs to be filled through the filling port... The inner cavity is filled with liquid. Since the upper end face of the force-transmitting diaphragm is completely limited by the limiting plane, overfilling will not cause the force-transmitting diaphragm to deform upwards. When not in use or during storage, the weight of the top pressure head will not act on the force-transmitting diaphragm because it is limited by the positioning blocks, thus avoiding the problem of the top pressure head deforming the force-transmitting diaphragm. When normal force measurement is required, the drive structure drives each positioning block to move away from the top pressure head. The positioning blocks move to the avoidance positions set at intervals between the upper and lower walls of the positioning groove and the upper and lower conical surfaces of the protrusion, respectively. At this time, the top pressure head can be normally pressurized to achieve pressure measurement. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of one embodiment of the present invention;

[0019] Figure 2 for Figure 1 Mid-top view;

[0020] Figure 3 yes Figure 1 A schematic diagram of the structure when the central positioning block is in the limit position;

[0021] Figure 4 yes Figure 3 Top view;

[0022] In the diagram: 1. Cylinder body; 2. Filling port; 3. Guide groove; 4. Guide block; 5. Fixing sleeve; 6. Adjusting screw; 7. Annular head; 8. Limiting block; 9. Lower conical surface of the protrusion; 10. Gap; 11. Top pressure block; 12. Sealing ring; 13. Force transmission diaphragm; 14. Overflow port; 15. Upper conical surface of the protrusion; 16. Positioning groove; 17. Annular protrusion; 18. Bottom surface of the limiting block; 19. Bottom surface of the top pressure block; 20. Connecting line between the lower and upper conical surfaces of the protrusion; 21. Calibration port; 22. Detection port; 23. Mounting ring groove. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0025] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0026] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0027] An embodiment of the pressure measuring device for mechanical experiments in this invention is as follows: Figure 1-4 As shown: A cylinder 1 with an inner cavity for filling with liquid is included. The cylinder 1 has a filling port 2, a calibration port 21, a detection port 22, and an overflow port 14. A hydraulic sensor (not shown) is connected to the detection port 22. A filling valve (not shown) is installed at the filling port 2. An overflow valve (not shown) is installed at the overflow port 14. A force-transmitting diaphragm 13, which seals the calibration port 21 and whose inner surface is for contact with the liquid, is used to transmit pressure in the inward and outward directions. The calibration port 21 is circular.

[0028] A top pressure head 11 is fixed on the force transmission diaphragm 13, and the upper end of the top pressure head 11 is used to cooperate with the pressure transmission of the press.

[0029] The outer periphery of the pressure head is provided with an annular protrusion 17. In this embodiment, the outer periphery of the annular protrusion is composed of an upper conical surface 15 and a lower conical surface 9 arranged vertically. The outer diameter of the upper conical surface gradually increases from top to bottom, and the outer diameter of the lower conical surface gradually decreases from top to bottom. Therefore, the cross-sectional shape of the annular protrusion is V-shaped. Item 20 in the figure represents the connecting line between the lower conical surface and the upper conical surface.

[0030] Multiple positioning blocks 8 are arranged sequentially along the circumference of the calibration port at the upper end of the cylinder body 1. Each positioning block 8 is radially guided and mounted on the cylinder body 1. The cylinder body 1 is provided with a positioning block driving structure that drives the positioning blocks 8 to move radially along the calibration port 21. In this embodiment, there are a total of 12 positioning blocks. The side of the positioning block 8 facing the annular protrusion has a positioning groove 16 that matches the annular protrusion. Since the cross-sectional shape of the annular protrusion is V-shaped, the cross-sectional shape of the positioning groove is also V-shaped.

[0031] During the movement of the positioning block 8, there is a limiting station that moves toward the top pressure head so that the upper and lower groove walls of the positioning groove contact the upper and lower conical surfaces of the protrusion, respectively. During the movement of the positioning block, there is also a clearance station that moves away from the top pressure head so that the upper and lower groove walls of the positioning groove are spaced apart from the upper and lower conical surfaces of the protrusion, respectively. Figure 1 Item 10 indicates the gap between the positioning block and the annular protrusion when avoiding the workstation.

[0032] The bottom surface 18 of each positioning block, the bottom surface 19 of the pressing head, and the upper surface of the force-transmitting diaphragm 13 are coplanar. When each positioning block is in the limiting position, the bottom surface 18 of the positioning block contacts the bottom surface 19 of the pressing head, and the bottom surfaces 18 of adjacent positioning blocks contact each other. The bottom surface 19 of the pressing head and the bottom surfaces of each positioning block together form a limiting plane with a size larger than the calibration port size. When the positioning block is in the clearance position, the bottom surface 18 of the positioning block and the bottom surface 19 of the pressing head are spaced apart, the bottom surfaces of adjacent positioning blocks are spaced apart, and adjacent positioning blocks are spaced apart in the circumferential direction.

[0033] In this embodiment, the positioning block drive structure includes a fixed sleeve 5 fixed to the upper end of the cylinder body 1, and each positioning block 8 is located inside the fixed sleeve 5. The fixed sleeve 5 is threaded with an adjusting screw 6 corresponding to the number of positioning blocks. The inner end of the adjusting screw 6 is rotatably connected to the corresponding positioning block. Specifically, the inner end of the adjusting screw is fixed with an annular head 7, and the positioning block 8 is provided with a receiving groove that is adapted to rotate with the annular head 7.

[0034] When each positioning block is in the avoidance position, the inner end of the positioning block protrudes beyond the edge of the calibration port. At the same time, the projection of the line 20 connecting the lower and upper conical surfaces of the annular protrusion at its maximum outer diameter in the downward direction is located on the outermost bottom of the lower groove wall of the positioning groove. In other words, when the top pressure head is pressed by the pressure head of the press machine, there is a risk that the force transmission diaphragm will be crushed. However, in the solution of this invention, the lower conical surface of the annular protrusion will press against the lower groove wall of the positioning groove of the positioning block. By limiting the movement of the lower groove wall, the occurrence of safety accidents is avoided.

[0035] An installation ring groove is provided at the upper end of the cylinder body around the calibration port 21. The outer periphery of the force transmission diaphragm 13 is welded and fixed in the installation ring groove 23. A sealing ring is provided between the bottom of the installation ring groove 23 and the force transmission diaphragm.

[0036] The thickness of the force-transmitting diaphragm 13 is consistent with the depth of the mounting ring groove 23. A guide groove 3, corresponding to the number of positioning blocks, is provided at the upper end of the cylinder body 1 around the mounting ring groove. The guiding direction of the guide groove 3 is consistent with the radial direction of the calibration port. A guide block 4, cooperating with the guide groove for guided movement, is provided at the bottom of the positioning block. The guide block can be a dovetail-shaped guide block.

[0037] When it is necessary to test the output pressure of the press under normal circumstances, such as Figure 1-2As shown, the positioning block moves away from the top pressure head to a clearance position. The press head of the press presses against the upper end of the top pressure head. The top pressure head applies pressure to the liquid through a force-transmitting diaphragm. The hydraulic sensor can detect the liquid pressure. Based on the bottom surface area of ​​the top pressure head, the force acting on the top pressure head, i.e., the output force of the press head, can be calculated. When not in use or during transportation, to prevent the force-transmitting diaphragm from being deformed by the weight of the top pressure head acting on it for a long time, the positioning block can be moved towards the top pressure head to a limit position. At this time, the upper wall of the positioning groove contacts the upper conical surface of the protrusion, the lower wall of the positioning groove contacts the lower conical surface of the protrusion, and the connecting line between the lower and upper conical surfaces of the protrusion contacts the bottom of the positioning groove. Figures 3-4 As shown, at this time, the pressure head is completely limited, and its weight cannot act on the force transmission diaphragm. At the same time, the bottom surface of the positioning block is in contact with the bottom surface of the pressure head, and the bottom surfaces of adjacent positioning blocks are in contact. The bottom surface of the pressure head and the bottom surfaces of each positioning block together form a limiting plane with a size larger than the calibration port size. The weight of the pressure head cannot act on the force transmission diaphragm, which can effectively protect the force transmission diaphragm from being deformed by the pressure head, ensuring the service life and detection accuracy of the force transmission diaphragm. At the same time, the entire upper surface of the force transmission diaphragm is completely protected by the limiting plane. When it is necessary to replenish the inner cavity through the filling port, there is no need to worry about the plastic deformation of the force transmission diaphragm caused by overfilling.

[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be determined by the claims. Similarly, any equivalent structural changes made based on the description and drawings of the present invention shall also be included within the scope of protection of the present invention.

Claims

1. A pressure measuring device for mechanical experiments, comprising a cylinder with an inner cavity for filling with liquid and a hydraulic sensor for detecting the liquid pressure in the cylinder, the cylinder having a filling port and a calibration port, a force-transmitting diaphragm for transmitting pressure in the inward and outward directions being sealed and fixed at the calibration port and having its inner surface in contact with the liquid, and a pressure head being fixed on the force-transmitting diaphragm, characterized in that, The outer periphery of the pressure head is provided with an annular protrusion, which has an upper conical surface and a lower conical surface arranged vertically. Multiple positioning blocks are arranged sequentially along the circumference of the calibration port at the upper end of the cylinder body. Each positioning block is radially guided and mounted on the cylinder body. The cylinder body is provided with a positioning block drive structure that drives the positioning blocks to move radially along the calibration port. The side of the positioning block facing the annular protrusion has a positioning groove that matches the annular protrusion. During movement, the positioning block has a limiting position that moves towards the pressure head, causing the upper and lower groove walls to contact the upper and lower conical surfaces of the protrusion, respectively, and a position away from the pressure head. The upper and lower walls of the positioning groove are respectively spaced apart from the upper and lower conical surfaces of the protrusion. The bottom surfaces of each positioning block, the bottom surface of the top pressure head, and the upper surface of the force transmission diaphragm are coplanar. When each positioning block is in the limiting position, the bottom surface of the positioning block contacts the bottom surface of the top pressure head, and the bottom surfaces of adjacent positioning blocks contact each other. The bottom surface of the top pressure head and the bottom surfaces of each positioning block together form a limiting plane with a size larger than the calibration port size. An installation ring groove is provided at the upper end of the cylinder around the calibration port. The outer periphery of the force transmission diaphragm is welded and fixed in the installation ring groove. The thickness of the force transmission diaphragm is consistent with the depth of the installation ring groove.

2. The pressure measuring device for mechanical experiments according to claim 1, characterized in that: The outer circumferential surface of the annular protrusion is composed of an upper conical surface and a lower conical surface.

3. The pressure measuring device for mechanical experiments according to claim 1, characterized in that: The number of positioning blocks shall not be less than six.

4. The pressure measuring device for mechanical experiments according to claim 1, characterized in that: The positioning block drive structure includes a fixed sleeve fixed to the upper end of the cylinder body, each positioning block is located inside the fixed sleeve, and an adjusting screw corresponding to the number of positioning blocks is threaded onto the fixed sleeve. The inner end of the adjusting screw is rotatably connected to the corresponding positioning block.

5. The pressure measuring device for mechanical experiments according to claim 1, characterized in that: When each positioning block is in the avoidance position, the inner end of the positioning block protrudes beyond the edge of the calibration port.

6. The pressure measuring device for mechanical experiments according to claim 1, characterized in that: The upper end of the cylinder is provided with a guide groove corresponding to the number of positioning blocks around the mounting ring groove. The guiding direction of the guide groove is consistent with the radial direction of the calibration port. The bottom of the positioning block is provided with a guide block that cooperates with the guide groove to guide the movement.

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