Electric cylinder test bench and electric cylinder test method

Abstract

The invention relates to the technical field of electric cylinder testing equipment, provides an electric cylinder testing table and an electric cylinder testing method, and solves the technical problems that different testing tables need to be prepared for different tests of an existing electric cylinder, the occupied space is large, and meanwhile potential safety hazards exist. The electric cylinder testboard comprises a testboard, a pressure measuring assembly, a spring assembly and a displacement measuring assembly. A first mounting plate, a pressure measuring assembly and a spring assembly are mounted on the test board from top to bottom; the pressure measuring assembly comprises a pressure sensor for detection and a digital display meter for detection, the pressure sensor for detection is installed on the movable plate of the spring assembly, and the pressure sensor for detection is electrically connected with the digital display meter for detection; the spring assembly comprises a spring, a guide column, a movable plate and a base, the upper end of the guide column is mounted on the movable plate, the lower end of the guide column is in guide fit with the base, the spring sleeves the guide column, and two ends of the spring abut against the movable plate and the base respectively; the displacement measuring assembly comprises a measuring plate and a second mounting plate, the measuring plate is mounted on the movable plate, and a measuring meter is mounted on the base.

Description

Technical Field

[0001] The invention relates to the technical field of electric cylinder testing equipment, and in particular to an electric cylinder testing bench and an electric cylinder testing method. Background Art

[0002] After the production of electric cylinders, especially new electric cylinders, the life of the electric cylinders, repeated positioning accuracy, and the matching pressure sensors need to be tested. Multiple test benches are required, which is not only costly but also takes up a lot of space. In addition, during the life test of the electric cylinder, that is, the fatigue test, a test cylinder is generally used to provide the corresponding load, but the cylinder not only needs to be equipped with an oil pump, oil tank, oil circuit, etc., which further increases the occupied space, but electric cylinders of different specifications and models often need to be equipped with multiple cylinders, which further increases the occupied space. In addition, during the long-term and repeated push-pull test of the electric cylinder, the cylinder will leak oil, the pressure value will drop, affecting the reliability of the test, and even the equipment will overheat, the oil pump will explode or burst, and there will be safety hazards.

[0003] For this purpose, we propose an electric cylinder test bench. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the shortcomings of the prior art, the present invention provides an electric cylinder test bench and an electric cylinder test method, which overcome the shortcomings of the prior art, have a reasonable design and a compact structure, and solve the technical problems that different tests of the prior electric cylinder require different test benches, occupy a large space, and have safety hazards.

[0006] (II) Technical solution

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] An electric cylinder test bench, characterized in that it comprises a test bench, a pressure measuring component, a spring component and a displacement measuring component;

[0009] The test bench is installed with a first mounting plate, a pressure measuring assembly and a spring assembly from top to bottom;

[0010] The pressure measurement assembly includes a detection pressure sensor and a detection digital display meter, the detection pressure sensor is installed on the movable plate of the spring assembly and a pressure head is installed at its sensing end, and the detection pressure sensor and the detection digital display meter are electrically connected;

[0011] The spring assembly includes a spring, a guide post, a movable plate and a base, wherein the guide post is arranged vertically, the upper end of the guide post is mounted on the movable plate, and the lower end thereof is matched with the base guide, the spring corresponds to the guide post one by one, the spring is sleeved on the guide post, and the two ends thereof are respectively against the movable plate and the base;

[0012] The displacement measurement assembly includes a measuring plate, a measuring table and a second mounting plate. The measuring plate is mounted on a movable plate. The second mounting plate is mounted on a base. The measuring table is mounted on the second mounting plate. When the measuring plate moves vertically downward with the movable plate, it can press down the measuring rod of the measuring table.

[0013] Furthermore, the test bench includes a bottom plate, a top plate spaced above the bottom plate by a support member, and a first mounting plate is mounted on the upper surface of the top plate;

[0014] The electric cylinder to be tested is vertically installed on the first installation plate, and the push rod of the electric cylinder to be tested passes through the first installation plate and the top plate downward.

[0015] Furthermore, the electric cylinder test bench also includes a connecting rod that can be coaxially installed on the lower end of the push rod of the electric cylinder to be tested, and a pressure head is installed at the lower end of the connecting rod.

[0016] Furthermore, the base is integrally formed on the bottom plate or is detachably connected to the bottom plate.

[0017] Furthermore, a plurality of guide pillars are arranged around the outer periphery of the detection pressure sensor.

[0018] Furthermore, the first mounting plate is in a circular ring shape, the second mounting plate is in an inverted L shape, and the measuring meter is installed on a lateral portion of the second mounting plate.

[0019] Furthermore, the transverse part of the second mounting plate is provided with an assembly hole and a slit, the slit extends from the outside to the inside and is connected with the assembly hole to form a pair of clamping arms, the measuring rod of the measuring meter is arranged upward and the outer peripheral sleeve of the measuring rod is inserted into the assembly hole, and the locking bolt passes through one clamping arm and is threadedly connected with the other clamping arm to tighten the assembly hole and clamp the fixed sleeve.

[0020] Furthermore, the measuring plate is L-shaped, the longitudinal portion of the measuring plate is mounted on the pressure head at the upper end of the sensor, and the transverse portion of the measuring plate is provided with reinforcing ribs, which are located in the center of the transverse portion and extend along the length direction of the transverse portion.

[0021] Furthermore, no reinforcing ribs are provided at the front end of the transverse portion of the measuring plate.

[0022] A method for testing an electric cylinder, which adopts the above-mentioned electric cylinder test bench for testing, is characterized in that the method comprises the following steps:

[0023] S1. Installation of the electric cylinder to be tested: select a first mounting plate and a connecting rod that are compatible with the electric cylinder to be tested, install the first mounting plate on the top plate of the test bench, install the electric cylinder to be tested on the first mounting plate, and coaxially install the connecting rod with the pressure head on the lower end of the push rod of the electric cylinder to be tested;

[0024] S2. Test the pressure sensor for the electric cylinder to be tested. The electric cylinder to be tested drives the connecting rod to move downward. The pressure head at the lower end of the connecting rod contacts the pressure head at the upper end of the detection pressure sensor. Observe whether the error between the reading of the detection digital display connected to the detection pressure sensor and the reading of the digital display of the pressure sensor to be tested is within the preset range, and repeat this step.

[0025] S3, fatigue test of the electric cylinder to be tested. The electric cylinder to be tested drives the connecting rod to move downward. The distance the electric cylinder pushes down when the reading of the digital display reaches the rated load of the electric cylinder to be tested is the loading distance of the electric cylinder fatigue test. The electric cylinder is repeatedly loaded according to the loading distance of the electric cylinder fatigue test until functional failure or obvious damage occurs.

[0026] S4. Repeat the positioning test of the electric cylinder to be tested. The electric cylinder to be tested drives the connecting rod to repeatedly move down the rated distance. At this distance, the measuring plate can press down the measuring rod of the measuring meter to observe whether the fluctuation of the measuring meter reading is within the preset range.

[0027] (III) Beneficial effects

[0028] The present invention provides an electric cylinder test bench, which has the following beneficial effects:

[0029] 1. Integrating the tests of electric cylinder life, repeated positioning accuracy and pressure sensor adaptation on the same test bench can not only effectively reduce the number of test bench configurations and the occupied space, but also make switching between tests faster without the need for disassembly, reassembly and calibration, thus improving the overall test efficiency, continuity and consistency;

[0030] 2. The pressure sensor is fixed on the movable plate connected to the spring assembly below, so as to achieve soft contact between the connecting rod and the pressure sensor (more precisely, in the embodiment of the present invention, the pressure head at the lower end of the connecting rod and the pressure head at the upper end of the pressure sensor are in soft contact), so as to avoid the inability to accurately control the subsequent stroke of the electric cylinder after the two are in hard contact. Any slight stroke may cause the detection value to increase sharply, or even greatly exceed the rated load, causing damage to the electric cylinder to be tested. In addition, in order to avoid the accidental nature of the test, it is generally necessary to test multiple groups, each group corresponding to a load / pressure test multiple times. After the connecting rod and the pressure sensor are in hard contact, the subsequent stroke of the electric cylinder cannot be accurately controlled, and the test data fluctuates greatly and has poor repeatability.

[0031] 3. Use spring components to replace electric cylinders. On the one hand, by replacing the springs, it can adapt to the needs of electric cylinder tests with different loads, with low initial production costs, low later maintenance costs, and small space occupation; on the other hand, there is no risk of oil leakage that may exist when the oil cylinder is repeatedly tested for a long time, which improves the reliability of the test and eliminates the safety hazards of oil pump explosion or bursting;

[0032] 4. Fix the measuring table to the side of the base. When the electric cylinder push rod is pressed down, the measuring rod of the measuring table is pressed down through the measuring plate connected to the movable plate. Since the movable plate is connected to the top of the spring assembly, after the push rod contacts the movable plate, or indirectly contacts, the movable table and the push rod move synchronously, ensuring that the measuring plate can stably and gently transmit the push rod displacement without causing vibration or unnecessary displacement jump, thereby improving the measurement accuracy and consistency. At the same time, in this process, the spring assembly absorbs the impact force to reduce the direct impact and wear on the measuring rod. In addition, the spring assembly can compensate for slight deviations caused by load changes or installation errors, ensuring that the measuring rod is always subjected to a stable and uniform force, thereby providing more accurate measurement data. In addition, the reinforcing ribs of the measuring plate do not extend to the ends of its lateral part, which can ensure the structural strength of the measuring plate while retaining its end elasticity, which not only ensures that the contact point of the measuring rod is protected, but also reduces the risk of deformation and wear caused by repeated contact during long-term use. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the structure of the present invention;

[0034] Figure 2 It is a schematic diagram of the explosion structure of the present invention;

[0035] Figure 3 It is a schematic diagram of the structure of the pressure measurement component, the spring component and the displacement measurement component in the present invention.

[0036] In the figure:

[0037] 1. Top plate;

[0038] 2. Bottom plate;

[0039] 21. Positioning hole;

[0040] 3. Column;

[0041] 4. The first mounting plate;

[0042] 5. Connecting rod;

[0043] 6. Press head;

[0044] 7. Pressure sensor for detection;

[0045] 8. Digital display for testing;

[0046] 9. Movable board;

[0047] 10. Spring;

[0048] 11. Guide pillar;

[0049] 12. Base;

[0050] 13. Measuring board;

[0051] 131, horizontal part;

[0052] 132. Strengthening ribs;

[0053] A. Front end area;

[0054] 14. Measuring table;

[0055] 141. Surveying rod;

[0056] 142, bushing;

[0057] 15. Second mounting plate;

[0058] 151, assembly hole;

[0059] 152, slit;

[0060] 153, clamp arm;

[0061] 154. Perforation;

[0062] 16. Linear bearings;

[0063] P, electric cylinder to be tested. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] See attached Figure 1-3 , an electric cylinder test bench, comprising a test bench, a connecting rod 5, a pressure measuring assembly, a spring assembly and a displacement measuring assembly;

[0066] The test bench comprises a bottom plate 2, a top plate 1 arranged above the bottom plate 2 by support members, the support members are four upright posts 3 (side plates may also be used) arranged circumferentially on the top plate 1, that is, the top plate 1 is supported circumferentially above the bottom plate 2 by four upright posts 3, an annular first mounting plate 4 is installed on the upper end surface of the top plate 1, the electric cylinder P to be tested is uprightly installed on the first mounting plate 4, the push rod of the electric cylinder P to be tested passes through the first mounting plate 4 and the top plate 1 downward, and an installation space for a pressure measuring component, a spring component and a displacement measuring component is formed between the top plate 1 and the bottom plate 2, wherein the pressure measuring component and the spring component are arranged from top to bottom;

[0067] The connecting rod 5 can be coaxially mounted on the lower end of the push rod of the electric cylinder P to be tested, and the pressure head 6 is installed at the lower end of the connecting rod 5, so that the electric cylinders P to be tested with fixed installation heights but different strokes can all be tested using the test bench, thereby improving the versatility of the test bench;

[0068] The pressure measurement assembly includes a detection pressure sensor 7 and a detection digital display 8, wherein the detection pressure sensor 7 is installed on a movable plate 9 of the spring assembly and a pressure head 6 is installed at the sensing end on the upper side thereof, and the detection digital display 8 and the detection pressure sensor 7 are electrically connected and used to feedback and display the pressure applied to the pressure sensor by the electric cylinder P to be tested through the connecting rod 5; wherein, if it is necessary to detect the tension of the electric cylinder P to be tested, the pressure head 6 at the upper end of the detection pressure sensor 7 and the pressure head 6 at the lower end of the connecting rod 5 should be connected and fixed, and at this time, the detection pressure sensor 7 is preferably a spoke-type pressure sensor with a perforation in the center, and the bolts pass through the movable plate 9, the detection pressure sensor 7, and the two pressure heads 6 from top to bottom, and then the connecting rod 5 is threaded and locked;

[0069] The spring assembly includes a spring 10, a guide column 11, a movable plate 9 and a base 12. Four guide columns 11 are arranged around the outer periphery of the detection pressure sensor 7. The guide columns 11 are arranged vertically. The upper ends of the guide columns 11 are installed on the movable plate 9, and the lower ends thereof are guided and matched with the base 12 (a retaining ring or a limit nut may also be installed at the lower ends of the guide columns 11 to prevent them from coming out). The base 12 is provided with a linear bearing 16 matched with the guide columns 11 to reduce the wear of the guide columns 11 and improve the positioning accuracy of the guide columns 11. The springs 10 correspond to the guide columns 11 one by one. The springs 10 are sleeved on the guide columns 11, and the two ends thereof are respectively against the movable plate 9 and the base 12. The base 12 is detachably mounted on the bottom plate 2.

[0070] The displacement measurement assembly includes a measuring plate 13, a measuring gauge 14 and a second mounting plate 15. The measuring plate 13 is mounted on the movable plate 9. The second mounting plate 15 is mounted on the base 12 and its bottom is positioned and inserted into the positioning hole 21 of the base plate 2 to achieve rapid positioning and assembly. The measuring gauge 14 is mounted on the second mounting plate 15. The measuring plate 13 can press down the measuring rod of the measuring gauge 14 when it moves vertically downward with the movable plate 9.

[0071] In this embodiment, the first mounting plate 4 is in a circular shape, and is formed with a circle of flange holes that cooperate with the top plate 1, and mounting holes that are compatible with different types of electric cylinders P to be tested, that is, one first mounting plate 4 can be compatible with more than two types of electric cylinders P to be tested. When there are many types of electric cylinders P to be tested, and the number and distribution of mounting holes required for the processing stroke cannot be obtained on one first mounting plate 4, multiple first mounting plates 4 can also be additionally reserved.

[0072] In this embodiment, the second mounting plate 15 is in an inverted L-shape, and the measuring meter 14 is mounted on the transverse part of the second mounting plate 15. The transverse part of the second mounting plate 15 is provided with an assembly hole 151 and a slit 152, and the slit 152 extends from the outside to the inside and is connected with the assembly hole 151 to form a pair of clamping arms 153. The measuring rod 141 of the measuring meter 14 is arranged upward and its outer peripheral shaft sleeve 142 is inserted into the assembly hole. The locking bolt (not shown in the figure) passes through the through hole 154 of one clamping arm 153 and is threadedly connected with the other clamping arm 153 to tighten the assembly hole 151 and clamp the fixed shaft sleeve 142, so as to facilitate the rapid assembly of the measuring meter 14. In addition, a strip hole is formed in the longitudinal part of the second mounting plate 15, and the locking bolt passes through the strip hole and is fixedly connected with the base 12, so as to facilitate the height adjustment of the measuring meter 14 by vertical translation of the second mounting plate 15.

[0073] In this embodiment, the measuring plate 13 is L-shaped, and the longitudinal part of the measuring plate 13 is installed on the cutting plane of the side of the pressure head 6 at the upper end of the sensor to improve the stability of the installation. The transverse part of the measuring plate 13 is provided with a reinforcing rib 132, and the reinforcing rib 132 is located in the center of the transverse part 131 and extends along the length direction of the transverse part 131. The provision of the reinforcing rib 132 can effectively improve the rigidity of the measuring plate 13, and can adapt to the long-term repeated measurement of the electric cylinder P to be measured. In addition, the front end area A of the transverse part of the measuring plate 13 is not provided with the reinforcing rib 132, which can ensure the structural strength of the measuring plate 13 while retaining its end elasticity, which not only ensures that the contact point of the measuring rod is protected, but also reduces the risk of deformation and wear caused by repeated contact during long-term use, and ensures the reliability of measurement.

[0074] A method for testing an electric cylinder, the method using the above-mentioned electric cylinder test bench for testing, the method comprising the following steps:

[0075] S1. Installation of the electric cylinder P to be tested: select the first mounting plate 4 and the connecting rod 5 that are compatible with the electric cylinder P to be tested, install the first mounting plate 4 on the top plate 1 of the test bench, install the electric cylinder P to be tested on the first mounting plate 4, and install the connecting rod 5 with the pressure head 6 upright and coaxially on the lower end of the push rod of the electric cylinder P to be tested;

[0076] S2. Test the pressure sensor of the electric cylinder P to be tested. The electric cylinder P to be tested drives the connecting rod 5 to move downward. The pressure head 6 at the lower end of the connecting rod 5 conflicts with the pressure head 6 at the upper end of the detection pressure sensor 7. Observe whether the error between the reading of the detection digital display 8 connected to the detection pressure sensor 7 and the reading of the digital display of the pressure sensor to be tested is within the preset range, and repeat this step. If the reading error exceeds the preset range, the pressure sensor to be tested is damaged, otherwise, it is normal.

[0077] S3, fatigue test of the electric cylinder P to be tested, the electric cylinder P to be tested drives the connecting rod 5 to move downward, and the reading of the detection digital display meter 8 reflects the electric cylinder push-down distance when the rated load of the electric cylinder P to be tested is reached, which is the electric cylinder fatigue test loading distance. The electric cylinder is repeatedly loaded according to the electric cylinder fatigue test loading distance until the electric cylinder P to be tested fails in function or is obviously damaged, and its service life is measured. The loading in this embodiment is specifically a "pressing down" operation. In some embodiments, it can also be loaded separately or in combination with "pulling up", and the operating principles of the two are the same;

[0078] S4, the electric cylinder P to be tested is subjected to repeated positioning test. The electric cylinder P to be tested drives the connecting rod 5 to repeatedly move downward by a rated distance. At this distance, the measuring plate 13 can press down the measuring rod of the measuring meter 14 to observe whether the fluctuation of the reading of the measuring meter 14 is within the preset range. If the fluctuation of the reading of the measuring meter 14 is small and close to the same during repeated tests, the repeated positioning accuracy of the electric cylinder meets the requirements. Otherwise, it does not meet the requirements.

[0079] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0080] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electric cylinder test bench, characterized in that: It includes a test bench, a pressure measuring assembly, a spring assembly and a displacement measuring assembly; The test bench is installed with a first mounting plate, a pressure measuring assembly and a spring assembly from top to bottom; The pressure measurement assembly includes a detection pressure sensor and a detection digital display meter, the detection pressure sensor is installed on the movable plate of the spring assembly and a pressure head is installed at its sensing end, and the detection pressure sensor and the detection digital display meter are electrically connected; The spring assembly includes a spring, a guide post, a movable plate and a base, wherein the guide post is arranged vertically, the upper end of the guide post is mounted on the movable plate, and the lower end thereof is matched with the base guide, the spring corresponds to the guide post one by one, the spring is sleeved on the guide post, and the two ends thereof are respectively against the movable plate and the base; The displacement measurement assembly includes a measuring plate, a measuring table and a second mounting plate. The measuring plate is mounted on a movable plate. The second mounting plate is mounted on a base. The measuring table is mounted on the second mounting plate. When the measuring plate moves vertically downward with the movable plate, it can press down the measuring rod of the measuring table.

2. The electric cylinder test bench according to claim 1, characterized in that: The test bench comprises a bottom plate, a top plate spaced above the bottom plate by a support member, and a first mounting plate is mounted on the upper surface of the top plate; The electric cylinder to be tested is vertically installed on the first installation plate, and the push rod of the electric cylinder to be tested passes through the first installation plate and the top plate downward.

3. The electric cylinder test bench according to claim 2, characterized in that: The electric cylinder test bench also includes a connecting rod which can be coaxially mounted on the lower end of the push rod of the electric cylinder to be tested, and a pressure head is mounted on the lower end of the connecting rod.

4. The electric cylinder test bench according to claim 2, characterized in that: The base is integrally formed on the bottom plate or is detachably connected to the bottom plate.

5. The electric cylinder test bench according to claim 2, characterized in that: A plurality of guide pillars are arranged around the outer periphery of the detection pressure sensor.

6. The electric cylinder test bench according to claim 2, characterized in that: The first mounting plate is in the shape of a circular ring, the second mounting plate is in the shape of an inverted L, and the measuring meter is mounted on a lateral portion of the second mounting plate.

7. The electric cylinder test bench according to claim 6, characterized in that: The transverse part of the second mounting plate is provided with an assembly hole and a slit, the slit extends from the outside to the inside and is connected with the assembly hole to form a pair of clamping arms, the measuring rod of the measuring meter is arranged upward and the outer peripheral sleeve of the measuring rod is inserted into the assembly hole, and the locking bolt passes through one clamping arm and is threadedly connected with the other clamping arm to tighten the assembly hole and clamp the fixed sleeve.

8. The electric cylinder test bench according to claim 2, characterized in that: The measuring plate is L-shaped, the longitudinal part of the measuring plate is installed on the pressure head at the upper end of the sensor, and the transverse part of the measuring plate is provided with reinforcing ribs, which are located in the center of the transverse part and extend along the length direction of the transverse part.

9. The electric cylinder test bench according to claim 2, characterized in that: The front end of the transverse portion of the measuring plate is not provided with reinforcing ribs.

10. A method for testing an electric cylinder, the method using any of the electric cylinder test benches described in 2-9 for testing, characterized in that: The method comprises the following steps: S1. Installation of the electric cylinder to be tested: select a first mounting plate and a connecting rod that are compatible with the electric cylinder to be tested, install the first mounting plate on the top plate of the test bench, install the electric cylinder to be tested on the first mounting plate, and coaxially install the connecting rod with the pressure head on the lower end of the push rod of the electric cylinder to be tested; S2. Test the pressure sensor for the electric cylinder to be tested. The electric cylinder to be tested drives the connecting rod to move downward. The pressure head at the lower end of the connecting rod contacts the pressure head at the upper end of the detection pressure sensor. Observe whether the error between the reading of the detection digital display connected to the detection pressure sensor and the reading of the digital display of the pressure sensor to be tested is within the preset range, and repeat this step. S3, fatigue test of the electric cylinder to be tested. The electric cylinder to be tested drives the connecting rod to move downward. The distance the electric cylinder pushes down when the reading of the digital display reaches the rated load of the electric cylinder to be tested is the loading distance of the electric cylinder fatigue test. The electric cylinder is repeatedly loaded according to the loading distance of the electric cylinder fatigue test until functional failure or obvious damage occurs. S4. Repeat the positioning test of the electric cylinder to be tested. The electric cylinder to be tested drives the connecting rod to repeatedly move down the rated distance. At this distance, the measuring plate can press down the measuring rod of the measuring meter to observe whether the fluctuation of the measuring meter reading is within the preset range.

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