A new material compression performance testing device

Abstract

The present invention belongs to the technical field of material detection, and discloses a new material compressive performance detection device, including a frame, a stage, a pressure mechanism and a positioning mechanism. In the present invention, the positioning mechanism is set to drive the first liquid pump to work, so that all telescopic rods are extended to the same length at the same time. As the push head at the front end of the telescopic rod approaches the detection part, the second liquid pump is started to make all the push heads and contact membranes bulge. Because the lengths of multiple telescopic rods extended at the same time are the same, the detection part is pushed toward the center of the stage, so that the center of the detection part and the center of the stage are on the same vertical line. At the same time, when it is detected that liquid cannot be continued to be input into the push head, the controller controls the first liquid pump and the second liquid pump to be closed, so that the telescopic rod is in a static state. At this time, the contact film abuts against the side of the detection part to prevent stress from being applied to the detection part from the side, thereby interfering with the actual compressive performance detection data.

Description

Technical Field

[0001] The invention belongs to the technical field of material detection, and in particular relates to a new material compression performance detection device. Background Art

[0002] New materials refer to structural materials with excellent performance and functional materials with special properties that are newly developed or being developed. Their materials include metal alloys, polymer materials, ceramics and composite materials. In the process of developing new materials, it is necessary to test and collect data on various aspects of the new materials to determine the various data of the new materials, so as to obtain new materials that meet the research and development needs.

[0003] The existing test device for testing the compressive performance of materials usually consists of a stage and a pressure head located above. After the test piece is placed on the stage, the upper extrusion head is controlled to move downward to extrude the test piece below. The extrusion head is controlled by a set control mechanism and the corresponding pressure data is recorded. In order to ensure the accuracy of the data when the test piece is extruded, the position of the test piece will be adjusted until the center of the test piece and the center of the upper extrusion head are on the same vertical line to ensure that the pressure applied by the extrusion head to the test piece is uniform. At the same time, in order to prevent the test piece from moving horizontally when being extruded, a clamping device will be added to move the test piece from the part close to the bottom surface. However, this arrangement causes additional pressure to be applied to the bottom of the test piece. When conducting destructive tests, such as testing the pressure at which the test piece will rupture or break, the data generated by the extrusion on the bottom of the test piece is inaccurate, thus affecting the test results. In addition, when conducting cyclic load tests, for example, the test piece may be deformed after multiple extrusions. When it is subsequently extruded and broken, the deformed part of the test piece will protrude above the chuck due to the deformation. With subsequent extrusion, the deformed part will be squeezed from the top to the chuck below, causing damage to the chuck, deformation, and other problems, affecting the normal use of the chuck. Summary of the invention

[0004] The purpose of the present invention is to provide a new material compression performance testing device to solve the problems raised in the above background technology.

[0005] In order to achieve the above object, the present invention provides the following technical solutions: a new material compression performance testing device, comprising a frame, a protective cabinet is fixedly connected to the inner bottom surface of the frame, a controller is fixedly connected to one side of the frame, a carrying plate is fixedly connected to the top surface of the protective cabinet, and a loading platform is fixedly connected to the top surface of the carrying plate, and further comprising:

[0006] A pressure mechanism, the pressure mechanism includes a first liquid pump, a second liquid pump and a motor fixedly connected to the inner bottom surface of the protection cabinet, the inner bottom surface of the protection cabinet is fixedly connected to a water tank, the water tank is connected to the first liquid pump and the second liquid pump, the pressure mechanism also includes two symmetrical threaded rods, the bottom ends of the threaded rods are rotatably mounted on the inner bottom surface of the protection cabinet, the top ends of the threaded rods penetrate the protection cabinet and the bearing plate and are rotatably mounted on the inner top surface of the frame, the motor is located in the middle of the two threaded rods, the output shaft of the motor is fixedly sleeved with a first gear, the threaded rod is fixedly sleeved with a second gear, the first gear is meshed with the second gear, and the two threaded rods are threadedly connected with a pressure plate;

[0007] The positioning mechanism includes four centrally symmetrical threaded columns fixedly connected to the top surface of the carrying plate, a threaded sleeve being threadedly connected to the threaded column, two threaded columns on the same side being slidably connected to a synchronization plate, a sliding sleeve being movably sleeved on the threaded column and sliding up and down, a symmetrical telescopic rod being fixedly sleeved on the side of the sliding sleeve, a reversing valve being fixedly connected to the fixed end of the telescopic rod corresponding to the same sliding sleeve, a liquid tank being fixedly connected to the top surface of the reversing valve, the telescopic end of the telescopic rod facing the center of the stage, a pusher head being fixedly connected to the telescopic end of the telescopic rod corresponding to the same sliding sleeve, and two symmetrical contact membranes being fixedly connected to the side of the pusher head facing the center of the stage.

[0008] Preferably, the contact film is made of elastic material, a liquid port is provided on the top surface of the pusher head, a pressure sealing valve is fixedly connected to the liquid port, and after liquid is injected into the pusher head, the contact film bulges.

[0009] Preferably, a first balancing valve and a second balancing valve are fixedly connected to the inner top surface of the protective cabinet, the first balancing valve is communicated with the first liquid pump through a first pipe, and the second balancing valve is communicated with the second liquid pump through a second pipe.

[0010] Preferably, a left-right symmetrical third equal-dividing valve is fixedly connected to the top surface of the carrier plate, and two output ports of the first equal-dividing valve are respectively connected to the third equal-dividing valves on the left and right sides.

[0011] Preferably, a fourth equal-dividing valve which is symmetrical front and rear is fixedly connected to the top surface of the carrier plate, and two output ports of the second equal-dividing valve are respectively communicated with the fourth equal-dividing valves on the front and rear sides.

[0012] Preferably, the two output ports of the third equal-dividing valve are connected to two adjacent reversing valves, and the two output ports of the fourth equal-dividing valve are connected to the pressure sealing valves of the adjacent pusher heads.

[0013] Preferably, a spring is elastically connected between the top surface of the sliding sleeve and the bottom surface of the synchronous plate, and a spring is also elastically connected between the bottom surface of the sliding sleeve and the top surface of the threaded column base.

[0014] Preferably, a transparent window is provided on the side of the liquid tank, and scales are equidistantly arranged on the transparent window. The inner diameter of the liquid tank is equal to the inner cavity diameter of the telescopic rod.

[0015] The beneficial effects of the present invention are as follows:

[0016] 1. In the present invention, a positioning mechanism is provided to replace the traditional clamp for clamping the detection member, and the first liquid pump is driven to work so that the liquid is pumped into the first equal-dividing valve, and then the first equal-dividing valve and the third equal-dividing valve are evenly transported so that all the telescopic rods are extended to the same length at the same time. As the push head at the front end of the telescopic rod approaches the detection member, the second liquid pump is started so that the liquid is pumped into the second equal-dividing valve, and then the second equal-dividing valve and the fourth equal-dividing valve are evenly transported so that all the push heads and the contact membranes are bulged. At this time, under the pushing action of the bulging push head and the contact membrane, the detection member located on the stage is pushed. At the same time, because the lengths of the extensions of the multiple telescopic rods at the same time are the same, the detection member is pushed toward the center of the stage, so that the center of the detection member and the center of the stage are on the same vertical line. At the same time, when it is detected that the liquid cannot be further input into the push head, the controller controls the first liquid pump and the second liquid pump to be closed, so that the telescopic rod is in a stationary state. At this time, the contact membrane abuts against the side of the detection member to prevent stress from being applied to the detection member from the side, thereby interfering with the actual compressive performance test data.

[0017] 2. In the present invention, by providing a reversing valve and a liquid tank, when the pressure plate squeezes the detection piece and causes the detection piece to deform, the detection piece pushes the push head, and the push head pushes the telescopic end of the telescopic rod, so that the liquid in the telescopic rod flows into the liquid tank. At this time, the height of the liquid in the liquid tank can be observed through the transparent window and scale on the liquid tank, and the retracted length of the telescopic rod can be understood according to calculation, and then the outward protrusion distance of the detection piece can be understood. The outward convex deformation value of the detection piece can be recorded without removing the detection piece, thereby improving the detection efficiency.

[0018] 3. In the present invention, by setting up a motor, a threaded rod and a pressure plate, when the test piece on the stage is subjected to an extrusion test, the motor is started to drive the first gear to rotate, and then the threaded rods on both sides are driven to rotate through the second gear meshing with the first gear. At this time, the threaded rod drives the pressure plate to move downward and extrude the test piece. The force output of the threaded rod for extrusion drive is more stable than that of the hydraulic system, avoiding the influence of oil pressure fluctuations in the hydraulic system on the test, and by adjusting the speed of the motor, the moving speed of the pressure plate can be quickly adjusted, which is more convenient for control for projects such as cyclic loads that require repeated pressure on the test piece. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0020] Figure 2 It is a cross-sectional view of the frame of the present invention;

[0021] Figure 3 For the present invention Figure 2 Enlarged view of point A in the middle;

[0022] Figure 4 It is a cross-sectional view of the protective cabinet of the present invention;

[0023] Figure 5 It is a partial structural schematic diagram of the positioning mechanism of the present invention.

[0024] In the figure: 1. frame; 11. protective cabinet; 12. controller; 13. load-bearing plate; 14. loading platform; 2. pressure mechanism; 21. first liquid pump; 22. second liquid pump; 23. water tank; 24. motor; 25. threaded rod; 26. first gear; 27. second gear; 28. first pipeline; 29. ​​second pipeline; 210. first equalizing valve; 211. second equalizing valve; 212. third equalizing valve; 213. fourth equalizing valve; 214. pressure plate; 3. positioning mechanism; 31. threaded column; 32. threaded sleeve; 33. synchronous plate; 34. sliding sleeve; 35. telescopic rod; 36. reversing valve; 37. liquid tank; 38. push head; 39. contact membrane; 310. spring. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0026] like Figures 1 to 5 As shown, an embodiment of the present invention provides a new material compression performance testing device, including a frame 1, a protective cabinet 11 is fixedly connected to the inner bottom surface of the frame 1, a controller 12 is fixedly connected to one side of the frame 1, a carrying plate 13 is fixedly connected to the top surface of the protective cabinet 11, and a loading platform 14 is fixedly connected to the top surface of the carrying plate 13, and further includes:

[0027] The pressure mechanism 2 includes a first liquid pump 21, a second liquid pump 22 and a motor 24 fixedly connected to the inner bottom surface of the protection cabinet 11. The inner bottom surface of the protection cabinet 11 is fixedly connected with a water tank 23, and the water tank 23 is connected to the first liquid pump 21 and the second liquid pump 22. The pressure mechanism 2 also includes two symmetrical threaded rods 25. The bottom ends of the threaded rods 25 are rotatably mounted on the inner bottom surface of the protection cabinet 11. The top ends of the threaded rods 25 penetrate the protection cabinet 11 and the bearing plate 13 and are rotatably mounted on the inner top surface of the frame 1. The motor 24 is located in the middle of the two threaded rods 25. The output shaft of the motor 24 is fixedly sleeved with a first gear 26. The threaded rod 25 is fixedly sleeved with a second gear 27. The first gear 26 is meshed with the second gear 27. The two threaded rods 25 are threadedly connected with a pressure plate 214.

[0028] The positioning mechanism 3 includes four centrally symmetrical threaded columns 31 fixedly connected to the top surface of the carrier plate 13, a threaded sleeve 32 is threadedly connected to the threaded column 31, and a synchronous plate 33 is slidably connected to the two threaded columns 31 on the same side, a sliding sleeve 34 that slides up and down is movably sleeved on the threaded column 31, and a symmetrical telescopic rod 35 is fixedly sleeved on the side of the sliding sleeve 34, and a reversing valve 36 is fixedly connected to the fixed end of the telescopic rod 35 corresponding to the same sliding sleeve 34, and a liquid tank 37 is fixedly connected to the top surface of the reversing valve 36, and the telescopic end of the telescopic rod 35 faces the center of the stage 14, and a push head 38 is fixedly connected to the telescopic end of the telescopic rod 35 corresponding to the same sliding sleeve 34, and two symmetrical contact membranes 39 are fixedly connected to the side of the push head 38 facing the center of the stage 14.

[0029] In the present invention, the positioning mechanism 3 is provided to replace the traditional clamp for clamping the detection part, and the first liquid pump 21 is driven to work so that the liquid is pumped into the first equalizing valve 210, and then the first equalizing valve 210 and the third equalizing valve 212 are evenly transported so that all the telescopic rods 35 are extended to the same length at the same time. As the push head 38 at the front end of the telescopic rod 35 approaches the detection part, the second liquid pump 22 is started so that the liquid is pumped into the second equalizing valve 211, and then the second equalizing valve 211 and the fourth equalizing valve 213 are evenly transported so that all the push heads 38 and the contact membrane 39 swell. At this time, at the push head 3 8 and the bulging of the contact membrane 39, the detection piece located on the stage 14 is pushed. At the same time, because the multiple telescopic rods 35 are extended to the same length at the same time, the detection piece is pushed toward the center of the stage 14, so that the center of the detection piece and the center of the stage 14 are on the same vertical line. At the same time, when it is detected that liquid cannot be further input into the push head 38, the controller 12 controls the first liquid pump 21 and the second liquid pump 22 to be closed, so that the telescopic rod 35 is in a stationary state. At this time, the contact membrane 39 abuts against the side of the detection piece to prevent stress from being applied to the detection piece from the side, thereby interfering with the actual compressive performance test data.

[0030] In the present invention, by providing the reversing valve 36 and the liquid tank 37, when the pressure plate 214 squeezes the detection part and causes the detection part to deform, the detection part pushes the push head 38, and the push head 38 pushes the telescopic end of the telescopic rod 35, so that the liquid in the telescopic rod 35 flows into the liquid tank 37. At this time, the liquid height in the liquid tank 37 can be observed through the transparent window and scale on the liquid tank 37, and the retracted length of the telescopic rod 35 can be understood according to calculation, and then the outward protrusion distance of the detection part can be understood. The outward convex deformation value of the detection part can be recorded without removing the detection part, thereby improving the detection efficiency.

[0031] In the present invention, by setting the motor 24, threaded rod 25 and pressure plate 214, when the test piece on the stage 14 is subjected to the extrusion test, the motor 24 is started to drive the first gear 26 to rotate, and then the second gear 27 meshing with the first gear 26 drives the threaded rod 25 on both sides to rotate. At this time, the threaded rod 25 drives the pressure plate 214 to move downward and squeeze the test piece. The force output of the threaded rod 25 for extrusion drive is more stable than that of the hydraulic system, avoiding the influence of oil pressure fluctuations in the hydraulic system on the test, and by adjusting the rotation speed of the motor 24, the moving speed of the pressure plate 214 can be quickly adjusted, which is more convenient for control for projects such as cyclic loads that require repeated pressure on the test piece.

[0032] The contact film 39 is made of elastic material. A liquid port is provided on the top surface of the push head 38. A pressure sealing valve is fixedly connected to the liquid port. When liquid is injected into the push head 38, the contact film 39 bulges. Figure 5 It can be seen that the contact membrane 39 is arc-shaped after swelling, while the push head 38 is right-angled, which enables the push head 38 to position both cubic-shaped detection parts and cylindrical detection parts, thereby improving the application range of the positioning mechanism 3. At the same time, the elastic contact membrane 39 also prevents the detection parts from being scratched by the push head 38, which would affect the detection data.

[0033] Among them, the inner top surface of the protective cabinet 11 is fixedly connected with a first equalizing valve 210 and a second equalizing valve 211, the first equalizing valve 210 and the first liquid pump 21 are communicated through a first pipe 28, the second equalizing valve 211 and the second liquid pump 22 are communicated through a second pipe 29, the top surface of the carrying plate 13 is fixedly connected with a left-right symmetrical third equalizing valve 212, the two output ports of the first equalizing valve 210 are respectively communicated with the third equalizing valve 212 on the left and right sides, the top surface of the carrying plate 13 is fixedly connected with a front-to-back symmetrical fourth equalizing valve 213, the two output ports of the second equalizing valve 211 are respectively communicated with the fourth equalizing valve 213 on the front and back sides, the two output ports of the third equalizing valve 212 are connected to two adjacent reversing valves 36, and the two output ports of the fourth equalizing valve 213 are connected to the pressure sealing valve of the adjacent push head 38.

[0034] As the first liquid pump 21 is started, the liquid in the water tank 23 is pumped into the first equalizing valve 210, and then enters the third equalizing valve 212 on both sides through the first equalizing valve 210. After the diversion of the third equalizing valve 212, the telescopic rod 35 connected thereto is extended. After the diversion of the first equalizing valve 210 and the third equalizing valve 212, the extension speed of the telescopic ends of each telescopic rod 35 is the same. After the action of the second equalizing valve 211 and the fourth equalizing valve 213, the speed at which the push head 38 is injected with liquid is the same, so that the detection part can be on the same vertical line with the center of the stage 14, thereby ensuring the accuracy of the detection data.

[0035] A spring 310 is elastically connected between the top surface of the sliding sleeve 34 and the bottom surface of the synchronous plate 33 , and a spring 310 is also elastically connected between the bottom surface of the sliding sleeve 34 and the top surface of the base of the threaded column 31 .

[0036] like Figure 5 As shown in the figure, as the pressure plate 214 contacts the synchronous plate 33, it pushes the synchronous plate 33 to move downward, and the sliding sleeve 34 is driven by the springs 310 at the upper and lower ends to be located in the middle position between the synchronous plate 33 and the base of the threaded column 31, so that the push head 38 can always face the middle position of the detection part. When the detection part is deformed by pressure, the deformation at the middle position can be effectively recorded by the liquid tank 37. At the same time, the springs 310 at the upper and lower ends can be adjusted as needed to make the push head 38 contact different heights of the detection part.

[0037] A transparent window is provided on the side of the liquid tank 37 , and scales are arranged at equal intervals on the transparent window. The inner diameter of the liquid tank 37 is equal to the inner cavity diameter of the telescopic rod 35 .

[0038] Before testing the inspection piece, the passage of the reversing valve 36 is switched to connect the liquid tank 37 with the telescopic rod 35. At this time, as the inspection piece is squeezed and deformed, it will push the telescopic end of the telescopic rod 35 to retract, thereby squeezing the liquid in the telescopic rod 35. At this time, the liquid will enter the liquid tank 37 along the passage. As the telescopic end of the telescopic rod 35 stops moving, the liquid level in the liquid tank 37 is still. At this time, the moving length of the telescopic end of the telescopic rod 35 can be converted according to the scale, and then the deformation data of the inspection piece can be obtained, so there is no need to remove the inspection piece for measurement, which improves the detection efficiency of new materials.

[0039] Working principle:

[0040] When testing the compressive performance of a new material, the test piece is first placed on the stage 14, and then the first liquid pump 21 is started through the controller 12 to extend the telescopic rod 35 toward the test piece on the stage 14. When the telescopic rod 35 begins to extend, the second liquid pump 22 is started to bulge the contact membrane 39 on the push head 38. At this time, the eccentric test piece is gradually pushed by the push head 38. Finally, under the action of multiple telescopic rods 35 and the push head 38, the center of the test piece is on the same vertical line as the center of the stage 14, so as to ensure the accuracy of the data obtained after the test piece is squeezed.

[0041] Then, the motor 24 is started to drive the threaded rods 25 on both sides to rotate, thereby moving the pressure plate 214 downward to squeeze the test piece on the stage 14. According to different experimental projects, different project data can be obtained by switching the rotation speed and rotation direction of the motor 24.

[0042] 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.

[0043] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A new material compression performance testing device, comprising a frame (1), a protective cabinet (11) is fixedly connected to the inner bottom surface of the frame (1), a controller (12) is fixedly connected to one side of the frame (1), a carrying plate (13) is fixedly connected to the top surface of the protective cabinet (11), and a loading platform (14) is fixedly connected to the top surface of the carrying plate (13), wherein: Also includes: A pressure mechanism (2), the pressure mechanism (2) comprising a first liquid pump (21), a second liquid pump (22) and a motor (24) fixedly connected to the inner bottom surface of the protection cabinet (11); a water tank (23) is fixedly connected to the inner bottom surface of the protection cabinet (11); the water tank (23) is connected to the first liquid pump (21) and the second liquid pump (22); the pressure mechanism (2) further comprises two symmetrical threaded rods (25), the bottom ends of the threaded rods (25) are rotatably mounted on the inner bottom surface of the protection cabinet (11) The top end of the threaded rod (25) passes through the protective cabinet (11) and the bearing plate (13) and is rotatably mounted on the inner top surface of the frame (1); the motor (24) is located in the middle of the two threaded rods (25); the output shaft of the motor (24) is fixedly sleeved with a first gear (26); the threaded rod (25) is fixedly sleeved with a second gear (27); the first gear (26) is meshed with the second gear (27); and the two threaded rods (25) are threadedly connected with a pressure plate (214); The positioning mechanism (3) comprises four centrally symmetrical threaded columns (31) fixedly connected to the top surface of the bearing plate (13), the threaded columns (31) being threadedly connected to threaded sleeves (32), two threaded columns (31) on the same side being slidably connected to a synchronous plate (33), the threaded columns (31) being movably sleeved with a sliding sleeve (34) that slides up and down, the side of the sliding sleeve (34) being fixedly sleeved with a symmetrical telescopic rod (35), and the same sliding sleeve The fixed end of the telescopic rod (35) corresponding to (34) is fixedly connected to a reversing valve (36), the top surface of the reversing valve (36) is fixedly connected to a liquid tank (37), the telescopic end of the telescopic rod (35) faces the center of the worktable (14), the telescopic end of the telescopic rod (35) corresponding to the same sliding sleeve (34) is fixedly connected to a push head (38), and the side of the push head (38) facing the center of the worktable (14) is fixedly connected to two symmetrical contact membranes (39).

2. A new material compressive performance testing device according to claim 1, characterized in that: The contact film (39) is made of elastic material. A liquid port is provided on the top surface of the push head (38). A pressure sealing valve is fixedly connected to the liquid port. After liquid is injected into the push head (38), the contact film (39) bulges.

3. A new material compressive performance testing device according to claim 2, characterized in that: A first equalizing valve (210) and a second equalizing valve (211) are fixedly connected to the inner top surface of the protection cabinet (11); the first equalizing valve (210) and the first liquid pump (21) are communicated through a first pipeline (28); and the second equalizing valve (211) and the second liquid pump (22) are communicated through a second pipeline (29).

4. A new material compressive performance testing device according to claim 3, characterized in that: A third equal-dividing valve (212) is fixedly connected to the top surface of the carrier plate (13) and is symmetrical on both sides. The two output ports of the first equal-dividing valve (210) are respectively connected to the third equal-dividing valves (212) on the left and right sides.

5. A new material compression performance testing device according to claim 4, characterized in that: A fourth equal-dividing valve (213) symmetrically disposed front and rear is fixedly connected to the top surface of the carrier plate (13), and two output ports of the second equal-dividing valve (211) are respectively connected to the fourth equal-dividing valves (213) on the front and rear sides.

6. A new material compressive performance testing device according to claim 5, characterized in that: The two output ports of the third equalizing valve (212) are connected to two adjacent reversing valves (36), and the two output ports of the fourth equalizing valve (213) are connected to the pressure sealing valve of the adjacent pusher head (38).

7. A new material compression performance testing device according to claim 6, characterized in that: A spring (310) is elastically connected between the top surface of the sliding sleeve (34) and the bottom surface of the synchronous plate (33), and a spring (310) is also elastically connected between the bottom surface of the sliding sleeve (34) and the top surface of the base of the threaded column (31).

8. A new material compression performance testing device according to claim 7, characterized in that: A transparent window is provided on the side of the liquid tank (37), and scales are arranged at equal intervals on the transparent window. The inner diameter of the liquid tank (37) is equal to the inner cavity diameter of the telescopic rod (35).

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