A sports equipment for testing

Abstract

The present application relates to the field of sports equipment, especially to a kind of sports equipment for testing. To solve the existing sitting forward bending test device cannot be well adapted to different population, and leg binding step is too cumbersome, long time and extremely easy to produce loosening, leading to inaccurate test data, while the protection of waist is insufficient during testing, prone to tester back sprain. The technical scheme of the present application includes base and measuring scale etc.;The upper part of the front side of the base is provided with a measuring scale for measuring the distance of forward bending. The present application realizes that the circular roller is driven by the torsion spring to wind the fixing belt, so that the excess fixing belt is on the circular roller, thereby avoiding the influence on the fixing effect of the knee of the test personnel due to the excessive length of the fixing belt, the circular roller and the fixing belt are fixed by the engagement of the ratchet and the pawl, to avoid the leg arching, so that the fixing belt is elongated under tension, thereby affecting the measurement accuracy.

Description

Technical Field

[0001] This invention relates to the field of sports equipment technology, and in particular to a testing sports equipment. Background Technology

[0002] Chinese patent application number CN202222112172.0 describes a seated forward bend testing device for testing students' physical fitness. The device involves a student pushing a push plate forward; when the plate stops on a measuring plate, an infrared detector measures the distance the plate has moved, thus providing forward bend test data. The device also includes a leg brace to prevent leg bending and ensure accurate data. However, this device is limited by differences in age, height, and weight, making it unsuitable for various groups. Furthermore, the leg brace is overly cumbersome and prone to loosening over time, leading to inconsistent test results and significantly impacting testing efficiency.

[0003] In addition, during the testing process, the tester bends forward, and the muscles are in a stretched state for a long time. If the tester's back muscles are too tense or the core strength is insufficient, the tester may fall backward. Due to insufficient lumbar protection, this can easily lead to severe back sprains, affecting daily activities and athletic ability.

[0004] Therefore, we propose a testing sports equipment. Summary of the Invention

[0005] In order to overcome the shortcomings of existing sit-and-reach testing devices, such as their inability to adapt well to different groups of people, the cumbersome leg binding process, the ease with which the legs can loosen over a long period, leading to inaccurate test data, and the lack of lumbar protection during the test, which can easily cause back sprains in test subjects, this invention provides a sports equipment for testing.

[0006] The technical solution adopted in this invention is as follows:

[0007] A testing sports device includes a base and a cushion attached to the base, which is slidably locked onto the base for testers of different heights to sit on; a forward measuring unit located in front of the cushion and slidably connected to the base in a horizontal direction for detecting the displacement generated by the tester's forward arm push; and an anti-strain system located between the cushion and the forward measuring unit for covering the tester's legs and restricting leg bending.

[0008] Optionally, the cushion is slidably connected to a groove provided on the base, and a locking mechanism is provided on the cushion.

[0009] Optionally, the base includes a vertical section and a horizontal section arranged in an L-shape. Two foot-positioning limiting plates are provided on the side of the vertical section near the backrest. The limiting plates are boat-shaped. Two support blocks for supporting the ankles are also connected to the horizontal section. The upper surface of the support blocks is arc-shaped with a high center and low front and back sides. Each support block is provided with several protrusions. The limiting plates, support blocks and anti-strain system are on the same straight line.

[0010] Optionally, the front measuring unit includes: a measuring block fixed on the vertical section of the base; a measuring ruler slidably inserted into a sliding hole in the measuring block; and a touch plate detachably vertically connected to one end of the measuring ruler near the cushion, for the tester to push it out horizontally with both hands.

[0011] Optionally, the measuring block is provided with an inertial damper to limit the movement of the measuring ruler under inertial action.

[0012] Optionally, the anti-strain system includes: two flexible plates for supporting the legs; a slide rail corresponding to the lower end of the flexible plates; a slider slidably connected to the slide rail, with two symmetrical cavities inside; a fixing strap with outwardly extending fixing straps on both sides of the slider for fixing the legs of the tester, each fixing strap having a Velcro fastener; two limiting mechanisms, each located in a cavity within the slider, for limiting the stretching of the fixing straps; and two winding mechanisms, each located in a cavity within the slider, for automatically winding up the fixing straps.

[0013] Optionally, the limiting mechanism includes a rotatably connected roller, a fixed belt wound on the roller, a torsion spring sleeved on the roller, and at least one ratchet sleeved on the roller. Two ratchets are engaged with the same pawl, and the lower end of the pawl is connected to multiple pulleys that pass through the slider and roll on the slide rail. The middle inner side of the slider is fixed to the pawl by several tension springs. The slider has a certain vertical displacement on the slide rail. Under pressure, the slider can move downwards, causing the pawl to disengage from the ratchet, thus rotating the roller and subsequently stretching the fixed belt. Conversely, when the slider is not under force, under the action of the tension springs, the slider moves upwards and engages with the pawl, restricting the rotation of the roller and thus preventing the stretching of the fixed belt.

[0014] Optionally, the winding mechanism includes a return spring connected inside the cavity via a rotating shaft, and a fixing end of a fixing belt connected to the return spring; one end of the fixing end of the fixing belt is connected to the fixing belt; the fixing end of the fixing belt is T-shaped to prevent the fixing belt from detaching from the slider; an electromagnet is installed on the upper and lower sides of the fixing end of the fixing belt respectively; a fixing block is rotatably connected to the right side of each of the two electromagnets; the fixing blocks are made of metal, and the two fixing blocks are arranged facing each other to achieve the limiting and resetting effect of the fixing end of the fixing belt and the fixing blocks, avoiding manual resetting; the fixing blocks are provided with grooves.

[0015] Optionally, the cushion is filled with sponge to conform to the shape of the human back. A fixing plate is fixed to the cushion, and a groove for accommodating a measuring ruler is provided on the left side of the fixing plate. The front side of the fixing plate is arc-shaped.

[0016] Optionally, a limiting ring is fixedly connected to the front side of the base; the limiting ring is rotatably connected to a limiting pin; and the limiting pin is fixedly connected to the lower side of the measuring ruler.

[0017] The beneficial effects of this invention are as follows:

[0018] (1). The front measuring unit includes: a measuring block, which is fixed on the vertical section of the base; a measuring ruler, which is slidably inserted into a sliding hole opened on the measuring block; and a touch plate, which is detachably vertically connected to the end of the measuring ruler near the backrest, for the tester to push horizontally with both hands. By using the touch plate, the contact range is improved, and the problem of poor measurement accuracy caused by the arm not being parallel to the measuring ruler is solved. By using the touch plate, the maximum displacement of the touch plate pushed by the fingers can be regarded as the distance pushed when the arm is parallel to the measuring ruler, that is, the front distance is measured more accurately.

[0019] (2). By folding and attaching the fixing straps on the left and right sides of the slider to the tester's knees with Velcro, the tester's knees are prevented from arching, reducing the possibility of cheating. After fixing, the staff loosens the fixing straps, allowing the torsion spring to return to its initial state. The torsion spring drives the roller to rewind the fixing straps, so that the excess fixing straps are rewound onto the roller. This avoids the fixing effect on the tester's knees being affected by the fixing straps being too long, and also avoids the excess fixing straps from hindering the testing process.

[0020] (3) To prevent testers from straining their legs due to excessive force, when the fixing strap pulls the fixing end outward and the force exceeds the set value, the fixing strap pulls the fixing end outward, causing the return spring to stretch. The fixing end of the fixing strap pulls the fixing block outward from the electromagnet, preventing testers from straining their legs due to excessive force. This protects the testers and improves the safety of the testing equipment. When the test is completed, the fixing strap loosens, the return spring pulls the fixing end of the fixing strap back, and the electromagnet re-attracts the fixing block to its original position, achieving the automatic retraction effect of the fixing end of the fixing strap and the fixing block. This avoids manual reset, ensures the continuity of the testing process, and improves testing efficiency. Attached Figure Description

[0021] Figure 1 This is a three-dimensional structural diagram of the present invention.

[0022] Figure 2 for Figure 1 Schematic diagram of a partial structure.

[0023] Figure 3This is a cross-sectional structural diagram of the anti-tear system of the present invention.

[0024] Figure 4 This is a schematic diagram of the combined connection structure of ratchet, pawl and pulley in the anti-pull system of the present invention.

[0025] Figure 5 for Figure 1 Schematic diagram of a partial structure.

[0026] Figure 6 for Figure 5 A magnified schematic diagram of the central part of the structure.

[0027] Figure 7 for Figure 3 A structural diagram from another perspective.

[0028] Figure 8 for Figure 7 A magnified view of a portion of the image.

[0029] Figure 9 for Figure 1 Schematic diagram of a partial section view (section view of the measurement block).

[0030] Figure 10 for Figure 10 A magnified view of a portion of the image.

[0031] Figure 11 This is a schematic diagram of the connection structure between the limiting ring and the limiting pin of the present invention.

[0032] Figure 12 This is a schematic diagram of the three-dimensional structure of the fixing plate in this invention.

[0033] Reference numerals: 1. Base; 2. Measuring ruler; 3. Measuring block; 4. Flexible plate; 5. Circular roller; 6. Ratchet; 7. Pad; 8. Pulley; 101. Slide rail; 102. Slider; 103. Fixing strap; 201. Limiting plate; 202. Bearing block; 20201. Protrusion; 203. Cushion; 204. Return spring; 205. Fixing end of fixing strap; 206. Electromagnet; 207. Fixing block; 20701. Groove; 301. Limiting ring; 302. Limiting pin; 303. Fixing plate. Detailed Implementation

[0034] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0035] like Figures 1-12As shown, the sports equipment for testing in this embodiment includes a base 1, a cushion 203, a front measuring part, and an anti-strain system connected to the base 1. The anti-strain system is the core of this patent. It can be adjusted according to the height of the measuring person, restrict the bending of the measuring person's legs, and prevent leg, back, and foot strains, which is highly practical.

[0036] In this embodiment, as Figure 1 , Figure 2 , Figure 5 and Figure 9 As shown, the base 1 includes a vertical section and a horizontal section arranged in an L-shape. Two foot positioning plates 201 are provided on the side of the vertical section near the cushion 203. The foot positioning plates 201 are boat-shaped. The boat-shaped foot positioning plates 201 correct the placement position of the tester's feet and prevent the tester from being injured due to excessive foot tilt during the test. This effectively protects the safety of the tester and improves the accuracy of the test data.

[0037] Two support blocks 202 for supporting the ankle are also connected to the horizontal section. The upper surface of each support block 202 is arc-shaped, with a higher center and lower front and back sides. Each support block 202 has several protrusions 20201. The multiple protrusions 20201 on the surface of the support block 202 increase the friction between the support block 202 and the tester's ankle, preventing the tester from sliding backward due to muscle stretching caused by bending forward during the test, thus affecting the accuracy of the test results.

[0038] Furthermore, the limiting plate 201, the bearing block 202, and the anti-pull injury system are all on the same straight line, which makes it convenient for the tester's legs, feet, and ankles to be on the same straight line, making the measurement results more accurate and reliable.

[0039] like Figure 1 , Figure 5 and Figure 9 As shown, in this embodiment, the cushion 203 is slidably locked onto the base 1 for testers of different heights to sit on. In this embodiment, the cushion 203 is slidably connected to the slide groove provided on the base 1, and a locking mechanism is provided on the cushion 203 (not shown in the figure). By adopting this sliding structure, it is possible to adjust according to the height of the tester, thereby improving the adaptability range.

[0040] Meanwhile, in this embodiment, the backrest 203 is filled with sponge, so that the backrest 203 conforms to the shape of the human back. When the test is completed, because the human muscles are in a stretched state for a long time, during the muscle retraction process, the tester may have excessive tension in the back muscles or insufficient core strength, causing the tester to lean backward and resulting in a serious sprain of the waist. The backrest 203, which is filled with sponge, better conforms to the back of the tester and effectively reduces the impact force when the tester leans backward, thereby improving the back protection effect of the tester.

[0041] like Figures 1-2 ,as well as Figure 5 , Figures 9-11 As shown, the front measuring unit in this embodiment is located in front of the cushion 203 and can be slidably connected to the base 1 in the horizontal direction to detect the displacement generated by the front pushing of the tester's arm.

[0042] In this embodiment, the fore-drive measuring unit includes: a measuring block 3, which is fixed on the vertical section of the base 1; a measuring ruler 2, which is slidably inserted into a sliding hole opened on the measuring block 3; and a touch plate, which is detachably vertically connected to one end of the measuring ruler 2 near the cushion 203, for the tester to push out with both hands horizontally. By using the touch plate, the contact range is improved, and the problem of poor measurement accuracy caused by the arm not being parallel to the measuring ruler 2 is solved. By using the touch plate, the maximum displacement of the finger pushing the touch plate can be regarded as the distance pushed out when the arm is parallel to the measuring ruler 2, that is, the fore-drive distance is measured more accurately.

[0043] In this embodiment, the measuring block 3 is equipped with an inertial damper to limit the movement of the measuring ruler 2 under inertia. In order to prevent the tester from deliberately using explosive force to push the contact plate out, causing the contact plate to displace a large distance under inertia and affecting the data accuracy, the inertial damper is set in this embodiment to avoid inaccurate data.

[0044] In this embodiment, a limiting ring 301 is fixedly connected to the front side of the base 1; the limiting ring 301 is rotatably connected to a limiting pin 302; the limiting pin 302 is fixedly connected to the lower side of the measuring ruler 2; a fixing plate 303 is fixedly connected to the cushion 203; a groove 20701 for accommodating the measuring ruler 2 is provided on the left side of the fixing plate 303; and the front side of the fixing plate 303 is arc-shaped.

[0045] When the test is finished, the measuring ruler 2 is rotated and folded by the limiting ring 301 and the limiting pin 302. At the same time, the limiting ring 301 and the limiting pin 302 cooperate to limit the movement and prevent the measuring ruler 2 from rotating too much, thus ensuring the safe and stable operation of the device. A fixing plate 303 is fixedly attached to the cushion 203. The fixing plate 303 has a groove 20701 on the left side. When the measuring ruler 2 is folded, the end of the measuring ruler 2 can be fixed in the groove 20701 of the fixing plate 303 to prevent it from falling off during transportation, thereby improving the stability and portability during transportation.

[0046] The front side of the fixing plate 303 is arc-shaped. When the test is completed, the arc-shaped fixing plate 303 fits against the neck of the tester, effectively reducing the impact force on the neck when the tester tilts backward, thereby improving the neck protection effect of the tester.

[0047] In this embodiment, as Figures 5-8 As shown, the biggest innovation in this embodiment is the anti-strain system, which is located between the cushion 203 and the front measuring part. It is used to cover the test subject's legs and restrict leg bending.

[0048] The anti-tear system includes a flexible plate 4, a slide rail 101, a slider 102, a fixing belt 103, a limiting mechanism, and a winding mechanism.

[0049] Among them, there are two flexible plates 4 for supporting the legs; and a slide rail 101 is correspondingly set at the lower end of the flexible plate 4.

[0050] The slider 102 is slidably connected to the slide rail 101 and has two symmetrical cavities inside. In this embodiment, the slide rail 101 and slider 102 are used to adjust the distance to accommodate the differences between different testers and improve the adaptability range.

[0051] The two sides of the slider 102 are provided with outwardly extending fixing straps 103 for fixing the legs of the tester. Each fixing strap 103 is provided with a Velcro. The two fixing straps 103 are folded in opposite directions by the Velcro to fix the knees of the tester, prevent the tester's legs from bending, shorten the test distance, and thus affect the accuracy of the test results.

[0052] Two limiting mechanisms are provided, each located in a cavity within the slider 102, to limit the stretching of the fixing belt 103.

[0053] Two winding mechanisms are provided, each located in a cavity within the slider 102, for automatically winding the fixed belt 103.

[0054] In this embodiment, the limiting mechanism includes a rotatably connected roller 5, a fixing belt 103 wound around the roller 5, a torsion spring sleeved on the roller 5, and at least one ratchet 6 sleeved on the roller 5. The same pawl 7 engages between two ratchet 6, and the lower end of the pawl 7 is connected to multiple pulleys 8 that pass through the slider 102 and roll on the slide rail 101. The inner middle part of the slider 102 is fixed to the pawl 7 by several tension springs. The slider 102 has a certain vertical displacement on the slide rail 101. Under pressure, the slider 102 can move downward, causing the pawl 7 to disengage from the ratchet 6, thereby rotating the roller 5 and then stretching the fixing belt 103. Conversely, when the slider 102 is not under force, under the action of the tension spring, the slider 102 moves upward and engages with the pawl 7, restricting the rotation of the roller 5 and thus preventing the stretching of the fixing belt 103.

[0055] In this embodiment, the winding mechanism includes a return spring 204, which is connected to the cavity via a rotating shaft. A fixing end 205 of the fixing strap is connected to the return spring 204. One end of the fixing end 205 is connected to the fixing strap 103. The fixing end 205 is T-shaped to prevent the fixing strap 103 from detaching from the slider 102. An electromagnet 206 is installed on the upper and lower sides of the fixing end 205. A fixing block 207 is rotatably connected to the right side of each of the two electromagnets 206. The fixing blocks 207 are made of metal and are arranged facing each other. Before testing, the return spring 204 winds up, and the electromagnets 206 are energized, causing the fixing blocks 207 to be firmly attracted to the electromagnets 206, forming a locking structure. When the tester's legs are slightly arched, to prevent... If the tester strains their leg due to excessive force, the fixing strap 103 pulls the fixing end 205 outwards. When the force exceeds the set value, the fixing strap 103 pulls the fixing end 205 outwards, causing the return spring 204 to stretch. The fixing end 205 then pulls the fixing block 207 outwards from the electromagnet 206, preventing the tester from straining their leg due to excessive force. This protects the tester and improves the safety of the testing equipment. When the test is completed, the fixing strap 103 releases, the return spring 204 retracts the fixing end 205, and the electromagnet 206 re-attracts the fixing block 207 back into place. This achieves the automatic retraction of the fixing end 205 and the fixing block 207, avoiding manual reset, ensuring the continuity of the testing process, and improving testing efficiency.

[0056] The fixing block 207 is provided with a groove 20701; when the pulling force of the tester's leg is greater than the set value, the fixing end 205 of the fixing strap disengages from the electromagnet 206. The groove 20701 limits the movement distance of the fixing end 205 of the fixing strap, so that the fixing end 205 of the fixing strap is fixed in the groove 20701. This further prevents the fixing end 205 of the fixing strap from disengaging from the electromagnet 206 and being thrown outward due to excessive force from the leg arching, which could accidentally injure the tester. This better protects the tester and improves the safety of the testing equipment.

[0057] The entire measurement process is described in detail below: Before the test begins, the tester sits facing forward on base 1 with both legs flat on the two soft boards 4, and the soles of their feet resting on the front end of base 1. Then, the operator adjusts the sliders 102 on the two slide rails 101 to below the tester's knees. When the knees are flat, the operator presses down on the sliders 102, causing them to drop. This simultaneously pushes down the roller 5 and ratchet 6, separating the ratchet 6 from the pawl 7. The operator then pulls the fixing strap 103 outward, causing the roller 5 to rotate, extending the fixing strap 103 wrapped around the roller 5. Simultaneously, the roller 5... The fixed torsion spring undergoes torsional deformation. At the same time, the staff folds and attaches the fixing straps 103 on both sides of the slider 102 to the tester's knees using Velcro to prevent the tester's knees from arching and reduce the possibility of cheating. After fixing, the staff loosens the fixing straps 103, allowing the torsion spring to return to its initial state. The torsion spring drives the roller 5 to wind up the fixing straps 103, so that the excess fixing straps 103 are wound onto the roller 5. This avoids the fixing straps 103 being too long and affecting the fixing effect on the tester's knees, and also prevents the excess fixing straps 103 from hindering the testing process.

[0058] After the test begins, the tester puts their hands together, palms down, and bends forward. They use the tips of their middle fingers to push the measuring block 3 on the measuring ruler 2 smoothly forward until they can no longer push it. Because the body is bent forward, the muscles are stretched, causing the leg muscles to arch. At this time, the slider 102 loses the downward pressure from the legs, and the tension spring fixed to the lower side of the pawl 7 retracts, causing the slider 102 to move upward. This allows the ratchet 6 to engage with the pawl 7, thus fixing the roller 5 and the fixed belt 103. This prevents the fixed belt 103 from being stretched due to the arched legs, which would affect the accuracy of the test.

[0059] The above description is an explanation of the present invention and not a limitation thereof. The scope of the present invention is defined by the claims. Within the scope of protection of the present invention, any form of modification may be made.

Claims

1. A type of sports equipment for testing, characterized in that, Includes a base (1), and components connected to the base (1): A cushion (203) that slides and locks onto a base (1) for testers of different heights to sit on; The front measuring unit is located in front of the cushion (203) and can be slidably connected to the base (1) in the horizontal direction to detect the displacement generated by the front push of the tester's arm; An anti-strain system, located between the cushion (203) and the fore-end measuring section, is used to cover the test subject's legs and restrict leg bending; The anti-strain system includes: Two soft boards (4) are used to support the legs; The slide rail (101) is correspondingly located at the lower end of the flexible plate (4); The slider (102) is slidably connected to the slide rail (101), and has two symmetrical cavities inside; The fixing strap (103) and the slider (102) are provided with outwardly extending fixing straps (103) on both sides for fixing the legs of the test personnel. Each fixing strap (103) is provided with a Velcro. Two limiting mechanisms are provided, each located in a cavity within the slider (102), to limit the stretching of the fixing belt (103); Two winding mechanisms are provided, each located in a cavity within a slider (102), for automatically winding up a fixed belt (103). The winding mechanism includes a return spring (204), which is connected to the cavity through a rotating shaft. A fixing end (205) of the fixing belt is connected to the return spring (204). One end of the fixing end (205) is connected to the fixing belt (103). The fixing end (205) of the fixing belt is T-shaped to prevent the fixing belt (103) from separating from the slider (102). An electromagnet (206) is installed on the upper and lower sides of the fixing end (205) of the fixing belt respectively; a fixing block (207) is rotatably connected to the right side of each of the two electromagnets (206); the fixing block (207) is made of metal and the two fixing blocks (207) are arranged facing each other to achieve the limiting and resetting effect of the fixing end (205) of the fixing belt and the fixing block (207), avoiding manual resetting. The fixing block (207) is provided with a groove (20701).

2. The testing sports equipment as described in claim 1, characterized in that: The cushion (203) is slidably connected to the slide groove provided on the base (1), and a locking mechanism is provided on the cushion (203).

3. The sports equipment for testing as described in claim 1, characterized in that: The base (1) includes a vertical section and a horizontal section arranged in an L-shape. Two foot positioning plates (201) are provided on the side of the vertical section near the cushion (203). The foot positioning plates (201) are boat-shaped. Two support blocks (202) for supporting the ankles are also connected on the horizontal section. The upper surface of the support blocks (202) is arc-shaped with a high center and low front and back sides. Each support block (202) is provided with several protrusions (20201). The foot positioning plates (201), support blocks (202) and anti-strain system are on the same straight line.

4. The testing sports equipment as described in claim 1, characterized in that: The precursor measuring unit includes: Measuring block (3), which is fixed on the vertical section of base (1); The measuring ruler (2) is slidably inserted into the sliding hole on the measuring block (3); The touch plate, which is detachably vertically connected to one end of the measuring ruler (2) near the cushion (203), is used by the tester to push it out horizontally with both hands.

5. The testing sports equipment as described in claim 4, characterized in that: The measuring block (3) is equipped with an inertial damper that restricts the movement of the measuring ruler (2) under inertial action.

6. The testing sports equipment as described in claim 1, characterized in that: The limiting mechanism includes a rotatably connected roller (5), a fixing belt (103) wound around the roller (5), a torsion spring sleeved on the roller (5), and at least one ratchet (6) sleeved on the roller (5). The same pawl (7) meshes between the two ratchet wheels (6), and the lower end of the pawl (7) is connected to multiple pulleys (8) that pass through the slider (102) and roll on the slide rail (101). The inner middle part of the slider (102) is fixed to the pawl (7) by several tension springs. The slider (102) has a certain vertical displacement on the slide rail (101). Under pressure, the slider (102) can move downward, causing the pawl (7) to disengage from the ratchet (6), thereby rotating the roller (5) and then stretching the fixed belt (103). Conversely, when the slider (102) is not under force, under the action of the tension spring, the slider (102) moves upward and cooperates with the pawl (7) to restrict the rotation of the roller (5), thereby avoiding the stretching of the fixed belt (103).

7. The sports equipment for testing as described in claim 1, characterized in that: The cushion (203) is filled with sponge so that it conforms to the shape of the human back. A fixing plate (303) is fixedly attached to the cushion (203). A groove (20701) for accommodating a measuring ruler (2) is provided on the left side of the fixing plate (303). The front side of the fixing plate (303) is arc-shaped.

8. The testing sports equipment as described in claim 1, characterized in that: The base (1) is fixed to the front side with a limiting ring (301); the limiting ring (301) is rotatably connected to a limiting pin (302); the limiting pin (302) is fixed to the lower side of the measuring ruler (2).

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