Breathability detection equipment for air fiber mattress
By designing air fiber mattress breathability detection equipment with air supply mechanism and height adjustment mechanism, a servo motor drives stainless steel orifice plate to simulate human body pressure, and combined with a pressure differential flowmeter to measure breathability performance, the problem of static detection deviation is solved and the accuracy of dynamic breathability detection is achieved.
Patent Information
- Application Number
- CN202510731290.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-03
- Publication Date
- 2025-08-15
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
The existing air fiber mattress breathability detection equipment can only perform static detection, and lacks the dynamic detection ability to simulate real use conditions, resulting in deviations from the actual use scenario.
A breathability detection device including an air supply mechanism, a height adjustment mechanism and a flow measurement mechanism is designed. The stainless steel orifice plate driven by a servo motor simulates the human body pressure, and combines a pressure differential flowmeter to measure the breathable performance of the mattress cutting material to achieve dynamic detection.
It can simulate the breathability of the mattress under real usage conditions, provide dynamic detection data, and improve the accuracy of the detection results.
Smart Images
Figure CN120489895A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of mattress testing equipment, in particular to an air permeability testing equipment for air fiber mattresses. Background Art
[0002] An air fiber mattress is a new type of mattress based on polymer materials. Its main structure is composed of breathable fibers in a three-dimensional mesh structure. This strategically arranged structure creates dense support points, providing both flexibility and resilience. The through-hole design within the air fiber mattress significantly enhances air circulation, effectively dissipating moisture and inhibiting bacterial growth. Air fiber mattress air permeability testing equipment is used to measure the air flow properties of the mattress material, and the test data can be used to evaluate the mattress's performance.
[0003] However, most of the existing air fiber mattress air permeability testing equipment on the market can only perform static testing on the mattress cutting materials, but ignores the dynamic air permeability performance of the mattress under the pressure of the human body. It lacks the ability to simulate dynamic testing under real usage conditions, resulting in deviations between the test results and actual usage scenarios. Summary of the Invention
[0004] In response to the shortcomings of the existing technology, the present invention provides an air permeability testing device for air fiber mattresses, which solves the problem that the existing air permeability testing equipment for air fiber mattresses on the market can only perform static testing on the cut materials of the mattress, but lacks the ability to simulate dynamic testing under real usage conditions, thereby resulting in deviations between the test results and the actual usage scenarios. Technical Solution
[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: an air permeability testing device for an air fiber mattress, comprising a testing box, a ventilation mechanism provided at the lower portion of the testing box, and a height adjustment mechanism and a flow measurement mechanism provided at the upper portion of the testing box; The air supply mechanism includes a mounting frame, an inner wall of the mounting frame is provided with a No. 1 servo motor, an output shaft of the No. 1 servo motor is fixedly connected to a rotating rod, an upper end of the rotating rod is fixedly connected to a fan blade, a placement frame is fixedly connected to the middle of the inner wall around the detection box, and a ventilation hole is opened in the middle of the upper surface of the placement frame; The height adjustment mechanism includes a U-shaped plate and a mounting bracket, the lower end of the mounting bracket is fixedly connected to the upper surface of the detection box, the middle of the front and rear inner walls of the detection box are respectively provided with limit grooves, the U-shaped plate slides inside the limit grooves, and the lower end of the inner wall of the U-shaped plate near the center of the detection box is fixedly connected to a stainless steel orifice plate, and the stainless steel orifice plate is snap-connected to the inner wall of the placement frame; The flow measurement mechanism includes a No. 1 air outlet pipe, a differential pressure flowmeter, and a No. 2 air outlet pipe, and the middle portion of one side of the upper surface of the detection box is connected to the No. 1 air outlet pipe; Through the above technical solution, by using the triangular indicator block in conjunction with the scale, it is convenient for staff to visually adjust the height of the U-shaped plate provided with a stainless steel orifice plate, thereby facilitating the measurement of the air permeability of the cut material of the mattress corresponding to different downward pressure distances through the differential pressure flow meter.
[0006] Preferably, the four corners of the lower surface of the detection box are respectively fixedly connected with support legs, and the middle part of the lower surface of the detection box is fixedly connected with a porous ventilation plate by multiple bolts; Through the above technical solution, the stability of the detection box is improved by the support legs, and a good air circulation environment is provided for the No. 1 servo motor equipped with fan blades through the porous ventilation plate, thereby ensuring the gas circulation inside the detection box.
[0007] Preferably, a sealing door is hingedly connected to the front end of the outer wall of one side of the detection box, an observation window is provided in the middle of the outer wall of the front end of the sealing door, and a handle is fixedly connected to the rear end of the outer wall of one side of the sealing door; Through the above technical solution, the staff can conveniently observe the contact between the stainless steel perforated plate and the cut material of the mattress through the observation window, and open the sealed door by the handle, so that the staff can conveniently place the cut material of the mattress inside the placement frame so that the cut material of the mattress covers the ventilation holes.
[0008] Preferably, a rubber sealing ring is provided on the inner wall of the upper end of the limiting groove, and the U-shaped plate fits tightly with the rubber sealing ring; With the above technical solution, the rubber sealing ring can effectively prevent the air at the upper end of the placement frame in the detection box from leaking from between the U-shaped plate and the limiting groove.
[0009] Preferably, a mounting groove is provided at the center of the upper surface of the detection box, an auxiliary bearing is fixedly connected to the inner wall of the mounting groove, a cavity is provided in the middle of the upper surface of the mounting frame, a No. 2 servo motor is provided in the middle of the upper surface of the mounting frame, a driving threaded rod is fixedly connected to the output shaft of the No. 2 servo motor, the lower end of the driving threaded rod passes through the cavity and is fixedly connected to the inner wall of the auxiliary bearing, and the middle part of the outer wall of the driving threaded rod is threadedly connected to the U-shaped plate; Through the above technical solution, the driving threaded rod is rotated by the No. 2 servo motor, thereby adjusting the height of the U-shaped plate, so that the stainless steel perforated plate applies a load to the cut material of the mattress, thereby simulating real usage conditions.
[0010] Preferably, the rear end of the differential pressure flowmeter is fixedly connected to a No. 2 flange ring, the front end of the No. 1 air outlet pipe is fixedly connected to a No. 1 flange ring, the No. 1 flange ring and the No. 2 flange ring are fixedly connected by multiple sets of bolts and nuts, the front end of the differential pressure flowmeter is fixedly connected to a No. 3 flange ring, the rear end of the No. 2 air outlet pipe is fixedly connected to a No. 4 flange ring, the No. 4 flange ring and the No. 3 flange ring are fixedly connected by multiple sets of bolts and nuts; Through the above technical solution, by using the No. 1 flange ring and the No. 2 flange ring, as well as the No. 4 flange ring and the No. 3 flange ring, it is convenient to install the differential pressure flowmeter between the No. 1 air outlet duct and the No. 2 air outlet duct, so as to measure the flow rate change value of the air flowing through the No. 1 air outlet duct and the No. 2 air outlet duct, and then reflect the air permeability of the cutting material of the mattress.
[0011] Preferably, a control panel is provided at the rear end of the lower portion of the outer wall of one side of the detection box, and the control panel is electrically connected to the No. 1 servo motor, the No. 2 servo motor and the differential pressure flowmeter respectively; Through the above technical solution, the staff can control the opening and closing of servo motor No. 1, servo motor No. 2 and differential pressure flowmeter respectively through the control panel, and can receive and record the data measured by the differential pressure flowmeter.
[0012] Preferably, the middle parts of the outer walls of the installation frame are respectively fixedly connected with connecting rods, and the sides of the connecting rods away from the center of the detection box are respectively fixedly connected to the detection box; Through the above technical solution, through the coordinated use of multiple connecting rods and the installation frame, it is convenient to install the No. 1 servo motor with fan blades under the placement frame.
[0013] Preferably, a scale is provided at the rear end of the outer wall of one side of the mounting frame, a fixing rod is fixedly connected to the middle of the outer wall of one side of the U-shaped plate, and a triangular indicator block is fixedly connected to one side of the outer wall at the front end of the fixing rod; Through the above technical solution, the scale reading indicated by the triangular indicator block is taken, and the staff manually records the scale reading, and the pressure differential flowmeter is used to measure the flow rate of air flowing through the No. 1 air outlet pipe and the No. 2 air outlet pipe under the corresponding scale reading state, and the measurement results of the air flow rate are transmitted to the control panel and recorded, so as to calculate the change in air flow rate corresponding to different downward pressure distances, and finally use the change result as the result of dynamic detection of the air permeability of the cutting material of the mattress. Beneficial effects
[0014] The present invention provides an air permeability detection device for air fiber mattresses. It has the following beneficial effects: 1. The present invention provides an air permeability testing device for air fiber mattresses. By using a triangular indicator block in conjunction with a scale, workers can visually adjust the height of a U-shaped plate provided with a stainless steel orifice plate, thereby facilitating measurement of the air permeability of the mattress cut material corresponding to different downward pressure distances using a differential pressure flowmeter.
[0015] 2. The present invention provides an air permeability testing device for an air fiber mattress. A load is applied to the cut material of the mattress through a stainless steel orifice plate, and the air permeability of the cut material of the mattress is measured by a differential pressure flowmeter, thereby simulating actual usage conditions and measuring dynamic air permeability test data of the cut material of the mattress. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 It is a schematic diagram of the main structure of the present invention; Figure 2 This is a schematic structural diagram of the sealing door of the present invention in an open state from a first perspective; Figure 3 This is a schematic structural diagram from a second perspective of the sealing door of the present invention in an open state; Figure 4 It is a schematic axial cross-sectional view of a local structure of the present invention; Figure 5 for Figure 4 Enlarged view of point B in the middle; Figure 6 for Figure 4 Enlarged view of point A in the middle.
[0017] in, 1. Test box; 2. Air supply mechanism; 201. Mounting frame; 202. Connecting rod; 203. Servo motor No. 1; 204. Rotating rod; 205. Fan blades; 206. Placement frame; 207. Ventilation holes; 208. Multi-hole ventilation plate; 3. Height adjustment mechanism; 301. Limiting slot; 302. U-shaped plate; 303. Fixing rod; 304. Triangular indicator block; 305. Mounting bracket; 306. Scale; 307. Second servo motor; 308. Driving threaded rod; 309. Mounting slot; 310. Auxiliary bearing; 311. Stainless steel orifice plate; 312. Cavity; 4. Control panel; 5. Sealed door; 6. Observation window; 7. Handle; 8. Flow measurement mechanism; 801. No. 1 air outlet pipe; 802. No. 1 flange ring; 803. Differential pressure flowmeter; 804. No. 2 flange ring; 805. No. 3 flange ring; 806. No. 2 air outlet pipe; 807. No. 4 flange ring; 9. Support leg. DETAILED DESCRIPTION
[0018] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.
[0019] like Figure 1-6 As shown, an embodiment of the present invention provides an air permeability testing device for an air fiber mattress, comprising a testing box 1, an air supply mechanism 2 being provided at the lower portion of the testing box 1, and a height adjustment mechanism 3 and a flow measurement mechanism 8 being provided at the upper portion of the testing box 1; The air supply mechanism 2 includes a mounting frame 201. A servo motor 203 is provided on the inner wall of the mounting frame 201. A rotating rod 204 is fixedly connected to the output shaft of the servo motor 203. A fan blade 205 is fixedly connected to the upper end of the rotating rod 204. A placement frame 206 is fixedly connected to the middle of the inner wall around the detection box 1. A ventilation hole 207 is opened in the middle of the upper surface of the placement frame 206. The height adjustment mechanism 3 includes a U-shaped plate 302 and a mounting bracket 305. The lower end of the mounting bracket 305 is fixedly connected to the upper surface of the detection box 1. The middle of the front and rear inner walls of the detection box 1 are respectively provided with a limit groove 301. The U-shaped plate 302 slides inside the limit groove 301. The lower end of the inner wall of the U-shaped plate 302 near the center of the detection box 1 is fixedly connected to a stainless steel orifice plate 311. The stainless steel orifice plate 311 is snap-connected to the inner wall of the placement frame 206. The flow measurement mechanism 8 includes a No. 1 air outlet pipe 801, a differential pressure flowmeter 803, and a No. 2 air outlet pipe 806. The middle portion of one side of the upper surface of the detection box 1 is connected to the No. 1 air outlet pipe 801. The four corners of the lower surface of the detection box 1 are respectively fixedly connected with support legs 9, and the middle part of the lower surface of the detection box 1 is fixedly connected with a porous ventilation plate 208 by multiple bolts. The support legs 9 improve the stability of the detection box 1, and the porous ventilation plate 208 provides a good air circulation environment for the No. 1 servo motor 203 equipped with fan blades 205, thereby ensuring the gas circulation inside the detection box 1. The front end of the outer wall of one side of the detection box 1 is hingedly connected with a sealing door 5, and the middle part of the outer wall of one side of the front end of the sealing door 5 is provided with an observation window 6. The rear end of the outer wall of one side of the sealing door 5 is fixedly connected with a handle 7. The observation window 6 can facilitate the staff to observe the contact between the stainless steel orifice plate 311 and the cutting material of the mattress, and the sealing door 5 is opened by the handle 7, so as to facilitate The staff places the cut material of the mattress inside the placement frame 206 and makes the cut material of the mattress cover the ventilation hole 207. The inner wall of the upper end of the limiting groove 301 is provided with a rubber sealing ring, and the U-shaped plate 302 fits tightly with the rubber sealing ring. The rubber sealing ring can effectively prevent the air at the upper end of the placement frame 206 in the detection box 1 from leaking between the U-shaped plate 302 and the limiting groove 301. A mounting groove 309 is provided at the center of the upper surface of the detection box 1. An auxiliary bearing 310 is fixedly connected to the inner wall of the mounting groove 309. A cavity 312 is provided in the middle of the upper surface of the mounting frame 305. A No. 2 servo motor 307 is provided in the middle of the upper surface of the mounting frame 305. The output shaft of the No. 2 servo motor 307 is fixedly connected to the driving threaded rod 308. The lower end of the movable threaded rod 308 passes through the cavity 312 and is fixedly connected to the inner wall of the auxiliary bearing 310. The middle part of the outer wall of the driving threaded rod 308 is threadedly connected to the U-shaped plate 302. The driving threaded rod 308 is rotated by the second servo motor 307 to adjust the height of the U-shaped plate 302, so that the stainless steel orifice plate 311 applies a load to the cut material of the mattress, thereby simulating real usage conditions. The rear end of the differential pressure flowmeter 803 is fixedly connected to the second flange ring 804, and the front end of the No. 1 air outlet pipe 801 is fixedly connected to the first flange ring 802. The No. 1 flange ring 802 and the No. 2 flange ring 804 are fixedly connected by multiple sets of bolts and nuts. The front end of the differential pressure flowmeter 803 is fixedly connected to the third flange ring 805, and the No. 2 air outlet pipe 8 06 is fixedly connected to the rear end with a No. 4 flange ring 807, and the No. 4 flange ring 807 and the No. 3 flange ring 805 are fixedly connected by multiple sets of bolts and nuts. By using the No. 1 flange ring 802 and the No. 2 flange ring 804, and the No. 4 flange ring 807 and the No. 3 flange ring 805 in conjunction with each other, it is convenient to install the differential pressure flowmeter 803 between the No. 1 air outlet pipe 801 and the No. 2 air outlet pipe 806, so as to measure the flow rate change value of the air flowing through the No. 1 air outlet pipe 801 and the No. 2 air outlet pipe 806, and then reflect the air permeability of the cutting material of the mattress. A control panel 4 is provided at the rear end of the lower part of the outer wall of one side of the detection box 1. The control panel 4 is electrically connected to the No. 1 servo motor 203, the No. 2 servo motor 307 and the differential pressure flowmeter 803 respectively.The control panel 4 is convenient for the staff to control the opening and closing of the No. 1 servo motor 203, the No. 2 servo motor 307 and the differential pressure flow meter 803 respectively, and can receive and record the data measured by the differential pressure flow meter 803. The middle of the outer wall of the installation frame 201 is fixedly connected with a connecting rod 202, and the side of the connecting rod 202 away from the center of the detection box 1 is fixedly connected to the detection box 1. Through the coordinated use of multiple connecting rods 202 and the installation frame 201, it is convenient to install the No. 1 servo motor 203 with the fan blade 205 under the placement frame 206. The rear end of the outer wall of one side of the mounting frame 305 is provided with a scale 306, and the outer wall of one side of the U-shaped plate 302 is fixedly connected to the detection box 1. A fixing rod 303 is fixedly connected to the middle of the mattress, and a triangular indicator block 304 is fixedly connected to one side of the front outer wall of the fixing rod 303. The scale 306 reading indicated by the triangular indicator block 304 is manually recorded by the staff. The flow rate of air flowing through the first and second air outlet pipes 801 and 806 corresponding to the reading of the scale 306 is measured by the differential pressure flowmeter 803. The air flow measurement results are transmitted to the control panel 4 and recorded, thereby calculating the change in air flow corresponding to different downward pressure distances. Ultimately, the change results are used as the results of the dynamic detection of the air permeability of the mattress cutting material.
[0020] Working principle: When using the air permeability testing device for air fiber mattresses, first, open the sealing door 5 through the handle 7, and place the cut material of the mattress inside the placement frame 206 so that the cut material of the mattress covers the ventilation hole 207. Secondly, close the sealing door 5, and start the second servo motor 307 through the control panel 4 to rotate the driving threaded rod 308, so that the U-shaped plate 302 slides inside the limiting groove 301, and adjust the height of the U-shaped plate 302 so that the stainless steel orifice plate 311 moves downward and contacts the upper surface of the cut material of the mattress. At this time, start the first servo motor 307 through the control panel 4. The fan 205 is driven by the motor 203 to rotate, generating airflow and causing the airflow to flow into the ventilation hole 207. The airflow then passes through the bottom of the mattress material and flows into the upper end of the mattress material, causing the airflow at the upper end of the placement frame 206 inside the detection box 1 to surge and flow into the No. 1 air outlet pipe 801. At the same time, the differential pressure flowmeter 803 is activated through the control panel 4 to measure the flow rate of air flowing through the No. 1 air outlet pipe 801 and the No. 2 air outlet pipe 806. The measurement result is transmitted to the control panel 4 and recorded as S1. The reading of the scale 306 indicated by the triangular indicator block 304 is recorded and manually recorded as L1 by the staff. Next, the second servo motor 307 is activated through the control panel 4, causing the driving threaded rod 308 to rotate, thereby causing the U-shaped plate 302 to slide inside the limiting groove 301. The height of the U-shaped plate 302 is adjusted, causing the stainless steel orifice plate 311 to continue to move downward and apply a load to the cut material of the mattress, causing the stainless steel orifice plate 311 to press the cut material of the mattress. Subsequently, the flow rate of air flowing through the first and second air outlet pipes 801, 806 is again measured by the differential pressure flowmeter 803. The measurement result is transmitted to the control panel 4 and recorded as S2. The reading of the scale 306 indicated by the triangular indicator block 304 is recorded and manually recorded as L2 by the staff. Finally, the staff calculated that the height change value of the above-mentioned stainless steel orifice plate 311 is ΔL=|L1-L2|, and the air flow change value ΔS=|S1-S2|. Taking ΔS and ΔL as the quotient, the slope of the above-mentioned change is obtained as K=ΔS / ΔL. The value of this slope K reflects the results of dynamic testing of the air permeability of the cutting material of the mattress.
[0021] While 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 these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.
Claims
1. An air permeability testing device for an air fiber mattress, comprising a testing box (1), characterized in that: The lower part of the detection box (1) is provided with an air supply mechanism (2), and the upper part of the detection box (1) is provided with a height adjustment mechanism (3) and a flow measurement mechanism (8); The air supply mechanism (2) comprises a mounting frame (201), an inner wall of the mounting frame (201) is provided with a first servo motor (203), an output shaft of the first servo motor (203) is fixedly connected to a rotating rod (204), an upper end of the rotating rod (204) is fixedly connected to a fan blade (205), a placement frame (206) is fixedly connected to the middle of the inner wall around the detection box (1), and a ventilation hole (207) is opened in the middle of the upper surface of the placement frame (206); The height adjustment mechanism (3) comprises a U-shaped plate (302) and a mounting frame (305), the lower end of the mounting frame (305) being fixedly connected to the upper surface of the detection box (1), the middle portions of the inner walls of the front end and the rear end of the detection box (1) are respectively provided with limiting grooves (301), the U-shaped plate (302) slides inside the limiting grooves (301), the lower end of the inner wall of one side of the U-shaped plate (302) near the center of the detection box (1) is fixedly connected to a stainless steel orifice plate (311), and the stainless steel orifice plate (311) is snap-connected to the inner wall of the placement frame (206); The flow measurement mechanism (8) comprises a No. 1 air outlet pipe (801), a differential pressure flow meter (803) and a No. 2 air outlet pipe (806), and the middle portion of one side of the upper surface of the detection box (1) is connected to the No. 1 air outlet pipe (801).
2. The air permeability testing device for an air fiber mattress according to claim 1, characterized in that: The four corners of the lower surface of the detection box (1) are respectively fixedly connected to support legs (9), and the middle portion of the lower surface of the detection box (1) is fixedly connected to a porous ventilation plate (208) via a plurality of bolts.
3. The air permeability testing device for an air fiber mattress according to claim 1, characterized in that: The front end of the outer wall of one side of the detection box (1) is hingedly connected to a sealing door (5), the middle part of the outer wall of the front end of the sealing door (5) is provided with an observation window (6), and the rear end of the outer wall of one side of the sealing door (5) is fixedly connected to a handle (7).
4. The air permeability testing device for an air fiber mattress according to claim 1, characterized in that: A rubber sealing ring is provided on the inner wall of the upper end of the limiting groove (301), and the U-shaped plate (302) is tightly fitted to the rubber sealing ring.
5. The air permeability testing device for an air fiber mattress according to claim 1, characterized in that: A mounting groove (309) is provided at the center of the upper surface of the detection box (1), an auxiliary bearing (310) is fixedly connected to the inner wall of the mounting groove (309), a cavity (312) is provided in the middle of the upper surface of the mounting frame (305), a second servo motor (307) is provided in the middle of the upper surface of the mounting frame (305), an output shaft of the second servo motor (307) is fixedly connected to a driving threaded rod (308), a lower end of the driving threaded rod (308) passes through the cavity (312) and is fixedly connected to the inner wall of the auxiliary bearing (310), and a middle portion of the outer wall of the driving threaded rod (308) is threadedly connected to the U-shaped plate (302).
6. The air permeability testing device for an air fiber mattress according to claim 1, characterized in that: The rear end of the differential pressure flowmeter (803) is fixedly connected to a No. 2 flange ring (804), the front end of the No. 1 air outlet pipe (801) is fixedly connected to a No. 1 flange ring (802), the No. 1 flange ring (802) and the No. 2 flange ring (804) are fixedly connected via multiple sets of bolts and nuts, the front end of the differential pressure flowmeter (803) is fixedly connected to a No. 3 flange ring (805), the rear end of the No. 2 air outlet pipe (806) is fixedly connected to a No. 4 flange ring (807), the No. 4 flange ring (807) and the No. 3 flange ring (805) are fixedly connected via multiple sets of bolts and nuts.
7. The air permeability testing device for an air fiber mattress according to claim 1, characterized in that: A control panel (4) is provided at the rear end of the lower portion of the outer wall of one side of the detection box (1), and the control panel (4) is electrically connected to the first servo motor (203), the second servo motor (307) and the differential pressure flow meter (803), respectively.
8. The air permeability testing device for an air fiber mattress according to claim 1, characterized in that: The middle portions of the outer walls of the installation frame (201) are fixedly connected to connecting rods (202), and the sides of the connecting rods (202) away from the center of the detection box (1) are fixedly connected to the detection box (1).
9. The air permeability testing device for an air fiber mattress according to claim 1, characterized in that: A scale (306) is provided at the rear end of the outer wall of one side of the mounting frame (305), a fixing rod (303) is fixedly connected to the middle portion of the outer wall of one side of the U-shaped plate (302), and a triangular indicator block (304) is fixedly connected to one side of the outer wall of the front end of the fixing rod (303).