Bimetallic strip parallelism detection equipment

Abstract

The present application relates to the technical field of circuit breaker production and testing, and in particular to a device for detecting the parallelism of a bimetallic strip (11). The device comprises a workbench (2), a horizontal clamp (3), a pressing mechanism (4) and a distance sensor (5). When in use, it is only necessary to place a bimetallic strip (11) connected with an arc-starting strip (12) on the workbench (2), and then clamp the arc-starting strip (12) in the horizontal direction by the horizontal clamp (3), and press the arc-starting strip (12) downward by the pressing mechanism (4), and the distance sensor (5) can directly obtain the height data of the bimetallic strip (11), thereby realizing the detection of the parallelism of the bimetallic strip (11). In this way, the parallelism detection device is easy to operate and improves the reliability of the detection of the parallelism of the bimetallic strip (11).

Description

Technical Field

[0001] The present application relates to the technical field of circuit breaker production testing, and in particular to a device for detecting the parallelism of a bimetallic strip. Background Art

[0002] The working principle of thermal overload protection of circuit breakers is to utilize the bending characteristics of bimetal when heated. There are two or more layers of metal with different thermal expansion coefficients in the bimetallic strip. The one with higher expansion coefficient is called active layer, and the one with lower expansion coefficient is called passive layer. When heated, the deformation of active layer is greater than that of passive layer, so the whole bimetallic strip will bend toward the passive layer. In order to ensure the quality of circuit breaker products, the parallelism of bimetallic strips needs to be measured in production to prevent the bimetal from being too high or too low, causing false tripping or no tripping of the product.

[0003] In an existing contact measurement method, when using a height gauge to measure the parallelism of a bimetallic strip, it is necessary to first find a reference surface, then move to the point where the bimetallic strip is in contact, and measure the height between the two points. Since this method is a contact measurement method, the bimetallic strip may be deformed when the height is obtained by contact with the bimetallic strip, and the measured value deviates from the true value, and the gauge has poor repeatability and reproducibility.

[0004] Another non-contact measurement method uses a three-line coordinate measuring machine with higher accuracy, but the instrument is expensive and not easy to carry. It is also complicated to operate and requires professional operators.

[0005] Proposing a set of bimetallic strip parallelism measuring equipment with simple operation and reliable performance is of great significance to the production of circuit breaker products. Summary of the invention

[0006] In view of this, the present application proposes a bimetallic strip parallelism detection device to improve the measurement efficiency and reliability of the bimetallic strip parallelism.

[0007] In one embodiment of the parallelism detection device for a bimetallic strip provided in the present application, the bimetallic strip is connected to an arc-starting strip, and the parallelism detection device comprises a workbench, and a horizontal clamp, a pressing mechanism and a distance sensor arranged on the top side of the workbench. The horizontal clamp is used to clamp the arc-starting strip, and the pressing mechanism is used to press the arc-starting strip downward; the distance sensor is arranged on the workbench through a bracket, and its probe faces downward and directly toward the bimetallic strip.

[0008] It can be seen from the above scheme that when measuring the parallelism of the bimetallic strip, it is only necessary to place a bimetallic strip connected with an arc-starting strip on a workbench, and then clamp the arc-starting strip in the horizontal direction by a horizontal clamp, and use a pressing mechanism to press the arc-starting strip downward, and the distance sensor can directly obtain the height data of the bimetallic strip, thereby realizing the parallelism detection of the bimetallic strip. In this way, the parallelism detection device is simple to operate, and since there is no need to contact the bimetallic strip during detection, it will not cause deformation of the bimetallic strip, thereby improving the reliability of the parallelism detection of the bimetallic strip.

[0009] In a preferred implementation of the parallelism detection device provided in the above embodiment, the parallelism detection device further includes a programmable logic controller and a computer device. The programmable logic controller is connected to the distance sensor for communication and receives measurement data, and the computer device is connected to the programmable logic controller for communication and processes and analyzes the measurement data.

[0010] In a preferred implementation manner of the parallelism detection device provided in the above embodiment, the parallelism detection device also includes a limit bar and a support plate, the limit bar is arranged on the top surface of the workbench; the horizontal clamp and the downward pressing mechanism are fixedly arranged on the support plate, and the support plate is arranged to be able to translate on the top surface of the workbench close to the limit bar.

[0011] In a preferred implementation of the parallelism detection device provided in the above embodiment, the horizontal clamp includes a set of positioning components and a driving mechanism, the positioning component includes at least one fixed block arranged on the support plate, and the driving mechanism drives a moving block to perform telescopic movement toward the positioning component.

[0012] In a preferred implementation of the parallelism detection device provided in the above embodiment, the driving mechanism includes a housing, a cam, a slider and at least one spring. The housing is fixed on the support plate, and a slide groove and at least one mounting hole are arranged inside the housing; the cam is rotatably arranged in the housing, and one end of its rotating shaft extends out of the housing, and an operating part is arranged at the end of the rotating shaft extending out; the slider is slidably arranged in the slide groove, one side of which contacts and cooperates with the cam, and the other side is connected to the moving block; the spring is arranged in the mounting hole, and applies a force to the slider to retract the moving block.

[0013] In a preferred implementation manner of the parallelism detection device provided in the above embodiment, two mounting holes are provided in the housing, the mounting holes are provided on a side of the slide slot close to the moving block, and the spring is a compression spring.

[0014] In a preferred implementation manner of the parallelism detection device provided in the above embodiment, the operating portion is a through hole arranged along the radial direction of the rotating shaft.

[0015] In a preferred implementation manner of the parallelism detection device provided in the above embodiment, a bending plate is provided at one end of the arc-starting plate close to the bimetallic strip, and the two ends of the bending plate are connected by an adjusting bolt; a first gap and a second gap are formed between three parallel fixed blocks, the adjusting bolt is located in the first gap, and the bent portion of the bending plate is located in the second gap; a groove is provided at the front end of the moving block for accommodating one end of the adjusting bolt.

[0016] In a preferred implementation of the parallelism detection device provided in the above embodiment, the pressing mechanism includes a support, a connecting rod, a crossbeam and a handle. The bottom end of the support is arranged on the support plate, and an upper notch is arranged on the top thereof. The first end of the connecting rod is hinged to the upper notch end; the first end of the crossbeam is provided with two hinge holes, one hinge hole is hinged to the upper notch end, and the second end thereof is connected to a pressing rod; the handle is hinged to the second end of the connecting rod, and is also hinged to the other hinge hole of the crossbeam.

[0017] In a preferred implementation of the parallelism detection device provided in the above embodiment, the crossbeam is provided with a long hole along its length direction; the pressing mechanism further includes two slotted washers and two nuts. Among them, one of the two slotted washers is buckled on the upper side of the crossbeam, and the other slotted washers is buckled on the lower side of the crossbeam; each of the two nuts is arranged on a corresponding one of the slotted washers; wherein the pressure rod passes through the long hole and the two slotted washers, and is fixed by two nuts.

[0018] In a preferred implementation of the parallelism detection device provided in the above embodiment, the bracket includes a column and a cross arm. The bottom end of the column is connected to the workbench, one end of the cross arm is provided with the distance sensor, and the other end is bifurcated to form two elastic connecting pieces, the middle parts of the two elastic connecting pieces are arranged around the column, and parallel connecting ends are formed at the ends, and the two parallel connecting ends are fastened with bolts to fix the cross arm on the column. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The preferred embodiments of the present application will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can better understand the above and other features and advantages of the present application. In the accompanying drawings:

[0020] Figure 1 It is a schematic diagram of the connection structure between the bimetallic strip and the arc-starting strip.

[0021] Figure 2 It is a schematic structural diagram of the parallelism detection device of the bimetallic strip in this embodiment.

[0022] Figure 3 Schematic diagram of communication connection in the parallelism detection device of this embodiment.

[0023] Figure 4 Schematic diagram of the internal structure of the horizontal clamp in the parallelism detection device of this embodiment.

[0024] Figure 5 Schematic diagram of the internal structure of the pressing mechanism in the parallelism detection device of this embodiment.

[0025] The reference numerals are as follows:

[0026] 11-bimetallic strip; 111-conducting wire; 12-arc-starting strip; 121-bending plate; 13-adjusting bolt;

[0027] 2-working table; 201-limiting strip; 202-supporting plate;

[0028] 21- bracket; 211- column; 212- cross arm; 2121- elastic connecting piece;

[0029] 3-horizontal fixture; 31-positioning assembly; 311-fixed block; 32-driving mechanism; 321-moving block; 3211-groove; 322-housing; 323-mounting hole; 324-cam; 325-rotating shaft; 3251-through hole; 326-slider;

[0030] 4- Pressing mechanism;

[0031] 41-support; 411-upper notch; 42-connecting rod;

[0032] 43-crossbeam; 431-long hole; 432-slotted gasket; 433-nut;

[0033] 44-pressure rod; 441-rubber pressure head; 45-handle;

[0034] 5- distance sensor; 6- programmable logic controller; 7- computer equipment. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application is further described in detail with reference to the following embodiments.

[0036] In the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0037] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] The working principle of thermal overload protection of circuit breakers is to utilize the bending characteristics of bimetal when heated. There are two or more layers of metal with different thermal expansion coefficients in the bimetallic strip. The one with higher expansion coefficient is called active layer, and the one with lower expansion coefficient is called passive layer. When heated, the deformation of active layer is greater than that of passive layer, so the whole bimetallic strip will bend toward the passive layer. In order to ensure the quality of circuit breaker products, the parallelism of bimetallic strips needs to be measured in production to prevent the bimetal from being too high or too low, causing false tripping or no tripping of the product.

[0039] like Figure 1 As shown, the bimetallic strip 11 is connected to an arc-striking strip 12, and a bent plate 121 is provided at one end of the arc-striking strip 12 close to the bimetallic strip 11. The two ends of the bent plate 121 are connected by an adjusting bolt 13, and the adjusting bolt 13 is used to adjust the horizontal position of the bimetallic strip 11 to ensure that the circuit breaker is tripped when a short circuit occurs. One end of the wire 111 connected to the arc-striking strip 12 is generally connected to the moving contact.

[0040] The present application provides a parallelism detection device for a bimetallic strip 11 , which is used to improve the measurement efficiency and reliability of the parallelism of the bimetallic strip 11 .

[0041] like Figure 2 As shown, the parallelism detection device includes a workbench 2, and a horizontal clamp 3, a pressing mechanism 4 and a distance sensor 5 arranged on the top side of the workbench 2. The horizontal clamp 3 is used to clamp the arc-starting sheet 12, and the pressing mechanism 4 is used to press the arc-starting sheet 12 downward; the distance sensor 5 is arranged on the workbench 2 through a bracket 21, and its probe faces downward and directly toward the bimetallic sheet 11.

[0042] The parallelism detection device includes a workbench 2, a horizontal clamp 3, a pressing mechanism 4 and a distance sensor 5. A bracket 21 is arranged on the workbench 2. The horizontal clamp 3 is arranged on the workbench 2 and is used to clamp the arc-starting sheet 12. The pressing mechanism 4 is arranged on the workbench 2 and presses the arc-starting sheet 12 downward. The distance sensor 5 is arranged on the bracket 21, and its probe faces downward and directly faces the bimetallic strip 11.

[0043] When the parallelism detection device is used to detect the parallelism of the bimetallic strip 11, it is only necessary to place a bimetallic strip 11 connected with an arc-starting strip 12 on the workbench 2, and then clamp the arc-starting strip 12 in the horizontal direction by the horizontal clamp 3, and press the arc-starting strip 12 downward by the pressing mechanism 4, and the distance sensor 5 can directly obtain the height data of the bimetallic strip 11, thereby realizing the detection of the parallelism of the bimetallic strip 11. In this way, the parallelism detection device is simple to operate, and since there is no need to contact the bimetallic strip 11 during detection, the bimetallic strip 11 will not be deformed, thereby improving the reliability of the parallelism detection of the bimetallic strip 11.

[0044] For example, when measuring the parallelism of the bimetallic strip 11, the distance sensor 5 can first measure the distance to the workbench 2, and then measure the distance to the head of the bimetallic strip 11 (that is, the end of the bimetallic strip 11 facing away from the horizontal clamp 3). Based on the difference between the two distances, it can be determined whether the parallelism of the bimetallic strip meets the requirements.

[0045] Preferably, if Figure 3 As shown, the parallelism detection device may also include a programmable logic controller 6 (PLC) and a computer device 7. The programmable logic controller 6 is connected to the distance sensor 5 for communication and receives the measurement data, and the computer device 7 is connected to the programmable logic controller 6 for communication and processes and analyzes the measurement data. In this way, the process of manually recording data is saved, and the efficiency of parallelism detection of the bimetallic strip 11 is further improved.

[0046] Preferably, the parallelism detection equipment also includes a limit bar 201 and a support plate 202, the limit bar 201 is arranged on the top surface of the workbench 2; the support plate 202 is fixedly provided with a horizontal clamp 3 and a pressing mechanism 4, and is configured to be able to translate on the top surface of the workbench 2 close to the limit bar 201.

[0047] In this way, when using the parallelism detection device to perform parallelism detection on the bimetallic strip 11, the bimetallic strip 11 can be first fixed on the support plate 202 using the horizontal clamp 3 and the pressing mechanism 4, and then by moving the support plate 202 along the limit strip 201, the distance sensor can first detect the height data of the support plate 202, and then detect the height data of the bimetallic strip 11, thereby further improving the parallelism detection efficiency of the bimetallic strip 11.

[0048] Preferably, refer to Figure 2 and Figure 4 The horizontal clamp 3 may further include a positioning assembly 31 and a driving mechanism 32. The positioning assembly 31 includes at least one fixed block 311 disposed on the support plate 202. The driving mechanism 32 drives a moving block 321 to telescopically move toward the positioning assembly 31. For example, the driving mechanism 32 may be manual or electric.

[0049] For example, refer to Figure 4 The positioning assembly 31 can be provided with three parallel fixed blocks 311, and a first gap and a second gap are formed between the fixed blocks 311, the adjusting bolt 13 is located in the first gap, and the bent portion of the bent plate 121 is located in the second gap; the front end of the moving block 321 is provided with a groove 3211 for accommodating one end of the adjusting bolt 13. In this way, when the bimetallic strip 11 is detected, necessary accommodation space is provided for related components.

[0050] In a preferred embodiment, referring to Figure 2 and Figure 4 The driving mechanism 32 may include a housing 322, a cam 324, a slider 326 and at least one spring (not shown). The housing 322 is fixed on the support plate 202, and a slide groove and at least one mounting hole 323 are provided inside the housing 322; the cam 324 is rotatably disposed in the housing 322, and one end of the rotating shaft 325 thereof extends out of the housing 322, as shown in FIG. Figure 2 In the figure, one end of the rotating shaft 325 extends upward, and an operating part is provided at the extended end of the rotating shaft 325; a slider 326 is slidably arranged in the slide groove, one side of which is in contact with the cam 324, and the other side is connected to the moving block 321; a spring is arranged in the mounting hole 323, and applies a force to the slider 326 to retract the moving block 321.

[0051] For example, refer to Figure 4 The housing 322 is provided with two mounting holes 323 , the mounting holes 323 are provided on one side of the slideway close to the moving block 321 , and the spring is a compression spring (not shown in the figure). For another example, the operating portion is a through hole 3251 provided along the radial direction of the rotating shaft 325 .

[0052] During the operation of the driving mechanism 32, an operating rod can be inserted into the through hole 3251 of the rotating shaft 325 to rotate the cam 324. When the cam 324 rotates to the point where the large diameter end hits the slider 326, the slider 326 moves toward the moving block 321 and the spring is compressed, pushing the moving block 321 outward and cooperating with the positioning assembly 31 to clamp the arc-starting piece 12. When the cam 324 rotates to the point where the small diameter end hits the slider 326, the slider 326 moves away from the moving block 321 under the elastic force of the spring, and the moving block 321 releases the arc-starting piece 12 or allows the arc-starting piece 12 connected to the bimetallic strip 11 to be tested to be placed.

[0053] Reference Figure 5 In a preferred embodiment, the pressing mechanism 4 includes a support 41, a connecting rod 42, a crossbeam 43 and a handle 45. The bottom end of the support 41 is arranged on the support plate 202, and an upper notch 411 is arranged on the top thereof. The first end of the connecting rod 42 is hinged at the end of the upper notch 411; the first end of the crossbeam 43 is provided with two hinge holes, one hinge hole is hinged at the end of the upper notch 411, and the second end thereof is connected with a pressing rod 44. Preferably, a rubber pressure head 441 may also be provided at the end of the pressing rod 44 to prevent pressure from damaging the arc-starting sheet 12. The handle 45 is hinged to the second end of the connecting rod 42, and is also hinged to another hinge hole of the crossbeam 43.

[0054] Thus, when the handle 45 is manually pressed down, the pressing rod 44 is lifted upwards, so that the bimetallic strip 11 can be placed in the detection position or the bimetallic strip 11 can be taken down from the detection position. When the handle 45 is manually lifted upwards, the pressing rod 44 is pressed down to compress the arc-starting sheet 12.

[0055] Preferably, continue to refer to Figure 5 In a preferred connection mode between the pressure rod 44 and the cross beam 43, the cross beam 43 is provided with a long hole 431 along its length direction, and the pressing mechanism 4 further includes two groove washers 432 and two nuts 433. Among them, one of the two groove washers 432 is buckled on the upper side of the cross beam 43, and the other groove washers 432 is buckled on the lower side of the cross beam 43; each of the two nuts 433 is arranged on a corresponding groove washers 432; wherein the pressure rod 44 is arranged through the long hole 431 and the two groove washers 432, and is fixed by the two nuts 433.

[0056] When the nut 433 is loosened, the pressure rod 44 can move along the long hole 431. In this way, the position of the pressure rod 44 can be adjusted according to the characteristics of the bimetallic strip 11 and the measurement requirements. This allows the parallelism detection device to meet the measurement requirements of bimetallic strips 11 of different specifications, so as to accurately position the bimetallic strip 11.

[0057] In a preferred implementation of the parallelism detection device provided in the above embodiment, referring to Figure 2 The bracket 21 provided with the distance sensor 5 may include a column 211 and a cross arm 212. The bottom end of the column 211 is connected to the workbench 2, one end of the cross arm 212 is provided with the distance sensor 5, and the other end is bifurcated to form two elastic connecting pieces 2121, the middle parts of the two elastic connecting pieces 2121 are surrounded on the column 211, and parallel connecting ends are formed at the ends, and the two parallel connecting ends are fastened with bolts to fix the cross arm 212 on the column 211.

[0058] In this way, after loosening the bolts, the height of the distance sensor 5 can be adjusted by sliding the crossbeam 43 on the column 211, and after tightening the bolts, the crossbeam 43 can be fixed on the column 211, and the distance sensor 5 can be fixed at a certain height.

[0059] The present application relates to the technical field of circuit breaker production and testing, and in particular to a parallelism detection device for a bimetallic strip 11. The parallelism detection device comprises a workbench 2, a horizontal clamp 3, a pressing mechanism 4 and a distance sensor 5. When in use, it is only necessary to place a bimetallic strip 11 connected with an arc-starting strip 12 on the workbench 2, and then clamp the arc-starting strip 12 in the horizontal direction by the horizontal clamp 3, and press the arc-starting strip 12 downward by the pressing mechanism 4, and the distance sensor 5 can directly obtain the height data of the bimetallic strip 11, thereby realizing the detection of the parallelism of the bimetallic strip 11. In this way, the parallelism detection device is simple to operate and improves the reliability of the parallelism detection of the bimetallic strip 11.

[0060] The above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application. The nouns and pronouns about people in this patent application are not limited to specific genders.

Claims

1. A device for detecting the parallelism of a bimetallic strip, wherein the bimetallic strip (11) is connected to an arc-starting strip (12), characterized in that: The parallelism detection device comprises a workbench (2), and arranged on the top side of the workbench (2): A horizontal clamp (3) for clamping the arc-starting piece (12); A pressing mechanism (4) for pressing the arc-starting sheet (12) downwards; A distance sensor (5) is arranged on the workbench (2) via a bracket (21), and its probe faces downward and directly toward the bimetallic strip (11).

2. The parallelism detection device according to claim 1, characterized in that: Also includes: a programmable logic controller (6) which is in communication with the distance sensor (5) and receives measurement data; A computer device (7) is connected to the programmable logic controller (6) for processing and analyzing the measurement data.

3. The parallelism detection device according to claim 1, characterized in that: Also includes: A limiting strip (201) arranged on the top surface of the workbench (2); A support plate (202) on which the horizontal clamp (3) and the pressing mechanism (4) are fixedly arranged, and is arranged to be able to move horizontally on the top surface of the workbench (2) in close contact with the limiting strip (201).

4. The parallelism detection device according to claim 3, characterized in that: The horizontal clamp (3) comprises: A positioning assembly (31) comprising at least one fixing block (311) arranged on a support plate (202); A driving mechanism (32) drives a moving block (321) to move telescopically toward the positioning assembly (31).

5. The parallelism detection device according to claim 4, characterized in that: The driving mechanism (32) comprises: A shell (322) is fixed on the support plate (202), and is provided with a slide groove and at least one mounting hole (323) inside the shell; A cam (324) is rotatably disposed in the housing (322), and one end of a rotating shaft (325) thereof protrudes out of the housing (322), and an operating portion is disposed at the protruding end of the rotating shaft (325); a slider (326) which is slidably disposed in the slide groove, one side of which is in contact with the cam (324) and the other side of which is connected to the moving block (321); At least one spring is arranged in the mounting hole (323) and applies a force to the slider (326) to cause the moving block (321) to retract.

6. The parallelism detection device according to claim 5, characterized in that: Two mounting holes (323) are provided in the housing (322), the mounting holes (323) are provided on a side of the slide slot close to the moving block (321), and the spring is a compression spring; or, The operating portion is a through hole (3251) arranged along the radial direction of the rotating shaft (325).

7. The parallelism detection device according to claim 4, characterized in that: A bent plate (121) is provided at one end of the arc-starting plate (12) close to the bimetallic plate (11), and two ends of the bent plate (121) are connected by an adjusting bolt (13); A first gap and a second gap are formed between the three fixed blocks (311) arranged in parallel, the adjusting bolt (13) is located in the first gap, and the bent portion of the bent plate (121) is located in the second gap; The front end of the moving block (321) is provided with a groove (3211) for accommodating one end of the adjusting bolt (13).

8. The parallelism detection device according to claim 3, characterized in that: The pressing mechanism (4) comprises: A support (41), the bottom end of which is arranged on the support plate (202) and the top of which is provided with an upper notch (411); a connecting rod (42), a first end of which is hinged to the end of the upper notch (411); A crossbeam (43), a first end of which is provided with two hinge holes, one of which is hinged to the end of the upper notch (411), and a second end of which is connected to a pressure rod (44); A handle (45) is hinged to the second end of the connecting rod (42) and is also hinged to another hinge hole of the crossbeam (43).

9. The parallelism detection device according to claim 8, characterized in that: The crossbeam (43) is provided with a long hole (431) along its length direction; the pressing mechanism (4) further comprises: Two grooved gaskets (432), one grooved gasket (432) is buckled on the upper side of the crossbeam (43), and the other grooved gasket (432) is buckled on the lower side of the crossbeam (43); two nuts (433), each nut (433) being arranged on a corresponding one of the groove-shaped washers (432); The pressure rod (44) is disposed through the long hole (431) and the two groove-shaped washers (432), and is fixed by two nuts (433).

10. The parallelism detection device according to claim 1, characterized in that: The support (21) comprises: A column (211), the bottom end of which is connected to the workbench (2); A horizontal arm (212) is provided with the distance sensor (5) at one end, and the other end is bifurcated to form two elastic connecting pieces (2121), the middle parts of the two elastic connecting pieces (2121) are arranged around the upright post (211), and parallel connecting ends are formed at the ends, and the horizontal arm (212) is fixed to the upright post (211) after the two parallel connecting ends are fastened with bolts.

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