Core rod for precision catheter in-diameter inspection mistake-proofing function and method of use

Abstract

The application discloses a kind of mandrel for precision catheter inner diameter inspection mistake-proof function and method, including mandrel main body and multiple detection components, multiple detection components are evenly arranged around mandrel main body;The detection component includes first connecting rod, second connecting rod, first spring and second spring, two ends of first connecting rod are lower limit detection end and first linkage end respectively, two ends of second connecting rod are upper limit detection end and second linkage end respectively;First connecting rod and second connecting rod are hinged to mandrel main body;Second linkage end of second connecting rod is pressed on first linkage end of first connecting rod;First spring is arranged between first connecting rod and mandrel main body, and first spring pushes lower limit detection end of first connecting rod to lift;Second spring is arranged between second connecting rod and mandrel main body, and second spring pushes upper limit detection end of second connecting rod to lift.When using, by the relative position of connecting rod and catheter, whether catheter is qualified can be quickly judged.

Description

Technical Field

[0001] This invention relates to the field of pipe bending equipment, and more particularly to a mandrel for use in precision conduits with inner diameter inspection and error prevention function, and a method of using it. Background Technology

[0002] Aircraft and rocket conduits play a crucial role in preparation, including fuel input, mechanism activation, pressure control, and environmental regulation. Failure or damage to any part of them could lead to a major tragedy of aircraft crashing and loss of life, or rocket failure, directly impacting the safety of officers, soldiers, and passengers.

[0003] The existing method for distinguishing pipe fittings is to mark the surface of the pipe fitting with a code. Before bending the pipe, the worker selects the corresponding blank pipe according to the requirements, or the worker measures the pipe fitting before bending it.

[0004] Normally, workers use calipers or plug gauges to inspect the blank pipes. Due to the varying skill levels of workers, manual measurement still has errors. Furthermore, after working for a long time, workers may make mistakes in picking up or testing the wrong pipe. The cost of a single conduit is very high, and when inspecting the finished pipes, the finished products often turn out to be substandard. Summary of the Invention

[0005] To address the problem of errors and omissions that easily occur when manually inspecting pipe diameter using calipers or plug gauges in existing technologies, the present invention aims to provide a mandrel with error-proofing function for inspecting the inner diameter of precision conduits and a method for using it, which can inspect each conduit and ensure that every processed conduit is qualified.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a mandrel for error prevention function of precision catheter inner diameter inspection, comprising a mandrel body and multiple sets of detection components, wherein the multiple sets of detection components are evenly arranged around the mandrel body; The detection assembly includes a first link, a second link, a first spring, and a second spring. The two ends of the first link are a lower limit detection end and a first linkage end, respectively, and the two ends of the second link are an upper limit detection end and a second linkage end, respectively. Both the first and second links are hinged to the mandrel body; The lower limit detection end of the first link and the upper limit detection end of the second link are set opposite to each other, and the second linkage end of the second link presses on the first linkage end of the first link; The first spring is disposed between the first connecting rod and the core rod body, and the first spring pushes the lower limit detection end of the first connecting rod to tilt up; The second spring is positioned between the second connecting rod and the core rod body. The second spring pushes the upper limit detection end of the second connecting rod upwards. The accuracy of the inner diameter of the catheter includes the upper limit, the upper acceptable limit, the lower acceptable limit, and the lower limit, which are successively reduced in size; In multiple sets of detection components, the vertices of multiple upper limit detection ends are located on the same circumference, which is the upper limit precision circle. The size of the upper limit precision circle is between the extreme upper limit and the qualified upper limit. In multiple detection components, the vertices of multiple lower limit detection ends are located on the same circumference, which is the lower limit accuracy circle. The size of the lower limit accuracy circle is between the qualified lower limit and the extreme lower limit.

[0007] Preferably, multiple receiving grooves are evenly formed on the outer circumferential surface of the mandrel body, and the multiple receiving grooves correspond one-to-one with multiple sets of detection components. The first connecting rod, the second connecting rod, the first spring and the second spring are all installed in the receiving grooves, and the lower limit detection end of the first connecting rod and the upper limit detection end of the second connecting rod extend out from the receiving grooves.

[0008] Preferably, the first spring and the second spring have the same specifications.

[0009] Preferably, the lower limit detection end of the first link is arc-shaped.

[0010] Preferably, the upper limit detection end of the second link protrudes outward from the main body of the mandrel, making the second link hook-shaped.

[0011] Preferably, the size of the lower limit accuracy ring and the upper limit accuracy ring is adjusted by grinding the lower limit detection end of the first connecting rod and the upper limit detection end of the second connecting rod.

[0012] Preferably, the size of the lower and upper precision rings is adjusted by changing the connection position of the first and second links.

[0013] Preferably, the mandrel body includes a first connecting part and a second connecting part, a first connecting rod and a second connecting rod are respectively installed on the first connecting part and the second connecting part, a shim is provided between the first connecting part and the second connecting part, and the first connecting part and the second connecting part are fixedly connected; by changing the number or thickness of the shim, the distance between the first connecting rod and the second connecting rod is adjusted, thereby adjusting the size of the lower limit precision ring and the upper limit precision ring.

[0014] The method of using the aforementioned mandrel is as follows: first, insert the mandrel body into the end of the conduit. When the inner diameter of the conduit is less than its lower limit: the wall of the conduit will abut against the lower limit detection end of the first link, the conduit will drive the first link to swing and compress the first spring, the first linkage end of the first link will tilt upward and push the second linkage end of the second link to tilt upward, the upper limit detection end of the second link will swing into the core rod body, thereby causing the second link to insert into the conduit. When the inner diameter of the catheter is greater than its upper limit: both the first and second links can be inserted into the catheter; When the inner diameter of the catheter is within acceptable limits: the first connecting rod is inserted into the catheter, and the upper limit detection end of the second connecting rod abuts against the end of the catheter.

[0015] The beneficial effects of the technical solution of the present invention are as follows: Since a mandrel is required to support the tube wall during the bending process of the precision conduit, the present solution adds a detection device to the end of the mandrel. This does not affect the specific use of the mandrel and can ensure that each mandrel is strictly inspected before bending, thereby enabling timely detection of problems, ensuring the success rate of conduit bending, ensuring the quality of the finished product after bending, and reducing the production of finished products. Attached Figure Description

[0016] Figure 1 A schematic diagram of the connection structure between the mandrel and the catheter when the inner diameter of the catheter is too large; Figure 2 This is a schematic diagram of the mandrel structure in Example 1; Figure 3 This is a schematic diagram of the second link; Figure 4 This is a schematic diagram of the first link; Figure 5 This is a schematic diagram of the mandrel structure in Example 2; Figure 6 A schematic diagram of the connection structure between the mandrel and the catheter when the inner diameter of the catheter is relatively small; Figure 7 This is a schematic diagram of the connection structure between the mandrel and the catheter when the inner diameter of the catheter is within acceptable limits.

[0017] Reference numerals: 21. Core rod body; 22. Bolt; 23. Connecting column; 24. Core rod bead; 241. Connecting part; 242. Positioning pin; 243. Support part; 244. Baffle; 3. Guide tube; 71. First connecting rod; 711. Lower limit detection end; 712. First linkage end; 72. Second connecting rod; 721. Upper limit detection end; 722. Second linkage end; 73. First spring; 74. Second spring; 75. First hinge shaft; 76. Second hinge shaft; 77. Washer. Detailed Implementation

[0018] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0019] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more, unless explicitly defined otherwise.

[0021] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0022] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature. Example 1

[0023] like Figure 1-4 The illustrated mandrel for error prevention in precision catheter inner diameter inspection includes a mandrel body 21 and multiple sets of detection components, which are evenly arranged around the mandrel body 21; as shown Figure 1As shown, the detection assembly includes a first connecting rod 71, a second connecting rod 72, a first spring 73, and a second spring 74. The two ends of the first connecting rod 71 are a lower limit detection end 711 and a first linkage end 712, respectively. The two ends of the second connecting rod 72 are an upper limit detection end 721 and a second linkage end 722, respectively. Both the first connecting rod 71 and the second connecting rod 72 are hinged to the mandrel body 21. The lower limit detection end 711 of the first connecting rod 71 and the upper limit detection end 721 of the second connecting rod 72 are arranged opposite to each other. The second linkage end 722 of the second connecting rod 72 presses on the first linkage end 712 of the first connecting rod 71. The first spring 73 is disposed between the first connecting rod 71 and the mandrel body 21. The first spring 73 pushes the lower limit detection end 711 of the first connecting rod 71 to tilt upwards. The second spring 74 is disposed between the second connecting rod 72 and the core rod body 21. The second spring 74 pushes the upper limit detection end 721 of the second connecting rod 72 to tilt up. The accuracy of the inner diameter of the conduit includes the limit upper limit, the qualified upper limit, the qualified lower limit and the limit lower limit, which are successively reduced in size. In multiple sets of detection components, the vertices of multiple upper limit detection ends 721 are located on the same circle, which is the upper limit accuracy circle. The size of the upper limit accuracy circle is between the extreme upper limit and the qualified upper limit. In multiple sets of detection components, the vertices of multiple lower limit detection ends 711 are located on the same circle, which is the lower limit accuracy circle. The size of the lower limit accuracy circle is between the qualified lower limit and the extreme lower limit.

[0024] The method of using the mandrel is as follows: first insert the mandrel body 21 into the end of the conduit 3; When the inner diameter of catheter 3 is less than its lower limit: For example Figure 6 As shown, the wall of the conduit 3 will abut against the lower limit detection end of the first connecting rod 71. The conduit 3 drives the first connecting rod 71 to swing and compress the first spring 73. The first linkage end 712 of the first connecting rod 71 tilts upward and pushes the second linkage end 722 of the second connecting rod 72 to tilt upward. The upper limit detection end 721 of the second connecting rod 72 swings into the core rod body 21, thereby causing the second connecting rod 72 to be inserted into the conduit 3. When the inner diameter of catheter 3 is greater than its upper limit: such as Figure 1 As shown, both the first connecting rod 71 and the second connecting rod 72 can be inserted into the conduit 3; When the inner diameter of catheter 3 is within acceptable limits: For example Figure 7 As shown, the first connecting rod 71 is inserted into the conduit 3, and the upper limit detection end 721 of the second connecting rod 72 abuts against the end of the conduit 3.

[0025] This design is because the precision conduit 3 requires a mandrel to support its wall during the bending process. Therefore, this solution adds a detection device to the end of the mandrel without affecting its use. It also ensures that each mandrel is strictly inspected before bending, thereby enabling timely detection of problems, ensuring the success rate of conduit 3 bending, guaranteeing the quality of the finished product after bending, and reducing the production of finished products.

[0026] To ensure detection accuracy, in this embodiment, the first spring 73 and the second spring 74 are of the same specifications. This arrangement allows for precision machining and control of both the connecting rod and the core rod body 21, ensuring that the force of each spring is consistent, thus guaranteeing detection accuracy.

[0027] To improve detection accuracy, in this embodiment, such as Figure 1 and Figure 2 As shown, the mandrel body 21 has multiple receiving slots 212, and multiple sets of detection components are connected to these slots. A first connecting rod 71, a second connecting rod 72, a first spring 73, and a second spring 74 are disposed within the receiving slots 212. The lower limit detection end 711 of the first connecting rod 71 and the upper limit detection end 721 of the second connecting rod 72 both extend from the receiving slots 212. This arrangement allows the outer diameter of the mandrel body 21 to be as close as possible to the inner diameter of the conduit 3, thereby ensuring that the first connecting rod 71 is used only to detect the inner diameter of the conduit 3, improving the accuracy of the inner diameter calibration.

[0028] To make the detection device more sensitive, in this embodiment, such as Figure 3 and Figure 4 As shown, the lower limit detection end 711 of the first connecting rod 71 is arc-shaped, so that the part of the first connecting rod 71 protruding from the receiving groove 212 is arc-shaped, thereby making the detection of the lower limit of the inner diameter of the conduit 3 more sensitive.

[0029] In a further preferred embodiment, the upper limit detection end 721 of the second connecting rod 72 protrudes outward from the outer side of the core rod body 21 with a limiting protrusion, making the second connecting rod 72 hook-shaped; when the inner diameter of the conduit 3 is qualified or too large, the limiting protrusion is in a vertical state; when the inner diameter of the conduit 3 is too small, the wall of the conduit 3 squeezes the first connecting rod 71, the first connecting rod 71 pushes the second connecting rod 72 to swing, and the limiting protrusion is tilted.

[0030] To facilitate the fabrication of the detection device, in this embodiment, as follows: Figure 1 and Figure 2 As shown, the first connecting rod 71 is hinged to the mandrel body 21 via the first hinge shaft 75, and the second connecting rod 72 is hinged to the mandrel body 21 via the second hinge shaft 76; the distance from the first hinge shaft 75 to the first linkage end 712 is greater than the distance from the second hinge shaft 76 to the second linkage end 722; on the second connecting rod 72, the distance from the second hinge shaft 76 to the second linkage end 722 is less than the distance from the second hinge shaft 76 to the upper limit detection end 721; on the first connecting rod 71, the distance from the first hinge shaft 75 to the first linkage end 712 is less than the distance from the first hinge shaft 75 to the lower limit detection end 711.

[0031] In this embodiment, as Figure 1 and Figure 2 As shown, the mandrel also includes multiple mandrel beads 24, which are arranged one by one and connected movably through a ball head structure. The mandrel beads 24 are connected to the mandrel body 21 through the ball head, and the mandrel beads 24 are installed on the end of the mandrel body 21 near the lower limit detection end 711.

[0032] Before using the mandrel, the mandrel bead 24 is inserted into the conduit 3, and then the mandrel body 21 is inserted into the conduit 3. Then, by judging whether the second connecting rod 72 has been activated, it is determined whether the conduit 3 is qualified, too large or too small.

[0033] With this setup, the mandrel beads 24 support each part of the conduit 3, ensuring the bending effect of the conduit 3.

[0034] In order to achieve the relative movement of the core bead 24, in this embodiment, as follows: Figure 2 and Figure 1 As shown, the core rod bead 24 includes a support portion 243 and a connecting portion 241. The support portion 243 is sleeved and fixed on the connecting portion 241. Two adjacent core rod beads 24 are connected through their respective connecting portions 241. The support portion is in the shape of two halves and is fixedly connected by a positioning pin 242. Specifically, a limiting part protrudes from the outer peripheral surface of the connecting part 241, a limiting groove is formed on the outer peripheral surface of the connecting part 241, a baffle 244 is snapped onto the connecting part 241, a ball head protrudes from one end of the connecting part 241, a ball groove is formed at the other end of the connecting part 241, and a support part 243 is sleeved on the connecting part 241. The support part 243 is clamped by the baffle 244 and the limiting part. When connecting two core beads, which are the first core bead and the second core bead, the first core bead is assembled first. Then, the ball head of the first core bead is clamped by the connecting part of the second core bead. The connecting part of the second core bead is then fixed into a whole by a positioning pin. Then, the supporting part of the second core bead is put on the connecting part of the second core bead. Finally, a baffle is put on the connecting part of the second core bead, thus connecting the first core bead and the second core bead together.

[0035] To facilitate the connection between the mandrel body and the mandrel bead, in this embodiment, the mandrel body 21 has a positioning groove and a connecting groove 211 at both ends, and a through hole is provided between the positioning groove and the connecting groove 211. A connecting post 23 is inserted into the connecting groove 211. One end of the connecting post 23 has a ball groove, and the other end of the connecting post 23 has a threaded hole. A bolt 22 is inserted into the positioning groove, and the threaded part of the bolt passes through the through hole and is threadedly connected to the threaded hole of the connecting post. The ball head of the mandrel bead is inserted into the ball groove of the connecting post 23.

[0036] Furthermore, such as Figure 2 and Figure 1 As shown, the connecting post 23 is bilobed. The two connecting posts 23 are joined together to clamp the ball head of the mandrel bead. Then the connecting post 23 is inserted into the connecting groove 211 of the mandrel body 21. The bolt is inserted into the positioning groove. The threaded part of the bolt passes through the through hole and is threadedly connected to the threaded hole of the connecting post.

[0037] In this embodiment, the size of the lower limit precision circle and the upper limit precision circle are adjusted by grinding the lower limit detection end 711 of the first connecting rod 71 and the upper limit detection end 721 of the second connecting rod 72. Example 2

[0038] Unlike Embodiment 1, in this embodiment, the size of the lower limit precision circle and the upper limit precision circle are adjusted by adjusting the distance between the first link 71 and the second link 72.

[0039] Specifically, such as Figure 5 As shown, the mandrel body 21 includes a first connecting part 2100 and a second connecting part 2101. A first connecting rod 71 and a second connecting rod 72 are respectively installed on the first connecting part 2100 and the second connecting part 2101. The first connecting part 2100 and the second connecting part 2101 are fixedly connected. A shim 77 is provided between the first connecting part 2100 and the second connecting part 2101. By adjusting the number and thickness of the shims 77, the distance between the first connecting rod 71 and the second connecting rod 72 can be adjusted, thereby adjusting the size of the lower limit precision ring and the upper limit precision ring.

[0040] More preferably, the positioning groove, the connecting groove 211, and the through hole are all provided on the second connecting part 2101, and the receiving groove 212 is provided on the first connecting part 2100 and the second connecting part 2101 respectively; the first connecting part 2100 is sleeved on the connecting post 23, and the first connecting part 2100 is threadedly connected to the connecting post 23; the washer 77 is sleeved on the connecting post 23; one end of the connecting post 23 is inserted into the positioning groove of the second connecting part 2101; the bolt 22 is inserted into the positioning groove; and the threaded part of the bolt passes through the through hole and is threadedly connected to the threaded hole of the connecting post.

[0041] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0042] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A mandrel for use in precision catheters with inner diameter inspection and error prevention function, characterized in that: It includes a core rod body (21) and multiple sets of detection components, which are evenly arranged around the core rod body (21); The detection assembly includes a first link (71), a second link (72), a first spring (73), and a second spring (74). The two ends of the first link (71) are the lower limit detection end (711) and the first linkage end (712), respectively. The two ends of the second link (72) are the upper limit detection end (721) and the second linkage end (722), respectively. Both the first link (71) and the second link (72) are hinged to the core rod body (21); The lower limit detection end (711) of the first link (71) and the upper limit detection end (721) of the second link (72) are arranged opposite to each other, and the second linkage end (722) of the second link (72) presses on the first linkage end (712) of the first link (71); The first spring (73) is located between the first connecting rod (71) and the core rod body (21). The first spring (73) pushes the lower limit detection end (711) of the first connecting rod (71) to tilt up. The second spring (74) is positioned between the second connecting rod (72) and the core rod body (21). The second spring (74) pushes the upper limit detection end (721) of the second connecting rod (72) upward. The accuracy of the inner diameter of the catheter includes the upper limit, the upper acceptable limit, the lower acceptable limit, and the lower limit, which are successively reduced in size; In multiple sets of detection components, the vertices of multiple upper limit detection ends (721) are located on the same circumference, which is the upper limit accuracy circle. The size of the upper limit accuracy circle is between the limit upper limit and the acceptable upper limit. In multiple sets of detection components, the vertices of multiple lower limit detection ends (711) are located on the same circumference, which is the lower limit accuracy circle. The size of the lower limit accuracy circle is between the qualified lower limit and the extreme lower limit.

2. A mandrel for error prevention in precision catheter with inner diameter inspection according to claim 1, characterized in that: Multiple receiving slots (212) are evenly provided on the outer circumferential surface of the mandrel body (21). The multiple receiving slots (212) correspond one-to-one with multiple sets of detection components. The first connecting rod (71), the second connecting rod (72), the first spring (73), and the second spring (74) are all installed in the receiving slots (212). The lower limit detection end (711) of the first connecting rod (71) and the upper limit detection end (721) of the second connecting rod (72) extend out from the receiving slots (212).

3. A mandrel for error prevention in precision catheter with inner diameter inspection according to claim 1, characterized in that: The first spring (73) and the second spring (74) have the same specifications.

4. A mandrel for error prevention in precision catheter with inner diameter inspection according to claim 1, characterized in that: The lower limit detection end (711) of the first link (71) is arc-shaped.

5. A mandrel for error prevention in precision catheter with inner diameter inspection according to claim 1, characterized in that: The upper limit detection end (721) of the second link (72) protrudes outward from the core rod body (21), making the second link (72) hook-shaped.

6. A mandrel for error prevention in precision catheter with inner diameter inspection according to claim 1, characterized in that: The size of the lower limit precision ring and the upper limit precision ring are adjusted by grinding the lower limit detection end (711) of the first link (71) and the upper limit detection end (721) of the second link (72).

7. A mandrel for error prevention in precision catheter with inner diameter inspection according to claim 1, characterized in that: The size of the lower and upper precision rings is adjusted by changing the connection position of the first link (71) and the second link (72).

8. A mandrel for checking the inner diameter of a precision catheter with error prevention function according to claim 7, characterized in that: The core rod body (21) includes a first connecting part (2100) and a second connecting part (2101). A first connecting rod (71) and a second connecting rod (72) are respectively installed on the first connecting part (2100) and the second connecting part (2101). A gasket (77) is provided between the first connecting part (2100) and the second connecting part (2101). The first connecting part (2100) and the second connecting part (2101) are fixedly connected. By changing the number or thickness of the shims (77), the distance between the first link (71) and the second link (72) is adjusted, thereby adjusting the size of the lower and upper precision rings.

9. A method of using a mandrel with error-proofing function for checking the inner diameter of a precision catheter, as described in any one of claims 1-8, characterized in that: The method of use is as follows: first insert the mandrel body (21) into the end of the conduit. When the inner diameter of the conduit is less than its lower limit: the wall of the conduit will abut against the lower limit detection end of the first link (71), the conduit drives the first link (71) to swing and compress the first spring (73), the first linkage end (712) of the first link (71) tilts upward and pushes the second linkage end (722) of the second link (72) to tilt upward, the upper limit detection end (721) of the second link (72) swings into the core rod body (21), thereby causing the second link (72) to insert into the conduit; When the inner diameter of the catheter is greater than its upper limit: both the first link (71) and the second link (72) can be inserted into the catheter; When the inner diameter of the catheter is qualified: the first connecting rod (71) is inserted into the catheter, and the upper limit detection end (721) of the second connecting rod (72) abuts against the end of the catheter.

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