A wire flame retardant testing machine

Abstract

The present invention discloses a wire flame retardancy testing machine, which belongs to the technical field of wire flame retardancy detection equipment. The wire flame retardancy testing machine comprises a combustion chamber for installing the wire, wherein two fixing parts for fixing the two ends of the wire and a flame spray gun are provided in the combustion chamber. The wire is fixed between the two fixing parts in a slanted and straightened form. The flame spray gun is installed on one side of the wire near the bottom end, and the flame spraying direction is arranged perpendicularly to the wire. During the detection, the wire flame retardancy testing machine can intuitively evaluate whether the flame retardancy is qualified based on the remaining complete length of the wire after the wire burns at the same time, thereby avoiding the influence of human subjective factors.

Description

Technical Field

[0001] The invention relates to the technical field of wire flame retardancy testing equipment, in particular to a wire flame retardancy testing machine. Background Art

[0002] Electrical wires are widely used in daily life and industrial production. If sparks or overheating occur due to short circuits, overloads, or other issues, wires with excellent flame retardancy can effectively prevent the rapid spread of flames, greatly reducing the possibility of fire. For example, in crowded places such as shopping malls, schools, and hospitals, wires with excellent flame retardancy can buy more time for rescue and reduce fire losses.

[0003] To test the flame retardancy of wires, a commonly used method is to vertically mount a certain length of wire sample, ignite it with a specified flame at the lower end for a specified period of time, then remove the flame and observe the burning behavior of the sample. For example, depending on design requirements, the flame may be removed after 10 minutes of ignition. The burning time, any dripping, and whether the dripping ignites the cotton wool are recorded. If the sample extinguishes itself within the specified time after the flame is removed, and if the dripping does not ignite the cotton wool, the wire is considered to have passed the vertical combustion test and possesses a certain degree of flame retardancy. Generally speaking, wires that pass this test are considered to have good flame retardancy when installed vertically.

[0004] Alternatively, a specific flame is ignited at one end of the wire to be tested, and the speed and distance of the flame spreading along the wire is observed. During the test, parameters such as the flame temperature and application time must be strictly controlled. If the flame spread speed is lower than a certain value, or it extinguishes itself within a certain distance, it indicates that the horizontal flame retardant performance of the wire meets the standard. This test simulates the burning conditions of wires when laid horizontally.

[0005] Existing techniques also use a small flame generated by a needle burner, applied to the wire insulation for a specified time, to evaluate the wire's flame retardancy when exposed to a small flame source. The test requires precise control of the needle flame's size, temperature, and application time. If the specimen does not ignite within the specified time, or if it ignites briefly but extinguishes itself within the specified time without igniting surrounding materials, the wire is considered to have passed the needle flame test, indicating that it exhibits good flame retardancy when exposed to similar small flame sources.

[0006] There is an obvious problem with the above existing testing equipment, that is, the judgment of the test results cannot be specific and parameterized, and it requires very high operating experience of the experimenter, and it can be said that it is seriously dependent on the detection level of the tester. Moreover, some equipment only focuses on the flame retardancy of wires when they are laid horizontally or vertically, and the detection is very limited. Summary of the Invention

[0007] In response to the shortcomings of the existing technology, the present invention provides a wire flame retardant testing machine. The wire flame retardant testing machine has a simple structure and is mainly based on the preliminary quantitative evaluation and detection of the flame retardancy of the wire. It is easy to operate and can intuitively and accurately judge the flame retardancy qualification of the wire. It has lower requirements and dependence on the experience level of the testers, the result judgment is more objective, and it is easier to realize automated detection.

[0008] To achieve the above-mentioned object, the present invention provides the following technical solution: a wire flame retardant testing machine, comprising a combustion chamber for installing the wire, the combustion chamber being provided with two fixing parts for fixing the two ends of the wire, and a flame spray gun, the wire being fixed between the two fixing parts in a diagonally stretched and straightened form, the flame spray gun being installed on one side of the wire near the bottom end, and the flame spraying direction being arranged perpendicularly to the wire.

[0009] Furthermore, the combustion chamber is a rectangular structure with an open top and front, and two fixing parts are located at both ends of the combustion chamber in the diagonal direction. The flame spray gun is arranged near the bottom of the combustion chamber and on the side of the wire at the lower diagonal and perpendicular to the wire.

[0010] Furthermore, the fixing part includes a column and a locking stud. The column is arranged perpendicular to the inner rear wall of the combustion chamber. A wire threading groove parallel to the line connecting the two fixing parts is provided in the column. The locking stud is arranged perpendicular to the wire threading groove and is screwed into the wire threading groove to press and fix the wires in the wire threading groove.

[0011] Furthermore, a lead screw installed in situ for self-rotation is provided behind the columns, the lead screw is arranged parallel to the wire threading groove, a threaded slider is threadedly sleeved on the lead screw, the threaded slider is fixed as a whole with a mounting column, the mounting column is arranged parallel to the columns, and a wire groove coaxial with the wire threading groove is provided inside; an elastic clamping component is also fixed on the mounting column, the elastic clamping component is used to clamp the wires, and the clamping force between the elastic clamping component and the wires is an elastic force, and the elastic clamping component can straighten the wires when moving along the direction of the lead screw, and after straightening, it can slide axially relative to the straightened wires to a set position.

[0012] Furthermore, the elastic clamping assembly includes a pair of clamping arms and clamping blocks arranged facing each other, the clamping arm and clamping block on each side are fixedly connected, the clamping arm is Π-shaped, one end of which slides into the mounting arm along the radial direction of the mounting column, and the clamping block is fixed to the other end, and arc-shaped grooves are provided on the opposite end faces of the clamping block. When the two arc-shaped grooves are close, the power line is squeezed through; the two clamping arms are elastically connected together by a clamping spring, and the clamping spring makes the two arc-shaped grooves fit together to form a cylindrical hole under normal conditions, and the cylindrical hole is coaxial with the wire groove.

[0013] Furthermore, a G-shaped curved arm is fixed on the clamping arm, the vertical arm section of the curved arm is vertically fixed to a section of the clamping arm near the mounting column, the horizontal arm section of the curved arm is slidably fitted into a mounting tube, and is installed axially aligned with the mounting tube, a guide slider is fixed to the end of the horizontal arm section, and the guide slider is connected to the clamping spring which is always in an extruded state on one end face of the horizontal arm section, and the clamping spring is sleeved on the horizontal arm section.

[0014] Furthermore, the end of the clamping spring facing away from the guide slider is connected to a positioning ring, and the positioning ring is axially slidably sleeved on the horizontal arm section. The end of the positioning ring facing away from the clamping spring is provided with an adjusting stud axially parallel to the clamping spring. One end of the adjusting stud is rotatably connected to the end face of the positioning ring and does not separate, and the other end thereof extends out of the end portion of the mounting tube and is coaxially fixed with a cylindrical long gear. The two opposite cylindrical long gears are simultaneously engaged with a flat gear ring located above them, and the flat gear is rotatably installed around the central vertical axis of the mounting tube.

[0015] Furthermore, the flat gear ring is fixed on the bottom end surface of a rotating cover, and the rotating cover is coaxially rotatably sleeved on a core column fixed to the center of the mounting tube. The upper section of the core column is provided with a thread, so that the rotating cover is axially compressed and fixed by a locking nut threaded on the core column.

[0016] Furthermore, a tubular contact piece is embedded in the end face of at least one of the clamping blocks, and the contact piece is used to contact the electric wire, and a pressure sensor is installed on the outer side of the contact piece in direct contact with it; when the burning of the electric wire ends, the screw is driven to reverse, so that the elastic clamping assembly moves in a straight line while clamping the remaining electric wire. When the pressure value detected by the pressure sensor is zero or drops to a set value, the motor driving the screw stops immediately and / or records the number of reverse revolutions at this time.

[0017] Furthermore, conductive rings are embedded in the end faces of the two clamps facing each other. When the two conductive rings are in contact, a control circuit will be turned on. The control circuit controls the start and stop of the motor used to drive the screw. When the control circuit is turned on, the motor stops immediately and / or the number of reverse revolutions at this time is recorded.

[0018] The present invention provides a wire flame retardant tester, which has the following beneficial effects: the wire flame retardant tester has a simple and reliable structure, a high degree of automatic sliding, and a more accurate and intuitive determination of the combustion detection results. By using an obliquely stretched and straightened wire, taking into account both horizontal and vertical laying, the ignition is started at a fixed point, and within the same time, the length of the final remaining wire is checked to intuitively characterize the flame retardant performance of the corresponding wire. Moreover, the present invention can also automatically measure the length of the wire required for the experiment while fixing the cable, killing two birds with one stone, which is very clever. In addition, after the combustion is completed, it is only necessary to fix the upper fixing part to fix the upper end of the wire, and then reverse the screw. In the process of the threaded block sliding down and resetting, once it slides to the burned part of the wire, it will trigger the screw to stop rotating, and thus automatically measure the remaining intact wire length, and then derive the flame retardant performance of the wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A front view of the present invention;

[0020] Figure 2 A cross-sectional view of the present invention in which a plane of a certain cross section of the column is located is a cross-sectional view;

[0021] Figure 3 for Figure 2 A magnified view of the structure at point A;

[0022] Figure 4 for Figure 2 A magnified view of the structure at B in the middle;

[0023] Figure 5 is a vertical cross-sectional view of the elastic clamping assembly;

[0024] Figure 6 A partial structural cross-sectional view of the elastic clamping assembly;

[0025] Figure 7-Figure 8 Schematic diagrams of two types of clamping block structures.

[0026] In the figure: combustion chamber 1, flame spray gun 2, fixing part 3, lower column 301, upper column 302, wire to be tested 4, locking stud 5, wire groove 6, lead screw 7, threaded slider 8, clamping arm 9, clamping block 10, wire groove 11, curved arm 12, horizontal arm section 1201, vertical arm section 1202, mounting column 13, conductive ring 14, mounting tube 15, cylindrical long gear 16, locking nut 17, core column 18, guide slider 19, clamping spring 20, positioning ring 21, adjusting stud 22, contact piece 23, pressure sensor 24, rotating cover 25, flat gear ring 26. DETAILED DESCRIPTION

[0027] This specification will clearly and completely express the technical solutions in the following embodiments based on the drawings of the embodiments of the present invention. The implementation methods described in this specification are only some of the embodiments of the present invention, not all of them. All other embodiments derived from these embodiments in this application by persons of ordinary skill in the art without any creative effort should fall within the scope of protection of the present invention.

[0028] like Figure 1 The illustrated wire flame retardancy tester comprises a combustion chamber 1 for mounting wires. This chamber 1 is used to hold the wire 4 under test after installation and then conduct a combustion test. Furthermore, the combustion chamber 1 includes two fixing portions 3 for securing the ends of the wire, as well as a flame spray gun 2, which is a gas-fired spray gun capable of spraying a flame of a fixed size. Furthermore, in this embodiment, the wire is secured between the two fixing portions 3 in an obliquely stretched, straightened manner. The flame spray gun 2 is mounted to one side of the wire near its bottom end, with the flame spray direction perpendicular to the wire. This ensures that the wire 4 under test can be ignited or burned from a relatively fixed position during the combustion test, allowing for subsequent measurement of the remaining length of the wire after combustion to determine its flame retardancy.

[0029] When manufacturing, Figure 1-2 As shown, the combustion chamber 1 is a rectangular structure with an open top and front to facilitate observation of combustion and corresponding operations. The open top facilitates smoke exhaust, and the front can also be provided with a transparent flame retardant material. In more detail, the two fixing parts 3 in this embodiment are located at the two ends of the combustion chamber 1 in the diagonal direction, and the flame spray gun 2 is set near the bottom of the combustion chamber 1 and on the side of the wire at the lower diagonal position and perpendicular to the wire, so as to accurately determine the starting point of combustion, and the area where the flame actually crosses and overlaps with it is small. In practice, it is best to Figure 2 As shown, the wire 4 to be tested is installed at an angle, which is beneficial for burning upward along the wire during combustion to determine the duration of combustion.

[0030] like Figure 2 and Figure 3 The fixing part 3 includes a column and a locking stud 5. The column is arranged perpendicular to the inner rear wall of the combustion chamber 1, and a wire groove 6 is provided in the column, which is parallel to the line connecting the two fixing parts 3. This wire groove 6 allows the power line to pass through. At the same time, the locking stud 5 is arranged perpendicular to the wire groove 6 and is screwed into the wire groove 6 to press and fix the wires in the wire groove 6. After manually installing the straightened wire 4 to be tested with a predetermined length, the two ends of the wire are fixed.

[0031] In order to automatically install the wire to be tested 4, as Figure 2 and Figure 4A lead screw 7 can be mounted behind the uprights, allowing for rotation in situ. The lead screw 7 is driven by a motor (not shown). The lead screw 7 is arranged parallel to and opposite the wire channel 6. A threaded slider 8 is threadedly mounted on the lead screw 7. The threaded slider 8 is integrally fixed to a mounting post 13. This mounting post 13 is arranged parallel to the uprights and includes a wire channel 11 coaxial with the wire channel 6, also for allowing the wire to pass through. Furthermore, a resilient clamping assembly is fixed to the mounting post 13. The resilient clamping assembly is used to clamp the wires. The clamping force applied to the wires is elastic. Under sufficiently strong force, the resilient clamping assembly will slip relative to the wires, releasing the clamping force. Specifically, as the resilient clamping assembly moves along the lead screw 7, it initially straightens the wires. Once straightened, the resilient clamping assembly cannot continue to straighten the wires, causing the resilient clamping assembly to slide axially relative to the straightened wires. This critical process ensures that the wires 4 under test are fully stretched to the desired test length. In practice, the elastic clamping assembly is generally initially set against the fixing portion 3 below, and when the wire passes through its wire groove 6 and through the wire groove 11, it is inserted into the corresponding wire groove at will, without the need to specifically measure the length, and can be inserted at will. In the subsequent movement of the elastic clamping assembly toward the upper right, the wire is not only straightened, but also because of the straightening, the wire between the elastic clamping assembly and the fixing portion 3 below that fixes the end of the wire is always in a straightened state. Afterwards, no matter where the elastic clamping assembly moves to, the distance between it and the fixing portion 3 that fixes the end of the wire is equal to the length of the wire to be tested 4 in a straightened state. Therefore, there is no need to manually measure the length accurately and cut the wire. While fixing the wire to be tested 4, the length of the wire to be tested in its straightened state is automatically locked, that is, the accurate experimental length of the wire, which is very clever.

[0032] In the above embodiments, specifically, the elastic clamping component is as follows Figure 4-Figure 5 As shown, it mainly includes a pair of clamping arms 9 and clamping blocks 10 arranged in opposite directions. The clamping arms 9 and clamping blocks 10 on each side are fixedly connected, and the clamping arms 9 are Π-shaped. One end of the clamping arm 9 slides into the mounting arm along the radial direction of the mounting column 13, while the clamping block 10 is fixed to the other end. The opposite end faces of the clamping block 10 are provided with arc-shaped grooves. When the two arc-shaped grooves are close to each other, the power supply line between them is squeezed through, achieving a certain degree of clamping force on the wires, which is sufficient to straighten the wires. In addition, the two clamping arms 9 need to be elastically connected together by a clamping spring 20, and the clamping spring 20 makes the two arc-shaped grooves fit together and contact each other under normal conditions to form a cylindrical hole, which is coaxial with the wire groove 11.

[0033] As for the more specific structural design of the elastic connection, it can be as follows Figure 5-Figure 6As shown, a G-shaped curved arm 12 is also fixed to the clamping arm 9. The vertical arm section 1202 of this curved arm 12 is perpendicularly fixed to a section of the clamping arm 9 near the mounting post 13. The horizontal arm section 1201 of the curved arm 12 is slidably fitted into a mounting tube 15 and is installed axially aligned with the mounting tube 15. During installation, a guide slider 19 is fixed to the end of this horizontal arm section 1201. A clamping spring 20 is connected to one end of the guide slider 19 facing the horizontal arm section 1201, which is always in a compressed state. The clamping spring 20 is sleeved on the horizontal arm section 1201 to allow elastic movement and retraction, thus achieving an elastic connection.

[0034] Due to the different thickness of the wires, the clamping force of the elastic clamping assembly is different. In order to avoid excessive clamping force on the thick wires, or in other words, when some wires are matched with the elastic clamping assembly, the wires may be straightened but still cannot or are difficult to slide relative to the wires, which will cause scratches, wear, or even break the wires. Therefore, the elastic clamping force of the elastic clamping assembly must be adjusted. In order to solve this problem, in this embodiment, Figure 6 A retaining ring 21 is connected to the end of the clamping spring 20 facing away from the guide slider 19. This retaining ring 21 slides axially around the horizontal arm section 1201. An adjustment stud 22 is provided axially parallel to the end of the retaining ring 21 facing away from the clamping spring 20. One end of the adjustment stud 22 is rotationally connected to the end face of the retaining ring 21 and remains connected, for example, via a T-bolt. After the other end of the adjustment stud 22 extends beyond the end of the mounting tube 15, a cylindrical gear is coaxially secured thereto. This cylindrical gear is actually an extremely thick cylindrical gear, forming a special gear structure similar to a spline shaft. At the same time, the two opposing cylindrical long gears need to engage with a flat gear ring 26 located above them at the same time. The flat gear ring 26 is installed to rotate around the central vertical axis of the mounting tube 15. When the flat gear ring 26 is rotated, the two adjusting screws 22 will be screwed in or out synchronously, so that the two positioning rings 21 move synchronously, and then adjust the elastic force of the two clamping springs 20 when the clamping block 10 clamps the wire, so that it can meet the aforementioned requirements of not only straightening the wire, but also sliding relative to the wire without damaging the wire after straightening.

[0035] In order to drive the face gear ring 26, as Figure 6 The flat gear ring 26 is fixed on the bottom end surface of a rotating cover 25, and the rotating cover 25 is coaxially rotatably sleeved on the core column 18 fixed to the center of the mounting tube 15. The upper part of the core column 18 is provided with a thread, so that the rotating cover 25 is axially compressed and fixed by the locking nut 17 threaded on the core column 18, thereby achieving the stability of the elastic force after the elastic clamping assembly is adjusted.

[0036] As one of the recommended design structures, such as Figure 7A tubular contact piece 23 is embedded in the end face of at least one of the clamping blocks 10. This contact piece 23 is used to contact the wire, and a pressure sensor 24 is installed on the outer side of the contact piece 23 in direct contact with it to detect the force when squeezing the wire. The degree to which the wire is clamped can be intuitively judged to avoid being damaged by the clamping and to ensure that the wire cannot be straightened. The most critical function of the above structural design is: when the burning of the wire ends, the screw 7 is driven to reverse, allowing the elastic clamping assembly to move in a straight line with the remaining wire. During this period, because the wire is not burned, when the pressure value detected by the pressure sensor 24 is zero, that is, the insulation layer has been burned, and the wire core is smaller than the above-mentioned cylindrical hole, there is no obvious squeezing contact with the contact piece 23, and the pressure value may be zero, or drop to the set value. At this time, it can be determined that the burning has spread to the current position and stopped near the position, so the motor driving the screw 7 stops immediately, the detection ends, and / or the number of reverse revolutions at this time is recorded. The displacement of the clamping block 10 along the still intact wire is judged by the number of revolutions, that is, the length of the current remaining wire that has not been damaged by burning, thereby demonstrating the flame retardant performance of the wire.

[0037] In addition to the above structural design, you can also Figure 8 As shown, a conductive ring 14 is embedded in the end face of one side of the two clamping blocks 10 facing each other. When the two conductive rings 14 are in contact, a control circuit will be turned on. The control circuit controls the start and stop of the motor used to drive the screw 7. When the control circuit is turned on, the motor will immediately stop and / or record the number of reverse revolutions at this time. The reason why the two conductive rings 14 are in contact is that the remaining wire core after burning is smaller than the wire itself, especially some multi-functional cables, which have multiple layers of insulating protective layers on the outside. The thickness difference between the wire core and the outer rubber sheath is huge. Without the outer insulating layer, it cannot be squeezed into contact with the cylindrical hole, which then causes the cylindrical hole to recover and the conductive rings 14 on both sides to naturally contact and fit. In addition, during the test, some wire cores were relatively small and may have melted directly during the combustion experiment, which made it easier to trigger the working mechanism of the above two residual length automatic detection structures.

[0038] It should be explained here that, in this specification, terms such as first and second are only used to distinguish one feature from another, and do not mean that there is a certain relationship or order between these technical features. The terms "include" and "comprise" refer to the inclusion of one or certain technical means or features, specifically meaning that there are other existing or non-existing technical features that have not been included. The discussion in the above embodiments is only a referential example for the present invention, and is by no means the only restrictive constraint feature. Those skilled in the art should understand that, without departing from the technical content recorded in all claims of this application, some simple replacements and modifications can be made, thereby changing or becoming equivalent to other specific embodiments and application scenarios. However, no matter how the adaptive changes are made, these embodiments will inevitably fall within the scope of protection of the present invention.

Claims

1. A wire flame retardant testing machine, comprising a combustion chamber (1) for installing a wire, characterized in that: The combustion chamber (1) is provided with two fixing parts (3) for fixing the two ends of the electric wire, and a flame spray gun (2); the electric wire is fixed between the two fixing parts (3) in a diagonally stretched and straightened form; the flame spray gun (2) is installed on one side of the electric wire near the bottom end, and the flame spray direction is arranged perpendicularly to the electric wire; The combustion chamber (1) is a rectangular structure with an open top and front side. Two fixing parts (3) are located at both ends of the combustion chamber (1) in a diagonal direction. The flame spray gun (2) is arranged near the bottom of the combustion chamber (1) and on the side of the electric wire at the lower diagonal position. The two fixing parts (3) each include a column and a locking stud (5). The two columns are respectively a lower column (301) and an upper column (302). The two columns are arranged perpendicular to the inner rear wall of the combustion chamber (1). A wire threading groove (6) parallel to the line connecting the two fixing parts (3) is provided in the column. The locking stud (5) is arranged perpendicular to the wire threading groove (6) and is screwed into the wire threading groove (6) to press and fix the electric wire in the wire threading groove (6). A lead screw (7) is provided behind the upright posts and is installed to rotate in situ. The lead screw (7) is arranged parallel to the threading groove (6). A threaded slider (8) is threadedly sleeved on the lead screw (7). The threaded slider (8) is fixed to a mounting post (13) as a whole. The mounting post (13) is arranged parallel to the upright posts and has a wire groove (11) coaxial with the threading groove (6) provided therein. An elastic clamping component is also fixed on the mounting post (13). The elastic clamping component is used to clamp the wires, and the clamping force between the elastic clamping component and the wires is an elastic force. When the elastic clamping component moves along the lead screw (7), the wires can be straightened, and after being straightened, the elastic clamping component can slide axially relative to the straightened wires to a set position. The elastic clamping assembly includes a pair of clamping arms (9) and clamping blocks (10) arranged in opposite directions, and the clamping arms (9) and clamping blocks (10) on each side are fixedly connected. The clamping arm (9) is Π-shaped, and one end thereof slides into the mounting arm along the radial direction of the mounting column (13), and the clamping block (10) is fixed to the other end thereof. An arc groove is provided on the opposite end face of the clamping block (10), and when the two arc grooves are close to each other, the power supply line is squeezed through; the two clamping arms (9) are elastically connected together by a clamping spring (20), and the clamping spring (20) makes the two arc grooves fit together and contact each other to form a cylindrical hole under normal conditions, and the cylindrical hole is coaxial with the wire groove (11).

2. The wire flame retardant testing machine according to claim 1, characterized in that: A G-shaped curved arm (12) is also fixed on the clamping arm (9), and the vertical arm section (1202) of the curved arm (12) is vertically fixed to a section of the clamping arm (9) near the mounting column (13). The horizontal arm section (1201) of the curved arm (12) is slidably fitted into a mounting tube (15) and is installed in axial alignment with the mounting tube (15). A guide slider (19) is fixed to the end of the horizontal arm section (1201), and the guide slider (19) is connected to the clamping spring (20) which is always in an extruded state on one end face of the horizontal arm section (1201), and the clamping spring (20) is sleeved on the horizontal arm section (1201).

3. The wire flame retardant testing machine according to claim 2, characterized in that: The end of the clamping spring (20) away from the guide slider (19) is connected to a positioning ring (21), and the positioning ring (21) is axially slidably sleeved on the horizontal arm section (1201). The end of the positioning ring (21) away from the clamping spring (20) is provided with an adjusting stud (22) axially parallel to the clamping spring (20). One end of the adjusting stud (22) is rotationally connected to the end face of the positioning ring (21) and is not separated. The other end of the adjusting stud (22) extends out of the end of the mounting tube (15) and is coaxially fixed with a cylindrical long gear. The two opposite cylindrical long gears are simultaneously engaged with a flat gear ring (26) located above them. The flat gear ring (26) is rotationally installed around the central vertical axis of the mounting tube (15).

4. The wire flame retardant testing machine according to claim 3, characterized in that: The flat gear ring (26) is fixed on the bottom end surface of a rotating cover (25). The rotating cover (25) is coaxially rotatably sleeved on a core column (18) fixed to the center of the mounting tube (15). The upper section of the core column (18) is provided with a thread, so that the rotating cover (25) is axially compressed and fixed by a locking nut (17) threadedly sleeved on the core column (18).

5. The wire flame retardant testing machine according to claim 1, characterized in that: A tubular contact piece (23) is embedded in the end face of at least one of the clamping blocks (10), and the contact piece (23) is used to contact the electric wire. A pressure sensor (24) is installed on the outer side of the contact piece (23) in direct contact with the electric wire. When the burning of the electric wire ends, the lead screw (7) is driven to reverse, so that the elastic clamping assembly moves linearly while clamping the remaining electric wire. When the pressure value detected by the pressure sensor (24) is zero or drops to a set value, the motor driving the lead screw (7) immediately stops and / or records the number of reverse revolutions at this time.

6. The wire flame retardant testing machine according to claim 1, characterized in that: A conductive ring (14) is embedded in the end faces of the two clamping blocks (10) facing each other. When the two conductive rings (14) are in contact, a control circuit is turned on. The control circuit controls the start and stop of the motor for driving the lead screw (7). When the control circuit is turned on, the motor stops immediately and / or the number of reverse rotations at that time is recorded.

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