A multifunctional clamp for wire and cable specimen vertical burning tester

Abstract

The utility model relates to wire and cable sample detection technical field, concretely to a kind of multifunctional fixture for wire and cable sample vertical combustion testing machine, including being positioned clamp in top in the upper portion of vertical combustion testing machine combustion test box and being positioned clamp in bottom in the bottom of combustion test box, top positioning clamp includes support plate being positioned on the sidewall of the box door of combustion test box, clamping plate being respectively horizontally slidably arranged on two support plates and drive mechanism being arranged on one of support plate and being transmission connection with two support plates;The utility model's bottom limiting clamp adopts spring-driven multidirectional self-adapting clamping structure, when cable lower end is clamped, bottom component need not manual adjustment, operator need not close high-temperature area in the bottom of combustion test box, realize insertion and clamping, need not contact bottom limiting disc, spline rod and other components that easily residual heat in whole process, completely avoid high-temperature scald risk from operation process, guarantee test personnel safety.

Description

Technical Field

[0001] This utility model relates to the field of wire and cable sample testing technology, specifically a multifunctional fixture for a vertical combustion test machine for wire and cable samples. Background Technology

[0002] In the field of quality inspection of wire and cable samples, vertical burning test is the core means of evaluating their flame retardant performance. As a key component for fixing cable samples in vertical burning test machine, the safety of operation, ease of clamping, and degree of integration of testing directly determine the test efficiency, result accuracy, and personnel safety.

[0003] In the prior art, there are relevant improvement schemes for the cable positioning structure of vertical combustion testing machines. For example, Chinese Patent No. CN216669876 discloses a cable positioner for a vertical combustion testing machine. This positioner uses the transmission cooperation of a positioning frame, a first bevel gear, a second bevel gear and a first threaded rod to drive the positioning plates to move closer together to clamp the cable. At the same time, the sliding seat, support plate and spring snap-fit ​​structure are used to adjust the position of the ignition mechanism, which improves the stability of cable positioning and the adjustment flexibility of the ignition mechanism to a certain extent, and provides a basic guarantee for the vertical combustion test of cables.

[0004] However, in actual testing scenarios and with diverse sample testing requirements, the positioner disclosed in the above patent still has some shortcomings: 1. Insufficient operational safety, easily leading to burn risk. When positioning the lower end of the cable, the cable positioner requires personnel to operate the relevant components at close range. During continuous testing, the positioning components and surrounding areas at the bottom of the test chamber retain some heat from the previous combustion. If workers are negligent or approach the high-temperature components when inserting a new sample before it has completely cooled down, burn accidents are likely to occur, threatening operational safety.

[0005] 2. Poor clamping convenience and adaptability. The cable locator requires multiple mechanical adjustments to clamp the cable: first, the first turntable is rotated to drive the bevel gear and threaded rod to initially clamp the positioning plate; then, the second turntable is rotated to adjust the fixing plate for secondary reinforcement. The operation is cumbersome, which not only prolongs the clamping time but may also affect the positioning stability and reduce the test efficiency due to adjustment errors.

[0006] 3. Lack of integrated measurement function limits detection accuracy and efficiency. The structure of this cable locator focuses only on cable positioning and ignition mechanism adjustment, without integrating measurement components for key indicators after the test. Core detection data such as the char length and burning range of the cable after combustion need to be measured separately after the test by removing the sample and using external tools such as rulers. This not only increases the extra steps of sampling and measurement, but also makes the measurement results inaccurate due to sample movement and positioning errors of external tools, thus affecting the detection accuracy. Utility Model Content

[0007] The purpose of this invention is to provide a multifunctional fixture for a vertical combustion test machine for wire and cable samples, in order to solve the problems mentioned in the prior art in the background section.

[0008] To achieve the above objectives, this utility model provides the following technical solution: a multifunctional clamp for a vertical combustion test machine for wire and cable samples, comprising a top positioning clamp located on the upper part of the combustion test chamber of the vertical combustion test machine and a bottom limiting clamp located at the bottom of the combustion test chamber. The top positioning clamp includes a support plate located inside the combustion test chamber and on the side walls of the chamber door, a clamping plate horizontally slidably mounted on the two support plates, and a drive mechanism mounted on one of the support plates and pulsatorically connected to the two clamping plates. The bottom limiting clamp includes a limiting plate detachably mounted on the middle of the bottom side of the combustion test chamber and a plurality of splined rods horizontally slidably connected to the circumference of the limiting plate. A clamping block is provided at one end of each splined rod, and a spring is sleeved on the splined rod connecting the limiting plate and the clamping block.

[0009] Furthermore, the driving mechanism includes a bidirectional screw mounted on one side of the clamping plate and rotatably connected to the two support plates; a driving shaft rotatably connected to one of the support plates along its length; a strip-shaped threaded seat is integrally formed on one side of each of the two clamping plates, and the two threaded seats are respectively threaded to both ends of the bidirectional screw; a helical gear is provided on one end of the driving shaft and one end of the bidirectional screw, and the two helical gears mesh with each other.

[0010] Furthermore, a rotating seat is provided on the other end of the drive shaft, and a fastening bolt for use with the drive shaft is threadedly connected to one end of the support plate near the rotating seat.

[0011] Furthermore, each of the spline rods has a limiting block at its other end.

[0012] Furthermore, it also includes a measuring ruler, and a support block is provided at the bottom of one side wall of the combustion test chamber. The measuring ruler is horizontally slidably connected between another support plate and the support block.

[0013] Furthermore, a measuring claw is vertically slidably connected to the measuring ruler.

[0014] This utility model addresses the core problems of existing vertical combustion test fixtures for wire and cable samples, such as insufficient operational safety, poor clamping convenience, narrow adaptability, and low degree of integrated testing, through structural innovations in the top positioning fixture, bottom limiting fixture, and integrated measuring component. Specific beneficial effects are as follows: 1. The bottom limiting clamp of this utility model adopts a spring-driven multi-directional adaptive clamping structure. When clamping the lower end of the cable, it is only necessary to insert it along the slope of the upper surface of the clamping block. There is no need to manually adjust the bottom components, and the operator does not need to approach the high-temperature area at the bottom of the combustion test chamber. The spring automatically pushes 3-4 clamping blocks toward the cable through its elastic force, achieving clamping upon insertion. Throughout the process, there is no need to contact the bottom limiting plate, spline rod, or other components that are prone to residual heat. This completely avoids the risk of high-temperature burns from the operation process and ensures the safety of the test personnel.

[0015] 2. This utility model achieves a dual improvement in clamping efficiency and adaptability through a combination of simplified top transmission and adaptive bottom design. Simply rotating the rotating base drives the bidirectional screw via helical gear transmission. The left / right-hand threads of the bidirectional screw synchronously drive the two clamping plates to slide in opposite directions, achieving rapid clamping or loosening of the upper end of the cable. After clamping, the drive shaft is locked by fastening bolts to prevent loosening during testing. Compared to the multi-step adjustment of existing technologies, this shortens clamping time. When the cable diameter is small, the spring of the bottom limiting clamp naturally extends to push the clamping block to clamp; when the diameter is large, the clamping block is pushed open, compressing the spring and maintaining stable clamping through greater elasticity. No clamping or adjusting components need to be replaced, making it suitable for various common cable samples.

[0016] 3. This utility model features a built-in adjustable measuring component, enabling integrated testing and measurement operations. The measuring scale slides horizontally via upper and lower guide grooves, while the measuring jaws slide vertically along the measuring scale. After the test, there is no need to remove the cable; simply slide the measuring scale near the cable and adjust the measuring jaws to align with the carbonization start and end points to obtain key data such as carbonization length. The measuring jaws can be fixed in position using set screws, and the measuring scale can also be locked using set screws to prevent component slippage during measurement. Compared to external tools, this eliminates errors such as sample movement and inaccurate tool positioning, improving detection accuracy. Simultaneously, it reduces additional sampling and measurement steps, increasing detection efficiency. Attached Figure Description

[0017] Figure 1 This is a structural diagram of the present invention; Figure 2 This is an internal perspective view of the present invention; Figure 3 This is a diagram of the internal structure of this utility model; Figure 4 This is a bottom view of the internal structure of this utility model.

[0018] In the diagram: 1. Combustion test chamber; 2. Chamber door; 3. Support plate; 4. Clamping plate; 5. Limiting plate; 6. Spline rod; 7. Clamping block; 8. Spring; 9. Double-acting screw; 10. Drive shaft; 11. Threaded seat; 12. Helical gear; 13. Rotating seat; 14. Fastening bolt; 15. Limiting block; 16. Measuring ruler; 17. Support block; 18. Measuring claw. Detailed Implementation

[0019] This utility model discloses a multi-functional clamp for a vertical combustion test machine for wire and cable specimens, aiming to solve the problems of poor clamping stability, low adaptability, lack of integrated measurement function, and easy accidental burns to test personnel due to accidental contact with the bottom heating element during continuous testing in existing vertical combustion tests of wire and cable specimens. The following is in conjunction with the appendix... Figure 1-4 The specific embodiments of this utility model will be described in detail below.

[0020] This multi-functional fixture is assembled inside the combustion test chamber 1 of the vertical combustion testing machine. It consists of three parts: a top positioning fixture (for fixing the upper end of the wire / cable sample), a bottom limiting fixture (for positioning the lower end of the wire / cable sample), and an integrated measuring component (for post-test dimensional inspection). Each part is fixed to the inner wall of the combustion test chamber 1 using bolts, welding, or other methods to ensure structural stability during the test. The combustion test chamber 1 has an openable door 2 on the front, facilitating the loading and unloading of the wire / cable sample and allowing observation of the combustion process through a transparent observation window (not shown in the attached diagram, standard testing machine configuration). The inner wall of the chamber is made of high-temperature resistant stainless steel to prevent damage to the fixture's mounting base from high temperatures. Detailed structure and assembly of each part are as follows: The top positioning clamp is used to achieve precise clamping and adjustment of the upper end of the cable. It consists of a support plate 3, a clamping plate 4 and a drive mechanism. Its core function is to drive the two clamping plates 4 to slide in opposite directions through the drive mechanism, adapt to wire and cable samples of different diameters and achieve stable clamping.

[0021] Two support plates 3 are provided, serving as the sliding support base for the top positioning clamp. The two support plates 3 are symmetrically fixed to the side walls on both sides of the chamber door 2 inside the combustion test chamber 1 by bolts, and are arranged horizontally and parallelly. Their height is determined according to actual usage requirements. The support plates 3 are made of 304 stainless steel with a thickness of 8-12mm. The surface is provided with T-shaped sliding grooves (not shown in the attached diagram) that cooperate with the clamping plate 4, ensuring that the clamping plate 4 can slide smoothly horizontally along the sliding grooves without any jamming.

[0022] There are two clamping plates 4, which are components that directly clamp the upper end of the cable. They are respectively embedded in the sliding grooves of the two support plates 3 and can move horizontally along the sliding grooves. The side of the clamping plate 4 near the cable has an arc-shaped groove (not shown in the attached figure). The inner wall of the groove is pasted with a high-temperature resistant silicone pad (2-3mm thick) to increase the friction with the cable, prevent damage to the cable sheath during clamping, and improve clamping stability. In addition, one side of each clamping plate 4 (the side wall near the inner cavity of the combustion test chamber 1) is integrally formed with a strip-shaped threaded seat 11. The axis of the threaded seat 11 is perpendicular to the sliding direction of the clamping plate 4, and the threaded seat 11 has an internal thread for cooperating with the drive mechanism 9.

[0023] The drive mechanism, used for power transmission and clamping control, is mounted on one of the support plates 3 and drives the two clamping plates 4 to move synchronously in opposite directions. It includes a bidirectional screw 9, a drive shaft 10, a helical gear 12, a rotating seat 13, and fastening bolts 14. The bidirectional screw 9 is rotatably connected between the bearing seats on the two support plates 3 (near the side wall of the inner cavity of the combustion test chamber 1) via a deep groove ball bearing (model 6204), and its axis is perpendicular to the length direction of the support plate 3. The left section of the bidirectional screw 9 has a left-hand thread, and the right section has a right-hand thread. The pitch of both threads is 2-3 mm, and they respectively mate with the internal threads of the threaded seats 11 of the two clamping plates 4. When the bidirectional screw 9 rotates clockwise, the two threaded seats 11 drive the two clamping plates 4 to slide in opposite directions (clamping the cable); when it rotates counterclockwise, the clamping plates 4 slide in the opposite direction (releasing the cable). The drive shaft 10 is rotatably connected to one of the support plates (3) via a bearing housing. One end of the drive shaft 10 is close to the double-acting screw 9, and the other end is close to the door 2. The axis of the drive shaft 10 is perpendicular to the axis of the double-acting screw 9. A helical gear 12 is fixedly mounted on one end of the drive shaft 10 (the end close to the double-acting screw 9), and a helical gear 12 is also mounted on the end of the double-acting screw 9. The two helical gears 12 mesh with each other (transmission ratio 1:1.2), realizing the power transmission of drive shaft 10 rotation → helical gear 12 meshing transmission → double-acting screw 9 rotation. The rotating seat 13 is fixedly installed on the other end of the drive shaft 10 (on the side close to the door 2, for easy operation by the test personnel). The rotating seat 13 has a hexagonal structure (or a circular structure with anti-slip texture), which is easy for the operator to rotate by wrench or hand to realize the rotation adjustment of the drive shaft 10. The fastening bolt 14 is connected to the end of the bearing housing on which the drive shaft 10 is installed (on the side close to the rotating seat 13) through a threaded hole. Its axis is perpendicular to and intersects the axis of the drive shaft 10. After the clamping plate 4 clamps the cable, tighten the fastening bolt 14 clockwise so that its end is in close contact with the outer wall of the drive shaft 10. Use friction to lock the drive shaft 10, prevent the drive shaft 10 from rotating unexpectedly during the test and causing the clamping plate to loosen, and ensure the stability of the test.

[0024] The bottom limiting clamp is used to achieve multi-directional adaptive clamping of the lower end of the cable without requiring close-range operation by the experimenter, effectively reducing the risk of accidental burns during continuous experiments. The bottom limiting clamp is installed in the middle of the bottom wall of the combustion test chamber 1 and consists of a limiting plate 5, a spline rod 6, a clamping block 7, a spring 8, and a limiting block 15. The elastic force of the spring 8 enables the multi-directional adaptive clamping of the lower end of the cable by the clamping block 7, adapting to cables of different diameters while avoiding excessive clamping force that could damage the cable.

[0025] The limiting plate 5 serves as the mounting and guiding base. The limiting plate 5 is a circular structure (10-15mm thick) and is detachably and replaceably fixed to the center of the bottom inner wall of the combustion test chamber 1 using bolts. It is made of 304 stainless steel. The limiting plate 5 has 3-4 splined holes evenly spaced along its circumference. The axis of these splined holes is arranged radially along the limiting plate 5, used to cooperate with the splined rod 6 to achieve horizontal sliding guidance.

[0026] The spline rod 6 and clamping block 7 are the clamping actuators. The number of spline rods 6 is consistent with the number of spline holes on the limiting plate 5 (3-4). One end of the spline rod (the end closer to the center of the limiting plate 5) is fixedly connected to the clamping block 7 by bolts, and the other end (the end away from the center) is fixedly connected to the limiting block 15. The spline rod 6 and the spline hole on the limiting plate 5 are clearance fit (fit clearance 0.1-0.2mm) to ensure that the spline rod 6 can slide horizontally along the spline hole without radial movement. The end of the clamping block 7 has an arc-shaped structure (adapted to the shape of the cable) and its upper surface has a downward slope. The inner wall is also attached with a high-temperature resistant silicone pad. Its curvature is determined according to the common cable diameter to ensure the fit with cables of different diameters. The spline rod 6 is made of 45# steel with heat treatment (hardness HRC28-32) to ensure sufficient rigidity and wear resistance.

[0027] Spring 8 and limiting block 15 provide elastic force and safety limit for the bottom limiting clamp. Spring 8 is sleeved on spline rod 6, and its two ends abut against the inner wall (near the center) of limiting plate 5 and the outer wall (away from the center) of clamping block 7, respectively (whether spring 8 needs to be fixed between the inner wall of limiting plate 5 and the outer wall of clamping block 7 depends on actual usage requirements). Spring 8 is a high-temperature resistant compression spring (material is Inconel alloy, working temperature ≤600℃). In its natural state, it is in a stretched state. Through elastic force, it pushes clamping block 7 towards the center of limiting plate 5 to achieve self-adaptive clamping of the cable. When the cable diameter is large, clamping block 7 is pushed open, spring 8 is compressed, generating a larger clamping force to ensure stable clamping. The limiting block 15 is a circular structure (the diameter is 2-3mm larger than the spline hole diameter). It is fixed to the end of the spline rod 6 (away from the clamping block 7) by welding. Its function is to limit the sliding range of the spline rod 6, prevent the spline rod 6 from completely coming out of the spline hole of the limiting plate 5, and ensure the structural integrity of the bottom limiting clamp.

[0028] Common wire and cable specimen diameters are typically 5-80 mm, therefore, multiple sets of the aforementioned bottom limiting clamps can be configured according to actual usage requirements. For example, three sets of limiting discs 5 with diameters of 5-35 mm, 35-60 mm, and 60-90 mm can be configured, with other components potentially adjusted accordingly. During testing, a bottom limiting clamp of appropriate size should be selected based on the diameter of the different wire and cable specimens to ensure effective clamping of the bottom of the specimen.

[0029] To avoid errors caused by individually handling and placing measuring tools after testing, this invention uses an integrated measuring component to achieve accurate dimensional detection during the testing process. It includes a measuring ruler 16, a support block 17, and measuring claws 18, used for real-time measurement of key indicators such as the charred length and burning range of the cable after combustion.

[0030] Support block 17 and measuring ruler 16 are the basic measuring components. Support block 17 is fixed to the bottom of one side wall of combustion test chamber 1 (located on the side of chamber door 2) by bolts. It is made of stainless steel and has a horizontal T-shaped guide groove on its top that mates with measuring ruler 16. Measuring ruler 16 is a metal ruler (300-500mm in length, 1mm accuracy). One side of the ruler has a scale (the 0 mark is flush with the lower edge of the top positioning clamp). The upper and lower ends of the ruler are respectively embedded in the T-shaped guide groove on the bottom of another support plate 3 (the support plate 3 is located on the side closer to the measuring component) and the T-shaped guide groove on the support block 17 (the bottoms of both support block 17 and measuring ruler 16 are below the combustion start position), and can slide horizontally along the guide groove. The body of measuring ruler 16 is made of stainless steel and chrome-plated to prevent high-temperature oxidation and scale wear. Support plate 3 or support block 17 also has set screws to fix the position of measuring ruler 16 and prevent it from sliding during the experiment.

[0031] The measuring claw 18 is used to locate the measurement point. The measuring claw 18 has a right-angled trapezoidal structure (made of stainless steel). A vertical groove is provided at the end near the measuring scale 16, allowing it to slide vertically up and down along the scale. The end of the measuring claw 18 away from the measuring scale 16 (facing the cable) is wedge-shaped with a smooth finish, used to conform to the cable surface and locate the measurement start point (e.g., the start of combustion) and end point (e.g., the end of carbonization). Furthermore, a set screw (not shown in the attached diagram) is provided within the vertical groove of the measuring claw 18. Once the measuring claw 18 has moved to the target position, tightening the set screw secures the measuring claw 18, preventing slippage and measurement errors.

[0032] This utility model's multifunctional fixture, through the synergistic action of a top positioning fixture, a bottom limiting fixture, and an integrated measuring component, achieves stable clamping and accurate testing of wire and cable samples for vertical combustion tests. The specific steps are as follows: 1. The operator first loosens the fastening bolt 14 of the top positioning clamp counterclockwise to release its lock on the drive shaft 10. Then, by wrench or hand-tightening the rotating seat 13 (hexagonal or non-slip circular structure), the drive shaft 10 is rotated; the helical gear 12 at one end of the drive shaft 10 meshes with the helical gear 12 at the end of the bidirectional screw 9 (transmission ratio 1:1.2), causing the bidirectional screw 9 to rotate counterclockwise. Since the left section of the bidirectional screw 9 has a left-hand thread and the right section has a right-hand thread, and they respectively cooperate with the threaded seats 11 of the two clamping plates 4, the two threaded seats 11 will drive the clamping plates 4 to slide in the opposite direction along the T-shaped sliding groove of the support plate 3 until the distance between the two clamping plates 4 is greater than the diameter of the cable to be tested, leaving space for clamping the upper end of the wire and cable sample.

[0033] 2. Slide the measuring scale 16 along the T-shaped guide groove of the support plate 3 and the support block 17 to the initial position (such as near the side wall of the combustion test chamber 1), and tighten the set screw of the measuring claw 18 to fix it in a certain position of the measuring scale 16. Finally, fix the position of the measuring scale 16 by the set screw to avoid displacement of the measuring components during the test.

[0034] 3. After processing according to the relevant standard GB / T 18380.12, the length of the wire and cable sample is (600±25) mm. The operator inserts the lower end of the wire and cable sample to be tested between multiple clamping blocks 7 of the bottom limiting fixture that are adapted to its diameter (the upper surface of the clamping block 7 has a ramp to facilitate the insertion of the lower end of the wire and cable sample). The spring 8 is compressed, and under the action of elastic force, it pushes the clamping blocks 7 toward the cable. The arc-shaped silicone pads of 3-4 clamping blocks 7 are in close contact with the outer wall of the cable, realizing multi-directional adaptive clamping of the lower end of the cable. At the same time, the limiting block 15 at the end of the spline rod 6 can prevent the spline rod 6 from coming out of the spline hole of the limiting plate 5, ensuring the stability of the bottom fixture structure.

[0035] 4. Adjust the verticality of the wire and cable sample to ensure the cable is suspended vertically. Then, rotate the rotating seat 13 of the top positioning fixture in the opposite direction, causing the drive shaft 10, helical gear 12, and double-acting screw 9 to rotate clockwise. The double-acting screw 9 drives the two clamping plates 4 to slide towards each other along the support plate 3 through threaded transmission until the arc-shaped silicone pads of the clamping plates 4 are in close contact with the upper outer wall of the cable. At this point, stop rotating the rotating seat 13 and tighten the fastening bolt 14 clockwise so that its end is in close contact with the outer wall of the drive shaft 10. The frictional force locks the drive shaft 10, preventing the clamping plates 4 from loosening due to accidental rotation of the double-acting screw 9 during the test, thus completing the rigid fixation of the upper end of the cable.

[0036] 5. Observe the cable condition to ensure that the cable is not tilted or loose. If tilting is present, fine-tune the rotating seat 13 or clamp 7 until the cable is vertical. Start the vertical combustion test machine for wire and cable samples and conduct the combustion test according to the preset test parameters (such as gas and air flow rate and combustion time). During the test, the operator can observe the combustion status of the cable in real time through the observation window. The top positioning clamp and the bottom limiting clamp keep the cable fixed to prevent the cable from shifting due to combustion deformation or external force.

[0037] 6. When the test reaches the preset stage (e.g., after combustion stops and complete cooling), if measurement is required, the operator can loosen the set screw of the measuring scale 16, allowing it to slide close to the wire and cable sample (measuring claw 18 should be in contact with or near it). Then, loosen the set screw of the measuring claw 18 and slide the measuring claw 18 along the vertical groove of the measuring scale 16 until the wedge-shaped end of the measuring claw 18 is in contact with the starting position of the cable combustion (e.g., the boundary between the unburned area and the carbonized area). Record the distance between the lower edge of the top positioning clamp and the lower starting point of the carbonized part at this time. Subsequently, slide the measuring claw 18 until it is in contact with the combustion termination position, and record the distance between the lower edge of the top positioning clamp and the upper starting point of the carbonized part at this time. If measurement is required during continuous experiments, a pull rod near the door 2 can be threaded or welded to the set screw on one side of the measuring claw 18. This can be used to remotely loosen or fix the measuring claw 18, and can also assist in moving the measuring claw 18 to prevent burns from residual high temperature.

[0038] 7. After the combustion test is completed, wait for the temperature inside the combustion test chamber 1 to drop to a safe range, then open the chamber door 2. First, loosen the fastening bolts 14 of the top positioning clamp counterclockwise, then rotate the rotating seat 13 to make the clamping plate 4 slide in the opposite direction to release the upper end of the cable; then remove the cable from the bottom limiting clamp to complete the recovery of the wire and cable sample. Clean the residual impurities (such as carbonized debris) on the clamping plate 4 and clamping block 7, and check whether the silicone pad is intact. If damaged, replace it in time. Reset the clamping plate 4 of the top positioning clamp, the clamping block 7 of the bottom limiting clamp, and the measuring components to their initial state, close the chamber door 2, and wait for the next test.

Claims

1. A multifunctional clamp for a vertical combustion test machine for wire and cable samples, comprising a top positioning clamp located on the upper part of the combustion test chamber (1) of the vertical combustion test machine and a bottom limiting clamp located at the bottom of the combustion test chamber (1), characterized in that, The top positioning fixture includes a support plate (3) located inside the combustion test chamber (1) and on the side walls of the chamber door (2), a clamping plate (4) that is horizontally slidably mounted on the two support plates (3), and a drive mechanism that is mounted on one of the support plates (3) and is connected to the two clamping plates (4) in a transmission manner; the bottom limiting fixture includes a limiting plate (5) that is detachably mounted in the middle of the bottom side of the combustion test chamber (1) and a plurality of spline rods (6) that are horizontally slidably connected to the circumference of the limiting plate (5); a clamping block (7) is provided on one end of the spline rod (6), and a spring (8) is sleeved on the spline rod (6) and connected between the limiting plate (5) and the clamping block (7).

2. The multifunctional clamp as described in claim 1, characterized in that, The driving mechanism includes a bidirectional screw (9) rotatably connected to two support plates (3) and located on one side of the clamping plate (4) and a driving shaft (10) rotatably connected to one of the support plates (3) along its length; each of the two clamping plates (4) has an integrally formed strip-shaped threaded seat (11), and the two threaded seats (11) are threadedly engaged with both ends of the bidirectional screw (9); both the driving shaft (10) and the bidirectional screw (9) are provided with helical gears (12), and the two helical gears (12) mesh with each other.

3. The multifunctional clamp as described in claim 2, characterized in that, The other end of the drive shaft (10) is provided with a rotating seat (13), and one of the support plates (3) is threaded with a fastening bolt (14) that works with the drive shaft (10) at one end near the rotating seat (13).

4. The multifunctional clamp as described in claim 1, characterized in that, Each of the spline rods (6) has a limiting block (15) on its other end.

5. The multifunctional clamp as described in claim 1, characterized in that, It also includes a measuring ruler (16), and a support block (17) is provided at the bottom of one side wall of the combustion test chamber (1). The measuring ruler (16) is horizontally slidably connected between another support plate (3) and the support block (17).

6. The multifunctional clamp as described in claim 5, characterized in that, The measuring ruler (16) is vertically slidably connected to a measuring claw (18).

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