Thermal expansion stone cracking medicine tube and application

Abstract

The invention discloses a thermal expansion stone cracking powder tube which comprises an outer tube body, a thermal expansion agent and a core ignition tube, the thermal expansion agent and the core ignition tube are located in the outer tube body, and the outer tube body ignites the internal thermal expansion agent through a set of ignition wires for rapid heating; the thermal expansion agent is composed of carbon black, coal gangue powder, straw powder, sodium nitrite, potassium perchlorate and a starch adhesive, and is used for rapid expansion after being heated. The thermal expansion agent is rapidly gasified and expanded under the condition of sudden rapid heating, good rock breaking destructive power is achieved, dangerous situations such as production, storage and transportation explosion do not exist, the situation of fire combustion explosion does not exist, safety and convenience are achieved, in addition, vibration generated by thermal expansion stone cracking is weak, noise is very small, noise pollution is basically avoided, and the thermal expansion stone cracking device is suitable for large-scale popularization and application. Meanwhile, the vibration of cracked stones is small, a large amount of dust cannot be generated, the damage range is within a specified range, and the influence on the surrounding environment is small for a working site which is greatly restricted by site factors.

Description

Technical Field

[0001] The invention relates to the technical field of engineering excavation construction, and in particular to a thermal expansion rock cracking cartridge used for non-blasting excavation construction and its application. Background Art

[0002] In mountain highway reconstruction and expansion projects, rock slope excavation construction faces challenges such as complex terrain, changeable geological conditions, steep slopes and limited construction space. During some on-site construction processes, since some of the geology is parent rock (Yanshanian granite), its compressive strength is above 100Mpa. Therefore, explosive blasting technology cannot be used in such highway reconstruction and expansion projects. Traditional hydraulic splitting drilling, expansion agent blasting and other technologies are extremely ineffective. Only about 100 cubic meters of rock are excavated every day, which is far from meeting the overall progress requirements on site.

[0003] To this end, the present application proposes a thermal expansion rock cracking cartridge for non-blasting excavation construction to solve the above technical problems. Summary of the Invention

[0004] The main purpose of the present invention is to provide a thermal expansion rock cracking charge tube for non-blasting earth and rock excavation construction to solve the above technical problems.

[0005] The present invention adopts the following technical solutions to solve the above technical problems:

[0006] A thermal expansion stone cracking cartridge comprises an outer tube body, a thermal expansion agent located inside the outer tube body, and a core ignition tube, wherein:

[0007] The outer tube body is quickly heated by igniting the internal thermal expansion agent through a set of ignition wires;

[0008] The thermal expansion agent consists of carbon black, coal gangue powder, straw powder, sodium nitrite, potassium perchlorate and starch adhesive, and is used for rapid expansion after being heated.

[0009] Preferably, the thermal expansion agent is prepared in a proportion comprising 30% carbon black, 13% coal gangue powder, 15% straw powder, 25% potassium perchlorate, 15% sodium nitrite, and 2% starch adhesive.

[0010] Preferably, the thermal expansion agent raw materials are processed by screening, mixing, granulating, drying, and cooling to be packaged to produce the thermal expansion agent.

[0011] Preferably, the method for producing the thermal expansion crack comprises:

[0012] S1. Raw material screening and activation: Conductive carbon black of a specified particle size was selected and dried to remove adsorbed water. Corn straw was enzymatically treated and then crushed to 80 mesh to obtain straw powder. Coal gangue powder was crushed to 100 mesh, acid-washed to remove carbonate impurities, and dried before being premixed with straw powder at a mass ratio of 2:1.

[0013] S2. Oxidant Treatment: Sodium nitrite was sieved through a 60-mesh sieve before use and pre-dry-mixed with carbon black to reduce hygroscopicity. Potassium perchlorate was ball-milled to a D90 of ≤20 μm and pre-mixed with sodium nitrite in a 5:3 mass ratio.

[0014] S3. After the raw materials are systematically proportioned and fed using a loss-in-weight feeder, they are dry-mixed using a double-cone vacuum mixer. First, mix the carbon black and sodium nitrite for 10 minutes, then add the coal gangue / straw composite powder and mix for 15 minutes, and finally slowly add potassium perchlorate and mix for 20 minutes. When the mixing uniformity CV value is ≤3%, stop dry mixing, and then wet-mix the adhesive in the form of a spray. The starch adhesive is configured as an 8% aqueous solution. Mixing is stopped after the moisture content of the material is ≤0.5%, completing the preparation of the thermal expansion agent.

[0015] Preferably, the outer tube body is composed of a group of tube bodies with one end sealed and the other end connected to the cover plate by a thread. A through hole is opened on the cover plate for placing the ignition tube inside the outer tube body and then discharging the fuse from the outer tube body.

[0016] Preferably, the drug tube production process includes: processing and manufacturing the outer body tube, sealing one end of the outer body tube, pouring thermal expansion agent into the tube to 1 / 4 height, placing the core ignition tube and reserving the ignition wire to the tube mouth, continuing to pour thermal expansion agent into the tube until it is full, and finally sealing the top of the thermal expansion tube.

[0017] Preferably, the outer tube body is composed of a group of outer tubes and a group of inner tubes, and the open end of the inner tube is provided with an external thread for rotationally fixing after plugging and combining with the outer tube body. A through hole is provided at the closed end of the outer tube body for discharging the lead from the outer tube body after the ignition tube is placed inside the outer tube body. The through hole is used to continue to inject thermal expansion agent into the internal space of the outer tube body after the outer tube and the inner tube are combined and fixed.

[0018] Preferably, the medicine tube production process includes: processing and manufacturing the outer tube and the inner tube, first depositing the tube at a specified height in the outer tube, connecting the ignition tube lead to the outer inner tube through the through hole, and placing an appropriate amount of thermal expansion agent in the inner tube until it is flush with the bottom of the ignition tube, and then plugging the inner and outer tubes together and rotating the threads to fix the combination, placing the bottom of the ignition tube on the thermal expansion agent, adjusting the position of the ignition tube through the lead so that it is located in the center of the outer tube body, and finally continuing to deposit thermal expansion agent through the through hole until the space inside the tube is completely filled.

[0019] Preferably, an application of a heat-expandable stone-splitting medicine tube is used to place the heat-expandable stone-splitting medicine tube in a preset hole to quickly heat and vaporize and expand.

[0020] Preferably, the thermal expansion stone cracking medicine tube is placed at the bottom of a preset hole, and the preset hole is densely filled with sand and gravel. An ignition wire is led out of the preset hole and then sealed, and the ignition wire is used to control the thermal expansion agent to heat quickly.

[0021] The present invention provides a thermal expansion stone cracking medicine tube. Compared with the prior art, the present invention has the following advantages:

[0022] 1. The thermal expansion rock cracking cartridge of the present invention utilizes the thermal expansion agent to rapidly vaporize and expand under the condition of sudden and rapid heating, and has good rock-breaking destructive power. It can cause the effect of expansion-induced cracking and rock-breaking through proper control. There are no dangerous situations such as explosions in production, storage, and transportation, and there will be no fire, combustion, or explosion. It is safe and convenient.

[0023] 2. The vibration generated by the thermal expansion stone cracking of the present invention is weak, the noise is very small, and there is basically no noise pollution. At the same time, the stone cracking vibration is very small and will not produce a large amount of dust. The damage range is within the specified range. For work sites that are greatly restricted by site factors, the impact on the surrounding environment is relatively small.

[0024] 3. The present invention does not generate new harmful gases during thermal expansion, and is green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0026] Figure 1 This is a schematic diagram of the internal structure of the medicine tube of the present invention;

[0027] Figure 2 This is a schematic diagram of the application structure of the medicine tube of the present invention;

[0028] Figure 3 This is a schematic diagram of the outer tube structure in one of the specific embodiments of the present invention;

[0029] Figure 4 Schematic diagram of filling a medicine tube with one of the outer tube structures in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. In the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] In the embodiment, see Figure 1 and Figure 4 .

[0032] In one specific example, on-site sampling revealed that the compressive strength of the parent rock (Yanshanian granite) was consistently above 100 MPa. However, due to the proximity to an operational highway, explosive blasting was not feasible. Traditional hydraulic splitting drilling and expansion agent blasting were also extremely ineffective, resulting in only about 100 cubic meters of rock excavated daily, far from meeting the overall site progress requirements.

[0033] Therefore, the present invention has compared the processes of mechanical breaking excavation, hydraulic splitting excavation, and expansion agent excavation, and combined with multiple considerations such as safety, progress, and cost, and the use of the "thermal expansion stone cracking" process for excavation of stone slopes in mountainous highway reconstruction and expansion has great advantages.

[0034] Specifically, a thermal expansion cracking medicine tube is provided, such as Figure 1 As shown, it includes an outer tube body and a thermal expansion agent and a core ignition tube located inside the outer tube body, wherein:

[0035] The outer tube (expansion tube) is quickly heated by igniting the internal thermal expansion agent through a set of ignition wires;

[0036] Thermal expansion agent is a black granular substance, which is made of carbon black, coal gangue powder, straw powder, sodium nitrite, potassium perchlorate and starch adhesive. It is made through screening, mixing, granulation, drying, cooling and packaging process. It is used for rapid expansion after heating.

[0037] Sodium nitrite and potassium perchlorate are used to decompose into potassium chloride and oxygen at a specified melting point.

[0038] The principle of thermal expansion rock cracking here is: using the thermal expansion agent to rapidly vaporize and expand under the condition of sudden and rapid heating, generating a strong expansion force; at this time, through proper control, the effect of expansion cracking and rock breaking is achieved.

[0039] Therefore, the thermal expansion rock cracking powder tube of the present invention utilizes the thermal expansion agent to rapidly vaporize and expand under the condition of sudden and rapid heating, has good rock-breaking destructive power, can cause the effect of expansion-induced cracking and rock-breaking through proper control, does not have the dangerous situations such as explosion in production, storage, and transportation, and will not encounter the situation of fire combustion and explosion, and is safe and convenient.

[0040] Furthermore, it should be noted that the preparation method of the thermal expansion agent specifically includes:

[0041] S1. Raw material screening and activation:

[0042] Conductive carbon black with a particle size of ≤50 μm (specific surface area ≥800 m³ / g) was selected and dried at 150°C for 2 hours to remove adsorbed water;

[0043] Corn straw powder is made from corn straw, which is enzymatically hydrolyzed (cellulase + xylanase, treated at 40°C for 6 hours) and then crushed to 80 mesh (≤180 μm).

[0044] The gangue powder was crushed to 100 mesh (≤150 μm), pickled (immersed in 5% hydrochloric acid for 24 hours) to remove carbonate impurities, dried and premixed with straw powder at a mass ratio of 2:1;

[0045] S2. Oxidant treatment:

[0046] Sodium nitrite was sieved through a 60-mesh sieve (≤250 μm) before use and pre-dry mixed with carbon black to reduce hygroscopicity. Potassium perchlorate was ball-milled to a D90 of ≤20 μm and pre-mixed with sodium nitrite in a mass ratio of 5:3 to avoid static electricity accumulation.

[0047] S3. Systematic proportioning of raw materials

[0048] After feeding with a loss-in-weight feeder, primary mixing (dry mixing) was performed using a double-cone vacuum mixer (speed 15 rpm, vacuum degree -0.08 MPa) in the following order:

[0049] ① Carbon black + sodium nitrite → Mix for 10 minutes (to form a conductive network and reduce the risk of static electricity);

[0050] ② Add coal gangue / straw composite powder → mix for 15 minutes (fiber skeleton construction);

[0051] ③Slowly add potassium perchlorate → mix for 20 minutes (avoid local overheating).

[0052] When the CV value of the mixing uniformity is ≤3% (near infrared spectrum online monitoring), stop the primary mixing (dry mixing);

[0053] Then, the adhesive is added (wet mixing), wherein the starch adhesive is configured into an 8% aqueous solution (pre-gelatinized at 60°C) and added by spraying (atomization pressure 0.3MPa). At this time, the mixing conditions are: maintain vacuum, temperature ≤40°C, humidity ≤15%RH, and stop mixing when the moisture content of the material is ≤0.5%, completing the preparation of the thermal expansion agent.

[0054] The rock-cracking effect of the interaction between sodium nitrite and potassium perchlorate is much greater than that of potassium perchlorate alone used in the prior art. The technical principle is explained as follows:

[0055] Sodium nitrite (decomposition temperature ~320℃) and potassium perchlorate (decomposition temperature ~400℃) can form a temperature-complementary decomposition sequence. The comparison found that:

[0056] Potassium perchlorate alone: single oxygen production is about 240mL / g, peak pressure is 45MPa, and the reaction time window is relatively long (5-8 seconds);

[0057] A mixed system consisting of sodium nitrite and potassium perchlorate: Sodium nitrite rapidly decomposes at low temperatures to release oxygen (120 mL / g) and a small amount of NOx gas (30 mL / g), triggering initial expansion. Potassium perchlorate then decomposes at high temperatures to release high-intensity oxygen (220 mL / g), forming a bimodal pressure curve. The total gas production increases by 28% (to 370 mL / g), the peak pressure increases to 58 MPa (+29%), and the reaction time is shortened to 3-4 seconds.

[0058] Furthermore, the sodium nitrite at this time can act as a nitrogen source oxidant to decompose and generate NOx gas (such as NO, NO2), which combines with the pure oxygen environment of potassium perchlorate to form a mixed oxidizing atmosphere:

[0059] NOx gas has a high diffusion rate (1.5 times faster than oxygen), which can accelerate crack penetration. Therefore, the mixture of oxygen and NOx can further produce a micro-explosion effect (pressure fluctuation frequency +40%) in the closed pores, enhancing rock fatigue damage, and its efficiency is far greater than that of traditional potassium perchlorate alone.

[0060] Therefore, in the specific implementation process, compared with the full potassium perchlorate system, the equivalent blasting energy efficiency of the mixed system can be significantly improved.

[0061] Furthermore, in a specific experiment, DSC testing revealed that the addition of sodium nitrite reduced the activation energy of the gas expansion system in the drug tube by 15%, pushing the reaction from diffusion-controlled to kinetic-dominated:

[0062] The initial reaction rate increased by 2.3 times (TGA data);

[0063] In the sand and gravel filling simulation experiment, the crack propagation speed reached 12m / s (8m / s for the full potassium perchlorate system), and the crack density increased by 42%.

[0064] In a specific embodiment, the friction sensitivity of the thermal expansion cracking cartridge structure of the present application was tested to be 0, the impact sensitivity was 0, and the ignition point was 503.38°C. During the specific test process, two specifications were mainly used: the first was 9 cm in diameter and 1.3 m in length; the second was 9 cm in diameter and 1.5 m in length. The specific dosage is as follows (unit: kg):

[0065] Drug name carbon black Coal gangue powder Straw powder potassium perchlorate Sodium nitrite starch adhesive Incorporation ratio 30％ 13％ 15％ 25％ 15％ 2％ 1.3m expansion tube 4.5 1.95 2.25 3.75 2.25 0.3 1.5m expansion tube 5.1 2.21 2.55 4.25 2.55 0.34

[0066] In a specific embodiment:

[0067] (1) The outer tube body is composed of a group of tube bodies with one end sealed and the other end connected to the cover plate by a thread. The cover plate is provided with a through hole for placing the ignition tube inside the outer tube body and then discharging the fuse from the outer tube body.

[0068] At this time, the production process of the medicine tube includes: processing and making the outer body tube, sealing one end of the outer body tube, filling the tube with thermal expansion agent to 1 / 4 height, placing the core ignition tube and reserving the ignition wire to the tube mouth, continuing to fill the tube with thermal expansion agent until it is full, and finally sealing the top of the thermal expansion tube.

[0069] (2) The outer tube body consists of a group of outer tubes and a group of inner tubes, such as Figure 3 As shown, an external thread is provided at the open end of the inner tube, which is used to be plugged into and assembled with the outer tube body and then rotated and fixed. A through hole is provided at the closed end of the outer tube body, which is used to place the ignition tube inside the outer tube body and discharge the lead from the outer tube body. The through hole is used to continue to inject thermal expansion agent into the internal space of the outer tube body after the outer tube and the inner tube are assembled and fixed.

[0070] At this time Figure 4 As shown, the production process of the medicine tube includes: processing and manufacturing the outer tube and the inner tube, first depositing the tube at a specified height in the outer tube, connecting the ignition tube lead through the through hole to the outer inner tube, and placing an appropriate amount of thermal expansion agent in the inner tube until it is flush with the bottom of the ignition tube. After that, the inner and outer tubes are plugged together and the threads are rotated to fix the assembly, the bottom of the ignition tube is placed on the thermal expansion agent, and the position of the ignition tube is adjusted by the lead so that it is located in the center of the outer tube body. Finally, the thermal expansion agent continues to be deposited through the through hole until the space inside the tube is completely filled.

[0071] In summary, among the thermal expansion agent components of the present application, sodium nitrite does not simply replace potassium perchlorate, but breaks through the performance bottleneck of the single oxidant system through the triple mechanism of graded gas release, gas composition regulation, and reaction kinetics enhancement. Compared with the conventional single use of potassium perchlorate, it can significantly increase the critical detonation temperature while reducing the raw material cost, improve thermal stability, and ensure safety during use and engineering transportation.

[0072] Comparing the actual test results of the thermal expansion rock-splitting cartridge structure of the present application with the existing rock-splitting operation results, we find that:

[0073]

[0074] By comparison, explosive blasting excavation has high safety risks and is difficult to control, and is not suitable for highway reconstruction and expansion construction. At this time, thermal expansion rock cracking has basically achieved the efficiency of explosive blasting excavation, which is much higher than other processes. At the same time, the vibration generated by thermal expansion rock cracking is weak, the noise is very small, and there is basically no noise pollution. At the same time, the rock cracking vibration is very small, and no large amount of dust is generated, and the damage range is within the specified range. For work sites that are more restricted by site factors, it has little impact on the surrounding environment, and no new harmful gases are generated during thermal expansion, which is green and environmentally friendly. Therefore, the thermal expansion rock cracking tube proposed in this application can be used in various small-scale scenes or construction environments with poor ground stability.

[0075] Therefore, based on the above embodiment, Figure 2 As shown, an application method of a thermal expansion stone-cracking medicine tube is further proposed.

[0076] Place the thermal expansion rock-cracking cartridge at the bottom of the preset drill hole, fill the preset hole with sand and gravel, lead out the ignition wire outside the preset hole and seal it, use the ignition wire to control the core ignition tube to cause the thermal expansion agent to heat quickly, causing it to gasify and expand, completing the rock-cracking operation.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0078] In addition, it should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0079] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which A and B are satisfied at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

Claims

1. A thermal expansion stone cracking medicine tube, characterized in that: It includes an outer tube body, a thermal expansion agent and a core ignition tube located inside the outer tube body, wherein: The outer tube body is quickly heated by igniting the internal thermal expansion agent through a set of ignition wires; The thermal expansion agent consists of carbon black, coal gangue powder, straw powder, sodium nitrite, potassium perchlorate and starch adhesive, and is used for rapid expansion after being heated.

2. The thermal expansion stone cracking medicine tube according to claim 1, characterized in that: The preparation ratio of the thermal expansion agent includes 30% carbon black, 13% coal gangue powder, 15% straw powder, 25% potassium perchlorate, 15% sodium nitrite and 2% starch adhesive.

3. The thermal expansion stone cracking medicine tube according to claim 2, characterized in that: The method for making the thermal expansion crack comprises: S1. Raw material screening and activation: Conductive carbon black of a specified particle size was selected and dried to remove adsorbed water. Corn straw was enzymatically treated and then crushed to 80 mesh to obtain straw powder. Coal gangue powder was crushed to 100 mesh, acid-washed to remove carbonate impurities, and dried before being premixed with straw powder at a mass ratio of 2:

1. S2. Oxidant Treatment: Sodium nitrite was sieved through a 60-mesh sieve before use and pre-dry-mixed with carbon black to reduce hygroscopicity. Potassium perchlorate was ball-milled to a D90 of ≤20 μm and pre-mixed with sodium nitrite in a 5:3 mass ratio. S3. After the raw materials are systematically proportioned and fed using a loss-in-weight feeder, they are dry-mixed using a double-cone vacuum mixer. First, mix the carbon black and sodium nitrite for 10 minutes, then add the coal gangue / straw composite powder and mix for 15 minutes, and finally slowly add potassium perchlorate and mix for 20 minutes. When the mixing uniformity CV value is ≤3%, stop dry mixing, and then wet-mix the adhesive in the form of a spray. The starch adhesive is configured as an 8% aqueous solution. Mixing is stopped after the moisture content of the material is ≤0.5%, completing the preparation of the thermal expansion agent.

4. The thermal expansion stone cracking medicine tube according to claim 1, characterized in that: The outer tube body is composed of a group of tube bodies with one end sealed and the other end connected to the cover plate by a thread. A through hole is opened on the cover plate for placing the ignition tube inside the outer tube body and then discharging the fuse from the outer tube body.

5. The thermal expansion stone cracking medicine tube according to claim 4, characterized in that: The production process includes: processing and manufacturing the outer body tube, sealing one end of the outer body tube, pouring thermal expansion agent into the tube to 1 / 4 height, placing the core ignition tube and reserving the ignition wire to the tube mouth, continuing to pour thermal expansion agent into the tube until it is full, and finally sealing the top of the thermal expansion tube.

6. The thermal expansion stone cracking medicine tube according to claim 1, characterized in that: The outer tube body is composed of a group of outer tubes and a group of inner tubes, and the open end of the inner tube is provided with an external thread for rotationally fixing after plugging and combining with the outer tube body. A through hole is opened at the closed end of the outer tube body for discharging the lead from the outer tube body after the ignition tube is placed inside the outer tube body. The through hole is used to continue to inject thermal expansion agent into the internal space of the outer tube body after the outer tube and the inner tube are combined and fixed.

7. The thermal expansion stone cracking medicine tube according to claim 6, characterized in that: The production process includes: processing and making the outer tube and the inner tube, first placing the tube at a specified height in the outer tube, connecting the ignition tube lead to the outer inner tube through the through hole, and placing an appropriate amount of thermal expansion agent in the inner tube until it is flush with the bottom of the ignition tube. After that, the inner and outer tubes are plugged in and combined and the threads are rotated to fix the combination, and the bottom of the ignition tube is placed on the thermal expansion agent. The position of the ignition tube is adjusted through the lead so that it is located in the center of the outer tube body, and finally, the thermal expansion agent continues to be placed through the through hole until the space inside the tube is completely filled.

8. An application of a thermal expansion stone cracking medicine tube, characterized in that: The heat-expandable stone-cracking medicine tube according to any one of claims 1 to 7 is placed in a preset hole to rapidly heat and vaporize and expand.

9. The use of the thermal expansion stone cracking medicine tube according to claim 7, characterized in that: The thermal expansion stone cracking medicine tube is placed at the bottom of a preset hole, and the preset hole is filled with sand and gravel. An ignition wire is led out of the preset hole and then sealed, and a lead is used to control the thermal expansion agent to be heated quickly.

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