Carbon-carbon heat preservation cylinder and manufacturing method

Abstract

The invention provides a carbon-carbon thermal insulation cylinder and a manufacturing method thereof. The carbon-carbon thermal insulation cylinder comprises a cylinder body, the cylinder body is made of a carbon-carbon composite material, a thermal insulation cavity is formed in the cylinder body, a thermal insulation layer is arranged in the cylinder body, the thermal insulation layer is arranged around the thermal insulation cavity, and the thermal insulation layer is filled with aluminum oxide cotton; and the cover bodies are arranged at the two ends of the cylinder body in a covering mode so that the heat preservation layer can be limited in the cylinder body. The technical problem that in the prior art, the crystal pulling production cost is rigid is solved.

Description

Technical Field

[0001] The invention relates to the technical field of single crystal furnaces, and in particular to a carbon-carbon heat preservation tube and a manufacturing method thereof. Background Art

[0002] Since the massive expansion of photovoltaic production, the photovoltaic industry has experienced overcapacity and sharp fluctuations in product prices. The four main photovoltaic materials that were once expensive - silicon materials, silicon wafers, batteries, and modules - have all experienced a significant "diving" price correction. The "stalling" performance of the photovoltaic third quarter report has actually sounded the alarm for investors - the industry has entered a reshuffle and elimination round, and the inventory of old products is facing clearance. The continued price drop of products will test the cash reserves of companies, and challenges are coming one after another. In the secondary market, the photovoltaic sector has fallen unilaterally throughout the year. It seems that everything indicates that the photovoltaic industry will fall into a downturn and some manufacturers may suffer losses.

[0003] In the current economic situation, enterprises require that as market competition becomes increasingly fierce, it is particularly important to improve the cost-effectiveness and competitiveness of products, and reducing costs and increasing efficiency have become the primary tasks of enterprises. In the existing technology, the power of crystal pulling production using an insulation barrel is relatively high, generally controlled at around 70KW, and the production cost has remained stagnant.

[0004] Therefore, the prior art needs to be further developed. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned technical deficiencies and provide a carbon-carbon insulation cylinder and a manufacturing method to solve the technical problem of high crystal pulling production cost in the related art.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions: a carbon-carbon insulation cylinder is provided, comprising: a cylinder body, the cylinder body is made of a carbon-carbon composite material, the cylinder body has an insulation cavity, the cylinder body has an insulation layer, the insulation layer is arranged around the insulation cavity, and the insulation layer is filled with alumina wool; a cover body, the cover body is arranged on the cylinder body to limit the insulation layer within the cylinder body.

[0007] Furthermore, the cylinder includes: an inner cylinder, which is arranged around the insulation cavity; an outer cylinder, which is arranged at an interval with the inner cylinder to form a accommodating cavity for accommodating the insulation layer between the inner cylinder and the outer cylinder; the outer cylinder is arranged on a side of the inner cylinder close to the insulation layer, and the outer cylinder is arranged around the insulation layer.

[0008] Furthermore, the cover body is detachably connected to the cylinder body to open or close the accommodating cavity.

[0009] Furthermore, the cover body comprises an upper cover and a lower cover, the upper cover is detachably arranged at one end of the cylinder body, and the lower cover is detachably arranged at the other end of the cylinder body.

[0010] Further, the upper cover includes a first mounting portion and a second mounting portion, and a first mounting groove for sleeve-mounting the cylinder body is arranged between the first mounting portion and the second mounting portion; and / or, the lower cover includes a third mounting portion and a fourth mounting portion, and a second mounting groove for sleeve-mounting the cylinder body is arranged between the third mounting portion and the fourth mounting portion.

[0011] Further, a first extrusion portion is provided in the first installation groove, and the first extrusion portion is used to extrude the thermal insulation layer; and / or a second extrusion portion is provided in the second installation groove, and the second extrusion portion is used to extrude the thermal insulation layer.

[0012] Furthermore, a first limiting portion is provided at one end of the inner cylinder, the first limiting portion is protruding from the surface of the inner cylinder along the axial direction of the inner cylinder, and a first limiting platform is provided on the side of the first limiting portion close to the insulation chamber; a second limiting portion is provided at one end of the outer cylinder close to the first limiting portion, the second limiting portion is protruding from the surface of the outer cylinder along the axial direction of the outer cylinder, and a second limiting platform is provided on the side of the second limiting portion away from the first limiting portion.

[0013] Furthermore, the first limiting portion is provided with a plurality of first mounting holes arranged at intervals, and the plurality of first mounting holes are used for fasteners to pass through; the first mounting portion is provided with a plurality of second mounting holes arranged at intervals, and the second mounting holes are arranged one-to-one corresponding to the first mounting holes, and the second mounting holes are used for fasteners to pass through.

[0014] A method for manufacturing a carbon-carbon thermal insulation cylinder comprises: preparing a preform according to a first preset size; subjecting the preform to high temperature treatment to obtain a hardened preform; subjecting the hardened preform to densification treatment to obtain a carbon-carbon composite material; processing the obtained carbon-carbon composite material according to a second preset size to obtain a cylinder and a cover; and assembling the cylinder, the cover and the thermal insulation layer to obtain the thermal insulation cylinder.

[0015] Furthermore, the method for assembling the heat-insulating cylinder includes: assembling the cover body with one end of the cylinder body, filling alumina wool into the cylinder body to form a heat-insulating layer, and covering the other end of the cylinder body with the cover body to obtain the heat-insulating cylinder.

[0016] Beneficial effects:

[0017] 1. The carbon-carbon heat preservation tube of the present invention achieves the effect of reducing power by designing the structure and combining different materials using their physical properties, thereby further reducing the production cost.

[0018] 2. The carbon-carbon heat preservation tube of the present invention better controls the overall thermal conductivity by combining the carbon-carbon composite material with the selected alumina wool material.

[0019] 3. The carbon-carbon heat preservation cylinder of the present invention reduces the complicated loading method of single crystals by combining different parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the structure of the carbon-carbon heat preservation cylinder used in the embodiment of the present invention;

[0021] Figure 2 yes Figure 1 A partial enlarged schematic diagram of part A;

[0022] Figure 3 is a top view of the cylinder body of the carbon-carbon heat preservation cylinder used in the embodiment of the present invention;

[0023] Figure 4 Schematic diagram of the structure of the cover of the carbon-carbon heat preservation cylinder used in the embodiment of the present invention;

[0024] Figure 5 It is a cross-sectional view of the carbon-carbon heat preservation tube used in the embodiment of the present invention.

[0025] The above drawings include the following reference numerals:

[0026] 1. Cylinder; 11. Insulation cavity; 12. Insulation layer; 13. Inner cylinder; 131. First limiting portion; 1311. First mounting hole; 132. First limiting platform; 14. Outer cylinder; 141. Second limiting portion; 142. Second limiting platform; 15. Accommodating cavity; 2. Cover; 21. Upper cover; 211. First mounting portion; 2111. Second mounting hole; 212. Second mounting portion; 213. First mounting groove; 2131. First extrusion portion; 22. Lower cover; 221. Third mounting portion; 222. Fourth mounting portion; 223. Second mounting groove; 2231. Second extrusion portion. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0028] According to an embodiment of the present invention, a carbon-carbon heat preservation cylinder is provided. Figures 1 to 5 , including: a cylinder 1, the cylinder 1 is made of carbon-carbon composite material, the cylinder 1 has a heat preservation cavity 11, the cylinder 1 has a heat preservation layer 12, the heat preservation layer 12 is arranged around the heat preservation cavity 11, and the heat preservation layer 12 is filled with alumina wool; a cover body 2, the cover body 2 is covered on the cylinder 1 to limit the heat preservation layer 12 in the cylinder 1.

[0029] By adopting the above arrangement, alumina wool is filled into the cylinder 1 made of carbon-carbon composite material to form an insulation layer surrounding the insulation cavity 11. The carbon-carbon composite material and alumina wool are combined together to utilize their unique physical properties to solve the problem of high crystal pulling production power of the single crystal furnace insulation cylinder.

[0030] Specifically, alumina wool is a polycrystalline inorganic fiber whose main component is alumina. It usually also contains about 5% silicon dioxide to stabilize the crystal phase and inhibit the growth of grains at high temperatures. Alumina wool is one of the latest ultra-light high-temperature insulation materials at home and abroad. It has a use temperature of 1450℃-1600℃ and a melting point of 1840℃. It has good heat resistance and stability. It can be used in acidic environments, oxidizing atmospheres, reducing atmospheres and vacuum conditions. It also has a certain corrosion resistance to alkaline environments. Because alumina wool has good thermal insulation effect, low thermal conductivity, heating shrinkage and heat capacity, it reduces the operating power of the equipment.

[0031] In actual practice, the temperature of pulling single crystals is continuously maintained at around 1600°C. During the process of pulling single crystals, silicon material will release silicon vapor, which will gradually corrode the carbon material of the carbon-carbon insulation tube. Silicon vapor reacts with the carbon-carbon composite material to form silicon carbide, causing the wall thickness of the carbon-carbon insulation tube to gradually become thinner and eventually lose its insulation effect. The alumina wool filled in the insulation tube will not react with silicon vapor. Therefore, the insulation tube can still maintain its existing physical properties, and the service life of the carbon-carbon insulation tube is also increased.

[0032] In the process of crystal pulling with a heat preservation tube, the power parameters and other performance parameters corresponding to the present application and the prior art are compared as shown in the following table:

[0033] contrast Temperature ℃ Vacuum degree pa Operating power kw / h Tensile strengthMpa Crystallization rate of crystal rod % Current production parameters 1600 500 70 260 98 Parameters after improvement 1600 500 60 260 98

[0034] In the carbon-carbon heat preservation cylinder of this embodiment, see Figure 3 The cylinder 1 comprises: an inner cylinder 13, which is arranged around the heat preservation cavity 11; an outer cylinder 14, which is arranged at intervals with the inner cylinder 13 to form a receiving cavity 15 for receiving the heat preservation layer 12 between the inner cylinder 13 and the outer cylinder 14; the outer cylinder 14 is arranged on the side of the inner cylinder 13 close to the heat preservation layer 12, and the outer cylinder 14 is arranged around the heat preservation layer 12. In this way, the inner cylinder 13 is arranged around the heat preservation cavity 11 to keep the heat preservation cavity 11 warm. The inner cylinder 13 is the first heat preservation measure. There is a receiving cavity 15 in the inner cylinder 13 and the outer cylinder 14. Alumina wool can be filled in the receiving cavity 15 to form the heat preservation layer 12. The heat preservation layer 12 is the second heat preservation measure. The outer cylinder 14 is arranged around the receiving cavity 15. The outer cylinder 14 serves as the third heat preservation measure. The three heat preservation measures work together to reduce the production power of the heat preservation cylinder crystal pulling.

[0035] In the carbon-carbon heat preservation cylinder of this embodiment, see Figure 1 The cover 2 is detachably connected to the barrel 1 to open or close the accommodating chamber 15. In this way, the cover 2 and the barrel 1 are detachably connected, and the combination of the cover 2 and the barrel 1 is more flexible and simple, which reduces the manufacturing difficulty of the carbon-carbon insulation barrel and avoids the cumbersome loading method of the single crystal.

[0036] In the carbon-carbon heat preservation cylinder of this embodiment, see Figure 1 The cover body 2 includes an upper cover 21 and a lower cover 22. The upper cover 21 is detachably arranged at one end of the cylinder body 1, and the lower cover 22 is detachably arranged at the other end of the cylinder body 1. In this way, when filling the accommodating cavity 15 of the cylinder body 1 with alumina wool, the lower cover 22 can be installed first, and then the accommodating cavity 15 is filled with alumina wool. At this time, the lower cover 22 plays a role of limiting and squeezing the thermal insulation layer 12. After the filling of alumina wool is completed, the upper cover 21 is covered to seal the alumina wool in the accommodating cavity 15.

[0037] In the carbon-carbon heat preservation cylinder of this embodiment, see Figure 4 The upper cover 21 includes a first mounting portion 211 and a second mounting portion 212, and a first mounting groove 213 for sleeve mounting of the barrel 1 is provided between the first mounting portion 211 and the second mounting portion 212; and / or the lower cover 22 includes a third mounting portion 221 and a fourth mounting portion 222, and a second mounting groove 223 for sleeve mounting of the barrel 1 is provided between the third mounting portion 221 and the fourth mounting portion 222. In this way, there is a first mounting groove 213 between the first mounting portion 211 and the second mounting portion 212, and the barrel 1 can be inserted into the first mounting groove 213, so that the barrel 1 is connected to the cover 2. Similarly, there is a second mounting groove 223 between the third mounting portion 221 and the fourth mounting portion 222, and the barrel 1 is inserted into the second mounting groove 223, so that the barrel 1 is connected to the cover 2.

[0038] In the carbon-carbon heat preservation cylinder of this embodiment, see Figure 2 The first installation groove 213 is provided with a first extrusion portion 2131, and the first extrusion portion 2131 is used to extrude the thermal insulation layer 12; and / or the second installation groove 223 is provided with a second extrusion portion 2231, and the second extrusion portion 2231 is used to extrude the thermal insulation layer 12. In this way, the first extrusion portion 2131 extrude the aluminum oxide wool in the thermal insulation layer 12 in a direction away from the first extrusion portion 2131, so that the thermal insulation layer 12 in the accommodating cavity 15 has a higher density and a better thermal insulation effect.

[0039] In the carbon-carbon heat preservation cylinder of this embodiment, see Figure 2, a first limiting portion 131 is provided at one end of the inner cylinder 13, the first limiting portion 131 is provided on the surface of the inner cylinder 13 along the axial direction of the inner cylinder 13, and a first limiting platform 132 is provided on the side of the first limiting portion 131 close to the heat preservation chamber 11; a second limiting portion 141 is provided at one end of the outer cylinder 14 close to the first limiting portion 131, the second limiting portion 141 is provided on the surface of the outer cylinder 14 along the axial direction of the outer cylinder 14, and a second limiting platform 142 is provided on the side of the second limiting portion 141 away from the first limiting portion 131. In this way, after the cover 2 is connected to the cylinder 1, the first limiting portion 131 abuts against the cover 2, and the first limiting platform 132 abuts against the first mounting portion 211. Similarly, the second limiting portion 141 abuts against the cover 2, and the second limiting platform 142 abuts against the second mounting portion 212, so that the cover 2 is sleeved on one end of the cylinder 1.

[0040] In the carbon-carbon heat preservation cylinder of this embodiment, see Figure 2 The first position-limiting portion 131 is provided with a plurality of first mounting holes 1311 arranged at intervals, and the plurality of first mounting holes 1311 are used for fasteners to pass through; the first mounting portion 211 is provided with a plurality of second mounting holes 2111 arranged at intervals, and the second mounting holes 2111 are arranged one-to-one with the first mounting holes 1311, and the second mounting holes 2111 are used for fasteners to pass through. In this way, the fastener passes through the first mounting holes 1311 and the second mounting holes 2111, and the first position-limiting portion 131 and the first mounting portion 211 are connected together, and then the cylinder body 1 and the cover body 2 are connected.

[0041] The present embodiment provides a method for manufacturing a carbon-carbon thermal insulation cylinder, comprising: preparing a preform according to a first preset size; subjecting the preform to high-temperature treatment to obtain a hardened preform; subjecting the hardened preform to densification treatment to obtain a carbon-carbon composite material; processing the obtained carbon-carbon composite material according to a second preset size to obtain a cylinder 1 and a cover 2; and assembling the cylinder 1, the cover 2 and the thermal insulation layer 12 to obtain the thermal insulation cylinder.

[0042] Specifically, the carbon fiber preforms of the upper cover, the lower cover, the inner cylinder and the outer cylinder are prepared by three-dimensional weaving, wherein the first preset size is specifically: the density of the fiber preform is 0.43-0.45g / cm 3 Between 0.43-0.45g / cm 3 The density range is the highest fiber content. If the density is higher than 0.45g / cm 3 The internal raw materials are easy to delaminate, resulting in product scrapping, and the density is less than 0.43g / cm 3 Insufficient fiber content affects the thermal insulation effect. At the same time, a 3-5mm margin is left in the inner and outer diameters and height directions to ensure subsequent processing. The second preset size is the finished product size.

[0043] The carbon fiber preform is treated at 300℃ to cure the soft fiber filaments to a hard state, ensuring that the product does not deform. 300℃ can harden the soft preform. If the temperature is lower than 300℃, the hardness of the preform will be insufficient after hardening. If the temperature is higher than 300℃, it will waste resources.

[0044] After hardening, heat to 1000-1100℃, maintain vacuum at 2.5-3KPa, then introduce carbon source gas, crack natural gas in high temperature atmosphere, and adhere to the surface of fiber pores to form deposited carbon, and mix 20% nitrogen as carrier gas to improve density uniformity. 1000-1100℃ is the best temperature for methane to crack into carbon, 2.5-3Kpa is the most suitable pressure range for maintaining the gas residence time of dense process, and 20% nitrogen is mixed in, which is calculated to be 2 / 10 of the nitrogen ratio, which can just carry the same amount of gas to flow through the product channel.

[0045] Since the utilization rate of carbon in methane is only about 30-35%, when the densification process is running for 2 / 3 of the time, the utilization rate of carbon in methane is between 25-30%, and then the utilization rate of carbon in methane decreases. Therefore, when the process is running for 2 / 3 of the time, the pressure in the furnace is changed to 2-2.5KPa to avoid large-area crusting and carbon black due to restricted airflow. After the densification process is completed, the vacuum system is turned off, and nitrogen protective gas is filled to normal pressure. The vent valve is opened to continue to inflate, and the nitrogen filling is stopped when the furnace temperature drops to room temperature to obtain a carbon / carbon composite material.

[0046] In the manufacturing method of the carbon-carbon insulation cylinder of the present embodiment, the method of assembling the insulation cylinder includes: assembling the cover body 2 with one end of the cylinder body 1, filling alumina wool into the cylinder body 1 to form an insulation layer, and covering the other end of the cylinder body 1 with the cover body 2 to obtain the insulation cylinder.

[0047] In specific practice, after obtaining the carbon-carbon composite material, the carbon-carbon composite material is mechanically processed to obtain the upper cover 21, the lower cover 22, the inner cylinder 13 and the outer cylinder 14 of the finished composite size, and then the assembly begins. First, the lower cover 22 is placed on the bottom, and then the inner cylinder 13 and the outer cylinder 14 are clamped on the lower cover 22. Then, alumina wool is filled into the accommodating cavity 15 between the inner cylinder 13 and the outer cylinder 14, and the upper cover 21 is buckled. Finally, fasteners are used to connect the connection between the cylinder 1 and the cover 2, and bolts are used to tighten them to complete the assembly work.

[0048] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0049] Optionally, the specific examples in this embodiment may refer to the examples described in the above embodiments, and this embodiment will not be described in detail here.

[0050] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0051] In the above embodiments of the present application, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments.

[0052] The above are only preferred implementations of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A carbon-carbon heat preservation cylinder, characterized in that: include: A cylinder (1), wherein the cylinder (1) is made of a carbon-carbon composite material, wherein a heat preservation cavity (11) is provided in the cylinder (1), wherein a heat preservation layer (12) is provided in the cylinder (1), wherein the heat preservation layer (12) is arranged around the heat preservation cavity (11), and wherein the heat preservation layer (12) is filled with alumina wool; A cover body (2), wherein the cover body (2) is arranged on the cylinder body (1) to limit the thermal insulation layer (12) within the cylinder body (1).

2. The carbon-carbon heat preservation cylinder according to claim 1, characterized in that: The cylinder (1) comprises: An inner cylinder (13), wherein the inner cylinder (13) is arranged around the heat preservation chamber (11); An outer cylinder (14), the outer cylinder (14) and the inner cylinder (13) are arranged at a distance to form a receiving cavity (15) for receiving the thermal insulation layer (12) between the inner cylinder (13) and the outer cylinder (14); the outer cylinder (14) is arranged on a side of the inner cylinder (13) close to the thermal insulation layer (12), and the outer cylinder (14) is arranged around the thermal insulation layer (12).

3. The carbon-carbon heat preservation cylinder according to claim 2, characterized in that: The cover body (2) is detachably connected to the cylinder body (1) to open or close the accommodating chamber (15).

4. The carbon-carbon heat preservation cylinder according to claim 3, characterized in that: The cover body (2) comprises an upper cover (21) and a lower cover (22); the upper cover (21) is detachably arranged at one end of the cylinder (1), and the lower cover (22) is detachably arranged at the other end of the cylinder (1).

5. The carbon-carbon heat preservation cylinder according to claim 4, characterized in that: The upper cover (21) comprises a first mounting portion (211) and a second mounting portion (212), and a first mounting groove (213) for sleeve-mounting the barrel (1) is provided between the first mounting portion (211) and the second mounting portion (212); and / or, The lower cover (22) comprises a third mounting portion (221) and a fourth mounting portion (222), and a second mounting groove (223) for sleeve-mounting the barrel (1) is provided between the third mounting portion (221) and the fourth mounting portion (222).

6. The carbon-carbon heat preservation cylinder according to claim 5, characterized in that: A first extrusion portion (2131) is provided in the first installation groove (213), and the first extrusion portion (2131) is used to extrude the thermal insulation layer (12); and / or, A second extrusion portion (2231) is provided in the second installation groove (223), and the second extrusion portion (2231) is used to extrude the thermal insulation layer (12).

7. The carbon-carbon heat preservation cylinder according to claim 5, characterized in that: A first limiting portion (131) is provided at one end of the inner cylinder (13), the first limiting portion (131) is provided protruding from the surface of the inner cylinder (13) along the axial direction of the inner cylinder (13), and a first limiting platform (132) is provided on one side of the first limiting portion (131) close to the heat preservation chamber (11); A second limiting portion (141) is provided at one end of the outer cylinder (14) close to the first limiting portion (131); the second limiting portion (141) is provided along the axial direction of the outer cylinder (14) and protrudes from the surface of the outer cylinder (14); and a second limiting platform (142) is provided on the side of the second limiting portion (141) away from the first limiting portion (131).

8. The carbon-carbon heat preservation cylinder according to claim 7, characterized in that: The first limiting portion (131) is provided with a plurality of first mounting holes (1311) arranged at intervals, and the plurality of first mounting holes (1311) are used for fasteners to pass through; The first mounting portion (211) is provided with a plurality of second mounting holes (2111) arranged at intervals, the second mounting holes (2111) being arranged in a one-to-one correspondence with the first mounting holes (1311), and the second mounting holes (2111) are used for the fasteners to pass through.

9. A method for manufacturing a carbon-carbon heat preservation cylinder, characterized in that: include: preparing a preform according to a first preset size; performing high temperature treatment on the preform to obtain a hardened preform; Densifying the hardened preform to obtain a carbon-carbon composite material; Processing the obtained carbon-carbon composite material according to a second preset size to obtain a cylinder (1) and a cover (2); The cylinder (1), the cover (2) and the heat-insulating layer (12) are assembled to obtain a heat-insulating cylinder.

10. The method for manufacturing the carbon-carbon heat preservation cylinder according to claim 9, characterized in that: The method for assembling a heat-insulating cylinder comprises: assembling a cover body (2) with one end of a cylinder body (1), filling the cylinder body (1) with alumina wool to form a heat-insulating layer, and covering the other end of the cylinder body (1) with the cover body (2) to obtain the heat-insulating cylinder.

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