Brazing method of vacuum interrupter and vacuum interrupter

Abstract

The present invention belongs to the technical field of vacuum arc chamber manufacturing, and discloses a brazing method of a vacuum arc chamber and a vacuum arc chamber, the method comprising the following steps: adding brazing material to the part to be welded of the vacuum arc chamber; placing the vacuum arc chamber in a vacuum furnace device, starting the device to start vacuuming and heating; melting the brazing material to fill the weld of the part to be welded; stopping heating, and when the temperature in the furnace drops to 270°C to 340°C, starting to inflate and rapidly cool; wherein the inflation pressure is 20kPa to 45kPa. The present invention increases the inflation rapid cooling temperature to 270°C to 340°C on the original basis, which can not only increase the inflation temperature to shorten the process time, but also control the cooling rate within the empirical value, thereby continuously improving the sealing efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of vacuum arc chamber manufacturing, and in particular relates to a brazing method of a vacuum arc chamber and the vacuum arc chamber. Background Art

[0002] The vacuum arc chamber uses vacuum brazing technology to complete the sealing, and the main equipment used is a vacuum furnace. For high-power equipment such as vacuum furnaces, reducing costs and improving production efficiency by reducing their operating time is an important strategy for enterprises to increase profits and competitiveness. When the vacuum arc chamber products are sealed in a vacuum furnace, the temperature-time process curve needs to be set in advance for control. The welding process curve represents the relationship between the welding temperature in the vacuum furnace and time. The sealing curve is divided into three parts: the heating section, the insulation section, and the cooling section. The heating section and the insulation section are already optimal and will not be optimized for the time being. The object of our study this time is the cooling section. The cooling section is mainly the bonding process of the product sealing. As the furnace temperature decreases, the solder distributed on each sealing surface gradually solidifies. At the same time, the different metals used for sealing are sealed together with the metals and the metals and the porcelain shells to form a new alloy to ensure the airtightness of the product.

[0003] The high-power energy-consuming equipment in the production process of vacuum arc chamber products is the vacuum furnace. When the product is sealed in the vacuum furnace, it is necessary to set the temperature-time process curve in advance for control. Curve optimization is a method of energy saving and consumption reduction in the sealing process of vacuum arc chamber products. There are two methods: one is to reduce kinetic energy consumption by optimizing and shortening the process time of the heating section; the other is to increase the inflation and rapid cooling temperature of the cooling section. Usually, in order to shorten the process time, the general measure taken is to increase the inflation (cooling gas) rapid cooling temperature of the curve. As we all know, if the inflation temperature is increased, the sealing time will be shortened, and the cooling rate will increase, and the sealing stress will increase. Therefore, when we gradually increase the inflation temperature to the upper limit of the empirical value, we can no longer optimize it further. The main reason is that we face two major difficulties that cannot be solved: First, there is sealing stress in this section. The existing metal and ceramic sealing stress verification method is limited, and there is no effective verification method; second, there is no theoretical data support for the relationship between the cooling rate and the sealing stress.

[0004] The Chinese patent publication number is CN111261459A, and the name is a patent application for a method for manufacturing a contactor arc extinguishing chamber. The method includes: placing brazing solder at the part to be welded of the arc extinguishing chamber; placing the arc extinguishing chamber in the furnace cavity of a heating furnace; raising the temperature in the heating furnace and exhausting the heating furnace; wherein the temperature in the heating furnace reaches the melting point temperature of the brazing solder after the vacuum degree in the heating furnace reaches a preset vacuum degree. The processing method of the patent application cannot solve the problem of reducing the cooling period. Summary of the invention

[0005] In order to overcome the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a brazing method for a vacuum arc chamber and a vacuum arc chamber, and propose a method of small inflation pressure, which reduces the inflation pressure from the original 70 kPa to 20 kPa to 45 kPa, and increases the inflation rapid cooling temperature to 270°C to 340°C on the original basis, which can not only increase the inflation temperature and shorten the process time, but also control the cooling rate within the empirical value, thereby continuously improving the sealing efficiency.

[0006] To achieve the above object, the technical solution adopted by the present invention is: In a first aspect, the present invention provides a brazing method for a vacuum interrupter, comprising the following steps: Add solder to the part to be welded in the vacuum interrupter; Place the vacuum interrupter in the vacuum furnace equipment, start the equipment to evacuate the vacuum and heat it up; Make the solder melt and fill the weld to be welded; Stop heating, and when the temperature in the furnace drops to 270°C to 340°C, start filling and rapid cooling; the filling pressure is 20kPa to 45kPa.

[0007] Optionally, after placing the vacuum arc extinguishing chamber in the vacuum furnace equipment, the furnace door is closed, and when the equipment starting point is reached, heating begins.

[0008] Optionally, the vacuum furnace equipment is heated to 700° C. to 1000° C. to melt the brazing material.

[0009] Optionally, the gas used for charge cooling is nitrogen.

[0010] Optionally, the materials to be welded at the welded portion of the vacuum interrupter are metal and ceramic.

[0011] Optionally, the solder is a nickel-based amorphous solder.

[0012] Optionally, when starting to inflate and quickly cool, a fan is used for rapid cooling.

[0013] Optionally, after starting to inflate and rapidly cooling, when the temperature in the furnace is less than or equal to 150° C., the pressure is restored to 70 kPa-80 kPa.

[0014] In a second aspect, the present invention provides a vacuum arc extinguishing chamber, which is manufactured by using the brazing method of a vacuum arc extinguishing chamber.

[0015] Optionally, the vacuum arc extinguishing chamber has a seam to be welded, one end of the seam to be welded is metal, and the other end of the seam to be welded is ceramic.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention proposes a method of low-pressure inflation, which reduces the inflation pressure from the original 70 kPa to 20 to 45 kPa, effectively controlling the cooling rate of the rapid cooling point within the empirical value. The inflation rapid cooling temperature is increased to 270°C to 340°C on the original basis, which increases the cooling rate of the cooling stage and shortens the process time.

[0017] The present invention provides a brazing method for a vacuum arc chamber and a vacuum arc chamber in the case where the original optimization method has reached its limit and there is a lack of verification means for the product sealing stress, thereby achieving the effect of shortening the process time of the arc chamber and improving the sealing efficiency. The present invention takes into account that the space inside the vacuum furnace is fixed, and the amount of cooling gas filled into the vacuum furnace per unit time is proportional to its cooling rate. The amount of cooling gas filled is reduced by reducing the inflation pressure, thereby reducing the cooling rate of the inflation and rapid cooling points. At the same time, the inflation temperature and rapid cooling temperature are gradually increased through verification tests to achieve process optimization and improve the sealing efficiency. While reducing the inflation pressure, the present invention can effectively improve the sealing efficiency by increasing the temperature during inflation rapid cooling and controlling the cooling rate within the empirical value, saving 40 to 70 minutes of process time for a single furnace, effectively saving kinetic energy costs, and accelerating the turnover of work-in-progress.

[0018] Furthermore, when the welding materials are metal and ceramic, since the product involves the sealing of ceramic and metal, due to the different expansion coefficients of the materials, if the cooling rate is too fast, the deformation of the ceramic cannot keep up with the deformation of the metal, which will cause tearing and bursting, and the vacuum degree of the product will fail, and then the product will be scrapped. By adopting the method of the present invention, this problem can be avoided.

[0019] Furthermore, the method of the present invention restores the pressure to 70 kPa to 80 kPa after rapid cooling and reaching a safe temperature range, i.e., below 150° C., thereby improving the cooling efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are for explanation purposes only and are not intended to limit the scope of the present invention in any way. In addition, the shapes and proportional dimensions of the components in the drawings are only for illustration purposes to help understand the present invention, and are not intended to specifically limit the shapes and proportional dimensions of the components of the present invention. In the drawings: Figure 1 The historical curves corresponding to different cooling gases in Example 1 of the present invention; Figure 2 The curve optimization fitting conditions of the specific implementation processes of Examples 2 to 4 of the present invention; Figure 3 Schematic diagram of the process flow of an embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0022] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the invention is usually placed when used. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0024] When an element is referred to as being "disposed on" another element, it may be directly on the other element or there may also be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may also be a central element. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only embodiments. If the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but it can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but it can be slightly tilted.

[0025] It should be noted that similar reference numerals and letters represent similar items in the following figures, so once an item is defined in one figure, it does not need to be further defined and explained in the subsequent figures. In the description of the present invention, it is understood that the terms "include" and "comprise" indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the technical field of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, the singular forms of "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise.

[0027] The present invention is described in detail below with reference to the accompanying drawings.

[0028] A brazing method for a vacuum interrupter of the present invention comprises the following steps: Add solder to the part to be welded in the vacuum interrupter; Place the vacuum interrupter in the vacuum furnace equipment, start the equipment to evacuate the vacuum and heat it up; Make the solder melt and fill the weld to be welded; Stop heating and start inflation cooling when the temperature drops to 270°C to 340°C; the inflation pressure is 20kPa to 45kPa.

[0029] The present invention proposes a method for low-pressure inflation, which reduces the inflation pressure from the original 70 kPa to 20 to 45 kPa, and increases the inflation quick cooling temperature to 270°C to 340°C on the original basis. This method can not only increase the inflation temperature and shorten the process time, but also control the cooling rate within the empirical value, thereby continuously improving the sealing efficiency.

[0030] Among them, the empirical value of the cooling rate is: the empirical value of the cooling rate in the charging cooling stage is 1°C / min to 8°C / min, and at the pressure recovery moment, the cooling rate is 1°C / min to 10°C / min.

[0031] Example 1 Combine the following Figure 1 The specific implementation modes of the present invention are further described.

[0032] Under the same conditions, nitrogen has a larger heat capacity than argon, which means that when used as a cooling gas, nitrogen has a better cooling effect than argon.

[0033] Figure 1 The curves in the figure are historical curves corresponding to different cooling gases when sealing the same product in this embodiment, wherein the x curve is argon, the z curve is nitrogen, and the y curve is nitrogen injected when the temperature is high. It is found that the nitrogen filling time is extended by more than one hour compared with the argon filling time, and the slope of the cooling point curve of nitrogen is greater than that of argon.

[0034] By comparing the differences in sealing curves when different cooling gases are filled for the same product with the same furnace input and the same sealing process, it is found that argon filling saves 1 hour compared to nitrogen filling. To this end, first find the cooling rate value at the maximum cooling rate point of the argon filling sealing curve, that is, the cooling rate in the gas filling cooling stage has an empirical value of 1℃ / min to 8℃ / min, and at the moment of pressure recovery, the cooling rate is 1℃ / min to 10℃ / min. Using this empirical value as a criterion, control the cooling rate within the empirical value. Then, improve the sealing efficiency while ensuring the sealing quality of the product. The optimization method of the present invention is based on existing experience and controls the cooling rate within the empirical value, which can ensure that the corresponding sealing stress is controlled below the safety line.

[0035] By reducing the nitrogen slope (cooling rate) through low inflation pressure, that is, fitting the nitrogen curve to the argon curve, it is considered safe to control the target curve in the middle of the historical curve, and forward fitting close to the argon inflation curve but not exceeding the empirical value is the optimization direction. Through experiments, the middle curve is used to achieve the desired effect. Therefore, the method of the present invention uses nitrogen as the inflation cooling gas, and with the corresponding cooling temperature selection, it can achieve the effect of safe and rapid cooling.

[0036] In this embodiment, the sealing of all products is controlled by corresponding time-temperature curves.

[0037] In this embodiment, a vacuum arc chamber product takes 5 hours to heat up and 5 hours to cool down, a total of 10 hours. There are two commonly used optimization methods: one is to reduce the heating time, from 5 hours to 4 hours, that is, it takes 9 hours to weld a furnace of products, saving 1 hour. The second is to increase the temperature at the beginning of the cooling gas filling, increase the cooling rate, and reduce the cooling time by 1 hour, so the total time becomes 8 hours. Since there is no margin at all in the heating section, the main difficulty of the cooling section is: there is sealing stress in the cooling section of the whole tube: the existing sealing stress verification method is limited, and there is no effective verification method; the cooling rate increases, the sealing stress increases, but the relationship between the cooling rate and the sealing stress is not supported by theoretical data. The present invention adopts a low-pressure inflation method to reduce the existing inflation pressure from 70kPa to 20kPa to 45kPa. Considering that the space inside the vacuum furnace is fixed, the amount of cooling gas filled into the vacuum furnace per unit time is proportional to its cooling rate. By reducing the inflation pressure, the amount of cooling gas filled is reduced, thereby reducing the cooling rate of the inflation and quick cooling points. Try to gradually increase the cooling gas inflation temperature and quick cooling temperature. Optimize the process and improve the sealing efficiency. Then conduct repeated experimental verification to achieve the expected effect.

[0038] Based on the existing process, the present invention increases the charging temperature of the cooling gas to 70-100° C. and the minimum pressure to 20 kPa to 45 kPa.

[0039] 70kPa is the normal inflation pressure. After the invention inflates at a low pressure to ensure the reliable cooling rate, as the temperature decreases, when the cooling rate is below the safe range, the pressure needs to be increased to 70kPa to improve the efficiency of the low temperature section (safety section). When the temperature drops to the low temperature section, the slower the cooling rate, if the inflation is carried out at a low pressure throughout the process, the overall efficiency will be reduced. Among them, the safety range refers to the vacuum furnace equipment below 150°C.

[0040] The method of the present invention effectively controls the cooling rate of the fast cooling point within the empirical value by first reducing the inflation pressure of the fast cooling gas. Under the premise of low-pressure inflation, the inflation pressure recovery point is set when the temperature drops to 270°C to 340°C to increase the cooling rate of the low-temperature section. Under the premise of low-pressure inflation, the inflation fast cooling temperature can be increased to 270°C to 340°C on the original basis, which can increase the cooling rate of the cooling section and shorten the process time.

[0041] When the method of the present invention is controlled through a time-temperature curve, the original process parameters are changed from three control quantities of inflation temperature, rapid cooling temperature, and inflation pressure to five control quantities: inflation temperature, rapid cooling temperature, inflation pressure, pressure recovery temperature after rapid cooling, and pressure recovery after rapid cooling.

[0042] Among them, the inflation temperature of the method of the present invention is the same as the starting point of the rapid cooling temperature, both of which are 270°C to 340°C; the inflation gas is nitrogen, and the rapid cooling method adopts a fan for rapid cooling; the inflation pressure is 20kPa-45kPa; the pressure recovery temperature after rapid cooling is 150°C, when the temperature is less than or equal to 150°C after inflation and rapid cooling, the pressure begins to recover to 70kPa-80kPa, wherein 70kPa-80kPa is the normal inflation pressure, and the efficiency of the low temperature section can be improved by increasing the pressure.

[0043] Before sealing, all metal parts are stacked in one area, and solder is added between the parts to complete the assembly before sealing.

[0044] Brazing filler metal refers to the metal or alloy that is added to the joint during the brazing process and melts at a temperature lower than the melting point of the parent metal to fill the gap in the joint. The function of the brazing filler metal is to form a metallurgical bond in the brazed joint through the melting, wetting, spreading, filling and diffusion process of the brazing filler metal itself without melting the parent metal to meet the design requirements of the comprehensive performance of the brazed joint.

[0045] When sealing: place the arc extinguishing chamber in the vacuum furnace equipment, close the furnace door and start vacuuming.

[0046] When the equipment starts to heat up, the temperature gradually rises and gradually reaches the melting point of the solder. The solder melts and fills the weld between the metals.

[0047] After the brazing filler metal melts and fills the weld between the metals, the vacuum furnace begins to cool down, and the brazing filler metal slowly solidifies with the furnace temperature, slowly forming a new alloy at the contact point with the metal.

[0048] This process also seals the high vacuum in the furnace inside the product, achieving the effect of sealing and high vacuum.

[0049] In the cooling stage, the parts of the product have been sealed. In order to increase the cooling rate, cooling gas needs to be filled in. The higher the temperature of the cooling gas, the faster the cooling rate.

[0050] In this embodiment, the materials to be welded at the welding point of the vacuum interrupter are metal and ceramic. Since the product involves the sealing of ceramic and metal, due to the different expansion coefficients of the materials, if the cooling rate is too fast, the deformation of the ceramic cannot keep up with the deformation of the metal, which will cause tearing and bursting, and the vacuum degree of the product will fail, and then the product will be scrapped. This problem can be avoided by adopting the method of starting the inflation cooling when the temperature drops to 270°C to 340°C selected by the method of the present invention.

[0051] Example 2 In this embodiment, a vacuum arc extinguishing chamber brazing method of the present invention is used to conduct an experiment, and the experimental data are as follows: The A1 curve was selected to conduct the test with product A as the representative: when the inflation temperature was increased to 270°C, the rapid cooling temperature remained unchanged, and the inflation pressure was reduced to 45 kPa, the cooling rate in the rapid cooling section decreased, and the rate was within the empirical value, indicating that the method was feasible. Compared with the original process, this process saves about 15 minutes.

[0052] Example 3 In this embodiment, a brazing method of a vacuum interrupter of the present invention is used to conduct an experiment, and the experimental data are as follows: The A2 curve was selected to conduct the test with product A as the representative: when the charging temperature was increased to 300°C, the rapid cooling temperature remained unchanged, and the charging pressure was reduced to 35kPa, the cooling rate in the rapid cooling section decreased, and the rate was within the empirical value. This process saves about 40 minutes compared with the original process.

[0053] Example 4 In this embodiment, a brazing method of a vacuum interrupter of the present invention is used to conduct an experiment, and the experimental data are as follows: The A3 curve was selected to conduct the test with product A as the representative: when the inflation temperature was increased to 340°C, the rapid cooling temperature remained unchanged, and the inflation pressure was reduced to 20 kPa, the cooling rate in the rapid cooling section decreased, and the rate was within the empirical value. This process saves about 70 minutes compared to the original process.

[0054] Example 5 In this embodiment, the parameters in Embodiment 3 are selected and a brazing method of a vacuum arc extinguishing chamber of the present invention is used for testing. At the same time, 3 test samples and 3 normal samples are welded with normal process parameters, and tensile tests are performed respectively.

[0055] The test data are as follows: the average tensile strength of the test samples is 176.33MPa, and the average tensile strength of the normal samples is 166.33MPa. The two data are equivalent, and the fracture positions of all samples are in the middle part of the porcelain shell, not the metallized layer, which proves that the samples welded by this process can meet the basic tensile test requirements.

[0056] In summary, under the premise of ensuring product quality, for vacuum interrupter products, the rapid cooling nitrogen filling temperature can be appropriately increased by using the method of low-pressure inflation, thus reducing the process time by 40 to 70 minutes.

[0057] Example 6 A vacuum arc extinguishing chamber is manufactured by adopting the brazing method of a vacuum arc extinguishing chamber.

[0058] Optionally, the vacuum arc extinguishing chamber has a seam to be welded, one end of the seam to be welded is metal, and the other end of the seam to be welded is ceramic.

[0059] Optionally, in this embodiment, the vacuum furnace equipment used is a vacuum brazing furnace. The vacuum brazing furnace can be used for vacuum brazing of aluminum products such as aluminum alloy heat exchangers, brazing of stainless steel, titanium alloy, hard alloy, high temperature alloy, non-ferrous metals, and vacuum tempering of high-speed steel, tool steel, bearing steel, stainless steel and other materials.

[0060] Unless otherwise specified, the device elements involved in the above embodiments are all conventional device elements, and the structural settings, working modes or control modes involved are all conventional settings, working modes or control modes in the art unless otherwise specified.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in the field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A brazing method for a vacuum interrupter, characterized in that: The following steps are involved: Add solder to the part to be welded in the vacuum interrupter; Place the vacuum interrupter in the vacuum furnace equipment, start the equipment to evacuate the vacuum and heat it up; Make the solder melt and fill the weld to be welded; Stop heating, and when the temperature in the furnace drops to 270°C to 340°C, start filling and rapid cooling; the filling pressure is 20kPa to 45kPa.

2. A vacuum interrupter brazing method according to claim 1, characterized in that: After placing the vacuum arc extinguishing chamber in the vacuum furnace equipment, close the furnace door, and start heating when the equipment starts.

3. A brazing method for a vacuum interrupter according to claim 1, characterized in that: The vacuum furnace equipment is heated to 700°C to 1000°C to melt the brazing material.

4. A brazing method for a vacuum interrupter according to claim 1, characterized in that: The gas used for charge cooling is nitrogen.

5. A brazing method for a vacuum interrupter according to claim 1, characterized in that: Materials to be welded at the welded portion of the vacuum interrupter are metal and ceramic.

6. A brazing method for a vacuum interrupter according to claim 1, characterized in that: The solder is a nickel-based amorphous solder.

7. A brazing method for a vacuum interrupter according to claim 1, characterized in that: When starting to inflate and quickly cool, a fan is used for rapid cooling.

8. A vacuum interrupter brazing method according to claim 1, characterized in that: After starting to charge and rapidly cool, when the temperature in the furnace is less than or equal to 150°C, the pressure is restored to 70kPa-80kPa.

9. A vacuum interrupter, characterized in that: The vacuum arc extinguishing chamber is manufactured by the brazing method of any one of claims 1 to 8.

10. A vacuum interrupter according to claim 9, characterized in that: The vacuum interrupter has a seam to be welded, one end of the seam to be welded is metal, and the other end of the seam to be welded is ceramic.

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