A plasma-flame composite cutting torch for nuclear power thick-walled stainless steel complex pipe fittings

Abstract

The present invention belongs to the technical field of nuclear power pipe cutting devices and discloses a plasma-flame composite cutting torch for cutting complex thick-walled stainless steel pipe fittings for nuclear power plants. The torch comprises a plasma cutting torch and a flame torch mounted thereon and capable of moving up and down along the axis of the plasma cutting torch. The flame torch is provided with an oxygen channel and a gas channel, respectively. The oxygen channel's gas outlet A and the gas channel's gas outlet B are located on the same horizontal plane, and the vertical distance between the oxygen channel's gas outlet A and the gas channel's gas outlet B and the plasma cutting torch's nozzle is 10 to 20 mm. By coaxially attaching a composite flame torch to an existing plasma cutting torch, the present invention reduces the energy and velocity losses of the plasma arc caused by the shock wave effect, thereby improving the capability and quality of plasma cutting and resolving the plasma cutting problem encountered by the full range of models during the AP1000 nuclear power plant thick-walled stainless steel pipe extrusion manufacturing process.

Description

Technical Field

[0001] The present invention proposes a plasma-flame composite cutting torch, which belongs to the technical field of ultra-thick stainless steel and nuclear power thick-walled pipe cutting devices, and particularly relates to a high-quality, high-efficiency cutting torch for 316L and 316LN stainless steel with a thickness or wall thickness of 120mm-180mm. Background Art

[0002] Compared to traditional forging, extrusion offers significant advantages in improving product quality and shortening manufacturing cycles due to the continuous deformation of various metal components during the forming process, resulting in a shorter forming time. To further reduce production costs, improve efficiency, and achieve near-net-shape manufacturing of nozzles for complex nuclear power pipe fittings, specialized high-power plasma cutting technology and equipment are urgently needed. However, the maximum wall thickness of nuclear power main pipelines ranges from 80-120mm, and the theoretical thickness of bevel cutting exceeds the cutting capacity of the highest-power plasma power sources currently available, both domestically and internationally. This results in poor cutting quality or difficulty in removing thick-walled bevels.

[0003] Extruded pipe fittings require the removal of excess parts, such as nozzles. However, nuclear power main pipe fittings, super pipe fittings, and oblique tees are large in size and specifications. For example, the AP1000 nuclear power main pipe has a maximum total length of 8000mm, a maximum end diameter of 2000mm, and a maximum wall thickness of 120mm. These fittings cannot be flipped during cutting, so they must be fixed and cut at various positions using a robotic arm. Because the cutting position is not fixed, the cutting must be able to be completed at any position within the placement area, that is, 360° cutting at all positions.

[0004] In the existing technology, the thin-walled part of the pipe can be cut by using a general-purpose plasma power supply equipment. The current cutting capacity of the highest-power power supply at home and abroad can theoretically achieve vertical cutting of 160mm thick stainless steel and 360° cutting of 100mm thick pipes (such as the inventor's previous patents CN201710896069.0 and CN201810526046.5). The maximum wall thickness of the AP1000 super pipe is generally 80-120mm, and the maximum theoretical requirement for bevel cutting can reach 170mm (45° bevel 360° cutting). Therefore, the existing plasma cutting technology cannot meet the cutting requirements of all types of nuclear power pipelines. In addition, the technology currently commonly used internationally is integral forging followed by machining. Since the typical nuclear power steel 316LN has high hardness and is difficult to process, machining requires a large amount of tools and time, and the cost is too high; nuclear power pipe fittings are large in size and require large multi-axis machining centers for processing, which makes clamping very difficult; the pipe fittings have large wall thickness, the amount of groove processing removed is large, and the machining efficiency is extremely low; the above shortcomings lead to low processing efficiency and high cost, which is not conducive to the development of new technologies for extrusion-formed nuclear power pipe fittings.

[0005] Moreover, when plasma power equipment is used for cutting in the prior art, due to the limitations of the plasma power and current, as the cutting thickness increases, the kinetic energy of the plasma gradually decreases, the speed drops rapidly, the power density decreases, and the impact force of the plasma jet decreases, resulting in insufficient cutting capacity and a significant deterioration in the quality of the lower part of the incision. It is easy to leave molten metal or the cut cannot be continued, and it cannot meet the requirements of vertical cutting of more than 150mm and 360° circular cutting of more than 120mm for materials such as stainless steel.

[0006] Furthermore, due to the high current of high-power plasma cutting, as the cutting power increases, the power density at the cathode arc root will become very high, resulting in a high local ablation rate of the electrode and extremely easy damage to related consumable parts, seriously affecting production efficiency and cutting quality. These problems have greatly restricted the high-quality plasma cutting of stainless steel with a thickness of more than 70mm and non-ferrous metals with a thickness of more than 120mm. In particular, when plasma cutting thicknesses of more than 150mm, the frequency of electrode nozzle burnout is extremely high, resulting in extremely poor cutting quality or even inability to complete the cutting operation. Therefore, in the current situation where plasma power sources and cutting torches with higher power and current cannot be obtained in the short term, the most practical and effective method is to improve the process through innovative torch design to improve the thickness and quality of existing high-power plasma cutting to meet the manufacturing needs of major core technology equipment such as nuclear power pipelines.

[0007] To this end, the present invention provides a plasma-flame coaxial composite cutting torch for nuclear power thick-walled stainless steel complex pipe fittings. Summary of the Invention

[0008] In order to solve the problem in the background technology that the cutting thickness and quality of existing plasma cutting equipment cannot reach 120-180mm, the present invention proposes a plasma-flame coaxial composite cutting torch for nuclear power thick-walled stainless steel complex pipe fittings.

[0009] The plasma-flame coaxial composite cutting process for nuclear power thick-walled stainless steel complex pipe fittings of the present invention is achieved through the following technical solutions:

[0010] A plasma-flame composite cutting torch for nuclear power thick-walled stainless steel complex pipe fittings, comprising a plasma cutting torch and a flame torch, wherein the flame torch is coaxially sleeved outside the plasma cutting torch and can move up and down along the axial direction of the plasma cutting torch;

[0011] The flame torch is provided with an oxygen channel and a gas channel that are independent of each other, and the gas outlet A of the oxygen channel and the gas outlet B of the gas channel are located on the same horizontal plane; and the vertical distance between the bottom of the gas outlet A and the gas outlet B and the nozzle of the plasma cutting torch is 10 to 20 mm

[0012] The gas outlet A and the gas outlet B are both composed of a stabilizing section and a diffusion section structure, presenting a diffusion structure; and the gas outlet A and the gas outlet B are both inclined, and the bottoms of the gas outlet A and the gas outlet B are both pointing to the axis of the plasma cutting torch.

[0013] Furthermore, the gas outlet A of the oxygen channel consists of a stabilizing section A and a diffusion section A, and the diameter of the stabilizing section A is 2.5 mm, the diffusion taper of the diffusion section A is 1.146%, and the diffusion length is 8 to 10 mm;

[0014] The gas outlet B of the gas channel consists of a stabilizing section B and a diffusing section B. The diameter of the stabilizing section B is 2.5 mm, the diffusion taper of the diffusing section B is 1.146%, and the diffusion length is 12 to 16 mm.

[0015] Furthermore, the oxygen channel is arranged on a side of the flame torch close to the plasma cutting torch, and the gas channel is arranged on a side of the flame torch away from the plasma cutting torch.

[0016] Furthermore, the angle between the gas outlet A of the oxygen channel and the axis of the plasma cutting torch is 8° to 12°;

[0017] The angle between the gas outlet B of the gas channel and the axis of the plasma cutting torch is 12° to 16°.

[0018] Furthermore, a plurality of gas outlets A of the oxygen channel are provided, and the plurality of gas outlets A of the oxygen channel are equidistantly arranged on the flame torch body along the circumferential direction;

[0019] There are a plurality of gas outlets B of the gas channel, and the gas outlets B of the gas channel are arranged at equal intervals along the circumferential direction on the flame torch body.

[0020] Furthermore, the flame torch comprises an upper flame torch body and a lower flame torch body, and the upper flame torch body and the lower flame torch body are sealed with a tapered pipe thread.

[0021] Furthermore, the tooth tops and tooth bottoms of the flame torch upper body and the flame torch lower body are both arc-shaped;

[0022] The upper body of the flame torch and the lower body of the flame torch are sealed with a 55° tapered pipe thread, and the thread taper ratio is 1:16.

[0023] Furthermore, the adjustment hand wheel is arranged on the upper body of the flame torch, and the upper body of the flame torch is respectively provided with an oxygen inlet and a gas inlet, and the oxygen inlet and the gas inlet are respectively connected to the inlet end of the oxygen channel and the inlet end of the gas channel.

[0024] Furthermore, a first gas valve is provided at the oxygen inlet, and a second gas valve is provided at the gas inlet.

[0025] Furthermore, the flame torch is made of flavonoid material.

[0026] Furthermore, the inner diameter of the oxygen inlet is 8 mm.

[0027] Furthermore, the inner diameter of the gas inlet is 6 mm.

[0028] The plasma cutting torch described in the present invention is a cutting torch matched with the existing HRP800XD plasma power supply (the size and process parameters of the composite flame torch of other types of cutting torches vary accordingly).

[0029] Furthermore, the plasma cutting equipment includes oxygen and propane gas supply cylinders (gas tanks), as well as a needle valve gas control device to ensure stable combustion of the flame torch. Furthermore, the plasma cutting torch uses a high-grade cooling system, such as a high-power water cooler and a coolant with high thermal and chemical stability and a narrow boiling range.

[0030] Furthermore, the plasma cutting torch electrode, nozzle and protective cap should be replaced with copper accessories with better cooling effect.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The composite cutting torch of the present invention comprises a plasma cutting torch and a flame torch. The flame torch is coaxially sleeved outside the plasma cutting torch and can move up and down along the axis of the plasma cutting torch. The flame torch of the present invention has an external mixing structure, that is, the oxygen outlet and the fuel gas outlet do not intersect within the flame torch. The oxygen and fuel gas are not pre-mixed inside the cutting torch, but are mixed and burned in the atmosphere after being ejected from the flame torch nozzle. This structure is less susceptible to annealing and tempering, which helps protect the plasma cutting torch from burning. In addition, the high-speed ejection of oxygen within the channel has a cooling effect on the plasma cutting torch.

[0033] In the flame torch of the present invention, the angle between the axis of the oxygen outlet and the axis of the plasma cutting torch is 8°, and the angle between the axis of the gas outlet and the axis of the plasma cutting torch is 12°. Moreover, both the oxygen outlet and the gas outlet are inclined and point toward the axis of the plasma cutting torch. This structure is beneficial for improving the protection of the plasma cutting arc by the mixed gas and is beneficial for the heating effect of the workpiece being cut. The heating point of the flame and the workpiece should be as close as possible to the heating area (anode area) of the plasma arc and the workpiece. The distance between the flame torch and the plasma cutting torch can be changed for fine adjustment.

[0034] The present invention achieves the purpose of improving the cutting ability, cutting thickness and cutting quality of plasma equipment by sleeve-mounting a flame torch of corresponding size on an existing plasma cutting torch and coordinating with a composite heat source cutting process.

[0035] The composite cutting torch of the present invention can improve the cutting capacity and cutting thickness of existing plasma equipment, and can realize 360° circular cutting of 120-180mm thick stainless steel materials. It can solve the problem of insufficient cutting capacity of existing AP1000 nuclear power main pipelines and super pipelines, and has the advantages of good cutting surface quality, narrow cutting seam, and less cutting residue.

[0036] The composite cutting torch of the present invention can be used to solve the problems of insufficient cutting capacity of existing plasma power supplies and the inability to achieve technological breakthroughs in a short period of time. In particular, it is used in plasma cutting of thick-walled nuclear power pipelines. It provides the best plasma cutting equipment for the AP1000 nuclear power full series of thick-walled pipelines with 360° plasma high-efficiency and high-quality cutting in all positions.

[0037] The composite cutting torch of this invention is a new technology that complements the new "axial feeding-radial extrusion" process for nuclear power plants. By eliminating the cycles required for traditional forging and extrusion processes and comparing only machining cycles, plasma cutting significantly improves efficiency. For example, the AP1000 main pipeline undergoes a machining cycle of at least 150 days, while plasma cutting takes approximately 60 days (mass production requires no retraining, resulting in higher efficiency), a reduction of 90 days. Furthermore, the material utilization rate for machining is 18.3%, while that for plasma cutting is at least 50%, a threefold improvement over existing technologies.

[0038] The composite cutting torch of the present invention facilitates cutting and significantly reduces cutting costs compared to existing technologies. Stainless steel cutting tools are expensive, and due to the thick walls of nuclear power pipelines, cutting tools must be replaced frequently, resulting in significant costs. Low machining efficiency also results in significant time, labor, and material waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram of the overall structure of the composite cutting torch of the present invention;

[0040] Figure 2 This is a cross-sectional view of the structure of the composite cutting torch of the present invention;

[0041] Figure 3 It is a schematic structural diagram of the oxygen inlet and the fuel gas inlet of the composite cutting torch of the present invention;

[0042] Figure 4 It is a schematic structural diagram of the oxygen outlet and the fuel gas outlet of the composite cutting torch of the present invention;

[0043] Figure 5 It is a structural cross-sectional view of the oxygen outlet and the fuel gas outlet of the composite cutting torch of the present invention;

[0044] Figure 6 for Figure 5 A magnified view of the structure at point A;

[0045] Figure 7 This is a schematic diagram of the shape of the oxygen outlet of the composite cutting torch of the present invention;

[0046] Figure 8 This is a schematic diagram of the shape of the gas outlet of the composite cutting torch of the present invention;

[0047] Figure 9 This is a schematic diagram of the structure of the hand wheel in the composite cutting torch of the present invention;

[0048] Figure 10 Schematic diagram of groove cutting using the composite cutting torch of the present invention;

[0049] Figure 11 A schematic diagram of using the composite cutting torch of the present invention to cut a flat workpiece;

[0050] Figure 12 This is a schematic diagram of the all-position 360° plasma cutting equipment and supporting devices of the composite cutting torch of the present invention. DETAILED DESCRIPTION

[0051] As mentioned in the background, existing plasma cutting techniques can achieve 360° cutting at all positions within a certain thickness. However, when the thickness is too large, plasma power equipment cannot achieve this. Consequently, it cannot meet the full range of nuclear power pipeline manufacturing requirements using the new "axial feeding and radial extrusion" technology. Traditional "forging + machining" techniques, with their long production cycles, high energy consumption, and high costs, lack international competitiveness.

[0052] Based on the above, the present invention proposes a plasma-flame coaxial hybrid cutting torch for complex, thick-walled stainless steel pipe fittings for nuclear power plants. This technology, combined with flame coaxial cutting, enhances the plasma cutting capability and quality, achieving full-range thickness specifications for beveling thick-walled stainless steel pipe fittings for AP1000 nuclear power plants in my country. By integrating this technology with a robotic arm, it can achieve 360° cutting of complex, thick-walled stainless steel pipe fittings for nuclear power plants in all positions. This overcomes the limitations of existing high-power plasma cutting technologies, both domestically and internationally, and addresses the challenge of plasma beveling 80-120mm thick stainless steel for nuclear power plants in all positions, 360°.

[0053] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention. It should be noted that the plasma cutting torch used in the following embodiments of the present invention is the cutting torch that is compatible with the existing HRP800XD plasma power supply (the size and process parameters of the composite flame torch of other models of cutting torches will vary accordingly).

[0054] Example 1

[0055] See also Figure 1 and Figure 2 This embodiment provides a plasma-flame composite cutting torch for nuclear power thick-walled stainless steel complex pipe fittings, including a plasma cutting torch 1 and a flame torch 2. The flame torch 2 is coaxially sleeved on the plasma cutting torch 1, and the flame torch 2 can move up and down along the axial direction of the plasma cutting torch 1.

[0056] It should be noted that the plasma cutting torch 1 is a conventional plasma cutting torch 1, and its internal structure and working principle are the same as those of the conventional technology, so the present invention will not be described in detail here, and those skilled in the art should know it. Figure 1 As shown, the plasma cutting torch 1 includes an electrode 11, a conductive ring 12 is provided at the bottom of the electrode 11, and a nozzle 13 is provided at the lower end of the electrode 11, and a ceramic cap 14 is provided on the nozzle 13. The plasma arc is ejected by the nozzle 13 to achieve the cutting effect.

[0057] See also Figures 2 to 5 In this embodiment, the flame torch 2 is an external mixing flame torch 2. By respectively setting an oxygen channel 21 and a gas channel 23 in the flame torch 2, the oxygen channel 21 and the gas channel 23 exist independently of each other, and the gas outlet A22 of the oxygen channel 21 and the gas outlet B24 of the gas channel 23 are located on the same horizontal plane. The gas outlet A22 of the oxygen channel 21 and the gas outlet B24 of the gas channel 23 are both inclined and their bottoms point to the axis of the plasma cutting torch 1, so that the oxygen and gas introduced are not pre-mixed in the flame torch 2, but are transported synchronously to the gas outlet A22 of the oxygen channel 21 and the gas outlet B24 of the gas channel 23 through the oxygen channel 21 and the gas channel 23, so that the gas and oxygen meet at the gas outlet and mix and burn in the atmosphere.

[0058] In order to increase the flame burning length of the composite cutting torch and improve the effect of the composite cutting torch in use, in another preferred embodiment of the present invention, please refer to Figures 2 to 5, so that the oxygen channel 21 is arranged on the side of the flame torch 2 close to the plasma cutting torch 1, and the gas channel 23 is arranged on the side of the flame torch 2 away from the plasma cutting torch 1; and a plurality of gas outlets A22 of the oxygen channel 21 are provided, and the gas outlets A22 of the plurality of oxygen channels 21 are arranged on the flame torch 2 body at equal intervals along the circumferential direction; a plurality of gas outlets B24 of the gas channel 23 are also provided, and the gas outlets B24 of the plurality of gas channels 23 are also arranged on the flame torch 2 body at equal intervals along the circumferential direction, and in this embodiment, each oxygen outlet, and each The two are arranged obliquely and their bottoms point to the axis of the plasma cutting torch 1, so that after the flame torch 2 respectively introduces oxygen and fuel gas into the oxygen channel 21 and the fuel gas channel 23, the oxygen and fuel gas are not pre-mixed in the flame torch 2, and flow out through the oxygen channel 21 and the fuel gas channel 23 respectively and are ejected from the oxygen outlet and the fuel gas outlet respectively, thereby ensuring that the oxygen channel 21 and the fuel gas channel 23 do not intersect inside the flame torch 2, but are mixed and burned in the atmosphere after they are ejected from the oxygen outlet and the fuel gas outlet respectively, which is beneficial to increasing the flame burning length.

[0059] In order to further improve the effect of mixing oxygen and fuel gas, in another preferred embodiment of the present invention, please refer to Figure 5 The included angle between the axis at the gas outlet A22 of the oxygen channel 21 and the axis of the plasma cutting torch 1 is 8°, and the included angle between the axis at the gas outlet of the gas outlet channel and the axis of the plasma cutting torch 1 is 12°. This special angle setting can better mix the oxygen and gas, so that the flame gradually strengthens the protection of the plasma arc jet and can ensure the concentration of the heating area, thereby improving the cutting effect.

[0060] In order to increase the flame length and improve the protection effect on the plasma arc, in another preferred embodiment of the present invention, please refer to Figure 6 、 Figure 7 and Figure 8 The oxygen outlet and the gas outlet are both composed of a stable section and a diffusion section structure, that is, the outlet at the bottom of the channel is a slightly diffuse structure. Figure 7 It can be seen that the outlet A of the oxygen channel consists of a stable section A and a diffusion section A, and the diameter of the stable section A is 2.5 mm, the diffusion taper of the diffusion section A is 1.146%, and the diffusion length is 8 to 10 mm. Figure 8 As can be seen, the gas outlet B of the gas channel consists of a stabilizing section B and a diffusing section B. The diameter of the stabilizing section B is 2.5 mm, while the diffusing section B has a diffusion taper of 1.146% and a diffusion length of 12 to 16 mm. The structural arrangement of the oxygen and gas outlets in the present invention helps increase the flame length and protect the plasma arc.

[0061] To facilitate control of the flow rates of fuel gas and oxygen, achieving a preferred oxygen-to-fuel gas flow ratio of 3:1 within the flame torch 2, a first gas valve and a second gas valve are provided at the oxygen inlet 27 of the oxygen channel 21 and the gas inlet 28 of the gas channel 23, respectively. Optionally, the first and second gas valves of the present invention are needle-valve gas regulating devices. In this embodiment, the inner diameter of the oxygen inlet 27 is 8 mm, and the inner diameter of the gas inlet 28 is 6 mm.

[0062] In order to facilitate the flame torch 2 to move up and down along the axial direction of the plasma cutting torch 1, so that the vertical distance between the gas outlet A22 of the oxygen channel 21, the gas outlet B24 of the gas channel 23 and the nozzle of the plasma cutting torch 1 can be adjusted within the range of 10 to 20 mm, in another preferred embodiment of the present invention, please refer to Figure 9 A rack 3 is mounted on the plasma cutting torch 1 along its axis, and a handwheel mounting base 4 is provided on the flame torch 2. A handwheel 5 is mounted within the handwheel mounting base 4, and an axial elastic ring 6 is provided between the handwheel mounting base 4 and the handwheel 5. A gear 7 is coaxially fixed on the handwheel 4. The gear 7 is meshed with the rack 3 so that the flame torch 2 is coaxially arranged outside the plasma cutting torch 1. By rotating the handwheel 5, the handwheel 5 is displaced on the rack 3, thereby moving it up and down along the plasma cutting torch 1, thereby adjusting the distance between the flame torch 2 and the plasma cutting torch 1. The handwheel 5 can be replaced with other manual adjustment fixing mechanisms or electric mechanisms, as long as it can achieve the effect of the flame on the plasma arc being increased by a short distance (10 to 20 mm) along the plasma cutting torch 1. The handwheel 5 is a universal mechanical transmission device that serves to fine-tune the flame torch 2 up and down along the plasma cutting torch 1. Those skilled in the art should understand its working principle, so the present invention will not be described in detail here. In order to ensure the flame's increasing effect on the plasma arc, the vertical distance between the bottom of the gas outlet A22 and the gas outlet B24 and the nozzle 13 of the plasma cutting torch 1 is preferably adjusted to 13-17 mm by the hand wheel 5 .

[0063] In order to facilitate processing, in another preferred embodiment of the present invention, the flame torch 2 is made of brass (such as H90), see Figure 1To facilitate processing, this embodiment employs a split upper and lower structure. Specifically, the upper and lower flame torch bodies 25 and 26 are each made of brass, sealed with 55° tapered pipe threads, and the crests and roots are arc-shaped, with a thread taper ratio of 1:16. The adjustment handwheel is mounted on the upper flame torch body 25, which is also equipped with an oxygen inlet 27 and a gas inlet 28. The oxygen channel 21 and its multiple oxygen outlets, as well as the gas channel 23 and its multiple gas outlets, are located on the lower flame torch body 26. The oxygen inlet 27 and the gas inlet 28 are connected to the inlet end of the oxygen channel 21 and the inlet end of the gas channel 23, respectively.

[0064] It should be noted that when cutting, the nozzle height of the compound cutting torch is based on the height of the nozzle 13 of the plasma cutting torch (that is, the height between the gas outlet of the plasma cutting torch 1 and the upper surface of the workpiece), which is the same as the nozzle height when cutting with a single plasma cutting torch 1 in the prior art, so it will not be repeated here, and those skilled in the art should know it.

[0065] When using the composite cutting torch of the present invention for cutting, first, according to the actual needs, Figure 10 or Figure 11 Adjust the nozzle height (d, the distance between the gas outlet of plasma cutting torch 1 and the upper surface of the workpiece). If the workpiece to be cut has a groove structure, follow Figure 10 Adjust the nozzle height d. If the workpiece to be cut is a flat structure, follow Figure 11 Adjust the nozzle height d. In addition, according to Table 1, adjust the corresponding nozzle height according to the actual thickness of the workpiece to be cut.

[0066] Table 1 Thickness of some materials and nozzle height

[0067]

[0068] After adjustment, follow Figure 12 As shown, connect all the equipment, then start the flame torch 2, open the second gas valve set on the gas inlet to let the gas in, observe the pressure gauge in the gas regulating device and adjust the gas pressure to 0.2~0.4MPa according to the cutting thickness. The gas regulating device here is Figure 12 The supporting devices of the flame torch 2 oxygen and fuel gas cylinders in the equipment (if the distance is short, there is no need to set up a separate gas regulating device, and the cylinder pressure reducing valve can be directly adjusted to read the cylinder pressure gauge value) are not related to the composite cutting torch of the present invention. They are common devices in the thermal cutting industry and will not be described in detail here. Those skilled in the art are aware of them.

[0069] After opening the second air valve and adjusting the pressure, open the first air valve set on the oxygen inlet and adjust the pressure of the oxygen introduced from small to large (0.4~0.7MPa) to adjust the flame to a neutral flame or a weak oxidizing flame. Adjust the upper and lower positions of the flame torch 2 so that the end of the flame converges on the upper surface of the workpiece. After the flame stabilizes, start the plasma cutting program immediately and cut according to the path and process set in the original cutting program.

[0070] After starting the plasma cutting torch 1, the high-power plasma arc jet is compressed and ejected at high speed through the nozzle of the plasma cutting torch 1. When leaving the nozzle, it interacts with the surrounding cold air to produce a shock wave phenomenon, causing the arc column to expand, the kinetic energy of the plasma to be converted into internal energy, the speed to drop rapidly, the power density to decrease, and the impact force of the plasma arc jet to decrease; at this time, the coaxial flame heat source attached to the flame torch 2 provides "annular protection" for the plasma arc (such as Figure 11 As shown in the figure, the plasma arc is isolated in the center of the flame and heat energy is provided; thereby reducing the heat exchange between the plasma arc and the air, reducing the resistance of the plasma jet, weakening the energy loss of the plasma arc jet due to the shock wave phenomenon, and improving the energy flow density of the plasma arc jet, so that the energy of the ion arc jet is more concentrated and the impact force is greater. Therefore, the setting of the flame torch 2 in the compound cutting torch can improve the capabilities of the existing plasma cutting power supply and cutting torch by improving the capacity and speed of the plasma arc jet.

[0071] Furthermore, the coaxial combination of the oxygen-flame heat source in flame torch 2 reduces the temperature difference along the thickness of the cut during cutting, shortens the cooling time difference along the thickness of the cut, makes the temperature more uniform across the thickness of the cut, increases the "penetration" of the cut, and reduces thermal cracking during stainless steel cutting, thereby improving the capability and quality of plasma cutting of medium and thick plate. Furthermore, the velocity and impact force of the plasma arc jet depend on the electric field strength and current density field. The motion of charged particles in the plasma arc is actually thermal motion under the combined action of electric field forces, thermal expansion forces, and self-magnetic compression forces. The additional flame heat source enhances thermal motion, changes various properties of the jet particles, and improves the fluidity of the molten metal. Therefore, the provision of flame torch 2 in the composite cutting torch can further enhance the capability, quality, and cutting speed of plasma cutting by supplementing the heat source, enhancing the characteristics of plasma activity, and improving the flow of the molten metal.

[0072] It should be noted that when the composite cutting torch of the present invention is used for cutting, the composite cutting torch of the present invention can be placed on any walking mechanism. In this embodiment, the composite cutting torch is connected to the inverted robot arm 9 at the lower end of the gantry frame column 8, as shown in FIG. Figure 12As shown, the plasma cutting torch 1 is connected to the plasma power supply 10, the flame torch 2 is connected to the oxygen source 101 and the gas source 102, and the robot arm 9 is electrically connected to the robot control cabinet 103. According to the actual cutting requirements, the robot arm 9 is controlled by the robot control cabinet 103 to move, thereby achieving full-position cutting of complex thick-walled stainless steel pipe fittings for nuclear power plants. This invention does not involve the actuator used in plasma cutting; stable and reliable operation is sufficient, which is known to those skilled in the art and will not be described in detail here.

[0073] Experimental part

[0074] The present invention uses the composite cutting torch to cut nuclear power stainless steel 316LN. Analysis shows that the cut nuclear power stainless steel 316LN material is 023Cr17Ni12Mo2N, and the thickness of the material is 180 mm.

[0075] During testing, the composite cutting torch described above was used as the cutting torch. The angle between the axis of the oxygen outlet and the axis of the plasma cutting torch 1 was 8°, and the angle between the axis of the gas outlet and the axis of the plasma cutting torch 1 was 12°. This structure improves the protection of the plasma cutting arc by the mixed gas and facilitates heating of the workpiece. The heating point between the flame and the workpiece should be aligned as closely as possible with the heating area (anode region) between the plasma arc and the workpiece. Fine-tuning the distance between the flame torch 2 and the plasma cutting torch 1 can be achieved by adjusting the distance. Each oxygen outlet and gas outlet was designed and machined into a bottom-diffusing structure. The inlet diameter of each oxygen outlet and gas outlet was 2.5 mm, the diffusion taper was 1.146%, and the diffusion section length was 8 mm.

[0076] The process specifications for cutting using the composite cutting torch of the present invention are as follows:

[0077] The inlet pressure of oxygen introduced from the oxygen inlet is 0.7 MPa;

[0078] The oxygen flow rate out of the oxygen outlet is 1.5Nm 3 / h;

[0079] The inlet pressure of propane gas introduced from the gas inlet is 0.4MPa;

[0080] The propane gas flow rate out of the gas outlet is 0.5Nm 3 / h;

[0081] The cutting speed using the above cutting torch and process specifications is 80mm / min (vertical cutting). Note: If 360° cutting is required, the cutting speed needs to be reduced according to the process specifications. The horizontal cutting speed is about 75mm / min, and the vertical upward cutting speed is about 60mm / min. During cutting, the cutting torch cutting speed and angle should be adjusted linearly and smoothly by the control program.

[0082] The plasma gas is H35 (H2-35%, Ar-65%), and the flow rate is adjusted to 4.2m 3 / h;

[0083] The protective gas is N2, and the flow rate is adjusted to 4.26m 3 / h;

[0084] The arc voltage is adjusted to 233V and the current is 800A;

[0085] The nozzle height is adjusted to 12.5 mm and the cutting speed is 80 mm / min. (Other parameters of the plasma cutting process are adjusted according to existing processes or operating manuals, which should be known to those skilled in the art and will not be described in detail in this invention.)

[0086] The material cutting is completed, the cutting section is smooth, without slag, and is a high-quality section.

[0087] Obviously, the above 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 making creative work are within the scope of protection of the present invention.

Claims

1. A plasma-flame composite cutting torch for nuclear power thick-walled stainless steel complex pipe fittings, characterized in that: The invention comprises a plasma cutting torch (1) and a flame torch (2), wherein the flame torch (2) is coaxially sleeved outside the plasma cutting torch (1), and the flame torch (2) can move up and down along the axial direction of the plasma cutting torch (1); The flame torch (2) is provided with an oxygen channel (21) and a gas channel (23) that are independent of each other, and the gas outlet A (22) of the oxygen channel (21) and the gas outlet B (24) of the gas channel (23) are located on the same horizontal plane; and the vertical distances between the bottoms of the gas outlet A (22) and the gas outlet B (24) and the nozzle (13) of the plasma cutting torch (1) are both 10 to 20 mm; The gas outlet A (22) and the gas outlet B (24) are both composed of a stabilizing section structure and a diffusion section structure, and are both diffusion-type structures; and the gas outlet A (22) and the gas outlet B (24) are both inclined, and the bottoms of the gas outlet A (22) and the gas outlet B (24) are both directed toward the axis of the plasma cutting torch (1); The gas outlet A (22) is composed of a stabilizing section A (221) and a diffusion section A (222), wherein the diameter of the stabilizing section A (221) is 2.5 mm, the diffusion taper of the diffusion section A (222) is 1.146%, and the diffusion length is 8 to 10 mm; The gas outlet B (24) is composed of a stabilizing section B (241) and a diffusion section B (242), wherein the diameter of the stabilizing section B (241) is 2.5 mm, the diffusion taper of the diffusion section B (242) is 1.146%, and the diffusion length is 12 to 16 mm; The angle between the axis of the gas outlet A (22) and the axis of the plasma cutting torch (1) is 8° to 12°; The angle between the axis of the gas outlet B (24) and the axis of the plasma cutting torch (1) is 12° to 16°.

2. The composite cutting torch according to claim 1, characterized in that: The oxygen channel (21) is arranged on a side of the flame torch (2) close to the plasma cutting torch (1), and the gas channel (23) is arranged on a side of the flame torch (2) away from the plasma cutting torch (1).

3. The composite cutting torch according to claim 1, characterized in that: There are a plurality of gas outlets A (22), and the gas outlets A (22) are arranged on the flame torch (2) body at equal intervals along the circumferential direction; A plurality of gas outlets B (24) are provided, and the plurality of gas outlets B (24) are arranged on the flame torch (2) body at equal intervals along the circumferential direction.

4. The composite cutting torch according to claim 1, wherein: The flame torch (2) comprises a flame torch upper body (25) and a flame torch lower body (26), and the flame torch upper body (25) and the flame torch lower body (26) are sealed by a tapered pipe thread.

5. The composite cutting torch according to claim 4, characterized in that: The top and bottom of the flame torch upper body (25) and the flame torch lower body (26) are both arc-shaped; The flame torch upper body (25) and the flame torch lower body (26) are sealed with a 55° tapered pipe thread, and the thread taper ratio is 1:

16.

6. The composite cutting torch according to claim 4, characterized in that: An oxygen inlet (27) and a fuel gas inlet (28) are respectively provided on the flame torch upper body (25), and the oxygen inlet (27) and the fuel gas inlet (28) are respectively connected to the inlet end of the oxygen channel (21) and the inlet end of the fuel gas channel (23).

7. The composite cutting torch according to claim 6, characterized in that: The oxygen inlet (27) is provided with a first gas valve, and the fuel gas inlet (28) is provided with a second gas valve.

8. The composite cutting torch according to claim 1, wherein: The flame torch (2) is made of brass.

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