Anti-backfire device and cutting torch

Abstract

The application discloses a backfire prevention device and a cutting torch. The backfire prevention device is applicable to the cutting torch and is arranged on one side of an air inlet end of a tail seat of the cutting torch. The backfire prevention device comprises a fireproof pipe, an input end connector and a one-way valve. The fireproof pipe is arranged in the tail seat and is arranged in an integrated mode with the tail seat. One end of the input end connector is connected with the fireproof pipe, and the other end of the input end connector is used for being connected with the one-way valve.

Description

Technical Field

[0001] This application relates to the field of cutting torch technology, and more specifically to an anti-backfire device and a cutting torch. Background Technology

[0002] Currently, in metal cutting operations, the cutting torch is the core tool, which requires the delivery of a mixture of oxygen and acetylene (or other fuel gas) for combustion and cutting. Backfire is a common safety hazard during the use of the cutting torch. If the backfire flame propagates backward to the oxygen or fuel gas storage container, it can easily cause an explosion. Therefore, backfire prevention devices have become an indispensable safety component in cutting torch operations.

[0003] Currently, the backfire prevention devices for conventional cutting torches on the market are all designed independently. This means that the backfire prevention device must be purchased separately by the user and assembled separately with the cutting torch. During the assembly process, multiple connection points are formed between the cutting torch and the flame arrestor, and between the flame arrestor and the gas pipeline. Each connection point has the risk of not being properly sealed, which significantly increases the probability of gas leakage. This can lead to fuel waste and safety accidents caused by leaked gas coming into contact with an open flame. On the other hand, the independent assembly method relies on the operator's manual operation. There is a possibility that the operator may neglect to install the backfire prevention device, leaving the cutting torch directly exposed to the risk of backfire, which seriously threatens operational safety. Utility Model Content

[0004] The purpose of this application is to provide a backfire prevention device and a cutting torch to reduce the risk of gas leakage at the connection between the backfire prevention device and the cutting torch, thereby improving the safety of cutting torch operations.

[0005] To achieve the above objectives, the technical solution adopted in this application is as follows: a backfire prevention device is provided, which is applicable to a cutting torch and is placed on the air inlet side of the tailstock of the cutting torch. The backfire prevention device includes: a flame arrestor tube, an input connector, and a one-way valve. The flame arrestor tube is placed inside the tailstock and is integrally formed with the tailstock. One end of the input connector is connected to the flame arrestor tube, and the other end is used to connect to the one-way valve.

[0006] As a preferred embodiment, the input terminal connector is provided with a first through hole and a second through hole that connect to the flame arrester. The first through hole and the second through hole are interconnected. The diameter of the first through hole is smaller than that of the second through hole to form an axial stepped structure. The second through hole is used to connect to the one-way valve.

[0007] As another preferred embodiment, the one-way valve includes an elastic element, an elastic element base, a steel ball, and a connector sleeve. The elastic element base is placed inside the second through hole to abut against the stepped structure between the first through hole and the second through hole. The connector sleeve has an opening, and one end of the connector sleeve is connected to the elastic element base, while the other end is used to connect to an external gas input device. The steel ball is housed in the connector sleeve, and the elastic element is disposed on the elastic element base, and always applies an elastic preload force toward the opening to the steel ball, so that the steel ball abuts against the opening to form a sealing pair.

[0008] Further preferably, the center of the connector sleeve is provided with an inner chamfer structure with a first tilt angle.

[0009] Preferably, the input terminal connector further includes a first connecting portion and a second connecting portion, the outer diameter of the second connecting portion is larger than the outer diameter of the first connecting portion, and the first connecting portion transitions to the second connecting portion through an axial step; the first connecting portion extends into the flame arrester tube to be interference-fitted with the flame arrester tube, and the second connecting portion is connected to the tailstock.

[0010] Preferably, the outer wall surface of the input terminal connector is provided with a limiting protrusion, and the input terminal connector is limited and abuts against the inner wall of the tailstock through the limiting protrusion.

[0011] Further preferably, it also includes a sealing ring, which is sleeved on the outer wall of the input terminal connector and located between the second connecting portion and the limiting protrusion. The sealing ring is used to seal and fill the gap between the tailstock and the input terminal connector.

[0012] Preferably, the backfire prevention device includes an oxygen flame arrester and a gas flame arrester that are independently arranged, and the oxygen flame arrester and the gas flame arrester have the same structure.

[0013] Furthermore, this application also provides a cutting torch, which includes a tailstock, a nozzle, and a gas supply pipe connecting the two. The gas supply pipe includes independent high-pressure oxygen pipe, heated oxygen pipe, and fuel gas pipe. The nozzle has a connecting cavity with multiple sets of axially spaced sealing surfaces for connecting different types of nozzles. The cutting torch also includes a backfire prevention device (as described above), integrally disposed within the tailstock. The cutting torch further includes a high-pressure oxygen quick-opening assembly, located at the top of the tailstock, for use with... Adjusting the high-pressure oxygen feed rate; the high-pressure oxygen quick-opening assembly includes a handle, a valve cover, a compression spring, a spring seat, and a quick-opening rubber-coated shaft. The valve cover is connected to the top of the tailstock. One end of the quick-opening rubber-coated shaft passes through the valve cover and extends into the tailstock to form a seal at the inlet end of the high-pressure oxygen tube. The other end of the quick-opening rubber-coated shaft is connected to the handle to form a lever structure outside the tailstock. An extension boss is provided on the side of the quick-opening rubber-coated shaft near the high-pressure oxygen tube. The spring seat is connected to the extension boss, and the compression spring is located between the spring seat and the valve cover.

[0014] Further preferably, the cutting torch also includes a gas regulating valve assembly connected to the tailstock. The gas regulating valve assembly is used to regulate the gas feed rate and includes a valve needle, a locking member, and an adjusting shaft. The adjusting shaft is connected to the tailstock, and the valve needle is connected to the adjusting shaft. The locking member is sleeved on the outer wall of the tailstock and has a stepped structure to stop the axial displacement of the adjusting shaft. The valve needle includes a tapered end, a middle section, and a tail section connected in sequence. The tapered end and the middle section are both placed in the valve cavity within the tailstock. The tapered end has a 6:1 taper and is used for sealing. The middle section is circumferentially locked to the valve cavity to restrict the circumferential rotation of the valve needle relative to the valve cavity. The tail section is rotatably connected to the adjusting shaft. By rotating the adjusting shaft, the valve needle is driven to move axially relative to the valve cavity to achieve sealing or opening of the valve body.

[0015] Compared with the prior art, the beneficial effects of this application are as follows: by designing the flame arrestor tube and the tailstock of the cutting torch as an integral part, the risk of leakage at the connection is reduced, and the possibility of the operator forgetting to install the flashback prevention device is also avoided. This facilitates regular inspection of the flashback prevention device and replacement of failed parts, thereby improving economic efficiency. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the backfire prevention device; Figure 2 for Figure 1 Side view of the structure of the anti-flashover device; Figure 3This is a schematic diagram of the input connector. Figure 4 This is a schematic diagram of a one-way valve. Figure 5 A schematic diagram of a three-barrel dual-purpose heavy-duty cutting torch; Figure 6 for Figure 5 Cross-sectional view of a triple-barrel dual-purpose heavy-duty cutting torch along the AA direction; Figure 7 This is a schematic diagram of another structure of a three-barrel dual-purpose heavy-duty cutting torch; Figure 8 A schematic diagram of the tailstock position of a three-barrel dual-purpose heavy-duty cutting torch; Figure 9 for Figure 8 Side view of the heavy tailstock position of a triple-barrel dual-purpose heavy cutting torch; Figure 10 This is a schematic diagram of the gas regulating valve assembly; Figure 11 This is a schematic diagram of the structure of a high-pressure oxygen quick-opening assembly; Figure 12 This is a structural diagram of the nozzle position in a three-barrel dual-purpose heavy-duty cutting torch. Figure 13 A schematic diagram of the structure for connecting the first type of gun nozzle to the gun head position connection part; Figure 14 A schematic diagram of the structure for connecting the second type of nozzle to the gun head position connection part; Figure 15 This is a schematic diagram of the structure of the first type of gun nozzle; Figure 16 This is a schematic diagram of the structure of the second type of gun nozzle.

[0017] In the diagram: 1. Heavy-duty cutting torch with three-tube dual-purpose design; 2. Nozzle; 10. Tailstock; 11. Valve chamber; 20. Nozzle head; 21. Connecting chamber; 211. First sealing surface; 212. Second sealing surface; 213. Third sealing surface; 22. First chamber; 23. Locking nut; 24. High-pressure oxygen gas zone; 30. Gas supply pipe; 31. High-pressure oxygen pipe; 32. Heated oxygen pipe; 33. Gas combustion pipe; 40. Type I nozzle; 41. Mixed gas annular chamber; 42. High-pressure oxygen straight-through chamber; 43. Cylindrical surface; 44. First inclined surface; 45. Second inclined surface; 50. Type II nozzle; 51. Third inclined surface; 60. Backfire prevention device; 61. Oxygen flame arrestor; 62. Gas flame arrestor; 621. Flame arrestor tube; 622. Input end connector; 6221. First through hole; 6222. Second through hole; 6223. First connecting part; 6224. External connector; 6225. Second connecting part; 6226. Limiting protrusion; 623. One-way valve; 6231. Connector sleeve; 6232. Inner chamfer; 624. Elastic element base; 625. Elastic element; 626. Steel ball; 627. One-way valve port; 63. Anti-loosening plate; 64. Sealing ring; 70. Gas regulating valve assembly; 71. Valve needle; 711. Conical end; 712. Middle section; 713. Tail end; 72. Locking element; 73. Adjusting shaft; 74. Handwheel; 75. Steel wire ring; 76. First sealing ring; 80. High-pressure oxygen quick-opening assembly; 81. Handle; 82. Valve cover; 83. Compression spring; 84. Spring seat; 85. Quick-opening rubber-coated shaft; 851. Extension boss; 852. Valve port; 86. Second sealing ring; 87. Third sealing ring; 88. Washer; 89. Elastic cylindrical pin; 90. Handheld position; 100. Heated oxygen regulating valve; 110. Decorative cover; 120. Solid metal rivet; 130. Machine-made rivet. Detailed Implementation

[0018] The present application will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0019] In the description of this application, it should be noted that the directional terms such as "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific protection scope of this application.

[0020] It should be noted that the terms "first," "second," etc., in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0021] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0022] In a preferred embodiment, see Figures 1 to 16 This application provides a backfire prevention device 60 and a cutting torch. The backfire prevention device 60 is applicable to a cutting torch, specifically a three-tube dual-purpose heavy-duty cutting torch 1. The three-tube dual-purpose heavy-duty cutting torch 1 includes: a tailstock 10, a torch head 20, and an air supply pipe 30 connecting the two. The air supply pipe 30 includes an independent high-pressure oxygen pipe 31, a heated oxygen pipe 32, and a gas combustion pipe 33. The cross-section of the three pipes is in a triangular structure, such as... Figures 5 to 7 As shown, high-pressure oxygen and heated oxygen flow into high-pressure oxygen pipe 31 and heated oxygen pipe 32 respectively along the X1 direction, and gas flows into gas pipe 33 along the X2 direction; that is, the anti-backfire three-pipe dual-purpose heavy-duty cutting torch 1 in this application adopts an isobaric structure. The gas and combustion-supporting gas required for heating the metal are sent to the torch head 20 through their respective metal pipes. The injection and adsorption mixing is carried out in the torch head 20. Since the injection and adsorption mixing occurs in the torch head 20, the mixed oxygen and gas are directly sprayed out from the nozzle, thereby reducing the probability of backfire.

[0023] The backfire prevention device 60 is located on the air inlet side of the tailstock 10 of the cutting torch. The backfire prevention device 60 includes: a flame arrestor tube 621, an input connector 622, and a one-way valve 623. The flame arrestor tube 621 is placed inside the tailstock 10 and is integrally formed with the tailstock 10. One end of the input connector 622 is connected to the flame arrestor tube 621, and the other end is used to connect to the one-way valve 623. By designing the flame arrestor tube 621 in the backfire prevention device 60 to be integral with the tailstock 10 of the cutting torch, the risk of leakage at the connection is reduced. At the same time, it also avoids the possibility that the operator will forget to install the backfire prevention device 60, which facilitates the regular inspection of the backfire prevention device 60 and the replacement of failed parts, thereby improving economic efficiency.

[0024] Meanwhile, the backfire prevention device 60 in this application is located on the side of the tailstock 10 of the cutting torch, that is, at the inlet end of oxygen, acetylene, or other fuels, and is not located in the oxygen and acetylene mixing pipeline. At the same time, in conjunction with the separately transported heated oxygen pipe 32 and gas pipe 33, the gas is mixed at the nozzle 20, thereby significantly improving the safety of the cutting torch.

[0025] Among them, the backfire prevention device 60 includes an oxygen flame arrester 61 and a gas flame arrester 62, which are independently set up. The oxygen flame arrester 61 and the gas flame arrester 62 have the same structure, and the only difference between them is the material and the air volume. The oxygen flame arrester 61 is set on the side corresponding to the high-pressure oxygen pipe 31 and the heated oxygen pipe 32, and the gas flame arrester 62 is set on the side corresponding to the gas pipe 33.

[0026] As a preferred embodiment, the input connector 622 is provided with a first through hole 6221 and a second through hole 6222 that connect to the flame arrester 621. The first through hole 6221 and the second through hole 6222 are interconnected. The diameter of the first through hole 6221 is smaller than that of the second through hole 6222 to form an axial stepped structure. The second through hole 6222 is used to connect to the one-way valve 623.

[0027] The input connector 622 also includes a first connecting part 6223 and a second connecting part 6225. The outer diameter of the second connecting part 6225 is larger than the outer diameter of the first connecting part 6223. Thus, the first connecting part 6223 transitions to the second connecting part 6225 through an axial step. The first connecting part 6223 extends into the flame arrester tube 621 to make an interference fit with the flame arrester tube 621. The second connecting part 6225 is connected to the tail seat 10. The outer wall of the second connecting part 6225 is specifically a threaded structure. Therefore, the first connecting part 6223 and the second connecting part 6225 respectively make an interference fit with the flame arrester tube 621 and make a threaded connection with the tail seat 10 to form a double fixed connection. The interference fit eliminates radial clearance and prevents lateral movement with radial clamping force. The threaded connection makes axial locking with axial preload force to prevent front and rear disengagement and effectively avoids the backfire prevention device 60 from shaking.

[0028] In a preferred embodiment, the gas flame arrestor tube 621 of the gas flame arrestor device 62 is made of sintered stainless steel with a filtration accuracy of 100µm (approximately 200 mesh). The gas flame arrestor tube 621 has a cylindrical structure with an inner surface area preferably of 11.8 cm². The flow velocity v is selected as 8 m / s, and the flow rate is selected as 50%, resulting in a permeable flow rate of 21.3 m³ / h for the gas flame arrestor tube 621. Since copper and its alloy particles have a catalytic decomposition effect on acetylene, stainless steel is selected to prevent the gas flame arrestor tube 621 from exploding. The oxygen flame arrestor tube 621 of the oxygen flame arrestor device 61 uses a lower-cost sintered copper filtration structure with a permeable flow rate as high as 20 m³ / h. 3 / h, filtration accuracy 150um, equivalent to 100 mesh. The hexagonal structure of the external connector 6224 of the input terminal connector 622 of the gas flame arrester 62 is engraved with a left-hand thread connection mark.

[0029] It should also be noted that the aforementioned metal flame-retardant pipes, including sintered metal parts, should be made from copper-free materials. At temperatures below 500℃, acetylene may explode and decompose in the presence of a catalyst. Copper, brass, silver, and other metals and metal oxides can all induce acetylene decomposition, acting as catalysts. The smaller the catalyst particles, the stronger their effect. Copper and its oxides are the most reactive substances in inducing the explosive decomposition of acetylene at lower temperatures. Therefore, acetylene equipment systems are not permitted to use copper sintered materials as flame-retardant materials; hence, the gas flame arrestor pipe 621 in this application is made of sintered stainless steel.

[0030] Therefore, taking the gas flame arrestor 62 as an example, the inner hole of the flame arrestor tube 621 in the gas flame arrestor 62 is connected to the first connecting part 6223 of the input terminal connector 622, and the two are interference fit. A stepped hole is provided at the center of the head of the input terminal connector, such as... Figure 3 As shown, the stepped holes specifically consist of a first through hole 6221 and a second through hole 6222. The diameter of the second through hole 6222 is larger than that of the first through hole 6221, and preferably 10 mm. A one-way valve 623 is installed inside the second through hole 6222. The one-way valve 623 specifically includes an elastic element base 624, an elastic element 625, a steel ball 626, and a connector sleeve 6231. The steel ball 626 is specifically a bearing steel ball 626. The elastic element base 624 is placed inside the second through hole 6222 to abut against the stepped structure between the first through hole 6221 and the second through hole 6222. The connector sleeve 6231 has an opening, and one end of the connector sleeve 6231 is connected to the elastic element base 624. The connector sleeve 6231 is located on the gas inlet side of the valve body of the one-way valve 623 for external connection. A gas input device, such as a gas input hose; a steel ball 626 is housed within a connector sleeve 6231, and an elastic element 625 is disposed on an elastic element base 624, and an elastic preload force is always applied to the steel ball 626 toward the opening, so that the steel ball 626 is pressed against the opening to form a sealing pair. By setting the steel ball 626, when the gas flow rate is large during use, the rotation of the steel ball 626 itself will not affect the spring, thereby effectively avoiding the situation in related technologies where the plug plate-type structure flips over and entangles the elastic element 625, causing failure.

[0031] Meanwhile, in related technologies, components such as sealing plates used to form sealing pairs are generally made of rubber. When backfire or abnormal combustion occurs, the instantaneous temperature may exceed 1500℃. Taking fluororubber with strong temperature resistance as an example, its high temperature resistance is 200~300℃, but it will also be affected by flames and high temperatures. The rubber material may soften or melt, deform, or experience a decline in physical properties, leading to device failure. However, the bearing steel balls used in this application, namely steel balls 626, will not experience this risk of decline in physical properties.

[0032] The elastic element base 624 is preferably a spring seat structure, and the elastic element 625 is a standard cylindrical compression spring structure. The connector sleeve 6231 has a through hole in its center. The center opening of the connector sleeve 6231 and the bearing steel ball 626 form a sealing pair. The length of this sealing surface shall not be less than 1 mm. The sealing surface needs to be formed by grinding, and the surface roughness shall not be less than Ra0.4. The colored area shall not be less than 40%, and there shall be no axial defects penetrating the colored part. After the sealing surface of the connector sleeve 6231 passes inspection, the bearing steel ball 626 with a diameter of 5 mm and the standard cylindrical compression spring are installed, and then the spring seat is tightened with the thread (M8).

[0033] The assembled one-way valve 623 is pressed into the second through hole 6222 of the input connector 622. The two are press-fitted, improving the seal between the one-way valve 623 and the input connector 622. Figure 4 As shown, the center of the connector sleeve 6231 is provided with an inner chamfer 6232 structure with a first inclination angle, preferably 60°, to form a conical connector sleeve 6231 structure, which facilitates the mating with the spherical connector of the external rubber hose connector. When the hexagonal locking nut on the external rubber hose connector is tightened with the thread of the external connector 6224 of the input end connector 622, it ensures that the connection is well sealed under a pressure of 2.5MPa. The center of the connector sleeve 6231 is provided with an internal thread (M6) to facilitate the installation and removal of the one-way valve 623. The assembled backfire prevention device 60 has a sealing ring 64 at the threaded connection between the input end connector 622 and the tailstock 10. The sealing ring 64 is a standard rubber sealing ring 64. Specifically, the sealing ring 64 is sleeved on the outer wall of the input end connector 622 and is located between the second connection 6225 and the limiting protrusion 6226. The sealing ring 64 is used to seal and fill the gap between the tailstock 10 and the input end connector 622, thereby achieving a seal between the backfire prevention device 60 and the tailstock 10.

[0034] Furthermore, the assembled gas flame arrestor 62 and oxygen flame arrestor 61 are screwed into the corresponding threaded holes of the tailstock 10 in sequence. The input end connector 622 is tightened through the threaded structure on the second connecting part 6225 and slightly adjusted so that the outer hexagon of the input end connector 622 is aligned with the two hexagonal holes of the connector anti-loosening plate 63. Then, the anti-loosening plate 63 is fixed to the tailstock 10 with screws. At this time, when installing or removing the external rubber hose, the input end connector 622 will not loosen and there will be no loosening phenomenon.

[0035] Specifically, the operation procedure of the anti-backfire device 60 is as follows: After connecting the rubber hose to the gas cylinder and pressure reducing valve, and connecting the other end of the rubber hose to the tailstock 10, and after checking the sealing and completing the preparations, ignite the cutting torch to begin operation. It is necessary to ensure that the torque of the elastic element 625 in the anti-backfire device 60 is sufficient to push open the bearing steel ball 626 when the external gas pressure is 0.04 MPa, and to meet the gas consumption requirements. When the external backfire gas flow occurs, because its pressure is much greater than 0.04 MPa, the bearing steel ball 626, under the dual action of the backfire gas flow and the compression and reset of the elastic element 625, immediately closes the one-way valve port 627, thereby preventing backfire.

[0036] Preferred, see Figures 1 to 3 The outer wall surface of the input end connector 622 is provided with a limiting protrusion 6226. The input end connector 622 is limited and abuts against the inner wall of the tail seat 10 through the limiting protrusion 6226, thereby further improving the connection stability between the input end connector 622 and the tail seat 10. At the same time, the limiting protrusion 6226 can also cooperate with the anti-loosening plate 63 to stop the axial movement of the input end structure.

[0037] In the three-tube dual-purpose heavy-duty cutting torch 1, the gas supply pipe 30 consists of three seamless stainless steel pipes with an outer diameter of 9.5mm. The high-pressure oxygen pipe 31, the heated oxygen pipe 32, and the gas pipe 33 are all 420mm long. One end of the gas supply pipe 30 is brazed to the corresponding mounting hole of the tailstock 10, and the other end is brazed to the corresponding mounting hole of the torch head 20, forming a triangular shape. For ease of handling, a handheld sleeve 90 is provided near the tailstock 10. The sleeve is made of non-ferrous metal H62 (copper) or 6061A (aluminum) profile, and the surface can be knurled in a striped or mesh pattern for an aesthetically pleasing appearance. The end of the tailstock 10 has a stepped structure that matches the inner diameter of the sleeve. The stepped structure provides positioning, and the two are further secured by solid metal rivets 120 to prevent displacement. The other end of the sleeve is provided with a bowl-shaped decorative cap 110, and the sleeve is fixed to the decorative cap 110 with a machine screw 130.

[0038] See Figures 12 to 16 The gun head 20 is provided with a connecting cavity 21 for connecting different types of nozzles 2. The connecting cavity 21 has multiple sets of sealing surfaces spaced apart along the axial direction. The nozzles 2 include a first type nozzle 40 and a second type nozzle 50. When the first type nozzle 40 is connected to the connecting cavity 21, at least two sets of sealing surfaces are adapted at the connecting surface. When the second type nozzle 50 is connected to the connecting cavity 21, at least one set of sealing surfaces is adapted at the connecting surface. The first type nozzle 40 is preferably as follows: Figure 15 The gas cutting nozzle shown, the second type of nozzle 50 is preferably a type such as... Figure 16 The welding nozzle shown is either a general-purpose third-party gas cutting nozzle or a third-party welding nozzle available on the market.

[0039] Preferably, the multiple sealing surfaces in this application include a first sealing surface 211, a second sealing surface 212, and a third sealing surface 213 distributed sequentially from top to bottom along the axial direction. The first sealing surface 211 is adjacent to the second sealing surface 212, and a transition area is provided between the second sealing surface 212 and the third sealing surface 213 to allow for spacing.

[0040] The first type of nozzle 40 is provided with a high-pressure oxygen direct passage chamber 42 and a mixed gas annular chamber 41; the connecting chamber 21 and the first type of nozzle 40 form a first chamber 22, which is connected to the mixed gas annular chamber 41. The first chamber 22 is used to heat the oxygen for heating transported in the oxygen pipe 32 and the gas transported in the gas pipe 33 to mix and spray out from the mixed gas annular chamber 41; the high-pressure oxygen direct passage chamber 42 is connected to the high-pressure oxygen pipe 31, and the high-pressure oxygen transported in the high-pressure oxygen pipe 31 enters the high-pressure oxygen gas area 24 and then sprays out from the high-pressure oxygen direct passage chamber 42.

[0041] In order to dissipate the radiant heat of the nozzle 2 as quickly as possible and keep its own temperature within an acceptable range, this embodiment uses... Figure 15 Taking the gas cutting nozzle shown as an example, the gas cutting nozzle is made of copper. The nozzle has a central through hole, which is the high-pressure oxygen direct-flow chamber 42. The diameter of this hole is proportional to the thickness of the metal plate being cut. Around the central hole, multiple evenly distributed small holes radiate outwards, forming the mixing gas annular chamber 41. Preferably, six such chambers are provided. The diameter of the small holes is related to the area being heated; the larger the diameter, the larger the area being heated. The gas cutting nozzle has at least two conical surfaces, namely a first inclined surface 44 and a second inclined surface 45. When the gas cutting nozzle is connected to the nozzle head 20, the first chamber 22 is located between the first inclined surface 44 and the second inclined surface 45. The lower end of the nozzle head 20 has an external thread, which, through a locking nut 23, connects the gas cutting nozzle to the nozzle head 20. After connection, the gas and heating oxygen can be fully mixed within the first chamber 22.

[0042] In actual manufacturing, due to the existence of manufacturing tolerances, it is almost impossible to make the first inclined surface 44 and the second inclined surface 45 simultaneously contact the two conical surfaces of the second sealing surface 212 and the third sealing surface 213, respectively. This is because when the first inclined surface 44 on the gas cutting nozzle is in complete contact with the second sealing surface 212, the second inclined surface 45 on the gas cutting nozzle will be restricted from moving, thus creating a gap.

[0043] Therefore, this application adds a first sealing surface 211 to the end of the nozzle 2. The first sealing surface 211 is a cylindrical sealing structure, that is, the outer diameter of the high-pressure oxygen inlet end of the original gas cutting nozzle is precision machined to form a cylindrical surface 43, which then makes an interference fit with the first sealing surface 211 at the high-pressure oxygen outlet of the nozzle head 20. The interference range is controlled within the elastic deformation range of the gas cutting nozzle metal to form a cylindrical sealing surface. Preferably, the length of the cylindrical sealing surface is controlled to be 2~3mm. If it is too short, it will not meet the sealing requirements. If it is too long, the mating surface will be difficult to separate when disassembling the gas cutting nozzle and the nozzle head 20.

[0044] Furthermore, during the actual assembly of the gas cutting nozzle and the nozzle head 20, it is essential to ensure that the conical third sealing surface 213 of the connecting cavity 21 of the nozzle head 20 is sealed and fitted with the second inclined surface 45 on the gas cutting nozzle. Otherwise, the mixture of heated oxygen and fuel gas in the first chamber 22 will leak and ignite upon contact with the open flame emitted from the ignited nozzle, which is unacceptable for welding and cutting processes and will result in a major safety accident. Therefore, when the cylindrical surface 43 in the gas cutting nozzle forms the first sealing surface 211 of the connecting cavity 21 of the nozzle head 20, the locking nut 23 on the nozzle head 20 is rotated further, thereby forcing the gas cutting nozzle to move axially upward until the third sealing surface 213 fits with the second inclined surface 45. Through the interference fit between the first sealing surface 211 and the cylindrical surface 43, combined with the fit between the third sealing surface 213 and the second inclined surface 45, the area of ​​heated oxygen and fuel gas mixture and the high-pressure oxygen area are completely isolated.

[0045] The second sealing surface 212 provided in the connecting cavity 21 of the nozzle 20 in this application is intended to allow the user to use a commercially available nozzle, such as a third-party gas cutting nozzle, to achieve a seal at the nozzle 2 through the universal second sealing surface 212, so that it can be used with difficulty, in case of emergency, thereby improving the applicability of the three-tube dual-purpose heavy-duty cutting torch 1 in this application.

[0046] Meanwhile, to facilitate the switching between gas cutting and welding, this application provides a second type of nozzle 50, such as... Figure 16 The welding nozzle 2 shown has a third inclined surface 51. When the welding nozzle 2 is connected to the connecting cavity 21 of the nozzle head 20, it is only necessary to replace the gas cutting nozzle with the welding nozzle 2. Figure 14 As shown, the welding nozzle 2 is provided with a third inclined surface 51 for fitting with the third sealing surface 213 on the connecting cavity 21 to form a seal. Similarly, the welding nozzle 2 is connected to the gun head 20 by locking the nut 23. Since high-pressure oxygen is not required during welding, there is only one mixed gas area chamber composed of heating oxygen and fuel gas between the gun head 20 and the welding nozzle 2.

[0047] Therefore, this application document, through differentiated configurations of multiple sets of sealing surfaces, enables the same nozzle head 20 to be compatible with first-type nozzles 40 and second-type nozzles 50, which have different structures and dimensions. The first-type nozzle 40 needs to be adapted to at least two sets of sealing surfaces to meet its functional requirements, such as the multi-port sealing requirements brought about by dual channels for high-pressure oxygen and mixed gas; the second-type nozzle 50 only needs to be adapted to at least one set of sealing surfaces, simplifying the connection structure of non-cutting nozzles 2, realizing multi-purpose use of one nozzle, eliminating the need to design nozzle heads 20 separately for different nozzles 2, and reducing equipment costs and operational complexity.

[0048] Due to differences in working pressure and medium characteristics among different nozzle types 2, such as gas cutting nozzles needing to withstand the dual pressure of high-pressure oxygen and mixed gas, while welding nozzles only require a mixed gas seal, a multi-set sealing surface design can provide graded sealing for nozzle type 2: the first type of nozzle 40 forms multiple barriers through two or more sets of sealing surfaces, effectively preventing high-pressure gas leakage; the second type of nozzle 50 can meet its sealing requirements under its working pressure with only one sealing surface, ensuring reliability while avoiding structural redundancy.

[0049] Combining the pressure-equalizing structure of the anti-backfire three-tube dual-purpose heavy-duty cutting torch 1 in this application, the gas and oxygen are mixed in the nozzle 20, and the heated oxygen forms a jet suction on the gas pipeline in the nozzle 20. With the help of multiple sets of sealing surfaces, the backfire propagation path can be further blocked. For the first type of nozzle 40 that needs to withstand higher pressure and mixed gas, the multiple sets of sealing surfaces reduce the amount of gas leakage at the connection through step-by-step sealing, thereby reducing the risk of flame entering the gas supply pipe 30 through the connection cavity 21 during backfire.

[0050] Further, see Figures 8 to 10 Both the oxygen heating regulating valve 100 and the gas regulating valve assembly 70 adopt a needle valve structure. To facilitate the operator's usage habits, two mutually perpendicular planes are arranged on the handheld position 90. The oxygen heating regulating valve 100 is located on the side of the operator, and the gas regulating valve assembly 70 is located below the operator.

[0051] Therefore, the three-tube dual-purpose heavy-duty cutting torch 1 in this application also includes a gas regulating valve assembly 70. The gas regulating valve assembly 70 is connected to the tailstock 10 and is used to regulate the gas feed rate. It includes a valve needle 71, a locking element 72, a handwheel 74, a wire ring 75, and an adjusting shaft 73. The locking element 72 is specifically a locking nut. The adjusting shaft 73 is connected to the tailstock 10, the valve needle 71 is connected to the adjusting shaft 73, and the locking element 72 is sleeved on the outer wall of the tailstock 10. The locking element 72 has a stepped structure to... The axial displacement of the stop adjustment shaft 73; the valve needle 71 includes a tapered end 711, a middle part 712 and a tail part 713 connected in sequence. The tapered end 711 and the middle part 712 are both placed in the valve cavity 11 in the tail seat 10. The tapered end 711 is used for sealing. The middle part 712 is circumferentially locked with the valve cavity 11 to restrict the circumferential rotation of the valve needle 71 relative to the valve cavity 11. The tail part 713 is rotatably connected to the adjustment shaft 73. By rotating the adjustment shaft 73, the valve needle 71 is driven to move axially relative to the valve cavity 11 to achieve sealing or opening of the valve body.

[0052] The oxygen heating regulating valve 100 is designed, manufactured, and installed according to the general needle valve structure, which will not be described in detail here. According to GB7899 "Gas Cylinder Pressure Regulators for Welding, Cutting and Similar Processes" 6.2.2, the design, processing, and assembly of acetylene pressure regulators should ensure that the outlet pressure does not exceed 0.15 MPa. Due to the low pressure, the general needle valve structure cannot meet the high flow rate requirements of heavy-duty cutting torches. Therefore, if it is necessary to cut through steel plates with a thickness of 250 mm or more, the needle valve structure must be innovatively adjusted. Simultaneously, due to the special chemical composition of the fuel gas, a fuel regulating valve assembly 70 needs to be specifically designed for low-pressure fuel gases such as acetylene. See [link to relevant documentation] for details. Figure 10 The structure is shown.

[0053] Specifically, one end of the valve needle 71 is provided with a standard left-hand thread (M5 left) which is connected to the internal thread of the adjusting shaft 73. The middle part 712 is specifically a hexagonal structure so as to cooperate with the hexagonal structure in the valve cavity 11 located in the corresponding position in the tailstock 10 to form a slide to restrict the rotation of the valve needle 71. The tail 713 of the valve needle 71 is connected to the adjusting shaft 73 by a thread, so that when the adjusting shaft 73 rotates, the valve needle 71 as a whole only moves axially and does not rotate.

[0054] Meanwhile, the tapered end 711 of the valve needle 71 is machined into a cone shape with a 6:1 taper (10°) and forms a sealing surface with the valve body located in the corresponding position inside the tailstock 10. The outer diameter of the large end of the tapered end 711 of the valve needle 71 is 3.2 mm and the total length is 3 mm. This is the key to ensuring that the needle valve can achieve the maximum flow rate when it is fully open relative to the valve body. The large end of the adjusting shaft 73 has an internal thread (M5 left) that connects to the tail 713 of the valve needle 71. The outer diameter of the large end has a groove for installing a sealing ring. The sealing ring is also a standard rubber sealing ring, which is located in the valve body gap corresponding to the sealing adjusting shaft 73 and the tail seat 10. The outer diameter of the small end of the adjusting shaft 73 has knurled straight lines. After the locking member 72 is correctly inserted, the handwheel 74 is press-fitted into the end of the adjusting shaft 73 with knurled straight lines. The locking member 72 has a through hole in the middle to facilitate the passage of the adjusting shaft 73. The internal thread of the locking member 72 is connected to the external thread located at the corresponding position of the tail seat 10 to restrict the axial displacement of the adjusting shaft 73.

[0055] Furthermore, a wire ring 75 is provided at the junction of the small end of the adjusting shaft 73 and the locking member 72. The wire ring 75 is open and warped, with a planar distance of approximately 1 mm between its beginning and end. Its function is to compensate for the space formed between the stepped structure on the adjusting shaft 73 that abuts against the wire ring 75 and the locking member 72 when the locking member 72 is fully tightened and contacts the threaded end face of the valve body located inside the tailstock 10. The handwheel 74 is made of non-ferrous metal profile with a striped multi-petal plum blossom pattern on its outer surface. The inner hole on its end face is interference-fitted with the knurled end of the adjusting shaft 73.

[0056] The valve body sealing surface within the tailstock 10 also features a 6:1 tapered bore. This sealing surface serves as the mating surface for the tapered end 711 of the valve needle 71. The tapered bore is precision reamed using a 6:1 special tapered reamer and then ground. A colorimetric inspection is performed on the tapered end 711 of the valve needle 71, ensuring that the colored area is not less than 40% and that there are no longitudinal defects penetrating the colored area. The lower end of the tailstock 10 has an external thread connecting to the locking element 72 at its relative mounting position, thereby limiting the displacement of the adjusting shaft 73. A steel wire ring 75 is also installed for compensation. Preferably, the threaded connection between the locking element 72 and the tailstock 10 is sealed with anaerobic sealant.

[0057] Further, see Figure 11The backfire-proof three-tube dual-purpose heavy-duty cutting torch 1 also includes a high-pressure oxygen quick-opening assembly 80, which is located on the top of the tailstock 10. The high-pressure oxygen quick-opening assembly 80 is used to adjust the high-pressure oxygen feed rate. The high-pressure oxygen quick-opening assembly 80 includes a handle 81, a valve cover 82, a compression spring 83, a spring seat 84, a second sealing ring 86, a third sealing ring 87, a washer 88, an elastic cylindrical pin 89, and a quick-opening rubber-coated shaft 85. The valve cover 82 is connected to the top of the tailstock 10. One end of the quick-opening rubber-coated shaft 85 passes through the valve cover 82 and extends into the tailstock 10 to form a seal with the air inlet end of the high-pressure oxygen tube. The other end of the quick-opening rubber-coated shaft 85 is connected to the handle 81 to form a lever structure outside the tailstock 10. The quick-opening rubber-coated shaft 85 has an extension boss 851 on the side near the high-pressure oxygen tube 31. The spring seat 84 is connected to the extension boss 851, and the compression spring 83 is located between the spring seat 84 and the washer 88.

[0058] The valve cover 82 is threadedly connected to the valve body located at the top of the tailstock 10. The seal is formed by a third sealing ring 87, which is a standard rubber sealing ring. The valve cover 82 has a stepped hole at its center. A standard metal washer 88 and a cylindrical compression spring 83 are installed at the larger end of the hole. A small hole near the top passes through a quick-opening rubber-coated shaft 85. The valve cover 82 and the quick-opening rubber-coated shaft 85 are sealed by a second sealing ring 86 located at the top of the small hole. The bottom of the quick-opening rubber-coated shaft 85 has a cylindrical extended boss 851. A spring seat 84 is placed on the top of the boss. The cylindrical part below the boss is wrapped with fluororubber and vulcanized to increase the connection strength. The fluororubber wrapping and the valve body inner cavity boss located at the top of the tailstock 10 form an elastic sealing surface. The cylindrical part at the top of the quick-opening rubber-coated shaft 85 has a groove, which is combined with the handle 81 to connect and open the quick-opening valve. The handle 81 is made of stainless steel and is streamlined. One end is hooked to the quick-opening rubber-coated shaft 85. It forms a lever by setting a fulcrum at the corresponding position on the top of the tailstock 10. The fulcrum shaft is realized by a standard elastic cylindrical pin 89, which is installed in the hole at the top of the tailstock 10. After all parts are adjusted, anaerobic sealant is applied to the threaded connection between the valve cover 82 and the tailstock 10 to seal it.

[0059] When using the high-pressure oxygen quick-opening assembly 80, simply press the handle 81 lightly. Under the combined action of oxygen pressure and the lever of the handle 81, the quick-opening valve assembly can be opened quickly and completely. To close, simply release the handle 81. Under the elastic reset action of the cylindrical compression spring 83, the quick-opening valve will be closed quickly and easily. It is very convenient to use and can achieve zero maintenance.

[0060] Seal the threaded outlet of nozzle 20 with a special plug, close the high-pressure oxygen quick-opening assembly, the heated oxygen regulating valve 100 and the gas regulating valve assembly 70, introduce 4MPa nitrogen into the gas inlet at the tail end of tailstock 10, open each gas circuit valve one by one, maintain pressure for 5 minutes to conduct a strength test, and pass if there is no deformation or abnormal noise during the test. Reduce the pressure to 2.5MPa, maintain pressure for 30 minutes to conduct a sealing test, and pass if there is no pressure drop at room temperature.

[0061] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims

1. A backfire prevention device, characterized in that, The backfire prevention device is applicable to cutting torches and is located on the air inlet side of the tailstock of the cutting torch. The backfire prevention device includes: Flame arrestor, inlet connector and check valve; The flame arrestor tube is placed inside the tailstock and is integrally formed with the tailstock. One end of the input connector is connected to the flame arrestor tube, and the other end is used to connect to the one-way valve.

2. The backfire prevention device as described in claim 1, characterized in that, The input terminal connector is provided with a first through hole and a second through hole that connect to the flame arrester. The first through hole and the second through hole are interconnected. The diameter of the first through hole is smaller than that of the second through hole to form an axial step structure. The second through hole is used to connect to the one-way valve.

3. The backfire prevention device as described in claim 2, characterized in that, The one-way valve includes an elastic element, an elastic element base, a steel ball, and a connector sleeve. The elastic element base is placed inside the second through hole to abut against the stepped structure between the first through hole and the second through hole. The connector sleeve has an opening, and one end of the connector sleeve is connected to the elastic element base, while the other end is used to connect to an external gas input device. The steel ball is housed within the connector sleeve, and the elastic element is disposed on the elastic element base, and an elastic preload force is always applied to the steel ball toward the opening, so that the steel ball is pressed against the opening to form a sealing pair.

4. The backfire prevention device as described in claim 3, characterized in that, The connector sleeve has an inner chamfer structure with a first tilt angle at its center.

5. The backfire prevention device as described in claim 1, characterized in that, The input terminal connector also includes a first connecting part and a second connecting part. The outer diameter of the second connecting part is larger than the outer diameter of the first connecting part, and the first connecting part transitions to the second connecting part through an axial step. The first connecting part extends into the flame arrester tube to make an interference fit with the flame arrester tube, and the second connecting part is connected to the tailstock.

6. The backfire prevention device as described in claim 5, characterized in that, The outer wall surface of the input terminal connector is provided with a limiting protrusion, and the input terminal connector is limited and abuts against the inner wall of the tailstock through the limiting protrusion.

7. The backfire prevention device as described in claim 6, characterized in that, It also includes a sealing ring, which is fitted onto the outer wall of the input terminal connector and located between the second connecting portion and the limiting protrusion. The sealing ring is used to seal and fill the gap between the tailstock and the input terminal connector.

8. The backfire prevention device as described in claim 1, characterized in that, The backfire prevention device includes an oxygen flame arrester and a gas flame arrester that are set up independently, and the oxygen flame arrester and the gas flame arrester have the same structure.

9. A cutting torch, characterized in that, The cutting torch includes a tailstock, a torch head, and an air supply pipe connecting the two. The air supply pipe includes an independent high-pressure oxygen pipe, a heated oxygen pipe, and a gas combustion pipe. The gun head is provided with a connecting cavity, and the connecting cavity is provided with multiple sets of sealing surfaces distributed at intervals along the axial direction for connecting different types of gun nozzles. The cutting torch further includes a backfire prevention device as described in any one of claims 1-8, wherein the backfire prevention device is integrally disposed within the tailstock; The cutting torch also includes a high-pressure oxygen quick-opening assembly, which is located on the top of the tailstock and is used to adjust the high-pressure oxygen feed rate. The high-pressure oxygen quick-opening assembly includes a handle, a valve cover, a compression spring, a spring seat, and a quick-opening rubber-coated shaft. The valve cover is connected to the top of the tailstock. One end of the quick-opening rubber-coated shaft passes through the valve cover and extends into the tailstock to form a seal at the air inlet of the high-pressure oxygen tube. The other end of the quick-opening rubber-coated shaft is connected to the handle to form a lever structure on the outside of the tailstock. The quick-opening rubber-coated shaft has an extended boss on the side near the high-pressure oxygen pipe. The spring seat is connected to the extended boss, and the compression spring is located between the spring seat and the valve cover.

10. The cutting torch as described in claim 9, characterized in that, The cutting torch also includes a gas regulating valve assembly, which is connected to the tailstock. The gas regulating valve assembly is used to regulate the gas feed rate and includes a valve needle, a locking element, and an adjusting shaft. The adjusting shaft is connected to the tailstock, the valve needle is connected to the adjusting shaft, the locking member is sleeved on the outer wall of the tailstock, and the locking member has a stepped structure to stop the axial displacement of the adjusting shaft. The valve needle includes a tapered end, a middle section, and a tail section connected in sequence. The tapered end and the middle section are both placed in the valve cavity within the tail seat. The tapered end has a 6:1 taper and is used for sealing. The middle section is circumferentially locked to the valve cavity to restrict the valve needle from rotating circumferentially relative to the valve cavity. The tail section is rotatably connected to the adjusting shaft. By rotating the adjusting shaft, the valve needle is driven to move axially relative to the valve cavity to achieve sealing or opening of the valve body.

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