Method for improving concentricity deviation in horizontal casing process of fluorine-doped quartz tube

Abstract

A method for improving process concentricity deviation in the horizontal casing process of a fluorine-doped quartz tube (1), comprising the following steps: preparation of a positioning assembly: welding a quartz ring (6) having a central hole (61) to a tail tube (3); etching of a fluorine-doped quartz tube (1): welding the tail end of the fluorine-doped quartz tube (1) to the quartz ring (6) in the positioning assembly, and etching the fluorine-doped quartz tube (1); treatment of an octagonal parent rod (2): cutting a groove (21) at one end of the octagonal parent rod (2), then welding an intake tube (4) to the end of the octagonal parent rod (2) having the groove (21), welding a handle rod (5) at the other end of the octagonal parent rod (2), and then burning the surface of the octagonal parent rod (2); assembly: horizontally inserting the octagonal parent rod (2) into the fluorine-doped quartz tube (1), and fixing the handle rod (5) welded on the octagonal parent rod (2) in the central hole (61) of the quartz ring (6) of the positioning assembly; secondary etching; and collapsing. The method can reduce the concentricity deviation between the octagonal parent rod (2) and the fluorine-doped quartz tube (1), and ensure that no impurity exists between the fluorine-doped quartz tube (1) and the octagonal parent rod (2), thereby effectively reducing the cladding loss.

Description

A method for improving the concentricity deviation of fluorine-doped quartz horizontal casing process Technical Field

[0001] The invention belongs to the technical field of optical fibers, and in particular relates to a method for improving the concentricity deviation of a fluorine-doped quartz tube horizontal casing process. Background Art

[0002] Nowadays, fiber lasers have been widely used in the field of industrial processing, in which optical fiber is the core component of the laser. At present, the optical fiber commonly used in fiber lasers is double-clad optical fiber, the inner cladding is pure quartz glass, and the outer cladding is a low-refractive index coating. The high refractive index difference between the inner cladding and the outer cladding is conducive to improving the absorption of pump light, and is mostly used in kilowatt-class lasers. However, with the increase in the output power of the laser, the coating of the outer cladding needs to withstand higher heat, which limits the increase in the output power of high-power optical fiber. The Chinese patent with publication number CN110187437A discloses a triple-clad fiber laser, which can solve the problem of poor working stability and low reliability of fiber lasers due to the use of double-clad passive optical fiber.

[0003] High-concentration fluorine-doped quartz tube sheathing is a process difficulty in the preparation of triple-clad optical fiber preform rods. The fluorine in the fluorine-doped layer is easily volatilized at high temperatures, and the gas generated by volatilization is easily retained between the fluorine-doped quartz layer and the octagonal mother rod, forming fluorine bubbles. After being drawn into optical fiber, the fluorine bubbles become scattering points and easily become damage points of the optical fiber under high-power conditions, thereby greatly reducing the power that the optical fiber can withstand. Chinese patent publication number CN111025459A discloses a high-concentration fluorine layer quartz tube sheathing rod method, specifically disclosing a solution for eliminating fluorine bubbles, which deposits a pure silicon layer before the sleeve collapses. The pure silicon layer deposition can be deposited in advance during the preparation of the fluorine-doped quartz tube, which can solve the problem of fluorine volatilization and bubble formation during high-temperature treatment.

[0004] Conventional quartz tube sleeves use a vertical sleeve process. However, vertical sleeves often use induction furnaces or resistance furnaces, and impurities at the interface between the quartz tube and the mother rod cannot be completely removed, and there is a large loss at both ends. The horizontal sleeve process for fluorine-doped quartz tubes also has a process difficulty, namely the large concentricity deviation between the octagonal mother rod and the fluorine-doped quartz tube. Chinese patent publication number CN111025459A proposes to pre-set a collapse support point on the fluorine-doped quartz tube before the octagonal mother rod and the fluorine-doped quartz tube collapse. This method ensures concentricity through the collapse support point, but the collapse support point is pre-fitted to the octagonal mother rod after sleeved and before collapse, making it difficult to ventilate and polish the inside of the fluorine-doped quartz tube. At the same time, the joint easily forms a mirror surface, and temperature changes during collapse can easily cause the joint to crack or even break.

[0005] Summary of the Invention

[0006] To solve the above technical problems, the purpose of the present invention is to provide a method for improving the concentricity deviation of the horizontal casing process of fluorine-doped quartz tubes. This method can reduce the concentricity deviation between the octagonal mother rod and the fluorine-doped quartz tube, ensure the concentricity of the optical fiber product, and ensure that there are no impurities between the fluorine-doped quartz tube and the octagonal mother rod, thereby effectively reducing the cladding loss.

[0007] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0008] A method for improving the concentricity deviation of a fluorine-doped quartz tube horizontal casing process comprises the following steps:

[0009] (1) Preparation of positioning assembly: Weld one end of a quartz ring with a center hole to the tail pipe, with the center of the quartz ring concentric with the center of the tail pipe, and the ring body of the quartz ring also has a vent hole;

[0010] (2) Etching of fluorine-doped quartz tube: welding the tail end of the fluorine-doped quartz tube to the quartz ring in the positioning assembly, and etching the inner wall of the fluorine-doped quartz tube;

[0011] (3) Octagonal mother bar processing: First, grooves are cut on the eight faces of one end of the octagonal mother bar. Then, the nozzle of the air intake pipe is welded to the end of the octagonal mother bar with the groove. The groove serves as a reserved air intake hole. A handle is welded to the other end of the octagonal mother bar. Then, the surface of the octagonal mother bar is burned to remove surface impurities.

[0012] (4) Assembly: Insert the octagonal mother rod processed in step (3) horizontally into the fluorine-doped quartz tube, and fix the handle rod welded on the octagonal mother rod into the center hole of the quartz ring in the positioning assembly to complete the horizontal assembly process of the fluorine-doped quartz tube and the octagonal mother rod. After assembly, weld the air inlet pipe to the head end of the fluorine-doped quartz tube;

[0013] (5) Secondary etching: Gas is introduced into the space between the fluorine-doped quartz tube and the octagonal mother rod through the gas inlet pipe and the groove of the octagonal mother rod to perform secondary etching. The introduced gas is discharged through the vent hole of the quartz ring;

[0014] (6) Collapse: Use a hydrogen-oxygen torch to heat the fluorine-doped quartz tube so that the fluorine-doped quartz tube collapses and wraps around the octagonal mother rod.

[0015] Furthermore, a pure silicon layer is pre-deposited on the inner wall of the fluorine-doped quartz tube.

[0016] Furthermore, the etching process of the fluorine-doped quartz tube in step (2) is as follows: a vent tube is welded to the head end of the fluorine-doped quartz tube, the tail end of the fluorine-doped quartz tube is welded to the quartz ring in the positioning assembly, 1000 sccm of oxygen, 500 sccm of helium, and 100 sccm of carbon tetrafluoride are introduced into the fluorine-doped quartz tube through the vent tube, and the pressure at the tail tube is controlled at about 85 Pa, heating is performed for etching, and after etching and cooling, high-pressure nitrogen is introduced through the center hole of the quartz ring for purging, and finally the vent tube is cut off.

[0017] Furthermore, in step (3), the distance between the welding point between the air inlet pipe and the octagonal mother rod and the groove is 0.5 cm.

[0018] Furthermore, the length of the handle bar is designed according to the total length of the fluorine-doped quartz tube and the quartz ring and the length of the octagonal mother bar.

[0019] Furthermore, in step (3), a hydrogen-oxygen high-temperature flame is used for burning, the burning temperature is 1900-2000° C., and the hydrogen-oxygen flow ratio is 2.5:1.

[0020] Furthermore, the secondary etching process of step (5) is as follows: 200 sccm of oxygen, 200 sccm of helium, and 100 sccm of carbon tetrafluoride are introduced through the air inlet pipe welded to the octagonal mother rod, and the pressure at the tail pipe is controlled at about 40 Pa. The gas passes through the groove of the octagonal mother rod and enters between the octagonal mother rod and the fluorine-doped quartz tube, and is heated for secondary etching. After the etching is completed, the exhaust gas is discharged through the vent hole on the quartz ring.

[0021] Furthermore, in step (6), the fluorine-doped quartz tube position corresponding to the welding point between the octagonal mother rod and the handle rod is first subjected to fixed-point collapse. After the fixed-point collapse is completed, the fluorine-doped quartz tube is gradually heated and collapsed along the length direction.

[0022] Furthermore, during the fixed-point collapse, oxygen was introduced through the air inlet pipe, the oxygen flow rate was 500 sccm, and the pressure at the tail pipe was 45 Pa.

[0023] Furthermore, in step (6), the hydrogen flow rate of the oxyhydrogen burner is 90-100 slm, and the moving speed of the oxyhydrogen burner is 2-5 mm / min.

[0024] Beneficial effects of the present invention:

[0025] The present invention welds the air inlet pipe to one end of the octagonal mother rod, welds the handle rod to the other end of the octagonal mother rod, welds a special positioning component to the tail end of the fluorine-doped quartz tube, and the quartz ring in the positioning component is concentric with the fluorine-doped quartz tube. When the octagonal mother rod and the fluorine-doped quartz tube are assembled, the handle rod is fixed to the center hole of the quartz ring, and the head end of the fluorine-doped quartz tube is welded to the air inlet pipe. This method can assemble and position the fluorine-doped quartz tube and the octagonal mother rod, ensuring that the fluorine-doped quartz tube and the octagonal mother rod are aligned. The rods are concentric, avoiding the problem of softening and twisting of the fluorine-doped quartz tube during collapse. At the same time, there is no need to set collapse support points on the fluorine-doped quartz tube in advance, avoiding the premature collapse of the existing mirror surface, and also avoiding the cracking of the mirror surface caused by temperature changes during collapse. In addition, due to the cooperation between the positioning component with the quartz ring and the handle rod, the octagonal mother rod will not shake due to high temperature softening when the fluorine-doped quartz tube is welded to the air inlet pipe, thereby ensuring the concentricity of the octagonal mother rod and the fluorine-doped quartz tube.

[0026] The present invention welds an air inlet pipe to an octagonal mother rod and one end of a fluorine-doped quartz tube, and respectively provides grooves on the eight faces of the octagonal mother rod. In this way, while the air inlet pipe and a positioning assembly having a quartz ring are used for assembly and positioning, ventilation can also be achieved by utilizing the grooves, so as to achieve secondary etching of the gap between the fluorine-doped quartz tube and the octagonal mother rod after assembly, thereby ensuring that there are no impurities between the fluorine-doped quartz tube and the octagonal mother rod and effectively reducing the optical fiber cladding loss. The air vents provided on the quartz ring can achieve exhaust, ensuring the progress of the secondary etching, and can discharge residual waste gas between the fluorine-doped quartz tube and the octagonal mother rod, thereby reducing the generation of fluorine bubbles. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG1 is a schematic structural diagram of a method for improving concentricity deviation of a fluorine-doped quartz tube horizontal casing process according to an embodiment of the present invention.

[0028] FIG2 is a schematic structural diagram of a quartz ring in an embodiment of the present invention.

[0029] FIG3 is a schematic structural diagram of a fluorine-doped quartz composite tube formed in the present invention.

[0030] FIG4 is a schematic diagram of the 1095 nm cladding loss of a fluorine-doped quartz composite tube formed according to an embodiment of the present invention.

[0031] FIG5 is a diagram showing the refractive index cross-sectional structure distribution of the fluorine-doped quartz composite tube formed after drawing according to an embodiment of the present invention.

[0032] In the figure, 1: fluorine-doped quartz tube; 2: octagonal mother rod, 21: groove; 3: tail pipe; 4: intake pipe; 5: handle; 6: quartz ring, 61: center hole, 62: vent hole. DETAILED DESCRIPTION

[0033] The technical solutions of the present invention are described clearly and completely below with reference to specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention.

[0034] As shown in FIG1 , the present invention provides a preferred embodiment of a method for improving the concentricity deviation of a fluorine-doped quartz tube horizontal casing process, which comprises the following steps:

[0035] (2) Preparation of the positioning assembly: Weld one end of a quartz ring 6 with a central hole to the tail pipe 3, with the center of the quartz ring 6 concentric with the center of the tail pipe 3. The inner diameter of the central hole 61 of the quartz ring 6 is 16 mm, and two 5 mm vent holes 62 are symmetrically provided on the ring body of the quartz ring 6. The specifications of the tail pipe 3 are an outer diameter of 40 mm and a wall thickness of 3 mm, and the tail pipe length is at least 500 mm.

[0036] (2) Etching of fluorine-doped quartz tube: The inner wall of the fluorine-doped quartz tube with a layer of pure silicon pre-deposited on the inner wall is etched in advance to remove impurities in the tube; specifically, the left end of the fluorine-doped quartz tube 1 with an outer diameter of 38 mm and an inner diameter of 30 mm is welded to a vent pipe, and the right end is welded to the quartz ring 6 in the positioning assembly, and then it is horizontally welded on an MCVD lathe; 1000 sccm (milliliters per minute) of oxygen, 500 sccm of helium, and 100 sccm of carbon tetrafluoride are introduced into the fluorine-doped quartz tube 1, and the pressure at the tail pipe is controlled at about 85 Pa, and the inside of the tube is etched cleanly at high temperature; the specific etching conditions are: etching temperature of 1750°C, hydrogen flow rate of 85 slm, and flame torch speed of 80 mm / min; while etching, the fluorine-doped quartz tube can be checked for fluorine bubbles generated at high temperature to prevent the subsequent fluorine-doped quartz tube from being scrapped due to excessive fluorine bubbles. After the cleanly etched fluorine-doped quartz tube is cooled, it is removed from the MCVD lathe. A high-pressure nitrogen gas tube is inserted into the center hole of the quartz ring of the special positioning component to purge it with high-pressure nitrogen. Then, the vent tube is cut off with a cutting machine. The purpose of venting at the tail end is to minimize the entry of impurities such as broken quartz slag. After treatment, the fluorine-doped quartz tube 1 is sealed with a film for standby use.

[0037] (3) Octagonal mother rod processing: First, cut 1 cm long grooves 21 on the eight faces of one end of the octagonal mother rod 2, then weld the mouth of the air inlet pipe 4 to the end of the octagonal mother rod 2 with the groove, and each welding point is 0.5 cm away from the groove; the groove 21 serves as a reserved air inlet hole; weld a handle 5 with a diameter of 15.4-15.6 mm and a length of at least 300 mm to the other end of the octagonal mother rod 2, and then use a high-temperature hydrogen and oxygen flame to burn the surface of the octagonal mother rod 2 to remove surface impurities; the burning temperature is 1900-2000 ° C, and the hydrogen and oxygen flow ratio is 2.5:1.

[0038] (4) Assembly: After the octagonal mother rod 2 processed in step (3) is fixed on the left chuck of the MCVD machine tool, the fluorine-doped quartz tube 1 with the tail pipe 3 and the quartz ring 6 is fixed on the right chuck of the machine tool, the octagonal mother rod 2 is horizontally inserted into the fluorine-doped quartz tube 1, and the handle rod 5 welded on the octagonal mother rod 2 is fixed in the center hole 61 of the quartz ring 6, completing the horizontal assembly process of the fluorine-doped quartz tube 1 and the octagonal mother rod 2. After assembly, the end of the air inlet pipe 4 is welded to the end of the fluorine-doped quartz tube 1. During welding, the handle rod 5 is matched with the center hole 61 of the quartz ring 6. The small gap of 0.2-0.3mm between the handle rod 5 and the center hole 61 of the quartz ring 6 ensures that the octagonal mother rod 2 and the fluorine-doped quartz tube 1 are on the same center line, thereby ensuring concentricity.

[0039] It should be noted here that the length of the handle rod is designed according to the total length of the fluorine-doped quartz tube and the quartz ring and the length of the octagonal mother rod to ensure that the handle rod can cooperate with the positioning assembly with the quartz ring, and after assembly, the left end of the fluorine-doped quartz tube can be abutted against the end of the intake pipe to facilitate welding.

[0040] (5) Secondary etching: Gas is introduced between the fluorine-doped quartz tube 1 and the octagonal mother rod 2 through the inlet pipe 4 and the groove 21 of the octagonal mother rod 2 to perform secondary etching. The introduced gas is discharged through the vent 62 of the quartz ring 6. The specific process of secondary etching is as follows: 200 sccm of oxygen, 200 sccm of helium, and 100 sccm of carbon tetrafluoride are introduced through the inlet pipe 4 welded to the octagonal mother rod 2, and the pressure at the tail pipe is controlled at about 40 Pa. The gas enters between the octagonal mother rod 2 and the fluorine-doped quartz tube 1 through the groove 21 of the octagonal mother rod 2, and is heated for secondary etching. The secondary etching temperature is 1850°C, the hydrogen flow rate is 80 slm, and the blowtorch speed is 50 mm / min. After the etching is completed, the exhaust gas is discharged through the vent 62 on the quartz ring 6. After the etching is completed, the heating is stopped and pure oxygen is introduced for 10 minutes to completely remove the carbon tetrafluoride in the tube.

[0041] (6) Collapse: Use a hydrogen-oxygen torch to heat the fluorine-doped quartz tube 1 so that the fluorine-doped quartz tube 1 collapses and wraps around the octagonal mother rod 2. During the collapse, first perform a fixed-point collapse on the position of the fluorine-doped quartz tube corresponding to the welding point between the octagonal mother rod 2 and the handle 5 (the position marked by A in the figure). After the fixed-point collapse is completed, gradually heat and collapse along the length direction of the fluorine-doped quartz tube 1 from right to left. During the fixed-point collapse, oxygen is introduced through the air inlet pipe 4, the oxygen flow rate is 500 sccm, and the pressure at the tail pipe is 45 Pa. During the collapse from right to left, the pressure at the air inlet pipe is 10 Pa. The pressure is controlled by PID. The use of positive pressure collapse can ensure that the thickness difference of the fluorine-doped layer of the fluorine-doped quartz tube after it is wrapped around the octagonal mother rod is small, ensuring that the outermost circle is circular. During the collapse process, the hydrogen flow rate of the hydrogen-oxygen torch is 90-100 slm, and the moving speed of the hydrogen-oxygen torch is 2-5 mm / min.

[0042] After the collapse is completed, the positioning assembly with the quartz ring, the air inlet pipe, and the handle are cut off, and the resulting fluorine-doped quartz composite tube is ground and polished to obtain the finished product shown in Figure 3. Figure 4 shows a schematic diagram of the 1095nm cladding loss of the fluorine-doped quartz composite tube formed in this embodiment; Figure 5 shows the refractive index profile structure distribution diagram of the fluorine-doped quartz composite tube formed in this embodiment after drawing. As can be seen from Figure 4, the cladding loss of the fluorine-doped quartz composite tube produced by the method of the present invention is relatively small, with the 1095nm cladding loss being around 5dB / km; at the same time, the concentricity deviation is relatively small, with the concentricity deviation between the octagonal mother rod and the fluorine-doped quartz tube being less than 2μm.

[0043] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0044] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for improving the concentricity deviation of the horizontal casing process of a fluorine-doped quartz tube, characterized in that, It includes the following steps: (1) Preparation of the positioning component: One end of a quartz ring with a central hole is welded to a tail pipe. The center of the quartz ring is concentric with the center of the tail pipe, and there are also vent holes on the ring body of the quartz ring; (2) Etching of the fluorine-doped quartz tube: The tail end of the fluorine-doped quartz tube is welded to the quartz ring in the positioning component, and the inner wall of the fluorine-doped quartz tube is etched; (3) Treatment of the octagonal mother rod: First, grooves are cut on the eight faces at one end of the octagonal mother rod, then the nozzle of the inlet pipe is welded to the end of the octagonal mother rod with grooves. The grooves serve as reserved air inlet holes. A handle rod is welded to the other end of the octagonal mother rod, and then the surface of the octagonal mother rod is burned to remove surface impurities; (4) Assembly: The octagonal mother rod processed in step (3) is horizontally inserted into the fluorine-doped quartz tube, and the handle rod welded to the octagonal mother rod is fixed in the central hole of the quartz ring in the positioning component to complete the horizontal assembly process of the fluorine-doped quartz tube and the octagonal mother rod. After assembly, the inlet pipe is welded to the head end of the fluorine-doped quartz tube; (5) Secondary etching: Gas is introduced between the fluorine-doped quartz tube and the octagonal mother rod through the inlet pipe and the grooves of the octagonal mother rod for secondary etching, and the introduced gas is discharged through the vent holes of the quartz ring; (6) Collapse: The fluorine-doped quartz tube is heated by a hydrogen-oxygen torch to make the fluorine-doped quartz tube collapse and wrap around the octagonal mother rod.

2. The method for improving the concentricity deviation of the horizontal casing process of a fluorine-doped quartz tube according to claim 1, characterized in that, A layer of pure silicon layer is pre-deposited on the inner wall of the fluorine-doped quartz tube.

3. The method for improving the concentricity deviation of the horizontal casing process of a fluorine-doped quartz tube according to claim 1, characterized in that, The etching process of the fluorine-doped quartz tube in step (2) is as follows: A vent pipe is welded to the head end of the fluorine-doped quartz tube, the tail end of the fluorine-doped quartz tube is welded to the quartz ring in the positioning component, 1000 sccm of oxygen, 500 sccm of helium, and 100 sccm of carbon tetrafluoride are introduced into the fluorine-doped quartz tube through the vent pipe, and the pressure at the tail pipe is controlled at about 85 Pa. Heating is carried out for etching. After etching and cooling, high-pressure nitrogen is introduced through the central hole of the quartz ring for purging, and finally the vent pipe is cut off.

4. The method for improving the concentricity deviation of the horizontal casing process of a fluorine-doped quartz tube according to claim 1, characterized in that, In step (3), the distance between the welding point between the inlet pipe and the octagonal mother rod and the groove is 0.5 cm.

5. The method for improving the concentricity deviation of the horizontal casing process of a fluorine-doped quartz tube according to claim 1, characterized in that, The length of the handle rod is designed according to the total length of the fluorine-doped quartz tube and the quartz ring and the length of the octagonal mother rod.

6. The method for improving the concentricity deviation of the horizontal casing process of a fluorine-doped quartz tube according to claim 1, characterized in that, In step (3), high-temperature hydrogen-oxygen flame is used for burning, the burning temperature is 1900 - 2000 °C, and the hydrogen-oxygen flow ratio is 2.5:

1.

7. The method for improving the concentricity deviation of the horizontal casing process of a fluorine-doped quartz tube according to claim 1, characterized in that, The secondary etching process in step (5) is as follows: 200 sccm of oxygen, 200 sccm of helium, and 100 sccm of carbon tetrafluoride are introduced through the inlet pipe welded to the octagonal mother rod, and the pressure at the tail pipe is controlled at about 40 Pa. The gas enters between the octagonal mother rod and the fluorine-doped quartz tube through the grooves of the octagonal mother rod, and heating is carried out for secondary etching. After the etching is completed, the waste gas is discharged through the vent holes on the quartz ring.

8. The method for improving the concentricity deviation of the horizontal casing process of a fluorine-doped quartz tube according to claim 1, characterized in that, In step (6), first, fixed-point collapse is carried out on the position of the fluorine-doped quartz tube corresponding to the welding point between the octagonal mother rod and the handle rod. After the fixed-point collapse is completed, step-by-step heating collapse is carried out along the length direction of the fluorine-doped quartz tube.

9. The method for improving the concentricity deviation of the horizontal casing process of a fluorine-doped quartz tube according to claim 8, characterized in that, During fixed-point collapse, oxygen is introduced through the inlet pipe, the oxygen flow rate is 500 sccm, and the pressure at the tail pipe is 45 Pa.

10. The method for improving the concentricity deviation of the horizontal casing process of a fluorine-doped quartz tube according to claim 8, characterized in that, In step (6), the hydrogen flow rate of the oxy-hydrogen torch is 90 - 100 slm, and the moving speed of the oxy-hydrogen torch is 2 - 5 mm / min.

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