Laser welding method for low-temperature heat-insulation gas cylinder

Abstract

The invention discloses a laser welding method for a low-temperature heat-insulation gas cylinder. The method comprises the following steps that a neck tube assembly is reassembled, the periphery of a supporting ring is sleeved with a reinforcing ring firstly, then the periphery of the supporting ring is sleeved with a supporting plate, the reinforcing ring is located on the inner side, and the supporting plate is located on the outer side; laser welding is adopted at the joint of the outer wall of the supporting ring and the inner diameter of the supporting plate, laser welding is adopted at the joint of the outer wall of the supporting ring and the inner side face of the reinforcing ring, and laser welding is adopted at the joint of the outer diameter of the reinforcing ring and the inner side face of the supporting plate; according to the laser welding mode, four points are symmetrically positioned and welded on each welding arc, and then full welding is carried out. The welding efficiency can be improved, the welding cost can be reduced, it can be guaranteed that weld joints are well formed, welding defects and welding deformation are reduced, and normal assembly of the supporting shaft and the supporting ring is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of welding, and in particular to a laser welding method for a low-temperature insulated gas cylinder. Background Art

[0002] The cryogenic insulated gas cylinder consists of an inner liner assembly, an outer cylinder, a front head assembly, a rear head assembly, a vacuum coating insulation layer between the inner liner and the outer shell, vacuum adsorption materials, inlet and outlet liquid pipelines and other components, such as Figure 1 As shown in the figure, the neck tube is an important component of the rear end of the shell, and its welding quality plays a vital role in the gas cylinder. The neck tube assembly includes a support ring 1, a reinforcement ring 2, a support plate 3, and a support shaft 4.

[0003] At present, argon arc welding is mostly used for welding in the production process of cryogenic insulated gas cylinders, such as Figure 2 As shown, the support ring 1 in the neck tube assembly is cylindrical, and the support plate 3 and the reinforcement ring 2 are both annular and are both welded onto the outer circumference of the support ring 1.

[0004] However, the use of argon arc welding for neck tube components often leads to the following technical problems: When using argon arc welding to weld the weld, it is necessary to first symmetrically position weld four points with a positioning weld arc length of 5 to 10 mm, then perform base welding, and finally cover the surface. This results in a large welding amount at the support ring 1, causing large welding deformation of the support ring 1. By measuring the post-weld dimensions of the support shaft 4 and the support ring 1, it was found that the welding deformation of the support ring 1 was 0.1 to 0.2 mm, while the welding deformation of the support shaft 4 was within 0.02 mm. Ultimately, the support shaft 4 and the support ring 1 are often unable to be assembled; Secondly, due to the large thickness of the neck tube assembly, if the heat input of argon arc welding is too large, there will be problems such as poor weld formation, gray and black weld appearance, and difficulty in ensuring good internal formation, which will affect the welding of the neck tube assembly; if the heat input of argon arc welding is too small, the neck tube assembly will be difficult to weld through, and the mechanical properties of the weld will be difficult to ensure; Third, when the neck tube assembly is welded by argon arc welding, it is generally necessary to weld the support ring 1 and the support plate 3, and to weld the support ring 1 and the reinforcement ring 2. However, the two welds often result in insufficient welding strength.

[0005] Fourth, the welding speed of argon arc welding is slow and the welding efficiency is not high; Fifth, the neck tube assembly must be processed by outsourcing before argon arc welding. The additional processing of the groove not only increases the process but also increases the cost. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the present invention proposes a laser welding method for low-temperature insulated gas cylinders, which not only improves welding efficiency, but also ensures good weld formation, reduces welding defects and welding deformation, and realizes normal assembly of the support shaft and support ring.

[0007] To achieve the above-mentioned object, the present invention provides a laser welding method for a cryogenic insulated gas cylinder, which is used for welding the neck tube assembly of the rear end cap of the shell. The method is particularly characterized in that it comprises the following steps: S1) Reassemble the neck tube assembly, first install a reinforcement ring on the outer periphery of the support ring, and then install the support plate, so that the reinforcement ring is located on the inner side and the support plate is located on the outer side; S2) Laser welding is used at the connection between the outer wall of the support ring and the inner diameter of the support plate, at the connection between the outer wall of the support ring and the inner side of the reinforcement ring, and at the connection between the outer diameter of the reinforcement ring and the inner side of the support plate; The laser welding method is to first perform symmetrical positioning welding on four points of each welding arc and then perform full welding.

[0008] Furthermore, in S1), before the neck tube assembly is reassembled, the support ring, the reinforcement ring, and the support plate need to be cleaned.

[0009] Furthermore, in S2), before laser welding, it is necessary to perform a self-inspection on the welding machine, clean the surface of the welding wire, and clean the area to be welded.

[0010] Furthermore, in S2), the self-check of the welding machine equipment includes checking whether each switch of the welding machine is turned to the correct position; checking whether the argon valve is open; turning on the welding machine, pressing the welding gun switch to measure the gas, and exhausting the air.

[0011] Furthermore, in S2), during the laser welding process, the arc length of each tack welding seam is 2 to 5 mm.

[0012] The advantages of the present invention are: 1. The present invention addresses the defects of argon arc welding technology and adopts laser welding to replace the original traditional argon arc welding for neck tube welding. The welding efficiency is improved by 2 to 3 times compared with argon arc welding.

[0013] 2. Reduce processes and reduce costs, as follows: ①When laser welding the neck tube assembly, there is no need to outsource the processing of the groove, which reduces the number of steps; ②Laser welding reduces the cost of equipment maintenance and wear compared to argon arc welding; ③ The shielding gas for laser welding can be nitrogen instead of argon. Compared with argon, nitrogen is cheaper. The price of nitrogen under the same specifications is only half of that of argon and it will not cause harm to the human body. ④ Laser welding has high power, high speed and low heat input. Nitrogen can play a better protective effect in high-power laser welding, which can avoid weld oxidation and workpiece deformation. ⑤ The laser welding cost of a set of neck tube components is 18.9 yuan, which is lower than the cost of argon arc welding of 19.25 yuan. The power of laser welding is 4.3kw, and the power of argon arc welding is 5.3kw. The welding time of argon arc welding is 2 to 3 times that of laser welding. The water and electricity consumption of a set of neck tube components is reduced by about 1.16 yuan. Therefore, the cost of using laser welding for a set of neck tube components is reduced by about 6.5 yuan compared with argon arc welding, which greatly reduces the manufacturing cost.

[0014] 3. It is beneficial to weld formation and welding quality, as follows: ① Due to the excessive heat input of argon arc welding, the support ring will be greatly thermally deformed after welding, which will affect the coaxiality of the support ring and the support shaft. Laser welding can reduce the thermal deformation of the support ring and realize the normal assembly of the support shaft and the support ring. ② When using argon arc welding to weld the neck tube assembly, there are problems such as poor weld formation, gray and black weld appearance, and difficulty in ensuring good internal formation. After switching to laser welding, the weld appearance is good, the back is welded through and has good formation. The process specifications strictly refer to the GB / T37778-2019 standard, and the radiographic inspection qualification level reaches Level II of the standard NB / T47013.2, and the technical level is AB.

[0015] The laser welding method of the low-temperature insulated gas cylinder of the present invention can not only improve welding efficiency and reduce welding costs, but also ensure good weld formation, reduce welding defects and welding deformation, and realize normal assembly of the support shaft and the support ring. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural diagram of a gas cylinder in the prior art; Figure 2 for Figure 1 A partial enlarged view of the middle neck tube assembly; Figure 3 It is a cross-sectional view of the assembly and welding of the neck tube assembly in the present invention; Figure 4 is a flow chart of the present invention; In the figure: support ring 1, reinforcement ring 2, support plate 3, support shaft 4. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention.

[0019] The assembly and welding cross-sectional view of the neck tube assembly in the prior art, such as Figure 2 As shown, the support ring 1 is cylindrical, and the reinforcement ring 2 and support plate 3 are both annular and welded to the outer circumference of the support ring 1. The support plate 3 is first placed on the outer circumference of the support ring 1, followed by the reinforcement ring 2, so that the support plate 3 is located on the inside and the reinforcement ring 2 is located on the outside. Prior art uses argon arc welding to weld the neck tube assembly, including two welds: one at the junction of the outer wall of the support ring 1 and the inner side of the support plate 3, and another at the junction of the outer wall of the support ring 1 and the inner diameter of the reinforcement ring 2. Using argon arc welding for these welds requires high current and heat input, which not only causes excessive thermal deformation of the support ring 1 during welding, but also lacks strength in both welds.

[0020] The present invention chooses to adopt a method of accelerating the welding speed to achieve the purpose of controlling welding deformation, and finally chooses to change the relevant process, that is, adopting a laser welding processing method that accurately controls welding deformation instead of argon arc welding.

[0021] like Figure 4 As shown, the present invention provides a laser welding method for a cryogenic insulated gas cylinder, which is used to weld the neck tube assembly of the rear head of the shell, comprising the following steps: S1) Reassemble the neck tube assembly, first sleeve the reinforcement ring 2 on the outer circumference of the support ring 1, and then sleeve the support plate 3, so that the reinforcement ring 2 is located on the inner side and the support plate 3 is located on the outer side.

[0022] Preferably, before reassembling the neck tube assembly, the support ring 1, the reinforcement ring 2, and the support plate 3 need to be cleaned.

[0023] Preferably, before laser welding, the welding machine needs to be self-checked, the surface of the welding wire needs to be cleaned, and the area to be welded needs to be cleaned.

[0024] The self-inspection of the welding machine equipment includes checking whether the switches of the welding machine are turned to the correct position; checking whether the argon valve is open; turning on the welding machine, pressing the welding gun switch to measure the gas, and exhausting the air.

[0025] Specifically, use industrial wipes dipped in alcohol or acetone to clean the surface of the welding wire, and use a stainless steel pneumatic wire wheel to clean the area of ​​the workpiece to be welded.

[0026] S2) Start the welding machine, set the welding current as required, and use laser welding at the connection between the outer wall of the support ring 1 and the inner diameter of the support plate 3, at the connection between the outer wall of the support ring 1 and the inner side of the reinforcement ring 2, and at the connection between the outer diameter of the reinforcement ring 2 and the inner side of the support plate 3.

[0027] In the present invention, the reinforcing ring 2 is clamped between the support plate 3 and the bottom of the support ring 1 for welding, that is, three-pass laser welding is performed, and the weld strength is sufficient.

[0028] The laser welding method is to first symmetrically position weld four points for each welding arc, and then perform full welding. Figure 2 In the argon arc welding, four points are symmetrically positioned and welded first, then the base is applied, and finally the surface is covered. The welding amount of laser welding is small and the welding efficiency is high.

[0029] In the prior art, if Figure 2 The outer diameter of the reinforcement ring 2 and the outer side of the support plate 3 are connected by argon arc welding. Due to the slow welding speed of argon arc welding and the large heat input at the same position, the support plate 3 is easily bent and deformed inward, which ultimately makes it impossible to assemble and weld the entire neck tube assembly with the rear head. Figure 2 The argon arc welding in the process can only weld two welds, and the two welds result in insufficient welding strength.

[0030] Therefore, the present invention first interchanges the assembly positions of the reinforcement ring 2 and the support plate 3. Then, in addition to the two welds, a weld is added where the outer diameter of the reinforcement ring 2 meets the inner side of the support plate 3. Because laser welding is fast and the heat input at the same location is low, not only does the support plate 3 not deform, but the three welds also increase the overall weld strength of the neck tube assembly.

[0031] Previously, the workshop used argon arc welding to manufacture a set of neck tube assemblies, which took 15 to 20 minutes. However, the welding method of the present invention only takes 5 minutes to weld a set of neck tube assemblies. In addition, laser welding does not require the welding tooling required for argon arc welding, and the efficiency is increased by 2 to 3 times compared with the original method.

[0032] Specifically, during the laser welding process, the arc length of each tack weld is 2 to 5 mm.

[0033] Since laser welding has strict requirements on the gap between welded parts, the neck tube assembly can be left without beveling, thus reducing the number of steps.

[0034] The laser welding method of the low-temperature insulated gas cylinder of the present invention can not only improve welding efficiency and reduce welding costs, but also ensure good weld formation, reduce welding defects and welding deformation, and realize normal assembly of the support shaft and the support ring.

[0035] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A laser welding method for cryogenic insulated gas cylinders, used for welding the neck tube assembly of the rear head of the shell, characterized in that: The steps include: S1) Reassemble the neck tube assembly, first sleeve the reinforcement ring (2) on the outer periphery of the support ring (1), and then sleeve the support plate (3), so that the reinforcement ring (2) is located on the inner side and the support plate (3) is located on the outer side; S2) Laser welding is used at the connection between the outer wall of the support ring (1) and the inner diameter of the support plate (3), laser welding is used at the connection between the outer wall of the support ring (1) and the inner side surface of the reinforcement ring (2), and laser welding is used at the connection between the outer diameter of the reinforcement ring (2) and the inner side surface of the support plate (3); The laser welding method is to first perform symmetrical positioning welding on four points of each welding arc and then perform full welding.

2. The laser welding method for cryogenic insulated gas cylinders according to claim 1, characterized in that: In S1), before the neck tube assembly is reassembled, the support ring (1), the reinforcement ring (2), and the support plate (3) must be cleaned and wiped clean.

3. The laser welding method for cryogenic insulated gas cylinders according to claim 2, characterized in that: In S2), before laser welding, the welding machine needs to be self-checked, the surface of the welding wire needs to be cleaned, and the area to be welded needs to be cleaned.

4. The laser welding method for cryogenic insulated gas cylinders according to claim 3, characterized in that: In S2), the self-test of the welding machine equipment includes checking whether the switches of the welding machine are turned to the correct position; checking whether the argon valve is open; turning on the welding machine, pressing the welding gun switch to measure the gas, and exhausting the air.

5. The laser welding method for cryogenic insulated gas cylinders according to claim 4, characterized in that: In S2), during the laser welding process, the arc length of each tack weld is 2~5mm.

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