Nylon gas cylinder liner laser welding structure and welding method

Abstract

The invention provides a nylon gas cylinder liner laser welding structure and welding method, and belongs to the technical field of gas cylinder liner manufacturing, the nylon gas cylinder liner laser welding structure comprises two half-piece type liners which are black on the left and transparent on the right, and the right side end face of each black half-piece type liner is a plane or a non-plane; a sharp ring is integrally arranged on the right side end face of the welding ring; a groove matched with the right side end face, the welding ring and the sharp ring is formed in the left side end face of the transparent half-piece type liner. According to the structure and the method, a gas escape path is prolonged, stress is dispersed, multi-section welding is adopted, and the welding firmness of the two half-piece type inner containers is guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of gas cylinder liner manufacturing technology, specifically relating to a laser welding structure and welding method for a nylon gas cylinder liner. Background Technology

[0002] Currently, the mainstream manufacturing processes for gas cylinder liners are blow molding and injection molding. Blow molding allows for one-piece molding of the liner, offering advantages such as high molding efficiency and strong structural integrity. However, its core drawback is the potential for uneven wall thickness. Injection molding, on the other hand, employs a "split molding + welding integration" method. It first precisely manufactures two half-sheet liners using a mold, then uses laser welding technology to join them into a complete liner. Because the mold directly defines the liner's wall thickness, allowing for higher precision control, injection molding effectively solves the uneven wall thickness problem inherent in blow molding.

[0003] As shown in Figure 1, the traditional half-piece inner liner has a two-tone structure with a black left and a transparent right: the black half is black due to the addition of sufficient carbon, and the welding surfaces of both halves are designed as bevels. During single-point laser welding, the laser beam is perpendicular to the welding surface, penetrates the transparent half, and precisely acts on the bevel of the black half; the black half absorbs the laser energy and heats up rapidly, causing the bevels of both halves to melt synchronously, thus achieving welding and fixation. After the single-point welding is completed, the inner liner of the gas cylinder is simply rotated gradually around its own axis, with the operation of stopping and continuing the single-point welding in coordination. Once the inner liner has rotated completely around its own axis for one full revolution, the sealing welding of the entire circumference is completed.

[0004] As shown in Figure 2, based on the welding principle described above, when the laser beam irradiates the welding surface near the outer surface of the gas cylinder liner, the penetration depth of the transparent half-sheet liner is relatively shallow; however, when irradiating the welding surface near the inner surface of the liner, the penetration depth is much greater. This difference leads to a critical issue: in areas near the inner surface of the liner, the laser energy attenuates due to the longer penetration distance, resulting in poor welding performance; in areas near the outer surface, the laser energy is sufficient, leading to good welding performance. In factory filling and discharging tests, gas cylinder liners manufactured using this process, after approximately 10,000 filling and discharging cycles, are prone to detachment near the poorly welded inner surface, thus rendering the gas cylinder liner a defective product. Summary of the Invention

[0005] This invention proposes a laser welding structure and welding method for nylon gas cylinder liners, which can increase the connection strength of two half-piece liners at the welding surface.

[0006] To achieve the above objectives, the present invention proposes the following technical content: A laser-welded structure for a nylon gas cylinder liner includes two half-liners, one black and one transparent. The right end face of the black half-liner is either planar or non-planar. A welding ring is integrally formed on the right end face. The welding ring is circular and its axis coincides with the axis of the half-liner. A pointed ring is integrally formed on the right end face of the welding ring. When the right end face of the black half-piece inner liner is flat, the right end face of the black half-piece inner liner, the welding ring and the pointed ring form a whole A; the left end face of the transparent half-piece inner liner is provided with a groove A that fits the whole A. When the right end face of the black half-piece inner liner is not flat, the right end face of the black half-piece inner liner, the welding ring and the pointed ring form a whole B; the left end face of the transparent half-piece inner liner is provided with a groove B that fits the whole B; the two half-piece inner liners are laser welded into a complete nylon gas cylinder inner liner.

[0007] The structure of claim 1 includes a circular welding ring and a pointed ring. Compared to traditional single-plane / sloping-plane welding structures, the welding surface is no longer a simple single-layer bonding, but forms a composite contact interface of "outer circumferential surface of the welding ring + contour surface of the pointed ring," significantly increasing the fusion area of ​​laser welding. The larger fusion area geometrically increases the weld joint strength, effectively resisting the radial and axial stresses generated during the gas cylinder filling and discharging cycles, preventing weld cracking, and structurally ensuring the stability of the connection between the two half-liners. The welding ring is designed as a circular ring with its axis coinciding with the inner liner, ensuring that the force during welding is symmetrically distributed around the center of the inner liner, avoiding local stress concentration; the integral structure of the pointed ring and welding ring has no splicing gaps, reducing stress weak points. Even if the gas cylinder is under the dynamic load of high-pressure filling and discharging cycles for a long time, it can effectively disperse stress, improve the fatigue resistance of the overall structure, and extend its service life. The multiple tortuous structure blocks gas permeation. This design requires gas to take a longer path along the tortuous interface if it wants to escape from the weld, significantly increasing the gas permeation resistance and significantly reducing the risk of leakage compared to traditional structures.

[0008] Furthermore, when the right end face of the black half-piece inner liner is not planar, the nylon cylinder inner liner is cut open along the axis of the nylon cylinder inner liner for observation. On a single side wall thickness, the right end face of the black half-piece inner liner is trapezoidal, with the narrower bottom edge facing to the right and the wider bottom edge facing to the left, and the narrower bottom edge completely coincides with the left side of the welding ring.

[0009] Compared to the double-zigzag interface of "planar end face + welding ring + pointed ring" in claim 1, this solution forms a triple-zigzag bonding interface through "trapezoidal end face + welding ring + pointed ring"—the wide base of the trapezoid faces left and the narrow base faces right. Combined with the radial extension of the welding ring and the triangular contour of the pointed ring, the weld surface forms a continuous zigzag structure of "trapezoidal transition with a wider left side and a narrower right side + annular step + pointed protrusion." For gas to permeate from the weld, it must successively bypass the two waist surfaces of the trapezoid, the inner and outer surfaces of the welding ring, and the contour surface of the pointed ring. The escape path length is significantly increased compared to the planar end face structure, and the permeation resistance is geometrically increased. This is particularly suitable for high-pressure, high-frequency charge-discharge, or long-term use scenarios, resulting in superior sealing reliability.

[0010] Furthermore, by dissecting the nylon cylinder liner along its axis, it can be observed that on one side of the wall, the pointed ring is an isosceles triangle, with the base of the pointed ring completely coinciding with the right side of the welded ring. When the right end face of the black half-piece liner is trapezoidal, the inner and outer sides of the trapezoid are parallel to the inner and outer sides of the pointed ring, respectively.

[0011] Simultaneous laser irradiation enables the trapezoidal outer waist and the pointed outer waist to be fused together at the same time, forming a continuous double sealing structure of "trapezoidal outer waist sealing strip + pointed outer waist sealing strip". With the parallel tortuous paths of the two, gas must break through two uniformly fused sealing strips at the same time when escaping, and the permeation resistance is increased geometrically. Compared with the discontinuous sealing surface of asynchronous welding, the risk of leakage is greatly reduced.

[0012] Furthermore, by dissecting the nylon cylinder liner along its axis, it can be observed that, on a single side wall thickness, the welded ring is closer to the inner wall of the half-piece liner and farther from the outer wall.

[0013] During the filling and emptying of gas cylinders, the stress distribution on the inner liner wall exhibits a "greater stress on the outer wall than the inner wall" characteristic—under high pressure, the inner liner expands radially, and the tensile stress on the outer wall is more significant. Positioning the welding ring closer to the inner wall keeps the weld (the fusion area between the welding ring and the transparent half-piece) away from the stress-concentrated outer wall side, preventing the weld from directly bearing the maximum tensile load and significantly reducing weld fatigue damage. Simultaneously, the small distance between the welding ring and the inner wall allows for the structural support of the inner wall to disperse some stress, further reducing the risk of weld cracking and extending the service life of the inner liner.

[0014] Furthermore, when the right end face of the black half-piece inner liner is flat, a threaded pipe section is provided on the right end face of the black half-piece inner liner to replace the welding ring and the pointed ring; the inner diameter of the threaded pipe section is the same as the inner diameter of the black half-piece inner liner, the axis coincides with the axis of the gas cylinder inner liner, and the outer diameter is smaller than the outer diameter of the black half-piece inner liner; the left end face of the transparent half-piece inner liner is integrally provided with a threaded groove section that matches the above-mentioned threaded pipe section. After the threaded connection, the right end face of the black half-piece and the left end face of the transparent half-piece fit tightly together.

[0015] The screw-in structure of the threaded pipe section and the threaded groove section forms a "helical engagement." Compared with the pure welding reliance of "welded ring + pointed ring" in claims 1-3, the threaded connection can directly share the radial and axial pressure loads during the filling and discharging cycles of the gas cylinder, significantly reducing stress concentration in the weld. Especially in high-frequency filling and discharging or high-pressure scenarios, the mechanical load-bearing capacity of the thread can prevent fatigue cracking caused by long-term concentrated stress in the weld, significantly improving the fatigue resistance and service life of the overall structure.

[0016] A laser welding method for nylon gas cylinder liners includes the following steps: S1: Assemble the two half-piece inner liners into a complete nylon inner liner; S2: For the following three types of nylon cylinder liners—a black half-piece liner with an integral A on the right end, a black half-piece liner with an integral B on the right end, and a black half-piece liner with a threaded pipe section on the right end—adjust the direction of the laser beam to the radial direction of the nylon cylinder; the laser beam passes through the transparent half-piece liner and irradiates the outer circumferential surface of the welding ring or the outer circumferential surface of the threaded pipe section; under the irradiation time T of the laser beam, the outer circumferential surface of the welding ring or the threaded pipe section heats up, and the welding with the transparent half-piece liner is initially completed; the surface not directly irradiated by the laser beam is heated by the thermal conduction effect. S3: Rotate the nylon inner liner circumferentially by an angle R along the axis of the nylon inner liner to ensure that the areas covered by the two laser beams overlap. Repeat step S2 until the nylon inner liner has been completely rotated 360 degrees and the full circumference irradiation has been completed. Then, the outer circumferential surface of the welding ring or threaded pipe section is completely welded to the transparent half-piece inner liner. Turn off the radial laser beam. S4: For a nylon cylinder liner with an integral B on the right end of a black half-piece inner liner, the direction of the laser beam is adjusted to be perpendicular to both the outer waist surface of the pointed ring and the outer waist surface of the right end of the black half-piece inner liner; the laser beam passes through the transparent half-piece inner liner and irradiates the outer waist surface of the pointed ring and the outer waist surface of the right end of the black half-piece inner liner; under the laser irradiation duration T, the aforementioned waist surfaces heat up and initially complete the welding with the transparent half-piece inner liner; the surfaces not directly irradiated by the laser beam transfer heat through the thermal conduction effect. S5: Rotate the nylon liner around its axis by an angle R to ensure that the areas covered by the two laser beams overlap. Repeat step S4 until the nylon liner has rotated 360 degrees and completed full circumferential irradiation. Then turn off the laser beam in that direction. S6: For nylon cylinder liners with an integral A on the right end of a black half-piece inner liner or nylon cylinder liners with a threaded pipe section, adjust the direction of the laser beam to form a 45-degree angle with the right end face of the black half-piece inner liner; the laser beam passes through the transparent half-piece inner liner and irradiates the right end face of the black half-piece inner liner or the right end face of the threaded pipe section; under laser irradiation duration T, the aforementioned end face heats up and initially completes welding with the transparent half-piece inner liner; the surface not directly irradiated by the laser beam transfers heat through thermal conduction. S7: Rotate the nylon liner around its axis by an angle R to ensure that the areas covered by the two laser beams overlap. Repeat step S6 until the nylon liner has rotated 360 degrees and completed full circumferential irradiation. Then turn off the laser beam.

[0017] The beneficial effects that can be achieved by adopting the above technologies are: 1. Strong connection: By using a composite structure of welded ring + pointed ring or thread + weld, the welding contact area is increased, the load is distributed, stress concentration is reduced, fatigue resistance is improved, and weld cracking is avoided.

[0018] 2. It forms a tortuous / spiral gas escape path, combined with a gapless fit design, which increases resistance and provides double protection to reduce the risk of leakage, making it suitable for high-pressure and long-term use scenarios.

[0019] 3. Multi-segment welding securely welds the two half-piece inner liner pieces together. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the welding process for two existing half-piece inner liners. Figure 2 yes Figure 1 Enlarged view of point A in the middle; Figure 3 This is the connection structure of the two half-piece inner liners when viewed from the side wall after being cut open along the axis of the nylon gas cylinder inner liner in Example 1. Figure 4 This is the connection structure of the two half-piece inner liner when viewed from the side wall after being cut open along the axis of the nylon gas cylinder inner liner in Example 2; Figure 5 This is the connection structure of the two half-piece inner liner when viewed from the side wall after being cut open along the axis of the nylon gas cylinder inner liner in Example 3; Figure 6 These are three methods of radial laser irradiation in the inner lining of nylon gas cylinders; Figure 7 It is a black, half-piece nylon gas cylinder liner with a trapezoidal right end and a welding ring and a pointed ring, irradiated at an angle.

[0021] Figure 8 It is a black half-piece nylon cylinder liner with a flat right end and a welded ring, and a nylon cylinder liner with a threaded pipe section, shown in the diagram of a 45-degree laser irradiation method.

[0022] 1. Black half-piece inner liner; 2. Transparent half-piece inner liner; 3. Welded ring; 4. Pointed ring; 5. Threaded pipe section; 6. Threaded groove section. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1: As Figure 3 As shown, a laser-welded structure for a nylon gas cylinder liner includes two half-sheet liners, one black on the left and one transparent on the right.

[0025] The black half-piece inner liner 1 is made of PA10, with a flat right end face. An annular welding ring 3 is integrally formed on the right end face, with the axis of the welding ring 3 coinciding with the axis of the black half-piece inner liner 1. A pointed ring 4 is further integrally formed on the right end face of the welding ring 3, with the axis of the pointed ring 4 aligned with the axis of the welding ring 3. Viewed from the perspective of a nylon cylinder inner liner cut along its axis, the cross-sectional shape of the pointed ring is an isosceles triangle, and the base of this isosceles triangle completely coincides with the right side of the welding ring 3. The core reason for designing the pointed ring 4 as an isosceles triangle is to facilitate processing and forming.

[0026] The right end face of the black half-piece inner liner, the aforementioned welding ring 3, and the pointed ring 4 are considered as a single structure (hereinafter referred to as "integral A"). The left end face of the transparent half-piece inner liner 2 has a groove A that perfectly matches the shape of integral A. When the two half-piece inner liners are joined together to form a complete nylon gas cylinder inner liner, integral A can be perfectly embedded in the groove A, achieving precise positioning and fitting. The two half-piece inner liners are then laser-welded together.

[0027] Taking a nylon gas cylinder liner with a standard wall thickness of 4.5cm as an example (section view along the axial direction): the thickness of the welding ring 3 is 1.5cm (its own dimension along the radial direction of the gas cylinder liner), and its length along the cylinder axis is approximately 2cm, which reduces stress concentration on the outer wall; the welding ring 3 is generally close to the inner surface of the nylon gas cylinder liner, with a distance of 1cm between the welding ring and the inner wall of the gas cylinder, and a distance of 2cm between the welding ring and the outer wall of the gas cylinder (1cm + 1.5cm + 2cm = 4.5cm, perfectly matching the total wall thickness of the gas cylinder). The distance between the tip of the pointed ring 4 and the right end face of the welding ring is 1cm, that is, the height of the pointed ring in the isosceles triangular section is 1cm.

[0028] The principle behind the improved weld strength of the nylon gas cylinder in this embodiment is: 1. Significantly increased welding surface area: As can be seen from the axial section, the welding surface of this design is composed of a welding ring and a pointed ring, and its overall contact area is much larger than that of the single-bevel type welding surface in the background technology. The larger welding contact area results in a wider fusion area after laser welding, significantly improving the weld bonding strength and structurally ensuring the robust connection between the two half-plate inner liner pieces.

[0029] 2. A tortuous structure extends the gas escape path: The welding surface of this design follows the contours of the welding ring and the pointed ring, forming a naturally tortuous interface, rather than a traditional flat or single-sloping surface structure. When the gas cylinder is filled with gas, even under long-term pressure changes during filling and discharging cycles, gas attempting to escape from the weld must travel a longer path along the tortuous welding interface, significantly reducing the risk of leakage. This design effectively improves the sealing reliability of the inner liner, enabling it to withstand more filling and discharging tests and fully meeting the factory's requirements for service life and safety.

[0030] Example 2: See Figure 4 A laser-welded structure for a nylon cylinder liner differs from Example 1 in only one structural aspect: the right end face of the black half-piece liner is not planar. Specifically, when viewed from the perspective of a nylon cylinder liner cut along its axis (taking a single side wall structure after cutting), the right end face of the black half-piece liner is trapezoidal. The narrower base of the trapezoid faces right and the wider base faces left. The inner and outer waist surfaces of the trapezoid are parallel to the inner and outer waist surfaces of the pointed ring 4, and the narrower base completely overlaps with the left side of the welding ring 3.

[0031] The right end face of the black half-piece inner liner, the welding ring 3 and the pointed ring 4 are defined as the whole B. The left end face of the right transparent half-piece inner liner still has a groove B that is perfectly matched with the shape of the whole B. When splicing, the whole B can be precisely embedded in the groove B to ensure that the welding surface fits without gaps.

[0032] In this embodiment, the trapezoidal structure forms a multi-fold convoluted interface with the contours of the welding ring and the pointed ring. Compared with Embodiment 1, this further extends the gas escape path, which can more effectively block gas from penetrating from the welding interface, further reducing the risk of leakage. Moreover, the overall structural design does not change the total wall thickness of the gas cylinder (4.5cm), and still maintains the same welding strength and size adaptability as Embodiment 1.

[0033] Example 3: As Figure 5 As shown, a laser-welded structure for a nylon gas cylinder liner is shown. The core difference between this embodiment and embodiments 1 and 2 is that the welding ring and the pointed ring are no longer used. Instead, a composite structure of "threaded connection + laser welding" is used to achieve fixation.

[0034] The specific structure is as follows: the right end face of the black half-piece inner liner 1 is flat, and a circular threaded tube section 5 is integrally formed on the right end face; the inner diameter of the threaded tube section is the same as the inner diameter of the black half-piece inner liner, the axis coincides with the axis of the gas cylinder inner liner, the outer diameter is 2cm smaller than the outer diameter of the black half-piece inner liner, and the length along the axis of the gas cylinder is about 2cm (corresponding to the axial length of the welding ring in Example 1, ensuring structural coordination).

[0035] The left end face of the transparent half-piece inner liner is integrally provided with a threaded groove section 6 that is compatible with the aforementioned threaded pipe section. During assembly, the two are fastened by screwing together. After the threaded connection, the right end face of the black half-piece fits tightly with the left end face of the transparent half-piece. Then, laser circumferential welding is performed along the joint of the two end faces to complete the final fixation (the recommended thread pitch is 1.8cm, the tooth profile is triangular thread, which is suitable for the processing and sealing requirements of nylon material. The thread pitch can be adjusted according to actual needs).

[0036] The principle behind this embodiment's enhanced connection strength lies in the fact that the helical structure of the threaded connection significantly extends the gas escape path. Combined with laser welding to seal the end face joint, this creates a dual guarantee of "mechanical engagement + weld reinforcement." Compared to embodiments 1 and 2, this not only further reduces the risk of leakage, but the threaded connection can also effectively share the pressure load during charge-discharge cycles, reduce stress concentration in the weld, improve the overall structure's fatigue resistance, and better meet the requirements of high-frequency charge-discharge tests.

[0037] Example 4: A laser welding method for nylon gas cylinder liners, comprising the following steps: S1: Assemble the two half-piece inner liners into a complete nylon inner liner; S2: As Figure 6 As shown, for the following three types of nylon cylinder liners—a black half-piece liner with an integral A on the right end, a black half-piece liner with an integral B on the right end, and a black half-piece liner with a threaded pipe section on the right end—the laser beam is adjusted to be along the radial direction of the nylon cylinder. The laser beam passes through the transparent half-piece liner and irradiates the outer circumferential surface of the welding ring or the outer circumferential surface of the threaded pipe section. Since the welding ring and the threaded pipe section are both integrally formed with the black half-piece liner, they are both black. Under the irradiation time T (e.g., 3 minutes) of the laser beam, the outer circumferential surface of the welding ring or the threaded pipe section heats up, and the welding with the transparent half-piece liner is initially completed. The surface not directly irradiated by the laser beam is heated by the thermal conduction effect. S3: Rotate the nylon inner liner circumferentially by an angle R (e.g., 10 degrees) to ensure that the areas covered by the two laser beams overlap. Repeat step S2 until the nylon inner liner has been completely rotated 360 degrees and the full circumference irradiation has been completed. Then, the outer circumferential surface of the welding ring or threaded pipe section is completely welded to the transparent half-piece inner liner. Turn off the radial laser beam. S4: As Figure 7 As shown, for a nylon cylinder liner with an integral B on the right end of a black half-piece inner liner, the direction of the laser beam is adjusted to be perpendicular to both the outer waist surface of the pointed ring and the outer waist surface of the right end of the black half-piece inner liner (the laser beam is incident obliquely along the radial outer side of the cylinder); the laser beam passes through the transparent half-piece inner liner and irradiates the outer waist surface of the pointed ring and the outer waist surface of the right end of the black half-piece inner liner; under laser irradiation duration T (e.g., 3 min), the aforementioned waist surfaces heat up and initially complete the welding with the transparent half-piece inner liner; the surfaces not directly irradiated by the laser beam are heated by thermal conduction. S5: Rotate the nylon liner around its axis by an angle R (e.g., 10 degrees) to ensure that the areas covered by the two laser beams overlap. Repeat step S4 until the nylon liner has rotated 360 degrees and completed full circumferential irradiation. Then turn off the laser beam in that direction. S6: As Figure 8 As shown, for a nylon cylinder liner with an integral A on the right end of a black half-piece inner liner or a nylon cylinder liner with a threaded pipe section, the direction of the laser beam is adjusted to form a 45-degree angle with the right end face of the black half-piece inner liner (or the right end face of the threaded pipe section); the laser beam passes through the transparent half-piece inner liner and irradiates the right end face of the black half-piece inner liner (where it is attached to the transparent half-piece) or the right end face of the threaded pipe section (where it is attached to the transparent half-piece); under laser irradiation duration T (e.g., 3 minutes), the aforementioned end faces heat up, and the initial welding with the transparent half-piece inner liner is completed; the surfaces not directly irradiated by the laser beam are heated by thermal conduction. S7: Rotate the nylon liner around its axis by an angle R (e.g., 10 degrees) to ensure that the areas covered by the two laser beams overlap. Repeat step S6 until the nylon liner has rotated 360 degrees and completed full circumferential irradiation. Then turn off the laser beam.

[0038] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A laser-welded structure for a nylon gas cylinder liner, comprising two half-sheet liner pieces, one black on the left and one transparent on the right, characterized in that, The right end face of the black half-piece inner liner is either flat or non-flat; a welding ring is integrally provided on the right end face, the welding ring is circular and its axis coincides with the axis of the half-piece inner liner; a pointed ring is integrally provided on the right end face of the welding ring. When the right end face of the black half-piece inner liner is flat, the right end face of the black half-piece inner liner, the welding ring and the pointed ring form a whole A; the left end face of the transparent half-piece inner liner is provided with a groove A that fits the whole A. When the right end face of the black half-piece inner liner is not flat, the right end face of the black half-piece inner liner, the welding ring and the pointed ring form a whole B; the left end face of the transparent half-piece inner liner is provided with a groove B that fits the whole B; the two half-piece inner liners are laser welded into a complete nylon gas cylinder inner liner.

2. The laser-welded structure for a nylon gas cylinder liner according to claim 1, characterized in that, When the right end face of the black half-piece inner liner is not flat, observe the nylon cylinder inner liner by cutting it open along the axis of the nylon cylinder inner liner. On one side of the wall thickness, the right end face of the black half-piece inner liner is trapezoidal, with the narrower bottom edge facing right and the wider bottom edge facing left, and the narrower bottom edge completely coincides with the left side of the welding ring.

3. The laser-welded structure for a nylon gas cylinder liner according to claim 2, characterized in that, When the nylon cylinder liner is cut open along its axis, the pointed ring is an isosceles triangle on one side of the wall, with the base of the pointed ring completely coinciding with the right side of the welded ring. When the right end face of the black half-piece liner is trapezoidal, the inner and outer sides of the trapezoid are parallel to the inner and outer sides of the pointed ring, respectively.

4. The laser-welded structure for a nylon gas cylinder liner according to claim 1, characterized in that, When the nylon cylinder liner is cut open along its axis, the welded ring is closer to the inner wall of the half-piece liner and farther from the outer wall of the half-piece liner on one side.

5. A laser-welded structure for a nylon gas cylinder liner, comprising two half-sheet liner pieces, one black on the left and one transparent on the right, characterized in that... The right end face of the black half-piece inner liner is flat; an annular threaded tube segment is integrally provided on the right end face, the axis of the threaded tube segment coincides with the axis of the half-piece inner liner, the inner diameter is the same as the inner diameter of the black half-piece inner liner, and the outer diameter is smaller than the outer diameter of the black half-piece inner liner; the left end face of the transparent half-piece inner liner is integrally provided with a threaded groove segment adapted to the threaded tube segment. After threaded connection, the right end face of the black half-piece and the left end face of the transparent half-piece are tightly fitted together, and the two half-piece inner liners are laser welded into a complete nylon gas cylinder inner liner.

6. A laser welding method for a nylon gas cylinder liner, based on the laser welding structure for a nylon gas cylinder liner as described in claim 3 or 5, characterized in that, Includes the following steps: S1: Assemble the two half-piece inner liners into a complete nylon inner liner; S2: For the following three types of nylon cylinder liners—a black half-piece liner with an integral A on the right end, a black half-piece liner with an integral B on the right end, and a black half-piece liner with a threaded pipe section on the right end—adjust the direction of the laser beam to the radial direction of the nylon cylinder; the laser beam passes through the transparent half-piece liner and irradiates the outer circumferential surface of the welding ring or the outer circumferential surface of the threaded pipe section; under the irradiation time T of the laser beam, the outer circumferential surface of the welding ring or the threaded pipe section heats up, and the welding with the transparent half-piece liner is initially completed; the surface not directly irradiated by the laser beam is heated by the thermal conduction effect. S3: Rotate the nylon inner liner circumferentially by an angle R along the axis of the nylon inner liner to ensure that the areas covered by the two laser beams overlap. Repeat step S2 until the nylon inner liner has been completely rotated 360 degrees and the full circumference irradiation has been completed. Then, the outer circumferential surface of the welding ring or threaded pipe section is completely welded to the transparent half-piece inner liner. Turn off the radial laser beam. S4: For a nylon cylinder liner with an integral B on the right end of a black half-piece inner liner, the direction of the laser beam is adjusted to be perpendicular to both the outer waist surface of the pointed ring and the outer waist surface of the right end of the black half-piece inner liner; the laser beam passes through the transparent half-piece inner liner and irradiates the outer waist surface of the pointed ring and the outer waist surface of the right end of the black half-piece inner liner; under the laser irradiation duration T, the aforementioned waist surfaces heat up and initially complete the welding with the transparent half-piece inner liner; the surfaces not directly irradiated by the laser beam transfer heat through the thermal conduction effect. S5: Rotate the nylon liner around its axis by an angle R to ensure that the areas covered by the two laser beams overlap. Repeat step S4 until the nylon liner has rotated 360 degrees and completed full circumferential irradiation. Then turn off the laser beam in that direction. S6: For nylon cylinder liners with an integral A on the right end of a black half-piece inner liner or nylon cylinder liners with a threaded pipe section, adjust the direction of the laser beam to form a 45-degree angle with the right end face of the black half-piece inner liner; the laser beam passes through the transparent half-piece inner liner and irradiates the right end face of the black half-piece inner liner or the right end face of the threaded pipe section; under laser irradiation duration T, the aforementioned end face heats up and initially completes welding with the transparent half-piece inner liner; the surface not directly irradiated by the laser beam transfers heat through thermal conduction. S7: Rotate the nylon liner around its axis by an angle R to ensure that the areas covered by the two laser beams overlap. Repeat step S6 until the nylon liner has rotated 360 degrees and completed full circumferential irradiation. Then turn off the laser beam.

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